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| versions
list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0704.2701 | Andrzej Sitarz | Andrzej Sitarz | Twisted Dirac Operators over Quantum Spheres | 17 pages | J. Math. Phys. 49, 033509 (2008) | 10.1063/1.2842067 | null | math.QA math-ph math.MP | null | We construct new families of spectral triples over quantum spheres, with a
particular attention focused on the standard Podles quantum sphere and twisted
Dirac operators.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 12:40:09 GMT"
}
] | 2013-11-21T00:00:00 | [
[
"Sitarz",
"Andrzej",
""
]
] |
0704.2702 | Jens Bolte | Jens Bolte, Daniel Waltner | Semiclassical theory of ballistic transport through chaotic cavities
with spin-orbit interaction | null | Phys. Rev. B 76, 075330 (2007) | 10.1103/PhysRevB.76.075330 | null | cond-mat.mes-hall nlin.CD | null | We investigate the influence of spin-orbit interaction on ballistic transport
through chaotic cavities by using semiclassical methods. Our approach is based
on the Landauer formalism and the Fisher-Lee relations, appropriately
generalized to spin-orbit interaction, and a semiclassical representation of
Green functions. We calculate conductance coefficients by exploiting ergodicity
and mixing of suitably combined classical spin-orbit dynamics, and making use
of the Sieber-Richter method and its most recent extensions. That way we obtain
weak anti-localization and confirm previous results obtained in the symplectic
ensemble of Random Matrix Theory.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 12:53:19 GMT"
}
] | 2010-02-25T00:00:00 | [
[
"Bolte",
"Jens",
""
],
[
"Waltner",
"Daniel",
""
]
] |
0704.2703 | Alex Tomasov Alexsandrovich | P. G. Kasherininov, A. V. Kichaev, and A. A. Tomasov | Photoelectric phenomena in structures based on high-resistivity
semiconductor crystals with a thin insulator layer at the semiconductor-metal
boundary | 8 pages, 8 figures | Semiconductors 29 (11) (1995) 1092-1099 | null | null | cond-mat.mtrl-sci | null | A previously unknown effect-giant spatial redistribution of the electric
field strength in a crystal under illumination of the structure - was
discovered and investigated in real photoresistors on high-resistivity
(semi-insulating) semiconductor CdTe crystals (in metal-thin insulator-
semiconductor-thin insulator -metal structures).
A new concept is proposed for photoelectric phenomena in high- resistivity
semiconductor crystals. The concept is based on the idea that the
redistribution of the field under such conditions that the carrier lifetime
remains unchanged under illumination plays a determining role in these
phenomena. The nature of the effect is described, the dependence of the
characteristics of the structures on the parameters of the crystal and the
insulator layers is explained by the manifestation of this effect, and ways to
produce structures with prescribed photoelectric characteristics for new
devices and scientific methods are examined.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 14:06:31 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kasherininov",
"P. G.",
""
],
[
"Kichaev",
"A. V.",
""
],
[
"Tomasov",
"A. A.",
""
]
] |
0704.2704 | Herma Cuppen | Q. Chang (1), H. M. Cuppen (1,2), and E. Herbst (1,3) ((1) Department
of Physics, The Ohio State University, USA (2) Leiden Observatory, Leiden
University, The Netherlands (3) Departments of Chemistry and Astronomy, The
Ohio State University, USA) | Gas-grain chemistry in cold interstellar cloud cores with a microscopic
Monte Carlo approach to surface chemistry | 13 pages, 7 figures, to be published in A. & A | null | 10.1051/0004-6361:20077423 | null | astro-ph | null | AIM: We have recently developed a microscopic Monte Carlo approach to study
surface chemistry on interstellar grains and the morphology of ice mantles. The
method is designed to eliminate the problems inherent in the rate-equation
formalism to surface chemistry. Here we report the first use of this method in
a chemical model of cold interstellar cloud cores that includes both gas-phase
and surface chemistry. The surface chemical network consists of a small number
of diffusive reactions that can produce molecular oxygen, water, carbon
dioxide, formaldehyde, methanol and assorted radicals. METHOD: The simulation
is started by running a gas-phase model including accretion onto grains but no
surface chemistry or evaporation. The starting surface consists of either flat
or rough olivine. We introduce the surface chemistry of the three species H, O
and CO in an iterative manner using our stochastic technique. Under the
conditions of the simulation, only atomic hydrogen can evaporate to a
significant extent. Although it has little effect on other gas-phase species,
the evaporation of atomic hydrogen changes its gas-phase abundance, which in
turn changes the flux of atomic hydrogen onto grains. The effect on the surface
chemistry is treated until convergence occurs. We neglect all non-thermal
desorptive processes. RESULTS: We determine the mantle abundances of assorted
molecules as a function of time through 2x10^5 yr. Our method also allows
determination of the abundance of each molecule in specific monolayers. The
mantle results can be compared with observations of water, carbon dioxide,
carbon monoxide, and methanol ices in the sources W33A and Elias 16. Other than
a slight underproduction of mantle CO, our results are in very good agreement
with observations.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 12:56:21 GMT"
},
{
"version": "v2",
"created": "Thu, 24 May 2007 10:45:08 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Chang",
"Q.",
""
],
[
"Cuppen",
"H. M.",
""
],
[
"Herbst",
"E.",
""
]
] |
0704.2705 | Ovidiu Vaduvescu | O. Vaduvescu, M. L. McCall, M. G. Richer | Chemical Properties of Star Forming Dwarf Galaxies | Accepted in AJ (Aug 2007) | Astron.J.134:604-616,2007 | 10.1086/518865 | null | astro-ph | null | Recent studies of the near-infrared (NIR) properties of dwarf irregular
galaxies (dIs) and blue compact dwarfs (BCDs) have provided improved estimates
for the NIR luminosity of old stellar populations in these galaxies. These can
be used to derive gas fractions, and thereby to evaluate how BCDs have evolved
with respect to dIs. Oxygen abundances have been derived for four BCDs in the
Virgo Cluster from a run at Gemini-North in 2003. Combining these new
abundances with published values, we study the correlations among the
metallicity, Ks luminosity, gas mass, baryonic mass, and gas fraction. Within
errors, the two types of dwarfs appear to share a common relation between the
oxygen abundance and the luminosity in Ks. The correlation between metallicity
and the gas fraction is the same for BCDs as for dIs, indicating that BCD
evolution has been similar to dIs. Since dIs appear to have evolved as isolated
systems, the BCD bursts are unlikely to be a consequence of gas infall or
merging.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 13:02:30 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Vaduvescu",
"O.",
""
],
[
"McCall",
"M. L.",
""
],
[
"Richer",
"M. G.",
""
]
] |
0704.2706 | Krishnamurthi Ravishankar | L. R. G. Fontes, C. M. Newman, K. Ravishankar, E. Schertzer | The Dynamical Discrete Web | 33 pages and 4 figures | null | null | null | math.PR math-ph math.MP | null | The dynamical discrete web (DDW), introduced in recent work of Howitt and
Warren, is a system of coalescing simple symmetric one-dimensional random walks
which evolve in an extra continuous dynamical parameter s. The evolution is by
independent updating of the underlying Bernoulli variables indexed by discrete
space-time that define the discrete web at any fixed s. In this paper, we study
the existence of exceptional (random) values of s where the paths of the web do
not behave like usual random walks and the Hausdorff dimension of the set of
such exceptional s. Our results are motivated by those about exceptional times
for dynamical percolation in high dimension by H\"aggstrom, Peres and Steif,
and in dimension two by Schramm and Steif. The exceptional behavior of the
walks in DDW is rather different from the situation for dynamical random walks
of Benjamini, H\"aggstrom, Peres and Steif. In particular, we prove that there
are exceptional values of s for which the walk from the origin S^s(n) has
limsup S^s(n)/\sqrt n \leq K with a nontrivial dependence of the Hausdorff
dimension on K. We also discuss how these and other results extend to the
dynamical Brownian web, a natural scaling limit of DDW. The scaling limit is
the focus of a paper in preparation; it was studied by Howitt and Warren and is
related to the Brownian net of Sun and Swart.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 13:05:38 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Fontes",
"L. R. G.",
""
],
[
"Newman",
"C. M.",
""
],
[
"Ravishankar",
"K.",
""
],
[
"Schertzer",
"E.",
""
]
] |
0704.2707 | Vikram Vyas | Vikram Vyas | Spin-String Interaction in QCD Strings | 19 pages, 1 figure; Published version with added discussion and
references in section 5 | Phys.Rev.D78:045003,2008 | 10.1103/PhysRevD.78.045003 | null | hep-th hep-lat | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | I consider the question of the interaction between a QCD string and the spin
of a quark or an antiquark on whose worldline the string terminates. The
problem is analysed from the point of view of a string representation for the
expectation value of a Wilson loop for a spin-half particle. A string
representation of the super Wilson loop is obtained starting from an effective
string representation of a Wilson Loop. The action obtained in this manner is
invariant under a worldline supersymmetry and has a boundary term which
contains the spin-string interaction. For rectangular loops the spin-string
interaction vanishes and there is no spin-spin term in the resulting heavy
quark potential. On the other hand if an allowance is made for the finite
intrinsic thickness of the flux-tube, by assuming that the spin-string
interaction takes place not just at the boundary of the string world-sheet but
extends to a distance of the order of the intrinsic thickness of the flux tube,
then we do obtain a spin-spin interaction which falls as the fifth power of the
distance. Such a term was previously suggested by Kogut and Parisi in the
context of a flux-tube model of confinement.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 13:15:43 GMT"
},
{
"version": "v2",
"created": "Tue, 5 Aug 2008 17:03:48 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Vyas",
"Vikram",
""
]
] |
0704.2708 | Matthias K\"oppe | Elke Eisenschmidt (1), Raymond Hemmecke (1), Matthias K\"oppe (1) ((1)
University of Magdeburg) | Computation of Atomic Fibers of Z-Linear Maps | 27 pages | Contributions to Discrete Mathematics 6 (2011), no. 2 | null | null | math.CO | null | For given matrix $A\in\Z^{d\times n}$, the set $P_{b}=\{z:Az=b,z\in\Z^n_+\}$
describes the preimage or fiber of $b\in\Z^d$ under the $\Z$-linear map
$f_A:\Z^n_+\to\Z^d$, $x\mapsto Ax$. The fiber $P_{b}$ is called atomic, if
$P_{b}=P_{b_1}+P_{b_2}$ implies $b=b_1$ or $b=b_2$. In this paper we present a
novel algorithm to compute such atomic fibers. An algorithmic solution to
appearing subproblems, computational examples and applications are included as
well.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 13:26:24 GMT"
}
] | 2017-01-03T00:00:00 | [
[
"Eisenschmidt",
"Elke",
""
],
[
"Hemmecke",
"Raymond",
""
],
[
"Köppe",
"Matthias",
""
]
] |
0704.2709 | M. Atakan Gurkan | M. Atakan G\"urkan (1) and Clovis Hopman (2) ((1) University of
Amsterdam (2) Leiden University) | Resonant relaxation near a massive black hole: the dependence on
eccentricity | 6 pages, 5 figures, submitted to MNRAS main journal | Mon.Not.Roy.Astron.Soc.379:1083-1088,2007 | 10.1111/j.1365-2966.2007.11982.x | null | astro-ph | null | The orbits of stars close to a massive black hole are nearly Keplerian
ellipses. Such orbits exert long term torques on each other, which lead to an
enhanced angular momentum relaxation known as resonant relaxation. Under
certain conditions, this process can modify the angular momentum distribution
and affect the interaction rates of the stars with the massive black hole more
efficiently than non-resonant relaxation. The torque on an orbit exerted by the
cluster depends on the eccentricity of the orbit. In this paper, we calculate
this dependence and determine the resonant relaxation timescale as a function
of eccentricity. In particular, we show that the component of the torque that
changes the magnitude of the angular momentum is linearly proportional to
eccentricity, so resonant relaxation is much more efficient on eccentric orbits
than on circular orbits.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 13:33:36 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Gürkan",
"M. Atakan",
""
],
[
"Hopman",
"Clovis",
""
]
] |
0704.2710 | Bj\"orn Voss | B. Voss, D. Koester, R. {\O}stensen, R. Napiwotzki, D. Homeier, and D.
Reimers | Six New ZZ Ceti Stars from the SPY and the HQS Surveys | 4 pages, 1 figure, to be published in the proceedings of the 15th
European Workshop on White Dwarfs (ASP) | null | null | null | astro-ph | null | We report on the discovery of six new ZZ Ceti stars. They were selected as
candidates based on preparatory photometric observations of objects from the
Hamburg Quasar Survey (HQS), and based on the spectra of the Supernova Ia
Progenitor Survey (SPY). Time-series photometry of 19 candidate stars was
carried out at the Nordic Optical Telescope (NOT) at Roque de Los Muchachos
Observatory, Spain. The new variables are relatively bright, 15.4<B<16.6. Among
them is WD1150-153, which is the third ZZ Ceti star that shows photospheric
CaII in its spectrum.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 13:33:56 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Voss",
"B.",
""
],
[
"Koester",
"D.",
""
],
[
"Østensen",
"R.",
""
],
[
"Napiwotzki",
"R.",
""
],
[
"Homeier",
"D.",
""
],
[
"Reimers",
"D.",
""
]
] |
0704.2711 | Ralf Toenjes | B. Blasius, R. Toenjes | Zipf law in the popularity distribution of chess openings | 5 pages, 4 figures | Phys. Rev. Lett. 103, 218701 (2009) | 10.1103/PhysRevLett.103.218701 | null | physics.soc-ph cond-mat.stat-mech physics.data-an | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform a quantitative analysis of extensive chess databases and show that
the frequencies of opening moves are distributed according to a power-law with
an exponent that increases linearly with the game depth, whereas the pooled
distribution of all opening weights follows Zipf's law with universal exponent.
We propose a simple stochastic process that is able to capture the observed
playing statistics and show that the Zipf law arises from the self-similar
nature of the game tree of chess. Thus, in the case of hierarchical
fragmentation the scaling is truly universal and independent of a particular
generating mechanism. Our findings are of relevance in general processes with
composite decisions.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 13:38:20 GMT"
},
{
"version": "v2",
"created": "Wed, 18 Nov 2009 10:08:40 GMT"
}
] | 2009-11-18T00:00:00 | [
[
"Blasius",
"B.",
""
],
[
"Toenjes",
"R.",
""
]
] |
0704.2712 | Walter Bergweiler | Walter Bergweiler, Philip J. Rippon and Gwyneth M. Stallard | Dynamics of meromorphic functions with direct or logarithmic
singularities | 29 pages, 2 figures; v2: some overall revision, with comments and
references added; to appear in Proc. London Math. Soc | Proc. London. Math. Soc. 97 (2008), 368-400. | 10.1112/plms/pdn007 | null | math.CV math.DS | null | We show that if a meromorphic function has a direct singularity over
infinity, then the escaping set has an unbounded component and the intersection
of the escaping set with the Julia set contains continua. This intersection has
an unbounded component if and only if the function has no Baker wandering
domains. We also give estimates of the Hausdorff dimension and the upper box
dimension of the Julia set of a meromorphic function with a logarithmic
singularity over infinity. The above theorems are deduced from more general
results concerning functions which have "direct or logarithmic tracts", but
which need not be meromorphic in the plane. These results are obtained by using
a generalization of Wiman-Valiron theory. The method is also applied to complex
differential equations.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 14:03:25 GMT"
},
{
"version": "v2",
"created": "Tue, 29 Jan 2008 16:26:06 GMT"
}
] | 2008-09-28T00:00:00 | [
[
"Bergweiler",
"Walter",
""
],
[
"Rippon",
"Philip J.",
""
],
[
"Stallard",
"Gwyneth M.",
""
]
] |
0704.2713 | Stephan Hell | Stephan Hell | Tverberg's theorem with constraints | 16 pages, 12 figures. Accepted for publication in JCTA. Substantial
revision due to the referees | null | null | null | math.CO | null | The topological Tverberg theorem claims that for any continuous map of the
(q-1)(d+1)-simplex to R^d there are q disjoint faces such that their images
have a non-empty intersection. This has been proved for affine maps, and if $q$
is a prime power, but not in general.
We extend the topological Tverberg theorem in the following way: Pairs of
vertices are forced to end up in different faces. This leads to the concept of
constraint graphs. In Tverberg's theorem with constraints, we come up with a
list of constraints graphs for the topological Tverberg theorem.
The proof is based on connectivity results of chessboard-type complexes.
Moreover, Tverberg's theorem with constraints implies new lower bounds for the
number of Tverberg partitions. As a consequence, we prove Sierksma's conjecture
for $d=2$, and $q=3$.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 14:05:42 GMT"
},
{
"version": "v2",
"created": "Mon, 25 Feb 2008 21:34:10 GMT"
}
] | 2008-02-25T00:00:00 | [
[
"Hell",
"Stephan",
""
]
] |
0704.2714 | Sergey Morozov | S. I. Morozov | On the formation of gyration-like excitations in solid solutions | 9 pages, 6 figures | null | null | 0704.2714 | cond-mat.supr-con | null | Measurements of thermal excitations of V-O and Y-Ba-Cu-O solid solutions have
been performed by a method of inelastic neutron scattering for low-energy
transfers range. Features at energy transfer about 3meV and about 5meV for V-O
and Y-Ba-Cu-O accordingly were observed in neutron scattering spectra. The
reason of appearance of the observed low-energy excitations are the formation
of an effective potential of oxygen with broad weakly upwards bottom at the xy
plane of tetragonal symmetry octahedron, which the interstitial atom occupies.
The experimental observed features can be understood in the representation of
hindered quantum gyration of the interstitial atom. It was assumed that O1 and
O4 atoms in Y-Ba-Cu-O, as well as in V-O system, are in two-dimensional
quantum-well, which has almost flat bottom formed by the surrounding atoms Cu
and Ba. The possibility of formation of collective excitations of gyration-type
as a result of exchange interaction of light atoms in matrix lattice is
considered. The assumption is made that the existence of gyration-like
excitations can play an important role for explanation of some phenomena in
solid state physics, in particular in realization of high values of
temperatures of superconducting transitions in high temperature
superconductors.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:22:52 GMT"
},
{
"version": "v2",
"created": "Thu, 26 Jul 2007 14:09:39 GMT"
}
] | 2007-07-26T00:00:00 | [
[
"Morozov",
"S. I.",
""
]
] |
0704.2715 | Zongxia Liang | Zongxia Liang | Multidimensional SDE with anticipating initial process and reflection | 25pages | null | null | null | math.PR | null | In this paper, the strong solutions $ (X, L)$ of multidimensional stochastic
differential equations with reflecting boundary and possible anticipating
initial random variables is established. The key is to obtain some substitution
formula for Stratonovich integrals via a uniform convergence of the
corresponding Riemann sums and to prove continuity of functionals of $ (X, L)$.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 14:09:55 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Liang",
"Zongxia",
""
]
] |
0704.2716 | J. Marshall Ash | J. M. Ash, M. A. Ash, and P. F. Ash | Constructing a quadrilateral inside another one | null | null | null | null | math.GM | null | Connect each vertex of a convex quadrilateral Q to the midpoint of the next
(proceeding counterclockwise) side. The four connecting lines create an
interior quadrilateral I. We study the ratio area(I)/area(Q). We also determine
what happens to area(I)/area(Q) when the four midpoints are replaced by points
which divide the sides in the ratio of rho to (1-rho) proceeding clockwise.
Here rho is any fixed number satisfying 0 < rho < 1.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 14:21:42 GMT"
},
{
"version": "v2",
"created": "Tue, 1 May 2007 13:19:58 GMT"
},
{
"version": "v3",
"created": "Mon, 17 Sep 2007 15:24:19 GMT"
}
] | 2007-09-17T00:00:00 | [
[
"Ash",
"J. M.",
""
],
[
"Ash",
"M. A.",
""
],
[
"Ash",
"P. F.",
""
]
] |
0704.2717 | F. Assaoui | F. Assaoui and T. Lhallabi | Two Dimensional Quantum (4,4) Null Superstring in de Sitter Space | 16 pages | Afr.J.Math.Phys.1:109-124,2004 | null | null | hep-th | null | The (4,4) null superstring equations of motions and constraints on de Sitter
space are given by using the harmonic superspace. These are solved explicitly
by performing a perturbative expansion of the (4,4) superstring coordinates in
powers of c2, the world-sheet speed of light. The analytic expressions of the
zeroth and first order solutions are determined. On the other hand, we study
the quantization of the (4,4)null superstring in de Sitter space and we
describe its superalgebra.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 14:24:06 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Assaoui",
"F.",
""
],
[
"Lhallabi",
"T.",
""
]
] |
0704.2718 | Adrian Sabin Popescu | Adrian Sabin Popescu | Cosmic Ray Origin and Propagation Model | 18 pages, 6 figures | null | null | null | astro-ph | null | It is presumed that the observed cosmic rays up to about $3\times 10^{18}$ eV
are of Galactic origin, the particles being the ones which are found in the
composition of the stellar winds of stars that explode as supernova into the
interstellar medium (ISM) or into their winds. These particles are accelerated
in the supernova shock. In order to obtain the observed cosmic ray spectrum it
is necessary to take into account the diffusive losses in the Galaxy (which are
making the energy spectrum more steeper). Another modification of the source
spectrum is due to the fragmentation (spallation) of the cosmic ray particles,
after their collision with the ISM atoms. In this paper we are proving that
some particles are injected in the supernova shock one or two time ionized,
and, also, that the contribution of massive stars ($30 M_{\odot}\leq M\leq 50
M_{\odot}$) accelerated particles to cosmic rays (where the winds are highly
enriched in heavy elements) is 1:2 for elements with $Z\geq 6$. Another goal of
this paper is to check if the particles are injected with the same velocity,
energy or momentum.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 14:24:33 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Popescu",
"Adrian Sabin",
""
]
] |
0704.2719 | Santiago Torres | S. Torres, E. Garcia-Berro, J. Isern | The white dwarf luminosity function --II. The effect of the measurement
errors and other biases | 11 pages, 9 figures. Accepted for publication in MNRAS | Mon.Not.Roy.Astron.Soc.378:1461-1470,2007 | 10.1111/j.1365-2966.2007.11887.x | null | astro-ph | null | Only the 1/V_max method has been employed so far for observationally
determining the white dwarf luminosity function, whereas for other kind of
luminosity functions several other methods have been frequently used. Moreover,
the procedures to determine the white dwarf luminosity function are not free of
biases. These biases have two different origins: they can either be of
statistical nature or a consequence of the measurement errors. In a previous
paper we carried out an in-depth study of the first category of biases for
several luminosity function estimators. In this paper we focus on the biases
introduced by the measurement errors and on the effects of the degree of
contamination of the input sample used to build the disc white dwarf luminosity
function by different kinematical populations. To assess the extent of these
biases we use a Monte Carlo simulator to generate a controlled synthetic
population and analyse the behaviour of the disc white dwarf luminosity
function for several assumptions about the magnitude of the measurement errors
and for several degrees of contamination, comparing the performances of the
most robust luminosity function estimators under such conditions.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 14:31:01 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Torres",
"S.",
""
],
[
"Garcia-Berro",
"E.",
""
],
[
"Isern",
"J.",
""
]
] |
0704.2720 | Clifford M. Will | Jing Zeng and Clifford M. Will (Washington University, St. Louis) | Application of energy and angular momentum balance to gravitational
radiation reaction for binary systems with spin-orbit coupling | 12 pages, submitted to General Relativity and Gravitation | Gen.Rel.Grav.39:1661-1673,2007 | 10.1007/s10714-007-0475-6 | null | gr-qc | null | We study gravitational radiation reaction in the equations of motion for
binary systems with spin-orbit coupling, at order (v/c)^7 beyond Newtonian
gravity, or O(v/c)^2 beyond the leading radiation reaction effects for
non-spinning bodies. We use expressions for the energy and angular momentum
flux at infinity that include spin-orbit corrections, together with an
assumption of energy and angular momentum balance, to derive equations of
motion that are valid for general orbits and for a class of coordinate gauges.
We show that the equations of motion are compatible with those derived earlier
by a direct calculation.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 14:45:05 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Zeng",
"Jing",
"",
"Washington University, St. Louis"
],
[
"Will",
"Clifford M.",
"",
"Washington University, St. Louis"
]
] |
0704.2721 | Yuri Rubo | Yuri Rubo | Half-vortices in polariton condensates | 4 pages, 3 figures | Phys. Rev. Lett. 99, 106401 (2007) | 10.1103/PhysRevLett.99.106401 | null | cond-mat.other | null | It is shown that vortices in linearly polarized polariton condensates in
planar semiconductor microcavities carry two winding numbers (k,m). These
numbers can be either integer or half-integer simultaneously. Four half-integer
vortices (1/2,1/2), (-1/2,-1/2), (1/2,-1/2), and (-1/2,1/2) are anisotropic,
possess the smallest energy, and define the Kosterlitz-Thouless transition
temperature. The condensate concentration remains finite within the core of
half-vortex and the polarization becomes fully circular in the core center.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 14:45:33 GMT"
},
{
"version": "v2",
"created": "Fri, 4 May 2007 15:41:02 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Rubo",
"Yuri",
""
]
] |
0704.2722 | Hongbing Cai | H.-B. Cai, Z.-Q. Shen, H. Sudou, L.-L. Shang, S. Iguchi, Y. Murata, Y.
Taniguchi, K. Wakamatsu, H. Takaba | Multi-epoch VLBA observations of 3C 66A | 10 pages, 5 figures, received 30 January 2007, accepted 22 March 2007 | null | 10.1051/0004-6361:20077155 | null | astro-ph | null | We present the results of six-epoch Very Long Baseline Array (VLBA)
observations of 3C~66A. The high-resolution Very Long Baseline Interferometer
(VLBI) maps obtained at multi-frequency (2.3, 8.4, and 22.2 GHz) simultaneously
enabled us to identify the brightest compact component with the core. We find
that the spectrum of the core can be reasonably fitted by the synchrotron
self-absorption model. Our VLBA maps show that the jet of 3C~66A has two
bendings at about 1.2 and 4 mas from the core. We also give possible
identifications of our jet components with the components in previous VLBA
observations by analysing their proper motions. We find consistent differences
of the position from the core in one component between different frequencies at
six epochs.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 14:49:44 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Cai",
"H. -B.",
""
],
[
"Shen",
"Z. -Q.",
""
],
[
"Sudou",
"H.",
""
],
[
"Shang",
"L. -L.",
""
],
[
"Iguchi",
"S.",
""
],
[
"Murata",
"Y.",
""
],
[
"Taniguchi",
"Y.",
""
],
[
"Wakamatsu",
"K.",
""
],
[
"Takaba",
"H.",
""
]
] |
0704.2723 | David Towers | Kevin Bowman, David A. Towers and Vicente R. Varea | Two Generator Subalgebras of Lie Algebras | 12 pages | null | null | null | math.RA | null | J. G. Thompson showed that a finite group G is solvable if and only if every
two -generated subgroup is solvable. Recently, Grunevald, Kunyavskii, Nikolova,
and Plotkin have shown that the analogue holds for finite-dimensional Lie
algebras over infinite fields of characteristic greater than 5. It is a natural
question to ask to what extent the two-generated subalgebras determine the
structure of the algebra. It is to this question that this paper is addressed.
Here, we consider the classes of strongly-solvable and of supersolvable Lie
algebras, and the property of triangulability.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 14:52:44 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Bowman",
"Kevin",
""
],
[
"Towers",
"David A.",
""
],
[
"Varea",
"Vicente R.",
""
]
] |
0704.2724 | Cristina Volpe | R. Lazauskas, C. Volpe | Neutrino beams as a probe of the nuclear isospin and spin-isospin
excitations | 13 pages, 4 figures, 3 tables | Nucl.Phys.A792:219-228,2007 | 10.1016/j.nuclphysa.2007.06.005 | null | nucl-th hep-ex hep-ph nucl-ex | null | We explore the possibility of performing nuclear structure studies using low
energy neutrino beams. In particular, low energy beta-beams and conventional
sources (muon decay-at-rest) are considered. We present results on the total
charged-current as well as flux-averaged cross sections associated to electron
(anti)-neutrino scattering on oxygen, iron, molybdenum and lead, as typical
examples. It is shown that by using neutrinos from low energy beta-beams,
information on forbidden states, in particular the spin-dipole, could be
extracted.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:06:25 GMT"
},
{
"version": "v2",
"created": "Tue, 21 Aug 2007 16:53:37 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Lazauskas",
"R.",
""
],
[
"Volpe",
"C.",
""
]
] |
0704.2725 | Manuel Cebri\'an | Manuel Cebrian and Ivan Cantador | Exploiting Heavy Tails in Training Times of Multilayer Perceptrons: A
Case Study with the UCI Thyroid Disease Database | 8 pages, 4 figures, submitted for consideration to the "Statistics
and Its Interface" journal | null | null | null | cs.NE | null | The random initialization of weights of a multilayer perceptron makes it
possible to model its training process as a Las Vegas algorithm, i.e. a
randomized algorithm which stops when some required training error is obtained,
and whose execution time is a random variable. This modeling is used to perform
a case study on a well-known pattern recognition benchmark: the UCI Thyroid
Disease Database. Empirical evidence is presented of the training time
probability distribution exhibiting a heavy tail behavior, meaning a big
probability mass of long executions. This fact is exploited to reduce the
training time cost by applying two simple restart strategies. The first assumes
full knowledge of the distribution yielding a 40% cut down in expected time
with respect to the training without restarts. The second, assumes null
knowledge, yielding a reduction ranging from 9% to 23%.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:58:04 GMT"
},
{
"version": "v2",
"created": "Fri, 7 Dec 2007 03:06:49 GMT"
}
] | 2011-11-09T00:00:00 | [
[
"Cebrian",
"Manuel",
""
],
[
"Cantador",
"Ivan",
""
]
] |
0704.2726 | Bodineau Thierry | T. Bodineau, B.Derrida | Cumulants and large deviations of the current through non-equilibrium
steady states | null | null | 10.1016/j.crhy.2007.04.014 | null | cond-mat.stat-mech | null | Using a generalisation of the detailed balance for systems maintained out of
equilibrium by contact with 2 reservoirs at unequal temperatures or at unequal
densities, we recover the fluctuation theorem for the large deviation funtion
of the current. For large diffusive systems, we show how the large deviation
funtion of the current can be computed using a simple additivity principle. The
validity of this additivity principle and the occurence of phase transitions
are discussed in the framework of the macroscopic fluctuation theory.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:27:56 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Bodineau",
"T.",
""
],
[
"Derrida",
"B.",
""
]
] |
0704.2727 | Fiammetta Battaglia | Fiammetta Battaglia | Complex quotients by nonclosed groups and their stratifications | Research announcement. Updated version, shortened, exposition
improved, 8 pp | C. R. Math. Rep. Acad. Sci. Canada Vol. 29 (2) 2007, pp 33-40 | null | null | math.AG | null | We define the notion of complex stratification by quasifolds and show that
such spaces occur as complex quotients by certain nonclosed subgroups of tori
associated to convex polytopes. The spaces thus obtained provide a natural
generalization to the nonrational case of the notion of toric variety
associated with a rational convex polytope.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:31:50 GMT"
},
{
"version": "v2",
"created": "Sat, 1 Mar 2008 22:45:52 GMT"
}
] | 2008-03-02T00:00:00 | [
[
"Battaglia",
"Fiammetta",
""
]
] |
0704.2728 | Alessandra Retico | I. Gori, M.E. Fantacci, A. Preite Martinez, A. Retico | An automated system for lung nodule detection in low-dose computed
tomography | 9 pages, 9 figures; Proceedings of the SPIE Medical Imaging
Conference, 17-22 February 2007, San Diego, California, USA, Vol. 6514,
65143R | null | 10.1117/12.709642 | null | physics.med-ph | null | A computer-aided detection (CAD) system for the identification of pulmonary
nodules in low-dose multi-detector helical Computed Tomography (CT) images was
developed in the framework of the MAGIC-5 Italian project. One of the main
goals of this project is to build a distributed database of lung CT scans in
order to enable automated image analysis through a data and cpu GRID
infrastructure. The basic modules of our lung-CAD system, a dot-enhancement
filter for nodule candidate selection and a neural classifier for
false-positive finding reduction, are described. The system was designed and
tested for both internal and sub-pleural nodules. The results obtained on the
collected database of low-dose thin-slice CT scans are shown in terms of free
response receiver operating characteristic (FROC) curves and discussed.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:33:35 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Gori",
"I.",
""
],
[
"Fantacci",
"M. E.",
""
],
[
"Martinez",
"A. Preite",
""
],
[
"Retico",
"A.",
""
]
] |
0704.2729 | Daniel Sunhede | Kimmo Kainulainen, Johanna Piilonen, Vappu Reijonen, and Daniel
Sunhede | Spherically symmetric spacetimes in f(R) gravity theories | Published version, 12 pages, 7 figures | Phys.Rev.D76:024020,2007 | 10.1103/PhysRevD.76.024020 | null | gr-qc astro-ph hep-th | null | We study both analytically and numerically the gravitational fields of stars
in f(R) gravity theories. We derive the generalized Tolman-Oppenheimer-Volkov
equations for these theories and show that in metric f(R) models the
Parameterized Post-Newtonian parameter $\gamma_{\rm PPN} = 1/2$ is a robust
outcome for a large class of boundary conditions set at the center of the star.
This result is also unchanged by introduction of dark matter in the Solar
System. We find also a class of solutions with $\gamma_{\rm PPN} \approx 1$ in
the metric $f(R)=R-\mu^4/R$ model, but these solutions turn out to be unstable
and decay in time. On the other hand, the Palatini version of the theory is
found to satisfy the Solar System constraints. We also consider compact stars
in the Palatini formalism, and show that these models are not inconsistent with
polytropic equations of state. Finally, we comment on the equivalence between
f(R) gravity and scalar-tensor theories and show that many interesting Palatini
f(R) gravity models can not be understood as a limiting case of a
Jordan-Brans-Dicke theory with $\omega \to -3/2$.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:34:02 GMT"
},
{
"version": "v2",
"created": "Fri, 7 Mar 2008 14:31:16 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kainulainen",
"Kimmo",
""
],
[
"Piilonen",
"Johanna",
""
],
[
"Reijonen",
"Vappu",
""
],
[
"Sunhede",
"Daniel",
""
]
] |
0704.2730 | James Colliander | J. Colliander, M. Keel, G. Staffilani, H. Takaoka, T. Tao | Resonant decompositions and the I-method for cubic nonlinear Schrodinger
on R^2 | null | null | null | null | math.AP math-ph math.MP | null | The initial value problem for the cubic defocusing nonlinear Schr\"odinger
equation $i \partial_t u + \Delta u = |u|^2 u$ on the plane is shown to be
globally well-posed for initial data in $H^s (\R^2)$ provided $s>1/2$. The
proof relies upon an almost conserved quantity constructed using multilinear
correction terms. The main new difficulty is to control the contribution of
resonant interactions to these correction terms. The resonant interactions are
significant due to the multidimensional setting of the problem and some
orthogonality issues which arise.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:36:26 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Colliander",
"J.",
""
],
[
"Keel",
"M.",
""
],
[
"Staffilani",
"G.",
""
],
[
"Takaoka",
"H.",
""
],
[
"Tao",
"T.",
""
]
] |
0704.2731 | Hideki Maeda | Hideki Maeda | Global structure and physical interpretation of the Fonarev solution for
a scalar field with exponential potential | 4 pages, 1 figure, revised version with title changed. The solution
was obtained by Fonarev in 1995 | null | null | CECS-PHY-07/06 | gr-qc hep-th | null | We discuss the physical interpretation of a dynamical and inhomogeneous
spherically symmetric solution obtained by Fonarev for a scalar field with an
exponential potential. There is a single parameter $w$ in the solution which
can be set to $\pm1$ if it is non-zero, in addition to the steepness parameter
$\lambda$ in the potential. The spacetime is conformally static and
asymptotically flat Friedmann-Robertson-Walker spacetime. The solution reduces
to the Friedmann-Robertson-Walker solution for $w=0$. There are two curvature
singularities, of which one is a timelike central singularity and the other is
a big-bang or big-crunch type singularity. Depending on the parameters, the
spacetime can possess a future outer trapping horizon in the collapsing case.
Then the solution represents a dynamical black hole in the sense of Hayward
although there is a locally naked singularity at the center and no black-hole
event horizon. This demonstrates a weak point of the local definition of a
black hole in terms of a trapping horizon.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:46:28 GMT"
},
{
"version": "v2",
"created": "Tue, 24 Apr 2007 15:38:46 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Maeda",
"Hideki",
""
]
] |
0704.2732 | David Wales | Arjeh M Cohen, Bart Frenk, David Wales | Brauer Algebras of Simply Laced Type | 19 pages | null | null | null | math.RT math.GR | null | The diagram algebra introduced by Brauer that describes the centralizer
algebra on tensor products of the natural representation of an orthogonal group
has a presentation by generators and relations that only depends on the graph
of type An on n nodes. Here we describe an algebra depending on an arbitrary
graph of type M. We study its structure when the type is An, Dn, E6, E7, E8. We
determine the representations and find the dimensions. The algebra is
generically semisimple and contains the group algebra of the Coxeter type M as
a subalgebra. It is a ring homomorphism of the Birman-Murakami-Wenzl algebra of
these types. This fact will be used in later work determining the structure of
Birman-Murakami-Wenzl algebras of simply laced spherical type.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 16:24:06 GMT"
},
{
"version": "v2",
"created": "Fri, 20 Apr 2007 21:01:40 GMT"
},
{
"version": "v3",
"created": "Thu, 26 Apr 2007 15:14:56 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Cohen",
"Arjeh M",
""
],
[
"Frenk",
"Bart",
""
],
[
"Wales",
"David",
""
]
] |
0704.2733 | Scott Zrebiec | Scott Zrebiec | The order of the decay of the hole probability for Gaussian random
SU(m+1) polynomials | This paper generalizes one which was previously posted by the author | null | null | null | math.CV math.PR | null | We show that for Gaussian random SU(m+1) polynomials of a large degree N the
probability that there are no zeros in the disk of radius r is less than
$e^{-c_{1,r} N^{m+1}}$, and is also greater than $e^{-c_{2,r} N^{m+1}}$.
Enroute to this result, we also derive a more general result: probability
estimates for the event where the volume of the zero set of a random polynomial
of high degree deviates significantly from its mean.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:40:44 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Zrebiec",
"Scott",
""
]
] |
0704.2734 | Lars Winther Christensen | Lars Winther Christensen and Sean Sather-Wagstaff | A Cohen-Macaulay algebra has only finitely many semidualizing modules | Final version; 3 pp. To appear in Math. Proc. Cambridge Philos. Soc | null | null | null | math.AC | null | We prove the result stated in the title, which answers the equicharacteristic
case of a question of Vasconcelos.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:46:43 GMT"
},
{
"version": "v2",
"created": "Fri, 16 Nov 2007 17:19:48 GMT"
}
] | 2011-11-09T00:00:00 | [
[
"Christensen",
"Lars Winther",
""
],
[
"Sather-Wagstaff",
"Sean",
""
]
] |
0704.2735 | F. Assaoui | F.Assaoui and P. Pereyra | Charge Polarization Effects and Hole Spectra Characteristics in
Alxgai-xN/Gan Superlattices | 21 pages, 12 figures | Journal of Applied Physics(J. Appl. Phys). Vol.91, No.9,(2002) | null | IC/2001/135 | cond-mat.other | null | We study the effects of charge polarization on the extended physical
properties of superlattices, such as transmission coefficients and valence band
structure. We consider both linear and parabolic modulation of the band edge.
Based on the theory of finite periodic systems (TFPS), analytic expressions and
high precision calculations of the relevant physical quantities for n-cell
systems are obtained. New and also well-known features of these systems are
identified. Besides the well-known energy bandstructure, we also have the field
bandstructure, with interesting characteristics.Wider field gaps at stronger
internal electric fields and higher density of field bands for larger layer
widths are some of these characteristics. Well denned level density asymmetries
identify the minibands induced by charge polarization or the so-called Quantum
Confining Stark Effect. We present the n-cell transmission amplitudes,
transmission coefficients and miniband structures for different values of the
relevant parameters.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:48:19 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Assaoui",
"F.",
""
],
[
"Pereyra",
"P.",
""
]
] |
0704.2736 | Jacques L. Rubin | T. Grandou, J.L. Rubin | Twin Paradox and Causality | 17 pages, no figures, submitted to Am. J. Phys | ECONFC0706044:15,2007 | null | INLN 2006#06 | gr-qc | null | After pointing out the historical avatar at the origin of a would be twin or
clock paradox, we argue that, at least on a local scale, the (re-qualified)
paradox is but a necessary consequence of the sole principle of causality.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:50:12 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Grandou",
"T.",
""
],
[
"Rubin",
"J. L.",
""
]
] |
0704.2737 | Vito Sguera | V. Sguera, A. Bazzano, A. J. Bird, A. B. Hill, A. J. Dean, L. Bassani,
A. Malizia, P. Ubertini | INTEGRAL high energy detection of the transient IGR J11321-5311 | accepted for publication in A&A letter, 4 pages, 6 figures | null | 10.1051/0004-6361:20077439 | null | astro-ph | null | Context: The transient hard X-ray source IGR J11321-5311 was discovered by
INTEGRAL on June 2005, during observations of the Crux spiral arm. To date,
this is the only detection of the source to be reported by any X/gamma-ray
mission. Aims: To characterize the behaviour and hence the nature of the source
through temporal and spectral IBIS analysis. Methods: Detailed spectral and
temporal analysis has been performed using standard INTEGRAL software OSA
v.5.1. Results: To date, IGR J11321-5311 has been detected only once. It was
active for about 3.5 hours, a short and bright flare lasting about 1.5 hours is
evident in the IBIS light curve. It reached a peak flux of about 80 mCrab or
2.2x10E-9 erg cmE-2 sE-1 (20--300 keV),corresponding to a peak luminosity of
1.1x10E37 erg sE-1 (assuming a distance of 6.5 kpc). During the outburst, the
source was detected with a significance of 18 sigma (20--300 keV) and 8 sigma
(100--300 keV). The spectrum of the total outburst activity (17--300 keV) is
best fitted by the sum of a power law (Gamma=0.55+/-0.18) plus a black body
(kT=1.0{+0.2}_{-0.3} keV), with no evidence for a break up to 300 keV. A
spectral analysis at Science Window level revealed an evident hardening of the
spectrum through the outburst. The IBIS data were searched for pulsations with
no positive result. Conclusions: The X-ray spectral shape and the flaring
behaviour favour the hypothesis that IGR J11321-5311 is an Anomalous X-ray
Pulsar, though a different nature can not be firmly rejected at the present
stage.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:54:06 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sguera",
"V.",
""
],
[
"Bazzano",
"A.",
""
],
[
"Bird",
"A. J.",
""
],
[
"Hill",
"A. B.",
""
],
[
"Dean",
"A. J.",
""
],
[
"Bassani",
"L.",
""
],
[
"Malizia",
"A.",
""
],
[
"Ubertini",
"P.",
""
]
] |
0704.2738 | Eric Nuss | E. Nuss (on behalf of GLAST LAT Dark Matter and New Physics WG) | Dark Matter Searche with GLAST | Comment: 6 pages, 3 figures, 36th COSPAR proceeding accepted for
publication in "Advances in Space Research" | Adv.Space Res.41:2029-2031,2008 | 10.1016/j.asr.2007.03.045 | null | astro-ph | null | The Gamma-Ray Large Area Space Telescope (GLAST), scheduled to be launched in
fall 2007, is the next generation satellite for high-energy gamma-ray
astronomy. The Large Area Telescope (LAT),
GLAST main instrument, with a wide field of view (> 2 sr), a large effective
area (> 8000 cm^2 at 1 GeV) and 20 MeV - 300 GeV energy range, will provide
excellent high energy gamma-ray observations for Dark Matter searches. In this
paper we examine the potential of the LAT to detect gamma-rays coming from
WIMPS annihilation in the context of supersymmetry. As an example, two search
regions are investigated: the galactic center and the galactic satellites.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:55:00 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Nuss",
"E.",
"",
"on behalf of GLAST LAT Dark Matter and New Physics WG"
]
] |
0704.2739 | Chris Stock | C. Stock, R.A. Cowley, W.J.L. Buyers, R. Coldea, C. Broholm, C.D.
Frost, R.J. Birgeneau, R. Liang, D. Bonn, W.N. Hardy | Evidence for decay of spin-waves above the pseudogap in underdoped
YBa2Cu3O6.35 | 5 pages, 4 figures, to be published in Physical Review B | Phys. Rev. B 75, 172510 (2007) | 10.1103/PhysRevB.75.172510 | null | cond-mat.supr-con cond-mat.str-el | null | The magnetic spectrum at high-energies in heavily underdoped
YBa$_{2}$Cu$_{3}$O$_{6.35}$ (T$_{c}$=18 K) has been determined throughout the
Brillouin zone. At low-energy the scattering forms a cone of spin excitations
emanating from the antiferromagnetic (0.5, 0.5) wave vector with an acoustic
velocity similar to that of insulating cuprates. At high energy transfers,
below the maximum energy of 270 meV at (0.5, 0), we observe zone boundary
dispersion much larger and spectral weight loss more extensive than in
insulating antiferromagnets. Moreover we report phenomena not found in
insulators, an overall lowering of the zone-boundary energies and a large
damping of $\sim$ 100 meV of the spin excitations at high-energies. The energy
above which the damping occurs coincides approximately with the gap determined
from transport measurements. We propose that as the energy is raised the spin
excitations encounter an extra channel of decay into particle-hole pairs of a
continuum that we associate with the pseudogap.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 16:15:24 GMT"
}
] | 2018-07-20T00:00:00 | [
[
"Stock",
"C.",
""
],
[
"Cowley",
"R. A.",
""
],
[
"Buyers",
"W. J. L.",
""
],
[
"Coldea",
"R.",
""
],
[
"Broholm",
"C.",
""
],
[
"Frost",
"C. D.",
""
],
[
"Birgeneau",
"R. J.",
""
],
[
"Liang",
"R.",
""
],
[
"Bonn",
"D.",
""
],
[
"Hardy",
"W. N.",
""
]
] |
0704.2740 | Jerome Petri | J. Petri | Relativistic stabilisation of the diocotron instability in a pulsar
"cylindrical" electrosphere | Accepted by A&A | null | 10.1051/0004-6361:20066985 | null | astro-ph | null | In a previous work, we showed that the differentially rotating equatorial
disk in the pulsar's electrosphere is diocotron unstable in the
non-relativistic regime. In this paper, we extend these results and study the
relativistic and electromagnetic stabilisation effects by including the
magnetic field perturbation and allow for relativistic speeds of the guiding
centre, in a self-consistent manner. We use the electric drift approximation,
valid for low-density plasmas.
We linearise the coupled relativistic cold-fluid and Maxwell equations in the
electric drift approximation. The non-linear eigenvalue problem for the
perturbed azimuthal electric field is solved numerically with standard technics
for boundary value problems like the shooting method. The spectrum of the
relativistic diocotron instability in a non-neutral plasma column confined
between two cylindrically conducting walls is computed.
For low-speed motions, we recover the eigenfunctions and eigenspectra of the
non-relativistic diocotron instability. Our algorithm is also checked in the
relativistic planar diode geometry for which an analytical expression of the
dispersion relation is known. As expected, when the relativistic and
electromagnetic effects become significant, the diocotron instability tends to
stabilise. In cylindrical geometry, for some special rotation profile, all
azimuthal modes $l$ are completely suppressed for sufficiently relativistic
flows. However, for the profile relevant to the electrosphere, depending on the
exact rotation curves, the growth rates can either significantly decrease till
they vanish or persist for moderate $l$.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 16:12:16 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Petri",
"J.",
""
]
] |
0704.2741 | Koji Murakawa | K. Murakawa, J. Nakashima, K. Ohnaka, and S. Deguchi | Near-infrared polarimetric study of the bipolar nebula IRAS 19312+1950 | 8 pages with 4 figures | null | 10.1051/0004-6361:20066574 | null | astro-ph | null | We obtained H-band polarimetric data of IRAS 19312+1950 using the
near-infrared camera (CIAO) on the 8 m Subaru telescope. In order to
investigate the physical properties of the central star and the nebula, we
performed dust radiative transfer modeling and compared the model results with
the observed spectral energy distributions (SEDs), the radial profiles of the
total intensity image, and the fraction of linear polarization map. The total
intensity image shows a nearly spherical core with ~3" radius, an S-shaped arm
extending ~10" in the northwest to southeast direction, and an extended lobe
towards the southwest. The polarization map shows a centro-symmetric vector
alignment in almost the entire nebula and low polarizations along the S-shaped
arm. These results suggest that the nebula is accompanied by a central star,
and the S-shaped arm has a physically ring-like structure. From our radiative
transfer modeling, we estimated the stellar temperature, the bolometric
luminosity, and the current mass-loss rate to be 2800 K, 7000 L_sun, and
5.3x10^{-6} M_sun yr^{-1}, respectively. Taking into account previous
observational results, such as the detection of SiO maser emissions and
silicate absorption feature in the 10 $\mu$m spectrum, our dust radiative
transfer analysis based on our NIR imaging polarimetry suggests that (1) the
central star of IRAS 19312+1950 is likely to be an oxygen-rich, dust-enshrouded
AGB star and (2) most of the circumstellar material originates from other
sources (e.g. ambient dark clouds) rather than as a result of mass loss from
the central star.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 16:05:53 GMT"
},
{
"version": "v2",
"created": "Tue, 24 Apr 2007 11:52:58 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Murakawa",
"K.",
""
],
[
"Nakashima",
"J.",
""
],
[
"Ohnaka",
"K.",
""
],
[
"Deguchi",
"S.",
""
]
] |
0704.2742 | Yuri V. Kopaev | V.I. Belyavsky and Yu.V. Kopaev | Biordered superconductivity and strong pseudogap state | 11 pages, 4 fugures | null | 10.1103/PhysRevB.76.214506 | null | cond-mat.supr-con | null | Interrelation between the two-particle and mean-field problems is used to
describe the strong pseudogap and superconducting states in cuprates. We
present strong pseudogap state as off-diagonal short-range order (ODSRO)
originating from quasi-stationary states of the pair of repulsing particles
with large total momentum (K - pair). Phase transition from the ODSRO state
into the off-diagonal long-range ordered (ODLRO) superconducting state is
associated with Bose-Einstein condensation of the K - pairs. A checkerboard
spatial order observable in the superconducting state in the cuprates is
explained by a rise of the K - pair density wave. A competition between the
ODSRO and ODLRO states leads to the phase diagram typical of the cuprates.
Biordered superconducting state of coexisting condensates of Cooper pairs with
zero momentum and K - pairs explains some properties of the cuprates observed
below Tc: Drude optical conductivity, unconventional isotope effect and two-gap
quasiparticle spectrum with essentially different energy scales.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 16:06:56 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Belyavsky",
"V. I.",
""
],
[
"Kopaev",
"Yu. V.",
""
]
] |
0704.2743 | David Wales | Arjeh M. Cohen, D. A. H. Gijsbers, David B. Wales | The Birman-Murakami-Algebras Algebras of Type Dn | 32 pages. This is a greatly expanded version of the earlier arXiv
version which was titled "The BMW Algebras of Type Dn" | null | null | null | math.RT math.GR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Birman-Murakami-Wenzl algebra (BMW algebra) of type Dn is shown to be
semisimple and free of rank (2^n+1)n!!-(2^(n-1)+1)n! over a specified
commutative ring R, where n!! is the product of the first n odd integers. We
also show it is a cellular algebra over suitable ring extensions of R. The
Brauer algebra of type Dn is the image af an R-equivariant homomorphism and is
also semisimple and free of the same rank, but over the polynomial ring Z with
delta and its inverse adjoined. A rewrite system for the Brauer algebra is used
in bounding the rank of the BMW algebra above. As a consequence of our results,
the generalized Temperley-Lieb algebra of type Dn is a subalgebra of the BMW
algebra of the same type.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 16:29:00 GMT"
},
{
"version": "v2",
"created": "Sun, 27 Jan 2008 19:01:30 GMT"
},
{
"version": "v3",
"created": "Mon, 2 May 2011 18:44:09 GMT"
}
] | 2011-05-03T00:00:00 | [
[
"Cohen",
"Arjeh M.",
""
],
[
"Gijsbers",
"D. A. H.",
""
],
[
"Wales",
"David B.",
""
]
] |
0704.2744 | Szil\'ard Szab\'o | Szilard Szabo | Nahm transform and parabolic minimal Laplace transform | Major revision of the exposition, new title, with essentially
unmodified results | Journal of Geometry and Physics 62 (2012) 2241--2258 | null | null | math.AG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove that Nahm transform for integrable connections with a finite number
of regular singularities and an irregular singularity of rank 1 on the Riemann
sphere is equivalent -- up to considering integrable connections as holonomic
$\D$-modules -- to minimal Laplace transform. We assume semi-simplicity and
resonance-freeness conditions, and we work in the framework of objects with a
parabolic structure. In particular, we describe the definition of the parabolic
version of Laplace transform due to C. Sabbah. The proof of the main result
relies on the study of a twisted de Rham complex.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 15:00:53 GMT"
},
{
"version": "v2",
"created": "Fri, 2 Sep 2011 15:32:04 GMT"
}
] | 2012-08-06T00:00:00 | [
[
"Szabo",
"Szilard",
""
]
] |
0704.2745 | Tomilchik Lev | L.M. Tomilchik | Pioneer Anomaly and Accelerating Universe as Effects of the Minkowski
Space Conformal Symmetry | 13 pages, 3 figures, typos in text and references have been corrected | null | null | null | gr-qc | null | On the basis of the nonisometric transformations subgroup of the SO(4.2)
group, the nonlinear time inhomogeneity one-parameter conformal transformations
are constructed. The connection between the group parameter and the Hubble
constant H0 is established. It is shown that the existence of an anomalous
blue-shifted frequency drift is a pure kinematic manifestation of the time
inhomogeneity induced by the Universe expansion. This conclusion is confirmed
via a generalization of the standard Special Relativity clock synchronization
procedure to the space expanding case. The obtained formulae are in accordance
with the observable Pioneer Anomaly effect. The anomalous blue-shifted drift is
universal, does not depend on the presence of graviting centers and can be, in
principle, observed on any frequencies under suitable experimental conditions.
The explicit analytic expression for the speed of recession--intergalactic
distance ratio is obtained in the form of a function of the red shift z valid
in the whole range of its variation. In the small z limit this expression
exactly reproduces the Hubble law. The maximum value of this function at
z=0.475 quantitatively corresponds to the experimentally found value z(exp) =
0.46 +/- 0.13 of the transition from the decelerated to the accelerated
expansion of the Universe.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 16:16:18 GMT"
},
{
"version": "v2",
"created": "Thu, 10 May 2007 10:07:52 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Tomilchik",
"L. M.",
""
]
] |
0704.2746 | Matteo Masino | Matteo Masino, Alberto Girlando, Aldo Brillante | Intermediate regime in Tetrathiafulvalene-Chloranil (TTF-CA)
pressure-induced neutral-ionic transition | 7 pages, 5 figures | Phys. Rev. B 76, 064114 (2007) | 10.1103/PhysRevB.76.064114 | null | cond-mat.mtrl-sci cond-mat.str-el | null | We report a detailed spectroscopic study of the pressure induced
neutral-ionic phase transition (NIT) of the mixed-stack charge-transfer (CT)
crystal tetrathiafulvalene-chloranil (TTF-CA). We show that the pressure
induced phase transition is still first-order and involves the presence of an
intermediate disordered phase, defined by the coexistence of two species of
different ionicity. Further application of pressure gradually converts this
phase into an homogeneous ferroelectric phase with a single ionicity. In
addition, we detect strong pretransitional phenomena which anticipate the
intermediate phase and are indicative of a precursor dynamic regime dominated
by fluctuations.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 16:53:40 GMT"
}
] | 2013-05-29T00:00:00 | [
[
"Masino",
"Matteo",
""
],
[
"Girlando",
"Alberto",
""
],
[
"Brillante",
"Aldo",
""
]
] |
0704.2747 | Christophe Pinte | C. Pinte, L. Fouchet, F. Menard, J.-F. Gonzalez, G. Duchene | On the stratified dust distribution of the GG Tau circumbinary ring | 9 pages, 11 figures. Accepted for publication in A&A | Astron.Astrophys.469:963-971,2007 | 10.1051/0004-6361:20077137 | null | astro-ph | null | Our objective is to study the vertical dust distribution in the circumbinary
ring of the binary system GG Tau and to search for evidence of stratification,
one of the first steps expected to occur during planet formation.
We present a simultaneous analysis of four scattered light images spanning a
range of wavelength from 800 nm to 3800 nm and compare them with (i) a
parametric prescription for the vertical dust stratification, and (ii) with the
results of SPH bi-fluid hydrodynamic calculations.
The parametric prescription and hydrodynamical calculations of stratification
both reproduce the observed brightness profiles well. These models also provide
a correct match for the observed star/ring integrated flux ratio. Another
solution with a well-mixed, but ``exotic'', dust size distribution also matches
the brightness profile ratios but fails to match the star/ring flux ratio.
These results give support to the presence of vertical stratification of the
dust in the ring of GG Tau and further predict the presence of a radial
stratification also.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:07:34 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Pinte",
"C.",
""
],
[
"Fouchet",
"L.",
""
],
[
"Menard",
"F.",
""
],
[
"Gonzalez",
"J. -F.",
""
],
[
"Duchene",
"G.",
""
]
] |
0704.2748 | Alexander K. Hartmann | A. K. Hartmann | Droplets in the two-dimensional +-J spin glass: evidence for (non-)
universality | 4 pages, 3 figures | null | null | null | cond-mat.dis-nn cond-mat.stat-mech | null | Using mappings to computer-science problems and by applying sophisticated
algorithms, one can study numerically many problems much better compared to
applying standard approaches like Monte Carlo simulations. Here, using
calculations of ground states of suitable perturbed systems, droplets are
obtained in two-dimensional +-J spin glasses, which are in the focus of a
currently very lifely debate. Since a sophisticated matching algorithm is
applied here, exact ground states of large systems up to L^2=256^2 spins can be
generated. Furthermore, no equilibration or extrapolation to T=0 is necessary.
Three different +-J models are studied here: a) with open boundary conditions,
b) with fixed boundary conditions and c) a diluted system where a fraction
p=0.125 of all bonds is zero. For large systems, the droplet energy shows for
all three models a power-law behavior E_D L^\theta'_D with \theta'_D<0. This is
different from previous studies of domain walls, where a convergence to a
constant non-zero value (\theta_dw=0) has been found for such models. After
correcting for the non-compactness of the droplets, the results are likely to
be compatible with \theta_D= -0.29 for all three models.
This is in accordance with the Gaussian system where \theta_D=-0.287(4)
(\nu=3.5 via \nu=-1/\theta_D). Nevertheless, the disorder-averaged spin-spin
correlation exponent \eta is determined here via the probability to have a
non-zero-energy droplet, and \eta~0.22$ is found for all three models, this
being in contrast to the behavior of the model with Gaussian interactions,
where exactly \eta=0.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 16:41:39 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Hartmann",
"A. K.",
""
]
] |
0704.2749 | Wieslaw Dudek | Wieslaw A. Dudek | Remarks to Glazek's results on n-ary groups | 22 pages | Discussiones Math., General Algebra and Applications vol. 27
(2007), 199-233 | null | null | math.HO math.GM | null | It is a survey of the results obtained by K. Glazek's and his co-workers. We
restrict our attention to the problems of axiomatizations of n-ary groups,
classes of n-ary groups, properties of skew elements and homomorphisms induced
by skew elements, constructions of covering groups, classifications and
representations of n-ary groups. Some new results are added too.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 16:47:36 GMT"
}
] | 2007-10-21T00:00:00 | [
[
"Dudek",
"Wieslaw A.",
""
]
] |
0704.2750 | Nikolai Lebovka I | Nikolai Lebovka, Eugene Vorobiev | The kinetics of inactivation of spheroidal microbial cells by pulsed
electric fields | 12 pages, 10 figures | null | null | null | physics.bio-ph | null | The nature of non-exponential kinetics in microbial cells inactivation by
pulsed electric fields (PEF) is discussed. It was demonstrated that possible
mechanism of non-exponential kinetics can be related to orientational disorder
in suspension of microbial cells of anisotropic form. A numerical studies of
spheroidal cell suspensions was carried out. The most pronounced deviations
from the exponential kinetics were observed for disordered suspensions of
prolate spheroids at small electric field strength $E$ or at large aspect ratio
$a$. For partially oriented suspensions, efficiency of inactivation enhances
with increasing of order parameter and field strength. A possibility of the
PEF-induced orientational ordering in microbial suspensions is discussed.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 16:49:47 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Lebovka",
"Nikolai",
""
],
[
"Vorobiev",
"Eugene",
""
]
] |
0704.2751 | Jorge Alfaro | Jorge Alfaro | Quantum Gravity and Maximum Attainable Velocities in the Standard Model | latex, 9 pages, Talk at the VI Silafae, Puerto Vallarta, Mexico,
November 1-8,2006. Added references | AIPConf.Proc.917:161-169,2007 | 10.1063/1.2751953 | null | hep-th | null | A main difficulty in the quantization of the gravitational field is the lack
of experiments that discriminate among the theories proposed to quantize
gravity. Recently we showed that the Standard Model(SM) itself contains tiny
Lorentz invariance violation(LIV) terms coming from QG. All terms depend on one
arbitrary parameter $\alpha$ that set the scale of QG effects. In this talk we
review the LIV for mesons nucleons and leptons and apply it to study several
effects, including the GZK anomaly.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:05:45 GMT"
},
{
"version": "v2",
"created": "Wed, 9 May 2007 16:01:00 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Alfaro",
"Jorge",
""
]
] |
0704.2752 | Premi Chandra | L. Palova, P. Chandra and K.M. Rabe | Modelling Thickness-Dependence of Ferroelectric Thin Film Properties | 13 pages, 17 figures | PRB 76, 014112 (2007) | 10.1103/PhysRevB.76.014112 | null | cond-mat.mtrl-sci | null | We present a segregrated strain model that describes the thickness-dependent
dielectric properties of ferroelectric films. Using a phenomenological Landau
approach, we present results for two specific materials, making comparison with
experiment and with first-principles calculations whenever possible. We also
suggest a "smoking gun" benchtop probe to test our elastic scenario.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:19:56 GMT"
},
{
"version": "v2",
"created": "Sun, 7 Oct 2007 21:39:01 GMT"
}
] | 2007-10-08T00:00:00 | [
[
"Palova",
"L.",
""
],
[
"Chandra",
"P.",
""
],
[
"Rabe",
"K. M.",
""
]
] |
0704.2753 | Dmitry Makarov | A. D. Chernin, I. D. Karachentsev, D. I. Makarov, O. G. Kashibadze, P.
Teerikorpi, M. J. Valtonen, V. P. Dolgachev, L. M. Domozhilova | Local dark energy: HST evidence from the expansion flow around Cen A/M83
galaxy group | null | null | 10.1080/10556790701415393 | null | astro-ph | null | A structure with a massive group in its center and a cool expansion outflow
outside is studied around the Cen A galaxy with the use of the Hubble Space
Telescope observations. It is demonstrated that the dynamics of the flow is
dominated by the antigravity of the dark energy background. The density of dark
energy in the cell is estimated to be near the global cosmological density.
This agrees with our previous result from the neighborhood of the Local group.
A notion of the ``Hubble cell'' is introduced as a building block of the local
structure of the universe.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:06:51 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Chernin",
"A. D.",
""
],
[
"Karachentsev",
"I. D.",
""
],
[
"Makarov",
"D. I.",
""
],
[
"Kashibadze",
"O. G.",
""
],
[
"Teerikorpi",
"P.",
""
],
[
"Valtonen",
"M. J.",
""
],
[
"Dolgachev",
"V. P.",
""
],
[
"Domozhilova",
"L. M.",
""
]
] |
0704.2754 | David Wales | Arjeh M. Cohen, D. A. H. Gijsbers, David B. Wales | Tangle and Brauer Diagram Algebras of Type Dn | 33 pages | null | null | null | math.RT math.GR | null | A generalization of the Kauffman tangle algebra is given for Coxeter type Dn.
The tangles involve a pole or order 2. The algebra is shown to be isomorphic to
the Birman-Murakami-Wenzl algebra of the same type. This result extends the
isomorphism between the two algebras in the classical case, which in our
set-up, occurs when the Coxeter type is of type A with index n-1. The proof
involves a diagrammatic version of the Brauer algebra of type Dn in which the
Temperley-Lieb algebra of type Dn is a subalgebra.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:07:11 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Cohen",
"Arjeh M.",
""
],
[
"Gijsbers",
"D. A. H.",
""
],
[
"Wales",
"David B.",
""
]
] |
0704.2755 | Rafael L\'opez | Rafael L\'opez | Parabolic surfaces in hyperbolic space with constant curvature | 8 pages, 6 figures. This is the text of the talk presented in the
International Congress on Pure and Applied Differential Geometry, PADGE 2007,
10-13 April, 2007. This is a brief of two preprints due to the author and
that appear in the References section | null | null | null | math.DG | null | We study parabolic linear Weingarten surfaces in hyperbolic space
$\rlopezh^3$. In particular, we classify two family of parabolic surfaces:
surfaces with constant Gaussian curvature and surfaces that satisfy the
relation $a\kappa_1+b\kappa_2=c$, where $\kappa_i$ are the principal
curvatures, and $a,b$ and $c$ are constant.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:19:03 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"López",
"Rafael",
""
]
] |
0704.2756 | Mario Gliozzi | M. Gliozzi (1), R.M. Sambruna (2), M. Eracleous (3), T. Yaqoob (4)
((1) Gmu, (2) NASA GSFC, (3) Psu, (4) Jhu, NASA GSFC) | The nature of a broad line radio galaxy: Simultaneous RXTE and Chandra
HETG observations of 3C 382 | 19 pages, 10 figures, 3 tables, accepted for publication in ApJ | Astrophys.J.664:88-100,2007 | 10.1086/518927 | null | astro-ph | null | We present the results from simultaneous chandra and rxte observations of the
X-ray bright Broad-Line Radio Galaxy (BLRG) 3C 382. The long (120 ks) exposure
with chandra HETG allows a detailed study of the soft X-ray continuum and of
the narrow component of the Fe Kalpha line. The rxte PCA data are used to put
an upper limit on the broad line component and constrain the hard X-ray
continuum. A strong soft excess below 1 keV is observed in the time-averaged
HETG spectrum, which can be parameterized with a steep power law or a thermal
model. The flux variability at low energies indicates that the origin of the
soft excess cannot be entirely ascribed to the circumnuclear diffuse emission,
detected by chandra on scales of 20-30 arcsec (22-33 kpc). A narrow (sigma<90
eV) Fe Kalpha line (with EW< 100 eV) is observed by the chandra HEG. Similar
values for the line parameters are measured by the rxte PCA, suggesting that
the contribution from a broad line component is negligible. The fact that the
exposure is split into two observations taken three days apart allows us to
investigate the spectral and temporal evolution of the source on different
timescales. Significant flux variability associated with spectral changes is
observed on timescales of hours and days. The spectral variability is similar
to that observed in radio-quiet AGN ruling out a jet-dominated origin of the
X-rays.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:14:58 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Gliozzi",
"M.",
"",
"Gmu"
],
[
"Sambruna",
"R. M.",
"",
"NASA GSFC"
],
[
"Eracleous",
"M.",
"",
"Psu"
],
[
"Yaqoob",
"T.",
"",
"Jhu, NASA GSFC"
]
] |
0704.2757 | Martin Bruderer | Martin Bruderer, Alexander Klein, Stephen R. Clark, and Dieter Jaksch | Polaron Physics in Optical Lattices | 4 pages, 4 figures | Phys. Rev. A 76, 011605(R) (2007) | 10.1103/PhysRevA.76.011605 | null | quant-ph | null | We investigate the effects of a nearly uniform Bose-Einstein condensate (BEC)
on the properties of immersed trapped impurity atoms. Using a weak-coupling
expansion in the BEC-impurity interaction strength, we derive a model
describing polarons, i.e., impurities dressed by a coherent state of Bogoliubov
phonons, and apply it to ultracold bosonic atoms in an optical lattice. We show
that, with increasing BEC temperature, the transport properties of the
impurities change from coherent to diffusive. Furthermore, stable polaron
clusters are formed via a phonon-mediated off-site attraction.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:16:45 GMT"
},
{
"version": "v2",
"created": "Fri, 20 Jul 2007 14:29:47 GMT"
}
] | 2011-11-09T00:00:00 | [
[
"Bruderer",
"Martin",
""
],
[
"Klein",
"Alexander",
""
],
[
"Clark",
"Stephen R.",
""
],
[
"Jaksch",
"Dieter",
""
]
] |
0704.2758 | M. Swisdak | M. Swisdak and J. F. Drake | The Orientation of the Reconnection X-line | null | null | 10.1029/2007GL029815 | null | physics.space-ph astro-ph | null | We propose a criterion for identifying the orientation of the X-line when two
regions of plasma with arbitrary densities, temperatures, and magnetic fields
undergo reconnection. The X-line points in the direction that maximizes the
(suitably-defined) Alfv\'en speed characterizing the reconnection outflow. For
many situations a good approximation is that the X-line bisects the angle
formed by the magnetic fields.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:17:30 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Swisdak",
"M.",
""
],
[
"Drake",
"J. F.",
""
]
] |
0704.2759 | Nagalakshmi Rao A | Nagalakshmi A. Rao and B. A. Kagali | Spectroscopic investigation of spin zero homonuclear and heteronuclear
molecules | Latex, 11 Pages | null | null | null | quant-ph | null | In the present article, we introduce a model to investigate the energy
spectrum of a relativistic rotor by considering the Klein-Gordon Hamiltonian.
Rotational spectral lines are a signature of homonuclear and heteronuclear
systems and play a key role in understanding diatomic molecules. We show that
the energy-correction term arising due to unequal masses influences the line
separation. Determining the rotational constant enables one to calculate the
moment of inertia and bond length of the molecule.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:18:36 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rao",
"Nagalakshmi A.",
""
],
[
"Kagali",
"B. A.",
""
]
] |
0704.2760 | Krishnendu Sengupta | Subhro Bhattacharjee, Moitri Maiti, and K. Sengupta | Theory of tunneling conductance of graphene NIS junctions | Revised version | Phys Rev B 76 184514 (2007) | 10.1103/PhysRevB.76.184514 | null | cond-mat.mes-hall cond-mat.supr-con | null | We calculate the tunneling conductance of a graphene normal
metal-insulator-superconductor (NIS) junction with a barrier of thickness $d$
and with an arbitrary voltage $V_0$ applied across the barrier region. We
demonstrate that the tunneling conductance of such a NIS junction is an
oscillatory function of both $d$ and $V_0$. We also show that the periodicity
and amplitude of such oscillations deviate from their universal values in the
thin barrier limit as obtained in earlier work [Phys. Rev. Lett. {\bf 97},
217001 (2006)] and become a function of the applied voltage $V_0$. Our results
reproduces the earlier results on tunneling conductance of such junctions in
the thin [Phys. Rev. Lett. {\bf 97}, 217001 (2006)] and zero [Phys. Rev. Lett.
{\bf 97}, 067007 (2006)] barrier limits as special limiting cases. We discuss
experimental relevance of our results.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:27:12 GMT"
},
{
"version": "v2",
"created": "Fri, 18 May 2007 04:58:00 GMT"
},
{
"version": "v3",
"created": "Tue, 9 Oct 2007 13:05:17 GMT"
}
] | 2018-08-29T00:00:00 | [
[
"Bhattacharjee",
"Subhro",
""
],
[
"Maiti",
"Moitri",
""
],
[
"Sengupta",
"K.",
""
]
] |
0704.2761 | Oleg Matveev | O. A. Matveev, A. I. Terent'ev, N. K. Zelenina, V. N. Gus'kov, V. E.
Sedov, A. A. Tomasov, and V. P. Karpenko | Self-Compensation of Conductionin Cd0.95Zn0.05Te:Cl Crystals in a Wide
Range of Cd Vapor Pressures | 5 pages, 2 figures | null | null | null | cond-mat.mtrl-sci | null | The process of self-compensation in Cd0.95Zn0.05Te:Cl solid-solution crystals
has been studied by annealing single crystals under a controlled Cd vapor
pressure, with subsequent measurements of the Hall effect, photoluminescence,
carrier lifetime and mobility, and photocurrent memory in the annealed
crystals. By means of this annealing, conditions of thermal treatment that make
it possible to fabricate low-conductivity samples with a low carrier density,
10E7-10E11 cm-3, are denned. In these samples, a p -- n conduction inversion is
observed at a higher free-carrier density ((n, p) near 10E9 cm-3) and the
dependence of the electron density on the Cd vapor pressure exhibits a more
gentle slope than in the case of CdTe:Cl crystals.
The obtained data are dis-cussed in terms of a self-compensation model in
which intrinsic point defects act as acceptors with deep levels. This level is
attributed to a Zn vacancy, which remains active at high Cd pressure.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:34:57 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Matveev",
"O. A.",
""
],
[
"Terent'ev",
"A. I.",
""
],
[
"Zelenina",
"N. K.",
""
],
[
"Gus'kov",
"V. N.",
""
],
[
"Sedov",
"V. E.",
""
],
[
"Tomasov",
"A. A.",
""
],
[
"Karpenko",
"V. P.",
""
]
] |
0704.2762 | Robert Stencel | D. E. Mais (1), D. Richards (2) and R. E. Stencel (3) ((1) Palomar
Community College, (2) Aberdeen and District Astronomical Society, (3)
University of Denver - Astronomy) | Three Years of Mira Variable CCD Photometry: What Has Been Learned? | 8 pages. Appeared in the Proceedings of the May 2006 Society for
Astronomical Sciences annual conference | null | null | null | astro-ph | null | The subject of micro-variability among Mira stars has received increased
attention since DeLaverny et al. (1998) reported short-term brightness
variations in 15 percent of the 250 Mira or Long Period Variable stars surveyed
using the broadband 340 to 890 nm Hp filter on the HIPPARCOS satellite. The
abrupt variations reported ranged 0.2 to 1.1 magnitudes, on time-scales between
2 to 100 hours, with a preponderance found nearer Mira minimum light phases.
However, the HIPPARCOS sampling frequency was extremely sparse and required
confirmation because of potentially important atmospheric dynamics and
dust-formation physics that could be revealed. We report on Mira light curve
sub-structure based on new CCD V and R band data, augmenting the known light
curves of Hipparcos-selected long period variables [LPVs], and interpret same
in terms of [1] interior structure, [2] atmospheric structure change, and/or
[3] formation of circumstellar [CS] structure. We propose that the alleged
micro-variability among Miras is largely undersampled, transient overtone
pulsation structure in the light curves.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:40:27 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mais",
"D. E.",
""
],
[
"Richards",
"D.",
""
],
[
"Stencel",
"R. E.",
""
]
] |
0704.2763 | Ian Hambleton | Ian Hambleton and Jean-Claude Hausmann | Equivariant Bundles and Isotropy Representations | Final version: to appear in "Groups, Geometry and Dynamics" | Groups Geom. Dyn. 4 (2010), no. 1, 127--162 | null | null | math.GT math.AT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce a new construction, the isotropy groupoid, to organize the orbit
data for split $\Gamma$-spaces. We show that equivariant principal $G$-bundles
over split $\Gamma$-CW complexes $X$ can be effectively classified by means of
representations of their isotropy groupoids. For instance, if the quotient
complex $A=\Gamma\backslash X$ is a graph, with all edge stabilizers toral
subgroups of $\Gamma$, we obtain a purely combinatorial classification of
bundles with structural group $G$ a compact connected Lie group. If $G$ is
abelian, our approach gives combinatorial and geometric descriptions of some
results of Lashof-May-Segal and Goresky-Kottwitz-MacPherson.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:41:49 GMT"
},
{
"version": "v2",
"created": "Sun, 21 Jun 2009 11:30:41 GMT"
}
] | 2013-02-12T00:00:00 | [
[
"Hambleton",
"Ian",
""
],
[
"Hausmann",
"Jean-Claude",
""
]
] |
0704.2764 | Apolodor Aristotel Raduta | A. A. Raduta and F. D. Aaron | A simple description of the states $0^+$ and $2^+$ in $^{168}Er$ | 9 pages, 5 figures | J.Phys.G34:2053-2062,2007 | 10.1088/0954-3899/34/9/014 | null | nucl-th | null | A sixth-order quadrupole boson Hamiltonian is used to describe 26 states
$0^+$ and 67 states $2^+$ which have been recently identified in $^{168}Er$.
Two closed expressions are alternatively used for energy levels. One
corresponds to a semi-classical approach while the other one represents the
exact eigenvalue of the model Hamiltonian. The semi-classical expression
involves four parameters, while the exact eigenvalue is determined by five
parameters. In each of the two descriptions a least square fit procedure is
adopted.
Both expressions provide a surprisingly good agreement with the experimental
data.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 17:49:51 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Raduta",
"A. A.",
""
],
[
"Aaron",
"F. D.",
""
]
] |
0704.2765 | Bertrand Georgeot | O. Giraud, J. Martin and B. Georgeot | Entanglement of localized states | 6 pages, 4 figures | Phys. Rev. A 76, 042333 (2007) | 10.1103/PhysRevA.76.042333 | null | quant-ph cond-mat.mes-hall nlin.CD | null | We derive exact expressions for the mean value of Meyer-Wallach entanglement
Q for localized random vectors drawn from various ensembles corresponding to
different physical situations. For vectors localized on a randomly chosen
subset of the basis, <Q> tends for large system sizes to a constant which
depends on the participation ratio, whereas for vectors localized on adjacent
basis states it goes to zero as a constant over the number of qubits.
Applications to many-body systems and Anderson localization are discussed.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 18:01:04 GMT"
},
{
"version": "v2",
"created": "Fri, 26 Oct 2007 14:10:08 GMT"
}
] | 2011-11-09T00:00:00 | [
[
"Giraud",
"O.",
""
],
[
"Martin",
"J.",
""
],
[
"Georgeot",
"B.",
""
]
] |
0704.2766 | Pamela Morehouse | R.A. Briere, et al. (CLEO Collaboration) | Comparison of Particle Production in Quark and Gluon Fragmentation at
sqrt s ~ 10 GeV | 21 pages postscript,also available through
http://www.lns.cornell.edu/public/CLNS/2006/, Submitted to PRD | Phys.Rev.D76:012005,2007 | 10.1103/PhysRevD.76.012005 | CLNS 06/1984, CLEO 06-24 | hep-ex | null | Using data collected with the CLEO III detector at the Cornell Electron
Storage Ring, we study the inclusive production of baryons/antibaryons (p, /)
and mesons (phi and f_2(1270)) in gluon-fragmentation and quark-fragmentation
processes. We first corroborate previous per-event total particle yields in
Upsilon(1S)->ggg compared with nearby continuum (e+e- -> qqbar) indicating
greater (x2) per-event yields of baryons in 3-gluon fragmentation. We find
similar results when we extend that comparison to include the Upsilon(2S) and
Upsilon(3S) resonances. With higher statistics, we now also probe the momentum
dependence of these per-event particle yields. Next, we compare particle
production in the photon-tagged process Upsilon(1S)->gggamma with that in e+e-
-> qqbar events, to allow comparison of two-parton with three-parton
particle-specific fragmentation. For each particle, we determine the
`enhancement' ratio, defined as the ratio of particle yields per gluon
fragmentation event compared to quark fragmentation event. Thus defined, an
enhancement of 1.0 implies equal per-event production in both gluon and quark
fragmentation. In the photon-tagged analysis (U(1S)->gggamma compared to e+e-
-> qqbar+gamma), we find almost no enhancement for protons (1.2+/-0.1), but a
significant enhancement (1.9+/-0.3) for /\'s. Overall, per-event baryon
production in radiative two-gluon fragmentation is somewhat smaller than that
observed in three-gluon decays of the Upsilon(1S). Our results for baryon
production are inconsistent with the predictions of the JETSET (7.3)
fragmentation model.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 18:16:41 GMT"
}
] | 2019-08-12T00:00:00 | [
[
"Briere",
"R. A.",
""
]
] |
0704.2767 | Qizhou Zhang Dr. | Qizhou Zhang, T. K. Sridharan, Todd R. Hunter, Yuan Chen, Henrik
Beuther and Friedrich Wyrowski | A Jet-like Outflow toward the High-Mass (Proto)stellar Object IRAS
18566+0408 | 19 pages, 9 figures. Accepted for publication in Astronomy and
Astrophysics | null | 10.1051/0004-6361:20077094 | null | astro-ph | null | We performed interferometric observations of a high-mass protostellar
candidate IRAS 18566+0408 in the \nh3 (J,K)=(1,1), (2,2) and (3,3) inversion
transitions, the SiO J=2-1 and HCN J=1-0 lines, and the 43 and 87 GHz continuum
emission using the VLA and OVRO. The 87 GHz continuum emission reveals two
continuum peaks MM-1 and MM-2 along a molecular ridge. The dominant peak MM-1
coincides with a compact emission feature at 43 GHz, and arises mostly from the
dust emission. For dust emissivity index $\beta$ of 1.3, the masses in the dust
peaks amount to 70 \msun for MM-1, and 27 \msun for MM-2. Assuming internal
heating, the central luminosities of MM-1 and MM-2 are $6 \times 10^4$ and $8
\times 10^3$ \lsun, respectively.
The SiO emission reveals a well collimated outflow emanating from MM-1. The
jet-like outflow is also detected in \nh3 at velocities similar to the SiO
emission. The outflow, with a mass of 27 \msun, causes significant heating in
the gas to temperatures of 70 K, much higher than the temperature of $\lsim 15$
K in the extended core. Compact ($< 3''$) and narrow line ($<1.5$ \kms-1) \nh3
(3,3) emission features are found associated with the outflow. They likely
arise from weak population inversion in \nh3 similar to the maser emission.
Toward MM-1, there is a compact \nh3 structure with a linewidth that
increases from 5.5 \kms-1 FHWM measured at 3$''$ resolution to 8.7 \kms-1\
measured at 1$''$ resolution. This linewidth is much larger than the FWHM of
$<$ 2 \kms-1 in the entire core, and does not appear to originate from the
outflow. This large linewidth may arise from rotation/infall, or relative
motions of unresolved protostellar cores.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 18:20:00 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Zhang",
"Qizhou",
""
],
[
"Sridharan",
"T. K.",
""
],
[
"Hunter",
"Todd R.",
""
],
[
"Chen",
"Yuan",
""
],
[
"Beuther",
"Henrik",
""
],
[
"Wyrowski",
"Friedrich",
""
]
] |
0704.2768 | Andrew Raich | Andrew Raich | Heat Equations and the Weighted $\bar\partial$-Problem | v5. 33 pages. Cleaned up the statements of the results, improved
Theorem 4.4 and Theorem 7.3 | Commun. Pure Appl. Anal. 11(3):885-909, 2012 | null | null | math.AP math.CV | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The purpose of this article is to establish regularity and pointwise upper
bounds for the (relative) fundamental solution of the heat equation associated
to the weighted dbar-operator in $L^2(C^n)$ for a certain class of weights. The
weights depend on a parameter, and we find pointwise bounds for heat kernel, as
well as its derivatives in time, space, and the parameter. We also prove
cancellation conditions for the heat semigroup. We reduce the $n$-dimensional
case to the one-dimensional case, and the estimates in one-dimensional case are
achieved by Duhamel's principle and commutator properties of the operators. As
an application, we recover estimates of heat kernels on polynomial models in
$C^2$.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 18:20:16 GMT"
},
{
"version": "v2",
"created": "Mon, 21 Jan 2008 22:27:47 GMT"
},
{
"version": "v3",
"created": "Fri, 10 Jul 2009 16:45:25 GMT"
},
{
"version": "v4",
"created": "Tue, 17 Nov 2009 19:23:51 GMT"
},
{
"version": "v5",
"created": "Fri, 20 Nov 2009 14:08:47 GMT"
}
] | 2012-08-13T00:00:00 | [
[
"Raich",
"Andrew",
""
]
] |
0704.2769 | Juan Antonio Nieto | J. A. Nieto | Towards a Background Independent Quantum Gravity in Eight Dimensions | 27 pages, Latex,some improvements introduced, typos corrected | null | null | null | hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We start a program of background independent quantum gravity in eight
dimensions. We begin by considering canonical gravity \textit{a la}
"Kaluza-Klein" in $D=d+1$ dimensions. We show that our canonical gravity
approach can be applied to the case of self-dual gravity in four dimensions.
Further, by using our previously proposed classical action of Ashtekar
self-dual gravity formalism in eight dimensions, we proceed to develop the
canonical approach in eight dimensions. Our construction considers different
SO(8) symmetry breakings. In particular, the breaking $SO(8)=S_{R}^{7}% \times
S_{L}^{7}\times G_{2}$ plays an important role in our discussion.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 18:22:04 GMT"
},
{
"version": "v2",
"created": "Fri, 31 Aug 2007 23:53:43 GMT"
},
{
"version": "v3",
"created": "Mon, 27 Oct 2008 19:55:52 GMT"
}
] | 2008-10-27T00:00:00 | [
[
"Nieto",
"J. A.",
""
]
] |
0704.2770 | Pavel Exner | Pavel Exner and Martin Fraas | A remark on helical waveguides | LaTeX, 12 pages | Phys. Lett. A369 (2007), 393-399 | 10.1016/j.physleta.2007.05.013 | null | quant-ph cond-mat.mes-hall math-ph math.MP | null | Motivated by a proposal to create an optical helix-shaped waveguides for cold
atoms and molecules, we discuss local perturbations which can create bound
states in such a setting. This is known about a local slowdown of the twist; we
show that a similar effect can result from a local tube protrusion or a change
of the helix radius in correlation with its pitch angle.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 18:27:23 GMT"
}
] | 2019-12-10T00:00:00 | [
[
"Exner",
"Pavel",
""
],
[
"Fraas",
"Martin",
""
]
] |
0704.2771 | Mitja Mastnak | Mitja Mastnak, Sarah Witherspoon | Bialgebra cohomology, pointed Hopf algebras, and deformations | Cohomological results in the paper were significantly improved and
generalized. See new abstract for details | null | null | null | math.RA math.QA | null | We give explicit formulas for maps in a long exact sequence connecting
bialgebra cohomology to Hochschild cohomology. We give a sufficient condition
for the connecting homomorphism to be surjective. We apply these results to
compute all bialgebra two-cocycles of certain Radford biproducts
(bosonizations). These two-cocycles are precisely those associated to the
finite dimensional pointed Hopf algebras in the recent classification of
Andruskiewitsch and Schneider, in an interpretation of these Hopf algebras as
graded bialgebra deformations of Radford biproducts.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 18:27:46 GMT"
},
{
"version": "v2",
"created": "Sun, 11 May 2008 23:58:45 GMT"
}
] | 2008-05-12T00:00:00 | [
[
"Mastnak",
"Mitja",
""
],
[
"Witherspoon",
"Sarah",
""
]
] |
0704.2772 | John Freeland | J.W. Freeland, J. Chakhalian, G. Cristiani, H.-U. Habermeier, and B.
Keimer | On Magnetic Interlayer Coupling and Proximity Effect in a
La$_{0.67}$Ca$_{0.33}$MnO$_3$(10 nm)/YBa$_2$Cu$_3$O$_7$(10 nm) Superlattice | 4 pages, submitted to Applied Physics Letters | null | 10.1063/1.2747678 | null | cond-mat.str-el cond-mat.mtrl-sci | null | We present a study of interlayer coupling and proximity effects in a
La$_{0.66}$Ca$_{0.33}$MnO$_3$(10 nm)/YBa$_2$Cu$_3$O$_7$(10 nm) superlattice.
Using element-sensitive x-ray probes, the magnetic state of Mn can be probed
without seeing the strong diamagnetism of the superconductor, which makes this
approach ideal to study changes in the magnetic properties across the
superconducting transition. By a combined experiment using {\it in situ}
transport measurements during polarized soft x-ray measurements, we were able
to see no noticeable influence of the superconducting state on the magnetic
properties and no evidence for magnetic coupling across a 10 nm YBCO layer.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 18:36:00 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Freeland",
"J. W.",
""
],
[
"Chakhalian",
"J.",
""
],
[
"Cristiani",
"G.",
""
],
[
"Habermeier",
"H. -U.",
""
],
[
"Keimer",
"B.",
""
]
] |
0704.2773 | Pamela Morehouse | J.L Rosner, et al, CLEO Collaboration | Measurement of Upper Limits for Upsilon --> gamma + R Decays | 15 pages postscript,also available through
http://www.lns.cornell.edu/public/CLNS/2006/, Submitted to PRD | Phys.Rev.D76:117102,2007 | 10.1103/PhysRevD.76.117102 | CLNS 06/1981, CLEO 06-21 | hep-ex | null | Motivated by concerns regarding possible two-body contributions to the
recently-measured inclusive Upsilon(nS)->gamma+X (n=1, 2, 3) direct photon
spectra, we report on a new study of exclusive radiative decays of these narrow
Upsilon(nS) resonances into two-body final states R+gamma, with R a narrow
resonant hadronic state decaying into four or more charged particles. Such
two-body processes are not explicitly addressed in the extant theoretical
frameworks used to calculate the inclusive direct photon spectra, and must also
be explicitly inserted into Monte Carlo simulations. Using data collected from
the CLEO III detector at the Cornell Electron Storage Ring, we present upper
limits of order 0.01 per cent for such bottomonium two-body decays as a
function of the R recoil mass.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 18:37:13 GMT"
}
] | 2010-04-08T00:00:00 | [
[
"Rosner",
"J. L",
""
],
[
"Collaboration",
"CLEO",
""
]
] |
0704.2774 | Jonathan Rosner | Jonathan L. Rosner | Moriond QCD 2007 - Theory Summary | 18 pages, 4 figures, XLII Rencontres de Moriond, La Thuile, Italy,
17-24 March 2007. References added; corrections to text and format | null | null | EFI 07-10 | hep-ph hep-ex | null | Developments reported at the 2007 Moriond Workshop on QCD and Hadronic
Interactions are reviewed and placed in a theoretical context.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 18:43:10 GMT"
},
{
"version": "v2",
"created": "Mon, 30 Apr 2007 19:38:08 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rosner",
"Jonathan L.",
""
]
] |
0704.2775 | Pierre Dreyfuss | Pierre Dreyfuss (IECN) | Results for a turbulent system with unbounded viscosities: weak
formulations, existence of solutions, boundedness, smoothness' | null | Nonlinear Analysis: Theory, Methods, and Applications (2007)
online publication: 10 January 2007 | 10.1016/j.na.2006.12.040 | null | math.AP | null | We consider a circulation system arising in turbulence modelling in fluid
dynamics with unbounded eddy viscosities. Various notions of weak solutions are
considered and compared. We establish existence and regularity results. In
particular we study the boundedness of weak solutions. We also establish an
existence result for a classical solution
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 19:12:23 GMT"
}
] | 2007-10-03T00:00:00 | [
[
"Dreyfuss",
"Pierre",
"",
"IECN"
]
] |
0704.2776 | Thomas Krantz | Thomas Krantz (IECN, Urmul) | Holonomy representations which are a diagonal direct sum of two faithful
representations | null | null | null | null | math.RT | null | We study holonomy representations admitting a pair of supplementary faithful
sub-representations. In particular the cases where the sub-representations are
isomorphic respectively dual to each other are treated. In each case we have a
closer look at the classification in small dimension.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 19:12:51 GMT"
},
{
"version": "v2",
"created": "Tue, 15 May 2007 09:46:33 GMT"
},
{
"version": "v3",
"created": "Thu, 21 Feb 2008 13:16:23 GMT"
}
] | 2008-02-21T00:00:00 | [
[
"Krantz",
"Thomas",
"",
"IECN, Urmul"
]
] |
0704.2777 | Thomas Krantz | Lionel B\'erard Bergery (IECN), Thomas Krantz (IECN) | Representations admitting two pairs of supplementary invariant spaces | null | null | null | null | math.RT | null | We examine the lattice generated by two pairs of supplementary vector
subspaces of a finite-dimensional vector space by intersection and sum, with
the aim of applying the results to the study of representations admitting two
pairs of supplementary invariant spaces, or one pair and a reflexive form. We
show that such a representation is a direct sum of three canonical
sub-representations which we characterize. We then focus on holonomy
representations with the same property.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 19:15:46 GMT"
},
{
"version": "v2",
"created": "Thu, 21 Feb 2008 10:51:19 GMT"
}
] | 2008-02-21T00:00:00 | [
[
"Bergery",
"Lionel Bérard",
"",
"IECN"
],
[
"Krantz",
"Thomas",
"",
"IECN"
]
] |
0704.2778 | Brooke Shrader | Brooke Shrader and Anthony Ephremides | Random Access Broadcast: Stability and Throughput Analysis | 19 pages, 5 figures. Submitted as correspondence to IEEE Transactions
on Information Theory, Sept 2006. Revised April 2007 | IEEE Transactions on Information Theory, vol. 53, no. 8, pp.
2915-2921, August 2007. | null | null | cs.IT math.IT | null | A wireless network in which packets are broadcast to a group of receivers
through use of a random access protocol is considered in this work. The
relation to previous work on networks of interacting queues is discussed and
subsequently, the stability and throughput regions of the system are analyzed
and presented. A simple network of two source nodes and two destination nodes
is considered first. The broadcast service process is analyzed assuming a
channel that allows for packet capture and multipacket reception. In this small
network, the stability and throughput regions are observed to coincide. The
same problem for a network with N sources and M destinations is considered
next. The channel model is simplified in that multipacket reception is no
longer permitted. Bounds on the stability region are developed using the
concept of stability rank and the throughput region of the system is compared
to the bounds. Our results show that as the number of destination nodes
increases, the stability and throughput regions diminish. Additionally, a
previous conjecture that the stability and throughput regions coincide for a
network of arbitrarily many sources is supported for a broadcast scenario by
the results presented in this work.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 19:17:43 GMT"
}
] | 2007-11-05T00:00:00 | [
[
"Shrader",
"Brooke",
""
],
[
"Ephremides",
"Anthony",
""
]
] |
0704.2779 | J D | Jonas Dieckelmann | The Complexity of Simple Stochastic Games | Hi, while reading through literature i noticed that it has not yet
been proved that computing the value vector of simple stochastic games is a
Problem in FNP. This is why i came up with a prove in this seminar work of
mine | null | null | null | cs.CC cs.GT | null | In this paper we survey the computational time complexity of assorted simple
stochastic game problems, and we give an overview of the best known algorithms
associated with each problem.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 19:51:36 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Dieckelmann",
"Jonas",
""
]
] |
0704.2780 | Robert Fesen | Gwen C. Rudie and Robert A. Fesen (Department of Physics and
Astronomy, Dartmouth College) | Evidence for Pre-SN Mass Loss in the Galactic SNR 3C 58 | To appear in "Circumstellar Media and Late Stages of Massive Stellar
Evolution" Rev Mex AA (SC) | null | null | null | astro-ph | null | We discuss the findings of a comprehensive imaging and spectroscopic survey
of the optical emission associated with the supernova remnant 3C 58 (Fesen et
al. 2007) as they relate to the topic of pre-SN mass loss. Spectroscopically
measured radial velocities of ~450 emission knots within the remnant show two
distinct kinematic populations of optical knots: a high-velocity group with
radial velocities in the range of 700 - 1100 km/s and a lower velocity group
exhibiting radial expansion velocities below ~250 km/s. We interpret the
high-velocity knots as ejecta from the SN explosion and the low-velocity knots
as shocked circumstellar material likely resulting from pre-SN mass loss. The
chemical signatures of the two populations also show marked differences. The
high velocity group includes a substantial number of knots with notably higher
[N II]/H-alpha ratios not seen in the lower velocity population, suggesting
greater nitrogen enrichment in the SN ejecta than in the CSM. These results are
compared with evidence for pre-SN mass loss in the Crab Nebula, perhaps the SNR
most similar to 3C 58. These SNRs may comprise two case studies of pre-SN mass
loss in relatively low mass (~8 - 10 solar masses) core-collapse SN
progenitors.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 19:42:37 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rudie",
"Gwen C.",
"",
"Department of Physics and\n Astronomy, Dartmouth College"
],
[
"Fesen",
"Robert A.",
"",
"Department of Physics and\n Astronomy, Dartmouth College"
]
] |
0704.2781 | Vladimir Karas | V. Karas, L. Subr | Enhanced activity of massive black holes by stellar capture assisted by
a self-gravitating accretion disc | 10 pages, 5 figures; Astronomy & Astrophysics accepted | Astronomy and Astrophysics 470 (2007) 11-19 | 10.1051/0004-6361:20066068 | null | astro-ph | null | We study the probability of close encounters between stars from a nuclear
cluster and a massive black hole. The gravitational field of the system is
dominated by the black hole in its sphere of influence. It is further modified
by the cluster mean field (a spherical term) and a gaseous disc/torus (an
axially symmetric term) causing a secular evolution of stellar orbits via Kozai
oscillations. Intermittent phases of large eccentricity increase the chance
that stars become damaged inside the tidal radius of the central hole. Such
events can produce debris and lead to recurring episodes of enhanced accretion
activity. We introduce an effective loss cone and associate it with tidal
disruptions during the high-eccentricity phases of the Kozai cycle. By
numerical integration of the trajectories forming the boundary of the loss cone
we determine its shape and volume. We also include the effect of relativistic
advance of pericentre. The potential of the disc has the efffect of enlarging
the loss cone and, therefore, the predicted number of tidally disrupted stars
should grow by factor of ~10^2. On the other hand, the effect of the cluster
mean potential together with the relativistic pericentre advance act against
the eccentricity oscillations. In the end we expect the tidal disruption events
to be approximately ten times more frequent in comparison with the model in
which the three effects -- the cluster mean field, the relativistic pericentre
advance, and the Kozai mechanism -- are all ignored. The competition of
different influences suppresses the predicted star disruption rate as the black
hole mass increases. Hence, the process under consideration is more important
for intermediate-mass black holes, M_bh~10^4M_s.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 20:02:45 GMT"
}
] | 2007-08-23T00:00:00 | [
[
"Karas",
"V.",
""
],
[
"Subr",
"L.",
""
]
] |
0704.2782 | Robert Schmunk | P.A. Kharecha, J.E. Hansen (NASA GISS and Columbia Univ. Earth
Institute) | Implications of "peak oil" for atmospheric CO2 and climate | (22 pages, 7 figures; final version accepted by Global Biogeochemical
Cycles) | Publ. in Global Biogeochem. Cycles, 22, GB3012 (2008) | 10.1029/2007GB003142 | null | physics.ao-ph | null | Unconstrained CO2 emission from fossil fuel burning has been the dominant
cause of observed anthropogenic global warming. The amounts of "proven" and
potential fossil fuel reserves are uncertain and debated. Regardless of the
true values, society has flexibility in the degree to which it chooses to
exploit these reserves, especially unconventional fossil fuels and those
located in extreme or pristine environments. If conventional oil production
peaks within the next few decades, it may have a large effect on future
atmospheric CO2 and climate change, depending upon subsequent energy choices.
Assuming that proven oil and gas reserves do not greatly exceed estimates of
the Energy Information Administration, and recent trends are toward lower
estimates, we show that it is feasible to keep atmospheric CO2 from exceeding
about 450 ppm by 2100, provided that emissions from coal, unconventional fossil
fuels, and land use are constrained. Coal-fired power plants without
sequestration must be phased out before mid-century to achieve this CO2 limit.
It is also important to "stretch" conventional oil reserves via energy
conservation and efficiency, thus averting strong pressures to extract liquid
fuels from coal or unconventional fossil fuels while clean technologies are
being developed for the era "beyond fossil fuels". We argue that a rising price
on carbon emissions is needed to discourage conversion of the vast fossil
resources into usable reserves, and to keep CO2 beneath the 450 ppm ceiling.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 20:03:07 GMT"
},
{
"version": "v2",
"created": "Wed, 14 Nov 2007 01:17:55 GMT"
},
{
"version": "v3",
"created": "Mon, 17 Mar 2008 21:16:53 GMT"
}
] | 2008-08-04T00:00:00 | [
[
"Kharecha",
"P. A.",
"",
"NASA GISS and Columbia Univ. Earth\n Institute"
],
[
"Hansen",
"J. E.",
"",
"NASA GISS and Columbia Univ. Earth\n Institute"
]
] |
0704.2783 | Hector Crocce | M. Crocce, R. Scoccimarro | Nonlinear Evolution of Baryon Acoustic Oscillations | 18 pages, 8 figures, submitted to Phys. Rev. D. v2: We show that
mode-coupling introduces out of phase oscillations that lead to shifts in the
power spectrum nodes in the method of arXiv:0705.3323 | Phys.Rev.D77:023533,2008 | 10.1103/PhysRevD.77.023533 | null | astro-ph | null | We study the nonlinear evolution of the baryon acoustic oscillations (BAO) in
the dark matter power spectrum and correlation function using renormalized
perturbation theory (RPT). In a previous paper we showed that RPT successfully
predicts the damping of acoustic oscillations; here we extend our calculation
to the enhancement of power due to mode-coupling. We show that mode-coupling
generates additional oscillations that are out of phase with those in the
linear spectrum, leading to shifts in the scales of oscillation nodes defined
with respect to a smooth spectrum. When Fourier transformed, these out of phase
oscillations induce percent-level shifts in the acoustic peak of the two-point
correlation function. We present predictions for these shifts as a function of
redshift; these should be considered as a robust lower limit to the more
realistic case that includes in addition redshift distortions and galaxy bias.
We show that these nonlinear effects occur at very large scales, leading to a
breakdown of linear theory at scales much larger than commonly thought. We
discuss why virialized halo profiles are not responsible for these effects,
which can be understood from basic physics of gravitational instability. Our
results are in excellent agreement with numerical simulations, and can be used
as a starting point for modeling BAO in future observations. To meet this end,
we suggest a simple physically motivated model to correct for the shifts caused
by mode-coupling.
| [
{
"version": "v1",
"created": "Mon, 23 Apr 2007 19:40:37 GMT"
},
{
"version": "v2",
"created": "Tue, 6 Nov 2007 15:54:36 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Crocce",
"M.",
""
],
[
"Scoccimarro",
"R.",
""
]
] |
0704.2784 | Ted Ashton | Ted Ashton | Exploring Continuous Tensegrities | 165 pages, 65 figures, dissertation; replaced proof of Prop. 3.7.20 | null | null | null | math.MG | null | A discrete tensegrity framework can be thought of as a graph in Euclidean
n-space where each edge is of one of three types: an edge with a fixed length
(bar) or an edge with an upper (cable) or lower (strut) bound on its length.
Roth and Whiteley, in their 1981 paper "Tensegrity Frameworks", showed that in
certain cases, the struts and cables can be replaced with bars when analyzing
the framework for infinitesimal rigidity. In that case we call the tensegrity
"bar equivalent". In specific, they showed that if there exists a set of
positive weights, called a positive "stress", on the edges such that the
weighted sum of the edge vectors is zero at every vertex, then the tensegrity
is bar equivalent.
In this paper we consider an extended version of the tensegrity framework in
which the vertex set is a (possibly infinite) set of points in Euclidean
n-space and the edgeset is a compact set of unordered pairs of vertices. These
are called "continuous tensegrities". We show that if a continuous tensegrity
has a strictly positive stress, it is bar equivalent and that it has a
semipositive stress if and only if it is partially bar equivalent. We also show
that if a tensegrity is minimally bar equivalent (it is bar equivalent but
removing any open set of edges makes it no longer so), then it has a strictly
positive stress.
In particular, we examine the case where the vertices form a rectifiable
curve and the possible motions of the curve are limited to local isometries of
it. Our methods provide an attractive proof of the following result: There is
no locally arclength preserving motion of a circle that increases any antipodal
distance without decreasing some other one.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 20:10:02 GMT"
},
{
"version": "v2",
"created": "Mon, 14 May 2007 23:25:18 GMT"
}
] | 2009-09-29T00:00:00 | [
[
"Ashton",
"Ted",
""
]
] |
0704.2785 | Fumihiro Takayama | Fumihiro Takayama | Extremely Long-Lived Charged Massive Particles as A Probe for Reheating
of the Universe | 7 pages, 2 figures, published in Physical Review D | Phys.Rev.D77:116003,2008 | 10.1103/PhysRevD.77.116003 | null | hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the impact of charged massive particle big bang
nucleosynthesis(CBBN) to explore the nature of the reheating of the Universe in
the case that a new extremely long-lived charged massive particle(CHAMP)
exists. If the mass of the CHAMP is within collider reach and it's lifetime is
longer than $10^4$sec, the comparison between the CBBN prediction and observed
$^6$Li abundances may indicate nonstandard reheating in the early Universe
without relying on details of the decay properties. Even if the CHAMP mass is
outside the reach of colliders, the cosmological considerations may provide a
nontrivial hint for the existence of such very heavy long-lived CHAMPs from the
late Universe if the daughter particles are the dominant component of the
present dark matter. We consider a low reheating temperature model as an
example of the nonstandard reheating scenarios.
| [
{
"version": "v1",
"created": "Mon, 23 Apr 2007 17:34:56 GMT"
},
{
"version": "v2",
"created": "Mon, 30 Apr 2007 16:40:45 GMT"
},
{
"version": "v3",
"created": "Sat, 5 May 2007 09:00:58 GMT"
},
{
"version": "v4",
"created": "Mon, 27 Aug 2007 18:44:51 GMT"
},
{
"version": "v5",
"created": "Tue, 17 Jun 2008 17:56:25 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Takayama",
"Fumihiro",
""
]
] |
0704.2786 | Wenyi Zhang | Wenyi Zhang, Shivaprasad Kotagiri, and J. Nicholas Laneman | Writing on Dirty Paper with Resizing and its Application to Quasi-Static
Fading Broadcast Channels | To appear in IEEE International Symposium on Information Theory 2007 | null | 10.1109/ISIT.2007.4557255 | null | cs.IT math.IT | null | This paper studies a variant of the classical problem of ``writing on dirty
paper'' in which the sum of the input and the interference, or dirt, is
multiplied by a random variable that models resizing, known to the decoder but
not to the encoder. The achievable rate of Costa's dirty paper coding (DPC)
scheme is calculated and compared to the case of the decoder's also knowing the
dirt. In the ergodic case, the corresponding rate loss vanishes asymptotically
in the limits of both high and low signal-to-noise ratio (SNR), and is small at
all finite SNR for typical distributions like Rayleigh, Rician, and Nakagami.
In the quasi-static case, the DPC scheme is lossless at all SNR in terms of
outage probability. Quasi-static fading broadcast channels (BC) without
transmit channel state information (CSI) are investigated as an application of
the robustness properties. It is shown that the DPC scheme leads to an outage
achievable rate region that strictly dominates that of time division.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 20:29:32 GMT"
}
] | 2016-11-17T00:00:00 | [
[
"Zhang",
"Wenyi",
""
],
[
"Kotagiri",
"Shivaprasad",
""
],
[
"Laneman",
"J. Nicholas",
""
]
] |
0704.2787 | Cristiano Dias Mr. | Cristiano L. Dias, Tapio Ala-Nissila, Mikko Karttunen, Ilpo
Vattulainen and Martin Grant | Microscopic mechanism for cold denaturation | null | null | 10.1103/PhysRevLett.100.118101 | null | cond-mat.soft | null | We elucidate the mechanism of cold denaturation through constant-pressure
simulations for a model of hydrophobic molecules in an explicit solvent. We
find that the temperature dependence of the hydrophobic effect is the driving
force/induces/facilitates cold denaturation. The physical mechanism underlying
this phenomenon is identified as the destabilization of hydrophobic contact in
favor of solvent separated configurations, the same mechanism seen in pressure
induced denaturation. A phenomenological explanation proposed for the mechanism
is suggested as being responsible for cold denaturation in real proteins.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 20:33:59 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Dias",
"Cristiano L.",
""
],
[
"Ala-Nissila",
"Tapio",
""
],
[
"Karttunen",
"Mikko",
""
],
[
"Vattulainen",
"Ilpo",
""
],
[
"Grant",
"Martin",
""
]
] |
0704.2788 | Michael Ibison | M. Ibison | On the Conformal forms of the Robertson-Walker metric | Historical review added. Accepted by J. Math. Phys | J.Math.Phys.48:122501,2007 | 10.1063/1.2815811 | null | gr-qc | null | All possible transformations from the Robertson-Walker metric to those
conformal to the Lorentz-Minkowski form are derived. It is demonstrated that
the commonly known family of transformations and associated conformal factors
are not exhaustive and that there exists another relatively less well known
family of transformations with a different conformal factor in the particular
case that K = -1. Simplified conformal factors are derived for the special case
of maximally-symmetric spacetimes. The full set of all possible
cosmologically-compatible conformal forms is presented as a comprehensive
table. A product of the analysis is the determination of the set-theoretical
relationships between the maximally symmetric spacetimes, the Robertson-Walker
spacetimes, and functionally more general spacetimes. The analysis is preceded
by a short historical review of the application of conformal metrics to
Cosmology.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 20:38:48 GMT"
},
{
"version": "v2",
"created": "Thu, 25 Oct 2007 22:29:46 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Ibison",
"M.",
""
]
] |
0704.2789 | Alexei Poltoratski | Evgeny Abakumov and Alexei Poltoratski | Pseudocontinuation and cyclicity for random power series | null | null | null | null | math.CV | null | We prove that a random function in the Hardy space $H^2$ is a non-cyclic
vector for the backward shift operator almost surely. The question of existence
of a local pseudocontinuation for a random analytic function is also studied.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 20:52:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Abakumov",
"Evgeny",
""
],
[
"Poltoratski",
"Alexei",
""
]
] |
0704.2790 | Meta van Faassen | Meta van Faassen, Adam Wasserman, Eberhard Engel, Fan Zhang, and
Kieron Burke | Time-dependent Density Functional calculation of e-H scattering | 5 pages, 4 figures, 1 table | null | 10.1103/PhysRevLett.99.043005 | null | cond-mat.mtrl-sci | null | Phase shifts for single-channel elastic electron-atom scattering are derived
from time-dependent density functional theory. The H$^-$ ion is placed in a
spherical box, its discrete spectrum found, and phase shifts deduced.
Exact-exchange yields an excellent approximation to the ground-state Kohn-Sham
potential, while the adiabatic local density approximation yields good singlet
and triplet phase shifts.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 20:56:07 GMT"
},
{
"version": "v2",
"created": "Wed, 11 Jul 2007 14:32:26 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"van Faassen",
"Meta",
""
],
[
"Wasserman",
"Adam",
""
],
[
"Engel",
"Eberhard",
""
],
[
"Zhang",
"Fan",
""
],
[
"Burke",
"Kieron",
""
]
] |
0704.2791 | William Sumner | W. Q. Sumner and D. Y. Sumner | Coevolution of Quantum Wave Functions and the Friedmann Universe | 8 pages | Nauka i Obrazovanie 4:113-116,2000 | null | null | physics.gen-ph | null | Erwin Schrodinger (1939) proved that quantum wave functions coevolve with the
curved spacetime of the Friedmann universe. Schrodinger's derivation explains
the Hubble redshift of photons in an expanding universe, the energy changes of
moving particles, and establishes the coevolution of atoms and other quantum
systems with spacetime geometry. The assumption often made that small quantum
systems are isolated and that their properties remain constant as the Friedmann
universe evolves is incompatible with relativistic quantum mechanics and with
general relativity.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 21:00:34 GMT"
}
] | 2009-04-21T00:00:00 | [
[
"Sumner",
"W. Q.",
""
],
[
"Sumner",
"D. Y.",
""
]
] |
0704.2792 | Waldeci Paraguassu | P.F. Facanha Filho, P.T.C. Freire, K.C.V. Lima, J. Mendes Filho,
F.E.A. Melo and P.S. Pizani | Raman spectra of L-leucine crystals | 12 pages in the body and 5 figures | null | null | null | cond-mat.mtrl-sci | null | Single crystal samples of L-leucine, C6H13NO2, a fundamental aliphatic amino
acid of the human body, have been studied by Raman spectroscopy at temperatures
from 300 to 430 K over the spectral range from 50 to 3100 cm-1. A tentative
assignment of all bands is given. For high temperatures, several modifications
on the Raman spectra were observed at about 353 K, giving evidence that the
L-leucine crystal undergoes a structural phase transition.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 21:16:10 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Filho",
"P. F. Facanha",
""
],
[
"Freire",
"P. T. C.",
""
],
[
"Lima",
"K. C. V.",
""
],
[
"Filho",
"J. Mendes",
""
],
[
"Melo",
"F. E. A.",
""
],
[
"Pizani",
"P. S.",
""
]
] |
0704.2793 | Matthew Scott | Matthew Scott, Terence Hwa and Brian Ingalls | Deterministic characterization of stochastic genetic circuits | 6 pages (Supplementary Information is appended) | Proceedings of the National Academy of Sciences USA (2007), vol.
104(18): 7402-7407 | 10.1073/pnas.0610468104 | null | q-bio.MN q-bio.QM | null | For cellular biochemical reaction systems where the numbers of molecules is
small, significant noise is associated with chemical reaction events. This
molecular noise can give rise to behavior that is very different from the
predictions of deterministic rate equation models. Unfortunately, there are few
analytic methods for examining the qualitative behavior of stochastic systems.
Here we describe such a method that extends deterministic analysis to include
leading-order corrections due to the molecular noise. The method allows the
steady-state behavior of the stochastic model to be easily computed,
facilitates the mapping of stability phase diagrams that include stochastic
effects and reveals how model parameters affect noise susceptibility, in a
manner not accessible to numerical simulation. By way of illustration we
consider two genetic circuits: a bistable positive-feedback loop and a
negative-feedback oscillator. We find in the positive feedback circuit that
translational activation leads to a far more stable system than transcriptional
control. Conversely, in a negative-feedback loop triggered by a
positive-feedback switch, the stochasticity of transcriptional control is
harnessed to generate reproducible oscillations.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 21:18:14 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Scott",
"Matthew",
""
],
[
"Hwa",
"Terence",
""
],
[
"Ingalls",
"Brian",
""
]
] |
0704.2794 | Rafael Quintero-Torres | R. Quintero-Torres and J.L. Aragon, M. Torres, M. Estrada and L. Cros | Strong far field coherent scattering of ultraviolet radiation by
holococcolithophores | 4 pages and 4 figures | Phys Rev E Stat Nonlin Soft Matter Phys. 2006 Sep;74:2006 Sep 12 | null | null | physics.bio-ph | null | By considering the structure of holococcoliths (calcite plates that cover
holococcolithophores, a haploid phase of the coccolithophore life cycle) as a
photonic structure, we apply a discrete dipolar approximation to study the
light backscattering properties of these algae. We show that some holococcolith
structures have the ability to scatter the ultraviolet (UV) radiation. This
property may represent an advantage for holococcolithophores possessing it, by
allowing them to live higher in the water column than other coccolithophores.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 21:22:04 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Quintero-Torres",
"R.",
""
],
[
"Aragon",
"J. L.",
""
],
[
"Torres",
"M.",
""
],
[
"Estrada",
"M.",
""
],
[
"Cros",
"L.",
""
]
] |
0704.2795 | Boris Vainberg | S. Molchanov, B. Vainberg | Laplace Operator in Networks of Thin Fibers: Spectrum Near the Threshold | null | Stochastic analysis in mathematical physics, 69-93, World Sci.
Publ., Hackensack, NJ, 2008 | null | null | math-ph math.MP | null | Our talk at Lisbon SAMP conference was based mainly on our recent results
(published in Comm. Math. Phys.) on small diameter asymptotics for solutions of
the Helmgoltz equation in networks of thin fibers. The present paper contains a
detailed review of these results under some assumptions which make them much
more transparent. It also contains several new theorems on the structure of the
spectrum near the threshold. small diameter asymptotics of the resolvent, and
solutions of the evolution equation.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 21:27:40 GMT"
}
] | 2016-04-04T00:00:00 | [
[
"Molchanov",
"S.",
""
],
[
"Vainberg",
"B.",
""
]
] |
0704.2796 | Alan L. T. Paterson | Anthony T. Lau and Alan L. T. Paterson | Group amenability properties for von Neumann algebras | null | Indiana University Mathematics Journal 55(2006), 1363-1388 | null | null | math.OA math.FA | null | In his study of amenable unitary representations, M. E. B. Bekka asked if
there is an analogue for such representations of the remarkable fixed-point
property for amenable groups. In this paper, we prove such a fixed-point
theorem in the more general context of a $G$-amenable von Neumann algebra $M$,
where $G$ is a locally compact group acting on $M$. The F{\o}lner conditions of
Connes and Bekka are extended to the case where $M$ is semifinite and admits a
faithful, semifinite, normal trace which is invariant under the action of $G$.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 21:36:47 GMT"
},
{
"version": "v2",
"created": "Tue, 22 May 2007 14:23:28 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Lau",
"Anthony T.",
""
],
[
"Paterson",
"Alan L. T.",
""
]
] |
0704.2797 | Alan L. T. Paterson | Alan L. T. Paterson | The equivariant analytic index for proper groupoid actions | null | K-Theory 32: 193-230, 2004 | null | null | math.OA math.KT | null | The paper constructs the analytic index for an elliptic pseudodifferential
family of $L^{m}_{\rho,\de}$-operators invariant under the proper action of a
continuous family groupoid on a $G$-compact, $C^{\infty,0}$ $G$-space.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 21:47:27 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Paterson",
"Alan L. T.",
""
]
] |
0704.2798 | Lance Dixon | Zvi Bern, Lance J. Dixon, David A. Kosower | On-Shell Methods in Perturbative QCD | 49 pages, 15 figures. v2: minor typos corrected | Annals Phys.322:1587-1634,2007 | 10.1016/j.aop.2007.04.014 | UCLA/07/TEP/11, SLAC-PUB-12447, SPhT-T07/039 | hep-ph | null | We review on-shell methods for computing multi-parton scattering amplitudes
in perturbative QCD, utilizing their unitarity and factorization properties. We
focus on aspects which are useful for the construction of one-loop amplitudes
needed for phenomenological studies at the Large Hadron Collider.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 21:48:53 GMT"
},
{
"version": "v2",
"created": "Wed, 30 May 2007 16:54:54 GMT"
}
] | 2010-11-15T00:00:00 | [
[
"Bern",
"Zvi",
""
],
[
"Dixon",
"Lance J.",
""
],
[
"Kosower",
"David A.",
""
]
] |
0704.2799 | Alan L. T. Paterson | Alan L. T. Paterson | The analytic index for proper, Lie groupoid actions | null | Comtemp. Math. 282(2001), 115-135 | null | null | math.OA math.KT | null | Many index theorems (both classical and in noncommutative geometry) can be
interpreted in terms of a Lie groupoid acting properly on a manifold and
leaving an elliptic family of pseudodifferential operators invariant. Alain
Connes in his book raised the question of an index theorem in this general
context. In this paper, an analytic index for many such situations is
constructed. The approach is inspired by the classical families theorem of
Atiyah and Singer, and the proof generalizes, to the case of proper Lie
groupoid actions, some of the results proved for proper locally compact group
actions by N. C. Phillips.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 21:53:44 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Paterson",
"Alan L. T.",
""
]
] |
0704.2800 | Alan L. T. Paterson | Alan L. T. Paterson | The Fourier algebra for locally compact groupoids | null | Canadian Journal of Mathematics 56(2004), 1259-1289 | null | null | math.OA math.FA | null | We introduce and investigate using Hilbert modules the properties of the {\em
Fourier algebra} $A(G)$ for a locally compact groupoid $G$. We establish a
duality theorem for such groupoids in terms of multiplicative module maps. This
includes as a special case the classical duality theorem for locally compact
groups proved by P. Eymard.
| [
{
"version": "v1",
"created": "Fri, 20 Apr 2007 21:59:56 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Paterson",
"Alan L. T.",
""
]
] |
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