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| versions
list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0708.0349 | Rong-Gen Cai | Xing Wu, Yi Zhang, Hui Li, Rong-Gen Cai, and Zong-Hong Zhu | Observational Constraints on Agegraphic Dark Energy | Revtex, 10 pages with 11 figures. Discussions and minor corrections
added | null | null | null | astro-ph | null | In this paper, we use the Type Ia supernova data as well as the CMB and LSS
data to constrain the agegraphic dark energy model recently proposed by Cai.
Due to its peculiar nature, the parameter $n$ of this model cannot be well
constrained by the SNIa data, while the other parameter $\Omega_{m0}$ can be
constrained to be $0.34\pm0.04$. When combined with CMB and LSS data, the range
of $1\sigma$ confidence level for $n$ is greatly narrowed, albeit still very
large. The best fit result is $\Omega_{m0}=0.28\pm0.02$, which is consistent
with most observations like WMAP and SDSS, and $n=3.4$, of which a meaningful
range of confidence level can not be obtained due to the fact that the contours
are not closed. Despite of this result, we conclude that for $n>1$ this model
is consistent with SNIa, CMB and LSS observations. Furthermore, the fitting
results indicate a generalized definition for the agegraphic dark energy.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 14:35:27 GMT"
},
{
"version": "v2",
"created": "Tue, 2 Oct 2007 15:27:08 GMT"
}
] | 2007-10-02T00:00:00 | [
[
"Wu",
"Xing",
""
],
[
"Zhang",
"Yi",
""
],
[
"Li",
"Hui",
""
],
[
"Cai",
"Rong-Gen",
""
],
[
"Zhu",
"Zong-Hong",
""
]
] |
0708.0350 | Vincent Garcia | V. Garcia, Y. Sidis, M. Marangolo, F. Vidal, M. Eddrief, P. Bourges,
F. Maccherozzi, F. Ott, G. Panaccione, and V. H. Etgens | Biaxial Strain in the Hexagonal Plane of MnAs Thin Films: The Key to
Stabilize Ferromagnetism to Higher Temperature | 4 pages, 3 figures, accepted for publication in Physical Review
Letters | null | 10.1103/PhysRevLett.99.117205 | null | cond-mat.mtrl-sci | null | The alpha-beta magneto-structural phase transition in MnAs/GaAs(111)
epilayers is investigated by elastic neutron scattering. The in-plane parameter
of MnAs remains almost constant with temperature from 100 K to 420 K, following
the thermal evolution of the GaAs substrate. This induces a temperature
dependent biaxial strain that is responsible for an alpha-beta phase
coexistence and, more important, for the stabilization of the ferromagnetic
alpha-phase at higher temperature than in bulk. We explain the premature
appearance of the beta-phase at 275 K and the persistence of the ferromagnetic
alpha-phase up to 350 K with thermodynamical arguments based on the MnAs phase
diagram. It results that the biaxial strain in the hexagonal plane is the key
parameter to extend the ferromagnetic phase well over room temperature.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 14:10:30 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Garcia",
"V.",
""
],
[
"Sidis",
"Y.",
""
],
[
"Marangolo",
"M.",
""
],
[
"Vidal",
"F.",
""
],
[
"Eddrief",
"M.",
""
],
[
"Bourges",
"P.",
""
],
[
"Maccherozzi",
"F.",
""
],
[
"Ott",
"F.",
""
],
[
"Panaccione",
"G.",
""
],
[
"Etgens",
"V. H.",
""
]
] |
0708.0351 | G\"oran F\"aldt | G\"oran F\"aldt and Ulla Tengblad | Hard pion bremsstrahlung in the Coulomb region | 18 pages, 5 figures | Phys.Rev.C76:064607,2007 | 10.1103/PhysRevC.76.064607 | null | nucl-th | null | Hard high-energy pion-nucleus bremsstrahlung, $\pi^- +A\to\pi^- +\gamma +A$,
is studied in the Coulomb region, i.e. the small-angle region where the nuclear
scattering is dominated by the Coulomb interaction. Special attention is
focussed on the possibility of measuring the pion polarizability in such
reactions. We study the sensitivity to the structure of the underlying the
pion-Compton amplitude through a model with $\sigma$, $\rho$, and a_1
exchanges. It is found that the effective energy in the virtual pion-Compton
scattering is often so large that the threshold approximation does not apply.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 14:10:46 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Fäldt",
"Göran",
""
],
[
"Tengblad",
"Ulla",
""
]
] |
0708.0352 | Alice Dechambre | A. Dechambre | Gribov Poles in Diffractive Physics | 4 pages, 7 figures, Proceedings Jjc, La Rochelle, December 2006 | null | null | null | hep-ph | null | High-energy diffractive physics has several interests for theoreticians and
experimentalists. We first remind the reader of the main characteristics of
diffraction in particles physics and present the calculation of a two-gluon
exchange in which non-perturbative effects are introduced via new singularities
from confinement.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 14:11:15 GMT"
}
] | 2007-08-03T00:00:00 | [
[
"Dechambre",
"A.",
""
]
] |
0708.0353 | Dariusz Grech | D. Grech, G. Pamu{\l}a (University of Wroclaw, ITP) | The Local Fractal Properties of the Financial Time Series on the Polish
Stock Exchange Market | LaTeX, 14 pages, 12 figures included | null | null | null | q-fin.ST cs.CE physics.data-an | null | We investigate the local fractal properties of the financial time series
based on the evolution of the Warsaw Stock Exchange Index (WIG) connected with
the largest developing financial market in Europe. Calculating the local Hurst
exponent for the WIG time series we find an interesting dependence between the
behavior of the local fractal properties of the WIG time series and the crashes
appearance on the financial market.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 14:22:30 GMT"
}
] | 2008-12-02T00:00:00 | [
[
"Grech",
"D.",
"",
"University of Wroclaw, ITP"
],
[
"Pamuła",
"G.",
"",
"University of Wroclaw, ITP"
]
] |
0708.0354 | Bhashyam Balaji | Bhashyam Balaji | Universal Nonlinear Filtering Using Feynman Path Integrals I: The
Continuous-Discrete Model with Additive Noise | Interdisciplinary, pedagogical, 37 pages, 2 figures | null | null | null | cond-mat.other | null | The continuous-discrete filtering problem requires the solution of a partial
differential equation known as the Fokker-Planck-Kolmogorov forward equation
(FPKfe). In this paper, the path integral formula for the fundamental solution
of the FPKfe is derived and verified for the general additive noise case (i.e.,
explicitly time-dependent state model and with state-independent rectangular
diffusion vielbein). The solution is universal in the sense that the initial
distribution may be arbitrary. The practical utility is demonstrated via some
examples.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 14:42:58 GMT"
}
] | 2007-08-03T00:00:00 | [
[
"Balaji",
"Bhashyam",
""
]
] |
0708.0355 | Alyson G. Wilson | Alyson G. Wilson, Todd L. Graves, Michael S. Hamada, C. Shane Reese | Advances in Data Combination, Analysis and Collection for System
Reliability Assessment | Published at http://dx.doi.org/10.1214/088342306000000439 in the
Statistical Science (http://www.imstat.org/sts/) by the Institute of
Mathematical Statistics (http://www.imstat.org) | Statistical Science 2006, Vol. 21, No. 4, 514-531 | 10.1214/088342306000000439 | IMS-STS-STS208 | stat.ME | null | The systems that statisticians are asked to assess, such as nuclear weapons,
infrastructure networks, supercomputer codes and munitions, have become
increasingly complex. It is often costly to conduct full system tests. As such,
we present a review of methodology that has been proposed for addressing system
reliability with limited full system testing. The first approaches presented in
this paper are concerned with the combination of multiple sources of
information to assess the reliability of a single component. The second general
set of methodology addresses the combination of multiple levels of data to
determine system reliability. We then present developments for complex systems
beyond traditional series/parallel representations through the use of Bayesian
networks and flowgraph models. We also include methodological contributions to
resource allocation considerations for system relability assessment. We
illustrate each method with applications primarily encountered at Los Alamos
National Laboratory.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 14:42:06 GMT"
}
] | 2009-09-29T00:00:00 | [
[
"Wilson",
"Alyson G.",
""
],
[
"Graves",
"Todd L.",
""
],
[
"Hamada",
"Michael S.",
""
],
[
"Reese",
"C. Shane",
""
]
] |
0708.0356 | Gian Luca Giorgi | Ferdinando de Pasquale, Gian Luca Giorgi | Quantum phase diffusion of a Bose system: beyond the
Hartree-Fock-Bogoliubov approximation | null | null | null | null | quant-ph | null | A diffusion process is usually assumed for the phase of the order parameter
of a Bose system of finite size. The theoretical basis is limited to the so
called Bogoliubov approximation. We show that a suitable generalization of the
Hartree-Fock-Bogoliubov approach recovers phase diffusion.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 14:46:05 GMT"
}
] | 2007-08-03T00:00:00 | [
[
"de Pasquale",
"Ferdinando",
""
],
[
"Giorgi",
"Gian Luca",
""
]
] |
0708.0357 | Pierre Capel | G. Goldstein, P. Capel, and D. Baye | Analysis of Coulomb breakup experiments of 8B with a dynamical eikonal
approximation | 24 pages, 8 figures. Accepted for publication in Phys. Rev. C | null | 10.1103/PhysRevC.76.024608 | null | nucl-th | null | Various measurements of the Coulomb breakup of 8B are analyzed within the
dynamical eikonal approximation using a single description of 8B. We obtain a
good agreement with experiment for different observables measured between 40
and 80 MeV per nucleon. A simple 7Be-p potential model description of 8B seems
sufficient to describe all observables. In particular, the asymmetry in
parallel-momentum distributions due to E1-E2 interferences is well reproduced
without any scaling. The projectile-target nuclear interactions seem negligible
if data are selected at forward angles. On the contrary, like in previous
analyzes we observe a significant influence of higher-order effects. The
accuracy of astrophysical S factors for the 7Be(p,gamma)8B reaction at stellar
energies extracted from breakup measurements therefore seems difficult to
evaluate.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 14:46:14 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Goldstein",
"G.",
""
],
[
"Capel",
"P.",
""
],
[
"Baye",
"D.",
""
]
] |
0708.0358 | Gian Luca Giorgi | Ferdinando de Pasquale, Gian Luca Giorgi | Entanglement, BEC, and superfluid-like behavior of two-mode photon
systems | null | null | 10.1140/epjst/e2008-00717-8 | null | quant-ph | null | A system of two interacting photon modes, without constraints on the photon
number, in the presence of a Kerr nonlinearity, exhibits BEC if the transfer
amplitude is greater than the mode frequency. A symmetry-breaking field (SBF)
can be introduced by taking into account a classical electron current. The
ground state, in the limit of small nonlinearity, becomes a squeezed state, and
thus the modes become entangled. The smaller is the SBF, the greater is
entanglement. Superfluid-like behavior is observed in the study of entanglement
growth from an initial coherent state, since in the short-time range the growth
does not depend on the SBF amplitude, and on the initial state amplitude. On
the other hand, the latter is the only parameter which determines entanglement
in the absence of the SBF.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 14:51:19 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"de Pasquale",
"Ferdinando",
""
],
[
"Giorgi",
"Gian Luca",
""
]
] |
0708.0359 | Andrei Kustarev | Andrei Kustarev | Geometric proof of Thom conjecture | This paper has been withdrawn by the author due a crucial sign error
in Theorem B | null | null | null | math.GT | null | This paper has been withdrawn by the author due a crucial sign error in
Theorem B. We present a geometric proof of Thom conjecture, which uses Khovanov
homology. Our approach doesn't use any analytic methods and is quite different
from proof given by Kronheimer and Mrowka in 1994.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 15:06:23 GMT"
},
{
"version": "v2",
"created": "Thu, 30 Aug 2007 07:58:44 GMT"
},
{
"version": "v3",
"created": "Sun, 10 Mar 2013 17:43:25 GMT"
}
] | 2013-03-12T00:00:00 | [
[
"Kustarev",
"Andrei",
""
]
] |
0708.0360 | Pablo Rom\'an | P. Roman and S. Simondi | The generalized matrix valued hypergeometric equation | null | null | null | null | math-ph math.MP math.RT | null | The matrix valued analog of the Euler's hypergeometric differential equation
was introduced by Tirao in \cite{T2}. This equation arises in the study of
matrix valued spherical functions and in the theory of matrix valued orthogonal
polynomials. The goal of this paper is to extend naturally the number of
parameters of Tirao's equation in order to get a generalized matrix valued
hypergeometric equation. We take advantage of the tools and strategies
developed in \cite{T2} to identify the corresponding matrix hypergeometric
functions ${}_nF_m$. We prove that, if n=m+1, this functions are analytic for
|z|<1 and we give a necesary condition for the convergence on the unit circle
|z|=1.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 15:08:57 GMT"
},
{
"version": "v2",
"created": "Fri, 10 Aug 2007 18:44:18 GMT"
},
{
"version": "v3",
"created": "Fri, 19 Oct 2007 14:39:44 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Roman",
"P.",
""
],
[
"Simondi",
"S.",
""
]
] |
0708.0361 | Grigoriev Evgeniy | Evgeniy Grigoriev | Why the relational data model can be considered as a formal basis for
group operations in object-oriented systems | 10 pages | null | null | null | cs.DB | null | Relational data model defines a specification of a type "relation". However,
its simplicity does not mean that the system implementing this model must
operate with structures having the same simplicity. We consider two principles
allowing create a system which combines object-oriented paradigm (OOP) and
relational data model (RDM) in one framework. The first principle -- "complex
data in encapsulated domains" -- is well known from The Third Manifesto by Date
and Darwen. The second principle --"data complexity in names"-- is the basis
for a system where data are described as complex objects and uniquely
represented as a set of relations. Names of these relations and names of their
attributes are combinations of names entered in specifications of the complex
objects. Below, we consider the main properties of such a system.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 15:24:29 GMT"
},
{
"version": "v2",
"created": "Fri, 3 Aug 2007 06:11:33 GMT"
},
{
"version": "v3",
"created": "Sun, 5 Aug 2007 22:38:53 GMT"
},
{
"version": "v4",
"created": "Tue, 7 Aug 2007 21:39:14 GMT"
},
{
"version": "v5",
"created": "Thu, 9 Aug 2007 04:56:59 GMT"
},
{
"version": "v6",
"created": "Thu, 9 Aug 2007 22:15:20 GMT"
},
{
"version": "v7",
"created": "Wed, 5 Sep 2007 20:18:51 GMT"
}
] | 2007-09-05T00:00:00 | [
[
"Grigoriev",
"Evgeniy",
""
]
] |
0708.0362 | Bo Henry Lindqvist | Bo Henry Lindqvist | On the Statistical Modeling and Analysis of Repairable Systems | Published at http://dx.doi.org/10.1214/088342306000000448 in the
Statistical Science (http://www.imstat.org/sts/) by the Institute of
Mathematical Statistics (http://www.imstat.org) | Statistical Science 2006, Vol. 21, No. 4, 532-551 | 10.1214/088342306000000448 | IMS-STS-STS211 | stat.ME | null | We review basic modeling approaches for failure and maintenance data from
repairable systems. In particular we consider imperfect repair models, defined
in terms of virtual age processes, and the trend-renewal process which extends
the nonhomogeneous Poisson process and the renewal process. In the case where
several systems of the same kind are observed, we show how observed covariates
and unobserved heterogeneity can be included in the models. We also consider
various approaches to trend testing. Modern reliability data bases usually
contain information on the type of failure, the type of maintenance and so
forth in addition to the failure times themselves. Basing our work on recent
literature we present a framework where the observed events are modeled as
marked point processes, with marks labeling the types of events. Throughout the
paper the emphasis is more on modeling than on statistical inference.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 15:13:56 GMT"
}
] | 2007-08-03T00:00:00 | [
[
"Lindqvist",
"Bo Henry",
""
]
] |
0708.0363 | Alice Fialowski | Alice Fialowski (Eotvos Lorand University, Budapest), Friedrich
Wagemann (Universite de Nantes, France) | Cohomology and deformations of the infinite dimensional filiform Lie
algebra m_2 | 17 pages | Journal of Algebra 319 (2008), 5125-5143 | null | null | math.RT math.RA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Denote $\fm_2$ the infinite dimensional $\N$-graded Lie algebra defined by
the basis $e_i$ for $i\geq 1$ and by relations $[e_1,e_i]=e_{i+1}$ for all
$i\geq 2$, $[e_2,e_j]=e_{j+2}$ for all $j\geq 3$. We compute in this article
the bracket structure on $H^1(\fm_2,\fm_2)$, $H^2(\fm_2,\fm_2)$ and in relation
to this, we establish that there are only finitely many true deformations of
$\fm_2$ in each weight by constructing them explicitely. It turns out that in
weight 0 one gets as non-trivial deformation only one formal non-converging
deformation.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 15:23:00 GMT"
},
{
"version": "v2",
"created": "Wed, 27 Aug 2008 09:39:11 GMT"
}
] | 2008-08-27T00:00:00 | [
[
"Fialowski",
"Alice",
"",
"Eotvos Lorand University, Budapest"
],
[
"Wagemann",
"Friedrich",
"",
"Universite de Nantes, France"
]
] |
0708.0364 | Roberto Alamino | Roberto C. Alamino, David Saad | The typical behaviour of relays | 8 pages, 8 figures | null | null | null | cond-mat.stat-mech cond-mat.other | null | The typical behaviour of the relay-without-delay channel and its many-units
generalisation, termed the relay array, under LDPC coding, is studied using
methods of statistical mechanics. A demodulate-and-forward strategy is
analytically solved using the replica symmetric ansatz which is exact in the
studied system at the Nishimori's temperature. In particular, the typical level
of improvement in communication performance by relaying messages is shown in
the case of small and large number of relay units.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 15:40:00 GMT"
}
] | 2007-08-03T00:00:00 | [
[
"Alamino",
"Roberto C.",
""
],
[
"Saad",
"David",
""
]
] |
0708.0365 | Andrew N. Jordan | Andrew N. Jordan and Alexander N. Korotkov | Uncollapsing the wavefunction | 8 pages, 4 figures, proceedings paper for Coherence and Quantum
Optics 9 | null | null | null | quant-ph cond-mat.mes-hall | null | The undoing of quantum measurements is discussed in the broader context of
irreversibility in physics. We give explicit examples of how a wavefunction can
be uncollapsed in two solid-state experimental set-ups. Wavefunction uncollapse
shows the quantum observer paradox in a new and significantly clearer way.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:03:29 GMT"
}
] | 2007-08-03T00:00:00 | [
[
"Jordan",
"Andrew N.",
""
],
[
"Korotkov",
"Alexander N.",
""
]
] |
0708.0366 | Gianluca Calcagni | Gianluca Calcagni, Giuseppe Nardelli | Tachyon solutions in boundary and cubic string field theory | 21 pages, 4 figures; v3: shorter version, contents rearranged and
simplified, spiky solution now discarded, novel interpretation of OSFT/BSFT
relation; v4: published version | Phys.Rev.D78:126010,2008 | 10.1103/PhysRevD.78.126010 | null | hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct rolling tachyon solutions of open and boundary string field
theory (OSFT and BSFT, respectively), in the bosonic and supersymmetric (susy)
case. The wildly oscillating solution of susy OSFT is recovered, together with
a family of time-dependent BSFT solutions for the bosonic and susy string.
These are parametrized by an arbitrary constant r involved in solving the Green
equation of the target fields. When r=0 we recover previous results in BSFT,
whereas for r attaining the value predicted by OSFT it is shown that the
bosonic OSFT solution is the derivative of the boundary one; in the
supersymmetric case the relation between the two solutions is more complicated.
This technical correspondence sheds some light on the nature of wild
oscillations, which appear in both theories whenever r>0.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 15:47:42 GMT"
},
{
"version": "v2",
"created": "Thu, 21 Feb 2008 14:59:43 GMT"
},
{
"version": "v3",
"created": "Fri, 8 Aug 2008 14:47:26 GMT"
},
{
"version": "v4",
"created": "Tue, 30 Dec 2008 23:26:00 GMT"
}
] | 2009-04-03T00:00:00 | [
[
"Calcagni",
"Gianluca",
""
],
[
"Nardelli",
"Giuseppe",
""
]
] |
0708.0367 | Mehreen Mahmud | Mehreen Mahmud, Denise Gabuzda and Vladislavs Bezrukovs | Surprising Evolution of Faraday Rotation Gradients in the Jet of
1803+784 | 5 pages for the proceedings for 'Extragalactic Jets, Theory and
Observation from Radio to Gamma Ray.' (21-24 May 2007, Alaska) | null | null | null | astro-ph | null | Several multi-frequency polarization studies have shown the presence of
systematic Faraday Rotation gradients across the parsec-scale jets of Active
Galactic Nuclei (AGN), taken to be due to the systematic variation of the
line-of-sight component of a helical magnetic field across the jet. Other
studies have confirmed the presence and sense of these gradients in several
sources, thus providing evidence that these gradients persist over time and
over large distances from the core. However, we find surprising new evidence
for a reversal in the direction of the Faraday Rotation gradient across the jet
of 1803+784, for which multi-wavelength polarization observations are available
at four epochs. At all four epochs, we observe transverse Rotation Measure (RM)
gradients across the jet, consistent with the presence of a helical magnetic
field wrapped around the jet. However, we also observe a ''flip'' in the
direction of the gradient between June 2000 and August 2002. Although the
origins of this phenomena are not understood, one way to interpret this change
is if the sense of rotation of the central supermassive black hole and
accretion disc has remained the same, but the dominant magnetic pole facing the
Earth has changed from North to South.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 15:59:03 GMT"
}
] | 2007-08-03T00:00:00 | [
[
"Mahmud",
"Mehreen",
""
],
[
"Gabuzda",
"Denise",
""
],
[
"Bezrukovs",
"Vladislavs",
""
]
] |
0708.0368 | Martin Rosvall | M. Rosvall, K. Sneppen | Dynamics of Opinions and Social Structures | 4 pages and 2 figures. For Java applet and a detailed model
description, see http://cmol.nbi.dk/models/ibattle/ibattle.html | null | null | null | physics.soc-ph | null | Social groups with widely different music tastes, political convictions, and
religious beliefs emerge and disappear on scales from extreme subcultures to
mainstream mass-cultures. Both the underlying social structure and the
formation of opinions are dynamic and changes in one affect the other. Several
positive feedback mechanisms have been proposed to drive the diversity in
social and economic systems, but little effort has been devoted to pinpoint the
interplay between a dynamically changing social network and the spread and
gathering of information on the network. Here we analyze this phenomenon in
terms of a social network-model that explicitly simulates the feedback between
information assembly and emergence of social structures: changing beliefs are
coupled to changing relationships because agents self-organize a dynamic
network to facilitate their hunter-gatherer behavior in information space. Our
analysis demonstrates that tribal organizations and modular social networks can
emerge as a result of contact-seeking agents that reinforce their beliefs among
like-minded. We also find that prestigious persons can streamline the social
network into hierarchical structures around themselves.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:09:26 GMT"
},
{
"version": "v2",
"created": "Mon, 12 Nov 2007 02:56:34 GMT"
}
] | 2007-11-12T00:00:00 | [
[
"Rosvall",
"M.",
""
],
[
"Sneppen",
"K.",
""
]
] |
0708.0369 | Luis A. Escobar | Luis A. Escobar, William Q. Meeker | A Review of Accelerated Test Models | Published at http://dx.doi.org/10.1214/088342306000000321 in the
Statistical Science (http://www.imstat.org/sts/) by the Institute of
Mathematical Statistics (http://www.imstat.org) | Statistical Science 2006, Vol. 21, No. 4, 552-577 | 10.1214/088342306000000321 | IMS-STS-STS209 | stat.ME | null | Engineers in the manufacturing industries have used accelerated test (AT)
experiments for many decades. The purpose of AT experiments is to acquire
reliability information quickly. Test units of a material, component, subsystem
or entire systems are subjected to higher-than-usual levels of one or more
accelerating variables such as temperature or stress. Then the AT results are
used to predict life of the units at use conditions. The extrapolation is
typically justified (correctly or incorrectly) on the basis of physically
motivated models or a combination of empirical model fitting with a sufficient
amount of previous experience in testing similar units. The need to extrapolate
in both time and the accelerating variables generally necessitates the use of
fully parametric models. Statisticians have made important contributions in the
development of appropriate stochastic models for AT data [typically a
distribution for the response and regression relationships between the
parameters of this distribution and the accelerating variable(s)], statistical
methods for AT planning (choice of accelerating variable levels and allocation
of available test units to those levels) and methods of estimation of suitable
reliability metrics. This paper provides a review of many of the AT models that
have been used successfully in this area.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:11:49 GMT"
}
] | 2007-08-03T00:00:00 | [
[
"Escobar",
"Luis A.",
""
],
[
"Meeker",
"William Q.",
""
]
] |
0708.0370 | David Anderson | David F. Anderson | A modified Next Reaction Method for simulating chemical systems with
time dependent propensities and delays | 25 pages, 1 figure. Some minor changes made to add clarity | null | 10.1063/1.2799998 | null | q-bio.MN q-bio.QM | null | Chemical reaction systems with a low to moderate number of molecules are
typically modeled as discrete jump Markov processes. These systems are
oftentimes simulated with methods that produce statistically exact sample paths
such as the Gillespie Algorithm or the Next Reaction Method. In this paper we
make explicit use of the fact that the initiation times of the reactions can be
represented as the firing times of independent, unit rate Poisson processes
with internal times given by integrated propensity functions. Using this
representation we derive a modified Next Reaction Method and, in a way that
achieves efficiency over existing approaches for exact simulation, extend it to
systems with time dependent propensities as well as to systems with delays.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:19:10 GMT"
},
{
"version": "v2",
"created": "Fri, 31 Aug 2007 19:45:03 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Anderson",
"David F.",
""
]
] |
0708.0371 | Michele Correggi | M. Correggi, G. Dell'Antonio, D. Finco | Spectral Analysis of a Two Body Problem with Zero Range Perturbation | Version submitted for publication, AMStex, 22 pages | J. Funct. Anal. 255 (2008), 502-531 | 10.1016/j.jfa.2008.04.005 | null | math-ph math.MP | null | We consider a class of singular, zero-range perturbations of the Hamiltonian
of a quantum system composed by a test particle and a harmonic oscillators in
dimension one, two and three and we study its spectrum. In facts we give a
detailed characterization of point spectrum and its asymptotic behavior with
respect to the parameters entering the Hamiltonian. We also partially describe
the positive spectrum and scattering properties of the Hamiltonian.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:14:37 GMT"
},
{
"version": "v2",
"created": "Fri, 5 Oct 2007 09:04:04 GMT"
}
] | 2008-06-27T00:00:00 | [
[
"Correggi",
"M.",
""
],
[
"Dell'Antonio",
"G.",
""
],
[
"Finco",
"D.",
""
]
] |
0708.0372 | Tomohiro Hasumi | Tomohiro Hasumi | Interoccurrence time statistics in the two-dimensional Burridge-Knopoff
earthquake model | 10 pages, 8 figures | Phys. Rev. E 76, 026117 (2007) | 10.1103/PhysRevE.76.026117 | null | cond-mat.stat-mech | null | We have numerically investigated statistical properties of the so-called
interoccurrence time or the waiting time, i.e., the time interval between
successive earthquakes, based on the two-dimensional (2-D) spring-block
(Burridge-Knopoff) model, selecting the velocity-weakening property as the
constitutive friction law. The statistical properties of frequency distribution
and the cumulative distribution of the interoccurrence time are discussed by
tuning the dynamical parameters, namely, a stiffness and frictional property of
a fault. We optimize these model parameters to reproduce the interoccurrence
time statistics in nature; the frequency and cumulative distribution can be
described by the power law and Zipf-Mandelbrot type power law, respectively. In
an optimal case, the b-value of the Gutenberg-Richter law and the ratio of wave
propagation velocity are in agreement with those derived from real earthquakes.
As the threshold of magnitude is increased, the interoccurrence time
distribution tends to follow an exponential distribution. Hence it is suggested
that a temporal sequence of earthquakes, aside from small-magnitude events, is
a Poisson process, which is observed in nature. We found that the
interoccurrence time statistics derived from the 2-D BK (original) model can
efficiently reproduce that of real earthquakes, so that the model can be
recognized as a realistic one in view of interoccurrence time statistics.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 13:07:36 GMT"
},
{
"version": "v2",
"created": "Thu, 30 Aug 2007 17:57:28 GMT"
}
] | 2007-08-30T00:00:00 | [
[
"Hasumi",
"Tomohiro",
""
]
] |
0708.0373 | Chad Middleton | Keith Andrew, Brett Bolen, and Chad A. Middleton | Solutions of Higher Dimensional Gauss-Bonnet FRW Cosmology | 10 pages, references added/corrected, accepted for publication in
General Relativity and Gravitation | Gen.Rel.Grav.39:2061-2071,2007 | 10.1007/s10714-007-0502-7 | null | gr-qc hep-th | null | We examine the effect on cosmological evolution of adding a Gauss-Bonnet term
to the standard Einstein-Hilbert action for a (1 + 3)+ d dimensional
Friedman-Robertson-Walker (FRW) metric. By assuming that the additional
dimensions compactify as a power law as the usual 3 spatial dimensions expand,
we solve the resulting dynamical equations and find that the solution may be of
either de Sitter or Kasner form depending upon whether the Gauss-Bonnet term or
the Einstein term dominates.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:19:21 GMT"
},
{
"version": "v2",
"created": "Tue, 21 Aug 2007 17:00:23 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Andrew",
"Keith",
""
],
[
"Bolen",
"Brett",
""
],
[
"Middleton",
"Chad A.",
""
]
] |
0708.0374 | Mike Todd | Henk Bruin and Mike Todd | Equilibrium states for potentials with $\sup\phi - \inf\phi < \htop(f)$ | Added Lemma 6 to deal with the disparity between leading eigenvalues
and operator norms. Added extra references and corrected some typos | Commun. Math. Phys. 283 (2008) 579-611 | 10.1007/s00220-008-0596-0 | null | math.DS | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the context of smooth interval maps, we study an inducing scheme approach
to prove existence and uniqueness of equilibrium states for potentials $\phi$
with he `bounded range' condition $\sup \phi - \inf \phi < \htop$, first used
by Hofbauer and Keller. We compare our results to Hofbauer and Keller's use of
Perron-Frobenius operators. We demonstrate that this `bounded range' condition
on the potential is important even if the potential is H\"older continuous. We
also prove analyticity of the pressure in this context.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:22:28 GMT"
},
{
"version": "v2",
"created": "Thu, 14 Aug 2008 13:34:33 GMT"
}
] | 2008-08-28T00:00:00 | [
[
"Bruin",
"Henk",
""
],
[
"Todd",
"Mike",
""
]
] |
0708.0375 | Mannan Ali | M. Ali, C. H. Marrows, and B. J. Hickey | Controlled enhancement or suppression of exchange biasing using impurity
$\delta$-layers | null | null | 10.1103/PhysRevB.77.134401 | null | cond-mat.other cond-mat.mtrl-sci | null | The effects of inserting impurity $\delta$-layers of various elements into a
Co/IrMn exchange biased bilayer, at both the interface, and at given points
within the IrMn layer a distance from the interface, has been investigated.
Depending on the chemical species of dopant, and its position, we found that
the exchange biasing can be either strongly enhanced or suppressed. We show
that biasing is enhanced with a dusting of certain magnetic impurities, present
at either at the interface or sufficiently far away from the Co/IrMn interface.
This illustrates that the final spin structure at the Co/IrMn interface is not
only governed by interface structure/roughness but is also mediated by local
exchange or anisotropy variations within the bulk of the IrMn.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:32:11 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ali",
"M.",
""
],
[
"Marrows",
"C. H.",
""
],
[
"Hickey",
"B. J.",
""
]
] |
0708.0376 | Gagan Mohanty | The BABAR Collaboration: B. Aubert, et al | Observation of the Decay B+ --> K+K-pi+ | 7 pages, 5 postscript figures, published in PRL | Phys.Rev.Lett.99:221801,2007 | 10.1103/PhysRevLett.99.221801 | BABAR-PUB-07/041, SLAC-PUB-12702 | hep-ex | null | We report the observation of charmless hadronic decays of charged B mesons to
the final state K+K-pi+. Using a data sample of 347.5 fb^-1 collected at the
Y(4S) resonance with the BABAR detector, we observe 429+/-43 signal events with
a significance of 9.6 sigma. We measure the inclusive branching fraction BF(B+
--> K+K-pi+) = [5.0+/-0.5(stat)+/-0.5(syst)]x10^-6. Inspection of the Dalitz
plot of signal candidates shows a broad structure peaking near 1.5 GeV/c^2 in
the K+K- invariant mass distribution. We find the direct CP asymmetry to be
consistent with zero.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 19:39:31 GMT"
},
{
"version": "v2",
"created": "Fri, 3 Aug 2007 09:56:31 GMT"
},
{
"version": "v3",
"created": "Thu, 29 Nov 2007 12:59:49 GMT"
}
] | 2010-04-12T00:00:00 | [
[
"The BABAR Collaboration",
"",
""
],
[
"Aubert",
"B.",
""
]
] |
0708.0377 | David Anderson | David F. Anderson | Incorporating postleap checks in tau-leaping | Final version. Minor changes | null | 10.1063/1.2819665 | null | q-bio.MN q-bio.QM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | By explicitly representing the reaction times of discrete chemical systems as
the firing times of independent, unit rate Poisson processes, we develop a new
adaptive tau-leaping procedure. The procedure developed is novel in that
accuracy is guaranteed by performing postleap checks. Because the
representation we use separates the randomness of the model from the state of
the system, we are able to perform the postleap checks in such a way that the
statistics of the sample paths generated will not be biased by the rejections
of leaps. Further, since any leap condition is ensured with a probability of
one, the simulation method naturally avoids negative population values
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:36:27 GMT"
},
{
"version": "v2",
"created": "Tue, 25 Sep 2007 03:59:25 GMT"
},
{
"version": "v3",
"created": "Tue, 30 Oct 2007 01:47:58 GMT"
},
{
"version": "v4",
"created": "Mon, 18 Aug 2008 15:34:52 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Anderson",
"David F.",
""
]
] |
0708.0378 | Paul Kvam | Paul Kvam | A Conversation With Harry Martz | Published at http://dx.doi.org/10.1214/088342306000000646 in the
Statistical Science (http://www.imstat.org/sts/) by the Institute of
Mathematical Statistics (http://www.imstat.org) | Statistical Science 2006, Vol. 21, No. 4, 578-585 | 10.1214/088342306000000646 | IMS-STS-STS213 | stat.ME | null | Harry F. Martz was born June 16, 1942 and grew up in Cumberland, Maryland. He
received a Bachelor of Science degree in mathematics (with a minor in physics)
from Frostburg State University in 1964, and earned a Ph.D. in statistics at
Virginia Polytechnic Institute and State University in 1968. He started his
statistics career at Texas Tech University's Department of Industrial
Engineering and Statistics right after graduation. In 1978, he joined the
technical staff at Los Alamos National Laboratory (LANL) in Los Alamos, New
Mexico after first working as Full Professor in the Department of Industrial
Engineering at Utah State University in the fall of 1977. He has had a prolific
23-year career with the statistics group at LANL; over the course of his
career, Martz has published over 80 research papers in books and refereed
journals, one book (with co-author Ray Waller), and has four patents associated
with his work at LANL. He is a fellow of the American Statistical Association
and has received numerous awards, including the Technometrics Frank Wilcoxon
Prize for Best Applications Paper (1996), Los Alamos National Laboratory
Achievement Award (1998), R&D 100 Award by R&D Magazine (2003), Council for
Chemical Research Collaboration Success Award (2004), and Los Alamos National
Laboratory's Distinguished Licensing Award (2004). Since retiring as a
Technical Staff member at LANL in 2001, he has worked as a LANL Laboratory
Associate.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:41:04 GMT"
}
] | 2007-08-03T00:00:00 | [
[
"Kvam",
"Paul",
""
]
] |
0708.0379 | Mike Todd | Henk Bruin and Mike Todd | Return time statistics for invariant measures for interval maps with
positive Lyapunov exponent | Proof of Proposition 5 simplified | Stoch. Dyn. 9 (2009) 81-100 | null | null | math.DS | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove that multimodal maps with an absolutely continuous invariant measure
have exponential return time statistics around a.e. point. We also show a
`polynomial Gibbs property' for these systems, and that the convergence to the
entropy in the Ornstein-Weiss formula has normal fluctuations. These results
are also proved for equilibrium states of some Hoelder potentials.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:43:19 GMT"
},
{
"version": "v2",
"created": "Mon, 18 Feb 2008 16:56:06 GMT"
},
{
"version": "v3",
"created": "Mon, 20 Apr 2009 17:21:40 GMT"
}
] | 2009-04-20T00:00:00 | [
[
"Bruin",
"Henk",
""
],
[
"Todd",
"Mike",
""
]
] |
0708.0380 | David Anderson | David F. Anderson and Jonathan C. Mattingly | Propagation of Fluctuations in Biochemical Systems, II: Nonlinear Chains | 36 pages, 1 figure | null | null | null | math.PR math.DS | null | We consider biochemical reaction chains and investigate how random external
fluctuations, as characterized by variance and coefficient of variation,
propagate down the chains. We perform such a study under the assumption that
the number of molecules is high enough so that the behavior of the
concentrations of the system is well approximated by differential equations. We
conclude that the variances and coefficients of variation of the fluxes will
decrease as one moves down the chain and, through an example, show that there
is no corresponding result for the variances of the chemical species. We also
prove that the fluctuations of the fluxes as characterized by their time
averages decrease down reaction chains. The results presented give insight into
how biochemical reaction systems are buffered against external perturbations
solely by their underlying graphical structure and point out the benefits of
studying the out-of-equilibrium dynamics of systems.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:46:07 GMT"
}
] | 2007-08-03T00:00:00 | [
[
"Anderson",
"David F.",
""
],
[
"Mattingly",
"Jonathan C.",
""
]
] |
0708.0381 | Ernie Croot | Ernie Croot and Tomasz Schoen | On Sumsets and Spectral Gaps | A few typos have been corrected. Also theorem 2 in the last draft
should have said ``t >= 3'', not ``t >= 2'' | null | null | null | math.CO math.NT | null | It is well known that if S is a subset of the integers mod p, and if the
second-largest Fourier coefficient is ``small'' relative to the largest
coefficient, then the sumset S+S is much larger than S. We show in the present
paper that if instead of having such a large ``spectral gap'' between the
largest and second-largest Fourier coefficients, we had it between the kth
largest and the (k+1)st largest, the same thing holds true, namely that |S+S|
is appreciably larger than |S|. Well, we only do this for k < (log p)/(log 4).
We also obtain analogous results for repeated sumsets S+S+...+S, and it turns
out that the more terms one includes, the larger the index k that can be used.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:48:22 GMT"
},
{
"version": "v2",
"created": "Tue, 27 Nov 2007 19:12:56 GMT"
},
{
"version": "v3",
"created": "Wed, 28 Nov 2007 16:19:09 GMT"
}
] | 2007-11-28T00:00:00 | [
[
"Croot",
"Ernie",
""
],
[
"Schoen",
"Tomasz",
""
]
] |
0708.0382 | Hao Wang | Hao Wang, D. N. Sheng, L. Sheng and F. D. M. Haldane | Broken-Symmetry States of Dirac Fermions in Graphene with A Partially
Filled High Landau Level | Contains are slightly changed. Journal reference and DOI are added | PRL 100, 116802 (2008) | 10.1103/PhysRevLett.100.116802 | null | cond-mat.str-el cond-mat.mes-hall | null | We report on numerical study of the Dirac fermions in partially filled N=3
Landau level (LL) in graphene. At half-filling, the equal-time density-density
correlation function displays sharp peaks at nonzero wavevectors $\pm {\bf
q^{*}}$. Finite-size scaling shows that the peak value grows with electron
number and diverges in the thermodynamic limit, which suggests an instability
toward a charge density wave. A symmetry broken stripe phase is formed at large
system size limit, which is robust against purturbation from disorder
scattering. Such a quantum phase is experimentally observable through transport
measurements. Associated with the special wavefunctions of the Dirac LL, both
stripe and bubble phases become possible candidates for the ground state of the
Dirac fermions in graphene with lower filling factors in the N=3 LL.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:50:08 GMT"
},
{
"version": "v2",
"created": "Sun, 5 Aug 2007 06:06:16 GMT"
},
{
"version": "v3",
"created": "Fri, 28 Mar 2008 21:47:35 GMT"
}
] | 2008-03-31T00:00:00 | [
[
"Wang",
"Hao",
""
],
[
"Sheng",
"D. N.",
""
],
[
"Sheng",
"L.",
""
],
[
"Haldane",
"F. D. M.",
""
]
] |
0708.0383 | Dumitru Ghilencea | I. Antoniadis, E. Dudas, D. M. Ghilencea | Supersymmetric Models with Higher Dimensional Operators | 36 pages; some clarifications and references added | JHEP 0803:045,2008 | 10.1088/1126-6708/2008/03/045 | CPHT-RR084.0807, CERN-PH-TH/2007-133, OUTP-0707P | hep-th hep-ph | null | In 4D renormalisable theories, integrating out massive states generates in
the low energy effective action higher dimensional operators (derivative or
otherwise). Using a superfield language it is shown that a 4D N=1
supersymmetric theory with higher derivative operators in either the Kahler or
the superpotential part of the Lagrangian and with an otherwise arbitrary
superpotential, is equivalent to a 4D N=1 theory of second order (i.e. without
higher derivatives) with additional superfields and renormalised interactions.
We provide examples where a free theory with trivial supersymmetry breaking
provided by a linear superpotential becomes, in the presence of higher
derivatives terms and in the second order version, a non-trivial interactive
one with spontaneous supersymmetry breaking. The couplings of the equivalent
theory acquire a threshold correction through their dependence on the scale of
the higher dimensional operator(s). The scalar potential in the second order
theory is not necessarily positive definite, and one can in principle have a
vanishing potential with broken supersymmetry. We provide an application to
MSSM and argue that at tree-level and for a mass scale associated to a higher
derivative term in the TeV range, the Higgs mass can be lifted above the
current experimental limits.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:50:20 GMT"
},
{
"version": "v2",
"created": "Mon, 3 Mar 2008 17:58:35 GMT"
}
] | 2009-04-03T00:00:00 | [
[
"Antoniadis",
"I.",
""
],
[
"Dudas",
"E.",
""
],
[
"Ghilencea",
"D. M.",
""
]
] |
0708.0384 | Mohammad H. S. Amin | M. H. S. Amin, Dmitri V. Averin, James A. Nesteroff | Decoherence in adiabatic quantum computation | 4 pages, 2 figures, published version | Phys. Rev. A 79, 022107 (2009) | 10.1103/PhysRevA.79.022107 | null | cond-mat.mes-hall quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have studied the decoherence properties of adiabatic quantum computation
(AQC) in the presence of in general non-Markovian, e.g., low-frequency, noise.
The developed description of the incoherent Landau-Zener transitions shows that
the global AQC maintains its properties even for decoherence larger than the
minimum gap at the anticrossing of the two lowest energy levels. The more
efficient local AQC, however, does not improve scaling of the computation time
with the number of qubits $n$ as in the decoherence-free case. The scaling
improvement requires phase coherence throughout the computation, limiting the
computation time and the problem size n.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 18:41:26 GMT"
},
{
"version": "v2",
"created": "Mon, 14 Jul 2008 22:26:30 GMT"
},
{
"version": "v3",
"created": "Wed, 25 Mar 2009 17:57:53 GMT"
}
] | 2013-05-29T00:00:00 | [
[
"Amin",
"M. H. S.",
""
],
[
"Averin",
"Dmitri V.",
""
],
[
"Nesteroff",
"James A.",
""
]
] |
0708.0385 | Richard A. Olshen | Richard A. Olshen | Tree-structured regression and the differentiation of integrals | Published at http://dx.doi.org/10.1214/009053606000001000 in the
Annals of Statistics (http://www.imstat.org/aos/) by the Institute of
Mathematical Statistics (http://www.imstat.org) | Annals of Statistics 2007, Vol. 35, No. 1, 1-12 | 10.1214/009053606000001000 | IMS-AOS-AOS0223 | math.ST stat.TH | null | This paper provides answers to questions regarding the almost sure limiting
behavior of rooted, binary tree-structured rules for regression. Examples show
that questions raised by Gordon and Olshen in 1984 have negative answers. For
these examples of regression functions and sequences of their associated binary
tree-structured approximations, for all regression functions except those in a
set of the first category, almost sure consistency fails dramatically on events
of full probability. One consequence is that almost sure consistency of binary
tree-structured rules such as CART requires conditions beyond requiring that
(1) the regression function be in ${\mathcal {L}}^1$, (2) partitions of a
Euclidean feature space be into polytopes with sides parallel to coordinate
axes, (3) the mesh of the partitions becomes arbitrarily fine almost surely and
(4) the empirical learning sample content of each polytope be ``large enough.''
The material in this paper includes the solution to a problem raised by Dudley
in discussions. The main results have a corollary regarding the lack of almost
sure consistency of certain Bayes-risk consistent rules for classification.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:55:24 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Olshen",
"Richard A.",
""
]
] |
0708.0386 | Sheng Yang | Sheng Yang and Jean-Claude Belfiore | Diversity of MIMO Multihop Relay Channels | 62 pages, 10 figures, submitted to the IEEE transactions on
Information Theory. Updated version of "Diversity of MIMO Multihop Relay
Channels - Part I: Amplify-and-Forward" | null | null | null | cs.IT math.IT | null | We consider slow fading relay channels with a single multi-antenna
source-destination terminal pair. The source signal arrives at the destination
via N hops through N-1 layers of relays. We analyze the diversity of such
channels with fixed network size at high SNR. In the clustered case where the
relays within the same layer can have full cooperation, the cooperative
decode-and-forward (DF) scheme is shown to be optimal in terms of the
diversity-multiplexing tradeoff (DMT). The upper bound on the DMT, the cut-set
bound, is attained. In the non-clustered case, we show that the naive
amplify-and-forward (AF) scheme has the maximum multiplexing gain of the
channel but is suboptimal in diversity, as compared to the cut-set bound. To
improve the diversity, space-time relay processing is introduced through the
parallel partition of the multihop channel. The idea is to let the source
signal go through K different "AF paths" in the multihop channel. This parallel
AF scheme creates a parallel channel in the time domain and has the maximum
diversity if the partition is properly designed. Since this scheme does not
achieve the maximum multiplexing gain in general, we propose a flip-and-forward
(FF) scheme that is built from the parallel AF scheme. It is shown that the FF
scheme achieves both the maximum diversity and multiplexing gains in a
distributed multihop channel of arbitrary size. In order to realize the DMT
promised by the relaying strategies, approximately universal coding schemes are
also proposed.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 16:59:21 GMT"
}
] | 2007-08-03T00:00:00 | [
[
"Yang",
"Sheng",
""
],
[
"Belfiore",
"Jean-Claude",
""
]
] |
0708.0387 | Benjamin Joachimi | B. Joachimi, P. Schneider and T. Eifler (Argelander-Institut f\"ur
Astronomie, Universit\"at Bonn) | Analysis of two-point statistics of cosmic shear: III. Covariances of
shear measures made easy | 15 pages, including 4 figures (Fig. 3 reduced in quality); minor
changes, Fig. 4 extended; published in A&A | A&A 477, 43-54 (2008) | 10.1051/0004-6361:20078400 | null | astro-ph | null | In recent years cosmic shear, the weak gravitational lensing effect by the
large-scale structure of the Universe, has proven to be one of the
observational pillars on which the cosmological concordance model is founded.
Several cosmic shear statistics have been developed in order to analyze data
from surveys. For the covariances of the prevalent second-order measures we
present simple and handy formulae, valid under the assumptions of Gaussian
density fluctuations and a simple survey geometry. We also formulate these
results in the context of shear tomography, i.e. the inclusion of redshift
information, and generalize them to arbitrary data field geometries. We define
estimators for the E- and B-mode projected power spectra and show them to be
unbiased in the case of Gaussianity and a simple survey geometry. From the
covariance of these estimators we demonstrate how to derive covariances of
arbitrary combinations of second-order cosmic shear measures. We then
recalculate the power spectrum covariance for general survey geometries and
examine the bias thereby introduced on the estimators for exemplary
configurations. Our results for the covariances are considerably simpler than
and analytically shown to be equivalent to the real-space approach presented in
the first paper of this series. We find good agreement with other numerical
evaluations and confirm the general properties of the covariance matrices. The
studies of the specific survey configurations suggest that our simplified
covariances may be employed for realistic survey geometries to good
approximation.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 17:40:39 GMT"
},
{
"version": "v2",
"created": "Wed, 12 Mar 2008 13:58:48 GMT"
}
] | 2008-03-12T00:00:00 | [
[
"Joachimi",
"B.",
"",
"Argelander-Institut für\n Astronomie, Universität Bonn"
],
[
"Schneider",
"P.",
"",
"Argelander-Institut für\n Astronomie, Universität Bonn"
],
[
"Eifler",
"T.",
"",
"Argelander-Institut für\n Astronomie, Universität Bonn"
]
] |
0708.0388 | Tomas Kopf | T.Kopf, M.Paschke | Generally covariant quantum mechanics on noncommutative configuration
spaces | 20 pages | null | 10.1063/1.2804075 | null | math-ph math.MP | null | We generalize the previously given algebraic version of "Feynman's proof of
Maxwell's equations" to noncommutative configuration spaces. By doing so, we
also obtain an axiomatic formulation of nonrelativistic quantum mechanics over
such spaces, which, in contrast to most examples discussed in the literature,
does not rely on a distinguished set of coordinates. We give a detailed account
of several examples, e.g., of nonabelian Yang-Mills theories, and of
noncommutative tori. Moreover we, examine models over the Moyal-deformed plane.
Assuming the conservation of electrical charges, we show that in this case the
canonical uncertainty relation [x_k, \dot{x}_l] = ig_{kl} with metric g_{kl} is
only consistent if g_{kl} is constant.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 17:12:47 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kopf",
"T.",
""
],
[
"Paschke",
"M.",
""
]
] |
0708.0389 | Rouin Farshchi | R. Farshchi, P. D. Ashby, D. J. Hwang, C. P. Grigoropoulos, R.V.
Chopdekar, Y. Suzuki, and O.D. Dubon | Hydrogen patterning of Ga1-xMnxAs for planar spintronics | ICDS-24, July 2007. 8 pages with 4 figures | null | 10.1016/j.physb.2007.08.208 | null | cond-mat.mtrl-sci | null | We demonstrate two patterning techniques based on hydrogen passivation of
Ga1-xMnxAs to produce isolated ferromagnetically active regions embedded
uniformly in a paramagnetic, insulating host. The first method consists of
selective hydrogenation of Ga1-xMnxAs by lithographic masking. Magnetotransport
measurements of Hall-bars made in this manner display the characteristic
properties of the hole-mediated ferromagnetic phase, which result from good
pattern isolation. Arrays of Ga1-xMnxAs dots as small as 250 nm across have
been realized by this process. The second process consists of blanket
hydrogenation of Ga1-xMnxAs followed by local reactivation using confined
low-power pulsed-laser annealing. Conductance imaging reveals local electrical
reactivation of micrometer-sized regions that accompanies the restoration of
ferromagnetism. The spatial resolution achievable with this method can
potentially reach <100 nm by employing near-field laser processing. The high
spatial resolution attainable by hydrogenation patterning enables the
development of systems with novel functionalities such as lateral
spin-injection as well as the exploration of magnetization dynamics in
individual and coupled structures made from this novel class of semiconductors.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 17:13:34 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Farshchi",
"R.",
""
],
[
"Ashby",
"P. D.",
""
],
[
"Hwang",
"D. J.",
""
],
[
"Grigoropoulos",
"C. P.",
""
],
[
"Chopdekar",
"R. V.",
""
],
[
"Suzuki",
"Y.",
""
],
[
"Dubon",
"O. D.",
""
]
] |
0708.0390 | Jos\'{e} R. Berrendero | Jos\'e R. Berrendero, Beatriz V. M. Mendes, David E. Tyler | On the maximum bias functions of MM-estimates and constrained
M-estimates of regression | Published at http://dx.doi.org/10.1214/009053606000000975 in the
Annals of Statistics (http://www.imstat.org/aos/) by the Institute of
Mathematical Statistics (http://www.imstat.org) | Annals of Statistics 2007, Vol. 35, No. 1, 13-40 | 10.1214/009053606000000975 | IMS-AOS-AOS0162 | math.ST stat.TH | null | We derive the maximum bias functions of the MM-estimates and the constrained
M-estimates or CM-estimates of regression and compare them to the maximum bias
functions of the S-estimates and the $\tau$-estimates of regression. In these
comparisons, the CM-estimates tend to exhibit the most favorable
bias-robustness properties. Also, under the Gaussian model, it is shown how one
can construct a CM-estimate which has a smaller maximum bias function than a
given S-estimate, that is, the resulting CM-estimate dominates the S-estimate
in terms of maxbias and, at the same time, is considerably more efficient.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 17:15:07 GMT"
}
] | 2009-09-29T00:00:00 | [
[
"Berrendero",
"José R.",
""
],
[
"Mendes",
"Beatriz V. M.",
""
],
[
"Tyler",
"David E.",
""
]
] |
0708.0391 | Stanislava Bartasiute | S. Bartasiute, V. Deveikis, V. Straizys, A. Bogdanovicius | Seven-color Vilnius photometry of the open cluster NGC 752 | 28 pages, 7 figures, accepted for Baltic Astronomy | BalticAstron.16:199-226,2007 | null | null | astro-ph | null | New photoelectric seven-color observations in the Vilnius system are
presented for 65 stars in the region of the open cluster NGC 752. Based on
individual stars with accurate photometric classifications, we determine the
apparent distance modulus (m-M)=8.38 and the mean reddening to the cluster
E(Y-V)=0.027, or E(B-V)=0.034. The mean photometric metallicity for the
main-sequence stars, [Fe/H]=-0.14, is found to be slightly lower than that
derived for the red clump giants, [Fe/H]=-0.08. This difference suggests that
red giants in later evolutionary phases may not have zero-age surface values of
[Fe/H]. We made use of the least-squares minimization techniques to fit the
Padova theoretical isochrones to the CMD, when the binary star population is
taken into account. By varying the distance modulus, metallicity and age, the
best match has been found between the seven magnitudes and colors of the
observed stars and those of model binaries, which gives the distance modulus by
0.2 mag smaller than that derived from individual stars, i.e., (m-M)=8.18, a
closely similar metallicity ([Fe/H]=-0.12), and age of 1.6 Gyr. With these
results, the fraction of photometric binaries among the main-sequence stars is
~40%.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 17:55:56 GMT"
},
{
"version": "v2",
"created": "Thu, 2 Aug 2007 21:12:30 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Bartasiute",
"S.",
""
],
[
"Deveikis",
"V.",
""
],
[
"Straizys",
"V.",
""
],
[
"Bogdanovicius",
"A.",
""
]
] |
0708.0392 | Ariel Edery | Ariel Edery and Ilana MacDonald | Cancellation of nonrenormalizable hypersurface divergences and the
d-dimensional Casimir piston | 29 pages; 3 figures; references added; to appear in JHEP | JHEP 0709:005,2007 | 10.1088/1126-6708/2007/09/005 | null | hep-th math-ph math.MP quant-ph | null | Using a multidimensional cut-off technique, we obtain expressions for the
cut-off dependent part of the vacuum energy for parallelepiped geometries in
any spatial dimension d. The cut-off part yields nonrenormalizable hypersurface
divergences and we show explicitly that they cancel in the Casimir piston
scenario in all dimensions. We obtain two different expressions for the
d-dimensional Casimir force on the piston where one expression is more
convenient to use when the plate separation a is large and the other when a is
small (a useful $a \to 1/a$ duality). The Casimir force on the piston is found
to be attractive (negative) for any dimension d. We apply the d-dimensional
formulas (both expressions) to the two and three-dimensional Casimir piston
with Neumann boundary conditions. The 3D Neumann results are in numerical
agreement with those recently derived in arXiv:0705.0139 using an optical path
technique providing an independent confirmation of our multidimensional
approach. We limit our study to massless scalar fields.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 19:10:35 GMT"
},
{
"version": "v2",
"created": "Wed, 29 Aug 2007 23:50:43 GMT"
}
] | 2009-04-03T00:00:00 | [
[
"Edery",
"Ariel",
""
],
[
"MacDonald",
"Ilana",
""
]
] |
0708.0393 | Norma Sanchez | D. J. Cirilo-Lombardo (Bogoliubov Laboratory JINR, Dubna) and N.G.
Sanchez (Observatoire de Paris LERMA) | Microcanonical model for a gaz of evaporating black holes and strings,
scattering amplitudes and mass spectrum | New material, 20 pages, no figures | Int.J.Mod.Phys.A23:975-1000,2008 | 10.1142/S0217751X08039554 | null | hep-th astro-ph gr-qc hep-ph | null | We study the system formed by a gaz of black holes and strings within a
microcanonical formulation. We derive the microcanonical content of the system:
entropy, equation of state, number of components N, temperature T and specific
heat. The pressure and the specific heat are negative reflecting the
gravitational unstability and a non-homogeneous configuration. The asymptotic
behaviour of the temperature for large masses emerges as the Hawking
temperature of the system (classical or semiclassical phase) in which the
classical black hole behaviour dominates, while for small masses (quantum black
hole or string behavior) the temperature becomes the string temperature which
emerges as the critical temperature of the system. At low masses, a phase
transition takes place showing the passage from the classical (black hole) to
quantum (string) behaviour. Within a microcanonical field theory formulation,
the propagator describing the string-particle-black hole system is derived and
from it the interacting four point scattering amplitude of the system is
obtained. For high masses it behaves asymptotically as the degeneracy of states
of the system (ie duality or crossing symmetry). The microcanonical propagator
and partition function are derived from a (Nambu-Goto) formulation of the
N-extended objects and the mass spectrum of the black-hole-string system is
obtained: for small masses (quantum behaviour) these yield the usual pure
string scattering amplitude and string-particle spectrum M_n\approx \sqrt{n};
for growing mass it pass for all the intermediate states up to the pure black
hole behaviour. The different black hole behaviours according to the different
mass ranges: classical, semiclassical and quantum or string behaviours are
present in the model.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 18:11:48 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Cirilo-Lombardo",
"D. J.",
"",
"Bogoliubov Laboratory JINR, Dubna"
],
[
"Sanchez",
"N. G.",
"",
"Observatoire de Paris LERMA"
]
] |
0708.0394 | Igor Aleiner | I.L. Aleiner, D.E. Kharzeev, A.M. Tsvelik | Spontaneous symmetry breakings in graphene subjected to in-plane
magnetic field | 28 pages, 20 figures; Supersedes arXiv:cond-mat/0611251 | Phys. Rev. B 76, 195415 (2007) | 10.1103/PhysRevB.76.195415 | null | cond-mat.mes-hall cond-mat.str-el hep-ph | null | Application of the magnetic field parallel to the plane of the graphene sheet
leads to the formation of electron- and hole-like Fermi surfaces. Such
situation is shown to be unstable with respect to the formation of an excitonic
condensate even for an arbitrary weak magnetic field and interaction strength.
At temperatures lower than the mean-field temperature the order parameter
amplitude is formed. The order parameter itself is a U(2) matrix allowing for
the combined rotations in the spin and valley spaces. These rotations smoothly
interpolate between site and bond centered spin density waves and spin flux
states. The trigonal warping, short range interactions, and the three particle
Umklapp processes freeze some degrees of freedom at temperatures much smaller
than the mean-field transition temperature and make either
Berezinskii-Kosterlitz-Thouless (driven either by vortices or half-vortices) or
Ising type transitions possible. Strong logarithmic renormalization for the
coupling constants of these terms by the Coulomb interaction are calculated
within one-loop renormalization group. It is found that in the presence of the
Coulomb interaction some short range interaction terms become much greater than
one might expect from the naive dimensionality counting.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 18:34:40 GMT"
}
] | 2012-04-10T00:00:00 | [
[
"Aleiner",
"I. L.",
""
],
[
"Kharzeev",
"D. E.",
""
],
[
"Tsvelik",
"A. M.",
""
]
] |
0708.0395 | Antonio Jos\'e Ramirez-Pastor Dr. | D. A. Matoz-Fernandez, D. H. Linares, A. J. Ramirez-Pastor | Determination of the Critical Exponents for the Isotropic-Nematic Phase
Transition in a System of Long Rods on Two-dimensional Lattices: Universality
of the Transition | 7 pages, 8 figures, uses epl2.cls, to appear in Europhysics Letters | null | 10.1209/0295-5075/82/50007 | null | cond-mat.stat-mech | null | Monte Carlo simulations and finite-size scaling analysis have been carried
out to study the critical behavior and universality for the isotropic-nematic
phase transition in a system of long straight rigid rods of length $k$
($k$-mers) on two-dimensional lattices. The nematic phase, characterized by a
big domain of parallel $k$-mers, is separated from the isotropic state by a
continuous transition occurring at a finite density. The determination of the
critical exponents, along with the behavior of Binder cumulants, indicate that
the transition belongs to the 2D Ising universality class for square lattices
and the three-state Potts universality class for triangular lattices.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 18:36:32 GMT"
},
{
"version": "v2",
"created": "Mon, 21 Apr 2008 19:25:54 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Matoz-Fernandez",
"D. A.",
""
],
[
"Linares",
"D. H.",
""
],
[
"Ramirez-Pastor",
"A. J.",
""
]
] |
0708.0396 | Nick Devereux | Nick Devereux, Andrew Shearer | Kinematics of the Broad Line Region in M81 | Accepted for Publication in ApJ 7/21/07 | null | 10.1086/522292 | null | astro-ph | null | A new model is presented which explains the origin of the broad emission
lines observed in the LINER/Seyfert nucleus of M81 in terms of a steady state
spherically symmetric inflow, amounting to 1 x 10^-5 Msun/yr, which is
sufficient to explain the luminosity of the AGN. The emitting volume has an
outer radius of ~1 pc, making it the largest broad line region yet to be
measured, and it contains a total mass of ~ 5 x 10^-2 Msun of dense, ~ 10^8
cm^-3, ionized gas, leading to a very low filling factor of ~ 5 x 10^-9. The
fact that the BLR in M81 is so large may explain why the AGN is unable to
sustain the ionization seen there. Thus, the AGN in M81 is not simply a scaled
down quasar.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 18:42:53 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Devereux",
"Nick",
""
],
[
"Shearer",
"Andrew",
""
]
] |
0708.0397 | B{\l}a\.zej Szepietowski | B{\l}a\.zej Szepietowski | A presentation for the mapping class group of the closed non-orientable
surface of genus 4 | 28 pages, 7 figures | J. Pure Appl. Algebra 213 (2009), 2001-2016 | 10.1016/j.jpaa.2009.02.009 | null | math.GT math.GR | null | Finite presentations for the mapping class group M(F) are known for arbitrary
orientable compact surface F. If F is non-orientable, then such presentations
are known only when F has genus at most 3 and few boundary components. In this
paper we obtain finite presentation for the mapping class group of the closed
non-orientable surface of genus 4 from its action on the so called ordered
complex of curves.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 18:54:03 GMT"
}
] | 2010-10-25T00:00:00 | [
[
"Szepietowski",
"Błażej",
""
]
] |
0708.0398 | Prakash Belkale | Prakash Belkale, Shrawan Kumar | Eigencone, saturation and Horn problems for symplectic and odd
orthogonal groups | 46 pages | null | null | null | math.RT math.AG | null | We consider the eigenvalue problem and the associated intersection theory of
homogenous spaces for the symplectic and odd orthogonal groups. We solve the
Horn and saturation problems for these classical groups.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 19:20:56 GMT"
}
] | 2007-08-03T00:00:00 | [
[
"Belkale",
"Prakash",
""
],
[
"Kumar",
"Shrawan",
""
]
] |
0708.0399 | Tun Wang | T. Wang, L. Zhao, L. Jiang, S. F. Yelin | Diffusion induced decoherence of stored optical vortices | 5 pages, 2 figures | null | 10.1103/PhysRevA.77.043815 | null | quant-ph | null | We study the coherence properties of optical vortices stored in atomic
ensembles. In the presence of thermal diffusion, the topological nature of
stored optical vortices is found not to guarantee slow decoherence. Instead the
stored vortex state has decoherence surprisingly larger than the stored
Gaussian mode. Generally, the less phase gradient, the more robust for stored
coherence against diffusion. Furthermore, calculation of coherence factor shows
that the center of stored vortex becomes completely incoherent once diffusion
begins and, when reading laser is applied, the optical intensity at the center
of the vortex becomes nonzero. Its implication for quantum information is
discussed. Comparison of classical diffusion and quantum diffusion is also
presented.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 19:43:44 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Wang",
"T.",
""
],
[
"Zhao",
"L.",
""
],
[
"Jiang",
"L.",
""
],
[
"Yelin",
"S. F.",
""
]
] |
0708.0400 | Klaus Bering | Igor A. Batalin (NBI) and Klaus Bering (NBI) | Odd Scalar Curvature in Field-Antifield Formalism | 23 pages, LaTeX. v2: More material added. v3: Reference added. v4:
Grant number added. v5: Minor changes. v6: Stylistic changes | J.Math.Phys.49:033515,2008 | 10.1063/1.2835485 | null | hep-th math-ph math.MP math.SG | null | We consider the possibility of adding a Grassmann-odd function \nu to the odd
Laplacian. Requiring the total \Delta operator to be nilpotent leads to a
differential condition for \nu, which is integrable. It turns out that the odd
function \nu is not an independent geometric object, but is instead completely
specified by the antisymplectic structure E and the density \rho. The main
impact of introducing the \nu term is that it makes compatibility relations
between E and \rho obsolete. We give a geometric interpretation of \nu as
(minus 1/8 times) the odd scalar curvature of an arbitrary antisymplectic,
torsion-free and \rho-compatible connection. We show that the total \Delta
operator is a \rho-dressed version of Khudaverdian's \Delta_E operator, which
takes semidensities to semidensities. We also show that the construction
generalizes to the situation where \rho is replaced by a non-flat line bundle
connection F. This generalization is implemented by breaking the nilpotency of
\Delta with an arbitrary Grassmann-even second-order operator source.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 19:47:44 GMT"
},
{
"version": "v2",
"created": "Mon, 27 Aug 2007 17:41:10 GMT"
},
{
"version": "v3",
"created": "Tue, 28 Aug 2007 18:22:11 GMT"
},
{
"version": "v4",
"created": "Wed, 7 Nov 2007 14:35:08 GMT"
},
{
"version": "v5",
"created": "Sun, 2 Dec 2007 10:02:38 GMT"
},
{
"version": "v6",
"created": "Thu, 24 Jan 2008 19:28:50 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Batalin",
"Igor A.",
"",
"NBI"
],
[
"Bering",
"Klaus",
"",
"NBI"
]
] |
0708.0401 | William Cherry | Ta Thi Hoai An, William Cherry, and Julie Tzu-Yueh Wang | Algebraic Degeneracy of Non-Archimedean Analytic Maps | 10 pages | Indag. Math. 19 (2008), 481-492 and Indag. Math. 26 (2015),
329-336 | 10.1016/j.indag.2014.11.001 | null | math.AG math.CV math.NT | null | We prove non-Archimedean analogs of results of Noguchi and Winkelmann showing
algebraic degeneracy of rigid analytic maps to projective varieties omitting an
effective divisor with sufficiently many irreducible components relative to the
rank of the group they generate in the Neron-Severi group of the variety.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 19:50:12 GMT"
}
] | 2015-03-23T00:00:00 | [
[
"An",
"Ta Thi Hoai",
""
],
[
"Cherry",
"William",
""
],
[
"Wang",
"Julie Tzu-Yueh",
""
]
] |
0708.0402 | Eric B. Burgh | Eric B. Burgh, Matthew A. Bershady, Kyle B. Westfall, Kenneth H.
Nordsieck | Recombination Ghosts in Littrow Configuration: Implications for
Spectrographs Using Volume Phase Holographic Gratings | 13 pages, 8 figures, emulateapj style, accepted for publication in
PASP | null | 10.1086/522058 | null | astro-ph | null | We report the discovery of optical ghosts generated when using Volume Phase
Holographic (VPH) gratings in spectrographs employing the Littrow
configuration. The ghost is caused by light reflected off the detector surface,
recollimated by the camera, recombined by, and reflected from, the grating and
reimaged by the camera onto the detector. This recombination can occur in two
different ways. We observe this ghost in two spectrographs being developed by
the University of Wisconsin - Madison: the Robert Stobie Spectrograph for the
Southern African Large Telescope and the Bench Spectrograph for the WIYN 3.5m
telescope. The typical ratio of the brightness of the ghost relative to the
integrated flux of the spectrum is of order 10^-4, implying a recombination
efficiency of the VPH gratings of order 10^-3 or higher, consistent with the
output of rigorous coupled wave analysis. Any spectrograph employing VPH
gratings, including grisms, in Littrow configuration will suffer from this
ghost, though the general effect is not intrinsic to VPH gratings themselves
and has been observed in systems with conventional gratings in non-Littrow
configurations. We explain the geometric configurations that can result in the
ghost as well as a more general prescription for predicting its position and
brightness on the detector. We make recommendations for mitigating the ghost
effects for spectrographs and gratings currently built. We further suggest
design modifications for future VPH gratings to eliminate the problem entirely,
including tilted fringes and/or prismatic substrates. We discuss the resultant
implications on the spectrograph performance metrics.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 19:52:21 GMT"
},
{
"version": "v2",
"created": "Thu, 2 Aug 2007 20:12:38 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Burgh",
"Eric B.",
""
],
[
"Bershady",
"Matthew A.",
""
],
[
"Westfall",
"Kyle B.",
""
],
[
"Nordsieck",
"Kenneth H.",
""
]
] |
0708.0403 | Timo Weigand | Ralph Blumenhagen, Mirjam Cvetic, Robert Richter, Timo Weigand | Lifting D-Instanton Zero Modes by Recombination and Background Fluxes | 38 pages, 3 figures, 5 tables; v2: Appendix B slightly expanded,
minor rewording | JHEP 0710:098,2007 | 10.1088/1126-6708/2007/10/098 | null | hep-th | null | We study the conditions under which D-brane instantons in Type II orientifold
compactifications generate a non-perturbative superpotential. If the instanton
is non-invariant under the orientifold action, it carries four instead of the
two Goldstone fermions required for superpotential contributions. Unless these
are lifted, the instanton can at best generate higher fermionic F-terms of
Beasley-Witten type. We analyse two strategies to lift the additional zero
modes. First we discuss the process of instantonic brane recombination in Type
IIA orientifolds. We show that in some cases charge invariance of the measure
enforces the presence of further zero modes which, unlike the Goldstinos,
cannot be absorbed. In other cases, the instanton exhibits reparameterisation
zero modes after recombination and a superpotential is generated if these are
lifted by suitable closed or open string couplings. In the second part of the
paper we address lifting the extra Goldstinos of D3-brane instantons by
supersymmetric three-form background fluxes in Type IIB orientifolds. This
requires non-trivial gauge flux on the instanton. Only if the part of the
fermionic action linear in the gauge flux survives the orientifold projection
can the extra Goldstinos be lifted.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:00:21 GMT"
},
{
"version": "v2",
"created": "Mon, 15 Oct 2007 20:44:33 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Blumenhagen",
"Ralph",
""
],
[
"Cvetic",
"Mirjam",
""
],
[
"Richter",
"Robert",
""
],
[
"Weigand",
"Timo",
""
]
] |
0708.0404 | Shaffique Adam | Shaffique Adam, E. H. Hwang and S. Das Sarma | Scattering mechanisms and Boltzmann transport in graphene | To be published in Physica E as EP2DS-17 conference proceedings | Physica E 40, 1022 (2008) | 10.1016/j.physe.2007.09.064 | null | cond-mat.mes-hall | null | Different scattering mechanisms in graphene are explored and conductivity is
calculated within the Boltzmann transport theory. We provide results for
short-range scattering using the Random Phase Approximation for electron
screening, as well as analytical expressions for the dependence of conductivity
on the dielectric constant of the substrate. We further examine the effect of
ripples on the transport using a surface roughness model developed for
semiconductor heterostructures. We find that close to the Dirac point, \sigma
\sim n^\beta, where \beta=1,0,-2 for Coulomb, short-range and surface roughness
respectively; implying that Coulomb scattering dominates over both short-range
and surface roughness scattering at low density.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:01:19 GMT"
},
{
"version": "v2",
"created": "Tue, 9 Oct 2007 19:07:48 GMT"
}
] | 2008-03-15T00:00:00 | [
[
"Adam",
"Shaffique",
""
],
[
"Hwang",
"E. H.",
""
],
[
"Sarma",
"S. Das",
""
]
] |
0708.0405 | Claudia Greco | C. Greco (1,2,3), G. Clementini (1), M. Catelan (4), E. V. Held (5),
E. Poretti (6), M. Gullieuszik (7), M. Maio (1), A. Rest (8), N. De Lee (9),
H. A. Smith (9), B. J. Pritzl (10) ((1) INAF - Osservatorio Astronomico di
Bologna, (2) Dipartimento di Astronomia, Universita' di Bologna, (3) Marco
Polo Fellow at the Pontificia Universidad de Chile, (4) Pontificia
Universidad de Chile, (5) INAF - Osservatorio Astronomico di Padova, (6) INAF
- Osservatorio Astronomico di Brera, (7) Dipartimento di Astronomia,
Universita' di Padova, (8) Cerro Tololo Inter American Observatory, (9)
Department of Physics and Astronomy, Michigan State University, (10)
Macalester College) | Variable stars in the Fornax dSph Galaxy. I. The Globular Cluster Fornax
4 | Apj, in press | null | 10.1086/522102 | null | astro-ph | null | Variable stars have been identified for the first time in Fornax 4, the
globular cluster located near the center of the Fornax dwarf spheroidal galaxy.
By applying the image subtraction technique to B,V time series photometry
obtained with the MagIC camera of the 6.5-m Magellan/Clay telescope and with
the wide field imager of the 4-m Blanco/CTIO telescope, we detected 27 RR Lyrae
stars (22 fundamental mode, 3 first overtone, and 2 double-mode pulsators) in a
2.4'x2.4' area centered on Fornax 4. The average and minimum periods of the
ab-type RR Lyrae stars, <Pab>= 0.594 d and P(ab,min)=0.5191 d, respectively, as
well as the revised position of the cluster in the horizontal branch
type--metallicity plane, all consistently point to an Oosterhoff-intermediate
status for the cluster, unlike what is seen for the vast majority of Galactic
globular clusters, but in agreement with previous indications for the other
globular clusters in Fornax.
The average apparent magnitude of the RR Lyrae stars located within 30 arcsec
from the cluster center is <V(RR)>=21.43 +/- 0.03 mag (sigma=0.10 mag, average
on 12 stars), leading to a true distance modulus of (m-M)o=20.64 +/- 0.09 mag
or (m-M)o=20.53 +/- 0.09 mag, depending on whether a low ([Fe/H]=-2.0) or a
moderately high ([Fe/H]=-1.5) metallicity is adopted.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:01:45 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Greco",
"C.",
""
],
[
"Clementini",
"G.",
""
],
[
"Catelan",
"M.",
""
],
[
"Held",
"E. V.",
""
],
[
"Poretti",
"E.",
""
],
[
"Gullieuszik",
"M.",
""
],
[
"Maio",
"M.",
""
],
[
"Rest",
"A.",
""
],
[
"De Lee",
"N.",
""
],
[
"Smith",
"H. A.",
""
],
[
"Pritzl",
"B. J.",
""
]
] |
0708.0406 | Andrew Cantrell | Andrew G. Cantrell, Charles D. Bailyn | Robust Models for Phase Shifts in Accreting Binary Stars | 38 pages, 3 figures, to be published in ApJ | null | 10.1086/522084 | null | astro-ph | null | Radial velocity studies of accreting binary stars commonly use accretion disk
emission lines to determine the radial velocity of the primary star and
therefore the mass ratio. These emission line radial velocity curves are often
shifted in phase from the expected motion of the primary. These phase shifts
cast doubt on the use of disk emission lines in the determination of mass
ratios. We present a systematic study of phase shifts, using data from the
literature to distinguish between possible explanations of the phase shift. We
find that one widely adopted class of models is contradicted by observations
(section 2). We present a generalized form of another class of models, which we
call "measurement offset models." We show that these models are quantitatively
consistent with existing data (figures 2 and 3, and the discussion in section
4.4). We consider the implications of adopting measurement offset models, for
both disk structure and determination of binary parameters. Specifically, we
describe in section 6 how measurement offset models may be used improve
determinations of the mass ratio based on disk emission lines. This could be a
valuable new tool in determining masses of important astrophysical objects such
as accreting neutron stars and black holes.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:04:58 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Cantrell",
"Andrew G.",
""
],
[
"Bailyn",
"Charles D.",
""
]
] |
0708.0407 | Anna Sajina | Anna Sajina, Lin Yan, Mark Lacy, Minh Huynh (Spitzer Science Center) | Discovery of Radio Jets in z~2 ULIRGs with Deep 9.7um Silicate
Absorption | 13 pages, 3 figures, accepted for publication in ApJL | null | 10.1086/522050 | null | astro-ph | null | Recent Spitzer observations have revealed a substantial population of z~2
ULIRGs with deep silicate absorption (\tau_{9.7}>1). This paper reports a 20cm
radio study of such a sample to elucidate their physical nature. We discover
that a substantial fraction (40%) of deep silicate absorption ULIRGs at z~2 are
moderately radio-loud with L_{1.4GHz}=10^{25}--10^{26}WHz^{-1}. This is in
strong contrast with z<1 radio galaxies and radio-loud quasars where none of
the sources with available IRS spectra have \tau_{9.7}>1. In addition, we
observe radio jets in two of our sources where one has a double lobe structure
~200kpc in extent, and another shows a one-sided jet extending ~90kpc from the
nucleus. The likely high inclination of the latter, coupled with its deep
silicate absorption, implies the mid-IR obscuration does not share an axis with
the radio jets. These sources are highly obscured quasars, observed in the
transition stage after the birth of the radio source, but before feedback
effects dispel the ISM and halt the black hole accretion and starburst
activity.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:05:07 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sajina",
"Anna",
"",
"Spitzer Science Center"
],
[
"Yan",
"Lin",
"",
"Spitzer Science Center"
],
[
"Lacy",
"Mark",
"",
"Spitzer Science Center"
],
[
"Huynh",
"Minh",
"",
"Spitzer Science Center"
]
] |
0708.0408 | Shiue Yuan Shiau | Shiueyuan Shiau, Robert Joynt | Spin-Valley Kondo Effect in Multi-electron Silicon Quantum Dots | 8 pages, 4 figures, in PRB format. This paper is a sequel to the
paper published in Phys. Rev. B 75, 195345 (2007) | Phys. Rev. B 76, 205314 (2007) | 10.1103/PhysRevB.76.205314 | null | cond-mat.mtrl-sci cond-mat.str-el | null | We study the spin-valley Kondo effect of a silicon quantum dot occupied by $%
\mathcal{N}$ electrons, with $\mathcal{N}$ up to four. We show that the Kondo
resonance appears in the $\mathcal{N}=1,2,3$ Coulomb blockade regimes, but not
in the $\mathcal{N}=4$ one, in contrast to the spin-1/2 Kondo effect, which
only occurs at $\mathcal{N}=$ odd. Assuming large orbital level spacings, the
energy states of the dot can be simply characterized by fourfold spin-valley
degrees of freedom. The density of states (DOS) is obtained as a function of
temperature and applied magnetic field using a finite-U equation-of-motion
approach. The structure in the DOS can be detected in transport experiments.
The Kondo resonance is split by the Zeeman splitting and valley splitting for
double- and triple-electron Si dots, in a similar fashion to single-electron
ones. The peak structure and splitting patterns are much richer for the
spin-valley Kondo effect than for the pure spin Kondo effect.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 19:13:47 GMT"
}
] | 2019-09-04T00:00:00 | [
[
"Shiau",
"Shiueyuan",
""
],
[
"Joynt",
"Robert",
""
]
] |
0708.0409 | Dimitar Stoyanov | Dimitar G. Stoyanov | Analytical form of current-voltage characteristic of parallel-plane,
cylindrical and spherical ionization chambers with homogeneous ionization | 20 pages, 6 figures, 2 tables; changed content | Journal of Instrumentation, 2007 JINST 2 P11006 | 10.1088/1748-0221/2/11/P11006 | null | physics.gen-ph physics.plasm-ph | null | The elementary processes taking place in the formation of charged particles
and their flow in parallel-plane, cylindrical and spherical ionization chambers
are considered. On the basis of particles and charges balance a differential
equation describing the distribution of current densities in the ionization
chamber volume is obtained. As a result of the differential equation solution
an analytical form of the current-voltage characteristic of an ionization
chamber with homogeneous ionization is obtained. For the parallel-plane case
the comparison with experimental data is performed.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:06:20 GMT"
},
{
"version": "v2",
"created": "Mon, 8 Oct 2007 18:24:49 GMT"
},
{
"version": "v3",
"created": "Fri, 2 Nov 2007 13:02:43 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Stoyanov",
"Dimitar G.",
""
]
] |
0708.0410 | Jan Fischer | Jan Fischer and Heinz-Peter Breuer | Correlated projection operator approach to non-Markovian dynamics in
spin baths | null | Phys. Rev. A 76, 052119 (2007) | 10.1103/PhysRevA.76.052119 | null | quant-ph cond-mat.mes-hall | null | The dynamics of an open quantum system is usually studied by performing a
weak-coupling and weak-correlation expansion in the system-bath interaction.
For systems exhibiting strong couplings and highly non-Markovian behavior this
approach is not justified. We apply a recently proposed correlated projection
superoperator technique to the model of a central spin coupled to a spin bath
via full Heisenberg interaction. Analytical solutions to both the
Nakajima-Zwanzig and the time-convolutionless master equation are determined
and compared with the results of the exact solution. The correlated projection
operator technique significantly improves the standard methods and can be
applied to many physical problems such as the hyperfine interaction in a
quantum dot.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:08:07 GMT"
},
{
"version": "v2",
"created": "Mon, 3 Dec 2007 14:16:45 GMT"
}
] | 2010-12-27T00:00:00 | [
[
"Fischer",
"Jan",
""
],
[
"Breuer",
"Heinz-Peter",
""
]
] |
0708.0411 | Marcelo J. Reboucas | J. Santos, J.S. Alcaniz, M.J. Reboucas, F.C. Carvalho | Energy conditions in f(R)-gravity | 5 pages. V2: Version to appear in Phys.Rev.D, references added, minor
changes | Phys.Rev.D76:083513,2007 | 10.1103/PhysRevD.76.083513 | null | astro-ph | null | In order to shed some light on the current discussion about f(R)-gravity
theories we derive and discuss the bounds imposed by the energy conditions on a
general f(R) functional form. The null and strong energy conditions in this
framework are derived from the Raychaudhuri's equation along with the
requirement that gravity is attractive, whereas the weak and dominant energy
conditions are stated from a comparison with the energy conditions that can be
obtained in a direct approach via an effective energy-momentum tensor for
f(R)-gravity. As a concrete application of the energy conditions to locally
homogeneous and isotropic f(R)-cosmology, the recent estimated values of the
deceleration and jerk parameters are used to examine the bounds from the weak
energy condition on the parameters of two families of f(R)-gravity theories.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:09:39 GMT"
},
{
"version": "v2",
"created": "Thu, 6 Sep 2007 02:08:41 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Santos",
"J.",
""
],
[
"Alcaniz",
"J. S.",
""
],
[
"Reboucas",
"M. J.",
""
],
[
"Carvalho",
"F. C.",
""
]
] |
0708.0412 | Ryan Baumbach | R. E. Baumbach, P. C. Ho, T. A. Sayles, M. B. Maple, R. Wawryk, T.
Cichorek, A. Pietraszko, Z. Henkie | Non-Fermi liquid behavior in a fluctuating valence system, the filled
skutterudite compound CeRu_{4}As_{12} | 18 pages, 5 figures | null | 10.1088/0953-8984/20/7/075110 | null | cond-mat.str-el | null | Electrical resistivity $\rho$, specific heat C, and magnetic susceptibility
$\chi$ measurements made on the filled skutterudite CeRu_4As_{12} reveal
non-Fermi liquid (NFL) T - dependences at low T, i.e., $\rho$(T) $\sim$ T^{1.4}
and weak power law or logarithmic divergences in C(T)/T and $\chi$(T).
Measurements also show that the T - dependence of the thermoelectric power S(T)
deviates from that seen in other Ce systems. The NFL behavior appears to be
associated with fluctuations of the Ce valence between 3^+ and 4^+ rather than
a typical Kondo lattice scenario that would be appropriate for an integral Ce
valence of 3^+.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:09:49 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Baumbach",
"R. E.",
""
],
[
"Ho",
"P. C.",
""
],
[
"Sayles",
"T. A.",
""
],
[
"Maple",
"M. B.",
""
],
[
"Wawryk",
"R.",
""
],
[
"Cichorek",
"T.",
""
],
[
"Pietraszko",
"A.",
""
],
[
"Henkie",
"Z.",
""
]
] |
0708.0413 | Albert Kong | Albert K.H. Kong, Jon M. Miller, Mariano Mendez, Jean Cottam, Walter
H.G. Lewin, Frederik Paerels, Erik Kuulkers, Rudy Wijnands, Michiel van der
Klis | Non-Detection of Gravitationally Redshifted Absorption Lines in the
X-ray Burst Spectra of GS 1826-24 | 4 pages, 4 figures; accepted for publication in ApJL | null | 10.1086/524137 | null | astro-ph | null | During a 200 ks observation with the XMM-Newton Reflection Grating
Spectrometer, we detected 16 type-I X-ray bursts from GS 1826-24. We combined
the burst spectra in an attempt to measure the gravitational redshifts from the
surface of the neutron star. We divided the composite GS 1826-24 burst spectrum
into three groups based on the blackbody temperature during the bursts. The
spectra do not show any obvious discrete absorption lines. We compare our
observations with those of EXO 0748-676.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:10:07 GMT"
},
{
"version": "v2",
"created": "Thu, 11 Oct 2007 16:13:46 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kong",
"Albert K. H.",
""
],
[
"Miller",
"Jon M.",
""
],
[
"Mendez",
"Mariano",
""
],
[
"Cottam",
"Jean",
""
],
[
"Lewin",
"Walter H. G.",
""
],
[
"Paerels",
"Frederik",
""
],
[
"Kuulkers",
"Erik",
""
],
[
"Wijnands",
"Rudy",
""
],
[
"van der Klis",
"Michiel",
""
]
] |
0708.0414 | Tamara Bogdanovic | Tamara Bogdanovic (1,2), Britton D. Smith (1), Steinn Sigurdsson (1),
and Michael Eracleous (1) ((1) Pennsylvania State University,(2) University
of Maryland) | Modeling of Emission Signatures of Massive Black Hole Binaries: I
Methods | 28 pages, 29 figures, to appear in ApJS | null | 10.1086/521828 | null | astro-ph | null | We model the electromagnetic signatures of massive black hole binaries
(MBHBs) with an associated gas component. The method comprises numerical
simulations of relativistic binaries and gas coupled with calculations of the
physical properties of the emitting gas. We calculate the UV/X-ray and the
Halpha light curves and the Halpha emission profiles. The simulations are
carried out with a modified version of the parallel tree SPH code Gadget. The
heating, cooling, and radiative processes are calculated for two different
physical scenarios, where the gas is approximated as a black-body or a solar
metallicity gas. The calculation for the solar metallicity scenario is carried
out with the photoionization code Cloudy. We focus on sub-parsec binaries which
have not yet entered the gravitational radiation phase. The results from the
first set of calculations, carried out for a coplanar binary and gas disk,
suggest that there are pronounced outbursts in the X-ray light curve during
pericentric passages. If such outbursts persist for a large fraction of the
lifetime of the system, they can serve as an indicator of this type of binary.
The predicted Halpha emission line profiles may be used as a criterion for
selection of MBHB candidates from existing archival data. The orbital period
and mass ratio of a binary may be inferred after carefully monitoring the
evolution of the Halpha profiles of the candidates. The discovery of sub-parsec
binaries is an important step in understanding of the merger rates of MBHBs and
their evolution towards the detectable gravitational wave window.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:14:33 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Bogdanovic",
"Tamara",
""
],
[
"Smith",
"Britton D.",
""
],
[
"Sigurdsson",
"Steinn",
""
],
[
"Eracleous",
"Michael",
""
]
] |
0708.0415 | Jan Timmermans | The DELPHI Collaboration: J. Abdallah, et al | Search for Pentaquarks in the Hadronic Decays of the Z Boson with the
DELPHI Detector at LEP | 15 pages, 5 figures, Accepted by Phys. Lett. B | Phys.Lett.B653:151-160,2007 | 10.1016/j.physletb.2007.08.005 | CERN-PH-EP-2007-017 | hep-ex | null | The quark model does not exclude states composed of more than three quarks,
like pentaquark systems. Controversial evidence for such states has been
published in the last years, in particular: for a strange pentaquark
Theta(1540)+; for a double-strange state, the Xi(1862)--, subsequently called
Phi(1860)--; and for a charmed state, the Theta_c(3100)^0. If confirmed, a full
pentaquark family might exist; such pentaquark states could be produced in e+e-
annihilations near the Z energy. In this paper a search for pentaquarks is
described using the DELPHI detector at LEP, characterized by powerful particle
identification sub-systems crucial in the separation of the signal from the
background for these states. At 95% CL, upper limits are set on the production
rates <N> of such particles and their charge-conjugate state per Z decay:
<N_Theta+> x Br(Theta+ -> pK0_S) < 5.1 x 10^{-4}
<N_Theta++> < 1.6 x 10^{-3}
<N_Phi(1860)-- > x Br(Phi(1860)-- -> Xi- pi-) < 2.9 x 10^{-4}
<Theta_c(3100)^0> x Br(Theta_c(3100)^0 -> D*+ pbar) < 8.8 x 10^{-4} .
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:18:57 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"The DELPHI Collaboration",
"",
""
],
[
"Abdallah",
"J.",
""
]
] |
0708.0416 | Johann Kroha | Michael Arnold and Johann Kroha (Universit"at Bonn) | Simultaneous ferromagnetic metal-semiconductor transition in
electron-doped EuO | 4 pages, 4 figures, Phys. Rev. Lett., published version; different
behavior of Gd impurities and O defects clarified | Phys. Rev. Lett. 100, 046404 (2008) | 10.1103/PhysRevLett.100.046404 | null | cond-mat.str-el cond-mat.mtrl-sci | null | We present a general framework to describe the simultaneous
para-to-ferromagnetic and semiconductor-to-metal transition in electron-doped
EuO. The theory correctly describes detailed experimental features of the
conductivity and of the magnetization, in particular the doping dependence of
the Curie temperature. The existence of correlation-induced local moments on
the impurity sites is essential for this description.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:19:14 GMT"
},
{
"version": "v2",
"created": "Wed, 12 Dec 2007 12:55:57 GMT"
}
] | 2008-02-02T00:00:00 | [
[
"Arnold",
"Michael",
"",
"Universit\"at Bonn"
],
[
"Kroha",
"Johann",
"",
"Universit\"at Bonn"
]
] |
0708.0417 | Xiaolei Zhang | Xiaolei Zhang | Disentangling the Dynamical Mechanisms for Cluster Galaxy Evolution | Accepted for publication in the PASP | null | 10.1086/527571 | null | astro-ph | null | The determination of the dynamical causes of the morphological Butcher-Oemler
(BO) effect, or the rapid transformation of a large population of late-type
galaxies to earlier Hubble types in the rich cluster environment between
intermediate redshifts and the local universe, has been an important unsolved
problem which is central to our understanding of the general problems of galaxy
formation and evolution. In this article, we survey the existing proposed
mechanisms for cluster galaxy transformation, and discuss their relevance and
limitations to the explanation of the morphological BO effect. A new infrared
diagnostic approach is devised to disentangle the relative importance of
several major physical mechanisms to account for the BO effect, and an example
of the first application of this procedure to a single rich, intermediate
redshift galaxy cluster is given to demonstrate the viability of this approach.
The preliminary result of this analysis favors the interaction-enhanced secular
evolution process as the major cause of the cluster-galaxy morphological
transformation. This conclusion is also supported by a wide range of other
published results which are assembled here to highlight their implications on a
coherent physical origin for the morphological BO effect.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:22:50 GMT"
},
{
"version": "v2",
"created": "Thu, 27 Dec 2007 18:22:05 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Zhang",
"Xiaolei",
""
]
] |
0708.0418 | Erik Bogaart | E.W. Bogaart and J.E.M. Haverkort | Anomalous exciton lifetime by an electromagnetic coupling of
self-assembled quantum dots | 4 figures | null | null | null | cond-mat.other | null | We report on the experimental observation of a hitherto ignored long-range
electromagnetic coupling between self-assembled quantum dots. A 12 times
enhancement of the quantum dot exciton lifetime is observed by means of
time-resolved differential reflection spectroscopy. The enhancement is
explained by utilizing and extending the local field effects as developed in
\emph{Phys. Rev. B \textbf{64},125326 (2001)}. The electromagnetic coupling of
the quantum dots results in a collective polarizability, and is observed as a
suppression of the emission rate. Our results reveal that the coupling is
established over a distance exceeding 490 nm. Moreover, the mutual coupling
strength is optically tuned by varying the pump excitation density and enables
us to optically tune the exciton lifetime.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 20:32:11 GMT"
}
] | 2007-08-06T00:00:00 | [
[
"Bogaart",
"E. W.",
""
],
[
"Haverkort",
"J. E. M.",
""
]
] |
0708.0419 | Kenneth Chu | Kenneth C. K. Chu | On the Geometry of the Moduli Space of Real Binary Octics | 23 pages | Can. J. Math.-J. Can. Math. 63 (2011) 755-797 | 10.4153/CJM-2011-026-1 | null | math.AG math.DG | null | The moduli space of smooth real binary octics has five connected components.
They parametrize the real binary octics whose defining equations have 0, 1,
..., 4 complex-conjugate pairs of roots respectively. We show that the
GIT-stable completion of each of these five components admits the structure of
an arithmetic real hyperbolic orbifold. The corresponding monodromy groups are,
up to commensurability, discrete hyperbolic reflection groups, and their
Vinberg diagrams are computed. We conclude with a simple proof that the moduli
space of GIT-stable real binary octics itself cannot be a real hyperbolic
orbifold.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 23:01:41 GMT"
}
] | 2019-08-15T00:00:00 | [
[
"Chu",
"Kenneth C. K.",
""
]
] |
0708.0420 | Richard Hill | Richard Hill | On Emerton's $p$-adic Banach spaces | 30 pages | null | null | null | math.NT | null | The purpose of the current paper is to introduce some new methods for
studying the $p$-adic Banach spaces introduced by Emerton \cite{emerton}. We
first relate these spaces to more familiar sheaf cohomology groups. As an
application, we obtain a more general version of Emerton's spectral sequence.
We also calculate the spaces in some easy cases. As a consequence, we obtain a
number of vanishing theorems.
| [
{
"version": "v1",
"created": "Fri, 3 Aug 2007 15:14:42 GMT"
}
] | 2007-08-06T00:00:00 | [
[
"Hill",
"Richard",
""
]
] |
0708.0421 | Edison Luiz Gra\c{c}a | E. L. Graca | Contributions to the Study of Thermal States of the Bosonic String in
the TFD Formalism | 62 pages, dissertation in portuguese | null | null | null | hep-th | null | We determine the local entropy of the free energy of the quantized open
bosonic string in Minkowski spacetime with the most general boundary
conditions. We formulate a finite temperature theory of the thermal closed
string excitations in anti-de Sitter spacetime within the TFD approach. We
write down the thermal states and obtain the entropy and the free energy in the
first order expansion of the semiclassical quantization in the center of mass
reference frame.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 21:12:40 GMT"
}
] | 2007-08-06T00:00:00 | [
[
"Graca",
"E. L.",
""
]
] |
0708.0422 | Stephane Courteau | S. Courteau, A. A. Dutton, F. van den Bosch, L. A. MacArthur, A.
Dekel, D. H. McIntosh, D. A. Dale (Queen's University, UCSC, MPIA, Caltech,
Hebrew University, UMASS, University of Wyoming) | Scaling Relations of Spiral Galaxies | Accepted for publication at ApJ. The full document, with
high-resolution B&W and colour figures, is available at
http://www.astro.queensu.ca/~courteau/papers/VRL2007ApJ.pdf . Our data base
for 1303 spiral galaxies is also available at
http://www.astro.queensu.ca/~courteau/data/VRL2007.dat | null | 10.1086/522193 | null | astro-ph | null | We construct a large data set of global structural parameters for 1300 field
and cluster spiral galaxies and explore the joint distribution of luminosity L,
optical rotation velocity V, and disk size R at I- and 2MASS K-bands. The I-
and K-band velocity-luminosity (VL) relations have log-slopes of 0.29 and 0.27,
respectively with sigma_ln(VL)~0.13, and show a small dependence on color and
morphological type in the sense that redder, early-type disk galaxies rotate
faster than bluer, later-type disk galaxies for most luminosities. The VL
relation at I- and K-bands is independent of surface brightness, size and light
concentration. The log-slope of the I- and K-band RL relations is a strong
function of morphology and varies from 0.25 to 0.5. The average dispersion
sigma_ln(RL) decreases from 0.33 at I-band to 0.29 at K, likely due to the
2MASS selection bias against lower surface brightness galaxies. Measurement
uncertainties are sigma_ln(V)~0.09, sigma_ln(L)~0.14 and somewhat larger and
harder to estimate for ln(R). The color dependence of the VL relation is
consistent with expectations from stellar population synthesis models. The VL
and RL residuals are largely uncorrelated with each other; the RV-RL residuals
show only a weak positive correlation. These correlations suggest that scatter
in luminosity is not a significant source of the scatter in the VL and RL
relations. The observed scaling relations can be understood in the context of a
model of disk galaxies embedded in dark matter halos that invokes low mean spin
parameters and dark halo expansion, as we describe in our companion paper
(Dutton et al. 2007). We discuss in two appendices various pitfalls of standard
analytical derivations of galaxy scaling relations, including the Tully-Fisher
relation with different slopes. (Abridged).
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 21:24:37 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Courteau",
"S.",
"",
"Queen's University, UCSC, MPIA, Caltech,\n Hebrew University, UMASS, University of Wyoming"
],
[
"Dutton",
"A. A.",
"",
"Queen's University, UCSC, MPIA, Caltech,\n Hebrew University, UMASS, University of Wyoming"
],
[
"Bosch",
"F. van den",
"",
"Queen's University, UCSC, MPIA, Caltech,\n Hebrew University, UMASS, University of Wyoming"
],
[
"MacArthur",
"L. A.",
"",
"Queen's University, UCSC, MPIA, Caltech,\n Hebrew University, UMASS, University of Wyoming"
],
[
"Dekel",
"A.",
"",
"Queen's University, UCSC, MPIA, Caltech,\n Hebrew University, UMASS, University of Wyoming"
],
[
"McIntosh",
"D. H.",
"",
"Queen's University, UCSC, MPIA, Caltech,\n Hebrew University, UMASS, University of Wyoming"
],
[
"Dale",
"D. A.",
"",
"Queen's University, UCSC, MPIA, Caltech,\n Hebrew University, UMASS, University of Wyoming"
]
] |
0708.0423 | Lincoln Greenhill | L.J. Greenhill | Masers in AGN environments | 10 pages, 6 figures, to appear in proceedings of IAU Symposium 242
"Astrophysical Masers and their Environments", held in Alice Springs, March
2007 | null | 10.1017/S1743921307013439 | null | astro-ph | null | Galactic nuclei are well known sources of OH and H2O maser emission. It
appears that intense star formation in ultra-luminous infrared galaxies drives
most OH sources. In contrast, nuclear activity appears to drive most H2O
sources. When H2O emission originates in accretion disk structures, constrained
geometry and dynamics enable robust interpretation of spectroscopic and imaging
data. The principal science includes study of AGN geometry at parsec and
sub-parsec radii and measurement of geometric distances in the Hubble Flow. New
high accuracy estimates of the Hubble constant, "Ho," obtained from maser
distances may enable new substantively improved constraints on fundamental
cosmological parameters (e.g., dark energy).
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 22:07:02 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Greenhill",
"L. J.",
""
]
] |
0708.0424 | Brian Rodriguez | B J Rodriguez, C Callahan, S V Kalinin, R Proksch | Dual-Frequency Resonance-Tracking Atomic Force Microscopy | null | Nanotechnology 18 475504 (6pp) 2007 | 10.1088/0957-4484/18/47/475504 | null | cond-mat.mtrl-sci | null | A dual-excitation method for resonant-frequency tracking in scanning probe
microscopy based on amplitude detection is developed. This method allows the
cantilever to be operated at or near resonance for techniques where standard
phase locked loops are not possible. This includes techniques with non-acoustic
driving where the phase of the driving force is frequency and/or position
dependent. An example of the later is Piezoresponse Force Microscopy (PFM),
where the resonant frequency of the cantilever is strongly dependent on the
contact stiffness of the tip-surface junction and the local mechanical
properties, but the spatial variability of the drive phase rules out the use of
a phase locked loop. Combined with high-voltage switching and imaging,
dual-frequency, resonance-tracking PFM allows reliable studies of
electromechanical and elastic properties and polarization dynamics in a broad
range of inorganic and biological systems, and is illustrated using lead
zirconate-titanate, rat tail collagen, and native and switched ferroelectric
domains in lithium niobate.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 21:39:26 GMT"
}
] | 2008-03-13T00:00:00 | [
[
"Rodriguez",
"B J",
""
],
[
"Callahan",
"C",
""
],
[
"Kalinin",
"S V",
""
],
[
"Proksch",
"R",
""
]
] |
0708.0425 | Mike Steel Prof. | Beata Faller, Fabio Pardi, Mike Steel | Distribution of phylogenetic diversity under random extinction | 20 pages, 4 figures | null | null | null | q-bio.SC q-bio.PE | null | Phylogenetic diversity is a measure for describing how much of an
evolutionary tree is spanned by a subset of species. If one applies this to the
(unknown) subset of current species that will still be present at some future
time, then this `future phylogenetic diversity' provides a measure of the
impact of various extinction scenarios in biodiversity conservation. In this
paper we study the distribution of future phylogenetic diversity under a simple
model of extinction (a generalized `field of bullets' model). We show that the
distribution of future phylogenetic diversity converges to a normal
distribution as the number of species grows (under mild conditions, which are
necessary). We also describe an algorithm to compute the distribution
efficiently, provided the edge lengths are integral, and briefly outline the
significance of our findings for biodiversity conservation.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 22:22:03 GMT"
}
] | 2009-09-29T00:00:00 | [
[
"Faller",
"Beata",
""
],
[
"Pardi",
"Fabio",
""
],
[
"Steel",
"Mike",
""
]
] |
0708.0426 | Patricia Faisca | Rui D.M. Travasso, M.M. Telo da Gama and P.F.N. Faisca | Pathways to folding, nucleation events and native geometry | Accepted in J. Chem. Phys | null | 10.1063/1.2777150 | null | q-bio.BM | null | We perform extensive Monte Carlo simulations of a lattice model and the Go
potential to investigate the existence of folding pathways at the level of
contact cluster formation for two native structures with markedly different
geometries. Our analysis of folding pathways revealed a common underlying
folding mechanism, based on nucleation phenomena, for both protein models.
However, folding to the more complex geometry (i.e. that with more non-local
contacts) is driven by a folding nucleus whose geometric traits more closely
resemble those of the native fold. For this geometry folding is clearly a more
cooperative process.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 21:35:18 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Travasso",
"Rui D. M.",
""
],
[
"da Gama",
"M. M. Telo",
""
],
[
"Faisca",
"P. F. N.",
""
]
] |
0708.0427 | Roopa Narayan | R. H. Narayan | Time Cycles in Indian Cosmology | 8 pages | null | null | null | physics.hist-ph | null | In this article we review some key time cycles in ancient Indian astronomy,
especially those that have emerged from researches in the past couple of
decades expressing knowledge of the changing frame of earth's axis. The article
also briefly reviews the philosophy related to the interconnection between the
inner and the outer cosmos that was used in the analytical narrative related to
this astronomy.
| [
{
"version": "v1",
"created": "Fri, 3 Aug 2007 00:51:48 GMT"
}
] | 2007-08-06T00:00:00 | [
[
"Narayan",
"R. H.",
""
]
] |
0708.0428 | R. Craig Walker | R. C. Walker, C. Ly, W. Junor and P. E. Hardee | Progress Toward a VLBA Movie of the Jet Collimation Region in M87 | 7 pages, 3 figures. To be published in the proceedings of
"Extragalactic Jets: Theory and Observation from Radio to Gamma Ray", eds. T.
A. Rector and D. S. De Young (ASP Conf. Ser.) | null | null | null | astro-ph | null | With its high black hole mass, proximity, and bright jet, M87 provides the
best prospect for a direct imaging study of the acceleration and collimation
region of a jet. Previous VLBI observations have shown an edge brightened
structure with a wide opening angle at small scales. An effort to measure
component speeds in this region using existing VLBA data at 43 GHz gave
tentative results of 0.25c to 0.4c but also indicated that faster sampling is
needed. Here we provide a progress report on a project to make a properly
sampled movie of motions in the inner jet using the VLBA at 43 GHz. A pilot
project during 2006 measured speeds of about 0.6c and was used to set a frame
interval of 3 weeks for the movie. The movie observations began in January
2007. Results from the pilot and from the first frame of the movie are
presented. The goal of the project is to provide observations of the structure
and dynamics of the jet on scales from under 100 to a few hundred Schwarzschild
radii that can be compared with expectations from theoretical studies and
numerical modeling.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 22:04:48 GMT"
}
] | 2007-08-06T00:00:00 | [
[
"Walker",
"R. C.",
""
],
[
"Ly",
"C.",
""
],
[
"Junor",
"W.",
""
],
[
"Hardee",
"P. E.",
""
]
] |
0708.0429 | Joao Magueijo | Pedro Ferreira and Joao Magueijo | Observing the temperature of the Big Bang through large scale structure | null | Phys.Rev.D78:061301,2008 | 10.1103/PhysRevD.78.061301 | null | astro-ph gr-qc hep-ph | null | It is widely accepted that the Universe underwent a period of thermal
equilibrium at very early times. One expects a residue of this primordial state
to be imprinted on the large scale structure of space time. In this paper we
study the morphology of this thermal residue in a universe whose early dynamics
is governed by a scalar field. We calculate the amplitude of fluctuations on
large scales and compare it to the imprint of vacuum fluctuations. We then use
the observed power spectrum of fluctuations on the cosmic microwave background
to place a constraint on the temperature of the Universe before and during
inflation. We also present an alternative scenario where the fluctuations are
predominantly thermal and near scale-invariant.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 22:07:23 GMT"
}
] | 2009-02-20T00:00:00 | [
[
"Ferreira",
"Pedro",
""
],
[
"Magueijo",
"Joao",
""
]
] |
0708.0430 | Ana Maria Hidalgo-G\'amez | A.M. Hidalgo-Gamez (ESFM-Ipn) | Diffuse Ionized Gas in the Dwarf Irregular Galaxy DDO 53 | 32 pages, 9 figures, 7 tables. AJ, in press | Astron.J.134:1447-1458,2007 | 10.1086/521392 | null | astro-ph | null | The spectral characteristics throughout the dwarf irregular galaxy DDO 53 are
studied. The results are very similar to those for other irregular galaxies:
high excitation and low values of the [SII]/Halpha ratio. The most likely
ionization source is photon leakage from the classical HII regions, without any
other source, although the interstellar medium of the galaxy is quite
perturbed. Moreover, the physical conditions throughout the galaxy do not
change very much because both the photon leakage percentage and the ionization
temperature are very similar. In addition, the determined metal content for two
HII regions indicates that DDO 53 is a low-metallicity galaxy.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 22:18:07 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hidalgo-Gamez",
"A. M.",
"",
"ESFM-Ipn"
]
] |
0708.0431 | Arsen Elkin | Arsen Elkin | The Rank of the Cartier operator on cyclic covers of the projective line | null | null | null | null | math.AG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give a lower bound on the rank of the Cartier operator of Jacobian
varieties of hyperelliptic and superelliptic curves in terms of their genus.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 22:30:50 GMT"
},
{
"version": "v2",
"created": "Mon, 17 May 2010 17:42:10 GMT"
}
] | 2010-05-18T00:00:00 | [
[
"Elkin",
"Arsen",
""
]
] |
0708.0432 | Emilio Elizalde | F. Briscese and E. Elizalde | Black hole entropy in modified gravity models | 5 pages, 3 figures, revtex file, version to appear in PRD | Phys.Rev.D77:044009,2008 | 10.1103/PhysRevD.77.044009 | null | hep-th | null | An analysis of some modified gravity models, based on the study of pure
Schwarzschild and of Schwarzschild-de Sitter black holes, and involving the use
of the Noether charge method, is carried out. Corrections to the classical
Einsteinian black hole entropy appear. It is shown explicitly how the condition
of positive entropy can be used in order to constrain the viability of modified
gravity theories.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 22:46:00 GMT"
},
{
"version": "v2",
"created": "Sun, 13 Jan 2008 19:30:12 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Briscese",
"F.",
""
],
[
"Elizalde",
"E.",
""
]
] |
0708.0433 | Karol Kozlowski Kajetan | K. K. Kozlowski | On the emptiness formation probability of the open XXZ spin-$\tf{1}{2}$
chain | 18 pages | J.Stat.Mech.0802:P02006,2008 | 10.1088/1742-5468/2008/02/P02006 | null | hep-th | null | This paper is devoted to the study of the emptiness formation probability
$\tau\pa{m}$ of the open XXZ chain. We derive a closed form for $\tau\pa{m}$ at
$\Delta=\tf{1}{2}$ when the boundary field vanishes. Moreover we obtain its
leading asymptotics for an arbitrary boundary field at the free fermion point.
Finally, we compute the first term of the asymptotics of $\ln\pa{\tau\pa{m}}$
in the whole massless regime $-1<\Delta<1$.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 22:51:16 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kozlowski",
"K. K.",
""
]
] |
0708.0434 | Raul Esquivel-Sirvent | R. Esquivel-Sirvent | Reduction of the Casimir force using aerogels | to appear J. Appl. Phys | null | 10.1063/1.2767225 | null | quant-ph | null | By using silicon oxide based aerogels we show numerically that the Casimir
force can be reduced several orders of magnitude, making its effect negligible
in nanodevices. This decrease in the Casimir force is also present even when
the aerogels are deposited on metallic substrates. To calculate the Casimir
force we model the dielectric function of silicon oxide aerogels using an
effective medium dielectric function such as the Clausius-Mossotti
approximation. The results show that both the porosity of the aerogel and its
thickness can be use as control parameters to reduce the magnitude of the
Casimir force.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 22:53:46 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Esquivel-Sirvent",
"R.",
""
]
] |
0708.0435 | Yi-Fang Chang | Yi-Fang Chang | Perfect Structure of the Special Relativity, Superluminal,
Neutrino-Photon Mass and New Entangled Interaction | 14 pages | null | null | null | physics.gen-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | First, some superluminal phenomena and experiments are introduced briefly.
Next, based on the basic principles of the special relativity, the Lorentz
transformation (LT) with smaller velocity and the general Lorentz
transformation (GLT) with larger velocity should be derived simultaneously by
the classification of the timelike and the spacelike intervals. In deriving LT,
an additional independent hypothesis has been used, thus the values of velocity
are restricted absolutely, and the spacelike interval is excluded. LT and GLT
are connected by the de Broglie relation. The fundamental properties of any
four-vector and the strange characteristic which these tachyons should possess
are described. The various superluminal transformations are discussed. Further,
we think that LT is unsuitable for photon and neutrino, the photon
transformation (PT) is unified for space and time. It may reasonably overcome
some existing difficulties, and cannot restrict that the rest mass of photon
and neutrino must be zero. LT, GLT and PT together form a complete structure of
the Lorentz group. Finally, we discuss that new experiments on the quantum
entangled state shown some characters, for example, coherency, nonlocality,
quantum teleportation and superluminal. Further, it should be a new fifth
interaction, and may probably apply GLT.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 23:13:15 GMT"
},
{
"version": "v2",
"created": "Wed, 9 Jun 2010 22:49:48 GMT"
}
] | 2010-06-11T00:00:00 | [
[
"Chang",
"Yi-Fang",
""
]
] |
0708.0436 | Masoud Mohseni | M. Mohseni, A. T. Rezakhani, and A. Aspuru-Guzik | Direct Estimation of Single- and Two-Qubit Hamiltonians and Relaxation
Rates | 5 pages, published version | Phys. Rev. A 77, 042320 (2008) | 10.1103/PhysRevA.77.042320 | null | quant-ph | null | We provide a novel approach for characterization of quantum Hamiltonian
systems via utilizing a single measurement device. Specifically, we demonstrate
how external quantum correlations can be used for Hamiltonian identification
tasks. We explicitly introduce experimental procedures for direct estimation of
single- and two-qubit Hamiltonian parameters, and also for simultaneous
estimation of transverse and longitudinal relaxation rates, using a single
Bell-state analyzer. An advantage of our method over the earlier approaches is
that it has a built-in feature which makes it suitable for partial
characterization of Hamiltonian parameters.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 23:40:52 GMT"
},
{
"version": "v2",
"created": "Sun, 5 Aug 2007 03:39:18 GMT"
},
{
"version": "v3",
"created": "Wed, 23 Apr 2008 18:23:48 GMT"
}
] | 2008-04-23T00:00:00 | [
[
"Mohseni",
"M.",
""
],
[
"Rezakhani",
"A. T.",
""
],
[
"Aspuru-Guzik",
"A.",
""
]
] |
0708.0437 | Zhanhua Ma | Zhanhua Ma, Clarence W. Rowley, and Gilead Tadmor | Snapshot-based Balanced Truncation for Linear Time-periodic Systems | null | null | null | null | math.OC math.DS | null | We introduce an algorithm based on a method of snapshots for computing
approximate balanced truncations for discrete-time, stable, linear
time-periodic systems. By construction, this algorithm is applicable to very
high-dimensional systems, even with very high-dimensional outputs (or,
alternatively, very high-dimensional inputs). An example is shown to validate
the method.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 23:19:54 GMT"
}
] | 2007-08-06T00:00:00 | [
[
"Ma",
"Zhanhua",
""
],
[
"Rowley",
"Clarence W.",
""
],
[
"Tadmor",
"Gilead",
""
]
] |
0708.0438 | Alexander Velytsky | A. Denbleyker, D. Du, Y. Meurice, A. Velytsky | Fisher's zeros of quasi-Gaussian densities of states | 11 pages, 21 figures, with minor corrections | Phys.Rev.D76:116002,2007 | 10.1103/PhysRevD.76.116002 | null | hep-lat cond-mat.stat-mech hep-th | null | We discuss apparent paradoxes regarding the location of the zeros of the
partition function in the complex $\beta$ plane (Fisher's zeros) of a pure
SU(2) lattice gauge theory in 4 dimensions. We propose a new criterion to draw
the region of the complex $\beta$ plane where reweighting methods can be
trusted when the density of states is almost but not exactly Gaussian. We
propose new methods to infer the existence of zeros outside of this region. We
demonstrate the reliability of these proposals with quasi Gaussian Monte Carlo
distributions where the locations of the zeros can be calculated by independent
numerical methods. The results are presented in such way that the methods can
be applied for general lattice models. Applications to specific lattice models
will be discussed in a separate publication.
| [
{
"version": "v1",
"created": "Thu, 2 Aug 2007 23:25:49 GMT"
},
{
"version": "v2",
"created": "Fri, 24 Aug 2007 23:16:52 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Denbleyker",
"A.",
""
],
[
"Du",
"D.",
""
],
[
"Meurice",
"Y.",
""
],
[
"Velytsky",
"A.",
""
]
] |
0708.0439 | Changhyun Ahn | Changhyun Ahn | Meta-Stable Brane Configurations with Seven NS5-Branes | 34pp, 9 figures; Improved the draft and added some footnotes; Figure
1, footnote 7 and captions of Figures 7,8,9 added or improved and to appear
in CQG | Class.Quant.Grav.25:095018,2008 | 10.1088/0264-9381/25/9/095018 | KIAS-P07034 | hep-th | null | We present the intersecting brane configurations consisting of NS-branes,
D4-branes(and anti D4-branes) and O6-plane, of type IIA string theory
corresponding to the meta-stable nonsupersymmetric vacua in four dimensional
N=1 supersymmetric SU(N_c) x SU(N_c') x SU(N_c'') gauge theory with a symmetric
tensor field, a conjugate symmetric tensor field and bifundamental fields. We
also describe the intersecting brane configurations of type IIA string theory
corresponding to the nonsupersymmetric meta-stable vacua in the above gauge
theory with an antisymmetric tensor field, a conjugate symmetric tensor field,
eight fundamental flavors and bifundamentals. These brane configurations
consist of NS-branes, D4-branes(and anti D4-branes), D6-branes and O6-planes.
| [
{
"version": "v1",
"created": "Fri, 3 Aug 2007 00:04:00 GMT"
},
{
"version": "v2",
"created": "Mon, 3 Dec 2007 11:13:00 GMT"
},
{
"version": "v3",
"created": "Fri, 21 Mar 2008 04:12:48 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Ahn",
"Changhyun",
""
]
] |
0708.0440 | Eugene Shakhnovich | Jae Shick Yang, Stefan Wallin, and Eugene Shakhnovich | Universality and diversity of folding mechanics for three-helix bundle
proteins | PNAS, in press, revised version | null | null | null | q-bio.BM | null | In this study we evaluate, at full atomic detail, the folding processes of
two small helical proteins, the B domain of protein A and the Villin headpiece.
Folding kinetics are studied by performing a large number of ab initio Monte
Carlo folding simulations using a single transferable all-atom potential. Using
these trajectories, we examine the relaxation behavior, secondary structure
formation, and transition-state ensembles (TSEs) of the two proteins and
compare our results with experimental data and previous computational studies.
To obtain a detailed structural information on the folding dynamics viewed as
an ensemble process, we perform a clustering analysis procedure based on graph
theory. Moreover, rigorous pfold analysis is used to obtain representative
samples of the TSEs and a good quantitative agreement between experimental and
simulated Fi-values is obtained for protein A. Fi-values for Villin are also
obtained and left as predictions to be tested by future experiments. Our
analysis shows that two-helix hairpin is a common partially stable structural
motif that gets formed prior to entering the TSE in the studied proteins. These
results together with our earlier study of Engrailed Homeodomain and recent
experimental studies provide a comprehensive, atomic-level picture of folding
mechanics of three-helix bundle proteins.
| [
{
"version": "v1",
"created": "Fri, 3 Aug 2007 00:04:37 GMT"
},
{
"version": "v2",
"created": "Fri, 30 Nov 2007 03:32:34 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Yang",
"Jae Shick",
""
],
[
"Wallin",
"Stefan",
""
],
[
"Shakhnovich",
"Eugene",
""
]
] |
0708.0441 | Jacek Dobaczewski | J. Dobaczewski, M.V. Stoitsov, W. Nazarewicz, P.-G. Reinhard | Particle-Number Projection and the Density Functional Theory | 18 RevTex pages, 12 figures, submitted to Physical Review C | Phys.Rev.C76:054315,2007 | 10.1103/PhysRevC.76.054315 | null | nucl-th | null | In the framework of the Density Functional Theory for superconductors, we
study the restoration of the particle number symmetry by means of the
projection technique. Conceptual problems are outlined and numerical
difficulties are discussed. Both are related to the fact that neither the
many-body Hamiltonian nor the wave function of the system appear explicitly in
the Density Functional Theory. Similar obstacles are encountered in
self-consistent theories utilizing density-dependent effective interactions.
| [
{
"version": "v1",
"created": "Fri, 3 Aug 2007 13:21:49 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Dobaczewski",
"J.",
""
],
[
"Stoitsov",
"M. V.",
""
],
[
"Nazarewicz",
"W.",
""
],
[
"Reinhard",
"P. -G.",
""
]
] |
0708.0442 | Stefan Schumacher | S. Schumacher, N. H. Kwong, and R. Binder | Large optical gain from four-wave mixing instabilities in semiconductor
quantum wells | null | Europhys. Lett. 81, 27003 (2008) | 10.1209/0295-5075/81/27003 | null | cond-mat.other | null | Based on a microscopic many-particle theory, we predict large optical gain in
the probe and background-free four-wave mixing directions caused by excitonic
instabilities in semiconductor quantum wells. For a single quantum well with
radiative-decay limited dephasing in a typical pump-probe setup we discuss the
microscopic driving mechanisms and polarization and frequency dependence of
these instabilities.
| [
{
"version": "v1",
"created": "Fri, 3 Aug 2007 00:06:02 GMT"
},
{
"version": "v2",
"created": "Wed, 12 Dec 2007 23:28:00 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Schumacher",
"S.",
""
],
[
"Kwong",
"N. H.",
""
],
[
"Binder",
"R.",
""
]
] |
0708.0443 | Po-Shen Loh | Michael Krivelevich, Po-Shen Loh, Benny Sudakov | Avoiding small subgraphs in Achlioptas processes | 43 pages; reorganized and shortened | null | null | null | math.CO math.PR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For a fixed integer r, consider the following random process. At each round,
one is presented with r random edges from the edge set of the complete graph on
n vertices, and is asked to choose one of them. The selected edges are
collected into a graph, which thus grows at the rate of one edge per round.
This is a natural generalization of what is known in the literature as an
Achlioptas process (the original version has r=2), which has been studied by
many researchers, mainly in the context of delaying or accelerating the
appearance of the giant component.
In this paper, we investigate the small subgraph problem for Achlioptas
processes. That is, given a fixed graph H, we study whether there is an online
algorithm that substantially delays or accelerates a typical appearance of H,
compared to its threshold of appearance in the random graph G(n, M). It is easy
to see that one cannot accelerate the appearance of any fixed graph by more
than the constant factor r, so we concentrate on the task of avoiding H. We
determine thresholds for the avoidance of all cycles C_t, cliques K_t, and
complete bipartite graphs K_{t,t}, in every Achlioptas process with parameter r
>= 2.
| [
{
"version": "v1",
"created": "Fri, 3 Aug 2007 01:08:32 GMT"
},
{
"version": "v2",
"created": "Sat, 25 Oct 2008 04:27:40 GMT"
}
] | 2008-10-25T00:00:00 | [
[
"Krivelevich",
"Michael",
""
],
[
"Loh",
"Po-Shen",
""
],
[
"Sudakov",
"Benny",
""
]
] |
0708.0444 | Yoon-Ho Kim | Myung-Joong Hwang and Yoon-Ho Kim | Practical scheme for non-postselection entanglement concentration using
linear optical elements | null | Phys. Lett. A 369, 208 (2007) | 10.1016/j.physleta.2007.04.098 | null | quant-ph | null | We report a practical non-postselection entanglement concentration scheme in
which a maximally entangled Bell-state photon pair is produced from two pairs
of partially (or non-maximally) entangled photons. Since this scheme is built
only upon linear optical elements and does not require photon-number resolving
detectors, it has immediate applications in experimental implementations of
various quantum information protocols which require two-photon Bell-states.
| [
{
"version": "v1",
"created": "Fri, 3 Aug 2007 01:56:21 GMT"
}
] | 2016-02-23T00:00:00 | [
[
"Hwang",
"Myung-Joong",
""
],
[
"Kim",
"Yoon-Ho",
""
]
] |
0708.0445 | Chow-Choong Ngeow | C. Ngeow (UIUC) and S. Kanbur (SUNY Oswego) | Large Magellanic Cloud Distance from Cepheid Variables using Least
Squares Solutions | 2 pages and 1 figure, to appear in proceeding of "Galaxies in the
Local Volume" Sydney 8-13 July 2007 | null | 10.1007/978-1-4020-6933-8_83 | null | astro-ph | null | Distance to the Large Magellanic Cloud (LMC) is determined using the Cepheid
variables in the LMC. We combine the individual LMC Cepheid distances obtained
from the infrared surface brightness method and a dataset with a large number
of LMC Cepheids. Using the standard least squares method, the LMC distance
modulus can be found from the ZP offsets of these two samples. We have adopted
both a linear P-L relation and a ``broken'' P-L relation in our calculations.
The resulting LMC distance moduli are 18.48+-0.03 mag and 18.49+-0.04 mag
(random error only), respectively, which are consistent to the adopted 18.50
mag in the literature.
| [
{
"version": "v1",
"created": "Fri, 3 Aug 2007 02:13:51 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Ngeow",
"C.",
"",
"UIUC"
],
[
"Kanbur",
"S.",
"",
"SUNY Oswego"
]
] |
0708.0446 | Susumu Ariki | Susumu Ariki | Finite dimensional Hecke algebras | 40 pages,(v2,v3) some minor errors corrected (v4) several more
corrections, references added | null | null | null | math.RT math.QA | null | These are notes prepared for ICRA workshop at Torun, Poland, August 2007. In
the first part, we explain results on canonical basic sets by Geck and Jacon
and propose a categorification framework which is suitable for our example of
Hecke algebras. In the second part, we review basics of Kashiwara crystal and
explain the Fock space theory of cyclotomic Hecke algebras and its
applications. In the third part, we explain Rouquier's theory of
quasihereditary covers of cyclotomic Hecke algebras. We add detailed
explanation of the proofs here. The third part is based on my intensive course
given at Nagoya university in January 2007.
| [
{
"version": "v1",
"created": "Fri, 3 Aug 2007 02:14:05 GMT"
},
{
"version": "v2",
"created": "Mon, 6 Aug 2007 08:49:12 GMT"
},
{
"version": "v3",
"created": "Fri, 10 Aug 2007 16:20:32 GMT"
},
{
"version": "v4",
"created": "Thu, 29 Nov 2007 08:27:54 GMT"
}
] | 2007-11-29T00:00:00 | [
[
"Ariki",
"Susumu",
""
]
] |
0708.0447 | Yoon-Ho Kim | So-Young Baek and Yoon-Ho Kim | Scalable scheme for entangling multiple ququarts using linear optical
elements | null | null | 10.1016/j.physleta.2007.05.033 | null | quant-ph | null | We report a scalable linear optical scheme for generating entangled states of
multiple ququarts in which the individual single-ququart state is prepared with
the biphoton polarization state of frequency-nondegenerate spontaneous
parametric down-conversion. The output state is calculated with the full
consideration of the higher order effect (double-pair events) of spontaneous
parametric down-conversion. Scalability to multiple-ququart entanglement is
demonstrated with examples: linear optical entanglement of three and four
individual biphoton ququarts.
| [
{
"version": "v1",
"created": "Fri, 3 Aug 2007 02:26:33 GMT"
}
] | 2007-08-06T00:00:00 | [
[
"Baek",
"So-Young",
""
],
[
"Kim",
"Yoon-Ho",
""
]
] |
0708.0448 | Matthew Hedden | Matthew Hedden | An Ozsvath-Szabo Floer homology invariant of knots in a contact manifold | 30 pages, no figures | null | null | null | math.GT math.SG | null | Using the knot Floer homology filtration, we define invariants associated to
a knot in a three-manifold possessing non-vanishing Floer co(homology) classes.
In the case of the Ozsvath-Szabo contact invariant we obtain an invariant of
knots in a contact three-manifold. This invariant provides an upper bound for
the Thurston-Bennequin plus rotation number of any Legendrian realization of
the knot. We use it to demonstrate the first systematic construction of prime
knots in contact manifolds other than the three-sphere with negative maximal
Thurston-Bennequin invariant. Perhaps more interesting, our invariant provides
a criterion for an open book to induce a tight contact structure. A corollary
is that if a manifold possesses contact structures with distinct non-vanishing
Ozsvath-Szabo invariants, then any fibered knot can realize the classical
Eliashberg-Bennequin bound in at most one of these contact structures.
| [
{
"version": "v1",
"created": "Fri, 3 Aug 2007 02:42:42 GMT"
},
{
"version": "v2",
"created": "Sun, 5 Aug 2007 13:22:35 GMT"
}
] | 2007-08-06T00:00:00 | [
[
"Hedden",
"Matthew",
""
]
] |
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