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Klein-Gordon Equation in Hydrodynamical Form
Wong, Cheuk-Yin
We follow and modify the Feshbach-Villars formalism by separating the Klein-Gordon equation into two coupled time-dependent Schroedinger equations for the particle and antiparticle wave functions with positive probability densities. We find that the equation of motion for the probability densities is in the form of relativistic hydrodynamics where various forces have their physical and classical counterparts. An additional element is the presence of the quantum stress tensor that depends on the derivatives of the amplitude of the wave function.
Klein-Gordon oscillator in Kaluza-Klein theory
NASA Astrophysics Data System (ADS)
Carvalho, Josevi; Carvalho, Alexandre M. de M.; Cavalcante, Everton; Furtado, Claudio
In this contribution we study the Klein-Gordon oscillator on the curved background within the Kaluza-Klein theory. The problem of the interaction between particles coupled harmonically with topological defects in Kaluza-Klein theory is studied. We consider a series of topological defects, then we treat the Klein-Gordon oscillator coupled to this background, and we find the energy levels and corresponding eigenfunctions in these cases. We show that the energy levels depend on the global parameters characterizing these spacetimes. We also investigate a quantum particle described by the Klein-Gordon oscillator interacting with a cosmic dislocation in Som-Raychaudhuri spacetime in the presence of homogeneous magnetic field in a Kaluza-Klein theory. In this case, the energy spectrum is determined, and we observe that these energy levels represent themselves as the sum of the terms related with Aharonov-Bohm flux and of the parameter associated to the rotation of the spacetime.
Quadratic nonlinear Klein-Gordon equation in one dimension
NASA Astrophysics Data System (ADS)
Hayashi, Nakao; Naumkin, Pavel I.
We study the initial value problem for the quadratic nonlinear Klein-Gordon equation vtt + v - vxx = λv2, t ∈ R, x ∈ R, with initial conditions v(0, x) = v0(x), vt(0, x) = v1(x), x ∈ R, where v0 and v1 are real-valued functions, λ ∈ R. Using the method of normal forms of Shatah ["Normal forms and quadratic nonlinear Klein-Gordon equations," Commun. Pure Appl. Math. 38, 685-696 (1985)], we obtain a sharp asymptotic behavior of small solutions without the condition of a compact support on the initial data, which was assumed in the previous work of J.-M. Delort ["Existence globale et comportement asymptotique pour l'équation de Klein-Gordon quasi-linéaire á données petites en dimension 1," Ann. Sci. Ec. Normale Super. 34(4), 1-61 (2001)].
Considerations on the hyperbolic complex Klein-Gordon equation
Ulrych, S.
This article summarizes and consolidates investigations on hyperbolic complex numbers with respect to the Klein-Gordon equation for fermions and bosons. The hyperbolic complex numbers are applied in the sense that complex extensions of groups and algebras are performed not with the complex unit, but with the product of complex and hyperbolic unit. The modified complexification is the key ingredient for the theory. The Klein-Gordon equation is represented in this framework in the form of the first invariant of the Poincare group, the mass operator, in order to emphasize its geometric origin. The possibility of new interactions arising from hyperbolic complex gauge transformations is discussed.
Numerical computation of travelling breathers in Klein Gordon chains
NASA Astrophysics Data System (ADS)
Sire, Yannick; James, Guillaume
We numerically study the existence of travelling breathers in Klein-Gordon chains, which consist of one-dimensional networks of nonlinear oscillators in an anharmonic on-site potential, linearly coupled to their nearest neighbors. Travelling breathers are spatially localized solutions having the property of being exactly translated by p sites along the chain after a fixed propagation time T (these solutions generalize the concept of solitary waves for which p=1). In the case of even on-site potentials, the existence of small amplitude travelling breathers superposed on a small oscillatory tail has been proved recently [G. James, Y. Sire, Travelling breathers with exponentially small tails in a chain of nonlinear oscillators, Commun. Math. Phys., 2005, in press (available online at http://www.springerlink.com)], the tail being exponentially small with respect to the central oscillation size. In this paper, we compute these solutions numerically and continue them into the large amplitude regime for different types of even potentials. We find that Klein-Gordon chains can support highly localized travelling breather solutions superposed on an oscillatory tail. We provide examples where the tail can be made very small and is difficult to detect at the scale of central oscillations. In addition, we numerically observe the existence of these solutions in the case of non-even potentials.
Dissipative effects in nonlinear Klein-Gordon dynamics
NASA Astrophysics Data System (ADS)
Plastino, A. R.; Tsallis, C.
We consider dissipation in a recently proposed nonlinear Klein-Gordon dynamics that admits exact time-dependent solutions of the power-law form e_qi(kx-wt) , involving the q-exponential function naturally arising within the nonextensive thermostatistics (e_qz \\equiv [1+(1-q)z]1/(1-q) , with e_1^z=ez ). These basic solutions behave like free particles, complying, for all values of q, with the de Broglie-Einstein relations p=\\hbar k , E=\\hbar ω and satisfying a dispersion law corresponding to the relativistic energy-momentum relation E2 = c^2p2 + m^2c4 . The dissipative effects explored here are described by an evolution equation that can be regarded as a nonlinear generalization of the celebrated telegraph equation, unifying within one single theoretical framework the nonlinear Klein-Gordon equation, a nonlinear Schrödinger equation, and the power-law diffusion (porous-media) equation. The associated dynamics exhibits physically appealing traveling solutions of the q-plane wave form with a complex frequency ω and a q-Gaussian square modulus profile.
Approximate symmetry and solutions of the nonlinear Klein-Gordon equation with a small parameter
NASA Astrophysics Data System (ADS)
Rahimian, Mohammad; Toomanian, Megerdich; Nadjafikhah, Mehdi
In this paper, the Lie approximate symmetry analysis is applied to investigate new solutions of the nonlinear Klein-Gordon equation with a small parameter. The nonlinear Klein-Gordon equation is used to model many nonlinear phenomena. The hyperbolic function method and Riccati equation method are employed to solve some of the obtained reduced ordinary differential equations. We construct new analytical solutions with a small parameter which is effectively obtained by the proposed method.
Hydrodynamic representation of the Klein-Gordon-Einstein equations in the weak field limit
NASA Astrophysics Data System (ADS)
Suárez, Abril; Chavanis, Pierre-Henri
Using a generalization of the Madelung transformation, we derive the hydrodynamic representation of the Klein-Gordon-Einstein equations in the weak field limit. We consider a complex self-interacting scalar field with an arbitrary potential of the form V(|ϕ|2). We compare the results with simplified models in which the gravitational potential is introduced by hand in the Klein-Gordon equation, and assumed to satisfy a (generalized) Poisson equation. Nonrelativistic hydrodynamic equations based on the Schrodinger-Poisson equations or on the Gross-Pitaevskii-Poisson equations are recovered in the limit c → +∞.
The statistical properties of Klein-Gordon oscillator in noncommutative space
Hassanabadi, H. Hosseini, S. S.; Boumali, A.; Zarrinkamar, S.
We study the relativistic spin-zero bosons influenced by the Klein-Gordon oscillator and an external magnetic field in noncommutative formulation. The problem is considered in two dimensions and is solved in an exact analytical manner. Having found the spectrum of the system, the statistical properties of an N-boson system are reported.
Group classification and conservation laws of the generalized Klein-Gordon-Fock equation
NASA Astrophysics Data System (ADS)
Muatjetjeja, B.
In the present paper, we perform Lie and Noether symmetries of the generalized Klein-Gordon-Fock equation. It is shown that the principal Lie algebra, which is one-dimensional, has several possible extensions. It is further shown that several cases arise for which Noether symmetries exist. Exact solutions for some cases are also obtained from the invariant solutions of the investigated equation.
Stability of Schwarzschild-AdS for the Spherically Symmetric Einstein-Klein-Gordon System
NASA Astrophysics Data System (ADS)
Holzegel, Gustav; Smulevici, Jacques
In this paper, we study the global behavior of solutions to the spherically symmetric coupled Einstein-Klein-Gordon (EKG) system in the presence of a negative cosmological constant. For the Klein-Gordon mass-squared satisfying a ≥ -1 (the Breitenlohner-Freedman bound being a > -9/8), we prove that the Schwarzschild-AdS spacetimes are asymptotically stable: Small perturbations of Schwarzschild-AdS initial data again lead to regular black holes, with the metric on the black hole exterior approaching, at an exponential rate, a Schwarzschild-AdS spacetime. The main difficulties in the proof arise from the lack of monotonicity for the Hawking mass and the asymptotically AdS boundary conditions, which render even (part of) the orbital stability intricate. These issues are resolved in a bootstrap argument on the black hole exterior, with the redshift effect and weighted Hardy inequalities playing the fundamental role in the analysis. Both integrated decay and pointwise decay estimates are obtained. As a corollary of our estimates on the Klein-Gordon field, one obtains in particular exponential decay in time of spherically-symmetric solutions to the linear Klein-Gordon equation on Schwarzschild-AdS.
Noncommutative Integrability of the Klein-Gordon and Dirac Equations in (2+1)-Dimensional Spacetime
NASA Astrophysics Data System (ADS)
Breev, A. I.; Shapovalov, A. V.
Noncommutative integration of the Klein-Gordon and Dirac relativistic wave equations in (2+1)-dimensional Minkowski space is considered. It is shown that for all non-Abelian subalgebras of the (2+1)-dimensional Poincaré algebra the condition of noncommutative integrability is satisfied.
What happens to linear properties as we move from the Klein-Gordon equation to the sine-Gordon equation
Kovalyov, Mikhail
In this article the sets of solutions of the sine-Gordon equation and its linearization the Klein-Gordon equation are discussed and compared. It is shown that the set of solutions of the sine-Gordon equation possesses a richer structure which partly disappears during linearization. Just like the solutions of the Klein-Gordon equation satisfy the linear superposition principle, the solutions of the sine-Gordon equation satisfy a nonlinear superposition principle.
The Klein-Gordon-Zakharov equations with the positive fractional power terms and their exact solutions
NASA Astrophysics Data System (ADS)
Zhang, Jinliang; Hu, Wuqiang; Ma, Yu
In this paper, the famous Klein-Gordon-Zakharov equations are firstly generalized, the new special types of Klein-Gordon-Zakharov equations with the positive fractional power terms (gKGZE) are presented. In order to derive the exact solutions of new special gKGZE, the subsidiary higher order ordinary differential equations (sub-ODEs) with the positive fractional power terms are introduced, and with the aids of the Sub-ODE, the exact solutions of three special types of the gKGZE are derived, which are the bell-type solitary wave solution, the algebraic solitary wave solution, the kink-type solitary wave solution and the sinusoidal traveling wave solution, provided that the coefficients of gKGZE satisfy certain constraint conditions.
Nonlinear self-adjointness and conservation laws of Klein-Gordon-Fock equation with central symmetry
NASA Astrophysics Data System (ADS)
Abdulwahhab, Muhammad Alim
The concept of nonlinear self-adjointness, introduced by Ibragimov, has significantly extends approaches to constructing conservation laws associated with symmetries since it incorporates the strict self-adjointness, the quasi self-adjointness as well as the usual linear self-adjointness. Using this concept, the nonlinear self-adjointness condition for the Klein-Gordon-Fock equation was established and subsequently used to construct simplified but infinitely many nontrivial and independent conserved vectors. The Noether's theorem was further applied to the Klein-Gordon-Fock equation to explore more distinct first integrals, result shows that conservation laws constructed through this approach are exactly the same as those obtained under strict self-adjointness of Ibragimov's method.
Dark soliton solutions of Klein-Gordon-Zakharov equation in (1+2) dimensions
NASA Astrophysics Data System (ADS)
Demiray, Seyma Tuluce; Bulut, Hasan
This study base on dark soliton solutions of Klein-Gordon-Zakharov (KGZ) equation in (1+2) dimensions. The generalized Kudryashov method (GKM) which is one of the analytical methods has been handled for finding exact solutions of KGZ equation in (1+2) dimensions. By using this method, dark soliton solutions of this equation have been obtained. Also, by using Mathematica Release 9, some graphical simulations were done to see the behavior of these solutions.
Solutions to the 1d Klein Gordon equation with cut-off Coulomb potentials
NASA Astrophysics Data System (ADS)
Hall, Richard L.
In a recent paper by Barton [G. Barton, J. Phys. A: Math. Gen. 40 (2007) 1011], the 1-dimensional Klein Gordon equation was solved analytically for the non-singular Coulomb-like potential V(|x|)=-α/(|x|+a). In the present Letter, these results are completely confirmed by a numerical formulation that also allows a solution for an alternative cut-off Coulomb potential V(|x|)=-α/|x|, |x|>a, and otherwise V(|x|)=-α/a.
Klein-Gordon equations for energy-momentum of the relativistic particle in rapidity space
Yamaleev, R. M.
The notion of four-rapidity is defined as a four-vector with one time-like and three space-like coordinates. It is proved, the energy and momentum defined in the space of four-rapidity obey Klein-Gordon equations constrained by the classical trajectory of a relativistic particle. It is shown, for small values of a proper mass influence of the constraint is weakened and the classical motion gains features of a wave motion.
Generalized Klein-Gordon and Dirac Equations from Nonlocal Kinetic Approach
NASA Astrophysics Data System (ADS)
El-Nabulsi, Rami Ahmad
In this note, I generalized the Klein-Gordon and the Dirac equations by using Suykens's nonlocal-in-time kinetic energy approach, which is motivated from Feynman's kinetic energy functional formalism where the position differences are shifted with respect to one another. I proved that these generalized equations are similar to those obtained in literature in the presence of minimal length based on the Quesne-Tkachuk algebra.
Relativistic superfluidity and vorticity from the nonlinear Klein-Gordon equation
NASA Astrophysics Data System (ADS)
Xiong, Chi; Good, Michael R. R.; Guo, Yulong; Liu, Xiaopei; Huang, Kerson
We investigate superfluidity, and the mechanism for creation of quantized vortices, in the relativistic regime. The general framework is a nonlinear Klein-Gordon equation in curved spacetime for a complex scalar field, whose phase dynamics gives rise to superfluidity. The mechanisms discussed are local inertial forces (Coriolis and centrifugal), and current-current interaction with an external source. The primary application is to cosmology, but we also discuss the reduction to the nonrelativistic nonlinear Schrödinger equation, which is widely used in describing superfluidity and vorticity in liquid helium and cold-trapped atomic gases.
First Order Solutions for Klein-Gordon-Maxwell Equations in a Specific Curved Manifold Case
Murariu, Gabriel
The aim of this paper is to study the SO(3,1)xU(1) gauge minimally coupled charged spinless field to a spherically symmetric curved space-time. It is derived the first order analytically approximation solution for the system of Klein-Gordon-Maxwell equations. Using these solutions, it evaluated the system electric charge density. The considered space -time manifold generalize an anterior studied one. The chosen space time configuration is of S diagonal type from the MAPLE GRTensor II metrics package.
Differential quadrature solution of nonlinear Klein-Gordon and sine-Gordon equations
NASA Astrophysics Data System (ADS)
Pekmen, B.; Tezer-Sezgin, M.
Differential quadrature method (DQM) is proposed to solve the one-dimensional quadratic and cubic Klein-Gordon equations, and two-dimensional sine-Gordon equation. We apply DQM in space direction and also blockwise in time direction. Initial and derivative boundary conditions are also approximated by DQM. DQM provides one to obtain numerical results with very good accuracy using considerably small number of grid points. Numerical solutions are obtained by using Gauss-Chebyshev-Lobatto (GCL) grid points in space intervals, and GCL grid points in each equally divided time blocks.
Length scale competition in nonlinear Klein-Gordon models: A collective coordinate approach
Cuenda, Sara; Sanchez, Angel
Working within the framework of nonlinear Klein-Gordon models as a paradigmatic example, we show that length scale competition, an instability of solitons subjected to perturbations of an specific length, can be understood by means of a collective coordinate approach in terms of soliton position and width. As a consequence, we provide a natural explanation of the phenomenon in much simpler terms than any previous treatment of the problem. Our technique allows us to study the existence of length scale competition in most soliton bearing nonlinear models and can be extended to coherent structures with more degrees of freedom.
Dispersion estimates for one-dimensional Schrödinger and Klein-Gordon equations revisited
NASA Astrophysics Data System (ADS)
Egorova, I. E.; Kopylova, E. A.; Marchenko, V. A.; Teschl, G.
It is shown that for a one-dimensional Schrödinger operator with a potential whose first moment is integrable the elements of the scattering matrix are in the unital Wiener algebra of functions with integrable Fourier transforms. This is then used to derive dispersion estimates for solutions of the associated Schrödinger and Klein-Gordon equations. In particular, the additional decay conditions are removed in the case where a resonance is present at the edge of the continuous spectrum. Bibliography: 29 titles.
Unstable Mode Solutions to the Klein-Gordon Equation in Kerr-anti-de Sitter Spacetimes
NASA Astrophysics Data System (ADS)
Dold, Dominic
For any cosmological constant {Λ = -3/ℓ2 < 0} and any {α < 9/4}, we find a Kerr-AdS spacetime {({M}, g_{KAdS})}, in which the Klein-Gordon equation {Box_{g_{KAdS}}ψ + α/ℓ2ψ = 0} has an exponentially growing mode solution satisfying a Dirichlet boundary condition at infinity. The spacetime violates the Hawking-Reall bound {r+2 > |a|ℓ}. We obtain an analogous result for Neumann boundary conditions if {5/4 < α < 9/4}. Moreover, in the Dirichlet case, one can prove that, for any Kerr-AdS spacetime violating the Hawking-Reall bound, there exists an open family of masses {α} such that the corresponding Klein-Gordon equation permits exponentially growing mode solutions. Our result adopts methods of Shlapentokh-Rothman developed in (Commun. Math. Phys. 329:859-891, 2014) and provides the first rigorous construction of a superradiant instability for negative cosmological constant.
Efficient and accurate numerical methods for the Klein-Gordon-Schroedinger equations
Bao, Weizhu . E-mail: email@example.com; Yang, Li . E-mail: email@example.com
In this paper, we present efficient, unconditionally stable and accurate numerical methods for approximations of the Klein-Gordon-Schroedinger (KGS) equations with/without damping terms. The key features of our methods are based on: (i) the application of a time-splitting spectral discretization for a Schroedinger-type equation in KGS (ii) the utilization of Fourier pseudospectral discretization for spatial derivatives in the Klein-Gordon equation in KGS (iii) the adoption of solving the ordinary differential equations (ODEs) in phase space analytically under appropriate chosen transmission conditions between different time intervals or applying Crank-Nicolson/leap-frog for linear/nonlinear terms for time derivatives. The numerical methods are either explicit or implicit but can be solved explicitly, unconditionally stable, and of spectral accuracy in space and second-order accuracy in time. Moreover, they are time reversible and time transverse invariant when there is no damping terms in KGS, conserve (or keep the same decay rate of) the wave energy as that in KGS without (or with a linear) damping term, keep the same dynamics of the mean value of the meson field, and give exact results for the plane-wave solution. Extensive numerical tests are presented to confirm the above properties of our numerical methods for KGS. Finally, the methods are applied to study solitary-wave collisions in one dimension (1D), as well as dynamics of a 2D problem in KGS.
Hadamard States for the Klein-Gordon Equation on Lorentzian Manifolds of Bounded Geometry
NASA Astrophysics Data System (ADS)
Gérard, Christian; Oulghazi, Omar; Wrochna, Michał
We consider the Klein-Gordon equation on a class of Lorentzian manifolds with Cauchy surface of bounded geometry, which is shown to include examples such as exterior Kerr, Kerr-de Sitter spacetime and the maximal globally hyperbolic extension of the Kerr outer region. In this setup, we give an approximate diagonalization and a microlocal decomposition of the Cauchy evolution using a time-dependent version of the pseudodifferential calculus on Riemannian manifolds of bounded geometry. We apply this result to construct all pure regular Hadamard states (and associated Feynman inverses), where regular refers to the state's two-point function having Cauchy data given by pseudodifferential operators. This allows us to conclude that there is a one-parameter family of elliptic pseudodifferential operators that encodes both the choice of (pure, regular) Hadamard state and the underlying spacetime metric.
Klein-Gordon equation and reflection of Alfven waves in nonuniform media
NASA Technical Reports Server (NTRS)
Musielak, Z. E.; Fontenla, J. M.; Moore, R. L.
A new analytical approach is presented for assessing the reflection of linear Alfven waves in smoothly nonuniform media. The general one-dimensional case in Cartesian coordinates is treated. It is shown that the wave equations, upon transformation into the form of the Klein-Gordon equation, display a local critical frequency for reflection. At any location in the medium, reflection becomes strong as the wave frequency descends past this characteristic frequency set by the local nonuniformity of the medium. This critical frequecy is given by the transformation as an explicit function of the Alfven velocity and its first and second derivatives, and hence as an explicit spatial function. The transformation thus directly yields, without solution of the wave equations, the location in the medium at which an Alfven wave of any given frequency becomes strongly reflected and has its propagation practically cut off.
Phase transition from the symmetry breaking of charged Klein-Gordon fields
NASA Astrophysics Data System (ADS)
Matos, T.; Castellanos, E.
We analyze the phase transition associated with the U(1) symmetry breaking of the complex Klein-Gordon (KG) equation with a Mexican-hat scalar field potential up to one loop in perturbations immersed in a thermal bath. We show that the KG equation reduces to a Gross-Pitaevskii like-equation (GP), which also contains the entire information of the phase transition. Indeed, the thermal bath contributions, together with the corresponding U(1) local symmetry, allow us to interpret the resulting GP equation as a charged and finite temperature version of the system. Finally, we obtain the hydrodynamics and consequently, the corresponding thermodynamics, and show that breakdown of the U(1) local symmetry of the KG field into the new version of the GP equation corresponds, under certain circumstances, to a phase transition of the gas into a condensate, superfluid, and/or superconductor.
Finite temperature Casimir effect for a massless fractional Klein-Gordon field with fractional Neumann conditions
Eab, C. H.; Lim, S. C.; Teo, L. P.
This paper studies the Casimir effect due to fractional massless Klein-Gordon field confined to parallel plates. A new kind of boundary condition called fractional Neumann condition which involves vanishing fractional derivatives of the field is introduced. The fractional Neumann condition allows the interpolation of Dirichlet and Neumann conditions imposed on the two plates. There exists a transition value in the difference between the orders of the fractional Neumann conditions for which the Casimir force changes from attractive to repulsive. Low and high temperature limits of Casimir energy and pressure are obtained. For sufficiently high temperature, these quantities are dominated by terms independent of the boundary conditions. Finally, validity of the temperature inversion symmetry for various boundary conditions is discussed.
On the Klein-Gordon equation using the dispersion relation of Doubly Special Relativity
NASA Astrophysics Data System (ADS)
Felipe, Yese J.
The theory of Doubly Special Relativity or Deformed Special Relativity (DSR), proposes that there is a maximum energy scale and a minimum length scale that is invariant for all observers. These maximum energy and minimum length correspond to the Planck energy and the Planck length, respectively. As a consequence, the dispersion relation is modified to be E2 =p2c2 +m2c4 + λE3 + ... Previous work has been done to express Quantum Mechanics using the dispersion relation of DSR. Solutions of the free particle, the harmonic oscillator, and the Hydrogen atom have been obtained from the DSR Schrodinger equation. We explore how the DSR Klein-Gordon equation can be consistently approximated in the non-relativistic limit in order to derive the DSR Schrodinger equation.
Three-dimensional Einstein-Klein-Gordon system in characteristic numerical relativity
Barreto, W.; Silva, A. da; Lehner, L.; Gomez, R.; Rosales, L.; Winicour, J.
We incorporate a massless scalar field into a three-dimensional code for the characteristic evolution of the gravitational field. The extended three-dimensional code for the Einstein-Klein-Gordon system is calibrated to be second-order convergent. It provides an accurate calculation of the gravitational and scalar radiation at infinity. As an application, we simulate the fully nonlinear evolution of an asymmetric scalar pulse of ingoing radiation propagating toward an interior Schwarzschild black hole and compute the backscattered scalar and gravitational outgoing radiation patterns. The amplitudes of the scalar and gravitational outgoing radiation modes exhibit the predicted power law scaling with respect to the amplitude of the initial data. For the scattering of an axisymmetric scalar field, the final ring down matches the complex frequency calculated perturbatively for the l=2 quasinormal mode.
Analyses of PION-40Ca Elastic Scattering Data Using the Klein-Gordon Equation
NASA Astrophysics Data System (ADS)
Shehadeh, Zuhair F.
The elastic scattering data for incident pion energies of 130, 163.3, 180, and 230 MeV on 40Ca have been analyzed using the full Klein-Gordon equation (KGE), as opposed to its approximate form which renders it to the format of a Schrödinger equation with an energy-dependent potential (RSE). Calculated angular distributions, using KGE and RSE, for all four cases are nearly the same up to about 70° but differ significantly at larger angles. To fit the large-angle data of 163.3 MeV, the nature of the old potential determined by using RSE needs to be revised. The new potentials in four cases are presented and they are compatible with those determined from the inverse scattering theory at a fixed energy in the surface region.
Dirac and Klein-Gordon particles in one-dimensional periodic potentials
NASA Astrophysics Data System (ADS)
Barbier, Michaël; Peeters, F. M.; Vasilopoulos, P.; Pereira, J. Milton, Jr.
We evaluate the dispersion relation for massless fermions, described by the Dirac equation, and for zero-spin bosons, described by the Klein-Gordon equation, moving in two dimensions and in the presence of a one-dimensional periodic potential. For massless fermions, the dispersion relation shows a zero gap for carriers with zero momentum in the direction parallel to the barriers in agreement with the well-known "Klein paradox." Numerical results for the energy spectrum and the density of states are presented. Those for fermions are appropriate to graphene in which carriers behave relativistically with the "light speed" replaced by the Fermi velocity. In addition, we evaluate the transmission through a finite number of barriers for fermions and zero-spin bosons and relate it with that through a superlattice.
Existence of global decaying solutions to the exterior problem for the Klein-Gordon equation with a nonlinear localized dissipation and a derivative nonlinearity
NASA Astrophysics Data System (ADS)
Nakao, Mitsuhiro
We prove the existence of global decaying solutions to the exterior problem for the Klein-Gordon equation with a nonlinear localized dissipation and a derivative nonlinearity. To derive the required estimates of solutions we employ a 'loan' method.
Lifespan estimates for the semi-linear Klein-Gordon equation with a quadratic potential in dimension one
NASA Astrophysics Data System (ADS)
Zhang, Qidi
We show for almost every m > 0, the solution to the semi-linear Klein-Gordon equation with a quadratic potential in dimension one, exists over a longer time interval than the one given by local existence theory, using the normal form method. By using an Lp -Lq estimate for eigenfunctions of the harmonic oscillator and by carefully analysis on the nonlinearity, we improve the result obtained by the author before.
Thermodynamic quantities for the Klein-Gordon equation with a linear plus inverse-linear potential: Biconfluent Heun functions
NASA Astrophysics Data System (ADS)
Arda, Altuğ; Tezcan, Cevdet; Sever, Ramazan
We study some thermodynamics quantities for the Klein-Gordon equation with a linear plus inverse-linear, scalar potential. We obtain the energy eigenvalues with the help of the quantization rule from the biconfluent Heun's equation. We use a method based on the Euler-MacLaurin formula to analytically compute the thermal functions by considering only the contribution of positive part of the spectrum to the partition function.
A local energy-preserving scheme for Klein-Gordon-Schrödinger equations
NASA Astrophysics Data System (ADS)
Cai, Jia-Xiang; Wang, Jia-Lin; Wang, Yu-Shun
A local energy conservation law is proposed for the Klein-Gordon-Schrödinger equations, which is held in any local time-space region. The local property is independent of the boundary condition and more essential than the global energy conservation law. To develop a numerical method preserving the intrinsic properties as much as possible, we propose a local energy-preserving (LEP) scheme for the equations. The merit of the proposed scheme is that the local energy conservation law can hold exactly in any time-space region. With the periodic boundary conditions, the scheme also possesses the discrete change and global energy conservation laws. A nonlinear analysis shows that the LEP scheme converges to the exact solutions with order 𝒪(τ2 + h2). The theoretical properties are verified by numerical experiments. Project supported by the National Natural Science Foundation of China (Grant Nos. 11201169, 11271195, and 41231173) and the Project of Graduate Education Innovation of Jiangsu Province, China (Grant No. CXLX13 366).
Huygens' principle for the Klein-Gordon equation in the de Sitter spacetime
Yagdjian, Karen
In this article we prove that the Klein-Gordon equation in the de Sitter spacetime obeys the Huygens' principle only if the physical mass m of the scalar field and the dimension n⩾ 2 of the spatial variable are tied by the equation m{sup 2}= (n{sup 2}−1)/4. Moreover, we define the incomplete Huygens' principle, which is the Huygens' principle restricted to the vanishing second initial datum, and then reveals that the massless scalar field in the de Sitter spacetime obeys the incomplete Huygens' principle and does not obey the Huygens' principle, for the dimensions n= 1, 3, only. Thus, in the de Sitter spacetime the existence of two different scalar fields (in fact, with m= 0 and m{sup 2}= (n{sup 2}−1)/4), which obey incomplete Huygens' principle, is equivalent to the condition n= 3, the spatial dimension of the physical world. In fact, Paul Ehrenfest in 1917 addressed the question: "Why has our space just three dimensions?". For n= 3 these two values of the mass are the endpoints of the so-called in quantum field theory the Higuchi bound. The value m{sup 2}= (n{sup 2}−1)/4 of the physical mass allows us also to obtain complete asymptotic expansion of the solution for the large time.
The Global Nonlinear Stability of Minkowski Space for Self-gravitating Massive Fields. The Wave-Klein-Gordon Model
NASA Astrophysics Data System (ADS)
LeFloch, Philippe G.; Ma, Yue
The Hyperboloidal Foliation Method (introduced by the authors in 2014) is extended here and applied to the Einstein equations of general relativity. Specifically, we establish the nonlinear stability of Minkowski spacetime for self-gravitating massive scalar fields, while existing methods only apply to massless scalar fields. First of all, by analyzing the structure of the Einstein equations in wave coordinates, we exhibit a nonlinear wave-Klein-Gordon model defined on a curved background, which is the focus of the present paper. For this model, we prove here the existence of global-in-time solutions to the Cauchy problem, when the initial data have sufficiently small Sobolev norms. A major difficulty comes from the fact that the class of conformal Killing fields of Minkowski space is significantly reduced in the presence of a massive scalar field, since the scaling vector field is not conformal Killing for the Klein-Gordon operator. Our method relies on the foliation (of the interior of the light cone) of Minkowski spacetime by hyperboloidal hypersurfaces and uses Lorentz-invariant energy norms. We introduce a frame of vector fields adapted to the hyperboloidal foliation and we establish several key properties: Sobolev and Hardy-type inequalities on hyperboloids, as well as sup-norm estimates, which correspond to the sharp time decay for the wave and the Klein-Gordon equations. These estimates allow us to control interaction terms associated with the curved geometry and the massive field by distinguishing between two levels of regularity and energy growth and by a successive use of our key estimates in order to close a bootstrap argument.
Classical and quantum field-theoretical approach to the non-linear q-Klein-Gordon equation
NASA Astrophysics Data System (ADS)
Plastino, A.; Rocca, M. C.
In the wake of efforts made Nobre and Rego-Monteiro in EPL, 97 (2012) 41001 and J. Math. Phys., 54 (2913) 103302, we extend them here by developing the conventional Lagrangian treatment of a classical field theory (FT) to the q-Klein-Gordon equation advanced in Phys. Rev. Lett., 106 (2011) 140601 and J. Math. Phys., 54 (2913) 103302 by the same authors, and the quantum theory corresponding to q=\\frac {3} {2} . This makes it possible to generate a putative conjecture regarding black matter. Our theory reduces to the usual FT for q→ 1 .
Klein-Gordon equation particles in exponential-type molecule potentials and their thermodynamic properties in D dimensions
NASA Astrophysics Data System (ADS)
Ikot, A. N.; Lutfuoglu, B. C.; Ngwueke, M. I.; Udoh, M. E.; Zare, S.; Hassanabadi, H.
In this paper we use the Nikiforov-Uvarov method to obtain the approximate solutions for the Klein-Gordon equation with the deformed five-parameter exponential-type potential (DFPEP) model. We also obtain solutions for the Schrödinger equation in the presence of DFPEP in non-relativistic limits. In addition, we calculate in the non-relativistic limits thermodynamics properties, such as vibrational mean energy U, free energy F and the specific heat capacity C. Special cases of the potential are also discussed.
Quantum Gravitational Corrections to the Real Klein-Gordon Field in the Presence of a Minimal Length
NASA Astrophysics Data System (ADS)
Moayedi, S. K.; Setare, M. R.; Moayeri, H.
The ( D+1)-dimensional ( β, β')-two-parameter Lorentz-covariant deformed algebra introduced by Quesne and Tkachuk (J. Phys., A Math. Gen. 39, 10909, 2006), leads to a nonzero minimal uncertainty in position (minimal length). The Klein-Gordon equation in a (3+1)-dimensional space-time described by Quesne-Tkachuk Lorentz-covariant deformed algebra is studied in the case where β'=2 β up to first order over deformation parameter β. It is shown that the modified Klein-Gordon equation which contains fourth-order derivative of the wave function describes two massive particles with different masses. We have shown that physically acceptable mass states can only exist for β<1/8m^{2c2} which leads to an isotropic minimal length in the interval 10-17 m<(Δ X i )0<10-15 m. Finally, we have shown that the above estimation of minimal length is in good agreement with the results obtained in previous investigations.
Hydrodynamic representation of the Klein-Gordon-Einstein equations in the weak field limit: General formalism and perturbations analysis
NASA Astrophysics Data System (ADS)
Suárez, Abril; Chavanis, Pierre-Henri
Using a generalization of the Madelung transformation, we derive the hydrodynamic representation of the Klein-Gordon-Einstein equations in the weak field limit. We consider a complex self-interacting scalar field with a λ |φ |4 potential. We study the evolution of the spatially homogeneous background in the fluid representation and derive the linearized equations describing the evolution of small perturbations in a static and in an expanding Universe. We compare the results with simplified models in which the gravitational potential is introduced by hand in the Klein-Gordon equation, and assumed to satisfy a (generalized) Poisson equation. Nonrelativistic hydrodynamic equations based on the Schrödinger-Poisson equations or on the Gross-Pitaevskii-Poisson equations are recovered in the limit c →+∞. We study the evolution of the perturbations in the matter era using the nonrelativistic limit of our formalism. Perturbations whose wavelength is below the Jeans length oscillate in time while perturbations whose wavelength is above the Jeans length grow linearly with the scale factor as in the cold dark matter model. The growth of perturbations in the scalar field model is substantially faster than in the cold dark matter model. When the wavelength of the perturbations approaches the cosmological horizon (Hubble length), a relativistic treatment is mandatory. In that case, we find that relativistic effects attenuate or even prevent the growth of perturbations. This paper exposes the general formalism and provides illustrations in simple cases. Other applications of our formalism will be considered in companion papers.
Complete set of commuting symmetry operators for the Klein-Gordon equation in generalized higher-dimensional Kerr-NUT-(A)dS spacetimes
Sergyeyev, Artur; Krtous, Pavel
We consider the Klein-Gordon equation in generalized higher-dimensional Kerr-NUT-(A)dS spacetime without imposing any restrictions on the functional parameters characterizing the metric. We establish commutativity of the second-order operators constructed from the Killing tensors found in [J. High Energy Phys. 02 (2007) 004] and show that these operators, along with the first-order operators originating from the Killing vectors, form a complete set of commuting symmetry operators (i.e., integrals of motion) for the Klein-Gordon equation. Moreover, we demonstrate that the separated solutions of the Klein-Gordon equation obtained in [J. High Energy Phys. 02 (2007) 005] are joint eigenfunctions for all of these operators. We also present an explicit form of the zero mode for the Klein-Gordon equation with zero mass. In the semiclassical approximation we find that the separated solutions of the Hamilton-Jacobi equation for geodesic motion are also solutions for a set of Hamilton-Jacobi-type equations which correspond to the quadratic conserved quantities arising from the above Killing tensors.
Asymptotic iteration method for analytical solution of Klein-Gordon equation for trigonometric Pӧschl-Teller potential in D-dimensions
NASA Astrophysics Data System (ADS)
Arya Nugraha, Dewanta; Suparmi, A.; Cari, C.; Nur Pratiwi, Beta
Klein-Gordon equation for Trigonometric Pöschl-Teller Potential in D-dimensions was obtained within framework of a centrifugal term approximation. Asymptotic iteration method was used to obtain the relativistic energy spectrum and wave functions. The value of relativistic energy was calculated numerically and the results have shown that in higher dimension the energy level is increased with positive energy states. The wave functions were expressed in hypergeometric term.
Analytical and numerical validation for solving the fractional Klein-Gordon equation using the fractional complex transform and variational iteration methods
NASA Astrophysics Data System (ADS)
Khader, M. M.; Adel, M.
In this paper, we implement the fractional complex transform method to convert the nonlinear fractional Klein-Gordon equation (FKGE) to an ordinary differential equation. We use the variational iteration method (VIM) to solve the resulting ODE. The fractional derivatives are presented in terms of the Caputo sense. Some numerical examples are presented to validate the proposed techniques. Finally, a comparison with the numerical solution using Runge-Kutta of order four is given.
Geometric properties of the Kantowski-Sachs and Bianchi-type Killing algebra in relation to a Klein-Gordon equation
NASA Astrophysics Data System (ADS)
Jamal, Sameerah; Shabbir, Ghulam
We study the geometric properties of generators for the Klein-Gordon equation in Kantowski-Sachs and certain Bianchi-type spaces. Several versions of the Klein-Gordon equation are derived from its dependence on a potential function. The criteria for different versions of the (1+3) Klein-Gordon equation originates from analyzing three sources, viz. through generators that are identically the Killing algebra, or with the Killing vector fields that are recast into linear combinations and thirdly, real sub-algebras within the conformal algebra. In turn, these equations admit a catalogue of infinitesimal symmetries that are equivalent to the corresponding Killing vector fields in Kantowski-Sachs, Bianchi type III, IX, VIII, VI0 and VII0 space-times, with the exception of a linear vector W=upartialu in every case. The sheer number of results are displayed in appropriate tables. Subsequently, in application, we derive some Noetherian conservation laws and identify some exact solutions by quadratures.
Wave-turbulence description of interacting particles: Klein-Gordon model with a Mexican-hat potential.
Gallet, Basile; Nazarenko, Sergey; Dubrulle, Bérengère
In field theory, particles are waves or excitations that propagate on the fundamental state. In experiments or cosmological models, one typically wants to compute the out-of-equilibrium evolution of a given initial distribution of such waves. Wave turbulence deals with out-of-equilibrium ensembles of weakly nonlinear waves, and is therefore well suited to address this problem. As an example, we consider the complex Klein-Gordon equation with a Mexican-hat potential. This simple equation displays two kinds of excitations around the fundamental state: massive particles and massless Goldstone bosons. The former are waves with a nonzero frequency for vanishing wave number, whereas the latter obey an acoustic dispersion relation. Using wave-turbulence theory, we derive wave kinetic equations that govern the coupled evolution of the spectra of massive and massless waves. We first consider the thermodynamic solutions to these equations and study the wave condensation transition, which is the classical equivalent of Bose-Einstein condensation. We then focus on nonlocal interactions in wave-number space: we study the decay of an ensemble of massive particles into massless ones. Under rather general conditions, these massless particles accumulate at low wave number. We study the dynamics of waves coexisting with such a strong condensate, and we compute rigorously a nonlocal Kolmogorov-Zakharov solution, where particles are transferred nonlocally to the condensate, while energy cascades towards large wave numbers through local interactions. This nonlocal cascading state constitutes the intermediate asymptotics between the initial distribution of waves and the thermodynamic state reached in the long-time limit.
Domain wall and bifurcation analysis of the Klein-Gordon Zakharov equation in (1+2)-dimensions with power law nonlinearity.
Song, Ming; Ahmed, Bouthina S; Zerrad, Essaid; Biswas, Anjan
This paper studies the Klein-Gordon Zakharov equation with power law nonlinearity in (1+2)-dimensions. The ansatz method will be applied to obtain the 1-soliton solution, also known as domain wall solution, along with several constraint conditions that naturally fall out. Subsequently, the bifurcation analysis is carried out where the phase portrait is given. Additionally, this analysis leads to several solutions to the equation with the traveling wave scheme. This gives soliton solution as well as singular periodic solutions. Finally, the numerical simulations for the domain wall solution were obtained where the finite difference scheme is applied.
The Klein-Gordon-Fock equation in the curved spacetime of the Kerr-Newman (anti) de Sitter black hole
NASA Astrophysics Data System (ADS)
Kraniotis, G. V.
Exact solutions of the Klein-Gordon-Fock (KGF) general relativistic equation that describe the dynamics of a massive, electrically charged scalar particle in the curved spacetime geometry of an electrically charged, rotating Kerr-Newman-(anti) de Sitter black hole are investigated. In the general case of a rotating, charged, cosmological black hole the solution of the KGF equation with the method of separation of variables results in Fuchsian differential equations for the radial and angular parts which for most of the parameter space contain more than three finite singularities and thereby generalise the Heun differential equations. For particular values of the physical parameters (i.e. mass of the scalar particle) these Fuchsian equations reduce to the case of the Heun equation and the closed form analytic solutions we derive are expressed in terms of Heun functions. For other values of the parameters some of the extra singular points are false singular points. We derive the conditions on the coefficients of the generalised Fuchsian equation such that a singular point is a false point. In such a case the exact solution of the Fuchsian equation can in principle be simplified and expressed in terms of Heun functions. This is the generalisation of the case of a Heun equation with a false singular point in which the exact solution of Heun's differential equation is expressed in terms of Gauß hypergeometric function. We also derive the exact solutions of the radial and angular equations for a charged massive scalar particle in the Kerr-Newman spacetime. The analytic solutions are expressed in terms of confluent Heun functions. Moreover, we derived the constraints on the parameters of the theory such that the solution simplifies and expressed in terms of confluent Kummer hypergeometric functions. We also investigate the radial solutions in the KN case in the regions near the event horizon and far from the black hole. Finally, we construct several expansions of the
Bound States of the Klein-Gordon Equation for Vector and Scalar General HULTHÉN-TYPE Potentials in D-Dimension
NASA Astrophysics Data System (ADS)
Ikhdair, Sameer M.
We solve the Klein-Gordon equation in any D-dimension for the scalar and vector general Hulthén-type potentials with any l by using an approximation scheme for the centrifugal potential. Nikiforov-Uvarov method is used in the calculations. We obtain the bound-state energy eigenvalues and the corresponding eigenfunctions of spin-zero particles in terms of Jacobi polynomials. The eigenfunctions are physical and the energy eigenvalues are in good agreement with those results obtained by other methods for D = 1 and 3 dimensions. Our results are valid for q = 1 value when l ≠ 0 and for any q value when l = 0 and D = 1 or 3. The s-wave (l = 0) binding energies for a particle of rest mass m0 = 1 are calculated for the three lower-lying states (n = 0, 1, 2) using pure vector and pure scalar potentials.
Bound States for a Klein-Gordon Particle in Vector Plus Scalar Generalized Hulthén Potentials in D Dimensions
NASA Astrophysics Data System (ADS)
Aggoun, L.; Benamira, F.; Guechi, L.; Sadoun, M. A.
The Green's function associated with a Klein-Gordon particle moving in a D-dimensional space under the action of vector plus scalar q-deformed Hulthén potentials is constructed by path integration for {q ≥ 1} and {1/α ln q < r < infty}. An appropriate approximation of the centrifugal potential term and the technique of space-time transformation are used to reduce the path integral for the generalized Hulthén potentials into a path integral for q-deformed Rosen-Morse potential. Explicit path integration leads to the radial Green's function for any l state in closed form. The energy spectrum and the correctly normalized wave functions, for a state of orbital quantum number {l ≥ 0}, are obtained. Eventually, the vector q-deformed Hulthén potential and the Coulomb potentials in D dimensions are considered as special cases.
Exact Solutions in the Invariant Manifolds of the Generalized Integrable Hénon-Heiles System and Exact Traveling Wave Solutions of Klein-Gordon-Schrödinger Equations
NASA Astrophysics Data System (ADS)
Li, Jibin
In this paper, we consider the exact explicit solutions for the famous generalized Hénon-Heiles (H-H) system. Corresponding to the three integrable cases, on the basis of the investigation of the dynamical behavior and level curves of the planar dynamical systems, we find all possible explicit exact parametric representations of solutions in the invariant manifolds of equilibrium points in the four-dimensional phase space. These solutions contain quasi-periodic solutions, homoclinic solutions, periodic solutions as well as blow-up solutions. Therefore, we answer the question: what are the flows in the center manifolds and homoclinic manifolds of the generalized Hénon-Heiles (H-H) system. As an application of the above results, we consider the traveling wave solutions for the coupled (n + 1)-dimensional Klein-Gordon-Schrödinger Equations with quadratic power nonlinearity.
Supersymmetric approach to exact solutions of (1+ 1)-dimensional time-independent Klein-Gordon equation: Application to a position-dependent mass and a PT-symmetric vector potential
NASA Astrophysics Data System (ADS)
Zaghou, N.; Benamira, F.; Guechi, L.
Rigorous use of the SUSYQM approach applied for the Klein-Gordon equation with scalar and vector potentials is discussed. The method is applied to solve exactly, for bound states, two models with position-dependent masses and PT-symmetric vector potentials, depending on some parameters. The necessary conditions on the parameters to get physical solutions are described. Some special cases are also derived by adjusting the parameters of the models.
Temperature-dependent thermal conductivities of one-dimensional nonlinear Klein-Gordon lattices with a soft on-site potential.
Yang, Linlin; Li, Nianbei; Li, Baowen
The temperature-dependent thermal conductivities of one-dimensional nonlinear Klein-Gordon lattices with soft on-site potential (soft-KG) are investigated systematically. Similarly to the previously studied hard-KG lattices, the existence of renormalized phonons is also confirmed in soft-KG lattices. In particular, the temperature dependence of the renormalized phonon frequency predicted by a classical field theory is verified by detailed numerical simulations. However, the thermal conductivities of soft-KG lattices exhibit the opposite trend in temperature dependence in comparison with those of hard-KG lattices. The interesting thing is that the temperature-dependent thermal conductivities of both soft- and hard-KG lattices can be interpreted in the same framework of effective phonon theory. According to the effective phonon theory, the exponents of the power-law dependence of the thermal conductivities as a function of temperature are only determined by the exponents of the soft or hard on-site potentials. These theoretical predictions are consistently verified very well by extensive numerical simulations.
Discrete nonlinear Schrödinger approximation of a mixed Klein Gordon/Fermi Pasta Ulam chain: Modulational instability and a statistical condition for creation of thermodynamic breathers
NASA Astrophysics Data System (ADS)
Johansson, Magnus
We analyze certain aspects of the classical dynamics of a one-dimensional discrete nonlinear Schrödinger model with inter-site as well as on-site nonlinearities. The equation is derived from a mixed Klein-Gordon/Fermi-Pasta-Ulam chain of anharmonic oscillators coupled with anharmonic inter-site potentials, and approximates the slow dynamics of the fundamental harmonic of discrete small-amplitude modulational waves. We give explicit analytical conditions for modulational instability of travelling plane waves, and find in particular that sufficiently strong inter-site nonlinearities may change the nature of the instabilities from long-wavelength to short-wavelength perturbations. Further, we describe thermodynamic properties of the model using the grand-canonical ensemble to account for two conserved quantities: norm and Hamiltonian. The available phase space is divided into two separated parts with qualitatively different properties in thermal equilibrium: one part corresponding to a normal thermalized state with exponentially small probabilities for large-amplitude excitations, and another part typically associated with the formation of high-amplitude localized excitations, interacting with an infinite-temperature phonon bath. A modulationally unstable travelling wave may exhibit a transition from one region to the other as its amplitude is varied, and thus modulational instability is not a sufficient criterion for the creation of persistent localized modes in thermal equilibrium. For pure on-site nonlinearities the created localized excitations are typically pinned to particular lattice sites, while for significant inter-site nonlinearities they become mobile, in agreement with well-known properties of localized excitations in Fermi-Pasta-Ulam-type chains.
Comment on: "Exact bound state solutions of the s-wave Klein Gordon equation with the generalized Hulthén potential" [Phys. Lett. A 331 (2004) 374
NASA Astrophysics Data System (ADS)
Benamira, F.; Guechi, L.; Zouache, A.
The supersymmetric quantum mechanical method employed by Gang Chen and co-workers to solve the problem of the s states of a Klein Gordon particle under the action of generalized vector plus scalar Hulthén-type potentials is shown inadequate since only one of their solutions remains valid for q⩾1 and 1αlnq
A uniformly accurate multiscale time integrator spectral method for the Klein-Gordon-Zakharov system in the high-plasma-frequency limit regime
NASA Astrophysics Data System (ADS)
Bao, Weizhu; Zhao, Xiaofei
A multiscale time integrator sine pseudospectral (MTI-SP) method is presented for discretizing the Klein-Gordon-Zakharov (KGZ) system with a dimensionless parameter 0 < ε ≤ 1, which is inversely proportional to the plasma frequency. In the high-plasma-frequency limit regime, i.e. 0 < ε ≪ 1, the solution of the KGZ system propagates waves with amplitude at O (1) and wavelength at O (ε2) in time and O (1) in space, which causes significantly numerical burdens due to the high oscillation in time. The main idea of the numerical method is to carry out a multiscale decomposition by frequency (MDF) to the electric field component of the solution at each time step and then apply the sine pseudospectral discretization for spatial derivatives followed by using the exponential wave integrator in phase space for integrating the MDF and the equation of the ion density component. The method is explicit and easy to be implemented. Extensive numerical results show that the MTI-SP method converges uniformly and optimally in space with exponential convergence rate if the solution is smooth, and uniformly in time with linear convergence rate at O (τ) for ε ∈ (0 , 1 ] with τ time step size and optimally with quadratic convergence rate at O (τ2) in the regime when either ε = O (1) or 0 < ε ≤ τ. Thus the meshing strategy requirement (or ε-scalability) of the MTI-SP for the KGZ system in the high-plasma-frequency limit regime is τ = O (1) and h = O (1) for 0 < ε ≪ 1, which is significantly better than classical methods in the literatures. Finally, we apply the MTI-SP method to study the convergence rates of the KGZ system to its limiting models in the high-plasma-frequency limit and the interactions of bright solitons of the KGZ system, and to identify certain parameter regimes that the solution of the KGZ system will be blow-up in one dimension.
Any l-state improved quasi-exact analytical solutions of the spatially dependent mass Klein-Gordon equation for the scalar and vector Hulthén potentials
NASA Astrophysics Data System (ADS)
Ikhdair, Sameer M.; Sever, Ramazan
We present a new approximation scheme for the centrifugal term to obtain a quasi-exact analytical bound state solution within the framework of the position-dependent effective mass radial Klein-Gordon equation with the scalar and vector Hulthén potentials in any arbitrary D dimension and orbital angular momentum quantum numbers l. The Nikiforov-Uvarov (NU) method is used in the calculations. The relativistic real energy levels and corresponding eigenfunctions for the bound states with different screening parameters have been given in a closed form. It is found that the solutions in the case of constant mass and in the case of s-wave (l=0) are identical with the ones obtained in the literature.
A Klein-Gordon acoustic theory
Anno, P.D.
Geophysicists do not associate traveltime variation with density variation in acoustic or elastic wavefield interpretation. Rather, given a constant index of refraction, density variation within the medium of propagation is associated only with amplitudes. This point of view prevails because density does not occur as a variable in classical results such as Snell's Law or the eikonal equation. Nevertheless, in this paper I predict, analytically, a continuum of density effects on acoustic wavefields-including a dispersive traveltime delay when density variation is rapid. I also examine the ability of a common imaging algorithm to cope with this time delay.
A Klein-Gordon acoustic theory
Anno, Phil D.
Geophysicists do not associate traveltime variation with density variation in acoustic or elastic wavefield interpretation. Rather, given a constant index of refraction, density variation within the medium of propagation is associated only with amplitudes. This point of view prevails because density does not occur as a variable in classical results such as Snell`s Law or the eikonal equation. Nevertheless, in this paper I predict, analytically, a continuum of density effects on acoustic wavefields-including a dispersive traveltime delay when density variation is rapid. I also examine the ability of a common imaging algorithm to cope with this time delay.
Klein-Gordon Fields and Bose-Einstein Condensates: Thermal Bath Contributions
NASA Astrophysics Data System (ADS)
Castellanos, E.; Matos, T.
We analyze the consequences caused by a thermal bath upon the properties associated to the symmetry breaking of scalar fields with one-loop correction potential. Concerning the nonrelativistic regime associated with the aforementioned system, we calculate the shift in the condensation temperature caused by the thermal bath, assuming a harmonic oscillator type potential. We prove that the shift in the condensation temperature depends on the associated scale of the system. In addition, we obtain bounds associated to the scale that could lead to relevant corrections on the condensation temperature under typical conditions.
Kink topology control by high-frequency external forces in nonlinear Klein-Gordon models.
Alvarez-Nodarse, R; Quintero, N R; Mertens, F G
A method of averaging is applied to study the dynamics of a kink in the damped double sine-Gordon equation driven by both external (nonparametric) and parametric periodic forces at high frequencies. This theoretical approach leads to the study of a double sine-Gordon equation with an effective potential and an effective additive force. Direct numerical simulations show how the appearance of two connected π kinks and of an individual π kink can be controlled via the frequency. An anomalous negative mobility phenomenon is also predicted by theory and confirmed by simulations of the original equation.
Aharonov-Bohm Effect and High-Momenta Inverse Scattering for the Klein-Gordon Equation
NASA Astrophysics Data System (ADS)
Ballesteros, Miguel; Weder, Ricardo
We analyze spin-0 relativistic scattering of charged particles propagating in the exterior, $\\Lambda \\subset \\mathbb{R}^3$, of a compact obstacle $K \\subset \\mathbb{R}^3$. The connected components of the obstacle are handlebodies. The particles interact with an electro-magnetic field in $\\Lambda$ and an inaccessible magnetic field localized in the interior of the obstacle (through the Aharonov-Bohm effect). We obtain high-momenta estimates, with error bounds, for the scattering operator that we use to recover physical information: We give a reconstruction method for the electric potential and the exterior magnetic field and prove that, if the electric potential vanishes, circulations of the magnetic potential around handles (or equivalently, by Stokes' theorem, magnetic fluxes over transverse sections of handles) of the obstacle can be recovered, modulo $2 \\pi$. We additionally give a simple formula for the high-momenta limit of the scattering operator in terms of certain magnetic fluxes, in the absence of electric potential. If the electric potential does not vanish, the magnetic fluxes on the handles above referred can be only recovered modulo $\\pi$ and the simple expression of the high-momenta limit of the scattering operator does not hold true.
Nonlinear instabilities of multi-site breathers in Klein-Gordon lattices
Cuevas-Maraver, Jesus; Kevrekidis, Panayotis G.; Pelinovsky, Dmitry E.
Here, we explore the possibility of multi-site breather states in a nonlinear Klein–Gordon lattice to become nonlinearly unstable, even if they are found to be spectrally stable. The mechanism for this nonlinear instability is through the resonance with the wave continuum of a multiple of an internal mode eigenfrequency in the linearization of excited breather states. For the nonlinear instability, the internal mode must have its Krein signature opposite to that of the wave continuum. This mechanism is not only theoretically proposed, but also numerically corroborated through two concrete examples of the Klein–Gordon lattice with a soft (Morse) and amore » hard (Φ4) potential. Compared to the case of the nonlinear Schrödinger lattice, the Krein signature of the internal mode relative to that of the wave continuum may change depending on the period of the multi-site breather state. For the periods for which the Krein signatures of the internal mode and the wave continuum coincide, multi-site breather states are observed to be nonlinearly stable.« less
Nonlinear instabilities of multi-site breathers in Klein-Gordon lattices
Cuevas-Maraver, Jesus; Kevrekidis, Panayotis G.; Pelinovsky, Dmitry E.
Here, we explore the possibility of multi-site breather states in a nonlinear Klein–Gordon lattice to become nonlinearly unstable, even if they are found to be spectrally stable. The mechanism for this nonlinear instability is through the resonance with the wave continuum of a multiple of an internal mode eigenfrequency in the linearization of excited breather states. For the nonlinear instability, the internal mode must have its Krein signature opposite to that of the wave continuum. This mechanism is not only theoretically proposed, but also numerically corroborated through two concrete examples of the Klein–Gordon lattice with a soft (Morse) and a hard (Φ4) potential. Compared to the case of the nonlinear Schrödinger lattice, the Krein signature of the internal mode relative to that of the wave continuum may change depending on the period of the multi-site breather state. For the periods for which the Krein signatures of the internal mode and the wave continuum coincide, multi-site breather states are observed to be nonlinearly stable.
Perturbed Coulomb potentials in the Klein-Gordon equation via the asymptotic iteration method
Barakat, T.
The asymptotic iteration method is used to construct the exact energy eigenvalues for a Lorentz vector or a Lorentz scalar, and an equally mixed Lorentz vector and Lorentz scalar Coulombic potentials. Highly accurate and rapidly converging ground-state energies for Lorentz vector Coulomb with a Lorentz vector or a Lorentz scalar linear potential, V(r)=-{lambda}{sub 1}/r+krandV(r)=-{lambda}{sub 1}/randW(r)=kr, respectively, are obtained.
Accelerated Cartesian expansion (ACE) based framework for the rapid evaluation of diffusion, lossy wave, and Klein-Gordon potentials
Baczewski, Andrew David; Vikram, Melapudi; Shanker, Balasubramaniam; ...
Diffusion, lossy wave, and Klein–Gordon equations find numerous applications in practical problems across a range of diverse disciplines. The temporal dependence of all three Green's functions are characterized by an infinite tail. This implies that the cost complexity of the spatio-temporal convolutions, associated with evaluating the potentials, scales as O(Ns2Nt2), where Ns and Nt are the number of spatial and temporal degrees of freedom, respectively. In this paper, we discuss two new methods to rapidly evaluate these spatio-temporal convolutions by exploiting their block-Toeplitz nature within the framework of accelerated Cartesian expansions (ACE). The first scheme identifies a convolution relation inmore » time amongst ACE harmonics and the fast Fourier transform (FFT) is used for efficient evaluation of these convolutions. The second method exploits the rank deficiency of the ACE translation operators with respect to time and develops a recursive numerical compression scheme for the efficient representation and evaluation of temporal convolutions. It is shown that the cost of both methods scales as O(NsNtlog2Nt). Furthermore, several numerical results are presented for the diffusion equation to validate the accuracy and efficacy of the fast algorithms developed here.« less
Accelerated Cartesian expansion (ACE) based framework for the rapid evaluation of diffusion, lossy wave, and Klein-Gordon potentials
Baczewski, Andrew David; Vikram, Melapudi; Shanker, Balasubramaniam; Kempel, Leo
Diffusion, lossy wave, and Klein–Gordon equations find numerous applications in practical problems across a range of diverse disciplines. The temporal dependence of all three Green's functions are characterized by an infinite tail. This implies that the cost complexity of the spatio-temporal convolutions, associated with evaluating the potentials, scales as O(Ns2Nt2), where Ns and Nt are the number of spatial and temporal degrees of freedom, respectively. In this paper, we discuss two new methods to rapidly evaluate these spatio-temporal convolutions by exploiting their block-Toeplitz nature within the framework of accelerated Cartesian expansions (ACE). The first scheme identifies a convolution relation in time amongst ACE harmonics and the fast Fourier transform (FFT) is used for efficient evaluation of these convolutions. The second method exploits the rank deficiency of the ACE translation operators with respect to time and develops a recursive numerical compression scheme for the efficient representation and evaluation of temporal convolutions. It is shown that the cost of both methods scales as O(NsNtlog2Nt). Furthermore, several numerical results are presented for the diffusion equation to validate the accuracy and efficacy of the fast algorithms developed here.
Separability of Hamilton-Jacobi and Klein-Gordon equations in general Kerr-NUT-AdS spacetimes
NASA Astrophysics Data System (ADS)
Frolov, Valeri P.; Krtous, Pavel; Kubiznák, David
We demonstrate the separability of the Hamilton-Jacobi and scalar field equations in general higher dimensional Kerr-NUT-AdS spacetimes. No restriction on the parameters characterizing these metrics is imposed.
Unstructured High-Order Galerkin-Temporal- Boundary Methods for the Klein-Gordon Equation with Non-Reflecting Boundary Conditions
Alex (Booga) and Jenna (Bean) who always make coming home the highlight of my day...BeE, Dx = Ne∧ e=1 Dex, Dy = Ne∧ e=1 Dey Lxx = Ne∧ e=1 Lexx, Lyy = Ne∧ e=1 Leyy, Lxy = Ne∧ e=1 Lexy, Lyx = Ne∧ e=1 Leyx, M b = Nb∧ b=1 mb, Db = Nb∧ b=1...Ωe ψi ∂ψj ∂x dΩe Dey ,ij = ∫ Ωe ψi ∂ψj ∂y dΩe L e xx,ij = ∫ Ωe ∂ψi ∂x ∂ψj ∂x dΩe L e yy,ij = ∫ Ωe ∂ψi ∂y ∂ψj ∂y dΩe Lexy,ij = ∫ Ωe ∂ψi ∂y ∂ψj ∂x
Particle beams guided by electromagnetic vortices: new solutions of the Lorentz, Schrödinger, Klein-Gordon, and Dirac equations.
Bialynicki-Birula, Iwo
It is shown that electromagnetic vortices can act as beam guides for charged particles. The confinement in the transverse directions is due to the rotation of the electric and magnetic fields around the vortex line. A large class of exact solutions describing various types of relativistic beams formed by an electromagnetic wave with a simple vortex line is found both in the classical and in the quantum case. In the second case, the motion in the transverse direction is fully quantized. Particle trajectories trapped by a vortex are very similar to those in a helical undulator.
Cook, Richard D.
The ParaDIS_lib software is a project that is funded by the DOE ASC Program. Its purpose is to provide visualization and analysis capabilities for the existing ParaDIS parallel dislocation dynamics simulation code.
Hawking Temperature of an Arbitrarily Accelerating Black Hole
NASA Astrophysics Data System (ADS)
Pan, Wei-Zhen; Liu, Wei
Hawking temperature of an arbitrarily accelerating black hole with electric and magnetic charges are obtained based on the Klein-Gordon equation with a correct-dimension new tortoise coordinate transformation.
Noncommutativity and the Friedmann Equations
Sabido, M.; Socorro, J.; Guzman, W.
In this paper we study noncommutative scalar field cosmology, we find the noncommutative Friedmann equations as well as the noncommutative Klein-Gordon equation, interestingly the noncommutative contributions are only present up to second order in the noncommutitive parameter.
NASA Astrophysics Data System (ADS)
Woltjer, L.
En la reunion celebrada en diciembre dei ano pasado informe al Consejo de mi deseo de terminar mi contrato como Director General de la ESO una vez que fuera aprobado el proyecto dei VLT, que se espera sucedera hacia fines de este aAo. Cuando fue renovada mi designacion hace tres aAos, el Consejo conocia mi intencion de no completar los cinco aAos dei contrato debido a mi deseo de disponer de mas tiempo para otras actividades. Ahora, una vez terminada la fase preparatoria para el VLT, Y habiendose presentado el proyecto formalmente al Consejo el dia 31 de marzo, y esperando su muy probable aprobacion antes dei termino de este ano, me parece que el 10 de enero de 1988 presenta una excelente fecha para que se produzca un cambio en la administracion de la ESO.
Quantum Radiation of a Non-stationary Kerr Newman Black Hole in de Sitter Space Time
NASA Astrophysics Data System (ADS)
Jiang, Qing-Quan; Yang, Shu-Zheng
Hawking radiation of Klein-Gordon and Dirac particles in a non-stationary Kerr-Newman-de-Sitter black hole is studied by introducing a new tortoise coordinate transformation. The result shows that the Fermi-Dirac radiant spectrum displays a new term that represents the interaction between the spin of spinor particles and the rotation of black holes, which is absent in the Bose-Einstein distribution of Klein-Gordon particles.
Non-Linear Effects of Self Generated Alfven Waves in Oblique Shocks and Cosmic Ray Acceleration Efficiency
NASA Astrophysics Data System (ADS)
Medina-Tanco, G. A.; Opher, R.
RESUMEN. Se presentan resultados numericos para un modelo hidrodinamico de cuatro componentes (plasma de fondo, particulas energeticas, ondas de Alfven autogeneradas y campo magnetico) para choques oblicuos. ABSTRACT. Numerical results of a four component hydrodynamic model (background plasma, energetic particles, self-generated Alfven waves and magnetic field) for oblique shocks are presented. Keq wo't : COSMIC RAY-GENERAL - PLASMAS - SHOCK WAVES
El astronauta de la NASA José Hernández alienta a los estudiantes a que sigan sus sueños. Hernández también habla acerca del papel que juegan los padres para ayudar a que sus hijos hagan realidad s...
Exact solutions in 3D new massive gravity.
Ahmedov, Haji; Aliev, Alikram N
We show that the field equations of new massive gravity (NMG) consist of a massive (tensorial) Klein-Gordon-type equation with a curvature-squared source term and a constraint equation. We also show that, for algebraic type D and N spacetimes, the field equations of topologically massive gravity (TMG) can be thought of as the "square root" of the massive Klein-Gordon-type equation. Using this fact, we establish a simple framework for mapping all types D and N solutions of TMG into NMG. Finally, we present new examples of types D and N solutions to NMG.
Covariant theory of Bose-Einstein condensates in curved spacetimes with electromagnetic interactions: The hydrodynamic approach
NASA Astrophysics Data System (ADS)
Chavanis, Pierre-Henri; Matos, Tonatiuh
We develop a hydrodynamic representation of the Klein-Gordon-Maxwell-Einstein equations. These equations combine quantum mechanics, electromagnetism, and general relativity. We consider the case of an arbitrary curved spacetime, the case of weak gravitational fields in a static or expanding background, and the nonrelativistic (Newtonian) limit. The Klein-Gordon-Maxwell-Einstein equations govern the evolution of a complex scalar field, possibly describing self-gravitating Bose-Einstein condensates, coupled to an electromagnetic field. They may find applications in the context of dark matter, boson stars, and neutron stars with a superfluid core.
Exact Solutions in 3D New Massive Gravity
Ahmedov, Haji; Aliev, Alikram N.
We show that the field equations of new massive gravity (NMG) consist of a massive (tensorial) Klein-Gordon-type equation with a curvature-squared source term and a constraint equation. We also show that, for algebraic type D and N spacetimes, the field equations of topologically massive gravity (TMG) can be thought of as the 'square root' of the massive Klein-Gordon-type equation. Using this fact, we establish a simple framework for mapping all types D and N solutions of TMG into NMG. Finally, we present new examples of types D and N solutions to NMG.
Exact Solutions in 3D New Massive Gravity
NASA Astrophysics Data System (ADS)
Ahmedov, Haji; Aliev, Alikram N.
We show that the field equations of new massive gravity (NMG) consist of a massive (tensorial) Klein-Gordon-type equation with a curvature-squared source term and a constraint equation. We also show that, for algebraic type D and N spacetimes, the field equations of topologically massive gravity (TMG) can be thought of as the "square root" of the massive Klein-Gordon-type equation. Using this fact, we establish a simple framework for mapping all types D and N solutions of TMG into NMG. Finally, we present new examples of types D and N solutions to NMG.
The hydrodynamic vortex: an exactly solvable black hole analogue
NASA Astrophysics Data System (ADS)
Ussembayev, Nail
We consider the Cauchy problem for the Klein-Gordon equation on an effective Lorentzian manifold describing the sound propagation on a background flow undergoing a subsonic-supersonic transition. For the hydrodynamic vortex model, a particular case of a draining bathtub geometry with non-zero circulation and no draining, we derive an exact solution and discuss its properties.
Stability properties of Q-stars
NASA Astrophysics Data System (ADS)
Becerril, R.; Bernal, A.; Guzmán, F. S.; Nucamendi, U.
We present the evolution of Q-star configurations using numerical methods. We solve the full Einstein-Klein-Gordon system of equations and show that: Q-stars can be stable and unstable. The unstable branch is two fold: configurations with negative binding energy that collapse and form black holes, and others with positive binding energy that explode and release the scalar field.
Orthogonality criterion for banishing hydrino states from standard quantum mechanics
NASA Astrophysics Data System (ADS)
de Castro, Antonio S.
Orthogonality criterion is used to shown in a very simple and general way that anomalous bound-state solutions for the Coulomb potential (hydrino states) do not exist as bona fide solutions of the Schr\\"{o}dinger, Klein-Gordon and Dirac equations.
The hydrino and other unlikely states
NASA Astrophysics Data System (ADS)
Dombey, Norman
We discuss the tightly bound (hydrino) solution of the Klein Gordon equation for the Coulomb potential in 3 dimensions. We show that a similar tightly bound state occurs for the Dirac equation for the Coulomb potential in 2 dimensions. These states are unphysical since they disappear if the nuclear charge distribution is taken to have an arbitrarily small but non-zero radius.
A new method dealing with hawking effects of evaporating black holes
Zhao, Z.; Dai, X. )
This paper reports that, both the location and the temperature of event horizons of evaporating black holes can be easily given if one proposes the Klein-Gordon equation approaches the standard form of wave equation near event horizons by using tortoise-type coordinates.
Hawking Temperature of Acoustic Black Hole
NASA Astrophysics Data System (ADS)
Xie, Zhi Kun
Using a new tortoise coordinate transformation, the Hawking radiation of the acoustic black hole was discussed by studying the Klein-Gordon equation of scalar particles in the curve space-time. It was found that the Hawking temperature is connected with time and position on the event horizon.
Lower bounds for sums of eigenvalues of elliptic operators and systems
Ilyin, Aleksei A
Two-term lower bounds of Berzin-Li-Yau type are obtained for the sums of eigenvalues of elliptic operators and systems with constant coefficients and Dirichlet boundary conditions. The polyharmonic operator, the Stokes system and its generalizations, the two-dimensional buckling problem, and also the Klein-Gordon operator are considered. Bibliography: 32 titles.
Resonant frequencies of the hydrodynamic vortex
NASA Astrophysics Data System (ADS)
Vieira, H. S.
We study the sound perturbation of the hydrodynamic vortex geometry and present an exact expression for the resonant frequencies (quasispectrum) of this geometry. Exact solution for the radial part of the covariant Klein-Gordon equation in this spacetime is obtained, and is given in terms of the double confluent Heun functions. We found that the resonant frequencies are complex number.
Oscillatons formed by nonlinear gravity
Obregon, Octavio; Urena-Lopez, L. Arturo; Schunck, Franz E.
Oscillatons are solutions of the coupled Einstein-Klein-Gordon equations that are globally regular and asymptotically flat. By means of a Legendre transformation we are able to visualize the behavior of the corresponding objects in nonlinear gravity where the scalar field has been absorbed by means of the conformal mapping.
The Stochastic Nonlinear Damped Wave Equation
Barbu, V. Da Prato, G.
We prove the existence of an invariant measure for the transition semigroup associated with a nonlinear damped stochastic wave equation in R{sup n} of the Klein-Gordon type. The uniqueness of the invariant measure and the structure of the corresponding Kolmogorov operator are also studied.
Perturbative Approaching for Boson Fields' System in a Lewis-Papapetrou Space-Time
Murariu, G.; Dariescu, M. A.; Dariescu, C.
In this paper the first order solutions of a Klein--Gordon--Maxwell--Einstein coupled system equations were derived for boson fields in a Lewis Papapetrou space time. The results expand the previous static solutions obtained in literature. A main goal is represented by the symbolic script built for such approach.
New Traveling Wave Solutions for a Class of Nonlinear Evolution Equations
NASA Astrophysics Data System (ADS)
Bai, Cheng-Jie; Zhao, Hong; Xu, Heng-Ying; Zhang, Xia
The deformation mapping method is extended to solve a class of nonlinear evolution equations (NLEEs). Many types of explicit and exact traveling wave solutions, which contain solitary wave solutions, trigonometric function solutions, and Jacobian elliptic function solutions, are obtained by a simple algebraic transformation relation between the solutions of the NLEEs and those of the cubic nonlinear Klein-Gordon (NKG) equation.
Vacuum effects in a spatially homogeneous and isotropic cosmological background
NASA Astrophysics Data System (ADS)
Villalba, Victor M.; Percoco, Umberto
We obtain, by separation of variables, an exact solution to the Klein-Gordon and Dirac equations in a cosmological, spatially-closed, Robertson-Walker space-time with a positive cosmological constant Lambda. The model is associated with a universe filled with radiation. We analyze the phenomenon of particle creation for different values of the dimensionless coupling constant xi.
Relativistic Particle in Electromagnetic Fields with a Generalized Uncertainty Principle
NASA Astrophysics Data System (ADS)
Merad, M.; Zeroual, F.; Falek, M.
In this paper, we propose to solve the relativistic Klein-Gordon and Dirac equations subjected to the action of a uniform electromagnetic field with a generalized uncertainty principle in the momentum space. In both cases, the energy eigenvalues and their corresponding eigenfunctions are obtained. The limit case is then deduced for a small parameter of deformation.
Notes on oscillator-like interactions of various spin relativistic particles
NASA Technical Reports Server (NTRS)
Dvoeglazov, Valeri V.; Delsolmesa, Antonio
The equations for various spin particles with oscillator-like interactions are discussed in this talk. Topics discussed include: (1) comment on 'The Klein-Gordon Oscillator'; (2) the Dirac oscillator in quaternion form; (3) the Dirac-Dowker oscillator; (4) the Weinberg oscillator; and (5) note on the two-body Dirac oscillator.
Calcineurin hydrolysis of para-nitrophenyl phosphorothioate.
Spannaus-Martin, Donna J; Martin, Bruce L
para-Nitrophenyl phosphorothioate (pNPT) was hydrolyzed by calcineurin at initial rates slightly, but comparable to rates for para-nitrophenyl phosphate (pNPP). Kinetic characterization yielded higher estimates for both Km and Vmax compared to pNPP. Metal ion activation of phosphorothioate hydrolysis was more promiscuous. Unlike the hydrolysis of with pNPP, Ca2+, Mg2+, and Ba2+ activated calcineurin as well as Mn2+.
A note on para-holomorphic Riemannian-Einstein manifolds
NASA Astrophysics Data System (ADS)
Ida, Cristian; Ionescu, Alexandru; Manea, Adelina
The aim of this note is the study of Einstein condition for para-holomorphic Riemannian metrics in the para-complex geometry framework. First, we make some general considerations about para-complex Riemannian manifolds (not necessarily para-holomorphic). Next, using a one-to-one correspondence between para-holomorphic Riemannian metrics and para-Kähler-Norden metrics, we study the Einstein condition for a para-holomorphic Riemannian metric and the associated real para-Kähler-Norden metric on a para-complex manifold. Finally, it is shown that every semi-simple para-complex Lie group inherits a natural para-Kählerian-Norden Einstein metric.
Nuevos aspectos en el estudio de la particula D en el experimento FOCUS de Fermilab
Quinones Gonzalez, Jose A.; /Puerto Rico U., Mayaguez
The purpose of this work is to improve the reconstruction techniques of the decays of the particles that contain charm in the quark composition using the information of the Target Silicon Detector of the experiment E831 (FOCUS). That experiment runs during 1997 to 1998 in Fermilab National Laboratory. The objective of the experiment was improving the understanding of the particles that contain charm. Adding the Target Silicon Detector information in the reconstruction process of the primary vertex the position error. This reduction produces an improvement in the mass signal and the knowledge of the charm particles properties. This ad to the possibility's that in other analysis will use the techniques developed in this work.
Ortho-para-hydrogen equilibration on Jupiter
NASA Technical Reports Server (NTRS)
Carlson, Barbara E.; Lacis, Andrew A.; Rossow, William B.
Voyager IRIS observations reveal that the Jovian para-hydrogen fraction is not in thermodynamic equilibrium near the NH3 cloud top, implying that a vertical gradient exists between the high-temperature equilibrium value of 0.25 at depth and the cloud top values. The height-dependent para-hydrogen profile is obtained using an anisotropic multiple-scattering radiative transfer model. A vertical correlation is found to exist between the location of the para-hydrogen gradient and the NH3 cloud, strongly suggesting that paramagnetic conversion on NH3 cloud particle surfaces is the dominant equilibration mechanism. Below the NH3 cloud layer, the para fraction is constant with depth and equal to the high-temperature equilibrium value of 0.25. The degree of cloud-top equilibration appears to depend on the optical depth of the NH3 cloud layer. Belt-zone variations in the para-hydrogen profile seem to be due to differences in the strength of the vertical mixing.
Para-methylstyrene from toluene and acetaldehyde
Innes, R.A.; Occelli, M.L.
High yields of para-methylstyrene (PMS) were obtained in this study by coupling toluene and acetaldehyde then cracking the resultant 1,1-ditolylethane (DTE) to give equimolar amounts of PMS and toluene. In the first step, a total DTE and ''trimer'' yield of 98% on toluene and 93% on acetaldehyde was obtained using 98% sulfuric acid as catalyst at 5-10/sup 0/C. In the second step, a choline chloride-offretite cracked DTE with 84.0% conversion and 91% selectivity to PMS and toluene. Additional PMS can be obtained by cracking the by-product ''trimer'' formed by coupling DTE and toluene with acetaldehyde. Zeolite Rho was as active but yielded less PMS (86%) and produced more para-ethyltoluene (PET), an undesirable by-product.
Allergic contact dermatitis to para-phenylenediamine.
Jenkins, David; Chow, Elizabeth T
Exposure to hair dye is the most frequent route of sensitisation to para-phenylenediamine (PPD), a common contact allergen. International studies have examined the profile of PPD, but Australian-sourced information is lacking. Patients are often dissatisfied with advice to stop dyeing their hair. This study examines patients' characteristics, patch test results and outcomes of PPD allergy from a single Australian centre, through a retrospective analysis of patch test data from 2006 to 2013 at the Liverpool Hospital Dermatology Department. It reviews the science of hair dye allergy, examines alternative hair dyes and investigates strategies for hair dyeing. Of 584 patients, 11 were allergic to PPD. Our PPD allergy prevalence rate of 2% is at the lower end of international reported rates. About half these patients also react to para-toluenediamine (PTD). Affected patients experience a significant lifestyle disturbance. In all, 78% tried alternative hair dyes after the patch test diagnosis and more than half continued to dye their hair. Alternative non-PPD hair dyes are available but the marketplace can be confusing. Although some patients are able to tolerate alternative hair dyes, caution is needed as the risk of developing an allergy to other hair dye ingredients, especially PTD, is high.
Time domain para hydrogen induced polarization.
Ratajczyk, Tomasz; Gutmann, Torsten; Dillenberger, Sonja; Abdulhussaein, Safaa; Frydel, Jaroslaw; Breitzke, Hergen; Bommerich, Ute; Trantzschel, Thomas; Bernarding, Johannes; Magusin, Pieter C M M; Buntkowsky, Gerd
Para hydrogen induced polarization (PHIP) is a powerful hyperpolarization technique, which increases the NMR sensitivity by several orders of magnitude. However the hyperpolarized signal is created as an anti-phase signal, which necessitates high magnetic field homogeneity and spectral resolution in the conventional PHIP schemes. This hampers the application of PHIP enhancement in many fields, as for example in food science, materials science or MRI, where low B(0)-fields or low B(0)-homogeneity do decrease spectral resolution, leading to potential extinction if in-phase and anti-phase hyperpolarization signals cannot be resolved. Herein, we demonstrate that the echo sequence (45°-τ-180°-τ) enables the acquisition of low resolution PHIP enhanced liquid state NMR signals of phenylpropiolic acid derivatives and phenylacetylene at a low cost low-resolution 0.54 T spectrometer. As low field TD-spectrometers are commonly used in industry or biomedicine for the relaxometry of oil-water mixtures, food, nano-particles, or other systems, we compare two variants of para-hydrogen induced polarization with data-evaluation in the time domain (TD-PHIP). In both TD-ALTADENA and the TD-PASADENA strong spin echoes could be detected under conditions when usually no anti-phase signals can be measured due to the lack of resolution. The results suggest that the time-domain detection of PHIP-enhanced signals opens up new application areas for low-field PHIP-hyperpolarization, such as non-invasive compound detection or new contrast agents and biomarkers in low-field Magnetic Resonance Imaging (MRI). Finally, solid-state NMR calculations are presented, which show that the solid echo (90y-τ-90x-τ) version of the TD-ALTADENA experiment is able to convert up to 10% of the PHIP signal into visible magnetization.
Cooling by Para-to-Ortho-Hydrogen Conversion
NASA Technical Reports Server (NTRS)
Sherman, A.; Nast, T.
Catalyst speeds conversion, increasing capacity of solid hydrogen cooling system. In radial-flow catalytic converter, para-hydrogen is converted to equilibrium mixture of para-hydrogen and ortho-hydrogen as it passes through porous cylinder of catalyst. Addition of catalyst increases capacity of hydrogen sublimation cooling systems for radiation detectors.
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Espanol.smokefree.gov ofrece apoyo y recursos para norteamericanos que hablan español y quieren dejar de fumar. Este sitio en la red fue creada por la División de Investigación para el Control del Tabaco del Instituto Nacional del Cáncer.
Towards a double field theory on para-Hermitian manifolds
NASA Astrophysics Data System (ADS)
Vaisman, Izu
In a previous paper, we have shown that the geometry of double field theory has a natural interpretation on flat para-Kähler manifolds. In this paper, we show that the same geometric constructions can be made on any para-Hermitian manifold. The field is interpreted as a compatible (pseudo-)Riemannian metric. The tangent bundle of the manifold has a natural, metric-compatible bracket that extends the C-bracket of double field theory. In the para-Kähler case, this bracket is equal to the sum of the Courant brackets of the two Lagrangian foliations of the manifold. Then, we define a canonical connection and an action of the field that correspond to similar objects of double field theory. Another section is devoted to the Marsden-Weinstein reduction in double field theory on para-Hermitian manifolds. Finally, we give examples of fields on some well-known para-Hermitian manifolds.
Towards a double field theory on para-Hermitian manifolds
Vaisman, Izu
In a previous paper, we have shown that the geometry of double field theory has a natural interpretation on flat para-Kähler manifolds. In this paper, we show that the same geometric constructions can be made on any para-Hermitian manifold. The field is interpreted as a compatible (pseudo-)Riemannian metric. The tangent bundle of the manifold has a natural, metric-compatible bracket that extends the C-bracket of double field theory. In the para-Kähler case, this bracket is equal to the sum of the Courant brackets of the two Lagrangian foliations of the manifold. Then, we define a canonical connection and an action of the field that correspond to similar objects of double field theory. Another section is devoted to the Marsden-Weinstein reduction in double field theory on para-Hermitian manifolds. Finally, we give examples of fields on some well-known para-Hermitian manifolds.
Approximation of small-amplitude weakly coupled oscillators by discrete nonlinear Schrödinger equations
NASA Astrophysics Data System (ADS)
Pelinovsky, Dmitry; Penati, Tiziano; Paleari, Simone
Small-amplitude weakly coupled oscillators of the Klein-Gordon lattices are approximated by equations of the discrete nonlinear Schrödinger type. We show how to justify this approximation by two methods, which have been very popular in the recent literature. The first method relies on a priori energy estimates and multi-scale decompositions. The second method is based on a resonant normal form theorem. We show that although the two methods are different in the implementation, they produce equivalent results as the end product. We also discuss the applications of the discrete nonlinear Schrödinger equation in the context of existence and stability of breathers of the Klein-Gordon lattice.
Bose-Einstein condensates and scalar fields; exploring the similitudes
NASA Astrophysics Data System (ADS)
Castellanos, E.; Macías, A.; Núñez, D.
We analyze the the remarkable analogy between the classical Klein-Gordon equation for a test scalar field in a flat and also in a curved background, and the Gross-Pitaevskii equation for a Bose-Einstein condensate trapped by an external potential. We stress here that the solution associated with the Klein-Gordon equation (KG) in a flat space time has the same mathematical structure, under certain circumstances, to those obtained for the Gross-Pitaevskii equation, that is, a static soliton solution. Additionally, Thomas-Fermi approximation is applied to the 3-dimensional version of this equation, in order to calculate some thermodynamical properties of the system in curved a space-time back ground. Finally, we stress the fact that a gravitational background provides, in some cases, a kind of confining potential for the scalar field, allowing us to remarks even more the possible connection between scalar fields and the phenomenon of Bose-Einstein condensation.
The two-dimensional Euler-Poisson system with spherical symmetry
NASA Astrophysics Data System (ADS)
Jang, Juhi
This article concerns the global-in-time existence of smooth solutions with small amplitude to two space dimensional Euler-Poisson system. The main difficulty lies in the slow time decay (1 + t)-1 of the linear system. Inspired by the work of Ozawa et al., ["Global existence and asymptotic behavior of solutions for the Klein-Gordon equations with quadratic nonlinearity in two space dimensions," Math. Z. 222, 341-362 (1996), 10.1007/BF02621870; "Remarks on the Klein-Gordon equation with quadratic nonlinearity in two space dimensions," in Nonlinear Waves, Gakuto International Series: Mathematical Sciences and Applications Vol. 10 (Gakkotosho, Tokyo, 1997), pp. 383-392,] we show that such smooth solutions exist for radially symmetric flows.
Photon mirror acceleration in the quantum regime
Mendonça, J. T.; Fedele, R.
Reflection of an electron beam by an intense laser pulse is considered. This is the so-called photon mirror configuration for laser acceleration in vacuum, where the energy of the incident electron beam is nearly double-Doppler shifted due to reflection on the laser pulse front. A wave-electron optical description for electron reflection and resonant backscattering, due to both linear electric field force and quadratic ponderomotive force, is provided beyond the paraxial approximation. This is done by assuming that the single electron of the beam is spin-less and therefore its motion can be described by a quantum scalar field whose spatiotemporal evolution is governed by the Klein-Gordon equation (Klein-Gordon field). Our present model, not only confirms the classical results but also shows the occurrence of purely quantum effects, such as partial reflection of the incident electron beam and enhanced backscattering due to Bragg resonance.
Strong-field Breit-Wheeler pair production in short laser pulses: Relevance of spin effects
NASA Astrophysics Data System (ADS)
Jansen, M. J. A.; Kamiński, J. Z.; Krajewska, K.; Müller, C.
Production of electron-positron pairs in the collision of a high-energy photon with a high-intensity few-cycle laser pulse is studied. By utilizing the frameworks of laser-dressed spinor and scalar quantum electrodynamics, a comparison between the production of pairs of Dirac and Klein-Gordon particles is drawn. Positron energy spectra and angular distributions are presented for various laser parameters. We identify conditions under which predictions from Klein-Gordon theory either closely resemble or largely differ from those of the proper Dirac theory. In particular, we address the question to which extent the relevance of spin effects is influenced by the short duration of the laser pulse.
Quantum particle probe of the Kerr naked singularity
NASA Astrophysics Data System (ADS)
Gurtug, O.; Halilsoy, M.
We investigate Kerr's timelike naked singularity within the framework of quantum mechanics. A quantum particle in the form of a massive boson is sent in the plane θ = π/2 to the naked ring singularity of Kerr which develops for the overspinning case (a>M) to test it from a quantum picture. This singularity is analysed in two different coordinate systems. We show that the spatial operator of the Klein-Gordon equation both in Boyer-Lindquist and in the dragging coordinate systems has a unique self-adjoint extension. As a result, the classical Kerr's ring singularity becomes quantum regular, if it is probed with massive bosonic particles obeying the Klein-Gordon equation.
Relativistic effects in elastic scattering of electrons in TEM.
Rother, Axel; Scheerschmidt, Kurt
Transmission electron microscopy typically works with highly accelerated thus relativistic electrons. Consequently the scattering process is described within a relativistic formalism. In the following, we will examine three different relativistic formalisms for elastic electron scattering: Dirac, Klein-Gordon and approximated Klein-Gordon, the standard approach. This corresponds to a different consideration of spin effects and a different coupling to electromagnetic potentials. A detailed comparison is conducted by means of explicit numerical calculations. For this purpose two different formalisms have been applied to the approaches above: a numerical integration with predefined boundary conditions and the multislice algorithm, a standard procedure for such simulations. The results show a negligibly small difference between the different relativistic equations in the vicinity of electromagnetic potentials, prevailing in the electron microscope. The differences between the two numeric approaches are found to be small for small-angle scattering but eventually grow large for large-angle scattering, recorded for instance in high-angle annular dark field.
Bosonic pair creation and the Schiff-Snyder-Weinberg effect
NASA Astrophysics Data System (ADS)
Lv, Q. Z.; Bauke, Heiko; Su, Q.; Keitel, C. H.; Grobe, R.
Interactions between different bound states in bosonic systems can lead to pair creation. We study this process in detail by solving the Klein-Gordon equation on space-time grids in the framework of time-dependent quantum field theory. By choosing specific external field configurations, two bound states can become pseudodegenerate, which is commonly referred to as the Schiff-Snyder-Weinberg effect. These pseudodegenerate bound states, which have complex energy eigenvalues, are related to the pseudo-Hermiticity of the Klein-Gordon Hamiltonian. In this work, the influence of the Schiff-Snyder-Weinberg effect on pair production is studied. A generalized Schiff-Snyder-Weinberg effect, where several pairs of pseudodegenerate states appear, is found in combined electric and magnetic fields. The generalized Schiff-Snyder-Weinberg effect likewise triggers pair creation. The particle number in these situations obeys an exponential growth law in time enhancing the creation of bosons, which cannot be found in fermionic systems.
Geometric creation of quantum vorticity
NASA Astrophysics Data System (ADS)
Good, Michael R. R.; Xiong, Chi; Chua, Alvin J. K.; Huang, Kerson
We consider superfluidity and quantum vorticity in rotating spacetimes. The system is described by a complex scalar satisfying a nonlinear Klein-Gordon equation. Rotation terms are identified and found to lead to the transfer of angular momentum of the spacetime to the scalar field. The scalar field responds by rotating, physically behaving as a superfluid, through the creation of quantized vortices. We demonstrate vortex nucleation through numerical simulation.
Spectral stability of periodic waves in the generalized reduced Ostrovsky equation
NASA Astrophysics Data System (ADS)
Geyer, Anna; Pelinovsky, Dmitry E.
We consider stability of periodic travelling waves in the generalized reduced Ostrovsky equation with respect to co-periodic perturbations. Compared to the recent literature, we give a simple argument that proves spectral stability of all smooth periodic travelling waves independent of the nonlinearity power. The argument is based on the energy convexity and does not use coordinate transformations of the reduced Ostrovsky equations to the semi-linear equations of the Klein-Gordon type.
Relativistic Photoionization Computations with the Time Dependent Dirac Equation
fields often occurs in the relativistic regime. A complete description of this phenomenon requires both relativistic and quantum mechanical treatment...photoionization, or other relativis- tic quantum electronics problems. While the Klein-Gordon equation captures much of the relevant physics, especially... quantum number. The orbital angular momentum is a bad quantum number because the stationary states have `0 6= `3 and `1 6= `2, so that they are not
The AEMS (Analysis of Electrical and Mechanical Systems) Project in Applied Mathematics at Carnegie-Mellon University.
Dirac matrices . Again, the Klein-Gordon equation can be replaced by the Proca equation, and this leads to the algebra of Duffin-Kemer matrices . A...interesting questions in algebra. In particular, the research has concerned network determinants Grassmann algebra, Wang algebra, matroids, and matrices ...equivalent matrices arising in linear programming. Various other types of network interconnections can be defined and this leads to associated sum operations
Equilibrium Configuration of Φ4 Oscillatons
NASA Astrophysics Data System (ADS)
Valdez-Alvarado, Susana; Becerril, Ricardo; Ureña-López, L. Arturo
We search for equilibrium configurations of the (coupled) Einstein-Klein-Gordon equations for the case of a real scalar field endowed with a quartic self-interaction potential. The resulting solutions are the generalizations of the (massive) oscillating soliton stars, the so-called oscillatons. Among other parameters, we estimate the mass curve of the configurations, and determine their critical mass for different values of the quartic interaction.
Evolution of boson-fermion stars
NASA Astrophysics Data System (ADS)
Valdez-Alvarado, Susana; Palenzuela, Carlos; Alic, Daniela; Ureña-López, L. Arturo; Becerril, Ricardo
The boson-fermion stars can be modeled with a complex scalar field coupled minimally to a perfect fluid (i.e., without viscosity and non-dissipative). We present a study of these solutions and their dynamical evolution by solving numerically the Einstein-Klein-Gordon-Hydrodynamic (EKGHD) system. It is shown that stable configurations exist, but stability of general configurations depends finely upon the number of bosons and fermions.
Comment on: "An observation on the periodic solutions to nonlinear physical models by means of the auxiliary equation with a sixth-degree nonlinear term" [Commun Nonlinear Sci Numer Simulat 2013;18:2177-2187
NASA Astrophysics Data System (ADS)
Liu, Hong-Zhun; Sun, Xiao-Quan; Chen, Li-Jiang
This article shows that all novel exact solutions in the commented paper are not admitted by the original generalized Klein-Gordon equation and active-dissipative dispersive media equation. In addition, we present general solutions of certain auxiliary equation with sixth-degree nonlinear term. Then, based on above general solutions, we find that five cases in their Table 1 is shown to be incorrect.
Rindler effect for a nonuniformly accelerating observer
Zhu Jian-yang; Bao Aidong; Zhao Zheng
Both the Klein-Gordon equation and the Dirac equation are dealt with in the generalized Rindler space-time of a nonuniformly accelerating observer. Making use of a new method and introducing a tortoise-type coordinate transformation, it is proved that there exist an event horizon and thermal radiation depending on time in the space-time. The Hawking-Unruh temperature is proportional to the variable acceleration.
On the correspondence between quantum and classical variational principles
Ruiz, D. E.; Dodin, I. Y.
Here, classical variational principles can be deduced from quantum variational principles via formal reparameterization of the latter. It is shown that such reparameterization is possible without invoking any assumptions other than classicality and without appealing to dynamical equations. As examples, first principle variational formulations of classical point-particle and cold-fluid motion are derived from their quantum counterparts for Schrodinger, Pauli, and Klein-Gordon particles.
Foundation of Hydrodynamics of Strongly Interacting Systems
Wong, Cheuk-Yin
Hydrodynamics and quantum mechanics have many elements in common, as the density field and velocity fields are common variables that can be constructed in both descriptions. Starting with the Schroedinger equation and the Klein-Gordon for a single particle in hydrodynamical form, we examine the basic assumptions under which a quantum system of particles interacting through their mean fields can be described by hydrodynamics.
Blowup results for the KGS system with higher order Yukawa coupling
Shi, Qi-Hong; Li, Wan-Tong; Wang, Shu
In this paper, we investigate the Klein-Gordon-Schrödinger (KGS) system with higher order Yukawa coupling in spatial dimensions N ≥ 3. We establish a perturbed virial type identity and prove blowup results relied on Lyapunov functionals for KGS system with a negative energy level. Additionally, we give a result with respect to the blowup rate in finite time for the radial solution in 3 spatial dimensions.
Approximate Solution of the Spin-0 Particle Subject to the Trigonometric Pöschl-Teller Potential with Centrifugal Barrier
NASA Astrophysics Data System (ADS)
Hamzavi, Majid; Rajabi, Ali Akbar; Amirfakhrian, Majid
The trigonometric Pöschl-Teller (PT) potential describes the diatomic molecular vibration. In this paper, we study the approximate solutions of the radial Klein-Gordon (KG) equation for the rotating trigonometric PT potential using the Nikiforov-Uvarov (NU) method. The energy eigenvalues and their corresponding eigenfunctions are calculated for arbitrary l-states in closed form. We obtain the non-relativistic limit and present some numerical results for both relativistic and non-relativistic cases.
Exact Solutions of Relativistic Bound State Problem for Spinless Bosons
NASA Astrophysics Data System (ADS)
Aslanzadeh, M.; Rajabi, A. A.
We investigated in detail the relativistic bound states of spin-zero bosons under the influence of Coulomb-plus-linear potentials with an arbitrary combination of scalar and vector couplings. Through an exact analytical solution of three-dimensional Klein-Gordon equation, closed form expressions were derived for energy eigenvalues and wave functions and some correlations between potential parameters were found. We also presented the relativistic description of bound states and nonrelativistic limit of the problem in some special cases.
Dynamics of nonrelativistic quantum mechanics
NASA Astrophysics Data System (ADS)
Efthimiades, Spyros
We show that the wavefunction of an electron interacting with an electric potential is accurately represented by the superposition of plane waves that fulfills the total energy relation. As a result, we explicitly derive the Schrödinger, Pauli, Klein-Gordon, and Dirac equations. While the traditional nonrelativistic quantum dynamics is based on postulates, the dynamics we introduce is theoretically justified, in agreement with experimental measurements, and consistent with the fundamental theory of quantum electrodynamics.
Lagrangian form of Schrödinger equation
NASA Astrophysics Data System (ADS)
Arsenović, D.; Burić, N.; Davidović, D. M.; Prvanović, S.
Lagrangian formulation of quantum mechanical Schrödinger equation is developed in general and illustrated in the eigenbasis of the Hamiltonian and in the coordinate representation. The Lagrangian formulation of physically plausible quantum system results in a well defined second order equation on a real vector space. The Klein-Gordon equation for a real field is shown to be the Lagrangian form of the corresponding Schrödinger equation.
Vacuum effects in a spatially homogeneous and isotropic cosmological background.
NASA Astrophysics Data System (ADS)
Villalba, V. M.; Percoco, U.
The authors obtain, by separation of variables, an exact solution to the Klein Gordon equation in a cosmological, spatially closed, Robertson-Walker space-time with a positive cosmological constant. The model is associated with a universe filled with radiation. The authors analyze the phenomenon of particle creation for different values of the dimensionless coupling constant. They discuss the relevance of the cosmological constant in this process.
On the tail problem in cosmology
NASA Astrophysics Data System (ADS)
Faraoni, Valerio; Sonego, Sebastiano
The tail problem for the propagation of a scalar field is considered in a cosmological background, taking a Robertson-Walker spacetime as a specific example. The explicit radial dependence of the general solution of the Klein-Gordon equation with non-minimal coupling is derived, and the inapplicability of the standard calculation of the reflection and transmission coefficients to the study of scattering of waves by the cosmological curvature is discussed.
Stationary Eigenmodes and Their Stability during Wave Propagation in a Medium with Quadratic and Cubic Nonlinearities without Dispersion
decomposed into a series of associated aperiodic solitary waves, as can be achieved for solutions of the KdV equation [11], is still under investigation. 3...The organization of the paper is as follows: In Section 2, we discuss aperiodic and periodic solitary wave solutions of a model equation with...Periodic Solitary Wave Solutions of the Nonlinear Klein Gordon Equation without Dispersion We shall take, as our model equation , the nonlinear Klein
Equilibrium Configuration of {Phi}{sup 4} Oscillatons
Valdez-Alvarado, Susana; Urena-Lopez, L. Arturo; Becerril, Ricardo
We search for equilibrium configurations of the (coupled) Einstein-Klein-Gordon equations for the case of a real scalar field endowed with a quartic self-interaction potential. The resulting solutions are the generalizations of the (massive) oscillating soliton stars, the so-called oscillatons. Among other parameters, we estimate the mass curve of the configurations, and determine their critical mass for different values of the quartic interaction.
ParaDiS-FEM dislocation dynamics simulation code primer
Tang, M; Hommes, G; Aubry, S; Arsenlis, A
The ParaDiS code is developed to study bulk systems with periodic boundary conditions. When we try to perform discrete dislocation dynamics simulations for finite systems such as thin films or cylinders, the ParaDiS code must be extended. First, dislocations need to be contained inside the finite simulation box; Second, dislocations inside the finite box experience image stresses due to the free surfaces. We have developed in-house FEM subroutines to couple with the ParaDiS code to deal with free surface related issues in the dislocation dynamics simulations. This primer explains how the coupled code was developed, the main changes from the ParaDiS code, and the functions of the new FEM subroutines.
Symmetries and unitary interactions of mass dimension one fermionic dark matter
NASA Astrophysics Data System (ADS)
Lee, Cheng-Yang
The fermionic fields constructed from Elko have several unexpected properties. They satisfy the Klein-Gordon but not the Dirac equation and are of mass dimension one instead of three-half. Starting with the Klein-Gordon Lagrangian, we initiate a careful study of the symmetries and interactions of these fermions and their higher-spin generalizations. We find, although the fermions are of mass dimension one, the four-point fermionic self-interaction violates unitarity at high-energy so it cannot be a fundamental interaction of the theory. Using the optical theorem, we derive an explicit bound on energy for the fermion-scalar interaction. It follows that for the spin-half fermions, the demand of renormalizability and unitarity forbids four-point interactions and only allows for the Yukawa interaction. For fermions with spin j > 1 2, they have no renormalizable or unitary interactions. Since the theory is described by a Klein-Gordon Lagrangian, the interaction generated by the local U(1) gauge symmetry which contains a four-point interaction, is excluded by the demand of renormalizability. In the context of the Standard Model, these properties make the spin-half fermions natural dark matter candidates. Finally, we discuss the recent developments on the introduction of new adjoint and spinor duals which may allow us to circumvent the unitarity constraints on the interactions.
Discrete solitons in electromechanical resonators.
Syafwan, M; Susanto, H; Cox, S M
We consider a particular type of parametrically driven discrete Klein-Gordon system describing microdevices and nanodevices, with integrated electrical and mechanical functionality. Using a multiscale expansion method we reduce the system to a discrete nonlinear Schrödinger equation. Analytical and numerical calculations are performed to determine the existence and stability of fundamental bright and dark discrete solitons admitted by the Klein-Gordon system through the discrete Schrödinger equation. We show that a parametric driving can not only destabilize onsite bright solitons, but also stabilize intersite bright discrete solitons and onsite and intersite dark solitons. Most importantly, we show that there is a range of values of the driving coefficient for which dark solitons are stable, for any value of the coupling constant, i.e., oscillatory instabilities are totally suppressed. Stability windows of all the fundamental solitons are presented and approximations to the onset of instability are derived using perturbation theory, with accompanying numerical results. Numerical integrations of the Klein-Gordon equation are performed, confirming the relevance of our analysis.
Quantum singularities in (2+1) dimensional matter coupled black hole spacetimes
Unver, O.; Gurtug, O.
Quantum singularities considered in the 3D Banados-Teitelboim-Zanelli (BTZ) spacetime by Pitelli and Letelier [Phys. Rev. D 77, 124030 (2008)] is extended to charged BTZ and 3D Einstein-Maxwell-dilaton gravity spacetimes. The occurrence of naked singularities in the Einstein-Maxwell extension of the BTZ spacetime both in linear and nonlinear electrodynamics as well as in the Einstein-Maxwell-dilaton gravity spacetimes are analyzed with the quantum test fields obeying the Klein-Gordon and Dirac equations. We show that with the inclusion of the matter fields, the conical geometry near r=0 is removed and restricted classes of solutions are admitted for the Klein-Gordon and Dirac equations. Hence, the classical central singularity at r=0 turns out to be quantum mechanically singular for quantum particles obeying the Klein-Gordon equation but nonsingular for fermions obeying the Dirac equation. Explicit calculations reveal that the occurrence of the timelike naked singularities in the considered spacetimes does not violate the cosmic censorship hypothesis as far as the Dirac fields are concerned. The role of horizons that clothes the singularity in the black hole cases is replaced by repulsive potential barrier against the propagation of Dirac fields.
Cooling by conversion of para to ortho-hydrogen
NASA Technical Reports Server (NTRS)
Sherman, A. (Inventor)
The cooling capacity of a solid hydrogen cooling system is significantly increased by exposing vapor created during evaporation of a solid hydrogen mass to a catalyst and thereby accelerating the endothermic para-to-ortho transition of the vapor to equilibrium hydrogen. Catalyst such as nickel, copper, iron or metal hydride gels of films in a low pressure drop catalytic reactor are suitable for accelerating the endothermic para-to-ortho conversion.
Ortho- and para-hydrogen in neutron thermalization
Daemen, L. L.; Brun, T. O.
The large difference in neutron scattering cross-section at low neutron energies between ortho- and para-hydrogen was recognized early on. In view of this difference (more than an order of magnitude), one might legitimately ask whether the ortho/para ratio has a significant effect on the neutron thermalization properties of a cold hydrogen moderator. Several experiments performed in the 60`s and early 70`s with a variety of source and (liquid hydrogen) moderator configurations attempted to investigate this. The results tend to show that the ortho/para ratio does indeed have an effect on the energy spectrum of the neutron beam produced. Unfortunately, the results are not always consistent with each other and much unknown territory remains to be explored. The problem has been approached from a computational standpoint, but these isolated efforts are far from having examined the ortho/para-hydrogen problem in neutron moderation in all its complexity. Because of space limitations, the authors cannot cover, even briefly, all the aspects of the ortho/para question here. This paper will summarize experiments meant to investigate the effect of the ortho/para ratio on the neutron energy spectrum produced by liquid hydrogen moderators.
ParaText : scalable text modeling and analysis.
Dunlavy, Daniel M.; Stanton, Eric T.; Shead, Timothy M.
Automated processing, modeling, and analysis of unstructured text (news documents, web content, journal articles, etc.) is a key task in many data analysis and decision making applications. As data sizes grow, scalability is essential for deep analysis. In many cases, documents are modeled as term or feature vectors and latent semantic analysis (LSA) is used to model latent, or hidden, relationships between documents and terms appearing in those documents. LSA supplies conceptual organization and analysis of document collections by modeling high-dimension feature vectors in many fewer dimensions. While past work on the scalability of LSA modeling has focused on the SVD, the goal of our work is to investigate the use of distributed memory architectures for the entire text analysis process, from data ingestion to semantic modeling and analysis. ParaText is a set of software components for distributed processing, modeling, and analysis of unstructured text. The ParaText source code is available under a BSD license, as an integral part of the Titan toolkit. ParaText components are chained-together into data-parallel pipelines that are replicated across processes on distributed-memory architectures. Individual components can be replaced or rewired to explore different computational strategies and implement new functionality. ParaText functionality can be embedded in applications on any platform using the native C++ API, Python, or Java. The ParaText MPI Process provides a 'generic' text analysis pipeline in a command-line executable that can be used for many serial and parallel analysis tasks. ParaText can also be deployed as a web service accessible via a RESTful (HTTP) API. In the web service configuration, any client can access the functionality provided by ParaText using commodity protocols ... from standard web browsers to custom clients written in any language.
A Comparative Usage-Based Approach to the Reduction of the Spanish and Portuguese Preposition "Para"
ERIC Educational Resources Information Center
Gradoville, Michael Stephen
This study examines the frequency effect of two-word collocations involving "para" "to," "for" (e.g. "fui para," "para que") on the reduction of "para" to "pa" (in Spanish) and "pra" (in Portuguese). Collocation frequency effects demonstrate that language speakers…
Hox and ParaHox genes: a review on molluscs.
Biscotti, Maria Assunta; Canapa, Adriana; Forconi, Mariko; Barucca, Marco
Hox and ParaHox genes are involved in patterning the anterior-posterior body axis in metazoans during embryo development. Body plan evolution and diversification are affected by variations in the number and sequence of Hox and ParaHox genes, as well as by their expression patterns. For this reason Hox and ParaHox gene investigation in the phylum Mollusca is of great interest, as this is one of the most important taxa of protostomes, characterized by a high morphological diversity. The comparison of the works reviewed here indicates that species of molluscs, belonging to different classes, share a similar composition of Hox and ParaHox genes. Therefore evidence suggests that the wide morphological diversity of this taxon could be ascribed to differences in Hox gene interactions and expressions and changes in the Hox downstream genes rather than to Hox cluster composition. Moreover the data available on Hox and ParaHox genes in molluscs compared with those of other Lophotrochozoa shed light on the complex and controversial evolutionary histories that these genes have undergone within protostomes.
Evolution of invertebrate deuterostomes and Hox/ParaHox genes.
Ikuta, Tetsuro
Transcription factors encoded by Antennapedia-class homeobox genes play crucial roles in controlling development of animals, and are often found clustered in animal genomes. The Hox and ParaHox gene clusters have been regarded as evolutionary sisters and evolved from a putative common ancestral gene complex, the ProtoHox cluster, prior to the divergence of the Cnidaria and Bilateria (bilaterally symmetrical animals). The Deuterostomia is a monophyletic group of animals that belongs to the Bilateria, and a sister group to the Protostomia. The deuterostomes include the vertebrates (to which we belong), invertebrate chordates, hemichordates, echinoderms and possibly xenoturbellids, as well as acoelomorphs. The studies of Hox and ParaHox genes provide insights into the origin and subsequent evolution of the bilaterian animals. Recently, it becomes apparent that among the Hox and ParaHox genes, there are significant variations in organization on the chromosome, expression pattern, and function. In this review, focusing on invertebrate deuterostomes, I first summarize recent findings about Hox and ParaHox genes. Next, citing unsolved issues, I try to provide clues that might allow us to reconstruct the common ancestor of deuterostomes, as well as understand the roles of Hox and ParaHox genes in the development and evolution of deuterostomes.
β-Cyclodextrin- para-aminosalicylic acid inclusion complexes
NASA Astrophysics Data System (ADS)
Roik, N. V.; Belyakova, L. A.; Oranskaya, E. I.
Complex formation of β-cyclodextrin with para-aminosalicylic acid in buffer solutions is studied by UV spectroscopy. It is found that the stoichiometric proportion of the components in the β-cyclodextrin-para-aminosalicylic acid inclusion complex is 1:1. The Ketelar equation is used to calculate the stability constants of the inclusion complexes at different temperatures. The thermodynamic parameters of the complex formation process (ΔG, ΔH, ΔS) are calculated using the van't Hoff equation. The 1:1 β-cyclodextrin-para-aminosalicylic acid inclusion complex is prepared in solid form and its characteristics are determined by IR spectroscopic and x-ray diffraction techniques.
Quantum simulation of driven para-Bose oscillators
NASA Astrophysics Data System (ADS)
Alderete, C. Huerta; Rodríguez-Lara, B. M.
Quantum mechanics allows paraparticles with mixed Bose-Fermi statistics that have not been experimentally confirmed. We propose a trapped-ion scheme whose effective dynamics are equivalent to a driven para-Bose oscillator of even order. Our mapping suggest highly entangled vibrational and internal ion states as the laboratory equivalent of quantum simulated parabosons. Furthermore, we show the generation and reconstruction of coherent oscillations and para-Bose analogs of Gilmore-Perelomov coherent states from population inversion measurements in the laboratory frame. Our proposal, apart from demonstrating an analog quantum simulator of para-Bose oscillators, provides a quantum state engineering tool that foreshadows the potential use of paraparticle dynamics in the design of quantum information systems.
Ortho and para-armalcolite samples in Apollo 17.
NASA Technical Reports Server (NTRS)
Haggerty, S. E.
Two paragenetically contrasting forms of armalcolite are present in basalts from the Apollo 17 Taurus-Littrow landing site. These armalcolites differ in optical properties, in crystal habit and in their distribution between coarse and fine grained rocks. It is proposed to call the two armalcolite forms ortho-armalcolite and para-armalcolite. Texural relationships and the evidence of experimental melting show that ortho-armalcolite is always the first crystalline phase to appear from unusually titanium rich magmas. The origin of para-armalcolite is not yet fully understood.
On some examples of para-Hermite and para-Kähler Einstein spaces with Λ ≠ 0
NASA Astrophysics Data System (ADS)
Chudecki, Adam
Spaces equipped with two complementary (distinct) congruences of self-dual null strings and at least one congruence of anti-self-dual null strings are considered. It is shown that if such spaces are Einsteinian then the vacuum Einstein field equations can be reduced to a single nonlinear partial differential equation of the second order. Different forms of these equations are analyzed. Finally, several new explicit metrics of the para-Hermite and para-Kähler Einstein spaces with Λ ≠ 0 are presented. Some relation of that metrics to a modern approach to mechanical issues is discussed.
The total neutron cross section of liquid para-hydrogen
NASA Astrophysics Data System (ADS)
Celli, M.; Rhodes, N.; Soper, A. K.; Zoppi, M.
We have measured, using the pulsed neutron source ISIS, the total neutron cross section of liquid para-hydrogen in the vicinity of the triple point. The experimental results compare only qualitatively with the results of the Young and Koppel theory. However, a much better agreement is found once modifications are included in the model which effectively take into account the intermolecular interactions.
Utilice en forma segura los productos con cebo para roedores
Si se usan de manera inadecuada, los productos con veneno para ratas y ratones podrían hacerle daño a usted, a sus hijos o a sus mascotas. Siempre que use pesticidas lea la etiqueta del producto y siga todas las indicaciones.
Wave Dark Matter and Dwarf Spheroidal Galaxies
NASA Astrophysics Data System (ADS)
Parry, Alan R.
We explore a model of dark matter called wave dark matter (also known as scalar field dark matter and boson stars) which has recently been motivated by a new geometric perspective by Bray. Wave dark matter describes dark matter as a scalar field which satisfies the Einstein-Klein-Gordon equations. These equations rely on a fundamental constant Upsilon (also known as the "mass term'' of the Klein-Gordon equation). Specifically, in this dissertation, we study spherically symmetric wave dark matter and compare these results with observations of dwarf spheroidal galaxies as a first attempt to compare the implications of the theory of wave dark matter with actual observations of dark matter. This includes finding a first estimate of the fundamental constant Upsilon. In the introductory Chapter 1, we present some preliminary background material to define and motivate the study of wave dark matter and describe some of the properties of dwarf spheroidal galaxies. In Chapter 2, we present several different ways of describing a spherically symmetric spacetime and the resulting metrics. We then focus our discussion on an especially useful form of the metric of a spherically symmetric spacetime in polar-areal coordinates and its properties. In particular, we show how the metric component functions chosen are extremely compatible with notions in Newtonian mechanics. We also show the monotonicity of the Hawking mass in these coordinates. Finally, we discuss how these coordinates and the metric can be used to solve the spherically symmetric Einstein-Klein-Gordon equations. In Chapter 3, we explore spherically symmetric solutions to the Einstein-Klein-Gordon equations, the defining equations of wave dark matter, where the scalar field is of the form f(t, r) = eiotF(r) for some constant o ∈ R and complex-valued function F(r). We show that the corresponding metric is static if and only if F( r) = h(r)eia for some constant alpha ∈ R and real-valued function h(r). We describe the
Sistemas Correctores de Campo Para EL Telescopio Cassegrain IAC80
NASA Astrophysics Data System (ADS)
Galan, M. J.; Cobos, F. J.
El proyecto de instrumentación de mayor importancia que ha tenido el Instituto de Astrofisica de Canarias en los últimos afios ha sido el diseflo y construcción del te1escopio IAC8O. Este requería del esfuerzo con junto en mec´nica, óptica y electrónica, lo que facilitó la estructuración y el crecimiento de los respectivos grupos de trabajo, que posteriormente se integraron en departamentos En su origen (1977), el telescopio IAC80 fue concebido como un sistema clásico tipo Cassegrain, con una razón focal F/i 1.3 para el sistema Casse grain y una razón focal F/20 para el sistema Coudé. Posteriormente, aunque se mantuvo la filosofia de que el sistema básico fuera el F/11.3, se consideró conveniente el diseño de secundarios para razones focales F/16 y F/32, y se eliminó el de F/20. Sin embargo, dada la importancia relativa que un foco estrictamente fotográfico tiene en un telescopio moderno, diseñado básicamente para fotometría fotoeléctrica y con un campo util mínimamente de 40 minutos de arco, se decídió Ilevar a cabo el diseño de un secundario F/8 con un sistema corrector de campo, pero que estuviera formado únicamente por lentes con superficies esféricas para que asl su construcción fuera posible en España ó en México. La creciente utilización de detectores bidimensionales para fines de investigación astron6mica y la viabilidad de que en un futuro cercano éstos tengan un área sensible cada vez mayor, hicieron atractiva la idea de tener diseñado un sistema corrector de campo para el foco primario (F/3), con un campo útil mínimo de un grado, y también con la limitante de que sus componentes tuvieron sólamente supérficies esféricas. Ambos diseños de los sis-temas correctores de campo se llevaron a cabo, en gran medida, como parte de un proyecto de colaboración e intercambio en el área de diseño y evaluación de sistemas ópticos.
Kit para aplicar la metodología de Lean en el gobierno
Este Kit para comenzar a aplicar la metodología Lean (Gobierno optimizado) ofrece información para ayudar a las agencias de protección ambiental a planificar e implementar iniciativas Lean exitosas.
Focal para-hisian atrial tachycardia with dual exits
Lawrance Jesuraj, M.; Sharada, K.; Sridevi, C.; Narasimhan, C.
Focal atrial tachycardias (AT) in the right atrium (RA) tend to cluster around the crista terminalis, coronary sinus (CS) region, tricuspid annulus, and para-hisian region. In most cases, the AT focus can be identified by careful activation mapping, and completely eliminated by radiofrequency (RF) catheter ablation. However, RF ablation near the His bundle (HB) carries a risk of inadvertent damage to the atrioventricular (AV) conduction system. Here we describe a patient with an AT originating in the vicinity of the AV node, which was successfully ablated earlier from non-coronary aortic cusp (NCC), and recurred with an exit from para-hisian location. Respiratory excursions of the catheter were associated with migration to the area of HIs. This was successfully ablated during controlled apnoea, using 3D electroanatomic mapping. PMID:23993015
Conversion of para and ortho hydrogen in the Jovian planets
NASA Technical Reports Server (NTRS)
Massie, S. T.; Hunten, D. M.
A mechanism is proposed which partially equilibrates the para and ortho rotational levels of molecular hydrogen in the atmospheres of Jupiter, Saturn, and Uranus. Catalytic reactions between the free-radical surface sites of aerosol particles and hydrogen modecules yield significant equilibration near 1 bar pressure, if the efficiency of conversion per collision is between 10 to the -8th and 10 to the -10th and the effective eddy mixing coefficient is 10,000 sq cm/sec. At lower pressures the ortho-para ratio retains the value at the top of the cloud layer, except for a very small effect from conversion in the thermosphere. The influence of conversion on the specific heat and adiabatic lapse rate is also investigated. The effect is found to be generally small, though is can rise to 10% inside the aerosol layer.
Para-acetabular periarthritis calcarea: its radiographic manifestations.
Kawashima, A; Murayama, S; Ohuchida, T; Russell, W J
On retrospective reviews of radiographs, periarthritis calcarea was distinguished from os acetabula by interval radiographic progression and regression. Among 59 men and 51 women, there were 137 instances of para-acetabular calcifications and ossifications, which were morphologically classified as 58 discrete, 58 amorphous, and 21 segmented types. Correlations with other radiographic abnormalities, symptoms, signs, and laboratory abnormalities were sought, but not established. Out of 93 serially imaged opacities, 90 changed, including 37 of the 40 instances (92.5%) of the discrete type and 53 instances (100%) of the amorphous and segmented types--due to periarthritis calcarea. At least 43 of 90 densities were newly developed. Mean age at first detection was 47.7 years. Three of the discrete densities were unchanged and represented os acetabula. Thus, recognition of para-acetabular periarthritis calcarea is not only of academic importance; it can facilitate proper treatment as well.
Synthesis of High Molecular Weight Para-Phenylene PBI
give high molecular weight m-phenylene PBI (Reference 7). The polymer was completely soluble in methanesulfonic acid and 98% formic acid . Polymer with...mono- mer is a white crystalline solid which can be quantitatively hydrolized in an acid medium to give the free TAB. Stoichiometric quantities of IX...WEIGHT "PARA"-PHENYLENE PBI TECHNICAL REPORT AFML-TR-74-199 NOVEMBER 1974 Distribution limited to U.S.Government agencies only, test and evaluation
Production Ratio for Para- and Ortho-Ps in Photodetachment of Ps^-
NASA Astrophysics Data System (ADS)
Igarashi, Akinori
Para- and ortho-Ps atoms are formed in the photodetachment of positronium negative ion. Since the lifetime against the pair annihilation is much shorter for para-Ps( ns) than for ortho-Ps( ns), the production ratio of para- and ortho-Ps atoms is important for the photodetachment experiments. We have derived the ratio explicitly.
Litewka, Sergio
La telemedicina es una tendencia creciente en la prestación de los servicios médicos. Aunque la eficacia de esta práctica no ha estado bien establecida, es probable que los países en desarrollo compartirán este nuevo paradigma con los desarrollados. Los defensores de la telemedicina en América Latina sostienen que será una herramienta útil para reducir las disparidades y mejorar la accesibilidad de atención de salud. Aunque América Latina quizá se convierta en un lugar para la investigación e investigación de estos procedimientos, no está claro cómo la telemedicina podría contribuir a mejorar la accesibilidad para las poblaciones desfavorecidas, o coexistir con sistemas de atención de salud públicos crónicamente enfermos.Telemedicine is a growing trend in the provision of medical services. Although the effectiveness of this practice has not been well established, it is likely that developing countries will share this new paradigm with developed ones. Supporters of telemedicine in Latin America maintain that it will be a useful tool for reducing disparities and improving health care accessibility. Although Latin America might become a place for research and investigation of these procedures, it is not clear how telemedicine could contribute to improving accessibility for disadvantaged populations, or coexist with chronically ill-funded public healthcare systems.
Para rubber seed oil: new promising unconventional oil for cosmetics.
Lourith, Nattaya; Kanlayavattanakul, Mayuree; Sucontphunt, Apirada; Ondee, Thunnicha
Para rubber seed was macerated in petroleum ether and n-hexane, individually, for 30 min. The extraction was additionally performed by reflux and soxhlet for 6 h with the same solvent and proportion. Soxhlet extraction by petroleum ether afforded the greatest extractive yield (22.90 ± 0.92%). Although antioxidant activity by means of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) assay was insignificantly differed in soxhleted (8.90 ± 1.15%) and refluxed (9.02 ± 0.71%) by n-hexane, soxhlet extraction by n-hexane was significantly (p < 0.05) potent scavenged 2,2'-azino-bis(3-ethylbenzothaiazoline)-6-sulfonic acid) or ABTS radical with trolox equivalent antioxidant capacity (TEAC) of 66.54 ± 6.88 mg/100 g oil. This extract was non cytotoxic towards normal human fibroblast cells. In addition, oleic acid and palmitic acid were determined at a greater content than in the seed of para rubber cultivated in Malaysia, although linoleic and stearic acid contents were not differed. This bright yellow extract was further evaluated on other physicochemical characters. The determined specific gravity, refractive index, iodine value, peroxide value and saponification value were in the range of commercialized vegetable oils used as cosmetic raw material. Therefore, Para rubber seed oil is highlighted as the promising ecological ingredient appraisal for cosmetics. Transforming of the seed that is by-product of the important industrial crop of Thailand into cosmetics is encouraged accordingly.
Surgical treatment of para-oesophageal hiatal hernia.
Rogers, M. L.; Duffy, J. P.; Beggs, F. D.; Salama, F. D.; Knowles, K. R.; Morgan, W. E.
The development of laparoscopic antireflux surgery has stimulated interest in laparoscopic para-oesophageal hiatal hernia repair. This review of our practice over 10 years using a standard transthoracic technique was undertaken to establish the safety and effectiveness of the open technique to allow comparison. Sixty patients with para-oesophageal hiatal hernia were operated on between 1989 and 1999. There were 38 women and 22 men with a median age of 69.5 years. There were 47 elective and 13 emergency presentations. Operation consisted of a left thoracotomy, hernia reduction and crural repair. An antireflux procedure was added in selected patients. There were no deaths among the elective cases and one among the emergency cases. Median follow-up time was 19 months. There was one recurrence (1.5%). Seven patients (12%) required a single oesophagoscopy and dilatation up to 2 years postoperatively but have been asymptomatic since. Two patients (3%) developed symptomatic reflux which has been well controlled on proton-pump inhibitors. Transthoracic para-oesophageal hernia repair can be safely performed with minimal recurrence. PMID:11777134
Litewka, Sergio
La telemedicina es una tendencia creciente en la prestación de los servicios médicos. Aunque la eficacia de esta práctica no ha estado bien establecida, es probable que los países en desarrollo compartirán este nuevo paradigma con los desarrollados. Los defensores de la telemedicina en América Latina sostienen que será una herramienta útil para reducir las disparidades y mejorar la accesibilidad de atención de salud. Aunque América Latina quizá se convierta en un lugar para la investigación e investigación de estos procedimientos, no está claro cómo la telemedicina podría contribuir a mejorar la accesibilidad para las poblaciones desfavorecidas, o coexistir con sistemas de atención de salud públicos crónicamente enfermos. Telemedicine is a growing trend in the provision of medical services. Although the effectiveness of this practice has not been well established, it is likely that developing countries will share this new paradigm with developed ones. Supporters of telemedicine in Latin America maintain that it will be a useful tool for reducing disparities and improving health care accessibility. Although Latin America might become a place for research and investigation of these procedures, it is not clear how telemedicine could contribute to improving accessibility for disadvantaged populations, or coexist with chronically ill-funded public healthcare systems. PMID:21625326
Studies on barium bis-para-nitrophenolate para-nitrophenol tetra hydrate NLO single crystal by unidirectional growth method
NASA Astrophysics Data System (ADS)
Uthrakumar, R.; Vesta, C.; Jose, M.; Sugandhi, K.; Krishnan, S.; Jerome Das, S.
The unidirectional crystal growth technique has been employed for the bulk growth of semi-organic nonlinear optical barium bis-para-nitrophenolate para-nitrophenol tetra hydrate single crystals along the (2 2 0) direction with almost high solute-crystal conversion efficiency. The grown crystal was subjected to single crystal and powder XRD analyses in order to confirm the crystal identity. Optical absorption studies reveal very high transmittance in the entire visible and near IR region. The presence of various functional groups is confirmed by FTIR analysis. Low dielectric loss at high frequency region is indicative of enhanced optical quality with lesser defects. Photoconductivity measurements carried out on the grown crystal reveal the negative photoconducting nature.
The Regulation of para-Nitrophenol Degradation in Pseudomonas putida DLL-E4.
Chen, Qiongzhen; Tu, Hui; Luo, Xue; Zhang, Biying; Huang, Fei; Li, Zhoukun; Wang, Jue; Shen, Wenjing; Wu, Jiale; Cui, Zhongli
Pseudomonas putida DLL-E4 can efficiently degrade para-nitrophenol and its intermediate metabolite hydroquinone. The regulation of para-nitrophenol degradation was studied, and PNP induced a global change in the transcriptome of P. putida DLL-E4. When grown on PNP, the wild-type strain exhibited significant downregulation of 2912 genes and upregulation of 845 genes, whereas 2927 genes were downregulated and 891 genes upregulated in a pnpR-deleted strain. Genes related to two non-coding RNAs (ins1 and ins2), para-nitrophenol metabolism, the tricarboxylic acid cycle, the outer membrane porin OprB, glucose dehydrogenase Gcd, and carbon catabolite repression were significantly upregulated when cells were grown on para-nitrophenol plus glucose. pnpA, pnpR, pnpC1C2DECX1X2, and pnpR1 are key genes in para-nitrophenol degradation, whereas pnpAb and pnpC1bC2bDbEbCbX1bX2b have lost the ability to degrade para-nitrophenol. Multiple components including transcriptional regulators and other unknown factors regulate para-nitrophenol degradation, and the transcriptional regulation of para-nitrophenol degradation is complex. Glucose utilization was enhanced at early stages of para-nitrophenol supplementation. However, it was inhibited after the total consumption of para-nitrophenol. The addition of glucose led to a significant enhancement in para-nitrophenol degradation and up-regulation in the expression of genes involved in para-nitrophenol degradation and carbon catabolite repression (CCR). It seemed that para-nitrophenol degradation can be regulated by CCR, and relief of CCR might contribute to enhanced para-nitrophenol degradation. In brief, the regulation of para-nitrophenol degradation seems to be controlled by multiple factors and requires further study.
The Regulation of para-Nitrophenol Degradation in Pseudomonas putida DLL-E4
Chen, Qiongzhen; Tu, Hui; Luo, Xue; Zhang, Biying; Huang, Fei; Li, Zhoukun; Wang, Jue; Shen, Wenjing; Wu, Jiale; Cui, Zhongli
Pseudomonas putida DLL-E4 can efficiently degrade para-nitrophenol and its intermediate metabolite hydroquinone. The regulation of para-nitrophenol degradation was studied, and PNP induced a global change in the transcriptome of P. putida DLL-E4. When grown on PNP, the wild-type strain exhibited significant downregulation of 2912 genes and upregulation of 845 genes, whereas 2927 genes were downregulated and 891 genes upregulated in a pnpR-deleted strain. Genes related to two non-coding RNAs (ins1 and ins2), para-nitrophenol metabolism, the tricarboxylic acid cycle, the outer membrane porin OprB, glucose dehydrogenase Gcd, and carbon catabolite repression were significantly upregulated when cells were grown on para-nitrophenol plus glucose. pnpA, pnpR, pnpC1C2DECX1X2, and pnpR1 are key genes in para-nitrophenol degradation, whereas pnpAb and pnpC1bC2bDbEbCbX1bX2b have lost the ability to degrade para-nitrophenol. Multiple components including transcriptional regulators and other unknown factors regulate para-nitrophenol degradation, and the transcriptional regulation of para-nitrophenol degradation is complex. Glucose utilization was enhanced at early stages of para-nitrophenol supplementation. However, it was inhibited after the total consumption of para-nitrophenol. The addition of glucose led to a significant enhancement in para-nitrophenol degradation and up-regulation in the expression of genes involved in para-nitrophenol degradation and carbon catabolite repression (CCR). It seemed that para-nitrophenol degradation can be regulated by CCR, and relief of CCR might contribute to enhanced para-nitrophenol degradation. In brief, the regulation of para-nitrophenol degradation seems to be controlled by multiple factors and requires further study. PMID:27191401
Faure, A.; Hily-Blant, P.; Le Gal, R.; Rist, C.
The ortho-para chemistry of ammonia in the cold interstellar medium is investigated using a gas-phase chemical network. Branching ratios for the primary reaction chain involved in the formation and destruction of ortho- and para-NH{sub 3} were derived using angular momentum rules based on the conservation of the nuclear spin. We show that the 'anomalous' ortho-to-para ratio of ammonia ({approx}0.7) observed in various interstellar regions is in fact consistent with nuclear spin selection rules in a para-enriched H{sub 2} gas. This ratio is found to be independent of temperature in the range 5-30 K. We also predict an ortho-to-para ratio of {approx}2.3 for NH{sub 2}. We conclude that a low ortho-to-para ratio of H{sub 2} naturally drives the ortho-to-para ratios of nitrogen hydrides below the statistical values.
Amazon Land Wars in the South of Para
NASA Technical Reports Server (NTRS)
Simmons, Cynthia S.; Walker, Robert T.; Arima, Eugenio Y.; Aldrich, Stephen P.; Caldas, Marcellus M.
The South of Para, located in the heart of the Brazilian Amazon, has become notorious for violent land struggle. Although land conflict has a long history in Brazil, and today impacts many parts of the country, violence is most severe and persistent here. The purpose of this article is to examine why. Specifically, we consider how a particular Amazonian place, the so-called South of Para has come to be known as Brazil's most dangerous badland. We begin by considering the predominant literature, which attributes land conflict to the frontier expansion process with intensified struggle emerging in the face of rising property values and demand for private property associated with capitalist development. From this discussion, we distill a concept of the frontier, based on notions of property rights evolution and locational rents. We then empirically test the persistence of place-based violence in the region, and assess the frontier movement through an analysis of transportation costs. The findings from the analyses indicate that the prevalent theorization of frontier violence in Amazonia does little to explain its persistent and pervasive nature in the South of Para. To fill this gap in understanding, we develop an explanation based the geographic conception of place, and we use contentious politics theory heuristically to elucidate the ways in which general processes interact with place specific history to engender a landscape of violence. In so doing, we focus on environmental, cognitive, and relational mechanisms (and implicated structures), and attempt to deploy them in an explanatory framework that allows direct observation of the accumulating layers of the region's tragic history. We end by placing our discussion within a political ecological context, and consider the implications of the Amazon Land War for the environment.
Miner, Sarah; Poupin, Lauren; Bernales, Margarita; Ferrer, Lilian; Cianelli, Rosina
RESUMEN En Chile se estima que aproximadamente 38 mil personas viven con el Virus de Inmunodeficiencia Humana [VIH]. En el año 2001, 1.092 mujeres chilenas vivían con VIH, actualmente se cree que hay más de 7.600 mujeres con el virus. Frente a estas cifras surge la necesidad de crear estrategias de prevención dirigidas a mujeres chilenas. Objetivo analizar los estudios ya realizados en la prevención de VIH para determinar qué aspectos se deben incluir en programas exitosos de prevención de VIH en mujeres. Diseño y Método se realizó una revisión de la literatura utilizando la base de datos Proquest, CINAHL, Pubmed y Scielo. Los límites comprendieron: textos completos, de los últimos 10 años, de acceso gratuito y escrito en español o inglés. Se seleccionaron 15 artículos para la revisión. Resultados todos los artículos comprenden la evaluación del efecto de una intervención sobre conocimiento y conductas relacionadas con VIH/SIDA. Catorce muestran resultados significativos en cambios positivos de conducta o conocimientos relacionados con la prevención de VIH. Conclusiones los programas de prevención de VIH en mujeres pueden ser efectivos para lograr cambios de conducta y de conocimiento. Las intervenciones exitosas son aquellas basadas en teorías o modelos de prevención y en cambios de conductas, todas adaptadas a la cultura de la población estudiada. PMID:27667897
Para-hydrogen narrow filament evaporation at low temperature
NASA Astrophysics Data System (ADS)
Elizarova, T. G.; Gogolin, A. A.; Montero, S.
Undercooling of liquid para-hydrogen (pH2) below its freezing point at equilibrium (13.8 K) has been shown recently in flowing micro-filaments evaporating in low density background gas [M. Kühnel et al, Phys. Rev. Lett. 106, 245301 (2011)]. An hydrodynamical model accounting for this process is reported here. Analytical expressions for the local temperature T of a filament, averaged over its cross section, are obtained as a function of distance z to the nozzle. Comparison with the experiment is shown. It is shown also that the thermocapillary forces induce a parabolic profile of velocity across the jet.
RVA: A Plugin for ParaView 3.14
RVA is a plugin developed for the 64-bit Windows version of the ParaView 3.14 visualization package. RVA is designed to provide support in the visualization and analysis of complex reservoirs being managed using multi-fluid EOR techniques. RVA, for Reservoir Visualization and Analysis, was developed at the University of Illinois at Urbana-Champaign, with contributions from the Illinois State Geological Survey, Department of Computer Science and National Center for Supercomputing Applications. RVA was designed to utilize and enhance the state-of-the-art visualization capabilities within ParaView, readily allowing joint visualization of geologic framework and reservoir fluid simulation model results. Particular emphasis was placed on enabling visualization and analysis of simulation results highlighting multiple fluid phases, multiple properties for each fluid phase (including flow lines), multiple geologic models and multiple time steps. Additional advanced functionality was provided through the development of custom code to implement data mining capabilities. The built-in functionality of ParaView provides the capacity to process and visualize data sets ranging from small models on local desktop systems to extremely large models created and stored on remote supercomputers. The RVA plugin that we developed and the associated User Manual provide improved functionality through new software tools, and instruction in the use of ParaView-RVA, targeted to petroleum engineers and geologists in industry and research. The RVA web site (http://rva.cs.illinois.edu) provides an overview of functions, and the development web site (https://github.com/shaffer1/RVA) provides ready access to the source code, compiled binaries, user manual, and a suite of demonstration data sets. Key functionality has been included to support a range of reservoirs visualization and analysis needs, including: sophisticated connectivity analysis, cross sections through simulation results between
Biodegradation of Para Amino Acetanilide by Halomonas sp. TBZ3
Hajizadeh, Nader; Sefidi Heris, Youssof; Zununi Vahed, Sepideh; Vallipour, Javad; Hejazi, Mohammad Amin; Golabi, Sayyed Mahdi; Asadpour-Zeynali, Karim; Hejazi, Mohammad Saeid
Background: Aromatic compounds are known as a group of highly persistent environmental pollutants. Halomonas sp. TBZ3 was isolated from the highly salty Urmia Lake of Iran. In this study, characterization of a new Halomonas isolate called Halomonas sp. TBZ3 and its employment for biodegradation of para-amino acetanilide (PAA), as an aromatic environmental pollutant, is described. Objectives: This study aimed to characterize the TBZ3 isolate and to elucidate its ability as a biodegradative agent that decomposes PAA. Materials and Methods: Primarily, DNA-DNA hybridization between TBZ3, Halomonas denitrificans DSM18045T and Halomonas saccharevitans LMG 23976T was carried out. Para-amino acetanilide biodegradation was assessed using spectrophotometry and confirmed by gas chromatography-mass spectroscopy (GC-MS). Parameters effective on biodegradation of PAA were optimized by the Response Surface Methodology (RSM). Results: The DNA-DNA hybridization experiments between isolate TBZ3, H. denitrificans and H. saccharevitans revealed relatedness levels of 57% and 65%, respectively. According to GC-MS results, TBZ3 degrades PAA to benzene, hexyl butanoate, 3-methyl-1-heptanol and hexyl hexanoate. Temperature 32.92°C, pH 6.76, and salinity 14% are the optimum conditions for biodegradation with a confidence level of 95% (at level α = 0.05). Conclusions: According to our results, Halomonas sp. TBZ3 could be considered as a biological agent for bioremediation of PAA and possibly other similar aromatic compounds. PMID:26495103
CYP96T1 of Narcissus sp. aff. pseudonarcissus Catalyzes Formation of the Para-Para' C-C Phenol Couple in the Amaryllidaceae Alkaloids
Kilgore, Matthew B.; Augustin, Megan M.; May, Gregory D.; Crow, John A.; Kutchan, Toni M.
The Amaryllidaceae alkaloids are a family of amino acid derived alkaloids with many biological activities; examples include haemanthamine, haemanthidine, galanthamine, lycorine, and maritidine. Central to the biosynthesis of the majority of these alkaloids is a C-C phenol-coupling reaction that can have para-para', para-ortho', or ortho-para' regiospecificity. Through comparative transcriptomics of Narcissus sp. aff. pseudonarcissus, Galanthus sp., and Galanthus elwesii we have identified a para-para' C-C phenol coupling cytochrome P450, CYP96T1, capable of forming the products (10bR,4aS)-noroxomaritidine and (10bS,4aR)-noroxomaritidine from 4′-O-methylnorbelladine. CYP96T1 was also shown to catalyzed formation of the para-ortho' phenol coupled product, N-demethylnarwedine, as less than 1% of the total product. CYP96T1 co-expresses with the previously characterized norbelladine 4′-O-methyltransferase. The discovery of CYP96T1 is of special interest because it catalyzes the first major branch in Amaryllidaceae alkaloid biosynthesis. CYP96T1 is also the first phenol-coupling enzyme characterized from a monocot. PMID:26941773
CYP96T1 of Narcissus sp. aff. pseudonarcissus Catalyzes Formation of the Para-Para' C-C Phenol Couple in the Amaryllidaceae Alkaloids.
Kilgore, Matthew B; Augustin, Megan M; May, Gregory D; Crow, John A; Kutchan, Toni M
The Amaryllidaceae alkaloids are a family of amino acid derived alkaloids with many biological activities; examples include haemanthamine, haemanthidine, galanthamine, lycorine, and maritidine. Central to the biosynthesis of the majority of these alkaloids is a C-C phenol-coupling reaction that can have para-para', para-ortho', or ortho-para' regiospecificity. Through comparative transcriptomics of Narcissus sp. aff. pseudonarcissus, Galanthus sp., and Galanthus elwesii we have identified a para-para' C-C phenol coupling cytochrome P450, CYP96T1, capable of forming the products (10bR,4aS)-noroxomaritidine and (10bS,4aR)-noroxomaritidine from 4'-O-methylnorbelladine. CYP96T1 was also shown to catalyzed formation of the para-ortho' phenol coupled product, N-demethylnarwedine, as less than 1% of the total product. CYP96T1 co-expresses with the previously characterized norbelladine 4'-O-methyltransferase. The discovery of CYP96T1 is of special interest because it catalyzes the first major branch in Amaryllidaceae alkaloid biosynthesis. CYP96T1 is also the first phenol-coupling enzyme characterized from a monocot.
Crystal growth and DFT insight on sodium para-nitrophenolate para-nitrophenol dihydrate single crystal for NLO applications
NASA Astrophysics Data System (ADS)
Selvakumar, S.; Boobalan, Maria Susai; Anthuvan Babu, S.; Ramalingam, S.; Leo Rajesh, A.
Single crystals of sodium para-nitrophenolate para-nitrophenol dihydrate (SPPD) were grown by slow evaporation technique and its structure has been studied by FT-IR, FT-Raman and single crystal X-ray diffraction techniques. The optical and electrical properties were characterized by UV-Vis spectrum, and dielectric studies respectively. SPPD was thermally stable up to 128 °C as determined by TG-DTA curves. Using the Kurtz-Perry powder method, the second-harmonic generation efficiency was found to be five times to that of KDP. Third-order nonlinear response was studied using Z-scan technique with a He-Ne laser (632.8 nm) and NLO parameters such as intensity dependent refractive index, nonlinear absorption coefficient and third-order susceptibility were also estimated. The molecular geometry from X-ray experiment in the ground state has been compared using density functional theory (DFT) with appropriate basis set. The first-order hyperpolarizability also calculated using DFT approaches. Stability of the molecule arising from hyperconjugative interactions leading to its nonlinear optical activity and charge delocalization were analyzed using natural bond orbital technique. HOMO-LUMO energy gap value suggests the possibility of charge transfer within the molecule. Based on optimized ground state geometries, Natural bond orbital (NBO) analysis was performed to study donor-acceptor interactions.
Oropouche Virus. 3. Entomological Observations from Three Epidemics in Para, Brazil, 1975,
by block number) OROPOUCHE VIRUS, CULICOIDES PARAENSIS, EPIDEMICS, BRAZIL, PARA I&2 ABSThAC (Cantmus = revers e e* I nessamy and idewtty by block nmbe...8217)URBAN EPIDEMTCS OF OROPOUCHE ORO FEVER IN THREE MUNICIPALITIES IN PARA, BR.tZIL WERE SrUDIED IN 1975. CULICOIDES PARAENSIS GOELDI WERE COLLECTED...Urban epidemics of Oropouche (ORO) fever in three municipalities in Para, Brazil were studied in 1975. Culicoides paraensis (Goeldi) were collected during
Ortho- and para-hydrogen in dense clouds, protoplanets, and planetary atmospheres
NASA Technical Reports Server (NTRS)
Decampli, W. M.; Cameron, A. G. W.; Bodenheimer, P.; Black, D. C.
If ortho- and para-hydrogen achieve a thermal ratio on dynamical time scales in a molecular hydrogen cloud, then the specific heat is high enough in the temperature range 35-70 K to possibly induce hydrodynamic collapse. The ortho-para ratio in many interstellar cloud fragments is expected to meet this condition. The same may have been true for the primitive solar nebula. Detailed hydrodynamic and hydrostatic calculations are presented that show the effects of the assumed ortho-para ratio on the evolution of Jupiter during its protoplanetary phase. Some possible consequences of a thermalized ortho-para ratio in the atmospheres of the giant planets are also discussed.
Luttinger parameter of quasi-one-dimensional para -H2
NASA Astrophysics Data System (ADS)
Ferré, G.; Gordillo, M. C.; Boronat, J.
We have studied the ground-state properties of para-hydrogen in one dimension and in quasi-one-dimensional configurations using the path-integral ground-state Monte Carlo method. This method produces zero-temperature exact results for a given interaction and geometry. The quasi-one-dimensional setup has been implemented in two forms: the inner channel inside a carbon nanotube coated with H2 and a harmonic confinement of variable strength. Our main result is the dependence of the Luttinger parameter on the density within the stable regime. Going from one dimension to quasi-one dimension, keeping the linear density constant, produces a systematic increase of the Luttinger parameter. This increase is, however, not enough to reach the superfluid regime and the system always remain in the quasicrystal regime, according to Luttinger liquid theory.
ParaText : scalable text analysis and visualization.
Dunlavy, Daniel M.; Stanton, Eric T.; Shead, Timothy M.
Automated analysis of unstructured text documents (e.g., web pages, newswire articles, research publications, business reports) is a key capability for solving important problems in areas including decision making, risk assessment, social network analysis, intelligence analysis, scholarly research and others. However, as data sizes continue to grow in these areas, scalable processing, modeling, and semantic analysis of text collections becomes essential. In this paper, we present the ParaText text analysis engine, a distributed memory software framework for processing, modeling, and analyzing collections of unstructured text documents. Results on several document collections using hundreds of processors are presented to illustrate the exibility, extensibility, and scalability of the the entire process of text modeling from raw data ingestion to application analysis.
Electron impact ionization dynamics of para-benzoquinone
NASA Astrophysics Data System (ADS)
Jones, D. B.; Ali, E.; Ning, C. G.; Colgan, J.; Ingólfsson, O.; Madison, D. H.; Brunger, M. J.
Triple differential cross sections (TDCSs) for the electron impact ionization of the unresolved combination of the 4 highest occupied molecular orbitals (4b3g, 5b2u, 1b1g, and 2b3u) of para-benzoquinone are reported. These were obtained in an asymmetric coplanar geometry with the scattered electron being observed at the angles -7.5°, -10.0°, -12.5° and -15.0°. The experimental cross sections are compared to theoretical calculations performed at the molecular 3-body distorted wave level, with a marginal level of agreement between them being found. The character of the ionized orbitals, through calculated momentum profiles, provides some qualitative interpretation for the measured angular distributions of the TDCS.
Nuevos sistemas de frecuencia intermedia para el IAR
NASA Astrophysics Data System (ADS)
Olalde, J. C.; Perilli, D.; Larrarte, J. J.
Se presenta el diagrama en bloques de los nuevos sistemas de Frecuencia Intermedia para los dos radiómetros instalados en el IAR. Entre las características más importantes del sistema podemos mencionar la posibilidad de conectar cualquiera de las dos antenas a los ``backend" disponibles: analizador espectral de alta resolución (META II) de 0,05 Hz, autocorrelador de 1008 canales y contínuo. Se incorporan al sistema nuevos sintetizadores de frecuencia implementados con PLL y la moderna técnica de síntesis digital directa. Por último, el conjunto del sistema es susceptible de ser configurado por las computadoras de adquisición de datos, supervisadas por otra, que entrega el estado de funcionamiento actual y evita la selección de configuraciones incorrectas por parte del usuario.
Para-phenylenediamine allergy: current perspectives on diagnosis and management
Mukkanna, Krishna Sumanth; Stone, Natalie M; Ingram, John R
Para-phenylenediamine (PPD) is the commonest and most well-known component of hair dyes. Oxidative hair dyes and dark henna temporary tattoos contain PPD. Individuals may be sensitized to PPD by temporary henna tattooing in addition to dyeing their hair. PPD allergy can cause severe reactions and may result in complications. In recent years, frequency of positive patch test reactions to PPD has been increasing. Cross-sensitization to other contact allergens may occur, in particular to other hair dye components. Hairdressers are at a high risk for PPD allergy and require counseling regarding techniques to minimize exposure and protective measures while handling hair dye. We focus this review on the current perspectives of diagnosis and management of PPD allergy. PMID:28176912
Pneumatic protection applied to an airbag for para-gliders
NASA Astrophysics Data System (ADS)
Raievski, V.; Valladas, G.
We present a theory of pneumatic protection based on the laws of thermodynamics, elasticity and fluid mechanics. A general pneumatic protection system is made up of several communicating compartments, the differences in pressure of the compartments generating a transfer of mass and energy between them. The transfer offers interesting possibilities to improve the performance of the system. An example of this type of protection in aerial sport is the airbag for para-gliders, it is used in this paper to illustrate the theory. As the pressure in the airbag depends uniquely on its volume, the geometric model in the theory can be simplified. Experiments carried out with crash-test dummies equipped with sensors have confirmed the theoretical predictions.
Para-Hydrogen-Enhanced Gas-Phase Magnetic Resonance Imaging
Bouchard, Louis-S.; Kovtunov, Kirill V.; Burt, Scott R.; Anwar,M. Sabieh; Koptyug, Igor V.; Sagdeev, Renad Z.; Pines, Alexander
Herein, we demonstrate magnetic resonance imaging (MRI) inthe gas phase using para-hydrogen (p-H2)-induced polarization. A reactantmixture of H2 enriched in the paraspin state and propylene gas is flowedthrough a reactor cell containing a heterogenized catalyst, Wilkinson'scatalyst immobilized on modified silica gel. The hydrogenation product,propane gas, is transferred to the NMR magnet and is spin-polarized as aresult of the ALTADENA (adiabatic longitudinal transport and dissociationengenders net alignment) effect. A polarization enhancement factor of 300relative to thermally polarized gas was observed in 1D1H NMR spectra.Enhancement was also evident in the magnetic resonance images. This isthe first demonstration of imaging a hyperpolarized gaseous productformed in a hydrogenation reaction catalyzed by a supported catalyst.This result may lead to several important applications, includingflow-through porous materials, gas-phase reaction kinetics and adsorptionstudies, and MRI in low fields, all using catalyst-free polarizedfluids.
The Ratio of Ortho- to Para-H2 in Photodissociation Regions
NASA Technical Reports Server (NTRS)
Sternberg, Amiel; Neufeld, David A.
We discuss the ratio of ortho- to para-H2 in photodissociation regions (PDRs). We draw attention to an apparent confusion in the literature between the ortho-to-para ratio of molecules in FUV-pumped vibrationally excited states and the total H2 ortho-to-para abundance ratio. These ratios are not the same because the process of FUV pumping of fluorescent H2 emission in PDRs occurs via optically thick absorption lines. Thus gas with an equilibrium ratio of ortho- to para-H2 equal to 3 will yield FUV-pumped vibrationally excited ortho-to-para ratios smaller than 3, because the ortho-H2 pumping rates are preferentially reduced by optical depth effects. Indeed, if the ortho and para pumping lines are on the "square root" part of the curve of growth, then the expected ratio of ortho and para vibrational line strengths is 3(sup 1/2) approximately 1.7, close to the typically observed value. Thus, contrary to what has sometimes been stated in the literature, most previous measurements of the ratio of ortho- to para-H2 in vibrationally excited states are entirely consistent with a total ortho-to-para ratio of 3, the equilibrium value for temperatures greater than 200 K. We present an analysis and several detailed models that illustrate the relationship between the total ratios of ortho- to para-H2 and the vibrationally excited ortho-to-para ratios in PDRs. Recent Infrared Space Observatory measurements of pure rotational and vibrational H2 emissions from the PDR in the star-forming region S140 provide strong observational support for our conclusions.
Ortho-para mixing hyperfine interaction in the H2O+ ion and nuclear spin equilibration.
Tanaka, Keiichi; Harada, Kensuke; Oka, Takeshi
The ortho to para conversion of water ion, H2O(+), due to the interaction between the magnetic moments of the unpaired electron and protons has been theoretically studied to calculate the spontaneous emission lifetime between the ortho- and para-levels. The electron spin-nuclear spin interaction term, Tab(SaΔIb + SbΔIa) mixes ortho (I = 1) and para (I = 0) levels to cause the "forbidden" ortho to para |ΔI| = 1 transition. The mixing term with Tab = 72.0 MHz is 4 orders of magnitude higher for H2O(+) than for its neutral counterpart H2O where the magnetic field interacting with proton spins is by molecular rotation rather than the free electron. The resultant 10(8) increase of ortho to para conversion rate possibly makes the effect of conversion in H2O(+) measurable in laboratories and possibly explains the anomalous ortho to para ratio recently reported by Herschel heterodyne instrument for the far-infrared (HIFI) observation. Results of our calculations show that the ortho ↔ para mixings involving near-degenerate ortho and para levels are high (∼10(-3)), but they tend to occur at high energy levels, ∼300 K. Because of the rapid spontaneous emission, such high levels are not populated in diffuse clouds unless the radiative temperature of the environment is very high. The low-lying 101 (para) and 111 (ortho) levels of H2O(+) are mixed by ∼10(-4) making the spontaneous emission lifetime for the para 101 → ortho 000 transition 520 years and 5200 years depending on the F value of the hyperfine structure. Thus the ortho ↔ para conversion due to the unpaired electron is not likely to seriously affect thermalization of interstellar H2O(+) unless either the radiative temperature is very high or number density of the cloud is very low.
The parA resolvase performs site-specific genomic excision in Arabidopsis
Technology Transfer Automated Retrieval System (TEKTRAN)
We have designed a site-specific excision detection system in Arabidopsis to study the in planta activity of the small serine recombinase ParA. Using a transient expression assay as well as stable transgenic plant lines, we show that the ParA recombinase is catalytically active and capable of perfo...
Primer registro para Peru del genero Nielsonia Young, 1977 (Hemiptera: Cicadellidae: Cicadellinae: Cicadellini)
Technology Transfer Automated Retrieval System (TEKTRAN)
En este articulo se reporta por primera vez para el Peru una especies del genero Nielsonia Young, 1977, de material procedente del Departamento de Tumbes. El genero ha sido reportada anteriormente de Ecuador, como unico registro para Sudamerica, y America Central. El unico especimen hembra encontra...
Tunnelling of relativistic particles from new type black hole in new massive gravity
Gecim, Ganim; Sucu, Yusuf E-mail: email@example.com
In the framework of the three dimensional New Massive Gravity theory introduced by Bergshoeff, Hohm and Townsend, we analyze the behavior of relativistic spin-1/2 and spin-0 particles in the New-type Black Hole backgroud, solution of the New Massive Gravity.We solve Dirac equation for spin-1/2 and Klein-Gordon equation for spin-0. Using Hamilton-Jacobi method, we discuss tunnelling probability and Hawking temperature of the spin-1/2 and spin-0 particles for the black hole. We observe that the tunnelling probability and Hawking temperature are same for the spin-1/2 and spin-0.
Partially Strong Transparency Conditions and a Singular Localization Method In Geometric Optics
NASA Astrophysics Data System (ADS)
Lu, Yong; Zhang, Zhifei
This paper focuses on the stability analysis of WKB approximate solutions in geometric optics with the absence of strong transparency conditions under the terminology of Joly, Métivier and Rauch. We introduce a compatible condition and a singular localization method which allows us to prove the stability of WKB solutions over long time intervals. This compatible condition is weaker than the strong transparency condition. The singular localization method allows us to do delicate analysis near resonances. As an application, we show the long time approximation of Klein-Gordon equations by Schrödinger equations in the non-relativistic limit regime.
Application of the three-dimensional telegraph equation to cosmic-ray transport
NASA Astrophysics Data System (ADS)
Tautz, Robert C.; Lerche, Ian
An analytical solution to the three-dimensional telegraph equation is presented. This equation has recently received some attention but so far the treatment has been one-dimensional. By using the structural similarity to the Klein-Gordon equation, the telegraph equation can be solved in closed form. Illustrative examples are used to discuss the qualitative differences from the diffusion solution. A comparison with a numerical test-particle simulation reveals that some features of an intensity profile can be better explained using the telegraph approach.
Spinning Kerr black holes with stationary massive scalar clouds: the large-coupling regime
NASA Astrophysics Data System (ADS)
Hod, Shahar
We study analytically the Klein-Gordon wave equation for stationary massive scalar fields linearly coupled to spinning Kerr black holes. In particular, using the WKB approximation, we derive a compact formula for the discrete spectrum of scalar field masses which characterize the stationary composed Kerr-black-hole-massive-scalar-field configurations in the large-coupling regime M μ ≫ 1 (here M and μ are respectively the mass of the central black hole and the proper mass of the scalar field). We confirm our analytically derived formula for the Kerr-scalar-field mass spectrum with numerical data that recently appeared in the literature.
A relativistic quantum oscillator subject to a Coulomb-type potential induced by effects of the violation of the Lorentz symmetry
NASA Astrophysics Data System (ADS)
Vitória, R. L. L.; Belich, H.; Bakke, K.
We consider a background of the violation of the Lorentz symmetry determined by the tensor (KF)_{μναβ} which governs the Lorentz symmetry violation out of the Standard Model Extension, where this background gives rise to a Coulomb-type potential, and then, we analyse its effects on a relativistic quantum oscillator. Furthermore, we analyse the behaviour of the relativistic quantum oscillator under the influence of a linear scalar potential and this background of the Lorentz symmetry violation. We show in both cases that analytical solutions to the Klein-Gordon equation can be achieved.
Superradiance of a charged scalar field coupled to the Einstein-Maxwell equations
NASA Astrophysics Data System (ADS)
Baake, Olaf; Rinne, Oliver
We consider the Einstein-Maxwell-Klein-Gordon equations for a spherically symmetric scalar field scattering off a Reissner-Nordström black hole in asymptotically flat spacetime. The equations are solved numerically using a hyperboloidal evolution scheme. For suitable frequencies of the initial data, superradiance is observed, leading to a substantial decrease of mass and charge of the black hole. We also derive a Bondi mass loss formula using the Kodama vector field and investigate the late-time decay of the scalar field.
Global Solutions to Repulsive Hookean Elastodynamics
NASA Astrophysics Data System (ADS)
Hu, Xianpeng; Masmoudi, Nader
The global existence of classical solutions to the three dimensional repulsive Hookean elastodynamics around an equilibrium is considered. By linearization and Hodge's decomposition, the compressible part of the velocity, the density, and the compressible part of the transpose of the deformation gradient satisfy Klein-Gordon equations with speed {√{2}}, while the incompressible parts of the velocity and of the transpose of the deformation gradient satisfy wave equations with speed one. The space-time resonance method combined with the vector field method is used in a novel way to obtain the decay of the solution and hence global existence.
Stationary charged scalar clouds around black holes in string theory
NASA Astrophysics Data System (ADS)
Bernard, Canisius
It was reported that Kerr-Newman black holes can support linear charged scalar fields in their exterior regions. These stationary massive charged scalar fields can form bound states, which are called stationary scalar clouds. In this paper, we show that Kerr-Sen black holes can also support stationary massive charged scalar clouds by matching the near- and far-region solutions of the radial part of the Klein-Gordon wave equation. We also review stationary scalar clouds within the background of static electrically charged black hole solutions in the low-energy limit of heterotic string field theory, namely, the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black holes.
Nonexistence of small, odd breathers for a class of nonlinear wave equations
NASA Astrophysics Data System (ADS)
Kowalczyk, Michał; Martel, Yvan; Muñoz, Claudio
In this note, we show that for a large class of nonlinear wave equations with odd nonlinearities, any globally defined odd solution which is small in the energy space decays to 0 in the local energy norm. In particular, this result shows nonexistence of small, odd breathers for some classical nonlinear Klein Gordon equations, such as the sine-Gordon equation and φ ^4 and φ ^6 models. It also partially answers a question of Soffer and Weinstein (Invent Math 136(1): 9-74, p 19 1999) about nonexistence of breathers for the cubic NLKG in dimension one.
Time-dependent scalar fields as candidates for dark matter
NASA Astrophysics Data System (ADS)
Malakolkalami, B.; Mahmoodzadeh, A.
In this paper, we study some properties of what is called the oscillaton, a spherically symmetric object made of a real time-dependent scalar field. Using an exponential scalar potential instead of a quadratic one discussed in previous works, as a new choice, we investigate the oscillaton properties with this potential. Solving the differential equation system resulting from the Einstein-Klein-Gordon equations reveals the importance of the oscillatons as candidates for dark matter. Meanwhile, a simplification called the stationary limit procedure is also carried out.
Hawking Radiation of Scalar and Vector Particles from 5D Myers-Perry Black Holes
NASA Astrophysics Data System (ADS)
Jusufi, Kimet; Övgün, Ali
In the present paper we explore the Hawking radiation as a quantum tunneling effect from a rotating 5 dimensional Myers-Perry black hole (5D-MPBH) with two independent angular momentum components. First, we investigate the Hawking temperature by considering the tunneling of massive scalar particles and spin-1 vector particles from the 5D-MPBH in the Painlevé coordinates and then in the corotating frames. More specifically, we solve the Klein-Gordon and Proca equations by applying the WKB method and Hamilton-Jacobi equation in both cases. Finally, we recover the Hawking temperature and show that coordinates systems do not affect the Hawking temperature.
Evolution and stability Φ4 oscillatons
NASA Astrophysics Data System (ADS)
Ureña-López, L. Arturo; Valdez-Alvarado, Susana; Becerril, Ricardo
We solve numerically the Einstein-Klein-Gordon (EKG) system, assuming spherical symmetry, for a real scalar field endowed with a quartic self-interaction potential, and obtain the so-called oscillatons: oscillating soliton stars. We obtain the equilibrium configurations for Φ4oscillatons. Also, we analyze numerically the evolution of the EKG equations to study the stability of such oscillatons. We present the influence of the quartic potential on the behavior of both the stable (S-oscillatons) and unstable (U-oscillatons) branches, under the influence of small and large radial perturbations.
Thermal corrections to the Casimir energy in a general weak gravitational field
NASA Astrophysics Data System (ADS)
Nazari, Borzoo
We calculate finite temperature corrections to the energy of the Casimir effect of a two conducting parallel plates in a general weak gravitational field. After solving the Klein-Gordon equation inside the apparatus, mode frequencies inside the apparatus are obtained in terms of the parameters of the weak background. Using Matsubara's approach to quantum statistical mechanics gravity-induced thermal corrections of the energy density are obtained. Well-known weak static and stationary gravitational fields are analyzed and it is found that in the low temperature limit the energy of the system increases compared to that in the zero temperature case.
Tortoise Coordinates and Hawking Radiation in a Dynamical Spherically Symmetric Spacetime
NASA Astrophysics Data System (ADS)
Yang, Jian; Zhao, Zheng; Tian, Gui-Hua; Liu, Wen-Biao
Hawking effect from dynamical spherical Vaidya black hole, Vaidya-Bonner black hole, and Vaidya-de Sitter black hole is investigated using the improved Damour-Ruffini method. After the new tortoise coordinate transformation in which the position r of event horizon is an undetermined function and the temperature parameter κ is an undetermined constant, the Klein-Gordon equation can be written as the standard form at the event horizon, and both r and κ can be determined automatically. Then extending the outgoing wave from outside to inside of the horizon analytically, the Hawking temperature can also be obtained automatically.
New tortoise coordinate transformation and Hawking's radiation in de Sitter space
NASA Astrophysics Data System (ADS)
Ibohal, N.; Ibungochouba, T.
Hawking's radiation effect of Klein-Gordon equation, Dirac particles and Maxwell's electromagnetic fields in the non-stationary rotating de Sitter cosmological space-time is investigated by using a new method of generalized tortoise coordinate transformation. It is found that the new transformation produces constant additional terms in the expressions of the surface gravities and the Hawking's temperatures. If the constant terms are set to zero, then the surface gravities and Hawking's temperatures will be equal to those obtained from the old generalized tortoise coordinate transformations. This shows that the new transformations are more reasonable. The Fermionic spectrum of Dirac particles displays a new spin-rotation coupling effect.
MAPLE Procedures For Boson Fields System On Curved Space - Time
Murariu, Gabriel
Systems of interacting boson fields are an important subject in the last years. From the problem of dark matter to boson stars' study, boson fields are involved. In the general configuration, it is considered a Klein-Gordon-Maxwell-Einstein fields system for a complex scalar field minimally coupled to a gravitational one. The necessity of studying a larger number of space-time configurations and the huge volume of computations for each particular situation are some reasons for building a MAPLE procedures set for this kind of systems.
Topological quantum scattering under the influence of a nontrivial boundary condition
NASA Astrophysics Data System (ADS)
Mota, Herondy
We consider the quantum scattering problem of a relativistic particle in (2 + 1)-dimensional cosmic string spacetime under the influence of a nontrivial boundary condition imposed on the solution of the Klein-Gordon equation. The solution is then shifted as consequence of the nontrivial boundary condition and the role of the phase shift is to produce an Aharonov-Bohm-like effect. We examine the connection between this phase shift and the electromagnetic and gravitational analogous of the Aharonov-Bohm effect and compare the present results with previous ones obtained in the literature, also considering non-relativistic cases.
Analytical solutions in rotating linear dilaton black holes: Resonant frequencies, quantization, greybody factor, and Hawking radiation
NASA Astrophysics Data System (ADS)
Sakalli, I.
Charged massive scalar field perturbations are studied in the gravitational, electromagnetic, dilaton, and axion fields of rotating linear dilaton black holes. In this geometry, we separate the covariant Klein-Gordon equation into radial and angular parts and obtain the exact solutions of both the equations in terms of the confluent Heun functions. Using the radial solution, we study the problems of resonant frequencies, entropy/area quantization, and greybody factor. We also analyze the behavior of the wave solutions near the event horizon of the rotating linear dilaton black hole and derive its Hawking temperature via the Damour-Ruffini-Sannan method.
Spinless Particles Subject to Unequal Scalar-Vector Nuclear Woods- Saxon Potentials in Arbitrary Dimensions
NASA Astrophysics Data System (ADS)
Hamzavi, Majid; Ikhdair, Sameer M.; Rajabi, Ali Akbar
We present analytical bound state solutions of the spin-zero particles in the Klein-Gordon (KG) equation in presence of an unequal mixture of scalar and vector Woods-Saxon potentials within the framework of the approximation scheme to the centrifugal potential term for any arbitrary l-state. The approximate energy eigenvalues and unnormalized wave functions are obtained in closed forms using a parametric Nikiforov-Uvarov (NU) method. Our numerical energy eigenvalues demonstrate the existence of inter-dimensional degeneracy amongst energy states of the KG-Woods-Saxon problem. The dependence of the energy levels on the dimension D is numerically discussed for spatial dimensions D = 2 - 6.
Field theory on R× S 3 topology: Lagrangian formulation
NASA Astrophysics Data System (ADS)
Carmeli, M.; Malka, A.
A brief description of the ordinary field theory, from the variational and Noether's theorem point of view, is outlined. A discussion is then given of the field equations of Klein-Gordon, Schrödinger, Dirac, Weyl, and Maxwell in their ordinary form on the Minkowskian space-time manifold as well as on the topological space-time manifold R × S3 as they were formulated by Carmeli and Malin, including the latter's most general solutions. We then formulate the general variational principle in the R × S3 topological space, from which we derive the field equations in this space.
Quantum Tunneling Time: Relativistic Extensions
NASA Astrophysics Data System (ADS)
Xu, Dai-Yu; Wang, Towe; Xue, Xun
Several years ago, in quantum mechanics, Davies proposed a method to calculate particle's traveling time with the phase difference of wave function. The method is convenient for calculating the sojourn time inside a potential step and the tunneling time through a potential hill. We extend Davies' non-relativistic calculation to relativistic quantum mechanics, with and without particle-antiparticle creation, using Klein-Gordon equation and Dirac Equation, for different forms of energy-momentum relation. The extension is successful only when the particle and antiparticle creation/annihilation effect is negligible.
Instantaneous rest-frame transformation method for temporally induced pair creation
NASA Astrophysics Data System (ADS)
Lv, Q. Z.; Vikartofsky, A.; Norris, S.; Li, Y. J.; Wagner, R.; Su, Q.; Grobe, R.
We introduce a computational method to determine the rate of the electron-positron pair creation triggered by a time-dependent subcritical external field. It is based on constructing a Lorentz transformation to an instantaneous rest frame, for which the pair-creation rate can be determined by standard techniques. We will discuss the accuracy and efficiency of this method by comparing its predictions with exact time-dependent quantum field theoretical solutions to the Dirac and Klein-Gordon equations for various space-time dependent external fields.
The Invariant Operator Theory, and the Unification of the Fundamental Interactions
NASA Astrophysics Data System (ADS)
Nduka, Amagh
This paper established explicitly and unambiguously that the Invariant Operator Theory is the most general physical theory that can be constructed in a pseudo-euclidean (space-time) background. Specifically, we show that the field theories of Isaac Newton, Clarke Maxwell, Erwin Schrodinger, Klein-Gordon, and Paul A. M. Dirac are mere derivatives of the new Theory. Finally we discuss the unification of the fundamental interactions. We find that the NEW Physics has succesfully resolved all the outstanding problems of Physics, with the exception of the problem of mass.
A quark transport theory to describe nucleon-nucleon collisions
NASA Astrophysics Data System (ADS)
Kalmbach, U.; Vetter, T.; Biró, T. S.; Mosel, U.
On the basis of the Friedberg-Lee model we formulate a semiclassical transport theory to describe the phase-space evolution of nucleon-nucleon collisions on the quark level. The time evolution is given by a Vlasov equation for the quark phase-space distribution and a Klein-Gordon equation for the mean-field describing the nucleon as a soliton bag. The Vlasov equation is solved numerically using an extended test-particle method. We test the confinement mechanism and mean-field effects in (1 + 1)-dimensional simulations.
Gordon Decomposition of Dirac Spinors in Gravitational Background
NASA Astrophysics Data System (ADS)
Parashar, D.
The scheme outlined earlier is continued here to investigate the structure of Dirac spinors in the background of a gravitational field within the context of cosmological Robertson-Walker metric where the treatment is based on general considerations of spatially curved (non-flat) hypersurfaces embracing open as well as closed versions of the Universe. A Gordon decomposition of the generalized Dirac current is then carried out in terms of the polarization and the magnetization densities. We also take a look at the Klein-Gordon equation in the curved space formalism.
Spacetime alternatives in the quantum mechanics of a relativistic particle
Whelan, J.T. Isaac Newton Institute for Mathematical Sciences, 20 Clarkson Road, Cambridge, CB3 0EH )
Hartle's generalized quantum mechanics formalism is used to examine spacetime coarse grainings, i.e., sets of alternatives defined with respect to a region extended in time as well as space, in the quantum mechanics of a free relativistic particle. For a simple coarse graining and suitable initial conditions, tractable formulas are found for branch wave functions. Despite the nonlocality of the positive-definite version of the Klein-Gordon inner product, which means that nonoverlapping branches are not sufficient to imply decoherence, some initial conditions are found to give decoherence and allow the consistent assignment of probabilities.
Gravitational collapse, chaos in CFT correlators and the information paradox
NASA Astrophysics Data System (ADS)
Farahi, Arya; Pando Zayas, Leopoldo A.
We consider gravitational collapse of a massless scalar field in asymptotically anti-de Sitter spacetime. Following the AdS/CFT dictionary we further study correlations in the field theory side by way of the Klein-Gordon equation of a probe scalar field in the collapsing background. We present evidence that in a certain regime the probe scalar field behaves chaotically, thus supporting Hawking's argument in the black hole information paradox proposing that although the information can be retrieved in principle, deterministic chaos impairs, in practice, the process of unitary extraction of information from a black hole. We emphasize that quantum chaos will change this picture. .
Elko and mass dimension one field of spin one-half: Causality and Fermi statistics
NASA Astrophysics Data System (ADS)
Ahluwalia, Dharam Vir; Nayak, Alekha Chandra
We review how Elko arise as an extension of complex-valued four-component Majorana spinors. This is followed by a discussion that constrains certain elements of phase freedom. A proof is reviewed that unambiguously establishes that Elko, and for that matter the indicated Majorana spinors, cannot satisfy Dirac equation. They, however do, as they must, satisfy spinorial Klein-Gordon equation. We then introduce a quantum field with Elko as its expansion coefficients and show that it is causal, satisfies Fermi statistics, and then refer to the existing literature to remind that its mass dimension is one. We conclude by providing an up-to-date bibliography on the subject.
Relativity and Quantum Mechanics
NASA Astrophysics Data System (ADS)
Brändas, Erkki J.
The old dilemma of quantum mechanics versus the theory of relativity is reconsidered via a first principles relativistically invariant theory. By analytic extension of quantum mechanics into the complex plane one may (i) include dynamical features such as time- and length-scales and (ii) examine the possibility and flexibility of so-called general Jordan block formations. The present viewpoint asks for a new perspective on the age-old problem of quantum mechanics versus the theory of relativity. To bring these ideas together, we will establish the relation with the Klein-Gordon-Dirac relativistic theory and confirm some dynamical features of both the special and the general relativity theory.
Discrete-time quantum walks: Continuous limit and symmetries
NASA Astrophysics Data System (ADS)
di Molfetta, G.; Debbasch, F.
The continuous limit of one-dimensional discrete-time quantum walks with time-and space-dependent coefficients is investigated. A given quantum walk does not generally admit a continuous limit but some families (1-jets) of quantum walks do. All families (1-jets) admitting a continuous limit are identified. The continuous limit is described by a Dirac-like equation or, alternately, a couple of Klein-Gordon equations. Variational principles leading to these equations are also discussed, together with local invariance properties.
New scale-relativistic derivations of Pauli and Dirac equations
NASA Astrophysics Data System (ADS)
Hammad, F.
In scale relativity, quantum mechanics is recovered by transcribing the classical equations of motion to fractal spaces and demanding, as dictated by the principle of scale relativity, that the form of these equations be preserved. In the framework of this theory, however, the form of the classical energy equations both in the relativistic and nonrelativistic cases are not preserved. Aiming to get full covariance, i.e., to restore to these equations their classical forms, we show that the scale-relativistic form of the Schrödinger equation yields the Pauli equation, whilst the Pissondes's scale-relativistic form of the Klein-Gordon equation gives the Dirac equation.
Superradiance from hydrodynamic vortices: A numerical study
Federici, F.; Tosi, M. P.; Cherubini, C.; Succi, S.
The scattering of sound-wave perturbations from vortex excitations in hydrodynamic systems with typical Bose-Einstein-condensate (BEC) parameters is investigated by numerical integration of the associated Klein-Gordon equation. The simulations indicate that at sufficiently high angular speeds, in the perturbative limit where back-reaction effects can be neglected, sound wave packets can extract a sizable fraction of the vortex energy through a mechanism of superradiant scattering. It is conjectured that this superradiant regime may be detectable in BEC experiments.
Noncompeting channel approach to pair creation in supercritical fields.
Lv, Q Z; Liu, Y; Li, Y J; Grobe, R; Su, Q
The Dirac and Klein-Gordon equations are solved on a space-time grid to study the strong-field induced pair creation process for bosons and fermions from the vacuum. If the external field is sufficiently strong to induce bound states that are embedded in the negative energy continuum, a complex scaling technique of the Hamiltonian can predict the longtime behavior of the dynamics. In the case of multiple bound states this technique predicts the occurrence of a new collective time scale. The longtime behavior of the pair creation is not determined by a single (most important) channel, but collectively by the sum of all individual widths of the embedded states.
First integrals of motion in a gauge covariant framework, Killing-Maxwell system and quantum anomalies
Visinescu, M.
Hidden symmetries in a covariant Hamiltonian framework are investigated. The special role of the Stackel-Killing and Killing-Yano tensors is pointed out. The covariant phase-space is extended to include external gauge fields and scalar potentials. We investigate the possibility for a higher-order symmetry to survive when the electromagnetic interactions are taken into account. Aconcrete realization of this possibility is given by the Killing-Maxwell system. The classical conserved quantities do not generally transfer to the quantized systems producing quantum gravitational anomalies. As a rule the conformal extension of the Killing vectors and tensors does not produce symmetry operators for the Klein-Gordon operator.
Deformed Hamilton-Jacobi Equations and the Tunneling Radiation of the Higher-Dimensional RN-(A)dS Black Hole
NASA Astrophysics Data System (ADS)
Feng, Zhongwen; Li, Guoping; Jiang, Pengying; Pan, Yang; Zu, Xiaotao
In this paper, we derive the deformed Hamilton-Jacobi equations from the generalized Klein-Gordon equation and generalized Dirac equation. Then, we study the tunneling rate, Hawking temperature and entropy of the higher-dimensional Reissner-Nordström de Sitter black hole via the deformed Hamilton-Jacobi equation. Our results show that the deformed Hamilton-Jacobi equations for charged scalar particles and charged fermions have the same expressions. Besides, the modified Hawking temperatures and entropy are related to the mass and charge of the black hole, the cosmology constant, the quantum number of emitted particles, and the term of GUP effects β.
Relativistic Approximate Solutions for a Two-Term Potential: Riemann-Type Equation
NASA Astrophysics Data System (ADS)
Arda, Altug
Approximate analytical solutions of a two-term potential are studied for the relativistic wave equations, namely, for the Klein-Gordon and Dirac equations. The results are obtained by solving of a Riemann-type equation whose solution can be written in terms of hypergeometric function 2F l(a,b; c; z). The energy eigenvalue equations and the corresponding normalized wave functions are given both for two wave equations. The results for some special cases including the Manning-Rosen potential, the Hulthen potential and the Coulomb potential are also discussed by setting the parameters as required.
Quantized scalar field as DM: the axion's case
Barranco, J.; Bernal, A.
We derive a rough estimation of the radius and the mass of a self-gravitating system made of axions. The system is a stationary solution of the Einstein-Klein-Gordon equations with a source term given by the vacuum expectation value of the energy-momentum operator constructed from the axion field. We found that such system would have masses of the order of asteroids ({approx}10{sup -10} M{sub {center_dot}}) and radius of the order of few centimeters. Some implications of such type of objects are discussed.
Nonlinear steady-state coupling of LH waves
Ko, K.; Krapchev, V.B.
The coupling of lower hybrid waves at the plasma edge by a two waveguide array with self-consistent density modulation is solved numerically. For a linear density profile, the governing nonlinear Klein-Gordon equation for the electric field can be written as a system of nonlinearly modified Airy equations in Fourier k/sub z/-space. Numerical solutions to the nonlinear system satisfying radiation condition are obtained. Spectra broadening and modifications to resonance cone trajectories are observed with increase of incident power.
Energy Criterion for the Spectral Stability of Discrete Breathers.
Kevrekidis, Panayotis G; Cuevas-Maraver, Jesús; Pelinovsky, Dmitry E
Discrete breathers are ubiquitous structures in nonlinear anharmonic models ranging from the prototypical example of the Fermi-Pasta-Ulam model to Klein-Gordon nonlinear lattices, among many others. We propose a general criterion for the emergence of instabilities of discrete breathers analogous to the well-established Vakhitov-Kolokolov criterion for solitary waves. The criterion involves the change of monotonicity of the discrete breather's energy as a function of the breather frequency. Our analysis suggests and numerical results corroborate that breathers with increasing (decreasing) energy-frequency dependence are generically unstable in soft (hard) nonlinear potentials.
Para-hydrogen induced polarization in heterogeneous hydrogenationreactions
Koptyug, Igor V.; Kovtunov, Kirill; Burt, Scott R.; Anwar, M.Sabieh; Hilty, Christian; Han, Song-I; Pines, Alexander; Sagdeev, Renad Z.
We demonstrate the creation and observation ofpara-hydrogen-induced polarization in heterogeneous hydrogenationreactions. Wilkinson's catalyst, RhCl(PPh3)3, supported on eithermodified silica gel or a polymer, is shown to hydrogenate styrene intoethylbenzene and to produce enhanced spin polarizations, observed throughNMR, when the reaction was performed with H2 gas enriched in the paraspinisomer. Furthermore, gaseous phase para-hydrogenation of propylene topropane with two catalysts, the Wilkinson's catalyst supported onmodified silica gel and Rh(cod)(sulfos) (cod = cycloocta-1,5-diene;sulfos) - O3S(C6H4)CH2C(CH2PPh2)3) supported on silica gel, demonstratesheterogeneous catalytic conversion resulting in large spin polarizations.These experiments serve as a direct verification of the mechanism ofheterogeneous hydrogenation reactions involving immobilized metalcomplexes and can be potentially developed into a practical tool forproducing catalyst-free fluids with highly polarized nuclear spins for abroad range of hyperpolarized NMR and MRI applications.
Conformation of ionizable poly Para phenylene ethynylene in dilute solutions
Wijesinghe, Sidath; Maskey, Sabina; Perahia, Dvora; ...
The conformation of dinonyl poly para phenylene ethynylenes (PPEs) with carboxylate side chains, equilibrated in solvents of different quality is studied using molecular dynamics simulations. PPEs are of interest because of their tunable electro-optical properties, chemical diversity, and functionality which are essential in wide range of applications. The polymer conformation determines the conjugation length and their assembly mode and affects electro-optical properties which are critical in their current and potential uses. The current study investigates the effect of carboxylate fraction on PPEs side chains on the conformation of chains in the dilute limit, in solvents of different quality. The dinonylmore » PPE chains are modeled atomistically, where the solvents are modeled both implicitly and explicitly. Dinonyl PPEs maintained a stretched out conformation up to a carboxylate fraction f of 0.7 in all solvents studied. The nonyl side chains are extended and oriented away from the PPE backbone in toluene and in implicit good solvent whereas in water and implicit poor solvent, the nonyl side chains are collapsed towards the PPE backbone. Thus, rotation around the aromatic ring is fast and no long range correlations are seen within the backbone.« less
Evidence for para dechlorination of polychlorobiphenyls by methanogenic bacteria
Ye, D.; Quensen, J.F.; Tiedje, J.M.
When microorganisms eluted from upper Hudson River sediment were cultured without any substrate except polychlorobiphenyl (PCB)-free Hudson River sediment, methane formation was the terminal step of the anaerobic food chain. In sediments containing Aroclor 1242, addition of eubacterium-inhibiting antibiotics, which should have directly inhibited fermentative bacteria and thereby should have indirectly inhibited methanogens, resulted in no dechlorination activity or methane production. However, when substrates for methanogenic bacteria were provided along with the antibiotics (to free the methanogens from dependence on eubacteria), concomitant methane production and dechlorination of PCBs were observed. The dechlorination of Aroclor 1242 was from the para positions, a pattern distinctly different from, and more limited than, the pattern observed with untreated or pasteurized inocula. Both methane production and dechlorination in cultures amended with antibiotics plus methanogenic substrates were inhibited by 2-bromoethanesulfonic acid. These results suggest that the methanogenic bacteria are among the physiological groups capable of anaerobic dechlorination of PCBs, but that the dechlorination observed with methanogenic bacteria is less extensive than the dechlorination observed with more complex anaerobic consortia. 27 refs., 5 figs., 1 tab.
DYNA3D/ParaDyn Regression Test Suite Inventory
Lin, Jerry I.
The following table constitutes an initial assessment of feature coverage across the regression test suite used for DYNA3D and ParaDyn. It documents the regression test suite at the time of preliminary release 16.1 in September 2016. The columns of the table represent groupings of functionalities, e.g., material models. Each problem in the test suite is represented by a row in the table. All features exercised by the problem are denoted by a check mark (√) in the corresponding column. The definition of "feature" has not been subdivided to its smallest unit of user input, e.g., algorithmic parameters specific to a particular type of contact surface. This represents a judgment to provide code developers and users a reasonable impression of feature coverage without expanding the width of the table by several multiples. All regression testing is run in parallel, typically with eight processors, except problems involving features only available in serial mode. Many are strictly regression tests acting as a check that the codes continue to produce adequately repeatable results as development unfolds; compilers change and platforms are replaced. A subset of the tests represents true verification problems that have been checked against analytical or other benchmark solutions. Users are welcomed to submit documented problems for inclusion in the test suite, especially if they are heavily exercising, and dependent upon, features that are currently underrepresented.
DYNA3D/ParaDyn Regression Test Suite Inventory
Lin, J I
The following table constitutes an initial assessment of feature coverage across the regression test suite used for DYNA3D and ParaDyn. It documents the regression test suite at the time of production release 10.1 in September 2010. The columns of the table represent groupings of functionalities, e.g., material models. Each problem in the test suite is represented by a row in the table. All features exercised by the problem are denoted by a check mark in the corresponding column. The definition of ''feature'' has not been subdivided to its smallest unit of user input, e.g., algorithmic parameters specific to a particular type of contact surface. This represents a judgment to provide code developers and users a reasonable impression of feature coverage without expanding the width of the table by several multiples. All regression testing is run in parallel, typically with eight processors. Many are strictly regression tests acting as a check that the codes continue to produce adequately repeatable results as development unfolds, compilers change and platforms are replaced. A subset of the tests represents true verification problems that have been checked against analytical or other benchmark solutions. Users are welcomed to submit documented problems for inclusion in the test suite, especially if they are heavily exercising, and dependent upon, features that are currently underrepresented.
El Transportador de las Particulas. Explorando el Mundo Natural-Nivel 3 (The Transporter of the Particles. Exploring the Natural World--Level 3.)
ERIC Educational Resources Information Center
California State Polytechnic Univ., Pomona.
The Intermediate Science Curriculum Study Spanish language science instruction manual for the intermediate grades focuses on energy of many types. The soft bound volume uses self-pacing and individualized learning to guide the students through a series of experiments. Basically, the students are asked to think about what they do and see, evaluate…
Para-nitrobenzyl esterases with enhanced activity in aqueous and nonaqueous media
Arnold, F.H.; Moore, J.C.
A method is disclosed for isolating and identifying modified para-nitrobenzyl esterases. These enzymes exhibit improved stability and/or esterase hydrolysis activity toward selected substrates and under selected reaction conditions relative to the unmodified para-nitrobenzyl esterase. The method involves preparing a library of modified para-nitrobenzyl esterase nucleic acid segments (genes) which have nucleotide sequences that differ from the nucleic acid segment which encodes for unmodified para-nitrobenzyl esterase. The library of modified para-nitrobenzyl nucleic acid segments is expressed to provide a plurality of modified enzymes. The clones expressing modified enzymes are then screened to identify which enzymes have improved esterase activity by measuring the ability of the enzymes to hydrolyze the selected substrate under the selected reaction conditions. Specific modified para-nitrobenzyl esterases are disclosed which have improved stability and/or ester hydrolysis activity in aqueous or aqueous-organic media relative to the stability and/or ester hydrolysis activity of unmodified naturally occurring para-nitrobenzyl esterase. 43 figs.
Para-nitrobenzyl esterases with enhanced activity in aqueous and nonaqueous media
Arnold, Frances H.; Moore, Jeffrey C.
A method for isolating and identifying modified para-nitrobenzyl esterases which exhibit improved stability and/or esterase hydrolysis activity toward selected substrates and under selected reaction conditions relative to the unmodified para-nitrobenzyl esterase. The method involves preparing a library of modified para-nitrobenzyl esterase nucleic acid segments (genes) which have nucleotide sequences that differ from the nucleic acid segment which encodes for unmodified para-nitrobenzyl esterase. The library of modified para-nitrobenzyl nucleic acid segments is expressed to provide a plurality of modified enzymes. The clones expressing modified enzymes are then screened to identify which enzymes have improved esterase activity by measuring the ability of the enzymes to hydrolyze the selected substrate under the selected reaction conditions. Specific modified para-nitrobenzyl esterases are disclosed which have improved stability and/or ester hydrolysis activity in aqueous or aqueous-organic media relative to the stability and/or ester hydrolysis activity of unmodified naturally occurring para-nitrobenzyl esterase.
Para-nitrobenzyl esterases with enhanced activity in aqueous and nonaqueous media
Arnold, Frances H.; Moore, Jeffrey C.
A method for isolating and identifying modified para-nitrobenzyl esterases which exhibit improved stability and/or esterase hydrolysis activity toward selected substrates and under selected reaction conditions relative to the unmodified para-nitrobenzyl esterase. The method involves preparing a library of modified para-nitrobenzyl esterase nucleic acid segments (genes) which have nucleotide sequences that differ from the nucleic acid segment which encodes for unmodified para-nitrobenzyl esterase. The library of modified para-nitrobenzyl nucleic acid segments is expressed to provide a plurality of modified enzymes. The clones expressing modified enzymes are then screened to identify which enzymes have improved esterase activity by measuring the ability of the enzymes to hydrolyze the selected substrate under the selected reaction conditions. Specific modified para-nitrobenzyl esterases are disclosed which have improved stability and/or ester hydrolysis activity in aqueous or aqueous-organic media relative to the stability and/or ester hydrolysis activity of unmodified naturally occurring para-nitrobenzyl esterase.
Para-nitrobenzyl esterases with enhanced activity in aqueous and nonaqueous media
Arnold, F.H.; Moore, J.C.
A method is disclosed for isolating and identifying modified para-nitrobenzyl esterases which exhibit improved stability and/or esterase hydrolysis activity toward selected substrates and under selected reaction conditions relative to the unmodified para-nitrobenzyl esterase. The method involves preparing a library of modified para-nitrobenzyl esterase nucleic acid segments (genes) which have nucleotide sequences that differ from the nucleic acid segment which encodes for unmodified para-nitrobenzyl esterase. The library of modified para-nitrobenzyl nucleic acid segments is expressed to provide a plurality of modified enzymes. The clones expressing modified enzymes are then screened to identify which enzymes have improved esterase activity by measuring the ability of the enzymes to hydrolyze the selected substrate under the selected reaction conditions. Specific modified para-nitrobenzyl esterases are disclosed which have improved stability and/or ester hydrolysis activity in aqueous or aqueous-organic media relative to the stability and/or ester hydrolysis activity of unmodified naturally occurring para-nitrobenzyl esterase. 43 figs.
Quantum fluctuations increase the self-diffusive motion of para-hydrogen in narrow carbon nanotubes.
Kowalczyk, Piotr; Gauden, Piotr A; Terzyk, Artur P; Furmaniak, Sylwester
Quantum fluctuations significantly increase the self-diffusive motion of para-hydrogen adsorbed in narrow carbon nanotubes at 30 K comparing to its classical counterpart. Rigorous Feynman's path integral calculations reveal that self-diffusive motion of para-hydrogen in a narrow (6,6) carbon nanotube at 30 K and pore densities below ∼29 mmol cm(-3) is one order of magnitude faster than the classical counterpart. We find that the zero-point energy and tunneling significantly smoothed out the free energy landscape of para-hydrogen molecules adsorbed in a narrow (6,6) carbon nanotube. This promotes a delocalization of the confined para-hydrogen at 30 K (i.e., population of unclassical paths due to quantum effects). Contrary the self-diffusive motion of classical para-hydrogen molecules in a narrow (6,6) carbon nanotube at 30 K is very slow. This is because classical para-hydrogen molecules undergo highly correlated movement when their collision diameter approached the carbon nanotube size (i.e., anomalous diffusion in quasi-one dimensional pores). On the basis of current results we predict that narrow single-walled carbon nanotubes are promising nanoporous molecular sieves being able to separate para-hydrogen molecules from mixtures of classical particles at cryogenic temperatures.
Management of large para-esophageal hiatal hernias.
Collet, D; Luc, G; Chiche, L
Para-esophageal hernias are relatively rare and typically occur in elderly patients. The various presenting symptoms are non-specific and often occur in combination. These include symptoms of gastro-esophageal reflux (GERD) in 26 to 70% of cases, microcytic anemia in 17 to 47%, and respiratory symptoms in 9 to 59%. Respiratory symptoms are not completely resolved by surgical intervention. Acute complications such as gastric volvulus with incarceration or strangulation are rare (estimated incidence of 1.2% per patient per year) but gastric ischemia leading to perforation is the main cause of mortality. Only patients with symptomatic hernias should undergo surgery. Prophylactic repair to prevent acute incarceration should only be undertaken in patients younger than 75 in good condition; surgical indications must be discussed individually beyond this age. The laparoscopic approach is now generally accepted. Resection of the hernia sac is associated with a lower incidence of recurrence. Repair of the hiatus can be reinforced with prosthetic material (either synthetic or biologic), but the benefit of prosthetic repair has not been clearly shown. Results of prosthetic reinforcement vary in different studies; it has been variably associated with four times fewer recurrences or with no measurable difference. A Collis type gastroplasty may be useful to lengthen a foreshortened esophagus, but no objective criteria have been defined to support this approach. The anatomic recurrence rate can be as high as 60% at 12years. But most recurrences are asymptomatic and do not affect the quality of life index. It therefore seems more appropriate to evaluate functional results and quality of life measures rather than to gauge success by a strict evaluation of anatomic hernia reduction.
Blood transfusion in the para-Bombay phenotype.
Lin-Chu, M; Broadberry, R E
The H-deficient phenotypes found in Chinese so far, have all been secretors of soluble blood group substances in saliva. The corresponding isoagglutinin activity (e.g. anti-B in OB(Hm) persons) has been found to be weak in all cases. To determine the clinical significance of these weak isoagglutinins 51Cr red cell survival tests were performed on three OB(Hm) individuals transfused with small volumes (4 ml) of groups B and O RBC. Rapid destruction of most of the RBC occurred whether or not the isoagglutinins of the OB(Hm) individuals were indirect antiglobulin test (IAGT) reactive. When a larger volume (54 ml packed RBC) of group B cells (weakly incompatible by IAGT) was transfused to another OB(Hm) individual with IAGT active anti-HI, the survival of the transfused RBC was 93% at 24 h, with 30% of the RBC remaining in the circulation at 28 d in contrast to 76% as would be expected if the survival was normal. Therefore when whole units of blood of normal ABO blood groups, compatible by IAGT, are transfused, the survival is expected to be almost normal. These weak isoagglutinins may not be very clinically significant and we suggest that when para-Bombay blood is not available, the compatibility testing for OA(Hm) persons should be performed with group A and group O packed RBC; OB(Hm) with group B and group O packed RBC: OAB(Hm) with groups A, B, AB and O packed RBC. For cross matching, the indirect antiglobulin test by a prewarmed technique should be used.
All the three ParaHox genes are present in Nuttallochiton mirandus (Mollusca: polyplacophora): evolutionary considerations.
Barucca, Marco; Biscotti, Maria A; Olmo, Ettore; Canapa, Adriana
The ParaHox gene cluster contains three homeobox genes, Gsx, Xlox and Cdx and has been demonstrated to be an evolutionary sister of the Hox gene cluster. Among deuterostomes the three genes are found in the majority of taxa, whereas among protostomes they have so far been isolated only in the phylum Sipuncula. We report the partial sequences of all three ParaHox genes in the polyplacophoran Nuttallochiton mirandus, the first species of the phylum Mollusca where all ParaHox genes have been isolated. This finding has phylogenetic implications for the phylum Mollusca and for its relationships with the other lophotrochozoan taxa.
Measurement of the formaldehyde ortho to para ratio in three molecular clouds
NASA Technical Reports Server (NTRS)
Kahane, C.; Lucas, R.; Frerking, M. A.; Langer, W. D.; Encrenaz, P.
Observations of ortho and para H2CO in two types of clouds, a warm cloud (Orion A) and two cold clouds (L183 and TMC1), are presented. The ortho to para ratio in Orion deduced from the H2(C-13)O data is about three, while that for TMC1 is about one and that for L183 is 1-2. The former value is in agreement with the value calculated from chemical models of ortho and para H2CO production. The values for the cold clouds are consistent with thermal equilibrium at a temperature slightly smaller than 10 K.
Endovascular Treatment of a Ruptured Para-Anastomotic Aneurysm of the Abdominal Aorta
Sfyroeras, Giorgos S.; Lioupis, Christos Bessias, Nikolaos; Maras, Dimitris; Pomoni, Maria; Andrikopoulos, Vassilios
We report a case of a ruptured para-anastomotic aortic aneurysm treated with implantation of a bifurcated stent-graft. A 72-year-old patient, who had undergone aortobifemoral bypass for aortoiliac occlusive disease 16 years ago, presented with a ruptured para-anastomotic aortic aneurysm. A bifurcated stent-graft was successfully deployed into the old bifurcated graft. This is the first report of a bifurcated stent-graft being placed through an 'end-to-side' anastomosed old aortobifemoral graft. Endovascular treatment of ruptured para-anastomotic aortic aneurysms can be accomplished successfully, avoiding open surgery which is associated with increased mortality and morbidity.
Cold-plasma assisted hydrophobisation of cellulose fibres with styrene and para-halogenated homologues
NASA Astrophysics Data System (ADS)
Gaiolas, C.; Costa, A. P.; Santos Silva, M. J.; Belgacem, M. N.
Cold-plasma-assisted treatment of additive-free hand sheet paper samples with styrene (ST), para-fluorostyrene (FST), para-fluoro-α-methylstyrene (FMST) and para-chloro-α-methylstyrene (ClMST) and para-bromostyrene (BrST) was studied and found that the grafting has occurred efficiently, as established by contact angle measurement. Thus, after solvent extraction of the modified substrates, in order to remove unbounded grafts, the contact angle value of a drop of water deposited at the surface of paper increased from 40° for unmodified substrate to 102, 99, 116, 100 and 107°, for ST-, FST- FMST-, ClMST- and BrST-treated samples, respectively, indicating that the surface has became totally hydrophobic. In fact, the polar component of the surface energy of treated samples decreased from 25 mJ/m2 to practically zero, indicating that treated surfaces were rendered totally non polar.
Genomic organisation of the seven ParaHox genes of coelacanths.
Mulley, John F; Holland, Peter W H
Human and mouse genomes contain six ParaHox genes implicated in gut and neural patterning. In coelacanths and cartilaginous fish, an additional ParaHox gene exists-Pdx2-that dates back to the genome duplications in early vertebrate evolution. Here we examine the genomic arrangement and flanking genes of all ParaHox genes in coelacanths, to determine the full complement of these genes. We find that coelacanths have seven ParaHox genes in total, in four chromosomal locations, revealing that five gene losses occurred soon after vertebrate genome duplication. Comparison of intergenic sequences reveals that some Pdx1 regulatory regions associated with development of pancreatic islets are older than tetrapods, that Pdx1 and Pdx2 share few if any conserved non-coding elements, and that there is very high sequence conservation between coelacanth species.
Spanish Coastal Patrol Ships for Argentina and Mexico (Guardacostas Espanoles para Argentina y Mejico),
IN TRANS ATION ~TITLE: .SPANISH COASTAL PATROL SHIPS FOR ARGENTINA AND MEXICO GUARDACOSTAS EFPANOLES PARA ARGENTINA Y MEJICO AUTHOR: M; RAMIREZ...SHIPS FOR ARGENTINA AND MEXICO [Ramirez Gabarrus, M.; Guardacostas espaioles para Argentina y Mejico; Tecnologia Militar, No. 4, 1983; pP. 50, 53-54... Mexico , Mr. Alvarez de Vayo, signed a contract with the Mexican War Minister, General Cardenas, to build a series of 10 coastal patrol boats and five
Diffusion Monte Carlo Study of Para-Diiodobenzene Polymorphism Revisited.
Hongo, Kenta; Watson, Mark A; Iitaka, Toshiaki; Aspuru-Guzik, Alán; Maezono, Ryo
We revisit our investigation of the diffusion Monte Carlo (DMC) simulation of para-diiodobenzene (p-DIB) molecular crystal polymorphism. [See J. Phys. Chem. Lett. 2010, 1, 1789-1794.] We perform, for the first time, a rigorous study of finite-size effects and choice of nodal surface on the prediction of polymorph stability in molecular crystals using fixed-node DMC. Our calculations are the largest that are currently feasible using the resources of the K-computer and provide insights into the formidable challenge of predicting such properties from first principles. In particular, we show that finite-size effects can influence the trial nodal surface of a small (1 × 1 × 1) simulation cell considerably. Therefore, we repeated our DMC simulations with a 1 × 3 × 3 simulation cell, which is the largest such calculation to date. We used a density functional theory (DFT) nodal surface generated with the PBE functional, and we accumulated statistical samples with ∼6.4 × 10(5) core hours for each polymorph. Our final results predict a polymorph stability that is consistent with experiment, but they also indicate that the results in our previous paper were somewhat fortuitous. We analyze the finite-size errors using model periodic Coulomb (MPC) interactions and kinetic energy corrections, according to the CCMH scheme of Chiesa, Ceperley, Martin, and Holzmann. We investigate the dependence of the finite-size errors on different aspect ratios of the simulation cell (k-mesh convergence) in order to understand how to choose an appropriate ratio for the DMC calculations. Even in the most expensive simulations currently possible, we show that the finite size errors in the DMC total energies are much larger than the energy difference between the two polymorphs, although error cancellation means that the polymorph prediction is accurate. Finally, we found that the T-move scheme is essential for these massive DMC simulations in order to circumvent population explosions and
para-C-H Borylation of Benzene Derivatives by a Bulky Iridium Catalyst.
Saito, Yutaro; Segawa, Yasutomo; Itami, Kenichiro
A highly para-selective aromatic C-H borylation has been accomplished. By a new iridium catalyst bearing a bulky diphosphine ligand, Xyl-MeO-BIPHEP, the C-H borylation of monosubstituted benzenes can be affected with para-selectivity up to 91%. This catalytic system is quite different from the usual iridium catalysts that cannot distinguish meta- and para-C-H bonds of monosubstituted benzene derivatives, resulting in the preferred formation of meta-products. The para-selectivity increases with increasing bulkiness of the substituent on the arene, indicating that the regioselectivity of the present reaction is primarily controlled by steric repulsion between substrate and catalyst. Caramiphen, an anticholinergic drug used in the treatment of Parkinson's disease, was converted into five derivatives via our para-selective borylation. The present [Ir(cod)OH]2/Xyl-MeO-BIPHEP catalyst represents a unique, sterically controlled, para-selective, aromatic C-H borylation system that should find use in streamlined, predictable chemical synthesis and in the rapid discovery and optimization of pharmaceuticals and materials.
The PARA-suite: PAR-CLIP specific sequence read simulation and processing
Kloetgen, Andreas; Borkhardt, Arndt; Hoell, Jessica I.
Background Next-generation sequencing technologies have profoundly impacted biology over recent years. Experimental protocols, such as photoactivatable ribonucleoside-enhanced cross-linking and immunoprecipitation (PAR-CLIP), which identifies protein–RNA interactions on a genome-wide scale, commonly employ deep sequencing. With PAR-CLIP, the incorporation of photoactivatable nucleosides into nascent transcripts leads to high rates of specific nucleotide conversions during reverse transcription. So far, the specific properties of PAR-CLIP-derived sequencing reads have not been assessed in depth. Methods We here compared PAR-CLIP sequencing reads to regular transcriptome sequencing reads (RNA-Seq) to identify distinctive properties that are relevant for reference-based read alignment of PAR-CLIP datasets. We developed a set of freely available tools for PAR-CLIP data analysis, called the PAR-CLIP analyzer suite (PARA-suite). The PARA-suite includes error model inference, PAR-CLIP read simulation based on PAR-CLIP specific properties, a full read alignment pipeline with a modified Burrows–Wheeler Aligner algorithm and CLIP read clustering for binding site detection. Results We show that differences in the error profiles of PAR-CLIP reads relative to regular transcriptome sequencing reads (RNA-Seq) make a distinct processing advantageous. We examine the alignment accuracy of commonly applied read aligners on 10 simulated PAR-CLIP datasets using different parameter settings and identified the most accurate setup among those read aligners. We demonstrate the performance of the PARA-suite in conjunction with different binding site detection algorithms on several real PAR-CLIP and HITS-CLIP datasets. Our processing pipeline allowed the improvement of both alignment and binding site detection accuracy. Availability The PARA-suite toolkit and the PARA-suite aligner are available at https://github.com/akloetgen/PARA-suite and https://github.com/akloetgen/PARA
Spontaneous Emission Between - and Para-Levels of Water-Ion H_2O^+
NASA Astrophysics Data System (ADS)
Tanaka, Keiichi; Harada, Kensuke; Nanbu, Shinkoh; Oka, Takeshi
Nuclear spin conversion interaction of water ion, H_2O^+, has been studied to derive spontaneous emission lifetime between ortho- and para-levels. H_2O^+ is a radical ion with the ^2B_1 electronic ground state. Its off-diagonal electron spin-nuclear spin interaction term, Tab(S_aΔ I_b + S_bΔ I_a), connects para and ortho levels, because Δ I = I_1 - I_2 has nonvanishing matrix elements between I = 0 and 1. The mixing by this term with Tab = 72 MHz predicted by ab initio theory in the MRD-CI/Bk level, is many orders of magnitude larger than for closed shell molecules because of the large magnetic interaction due to the un-paired electron. Using the molecular constants reported by Mürtz et al. by FIR-LMR, we searched for ortho and para coupling channels below 1000 cm-1 with accidental near degeneracy between para and ortho levels. For example, hyperfine components of the 42,2(ortho) and 33,0(para) levels mix by 1.2 × 10-3 due to their near degeneracy (Δ E = 0.417 cm-1), and give the ortho-para spontaneous emission lifetime of about 0.63 year. The most significant low lying 10,1(para) and 11,1(ortho) levels, on the contrary, mix only by 8.7 × 10-5 because of their large separation (Δ E = 16.267 cm-1) and give the spontaneous emission lifetime from 10,1(para) to 00,0(ortho) of about 100 year.These results qualitatively help to understand the observed high ortho- to para- H_2O^+ ratio of 4.8 ± 0.5 toward Sgr B2 but they are too slow to compete with the conversion by collision unless the number density of the region is very low (n ˜1 cm-3) or radiative temperature is very high (T_r > 100 K). M. Staikova, B. Engels, M. Peric, and S.D. Peyerimhoff, Mol. Phys. 80, 1485 (1993) P. Mürtz, L.R. Zink, K.M. Evenson, and J.M. Brown J. Chem. Phys. 109, 9744 (1998). LP. Schilke, et al., A&A 521, L11 (2010).
Estimation of Carbon Storage in Para Rubber Plantation in Eastern Thailand
NASA Astrophysics Data System (ADS)
Charoenjit, K.; Zuddas, P.; Allemand, P.
This study aims to estimate the carbon stock and sequestration in Para rubber plantation of East Thailand using the THAICHOTE (Thailand Earth Observation System data). For that purpose we identify the area of every stage class Para rubber plantation by the analysis of different image objects (i.e., rule base and multiple regression classifications) and we map the carbon stock and sequestration of each Para rubber class using biomass allometric regressions and carbon content equations. THAICHOTE data include Multispectral image (4 bands at 15x15 m spatial resolution), Panchromatic image (2x2 m spatial resolution) and Stereo image, data acquisition from December 2011-April 2012. The preliminary investigated area is located in Wangchun, (Eastern, Thailand) and covers about 20 Km2. Calibrating the class stage, by image analysis that integrated edge-based segmentation, reflectance, remote sensing indices, texture analysis and canopy height model (CHM), we found that best classification was obtained by multiple regression (accuracy of 80%) compared to rule base logical operation (accuracy 70%) suggesting that manual 3D stereo measurements or Light Detection And Ranging (LiDAR) both are able to construct the CHM. The results of this study indicate that for a total Para rubber biomass of 14,651 tons, the amount of stored carbon is of 7,326 tons. Mature stage of Para rubber plantations exhibits the highest capacity of sequestering with a global flux of 0.21 tons C/ Km2/year.
The ortho/para ratio of water vapor in Comet Halley
NASA Technical Reports Server (NTRS)
Mumma, Michael J.; Larson, Harold P.; Weaver, Harold A.
The ortho/para ratio of H2O is shown to be an invariant in the cometary coma. The dependence of ortho-para ratio on temperature in thermal equilibrium is given, and the nuclear-spin-temperature is defined. Its relation to the physical temperature of the cometary ices is discussed, and the prospects for using the observed ortho/para ratio to infer properties of the cometary nucleus are explored. The ortho/para ratio in Halley's comet is derived from high resolution infrared spectra of near 2.7 microns wavelength. On UT December 24.1, 1985 it was 2.73 + or - 0.17, and on UT March 22.7, 1986 it was 3.23 + or - 0.37. The nuclear-spin-temperature was 35 K (+9 K, -5 K) pre-perihelion, and less than 40 K post-perihelion, at the 67% confidence limit. Both numbers are consistent with modeled values of the equilibrium temperature of the cometary nucleus at aphelion (47 K). However, at the 95% confidence limit they are also fully consistent with temperatures less than 50 K, corresponding to an ortho/para ratio of about 3.0.
The formaldehyde ortho/para ratio as a probe of dark cloud chemistry and evolution
NASA Technical Reports Server (NTRS)
Dickens, J. E.; Irvine, W. M.
We present measurements of the H2CO ortho/para ratio toward four star-forming cores, L723, L1228, L1527, and L43, and one quiescent core, L1498. Combining these data with earlier results by Minh et al., three quiescent cores are found to have ortho/para ratios near 3, the ratio of statistical weights expected for gas-phase formation processes. In contrast, ortho/para ratios are 1.5-2.1 in five star-forming cores, suggesting thermalization at a kinetic temperature of 10 K. We attribute modification of the ortho/para ratio in the latter cores to formation and/or equilibration of H2CO on grains with sub-sequent release back into the gas phase due to the increased energy inputs from the forming star and outflow. We see accompanying enhancements in the H2CO abundance relative to H, to support this idea. The results suggest that the formaldehyde ortho/para ratio can differentiate between quiescent cores and those in which low-mass star formation has occurred.
Sistemas Correctores de Campo Para EL Telescopio Ritchey-Chretien UNAM212
NASA Astrophysics Data System (ADS)
Cobos, F. J.; Galan, M. J.
El telescopio UNAM2l2 fue inaugurado hace siete años y concebido para trabajar en las razones focales: f/7.5, F/13.5, F/27 y F/98. El diseño Ritchey-Chretién corresponde a la razón focal F/7.5 y el foco primario (F/2.286) no se consideró como utilizable para fotografía directa. En el Instituto de Astronomía de la UNAM, se diseñó y construyó un sistema corrector de campo para la razón focal F/7.5, que actualmente está en funcionamiento. Dentro de un programa de colaboración en diseflo y evaluación de sistemas ópticos, entre el Instituto de Astrofísica de Canarias y el Instituto de Astronomía de la UNAM, decidimos intentar el diseño de una correctora de campo para el foco primario del tȩlescopio UNAM212 bajo la consideración de que no son insalvables los problemas que implicaría su instalación y de que es muy posible que, en un futuro relativamente cercano, podamom tener un detector bidimenmional tipo Mepsicrón cuya área sensible haga tentadora la idea de construir la cámara directa para foco primario
Separability in cohomogeneity-2 Kerr-NUT-AdS metrics
NASA Astrophysics Data System (ADS)
Chen, Wei; Lü, Hong; Pope, Christopher N.
The remarkable and unexpected separability of the Hamilton-Jacobi and Klein-Gordon equations in the background of a rotating four-dimensional black hole played an important role in the construction of generalisations of the Kerr metric, and in the uncovering of hidden symmetries associated with the existence of Killing tensors. In this paper, we show that the Hamilton-Jacobi and Klein-Gordon equations are separable in Kerr-AdS backgrounds in all dimensions, if one specialises the rotation parameters so that the metrics have cohomogeneity 2. Furthermore, we show that this property of separability extends to the NUT generalisations of these cohomogeneity-2 black holes that we obtained in a recent paper. In all these cases, we also construct the associated irreducible rank-2 Killing tensor whose existence reflects the hidden symmetry that leads to the separability. We also consider some cohomogeneity-1 specialisations of the new Kerr-NUT-AdS metrics, showing how they relate to previous results in the literature.
The necessity of the Hadamard condition
NASA Astrophysics Data System (ADS)
Fewster, Christopher J.; Verch, Rainer
Hadamard states are generally considered as the physical states for linear quantized fields on curved spacetimes, for several good reasons. Here, we provide a new motivation for the Hadamard condition: for 'ultrastatic slab spacetimes' with compact Cauchy-surface, we show that the Wick squares of all time-derivatives of the quantized Klein-Gordon field have finite fluctuations only if the Wick-ordering is defined with respect to a Hadamard state. This provides a converse to an important result of Brunetti and Fredenhagen. The recently proposed 'S-J (Sorkin-Johnston) states' are shown, generically, to give infinite fluctuations for the Wick square of the time-derivative of the field, further limiting their utility as reasonable states. Motivated by the S-J construction, we also study the general question of extending states that are pure (or given by density matrices relative to a pure state) on a double-cone region of Minkowski space. We prove a result for general quantum field theories showing that such states cannot be extended to any larger double cone without encountering singular behaviour at the spacelike boundary of the inner region. In the context of the Klein-Gordon field this shows that even if an S-J state is Hadamard within the double cone, this must fail at the boundary.
Exact static solutions for discrete phi4 models free of the Peierls-Nabarro barrier: discretized first-integral approach.
Dmitriev, S V; Kevrekidis, P G; Yoshikawa, N; Frantzeskakis, D J
We propose a generalization of the discrete Klein-Gordon models free of the Peierls-Nabarro barrier derived in Spreight [Nonlinearity 12, 1373 (1999)] and Barashenkov [Phys. Rev. E 72, 035602(R) (2005)], such that they support not only kinks but a one-parameter set of exact static solutions. These solutions can be obtained iteratively from a two-point nonlinear map whose role is played by the discretized first integral of the static Klein-Gordon field, as suggested by Dmitriev [J. Phys. A 38, 7617 (2005)]. We then discuss some discrete phi4 models free of the Peierls-Nabarro barrier and identify for them the full space of available static solutions, including those derived recently by Cooper [Phys. Rev. E 72, 036605 (2005)] but not limited to them. These findings are also relevant to standing wave solutions of discrete nonlinear Schrödinger models. We also study stability of the obtained solutions. As an interesting aside, we derive the list of solutions to the continuum phi4 equation that fill the entire two-dimensional space of parameters obtained as the continuum limit of the corresponding space of the discrete models.
Quasi-exactly solvable relativistic soft-core Coulomb models
Agboola, Davids Zhang, Yao-Zhong
By considering a unified treatment, we present quasi exact polynomial solutions to both the Klein-Gordon and Dirac equations with the family of soft-core Coulomb potentials V{sub q}(r)=-Z/(r{sup q}+{beta}{sup q}){sup 1/q}, Z>0, {beta}>0, q{>=}1. We consider cases q=1 and q=2 and show that both cases are reducible to the same basic ordinary differential equation. A systematic and closed form solution to the basic equation is obtained using the Bethe ansatz method. For each case, the expressions for the energies and the allowed parameters are obtained analytically and the wavefunctions are derived in terms of the roots of a set of Bethe ansatz equations. - Highlights: Black-Right-Pointing-Pointer The relativistic bound-state solutions of the soft-core Coulomb models. Black-Right-Pointing-Pointer Quasi-exact treatments of the Dirac and Klein-Gordon equations for the soft-core Coulomb models. Black-Right-Pointing-Pointer Solutions obtained in terms of the roots to the Bethe ansatz equations. Black-Right-Pointing-Pointer The hidden Lie algebraic structure discussed for the models. Black-Right-Pointing-Pointer Results useful in describing mesonic atoms and interaction of intense laser fields with atom.
Quantum Gowdy T{sup 3} model: A unitary description
Corichi, Alejandro; Cortez, Jeronimo; Mena Marugan, Guillermo A.
The quantization of the family of linearly polarized Gowdy T{sup 3} spacetimes is discussed in detail, starting with a canonical analysis in which the true degrees of freedom are described by a scalar field that satisfies a Klein-Gordon type equation in a fiducial time-dependent background. A time-dependent canonical transformation, which amounts to a change of the basic (scalar) field of the model, brings the system to a description in terms of a Klein-Gordon equation on a background that is now static, although subject to a time-dependent potential. The system is quantized by means of a natural choice of annihilation and creation operators. The quantum time evolution is considered and shown to be unitary, so that both the Schroedinger and Heisenberg pictures can be consistently constructed. This has to be contrasted with previous treatments for which time evolution failed to be implementable as a unitary transformation. Possible implications for both canonical quantum gravity and quantum field theory in curved spacetime are noted.
Pair creation rates for one-dimensional fermionic and bosonic vacua
Cheng, T.; Ware, M. R.; Su, Q.; Grobe, R.
We compare the creation rates for particle-antiparticle pairs produced by a supercritical force field for fermionic and bosonic model systems. The rates obtained from the Dirac and Klein-Gordon equations can be computed directly from the quantum-mechanical transmission coefficients describing the scattering of an incoming particle with the supercritical potential barrier. We provide a unified framework that shows that the bosonic rates can exceed the fermionic ones, as one could expect from the Pauli-exclusion principle for the fermion system. This imbalance for small but supercritical forces is associated with the occurrence of negative bosonic transmission coefficients of arbitrary size for the Klein-Gordon system, while the Dirac coefficient is positive and bound by unity. We confirm the transmission coefficients with time-dependent scattering simulations. For large forces, however, the fermionic and bosonic pair-creation rates are surprisingly close to each other. The predicted pair creation rates also match the slopes of the time-dependent particle probabilities obtained from large-scale ab initio numerical simulations based on quantum field theory.
Second-order differential equations for bosons with spin j ≥ 1 and in the bases of general tensor-spinors of rank 2j
NASA Astrophysics Data System (ADS)
Banda Guzmán, V. M.; Kirchbach, M.
A boson of spin j≥ 1 can be described in one of the possibilities within the Bargmann-Wigner framework by means of one sole differential equation of order twice the spin, which however is known to be inconsistent as it allows for non-local, ghost and acausally propagating solutions, all problems which are difficult to tackle. The other possibility is provided by the Fierz-Pauli framework which is based on the more comfortable to deal with second-order Klein-Gordon equation, but it needs to be supplemented by an auxiliary condition. Although the latter formalism avoids some of the pathologies of the high-order equations, it still remains plagued by some inconsistencies such as the acausal propagation of the wave fronts of the (classical) solutions within an electromagnetic environment. We here suggest a method alternative to the above two that combines their advantages while avoiding the related difficulties. Namely, we suggest one sole strictly D^{(j,0)oplus (0,j)} representation specific second-order differential equation, which is derivable from a Lagrangian and whose solutions do not violate causality. The equation under discussion presents itself as the product of the Klein-Gordon operator with a momentum-independent projector on Lorentz irreducible representation spaces constructed from one of the Casimir invariants of the spin-Lorentz group. The basis used is that of general tensor-spinors of rank 2 j.
On Energy and Momentum in Contemporary Physics
NASA Astrophysics Data System (ADS)
Sujak, Peter
This paper analyzes the quantities of energy and momentum in the definitional relationship of classical mechanics and relativistic mechanics, in the de Broglie momentum hypothesis and in the Klein-Gordon, Dirac and Schrodinger equation. The results of analysis shows that λ designated in the de Broglie hypothesis λ = h / mv as the wave of matter with rest state value λ = ∞ must be connected with a real dimension of a particle with rest state value λ =lo = h /mo c and that on this basis we can come to the fundamental equations of quantum mechanics that are the Klein-Gordon, Dirac and Schrodinger equation without the necessity of the wave functions. Energies in relativistic mechanics as mc2 , mvc , and moc2 , and energy of a photon hν do not represent quantities of energies, but quantity of momentums intentionally multiplied by c, so mc . c , mv . c , mo c . c , hν / c . c and merely the dimension of such quantities equals in dimension the quantity of energy.
The breakdown of one-dimensional fermionic and bosonic vaccua in strong fields
NASA Astrophysics Data System (ADS)
Ware, M.; Cheng, T.; Su, Q.; Grobe, R.
We compare the creation rates for particle-antiparticle pairs produced by a supercritical force field for fermionic and bosonic model systems. The rates obtained from the Dirac and Klein-Gordon equations can be computed directly from the quantum mechanical transmission coefficients describing the scattering of an incoming particle with the supercritical potential barrier. We provide a unified framework that shows that the bosonic rates can exceed the fermionic ones, as one could expect from the Pauli exclusion principle for the fermion system. This imbalance for small but supercritical forces is associated with the occurrence of negative bosonic transmission coefficients of arbitrary size for the Klein-Gordon system, while the Dirac coefficient is positive and bound by unity. We confirm the transmission coefficients with time-dependent scattering simulations. For large forces, however, the fermionic and bosonic pair creation rates are surprisingly close to each other. The predicted pair-creation rates also match the slopes of the time-dependent particle probabilities obtained from large-scale ab initio numerical simulations based on quantum field theory.
A fractional Dirac equation and its solution
NASA Astrophysics Data System (ADS)
Muslih, Sami I.; Agrawal, Om P.; Baleanu, Dumitru
This paper presents a fractional Dirac equation and its solution. The fractional Dirac equation may be obtained using a fractional variational principle and a fractional Klein-Gordon equation; both methods are considered here. We extend the variational formulations for fractional discrete systems to fractional field systems defined in terms of Caputo derivatives. By applying the variational principle to a fractional action S, we obtain the fractional Euler-Lagrange equations of motion. We present a Lagrangian and a Hamiltonian for the fractional Dirac equation of order α. We also use a fractional Klein-Gordon equation to obtain the fractional Dirac equation which is the same as that obtained using the fractional variational principle. Eigensolutions of this equation are presented which follow the same approach as that for the solution of the standard Dirac equation. We also provide expressions for the path integral quantization for the fractional Dirac field which, in the limit α → 1, approaches to the path integral for the regular Dirac field. It is hoped that the fractional Dirac equation and the path integral quantization of the fractional field will allow further development of fractional relativistic quantum mechanics.
Pair creation rates for one-dimensional fermionic and bosonic vacua
NASA Astrophysics Data System (ADS)
Cheng, T.; Ware, M. R.; Su, Q.; Grobe, R.
We compare the creation rates for particle-antiparticle pairs produced by a supercritical force field for fermionic and bosonic model systems. The rates obtained from the Dirac and Klein-Gordon equations can be computed directly from the quantum-mechanical transmission coefficients describing the scattering of an incoming particle with the supercritical potential barrier. We provide a unified framework that shows that the bosonic rates can exceed the fermionic ones, as one could expect from the Pauli-exclusion principle for the fermion system. This imbalance for small but supercritical forces is associated with the occurrence of negative bosonic transmission coefficients of arbitrary size for the Klein-Gordon system, while the Dirac coefficient is positive and bound by unity. We confirm the transmission coefficients with time-dependent scattering simulations. For large forces, however, the fermionic and bosonic pair-creation rates are surprisingly close to each other. The predicted pair creation rates also match the slopes of the time-dependent particle probabilities obtained from large-scale ab initio numerical simulations based on quantum field theory.
White light parametric instabilities
NASA Astrophysics Data System (ADS)
Santos, Jorge; Bingham, Robert
The Wigner formalism of quantum mechanics provides an alternative formulation to describe waves propagating in a dispersive medium. However the wave equation describes a two mode problem, and all previous theoretical models, based on the Wigner-Moyal equation, only deal with the single mode problem, where propagation is assumed to obey a Schr"odinger-like equation. We first present a formulation to describe the laser propagation in a cold plasma based on the Wigner formalism generalized to Klein-Gordon like-fields. We constructed a 2x2 Wigner matrix on the basis of the Hamiltonian form of the Klein-Gordon equation of a charged scalar particle field. The system of coupled transport equations governing the evolution of the photon densities in phase-space is then derived; this system is formally equivalent to the full wave equation. The system of transport equations for the photons is coupled with the relativistic fluid equations for the plasma. A general dispersion relation is obtained and, from first principles, the effect of a broadband radiation spectrum on stimulated Raman scattering is studied.
Tsunami runup in u and v shaped bays
NASA Astrophysics Data System (ADS)
Garayshin, Viacheslav V.
Tsunami runup can be effectively modeled using the shallow water wave equations. In 1958 Carrier and Greenspan in their work "Water waves of finite amplitude on a sloping beach" used this system to model tsunami runup on a uniformly sloping plane beach. They linearized this problem using a hodograph type transformation and obtained the Klein-Gordon equation which could be explicitly solved by using the Fourier-Bessel transform. In 2011, Efim Pelinovsky and Ira Didenkulova in their work "Runup of Tsunami Waves in U-Shaped Bays" used a similar hodograph type transformation and linearized the tsunami problem for a sloping bay with parabolic cross-section. They solved the linear system by using the D'Alembert formula. This method was generalized to sloping bays with cross-sections parameterized by power functions. However, an explicit solution was obtained only for the case of a bay with a quadratic cross-section. In this paper we will show that the Klein-Gordon equation can be solved by a spectral method for any inclined bathymetry with power function for any positive power. The result can be used to estimate tsunami runup in such bays with minimal numerical computations. This fact is very important because in many cases our numerical model can be substituted for full-scale numerical models which are computationally expensive, and time consuming, and not feasible to investigate tsunami behavior in the Alaskan coastal zone, due to the low population density in this area.
On a class of synchronized observers attached to the Lorentzian structures
NASA Astrophysics Data System (ADS)
Coll, Bartolomé; Moreno, Carlos
The first-order evolution form for the Klein-Gordon equation is characterized by an operator T(t) which, for inertial observers in the Minkowski space-time, is skew-self-adjoint with respect to the energy product. This fact is essential for a rigorous treatment of the equation. We prove here that, in arbitrary Lorentzian structures, there always exists a class of ``synchronized observers'' (equivalence class of physically admissible local charts), here called adjoint systems, for which this property of T(t) remains true. They are completely determined by the Lorentzian structure, and, in this sense, they appear as a suitable generalization of the Killing vector fields. We obtain the definition equations for such observers and state some of their properties. A particular class of them, here called simple adjoint systems, has already been introduced by one of us (C.M.) for the study of the Klein-Gordon equation in arbitrary space-times, according with Lichnerowicz's quantization program.
Kay, Bernard S.; Larkin, Peter
We construct a symplectic isomorphism h from classical Klein Gordon solutions of mass m on (d+1)-dimensional Lorentzian anti-de Sitter space (equipped with the usual symplectic form) to a certain symplectic space of functions on its conformal boundary (only) for all integer and half-integer {delta} (=(d/2)+(1/2)(d{sup 2}+4m{sup 2}){sup 1/2}). h induces a large family of new examples of Rehren's algebraic holography in which the net of local quantum Klein Gordon algebras in AdS is seen to map to a suitably defined net of local algebras for the (generalized free) scalar conformal field with anomalous dimension {delta} on d-dimensional Minkowski space (the AdS boundary). Relatedly, we show for these models that Bertola et al.'s boundary-limit holography becomes a quantum duality (only) if the test functions for boundary Wightman distributions are restricted in a particular way.
The School of Posture as a postural training method for Paraíba Telecommunications Operators.
Cardia, M C; Soares Màsculo, F
This work proposes to show the experience of posture training accomplished in the Paraíba State Telecommunication Company, using the knowledge of the Back School. The sample was composed of 12 operators, employees of the company, representing 31% of this population. The model applied in TELPA (Paraíba Telecommunication Company, Brazil) was based on the models of Sherbrooke, Canada, and of the School of Posture of Paraìba Federal University. Fifty-eight point four percent of participants showed a reduction of column pain, 25% improved the quality of the rest and the received training was considered enough for the learning of correct postures at work in 75% of the cases. The whole population approved of the training, and 83.3% of the cases considered that this training influenced their lives very positively.
Production and characterization of para-hydrogen gas for matrix isolation infrared spectroscopy
NASA Astrophysics Data System (ADS)
Sundararajan, K.; Sankaran, K.; Ramanathan, N.; Gopi, R.
Normal hydrogen (n-H2) has 3:1 ortho/para ratio and the production of enriched para-hydrogen (p-H2) from normal hydrogen is useful for many applications including matrix isolation experiments. In this paper, we describe the design, development and fabrication of the ortho-para converter that is capable of producing enriched p-H2. The p-H2 thus produced was probed using infrared and Raman techniques. Using infrared measurement, the thickness and the purity of the p-H2 matrix were determined. The purity of p-H2 was determined to be >99%. Matrix isolation infrared spectra of trimethylphosphate (TMP) and acetylene (C2H2) were studied in p-H2 and n-H2 matrices and the results were compared with the conventional inert matrices.
Evidence for disequilibrium of ortho and para hydrogen on Jupiter from Voyager IRIS measurements
NASA Technical Reports Server (NTRS)
Conrath, B. J.; Gierasch, P. J.
Preliminary results of an analysis of the ortho state/para state ratio (parallel/antiparallel) for molecular H2 in the Jovian atmosphere using Voyager IR spectrometer (IRIS) data are reported. The study was undertaken to expand the understanding of the thermodynamics of a predominantly H2 atmosphere, which takes about 100 million sec to reach equilibrium. IRIS data provided 4.3/cm resolution in the 300-700/cm spectral range dominated by H2 lines. Approximately 600 spectra were examined to detect any disequilibrium between the hydrogen species. The results indicate that the ortho-para ratio is not in an equilibrium state in the upper Jovian troposphere. A thorough mapping of the para-state molecules in the upper atmosphere could therefore aid in mapping the atmospheric flowfield.
Modelos Teoricos de Linhas de Recombinacao EM Radio Frequencias Para Regioes H II
NASA Astrophysics Data System (ADS)
Abraham, Z.; Cancoro, A. C. O.
Foram feitos modelos de linhas de recombinção provenientes de regiões HII nas frequências de rádio para distintos números quãnticos. Estes modelos consideram regrões H II esfericamente simétricas com variações radiais na densidade e temperatura eletrônica, efeitos de colisoes inelásticas dos eletrons (alargarnento por pressão), e afastarnento do equiliíbrio termodinâmico local. 0 bojetivo é construir o perfil da linha para cada ponto da nuvern e obter o valor médio resultante da sua convoluçã com o feixe da antena de tarnanho comparável corn o tarnanho angular da nuvern para posterIor cornpara o corn
Electrical detection of ortho-para conversion in fullerene-encapsulated water
NASA Astrophysics Data System (ADS)
Meier, Benno; Mamone, Salvatore; Concistrè, Maria; Alonso-Valdesueiro, Javier; Krachmalnicoff, Andrea; Whitby, Richard J.; Levitt, Malcolm H.
Water exists in two spin isomers, ortho and para, that have different nuclear spin states. In bulk water, rapid proton exchange and hindered molecular rotation obscure the direct observation of two spin isomers. The supramolecular endofullerene H2O@C60 provides freely rotating, isolated water molecules even at cryogenic temperatures. Here we show that the bulk dielectric constant of this substance depends on the ortho/para ratio, and changes slowly in time after a sudden temperature jump, due to nuclear spin conversion. The attribution of the effect to ortho-para conversion is validated by comparison with nuclear magnetic resonance and quantum theory. The change in dielectric constant is consistent with an electric dipole moment of 0.51+/-0.05 Debye for an encapsulated water molecule, indicating the partial shielding of the water dipole by the encapsulating cage. The dependence of bulk dielectric constant on nuclear spin isomer composition appears to be a previously unreported physical phenomenon.
Calcisponges have a ParaHox gene and dynamic expression of dispersed NK homeobox genes.
Fortunato, Sofia A V; Adamski, Marcin; Ramos, Olivia Mendivil; Leininger, Sven; Liu, Jing; Ferrier, David E K; Adamska, Maja
Sponges are simple animals with few cell types, but their genomes paradoxically contain a wide variety of developmental transcription factors, including homeobox genes belonging to the Antennapedia (ANTP) class, which in bilaterians encompass Hox, ParaHox and NK genes. In the genome of the demosponge Amphimedon queenslandica, no Hox or ParaHox genes are present, but NK genes are linked in a tight cluster similar to the NK clusters of bilaterians. It has been proposed that Hox and ParaHox genes originated from NK cluster genes after divergence of sponges from the lineage leading to cnidarians and bilaterians. On the other hand, synteny analysis lends support to the notion that the absence of Hox and ParaHox genes in Amphimedon is a result of secondary loss (the ghost locus hypothesis). Here we analysed complete suites of ANTP-class homeoboxes in two calcareous sponges, Sycon ciliatum and Leucosolenia complicata. Our phylogenetic analyses demonstrate that these calcisponges possess orthologues of bilaterian NK genes (Hex, Hmx and Msx), a varying number of additional NK genes and one ParaHox gene, Cdx. Despite the generation of scaffolds spanning multiple genes, we find no evidence of clustering of Sycon NK genes. All Sycon ANTP-class genes are developmentally expressed, with patterns suggesting their involvement in cell type specification in embryos and adults, metamorphosis and body plan patterning. These results demonstrate that ParaHox genes predate the origin of sponges, thus confirming the ghost locus hypothesis, and highlight the need to analyse the genomes of multiple sponge lineages to obtain a complete picture of the ancestral composition of the first animal genome.
Quantitative structure–activity relationship analysis of the pharmacology of para-substituted methcathinone analogues
Bonano, J S; Banks, M L; Kolanos, R; Sakloth, F; Barnier, M L; Glennon, R A; Cozzi, N V; Partilla, J S; Baumann, M H; Negus, S S
Background and Purpose Methcathinone (MCAT) is a potent monoamine releaser and parent compound to emerging drugs of abuse including mephedrone (4-CH3 MCAT), the para-methyl analogue of MCAT. This study examined quantitative structure–activity relationships (QSAR) for MCAT and six para-substituted MCAT analogues on (a) in vitro potency to promote monoamine release via dopamine and serotonin transporters (DAT and SERT, respectively), and (b) in vivo modulation of intracranial self-stimulation (ICSS), a behavioural procedure used to evaluate abuse potential. Neurochemical and behavioural effects were correlated with steric (Es), electronic (σp) and lipophilic (πp) parameters of the para substituents. Experimental Approach For neurochemical studies, drug effects on monoamine release through DAT and SERT were evaluated in rat brain synaptosomes. For behavioural studies, drug effects were tested in male Sprague-Dawley rats implanted with electrodes targeting the medial forebrain bundle and trained to lever-press for electrical brain stimulation. Key Results MCAT and all six para-substituted analogues increased monoamine release via DAT and SERT and dose- and time-dependently modulated ICSS. In vitro selectivity for DAT versus SERT correlated with in vivo efficacy to produce abuse-related ICSS facilitation. In addition, the Es values of the para substituents correlated with both selectivity for DAT versus SERT and magnitude of ICSS facilitation. Conclusions and Implications Selectivity for DAT versus SERT in vitro is a key determinant of abuse-related ICSS facilitation by these MCAT analogues, and steric aspects of the para substituent of the MCAT scaffold (indicated by Es) are key determinants of this selectivity. PMID:25438806
Experiments at Scale with In-Situ Visualization Using ParaView/Catalyst in RAGE
Kares, Robert John
In this paper I describe some numerical experiments performed using the ParaView/Catalyst in-situ visualization infrastructure deployed in the Los Alamos RAGE radiation-hydrodynamics code to produce images from a running large scale 3D ICF simulation on the Cielo supercomputer at Los Alamos. The detailed procedures for the creation of the visualizations using ParaView/Catalyst are discussed and several images sequences from the ICF simulation problem produced with the in-situ method are presented. My impressions and conclusions concerning the use of the in-situ visualization method in RAGE are discussed.
Quantum rotation of ortho and para-water encapsulated in a fullerene cage.
Beduz, Carlo; Carravetta, Marina; Chen, Judy Y-C; Concistrè, Maria; Denning, Mark; Frunzi, Michael; Horsewill, Anthony J; Johannessen, Ole G; Lawler, Ronald; Lei, Xuegong; Levitt, Malcolm H; Li, Yongjun; Mamone, Salvatore; Murata, Yasujiro; Nagel, Urmas; Nishida, Tomoko; Ollivier, Jacques; Rols, Stéphane; Rõõm, Toomas; Sarkar, Riddhiman; Turro, Nicholas J; Yang, Yifeng
Inelastic neutron scattering, far-infrared spectroscopy, and cryogenic nuclear magnetic resonance are used to investigate the quantized rotation and ortho-para conversion of single water molecules trapped inside closed fullerene cages. The existence of metastable ortho-water molecules is demonstrated, and the interconversion of ortho-and para-water spin isomers is tracked in real time. Our investigation reveals that the ground state of encapsulated ortho water has a lifted degeneracy, associated with symmetry-breaking of the water environment.
In para totale...una cosa da panico...sulla lingua dei giovani in Italia (In para totale...una cosa da panico...The Language of Young People in Italy).
ERIC Educational Resources Information Center
Marcato, Carla
Describes and analyzes the language of young people in Italy today. Particular focus is on the expressions using "para" (e.g., "in para totale" = to be very bored or worried) and the phrase "una cosa da panico" (something terrible or its opposite something wonderful). (CFM)
Factor Structure of the "Escala de Autoeficacia para la Depresion en Adolescentes" (EADA)
ERIC Educational Resources Information Center
Diaz-Santos, Mirella; Cumba-Aviles, Eduardo; Bernal, Guillermo; Rivera-Medina, Carmen
The current concept and measures of self-efficacy for depression in adolescents do not consider developmental and cultural aspects essential to understand and assess this construct in Latino youth. We examined the factor structure of the "Escala de Autoeficacia para la Depresion en Adolescentes" (EADA), a Spanish instrument designed to…
Anuncios de servicio público para proteger a los trabajadores de plaguicidas
Estos archivos de anuncios de servicio público se pueden descargar libremente para su uso en la formación, transmisiones de audio, etc.(These public service announcement files can be freely downloaded for use in training, audio broadcasts, etc.)
Antimicrobial effect of para-alkoxyphenylcarbamic acid esters containing substituted N-phenylpiperazine moiety
Malík, Ivan; Bukovský, Marián; Andriamainty, Fils; Gališinová, Jana
In current research, nine basic esters of para-alkoxyphenylcarbamic acid with incorporated 4-(4-fluoro-/3-trifluoromethylphenyl)piperazin-1-yl fragment, 6i–6m and 8f–8i, were screened for their in vitro antimicrobial activity against Candida albicans, Staphylococcus aureus and Escherichia coli, respectively. Taking into account the minimum inhibitory concentration assay (MIC), as the most active against given yeast was evaluated 8i (MIC = 0.20 mg/mL), the most lipophilic structure containing para-butoxy and trifluoromethyl substituents. Investigating the efficiency of the compounds bearing only a single atom of fluorine and appropriate para-alkoxy side chain against Candida albicans, the cut-off effect was observed. From evaluated homological series, the maximum of the effectiveness was noticed for the stucture 6 k (MIC = 0.39 mg/mL), containing para-propoxy group attached to phenylcarbamoyloxy fragment, beyond which the compounds ceased to be active. On the contrary, all the tested molecules were against Staphylococcus aureus and Escherichia coli (MICs > 1.00 mg/mL) practically inactive. PMID:24294237
Irradiation of para-aortic lymph node metastases from carcinoma of the cervix or endometrium
Komaki, R.; Mattingly, R.F.; Hoffman, R.G.; Barber, S.W.; Satre, R.; Greenberg, M.
Twenty-two patients with biopsy-proved para-aortic lymph node metastases from carcinoma of the cervix (15 patients) or endometrium (7 patients) received a median dose of 5,000 rad/25 fractions. Para-aortic nodal metastases were controlled in 77% of cases. Control was significantly lower following radical retroperitoneal lymph node dissection than less extensive sampling procedures. Obstruction of the small bowel developed in 3 patients with tumor recurrence in the para-aortic region. Eight of the 10 patients who were disease-free at 2 years received >5,000 rad. Three patients were still alive without disease at 129, 63, and 60 months, respectively. The 5-year disease-free survival rate was 40% for cervical cancer and 60% for endometrial cancer: in the former group, it was significantly different depending on whether the para-aortic nodes were irradiated (40%) or not (0%). The authors suggest that 5,000-5,500 rad in 5-5.5 weeks is well tolerated and can control aortic nodal metastases in cervical and possibly endometrial cancer.
Energia Renovable para Centros de Salud Rurales (Renewable Energy for Rural Health Clinics)
Jimenez, T.; Olson, K.
Esta es la primera de una serie de guias de aplicaciones que el Programa de Energia de Villas de NREL esta comisionando para acoplar sistemas comerciales renovables con aplicaciones rurales, incluyendo agua, escuelas rurales y micro empresas. La guia esta complementada por las actividades de desarrollo del Programa de Energia de Villas de NREL, proyectos pilotos internacionales y programas de visitas profesionales.
[Fut1 gene mutation for para-bombay blood type individual in Fujian Province of China].
Huang, Hao-Bou; Fan, Li-Ping; Wai, Shi-Jin; Zeng, Feng; Lin, Hai-Yan; Zhang, Rong
This study was aimed to investigate the molecular mechanisms for para-Bombay blood type individual in Fujian Province of China. The para-Bombay blood type of this individual was identified by routine serological techniques. The full coding region of alpha (1,2) fucosyltransferase (FUT1) gene of this individual was amplified by polymerase chain reaction (PCR), then the PCR product was cloned into T vector. The mutation in coding region of fut1 gene was identified by TA cloning, so as to explore the molecular mechanisms for para-Bombay blood type individual. The results indicated that the full coding region of fut1 gene was successfully amplified by PCR. AG deletion at position 547-552 on 2 homologous chromosomes was detected by TA cloning method, leading to a reading frame shift and a premature stop codon. It is concluded that genetic mutation of fut1 gene in this para-bombay blood type individual was h1h1 homozygotic type.
Can para-aryl-dithiols cross-link two plasmonic noble nanoparticles as monolayer dithiolate spacers
Technology Transfer Automated Retrieval System (TEKTRAN)
Para-aryl-dithiols (PADTs, HS-(C6H4)n-SH, n = 1, 2, and 3) have been used extensively in molecular electronics, surface-enhanced Raman spectroscopy (SERS), and quantum electron tunneling between two gold or silver nanoparticles (AuNPs and AgNPs). One popular belief is that these dithiols cross-link ...
Interrupting Commemoration: Thinking with Art, Thinking through the Strictures of Argentina's "Espacio para la memoria"
ERIC Educational Resources Information Center
Paolantonio, Mario Di
Recently, a few buildings within the "Espacio para la memoria" in Buenos Aires have been designated as a UNESCO Centre where, amongst other educational activities, evidentiary materials of the past repression are to be stored and displayed. Another building in the complex houses a Community Centre operated by the Mothers of the Plaza de…
Performance characteristics of magnesium/para-nitrophenol cells in 2:1 magnesium electrolytes
Kumar, G.; Sivashanugam, A.; Sridharan, R. )
1 V/1 Ah magnesium/para-nitrophenol (PNP) reserve cells were fabricated and their performance was evaluated in different electrolytes [2M aqueous solutions of Mg(C1O[sub 4])[sub 2], MgCl[sub 2], and MgBr[sub 2
Autoguía para el telescopio 2,15 mts de CASLEO
NASA Astrophysics Data System (ADS)
Aballay, J. A.; Casagrande, A. R.; Pereyra, P. F.; Marún, A. H.
Se está desarrollando un sistema de autoguía para el telescopio de 2,15 mts. El mismo se realizará aprovechando el Offset Guider. Al ocular móvil de éste se vinculará alguna cámara digital (ST4-ST7-CH250) para lograr la visión del objeto. El funcionamiento del equipo será el siguiente: primero, dadas las coordenadas del objeto a observar, se tomarán las coordenadas del telescopio para que, a través de una base de datos, se determine un campo de objetos que sirvan para la cámara de visión, luego, la PC obtendrá el offset entre la estrella de observación y la estrella seleccionada como guía, este valor será trasladado a los motores que posicionarán en forma automática el ocular. Una vez que la estrella es visualizada en la cámara (monitor de PC ) se correrá el programa que guiará el telescopio automáticamente.
Ortho-para conversion of endohedral water in the fullerene C60 at cryogenic temperatures
NASA Astrophysics Data System (ADS)
Shugai, Anna; Nagel, U.; Rõõm, T.; Mamone, S.; Concistrè, M.; Meier, B.; Krachmalnicoff, A.; Whitby, R. J.; Levitt, M. H.; Lei, Xuegong; Li, Yongjun; Turro, N. J.
Water displays the phenomenon of spin isomerism in which the two proton spins either couple to form a triplet (ortho water, I = 1) or a singlet nuclear spin state (para water, I = 0). Here we study the interconversion of para and ortho water. The exact mechanism of this process is still not fully understood. In order to minimize interactions between molecules we use a sample where a single H2O is trapped in the C60 molecular cage (H2O@C60)email@example.com@C60 has long-lived ortho state and ortho-para conversion kinetics is non-exponential at LHeT. We studied mixtures of H2O@C60, D2O@C60 and C60 using IR absorption, NMR and dielectric measurements. We saw the speeding up of the interconversion with the growth of H2O@C60 concentration in C60 or when D2O@C60 was added. At some temperatures the kinetics is exponential. Models are discussed in order to explain the T and concentration dependence of ortho-para interconversion kinetics. This work was supported by institutional research funding IUT23-3 of the Estonian Ministry of Education and Research.
Intact cluster and chordate-like expression of ParaHox genes in a sea star
Background The ParaHox genes are thought to be major players in patterning the gut of several bilaterian taxa. Though this is a fundamental role that these transcription factors play, their activities are not limited to the endoderm and extend to both ectodermal and mesodermal tissues. Three genes compose the ParaHox group: Gsx, Xlox and Cdx. In some taxa (mostly chordates but to some degree also in protostomes) the three genes are arranged into a genomic cluster, in a similar fashion to what has been shown for the better-known Hox genes. Sea urchins possess the full complement of ParaHox genes but they are all dispersed throughout the genome, an arrangement that, perhaps, represented the primitive condition for all echinoderms. In order to understand the evolutionary history of this group of genes we cloned and characterized all ParaHox genes, studied their expression patterns and identified their genomic loci in a member of an earlier branching group of echinoderms, the asteroid Patiria miniata. Results We identified the three ParaHox orthologs in the genome of P. miniata. While one of them, PmGsx is provided as maternal message, with no zygotic activation afterwards, the other two, PmLox and PmCdx are expressed during embryogenesis, within restricted domains of both endoderm and ectoderm. Screening of a Patiria bacterial artificial chromosome (BAC) library led to the identification of a clone containing the three genes. The transcriptional directions of PmGsx and PmLox are opposed to that of the PmCdx gene within the cluster. Conclusions The identification of P. miniata ParaHox genes has revealed the fact that these genes are clustered in the genome, in contrast to what has been reported for echinoids. Since the presence of an intact cluster, or at least a partial cluster, has been reported in chordates and polychaetes respectively, it becomes clear that within echinoderms, sea urchins have modified the original bilaterian arrangement. Moreover, the sea star
Vínculos observacionais para o processo-S em estrelas gigantes de Bário
NASA Astrophysics Data System (ADS)
Smiljanic, R. H. S.; Porto de Mello, G. F.; da Silva, L.
Estrelas de bário são gigantes vermelhas de tipo GK que apresentam excessos atmosféricos dos elementos do processo-s. Tais excessos são esperados em estrelas na fase de pulsos térmicos do AGB (TP-AGB). As estrelas de bário são, no entanto, menos massivas e menos luminosas que as estrelas do AGB, assim, não poderiam ter se auto-enriquecido. Seu enriquecimento teria origem em uma estrela companheira, inicialmente mais massiva, que evolui pelo TP-AGB, se auto-enriquece com os elementos do processo-s e transfere material contaminado para a atmosfera da atual estrela de bário. A companheira evolui então para anã branca deixando de ser observada diretamente. As estrelas de bário são, portanto, úteis como testes observacionais para teorias de nucleossíntese pelo processo-s, convecção e perda de massa. Análises detalhadas de abundância com dados de alta qualidade para estes objetos são ainda escassas na literatura. Neste trabalho construímos modelos de atmosferas e, procedendo a uma análise diferencial, determinamos parâmetros atmosféricos e evolutivos de uma amostra de dez gigantes de bário e quatro normais. Determinamos seus padrões de abundância para Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, Eu e Gd, concluindo que algumas estrelas classificadas na literatura como gigantes de bário são na verdade gigantes normais. Comparamos dois padrões médios de abundância, para estrelas com grandes excessos e estrelas com excessos moderados, com modelos teóricos de enriquecimento pelo processo-s. Os dois grupos de estrelas são ajustados pelos mesmos parâmetros de exposição de nêutrons. Tal resultado sugere que a ocorrência do fenômeno de bário com diferentes intensidades não se deve a diferentes exposições de nêutrons. Discutimos ainda efeitos nucleossintéticos, ligados ao processo-s, sugeridos na literatura para os elementos Cu, Mn, V e Sc.
Mothcakes made of para-dichlorobenzene have been widely available for the general population to be used as a moth repellant to protect garments from insect damage. Usually, a mothcake is expected to last for weeks or even months during which the para-dichlorobenzene emits slowly ...
Hox and ParaHox gene expression in early body plan patterning of polyplacophoran mollusks.
Fritsch, Martin; Wollesen, Tim; Wanninger, Andreas
Molecular developmental studies of various bilaterians have shown that the identity of the anteroposterior body axis is controlled by Hox and ParaHox genes. Detailed Hox and ParaHox gene expression data are available for conchiferan mollusks, such as gastropods (snails and slugs) and cephalopods (squids and octopuses), whereas information on the putative conchiferan sister group, Aculifera, is still scarce (but see Fritsch et al., 2015 on Hox gene expression in the polyplacophoran Acanthochitona crinita). In contrast to gastropods and cephalopods, the Hox genes in polyplacophorans are expressed in an anteroposterior sequence similar to the condition in annelids and other bilaterians. Here, we present the expression patterns of the Hox genes Lox5, Lox4, and Lox2, together with the ParaHox gene caudal (Cdx) in the polyplacophoran A. crinita. To localize Hox and ParaHox gene transcription products, we also investigated the expression patterns of the genes FMRF and Elav, and the development of the nervous system. Similar to the other Hox genes, all three Acr-Lox genes are expressed in an anteroposterior sequence. Transcripts of Acr-Cdx are seemingly present in the forming hindgut at the posterior end. The expression patterns of both the central class Acr-Lox genes and the Acr-Cdx gene are strikingly similar to those in annelids and nemerteans. In Polyplacophora, the expression patterns of the Hox and ParaHox genes seem to be evolutionarily highly conserved, while in conchiferan mollusks these genes are co-opted into novel functions that might have led to evolutionary novelties, at least in gastropods and cephalopods.
Ancient origins of axial patterning genes: Hox genes and ParaHox genes in the Cnidaria.
Finnerty, J R; Martindale, M Q
Among the bilaterally symmetrical, triploblastic animals (the Bilateria), a conserved set of developmental regulatory genes are known to function in patterning the anterior-posterior (AP) axis. This set includes the well-studied Hox cluster genes, and the recently described genes of the ParaHox cluster, which is believed to be the evolutionary sister of the Hox cluster (Brooke et al. 1998). The conserved role of these axial patterning genes in animals as diverse as frogs and flies is believed to reflect an underlying homology (i.e., all bilaterians derive from a common ancestor which possessed an AP axis and the developmental mechanisms responsible for patterning the axis). However, the origin and early evolution of Hox genes and ParaHox genes remain obscure. Repeated attempts have been made to reconstruct the early evolution of Hox genes by analyzing data from the triphoblastic animals, the Bilateria (Schubert et al. 1993; Zhang and Nei 1996). A more precise dating of Hox origins has been elusive due to a lack of sufficient information from outgroup taxa such as the phylum Cnidaria (corals, hydras, jellyfishes, and sea anemones). In combination with outgroup taxa, another potential source of information about Hox origins is outgroup genes (e.g., the genes of the ParaHox cluster). In this article, we present cDNA sequences of two Hox-like genes (anthox2 and anthox6) from the sea anemone, Nematostella vectensis. Phylogenetic analysis indicates that anthox2 (= Cnox2) is homologous to the GSX class of ParaHox genes, and anthox6 is homologous to the anterior class of Hox genes. Therefore, the origin of Hox genes and ParaHox genes occurred prior to the evolutionary split between the Cnidaria and the Bilateria and predated the evolution of the anterior-posterior axis of bilaterian animals. Our analysis also suggests that the central Hox class was invented in the bilaterian lineage, subsequent to their split from the Cnidaria.
Hox and ParaHox gene expression in early body plan patterning of polyplacophoran mollusks
Fritsch, Martin; Wollesen, Tim
ABSTRACT Molecular developmental studies of various bilaterians have shown that the identity of the anteroposterior body axis is controlled by Hox and ParaHox genes. Detailed Hox and ParaHox gene expression data are available for conchiferan mollusks, such as gastropods (snails and slugs) and cephalopods (squids and octopuses), whereas information on the putative conchiferan sister group, Aculifera, is still scarce (but see Fritsch et al., 2015 on Hox gene expression in the polyplacophoran Acanthochitona crinita). In contrast to gastropods and cephalopods, the Hox genes in polyplacophorans are expressed in an anteroposterior sequence similar to the condition in annelids and other bilaterians. Here, we present the expression patterns of the Hox genes Lox5, Lox4, and Lox2, together with the ParaHox gene caudal (Cdx) in the polyplacophoran A. crinita. To localize Hox and ParaHox gene transcription products, we also investigated the expression patterns of the genes FMRF and Elav, and the development of the nervous system. Similar to the other Hox genes, all three Acr‐Lox genes are expressed in an anteroposterior sequence. Transcripts of Acr‐Cdx are seemingly present in the forming hindgut at the posterior end. The expression patterns of both the central class Acr‐Lox genes and the Acr‐Cdx gene are strikingly similar to those in annelids and nemerteans. In Polyplacophora, the expression patterns of the Hox and ParaHox genes seem to be evolutionarily highly conserved, while in conchiferan mollusks these genes are co‐opted into novel functions that might have led to evolutionary novelties, at least in gastropods and cephalopods. PMID:27098677
Rotational excitation of HCN by para- and ortho-H{sub 2}
Vera, Mario Hernández; Kalugina, Yulia; Denis-Alpizar, Otoniel; Stoecklin, Thierry; Lique, François
Rotational excitation of the hydrogen cyanide (HCN) molecule by collisions with para-H{sub 2}( j = 0, 2) and ortho-H{sub 2}( j = 1) is investigated at low temperatures using a quantum time independent approach. Both molecules are treated as rigid rotors. The scattering calculations are based on a highly correlated ab initio 4-dimensional (4D) potential energy surface recently published. Rotationally inelastic cross sections among the 13 first rotational levels of HCN were obtained using a pure quantum close coupling approach for total energies up to 1200 cm{sup −1}. The corresponding thermal rate coefficients were computed for temperatures ranging from 5 to 100 K. The HCN rate coefficients are strongly dependent on the rotational level of the H{sub 2} molecule. In particular, the rate coefficients for collisions with para-H{sub 2}( j = 0) are significantly lower than those for collisions with ortho-H{sub 2}( j = 1) and para-H{sub 2}( j = 2). Propensity rules in favor of even Δj transitions were found for HCN in collisions with para-H{sub 2}( j = 0) whereas propensity rules in favor of odd Δj transitions were found for HCN in collisions with H{sub 2}( j ⩾ 1). The new rate coefficients were compared with previously published HCN-para-H{sub 2}( j = 0) rate coefficients. Significant differences were found due the inclusion of the H{sub 2} rotational structure in the scattering calculations. These new rate coefficients will be crucial to improve the estimation of the HCN abundance in the interstellar medium.
Saturn's Tropospheric Temperatures and Para-Hydrogen Distribution from Ten Years of Cassini Observations
NASA Astrophysics Data System (ADS)
Fletcher, Leigh N.; Irwin, Patrick G.; Sinclair, James; Giles, Rohini; Barstow, Joanna; Achterberg, Richard K.; Orton, Glenn S.
Cassini/CIRS observations of Saturn's 10-1400 cm-1 spectrum have been inverted to construct a global record of tropospheric temperature and para-hydrogen variability over the ten-year span of the Cassini mission. The data record the slow reversal of seasonal asymmetries in tropospheric conditions from northern winter (2004, Ls=293), through northern spring equinox (2009, Ls=0) to the present day (2014, Ls=60). Mid-latitude tropospheric temperatures have cooled by approximately 4-6 K in the south and warmed by 2-4 K in the north, with the seasonal contrast decreasing with depth. CIRS detected the north polar minimum 100-mbar temperatures 6-8 years after winter solstice, whereas the south polar maximum occurred 1-2 years after summer solstice, consistent with the lag times predicted by radiative equilibrium models. Warm polar cyclones and the northern hexagon persist throughout the mission, suggesting that they are permanent features of Saturn's tropospheric circulation. The 200-mbar thermal enhancement ("knee") that was strongest in the summer but weak or absent in winter in 2004-2006 (Fletcher et al., 2007, Icarus 189, p.457-478) has now shifted northward and is present globally in 2014, suggestive of radiative heating in Saturn's tropospheric haze layer. Saturn's para-H2 fraction, which serves as a tracer of both tropospheric mixing and the efficiency of re-equilibration between the ortho- and para-hydrogen states, is slowly altering: super-equilibrium conditions (para-H2 fraction exceeding equilibrium expectations and suggestive of subsiding airmasses) that dominated the southern summer hemisphere are now weakening, whereas the sub-equilibrium conditions (suggestive of uplift) of the northern winter are being replaced by equilibrium or super-equilibrium conditions in spring. The thermal 'knee' and the para-H2 distribution are tracking both the increased spring illumination and the increasing tropospheric haze opacity of the springtime hemisphere
Anatomic Distribution of Fluorodeoxyglucose-Avid Para-aortic Lymph Nodes in Patients With Cervical Cancer
Takiar, Vinita; Fontanilla, Hiral P.; Eifel, Patricia J.; Jhingran, Anuja; Kelly, Patrick; Iyer, Revathy B.; Levenback, Charles F.; Zhang, Yongbin; Dong, Lei; Klopp, Ann
Purpose: Conformal treatment of para-aortic lymph nodes (PAN) in cervical cancer allows dose escalation and reduces normal tissue toxicity. Currently, data documenting the precise location of involved PAN are lacking. We define the spatial distribution of this high-risk nodal volume by analyzing fluorodeoxyglucose (FDG)-avid lymph nodes (LNs) on positron emission tomography/computed tomography (PET/CT) scans in patients with cervical cancer. Methods and Materials: We identified 72 PANs on pretreatment PET/CT of 30 patients with newly diagnosed stage IB-IVA cervical cancer treated with definitive chemoradiation. LNs were classified as left-lateral para-aortic (LPA), aortocaval (AC), or right paracaval (RPC). Distances from the LN center to the closest vessel and adjacent vertebral body were calculated. Using deformable image registration, nodes were mapped to a template computed tomogram to provide a visual impression of nodal frequencies and anatomic distribution. Results: We identified 72 PET-positive para-aortic lymph nodes (37 LPA, 32 AC, 3 RPC). All RPC lymph nodes were in the inferior third of the para-aortic region. The mean distance from aorta for all lymph nodes was 8.3 mm (range, 3-17 mm), and from the inferior vena cava was 5.6 mm (range, 2-10 mm). Of the 72 lymph nodes, 60% were in the inferior third, 36% were in the middle third, and 4% were in the upper third of the para-aortic region. In all, 29 of 30 patients also had FDG-avid pelvic lymph nodes. Conclusions: A total of 96% of PET positive nodes were adjacent to the aorta; PET positive nodes to the right of the IVC were rare and were all located distally, within 3 cm of the aortic bifurcation. Our findings suggest that circumferential margins around the vessels do not accurately define the nodal region at risk. Instead, the anatomical extent of the nodal basin should be contoured on each axial image to provide optimal coverage of the para-aortic nodal compartment.
Astronomia para/com crianças carentes em Limeira
NASA Astrophysics Data System (ADS)
Bretones, P. S.; Oliveira, V. C.
Em 2001, o Instituto Superior de Ciências Aplicadas (ISCA Faculdades de Limeira) iniciou um projeto pelo qual o Observatório do Morro Azul empreendeu uma parceria com o Centro de Promoção Social Municipal (CEPROSOM), instituição mantida pela Prefeitura Municipal de Limeira para atender crianças e adolescentes carentes. O CEPROSOM contava com dois projetos: Projeto Centro de Convivência Infantil (CCI) e Programa Criança e Adolescente (PCA), que atendiam crianças e adolescentes em Centros Comunitários de diversas áreas da cidade. Esses projetos têm como prioridades estabelecer atividades prazerosas para as crianças no sentido de retirá-las das ruas. Assim sendo, as crianças passaram a ter mais um tipo de atividade - as visitas ao observatório. Este painel descreve as várias fases do projeto, que envolveu: reuniões de planejamento, curso de Astronomia para as orientadoras dos CCIs e PCAs, atividades relacionadas a visitas das crianças ao Observatório, proposta de construção de gnômons e relógios de Sol nos diversos Centros Comunitários de Limeira e divulgação do projeto na imprensa. O painel inclui discussões sobre a aprendizagem de crianças carentes, relatos que mostram a postura das orientadoras sobre a pertinência do ensino de Astronomia, relatos do monitor que fez o atendimento no Observatório e o que o número de crianças atendidas representou para as atividades da instituição desde o início de suas atividades e, em particular, em 2001. Os resultados são baseados na análise de relatos das orientadoras e do monitor do Observatório, registros de visitas e matérias da imprensa local. Conclui com uma avaliação do que tal projeto representou para as Instituições participantes. Para o Observatório, em particular, foi feita uma análise com relação às outras modalidades de atendimentos que envolvem alunos de escolas e público em geral. Também é abordada a questão do compromisso social do Observatório na educação do
ParA and ParB coordinate chromosome segregation with cell elongation and division during Streptomyces sporulation
Donczew, Magdalena; Mackiewicz, Paweł; Wróbel, Agnieszka; Flärdh, Klas; Zakrzewska-Czerwińska, Jolanta
In unicellular bacteria, the ParA and ParB proteins segregate chromosomes and coordinate this process with cell division and chromosome replication. During sporulation of mycelial Streptomyces, ParA and ParB uniformly distribute multiple chromosomes along the filamentous sporogenic hyphal compartment, which then differentiates into a chain of unigenomic spores. However, chromosome segregation must be coordinated with cell elongation and multiple divisions. Here, we addressed the question of whether ParA and ParB are involved in the synchronization of cell-cycle processes during sporulation in Streptomyces. To answer this question, we used time-lapse microscopy, which allows the monitoring of growth and division of single sporogenic hyphae. We showed that sporogenic hyphae stop extending at the time of ParA accumulation and Z-ring formation. We demonstrated that both ParA and ParB affect the rate of hyphal extension. Additionally, we showed that ParA promotes the formation of massive nucleoprotein complexes by ParB. We also showed that FtsZ ring assembly is affected by the ParB protein and/or unsegregated DNA. Our results indicate the existence of a checkpoint between the extension and septation of sporogenic hyphae that involves the ParA and ParB proteins. PMID:27248800
Differential regulation of ParaHox genes by retinoic acid in the invertebrate chordate amphioxus (Branchiostoma floridae).
Osborne, Peter W; Benoit, Gérard; Laudet, Vincent; Schubert, Michael; Ferrier, David E K
The ParaHox cluster is the evolutionary sister to the Hox cluster. Like the Hox cluster, the ParaHox cluster displays spatial and temporal regulation of the component genes along the anterior/posterior axis in a manner that correlates with the gene positions within the cluster (a feature called collinearity). The ParaHox cluster is however a simpler system to study because it is composed of only three genes. We provide a detailed analysis of the amphioxus ParaHox cluster and, for the first time in a single species, examine the regulation of the cluster in response to a single developmental signalling molecule, retinoic acid (RA). Embryos treated with either RA or RA antagonist display altered ParaHox gene expression: AmphiGsx expression shifts in the neural tube, and the endodermal boundary between AmphiXlox and AmphiCdx shifts its anterior/posterior position. We identified several putative retinoic acid response elements and in vitro assays suggest some may participate in RA regulation of the ParaHox genes. By comparison to vertebrate ParaHox gene regulation we explore the evolutionary implications. This work highlights how insights into the regulation and evolution of more complex vertebrate arrangements can be obtained through studies of a simpler, unduplicated amphioxus gene cluster.
ParA and ParB coordinate chromosome segregation with cell elongation and division during Streptomyces sporulation.
Donczew, Magdalena; Mackiewicz, Paweł; Wróbel, Agnieszka; Flärdh, Klas; Zakrzewska-Czerwińska, Jolanta; Jakimowicz, Dagmara
In unicellular bacteria, the ParA and ParB proteins segregate chromosomes and coordinate this process with cell division and chromosome replication. During sporulation of mycelial Streptomyces, ParA and ParB uniformly distribute multiple chromosomes along the filamentous sporogenic hyphal compartment, which then differentiates into a chain of unigenomic spores. However, chromosome segregation must be coordinated with cell elongation and multiple divisions. Here, we addressed the question of whether ParA and ParB are involved in the synchronization of cell-cycle processes during sporulation in Streptomyces To answer this question, we used time-lapse microscopy, which allows the monitoring of growth and division of single sporogenic hyphae. We showed that sporogenic hyphae stop extending at the time of ParA accumulation and Z-ring formation. We demonstrated that both ParA and ParB affect the rate of hyphal extension. Additionally, we showed that ParA promotes the formation of massive nucleoprotein complexes by ParB. We also showed that FtsZ ring assembly is affected by the ParB protein and/or unsegregated DNA. Our results indicate the existence of a checkpoint between the extension and septation of sporogenic hyphae that involves the ParA and ParB proteins.
Functional expression of Drosophila para sodium channels. Modulation by the membrane protein TipE and toxin pharmacology.
Warmke, J W; Reenan, R A; Wang, P; Qian, S; Arena, J P; Wang, J; Wunderler, D; Liu, K; Kaczorowski, G J; Van der Ploeg, L H; Ganetzky, B; Cohen, C J
The Drosophila para sodium channel alpha subunit was expressed in Xenopus oocytes alone and in combination with tipE, a putative Drosophila sodium channel accessory subunit. Coexpression of tipE with para results in elevated levels of sodium currents and accelerated current decay. Para/TipE sodium channels have biophysical and pharmacological properties similar to those of native channels. However, the pharmacology of these channels differs from that of vertebrate sodium channels: (a) toxin II from Anemonia sulcata, which slows inactivation, binds to Para and some mammalian sodium channels with similar affinity (Kd congruent with 10 nM), but this toxin causes a 100-fold greater decrease in the rate of inactivation of Para/TipE than of mammalian channels; (b) Para sodium channels are >10-fold more sensitive to block by tetrodotoxin; and (c) modification by the pyrethroid insecticide permethrin is >100-fold more potent for Para than for rat brain type IIA sodium channels. Our results suggest that the selective toxicity of pyrethroid insecticides is due at least in part to the greater affinity of pyrethroids for insect sodium channels than for mammalian sodium channels.
A sensitive and selective enzyme-linked immunosorbent assay for the analysis of Para red in foods.
Wang, Jia; Wei, Keyi; Li, Hao; Li, Qing X; Li, Ji; Xu, Ting
Para red is a synthetic dye and a potential genotoxic carcinogen. A hapten mimicking Para red structure was synthesized by introducing a carboxyl to the naphthol part of Para red and coupled to carrier protein to form an immunogen for the production of specific antibodies. A sensitive and selective enzyme-linked immunosorbent assay (ELISA) was developed for the detection of Para red in food samples. The limit of detection and inhibition half-maximum concentrations of Para red in phosphate buffered saline with 10% methanol were 0.06 and 2.2 ng mL(-1), respectively. Cross-reactivity values of the ELISA with the tested compounds including Sudan red I, II, III, IV, and G, sunset yellow, 2-naphthol, and 4-nitroaniline were ≤0.2%. This assay was used to determine Para red in tomato sauce, chilli sauce, chilli powder and sausage samples after ultrasonic extraction, cleanup and concentration steps. The average recoveries, repeatability (intraday extractions and analysis), and intra-laboratory reproducibility (interday extractions and analysis) were in the range 90-108%, 4-12% and 8-17%, respectively. This assay was compared to a high-performance liquid chromatographic method for 28 samples, displaying a good correlation (R(2) = 0.95). Para red residues in 53 real world samples determined by ELISA were below the limit of detection.
A Density Functional Approach to Para-hydrogen at Zero Temperature
NASA Astrophysics Data System (ADS)
Ancilotto, Francesco; Barranco, Manuel; Navarro, Jesús; Pi, Marti
We have developed a density functional (DF) built so as to reproduce either the metastable liquid or the solid equation of state of bulk para-hydrogen, as derived from quantum Monte Carlo zero temperature calculations. As an application, we have used it to study the structure and energetics of small para-hydrogen clusters made of up to N=40 molecules. We compare our results for liquid clusters with diffusion Monte Carlo (DMC) calculations and find a fair agreement between them. In particular, the transition found within DMC between hollow-core structures for small N values and center-filled structures at higher N values is reproduced. The present DF approach yields results for (pH_2)_N clusters indicating that for small N values a liquid-like character of the clusters prevails, while solid-like clusters are instead energetically favored for N ≥ 15.
Charge-transfer-directed radical substitution enables para-selective C-H functionalization
NASA Astrophysics Data System (ADS)
Boursalian, Gregory B.; Ham, Won Seok; Mazzotti, Anthony R.; Ritter, Tobias
Efficient C-H functionalization requires selectivity for specific C-H bonds. Progress has been made for directed aromatic substitution reactions to achieve ortho and meta selectivity, but a general strategy for para-selective C-H functionalization has remained elusive. Herein we introduce a previously unappreciated concept that enables nearly complete para selectivity. We propose that radicals with high electron affinity elicit arene-to-radical charge transfer in the transition state of radical addition, which is the factor primarily responsible for high positional selectivity. We demonstrate with a simple theoretical tool that the selectivity is predictable and show the utility of the concept through a direct synthesis of aryl piperazines. Our results contradict the notion, widely held by organic chemists, that radical aromatic substitution reactions are inherently unselective. The concept of radical substitution directed by charge transfer could serve as the basis for the development of new, highly selective C-H functionalization reactions.
Potential of Brachiaria mutica (Para grass) for bioethanol production from Loktak Lake.
Sahoo, Dinabandhu; Ummalyma, Sabeela Beevi; Okram, Aswini Kumar; Sukumaran, Rajeev K; George, Emrin; Pandey, Ashok
The aim of present study was to evaluate feasibility of using the Para grass as feedstock for production of bioethanol. Process involved the pretreatment with dilute acid or alkali and followed by enzymatic saccharification with commercial cellulase. Maximum sugar release of 696mg/g was obtained from 10% biomass loading and 0.5% w/v of alkali whereas in the case of acid pretreatment maximum sugar of 660mg/g was obtained from 20% biomass loading and 2% w/v acid loading. Results showed that Para grass utilization as a biorefinery feedstock can be a potential strategy to address the sustainable utilization of this invasive grass thereby keeping its population in check in the Loktak Lake.
Molecular Characterization of Neurally Expressing Genes in the Para Sodium Channel Gene Cluster of Drosophila
Hong, C. S.; Ganetzky, B.
To elucidate the mechanisms regulating expression of para, which encodes the major class of sodium channels in the Drosophila nervous system, we have tried to locate upstream cis-acting regulatory elements by mapping the transcriptional start site and analyzing the region immediately upstream of para in region 14D of the polytene chromosomes. From these studies, we have discovered that the region contains a cluster of neurally expressing genes. Here we report the molecular characterization of the genomic organization of the 14D region and the genes within this region, which are: calnexin (Cnx), actin related protein 14D (Arp14D), calcineurin A 14D (CnnA14D), and chromosome associated protein (Cap). The tight clustering of these genes, their neuronal expression patterns, and their potential functions related to expression, modulation, or regulation of sodium channels raise the possibility that these genes represent a functionally related group sharing some coordinate regulatory mechanism. PMID:8849894
Jupiter's Tropospheric Dynamics from SOFIA Mapping of Temperature, Para-Hydrogen, and Aerosols
NASA Astrophysics Data System (ADS)
de Pater, Imke
We request time with FORCAST to observe Jupiter at mid-infrared wavelengths using 8-37 micron grism spectroscopy of the collisionally-induced H2-He continuum to derive the zonal mean tropospheric temperatures and para-H2 distribution. In addition, we request imaging in discrete filters between 5 and 37 micron to provide spatial context for the spectroscopy. This proposal is a follow-up of our successful observations in May 2014, where we confirmed the N-S polar asymmetry in the para-H2 fraction detected by Voyager 1, also during late summer in Jupiter's northern hemisphere. In spring 2017, during a world-wide campaign in support of the Juno mission, it gets close to southern summer solstice. This timing is ideal to assess seasonable variability on the planet.
Control of Photoluminescence of Carbon Nanodots via Surface Functionalization using Para-substituted Anilines
Kwon, Woosung; Do, Sungan; Kim, Ji-Hee; Seok Jeong, Mun; Rhee, Shi-Woo
Carbon nanodots (C-dots) are a kind of fluorescent carbon nanomaterials, composed of polyaromatic carbon domains surrounded by amorphous carbon frames, and have attracted a great deal of attention because of their interesting properties. There are still, however, challenges ahead such as blue-biased photoluminescence, spectral broadness, undefined energy gaps and etc. In this report, we chemically modify the surface of C-dots with a series of para-substituted anilines to control their photoluminescence. Our surface functionalization endows our C-dots with new energy levels, exhibiting long-wavelength (up to 650 nm) photoluminescence of very narrow spectral widths. The roles of para-substituted anilines and their substituents in developing such energy levels are thoroughly studied by using transient absorption spectroscopy. We finally demonstrate light-emitting devices exploiting our C-dots as a phosphor, converting UV light to a variety of colors with internal quantum yields of ca. 20%. PMID:26218869
Charge Transfer Directed Radical Substitution Enables para-Selective C–H Functionalization
Boursalian, Gregory B.; Ham, Won Seok; Mazzotti, Anthony R.; Ritter, Tobias
Efficient C–H functionalization requires selectivity for specific C–H bonds. Progress has been made for directed aromatic substitution reactions to achieve ortho- and meta- selectivity, but a general strategy for para-selective C–H functionalization has remained elusive. Herein, we introduce a previously unappreciated concept which enables nearly complete para selectivity. We propose that radicals with high electron affinity elicit areneto-radical charge transfer in the transition state of radical addition, which is the factor primarily responsible for high positional selectivity. We demonstrate that the selectivity is predictable by a simple theoretical tool and show the utility of the concept through a direct synthesis of aryl piperazines. Our results contradict the notion, widely held by organic chemists, that radical aromatic substitution reactions are inherently unselective. The concept of charge transfer directed radical substitution could serve as the basis for the development of new, highly selective C–H functionalization reactions. PMID:27442288
H2CS abundances and ortho-to-para ratios in interstellar clouds
NASA Technical Reports Server (NTRS)
Minh, Y. C.; Irvine, W. M.; Brewer, M. K.
Several H2CS ortho and para transitions have been observed toward interstellar molecular clouds, including cold, dark clouds and star-forming regions. H2CS fractional abundances f(H2CS) about 1-2 10 to the -9th relative to molecular hydrogen toward TMC-1, Orion A, and NGC 7538, and about 5 10 to the -10th for L134N are derived. The H2CS ortho-to-para ratios in TMC-1 are about 1.8 toward the cyanopolyyne peak and the ammonia peak, which may indicate the thermalization of H2CS on 10 K grains. A ratio of about 3, the statistical value, for Orion (3N, 1E) and NGC 7538 is derived, while a value of about 2 for Orion (KL) is found.
Una propuesta para el desarrollo de un arreglo de síntesis de apertura
NASA Astrophysics Data System (ADS)
Arnal, E. M.
Los estudios llevados a cabo en la transición del hidrógeno neutro a λ~21-cm han contribuído a incrementar nuestro conocimiento acerca de las propiedades globales del medio interestelar, sea este galáctico o extragaláctico. Avances en este campo han sido provocados, a menudo, por la puesta en servicio de radiotelescopios que poseen una mayor resolución angular. Aquí se presenta una propuesta para desarrollar un nuevo instrumento, un interferómetro, que permitirá abrir nuevas líneas de investigación. Este instrumento combinará la técnica de síntesis de apertura con la de espectroscopía de correlación digital, para alcanzar una resolución angular de 1' y un campo de visión de ~1o.7.
Sludge reduction by uncoupling metabolism: SBR tests with para-nitrophenol and a commercial uncoupler.
Zuriaga-Agustí, E; Mendoza-Roca, J A; Bes-Piá, A; Alonso-Molina, J L; Amorós-Muñoz, I
Nowadays cost reduction is a very important issue in wastewater treatment plants. One way, is to minimize the sludge production. Microorganisms break down the organic matter into inorganic compounds through catabolism. Uncoupling metabolism is a method which promote catabolism reactions instead of anabolism ones, where adenosine triphosphate synthesis is inhibited. In this work, the influence of the addition of para-nitrophenol and a commercial reagent to a sequencing batch reactor (SBR) on sludge production and process performance has been analyzed. Three laboratory SBRs were operated in parallel to compare the effect of the addition of both reagents with a control reactor. SBRs were fed with synthetic wastewater and were operated with the same conditions. Results showed that sludge production was slightly reduced for the tested para-nitrophenol concentrations (20 and 25 mg/L) and for a LODOred dose of 1 mL/day. Biological process performance was not influenced and high COD removals were achieved.
Regioselective Enzymatic β-Carboxylation of para-Hydroxy- styrene Derivatives Catalyzed by Phenolic Acid Decarboxylases
Wuensch, Christiane; Pavkov-Keller, Tea; Steinkellner, Georg; Gross, Johannes; Fuchs, Michael; Hromic, Altijana; Lyskowski, Andrzej; Fauland, Kerstin; Gruber, Karl; Glueck, Silvia M; Faber, Kurt
We report on a 'green' method for the utilization of carbon dioxide as C1 unit for the regioselective synthesis of (E)-cinnamic acids via regioselective enzymatic carboxylation of para-hydroxystyrenes. Phenolic acid decarboxylases from bacterial sources catalyzed the β-carboxylation of para-hydroxystyrene derivatives with excellent regio- and (E/Z)-stereoselectivity by exclusively acting at the β-carbon atom of the C=C side chain to furnish the corresponding (E)-cinnamic acid derivatives in up to 40% conversion at the expense of bicarbonate as carbon dioxide source. Studies on the substrate scope of this strategy are presented and a catalytic mechanism is proposed based on molecular modelling studies supported by mutagenesis of amino acid residues in the active site. PMID:26190963
ROTATIONAL SPECTROSCOPY OF THE CO-PARA-H{sub 2} MOLECULAR COMPLEX
Potapov, A. V.; Surin, L. A.; Giesen, T. F.; Schlemmer, S.; Panfilov, V. A.; Dumesh, B. S.; Raston, P. L.; Jaeger, W.
The rotational spectrum of the CO-para-H{sub 2} van der Waals complex, produced using a molecular jet expansion, was observed with two different techniques: OROTRON intracavity millimeter-wave spectroscopy and pulsed Fourier transform microwave spectroscopy. Thirteen transitions in the frequency range from 80 to 130 GHz and two transitions in the 14 GHz region were measured and assigned, allowing for a precise determination of the corresponding energy level positions of CO-para-H{sub 2}. The data obtained enable further radio astronomical searches for this molecular complex and provide a sensitive test of the currently best available intermolecular potential energy surface for the CO-H{sub 2} system.
Synthesis and Properties of Rodlike Aromatic Heterocyclic Polymers: Phenylated Para-Terphenylene-Polybenzobis-Oxazoles
Polybenzobisoxazoles 6. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(s) S. CONTRACT OR GRANT NUMBER(s) Dr. J. F. Wolfe Dr. F. E. Arnold 9. PERFORMING ORGANIZATION...number) Para-ordered Polymers Polybenzobisoxazoles Polyphenylated Terphenylene 20. ABSTRACT (Continue on reverse side If necessary and Identify by block...poly(amide hydrazide) fibers 1-4 recently described in the literature meet the first two of these criteria. The overriding structural feature of
Parallel Visualization and Analysis with ParaView on a Cray XT4
Patchett, John; Ahrens, James; Ahern, Sean; Pugmire, Dave
Scienti c data sets produced by modern supercomputers like ORNL s Cray XT 4, Jaguar, can be extremely large, making visualization and analysis more di cult as moving large resultant data to dedicated analysis systems can be pro- hibitively expensive. We share our continuing work of integrating a parallel visu- alization system, ParaView, on ORNL s Jaguar system and our e orts to enable extreme scale interactive data visualization and analysis. We will discuss porting challenges and present performance numbers.
ParaDiS on Blue Gene/L: stepping up to the challenge
Hommes, G; Arsenlis, A; Bulatov, V; Cai, W; Cook, R; Hiratani, M; Oppestrup, T; Rhee, M; Tang, M
This paper reports on the efforts to enable fully scalable simulations of Dislocation Line Dynamics (DLD) for direct calculations of strength of crystalline materials. DLD simulations are challenging and do not lend themselves naturally to parallel computing. Through a combinations of novel physical approaches, mathematical algorithms and computational science developments, a new DLD code ParaDiS is shown to take meaningful advantage of BG/L and, by doing so, to enable discovery class science by computation.
ParaDiS on BlueGene/L: scalable line dynamics
Bulatov, V; Cai, W; Fier, J; Hiratani, M; Pierce, T; Tang, M; Rhee, M; Yates, R K; Arsenlis, A
We describe an innovative highly parallel application program, ParaDiS, which computes the plastic strength of materials by tracing the evolution of dislocation lines over time. We discuss the issues of scaling the code to tens of thousands of processors, and present early scaling results of the code run on a prototype of the BlueGene/L supercomputer being developed by IBM in partnership with the US DOE's ASC program.
Aplicación del Teorema de Nekhorochev para tiempos de estabilidad en Mecánica Celeste
NASA Astrophysics Data System (ADS)
Miloni, O.; Núñez, J.; Brunini, A.
En Mecánica Celeste, uno de los problemas centrales consiste en la determinación de los tiempos de estabilidad. El teorema de Nekhorochev proporciona un método para dicho estudio, para un sistema determinado por un hamiltoniano descripto en las variables acción-ángulo. El trabajo consiste en la acotación tanto del potencial perturbador y de la matriz hessiana del hamiltoniano integrable para determinar luego el tiempo de estabilidad de dicho sistema, donde por estabilidad se entiende la separación en norma infinito en el espacio de las acciones.
Atlas de aves: Un metodo para documentar distribucion y seguir poblaciones
Robbins, C.S.; Dowell, B.A.; Dawson, D.K.; Alvarez-Lopez, Humberto; Kattan, Gustavo; Murcia, Carolina
Los Atlas de Aves son proyectos nacionales o regionalies para trazar en mapas la distribucion en reproduccion de cada especie de ave. Ese procedimiento se esta usando en Europa, Australia, Nueva Zelanda, Norteamerica, y partes de Africa. El tama?o de los cuadrados varia de medio grado de latitud y Iongitud hasta 5 x 5 km. El trabajo de campo de cada proyecto exige aproxlmadamente cinco a?os, pero los aficionados pueden llevar a cabo la mayor parte del trabajo. Es posible almacenar los resultados en un computador personal. Hay muchos beneficios: (I) se presenta la distribucion corriente de las aves de la nacion, del estado, o de la Iocalidad; (2) se desarrolla nueva informacion especialmente sobre especies raras o en peligro; (3) se descubren areas que tienen una avlfauna sobresaliente o habitats raros y ayuda a su proteccion, (4) se documentan cambios de dlstribucion; (5) se pueden usar para documentar cambios de poblacion, especialmente en los tropicos donde otros metodos son mas dificiles de usar porque hay muchas especies y no hay muchos observadores calificados en la identificacion de sonidos de las aves; (6) son proyectos buenos de investigacion para estudiantes graduados; (7) los turistas y los jefes de excursiones de historia natural pueden contribuir con muchas informaciones
Quantum chemical and experimental study of 1,2,4-trihydroxy-para-menthane
NASA Astrophysics Data System (ADS)
Rottmannová, Lenka; Lukeš, Vladimír; Ilčin, Michal; Fodran, Peter; Herich, Peter; Kožíšek, Jozef; Liptaj, Tibor; Klein, Erik
The conformational analysis of the para-menthane (PM) and 1,2,4-trihydroxy-para-menthane (TPM) is performed using the quantum chemical density functional theory (DFT) and ab initio Møller-Plesset perturbation theory up to the second order (MP2). In TPM, three hydroxyl groups generate eight stereoisomers comparing to the four para-menthane stereoisomers. From the thermodynamics point of view, the most preferred conformations show the chair-shaped configuration of the cyclohexane ring. The obtained energy barriers for the isopropyl group rotation in the chair-shaped stereoisomers are between 35 and 45 kJ mol-1. The crystal structure as well as the solvated TPM stereoisomer isolated from the Tea tree oil, Melaleuca alternifolia (Maiden & Betche) Cheel, were investigated experimentally. Isolated stereoisomer corresponds to the most energetically preferred conformation and the calculated structural data agree very well with the results from the X-ray and nuclear magnetic resonance measurements. Finally, the influence of the conformation and the presence of the intramolecular hydrogen bonds on the homolytic Osbnd H bond dissociation enthalpies and proton affinities were also discussed with respect to the simple alcohols (methanol, iso-propanol, iso-pentanol, tert-butanol, cyclohexanol) and phenol.
The ortho:para ratio of H{sub 3}{sup +} in laboratory and astrophysical plasmas
Crabtree, Kyle N.; Indriolo, Nick; Kreckel, Holger; McCall, Benjamin J.
The discovery of H{sub 3}{sup +} in the diffuse interstellar medium has dramatically changed our view of the cosmic-ray ionization rate in diffuse molecular clouds. However, another surprise has been that the ortho:para ratio of H{sub 3}{sup +} in these clouds is inconsistent with the temperature derived from the excitation of H{sub 2}, the dominant species in these clouds. In an effort to understand this discrepancy, we have embarked on an experimental program to measure the nuclear spin dependence of the dissociative electron recombination rate of H{sub 3}{sup +} using the CRYRING and TSR ion storage rings. We have also performed the first measurements of the reaction H{sub 3}{sup +}+H{sub 2}→H{sub 2}+H{sub 3}{sup +} below room temperature. This reaction is likely the most common bimolecular reaction in the universe, and plays an important role in interconverting ortho- and para-H{sub 3}{sup +}. Finally, we have constructed a steady-state chemical model for diffuse clouds, which takes into account the spin-dependence of the formation of H{sub 3}{sup +}, its electron recombination, and its reaction with H{sub 2}. We find that the ortho:para ratio of H{sub 3}{sup +} in diffuse clouds is likely governed by a competition between dissociative recombination and thermalization by reactive collisions.
Beyond Hox: the role of ParaHox genes in normal and malignant hematopoiesis.
Rawat, Vijay P S; Humphries, R Keith; Buske, Christian
During the past decade it was recognized that homeobox gene families such as the clustered Hox genes play pivotal roles both in normal and malignant hematopoiesis. More recently, similar roles have also become apparent for members of the ParaHox gene cluster, evolutionarily closely related to the Hox gene cluster. This is in particular found for the caudal-type homeobox genes (Cdx) genes, known to act as upstream regulators of Hox genes. The CDX gene family member CDX2 belongs to the most frequent aberrantly expressed proto-oncogenes in human acute leukemias and is highly leukemogenic in experimental models. Correlative studies indicate that CDX2 functions as master regulator of perturbed HOX gene expression in human acute myeloid leukemia, locating this ParaHox gene at a central position for initiating and maintaining HOX gene dysregulation as a driving leukemogenic force. There are still few data about potential upstream regulators initiating aberrant CDX2 expression in human leukemias or about critical downstream targets of CDX2 in leukemic cells. Characterizing this network will hopefully open the way to therapeutic approaches that target deregulated ParaHox genes in human leukemia.
The ortho:para-H_2 ratio in C- and J-type shocks
NASA Astrophysics Data System (ADS)
Wilgenbus, D.; Cabrit, S.; Pineau des Forêts, G.; Flower, D. R.
We have computed extensive grids of models of both C- and J-type planar shock waves, propagating in dark, cold molecular clouds, in order to study systematically the behaviour of the ortho:para-H_2 ratio. Careful attention was paid to both macroscopic (dynamical) and microscopic (chemical reactions and collisional population transfer in H_2) aspects. We relate the predictions of the models to observational determinations of the ortho:para-H_2 ratio using both pure rotational lines and rovibrational lines. As an illustration, we consider ISO and ground-based H_2 observations of HH 54. Neither planar C-type nor planar J-type shocks appear able to account fully for these observations. Given the additional constraints provided by the observed ortho:para H_2 ratios, a C-type bowshock, or a C-type precursor followed by a J-type shock, remain as plausible models. Tables~2a-f and 4a-f are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsweb.u-strasbg.fr/Abstract.html
Theoretical study of the design of a catalyst for para to ortho hydrogen conversion
NASA Technical Reports Server (NTRS)
Coffman, Robert E.
The theory of Petzinger and Scalapino (1973) was thoroughly reviewed, and all of the basic equations for paramagnetic para to ortho hydrogen catalysis re-derived. There are only a few minor phase errors and errors of omission in the description of the theory. Three models (described by Petzinger and Scalapino) for the rate of para to ortho H2 catalysis were worked out, and uniform agreement obtained to within a constant factor of 2 pi. The analytical methods developed in the course of this study were then extended to two new models, which more adequately describe the process of surface catalysis including transfer of hydrogen molecules onto and off of the surface. All five equations for the para to ortho catalytic rate of conversion are described. The two new equations describe the catalytic rate for these models: H2 on the surface is a 2-D gas with lifetime tau; and H2 on the surface is a 2-D liquid undergoing Brownian motion (diffusion) with surface lifetime tau.
Base de linhas moleculares para síntese espectral estelar
NASA Astrophysics Data System (ADS)
Milone, A.; Sanzovo, G.
A análise das abundâncias quí micas fotosféricas em estrelas do tipo solar ou tardia, através do cálculo teórico de seus espectros, emprega a espectroscopia de alta resolução e necessita de uma base representativa de linhas atômicas e moleculares com suas respectivas constantes bem determinadas. Nesse trabalho, utilizamos como ponto de partida as extensas listas de linhas espectrais de sistemas eletrônicos de algumas moléculas diatômicas compiladas por Kurucz para a construção de uma base de linhas moleculares para a sí ntese espectral estelar. Revisamos as determinações dos fatores rotacionais de Honl-London das forças de oscilador das linhas moleculares, para cada banda vibracional de alguns sistemas eletrônicos, seguindo a regra usual de normalização. Usamos as forças de oscilador eletrônicas da literatura. Os fatores vibracionais de Franck-Condon de cada banda foram especialmente recalculados empregando-se novas constantes moleculares. Reproduzimos, com êxito, as absorções espectrais de determinadas bandas eletrônicas-vibracionais das espécies moleculares C12C12, C12N14 e Mg24H em espectros de estrelas de referência como o Sol e Arcturus.
ParaView visualization of Abaqus output on the mechanical deformation of complex microstructures
NASA Astrophysics Data System (ADS)
Liu, Qingbin; Li, Jiang; Liu, Jie
Abaqus® is a popular software suite for finite element analysis. It delivers linear and nonlinear analyses of mechanical and fluid dynamics, includes multi-body system and multi-physics coupling. However, the visualization capability of Abaqus using its CAE module is limited. Models from microtomography have extremely complicated structures, and datasets of Abaqus output are huge, requiring a visualization tool more powerful than Abaqus/CAE. We convert Abaqus output into the XML-based VTK format by developing a Python script and then using ParaView to visualize the results. Such capabilities as volume rendering, tensor glyphs, superior animation and other filters allow ParaView to offer excellent visualizing manifestations. ParaView's parallel visualization makes it possible to visualize very big data. To support full parallel visualization, the Python script achieves data partitioning by reorganizing all nodes, elements and the corresponding results on those nodes and elements. The data partition scheme minimizes data redundancy and works efficiently. Given its good readability and extendibility, the script can be extended to the processing of more different problems in Abaqus. We share the script with Abaqus users on GitHub.
El diseño final del espectrógrafo de banco (EBASIM) para CASLEO
NASA Astrophysics Data System (ADS)
Simmons, J.; Levato, H.
Utilizando el código de óptica ACCOS V se ha finalizado el diseño del espectrógrafo de banco para CASLEO. En una comunicación anterior habíamos indicado que utilizaríamos un colimador de 150 mm de diámetro con un radio de curvatura de 1540 mm. Para el espejo cámara, que tiene un diámetro de 200 mm, el radio de curvatura es de 1200 mm, ambos radios con una tolerancia no mayor a los 3 mm. En la presente, se informa sobre los detalles finales del cálculo del espectrógrafo que incluye el cómputo para 5 longitudes de onda diferentes y alrededor de 100 rayos. En todos los casos el 75 % de energía está dentro de un diámetro de 13 micrones. El diseño ha sido probado entre 3500 Å hasta 9000 Å con resultados satisfactorios.
Para-GMRF: parallel algorithm for anomaly detection of hyperspectral image
NASA Astrophysics Data System (ADS)
Dong, Chao; Zhao, Huijie; Li, Na; Wang, Wei
The hyperspectral imager is capable of collecting hundreds of images corresponding to different wavelength channels for the observed area simultaneously, which make it possible to discriminate man-made objects from natural background. However, the price paid for the wealthy information is the enormous amounts of data, usually hundreds of Gigabytes per day. Turning the huge volume data into useful information and knowledge in real time is critical for geoscientists. In this paper, the proposed parallel Gaussian-Markov random field (Para-GMRF) anomaly detection algorithm is an attempt of applying parallel computing technology to solve the problem. Based on the locality of GMRF algorithm, we partition the 3-D hyperspectral image cube in spatial domain and distribute data blocks to multiple computers for concurrent detection. Meanwhile, to achieve load balance, a work pool scheduler is designed for task assignment. The Para-GMRF algorithm is organized in master-slave architecture, coded in C programming language using message passing interface (MPI) library and tested on a Beowulf cluster. Experimental results show that Para-GMRF algorithm successfully conquers the challenge and can be used in time sensitive areas, such as environmental monitoring and battlefield reconnaissance.
ParaDock: a flexible non-specific DNA--rigid protein docking algorithm.
Banitt, Itamar; Wolfson, Haim J
Accurate prediction of protein-DNA complexes could provide an important stepping stone towards a thorough comprehension of vital intracellular processes. Few attempts were made to tackle this issue, focusing on binding patch prediction, protein function classification and distance constraints-based docking. We introduce ParaDock: a novel ab initio protein-DNA docking algorithm. ParaDock combines short DNA fragments, which have been rigidly docked to the protein based on geometric complementarity, to create bent planar DNA molecules of arbitrary sequence. Our algorithm was tested on the bound and unbound targets of a protein-DNA benchmark comprised of 47 complexes. With neither addressing protein flexibility, nor applying any refinement procedure, CAPRI acceptable solutions were obtained among the 10 top ranked hypotheses in 83% of the bound complexes, and 70% of the unbound. Without requiring prior knowledge of DNA length and sequence, and within <2 h per target on a standard 2.0 GHz single processor CPU, ParaDock offers a fast ab initio docking solution.
Electrical detection of ortho–para conversion in fullerene-encapsulated water
Meier, Benno; Mamone, Salvatore; Concistrè, Maria; Alonso-Valdesueiro, Javier; Krachmalnicoff, Andrea; Whitby, Richard J.; Levitt, Malcolm H.
Water exists in two spin isomers, ortho and para, that have different nuclear spin states. In bulk water, rapid proton exchange and hindered molecular rotation obscure the direct observation of two spin isomers. The supramolecular endofullerene H2O@C60 provides freely rotating, isolated water molecules even at cryogenic temperatures. Here we show that the bulk dielectric constant of this substance depends on the ortho/para ratio, and changes slowly in time after a sudden temperature jump, due to nuclear spin conversion. The attribution of the effect to ortho–para conversion is validated by comparison with nuclear magnetic resonance and quantum theory. The change in dielectric constant is consistent with an electric dipole moment of 0.51±0.05 Debye for an encapsulated water molecule, indicating the partial shielding of the water dipole by the encapsulating cage. The dependence of bulk dielectric constant on nuclear spin isomer composition appears to be a previously unreported physical phenomenon. PMID:26299447
The ParaShield entry vehicle concept - Basic theory and flight test development
NASA Astrophysics Data System (ADS)
Akin, David L.
The ParaShield concept of the Space Systems Laboratory is an ultra-low ballistic coefficient entry vehicle, created to meet the need for entry vehicle technology to return mass from low earth orbit. The concept involves decoupling the ballistic coefficient from the launch vehicle parameters, to pick a value (beta) which optimizes the desired entry vehicle characteristics. Trajectory simulations show that, as the ballistic coefficient is lowered to range of 100-150 Pa, the total heat load and peak heating flux drop markedly, due to primary deceleration in regions of extremely low dynamic pressure. These same low values of beta also result in a low terminal velocity, allowing the use of simple impact attenuation to provide a soft landing on water or dry land. Because the deployable fabric framework serves the functions of both heat shield and parachute, it is referred to as a ParaShield. The experience gained from the design, construction, and integration of a ParaShield test vehicle is discussed.
El uso de la neuromodulación para el tratamiento del temblor
Bendersky, Damián; Ajler, Pablo; Yampolsky, Claudio
Introducción: El temblor puede ser un desorden incapacitante y el tratamiento de primera línea para estos pacientes es farmacológico. Sin embargo, este tratamiento puede llevar a una reducción satisfactoria del temblor en sólo el 50% de los pacientes con temblor esencial. La talamotomía era el tratamiento de elección para el temblor refractario al tratamiento médico hasta que comenzó a utilizarse la estimulación cerebral profunda (ECP) del núcleo ventral intermedio (Vim) del tálamo. En la actualidad, raramente se realiza la talamotomía. Métodos: Este artículo es una revisión no sistemática de las indicaciones, resultados, parámetros de programación y técnica quirúrgica de la ECP del Vim para el tratamiento del temblor. Resultados: Aunque los resultados clínicos son similares usando la talamotomía o la ECP del Vim, la primera causa más efectos adversos que la última. Además, la ECP puede ser usada bilateralmente, mientras que la talamotomía tiene un alto riesgo de causar disartria cuando se realiza de ambos lados. La ECP del Vim logró una adecuada mejoría del temblor en varias series de pacientes con temblor causado por temblor esencial, enfermedad de Parkinson o esclerosis múltiple. Además del Vim, hay otros blancos que están siendo usados por varios autores, tales como la zona incerta y las radiaciones prelemniscales. Conclusión: La ECP del Vim es un tratamiento útil para el temblor incapacitante refractario al tratamiento médico. Es esencial realizar una precisa selección de pacientes, así como utilizar una técnica quirúrgica correcta. Aún se desconoce el mejor blanco estereotáctico para el temblor, aunque el Vim es el más usado. PMID:25165613
Melhoramentos no código Wilson-Devinney para binárias eclipsantes
NASA Astrophysics Data System (ADS)
Vieira, L. A.; Vaz, L. P. R.
A análise de curvas de luz e velocidades radiais de sistemas binários eclipsantes pode ser feita por meio de vários modelos. Um desses é o Modelo Wilson-Devinney (WD). Ao longo dos anos, esse modelo sofreu várias alterações em seus códigos principais, com a finalidade de torná-lo mais consistente tanto fíisica como numericamente. O Modelo WD tem sido melhorado de várias maneiras em seus dois códigos: um para a predição das curvas de luz teórica e de velocidade radiais e outra para as soluções destas curvas. Teoricamente, na física do modelo, nós introduzimos a possibilidade de levar em conta os efeitos do movimento apsidal. Numericamente, nós introduzimos a possibilidade de usar o Método SIMPLEX no procedimento da solução, como uma alternativa para o já implementado Método de Mínimos Quadrados (Least Squares Method). Estas modificações, juntamente com outras já introduzidas pelo nosso grupo anteriormente, tornam o código mais eficiente na solução das curvas de luz e de velocidade radiais de binárias eclipsantes. Como o modelo tem sido usado para analisar sistemas com componentes pré-sequência principal (TY CrA, Casey et al. 1998, Vaz et al. 1998), SM 790, Stassun et al. 2003), este melhoramento beneficiará estes casos também. Apresentamos os resultados obtidos com a modificação do código WD por meio do uso de dados da estrela GL Carinae, comprovando, (1) que os parâmetros orbitais calculados por nós são coerentes com os obtidos anteriormente na literatura (Giménez & Clausen, 1986) e com os obtidos por Faria (1987), e (2) que a implementação do Método SIMPLEX torna o código mais lento mas completamente consistente internamente e evita os problemas gerados pelo uso do Método de Mínimos Quadrados, tais como imprecisão no cálculo das derivadas parciais e convergência para mínimos locais.
ParaDyn Implementation in the US Navy's DYSMAS Simulation System: FY08 Progress Report
Ferencz, R M; DeGroot, A J; Lin, J I; Zywicz, E; Durrenberger, J K; Sherwood, R J; Corey, I R
The goal of this project is to increase the computational efficiency and capacity of the Navy's DYSMAS simulation system for full ship shock response to underwater explosion. Specifically, this project initiates migration to a parallel processing capability for the structural portion of the overall fluid-structure interaction model. The capstone objective for the first phase is to demonstrate operation of the DYSMAS simulation engine with a production model on a Naval Surface Warfare Center (IHD) parallel platform using the ParaDyn code for parallel processing of the structural dynamics. This year saw a successful launch to integrate ParaDyn, the high-parallel structural dynamics code from Lawrence Livermore National Laboratory (LLNL), into the DYSMAS system for simulating the response of ship structures to underwater explosion (UNDEX). The current LLNL version of DYNA3D, representing ten years of general development beyond the source branch used to initiate DYNA-N customization for DYSMAS, was first connected to the GEMINI flow code through DYSMAS Standard Coupler Interface (SCI). This permitted an early 'sanity check' by Naval Surface Warfare Center, Indian Head Division (NSWC-IHD) personnel that equivalent results were generated for their standard UNDEX test problems, thus ensuring the Verification & Validation pedigree they have developed remains intact. The ParaDyn code was then joined to the SCI in a manner requiring no changes to GEMINI. Three NSWC-IHD engineers were twice hosted at LLNL to become familiar with LLNL computer systems, the execution of the prototype software system, and to begin assessment of its accuracy and performance. Scaling data for the flow solver GEMINI was attained up to a one billion cell, 1000 processor run. The NSWC-IHD engineers were granted privileges to continue their evaluations through remote connections to LLNL's Open Computing Facility. Finally, the prototype changes were integrated into the mainline ParaDyn source
Conformational isomerism in the solid-state structures of tetracaine and tamoxifen with para-sulphonato-calix[4]arene
NASA Astrophysics Data System (ADS)
Danylyuk, Oksana; Monachino, Melany; Lazar, Adina N.; Suwinska, Kinga; Coleman, Anthony W.
The solid-state complexes between para-sulphonato-calix[4]arene and the drugs tamoxifen and tetracaine show an unusual 4:1 guest-host stoichiometry with formation of hydrophobic layer of drug molecules held between bilayers of para-sulphonato-calix[4]arene. In both structures each of the four independent drug molecules adopts different conformation due to the different mode of interaction with the anionic host, the neighbouring drug cations and water molecules.
Effects of para-substituents of styrene derivatives on their chemical reactivity on platinum nanoparticle surfaces
NASA Astrophysics Data System (ADS)
Hu, Peiguang; Chen, Limei; Deming, Christopher P.; Lu, Jia-En; Bonny, Lewis W.; Chen, Shaowei
Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent aggregation, suggesting sufficient protection of the nanoparticles by the organic capping ligands, and the average core diameter was estimated to be 2.0 +/- 0.3 nm, 1.3 +/- 0.2 nm, and 1.1 +/- 0.2 nm for the nanoparticles capped with 4-tert-butylstyrene, 4-methoxystyrene, and 4-(trifluoromethyl)styrene, respectively, as a result of the decreasing rate of dehydrogenation with the increasing Taft (polar) constant of the para-substituents. Importantly, the resulting nanoparticles exhibited unique photoluminescence, where an increase of the Hammett constant of the para-substituents corresponded to a blue-shift of the photoluminescence emission, suggesting an enlargement of the HOMO-LUMO band gap of the nanoparticle-bound acetylene moieties. Furthermore, the resulting nanoparticles exhibited apparent electrocatalytic activity towards oxygen reduction in acidic media, with the best performance among the series of samples observed with the 4-tert-butylstyrene-capped nanoparticles due to an optimal combination of the nanoparticle core size and ligand effects on the bonding interactions between platinum and oxygen species.Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent
Supported transition metal catalysts for para- to ortho-hydrogen conversion
NASA Technical Reports Server (NTRS)
Brooks, Christopher J.; Wang, Wei; Eyman, Darrell P.
The main goal of this study was to develop and improve on existing catalysts for the conversion of ortho- to para-hydrogen. Starting with a commercially available Air Products nickel silicate, which had a beta value of 20, we were trying to synthesize catalysts that would be an improvement to AP. This was accomplished by preparing silicates with various metals as well as different preparation methods. We also prepared supported ruthenium catalysts by various techniques using several metal precursors to improve present technology. What was also found was that the activation conditions prior to catalytic testing was highly important for both the silicates and the supported ruthenium catalysts. While not the initial focus of the research, we made some interesting observations into the adsorption of H2 on ruthenium. This helped us to get a better understanding of how ortho- to para-H2 conversion takes place, and what features in a catalyst are important to optimize activity. Reactor design was the final area in which some interesting conclusions were drawn. As discussed earlier, the reactor catalyst bed must be constructed using straight 1/8 feet OD stainless steel tubing. It was determined that the use of 1/4 feet OD tubing caused two problems. First, the radius from the center of the bed to the wall was too great for thermal equilibrium. Since the reaction of ortho- to para-H2 is exothermic, the catalyst bed center was warmer than the edges. Second, the catalyst bed was too shallow using a 1/4 feet tube. This caused reactant blow-by which was thought to decrease the measured activity when the flow rate was increased. The 1/8 feet tube corrected both of these concerns.
ParaSight-F rapid manual diagnostic test of Plasmodium falciparum infection.
Uguen, C.; Rabodonirina, M.; De Pina, J. J.; Vigier, J. P.; Martet, G.; Maret, M.; Peyron, F.
The ParaSight(R)-F test is a qualitative diagnostic test of Plasmodium falciparum, which is based on the detection by a monoclonal antibody of a species-specific soluble antigen (histidine-rich protein (HRP-II)) in whole blood and which can be performed without special equipment. A visual reading is given by a polyclonal antibody coupled with dye-loaded liposomes; when positive, a pink line appears. The test has been compared with microscopic examination of thin blood smears and with Quantitative Buffy Coat malaria test (QBC(R) in a single-blind study. A total of 358 patients who had returned to France from malarial areas and consulted their doctor with symptoms or for a routine examination were enrolled in the study; 33 of them were found to have a falciparum malaria infection by the diagnostic test. On the day of consultation, the specificity of the ParaSight(R)-F test was 99% and its sensitivity 94%. The follow-up of infected patients after treatment showed that the test became negative later than the other reference tests. There was no correlation between antigen persistence and the intensity of the ParaSight(R)-F signal or circulating parasitaemia. No cross-reaction was noted for seven malaria cases due to other Plasmodium species. The test was performed quickly (10 tests in 20 minutes), was easy to read, and required minimal space. For cases of imported malaria, the test's specificity and low threshold for detection could make it a valuable adjunct test. However, in its present form, it cannot replace microscopic techniques which are species-specific and quantitative. In endemic areas, the test seems to be very promising by its results and ease of use according to published field studies. Images Fig. 1 Fig. 2 PMID:8846490
Madres para la Salud: Design of a Theory-based Intervention for Postpartum Latinas
Keller, Colleen; Records, Kathie; Ainsworth, Barbara; Belyea, Michael; Permana, Paska; Coonrod, Dean; Vega-López, Sonia; Nagle-Williams, Allison
Background Weight gain in young women suggests that childbearing may be an important contributor to the development of obesity in women. Depressive symptoms can interfere with resumption of normal activity levels following childbirth or with the initiation of or adherence to physical activity programs essential for losing pregnancy weight. Depression symptoms may function directly to promote weight gain through a physiologic mechanism. Obesity and its related insulin resistance may contribute to depressed mood physiologically. Although physical activity has well-established beneficial effects on weight management and depression, women tend to under participate in physical activity during childbearing years. Further, the mechanisms underpinning the interplay of overweight, obesity, physical activity, depression, and inflammatory processes are not clearly explained. Objectives This report describes the theoretical rationale, design considerations, and cultural relevance for "Madres para la Salud" [Mothers for Health]. Design and Methods Madres para la Salud is a 12 month prospective, randomized controlled trial exploring the effectiveness of a culturally specific intervention using "bouts" of physical activity to effect changes in body fat, systemic and fat tissue inflammation, and postpartum depression symptoms in sedentary postpartum Latinas. Summary The significance and innovation of Madres para la Salud includes use of a theory-driven approach to intervention, specification and cultural relevance of a social support intervention, use of a Promotora model to incorporate cultural approaches, use of objective measures of physical activity in post partum Latinas women, and the examination of biomarkers indicative of cardiovascular risk related to physical activity behaviors in postpartum Latinas. PMID:21238614
Synthesis of icariin from kaempferol through regioselective methylation and para-Claisen–Cope rearrangement
Mei, Qinggang; Wang, Chun; Zhao, Zhigang; Yuan, Weicheng
Summary The hemisynthesis of the naturally occurring bioactive flavonoid glycoside icariin (1) has been accomplished in eleven steps with 7% overall yield from kaempferol. The 4′-OH methylation of kaempferol, the 8-prenylation of 3-O-methoxymethyl-4′-O-methyl-5-O-prenyl-7-O-benzylkaempferol (8) via para-Claisen–Cope rearrangement catalyzed by Eu(fod)3 in the presence of NaHCO3, and the glycosylation of icaritin (3) are the key steps. PMID:26425179
Summary of Documentation for DYNA3D-ParaDyn's Software Quality Assurance Regression Test Problems
Zywicz, Edward
The Software Quality Assurance (SQA) regression test suite for DYNA3D (Zywicz and Lin, 2015) and ParaDyn (DeGroot, et al., 2015) currently contains approximately 600 problems divided into 21 suites, and is a required component of ParaDyn's SQA plan (Ferencz and Oliver, 2013). The regression suite allows developers to ensure that software modifications do not unintentionally alter the code response. The entire regression suite is run prior to permanently incorporating any software modification or addition. When code modifications alter test problem results, the specific cause must be determined and fully understood before the software changes and revised test answers can be incorporated. The regression suite is executed on LLNL platforms using a Python script and an associated data file. The user specifies the DYNA3D or ParaDyn executable, number of processors to use, test problems to run, and other options to the script. The data file details how each problem and its answer extraction scripts are executed. For each problem in the regression suite there exists an input deck, an eight-processor partition file, an answer file, and various extraction scripts. These scripts assemble a temporary answer file in a specific format from the simulation results. The temporary and stored answer files are compared to a specific level of numerical precision, and when differences are detected the test problem is flagged as failed. Presently, numerical results are stored and compared to 16 digits. At this accuracy level different processor types, compilers, number of partitions, etc. impact the results to various degrees. Thus, for consistency purposes the regression suite is run with ParaDyn using 8 processors on machines with a specific processor type (currently the Intel Xeon E5530 processor). For non-parallel regression problems, i.e., the two XFEM problems, DYNA3D is used instead. When environments or platforms change, executables using the current source code and the new
Electrically conducting poly(para-phenylene sulfide) prepared by doping with nitrosyl salts from solution
NASA Astrophysics Data System (ADS)
Rubner, Michael; Cukor, Peter; Jopson, Harriet; Deits, Walter
Para(polyphenylene sulfide) may be doped spontaneously and rapidly with nitrosyl salts (NOPF6, NOSbF6) from solution to yield an electrically conducting material (10-1ohm-1cm-1). The level of conductivity is primarily dependent on the extent of dopant incorporation, which in turn is determined by the polymer's crystallinity; the more amorphous the polymer, the more dopant it takes up and the more conductive it becomes. The incorporation of dopants produces irreversible chemical changes in the polymer resulting in the deterioration of its mechanical properties.
ParaCEST MRI contrast agents capable of derivatization via"click" chemistry.
Milne, Mark; Chicas, Kirby; Li, Alex; Bartha, Robert; Hudson, Robert H E
A comprehensive series of lanthanide chelates has been prepared with a tetrapropargyl DOTAM type ligand. The complexes have been characterized by a combination of (1)H NMR, single-crystal X-ray crystallography, CEST and relaxation studies and have also been evaluated for potential use as paramagnetic chemical exchange saturation transfer (ParaCEST) contrast agents in magnetic resonance imaging (MRI). We demonstrate the functionalization of several chelates by means of alkyne-azide "click" chemistry in which a glucosyl azide is used to produce a tetra-substituted carbohydrate-decorated lanthanide complex. The carbohydrate periphery of the chelates has a potent influence on the CEST properties as described herein.
NMR at earth's magnetic field using para-hydrogen induced polarization.
Hamans, Bob C; Andreychenko, Anna; Heerschap, Arend; Wijmenga, Sybren S; Tessari, Marco
A method to achieve NMR of dilute samples in the earth's magnetic field by applying para-hydrogen induced polarization is presented. Maximum achievable polarization enhancements were calculated by numerically simulating the experiment and compared to the experimental results and to the thermal equilibrium in the earth's magnetic field. Simultaneous 19F and 1H NMR detection on a sub-milliliter sample of a fluorinated alkyne at millimolar concentration (∼10(18) nuclear spins) was realized with just one single scan. A highly resolved spectrum with a signal/noise ratio higher than 50:1 was obtained without using an auxiliary magnet or any form of radio frequency shielding.
Path integral molecular dynamics simulation of solid para-hydrogen with an aluminum impurity
NASA Astrophysics Data System (ADS)
Mirijanian, Dina T.; Alexander, Millard H.; Voth, Gregory A.
The equilibrium properties of an aluminum impurity trapped in solid para-hydrogen have been studied. The results were compared to those of a previous study by Krumrine et al. [J. Chem. Phys. 113 (2000) 9079] with an atomic boron. In the presence of vacancy defect, when the orientation-dependent Al- pH 2 potential is used, the Al atom is displaced to a position half way between its original substituted site and the vacancy site. Thermodynamic results also indicate that the presence of a neighboring vacancy helps to stabilize the Al impurity to a far greater extent than in the case of the B impurity.
Where does the electron go? The nature of ortho/para and meta group directing in electrophilic aromatic substitution.
Liu, Shubin
Electrophilic aromatic substitution as one of the most fundamental chemical processes is affected by atoms or groups already attached to the aromatic ring. The groups that promote substitution at the ortho/para or meta positions are, respectively, called ortho/para and meta directing groups, which are often characterized by their capability to donate electrons to or withdraw electrons from the ring. Though resonance and inductive effects have been employed in textbooks to explain this phenomenon, no satisfactory quantitative interpretation is available in the literature. Here, based on the theoretical framework we recently established in density functional reactivity theory (DFRT), where electrophilicity and nucleophilicity are simultaneously quantified by the Hirshfeld charge, the nature of ortho/para and meta group directing is systematically investigated for a total of 85 systems. We find that regioselectivity of electrophilic attacks is determined by the Hirshfeld charge distribution on the aromatic ring. Ortho/para directing groups have most negative charges on the ortho/para positions, while meta directing groups often possess the largest negative charge on the meta position. Our results do not support that ortho/para directing groups are electron donors and meta directing groups are electron acceptors. Most neutral species we studied here are electron withdrawal in nature. Anionic systems are always electron donors. There are also electron donors serving as meta directing groups. We predicted ortho/para and meta group directing behaviors for a list of groups whose regioselectivity is previously unknown. In addition, strong linear correlations between the Hirshfeld charge and the highest occupied molecular orbital have been observed, providing the first link between the frontier molecular orbital theory and DFRT.
Genetic evidence that the degradation of para-cresol by Geobacter metallireducens is catalyzed by the periplasmic para-cresol methylhydroxylase.
Chaurasia, Akhilesh Kumar; Tremblay, Pier-Luc; Holmes, Dawn E; Zhang, Tian
Two pathways for para-cresol (p-cresol) degradation by anaerobic bacteria have been elucidated; one involves fumarate addition at the methyl group of p-cresol by a hydroxylbenzylsuccinate synthase protein while the other utilizes a methylhydroxylase protein (PCMH) to catalyze hydroxylation of the methyl group of p-cresol. In Geobacter metallireducens, in vitro enzymatic assays showed that p-cresol is degraded via the methylhydroxylation pathway. However, prior to this study these results had not been confirmed by genetic analyses. In this work, the gene coding for benzylsuccinate-CoA dehydrogenase (bbsG), an enzyme required for toluene degradation by G. metallireducens that is homologous to the p-hydroxybenzylsuccinyl-CoA dehydrogenase involved in p-cresol degradation by Desulfobacula toluolica Tol2 via fumarate addition, and the gene encoding the alpha prime subunit of PCMH (pcmI), were deleted to investigate the possibility of co-existing p-cresol degradation pathways in G. metallireducens. The absence of a functional PcmI protein completely inhibited p-cresol degradation, while deletion of the bbsG gene had little impact. These results further support the observation that G. metallireducens utilizes a PCMH-initiated pathway for p-cresol degradation.
Para-position derivatives of fungal anthelmintic cyclodepsipeptides engineered with Streptomyces venezuelae antibiotic biosynthetic genes.
Yanai, Koji; Sumida, Naomi; Okakura, Kaoru; Moriya, Tatsuki; Watanabe, Manabu; Murakami, Takeshi
PF1022A, a cyclooctadepsipeptide possessing strong anthelmintic properties and produced by the filamentous fungus Rosellinia sp. PF1022, consists of four alternating residues of N-methyl-L-leucine and four residues of D-lactate or D-phenyllactate. PF1022A derivatives obtained through modification of their benzene ring at the para-position with nitro or amino groups act as valuable starting materials for the synthesis of compounds with improved anthelmintic activities. Here we describe the production of such derivatives by fermentation through metabolic engineering of the PF1022A biosynthetic pathway in Rosellinia sp. PF1022. Three genes cloned from Streptomyces venezuelae, and required for the biosynthesis of p-aminophenylpyruvate from chorismate in the chloramphenicol biosynthetic pathway, were expressed in a chorismate mutase-deficient strain derived from Rosellinia sp. PF1022. Liquid chromatography-mass spectrometry and NMR analyses confirmed that this approach facilitated the production of PF1022A derivatives specifically modified at the para-position. This fermentation method is environmentally safe and can be used for the industrial scale production of PF1022A derivatives.
Fire safety improvement of para-aramid fiber in thermoplastic polyurethane elastomer.
Chen, Xilei; Wang, Wenduo; Li, Shaoxiang; Jiao, Chuanmei
This article mainly studied fire safety effects of para-aramid fiber (AF) in thermoplastic polyurethane (TPU). The TPU/AF composites were prepared by molten blending method, and then the fire safety effects of all TPU composites were tested using cone calorimeter test (CCT), microscale combustion colorimeter test (MCC), smoke density test (SDT), and thermogravimetric/fourier transform infrared spectroscopy (TG-IR). The CCT test showed that AF could improve the fire safety of TPU. Remarkably, the peak value of heat release rate (pHRR) and the peak value of smoke production rate (pSPR) for the sample with 1.0wt% content of AF were decreased by 52.0% and 40.5% compared with pure TPU, respectively. The MCC test showed that the HRR value of AF-2 decreased by 27.6% compared with pure TPU. TG test showed that AF promoted the char formation in the degradation process of TPU; as a result the residual carbon was increased. The TG-IR test revealed that AF had increased the thermal stability of TPU at the beginning and reduced the release of CO2 with the decomposition going on. Through the analysis of the results of this experiment, it will make a great influence on the study of the para-aramid fiber in the aspect of fire safety of polymer.
Theoretical study of the preferential solvation effect on the solvatochromic shifts of para-nitroaniline.
Frutos-Puerto, Samuel; Aguilar, Manuel A; Fdez Galván, Ignacio
The origin of the nonlinear solvatochromic shift of para-nitroaniline was investigated using a mean-field sequential QM/MM method, with electron transitions computed at the CASPT2/cc-pVDZ level. Experimental data shows that the solvatochromic shift has a strong nonlinear behavior in certain solvent mixtures. We studied the case of cyclohexane-triethylamine mixtures. The results are in good agreement with the experiments and correctly reproduce the nonlinear variation of the solvent shift. Preferential solvation is clearly observed, where the local solvent composition in the neighborhood of the solute is significantly different from the bulk. It is found that even at low triethylamine concentrations a strong hydrogen bond is formed between para-nitroaniline and triethylamine, and cyclohexane is practically absent from the first solvation layer already at a molar fraction of 0.6 in triethylamine. The hydrogen bond formed is sufficiently long-lived to determine an asymmetric environment around the solute molecule. The resulting nonlinear solvent effect is mainly due to this hydrogen bond influence, although there is also a small contribution from dielectric enrichment.
Effects of acoustic feedback training in elite-standard Para-Rowing.
Schaffert, Nina; Mattes, Klaus
Assessment and feedback devices have been regularly used in technique training in high-performance sports. Biomechanical analysis is mainly visually based and so can exclude athletes with visual impairments. The aim of this study was to examine the effects of auditory feedback on mean boat speed during on-water training of visually impaired athletes. The German National Para-Rowing team (six athletes, mean ± s, age 34.8 ± 10.6 years, body mass 76.5 ± 13.5 kg, stature 179.3 ± 8.6 cm) participated in the study. Kinematics included boat acceleration and distance travelled, collected with Sofirow at two intensities of training. The boat acceleration-time traces were converted online into acoustic feedback and presented via speakers during rowing (sections with and without alternately). Repeated-measures within-participant factorial ANOVA showed greater boat speed with acoustic feedback than baseline (0.08 ± 0.01 m·s(-1)). The time structure of rowing cycles was improved (extended time of positive acceleration). Questioning of athletes showed acoustic feedback to be a supportive training aid as it provided important functional information about the boat motion independent of vision. It gave access for visually impaired athletes to biomechanical analysis via auditory information. The concept for adaptive athletes has been successfully integrated into the preparation for the Para-Rowing World Championships and Paralympics.
Rotational relaxation of CS by collision with ortho- and para-H{sub 2} molecules
Denis-Alpizar, Otoniel; Stoecklin, Thierry Halvick, Philippe; Dubernet, Marie-Lise
Quantum mechanical investigation of the rotationally inelastic collisions of CS with ortho- and para-H{sub 2} molecules is reported. The new global four-dimensional potential energy surface presented in our recent work is used. Close coupling scattering calculations are performed in the rigid rotor approximation for ortho- and para-H{sub 2} colliding with CS in the j = 0–15 rotational levels and for collision energies ranging from 10{sup −2} to 10{sup 3} cm{sup −1}. The cross sections and rate coefficients for selected rotational transitions of CS are compared with the ones previously reported for the collision of CS with He. The largest discrepancies are observed at low collision energy, below 1 cm{sup −1}. Above 10 cm{sup −1}, the approximation using the square root of the relative mass of the colliders to calculate the cross sections between a molecule and H{sub 2} from the data available with {sup 4}He is found to be a good qualitative approximation. The rate coefficients calculated with the electron gas model for the He-CS system show more discrepancy with our accurate results. However, scaling up these rates by a factor of 2 gives a qualitative agreement.
Effects of para-fluorine substituent of polystyrene on gradient-index fiber-optic properties
NASA Astrophysics Data System (ADS)
Koike, Kotaro; Suzuki, Akifumi; Makino, Kenji; Koike, Yasuhiro
To study the effects of fluorine substituent of polystyrene (PSt) on gradient-index fiber-optic properties, a poly(para-fluorostyrene) (P(p-FSt))-based graded-index plastic optical fiber (GI POF) is fabricated, and its properties are compared with those of a PSt-based GI POF. The para-fluorine substitution positively affects the glass transition temperature (Tg) of the core, wavelength dispersion of the optimum refractive index profile, bandwidth, and attenuation. The core Tg of the P(p-FSt)-based GI POF is 88 °C, which is higher than that of the PSt-based GI POF by 9 °C when both fibers have an identical numerical aperture (NA = 0.2). The optimum refractive index profile coefficient for the P(p-FSt)-based GI POF varies from 2.2 to 2.1 in the 600-800 nm range, whereas that for the PSt-based GI POF varies from 2.6 to 2.3 in the same wavelength region. The bandwidth of the P(p-FSt)-based GI POF is intrinsically higher than that of PSt-based GI POF. Moreover, the fiber attenuation of the P(p-FSt)-based GI POF was significantly smaller than that of the PSt-based GI POF over the source wavelength range. Our study demonstrates that P(p-FSt) has favorable properties as a GI POF base material.
Modelizacion, control e implementacion de un procesador energetico paralelo para aplicacion en sistemas multisalida
NASA Astrophysics Data System (ADS)
Ferreres Sabater, Agustin
Cualquier sistema electronico que incluya un procesado o tratamiento de la senal, y ademas, algun tipo de actuador mecanico generalmente necesita, como minimo, dos tensiones diferentes de alimentacion. Excluyendo los sistemas de alimentacion distribuida, la solucion tecnica mas utilizada para proporcionar dos o mas tensiones consiste en las fuentes de alimentacion multisalida. En una fuente de alimentacion multisalida los diferentes circuitos que conforman cada salida comparten un mismo transformador de potencia optimizando coste, masa, y volumen. Las ventajas obtenidas con este procedimiento tienen en su contra el efecto que sobre cada salida individual provocan las demas en su conjunto debido, principalmente, a los efectos de los elementos parasitos de los componentes. Un cambio de carga en una de las salidas produce un transitorio que es visto por todas las demas como un efecto de impedancia cruzada, y al final del transitorio, la tension de cada salida es diferente respecto a la que tenian antes del transitorio. Este ultimo resultado se conoce como regulacion cruzada. La disminucion de los efectos de la regulacion cruzada ha sido objeto de estudio durante los ultimos anos. El objetivo ha sido el desarrollo de distintas estrategias que permiten, desde disminuir los efectos de la regulacion cruzada hasta los niveles deseables, a eliminarla completamente. El resultado final suele suponer una penalizacion sobre el diseno del sistema directamente proporcional al grado de regulacion a conseguir en las distintas salidas. Entre las soluciones propuestas para eliminar la regulacion cruzada las tecnicas de post-regulacion se han consolidado como la opcion mas aceptada ya que, pueden aplicarse a cualquier convertidor y no suponen ninguna complejidad adicional a la hora de plantear el diseno. En esta Tesis Doctoral se abordara el estudio de la tecnica conocida como postregulacion mediante transformador controlado, que si bien se ha empleado en convertidores resonantes, su
WormBase ParaSite - a comprehensive resource for helminth genomics.
Howe, Kevin L; Bolt, Bruce J; Shafie, Myriam; Kersey, Paul; Berriman, Matthew
The number of publicly available parasitic worm genome sequences has increased dramatically in the past three years, and research interest in helminth functional genomics is now quickly gathering pace in response to the foundation that has been laid by these collective efforts. A systematic approach to the organisation, curation, analysis and presentation of these data is clearly vital for maximising the utility of these data to researchers. We have developed a portal called WormBase ParaSite (http://parasite.wormbase.org) for interrogating helminth genomes on a large scale. Data from over 100 nematode and platyhelminth species are integrated, adding value by way of systematic and consistent functional annotation (e.g. protein domains and Gene Ontology terms), gene expression analysis (e.g. alignment of life-stage specific transcriptome data sets), and comparative analysis (e.g. orthologues and paralogues). We provide several ways of exploring the data, including genome browsers, genome and gene summary pages, text search, sequence search, a query wizard, bulk downloads, and programmatic interfaces. In this review, we provide an overview of the back-end infrastructure and analysis behind WormBase ParaSite, and the displays and tools available to users for interrogating helminth genomic data.
Comparing the Well-Being of Para and Olympic Sport Athletes: A Systematic Review.
Macdougall, Hannah; O'Halloran, Paul; Shields, Nora; Sherry, Emma
This systematic review included 12 studies that compared the well-being of Para and Olympic sport athletes. Meta-analyses revealed that Para athletes, compared with Olympic sport athletes, had lower levels of self-acceptance, indicated by athletic identity, d = 0.47, 95% confidence interval (CI) [0.77, 0.16], and body-image perceptions, d = 0.33, 95% CI [0.59, 0.07], and differed from Olympic sport athletes in terms of their motivation, indicated by a greater mastery-oriented climate, d = 0.74, 95% CI [0.46, 1.03]. Given an inability to pool the remaining data for meta-analysis, individual standardized mean differences were calculated for other dimensions of psychological and subjective well-being. The results have implications for professionals and coaches aiming to facilitate the well-being needs of athletes under their care. Future research would benefit from incorporating established models of well-being based on theoretical rationale combined with rigorous study designs.
Asymmetric Top Rotors in Superfluid Para-Hydrogen Nano-Clusters
NASA Astrophysics Data System (ADS)
Zeng, Tao; Li, Hui; Roy, Pierre-Nicholas
We present the first simulation study of bosonic clusters doped with an asymmetric top molecule. A variation of the path-integral Monte Carlo method is developed to study a para-water (pH_2O) impurity in para-hydrogen (pH_2) clusters. The growth pattern of the doped clusters is similar in nature to that of the pure clusters. The pH_2O molecule appears to rotate freely in the cluster due to its large rotational constants and the lack of adiabatic following. The presence of pH_2O substantially quenches the superfluid response of pH_2 with respect to the space fixed frame. We also study the behaviour of a sulphur dioxide (32S16O_2) dopant in the pH_2 clusters. For such a heavy rotor, the adiabatic following of the pH_2 molecules is established and the superfluid renormalization of the rotational constants is observed. The rotational structure of the SO_2-p(H_2)_N clusters' ro-vibrational spectra is predicted. The connection between the superfluid response respect to the external boundary rotation and the dopant rotation is discussed.
Herschel/SPIRE observations of water production rates and ortho-to-para ratios in comets★
NASA Astrophysics Data System (ADS)
Wilson, Thomas G.; Rawlings, Jonathan M. C.; Swinyard, Bruce M.
This paper presents Herschel/SPIRE (Spectral and Photometric Imaging Receiver) spectroscopic observations of several fundamental rotational ortho- and para-water transitions seen in three Jupiter-family comets and one Oort-cloud comet. Radiative transfer models that include excitation by collisions with neutrals and electrons, and by solar infrared radiation, were used to produce synthetic emission line profiles originating in the cometary coma. Ortho-to-para ratios (OPRs) were determined and used to derived water production rates for all comets. Comparisons are made with the water production rates derived using an OPR of 3. The OPR of three of the comets in this study is much lower than the statistical equilibrium value of 3; however they agree with observations of comets 1P/Halley and C/2001 A2 (LINEAR), and the protoplanetary disc TW Hydrae. These results provide evidence suggesting that OPR variation is caused by post-sublimation gas-phase nuclear-spin conversion processes. The water production rates of all comets agree with previous work and, in general, decrease with increasing nucleocentric offset. This could be due to a temperature profile, additional water source or OPR variation in the comae, or model inaccuracies.
In-Situ Visualization Experiments with ParaView Cinema in RAGE
Kares, Robert John
A previous paper described some numerical experiments performed using the ParaView/Catalyst in-situ visualization infrastructure deployed in the Los Alamos RAGE radiation-hydrodynamics code to produce images from a running large scale 3D ICF simulation. One challenge of the in-situ approach apparent in these experiments was the difficulty of choosing parameters likes isosurface values for the visualizations to be produced from the running simulation without the benefit of prior knowledge of the simulation results and the resultant cost of recomputing in-situ generated images when parameters are chosen suboptimally. A proposed method of addressing this difficulty is to simply render multiple images at runtime with a range of possible parameter values to produce a large database of images and to provide the user with a tool for managing the resulting database of imagery. Recently, ParaView/Catalyst has been extended to include such a capability via the so-called Cinema framework. Here I describe some initial experiments with the first delivery of Cinema and make some recommendations for future extensions of Cinema's capabilities.
Association of plasma ortho-tyrosine/para-tyrosine ratio with responsiveness of erythropoiesis-stimulating agent in dialyzed patients.
Kun, Szilárd; Mikolás, Esztella; Molnár, Gergo A; Sélley, Eszter; Laczy, Boglárka; Csiky, Botond; Kovács, Tibor; Wittmann, István
Objectives Patients with end-stage renal failure (ESRF) treated with erythropoiesis-stimulating agents (ESAs) are often ESA-hyporesponsive associated with free radical production. Hydroxyl free radical converts phenylalanine into ortho-tyrosine, while physiological isomer para-tyrosine is formed enzymatically, mainly in the kidney. Production of 'para-tyrosine' is decreased in ESRF and it can be replaced by ortho-tyrosine in proteins. Our aim was to study the role of tyrosines in ESA-responsiveness. Methods Four groups of volunteers were involved in our cross-sectional study: healthy volunteers (CONTR; n = 16), patients on hemodialysis without ESA-treatment (non-ESA-HD; n = 8), hemodialyzed patients with ESA-treatment (ESA-HD; n = 40), and patients on continuous peritoneal dialysis (CAPD; n = 21). Plasma ortho-, para-tyrosine, and phenylalanine levels were detected using a high performance liquid chromatography (HPLC)-method. ESA-demand was expressed by ESA-dose, ESA-dose/body weight, and erythropoietin resistance index1 (ERI1, weekly ESA-dose/body weight/hemoglobin). Results We found significantly lower para-tyrosine levels in all groups of dialyzed patients when compared with control subjects, while in contrast ortho-tyrosine levels and ortho-tyrosine/para-tyrosine ratio were comparatively significantly higher in dialyzed patients. Among groups of dialyzed patients the ortho-tyrosine level and ortho-tyrosine/para-tyrosine ratio were significantly higher in ESA-HD than in the non-ESA-HD and CAPD groups. There was a correlation between weekly ESA-dose/body weight, ERI1, and ortho-tyrosine/para-tyrosine ratio (r = 0.441, P = 0.001; r = 0.434, P = 0.001, respectively). Our most important finding was that the ortho-tyrosine/para-tyrosine ratio proved to be an independent predictor of ERI1 (β = 0.330, P = 0.016). In these multivariate regression models most of the known predictors of ESA-hyporesponsiveness were included. Discussion Our findings may
Um enfoque antropológico para o ensino de astronomia no nível médio
NASA Astrophysics Data System (ADS)
Costa, G. B.; Jafelice, L. C.
Há uma enorme carência de materiais didático-pedagógicos em astronomia para professores do ensino médio, sobretudo materiais que explorem também aspectos humanísticos. A origem do Universo é um bom exemplo desta constatação central. Embora tal origem teve explicações culturais diversas, os professores não têm informações sobre isso e muito menos material que trabalhe diferentes visões de mundo e treinamento que os capacite a abordá-las devidamente. Conseqüentemente o ensino de astronomia costuma ser tecnicista e dissociado do aspecto humano que alimenta o grande interesse e curiosidade que esses temas despertam. Aqui apresentamos propostas visando contribuir para reverter esse quadro e trabalhamos distintas visões de Universo: espontâneas, autóctones e científicas. Desenvolvemos práticas, materiais instrucionais e textos para viabilizar a adoção de um enfoque antropológico para o ensino de astronomia no nível médio, no qual as culturas humanística e científica sejam integradas de uma maneira contextualizada e eficaz para aquele ensino. Estas propostas foram aplicadas em um curso de treinamento para professores da rede pública de diferentes disciplinas. A receptividade dos professores à abordagem proposta e os resultados alcançados foram muito estimulantes. Destes, destacamos: produção de roteiros de atividades; desenvolvimento de práticas didático-pedagógicas específicas (e.g., encenação de mitos; dança primordial guarani; "criação" de constelações e interpretações pluriculturais; etc.); e sugestões concretas para a efetiva realização de um ensino interdisciplinar contextualizado, onde questões cosmogônicas servem de mote para iniciar tal ensino. Discutimos estes resultados e como o enfoque adotado pode instrumentalizar os professores para leituras de mundo que incluem naturalmente aspectos culturais, sociais e históricos associados aos temas estudados. (PPGECNM/UFRN; PRONEX/FINEP; NUPA/USP; Temáticos/FAPESP)
Comparing para-rowing set-ups on an ergometer using kinematic movement patterns of able-bodied rowers.
Cutler, B; Eger, T; Merritt, T; Godwin, A
While numerous studies have investigated the biomechanics of able-bodied rowing, few studies have been completed with para-rowing set-ups. The purpose of this research was to provide benchmark data for handle kinetics and joint kinematics for able-bodied athletes rowing in para- rowing set-ups on an indoor ergometer. Able-bodied varsity rowers performed maximal trials in three para-rowing set-ups; Legs, Trunk and Arms (LTA), Trunk and Arms (TA) and Arms and Shoulders (AS) rowing. The handle force kinetics of the LTA stroke were comparable to the values for able-bodied literature. Lumbar flexion at the catch, extension at the finish and total range of motion were, however, greater than values in the literature for able-bodied athletes in the LTA set-up. Additionally, rowers in TA and AS set-ups utilised more extreme ranges of motion for lumbar flexion, elbow flexion and shoulder abduction than the LTA set-up. This study provides the first biomechanical values of the para-rowing strokes for researchers, coaches and athletes to use while promoting the safest training programmes possible for para-rowing.
Ordered expression pattern of Hox and ParaHox genes along the alimentary canal in the ascidian juvenile.
Nakayama, Satoshi; Satou, Kunihiro; Orito, Wataru; Ogasawara, Michio
The Hox and ParaHox genes of bilateria share a similar expression pattern along the body axis and are known to be associated with anterior-posterior patterning. In vertebrates, the Hox genes are also expressed in presomitic mesoderm and gut endoderm and the ParaHox genes show a restricted expression pattern in the gut-related derivatives. Regional expression patterns in the embryonic central nervous system of the basal chordates amphioxus and ascidian have been reported; however, little is known about their endodermal expression in the alimentary canal. We focus on the Hox and ParaHox genes in the ascidian Ciona intestinalis and investigate the gene expression patterns in the juvenile, which shows morphological regionality in the alimentary canal. Gene expression analyses by using whole-mount in situ hybridization reveal that all Hox genes have a regional expression pattern along the alimentary canal. Expression of Hox1 to Hox4 is restricted to the posterior region of pharyngeal derivatives. Hox5 to Hox13 show an ordered expression pattern correlated with each Hox gene number along the postpharyngeal digestive tract. This expression pattern along the anterior-posterior axis has also been observed in Ciona ParaHox genes. Our observations suggest that ascidian Hox and ParaHox clusters are dispersed; however, the ordered expression patterns along the alimentary canal appear to be conserved among chordates.
Determination of the ortho to para ratio of H2Cl+ and H2O+ from submillimeter observations.
Gerin, Maryvonne; de Luca, Massimo; Lis, Dariusz C; Kramer, Carsten; Navarro, Santiago; Neufeld, David; Indriolo, Nick; Godard, Benjamin; Le Petit, Franck; Peng, Ruisheng; Phillips, Thomas G; Roueff, Evelyne
The opening of the submillimeter sky with the Herschel Space Observatory has led to the detection of new interstellar molecular ions, H2O(+), H2Cl(+), and HCl(+), which are important intermediates in the synthesis of water vapor and hydrogen chloride. In this paper, we report new observations of H2O(+) and H2Cl(+) performed with both Herschel and ground-based telescopes, to determine the abundances of their ortho and para forms separately and derive the ortho-to-para ratio. At the achieved signal-to-noise ratio, the observations are consistent with an ortho-to-para ratios of 3 for both H2O(+) and H2Cl(+), in all velocity components detected along the lines-of-sight to the massive star-forming regions W31C and W49N. We discuss the mechanisms that contribute to establishing the observed ortho-to-para ratio and point to the need for a better understanding of chemical reactions, which are important for establishing the H2O(+) and H2Cl(+) ortho-to-para ratios.
Amine vs. carboxylic acid protonation in ortho-, meta-, and para-aminobenzoic acid: An IRMPD spectroscopy study
NASA Astrophysics Data System (ADS)
Cismesia, Adam P.; Nicholls, Georgina R.; Polfer, Nicolas C.
Infrared multiple photon dissociation (IRMPD) spectroscopy and computational chemistry are applied to the ortho-, meta-, and para- positional isomers of aminobenzoic acid to investigate whether the amine or the carboxylic acid are the favored sites of proton attachment in the gas phase. The NH and OH stretching modes yield distinct patterns that establish the carboxylic acid as the site of protonation in para-aminobenzoic acid, as opposed to the amine group in ortho- and meta-aminobenzoic acid, in agreement with computed thermochemistries. The trends for para- and meta-substitutions can be rationalized simplistically by inductive effects and resonant stabilization, and will be discussed in light of computed charge distributions based from electrostatic potentials. In ortho-aminobenzoic acid, the close proximity of the amine and acid groups allow a simultaneous interaction of the proton with both groups, thus stabilizing and delocalizing the charge more effectively, and compensating for some of the resonance stabilization effects.
A Case of Advanced Gastric Cancer with Para-Aortic Lymph Node Metastasis from Co-Occurring Prostate Cancer
Park, Miyeong; Lee, Young-Joon; Park, Ji-Ho; Choi, Sang-Kyung; Hong, Soon-Chan; Jung, Eun-Jung; Ju, Young-tae; Jeong, Chi-Young; Lee, Jeong-Hee; Ha, Woo-Song
An 84-year-old man was diagnosed with two synchronous adenocarcinomas, a Borrmann type IV advanced gastric adenocarcinoma in his antrum and a well-differentiated Borrmann type I carcinoma on the anterior wall of the higher body of his stomach. Pre-operatively, computed tomography of the abdomen revealed the presence of advanced gastric cancer with peri-gastric and para-aortic lymph node (LN) metastasis. He planned for palliative total gastrectomy owing to the risk of obstruction by the antral lesion. We performed a frozen biopsy of a para-aortic LN during surgery and found that the origin of the para-aortic LN metastasis was from undiagnosed prostate cancer. Thus, we performed radical total gastrectomy and D2 LN dissection. Post-operatively, his total prostate-specific antigen levels were high (227 ng/mL) and he was discharged 8 days after surgery without any complications. PMID:28337367
Molecular hydrogen in the vicinity of NGC 7538 IRS 1 and IRS 2 - Temperature and ortho-to-para ratio
NASA Technical Reports Server (NTRS)
Hoban, Susan; Reuter, Dennis C.; Mumma, Michael J.; Storrs, Alex D.
Near-infrared spectroscopic observations of the active star-forming region near NGC 7538 IRS 1 and IRS 2 were made. The relative intensities of the v = 1-0 Q(1), Q(3), and Q(5) lines of molecular hydrogen are used to calculate a rotational excitation temperature. Comparison of the measured intensity of the Q(2) transition relative to the intensity of Q(1) and Q(3) permitted the retrieval of the ratio of ortho-to-para hydrogen. It is found that an ortho-to-para ratio of between 1.6 and 2.35 is needed to explain the Q-branch line intensity ratios, depending on the excitation model used. This range in ortho-to-para ratios implies a range of molecular hydrogen formation temperature of approximately 105 K to 140 K.
Prevalence and risk factors for Cysticercus tenuicollis in goats and sheep in Paraíba, northeastern Brazil.
Morais, Dayana Firmino de; Vilela, Vinícius Longo Ribeiro; Feitosa, Thais Ferreira; Santos, Vinícius Mamede Dos; Gouveia, Vitória Régia; Athayde, Ana Célia Rodrigues; Azevêdo, Sérgio Santos de
This study aimed to determine the prevalence and risk factors for C. tenuicollis among goats and sheep in slaughterhouses in Paraíba. 390 animals (195 goats and 195 sheep) in the municipalities of Patos and Esperança, Paraíba, Brazil, were inspected between February and May 2014. The prevalence of C. tenuicollis was 39% (76/195) in goats and 17.4% (34/195) in sheep. In both species, most of the cysticerci vesicles were located at the omentum and mesentery. The only risk factor found was extensive sheep farming. It can be concluded that C. tenuicollis is highly prevalent in small ruminants in Paraíba, being more prevalent in goats than in sheep. Extensively-reared sheep were twice as likely to develop infection by this parasite.
Metabolism of Doubly para-Substituted Hydroxychlorobiphenyls by Bacterial Biphenyl Dioxygenases
Pham, Thi Thanh My; Sondossi, Mohammad
In this work, we examined the profile of metabolites produced from the doubly para-substituted biphenyl analogs 4,4′-dihydroxybiphenyl, 4-hydroxy-4′-chlorobiphenyl, 3-hydroxy-4,4′-dichlorobiphenyl, and 3,3′-dihydroxy-4,4′-chlorobiphenyl by biphenyl-induced Pandoraea pnomenusa B356 and by its biphenyl dioxygenase (BPDO). 4-Hydroxy-4′-chlorobiphenyl was hydroxylated principally through a 2,3-dioxygenation of the hydroxylated ring to generate 2,3-dihydro-2,3,4-trihydroxy-4′-chlorobiphenyl and 3,4-dihydroxy-4′-chlorobiphenyl after the removal of water. The former was further oxidized by the biphenyl dioxygenase to produce ultimately 3,4,5-trihydroxy-4′-chlorobiphenyl, a dead-end metabolite. 3-Hydroxy-4,4′-dichlorobiphenyl was oxygenated on both rings. Hydroxylation of the nonhydroxylated ring generated 2,3,3′-trihydroxy-4′-chlorobiphenyl with concomitant dechlorination, and 2,3,3′-trihydroxy-4′-chlorobiphenyl was ultimately metabolized to 2-hydroxy-4-chlorobenzoate, but hydroxylation of the hydroxylated ring generated dead-end metabolites. 3,3′-Dihydroxy-4,4′-dichlorobiphenyl was principally metabolized through a 2,3-dioxygenation to generate 2,3-dihydro-2,3,3′-trihydroxy-4,4′-dichlorobiphenyl, which was ultimately converted to 3-hydroxy-4-chlorobenzoate. Similar metabolites were produced when the biphenyl dioxygenase of Burkholderia xenovorans LB400 was used to catalyze the reactions, except that for the three substrates used, the BPDO of LB400 was less efficient than that of B356, and unlike that of B356, it was unable to further oxidize the initial reaction products. Together the data show that BPDO oxidation of doubly para-substituted hydroxychlorobiphenyls may generate nonnegligible amounts of dead-end metabolites. Therefore, biphenyl dioxygenase could produce metabolites other than those expected, corresponding to dihydrodihydroxy metabolites from initial doubly para-substituted substrates. This finding shows that a clear
Shinnaka, Yoshiharu; Kawakita, Hideyo; Kobayashi, Hitomi; Boice, Daniel C.; Martinez, Susan E.
The ortho-to-para abundance ratio (OPR) of cometary molecules is considered to be one of the primordial characteristics of cometary ices, and contains information concerning their formation. Water is the most abundant species in cometary ices, and OPRs of water in comets have been determined from infrared spectroscopic observations of H{sub 2}O rovibrational transitions so far. In this paper, we present a new method to derive OPR of water in comets from the high-dispersion spectrum of the rovibronic emission of H{sub 2}O{sup +} in the optical wavelength region. The rovibronic emission lines of H{sub 2}O{sup +} are sometimes contaminated by other molecular emission lines but they are not affected seriously by telluric absorption compared with near-infrared observations. Since H{sub 2}O{sup +} ions are mainly produced from H{sub 2}O by photoionization in the coma, the OPR of H{sub 2}O{sup +} is considered to be equal to that of water based on the nuclear spin conservation through the reaction. We have developed a fluorescence excitation model of H{sub 2}O{sup +} and applied it to the spectrum of comet C/2001 Q4 (NEAT). The derived OPR of water is 2.54{sup +0.32}{sub -0.25}, which corresponds to a nuclear spin temperature (T{sub spin}) of 30{sup +10}{sub -4} K. This is consistent with the previous value determined in the near-infrared for the same comet (OPR = 2.6 {+-} 0.3, T{sub spin} = 31{sup +11}{sub -5} K).
Precision velocimetry planet hunting with PARAS: current performance and lessons to inform future extreme precision radial velocity instruments
NASA Astrophysics Data System (ADS)
Roy, Arpita; Chakraborty, Abhijit; Mahadevan, Suvrath; Chaturvedi, Priyanka; Prasad, Neelam J. S. S. V.; Shah, Vishal; Pathan, F. M.; Anandarao, B. G.
The PRL Advanced Radial-velocity Abu-sky Search (PARAS) instrument is a fiber-fed stabilized high-resolution cross-dispersed echelle spectrograph, located on the 1.2 m telescope in Mt. Abu India. Designed for exoplanet detection, PARAS is capable of single-shot spectral coverage of 3800 - 9600 Å, and currently achieving radial velocity (RV) precisions approaching 1 m s-1 over several months using simultaneous ThAr calibration. As such, it is one of the few dedicated stabilized fiber-fed spectrographs on small (1-2 m) telescopes that are able to fill an important niche in RV follow-up and stellar characterization. The success of ground-based RV surveys is motivating the push into extreme precisions, with goals of 10 cm s-1 in the optical and <1 m s-1 in the near-infrared (NIR). Lessons from existing instruments like PARAS are invaluable in informing hardware design, providing pipeline prototypes, and guiding scientific surveys. Here we present our current precision estimates of PARAS based on observations of bright RV standard stars, and describe the evolution of the data reduction and RV analysis pipeline as instrument characterization progresses and we gather longer baselines of data. Secondly, we discuss how our experience with PARAS is a critical component in the development of future cutting edge instruments like (1) the Habitable Zone Planet Finder (HPF), a near-infrared spectrograph optimized to look for planets around M dwarfs, scheduled to be commissioned on the Hobby Eberly Telescope in 2017, and (2) the NEID optical spectrograph, designed in response to the NN-EXPLORE call for an extreme precision Doppler spectrometer (EPDS) for the WIYN telescope. In anticipation of instruments like TESS and GAIA, the ground-based RV support system is being reinforced. We emphasize that instruments like PARAS will play an intrinsic role in providing both complementary follow-up and battlefront experience for these next generation of precision velocimeters.
Practical in-situ determination of ortho-para hydrogen ratios via fiber-optic based Raman spectroscopy
Sutherland, Liese -Marie; Knudson, James N.; Mocko, Michal; ...
An experiment was designed and developed to prototype a fiber-optic-based laser system, which measures the ratio of ortho-hydrogen to para-hydrogen in an operating neutron moderator system at the Los Alamos Neutron Science Center (LANSCE) spallation neutron source. Preliminary measurements resulted in an ortho to para ratio of 3.06:1, which is within acceptable agreement with the previously published ratio. As a result, the successful demonstration of Raman Spectroscopy for this measurement is expected to lead to a practical method that can be applied for similar in-situ measurements at operating neutron spallation sources.
Ruthenium-Catalyzed Ortho C-H Arylation of Aromatic Nitriles with Arylboronates and Observation of Partial Para Arylation.
Koseki, Yuta; Kitazawa, Kentaroh; Miyake, Masashi; Kochi, Takuya; Kakiuchi, Fumitoshi
Ruthenium-catalyzed C-H arylation of aromatic nitriles with arylboronates is described. The use of RuH2(CO){P(4-MeC6H4)3}3 as a catalyst provided higher yields of the ortho arylation products than the conventional RuH2(CO)(PPh3)3 catalyst. The arylation takes place mostly at the ortho positions, but unprecedented para arylation was also partially observed to give ortho,para diarylation products. In addition to C-H bond cleavage, the cyano group was also found to function as a directing group for cleavage of C-O bonds in aryl ethers.
Evaluation of para-dichlorobenzene emissions from solid moth repellant as a source of indoor air pollution
Chang, J.C.S.; Krebs, K.A.
The paper reports results of dynamic and static chamber tests to evaluate para-dichlorobenzene emission rates from mothcakes. The data were analyzed by a model that assumes that the emission rate is controlled by gas-phase mass transfer. Results indicate that the para-dichlorobenzene emission from mothcakes is a temperature-sensitive sublimation process. Full-scale house tests were also conducted to measure mass transfer coefficients based on the model developed. The values of the mass transfer coefficient obtained are very comparable to those estimated by theoretical heat transfer studies.
Uma grade de perfis teóricos para estrelas massivas em transição
NASA Astrophysics Data System (ADS)
Nascimento, C. M. P.; Machado, M. A.
Na XXVIII Reunião Anual da Sociedade Astronômica Brasileira (2002) apresentamos uma grade de perfis calculados de acordo com os pontos da trajetória evolutiva de metalicidade solar, Z = 0.02 e taxa de perda de massa () padrão, para estrelas com massa inicial de 25, 40, 60, 85 e 120 massas solares. Estes perfis foram calculados com o auxílio de um código numérico adequado para descrever os ventos de objetos massivos, supondo simetria esférica, estacionaridade e homogeneidade. No presente trabalho, apresentamos a complementação da grade com os perfis teóricos relativos às trajetórias de Z = 0.02 com taxa de perda de massa dobrada em relação a padrão (2´), e de metalicidade Z = 0.008. Para cada ponto das três trajetórias obtemos os perfis teóricos de Ha, Hb, Hg e Hd, e como esperado eles se apresentam em pura emissão, pura absorção ou em P-Cygni. Para valores de taxa de perda de massa muito baixos (~10-7) não há formação de linhas, o que é visto nos primeiros pontos em todas as trajetórias. Em geral, para um mesmo ponto a componente de emissão diminui e a absorção aumenta de Ha para Hd. É verificado que as trajetórias com Z = 0.02 e padrão possuem menos circuitos (loops) do que as com metalicidade Z = 0.02 e 2´ padrão, e seus perfis são, em geral, menos intensos. Em relação a trajetória de Z = 0.008, verifica-se menos circuitos e maior variação em luminosidade, e seus perfis mostram-se em, algumas trajetórias, mais intensos. Verificamos também que, pontos distintos em uma mesma trajetória, apresentam perfis diferentes para valores similares de luminosidade e temperatura efetiva. Sendo assim, uma grade de perfis teóricos parece ser útil para fornecer uma informação preliminar sobre o estágio evolutivo de uma estrela massiva.
Fluorescence resonance energy transfer for investigation of the interaction of Para Red with serum albumins.
Zhu, Lin; Zeng, Xiaodan; Zhang, Fusheng
Para Red (PR) has been isolated from food additives, and shown to be toxic to humans. To facilitate examination of its toxicity, the interaction between PR and serum albumins (SA) was studied using fluorescence quenching and circular dichroism (CD) spectrophotometry. The experiments showed that the fluorescence intensity of serum albumins decreased with increasing concentrations of PR, which resulted from the binding of PR and SA. The binding constant, number of binding sites and thermodynamic parameters were calculated and hydrogen bond and van der Waals interactions were shown to play a key role in the binding process. Competition experiments indicated that PR mainly binds to Trp residues of SA within the site I. As the CD and three-dimensional spectra revealed, the addition of PR induced a conformational change in SA.
El Proyecto Sismico "LARSE" - Trabajando Hacia un Futuro con Mas Seguridad para Los Angeles
Henyey, Thomas L.; Fuis, Gary S.; Benthien, Mark L.; Burdette, Thomas R.; Christofferson, Shari A.; Clayton, Robert W.; Criley, Edward E.; Davis, Paul M.; Hendley, James W.; Kohler, Monica D.; Lutter, William J.; McRaney, John K.; Murphy, Janice M.; Okaya, David A.; Ryberg, Trond; Simila, Gerald W.; Stauffer, Peter H.
La region de Los Angeles contiene una red de fallas activas, incluyendo muchas fallas por empuje que son profundas y no rompen la superficie de la tierra. Estas fallas ocultas incluyen la falla anteriormente desconocida que fue responsable por la devastacion que ocurrio durante el terremoto de Northridge en enero de 1994, el terremoto mas costoso en la historia de los Estados Unidos. El Experimento Sismico en la Region de Los Angeles (Los Angeles Region Seismic Experiment, LARSE), esta localizando los peligros ocultos de los terremotos debajo de la region de Los Angeles para mejorar la construccion de las estructuras que pueden apoyar terremotos que son inevitables en el futuro, y que ayudaran a los cientificos determinar donde occurira el sacudimento mas fuerte y poderoso.
Analysis of the thermal reaction products of para polyphenylene by combined gas chromatography-mass spectrometry
NASA Technical Reports Server (NTRS)
Fewell, L. L.
Analysis of the volatiles and sublimate produced when para-polyphenylene is pyrolyzed to constant weight under vacuum in the temperature range from 380 to 1000 C indicates that the polymer undergoes thermal degradation in two stages. The first stage involved dehydrohalogenation, which is essentially a curing reaction that produces crosslinking between polyphenylene chains resulting from the loss of chlorine from the polymer in the form of hydrogen chloride. The second stage of the thermal degradation is dehydrogenation because hydrogen is the major volatile species. Increasing amounts of polycyclic aromatic hydrocarbons (phenanthrene and 9, 10 benzphenanthrene) in the sublimate, concomitant with increasing C/H ratios of the polymeric residue with pyrolysis temperature, is consistent with the buildup of polynuclear structures in the polymer matrix.
pH-dependent spectral properties of para-aminobenzoic acid and its derivatives
NASA Astrophysics Data System (ADS)
Thayer, Mitchell P.; McGuire, Colin; Stennett, Elana M. S.; Lockhart, Mary Kate; Canache, Daniela; Novak, Marnie; Schmidtke, Sarah J.
The local environment dictates the structural and functional properties of many important chemical and biological systems. The impact of pH on the photophysical properties of a series of para-aminobenzoic acids is examined using a combination of experimental spectroscopy and quantum chemical calculations. Following photoexcitation, PABA derivatives may undergo an intramolecular charge transfer (ICT) resulting in the formation of a zwitterionic species. The thermodynamics of the excited state reaction and temperature-dependence of the radiative emission processes are evaluated through variable temperature fluorescence spectroscopy carried out in a range of aqueous buffers. Quantum chemical calculations are used to analyze structural changes with modifications at the amine position and different protonation states. The ICT is only observed in the tertiary amine, which calculations show has more sp 2 character than the primary or secondary amines. Thermodynamic analysis indicates the ICT reaction is driven by entropy.
Searching for Auxetics with DYNA3D and ParaDyn
Hoover, W G; Hoover, C G
We sought to simulate auxetic behavior by carrying out dynamic analyses of mesoscopic model structures. We began by generating nearly periodic cellular structures. Four-node 'Shell' elements and eight-node 'Brick' elements are the basic building blocks for each cell. The shells and bricks obey standard elastic-plastic continuum mechanics. The dynamical response of the structures was next determined for a three-stage loading process: (1) homogeneous compression; (2) viscous relaxation; (3) uniaxial compression. The simulations were carried out with both serial and parallel computer codes--DYNA3D and ParaDyn--which describe the deformation of the shells and bricks with a robust contact algorithm. We summarize the results found here.
Leaf Pressure Volume Data in Caxiuana and Tapajos National Forest, Para, Brazil (2011)
Powell, Thomas; Moorcroft, Paul
Pressure volume curve measurements on leaves of canopy trees from the from the Caxiuana and Tapajos National Forests, Para, Brazil. Tapajos samples were harvested from the km 67 forested area, which is adjacent to the decommissioned throughfall exclusion drought experimental plot. Caxiuana samples were harvested from trees growing in the throughfall exclusion plots. Data were collected in 2011. Dataset includes: date of measurement, site ID, plot ID, tree ID (species, tree tag #), leaf area, fresh weight, relative weight, leaf water potential, and leaf water loss. P-V curve parameters (turgor loss point, osmotic potential, and bulk modulus of elasticity) can be found in Powell et al. (2017) Differences in xylem cavitation resistance and leaf hydraulic traits explain differences in drought tolerance among mature Amazon rainforest trees. Global Change Biology.
Evaluation of apparent viscosity of Para rubber latex by diffuse reflection near-infrared spectroscopy.
Sirisomboon, Panmanas; Chowbankrang, Rawiphan; Williams, Phil
Near-infrared spectroscopy in diffuse reflection mode was used to evaluate the apparent viscosity of Para rubber field latex and concentrated latex over the wavelength range of 1100 to 2500 nm, using partial least square regression (PLSR). The model with ten principal components (PCs) developed using the raw spectra accurately predicted the apparent viscosity with correlation coefficient (r), standard error of prediction (SEP), and bias of 0.974, 8.6 cP, and -0.4 cP, respectively. The ratio of the SEP to the standard deviation (RPD) and the ratio of the SEP to the range (RER) for the prediction were 4.4 and 16.7, respectively. Therefore, the model can be used for measurement of the apparent viscosity of field latex and concentrated latex in quality assurance and process control in the factory.
Genomic organization of Hox and ParaHox clusters in the echinoderm, Acanthaster planci.
Baughman, Kenneth W; McDougall, Carmel; Cummins, Scott F; Hall, Mike; Degnan, Bernard M; Satoh, Nori; Shoguchi, Eiichi
The organization of echinoderm Hox clusters is of interest due to the role that Hox genes play in deuterostome development and body plan organization, and the unique gene order of the Hox complex in the sea urchin Strongylocentrotus purpuratus, which has been linked to the unique development of the axial region. Here, it has been reported that the Hox and ParaHox clusters of Acanthaster planci, a corallivorous starfish found in the Pacific and Indian oceans, generally resembles the chordate and hemichordate clusters. The A. planci Hox cluster shared with sea urchins the loss of one of the medial Hox genes, even-skipped (Evx) at the anterior of the cluster, as well as organization of the posterior Hox genes.
[Neurocience in the Junta para Ampliación de Estudios].
Díaz, Alfredo Baratas
The development of the Neurociencias in the Spain at the first third of the 20th century had a strong histological and pathological component. The work of Santiago Ramon and Cajal and Luis Simarro was continued by some excellent disciples: Nicolas Achúcarro, Gonzalo Rodriguez Lafora, Fernando de Castro, etc. Some of them had to make compatible diverse occupations, even the professional exercise of psychiatry, before obtaining a modest - but stable - position of investigation. In spite of some misalignments in the institutional development of the centers and the personal biographical ups and downs, the Junta para Ampliación de Estudios was the great institution that fomented the international formation of the investigators and equipped to them with the means to develop its work.
Parallel Grand Canonical Monte Carlo (ParaGrandMC) Simulation Code
NASA Technical Reports Server (NTRS)
Yamakov, Vesselin I.
This report provides an overview of the Parallel Grand Canonical Monte Carlo (ParaGrandMC) simulation code. This is a highly scalable parallel FORTRAN code for simulating the thermodynamic evolution of metal alloy systems at the atomic level, and predicting the thermodynamic state, phase diagram, chemical composition and mechanical properties. The code is designed to simulate multi-component alloy systems, predict solid-state phase transformations such as austenite-martensite transformations, precipitate formation, recrystallization, capillary effects at interfaces, surface absorption, etc., which can aid the design of novel metallic alloys. While the software is mainly tailored for modeling metal alloys, it can also be used for other types of solid-state systems, and to some degree for liquid or gaseous systems, including multiphase systems forming solid-liquid-gas interfaces.
A Very Rare Cause of a Relapsing Para-Oesophageal Abscess
Wespi, Simon Peter; Frei, Remus; Sulz, Michael Christian
Oesophageal involvement in Crohn's disease (CD) is uncommon and most often accompanied by involvement of more distal parts. Its presentation is mostly non-specific, and therefore a diagnosis, especially in isolated oesophageal disease, is difficult. We present the case of a 42-year-old male patient who was referred to our gastroenterology department because of a para-oesophageal abscess. Under antibiotic treatment the abscess healed, but despite great diagnostic efforts, its aetiology remained unclear. Three years later the patient was hospitalized again because of an abscess at the same site. Endoscopy showed disseminated ulcerations of the lower oesophagus, raising suspicion of CD. After excluding other possible causes, we made the diagnosis of isolated CD of the oesophagus. We review the available literature on this topic and discuss the clinical presentation, symptoms, endoscopic findings, and histology as well as treatment of oesophageal CD. PMID:27403115
pH-dependent spectral properties of para-aminobenzoic acid and its derivatives.
Thayer, Mitchell P; McGuire, Colin; Stennett, Elana M S; Lockhart, Mary Kate; Canache, Daniela; Novak, Marnie; Schmidtke, Sarah J
The local environment dictates the structural and functional properties of many important chemical and biological systems. The impact of pH on the photophysical properties of a series of para-aminobenzoic acids is examined using a combination of experimental spectroscopy and quantum chemical calculations. Following photoexcitation, PABA derivatives may undergo an intramolecular charge transfer (ICT) resulting in the formation of a zwitterionic species. The thermodynamics of the excited state reaction and temperature-dependence of the radiative emission processes are evaluated through variable temperature fluorescence spectroscopy carried out in a range of aqueous buffers. Quantum chemical calculations are used to analyze structural changes with modifications at the amine position and different protonation states. The ICT is only observed in the tertiary amine, which calculations show has more sp(2) character than the primary or secondary amines. Thermodynamic analysis indicates the ICT reaction is driven by entropy.
Food for Life / Comida para la Vida: creating a food festival to raise diabetes awareness.
Lancaster, Kristie; Walker, Willie; Vance, Thomas; Kaskel, Phyllis; Arniella, Guedy; Horowitz, Carol
African and Latino Americans have higher rates of diabetes and its complications than White Americans. Identifying people with undiagnosed diabetes and helping them obtain care can help to prevent complications and mortality. To kick off a screening initiative, our community-academic partnership created the "Food for Life Festival," or "Festival Comida para la Vida." This article will describe the community's perspective on the Festival, which was designed to screen residents, and demonstrate that eating healthy can be fun, tasty, and affordable in a community-centered, culturally consonant setting. More than 1,000 residents attended the event; 382 adults were screened for diabetes, and 181 scored as high risk. Fifteen restaurants distributed free samples of healthy versions of their popular dishes. Community residents, restaurateurs, and clinicians commented that the event transformed many of their preconceived ideas about healthy foods and patient care.
Food for Life/Comida para la Vida: Creating a Food Festival to Raise Diabetes Awareness
Lancaster, Kristie; Walker, Willie; Vance, Thomas; Kaskel, Phyllis; Arniella, Guedy; Horowitz, Carol
African and Latino Americans have higher rates of diabetes and its complications than White Americans. Identifying people with undiagnosed diabetes and helping them obtain care can help to prevent complications and mortality. To kick off a screening initiative, our community-academic partnership created the "Food for Life Festival," or "Festival Comida para la Vida." This article will describe the community's perspective on the Festival, which was designed to screen residents, and demonstrate that eating healthy can be fun, tasty, and affordable in a community-centered, culturally consonant setting. More than 1,000 residents attended the event; 382 adults were screened for diabetes, and 181 scored as high risk. Fifteen restaurants distributed free samples of healthy versions of their popular dishes. Community residents, restaurateurs, and clinicians commented that the event transformed many of their preconceived ideas about healthy foods and patient care. PMID:20097997
Theoretical and Experimental Studies on the Nonlinear Optical Chromophore para Bromoacetanilide
NASA Astrophysics Data System (ADS)
Jothy, V. Bena; Vijayakumar, T.; Jayakumar, V. S.; Udayalekshmi, K.; Ramamurthy, K.; Joe, I. Hubert
Vibrational spectral analysis of the hydrogen bonded non-linear optical (NLO) material para Bromo Acetanilide (PBA) is carried out using NIR FT-Raman and FT-IR spectroscopy. Ab initio molecular orbital computations have been performed at HF/6-31G(d) level to derive equilibrium geometry, vibrational wavenumbers, intensities and first hyperpolarizability. The lowering of the imino stretching wavenumbers suggests the existence of strong intermolecular N-H⋯O hydrogen bonding substantiated by the natural bond orbital (NBO) analysis. Blue shifting CH stretching wavenumbers, simultaneous activation of carbonyl stretching mode and the strong activation of low wavenumber H-bond stretching vibrations shows the presence of intramolecular charge transfer in the molecule.
Quantum dynamical simulations for nuclear spin selective laser control of ortho- and para-fulvene.
Belz, S; Grohmann, T; Leibscher, M
In the present paper we explore the prospects for laser control of the photoinduced nonadiabatic dynamics of para- and ortho-fulvene with the help of quantum dynamical simulations. Previous investigations [Bearpark et al., J. Am. Chem. Soc. 118, 5253 (1996); Alfalah et al., J. Chem. Phys. 130, 124318 (2009)] show that photoisomerization of fulvene is hindered by ultrafast radiationless decay through a conical intersection at planar configuration. Here, we demonstrate that photoisomerization can nevertheless be initiated by damping unfavorable nuclear vibrations with properly designed laser pulses. Moreover, we show that the resulting intramolecular torsion is nuclear spin selective. The selectivity of the photoexcitation with respect to the nuclear spin isomers can be further enhanced by applying an optimized sequence of two laser pulses.
Searching for auxetics with DYNA3D and ParaDyn
NASA Astrophysics Data System (ADS)
Hoover, Wm. G.; Hoover, C. G.
We sought to simulate auxetic behavior by carrying out dynamic analyses of mesoscopic model structures. We began by generating nearly periodic cellular structures. Four-node Shell elements and eight-node Brick elements are the basic building blocks for each cell. The shells and bricks obey standard elastic-plastic continuum mechanics. The dynamical response of the structures was next determined for a three-stage loading process: (1) homogeneous compression; (2) viscous relaxation; (3) uniaxial compression. The simulations were carried out with both serial and parallel computer codes - DYNA3D and ParaDyn - which describe the deformation of the shells and bricks with a robust contact algorithm. We summarize the results found here.
Wild birds as pets in Campina Grande, Paraíba State, Brazil: an ethnozoological approach.
Licarião, Morgana R; Bezerra, Dandara M M; Alves, Rômulo R N
Birds are one of the animals most widely used by humans and are highly valued as pets. The present work reports the use of wild birds as pets in the city of Campina Grande, Paraíba State (PB), Brazil. The owners' choice and perceptions of the species ecology was assessed as well. The methodology employed included unstructured and semi-structured interviews, guided tours and direct observations. A total of 26 bird species distributed among ten families and four orders were identified. The most frequently encountered order was Passeriformes (76.9%), with a predominance of the family Emberizidae (34.6%). The specimens kept as pets were principally obtained in public markets or between the breeders themselves. The popularity of birds as pets, compounded by the inefficiency of official controls over the commerce of wild animals has stimulated the illegal capture and breeding of wild birds in Campina Grande.
Proyecto para la medición sistemática de seeing en CASLEO
NASA Astrophysics Data System (ADS)
Fernández Lajus, E.; Forte, J. C.
La calidad del seeing astronómico es ciertamente uno de los parámetros mas importantes que caracterizan el sitio de un observatorio. Por tanto se desea determinar si el alto valor de seeing observado con el telescopio de 2.15 m se debe a efectos internos y/o del entorno a la cupula o si se debe simplemente al seeing propio del lugar. El actual mecanismo de refrigeración del espejo primario del 2.15, parece haber mejorado notablemente la calidad del seeing. Sin embargo se hace necesario saber hasta que punto el valor del seeing puede ser mejorado. La primera etapa del proyecto consistió en la puesta a punto del telescopio emplazado para este propósito y la adquisición de las primeras medidas tentativas de seeing.
Coordination nano-space as stage of hydrogen ortho-para conversion.
Kosone, Takashi; Hori, Akihiro; Nishibori, Eiji; Kubota, Yoshiki; Mishima, Akio; Ohba, Masaaki; Tanaka, Hiroshi; Kato, Kenichi; Kim, Jungeun; Real, José Antonio; Kitagawa, Susumu; Takata, Masaki
The ability to design and control properties of nano-sized space in porous coordination polymers (PCPs) would provide us with an ideal stage for fascinating physical and chemical phenomena. We found an interconversion of nuclear-spin isomers for hydrogen molecule H2 adsorbed in a Hofmann-type PCP, {Fe(pz)[Pd(CN)4]} (pz=pyrazine), by the temperature dependence of Raman spectra. The ortho (o)-para (p) conversion process of H2 is forbidden for an isolated molecule. The charge density study using synchrotron radiation X-ray diffraction reveals the electric field generated in coordination nano-space. The present results corroborate similar findings observed on different systems and confirm that o-p conversion can occur on non-magnetic solids and that electric field can induce the catalytic hydrogen o-p conversion.
Applicability of the ParaDNA(®) Screening System to Seminal Samples.
Tribble, Nicholas D; Miller, Jamie A D; Dawnay, Nick; Duxbury, Nicola J
Seminal fluid represents a common biological material recovered from sexual assault crime scenes. Such samples can be prescreened using different techniques to determine cell type and relative amount before submitting for full STR profiling. The ParaDNA(®) Screening System is a novel forensic test which identifies the presence of DNA through amplification and detection of two common STR loci (D16S539 and TH01) and the Amelogenin marker. The detection of the Y allele in samples could provide a useful tool in the triage and submission of sexual assault samples by enforcement authorities. Male template material was detected on a range of common sexual assault evidence items including cotton pillow cases, condoms, swab heads and glass surfaces and shows a detection limit of 1 in 1000 dilution of neat semen. These data indicate this technology has the potential to be a useful tool for the detection of male donor DNA in sexual assault casework.
Shaped Ceria Nanocrystals Catalyze Efficient and Selective Para-Hydrogen-Enhanced Polarization.
Zhao, Evan W; Zheng, Haibin; Zhou, Ronghui; Hagelin-Weaver, Helena E; Bowers, Clifford R
Intense para-hydrogen-enhanced NMR signals are observed in the hydrogenation of propene and propyne over ceria nanocubes, nano-octahedra, and nanorods. The well-defined ceria shapes, synthesized by a hydrothermal method, expose different crystalline facets with various oxygen vacancy densities, which are known to play a role in hydrogenation and oxidation catalysis. While the catalytic activity of the hydrogenation of propene over ceria is strongly facet-dependent, the pairwise selectivity is low (2.4% at 375 °C), which is consistent with stepwise H atom transfer, and it is the same for all three nanocrystal shapes. Selective semi-hydrogenation of propyne over ceria nanocubes yields hyperpolarized propene with a similar pairwise selectivity of (2.7% at 300 °C), indicating product formation predominantly by a non-pairwise addition. Ceria is also shown to be an efficient pairwise replacement catalyst for propene.
Unusual Raman spectra of para-nitroaniline by sequential Fermi resonances.
Xia, Jiarui; Zhu, Ling; Feng, Yanting; Li, Yongqing; Zhang, Zhenglong; Xia, Lixin; Liu, Liwei; Ma, Fengcai
In this communication, we report the unusual Raman spectra of para-nitroaniline (PNA) by sequential Fermi resonances. The combinational mode 1292 cm(-1) in the experimental Raman spectrum indirectly gains the initial spectral weight at 1392 cm(-1) by three sequential Fermi resonances. These Fermi resonances result in the strong interaction between the donor group of NH2 and the acceptor group of NO2. Our theoretical calculations provide reasonable interpretation for the abnormal Raman spectra of PNA. Experimental surface enhanced Raman scattering (SERS) spectrum of PNA further confirmed our conclusion, where the strongest Raman peak at 1292 cm(-1) is very weak, while the Raman peak at 1392 cm(-1) becoming the strongest Raman peak, which is consistent with the theoretical simulations.
Long-range excitons in conjugated polymers with ring torsions: poly( para-phenylene) and polyaniline
NASA Astrophysics Data System (ADS)
Harigaya, Kikuo
Ring torsion effects on the optical excitation properties of poly( para-phenylene) (PPP) and polyaniline (PAN) are investigated by extending the Shimoi-Abe model (Shimoi Y and Abe S 1996 Synth. Met. 78 219). The model is solved using the intermediate-exciton formalism. Long-range excitons are characterized, and the long-range component of the oscillator strengths is calculated. We find that ring torsions affect the long-range excitons in PAN more readily than those in PPP, due to the larger torsion angle of PAN and the large number of bonds whose hopping integrals are modulated by torsions. Next, ring torsional disorder effects simulated by the Gaussian distribution function are analysed. The long-range component of the total oscillator strengths after sample averaging is nearly independent of the disorder strength in the PPP case, while that in the PAN case decreases readily as the disorder becomes stronger.
Path integral centroid molecular dynamics simulation of para-hydrogen sandwiched by graphene sheets
NASA Astrophysics Data System (ADS)
Minamino, Yuki; Kinugawa, Kenichi
The carbon-hydrogen composite systems of para-hydrogen (p-H2) sandwiched by a couple of graphene sheets have been investigated by means of path integral centroid molecular dynamics simulations at 17 K. It has been shown that sandwiched hydrogen is liquid-like but p-H2 molecules are preferably adsorbed onto the graphene sheets because of attractive graphene-hydrogen interaction. The diffusion coefficient of p-H2 molecules in the direction parallel to the graphene sheets is comparable to that in pure liquid p-H2. There exists a characteristic mode of 140 cm-1 of the p-H2 molecules, attributed to adsorption-binding motion perpendicular to the graphene sheets.
Extraperitoneal Robotic-Assisted Para-Aortic Lymphadenectomy in Gynecologic Cancer Staging: Current Evidence.
Bogani, Giorgio; Ditto, Antonino; Martinelli, Fabio; Signorelli, Mauro; Chiappa, Valentina; Sabatucci, Ilaria; Scaffa, Cono; Lorusso, Domenica; Raspagliesi, Francesco
We reviewed the current evidence on the safety, effectiveness, and applicability of extraperitoneal robotic-assisted para-aortic lymphadenectomy (ExtRA-PAL) as the staging procedure of gynecologic malignancies. PubMed (MEDLINE), Scopus, Web of Science databases, and ClinicalTrials.gov were searched for original studies reporting outcomes of ExtRA-PAL. Quality of the included studies and their level of recommendation were assessed using the Grading of Recommendations, Assessment, Development, and Evaluation and the American College of Obstetricians and Gynecologists guidelines, respectively. Overall, 62 studies were identified; after a process of evidence acquisition 5 original investigations were available for this review that included 98 patients undergoing ExtRA-PAL. The main surgical indication was staging for cervical cancer (n = 71, 72%). The mean (SD) number of para-aortic node yielded was 15.4 (±4.7) nodes. Blood transfusion and intraoperative complication rates were 2% and 6%, respectively. ExtRA-PAL was completed in 88 patients (90%). Six (6%) and 4 (4%) patients had conversion to other minimally invasive procedures and open surgery, respectively. Success rate was 99% among patients undergoing ExtRA-PAL without concomitant procedures. Overall, mean (SD) length of hospital stay was 2.8 (±0.5) days. Twenty-four patients (24%) developed postoperative events. According to the Clavien-Dindo grading system, grades IIIa and IIIb morbidity rates were 12% and 2%, respectively. No grades IV and V morbidity occurred. ExtRA-PAL is associated with a high success rate and a relative low morbidity rate. However, because of the limited data on this issue, further studies are warranted to assess the long-term effectiveness of this procedure.
Effects of lead on K(+)-para-nitrophenyl phosphatase activity and protection by thiol reagents.
Rajanna, B; Chetty, C S; McBride, V; Rajanna, S
Lead (Pb) inhibited K(+)-stimulated para-nitrophenyl phosphatase (K(+)-PNPPase) of rat brain P2 fraction in a concentration-dependent manner with IC50 3.5 microM. Altered pH versus activity demonstrated comparable inhibitions by Pb in buffered acidic, neutral and alkaline pH ranges. Inhibition of enzyme activity was higher at lower temperatures (17-27 degrees C) compared to 37 degrees C. Preincubation of enzyme with sulfhydryl (-SH) agents such as cysteine (Cyst) and dithiothreitol (DTT) but not glutathione (GSH) protected against Pb-inhibition. Uncompetitive type of inhibition with respect to the activation of K+ was indicated by a decrease in Vmax from 16.2 to 8.37 mumoles of para-nitrophenol (PNP)/mg protein/hr and Km from 18.99 to 12.39 mM. Kinetic studies on substrate (p-nitrophenyl phosphate) activation in the presence of Pb (3.5 microM) indicated a significant decrease in Vmax from 8.94 to 4.69 mumoles of PNP/mg protein/hr with no change in Km. Cyst (3 microM) and DTT (10 microM) reversed the Pb-inhibited Vmax from 4.69 to 8.38 and 7.24 mumoles of PNP/mg protein/hr respectively. These results suggest that the critical conformational property of K(+)-PNPPase is sensitive to Pb. The data also indicates that the Pb inhibits Na(+)-K+ ATPase system by interacting with dephosphorylation of the enzyme-phosphoryl complex, while Cyst and DTT protected against Pb-inhibition.
On Ensino de Astronomia: Desafios para Implantação
NASA Astrophysics Data System (ADS)
Faria, R. Z.; Voelzke, M. R.
Em 2002 o ensino de Astronomia foi proposto como um dos temas estruturadores pelos Parâmetros Curriculares Nacionais e sugerido como facilitador para que o aluno compreendesse a Física como construção humana e parte do seu mundo vivencial, mas raramente seus conceitos foram ensinados. A presente pesquisa discute dois aspectos relacionados à abordagem de Astronomia. O primeiro aspecto é se ela está sendo abordada pelos professores do Ensino Médio e o segundo, aborda a maneira como ela está sendo ensinada. Optou-se pela aplicação de um questionário a partir do 2° semestre de 2006 e durante o ano de 2007 com professores que ministram a disciplina de Física, os quais trabalham em escolas estaduais em Rio Grande da Serra, Ribeirão Pires e Mauá no estado São Paulo. Dos 66,2% dos professores que responderam ao questionário nos municípios de Rio Grande da Serra, Ribeirão Pires e Mauá, 57,4% não aplicaram nenhum tópico de astronomia, 70,2% não utilizaram laboratório, 89,4% não utilizaram qualquer tipo de programa computacional, 83,0% nunca fizeram visitas com alunos a museus e planetários e 38,3% não indicaram qualquer tipo de livro ou revista referente à astronomia aos seus alunos. Mesmo considerando a Astronomia um conteúdo potencialmente significativo, esta não fez parte dos planejamentos escolares. Portanto são necessárias propostas que visem estratégias para a educação continuada dos professores como, por exemplo, cursos específicos sobre o ensino em Astronomia.
Anion photoelectron spectroscopy of deprotonated ortho-, meta-, and para-methylphenol.
Nelson, Daniel J; Gichuhi, Wilson K; Miller, Elisa M; Lehman, Julia H; Lineberger, W Carl
The anion photoelectron spectra of ortho-, meta-, and para-methylphenoxide, as well as methyl deprotonated meta-methylphenol, were measured. Using the Slow Electron Velocity Map Imaging technique, the Electron Affinities (EAs) of the o-, m-, and p-methylphenoxyl radicals were measured as follows: 2.1991±0.0014, 2.2177±0.0014, and 2.1199±0.0014 eV, respectively. The EA of m-methylenephenol was also obtained, 1.024±0.008 eV. In all four cases, the dominant vibrational progressions observed are due to several ring distortion vibrational normal modes that were activated upon photodetachment, leading to vibrational progressions spaced by ∼500 cm(-1). Using the methylphenol O-H bond dissociation energies reported by King et al. and revised by Karsili et al., a thermodynamic cycle was constructed and the acidities of the methylphenol isomers were determined as follows: ΔacidH298K(0)=348.39±0.25, 348.82±0.25, 350.08±0.25, and 349.60±0.25 kcal/mol for cis-ortho-, trans-ortho-, m-, and p-methylphenol, respectively. The excitation energies for the ground doublet state to the lowest excited doublet state electronic transition in o-, m-, and p-methylphenoxyl were also measured as follows: 1.029±0.009, 0.962±0.002, and 1.029±0.009 eV, respectively. In the photoelectron spectra of the neutral excited states, C-O stretching modes were excited in addition to ring distortion modes. Electron autodetachment was observed in the cases of both m- and p-methylphenoxide, with the para isomer showing a lower photon energy onset for this phenomenon.
Anion photoelectron spectroscopy of deprotonated ortho-, meta-, and para-methylphenol
NASA Astrophysics Data System (ADS)
Nelson, Daniel J.; Gichuhi, Wilson K.; Miller, Elisa M.; Lehman, Julia H.; Lineberger, W. Carl
The anion photoelectron spectra of ortho-, meta-, and para-methylphenoxide, as well as methyl deprotonated meta-methylphenol, were measured. Using the Slow Electron Velocity Map Imaging technique, the Electron Affinities (EAs) of the o-, m-, and p-methylphenoxyl radicals were measured as follows: 2.1991±0.0014, 2.2177±0.0014, and 2.1199±0.0014 eV, respectively. The EA of m-methylenephenol was also obtained, 1.024±0.008 eV. In all four cases, the dominant vibrational progressions observed are due to several ring distortion vibrational normal modes that were activated upon photodetachment, leading to vibrational progressions spaced by ˜500 cm-1. Using the methylphenol O-H bond dissociation energies reported by King et al. and revised by Karsili et al., a thermodynamic cycle was constructed and the acidities of the methylphenol isomers were determined as follows: Δa c i dH298K 0=348.39 ±0.25 , 348.82±0.25, 350.08±0.25, and 349.60±0.25 kcal/mol for cis-ortho-, trans-ortho-, m-, and p-methylphenol, respectively. The excitation energies for the ground doublet state to the lowest excited doublet state electronic transition in o-, m-, and p-methylphenoxyl were also measured as follows: 1.029±0.009, 0.962±0.002, and 1.029±0.009 eV, respectively. In the photoelectron spectra of the neutral excited states, C-O stretching modes were excited in addition to ring distortion modes. Electron autodetachment was observed in the cases of both m- and p-methylphenoxide, with the para isomer showing a lower photon energy onset for this phenomenon.
Electron Spin Polarization Transfer to ortho-H2 by Interaction of para-H2 with Paramagnetic Species: A Key to a Novel para → ortho Conversion Mechanism.
Terenzi, Camilla; Bouguet-Bonnet, Sabine; Canet, Daniel
We report that at ambient temperature and with 100% enriched para-hydrogen (p-H2) dissolved in organic solvents, paramagnetic spin catalysis of para → ortho hydrogen conversion is accompanied at the onset by a negative ortho-hydrogen (o-H2) proton NMR signal. This novel finding indicates an electron spin polarization transfer, and we show here that this can only occur if the H2 molecule is dissociated upon its transient adsorption by the paramagnetic catalyst. Following desorption, o-H2 is created until the thermodynamic equilibrium is reached. A simple theory confirms that in the presence of a static magnetic field, the hyperfine coupling between unpaired electrons and nuclear spins is responsible for the observed polarization transfer. Owing to the negative electron gyromagnetic ratio, this explains the experimental results and ascertains an as yet unexplored mechanism for para → ortho conversion. Finally, we show that the recovery of o-H2 magnetization toward equilibrium can be simply modeled, leading to the para → ortho conversion rate.
[Genetics and the Junta para Ampliación de Estudios e Investigaciones Científicas].
Peláez, Raquel Alvarez
The aim of this paper is to show the essential paper developed by the Junta para Ampliación de Estudios in the origin of the Spanish genetics, using for that the most relevant researchers of the time, and between them two women, Jimena Fernández de la Vega and Käte Pariser.
A Conceptual Model for Supporting Para-Teacher Learning in an Indian Non-Governmental Organization (NGO)
ERIC Educational Resources Information Center
Raval, Harini; McKenney, Susan; Pieters, Jules
Non-governmental organizations (NGOs) are being recognized globally for their influential role in realizing the UN Millennium Development Goal of education for all in developing countries. NGOs mostly employ untrained para-educators for grassroots activities. The professional development of these teachers is critical for NGO effectiveness, yet…
Millimeter-wave spectroscopy of S2Cl2: a candidate molecule for measuring ortho-para transition.
Dehghani, Zeinab Tafti; Ota, Shinji; Mizoguchi, Asao; Kanamori, Hideto
S2Cl2 is a candidate for the observation of ortho-para transition. To estimate the ortho-para mixing in a hyperfine-resolved rotational state, pure rotational transitions were measured by millimeter-wave (mm-wave) spectroscopy using two different experimental set-ups. The transitions from the term value around 20 K was measured with a supersonic jet and those around 200 K were measured with a dry ice cooled gas cell. Several hundred peaks were assigned for the naturally abundant S2(35)Cl2 and S2(35)Cl(37)Cl isotopic species and the rotational molecular parameters including the fourth-order and sixth-order centrifugal distortion constants were determined. The hyperfine structures were partly resolved in some Q-branch transitions, which were well described with the hyperfine constants determined by FTMW spectroscopy in the centimeter-wave region. With the new rotational constants determined in our study and the previous hyperfine constants, it will be possible to obtain a more reliable ortho-para mixing ratio and to narrow down the possible candidate transitions in the mm-wave region for the observation of ortho-para transition.
Electrochemical determination of para-nitrophenol at apatite-modified carbon paste electrode: application in river water samples.
El Mhammedi, M A; Achak, M; Bakasse, M; Chtaini, A
The behavior of a modified carbon paste electrode (CPE) for para-nitrophenol detection by cyclic and square wave voltammetry (SWV) was studied. The electrode was built by incorporating the hydroxyapatite (HAP) to carbon paste. The overall analysis involved a two-step procedure: an accumulation step at open circuit, followed by medium exchange to a pure electrolyte solution for the voltammetric quantification. During the preconcentration step, para-nitrophenol was adsorbed onto hydroxyapatite surface. The influence of various experimental parameters on the HAP-CPE response was investigated (i.e. pH, carbon paste composition, accumulation time). Under the optimized conditions, the reduction peak shows that the peak height was found to be directly proportional to the para-nitrophenol concentration in the range comprised between 2x10(-7) mol L(-1) and 1x10(-4) mol L(-1). With this, it was possible to determine detection limit (DL), which resulted in 8x10(-9) mol L(-1) for peak 1. The proposed electrode (HAP-CPE) presented good repeatability, evaluated in term of relative standard deviation (R.S.D.=2.87%) for n=7 and was applied for para-nitrophenol determination in water samples. The average recovery for these samples was 86.2%.
Two experiments were performed to determine the rate of vitellogenin plasma accumulation and clearance in male sheepshead minnows (Cyprinodon variegatus) during and after exposure to either 17b-estradiol (E2) or para-nonylphenol (p-NP). Adult fish were continuously exposed to aqu...
Four novel sequences in Drosophila melanogaster homologous to the auxiliary Para sodium channel subunit TipE.
Derst, Christian; Walther, Christian; Veh, Rüdiger W; Wicher, Dieter; Heinemann, Stefan H
TipE is an auxiliary subunit of the Drosophila Para sodium channel. Here we describe four sequences, TEH1-4, homologous to TipE in the Drosophila melanogaster genome, harboring all typical structures of both TipE and the beta-Subunit family of big-conductance Ca(2+)-activated potassium channels: short cytosolic N- and C-terminal stretches, two transmembrane domains, and a large extracellular loop with two disulfide bonds. Whereas TEH1 and TEH2 lack the TipE-specific extension in the extracellular loop, both TEH3 and TEH4 possess two extracellular EGF-like domains. A CNS-specific expression was found for TEH1, while TEH2-4 were more widely expressed. The genes for TEH2-4 are localized close to the tipE gene on chromosome 3L. Coexpression of TEH subunits with Para in Xenopus oocytes showed a strong (30-fold, TEH1), medium (5- to 10-fold, TEH2 and TEH3), or no (TEH4) increase in sodium current amplitude, while TipE increased the current 20-fold. In addition, steady-state inactivation and the recovery from fast inactivation were altered by coexpression of Para with TEH1. We conclude that members of the TEH-family are auxiliary subunits for Para sodium channels and possibly other ion channels.
Factor Analysis of the Spanish Version of the WAIS: The Escala de Inteligencia Wechsler para Adultos (EIWA).
ERIC Educational Resources Information Center
Gomez, Francisco C., Jr.; And Others
The standardization of the Escala de Inteligencia Wechsler para Adultos (EIWA) and the original Wechsler Adult Intelligence Scale (WAIS) were subjected to principal components analysis to examine their comparability for 616 EIWA subjects and 800 WAIS subjects. Similarity of factor structures of both scales is supported. (SLD)
75 FR 34943 - Defense Federal Acquisition Regulation Supplement; Para-Aramid Fibers and Yarns Manufactured in a...
Federal Register 2010, 2011, 2012, 2013, 2014
... made from DuPont Kevlar. DuPont supplies its Kevlar staple fiber to four major and six minor yarn... para-aramid yarns: DuPont TM which makes Kevlar , and the Teijin Group which makes Twaron. DuPont TM...
Contribuições para o projeto da câmara infravermelha Spartan do telescópio SOAR
NASA Astrophysics Data System (ADS)
Laporte, R.; Jablonski, F.; Loh, E.
Como parte de uma colaboração entre a Divisão de Astrofísica do INPE, IAG-USP, Instituto do Milênio MEGALIT e a Michigan State University, trabalhamos durante um ano junto ao grupo do Dr. Edwin Loh (MSU) no projeto e detalhamento de diversos subsistemas para a câmara infravermelho Spartan do telescópio SOAR. Trata-se de um imageador para as bandas J, H e K que explora todo o potencial, em termos de qualidade de imagem e campo de visada, fornecido pelo sistema de óptica adaptativa de primeira ordem do telescópio SOAR. Projetamos soluções detalhadas para os subsistemas de rodas de filtros/grismas/máscaras de Lyot; subsistema de compactação do mosaico de detectores em duas versões distintas; subsistema de alimentação de Nitrogênio líquido. Mantivemos sempre uma supervisão geral sobre todas as partes restantes e os respectivos envelopes volumétricos produzindo soluções para a integração de todos os componentes. Neste trabalho, ilustramos as principais contribuições e fornecemos um resumo do estado atual do instrumento.
Violencia de Pareja en Mujeres Hispanas: Implicaciones para la Investigación y la Práctica
Gonzalez-Guarda, Rosa Maria; Becerra, Maria Mercedes
Las investigaciones sobre la violencia entre parejas sugieren que las mujeres hispanas están siendo afectadas desproporcionadamente por la ocurrencia y consecuencias de este problema de salud pública. El objetivo del presente artículo es dar a conocer el estado del arte en relación a la epidemiologia, consecuencias y factores de riesgo para VP entre mujeres Hispanas, discutiendo las implicaciones para la investigación y la práctica. Investigaciones han demostrado una fuerte asociación del status socioeconómico, abuso de droga y el alcohol, la salud mental, aculturación, inmigración, comportamientos sexuales riesgosos e historia de abuso con la violencia entre parejas. Sin embargo, más estudios se deben llevar a cabo para identificar otros factores de riesgos y de protección a poblaciones hispanas no clínicas. Mientras que el conocimiento sobre la etiología de la VP entre mujeres Hispanas se expanda, enfermeras y otros profesionales de la salud deben desarrollar, implementar y evaluar estrategias culturalmente adecuadas para la prevención primaria y secundaria de la violencia entre pareja. PMID:26166938
Explosion and Final State of an Unstable Reissner-Nordström Black Hole.
Sanchis-Gual, Nicolas; Degollado, Juan Carlos; Montero, Pedro J; Font, José A; Herdeiro, Carlos
A Reissner-Nordström black hole (BH) is superradiantly unstable against spherical perturbations of a charged scalar field enclosed in a cavity, with a frequency lower than a critical value. We use numerical relativity techniques to follow the development of this unstable system-dubbed a charged BH bomb-into the nonlinear regime, solving the full Einstein-Maxwell-Klein-Gordon equations, in spherical symmetry. We show that (i) the process stops before all the charge is extracted from the BH, and (ii) the system settles down into a hairy BH: a charged horizon in equilibrium with a scalar field condensate, whose phase is oscillating at the (final) critical frequency. For a low scalar field charge q, the final state is approached smoothly and monotonically. For large q, however, the energy extraction overshoots, and an explosive phenomenon, akin to a bosenova, pushes some energy back into the BH. The charge extraction, by contrast, does not reverse.
Superradiance and black hole bomb in five-dimensional minimal ungauged supergravity
Aliev, Alikram N.
We examine the black hole bomb model which consists of a rotating black hole of five-dimenensional minimal ungauged supergravity and a reflecting mirror around it. For low-frequency scalar perturbations, we find solutions to the Klein-Gordon equation in the near-horizon and far regions of the black hole spacetime. To avoid solutions with logarithmic terms, we assume that the orbital quantum number l takes on nearly, but not exactly, integer values and perform the matching of these solutions in an intermediate region. This allows us to calculate analytically the frequency spectrum of quasinormal modes, taking the limits as l approaches even or odd integers separately. We find that all l modes of scalar perturbations undergo negative damping in the regime of superradiance, resulting in exponential growth of their amplitudes. Thus, the model under consideration would exhibit the superradiant instability, eventually behaving as a black hole bomb in five dimensions.
Covariant approach of perturbations in Lovelock type brane gravity
NASA Astrophysics Data System (ADS)
Bagatella-Flores, Norma; Campuzano, Cuauhtemoc; Cruz, Miguel; Rojas, Efraín
We develop a covariant scheme to describe the dynamics of small perturbations on Lovelock type extended objects propagating in a flat Minkowski spacetime. The higher-dimensional analogue of the Jacobi equation in this theory becomes a wave type equation for a scalar field Φ . Whithin this framework, we analyse the stability of membranes with a de Sitter geometry where we find that the Jacobi equation specializes to a Klein-Gordon (KG) equation for Φ possessing a tachyonic mass. This shows that, to some extent, these types of extended objects share the symmetries of the Dirac-Nambu-Goto (DNG) action which is by no means coincidental because the DNG model is the simplest included in this type of gravity.
Unique Continuation from Infinity in Asymptotically Anti-de Sitter Spacetimes
NASA Astrophysics Data System (ADS)
Holzegel, Gustav; Shao, Arick
We consider the unique continuation properties of asymptotically anti-de Sitter spacetimes by studying Klein-Gordon-type equations {Box_g φ + σ φ = {G} ( φ, partial φ )}, {σ in {R}}, on a large class of such spacetimes. Our main result establishes that if {φ} vanishes to sufficiently high order (depending on {σ}) on a sufficiently long time interval along the conformal boundary I, then the solution necessarily vanishes in a neighborhood of I. In particular, in the {σ}-range where Dirichlet and Neumann conditions are possible on I for the forward problem, we prove uniqueness if both these conditions are imposed. The length of the time interval can be related to the refocusing time of null geodesics on these backgrounds and is expected to be sharp. Some global applications as well as a uniqueness result for gravitational perturbations are also discussed. The proof is based on novel Carleman estimates established in this setting.
Analogue model for anti-de Sitter as a description of point sources in fluids
NASA Astrophysics Data System (ADS)
Mosna, Ricardo A.; Pitelli, João Paulo M.; Richartz, Maurício
We introduce an analogue model for a nonglobally hyperbolic spacetime in terms of a two-dimensional fluid. This is done by considering the propagation of sound waves in a radial flow with constant velocity. We show that the equation of motion satisfied by sound waves is the wave equation on AdS2×S1. Since this spacetime is not globally hyperbolic, the dynamics of the Klein-Gordon field is not well defined until boundary conditions at the spatial boundary of AdS2 are prescribed. On the analogue model end, those extra boundary conditions provide an effective description of the point source at r =0 . For waves with circular symmetry, we relate the different physical evolutions to the phase difference between ingoing and outgoing scattered waves. We also show that the fluid configuration can be stable or unstable depending on the chosen boundary condition.
Tests of quantum-gravity-induced nonlocality via optomechanical experiments
NASA Astrophysics Data System (ADS)
Belenchia, Alessio; Benincasa, Dionigi M. T.; Liberati, Stefano; Marin, Francesco; Marino, Francesco; Ortolan, Antonello
The nonrelativistic limit of nonlocal modifications to the Klein-Gordon operator is studied, and the experimental possibilities of casting stringent constraints on the nonlocality scale via planned and/or current optomechanical experiments are discussed. Details of the perturbative analysis and semianalytical simulations leading to the dynamic evolution of a quantum harmonic oscillator in the presence of nonlocality reported in [A. Belenchia, D. M. T. Benincasa, S. Liberati, F. Marin, F. Marino, and A. Ortolan, Phys. Rev. Lett. 116, 161303 (2016), 10.1103/PhysRevLett.116.161303] are given, together with a comprehensive account of the experimental methodology with particular regard to sensitivity limitations related to thermal decoherence time and active cooling of the oscillator. Finally, a strategy for detecting nonlocality scales of the order of 10-22÷10-26 m by means of the spontaneous time-periodic squeezing of quantum-coherent states is provided.
Long time stability of small-amplitude Breathers in a mixed FPU-KG model
NASA Astrophysics Data System (ADS)
Paleari, Simone; Penati, Tiziano
In the limit of small couplings in the nearest neighbor interaction, and small total energy, we apply the resonant normal form result of a previous paper of ours to a finite but arbitrarily large mixed Fermi-Pasta-Ulam Klein-Gordon chain, i.e., with both linear and nonlinear terms in both the on-site and interaction potential, with periodic boundary conditions. An existence and orbital stability result for Breathers of such a normal form, which turns out to be a generalized discrete nonlinear Schrödinger model with exponentially decaying all neighbor interactions, is first proved. Exploiting such a result as an intermediate step, a long time stability theorem for the true Breathers of the KG and FPU-KG models, in the anti-continuous limit, is proven.
Modeling Kleinian cosmology with electronic metamaterials
NASA Astrophysics Data System (ADS)
Figueiredo, David; Gomes, Felipe A.; Fumeron, Sébastien; Berche, Bertrand; Moraes, Fernando
This paper deals with the propagation of Klein-Gordon particles in flat background spacetime exhibiting discontinuous metric changes from a Lorentzian signature (-,+,+,+) to a Kleinian signature (-,+,+,-) . A formal analogy with the propagation of electrons at a junction between an anisotropic semiconductor and an electronic metamaterial is presented. From that analogy, we study the dynamics of these particles falling onto planar boundary interfaces between these two families of media and show a mirror-like behavior for the particle flux. Finally, the case of a double junction of finite thickness is examined and the possibility of tunneling through it is discussed. A physical link between the metamaterial and the Kleinian slabs is found by calculating the time of flight of the respective traversing particles.
Whitham modulation equations, coalescing characteristics, and dispersive Boussinesq dynamics
NASA Astrophysics Data System (ADS)
Ratliff, Daniel J.; Bridges, Thomas J.
Whitham modulation theory with degeneracy in wave action is considered. The case where all components of the wave action conservation law, when evaluated on a family of periodic travelling waves, have vanishing derivative with respect to wavenumber is considered. It is shown that Whitham modulation equations morph, on a slower time scale, into the two way Boussinesq equation. Both the 1 + 1 and 2 + 1 cases are considered. The resulting Boussinesq equation arises in a universal form, in that the coefficients are determined from the abstract properties of the Lagrangian and do not depend on particular equations. One curious by-product of the analysis is that the theory can be used to confirm that the two-way Boussinesq equation is not a valid model in shallow water hydrodynamics. Modulation of nonlinear travelling waves of the complex Klein-Gordon equation is used to illustrate the theory.
Superradiant Instability of D-Dimensional Reissner—Nordström Black Hole Mirror System
NASA Astrophysics Data System (ADS)
Li, Ran; Zhao, Jun-Kun; Zhang, Yan-Ming
We analytically study the superradiant instability of charged massless scalar field in the background of D-dimensional Reissner-Nordström (RN) black hole caused by mirror-like boundary condition. By using the asymptotic matching method to solve the Klein-Gordon equation that governs the dynamics of scalar field, we have derived the expressions of complex parts of boxed quasinormal frequencies, and shown they are positive in the regime of superradiance. This indicates the charged scalar field is unstable in D-dimensional Reissner-Nordström (RN) black hole surrounded by mirror. However, the numerical work to calculate the boxed quasinormal frequencies in this system is still required in the future. Supported by the National Natural Science Foundation of China under Grant No. 11205048
Existence of multisite intrinsic localized modes in one-dimensional Debye crystals
Koukouloyannis, V.; Kourakis, I.
The existence of highly localized multisite oscillatory structures (discrete multibreathers) in a nonlinear Klein-Gordon chain which is characterized by an inverse dispersion law is proven and their linear stability is investigated. The results are applied in the description of vertical (transverse, off-plane) dust grain motion in dusty plasma crystals, by taking into account the lattice discreteness and the sheath electric and/or magnetic field nonlinearity. Explicit values from experimental plasma discharge experiments are considered. The possibility for the occurrence of multibreathers associated with vertical charged dust grain motion in strongly coupled dusty plasmas (dust crystals) is thus established. From a fundamental point of view, this study aims at providing a rigorous investigation of the existence of intrinsic localized modes in Debye crystals and/or dusty plasma crystals and, in fact, suggesting those lattices as model systems for the study of fundamental crystal properties.
Discreteness of space from GUP in a weak gravitational field
NASA Astrophysics Data System (ADS)
Deb, Soumen; Das, Saurya; Vagenas, Elias C.
Quantum gravity effects modify the Heisenberg's uncertainty principle to a generalized uncertainty principle (GUP). Earlier work showed that the GUP-induced corrections to the Schrödinger equation, when applied to a non-relativistic particle in a one-dimensional box, led to the quantization of length. Similarly, corrections to the Klein-Gordon and the Dirac equations, gave rise to length, area and volume quantizations. These results suggest a fundamental granular structure of space. In this work, it is investigated how spacetime curvature and gravity might influence this discreteness of space. In particular, by adding a weak gravitational background field to the above three quantum equations, it is shown that quantization of lengths, areas and volumes continue to hold. However, it should be noted that the nature of this new quantization is quite complex and under proper limits, it reduces to cases without gravity. These results suggest that quantum gravity effects are universal.
Orbital stability of periodic waves in the class of reduced Ostrovsky equations
NASA Astrophysics Data System (ADS)
Johnson, Edward R.; Pelinovsky, Dmitry E.
Periodic travelling waves are considered in the class of reduced Ostrovsky equations that describe low-frequency internal waves in the presence of rotation. The reduced Ostrovsky equations with either quadratic or cubic nonlinearities can be transformed to integrable equations of the Klein-Gordon type by means of a change of coordinates. By using the conserved momentum and energy as well as an additional conserved quantity due to integrability, we prove that small-amplitude periodic waves are orbitally stable with respect to subharmonic perturbations, with period equal to an integer multiple of the period of the wave. The proof is based on construction of a Lyapunov functional, which is convex at the periodic wave and is conserved in the time evolution. We also show numerically that convexity of the Lyapunov functional holds for periodic waves of arbitrary amplitudes.
Explosion and Final State of an Unstable Reissner-Nordström Black Hole
NASA Astrophysics Data System (ADS)
Sanchis-Gual, Nicolas; Degollado, Juan Carlos; Montero, Pedro J.; Font, José A.; Herdeiro, Carlos
A Reissner-Nordström black hole (BH) is superradiantly unstable against spherical perturbations of a charged scalar field enclosed in a cavity, with a frequency lower than a critical value. We use numerical relativity techniques to follow the development of this unstable system—dubbed a charged BH bomb—into the nonlinear regime, solving the full Einstein-Maxwell-Klein-Gordon equations, in spherical symmetry. We show that (i) the process stops before all the charge is extracted from the BH, and (ii) the system settles down into a hairy BH: a charged horizon in equilibrium with a scalar field condensate, whose phase is oscillating at the (final) critical frequency. For a low scalar field charge q , the final state is approached smoothly and monotonically. For large q , however, the energy extraction overshoots, and an explosive phenomenon, akin to a bosenova, pushes some energy back into the BH. The charge extraction, by contrast, does not reverse.
On the spring and mass of the Dirac oscillator
NASA Technical Reports Server (NTRS)
Crawford, James P.
The Dirac oscillator is a relativistic generalization of the quantum harmonic oscillator. In particular, the square of the Hamiltonian for the Dirac oscillator yields the Klein-Gordon equation with a potential of the form: (ar(sub 2) + b(L x S)), where a and b are constants. To obtain the Dirac oscillator, a 'minimal substitution' is made in the Dirac equation, where the ordinary derivative is replaced with a covariant derivative. However, an unusual feature of the covariant derivative in this case is that the potential is a non-trivial element of the Clifford algebra. A theory which naturally gives rise to gage potentials which are non-trivial elements of the Clifford algebra is that based on local automorphism invariance. An exact solution of the automorphism gage field equations which reproduces both the potential term and the mass term of the Dirac oscillator is presented.
X-ray energies of circular transitions and electron screening in kaonic atoms
Santos, J.P.; Parente, F.; Boucard, S.; Indelicato, P.; Desclaux, J.P.
The QED contribution to the energies of the circular (n,l=n-1), 2{<=}n{<=}13, transitions have been calculated for several kaonic atoms throughout the periodic table, using the current world-average kaon mass. Calculations were done in the framework of the Klein-Gordon equation, with finite nuclear size, finite particle size, and all-order Uelhing vacuum polarization corrections, as well as Kaellen and Sabry and Wichmann and Kroll corrections. These energy level values are compared with other computed values. The circular transition energies are compared with available measured and theoretical transition energies. Electron screening is evaluated using a Dirac-Fock model for the electronic part of the wave function. The effect of electronic wave-function correlation is evaluated.
Hawking's radiation in non-stationary rotating de Sitter background
NASA Astrophysics Data System (ADS)
Ibohal, N.; Ibungochouba, T.
Hawking's radiation effect of Klein-Gordon scalar field, Dirac particles and Maxwell's electromagnetic field in the non-stationary rotating de Sitter cosmological space-time is investigated by using a method of generalized tortoise co-ordinates transformation. The locations and the temperatures of the cosmological horizons of the non-stationary rotating de Sitter model are derived. It is found that the locations and the temperatures of the rotating cosmological model depend not only on the time but also on the angle. The stress-energy regularization techniques are applied to the two dimensional analog of the de Sitter metrics and the calculated stress-energy tensor contains the thermal radiation effect.
DBI potential, DBI inflation action and general Lagrangian relative to phantom, K-essence and quintessence
Zhang, Qing; Huang, Yong-Chang
We derive a Dirac-Born-Infeld (DBI) potential and DBI inflation action by rescaling the metric. The determinant of the induced metric naturally includes the kinetic energy and the potential energy. In particular, the potential energy and kinetic energy can convert into each other in any order, which is in agreement with the limit of classical physics. This is quite different from the usual DBI action. We show that the Taylor expansion of the DBI action can be reduced into the form in the non-linear classical physics. These investigations are the support for the statement that the results of string theory are consistent with quantum mechanics and classical physics. We deduce the Phantom, K-essence, Quintessence and Generalized Klein-Gordon Equation from the DBI model.
Black hole evolution by spectral methods
NASA Astrophysics Data System (ADS)
Kidder, Lawrence E.; Scheel, Mark A.; Teukolsky, Saul A.; Carlson, Eric D.; Cook, Gregory B.
Current methods of evolving a spacetime containing one or more black holes are plagued by instabilities that prohibit long-term evolution. Some of these instabilities may be due to the numerical method used, traditionally finite differencing. In this paper, we explore the use of a pseudospectral collocation (PSC) method for the evolution of a spherically symmetric black hole spacetime in one dimension using a hyperbolic formulation of Einstein's equations. We demonstrate that our PSC method is able to evolve a spherically symmetric black hole spacetime forever without enforcing constraints, even if we add dynamics via a Klein-Gordon scalar field. We find that, in contrast with finite-differencing methods, black hole excision is a trivial operation using PSC applied to a hyperbolic formulation of Einstein's equations. We discuss the extension of this method to three spatial dimensions.
SNe Ia tests of quintessence tracker cosmology in an anisotropic background
Miranda, W.; Carneiro, S.; Pigozzo, C. E-mail: email@example.com
We investigate the observational effects of a quintessence model in an anisotropic spacetime. The anisotropic metric is a non-rotating particular case of a generalized Gödel's metric and is classified as Bianchi III. This metric is an exact solution of the Einstein-Klein-Gordon field equations with an anisotropic scalar field ψ, which is responsible for the anisotropy of the spacetime geometry. We test the model against observations of type Ia supernovae, analyzing the SDSS dataset calibrated with the MLCS2k2 fitter, and the results are compared to standard quintessence models with Ratra-Peebles potentials. We obtain a good agreement with observations, with best values for the matter and curvature density parameters Ω{sub M} = 0.29 and Ω{sub k}= 0.01 respectively. We conclude that present SNe Ia observations cannot, alone, distinguish a possible anisotropic axis in the cosmos.
Scalar field as a Bose-Einstein condensate?
Castellanos, Elías; Escamilla-Rivera, Celia; Macías, Alfredo; Núñez, Darío E-mail: email@example.com E-mail: email@example.com
We discuss the analogy between a classical scalar field with a self-interacting potential, in a curved spacetime described by a quasi-bounded state, and a trapped Bose-Einstein condensate. In this context, we compare the Klein-Gordon equation with the Gross-Pitaevskii equation. Moreover, the introduction of a curved background spacetime endows, in a natural way, an equivalence to the Gross-Pitaevskii equation with an explicit confinement potential. The curvature also induces a position dependent self-interaction parameter. We exploit this analogy by means of the Thomas-Fermi approximation, commonly used to describe the Bose-Einstein condensate, in order to analyze the quasi bound scalar field distribution surrounding a black hole.
Toward a quantum theory of tachyon fields
NASA Astrophysics Data System (ADS)
Schwartz, Charles
We construct momentum space expansions for the wave functions that solve the Klein-Gordon and Dirac equations for tachyons, recognizing that the mass shell for such fields is very different from what we are used to for ordinary (slower than light) particles. We find that we can postulate commutation or anticommutation rules for the operators that lead to physically sensible results: causality, for tachyon fields, means that there is no connection between space-time points separated by a timelike interval. Calculating the conserved charge and four-momentum for these fields allows us to interpret the number operators for particles and antiparticles in a consistent manner; and we see that helicity plays a critical role for the spinor field. Some questions about Lorentz invariance are addressed and some remain unresolved; and we show how to handle the group representation for tachyon spinors.
Lie and Noether point symmetries of a class of quasilinear systems of second-order differential equations
NASA Astrophysics Data System (ADS)
Paliathanasis, Andronikos; Tsamparlis, Michael
We study the Lie and Noether point symmetries of a class of systems of second-order differential equations with n independent and m dependent variables (n × m systems). We solve the symmetry conditions in a geometric way and determine the general form of the symmetry vector and of the Noetherian conservation laws. We prove that the point symmetries are generated by the collineations of two (pseudo)metrics, which are defined in the spaces of independent and dependent variables. We demonstrate the general results in two special cases (a) a system of m coupled Laplace equations and (b) the Klein-Gordon equation of a particle in the context of Generalized Uncertainty Principle. In the second case we determine the complete invariant group of point transformations, and we apply the Lie invariants in order to find invariant solutions of the wave function for a spin-0 particle in the two dimensional hyperbolic space.
Towards a Realistic Axion Star
Barranco, J.; Bernal, A.
In this work we estimate the radius and the mass of a self-gravitating system made of axions. The quantum axion field satisfies the Klein-Gordon equation in a curved space-time and the metric components of this space-time are solutions to the Einstein equations with a source term given by the vacuum expectation value of the energy-momentum operator constructed from the axion field. As a first step towards an axion star we consider the up to the {phi}{sup 6} term in the axion potential expansion. We found that axion stars would have masses of the order of asteroids ({approx}10{sup -10}M{center_dot}) and radius of the order {approx} few centimeters.
Supersymmetric classical cosmology
Escamilla-Rivera, Celia; Obregón, Octavio; Ureña-López, L. Arturo E-mail: firstname.lastname@example.com
In this work a supersymmetric cosmological model is analyzed in which we consider a general superfield action of a homogeneous scalar field supermultiplet interacting with the scale factor in a supersymmetric FRW model. There appear fermionic superpartners associated with both the scale factor and the scalar field, and classical equations of motion are obtained from the super-Wheeler-DeWitt equation through the usual WKB method. The resulting supersymmetric Einstein-Klein-Gordon equations contain extra radiation and stiff matter terms, and we study their solutions in flat space for different scalar field potentials. The solutions are compared to the standard case, in particular those corresponding to the exponential potential, and their implications for the dynamics of the early Universe are discussed in turn.
Discrete breathers in hexagonal dusty plasma lattices
Koukouloyannis, V.; Kourakis, I.
The occurrence of single-site or multisite localized vibrational modes, also called discrete breathers, in two-dimensional hexagonal dusty plasma lattices is investigated. The system is described by a Klein-Gordon hexagonal lattice characterized by a negative coupling parameter epsilon in account of its inverse dispersive behavior. A theoretical analysis is performed in order to establish the possibility of existence of single as well as three-site discrete breathers in such systems. The study is complemented by a numerical investigation based on experimentally provided potential forms. This investigation shows that a dusty plasma lattice can support single-site discrete breathers, while three-site in phase breathers could exist if specific conditions, about the intergrain interaction strength, would hold. On the other hand, out of phase and vortex three-site breathers cannot be supported since they are highly unstable.
Symmetries of second-order PDEs and conformal Killing vectors
NASA Astrophysics Data System (ADS)
Tsamparlis, Michael; Paliathanasis, Andronikos
We study the Lie point symmetries of a general class of partial differential equations (PDE) of second order. An equation from this class naturally defines a second-order symmetric tensor (metric). In the case the PDE is linear on the first derivatives we show that the Lie point symmetries are given by the conformal algebra of the metric modulo a constraint involving the linear part of the PDE. Important elements in this class are the Klein-Gordon equation and the Laplace equation. We apply the general results and determine the Lie point symmetries of these equations in various general classes of Riemannian spaces. Finally we study the type II hidden symmetries of the wave equation in a Riemannian space with a Lorenzian metric.
Semi-relativistic stability and critical mass of a system of spinless bosons in gravitational interaction
NASA Astrophysics Data System (ADS)
Martin, André; Roy, S. M.
The N particle hamiltonian Σi=1N(pi2+m2)1/2-Σi
Confluent Heun functions and the physics of black holes: Resonant frequencies, Hawking radiation and scattering of scalar waves
NASA Astrophysics Data System (ADS)
Vieira, H. S.; Bezerra, V. B.
We apply the confluent Heun functions to study the resonant frequencies (quasispectrum), the Hawking radiation and the scattering process of scalar waves, in a class of spacetimes, namely, the ones generated by a Kerr-Newman-Kasuya spacetime (dyon black hole) and a Reissner-Nordström black hole surrounded by a magnetic field (Ernst spacetime). In both spacetimes, the solutions for the angular and radial parts of the corresponding Klein-Gordon equations are obtained exactly, for massive and massless fields, respectively. The special cases of Kerr and Schwarzschild black holes are analyzed and the solutions obtained, as well as in the case of a Schwarzschild black hole surrounded by a magnetic field. In all these special situations, the resonant frequencies, Hawking radiation and scattering are studied.
Paramagnetic colloidal ribbons in a precessing magnetic field.
Alvarez-Nodarse, R; Quintero, N R; Mertens, F G; Casic, N; Fischer, Th M
We investigate the dynamics of a kink in a damped parametrically driven nonlinear Klein-Gordon equation. We show by using a method of averaging that, in the high-frequency limit, the kink moves in an effective potential and is driven by an effective constant force. We demonstrate that the shape of the solitary wave can be controlled via the frequency and the eccentricity of the modulation. This is in accordance with the experimental results reported in a recent paper [Casic et al., Phys. Rev. Lett. 110, 168302 (2013)], where the dynamic self-assembly and propulsion of a ribbon formed from paramagnetic colloids in a time-dependent magnetic field has been studied.
Classical and quantum dynamics of a charged scalar particle in a background of two counterpropagating plane waves
NASA Astrophysics Data System (ADS)
King, B.; Hu, H.
We consider a scalar particle in a background formed by two counterpropagating plane waves. Two cases are studied: (i) dynamics at a magnetic node and (ii) zero initial transverse canonical momentum. The Lorentz and Klein-Gordon equations are solved for these cases and approximations analyzed. For the magnetic-node solution (homogeneous, time-dependent electric field), the modified Volkov wave function which arises from a high-energy approximation is found to be inaccurate for all energies and the solution itself unstable when the photon emission (nonlinear Compton scattering) is included. For the zero initial transverse canonical momentum case, in both quantum and classical cases, forbidden parameter regimes, absent in the plane-wave model, are identified.
Separation of noncommutative differential calculus on quantum Minkowski space
Bachmaier, Fabian; Blohmann, Christian
Noncommutative differential calculus on quantum Minkowski space is not separated with respect to the standard generators, in the sense that partial derivatives of functions of a single generator can depend on all other generators. It is shown that this problem can be overcome by a separation of variables. We study the action of the universal L-matrix, appearing in the coproduct of partial derivatives, on generators. Powers of the resulting quantum Minkowski algebra valued matrices are calculated. This leads to a nonlinear coordinate transformation which essentially separates the calculus. A compact formula for general derivatives is obtained in form of a chain rule with partial Jackson derivatives. It is applied to the massive quantum Klein-Gordon equation by reducing it to an ordinary q-difference equation. The rest state solution can be expressed in terms of a product of q-exponential functions in the separated variables.
Field theory on R× S 3 topology. IV: Electrodynamics of magnetic moments
NASA Astrophysics Data System (ADS)
Carmeli, M.; Malin, S.
The equations of electrodynamics for the interactions between magnetic moments are written on R×S3 topology rather than on Minkowskian space-time manifold of ordinary Maxwell's equations. The new field equations are an extension of the previously obtained Klein-Gordon-type, Schrödinger-type, Weyl-type, and Dirac-type equations. The concept of the magnetic moment in our case takes over that of the charge in ordinary electrodynamics as the fundamental entity. The new equations have R×S3 invariance as compared to the Lorentz invariance of Maxwell's equations. The solutions of the new field equations are given. In this theory the divergence of the electric field vanishes whereas that of the magnetic field does not.
Charged massive scalar field configurations supported by a spherically symmetric charged reflecting shell
NASA Astrophysics Data System (ADS)
Hod, Shahar
The physical properties of bound-state charged massive scalar field configurations linearly coupled to a spherically symmetric charged reflecting shell are studied analytically. To that end, we solve the Klein-Gordon wave equation for a static scalar field of proper mass μ, charge coupling constant q, and spherical harmonic index l in the background of a charged shell of radius R and electric charge Q. It is proved that the dimensionless inequality μR <√{(qQ) 2 -(l + 1 / 2) 2 } provides an upper bound on the regime of existence of the composed charged-spherical-shell-charged-massive-scalar-field configurations. Interestingly, we explicitly show that the discrete spectrum of shell radii {Rn(μ,qQ,l)}n = 0 n = ∞ which can support the static bound-state charged massive scalar field configurations can be determined analytically. We confirm our analytical results by numerical computations.
Scalar boundary conditions in Lifshitz spacetimes
NASA Astrophysics Data System (ADS)
Keeler, Cynthia
We investigate the conditions imposable on a scalar field at the boundary of the so-called Lifshitz spacetime which has been proposed as the dual to Lifshitz field theories. For effective mass squared between -( d + z - 1)2 /4 and z 2 - ( d + z - 1)2 /4, we find a one-parameter choice of boundary condition type. The bottom end of this range corresponds to a Breitenlohner-Freedman bound; below it, the Klein-Gordon operator need not be positive, so we cannot make sense of the dynamics. Above the top end of the range, only one boundary condition type is available; here we expect compact initial data will remain compact in the future.
The Spacetime Between Einstein and Kaluza-Klein: Further Explorations
NASA Astrophysics Data System (ADS)
Vuille, Chris
Tensor multinomials can be used to create a generalization of Einstein's general relativity that in a mathematical sense falls between Einstein's original theory in four dimensions and the Kaluza-Klein theory in five dimensions. In the extended theory there are only four physical dimensions, but the tensor multinomials are expanded operators that can accommodate other forces of nature. The equivalent Ricci tensor of this geometry yields vacuum general relativity and electromagnetism, as well as a Klein-Gordon-like quantum scalar field. With a generalization of the stress-energy tensor, an exact solution for a plane-symmetric dust can be found where the scalar portion of the field drives early universe inflation, levels off for a period, then causes a later continued universal acceleration, a possible geometric mechanism for the inflaton or dark energy. Some new explorations of the equations, the problems, and possibilities will be presented and discussed.
The Clifford algebra of physical space and Dirac theory
NASA Astrophysics Data System (ADS)
Vaz, Jayme, Jr.
The claim found in many textbooks that the Dirac equation cannot be written solely in terms of Pauli matrices is shown to not be completely true. It is only true as long as the term β \\psi in the usual Dirac factorization of the Klein-Gordon equation is assumed to be the product of a square matrix β and a column matrix ψ. In this paper we show that there is another possibility besides this matrix product, in fact a possibility involving a matrix operation, and show that it leads to another possible expression for the Dirac equation. We show that, behind this other possible factorization is the formalism of the Clifford algebra of physical space. We exploit this fact, and discuss several different aspects of Dirac theory using this formalism. In particular, we show that there are four different possible sets of definitions for the parity, time reversal, and charge conjugation operations for the Dirac equation.
Fast route to nonlinear clustering statistics in modified gravity theories
NASA Astrophysics Data System (ADS)
Winther, Hans A.; Ferreira, Pedro G.
We propose a simple and computationally fast method for performing N -body simulations for a large class of modified gravity theories with a screening mechanism such as chameleons, symmetrons, and Galileons. By combining the linear Klein-Gordon equation with a screening factor, calculated from analytical solutions of spherical symmetric configurations, we obtain a modified field equation of which the solution is exact in the linear regime while at the same time taking screening into account on nonlinear scales. The resulting modified field equation remains linear and can be solved just as quickly as the Poisson equation without any of the convergence problems that can arise when solving the full equation. We test our method with N -body simulations and find that it compares remarkably well with full simulations well into the nonlinear regime.
Relativistic x-ray free-electron lasers in the quantum regime.
Eliasson, Bengt; Shukla, P K
We present a nonlinear theory for relativistic x-ray free-electron lasers in the quantum regime, using a collective Klein-Gordon (KG) equation (for relativistic electrons), which is coupled with the Maxwell-Poisson equations for the electromagnetic and electrostatic fields. In our model, an intense electromagnetic wave is used as a wiggler which interacts with a relativistic electron beam to produce coherent tunable radiation. The KG-Maxwell-Poisson model is used to derive a general nonlinear dispersion relation for parametric instabilities in three space dimensions, including an arbitrarily large amplitude electromagnetic wiggler field. The nonlinear dispersion relation reveals the importance of quantum recoil effects and oblique scattering of the radiation that can be tuned by varying the beam energy.
A transport theory of relativistic nucleon-nucleon collisions with confinement
NASA Astrophysics Data System (ADS)
Vetter, T.; Biró, T. S.; Mosel, U.
A transport theory is developed on the quark level to describe nucleon-nucleon collisions. We treat the strong interaction effectively by the Friedberg-Lee model both in its original and in its modified confining version. First we study the stability of the static three-dimensional semiclassical configuration, then we present results of the time evolution given by a Vlasov equation for the quarks coupled to a Klein-Gordon equation for the mean field. We find at higher energies that the nucleons are almost transparent, whereas at lower energies we observe a substantial interaction. At very low energies we see a fusion of our bags, which is due to the purely attractive nature of the mean field and hence is an artifact of our model. We test the confinement mechanism and find that at higher energies the nucleons are restored shortly after the collision.
Quantum singularities in the BTZ spacetime
Pitelli, Joao Paulo M.; Letelier, Patricio S.
The spinless Banados-Teiltelboim-Zanelli spacetime is considered in the quantum theory context. Specifically, we study the case of a negative mass parameter using quantum test particles obeying the Klein-Gordon and Dirac equations. We study if this classical singular spacetime, with a naked singularity at the origin, remains singular when tested with quantum particles. The need for additional information near the origin is confirmed for massive scalar particles and all of the possible boundary conditions necessary to turn the spatial portion of the wave operator self-adjoint are found. When tested by massless scalar particles or fermions, the singularity is ''healed'' and no extra boundary condition is needed. Near infinity, no boundary conditions are necessary.
Are Einstein's Laws of Relativity a Quantum Effect?
NASA Astrophysics Data System (ADS)
Brändas, Erkki J.
The problem of unifying quantum mechanics with special and general relativity is reconsidered from a relativistically invariant first principles theory. The ingredients are: (i) analytic extension of quantum mechanics into the complex plane via a complex symmetric ansatz, involving (ii) particle- antiparticle states interacting through a kinematical law including (iii) dynamical features such as time- and length-scale contractions and examining (iv) the likelihood of the so-called general Jordan block formations. The extended formulation has a wider set of solutions compared to standard mechanics, with general gauge invariance appropriately embedded. In the present development we establish connections with the Klein-Gordon-Dirac relativistic theories and confirm dynamical features like space and time contractions, Einstein's law of light deflection in a gravitational field, and the appearance of the Schwarzschild-gravitational radius associated with every mass-matter object.
Dirac-Type Equations in a Gravitational Field, with Vector Wave Function
NASA Astrophysics Data System (ADS)
Arminjon, Mayeul
An analysis of the classical-quantum correspondence shows that it needs to identify a preferred class of coordinate systems, which defines a torsionless connection. One such class is that of the locally-geodesic systems, corresponding to the Levi-Civita connection. Another class, thus another connection, emerges if a preferred reference frame is available. From the classical Hamiltonian that rules geodesic motion, the correspondence yields two distinct Klein-Gordon equations and two distinct Dirac-type equations in a general metric, depending on the connection used. Each of these two equations is generally-covariant, transforms the wave function as a four-vector, and differs from the Fock-Weyl gravitational Dirac equation (DFW equation). One obeys the equivalence principle in an often-accepted sense, whereas the DFW equation obeys that principle only in an extended sense.
Principles of Discrete Time Mechanics
NASA Astrophysics Data System (ADS)
Jaroszkiewicz, George
1. Introduction; 2. The physics of discreteness; 3. The road to calculus; 4. Temporal discretization; 5. Discrete time dynamics architecture; 6. Some models; 7. Classical cellular automata; 8. The action sum; 9. Worked examples; 10. Lee's approach to discrete time mechanics; 11. Elliptic billiards; 12. The construction of system functions; 13. The classical discrete time oscillator; 14. Type 2 temporal discretization; 15. Intermission; 16. Discrete time quantum mechanics; 17. The quantized discrete time oscillator; 18. Path integrals; 19. Quantum encoding; 20. Discrete time classical field equations; 21. The discrete time Schrodinger equation; 22. The discrete time Klein-Gordon equation; 23. The discrete time Dirac equation; 24. Discrete time Maxwell's equations; 25. The discrete time Skyrme model; 26. Discrete time quantum field theory; 27. Interacting discrete time scalar fields; 28. Space, time and gravitation; 29. Causality and observation; 30. Concluding remarks; Appendix A. Coherent states; Appendix B. The time-dependent oscillator; Appendix C. Quaternions; Appendix D. Quantum registers; References; Index.
Pair creation rates for one-dimensional fermionic and bosonic vacua
NASA Astrophysics Data System (ADS)
Ware, Matthew; Su, Q.; Grobe, R.
We compare the creation rates for particle-antiparticle pairs produced by a supercritical force field for fermionic and bosonic model systems. The rates obtained from the Dirac and Klein-Gordon equations can be computed directly from the quantum mechanical transmission coefficients describing the scattering of an incoming particle with the supercritical potential barrier. We provide a unified framework that shows that the bosonic rates can exceed the fermionic ones, as one could expect from the Pauli exclusion principle for the fermion system. The predicted pair-creation rates also match the slopes of the time-dependent particle probabilities obtained from large-scale ab initio numerical simulations based on quantum field theory. This work has been supported by the NSF and Research Corporation.
Charged particle in higher dimensional weakly charged rotating black hole spacetime
Frolov, Valeri P.; Krtous, Pavel
We study charged particle motion in weakly charged higher dimensional black holes. To describe the electromagnetic field we use a test field approximation and the higher dimensional Kerr-NUT-(A)dS metric as a background geometry. It is shown that for a special configuration of the electromagnetic field, the equations of motion of charged particles are completely integrable. The vector potential of such a field is proportional to one of the Killing vectors (called a primary Killing vector) from the 'Killing tower' of symmetry generating objects which exists in the background geometry. A free constant in the definition of the adopted electromagnetic potential is proportional to the electric charge of the higher dimensional black hole. The full set of independent conserved quantities in involution is found. We demonstrate that Hamilton-Jacobi equations are separable, as is the corresponding Klein-Gordon equation and its symmetry operators.
Separability of the massive Dirac equation in 5-dimensional Myers-Perry black hole geometry and its relation to a rank-three Killing-Yano tensor
Wu Shuangqing
The Dirac equation for the electron around a five-dimensional rotating black hole with two different angular momenta is separated into purely radial and purely angular equations. The general solution is expressed as a superposition of solutions derived from these two decoupled ordinary differential equations. By separating variables for the massive Klein-Gordon equation in the same spacetime background, I derive a simple and elegant form for the Staeckel-Killing tensor, which can be easily written as the square of a rank-three Killing-Yano tensor. I have also explicitly constructed a symmetry operator that commutes with the scalar Laplacian by using the Staeckel-Killing tensor, and the one with the Dirac operator by the Killing-Yano tensor admitted by the five-dimensional Myers-Perry metric, respectively.
Large Quantum Gravity Effects: Unforeseen Limitations of the Classical Theory
NASA Astrophysics Data System (ADS)
Ashtekar, Abhay
Three-dimensional gravity coupled to Maxwell (or Klein-Gordon) fields is exactly soluble under the assumption of axisymmetry. The solution is used to probe several quantum gravity issues. In particular, it is found that if there is an electromagnetic wave of Planckian frequency even with such low amplitude that the curvature of the classical solution is small, the uncertainty in the quantum metric can be very large. More generally, the quantum fluctuations in the geometry are large unless the number and frequency of photons satisfy the inequality N\\(ħGω\\)2<<1. Results hold also for a sector of the four-dimensional theory (consisting of Einstein-Rosen gravitational waves).
Path integral for the relativistic particle in curved space
NASA Astrophysics Data System (ADS)
Ferraro, Rafael
The propagator for a single relativistic particle in a (D+1)-dimensional curved background is obtained by evaluating the canonical path integral in the true 2D-dimensional phase space. Since only paths moving forward in time are integrated, the resulting propagator depends on how the time is chosen; i.e., it depends on the reference system. In order for the propagator to satisfy the properties of a unitary theory, the time must be attached to a Killing vector. Although the measure is unique (it is the Liouville measure), the skeletonization of the phase-space functional action is ambiguous. One such ambiguity is exploited to obtain different propagators obeying the Klein-Gordon equation with different couplings to quantities related to the shape of the reference system (spatial curvature, etc.).
Collisional interactions between self-interacting nonrelativistic boson stars: Effective potential analysis and numerical simulations
NASA Astrophysics Data System (ADS)
Cotner, Eric
Scalar particles are a common prediction of many beyond the Standard Model theories. If they are light and cold enough, there is a possibility they may form Bose-Einstein condensates, which will then become gravitationally bound. These boson stars are solitonic solutions to the Einstein-Klein-Gordon equations but may be approximated in the nonrelativistic regime with a coupled Schrödinger-Poisson system. General properties of single soliton states are derived, including the possibility of quartic self-interactions. Binary collisions between two solitons are then studied, and the effects of different mass ratios, relative phases, self-couplings, and separation distances are characterized, leading to an easy conceptual understanding of how these parameters affect the collision outcome in terms of conservation of energy. Applications to dark matter are discussed.
Lagrange interpolation and modified cubic B-spline differential quadrature methods for solving hyperbolic partial differential equations with Dirichlet and Neumann boundary conditions
NASA Astrophysics Data System (ADS)
Jiwari, Ram
In this article, the author proposed two differential quadrature methods to find the approximate solution of one and two dimensional hyperbolic partial differential equations with Dirichlet and Neumann's boundary conditions. The methods are based on Lagrange interpolation and modified cubic B-splines respectively. The proposed methods reduced the hyperbolic problem into a system of second order ordinary differential equations in time variable. Then, the obtained system is changed into a system of first order ordinary differential equations and finally, SSP-RK3 scheme is used to solve the obtained system. The well known hyperbolic equations such as telegraph, Klein-Gordon, sine-Gordon, Dissipative non-linear wave, and Vander Pol type non-linear wave equations are solved to check the accuracy and efficiency of the proposed methods. The numerical results are shown in L∞ , RMS andL2 errors form.
Classical electromagnetic fields from quantum sources in heavy-ion collisions
NASA Astrophysics Data System (ADS)
Holliday, Robert; McCarty, Ryan; Peroutka, Balthazar; Tuchin, Kirill
Electromagnetic fields are generated in high energy nuclear collisions by spectator valence protons. These fields are traditionally computed by integrating the Maxwell equations with point sources. One might expect that such an approach is valid at distances much larger than the proton size and thus such a classical approach should work well for almost the entire interaction region in the case of heavy nuclei. We argue that, in fact, the contrary is true: due to the quantum diffusion of the proton wave function, the classical approximation breaks down at distances of the order of the system size. We compute the electromagnetic field created by a charged particle described initially as a Gaussian wave packet of width 1 fm and evolving in vacuum according to the Klein-Gordon equation. We completely neglect the medium effects. We show that the dynamics, magnitude and even sign of the electromagnetic field created by classical and quantum sources are different.
Complex statistics and diffusion in nonlinear disordered particle chains
Antonopoulos, Ch. G.; Bountis, T.; Skokos, Ch.; Drossos, L.
We investigate dynamically and statistically diffusive motion in a Klein-Gordon particle chain in the presence of disorder. In particular, we examine a low energy (subdiffusive) and a higher energy (self-trapping) case and verify that subdiffusive spreading is always observed. We then carry out a statistical analysis of the motion, in both cases, in the sense of the Central Limit Theorem and present evidence of different chaos behaviors, for various groups of particles. Integrating the equations of motion for times as long as 10{sup 9}, our probability distribution functions always tend to Gaussians and show that the dynamics does not relax onto a quasi-periodic Kolmogorov-Arnold-Moser torus and that diffusion continues to spread chaotically for arbitrarily long times.
Are black holes a serious threat to scalar field dark matter models?
Barranco, Juan; Degollado, Juan Carlos; Bernal, Argelia; Diez-Tejedor, Alberto; Megevand, Miguel; Alcubierre, Miguel; Nunez, Dario; Sarbach, Olivier
Classical scalar fields have been proposed as possible candidates for the dark matter component of the universe. Given the fact that supermassive black holes seem to exist at the center of most galaxies, in order to be a viable candidate for the dark matter halo a scalar field configuration should be stable in the presence of a central black hole, or at least be able to survive for cosmological time scales. In the present work we consider a scalar field as a test field on a Schwarzschild background, and study under which conditions one can obtain long-lived configurations. We present a detailed study of the Klein-Gordon equation in the Schwarzschild space-time, both from an analytical and numerical point of view, and show that indeed there exist quasistationary solutions that can remain surrounding a black hole for large time scales.
Differential realization of pseudo-Hermiticity: A quantum mechanical analog of Einstein's field equation
NASA Astrophysics Data System (ADS)
Mostafazadeh, Ali
For a given pseudo-Hermitian Hamiltonian of the standard form: H =p2/2m+v (x), we reduce the problem of finding the most general (pseudo-)metric operator η satisfying H†=ηHη-1 to the solution of a differential equation. If the configuration space is R, this is a Klein-Gordon equation with a nonconstant mass term. We obtain a general series solution of this equation that involves a pair of arbitrary functions. These characterize the arbitrariness in the choice of η. We apply our general results to calculate η for the PT-symmetric square well, an imaginary scattering potential, and a class of imaginary delta-function potentials. For the first two systems, our method reproduces the known results in a straightforward and extremely efficient manner. For all these systems we obtain the most general η up to second-order terms in the coupling constants.
Conservation of ParaHox genes' function in patterning of the digestive tract of the marine gastropod Gibbula varia
Background Presence of all three ParaHox genes has been described in deuterostomes and lophotrochozoans, but to date one of these three genes, Xlox has not been reported from any ecdysozoan taxa and both Xlox and Gsx are absent in nematodes. There is evidence that the ParaHox genes were ancestrally a single chromosomal cluster. Colinear expression of the ParaHox genes in anterior, middle, and posterior tissues of several species studied so far suggest that these genes may be responsible for axial patterning of the digestive tract. So far, there are no data on expression of these genes in molluscs. Results We isolated the complete coding sequences of the three Gibbula varia ParaHox genes, and then tested their expression in larval and postlarval development. In Gibbula varia, the ParaHox genes participate in patterning of the digestive tract and are expressed in some cells of the neuroectoderm. The expression of these genes coincides with the gradual formation of the gut in the larva. Gva-Gsx patterns potential neural precursors of cerebral ganglia as well as of the apical sensory organ. During larval development this gene is involved in the formation of the mouth and during postlarval development it is expressed in the precursor cells involved in secretion of the radula, the odontoblasts. Gva-Xolx and Gva-Cdx are involved in gut patterning in the middle and posterior parts of digestive tract, respectively. Both genes are expressed in some ventral neuroectodermal cells; however the expression of Gva-Cdx fades in later larval stages while the expression of Gva-Xolx in these cells persists. Conclusions In Gibbula varia the ParaHox genes are expressed during anterior-posterior patterning of the digestive system. This colinearity is not easy to spot during early larval stages because the differentiated endothelial cells within the yolk permanently migrate to their destinations in the gut. After torsion, Gsx patterns the mouth and foregut, Xlox the midgut gland or
PFI-ZEKE (Pulsed Field Ionization-Zero Electron Kinetic Energy) para el estudio de iones
NASA Astrophysics Data System (ADS)
Castaño, F.; Fernández, J. A.; Basterretxea, A. Longarte. F.; Sánchez Rayo, M. N.; Martínez, R.
Entre las áreas hacia donde ha evolucionado la Química en los últimos años están los estudios de sistemas con especies reactivas de alta energía y los dominados por fuerzas intermoleculares débiles, con energías de unas pocas kcal/mol. En efecto, el estudio de las propiedades de los iones, comenzando por su relación con la molécula neutra de la que procede, la energía de ionización, los estados vibracionales y rotacionales, energías de enlace de Van der Waals entre el ión y una amplia variedad de otras moléculas, sus confórmeros o isómeros y sus reacciones o semi-reacciones químicas están en la raíz de la necesidad de la espectroscopía conocida como PFI-ZEKE, Pulsed Field Ionization-Zero Electron Kinetic Energy. Entre las aplicaciones que requieren estos conocimientos se encuentran la generación de plasmas para la fabricación de semiconductores, memorias magnéticas, etc, así como los sistemas astrofísicos, la ionosfera terrestre, etc. La espectroscopía ZEKE es una evolución de las de fluorescencia inducida por láser, LIF, ionización multifotónica acrecentada por resonancia, REMPI, con uno y dos colores y acoplada a un sistema de tiempo de vuelo, REMPI-TOF-MS, y las espectroscopías de doble resonancia IR-UV y UV-UV. Sus espectros y la ayuda de cálculos ab inicio permite determinar las energías de enlace de complejos de van der Waals en estados fundamental y excitados, identificar confórmeros e isómeros, obtener energías de ionización experimentales aproximadas (100 cm-1) y otras variables de interés. Al igual que con LIF, REMPI y dobles resonancias, es posible utilizar muestras gaseosas, pero los espectros están muy saturados de bandas y su interpretación es difícil o imposible. Se evitan estas dificultades estudiando las moléculas o complejos en expansiones supersónicas, donde la T de los grados de libertad solo alcanzan unos pocos K. Para realizar experimentos de ZEKE hay que utilizar una propiedad recientemente
La EPA propone normas más rigurosas para las personas que aplican los plaguicidas de más alto riesgo
La EPA emitió una propuesta para la revisión de la norma para la Certificación de Aplicadores de Plaguicidas. La norma ayudará a mantener nuestras comunidades seguras, salvaguardar el medio ambiente y reducir el riesgo a los que aplican los plaguicidas.
Intensity-Modulated Radiation Therapy for the Treatment of Squamous Cell Anal Cancer With Para-aortic Nodal Involvement
Hodges, Joseph C.; Das, Prajnan; Eng, Cathy; Reish, Andrew G.; Beddar, A. Sam; Delclos, Marc E.; Krishnan, Sunil; Crane, Christopher H.
Purpose: To determine the rates of toxicity, locoregional control, distant control, and survival in anal cancer patients with para-aortic nodal involvement, treated with intensity-modulated radiotherapy (IMRT) and concurrent chemotherapy at a single institution. Methods and Materials: Between 2001 and 2007, 6 patients with squamous cell anal cancer and para-aortic nodal involvement were treated with IMRT and concurrent infusional 5-fluorouracil and cisplatin. The primary tumor was treated with a median dose of 57.5 Gy (range, 54-60 Gy), involved para-aortic, pelvic, and inguinal lymph nodes were treated with a median dose of 55 Gy (range, 50.5-55 Gy), and noninvolved nodal regions were treated with a median dose of 45 Gy (range, 43.5-45 Gy). Results: After a median follow-up of 25 months, none of the patients had a recurrence at the primary tumor, pelvic/inguinal nodes, or para-aortic nodes, whereas 2 patients developed distant metastases to the liver. Four of the 6 patients are alive. The 3-year actuarial locoregional control, distant control, and overall survival rates were 100%, 56%, and 63%, respectively. Four of the 6 patients developed Grade 3 acute gastrointestinal toxicity during chemoradiation. Conclusions: Intensity-modulated radiotherapy and concurrent chemotherapy could potentially serve as definitive therapy in anal cancer patients with para-aortic nodal involvement. Adjuvant chemotherapy may be indicated in these patients, as demonstrated by the distant failure rates. These patients need to be followed carefully because of the potential for treatment-related toxicities.
Agrobacterium tumefaciens pTAR parA promoter region involved in autoregulation, incompatibility and plasmid partitioning.
Gallie, D R; Kado, C I
The locus responsible for directing proper plasmid partitioning of Agrobacterium tumefaciens pTAR is contained within a 1259 base-pair region. Insertions or deletions within this locus can result in the loss of the plasmid's ability to partition properly. One protein product (parA), approximately 25,000 Mr, is expressed from the par locus in Escherichia coli and A. tumefaciens protein analysis systems in vitro. DNA sequence analysis of the locus revealed a single 23,500 Mr open reading frame, confirming the protein data. A 248 base-pair region immediately upstream from the 23,500 Mr open reading frame, containing an array of 12 seven-base-pair palindromic repeats each of which are separated by exactly ten base-pairs of A + T-rich (75%) sequence, not only serves to provide the promoter but is also involved in parA autoregulation. In addition, this region containing a set of 12 seven-base-pair palindromic repeats, is responsible for plasmid-associated incompatibility within Inc Ag-1 and also functions as the cis-acting recognition site at which parA interacts to bring about partitioning. Transcriptional analysis indicated that only the DNA strand responsible for parA is actively transcribed, and that active transcription of the opposite strand of par can inhibit the production of parA, resulting in plasmid destabilization. The presence of the par locus in a plasmid results in stable inheritance within a wide range of members of Rhizobiaceae. Segregation rates of par-defective derivatives can be influenced by the host.
Monoamine transporter and receptor interaction profiles of novel psychoactive substances: para-halogenated amphetamines and pyrovalerone cathinones.
Rickli, Anna; Hoener, Marius C; Liechti, Matthias E
The pharmacology of novel psychoactive substances is mostly unknown. We evaluated the transporter and receptor interaction profiles of a series of para-(4)-substituted amphetamines and pyrovalerone cathinones. We tested the potency of these compounds to inhibit the norepinephrine (NE), dopamine (DA), and serotonin (5-HT) transporters (NET, DAT, and SERT, respectively) using human embryonic kidney 293 cells that express the respective human transporters. We also tested the substance-induced efflux of NE, DA, and 5-HT from monoamine-loaded cells, binding affinities to monoamine receptors, and 5-HT2B receptor activation. Para-(4)-substituted amphetamines, including 4-methylmethcathinone (mephedrone), 4-ethylmethcathinone, 4-fluoroamphetamine, 4-fluoromethamphetamine, 4-fluoromethcatinone (flephedrone), and 4-bromomethcathinone, were relatively more serotonergic (lower DAT:SERT ratio) compared with their analogs amphetamine, methamphetamine, and methcathinone. The 4-methyl, 4-ethyl, and 4-bromo groups resulted in enhanced serotonergic properties compared with the 4-fluoro group. The para-substituted amphetamines released NE and DA. 4-Fluoramphetamine, 4-flouromethamphetamine, 4-methylmethcathinone, and 4-ethylmethcathinone also released 5-HT similarly to 3,4-methylenedioxymethamphetamine. The pyrovalerone cathinones 3,4-methylenedioxypyrovalerone, pyrovalerone, α-pyrrolidinovalerophenone, 3,4-methylenedioxy-α-pyrrolidinopropiophenone, and 3,4-methylenedioxy-α-pyrrolidinobutiophenone potently inhibited the NET and DAT but not the SERT. Naphyrone was the only pyrovalerone that also inhibited the SERT. The pyrovalerone cathinones did not release monoamines. Most of the para-substituted amphetamines exhibited affinity for the 5-HT2A receptor but no relevant activation of the 5-HT2B receptor. All the cathinones exhibited reduced trace amine-associated receptor 1 binding compared with the non-β-keto-amphetamines. In conclusion, para-substituted amphetamines exhibited
ParaCalc®--a novel tool to evaluate the economic importance of worm infections on the dairy farm.
Charlier, Johannes; Van der Voort, Mariska; Hogeveen, Henk; Vercruysse, Jozef
Subclinical infections with gastrointestinal nematodes and liver fluke are important causes of production losses in grazing cattle. Although there is an extensive compilation of literature describing the effect of these infections on animal performance, only a few attempts have been made to convert these production losses to an economic cost. Here, we propose a novel tool (ParaCalc(®)), available as a web-application, to provide herd-specific estimates of the costs of these infections on dairy farms. ParaCalc(®) is a deterministic spread-sheet model where results from diagnostic methods to monitor the helminth infection status on a herd and anthelmintic usage are used as input parameters. Default values are provided to describe the effects of the infections on production and the cost of these production losses, but the latter can be adapted to improve the herd-specificity of the cost estimate. After development, ParaCalc(®) was applied on input parameters that were available for 93 Belgian dairy herds. In addition, the tool was provided to 6 veterinarians and their user experiences were evaluated. The estimated median [25th-75th percentile] cost per year per cow was € 46 [29-58] and € 6 [0-19] for gastrointestinal nematode and liver fluke infection, respectively. For both infections, the major components in the total costs were those associated with milk production losses in the adult cows. The veterinarians evaluated ParaCalc(®) as a useful tool to raise the farmers' awareness on the costs of worm infections, providing added value for their services. However, the score given for user-friendliness was diverse among users. Although the model behind ParaCalc(®) is a strong simplification of the real herd processes inducing economic losses, the tool may be used in the future to support economic decisions on helminth control.
An NMR study of cobalt-catalyzed hydroformylation using para-hydrogen induced polarisation.
Godard, Cyril; Duckett, Simon B; Polas, Stacey; Tooze, Robert; Whitwood, Adrian C
The syntheses of Co(eta3-C3H5)(CO)2PR2R' (R, R' = Ph, Me; R, R' = Me, Ph; R = R' = Ph, Cy, CH2Ph) and Co(eta3-C3H5)(CO)(L) (L = dmpe and dppe) are described, and X-ray structures for Co(eta3-C3H5)(CO)(dppe) and the PPh2Me, PCy3 derivatives reported. The relative ability of Co(eta3-C3H5)(CO)2(PR2R') to exchange phosphine for CO follows the trend PMe2Ph < PPh2Me < PCy3 < P(CH2Ph)3 < PPh3. Reactions of the allyl complexes with para-hydrogen (p-H2) lead to the observation of para-hydrogen induced polarisation (PHIP) in both liberated propene and propane. Reaction of these complexes with both CO and H2 leads to the detection of linear acyl containing species Co(COCH2CH2CH3)(CO)3(PR2R') and branched acyl complexes Co(COCH(CH3)2)(CO)3(PR2R') via the PHIP effect. In the case of PPh2Me, additional signals for Co(COCH2CH2CH3)(CO)2(PPh2Me)(propene) and Co(COCH(CH3)2)(CO)2(PPh2Me)(propene) are also detected. When the reactions of H2 and diphenylacetylene are studied with the same precursor, Co(CO)3(PPh2Me)(CHPhCH2Ph) is seen. Studies on how the appearance and ratio, of the PHIP enhanced signals vary as a function of reaction temperature and H2 : CO ratio are reported. These profiles are used to learn about the mechanism of catalysis and reveal how the rates of key steps leading to linear and branched hydroformylation products vary with the phosphine. These data also reveal that the PMe2Ph and PPh2Me based systems yield the highest selectivity for linear hydroformylation products.
Desarrollo curricular, conciencia ambiental y tecnologia para estudiantes de intermedia: Una investigacion en accion
NASA Astrophysics Data System (ADS)
Rodriguez Ramos, Teresita
Se llevó a cabo una investigación en acción con los propósitos de 1) documentar las relaciones de las tecnologías de la información y la comunicación en las clases de ciencias de escuela intermedia como elemento de apoyo cuando se aborda el tema ambiental y sus conceptos pertinentes, a partir de las observaciones de la investigadora, así como las entrevistas y diarios reflexivos de los estudiantes de una escuela intermedia en la zona metropolitana, y luego 2) diseñar una unidad instruccional sobre el tema ambiental que integre actividades tecnologías para el curso de ciencias de la escuela intermedia según el modelo PROCIC y las observaciones que hayan iniciado los estudiantes participantes. Finalmente, se plantearon las implicaciones educativas para el currículo del Programa de Ciencias al instrumentar este modelo de unidad mediante PROCIC, e integrado la tecnología y el tema ambiental. Los hallazgos se analizaron y se categorizaron de acuerdo con las preguntas de investigación. El hallazgo principal de la investigación aborda las cuatro relaciones centrales en las que se articula la utilización de las tecnologías y sus aplicaciones en la clase de ciencias. Estas cuatro relaciones que recogen la posición de los estudiantes son: 1) Perspectiva de los estudiantes hacia la tecnología. 2) Participación de los estudiantes en los aspectos docentes. 3) Aprendizaje estudiantil sobre el ambiente, y 4) Conciencia ambiental en relación con la vida diaria. Estas relaciones ponen de manifiesto,cómo se plantea en las implicaciones, la necesidad de más investigación en acción en la sala de clases, la importancia—como tema transversal—de la conciencia ambiental mediante la tecnología al construir conocimientos significativos dentro y fuera de la escuela, asó como, valorar la investigación y la dialogicidad en la sala de clases como actividades que obligan al reexamen de la práctica didáctica en su formas curriculares de objetivos, recursos
Cosmoeducação: uma proposta para o ensino de astronomia
NASA Astrophysics Data System (ADS)
Medeiros, L. A. L.; Jafelice, L. C.
Entende-se por cosmoeducação o desenvolvimento vivencial da unidade homem-cosmo. Este conceito é norteado pela psicologia transpessoal, que estuda o ser humano em sua totalidade, onde suas relações ecológicas e cósmicas são de grande importância. Constata-se uma necessidade latente no ser humano moderno em resgatar uma relação holística com o Universo. Neste trabalho exploramos meios de cultivar a consciência de que o ser humano constitui parte integrante do cosmo e se relaciona com este com o objetivo de promover em si uma percepção ambiental mais ampla. Nossa hipótese de trabalho inicial foi que o ensino de conteúdos básicos em astronomia realizado através de uma abordagem holística, que incorpore práticas vivenciais correlacionadas àqueles conteúdos, pode despertar no indivíduo sua identidade cósmica. O método que utilizamos é o fenomenológico e o universo desta pesquisa é um grupo de estudantes da disciplina de Astronomia (Curso de Licenciatura em Geografia/UFRN), onde realizamos observação participante, entrevistas, depoimentos e as práticas vivenciais mencionadas. Neste caso estamos desenvolvendo e adaptando exercícios de algumas técnicas terapêuticas de psicologia transpessoal, que um de nós (LALM) tem aplicado no contexto clínico, para trabalhar aspectos cognitivos envolvidos naquele processo de conscientização cósmica. Resultados parciais claramente referendam a hipótese inicial. Um resultado a destacar é fruto de uma dinâmica de representação corporal interiorizada do eclipse lunar, envolvendo um pequeno grupo daqueles estudantes, na qual conteúdos míticos afloraram de maneira espontânea e contundente para todos, sugerindo ressonância, ou pelo menos isomorfismo, entre o macro e o microcosmo. Este e outros resultados são discutidos em detalhe neste trabalho. (PPGECNM/UFRN; PRONEX/FINEP; NUPA/USP; Temáticos/FAPESP).
Clinical significance of para-aortic lymph node dissection and prognosis in ovarian cancer.
Li, Xianxian; Xing, Hui; Li, Lin; Huang, Yanli; Zhou, Min; Liu, Qiong; Qin, Xiaomin; He, Min
Lymph node metastasis has an important effect on prognosis of patients with ovarian cancer. Moreover, the impact of para-aortic lymph node (PAN) removal on patient prognosis is still unclear. In this study, 80 patients were divided into groups A and B. Group A consisted of 30 patients who underwent PAN + pelvic lymph node (PLN) dissection, whereas group B consisted of 50 patients who only underwent PLN dissection. Analysis of the correlation between PAN clearance and prognosis in epithelial ovarian cancer was conducted. Nineteen cases of lymph node metastasis were found in group A, among whom seven cases were positive for PAN, three cases for PLN, and nine cases for both PAN and PLN. In group B, 13 cases were positive for lymph node metastasis. Our study suggested that the metastatic rate of lymph node is 40.0%. Lymph node metastasis was significantly correlated with FIGO stage, tumor differentiation, and histological type both in groups A and B (P < 0.05). In groups A and B, the three-year survival rates were 77.9% and 69.0%, and the five-year survival rates were 46.7% and 39.2%, respectively. However, the difference was not statistically significant (P > 0.05). The three-year survival rates of PLN metastasis in groups A and B were 68.5% and 41.4%, and the five-year survival rates were 49.7% and 26.4%, respectively. Furthermore, PLN-positive patients who cleared PAN had significantly higher survival rate (P = 0.044). In group A, the three-year survival rates of positive and negative lymph nodes were 43.5% and 72.7%, and the five-year survival rates were 27.2% and 58.5%, respectively. The difference was statistically significant (P = 0.048). Cox model analysis of single factor suggested that lymph node status affected the survival rate (P < 0.01), which was the death risk factor. Consequently, in ovarian carcinoma cytoreductive surgery, resection of the para-aortic lymph node, which has an important function in clinical treatment and prognosis of patients with
Villegas, N.; Cianelli, R.; Ferrer, L.; Kaelber, L.; Peragallo, N.; Yaya, Alexandra O.
Introducción Las mujeres Hispanas de 50 años y más (MHC) son una minoría en Estados Unidos que está a elevado riesgo de adquirir VIH y son el grupo menos estudiado en lo que respecta a salud, características sociales y de comportamiento sexual. Objetivo Investigar los factores que incrementan el riesgo de VIH en las MHC con el propósito de desarrollar o adaptar una intervención apropiada para la "edad y la cultura "de este grupo de mujeres. Metodología Estudio descriptivo de corte transversal con una muestra de 50 MHC, sexualmente activas y que residían en Miami, Florida, Estados Unidos. Se utilizó un cuestionario estructurado administrado por entrevistadores entrenados y bilingües (inglés/español). Las participantes fueron reclutadas en diferentes lugares en el Sur de Florida. Para el análisis de los datos se utilizó estadística descriptiva, tanto medidas de tendencia central como medidas de dispersión. Resultados La edad promedio de las MHC fue de 55,7 ± 6 años (rango 50–76 años). Todas las MHC estaban en la menopausia. Prevención del VIH Las MHC reportaron niveles medios de conocimientos sobre VIH y comunicación con la pareja. En la muestra se reportó la presencia de síntomas depresivos, violencia en la pareja, actitudes negativas hacia las personas viviendo con VIH y baja percepción de riesgo de adquirir VIH. Las MHC mencionaron necesidades de aprendizaje en tópicos relacionados con prevención de VIH y cambios de la edad. Conclusión Las MHC están a riesgo de adquirir VIH y tienen necesidades especiales en términos de educación sobre prevención de VIH. PMID:25242862
On Gravitational Effects in the Schrödinger Equation
NASA Astrophysics Data System (ADS)
Pollock, M. D.
The Schrödinger equation for a particle of rest mass and electrical charge interacting with a four-vector potential can be derived as the non-relativistic limit of the Klein-Gordon equation for the wave function , where and , or equivalently from the one-dimensional action for the corresponding point particle in the semi-classical approximation , both methods yielding the equation in Minkowski space-time , where and . We show that these two methods generally yield equations that differ in a curved background space-time , although they coincide when if is replaced by the effective mass in both the Klein-Gordon action and , allowing for non-minimal coupling to the gravitational field, where is the Ricci scalar and is a constant. In this case , where and , the correctness of the gravitational contribution to the potential having been verified to linear order in the thermal-neutron beam interferometry experiment due to Colella et al. Setting and regarding as the quasi-particle wave function, or order parameter, we obtain the generalization of the fundamental macroscopic Ginzburg-Landau equation of superconductivity to curved space-time. Conservation of probability and electrical current requires both electromagnetic gauge and space-time coordinate conditions to be imposed, which exemplifies the gravito-electromagnetic analogy, particularly in the stationary case, when div, where and . The quantum-cosmological Schrödinger (Wheeler-DeWitt) equation is also discussed in the -dimensional mini-superspace idealization, with particular regard to the vacuum potential and the characteristics of the ground state, assuming a gravitational Lagrangian which contains higher-derivative terms up to order . For the heterotic superstring theory , consists of an infinite series in , where is the Regge slope parameter, and in the perturbative approximation , is positive semi-definite for . The maximally symmetric ground state satisfying the field equations is Minkowski space for and
Mathematical issues in eternal inflation
NASA Astrophysics Data System (ADS)
Singh Kohli, Ikjyot; Haslam, Michael C.
In this paper, we consider the problem of the existence and uniqueness of solutions to the Einstein field equations for a spatially flat Friedmann-Lemaître-Robertson-Walker universe in the context of stochastic eternal inflation, where the stochastic mechanism is modelled by adding a stochastic forcing term representing Gaussian white noise to the Klein-Gordon equation. We show that under these considerations, the Klein-Gordon equation actually becomes a stochastic differential equation. Therefore, the existence and uniqueness of solutions to Einstein's equations depend on whether the coefficients of this stochastic differential equation obey Lipschitz continuity conditions. We show that for any choice of V(φ ), the Einstein field equations are not globally well-posed, hence, any solution found to these equations is not guaranteed to be unique. Instead, the coefficients are at best locally Lipschitz continuous in the physical state space of the dynamical variables, which only exist up to a finite explosion time. We further perform Feller's explosion test for an arbitrary power-law inflaton potential and prove that all solutions to the Einstein field equations explode in a finite time with probability one. This implies that the mechanism of stochastic inflation thus considered cannot be described to be eternal, since the very concept of eternal inflation implies that the process continues indefinitely. We therefore argue that stochastic inflation based on a stochastic forcing term would not produce an infinite number of universes in some multiverse ensemble. In general, since the Einstein field equations in both situations are not well-posed, we further conclude that the existence of a multiverse via the stochastic eternal inflation mechanism considered in this paper is still very much an open question that will require much deeper investigation.
LabVIEW-based control software for para-hydrogen induced polarization instrumentation
Agraz, Jose Grunfeld, Alexander; Li, Debiao; Cunningham, Karl; Willey, Cindy; Pozos, Robert; Wagner, Shawn
The elucidation of cell metabolic mechanisms is the modern underpinning of the diagnosis, treatment, and in some cases the prevention of disease. Para-Hydrogen induced polarization (PHIP) enhances magnetic resonance imaging (MRI) signals over 10 000 fold, allowing for the MRI of cell metabolic mechanisms. This signal enhancement is the result of hyperpolarizing endogenous substances used as contrast agents during imaging. PHIP instrumentation hyperpolarizes Carbon-13 ({sup 13}C) based substances using a process requiring control of a number of factors: chemical reaction timing, gas flow, monitoring of a static magnetic field (B{sub o}), radio frequency (RF) irradiation timing, reaction temperature, and gas pressures. Current PHIP instruments manually control the hyperpolarization process resulting in the lack of the precise control of factors listed above, resulting in non-reproducible results. We discuss the design and implementation of a LabVIEW based computer program that automatically and precisely controls the delivery and manipulation of gases and samples, monitoring gas pressures, environmental temperature, and RF sample irradiation. We show that the automated control over the hyperpolarization process results in the hyperpolarization of hydroxyethylpropionate. The implementation of this software provides the fast prototyping of PHIP instrumentation for the evaluation of a myriad of {sup 13}C based endogenous contrast agents used in molecular imaging.
Conformation of ionizable poly Para phenylene ethynylene in dilute solutions
Wijesinghe, Sidath; Maskey, Sabina; Perahia, Dvora; Grest, Gary S.
The conformation of dinonyl poly para phenylene ethynylenes (PPEs) with carboxylate side chains, equilibrated in solvents of different quality is studied using molecular dynamics simulations. PPEs are of interest because of their tunable electro-optical properties, chemical diversity, and functionality which are essential in wide range of applications. The polymer conformation determines the conjugation length and their assembly mode and affects electro-optical properties which are critical in their current and potential uses. The current study investigates the effect of carboxylate fraction on PPEs side chains on the conformation of chains in the dilute limit, in solvents of different quality. The dinonyl PPE chains are modeled atomistically, where the solvents are modeled both implicitly and explicitly. Dinonyl PPEs maintained a stretched out conformation up to a carboxylate fraction f of 0.7 in all solvents studied. The nonyl side chains are extended and oriented away from the PPE backbone in toluene and in implicit good solvent whereas in water and implicit poor solvent, the nonyl side chains are collapsed towards the PPE backbone. Thus, rotation around the aromatic ring is fast and no long range correlations are seen within the backbone.
Local Ecological Knowledge about Endangered Primates in a Rural Community in Paraíba, Brazil.
Torres Junior, Emanuel Ubaldino; Valença-Montenegro, Mônica Mafra; Castro, Carla Soraia Soares de
The study of local ecological knowledge (LEK) fosters a better understanding of the relationship between humans and the environment. We assessed respondents' ecological knowledge of primates in a rural community located near the Atlantic Forest remnants in the state of Paraíba, Brazil. Populations of Alouatta belzebul (red-handed howler monkeys), Sapajus flavius (blonde capuchins), and Callithrix jacchus (the common marmoset) inhabit the region. We conducted 200 semi-structured interviews and applied thematic content analysis, with weighting, to the responses to quantify the LEK. Respondents showed a low LEK, despite the community's proximity to forest remnants. However, the LEK was significantly higher among men, as well as among those who had a greater degree of contact with the primates. Age did not influence LEK. The studied community apparently does not intensively exploit the forest resources nor does it economically depend on primates, which may explain these individuals' low levels of knowledge about these animals. Such data may support future studies, as well as environmental education and action plans, especially for A. belzebul and S. flavius, both of which are endangered species and targets of the National Action Plan for the Conservation of the Primates of the Northeast.
Para-Phenylenediamine Induces Apoptotic Death of Melanoma Cells and Reduces Melanoma Tumour Growth in Mice
Bhowmick, Debajit; Bhar, Kaushik; Mallick, Sanjaya K.; Das, Subhadip; Chatterjee, Nabanita; Sarkar, Tuhin Subhra; Chakrabarti, Rajarshi; Das Saha, Krishna; Siddhanta, Anirban
Melanoma is one of the most aggressive forms of cancer, usually resistant to standard chemotherapeutics. Despite a huge number of clinical trials, any success to find a chemotherapeutic agent that can effectively destroy melanoma is yet to be achieved. Para-phenylenediamine (p-PD) in the hair dyes is reported to purely serve as an external dyeing agent. Very little is known about whether p-PD has any effect on the melanin producing cells. We have demonstrated p-PD mediated apoptotic death of both human and mouse melanoma cells in vitro. Mouse melanoma tumour growth was also arrested by the apoptotic activity of intraperitoneal administration of p-PD with almost no side effects. This apoptosis is shown to occur primarily via loss of mitochondrial membrane potential (MMP), generation of reactive oxygen species (ROS), and caspase 8 activation. p-PD mediated apoptosis was also confirmed by the increase in sub-G0/G1 cell number. Thus, our experimental observation suggests that p-PD can be a potential less expensive candidate to be developed as a chemotherapeutic agent for melanoma. PMID:27293892
Geochemical and isotopic constraints on the tectonic setting of Serra dos Carajas belt, eastern Para, Brazil
NASA Technical Reports Server (NTRS)
Olszewski, W. J., Jr.; Gibbs, A. K.; Wirth, K. R.
The lower part of the Serra dos Carajas belt is the metavolcanic and metasedimentary Grao para Group (GPG). The GPG is thought to unconformably overlie the older (but undated) Xingu Complex, composed of medium and high-grade gneisses and amphibolite and greenstone belts. The geochemical data indicate that the GPG has many features in common with ancient and modern volcanic suites erupted through continental crust. The mafic rocks clearly differ from those of most Archean greenstone belts, and modern MORB, IAB, and hot-spot basalts. The geological, geochemical, and isotopic data are all consistent with deposition on continental crust, presumably in a marine basin formed by crustal extension. The isotopic data also suggest the existence of depleted mantle as a source for the parent magmas of the GPG. The overall results suggest a tectonic environment, igneous sources, and petrogenesis similar to many modern continental extensional basins, in contrast to most Archean greenstone belts. The Hammersley basin in Australia and the circum-Superior belts in Canada may be suitable Archean and Proterozoic analogues, respectively.
LabVIEW-based control software for para-hydrogen induced polarization instrumentation.
Agraz, Jose; Grunfeld, Alexander; Li, Debiao; Cunningham, Karl; Willey, Cindy; Pozos, Robert; Wagner, Shawn
The elucidation of cell metabolic mechanisms is the modern underpinning of the diagnosis, treatment, and in some cases the prevention of disease. Para-Hydrogen induced polarization (PHIP) enhances magnetic resonance imaging (MRI) signals over 10,000 fold, allowing for the MRI of cell metabolic mechanisms. This signal enhancement is the result of hyperpolarizing endogenous substances used as contrast agents during imaging. PHIP instrumentation hyperpolarizes Carbon-13 ((13)C) based substances using a process requiring control of a number of factors: chemical reaction timing, gas flow, monitoring of a static magnetic field (Bo), radio frequency (RF) irradiation timing, reaction temperature, and gas pressures. Current PHIP instruments manually control the hyperpolarization process resulting in the lack of the precise control of factors listed above, resulting in non-reproducible results. We discuss the design and implementation of a LabVIEW based computer program that automatically and precisely controls the delivery and manipulation of gases and samples, monitoring gas pressures, environmental temperature, and RF sample irradiation. We show that the automated control over the hyperpolarization process results in the hyperpolarization of hydroxyethylpropionate. The implementation of this software provides the fast prototyping of PHIP instrumentation for the evaluation of a myriad of (13)C based endogenous contrast agents used in molecular imaging.
Long-Range Ruthenium-Amine Electronic Communication through the para-Oligophenylene Wire
Shen, Jun-Jian; Zhong, Yu-Wu
The studies of long-range electronic communication are hampered by solubility and potential-splitting issues. A "hybridized redox-asymmetry" method using a combination of organic and inorganic redox species is proposed and exemplified to overcome these two issues. Complexes 1(PF6)–6(PF6) (from short to long in length) with the organic redox-active amine and inorganic cyclometalated ruthenium termini bridged by the para-oligophenylene wire have been prepared. Complex 6 has the longest Ru-amine geometrical distance of 27.85 Å. Complexes 3(PF6) and 4(PF6) show lamellar crystal packing on the basis of a head-to-tail anti-parallelly aligned dimeric structure. Two redox waves are observed for all complexes in the potential region between +0.2 and +0.9 V vs Ag/AgCl. The electrochemical potential splitting is 410, 220, 143, 112, 107, and 105 mV for 1(PF6) through 6(PF6), respectively. Ruthenium (+2) to aminium (N•+) charge transfer transitions have been identified for the odd-electron compounds 12+–62+ by spectroelectrochemical measurements. The electronic communication between amine and ruthenium decreases exponentially with a decay slope of −0.137 Å−1. DFT calculations have been performed to complement these experimental results. PMID:26344929
Time-resolved rotational spectroscopy of para-difluorobenzene·Ar
NASA Astrophysics Data System (ADS)
Weichert, A.; Riehn, C.; Matylitsky, V. V.; Jarzeba, W.; Brutschy, B.
We report on time-resolved rotational spectroscopy experiments of the cluster para-difluorobenzene·Ar ( pDFB·Ar) by picosecond laser pulses in a supersonic expansion. Rotational coherences of pDFB·Ar are generated by resonant electronic excitation and probed by time-resolved fluorescence depletion spectroscopy and time-resolved photoionization ((1+1') PPI) spectroscopy. The former allows the determination of both ground and excited state rotational constants, whereas the latter technique enables the separate study of the excited state with the benefit of mass-selective detection. Since pDFB·Ar represents a near symmetric oblate rotor, persistent J-type transients with tJ≈ n/2( A+ B) could be measured. From their analysis, (A″+B″)=2234.9±2 MHz and (A'+B')=2237.9±2 MHz were obtained. A structural investigation, based on data of the pDFB monomer, is presented resulting in a pDFB·Ar center-of-mass distance of both moieties of R z=3.543±0.017 Å with a change of ΔR z=-0.057±0.009 Å upon electronic excitation. These results are compared to data of former frequency-resolved experiments and ab initio computations.
Origin of the low-energy emission band in epitaxially grown para-sexiphenyl nanocrystallites
Kadashchuk, A.; Schols, S.; Heremans, P.; Skryshevski, Yu.; Piryatinski, Yu.; Beinik, I.; Teichert, C.; Hernandez-Sosa, G.; Sitter, H.; Andreev, A.; Frank, P.; Winkler, A.
A comparative study of steady-state and time-resolved photoluminescence of para-sexiphenyl (PSP) films grown by organic molecular beam epitaxy (OMBE) and hot wall epitaxy (HWE) under comparable conditions is presented. Using different template substrates [mica(001) and KCl(001) surfaces] as well as different OMBE growth conditions has enabled us to vary greatly the morphology of the PSP crystallites while keeping their chemical structure virtually untouched. We prove that the broad redshifted emission band has a structure-related origin rather than being due to monomolecular oxidative defects. We conclude that the growth conditions and type of template substrate impacts substantially on the film morphology (measured by atomic force microscopy) and emission properties of the PSP films. The relative intensity of the defect emission band observed in the delayed spectra was found to correlate with the structural quality of PSP crystallites. In particular, the defect emission has been found to be drastically suppressed when (i) a KCl template substrate was used instead of mica in HWE-grown films, and (ii) in the OMBE-grown films dominated by growth mounds composed of upright standing molecules as opposed to the films consisting of crystallites formed by molecules lying parallel to the substrate.