id
stringlengths 9
16
| submitter
stringlengths 1
64
⌀ | authors
stringlengths 3
36.7k
| title
stringlengths 1
382
| comments
stringlengths 1
1.15k
⌀ | journal-ref
stringlengths 1
557
⌀ | doi
stringlengths 7
153
⌀ | report-no
stringlengths 1
479
⌀ | categories
stringlengths 5
125
| license
stringclasses 9
values | abstract
stringlengths 6
6.09k
| versions
list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0707.2130 | Nadine Badr | Nadine Badr | Gagliardo-Nirenberg inequalities on manifolds | 15 pages | null | null | null | math.AP | null | We prove Gagliardo-Nirenberg inequalities on some classes of manifolds, Lie
groups and graphs.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 07:22:05 GMT"
},
{
"version": "v2",
"created": "Fri, 28 Sep 2007 13:09:44 GMT"
},
{
"version": "v3",
"created": "Wed, 2 Apr 2008 08:43:40 GMT"
},
{
"version": "v4",
"created": "Wed, 9 Apr 2008 07:21:46 GMT"
}
] | 2008-04-09T00:00:00 | [
[
"Badr",
"Nadine",
""
]
] |
0707.2131 | A. M. Jayannavar | Arnab Saha and A. M. Jayannavar | Nonequilibrium Work distributions for a trapped Brownian particle in a
time dependent magnetic field | 4 pages and 5 figures | null | 10.1103/PhysRevE.77.022105 | null | cond-mat.stat-mech | null | We study the dynamics of a trapped, charged Brownian particle in presence of
a time dependent magnetic field. We calculate work distributions for different
time dependent protocols. In our problem thermodynamic work is related to
variation of vector potential with time as opposed to the earlier studies where
the work is related to time variation of the potentials which depends only on
the coordinates of the particle. Using Jarzynski identity and Crook's equality
we show that the free energy of the particle is independent of the magnetic
field, thus complementing the Bohr-van Leeuwen theorem. We also show that our
system exhibits a parametric resonance in certain parameter space.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 07:38:24 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Saha",
"Arnab",
""
],
[
"Jayannavar",
"A. M.",
""
]
] |
0707.2132 | Chong Sheng Li | Hao Zhang, Chong Sheng Li, Zhao Li | Unparticle Physics and Supersymmetry Phenomenology | Version published in Physical Review D | Phys.Rev.D76:116003,2007 | 10.1103/PhysRevD.76.116003 | null | hep-ph | null | We show a natural form of the interaction between unparticle and
supersymmetry. Using the couplings of unparticle to supersymmetry presented, as
examples, we calculate the differential decay rates for the processes ${\it
{\tilde f}}\to {\it f}+{\cal U}_{3/2}$, ${\it {\tilde \chi}}^0\to{\it
\gamma}+{\cal U}_{3/2}$, ${\it {\tilde \chi}}^\pm\to W^\pm+{\cal U}_{3/2}$ and
${\it {\tilde \chi}}^0\to Z^0+{\cal U}_{3/2}$. Finally, we discuss the
phenomenological implication of our results and give some comments.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 10:54:32 GMT"
},
{
"version": "v2",
"created": "Wed, 18 Jul 2007 12:00:40 GMT"
},
{
"version": "v3",
"created": "Thu, 16 Aug 2007 12:25:00 GMT"
},
{
"version": "v4",
"created": "Fri, 17 Aug 2007 03:17:03 GMT"
},
{
"version": "v5",
"created": "Tue, 30 Oct 2007 06:28:39 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Zhang",
"Hao",
""
],
[
"Li",
"Chong Sheng",
""
],
[
"Li",
"Zhao",
""
]
] |
0707.2133 | Sudipta Roy Barman | S. R. Barman, S. Banik, A. K. Shukla, C. Kamal and Aparna Chakrabarti | Martensitic transition, ferrimagnetism and Fermi surface nesting in
Mn_2NiGa | Euro Physics Letters (accepted) | null | 10.1209/0295-5075/80/57002 | null | cond-mat.other | null | The electronic structure of Mn_2NiGa has been studied using density
functional theory and photoemission spectroscopy. The lower temperature
tetragonal martensitic phase with c/a= 1.25 is more stable compared to the
higher temperature austenitic phase. Mn_2NiGa is ferrimagnetic in both phases.
The calculated valence band spectrum, the optimized lattice constants and the
magnetic moments are in good agreement with experiment. The majority-spin Fermi
surface (FS) expands in the martensitic phase, while the minority-spin FS
shrinks. FS nesting indicates occurrence of phonon softening and modulation in
the martensitic phase.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 08:44:28 GMT"
},
{
"version": "v2",
"created": "Mon, 15 Oct 2007 18:24:00 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Barman",
"S. R.",
""
],
[
"Banik",
"S.",
""
],
[
"Shukla",
"A. K.",
""
],
[
"Kamal",
"C.",
""
],
[
"Chakrabarti",
"Aparna",
""
]
] |
0707.2134 | T Sengadir | T Sengadir | Semigroups on Frechet spaces and equations with infinite delays | 14 pages | null | null | null | math.DS | null | In this paper, we show existence and uniqueness of a solution to a functional
differential equation with infinite delay. We choose an appropriate Frechet
space so as to cover a large class of functions to be used as initial functions
to obtain existence and uniqueness of solutions.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 08:57:53 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Sengadir",
"T",
""
]
] |
0707.2135 | P K Dutt, N Kishore Kumar and C S Upadhyay | P K Dutt, N Kishore Kumar and C S Upadhyay | Nonconforming h-p spectral element methods for elliptic problems | 37 pages, 3 figures | null | null | null | math.NA | null | In this paper we show that we can use a modified version of the h-p spectral
element method proposed in \cite{duttora1,duttom,duttora2,tomarth} to solve
elliptic problems with general boundary conditions to exponential accuracy on
polygonal domains using nonconforming spectral element functions. A geometrical
mesh is used in a neighbourhood of the corners. With this mesh we seek a
solution which minimizes the sum of a weighted squared norm of the residuals in
the partial differential equation and the squared norm of the residuals in the
boundary conditions in fractional Sobolev spaces and enforce continuity by
adding a term which measures the jump in the function and its derivatives at
inter-element boundaries, in fractional Sobolev norms, to the functional being
minimized. In the neighbourhood of the corners, modified polar coordinates are
used and a global coordinate system elsewhere. A stability estimate is derived
for the functional which is minimized based on the regularity estimate in
\cite{babguo1}. We examine how to parallelize the method and show that the set
of common boundary values consists of the values of the function at the corners
of the polygonal domain. The method is faster than that proposed in
\cite{duttora1,duttom,tomarth} and the h-p finite element method and stronger
error estimates are obtained.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 09:07:54 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Dutt",
"P K",
""
],
[
"Kumar",
"N Kishore",
""
],
[
"Upadhyay",
"C S",
""
]
] |
0707.2136 | Bjorn Maurer and Jurgen Stuckrad | Bjorn Maurer and Jurgen Stuckrad | Reducing system of parameters and the Cohen--Macaulay property | 7 pages | null | null | null | math.AC | null | Let $R$ be a local ring and let ($x_1\biss x_r$) be part of a system of
parameters of a finitely generated $R$-module $M,$ where $r < \dim_R M$. We
will show that if ($y_1\biss y_r$) is part of a reducing system of parameters
of $M$ with $(y_1\biss y_r)M=(x_1\biss x_r)M$ then $(x_1\biss x_r)$ is already
reducing. Moreover, there is such a part of a reducing system of parameters of
$M$ iff for all primes $P\in \supp M \cap V_R(x_1\biss x_r)$ with $\dim_R R/P =
\dim_R M -r$ the localization $M_P$ of $M$ at $P$ is an $r$-dimensional \cm\
module over $R_P$. Furthermore, we will show that $M$ is a \cm module iff $y_d$
is a non zero divisor on $M/(y_1\biss y_{d-1})M$, where $(y_1\biss y_d)$ is a
reducing system of parameters of $M$ ($d := \dim_R M$).
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 09:14:33 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Maurer",
"Bjorn",
""
],
[
"Stuckrad",
"Jurgen",
""
]
] |
0707.2137 | Emilio Santos Corchero | Trevor W. Marshall and Emilio Santos | A classical model for a photodetector in the presence of electromagnetic
vacuum fluctuations | 14 pages, no figures | null | null | null | quant-ph | null | The main argument against the reality of the electromagnetic vacuum
fluctuations is that they do not activate photon detectors. In order to meet
this objection we propose a classical model of a photodetector which, in the
simple case of a light signal with constant intensity, gives a counting rate
which is a non-linear function of the intensity. For sufficiently large signal
intensity, the counting rate is proportional to the intensity, in agreement
with the standard quantum results, but there is a dark rate when the signal
intensity is low.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 09:55:25 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Marshall",
"Trevor W.",
""
],
[
"Santos",
"Emilio",
""
]
] |
0707.2138 | Rajendra Bhatia and Man-Duen Choi | Rajendra Bhatia and Man-Duen Choi | Corners of normal matrices | 7 pages | null | null | null | math.RA | null | We study various conditions on matrices $B$ and $C$ under which they can be
the off-diagonal blocks of a partitioned normal matrix.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 10:12:54 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Bhatia",
"Rajendra",
""
],
[
"Choi",
"Man-Duen",
""
]
] |
0707.2139 | Mehdi Hassani | M. Avalin Charsooghi, Y. Azizi, M. Hassani, L. Mola-Zadeh Bidokhti | On a Result of Hardy and Ramanujan | Project Report. Accepted for publication in the Sarajevo Journal of
Mathematics | null | null | null | math.NT math.GM | null | In this paper, we introduce some explicit approximations for the summation
$\sum_{k\leq n}\Omega(k)$, where $\Omega(k)$ is the total number of prime
factors of $k$.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 10:14:46 GMT"
},
{
"version": "v2",
"created": "Sat, 17 Nov 2007 08:28:53 GMT"
}
] | 2007-11-17T00:00:00 | [
[
"Charsooghi",
"M. Avalin",
""
],
[
"Azizi",
"Y.",
""
],
[
"Hassani",
"M.",
""
],
[
"Bidokhti",
"L. Mola-Zadeh",
""
]
] |
0707.2140 | T S S R K Rao | T s s R K Rao | Nice surjections on spaces of operators | 8 pages | null | null | null | math.FA | null | A bounded linear operator is said to be nice if its adjoint preserves extreme
points of the dual unit ball. Motivated by a description due to Labuschagne and
Mascioni \cite{LM} of such maps for the space of compact operators on a Hilbert
space, in this article we consider a description of nice surjections on
${\mathcal K}(X,Y)$ for Banach spaces $X,Y$. We give necessary and sufficient
conditions when nice surjections are given by composition operators. Our
results imply automatic continuity of these maps with respect to other
topologies on spaces of operators. We also formulate the corresponding result
for ${\mathcal L}(X,Y)$ thereby proving an analogue of the result from
\cite{LM} for $L^p$ ($1 <p \neq 2 <\infty$) spaces. We also formulate results
when nice operators are not of the canonical form, extending and correcting the
results from \cite{KS}.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 10:16:09 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Rao",
"T s s R K",
""
]
] |
0707.2141 | Amiya Mukherjee | Amiya Mukherjee | Gromov--Witten invariants and quantum cohomology | 18 pages | null | null | null | math.AG | null | This article is an elaboration of a talk given at an international conference
on Operator Theory, Quantum Probability, and Noncommutative Geometry held
during December~20--23, 2004, at the Indian Statistical Institute, Kolkata. The
lecture was meant for a general audience, and also prospective research
students, the idea of the quantum cohomology based on the Gromov--Witten
invariants. Of course there are many important aspects that are not discussed
here.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 10:28:22 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Mukherjee",
"Amiya",
""
]
] |
0707.2142 | V P Belavkin and L Gregory | V P Belavkin and L Gregory | Representations of homogeneous quantum L\'evy fields | 12 pages | null | null | null | math.PR | null | We study homogeneous quantum L\'{e}vy processes and fields with independent
additive increments over a noncommutative *-monoid. These are described by
infinitely divisible generating state functionals, invariant with respect to an
endomorphic injective action of a symmetry semigroup. A strongly covariant GNS
representation for the conditionally positive logarithmic functionals of these
states is constructed in the complex Minkowski space in terms of canonical
quadruples and isometric representations on the underlying pre-Hilbert field
space. This is of much use in constructing quantum stochastic representations
of homogeneous quantum L\'{e}vy fields on It\^{o} monoids, which is a natural
algebraic way of defining dimension free, covariant quantum stochastic
integration over a space-time indexing set.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 10:31:13 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Belavkin",
"V P",
""
],
[
"Gregory",
"L",
""
]
] |
0707.2143 | Remi Leandre | Remi Leandre | Malliavin calculus of Bismut type without probability | 12 pages | null | null | null | math.PR | null | We translate in semigroup theory Bismut's way of the Malliavin calculus.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 10:33:31 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Leandre",
"Remi",
""
]
] |
0707.2144 | Un Cig Ji | Un Cig Ji | Stochastic integral representations of quantum martingales on multiple
Fock space | 17 pages | null | null | null | math.PR | null | In this paper a quantum stochastic integral representation theorem is
obtained for unbounded regular martingales with respect to multidimensional
quantum noise. This simultaneously extends results of Parthasarathy and Sinha
to unbounded martingales and those of the author to multidimensions.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 10:37:11 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Ji",
"Un Cig",
""
]
] |
0707.2145 | Partha Sarathi Chakraborty and Arupkumar Pal | Partha Sarathi Chakraborty and Arupkumar Pal | On equivariant Dirac operators for $SU_q(2)$ | 11 pages | null | null | null | math.OA | null | We explain the notion of minimality for an equivariant spectral triple and
show that the triple for the quantum SU(2) group constructed by Chakraborty and
Pal in \cite{c-p1} is minimal. We also give a decomposition of the spectral
triple constructed by Dabrowski {\it et al} \cite{dlssv} in terms of the
minimal triple constructed in \cite{c-p1}.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 10:43:17 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Chakraborty",
"Partha Sarathi",
""
],
[
"Pal",
"Arupkumar",
""
]
] |
0707.2146 | Arne Jensen and Gheorghe Nenciu | Arne Jensen and Gheorghe Nenciu | Schr\"odinger operators on the half line: Resolvent expansions and the
Fermi golden rule at thresholds | 17 pages, 2 figures | null | null | null | math-ph math.MP math.SP | null | We consider Schr\"odinger operators $H=- \d^2/\d r^2+V$ on $L^2([0,\infty))$
with the Dirichlet boundary condition. The potential $V$ may be local or
non-local, with polynomial decay at infinity. The point zero in the spectrum of
$H$ is classified, and asymptotic expansions of the resolvent around zero are
obtained, with explicit expressions for the leading coefficients. These results
are applied to the perturbation of an eigenvalue embedded at zero, and the
corresponding modified form of the Fermi golden rule.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 10:49:21 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Jensen",
"Arne",
""
],
[
"Nenciu",
"Gheorghe",
""
]
] |
0707.2147 | Franco Fagnola | Franco Fagnola, Veronica Umanita | Generators of Detailed Balance Quantum Markov Semigroups | 31 pages | Infin. Dimens. Anal. Quantum Probab. Relat. Top. 10 (3) 2007,
335-363 | 10.1142/S0219025707002762 | null | math-ph math.MP | null | For a quantum Markov semigroup $\T$ on the algebra $\B$ with a faithful
invariant state $\rho$, we can define an adjoint $\widetilde{\T}$ with respect
to the scalar product determined by $\rho$. In this paper, we solve the open
problems of characterising adjoints $\widetilde{\T}$ that are also a quantum
Markov semigroup and satisfy the detailed balance condition in terms of the
operators $H,L_k$ in the Gorini Kossakowski Sudarshan Lindblad representation
$\Ll(x)=i[H,x] - {1/2}\sum_k(L^*_kL_k x-2L^*_kxL_k + xL^*_kL_k)$ of the
generator of $\T$. We study the adjoint semigroup with respect to both scalar
products $<a,b> = \tr(\rho a^* b)$ and $<a,b> = \tr(\rho^{1/2} a^*
\rho^{1/2}b)$.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 11:02:27 GMT"
},
{
"version": "v2",
"created": "Tue, 22 Apr 2008 12:46:39 GMT"
}
] | 2012-03-14T00:00:00 | [
[
"Fagnola",
"Franco",
""
],
[
"Umanita",
"Veronica",
""
]
] |
0707.2148 | Anthony Iarrobino jr | Mats Boij and Anthony Iarrobino | Reducible family of height three level algebras | 20 pages. Minor revision | null | null | null | math.AC math.AG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Let $R=k[x_1,..., x_r]$ be the polynomial ring in $r$ variables over an
infinite field $k$, and let $M$ be the maximal ideal of $R$. Here a \emph{level
algebra} will be a graded Artinian quotient $A$ of $R$ having socle
$Soc(A)=0:M$ in a single degree $j$. The Hilbert function $H(A)=(h_0,h_1,...
,h_j)$ gives the dimension $h_i=\dim_k A_i$ of each degree-$i$ graded piece of
$A$ for $0\le i\le j$. The embedding dimension of $A$ is $h_1$, and the
\emph{type} of $A$ is $\dim_k \Soc (A)$, here $h_j$. The family $\Levalg (H)$
of level algebra quotients of $R$ having Hilbert function $H$ forms an open
subscheme of the family of graded algebras or, via Macaulay duality, of a
Grassmannian.
We show that for each of the Hilbert functions $H=H_1=(1,3,4,4)$ and
$H=H_2=(1,3,6,8,9,3)$ the family $LevAlg (H)$ parametrizing level Artinian
algebras of Hilbert function $H$ has several irreducible components. We show
also that these examples each lift to points. However, in the first example, an
irreducible Betti stratum for Artinian algebras becomes reducible when lifted
to points. These were the first examples we obtained of multiple components for
$\Levalg(H)$ in embedding dimension three.
We also show that the second example is the first in an infinite sequence of
examples of type three Hilbert functions $H(c)$ in which also the number of
components of LevAlg(H) gets arbitrarily large.
The first case where the phenomenon of multiple components can occur (i.e.
the lowest embedding dimension and then the lowest type) is that of dimension
three and type two. Examples of this first case have been obtained by the
authors and also by J.-O. Kleppe.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 13:16:16 GMT"
},
{
"version": "v2",
"created": "Sat, 27 Sep 2008 14:58:49 GMT"
}
] | 2008-09-27T00:00:00 | [
[
"Boij",
"Mats",
""
],
[
"Iarrobino",
"Anthony",
""
]
] |
0707.2149 | Jochen Zahn | Jochen Zahn | Dispersion relations in quantum electrodynamics on the noncommutative
Minkowski space | 137 pages, 2 figures, PhD thesis | null | null | DESY-THESIS-2006-037 | hep-th | null | We study field theories on the noncommutative Minkowski space with
noncommuting time. The focus lies on dispersion relations in quantized
interacting models in the Yang-Feldman formalism. In particular, we compute the
two-point correlation function of the field strength in noncommutative quantum
electrodynamics to second order. At this, we take into account the covariant
coordinates that allow the construction of local gauge invariant quantities
(observables). It turns out that this does not remove the well-known severe
infrared problem, as one might have hoped. Instead, things become worse, since
nonlocal divergences appear. We also show that these cancel in a supersymmetric
version of the theory if the covariant coordinates are adjusted accordingly.
Furthermore, we study the phi^3 and the Wess-Zumino model and show that the
distortion of the dispersion relations is moderate for parameters typical for
the Higgs field. We also disuss the formulation of gauge theories on
noncommutative spaces and study classical electrodynamics on the noncommutative
Minkowski space using covariant coordinates. In particular, we compute the
change of the speed of light due to nonlinear effects in the presence of a
background field. Finally, we examine the so-called twist approach to quantum
field theory on the noncommutative Minkowski space and point out some
conceptual problems of this approach.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 11:16:04 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Zahn",
"Jochen",
""
]
] |
0707.2150 | Nejat Yilmaz | Nejat Tevfik Yilmaz | On the Symmetric Space Sigma-Model Kinematics | 17 pages | Int.J.Mod.Phys.A22:2683-2695,2007 | 10.1142/S0217751X07036324 | null | hep-th | null | The solvable Lie algebra parametrization of the symmetric spaces is
discussed. Based on the solvable Lie algebra gauge two equivalent formulations
of the symmetric space sigma model are studied. Their correspondence is
established by inspecting the normalization conditions and deriving the field
transformation laws.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 13:03:54 GMT"
}
] | 2010-10-27T00:00:00 | [
[
"Yilmaz",
"Nejat Tevfik",
""
]
] |
0707.2151 | Francis Bonahon | Hua Bai (U. Georgia), Francis Bonahon (USC), Xiaobo Liu (Columbia U.) | Local representations of the quantum Teichmuller space | 35 pages | null | null | null | math.GT math.QA | null | We introduce a certain type of representations for the quantum Teichmuller
space of a punctured surface, which we call local representations. We show
that, up to finitely many choices, these purely algebraic representations are
classified by classical geometric data. We also investigate the family of
intertwining operators associated to such a representations. In particular, we
use these intertwiners to construct a natural fiber bundle over the Teichmuller
space and its quotient under the action of the mapping class group. This
construction also offers a convenient framework to exhibit invariants of
surface diffeomorphisms.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 13:03:58 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Bai",
"Hua",
"",
"U. Georgia"
],
[
"Bonahon",
"Francis",
"",
"USC"
],
[
"Liu",
"Xiaobo",
"",
"Columbia U."
]
] |
0707.2152 | Muhammad Tahir | M Tahir, K Sabeeh and A MacKinnon | Weiss oscillations in the electronic structure of modulated graphene | 8 pages, 2 figures, accepted in J. Phys.: Conden. matt | null | 10.1088/0953-8984/19/40/406226 | null | cond-mat.mes-hall | null | We present a theoretical study of the electronic structure of modulated
graphene in the presence of a perpendicular magnetic field. The density of
states and the bandwidth for the Dirac electrons in this system are determined.
The appearance of unusual Weiss oscillations in the bandwidth and density of
states is the main focus of this work.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 13:38:11 GMT"
},
{
"version": "v2",
"created": "Mon, 17 Sep 2007 15:05:22 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Tahir",
"M",
""
],
[
"Sabeeh",
"K",
""
],
[
"MacKinnon",
"A",
""
]
] |
0707.2153 | Thomas Buchert | Thomas Buchert | Dark Energy from structure: a status report | Invited Review for a special Gen. Rel. Grav. issue on Dark Energy, 59
pages, 2 figures; matches published version | Gen.Rel.Grav.40:467-527,2008 | 10.1007/s10714-007-0554-8 | null | gr-qc astro-ph hep-th | null | The effective evolution of an inhomogeneous universe model in any theory of
gravitation may be described in terms of spatially averaged variables. In
Einstein's theory, restricting attention to scalar variables, this evolution
can be modeled by solutions of a set of Friedmann equations for an effective
volume scale factor, with matter and backreaction source terms. The latter can
be represented by an effective scalar field (`morphon field') modeling Dark
Energy.
The present work provides an overview over the Dark Energy debate in
connection with the impact of inhomogeneities, and formulates strategies for a
comprehensive quantitative evaluation of backreaction effects both in
theoretical and observational cosmology. We recall the basic steps of a
description of backreaction effects in relativistic cosmology that lead to
refurnishing the standard cosmological equations, but also lay down a number of
challenges and unresolved issues in connection with their observational
interpretation.
The present status of this subject is intermediate: we have a good
qualitative understanding of backreaction effects pointing to a global
instability of the standard model of cosmology; exact solutions and
perturbative results modeling this instability lie in the right sector to
explain Dark Energy from inhomogeneities. It is fair to say that, even if
backreaction effects turn out to be less important than anticipated by some
researchers, the concordance high-precision cosmology, the architecture of
current N-body simulations, as well as standard perturbative approaches may all
fall short in correctly describing the Late Universe.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 14:23:00 GMT"
},
{
"version": "v2",
"created": "Mon, 24 Sep 2007 10:56:21 GMT"
},
{
"version": "v3",
"created": "Mon, 3 Dec 2007 15:16:22 GMT"
}
] | 2010-04-06T00:00:00 | [
[
"Buchert",
"Thomas",
""
]
] |
0707.2154 | Daniel Evans | D. A. Evans (1), M. J. Hardcastle (2), J. H. Croston (2) ((1)
Harvard-Smithsonian Center for Astrophysics, (2) University of Hertfordshire) | X-Ray Nuclei in Radio Galaxies: Exploring the Roles of Hot and Cold Gas
Accretion | 7 pages, 2 figures; to appear in "Extragalactic Jets: Theory and
Observation from Radio to Gamma Ray", eds. T. A. Rector and D. S. De Young,
ASP conference series. Typo fixed and NASA financial support acknowledgment
added | null | null | null | astro-ph | null | We present results from Chandra and XMM-Newton spectroscopic observations of
the nuclei of z<0.5 radio galaxies and quasars from the 3CRR catalog, and
examine in detail the dichotomy in the properties of low- and high-excitation
radio galaxies. The X-ray spectra of low-excitation sources (those with weak or
absent optical emission lines) are dominated by unabsorbed emission from a
parsec-scale jet, with no contribution from accretion-related emission. These
sources show no evidence for an obscuring torus, and are likely to accrete in a
radiatively inefficient manner. High-excitation sources (those with prominent
optical emission lines), on the other hand, show a significant contribution
from a radiatively efficient accretion disk, which is heavily absorbed in the
X-ray when they are oriented close to edge-on with respect to the observer.
However, the low-excitation/high-excitation division does not correspond to the
FRI/FRII division: thus the Fanaroff-Riley dichotomy remains a consequence of
the interaction between the jet and the hot-gas environment through which it
propagates. Finally, we suggest that accretion of the hot phase of the IGM is
sufficient to power all low-excitation radio sources, while high-excitation
sources require an additional contribution from cold gas that in turn forms the
cold disk and torus. This model explains a number of properties of the
radio-loud active galaxy population, and has important implications for AGN
feedback mechanisms.
| [
{
"version": "v1",
"created": "Mon, 16 Jul 2007 15:39:40 GMT"
},
{
"version": "v2",
"created": "Thu, 2 Aug 2007 22:06:01 GMT"
}
] | 2007-08-03T00:00:00 | [
[
"Evans",
"D. A.",
""
],
[
"Hardcastle",
"M. J.",
""
],
[
"Croston",
"J. H.",
""
]
] |
0707.2155 | Arul Lakshminarayan | Arul Lakshminarayan | The modular multiplication operator and the quantized bakers maps | null | Phys. Rev. A 76, 042330 (2007) | 10.1103/PhysRevA.76.042330 | IITM/PH/TH/2007/7 | quant-ph nlin.CD | null | The modular multiplication operator, a central subroutine in Shor's factoring
algorithm, is shown to be a coherent superposition of two quantum bakers maps
when the multiplier is 2. The classical limit of the maps being completely
chaotic, it is shown that there exist perturbations that push the modular
multiplication operator into regimes of generic quantum chaos with spectral
fluctuations that are those of random matrices. For the initial state of
relevance to Shor's algorithm we study fidelity decay due to phase and bit-flip
errors in a single qubit and show exponential decay with shoulders at multiples
or half-multiples of the order. A simple model is used to gain some
understanding of this behavior.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 14:40:33 GMT"
}
] | 2011-08-02T00:00:00 | [
[
"Lakshminarayan",
"Arul",
""
]
] |
0707.2156 | Bruce Reznick | Bruce Reznick | On Hilbert's construction of positive polynomials | null | null | null | null | math.AG math.NT | null | In 1888, Hilbert described how to find real polynomials in more than one
variable which take only non-negative values but are not a sum of squares of
polynomials. His construction was so restrictive that no explicit examples
appeared until the late 1960s. We revisit and generalize Hilbert's construction
and present many such polynomials.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 15:15:54 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Reznick",
"Bruce",
""
]
] |
0707.2157 | Shung-ichi Ando | Shung-ichi Ando (Sungkyunkwan U.) | $pp \to pp\pi^0$ near threshold in pionless effective theory | 15 pages, 7 figures; 6 references added, minor revision | Eur.Phys.J.A33:185-191,2007 | 10.1140/epja/i2007-10448-8 | null | nucl-th hep-ph | null | The total cross section of the $pp\to pp\pi^0$ reaction near threshold is
calculated in pionless effective field theory with a di-baryon and external
pions. The amplitudes for a leading one-body and subleading contact neutral
pion production vertex are obtained including the initial and final state
interactions. After estimating a low-energy constant in the contact vertex, we
compare our results for the total cross section with the experimental data.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 15:33:52 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Jul 2007 02:49:52 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Ando",
"Shung-ichi",
"",
"Sungkyunkwan U."
]
] |
0707.2158 | Robert Kohn | Remy Cottet, Robert Kohn and David Nott | Variable Selection and Model Averaging in Semiparametric Overdispersed
Generalized Linear Models | 8 graphs 35 pages | null | null | null | stat.ME | null | We express the mean and variance terms in a double exponential regression
model as additive functions of the predictors and use Bayesian variable
selection to determine which predictors enter the model, and whether they enter
linearly or flexibly. When the variance term is null we obtain a generalized
additive model, which becomes a generalized linear model if the predictors
enter the mean linearly. The model is estimated using Markov chain Monte Carlo
simulation and the methodology is illustrated using real and simulated data
sets.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 16:00:44 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Cottet",
"Remy",
""
],
[
"Kohn",
"Robert",
""
],
[
"Nott",
"David",
""
]
] |
0707.2159 | Gerard Ben Arous | Gerard Ben Arous, Alice Guionnet | The spectrum of heavy-tailed random matrices | null | null | null | null | math.PR math-ph math.MP | null | Let $X_N$ be an $N\ts N$ random symmetric matrix with independent
equidistributed entries. If the law $P$ of the entries has a finite second
moment, it was shown by Wigner \cite{wigner} that the empirical distribution of
the eigenvalues of $X_N$, once renormalized by $\sqrt{N}$, converges almost
surely and in expectation to the so-called semicircular distribution as $N$
goes to infinity. In this paper we study the same question when $P$ is in the
domain of attraction of an $\alpha$-stable law. We prove that if we renormalize
the eigenvalues by a constant $a_N$ of order $N^{\frac{1}{\alpha}}$, the
corresponding spectral distribution converges in expectation towards a law
$\mu_\alpha$ which only depends on $\alpha$. We characterize $\mu_\alpha$ and
study some of its properties; it is a heavy-tailed probability measure which is
absolutely continuous with respect to Lebesgue measure except possibly on a
compact set of capacity zero.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 16:21:31 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Arous",
"Gerard Ben",
""
],
[
"Guionnet",
"Alice",
""
]
] |
0707.2160 | Seth Pettie | Seth Pettie | Splay Trees, Davenport-Schinzel Sequences, and the Deque Conjecture | null | null | null | null | cs.DS | null | We introduce a new technique to bound the asymptotic performance of splay
trees. The basic idea is to transcribe, in an indirect fashion, the rotations
performed by the splay tree as a Davenport-Schinzel sequence S, none of whose
subsequences are isomorphic to fixed forbidden subsequence. We direct this
technique towards Tarjan's deque conjecture and prove that n deque operations
require O(n alpha^*(n)) time, where alpha^*(n) is the minimum number of
applications of the inverse-Ackermann function mapping n to a constant. We are
optimistic that this approach could be directed towards other open conjectures
on splay trees such as the traversal and split conjectures.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 16:38:08 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Pettie",
"Seth",
""
]
] |
0707.2161 | Andreas de Vries | Andreas de Vries | Algebraic hierarchy of logics unifying fuzzy logic and quantum logic | 59 pages, 17 figures, lecture notes | null | null | null | math.LO | null | In this paper, a short survey about the concepts underlying general logics is
given. In particular, a novel rigorous definition of a fuzzy negation as an
operation acting on a lattice to render it into a fuzzy logic is presented.
According to this definition, a fuzzy negation satisfies the weak double
negation condition, requiring double negation to be expansive, the antitony
condition, being equivalent to the disjunctive De Morgan law and thus
warranting compatibility of negation with the lattice operations, and the
Boolean boundary condition stating that the universal bounds of the lattice are
the negation of each other. From this perspective, the most general logics are
fuzzy logics, containing as special cases paraconsistent (quantum) logics,
quantum logics, intuitionistic logics, and Boolean logics, each of which given
by its own algebraic restrictions. New examples of a non-contradictory logic
violating the conjunctive De Morgan law, and of a typical non-orthomodular
fuzzy logic along with its explicit lattice representation are given.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 17:21:47 GMT"
}
] | 2015-03-13T00:00:00 | [
[
"de Vries",
"Andreas",
""
]
] |
0707.2162 | Edvige Corbelli | Edvige Corbelli and Rene' A. M. Walterbos | Bar imprints on the inner gas kinematics of M33 | 20 pages, 12 figures, ApJ in press | null | 10.1086/521618 | null | astro-ph | null | We present measurements of the stellar and gaseous velocities in the central
5' of the Local Group spiral M33. The data were obtained with the ARC 3.5m
telescope. Blue and red spectra with resolutions from 2 to 4\AA covering the
principal gaseous emission and stellar absorption lines were obtained along the
major and minor axes and six other position angles. The observed radial
velocities of the ionized gas along the photometric major axis of M33 remain
flat at ~22 km s^{-1} all the way into the center, while the stellar velocities
show a gradual rise from zero to 22 km s^{-1} over that same region. The
central star cluster is at or very close to the dynamical center, with a
velocity that is in accordance with M33's systemic velocity to within our
uncertainties. Velocities on the minor axis are non-zero out to about 1' from
the center in both the stars and gas. Together with the major axis velocities,
they point at significant deviations from circular rotation. The most likely
explanation for the bulk of the velocity patterns are streaming motions along a
weak inner bar with a PA close to that of the minor axis, as suggested by
previously published IR photometric images. The presence of bar imprints in M33
implies that all major Local Group galaxies are barred. The non-circular
motions over the inner 200 pc make it difficult to constrain the shape of M33's
inner dark matter halo profile. If the non-circular motions we find in this
nearby Sc galaxy are present in other more distant late-type galaxies, they
might be difficult to recognize.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 17:31:51 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Corbelli",
"Edvige",
""
],
[
"Walterbos",
"Rene' A. M.",
""
]
] |
0707.2163 | Hiroyuki Tamura | Hiroyuki Tamura, John G. S. Ramon, Eric R. Bittner, and Irene
Burghardt | Phonon-driven ultrafast exciton dissociation at donor-acceptor polymer
heterojunctions | null | null | 10.1103/PhysRevLett.100.107402 | null | cond-mat.soft | null | A quantum-dynamical analysis of phonon-driven exciton dissociation at polymer
heterojunctions is presented, using a hierarchical electron-phonon model
parameterized for three electronic states and 24 vibrational modes. Two
interfering decay pathways are identified: a direct charge separation, and an
indirect pathway via an intermediate bridge state. Both pathways depend
critically on the dynamical interplay of high-frequency C=C stretch modes and
low-frequency ring-torsional modes. The ultrafast, highly non-equilibrium
dynamics is consistent with time-resolved spectroscopic observations.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 17:42:07 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Tamura",
"Hiroyuki",
""
],
[
"Ramon",
"John G. S.",
""
],
[
"Bittner",
"Eric R.",
""
],
[
"Burghardt",
"Irene",
""
]
] |
0707.2164 | Jacob Eapen | Jacob Eapen, Ju Li and Sidney Yip | Beyond the Maxwell Limit: Thermal Conduction in Nanofluids with
Percolating Fluid Structures | 5 Pages, 3 Figures, In Review: APL, Accepted for presentation at
"Nanofluids: Fundamentals and Applications", September 16-20, 2007, Copper
Mountain, Colorado | Physical Review E, 76, 062501 (2007) | 10.1103/PhysRevE.76.062501 | null | cond-mat.mtrl-sci | null | In a well-dispersed nanofluid with strong cluster-fluid attraction, thermal
conduction paths can arise through percolating amorphous-like interfacial
structures. This results in a thermal conductivity enhancement beyond the
Maxwell limit of 3*phi, with phi being the nanoparticle volume fraction. Our
findings from non-equilibrium molecular dynamics simulations, which are
amenable to experimental verification, can provide a theoretical basis for the
development of future nanofluids.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 18:03:11 GMT"
}
] | 2008-12-31T00:00:00 | [
[
"Eapen",
"Jacob",
""
],
[
"Li",
"Ju",
""
],
[
"Yip",
"Sidney",
""
]
] |
0707.2165 | Samson Saneblidze | Samson Saneblidze | Filtered Hirsch Algebras | 29 pages, 2 figures, revised the definition of a Hirsch resolution,
corrected typos | Transactions RMI, 170 (2016) 114-136 | null | null | math.AT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by the cohomology theory of loop spaces, we consider a special
class of higher order homotopy commutative differential graded algebras and
construct the filtered Hirsch model for such an algebra $A$. When $x\in H(A)$
with $\mathbb{Z}$ coefficients and $x^{2}=0,$ the symmetric Massey products $%
\langle x\rangle ^{n}$ with $n\geq 3$ have a finite order (whenever defined).
However, if $\Bbbk $ is a field of characteristic zero, $\langle x\rangle ^{n}$
is defined and vanishes in $H(A\otimes \Bbbk )$ for all $n$. If $p$ is an odd
prime, the Kraines formula $\langle x\rangle ^{p}=-\beta \mathcal{P}_{1}(x)$
lifts to $H^{\ast }(A\otimes {\mathbb{Z}}_{p}).$ Applications of the existence
of polynomial generators in the loop homology and the Hochschild cohomology
with a $G$-algebra structure are given.
| [
{
"version": "v1",
"created": "Mon, 16 Jul 2007 07:36:11 GMT"
},
{
"version": "v10",
"created": "Tue, 15 Mar 2011 07:44:43 GMT"
},
{
"version": "v11",
"created": "Mon, 19 Mar 2012 12:31:03 GMT"
},
{
"version": "v12",
"created": "Wed, 4 May 2016 11:53:54 GMT"
},
{
"version": "v2",
"created": "Wed, 8 Aug 2007 14:55:02 GMT"
},
{
"version": "v3",
"created": "Mon, 24 Sep 2007 16:01:18 GMT"
},
{
"version": "v4",
"created": "Tue, 25 Sep 2007 10:36:32 GMT"
},
{
"version": "v5",
"created": "Tue, 18 Mar 2008 13:46:07 GMT"
},
{
"version": "v6",
"created": "Fri, 21 Mar 2008 17:55:54 GMT"
},
{
"version": "v7",
"created": "Fri, 24 Oct 2008 19:13:11 GMT"
},
{
"version": "v8",
"created": "Fri, 15 May 2009 17:59:34 GMT"
},
{
"version": "v9",
"created": "Tue, 22 Feb 2011 12:09:29 GMT"
}
] | 2016-05-05T00:00:00 | [
[
"Saneblidze",
"Samson",
""
]
] |
0707.2166 | Reiner Hammer | R. Hammer and P. Ulmschneider | Chromospheric Dynamics and Line Formation | Lecture notes and review, held at Kodaikanal Winter School on Solar
Physics, Dec 2006. This version contains corrected page numbers for some of
the references | null | 10.1063/1.2756786 | null | astro-ph | null | The solar chromosphere is very dynamic, due to the presence of large
amplitude hydrodynamic waves. Their propagation is affected by NLTE radiative
transport in strong spectral lines, which can in turn be used to diagnose the
dynamics of the chromosphere. We give a basic introduction into the equations
of NLTE radiation hydrodynamics and describe how they are solved in current
numerical simulations. The comparison with observation shows that
one-dimensional codes can describe strong brightenings quite well, but the
overall chromospheric dynamics appears to be governed by three-dimensional
shock propagation.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 18:54:52 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Hammer",
"R.",
""
],
[
"Ulmschneider",
"P.",
""
]
] |
0707.2167 | Ehud Meir | Ehud Meir | An explicit formula for the action of a finite group on a commutative
ring | 7 pages | Journal of Pure and Applied Algebra 211 (2007) 43-49 | null | null | math.RA math.GR | null | Let G be a group which acts on a commutative ring k. We exhibit an induction
formula which expresses an element x_G with tr_G(x_G)=1 by elements x_P with
tr_P(x_P)=1, where P varies over prime order subgroups of P.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 20:39:55 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Meir",
"Ehud",
""
]
] |
0707.2168 | Henning Esbensen | H. Esbensen, K. Hagino, P. Mueller, and H. Sagawa | Charge radius and dipole response of $^{11}$Li | 6 pages, 3 figures | Phys.Rev.C76:024302,2007 | 10.1103/PhysRevC.76.024302 | null | nucl-th | null | We investigate the consistency of the measured charge radius and dipole
response of $^{11}$Li within a three-body model. We show how these observables
are related to the mean square distance between the $^9$Li core and the center
of mass of the two valence neutrons. In this representation we find by
considering the effect of smaller corrections that the discrepancy between the
results of the two measurements is of the order of 1.5$\sigma$. We also
investigate the sensitivity to the three-body structure of $^{11}$Li and find
that the charge radius measurement favors a model with a 50% s-wave component
in the ground state of the two-neutron halo, whereas the dipole response is
consistent with a smaller s-wave component of about 25% value.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 20:44:03 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Esbensen",
"H.",
""
],
[
"Hagino",
"K.",
""
],
[
"Mueller",
"P.",
""
],
[
"Sagawa",
"H.",
""
]
] |
0707.2169 | Yehuda Pinchover | Yehuda Pinchover and Kyril Tintarev | On positive solutions of minimal growth for singular p-Laplacian with
potential term | 28 pages | null | null | null | math.AP math.SP | null | Let $\Omega$ be a domain in $\mathbb{R}^d$, $d\geq 2$, and $1<p<\infty$. Fix
$V\in L_{\mathrm{loc}}^\infty(\Omega)$. Consider the functional $Q$ and its
G\^{a}teaux derivative $Q^\prime$ given by
Q(u):=\frac{1}{p}\int_\Omega (|\nabla u|^p+V|u|^p)\dx,
Q^\prime (u):=-\nabla\cdot(|\nabla u|^{p-2}\nabla u)+V|u|^{p-2}u.
It is assumed that $Q\geq 0$ on $C_0^\infty(\Omega)$. In a previous paper we
discussed relations between the absence of weak coercivity of the functional
$Q$ on $C_0^\infty(\Omega)$ and the existence of a generalized ground state. In
the present paper we study further relationships between functional-analytic
properties of the functional $Q$ and properties of positive solutions of the
equation $Q^\prime (u)=0$.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 21:03:51 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Pinchover",
"Yehuda",
""
],
[
"Tintarev",
"Kyril",
""
]
] |
0707.2170 | Takanori Sakamoto | T. Sakamoto, J. E. Hill, R. Yamazaki, L. Angelini, H. A. Krimm, G.
Sato, S. Swindell, K. Takami, J. P. Osborne | Evidence of Exponential Decay Emission in the Swift Gamma-ray Bursts | 33 pages, 34 figures; accepted for publication in ApJ | null | 10.1086/521640 | null | astro-ph | null | We present a systematic study of the steep decay emission from gamma-ray
bursts (GRBs) observed by the Swift X-Ray Telescope (XRT). In contrast to the
analysis described in recent literature, we produce composite Burst Alert
Telescope (BAT) and XRT light curves by extrapolating the XRT data (2-10 keV)
into the BAT energy range (15-25 keV) rather than extrapolating the BAT data
into the XRT energy band (0.3-10 keV). Based on the fits to the composite light
curves, we have confirmed the existence of an exponential decay component which
smoothly connects the BAT prompt data to the XRT steep decay for several GRBs.
We also find that the XRT steep decay for some of the bursts can be well fit by
a combination of a power-law with an exponential decay model. We discuss this
exponential component within the frame work of both the internal and the
external shock model.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 21:04:17 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sakamoto",
"T.",
""
],
[
"Hill",
"J. E.",
""
],
[
"Yamazaki",
"R.",
""
],
[
"Angelini",
"L.",
""
],
[
"Krimm",
"H. A.",
""
],
[
"Sato",
"G.",
""
],
[
"Swindell",
"S.",
""
],
[
"Takami",
"K.",
""
],
[
"Osborne",
"J. P.",
""
]
] |
0707.2171 | Maxim M. Korshunov | M.A. Korshunov | Influence of Vacancies on the Nanoparticle Pulsation | 2 pages | null | null | null | cond-mat.soft cond-mat.dis-nn cond-mat.other | null | Computer modeling of the one-dimensional and three-dimensional nanoparticles
with Van-der-Waals interaction was performed. The arrangement of atoms was
defined on the grounds of an energy minimum. The calculations have shown that
in the presence of vacancies in a nanoparticle and the account of a relaxation
and oscillations the nanoparticle will pulse. This pulsation on distance
between atoms of a nanoparticle is observed in both one-dimensional and a
three-dimensional cases.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 21:13:16 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Korshunov",
"M. A.",
""
]
] |
0707.2172 | Luis Alvarez-Ruso | L. Alvarez-Ruso, L. S. Geng, M. J. Vicente Vacas | Neutral current coherent pion production | 4 pages, 3 figures, minor corrections, a few references added | Phys.Rev.C76:068501,2007; Erratum-ibid.C80:029904,2009 | 10.1103/PhysRevC.76.068501 10.1103/PhysRevC.80.029904 | null | nucl-th hep-ex hep-ph nucl-ex | null | We investigate the neutrino induced coherent pion production reaction at low
and intermediate energies. The model includes pion, nucleon and Delta(1232)
resonance as the relevant hadronic degrees of freedom. Nuclear medium effects
on the production mechanisms and pion distortion are taken into account. We
obtain that the dominance of the Delta excitation holds due to large
cancellations among the background contributions. We consider two sets of
vector and axial-vector N-Delta transition form-factors, evidencing the strong
sensitivity of the results to the axial coupling C5A(0). The differences
between neutrino and antineutrino cross sections, emerging from interference
terms, are also discussed.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 21:13:42 GMT"
},
{
"version": "v2",
"created": "Mon, 28 Jan 2008 18:02:12 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Alvarez-Ruso",
"L.",
""
],
[
"Geng",
"L. S.",
""
],
[
"Vacas",
"M. J. Vicente",
""
]
] |
0707.2173 | Dragomir Z. Djokovic | Dragomir Z. Djokovic | Cyclic (v;r,s;lambda) difference families with two base blocks and v <=
50 | 39 pages, 6 tables. Minor corrections, a new SDS inserted. Abridged
version to appear in Annals of Combinatorics | Ann. Comb. 15 (2011) 233-254 | 10.1007/s00026-011-0092-7 | null | math.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct many new cyclic (v;r,s;lambda) difference families with v less
than or equal 50. In particular we construct the difference families with
parameters (45;18,10;9), (45;22,22;21), (47;21,12;12), (47;19,15;12),
(47;22,14;14), (48;20,10;10), (48;24,4;12), (50;25,20;20) for which the
existence question was an open problem. The (45;22,22;21) difference family
gives a BIBD with parameters v=45, b=90, r=44, k=22 and lambda=21, and the one
with parameters (50;25,20;20) gives a pair of binary sequences of length 50
with zero periodic autocorrelation function (the periodic analog of a Golay
pair). We also construct nine new D-optimal designs. A normal form for cyclic
difference families is proposed and used effectively in compiling the list of
known and new difference families.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 21:26:13 GMT"
},
{
"version": "v2",
"created": "Thu, 22 Nov 2007 19:49:23 GMT"
},
{
"version": "v3",
"created": "Tue, 17 Mar 2009 23:18:47 GMT"
},
{
"version": "v4",
"created": "Mon, 30 Mar 2009 04:47:15 GMT"
}
] | 2018-01-24T00:00:00 | [
[
"Djokovic",
"Dragomir Z.",
""
]
] |
0707.2174 | Christopher Pope | G.W. Gibbons, Joaquim Gomis, C.N. Pope | General Very Special Relativity is Finsler Geometry | 4 pages, minor corrections, references added | Phys.Rev.D76:081701,2007 | 10.1103/PhysRevD.76.081701 | DAMTP-2007-68, UB-ECM-PF-07-17, MIFP-07-18 | hep-th gr-qc hep-ph | null | We ask whether Cohen and Glashow's Very Special Relativity model for Lorentz
violation might be modified, perhaps by quantum corrections, possibly producing
a curved spacetime with a cosmological constant. We show that its symmetry
group ISIM(2) does admit a 2-parameter family of continuous deformations, but
none of these give rise to non-commutative translations analogous to those of
the de Sitter deformation of the Poincar\'e group: spacetime remains flat. Only
a 1-parameter family DISIM_b(2) of deformations of SIM(2) is physically
acceptable. Since this could arise through quantum corrections, its
implications for tests of Lorentz violations via the Cohen-Glashow proposal
should be taken into account. The Lorentz-violating point particle action
invariant under DISIM_b(2) is of Finsler type, for which the line element is
homogeneous of degree 1 in displacements, but anisotropic. We derive
DISIM_b(2)-invariant wave equations for particles of spins 0, 1/2 and 1. The
experimental bound, $|b|<10^{-26}$, raises the question ``Why is the
dimensionless constant $b$ so small in Very Special Relativity?''
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 21:46:54 GMT"
},
{
"version": "v2",
"created": "Mon, 20 Aug 2007 09:08:13 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Gibbons",
"G. W.",
""
],
[
"Gomis",
"Joaquim",
""
],
[
"Pope",
"C. N.",
""
]
] |
0707.2175 | Chenchang Zhu | Henrique Bursztyn, Chenchang Zhu | Morita equivalence of Poisson manifold via stack groupoids | 4 pages, to appear in the Oberwolfach Reports | Oberwolfach Reports. Vol. 4, no. 2. Oberwolfach Rep. 4 (2007), no.
2, 1243--1298. 53D17 (53-06) | null | null | math.DG math.SG | null | This is a condensed exposition of the results of a future work, based on a
talk of the second author at the Oberwolfach workshop "Poisson Geometry", April
30--4 May 2007.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 22:20:10 GMT"
}
] | 2009-12-10T00:00:00 | [
[
"Bursztyn",
"Henrique",
""
],
[
"Zhu",
"Chenchang",
""
]
] |
0707.2176 | Prakash Ishwar | Masoud Sharif and Prakash Ishwar | Benefit of Delay on the Diversity-Multiplexing Tradeoffs of MIMO
Channels with Partial CSI | 5 pages, 2 figures, to appear in the Proceedings of the IEEE
International Symposium on Information Theory, Nice, France, 24-29 June, 2007 | null | null | null | cs.IT math.IT | null | This paper re-examines the well-known fundamental tradeoffs between rate and
reliability for the multi-antenna, block Rayleigh fading channel in the high
signal to noise ratio (SNR) regime when (i) the transmitter has access to
(noiseless) one bit per coherence-interval of causal channel state information
(CSI) and (ii) soft decoding delays together with worst-case delay guarantees
are acceptable. A key finding of this work is that substantial improvements in
reliability can be realized with a very short expected delay and a slightly
longer (but bounded) worst-case decoding delay guarantee in communication
systems where the transmitter has access to even one bit per coherence interval
of causal CSI. While similar in spirit to the recent work on communication
systems based on automatic repeat requests (ARQ) where decoding failure is
known at the transmitter and leads to re-transmission, here transmit
side-information is purely based on CSI. The findings reported here also lend
further support to an emerging understanding that decoding delay (related to
throughput) and codeword blocklength (related to coding complexity and delays)
are distinctly different design parameters which can be tuned to control
reliability.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 22:42:02 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Sharif",
"Masoud",
""
],
[
"Ishwar",
"Prakash",
""
]
] |
0707.2177 | Eric J West | Cristian Armendariz-Picon, Mark Trodden, Eric J. West | Preheating in Derivatively-Coupled Inflation Models | 10 pages, 9 figures | JCAP0804:036,2008 | 10.1088/1475-7516/2008/04/036 | null | hep-ph astro-ph | null | We study preheating in theories where the inflaton couples derivatively to
scalar and gauge fields. Such couplings may dominate in natural models of
inflation, in which the flatness of the inflaton potential is related to an
approximate shift symmetry of the inflaton. We compare our results with
previously studied models with non-derivative couplings. For sufficiently heavy
scalar matter, parametric resonance is ineffective in reheating the universe,
because the couplings of the inflaton to matter are very weak. If scalar matter
fields are light, derivative couplings lead to a mild long-wavelength
instability that drives matter fields to non-zero expectation values. In this
case however, long-wavelength fluctuations of the light scalar are produced
during inflation, leading to a host of cosmological problems. In contrast,
axion-like couplings of the inflaton to a gauge field do not lead to production
of long-wavelength fluctuations during inflation. However, again because of the
weakness of the couplings to the inflaton, parametric resonance is not
effective in producing gauge field quanta.
| [
{
"version": "v1",
"created": "Mon, 16 Jul 2007 19:29:28 GMT"
},
{
"version": "v2",
"created": "Tue, 27 Nov 2007 22:56:19 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Armendariz-Picon",
"Cristian",
""
],
[
"Trodden",
"Mark",
""
],
[
"West",
"Eric J.",
""
]
] |
0707.2178 | Peter Muys | Peter Muys | Stimulated radiative laser cooling | null | null | 10.1134/s11490-008-4012-4 | null | physics.optics | null | Building a refrigerator based on the conversion of heat into optical energy
is an ongoing engineering challenge. Under well-defined conditions, spontaneous
anti-Stokes fluorescence of a dopant material in a host matrix is capable of
lowering the host temperature. The fluorescence is conveying away a part of the
thermal energy stored in the vibrational oscillations of the host lattice. In
particular, applying this principle to the cooling of (solid-state) lasers
opens up many potential device applications, especially in the domain of
high-power lasers. In this paper, an alternative optical cooling scheme is
outlined, leading to radiative cooling of solid-state lasers. It is based on
converting the thermal energy stored in the host, into optical energy by means
of a stimulated nonlinear process, rather than a spontaneous process. This
should lead to better cooling efficiencies and a higher potential of applying
the principle for device applications.
| [
{
"version": "v1",
"created": "Sat, 14 Jul 2007 23:04:59 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Muys",
"Peter",
""
]
] |
0707.2179 | E. T. Tomboulis | E. T. Tomboulis | Confinement for all values of the coupling in four-dimensional SU(2)
gauge theory | 49 pages, 3 figures | null | null | null | hep-th hep-lat | null | A derivation is given from first principles of the fact that the SU(2) gauge
theory is in a confining phase for all values of the coupling $0 < g < \infty$
defined at lattice spacing (UV regulator) $a$, and space-time dimension $d \leq
4$. The strategy is to employ approximate RG decimation transformations of the
potential moving type which give both upper and lower bounds on the partition
function at each successive decimation step. By interpolation between these
bounds an exact representation of the partition function is obtained on
progressively coarser lattices. In the same manner, one obtains a
representation of the partition function in the presence of external center
flux. Under successive decimations the flow of the effective action in these
representations is constrained by that in the upper and lower bounds which are
easily explicitly computable. Confining behavior for the vortex free energy
order parameter (ratio of partition functions with and without external flux),
hence `area law' for the Wilson loop, is the result for any initial coupling.
Keeping the string tension fixed determines the dependence $g(a)$, which is
such that $g(a) \to 0$ for $a \to 0$.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 18:37:41 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Tomboulis",
"E. T.",
""
]
] |
0707.2180 | Akiyuki Matsushita | Akiyuki Matsushita, Kazunori Fukuda, Yuh Yamada, Fumihiro Ishikawa,
Syun Sekiya, Masato Hedo, Takashi Naka | Physical properties of a new cuprate superconductor
Pr_2Ba_4Cu_7O_{15-\delta} | Science and Technology of Advanced Materials (in press) | null | 10.1016/j.stam.2007.07.003 | null | cond-mat.supr-con | null | We present studies of the thermal, magnetic and electrical transport
properties of reduced polycrystalline Pr_2Ba_4Cu_7O_{15-\delta} (Pr247) showing
a superconducting transition at Tc = 10 - 16 K and compare them with those of
as-sintered non-superconducting Pr247. The electrical resistivity in the normal
state exhibited T2 dependence up to approximately 150 K. A clear specific heat
anomaly was observed at Tc for Pr247 reduced in a vacuum for 24 hrs, proving
the bulk nature of the superconducting state. By the reduction treatment, the
magnetic ordering temperature TN of Pr moments decreased from 16 to 11 K, and
the entropy associated with the ordering increased, while the effective
paramagnetic moments obtained from the DC magnetic susceptibility varied from
2.72 to 3.13 mB. The sign of Hall coefficient changed from positive to negative
with decreasing temperature in the normal state of a superconducting Pr247,
while that of as-sintered one was positive down to 5 K. The electrical
resistivity under high magnetic fields was found to exhibit T^a dependence (a =
0.08 - 0.4) at low temperatures. A possibility of superconductivity in the
so-called CuO double chains is discussed.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 03:35:23 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Matsushita",
"Akiyuki",
""
],
[
"Fukuda",
"Kazunori",
""
],
[
"Yamada",
"Yuh",
""
],
[
"Ishikawa",
"Fumihiro",
""
],
[
"Sekiya",
"Syun",
""
],
[
"Hedo",
"Masato",
""
],
[
"Naka",
"Takashi",
""
]
] |
0707.2181 | I. L. Buchbinder | I.L. Buchbinder, V.A. Krykhtin, H. Takata | Gauge invariant Lagrangian construction for massive bosonic mixed
symmetry higher spin fields | v2: 15 pages, references added, minor changes, version accepted for
publication in PLB | Phys.Lett.B656:253-264,2007 | 10.1016/j.physletb.2007.09.033 | null | hep-th | null | We develop the BRST approach to gauge invariant Lagrangian construction for
the massive mixed symmetry integer higher spin fields described by the rank-two
Young tableaux in arbitrary dimensional Minkowski space. The theory is
formulated in terms of auxiliary Fock space. No off-shell constraints on the
fields and the gauge parameters are imposed. The approach under consideration
automatically leads to a gauge invariant Lagrangian for massive theory with all
appropriate Stuckelberg fields. It is shown that all the restrictions defining
an irreducible representation of the Poincare group arise from Lagrangian
formulation as a consequence of the equations of motion and gauge
transformations. As an example of the general procedure, we derive the
gauge-invariant Lagrangian for massive rank-2 antisymmetric tensor field
containing the complete set of auxiliary fields and gauge parameters.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 04:40:59 GMT"
},
{
"version": "v2",
"created": "Mon, 24 Sep 2007 15:00:11 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Buchbinder",
"I. L.",
""
],
[
"Krykhtin",
"V. A.",
""
],
[
"Takata",
"H.",
""
]
] |
0707.2182 | Massimiliano Laddomada Ph.D. | Massimiliano Laddomada | Design of Multistage Decimation Filters Using Cyclotomic Polynomials:
Optimization and Design Issues | Submitted to CAS-I, July 07; 11 pages, 5 figures, 3 tables | null | null | null | cs.OH | null | This paper focuses on the design of multiplier-less decimation filters
suitable for oversampled digital signals. The aim is twofold. On one hand, it
proposes an optimization framework for the design of constituent decimation
filters in a general multistage decimation architecture. The basic building
blocks embedded in the proposed filters belong, for a simple reason, to the
class of cyclotomic polynomials (CPs): the first 104 CPs have a z-transfer
function whose coefficients are simply {-1,0,+1}. On the other hand, the paper
provides a bunch of useful techniques, most of which stemming from some key
properties of CPs, for designing the proposed filters in a variety of
architectures. Both recursive and non-recursive architectures are discussed by
focusing on a specific decimation filter obtained as a result of the
optimization algorithm.
Design guidelines are provided with the aim to simplify the design of the
constituent decimation filters in the multistage chain.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 05:35:32 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Laddomada",
"Massimiliano",
""
]
] |
0707.2183 | Alexey Nenashev | A. V. Nenashev and A. V. Dvurechenskii | Strain distribution in quantum dot of arbitrary polyhedral shape:
Analytical solution in closed form | revtex4, 12 pages, 6 figures; Ch. II rewritten, new Ch. V added,
errors in Eq.(13) and Eq.(22) fixed | J. Appl. Phys. 107, 064322 (2010) | 10.1063/1.3357302 | null | cond-mat.other | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An analytical expression of the strain distribution due to lattice mismatch
is obtained in an infinite isotropic elastic medium (a matrix) with a
three-dimensional polyhedron-shaped inclusion (a quantum dot). The expression
was obtained utilizing the analogy between electrostatic and elastic theory
problems. The main idea lies in similarity of behavior of point charge electric
field and the strain field induced by point inclusion in the matrix. This opens
a way to simplify the structure of the expression for the strain tensor. In the
solution, the strain distribution consists of contributions related to faces
and edges of the inclusion. A contribution of each face is proportional to the
solid angle at which the face is seen from the point where the strain is
calculated. A contribution of an edge is proportional to the electrostatic
potential which would be induced by this edge if it is charged with a constant
linear charge density. The solution is valid for the case of inclusion having
the same elastic constants as the matrix. Our method can be applied also to the
case of semi-infinite matrix with a free surface. Three particular cases of the
general solution are considered--for inclusions of pyramidal, truncated
pyramidal, and "hut-cluster" shape. In these cases considerable simplification
was achieved in comparison with previously published solutions. A
generalization of the obtained solution to the case of anisotropic media is
discussed.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 15:07:48 GMT"
},
{
"version": "v2",
"created": "Sun, 29 Nov 2009 16:08:36 GMT"
}
] | 2013-08-27T00:00:00 | [
[
"Nenashev",
"A. V.",
""
],
[
"Dvurechenskii",
"A. V.",
""
]
] |
0707.2184 | Abdurrouf Abdurrouf | F.H.M. Faisal and A. Abdurrouf | Interplay of polarization geometry and rotational dynamics in high
harmonic generation from coherently rotating linear molecule | 4 pages, 5 figures | null | 10.1103/PhysRevLett.100.123005 | null | physics.atm-clus | null | Recent reports on intense-field pump-probe experiments for high harmonic
generation from coherently rotating linear molecules, have revealed remarkable
characteristic effects of the simultaneous variation of the polarization
geometry and the time delay on the high harmonic signals. We analyze the
effects and give a unified theoretical account of the experimental observations
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 06:54:35 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Faisal",
"F. H. M.",
""
],
[
"Abdurrouf",
"A.",
""
]
] |
0707.2185 | Damien Chablat | Sylvain Guegan (IRCCyN), Wisama Khalil (IRCCyN), Damien Chablat
(IRCCyN), Philippe Wenger (IRCCyN) | Mod\'elisation Dynamique d'un Robot Parall\`ele \`a 3-DDL : l'Orthoglide | null | Conf\'erence Internationale Francophone d'Automatique (07/2002)
1-6 | null | null | cs.RO | null | In this article, we propose a method for calculation of the inverse and
direct dynamic models of the Orthoglide, a parallel robot with threedegrees of
freedom in translation. These models are calculated starting from the elements
of the dynamic model of the kinematic chain structure and equations of
Newton-Euler applied to the platform. These models are obtained in explicit
form having an interesting physical interpretation.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 07:14:51 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Guegan",
"Sylvain",
"",
"IRCCyN"
],
[
"Khalil",
"Wisama",
"",
"IRCCyN"
],
[
"Chablat",
"Damien",
"",
"IRCCyN"
],
[
"Wenger",
"Philippe",
"",
"IRCCyN"
]
] |
0707.2186 | Matyas Barczy | Matyas Barczy, Gyula Pap | Weakly infinitely divisible measures on some locally compact Abelian
groups | 15 pages; added references and corrected typos | Lithuanian Mathematical Journal, Vol. 48, No. 1, 2008, 17-29 | null | null | math.PR math.GR | null | On the torus group, on the group of p-adic integers and on the p-adic
solenoid, we give a construction of an arbitrary weakly infinitely divisible
probability measure using a random element with values in a product of
(possibly infinitely many) subgroups of the real numbers. As a special case of
our results, we have a new construction of the Haar measure on the p-adic
solenoid.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 07:27:02 GMT"
},
{
"version": "v2",
"created": "Thu, 28 Feb 2008 06:58:17 GMT"
}
] | 2008-02-28T00:00:00 | [
[
"Barczy",
"Matyas",
""
],
[
"Pap",
"Gyula",
""
]
] |
0707.2187 | Nozomu Tominaga | K. Nomoto, N. Tominaga, M. Tanaka, K. Maeda, and H. Umeda | Nucleosynthesis in Core-Collapse Supernovae and GRB--Metal-Poor Star
Connection | 15 pages, 9 figures. To appear in "Supernova 1987A: 20 Years After:
Supernovae and Gamma-Ray Bursters", eds. S. Immler, K. Weiler, & R. McCray
(American Institute of Physics) (2007) | AIP Conf.Proc.937:412-426,2007 | 10.1063/1.2803601 | null | astro-ph | null | We review the nucleosynthesis yields of core-collapse supernovae (SNe) for
various stellar masses, explosion energies, and metallicities. Comparison with
the abundance patterns of metal-poor stars provides excellent opportunities to
test the explosion models and their nucleosynthesis. We show that the abundance
patterns of extremely metal-poor (EMP) stars, e.g., the excess of C, Co, Zn
relative to Fe, are in better agreement with the yields of hyper-energetic
explosions (Hypernovae, HNe) rather than normal supernovae.
We note that the variation of the abundance patterns of EMP stars are related
to the diversity of the Supernova-GRB connection. We summarize the diverse
properties of (1) GRB-SNe, (2) Non-GRB HNe/SNe, (3) XRF-SN, and (4) Non-SN GRB.
In particular, the Non-SN GRBs (dark hypernovae) have been predicted in order
to explain the origin of C-rich EMP stars. We show that these variations and
the connection can be modeled in a unified manner with the explosions induced
by relativistic jets. Finally, we examine whether the most luminous supernova
2006gy can be consistently explained with the pair-instability supernova model.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 08:10:00 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Nomoto",
"K.",
""
],
[
"Tominaga",
"N.",
""
],
[
"Tanaka",
"M.",
""
],
[
"Maeda",
"K.",
""
],
[
"Umeda",
"H.",
""
]
] |
0707.2188 | Kenji Bekki dr | Kenji Bekki | On the Origin of the Kinematical Differences Between the Stellar Halo
and the Old Globular Cluster System in the Large Magellanic Cloud | 10 pages, 8 figures, accepted by MNRAS | null | 10.1111/j.1365-2966.2007.12219.x | null | astro-ph | null | We discuss structural and kinematical properties of the stellar halo and the
old globular cluster system (GCS) in the Large Magellanic Cloud (LMC) based on
numerical simulations of the LMC formation. We particularly discuss the
observed possible GCS's rotational kinematics (V/sigma > 2) that appears to be
significantly different from the stellar halo's one with a large velocity
dispersion (~50 km/s). We consider that both halo field stars and old GCs can
originate from low-mass subhalos virialized at high redshifts (z >6). We
investigate the final dynamical properties of the two old components in the
LMC's halo formed from merging of low-mass subhalos with field stars and GCs.
We find that the GCS composed of old globular clusters (GCs) formed at high
redshifts (z > 6) has little rotation (V/sigma ~0.4) and structure and
kinematics similar to those of the stellar halo. This inconsistency between the
simulated GCS's kinematics and the observed one is found to be seen in models
with different parameters. This inconsistency therefore implies that if old,
metal-poor GCs in the LMC have rotational kinematics, they are highly unlikely
to originate from the low-mass subhalos that formed the stellar halo. We thus
discuss a scenario in which the stellar halo was formed from low-mass subhalos
with no/few GCs whereas the GCS was formed at the very early epoch of the LMC's
disk formation via dissipative minor and major merging of gas-rich subhalos and
gas infall. We suggest that there can be a threshold subhalo mass above which
GCs can be formed within subhalos at high redshifts and thus that this
threshold causes differences in physical properties between stellar halos and
GCSs in less luminous galaxies like the LMC.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 08:33:48 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Bekki",
"Kenji",
""
]
] |
0707.2189 | Jose Capco | Jose Capco | Real Closed Rings and Real Closed * Rings | null | null | null | null | math.RA math.AC | null | Here we try to distinguish and compare different notions of real closedness
mainly one developed by N. Schwartz in his Habilitationschrift and the other
developed by A. Sankaranand K. Varadarajan which we shall call real closed *.
We stick to the definition of real closed rings as defined and characterized N.
Schwartz and we try to determine and characterize real closed rings that are
real closed *. The main result is that real closed rings have unique real
closure * and that real closure of real closed * rings arent necessarily real
closed *.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 08:46:13 GMT"
},
{
"version": "v2",
"created": "Wed, 12 Sep 2007 14:13:12 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Capco",
"Jose",
""
]
] |
0707.2190 | Lourdes Benito | Lourdes Benito | Solutions of the problem of Erd\"os-Sierpi\'nski:
$\sigma(n)=\sigma(n+1)$ | null | null | null | null | math.NT | null | For $n\leq 1.5 \cdot 10^{10}$, we have found a total number of 1268 solutions
to the Erd\"os-Sierpi\'nski problem finding positive integer solutions of
$\sigma(n)=\sigma(n+1)$, where $\sigma(n)$ is the sum of the positive divisors
of n. On the basis of that set of solutions the following empirical properties
are enunciated: first, all the $\sigma(n)$, $n$ being a solution, are divisible
by 6; second, the repetition of solutions leads to the formulation of a new
problem: \emph{Find the natural numbers $n$ such that
$\sigma(n)=\sigma(n+1)=\sigma(n+k)=\sigma(n+k+1)$ for some positive integer
$k$}. A third empirical property concerns the asymptotic behavior of the
function of $n$ that gives the number of solutions for $m$ less or equal to
$n$, which we find to be as $n^{1/3}$. Finally some theorems related to the
Erd\"os-Sierpi\'nski problem are enunciated and proved.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 08:49:52 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Benito",
"Lourdes",
""
]
] |
0707.2191 | Renaud Lambiotte | R. Lambiotte, M. Ausloos and M. Thelwall | Word statistics in Blogs and RSS feeds: Towards empirical universal
evidence | 16 pages, 6 figures | J. Informetrics 1 (2007) 277-286 | null | null | cs.IT math.IT | null | We focus on the statistics of word occurrences and of the waiting times
between such occurrences in Blogs. Due to the heterogeneity of words'
frequencies, the empirical analysis is performed by studying classes of
"frequently-equivalent" words, i.e. by grouping words depending on their
frequencies. Two limiting cases are considered: the dilute limit, i.e. for
those words that are used less than once a day, and the dense limit for
frequent words. In both cases, extreme events occur more frequently than
expected from the Poisson hypothesis. These deviations from Poisson statistics
reveal non-trivial time correlations between events that are associated with
bursts of activities. The distribution of waiting times is shown to behave like
a stretched exponential and to have the same shape for different sets of words
sharing a common frequency, thereby revealing universal features.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 08:51:43 GMT"
}
] | 2012-09-25T00:00:00 | [
[
"Lambiotte",
"R.",
""
],
[
"Ausloos",
"M.",
""
],
[
"Thelwall",
"M.",
""
]
] |
0707.2192 | S Brendle | S. Brendle | A generalization of Hamilton's differential Harnack inequality for the
Ricci flow | revised version, to appear in J. Diff. Geom | null | null | null | math.DG math.AP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In [10], R. Hamilton established a differential Harnack inequality for
solutions to the Ricci flow with nonnegative curvature operator. We show that
this inequality holds under the weaker condition that M x R^2 has nonnegative
isotropic curvature.
| [
{
"version": "v1",
"created": "Mon, 16 Jul 2007 14:40:11 GMT"
},
{
"version": "v2",
"created": "Thu, 25 Sep 2008 09:16:29 GMT"
}
] | 2008-09-25T00:00:00 | [
[
"Brendle",
"S.",
""
]
] |
0707.2193 | Denis Rastegaev Mr. | E.V. Malogolovets (1), Yu. Yu. Balega (1), D.A. Rastegaev (1), K.-H.
Hofmann (2), G. Weigelt (2) ((1) Special Astrophysical Observatory, Russia,
(2) Max-Planck-Institut fur Radioastronomie, Germany) | GJ 900: A new hierarchical system with low-mass components | 7 pages, 5 figures | null | 10.1134/S1990341307020034 | null | astro-ph | null | Speckle interferometric observations made with the 6 m telescope of the
Special Astrophysical Observatory of the Russian Academy of Sciences in 2000
revealed the triple nature of the nearby ($\pi_{Hip}=51.80\pm1.74$ mas)
low-mass young ($\approx200$ Myr) star GJ 900. The configuration of the triple
system allowed it to be dynamically unstable. Differential photometry performed
from 2000 through 2004 yielded $I$- and $K$-band absolute magnitudes and
spectral types for the components to be $I_{A}$=6.66$\pm$0.08,
$I_{B}$=9.15$\pm$0.11, $I_{C}$=10.08$\pm$0.26, $K_{A}$=4.84$\pm$0.08,
$K_{B}$=6.76$\pm$0.20, $K_{C}$=7.39$\pm$0.31, $Sp_{A}$$\approx$K5--K7,
$Sp_{B}$$\approx$M3--M4, $Sp_{C}$$\approx$M5--M6. The ``mass--luminosity''
relation is used to estimate the individual masses of the components:
$\mathcal{M}_{A}$$\approx0.64\mathcal{M}_{\odot}$,
$\mathcal{M}_{B}$$\approx0.21\mathcal{M}_{\odot}$,
$\mathcal{M}_{C}$$\approx0.13\mathcal{M}_{\odot}$. From the observations of the
components relative motion in the period 2000--2006, we conclude that GJ 900 is
a hierarchical triple star with the possible orbital periods
P$_{A-BC}$$\approx$80 yrs and P$_{BC}$$\approx$20 yrs. An analysis of the 2MASS
images of the region around GJ 900 leads us to suggest that the system can
include other very-low-mass components.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 09:09:02 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Malogolovets",
"E. V.",
""
],
[
"Balega",
"Yu. Yu.",
""
],
[
"Rastegaev",
"D. A.",
""
],
[
"Hofmann",
"K. -H.",
""
],
[
"Weigelt",
"G.",
""
]
] |
0707.2194 | Didier Sornette | D. Sornette (ETH Zurich) | Probability Distributions in Complex Systems | 27 pages, Review article for the Encyclopedia of Complexity and
System Science (Springer Science) | null | null | null | physics.data-an physics.gen-ph | null | We review briefly the concepts underlying complex systems and probability
distributions. The later are often taken as the first quantitative
characteristics of complex systems, allowing one to detect the possible
occurrence of regularities providing a step toward defining a classification of
the different levels of organization (the ``universality classes''). A rapid
survey covers the Gaussian law, the power law and the stretched exponential
distributions. The fascination for power laws is then explained, starting from
the statistical physics approach to critical phenomena, out-of-equilibrium
phase transitions, self-organized criticality, and ending with a large but not
exhaustive list of mechanisms leading to power law distributions. A check-list
for testing and qualifying a power law distribution from your data is described
in 7 steps. This essay enlarges the description of distributions by proposing
that ``kings'', i.e., events even beyond the extrapolation of the power law
tail, may reveal an information which is complementary and perhaps sometimes
even more important than the power law distribution. We conclude a list of
future directions.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 09:25:19 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Sornette",
"D.",
"",
"ETH Zurich"
]
] |
0707.2195 | Usha Devi A. R. | A. R. Usha Devi and A. K. Rajagopal | Generalized information theoretic measure to discern the quantumness of
correlations | 5 pages, no figures, Revtex, Minor changes; Accepted for publication
in Physical Review Letters | Phys. Rev. Lett. 100, 140502 (2008) | 10.1103/PhysRevLett.100.140502 | null | quant-ph | null | A novel measure, quantumness of correlations is introduced here for bipartite
states, by incorporating the required measurement scheme crucial in defining
any such quantity. Quantumness coincides with the previously proposed measures
in special cases and it vanishes for separable states - a feature not captured
by the measures proposed earlier. It is found that an optimal generalized
measurement on one of the parts leaves the overall state in its closest
separable form, which shares the same marginal for the other part, implying
that quantumness is non-zero for all entangled bipartite states and it serves
as an upper bound to the relative entropy of entanglement.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 11:17:22 GMT"
},
{
"version": "v2",
"created": "Tue, 2 Oct 2007 13:54:57 GMT"
},
{
"version": "v3",
"created": "Wed, 28 Nov 2007 17:01:38 GMT"
},
{
"version": "v4",
"created": "Fri, 29 Feb 2008 15:03:52 GMT"
}
] | 2008-04-20T00:00:00 | [
[
"Devi",
"A. R. Usha",
""
],
[
"Rajagopal",
"A. K.",
""
]
] |
0707.2196 | Hrvoje Buljan | H. Buljan, K. Lelas, R. Pezer, and M. Jablan | The single-particle density matrix and the momentum distribution of dark
"solitons" in a Tonks-Girardeau gas | 9 pages, 8 figures | Phys. Rev. A 76, 043609 (2007) | 10.1103/PhysRevA.76.043609 | null | cond-mat.other | null | We study the reduced single-particle density matrix (RSPDM), the momentum
distribution, natural orbitals and their occupancies, of dark "soliton" (DS)
states in a Tonks-Girardeau gas. DS states are specially tailored excited
many-body eigenstates, which have a dark solitonic notch in their
single-particle density. The momentum distribution of DS states has a
characteristic shape with two sharp spikes. We find that the two spikes arise
due to the high degree of correlation observed within the RSPDM between the
mirror points ($x$ and $-x$) with respect to the dark notch at $x=0$; the
correlations oscillate rather than decay as the points $x$ and $-x$ are being
separated.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 10:34:30 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Buljan",
"H.",
""
],
[
"Lelas",
"K.",
""
],
[
"Pezer",
"R.",
""
],
[
"Jablan",
"M.",
""
]
] |
0707.2197 | Edouard B. Sonin | E.B. Sonin | Mechanical measurement of equilibrium spin currents in the Rashba medium | 4 pages, 1 figure | Phys. Rev. Lett. 99, 266602 (2007) | 10.1103/PhysRevLett.99.266602 | null | cond-mat.mes-hall | null | We demonstrate that an equilibrium spin current in a 2D electron gas with
Rashba spin-orbit interaction (Rashba medium) results in a mechanical torque on
a substrate near an edge of the medium. If the substrate is a cantilever, the
mechanical torque displaces the free end of the cantilever. The effect can be
enhanced and tuned by a magnetic field. Observation of this displacement would
be an effective method to prove existence of equilibrium spin currents. The
analysis of edges of the Rashba medium demonstrates the existence of localized
edge states. They form a 1D continuum of states. This suggests a new type of
quantum wire: spin-orbit quantum wire.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 10:32:24 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sonin",
"E. B.",
""
]
] |
0707.2198 | Estelle Moraux | E. Moraux, W. Lawson, C. Clarke | eta Chameleontis: abnormal initial mass function or dynamical evolution? | 10 pages, 5 figures, accepted by A&A | null | 10.1051/0004-6361:20066847 | null | astro-ph | null | Eta Chamaeleontis is a unique young (~9 Myr) association with 18 systems
concentrated in a radius of ~35 arcmin, i.e. 1pc at the cluster distance of
97pc. No other members have been found up to 1.5 degrees from the cluster
centre. The cluster mass function is consistent with the IMF of other rich
young open clusters in the higher mass range but shows a clear deficit of low
mass stars and brown dwarfs with no objects below 0.1Msun. The aim of this
paper is to test whether this peculiar mass function could result from
dynamical evolution despite the young age of the cluster. We performed N-body
numerical calculations starting with a log-normal IMF and different initial
conditions in terms of number of systems and cluster radius using the code
NBODY3. We simulated the cluster dynamical evolution over 10 Myr and compared
the results to the observations. We found that it is possible to reproduce eta
Cha when starting with a very compact configuration (with Ninit=40 and
R0=0.005pc) which suggests that the IMF of the association might not be
abnormal. The high initial density might also explain the deficit of wide
binaries that is observed in the cluster.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 10:35:46 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Moraux",
"E.",
""
],
[
"Lawson",
"W.",
""
],
[
"Clarke",
"C.",
""
]
] |
0707.2199 | Sadegh Movahed | M. Sadegh Movahed and Ahmad Sheykhi | Observational constraints on the braneworld model with brane-bulk energy
exchange | 17 pages and 18 figures, V2: Added comments, references, explained
some topics related to the matter power spectrum as a robust constraint,
accepted for publication in Mon. Not. R. Astron. Soc | Mon. Not. R. Astron. Soc. 388, 197- 210 (2008) | 10.1111/j.1365-2966.2008.13330.x | null | astro-ph | null | We investigate the viability of the braneworld model with energy exchange
between the brane and bulk, by using the most recent observational data related
to the background evolution. We show that this energy exchange behaves like a
source of dark energy and can alter the profile of the cosmic expansion. The
new Supernova Type Ia (SNIa) Gold sample, Supernova Legacy Survey (SNLS) data,
the position of the acoustic peak at the last scattering surface from the
Wilkinson Microwave Anisotropy Probe (WMAP) observations and the baryon
acoustic oscillation peak found in the Sloan Digital Sky Survey (SDSS) are used
to constrain the free parameters of this model. To infer its consistency with
the age of the Universe, we compare the age of old cosmological objects with
what computed using the best fit values for the model parameters. At 68% level
of confidence, the combination of Gold sample SNIa, Cosmic Microwave Background
(CMB) shift parameter and SDSS databases provide
$\Omega_m=0.29_{-0.02}^{+0.03}$, $\Omega_{A}=-0.71_{-0.03}^{+0.03}$ and
$\mu=-0.40_{-0.26}^{+0.28}$, hence a spatially flat Universe with
$\Omega_K=0.00_{-0.04}^{+0.04}$. The same combination with SNLS supernova
observation give $\Omega_m=0.27_{-0.02}^{+0.02}$,
$\Omega_{A}=-0.74_{-0.02}^{+0.04}$ and $\mu=0.00_{-0.30}^{+0.30}$ consequently
provides a spatially flat Universe $\Omega_K=-0.01_{-0.03}^{+0.04}$. These
results obviously seem to be compatible with the most recent WMAP results
indicating a flat Universe.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 10:46:57 GMT"
},
{
"version": "v2",
"created": "Fri, 30 May 2008 16:09:44 GMT"
}
] | 2008-07-24T00:00:00 | [
[
"Movahed",
"M. Sadegh",
""
],
[
"Sheykhi",
"Ahmad",
""
]
] |
0707.2200 | Lester Fox Machado | J.H. Pena, L. Fox Machado, R. Garrido | uvby--beta photoelectric photometry of NGC 7063 | 9 pages, 5 figures, accepted for publication in RevMexAA | null | null | null | astro-ph | null | From uvby photometry of 75 stars in the direction of NGC 7063 we were able to
determine membership of some stars and fix the distance (722 +- 105 pc), log
age (of 8.146) and reddening (E(b-y) = 0.091 +- 0.039 mag) for the cluster.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 10:51:18 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Pena",
"J. H.",
""
],
[
"Machado",
"L. Fox",
""
],
[
"Garrido",
"R.",
""
]
] |
0707.2201 | Irina Bobkova V | I. V. Bobkova, A. M. Bobkov | Influence of spin filtering and spin mixing on the subgap structure of
I-V characteristics in superconducting quantum point contact | 9 pages, 3 figures | PRB 76, 094517 (2007) | 10.1103/PhysRevB.76.094517 | null | cond-mat.supr-con cond-mat.mes-hall | null | The effect of spin filtering and spin mixing on the dc electric current for
voltage biased magnetic quantum point contact with superconducting leads is
theoretically studied. The I-V characteristics are calculated for the whole
range of spin filtering and spin mixing parameters. It is found that with
increasing of spin filtering the subharmonic step structure of the dc electric
current, typical for low-transparency junction and junction without
considerable spin filtering qualitatively changes. In the lower voltage region
and for small enough spin mixing the peak structure arises. When spin mixing
increases the peak subgap structure evolves to the step structure. The voltages
where subharmonic gap features are located are found to be sensitive to the
value of spin filtering. The positions of peaks and steps are calculated
analytically and the evolution of the subgap structure from well-known tunnel
limit to the large spin filtering case is explained in terms of multiple
Andreev reflection (MAR) processes. In particular, it is found that for large
spin filtering the subgap feature at $eV_k$ arises from $2k^{\rm th}$ and
$(2k\pm 1)^{\rm th}$ order MAR processes, while in the tunnel limit the step at
$eV_n$ is known to result from $n^{\rm th}$ order MAR process.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 10:59:06 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Bobkova",
"I. V.",
""
],
[
"Bobkov",
"A. M.",
""
]
] |
0707.2202 | Andrey Kormilitzin | Andrey Kormilitzin | Saturation model in the non-Glauber approach | 27 pages, 18 figures and one table, typos were corrected | null | null | null | hep-ph | null | In this paper a new saturation model is presented. This model is based on the
theoretical solution for the generating functional, and it is quite different
and not more complicated than the Glauber-like approach used before. The model
describes the structure function F_{2} of the proton, as well as the
diffractive structure function F_{2}^{D}. We show the difference between our
model, and the eikonal approach by calculating the multiplicity distribution,
using the AGK cutting rules strategy.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 13:03:32 GMT"
},
{
"version": "v2",
"created": "Wed, 18 Jul 2007 14:38:44 GMT"
},
{
"version": "v3",
"created": "Sun, 22 Jul 2007 15:04:50 GMT"
},
{
"version": "v4",
"created": "Tue, 31 Jul 2007 09:46:24 GMT"
}
] | 2007-07-31T00:00:00 | [
[
"Kormilitzin",
"Andrey",
""
]
] |
0707.2203 | Sergei Chekanov V. | S.V. Chekanov and B.B. Levchenko | On influence of experimental resolution on the statistical significance
of a signal: implication for pentaquark searches | 12 pages, 3 eps figures, 2 tables | Phys.Rev.D76:074025,2007 | 10.1103/PhysRevD.76.074025 | ANL-HEP-PR-07-47 | hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An analytical relationship between the statistical significance of an
observed signal and the signal width in case of a large background was
obtained. It can help to explain why high-energy experiments may have different
conclusions on the existence of new particles. We illustrate our approach using
the experimental data on searches for the Theta+(1530) pentaquark state. The
obtained relationship is also useful for planning of future experiments
designed to search for signals of new particles in invariant-mass
distributions.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 11:15:30 GMT"
},
{
"version": "v2",
"created": "Mon, 22 Jun 2009 18:32:38 GMT"
}
] | 2009-06-22T00:00:00 | [
[
"Chekanov",
"S. V.",
""
],
[
"Levchenko",
"B. B.",
""
]
] |
0707.2204 | Levent Akant | Levent Akant | Deformation Quantization of Odd Dimensional anti-de Sitter Spaces as
Contact Manifolds | 10 pages | null | null | null | hep-th | null | We quantize odd dimensional anti-de Sitter spaces by applying the method of
deforming contact manifolds proposed by Rajeev. The construction in the present
paper consists of the identification of the odd dimensional anti-de Sitter
space as a hypersurface of contact type and the subsequent use of
'symplectization' principle. We also show that this construction generalizes to
any odd dimensional hypersurface which can be represented as a nonzero level
set of a homogenous function.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 11:41:09 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Akant",
"Levent",
""
]
] |
0707.2205 | Xiaoping Yang | Xiaoping Yang, Jiangwei Chen, Hui Jiang, Jinming Dong | Chiral Symmetry of Double-Walled Carbon Nanotubes detected in
First-principles Optical Absorption Spectra | 10 pages, 5 figures | Physical Review B 69, 193401 (2004) | 10.1103/PhysRevB.69.193401 | null | cond-mat.mtrl-sci cond-mat.other | null | The linear polarizability absorption spectra of the double-walled carbon
nanotubes (DWNTs) have been calculated by using the tight-binding (TB) model
and sum-over-state (SOS) method, supplemented by the first principles CASTEP
calculations. It is found that the chiral symmetries of both outer and inner
tubes in the DWNTs can always be identified distinctly by the characteristic
peaks in the absorption spectra of the DWNTs, no matter what kind of the outer
tube is, offering a powerful experimental tool to measure precisely the chiral
angle of the inner tube of a DWNT.
| [
{
"version": "v1",
"created": "Mon, 16 Jul 2007 19:15:40 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Jul 2007 12:45:28 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Yang",
"Xiaoping",
""
],
[
"Chen",
"Jiangwei",
""
],
[
"Jiang",
"Hui",
""
],
[
"Dong",
"Jinming",
""
]
] |
0707.2206 | Jeremy Shears | Jeremy Shears, David Boyd, Tom Krajci, Robert Koff, John R.
Thorstensen and Gary Poyner | Photometry and astrometry of SS Leo Minoris during the 2006 October
superoutburst | 15 pages, 9 figures. Accepted for publication in the Journal of the
British Astronomical Association | null | null | null | astro-ph | null | We report unfiltered CCD observations of the first confirmed superoutburst of
the SU UMa-type dwarf nova SS LMi in October 2006. From a quiescent magnitude
of around 21.7 it rose to 16.2, an outburst amplitude of about 5.5 magnitudes.
It declined at 0.17 mag/d for 5 days before slowing to 0.11 mag/d for a further
3 days. The light curve revealed common superhumps with a peak-to-peak
amplitude of 0.3 magnitude, which decayed and then re-grew concurrently with
the change in decline rate. These were followed by a phase-changing transition
to late superhumps. Analysis of these observations has revealed evidence for an
orbital period of 0.05572(19) d and a common superhump period of 0.05664(2) d,
giving a fractional superhump period excess of 0.017(5). From astrometry of SS
LMi in outburst we have established for the first time its correct position as
RA 10h 34m 05.85(1)s, Dec +31deg 08m 00.00(18)s (J2000). The position commonly
given for SS LMi is that of a nearby star.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 13:38:28 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Shears",
"Jeremy",
""
],
[
"Boyd",
"David",
""
],
[
"Krajci",
"Tom",
""
],
[
"Koff",
"Robert",
""
],
[
"Thorstensen",
"John R.",
""
],
[
"Poyner",
"Gary",
""
]
] |
0707.2207 | Chang-Guang Shi | Minoru Hirayama, Chang-Guang Shi | Reduction of static field equation of Faddeev model | 8 pages | Phys.Lett.B652:384-387,2007 | 10.1016/j.physletb.2007.07.025 | null | hep-th | null | A method to solve the static field equation of the Faddeev model is
presented. For an special combination of the concerned field, we adopt a form
which is compatible with the field equation and involves two arbitrary complex
functions. As a result, the static field equation is reduced to a set of first
order partial differential equations.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 14:04:27 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hirayama",
"Minoru",
""
],
[
"Shi",
"Chang-Guang",
""
]
] |
0707.2208 | Maxim V. Polyakov | N. Kivel, M.V. Polyakov | Breakdown of chiral expansion for parton distributions | 10 pages, 7 figures | Phys.Lett.B664:64-69,2008 | 10.1016/j.physletb.2008.04.048 | null | hep-ph hep-lat nucl-ex | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the framework of the chiral perturbation theory we computed two- and
three-loop corrections to the pion parton distributions which posses
$\delta$-function singularities at x->0. This calculation explicitly
demonstrates that in the region of small x ~ mpi^2/(4 pi F)^2 standard ChPT
breaks down and one needs resummation of all orders. We give an example of such
resummation.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 14:22:29 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Jun 2008 08:02:42 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kivel",
"N.",
""
],
[
"Polyakov",
"M. V.",
""
]
] |
0707.2209 | Alexander Zuyev L. | Alexander L. Zuyev | Stabilization of the spatial oscillations of an elastic system model | Bulletin of University of Kyiv (Series: Physics & Mathematics), 2007,
No. 3, P. 74-79 | null | null | null | math.OC math.DS | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A system of partial differential equations describing the spatial
oscillations of an Euler-Bernoulli beam with a tip mass is considered. The
linear system considered is actuated by two independent controls and separated
into a pair of differential equations in a Hilbert space. A feedback control
ensuring strong stability of the equilibrium in the sense of Lyapunov is
proposed. The proof of the main result is based on the theory of strongly
continuous semigroups.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 14:27:02 GMT"
},
{
"version": "v2",
"created": "Fri, 9 Feb 2018 21:53:58 GMT"
}
] | 2018-02-13T00:00:00 | [
[
"Zuyev",
"Alexander L.",
""
]
] |
0707.2210 | Alexander K. Motovilov | Elena A. Kolganova, Alexander K. Motovilov, Werner Sandhas | Ultracold scattering processes in three-atomic helium systems | null | Nucl. Phys. A 790 (2007), 752c-756c | 10.1016/j.nuclphysa.2007.03.120 | null | physics.atm-clus physics.chem-ph | null | We review results on scattering observables for $^4$He--$^4$He$_2$ and
$^3$He--$^4$He$_2$ collisions. We also study the effect of varying the coupling
constant of the atom-atom interaction on the scattering length.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 15:04:04 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Kolganova",
"Elena A.",
""
],
[
"Motovilov",
"Alexander K.",
""
],
[
"Sandhas",
"Werner",
""
]
] |
0707.2211 | Menachem Tsindlekht | M.I. Tsindlekht, V.M. Genkin, G.I. Leviev, I. Felner, O. Yuli, I.
Asulin, O. Millo, M.A. Belogolovskii and N.Yu. Shitsevalov | Linear and nonlinear low frequency electrodynamics of the surface
superconducting states in an yttrium hexaboride a single crystal | 21 figures, 12 pages | null | 10.1103/PhysRevB.78.024522 | null | cond-mat.supr-con | null | We report the low-frequency and tunneling studies of yttrium hexaboride
single crystal. Ac susceptibility at frequencies 10 - 1500 Hz has been measured
in parallel to the crystal surface DC felds, H0. We found that in the DC feld
H0 > Hc2 DC magnetic moment completely disappears while the ac response
exhibited the presence of superconductivity at the surface. Increasing of the
DC field from Hc2 revealed the enlarging of losses with a maximum in the feld
between Hc2 and Hc3. Losses at the maximum were considerably larger than in the
mixed and in the normal states. The value of the DC field, where loss peak was
observed, depends on the amplitude and frequency of the ac feld. Close to Tc
this peak shifts below Hc2 which showed the coexistence of surface
superconducting states and Abrikosov vortices. We observed a logarithmic
frequency dependence of the in-phase component of the susceptibility. Such
frequency dispersion of the inphase component resembles the response of
spin-glass systems, but the out-of-phase component also exhibited frequency
dispersion that is not a known feature of the classic spin-glass response.
Analysis of the experimental data with Kramers-Kronig relations showed the
possible existence of the loss peak at very low frequencies (< 5 Hz). We found
that the amplitude of the third harmonic was not a cubic function of the ac
amplitude even at considerably weak ac felds. This does not leave any room for
treating the nonlinear effects on the basis of perturbation theory. We show
that the conception of surface vortices or surface critical currents could not
adequately describe the existing experimental data. Consideration of a model of
slow relaxing nonequilibrium order parameter permits one to explain the partial
shielding and losses of weak ac field for H0 > Hc2.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 14:53:44 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Tsindlekht",
"M. I.",
""
],
[
"Genkin",
"V. M.",
""
],
[
"Leviev",
"G. I.",
""
],
[
"Felner",
"I.",
""
],
[
"Yuli",
"O.",
""
],
[
"Asulin",
"I.",
""
],
[
"Millo",
"O.",
""
],
[
"Belogolovskii",
"M. A.",
""
],
[
"Shitsevalov",
"N. Yu.",
""
]
] |
0707.2212 | Dmitry Krimer | Dmitry O. Krimer and Etienne Brasselet | Light-driven liquid crystalline nonlinear oscillator under optical
periodic forcing | 5 pages, 6 figures, submitted to Phys. Rev. E | Phys. Rev. E 76, 021705 (2007) | 10.1103/PhysRevE.76.021705 | null | cond-mat.soft cond-mat.other | null | An all-optically driven strategy to govern a liquid crystalline collective
molecular nonlinear oscillator is discussed. It does not require external
feedbacks of any kind while the oscillator and a time-depending perturbation
both are sustained by incident light. Various dynamical regimes such as
frequency -locked, quasiperiodic, forced and chaotic are observed in agreement
with a theoretical approach developed in the limit of the plane wave
approximation.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 15:13:03 GMT"
}
] | 2010-01-29T00:00:00 | [
[
"Krimer",
"Dmitry O.",
""
],
[
"Brasselet",
"Etienne",
""
]
] |
0707.2213 | Armando Villares Ferrer | A. Villares Ferrer, C. Morais Smith | Dynamical localization of a particle coupled to a two-level systems
thermal reservoir | null | null | null | null | cond-mat.mes-hall cond-mat.stat-mech | null | Using the functional-integral method, we investigate the effect of a
two-level systems thermal reservoir on the single particle dynamics. We find
that at low temperatures, within the sub-ohmic regime, the particle becomes
{}``dynamically'' localized at long times due to an effective potential
generated by the particle-reservoir interaction. This behavior is different
from the one obtained for the usual bath of harmonic oscillators and is
fundamentally related with the non-Markovian character of the dissipative
process.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 15:13:36 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Ferrer",
"A. Villares",
""
],
[
"Smith",
"C. Morais",
""
]
] |
0707.2214 | Petros Souvatzis Dr | P. Souvatzis, O. Eriksson, M. I. Katsnelson | Anomalous thermal expansion in $\alpha$-titanium | article, 4 pages, 3 figures | Phys. Rev. Lett. 99, 015901 (2007) | 10.1103/PhysRevLett.99.015901 | null | cond-mat.mtrl-sci | null | We provide a complete quantitative explanation for the anisotropic thermal
expansion of hcp Ti at low temperature. The observed negative thermal expansion
along the c-axis is reproduced theoretically by means of a parameter free
theory which involves both the electron and phonon contributions to the free
energy. The thermal expansion of titanium is calculated and found to be
negative along the c-axis for temperatures below $\sim$ 170 K, in good
agreement with observations. We have identified a saddle-point Van Hove
singularity near the Fermi level as the main reason for the anisotropic thermal
expansion in $\alpha-$titanium.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 15:24:26 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Souvatzis",
"P.",
""
],
[
"Eriksson",
"O.",
""
],
[
"Katsnelson",
"M. I.",
""
]
] |
0707.2215 | Pedro Sancho | Pedro Sancho | Detection of massive multi-particle beams by two-particle ionization | Accepted in PLA | null | 10.1016/j.physleta.2007.05.004 | null | quant-ph | null | Multi-photon absorption is a well-known phenomenon. With atom lasers a
similar process could take place for massive particles, the ionization of an
atom or molecule by the successive interaction with various particles. This
process would lead to multi-particle detection events for incident
multi-particle beams. We show that two-particle detections would introduce a
correction (proportional to the fourth power of the wavefunction modulus) to
the usual one-particle detection probability (only proportional to the second
power).
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 15:27:42 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sancho",
"Pedro",
""
]
] |
0707.2216 | Angelo Nucciotti | A. Nucciotti | Double beta decay: experiments and theory review | Talk presented at Flavor Physics & CP Violation Conference, Bled,
2007; 7 pages | ECONFC070512:025,2007 | null | fpcp07_412 | nucl-ex | null | Neutrinoless double beta decay is one of the most powerful tools to set the
neutrino mass absolute scale and establish whether the neutrino is a Majorana
particle. After a summary of the neutrinoless double beta decay phenomenology,
the present status of the experimental search for this rare decay is reported
and the prospects for next generation experiments are reviewed.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 15:37:22 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Jul 2007 08:23:09 GMT"
},
{
"version": "v3",
"created": "Sat, 28 Jul 2007 17:04:42 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Nucciotti",
"A.",
""
]
] |
0707.2217 | Christof Puhle | Christof Puhle | The Killing spinor equation with higher order potentials | 28 pages; revised, more concise | J.Geom.Phys.58:1355-1375,2008 | 10.1016/j.geomphys.2008.05.010 | null | math.DG math-ph math.MP | null | Let (M^n,g) be a Riemannian spin manifold. The basic equations in
supergravity models of type IIa string theory with 4-form flux involve a 3-form
T, a 4-form F, a spinorial covariant derivative \nabla depending on \nabla^g,
T, F, and a \nabla-parallel spinor field \Psi. We classify and construct many
explicit families of solutions to this system of spinorial field equations by
means of non-integrable special geometries. The latter include \alpha-Sasakian
structures in dimensions 5 and 7, almost Hermitian structures in dimension 6
and cocalibrated G_2-structures in dimension 7. We show that there are several
examples also satisfying an additional constraint for the energy-momentum
tensor.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 16:27:19 GMT"
},
{
"version": "v2",
"created": "Mon, 14 Jan 2008 14:02:41 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Puhle",
"Christof",
""
]
] |
0707.2218 | Laurent Hilico | Franck Bielsa (LKB - Jussieu, DPM), Khelifa Djerroud (LPL), Andrei
Goncharov (LPL), Albane Douillet (LKB - Jussieu, DPM), Tristan Valenzuela
(LKB - Jussieu, DPM), Christophe Daussy (LPL), Laurent Hilico (LKB - Jussieu,
DPM), Anne Amy-Klein (LPL) | HCOOH high resolution spectroscopy in the 9.18$\mu$m region | null | null | 10.1016/j.jms.2007.10.003 | null | physics.atom-ph | null | We report on higly accurate absolute frequency measurement against a
femtosecond frequency comb of 6 saturated absorption lines of formic acid
(HCOOH) with an accuracy of 1 kHz. We also report the frequency measurement of
17 other lines with an accuracy of 2 kHz. Those lines are in quasi coincidence
with the 9R(36) to 9R(42) CO$_2$ laser emission lines and are probed either by
a CO$_2$ or a widely tunable quantum cascade laser phase locked to a master
CO$_2$ laser. The relative stability of two HCOOH stabilized lasers is
characterized by a relative Allan deviation of 4.5 10$^{-12}$ $\tau^{-1/2}$.
They give suitable frequency references for H$_2^+$ Doppler free two-photon
spectroscopy.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 16:46:17 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Bielsa",
"Franck",
"",
"LKB - Jussieu, DPM"
],
[
"Djerroud",
"Khelifa",
"",
"LPL"
],
[
"Goncharov",
"Andrei",
"",
"LPL"
],
[
"Douillet",
"Albane",
"",
"LKB - Jussieu, DPM"
],
[
"Valenzuela",
"Tristan",
"",
"LKB - Jussieu, DPM"
],
[
"Daussy",
"Christophe",
"",
"LPL"
],
[
"Hilico",
"Laurent",
"",
"LKB - Jussieu,\n DPM"
],
[
"Amy-Klein",
"Anne",
"",
"LPL"
]
] |
0707.2219 | Masaomi Tanaka | Ken'ichi Nomoto, Masaomi Tanaka, Nozomu Tominaga, Keiichi Maeda, and
Paolo A. Mazzali | Hypernovae and their Gamma-Ray Bursts Connection | 23 pages, 12 figures. To appear in New Astronomy Reviews, Proceedings
of the Conference ``A LIFE WITH STARS'' | null | null | null | astro-ph | null | The connection between long Gamma Ray Bursts (GRBs) and Supernovae (SNe),
have been established through the well observed cases of GRB980425/SN 1998bw,
GRB030329/SN 2003dh and GRB031203/SN 2003lw. These events can be explained as
the prompt collapse to a black hole (BH) of the core of a massive star (M ~ 40
Msun) that had lost its outer hydrogen and helium envelopes. All these SNe
exhibited strong oxygen lines, and their energies were much larger than those
of typical SNe, thus these SNe are called Hypernovae (HNe). The case of SN
2006aj/GRB060218 appears different: the GRB was weak and soft (an X-Ray Flash,
XRF); the SN is dimmer and has very weak oxygen lines. The explosion energy of
SN 2006aj was smaller, as was the ejected mass. In our model, the progenitor
star had a smaller mass than other GRB/SNe (M ~ 20 Msun), suggesting that a
neutron star (NS) rather than a black hole was formed. If the nascent neutron
star was strongly magnetized (a so-called magnetar) and rapidly spinning, it
may launch a weak GRB or an XRF. The final fate of 20-30 Msun stars show
interesting variety, as seen in the very peculiar Type Ib/c SN 2005bf. This
mass range corresponds to the NS to BH transition. We also compare the
nucleosynthesis feature of HNe with the metal-poor stars and suggest the
Hypernova-First Star connection.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 16:49:34 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Nomoto",
"Ken'ichi",
""
],
[
"Tanaka",
"Masaomi",
""
],
[
"Tominaga",
"Nozomu",
""
],
[
"Maeda",
"Keiichi",
""
],
[
"Mazzali",
"Paolo A.",
""
]
] |
0707.2220 | Alin Ciuperca | Alin Ciuperca and George A. Elliott | A remark on invariants for C*-algebras of stable rank one | null | null | null | null | math.OA | null | It is shown that, for a C*-algebra of stable rank one (i.e., in which the
invertible elements are dense), two well-known isomorphism invariants, the
Cuntz semigroup and the Thomsen semigroup, contain the same information. More
precisely, these two invariants, viewed appropiately, determine each other in a
natural way.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 16:50:29 GMT"
},
{
"version": "v2",
"created": "Fri, 21 Sep 2007 22:57:58 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Ciuperca",
"Alin",
""
],
[
"Elliott",
"George A.",
""
]
] |
0707.2221 | Eugen Varvaruca | Eugen Varvaruca | On some properties of travelling water waves with vorticity | null | SIAM J. Math. Anal., 39 (2008), 1686-1692 | null | null | math.AP | null | We prove that for a large class of vorticity functions the crest of a
corresponding travelling water wave is necessarily a point of maximal
horizontal velocity. We also show that for waves with nonpositive vorticity the
pressure in the flow is everywhere larger than the atmospheric pressure. A
related a priori estimate for waves with nonnegative vorticity is also given.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 16:51:27 GMT"
}
] | 2008-03-26T00:00:00 | [
[
"Varvaruca",
"Eugen",
""
]
] |
0707.2222 | Jacques Soffer | Claude Bourrely, Jacques Soffer and Tai Tsun Wu | Impact picture for the analyzing power $A_N$ in very forward $pp$
elastic scattering | 6 pages, 6 figures, to appear Physical Review D | Phys.Rev.D76:053002,2007 | 10.1103/PhysRevD.76.053002 | null | hep-ph | null | In the framework of the impact picture we compute the analyzing power $A_N$
for $pp$ elastic scattering at high energy and in the very forward direction.
We consider the full set of Coulomb amplitudes and show that the interference
between the hadronic non-flip amplitude and the single-flip Coulomb amplitude
is sufficient to obtain a good agreement with the present experimental data.
This leads us to conclude that the single-flip hadronic amplitude is small in
this low momentum transfer region and it strongly suggests that this process
can be used as an absolute polarimeter at the BNL-RHIC $pp$ collider.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 16:53:18 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Bourrely",
"Claude",
""
],
[
"Soffer",
"Jacques",
""
],
[
"Wu",
"Tai Tsun",
""
]
] |
0707.2223 | Philippe Grangier | Philippe Grangier | "Disproof of Bell's Theorem" : more critics | 2 pages, no figure - in v2 some remarks and one simple example are
added - in v3 a more explicit conclusion is added | null | null | null | quant-ph | null | In a series of recent papers (quant-ph/0703179, quant-ph/0703244,
arXiv:0707.1333) Joy Christian claims to have "disproved Bell's theorem".
Though his work is certainly intellectually stimulating, we argue below that
his main claim is unwarranted.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 17:18:50 GMT"
},
{
"version": "v2",
"created": "Sat, 28 Jul 2007 09:02:56 GMT"
},
{
"version": "v3",
"created": "Fri, 17 Aug 2007 12:25:38 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Grangier",
"Philippe",
""
]
] |
0707.2224 | Eugen Varvaruca | Eugen Varvaruca | On the existence of extreme waves and the Stokes conjecture with
vorticity | 36 pages, main results are improved, additional material is added | J. Differential Equations, 246 (2009), 4043-4076. | null | null | math.AP | null | This is a study of singular solutions of the problem of traveling gravity
water waves on flows with vorticity. We show that, for a certain class of
vorticity functions, a sequence of regular waves converges to an extreme wave
with stagnation points at its crests. We also show that, for any vorticity
function, the profile of an extreme wave must have either a corner of
$120^\circ$ or a horizontal tangent at any stagnation point about which it is
supposed symmetric. Moreover, the profile necessarily has a corner of
$120^\circ$ if the vorticity is nonnegative near the free surface.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 18:18:20 GMT"
},
{
"version": "v2",
"created": "Thu, 4 Oct 2007 13:33:54 GMT"
},
{
"version": "v3",
"created": "Mon, 31 Mar 2008 12:11:22 GMT"
}
] | 2009-10-04T00:00:00 | [
[
"Varvaruca",
"Eugen",
""
]
] |
0707.2225 | Willy Kley | Paul Cresswell (1), Gerben Dirksen (2), Willy Kley (2), Richard P.
Nelson (1) ((1) Queen May University of London, (2) University of Tuebingen) | On the evolution of eccentric and inclined protoplanets embedded in
protoplanetary disks | accepted for Astronomy & Astrophysics, 16 pages, 16 figures,
animations under:
http://www.tat.physik.uni-tuebingen.de/~kley/publ/paper/eccp.html | null | 10.1051/0004-6361:20077666 | null | astro-ph | null | Young planets embedded in their protoplanetary disk interact gravitationally
with it leading to energy and angular momentum exchange. This interaction
determines the evolution of the planet through changes to the orbital
parameters. We investigate changes in the orbital elements of a 20 Earth--mass
planet due to the torques from the disk. We focus on the non-linear evolution
of initially non-vanishing eccentricity $e$ and/or inclination $i$. We treat
the disk as a two- or three-dimensional viscous fluid and perform
hydrodynamical simulations with an embedded planet. We find rapid exponential
decay of the planet orbital eccentricity and inclination for small initial
values of $e$ and $i$, in agreement with linear theory. For larger values of $e
> 0.1$ the decay time increases and the decay rate scales as $\dot{e} \propto
e^{-2}$, consistent with existing theoretical models. For large inclinations
($i$ > 6 deg) the inclination decay rate shows an identical scaling $di/dt
\propto i^{-2}$. We find an interesting dependence of the migration on the
eccentricity. In a disk with aspect ratio $H/r=0.05$ the migration rate is
enhanced for small non-zero eccentricities ($e < 0.1$), while for larger values
we see a significant reduction by a factor of $\sim 4$. We find no indication
for a reversal of the migration for large $e$, although the torque experienced
by the planet becomes positive when $e \simeq 0.3$. This inward migration is
caused by the persisting energy loss of the planet.
For non gap forming planets, eccentricity and inclination damping occurs on a
time scale that is very much shorter than the migration time scale. The results
of non linear hydrodynamic simulations are in very good agreement with linear
theory for small $e$ and $i$.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 17:13:46 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Cresswell",
"Paul",
"",
"Queen May University of London"
],
[
"Dirksen",
"Gerben",
"",
"University of Tuebingen"
],
[
"Kley",
"Willy",
"",
"University of Tuebingen"
],
[
"Nelson",
"Richard P.",
"",
"Queen May University of London"
]
] |
0707.2226 | Hicham El Bouanani | Hicham El-Bouanani (CPT), Michel Rouleux (CPT) | Thermodynamical Equilibrium of Vortices in the Isotropic Bidimensional
Kac Rotator | 48pages | null | null | null | math-ph math.MP | null | We consider here the problem of extrema for the Kac functional with long
range, ferromagnetic interaction, and vorticity conditions at infinity which
make it not weakly closed. Using a gradient-flow dynamics, we investigate local
minima, showing strong analogies with the Ginzburg-Landau functional in
infinite volume.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 17:48:36 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Jul 2007 14:52:24 GMT"
},
{
"version": "v3",
"created": "Wed, 22 Aug 2007 09:06:59 GMT"
}
] | 2007-08-22T00:00:00 | [
[
"El-Bouanani",
"Hicham",
"",
"CPT"
],
[
"Rouleux",
"Michel",
"",
"CPT"
]
] |
0707.2227 | Damien Chablat | Philippe Wenger (IRCCyN), Damien Chablat (IRCCyN), Mazen Zein (IRCCyN) | Degeneracy study of the forward kinematics of planar 3-RPR parallel
manipulators | null | Journal of Mechanical Design 129, 12 (12/2007) 1-6 | null | null | cs.RO | null | This paper investigates two situations in which the forward kinematics of
planar 3-RPR parallel manipulators degenerates. These situations have not been
addressed before. The first degeneracy arises when the three input joint
variables r1, r2 and r3 satisfy a certain relationship. This degeneracy yields
a double root of the characteristic polynomial in t, which could be erroneously
interpreted as two coalesce assembly modes. But, unlike what arises in
non-degenerate cases, this double root yields two sets of solutions for the
position coordinates (x, y) of the platform. In the second situation, we show
that the forward kinematics degenerates over the whole joint space if the base
and platform triangles are congruent and the platform triangle is rotated by
180 deg about one of its sides. For these "degenerate" manipulators, which are
defined here for the first time, the forward kinematics is reduced to the
solution of a 3rd-degree polynomial and a quadratics in sequence. Such
manipulators constitute, in turn, a new family of analytic planar manipulators
that would be more suitable for industrial applications.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 17:57:21 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Wenger",
"Philippe",
"",
"IRCCyN"
],
[
"Chablat",
"Damien",
"",
"IRCCyN"
],
[
"Zein",
"Mazen",
"",
"IRCCyN"
]
] |
0707.2228 | Damien Chablat | Maher Baili (IRCCyN), Philippe Wenger (IRCCyN), Damien Chablat
(IRCCyN) | Kinematic Analysis of a Family of 3R Manipulators | null | Problems of Mechanics 15, 2 (07/2004) 27-32 | null | null | cs.RO | null | The workspace topologies of a family of 3-revolute (3R) positioning
manipulators are enumerated. The workspace is characterized in a half-cross
section by the singular curves. The workspace topology is defined by the number
of cusps that appear on these singular curves. The design parameters space is
shown to be divided into five domains where all manipulators have the same
number of cusps. Each separating surface is given as an explicit expression in
the DH-parameters. As an application of this work, we provide a necessary and
sufficient condition for a 3R orthogonal manipulator to be cuspidal, i.e. to
change posture without meeting a singularity. This condition is set as an
explicit expression in the DH parameters.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 18:00:53 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Baili",
"Maher",
"",
"IRCCyN"
],
[
"Wenger",
"Philippe",
"",
"IRCCyN"
],
[
"Chablat",
"Damien",
"",
"IRCCyN"
]
] |
0707.2229 | Damien Chablat | Damien Chablat (IRCCyN), Jorge Angeles (CIM) | The Computation of All 4R Serial Spherical Wrists With an Isotropic
Architecture | null | Journal of Mechanical Design 125, 2 (06/2003) 275-280 | null | null | cs.RO | null | A spherical wrist of the serial type with n revolute (R) joints is said to be
isotropic if it can attain a posture whereby the singular values of its
Jacobian matrix are all equal to sqrt(n/3). What isotropy brings about is
robustness to manufacturing, assembly, and measurement errors, thereby
guaranteeing a maximum orientation accuracy. In this paper we investigate the
existence of redundant isotropic architectures, which should add to the
dexterity of the wrist under design by virtue of its extra degree of freedom.
The problem formulation, for, leads to a system of eight quadratic equations
with eight unknowns. The Bezout number of this system is thus 2^8=256, its BKK
bound being 192. However, the actual number of solutions is shown to be 32. We
list all solutions of the foregoing algebraic problem. All these solutions are
real, but distinct solutions do not necessarily lead to distinct manipulators.
Upon discarding those algebraic solutions that yield no new wrists, we end up
with exactly eight distinct architectures, the eight corresponding manipulators
being displayed at their isotropic postures.
| [
{
"version": "v1",
"created": "Sun, 15 Jul 2007 18:04:09 GMT"
}
] | 2007-07-17T00:00:00 | [
[
"Chablat",
"Damien",
"",
"IRCCyN"
],
[
"Angeles",
"Jorge",
"",
"CIM"
]
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.