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list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0708.0649 | Jonathon Peterson | Jonathon Peterson | Quenched Limits for Transient, Ballistic, Sub-Gaussian One-Dimensional
Random Walk in Random Environment | 28 pages | null | null | null | math.PR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a nearest-neighbor, one-dimensional random walk $\{X_n\}_{n\geq
0}$ in a random i.i.d. environment, in the regime where the walk is transient
with speed v_P > 0 and there exists an $s\in(1,2)$ such that the annealed law
of $n^{-1/s} (X_n - n v_P)$ converges to a stable law of parameter s. Under the
quenched law (i.e., conditioned on the environment), we show that no limit laws
are possible. In particular we show that there exist sequences {t_k} and {t_k'}
depending on the environment only, such that a quenched central limit theorem
holds along the subsequence t_k, but the quenched limiting distribution along
the subsequence t_k' is a centered reverse exponential distribution. This
complements the results of a recent paper of Peterson and Zeitouni
(arXiv:0704.1778v1 [math.PR]) which handled the case when the parameter
$s\in(0,1)$.
| [
{
"version": "v1",
"created": "Sat, 4 Aug 2007 22:03:53 GMT"
},
{
"version": "v2",
"created": "Sat, 11 Jun 2016 02:51:52 GMT"
}
] | 2016-06-14T00:00:00 | [
[
"Peterson",
"Jonathon",
""
]
] |
0708.0650 | Arash Mostofi | A. A. Mostofi, J. R. Yates, Y.-S. Lee, I. Souza, D. Vanderbilt and N.
Marzari | Wannier90: A Tool for Obtaining Maximally-Localised Wannier Functions | Submitted to Computer Physics Communications | Comput. Phys. Commun. 178, 685 (2008) | 10.1016/j.cpc.2007.11.016 | null | cond-mat.mtrl-sci | null | We present Wannier90, a program for calculating maximally-localised Wannier
functions (MLWF) from a set of Bloch energy bands that may or may not be
attached to or mixed with other bands. The formalism works by minimising the
total spread of the MLWF in real space. This done in the space of unitary
matrices that describe rotations of the Bloch bands at each k-point. As a
result, Wannier90 is independent of the basis set used in the underlying
calculation to obtain the Bloch states. Therefore, it may be interfaced
straightforwardly to any electronic structure code. The locality of MLWF can be
exploited to compute band-structure, density of states and Fermi surfaces at
modest computational cost. Furthermore, Wannier90 is able to output MLWF for
visualisation and other post-processing purposes. Wannier functions are already
used in a wide variety of applications. These include analysis of chemical
bonding in real space; calculation of dielectric properties via the modern
theory of polarisation; and as an accurate and minimal basis set in the
construction of model Hamiltonians for large-scale systems, in linear-scaling
quantum Monte Carlo calculations, and for efficient computation of material
properties, such as the anomalous Hall coefficient. Wannier90 is freely
available under the GNU General Public License from http://www.wannier.org/
| [
{
"version": "v1",
"created": "Sat, 4 Aug 2007 23:18:00 GMT"
}
] | 2011-05-18T00:00:00 | [
[
"Mostofi",
"A. A.",
""
],
[
"Yates",
"J. R.",
""
],
[
"Lee",
"Y. -S.",
""
],
[
"Souza",
"I.",
""
],
[
"Vanderbilt",
"D.",
""
],
[
"Marzari",
"N.",
""
]
] |
0708.0651 | John Wisniewski | John P. Wisniewski (1), Karen S. Bjorkman (2), Antonio M. Magalhaes
(3), Jon E. Bjorkman (2), Marilyn R. Meade (4), Antonio Pereyra (3) ((1) NASA
GSFC, (2) University of Toledo, (3) University of Sao Paulo, (4) University
of Wisconsin) | The Role of Evolutionary Age and Metallicity in the Formation of
Classical Be Circumstellar Disks II. Assessing the Evolutionary Nature of
Candidate Disk Systems | 30 pages, accepted by ApJ, emulateapj5 format | null | 10.1086/522293 | null | astro-ph | null | (Abridged version) We present the first detailed imaging polarization
observations of six SMC and six LMC clusters, known to have large populations
of B-type stars which exhibit excess H-alpha emission, to constrain the
evolutionary status of these stars and hence better establish links between the
onset of disk formation in classical Be stars and cluster age and/or
metallicity. The wavelength dependence of our intrinsic polarization data
provides a diagnostic of the dominant and any secondary polarigenic agents
present, enabling us to discriminate pure gas disk systems, i.e. classical Be
stars, from composite gas plus dust disk systems, i.e. Herbig Ae/Be or B[e]
stars. Our intrinsic polarization results, along with available near-IR color
information, strongly supports the suggestion of Wisniewski et al. that
classical Be stars are present in clusters of age 5-8 Myr, and contradict
assertions that the Be phenomenon only develops in the second half of a B
star's main sequence lifetime, i.e. no earlier than 10 Myr.
Comparing the polarimetric properties of our dataset to a similar survey of
Galactic classical Be stars, we find that the prevalence of polarimetric Balmer
jump signatures decreases with metallicity. We speculate that these results
might indicate that either it is more difficult to form large disk systems in
low metallicity environments, or that the average disk temperature is higher in
these low metallicity environments. We have characterized the polarimetric
signatures of all candidate Be stars in our data sample and find ~25% are
unlikely to arise from true classical Be star-disk systems.
| [
{
"version": "v1",
"created": "Sat, 4 Aug 2007 23:37:06 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Wisniewski",
"John P.",
""
],
[
"Bjorkman",
"Karen S.",
""
],
[
"Magalhaes",
"Antonio M.",
""
],
[
"Bjorkman",
"Jon E.",
""
],
[
"Meade",
"Marilyn R.",
""
],
[
"Pereyra",
"Antonio",
""
]
] |
0708.0652 | Daniel Heber Theodoro Franco | Daniel H.T. Franco | A Uniqueness Theorem and Its Application to Field-Theoretical Models
with a Fundamental Length | null | null | null | null | math.FA math-ph math.MP | null | It is shown that if a distribution V of exponential growth has support in a
proper convex cone and its Fourier transform is carried by a closed cone
different from whole space, then V=0. The application of this result to a {\em
quasi-local} quantum field theory (where the fields are localizable only in
regions greater than a certain scale of nonlocality) is contemplated. In
particular, we show that a number of physically important predictions of {\em
local} quantum field theory also hold in a quantum field theory with a
fundamental length, as indicated from string theory.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 00:32:10 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Franco",
"Daniel H. T.",
""
]
] |
0708.0653 | Timothy Yarnall | Timothy Yarnall, Ayman F. Abouraddy, Bahaa E. A. Saleh, and Malvin C.
Teich | Experimental Violation of Bell's Inequality in Spatial-Parity Space | 10 pages, 3 figures, 1 Table | Phys. Rev. Lett. 99, 170408 (2007) | 10.1103/PhysRevLett.99.170408 | null | quant-ph | null | We report the first experimental violation of Bell's inequality in the
spatial domain using the Einstein--Podolsky--Rosen state. Two-photon states
generated via optical spontaneous parametric downconversion are shown to be
entangled in the parity of their one-dimensional transverse spatial profile.
Superpositions of Bell states are prepared by manipulation of the optical
pump's transverse spatial parity--a classical parameter. The Bell-operator
measurements are made possible by devising simple optical arrangements that
perform rotations in the one-dimensional spatial-parity space of each photon of
an entangled pair and projective measurements onto a basis of even--odd
functions. A Bell-operator value of 2.389 +- 0.016 is recorded, a violation of
the inequality by more than 24 standard deviations.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 02:23:53 GMT"
}
] | 2008-05-06T00:00:00 | [
[
"Yarnall",
"Timothy",
""
],
[
"Abouraddy",
"Ayman F.",
""
],
[
"Saleh",
"Bahaa E. A.",
""
],
[
"Teich",
"Malvin C.",
""
]
] |
0708.0654 | James P. Crutchfield | Susanne Still, James P. Crutchfield | Structure or Noise? | 6 pages, 2 figures;
http://cse.ucdavis.edu/~cmg/compmech/pubs/son.html | null | null | null | physics.data-an cond-mat.stat-mech cs.IT cs.LG math-ph math.IT math.MP math.ST nlin.CD stat.TH | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show how rate-distortion theory provides a mechanism for automated theory
building by naturally distinguishing between regularity and randomness. We
start from the simple principle that model variables should, as much as
possible, render the future and past conditionally independent. From this, we
construct an objective function for model making whose extrema embody the
trade-off between a model's structural complexity and its predictive power. The
solutions correspond to a hierarchy of models that, at each level of
complexity, achieve optimal predictive power at minimal cost. In the limit of
maximal prediction the resulting optimal model identifies a process's intrinsic
organization by extracting the underlying causal states. In this limit, the
model's complexity is given by the statistical complexity, which is known to be
minimal for achieving maximum prediction. Examples show how theory building can
profit from analyzing a process's causal compressibility, which is reflected in
the optimal models' rate-distortion curve--the process's characteristic for
optimally balancing structure and noise at different levels of representation.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 01:37:53 GMT"
},
{
"version": "v2",
"created": "Sun, 29 Jun 2008 23:52:26 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Still",
"Susanne",
""
],
[
"Crutchfield",
"James P.",
""
]
] |
0708.0655 | Steve Warren | S. J. Warren, D. J. Mortlock, S. K. Leggett, D. J. Pinfield, D.
Homeier, S. Dye, R. F. Jameson, N. Lodieu, P. W. Lucas, A. J. Adamson, F.
Allard, D. Barrado y Navascues, M. Casali, K. Chiu, N. C. Hambly, P. C.
Hewett, P. Hirst, M. J. Irwin, A. Lawrence, M. C. Liu, E. L. Martin, R. L.
Smart, L. Valdivielso, B. P. Venemans | A very cool brown dwarf in UKIDSS DR1 | To appear in MNRAS | Mon.Not.Roy.Astron.Soc.381:1400-1412,2007 | 10.1111/j.1365-2966.2007.12348.x | null | astro-ph | null | (abridged) We report the discovery of a very cool brown dwarf, ULAS
J003402.77-005206.7 (ULAS J0034-00), identified in UKIDSS DR1. We provide
optical, near-infrared, and mid-infrared photometry of the source, and two
near-infrared spectra. Comparing the spectral energy distribution of ULAS
J0034-00 to that of the T8 brown dwarf 2MASS J0415-09, the latest-type and
coolest well-studied brown dwarf to date, with Teff~750 K, we find evidence
that ULAS J0034-00 is significantly cooler. First, the measured values of the
near-infrared absorption spectral indices imply a later classification, of
T8.5. Second, the H-[4.49] colour provides an empirical estimate of the
temperature of 540<Teff<660 K (+/-2sig range). Third, the J- and H-band peaks
are somewhat narrower in ULAS J0034-00, and detailed comparison against
spectral models calibrated to 2MASS J0415-09 yields an estimated temperature
lower by 60-120 K relative to 2MASS J0415-09 i.e. 630<Teff<690 K (+/-2sig), and
lower gravity or higher metallicity according to the degenerate combination
-0.5<delta(log g-2[m/H])<-0.25 (+/-2sig). Combining these estimates, and
considering systematics, it is likely the temperature lies in the range
600<Teff<700 K. Despite the low inferred Teff we find no evidence for strong
absorption by NH3 over the wavelength range 1.51-1.56 um. Evolutionary models
imply that the mass and age are in the ranges 15-36 M(Jup) and 0.5-8 Gyr,
respectively. The measured proper motion, of (0.37+/-0.07)arcsec/yr, combined
with the photometrically estimated distance of 14-22 pc, implies a tangential
velocity of ~30 km/s. ULAS J0034-00 is significantly bluer than 2MASS J0415-09
in Y-J, so future searches should allow for the possibility that cooler T
dwarfs are bluer still.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 02:32:53 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Warren",
"S. J.",
""
],
[
"Mortlock",
"D. J.",
""
],
[
"Leggett",
"S. K.",
""
],
[
"Pinfield",
"D. J.",
""
],
[
"Homeier",
"D.",
""
],
[
"Dye",
"S.",
""
],
[
"Jameson",
"R. F.",
""
],
[
"Lodieu",
"N.",
""
],
[
"Lucas",
"P. W.",
""
],
[
"Adamson",
"A. J.",
""
],
[
"Allard",
"F.",
""
],
[
"Navascues",
"D. Barrado y",
""
],
[
"Casali",
"M.",
""
],
[
"Chiu",
"K.",
""
],
[
"Hambly",
"N. C.",
""
],
[
"Hewett",
"P. C.",
""
],
[
"Hirst",
"P.",
""
],
[
"Irwin",
"M. J.",
""
],
[
"Lawrence",
"A.",
""
],
[
"Liu",
"M. C.",
""
],
[
"Martin",
"E. L.",
""
],
[
"Smart",
"R. L.",
""
],
[
"Valdivielso",
"L.",
""
],
[
"Venemans",
"B. P.",
""
]
] |
0708.0656 | Wei-Liem Loh | Wei-Liem Loh | A multivariate central limit theorem for randomized orthogonal array
sampling designs in computer experiments | 89 pages | null | null | null | math.ST stat.ME stat.TH | null | Let $f:[0,1)^d \to {\mathbb R}$ be an integrable function. An objective of
many computer experiments is to estimate $\int_{[0,1)^d} f(x) dx$ by evaluating
f at a finite number of points in [0,1)^d. There is a design issue in the
choice of these points and a popular choice is via the use of randomized
orthogonal arrays. This article proves a multivariate central limit theorem for
a class of randomized orthogonal array sampling designs [Owen (1992a)] as well
as for a class of OA-based Latin hypercubes [Tang (1993)].
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 03:35:36 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Loh",
"Wei-Liem",
""
]
] |
0708.0657 | Steven Olmschenk | S. Olmschenk, K. C. Younge, D. L. Moehring, D. Matsukevich, P. Maunz
and C. Monroe | Manipulation and Detection of a Trapped Yb+ Ion Hyperfine Qubit | 10 pages, 9 figures, 1 table | Phys. Rev. A 76, 052314 (2007) | 10.1103/PhysRevA.76.052314 | null | quant-ph | null | We demonstrate the use of trapped ytterbium ions as quantum bits for quantum
information processing. We implement fast, efficient state preparation and
state detection of the first-order magnetic field-insensitive hyperfine levels
of 171Yb+, with a measured coherence time of 2.5 seconds. The high efficiency
and high fidelity of these operations is accomplished through the stabilization
and frequency modulation of relevant laser sources.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 03:45:59 GMT"
}
] | 2008-01-30T00:00:00 | [
[
"Olmschenk",
"S.",
""
],
[
"Younge",
"K. C.",
""
],
[
"Moehring",
"D. L.",
""
],
[
"Matsukevich",
"D.",
""
],
[
"Maunz",
"P.",
""
],
[
"Monroe",
"C.",
""
]
] |
0708.0658 | Akram Mukhamedzhanov | A. M. Mukhamedzhanov, L. D. Blokhintsev, B. F. Irgaziev, A. S.
Kadyrov, M. La Cognata, C. Spitaleri and R. E. Tribble | Trojan Horse as an indirect technique in nuclear astrophysics. Resonance
reactions | 6 pages and 1 figure | J.Phys.G35:014016,2008 | 10.1088/0954-3899/35/1/014016 | null | nucl-th | null | The Trojan Horse method is a powerful indirect technique that provides
information to determine astrophysical factors for binary rearrangement
processes $x + A \to b + B$ at astrophysically relevant energies by measuring
the cross section for the Trojan Horse reaction $a + A \to y+ b + B$ in
quasi-free kinematics. We present the theory of the Trojan Horse method for
resonant binary subreactions based on the half-off-energy-shell R matrix
approach which takes into account the off-energy-shell effects and initial and
final state interactions.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 04:02:45 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Mukhamedzhanov",
"A. M.",
""
],
[
"Blokhintsev",
"L. D.",
""
],
[
"Irgaziev",
"B. F.",
""
],
[
"Kadyrov",
"A. S.",
""
],
[
"La Cognata",
"M.",
""
],
[
"Spitaleri",
"C.",
""
],
[
"Tribble",
"R. E.",
""
]
] |
0708.0659 | David Treumann | David Treumann | Exit paths and constructible stacks | null | null | 10.1112/S0010437X09004229 | null | math.AT | null | For a Whitney stratification S of a space X (or more generally a topological
stratification in the sense of Goresky and MacPherson) we introduce the notion
of an S-constructible stack of categories on X. The motivating example is the
stack of S-constructible perverse sheaves. We introduce a 2-category $EP_{\leq
2}(X,S)$, called the exit-path 2-category, which is a natural stratified
version of the fundamental 2-groupoid. Our main result is that the 2-category
of S-constructible stacks on X is equivalent to the 2-category of 2-functors
from $EP_{\leq 2}(X,S)$ to the 2-category of small categories.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 04:06:38 GMT"
}
] | 2014-01-14T00:00:00 | [
[
"Treumann",
"David",
""
]
] |
0708.0660 | Guanrong Chen | Zhisheng Duan, Chao Liu and Guanrong Chen | Network synchronizability analysis: the theory of subgraphs and
complementary graphs | 13 pages, 7 figures | null | 10.1016/j.physd.2007.12.003 | null | cs.NI cs.GR | null | In this paper, subgraphs and complementary graphs are used to analyze the
network synchronizability. Some sharp and attainable bounds are provided for
the eigenratio of the network structural matrix, which characterizes the
network synchronizability, especially when the network's corresponding graph
has cycles, chains, bipartite graphs or product graphs as its subgraphs.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 05:25:45 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Duan",
"Zhisheng",
""
],
[
"Liu",
"Chao",
""
],
[
"Chen",
"Guanrong",
""
]
] |
0708.0661 | Rong Xiang Mr | Rong Xiang, Zhou Yang, Qiang Zhang, Guohua Luo, Weizhong Qian, Fei
Wei, Masayuki Kadowaki, Shigeo Maruyama | Decelerating Growth of Vertically Aligned Carbon Nanotube Arrays:
Kinetic Controlled or Diffusion Controlled? | 20 pages, 1 table, 4 figures | null | null | null | cond-mat.mtrl-sci cond-mat.other | null | Feedstock and byproduct diffusion in the root growth of aligned CNT arrays
was discussed in this work. A non-dimensional modulus was proposed to
differentiate catalyst-decay controlled growth deceleration from diffusion
controlled one. It was found that aligned MWNT arrays are usually free of
feedstock diffusion while SWNT arrays are usually facing strong diffusion
limit. The present method can also be utilized to predict the maximum length
that CNT forest can grow in certain CVD process.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 07:53:35 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Xiang",
"Rong",
""
],
[
"Yang",
"Zhou",
""
],
[
"Zhang",
"Qiang",
""
],
[
"Luo",
"Guohua",
""
],
[
"Qian",
"Weizhong",
""
],
[
"Wei",
"Fei",
""
],
[
"Kadowaki",
"Masayuki",
""
],
[
"Maruyama",
"Shigeo",
""
]
] |
0708.0662 | Qasem Exirifard | Qasem Exirifard | Constraints on $f(R_{ijkl}R^{ijkl})$ gravity: An evidence against the
covariant resolution of the Pioneer anomaly | ...v5: references added, new discussions added | Class. Quant. Grav. 26: 025001,2009 | 10.1088/0264-9381/26/2/025001 | IPM/P-2007/056 | gr-qc astro-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider corrections in the form of $\Delta L(R_{ijkl}R^{ijkl})$ to the
Einstein-Hilbert Lagrangian. Then we compute the corrections to the
Schwarszchild geometry due to the inclusion of this general term to the
Lagrangian. We show that $\Delta L_3=\alpha_{{1/3}}(R_{ijkl}R^{ijkl})^{{1/3}}$
gives rise to a constant anomalous acceleration for objects orbiting the Sun
onward the Sun. This leads to the conclusion that $\alpha_{{1/3}}=(13.91\pm
2.11) \times 10^{-26}(\frac{1}{\text{meters}})^{{2/3}}$ would have covariantly
resolved the Pioneer anomaly if this value of $\alpha_{{1/3}}$ had not
contradicted other observations.
We notice that the experimental bounds on $\Delta L_3$ grows stronger in case
we examine the deformation of the space-time geometry around objects lighter
than the Sun. We therefore use the high precision measurements around the Earth
(LAGEOS and LLR) and obtain a very strong constraint on the corrections in the
form of $\Delta L(R_{ijkl}R^{ijkl})$ and in particular $\Delta
L=\alpha_n(R_{ijkl}R^{ijkl})^n$. This bound requires
$\alpha_{{1/3}}\leq6.12\times 10^{-29}(\frac{1}{\text{meters}})^{{2/3}}$.
Therefore it refutes the covariant resolution of the Pioneer anomaly.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 09:27:02 GMT"
},
{
"version": "v2",
"created": "Sat, 18 Aug 2007 07:37:13 GMT"
},
{
"version": "v3",
"created": "Mon, 3 Dec 2007 08:35:15 GMT"
},
{
"version": "v4",
"created": "Sat, 5 Apr 2008 11:25:28 GMT"
},
{
"version": "v5",
"created": "Mon, 27 Oct 2008 13:12:54 GMT"
}
] | 2011-09-28T00:00:00 | [
[
"Exirifard",
"Qasem",
""
]
] |
0708.0663 | Grigory Volovik | Yu.M. Bunkov and G.E. Volovik | Bose-Einstein condensation of magnons in superfluid 3He | 10 pages, 5 figures, prepared for proceedings of QFS-2007, JLTP style | J. Low Temp. Phys. 150 (2008) 135-144 | 10.1007/s10909-007-9530-7 | null | cond-mat.other | null | The possibility of Bose-Einstein condensation of excitations has been
discussed for a long time. The phenomenon of the phase-coherent precession of
magnetization in superfluid 3He and the related effects of spin superfluidity
are based on the true Bose-Einstein condensation of magnons. Several different
states of coherent precession has been observed in 3He-B: homogeneously
precessing domain (HPD); persistent signal formed by Q-balls at very low
temperatures; coherent precession with fractional magnetization; and two new
modes of the coherent precession in compressed aerogel. In compressed aerogel
the coherent precession has been also found in 3He-A. Here we demonstrate that
all these cases are examples of a Bose-Einstein condensation of magnons, with
the magnon interaction term in the Gross-Pitaevskii equation being provided by
different types of spin-orbit coupling in the background of the coherent
precession.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 08:44:38 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Bunkov",
"Yu. M.",
""
],
[
"Volovik",
"G. E.",
""
]
] |
0708.0664 | Lajos Di\'osi | Lajos Di\'osi | Shortnote on local hidden Grassmann variables vs. quantum correlations | 2pp | null | null | null | quant-ph | null | Grassmannian local hidden variables are shown to generate all possible
quantum correlations in a bipartite quantum system. Grassmann representation of
fermions, common in field theory, opens a related perspective. Although
Grassmann hidden variables can not challange Bell's locality theorem, they can
become an interesting mathematical tool to investigate entanglement.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 08:49:02 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Diósi",
"Lajos",
""
]
] |
0708.0665 | Miroslav Grajcar | M. Grajcar, S.H.W. van der Ploeg, A. Izmalkov, E. Il'ichev, H.-G.
Meyer, A. Fedorov, A. Shnirman, Gerd Sch\"on | Sisyphus cooling and amplification by a superconducting qubit | 7 pages, 4 figures | null | 10.1038/nphys1019 | null | cond-mat.supr-con | null | Laser cooling of the atomic motion paved the way for remarkable achievements
in the fields of quantum optics and atomic physics, including Bose-Einstein
condensation and the trapping of atoms in optical lattices. More recently
superconducting qubits were shown to act as artificial two-level atoms,
displaying Rabi oscillations, Ramsey fringes, and further quantum effects.
Coupling such qubits to resonators brought the superconducting circuits into
the realm of quantum electrodynamics (circuit QED). It opened the perspective
to use superconducting qubits as micro-coolers or to create a population
inversion in the qubit to induce lasing behavior of the resonator. Furthering
these analogies between quantum optical and superconducting systems we
demonstrate here Sisyphus cooling of a low frequency LC oscillator coupled to a
near-resonantly driven superconducting qubit. In the quantum optics setup the
mechanical degrees of freedom of an atom are cooled by laser driving the atom's
electronic degrees of freedom. Here the roles of the two degrees of freedom are
played by the LC circuit and the qubit's levels, respectively. We also
demonstrate the counterpart of the Sisyphus cooling, namely Sisyphus
amplification. Parallel to the experimental demonstration we analyze the system
theoretically and find quantitative agreement, which supports the
interpretation and allows us to estimate system parameters.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 10:29:16 GMT"
},
{
"version": "v2",
"created": "Mon, 19 May 2008 16:47:53 GMT"
}
] | 2008-07-08T00:00:00 | [
[
"Grajcar",
"M.",
""
],
[
"van der Ploeg",
"S. H. W.",
""
],
[
"Izmalkov",
"A.",
""
],
[
"Il'ichev",
"E.",
""
],
[
"Meyer",
"H. -G.",
""
],
[
"Fedorov",
"A.",
""
],
[
"Shnirman",
"A.",
""
],
[
"Schön",
"Gerd",
""
]
] |
0708.0666 | Arbab Ibrahim Arbab | Arbab I. Arbab | On the Planetary acceleration and the Rotation of the Earth | 8 Latex pages | Astrophys.Space Sci.314:35-39,2008 | 10.1007/s10509-007-9731-1 | null | astro-ph | null | We have developed a model for the Earth rotation that gives a good account
(data) of the Earth astronomical parameters. These data can be compared with
the ones obtained using space-base telescopes. The expansion of the universe
has an impact on the rotation of planets, and in particular, the Earth. The
expansion of the universe causes an acceleration that is exhibited by all
planets.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 07:55:51 GMT"
}
] | 2011-04-01T00:00:00 | [
[
"Arbab",
"Arbab I.",
""
]
] |
0708.0667 | Joanna Modlawska MSc | Joanna Modlawska and Andrzej Grudka | Nonmaximally entangled states can be better for multiple linear optical
teleportation | 4 pages, 3 figures | Phys. Rev. Lett. 100, 110503 (2008) | 10.1103/PhysRevLett.100.110503 | null | quant-ph | null | We investigate multiple linear optical teleportation in the
Knill-Laflamme-Milburn scheme with both maximally and nonmaximally entangled
states. We show that if the qubit is teleported several times via nonmaximally
entangled state then the errors introduced in the previous teleportations can
be corrected by the errors introduced in the following teleportations. This
effect is so strong that it leads to another interesting phenomenon, i.e., the
total probability of successful multiple linear optical teleportation is higher
for nonmaximally entangled states than maximally entangled states.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 12:11:35 GMT"
},
{
"version": "v2",
"created": "Mon, 17 Mar 2008 17:33:04 GMT"
}
] | 2008-07-24T00:00:00 | [
[
"Modlawska",
"Joanna",
""
],
[
"Grudka",
"Andrzej",
""
]
] |
0708.0668 | Shin Sasaki | Masato Arai, Claus Montonen, Nobuchika Okada, Shin Sasaki | Meta-stable Vacuum in Spontaneously Broken N=2 Supersymmetric Gauge
Theory | 27 pages, 11 figures, journal reference added, minor modifications in
the text | Phys.Rev.D76:125009,2007 | 10.1103/PhysRevD.76.125009 | HIP-2007-41/TH | hep-th hep-ph | null | We consider an N=2 supersymmetric SU(2) \times U(1) gauge theory with N_f=2
massless flavors and a Fayet-Iliopoulos (FI) term. In the presence of the FI
term, supersymmetry is spontaneously broken at tree level (on the Coulomb
branch), leaving a pseudo-flat direction in the classical potential. This
vacuum degeneracy is removed once quantum corrections are taken into account.
Due to the SU(2) gauge dynamics, the effective potential exhibits a local
minimum at the dyon point, where not only supersymmetry but also U(1)_R
symmetry is broken, while a supersymmetric vacuum would be realized toward
infinity with the runaway behavior of the potential. This local minimum is
found to be parametrically long-lived. Interestingly, from a phenomenological
point of view, in this meta-stable vacuum the massive hypermultiplets inherent
in the theory play the role of the messenger fields in the gauge mediation
scenario, when the Standard Model gauge group is embedded into their flavor
symmetry.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 12:17:27 GMT"
},
{
"version": "v2",
"created": "Mon, 10 Sep 2007 12:26:16 GMT"
},
{
"version": "v3",
"created": "Mon, 10 Dec 2007 15:24:57 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Arai",
"Masato",
""
],
[
"Montonen",
"Claus",
""
],
[
"Okada",
"Nobuchika",
""
],
[
"Sasaki",
"Shin",
""
]
] |
0708.0669 | Shamgar Gurevich | Shamgar Gurevich (Berkeley) and Ronny Hadani (Chicago) | Notes on quantization of symplectic vector spaces over finite fields | Notes from the lecture at the AGAQ conference (Istanbul, June 2006)
on our solution to Kazhdan's problem on canonical quantization | null | null | null | math-ph math.MP math.RT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In these notes we construct a quantization functor, associating an Hilbert
space H(V) to a finite dimensional symplectic vector space V over a finite
field F_q. As a result, we obtain a canonical model for the Weil representation
of the symplectic group Sp(V). The main technical result is a proof of a
stronger form of the Stone-von Neumann theorem for the Heisenberg group over
F_q. Our result answers, for the case of the Heisenberg group, a question of
Kazhdan about the possible existence of a canonical Hilbert space attached to a
coadjoint orbit of a general unipotent group over F_q.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 12:26:47 GMT"
},
{
"version": "v2",
"created": "Sat, 12 Jul 2008 12:10:33 GMT"
},
{
"version": "v3",
"created": "Mon, 20 Apr 2009 05:44:05 GMT"
}
] | 2009-04-20T00:00:00 | [
[
"Gurevich",
"Shamgar",
"",
"Berkeley"
],
[
"Hadani",
"Ronny",
"",
"Chicago"
]
] |
0708.0670 | Jonathan Breuer | Jonathan Breuer | Spectral and Dynamical Properties of Certain Random Jacobi Matrices with
Growing Parameters | 26 pages, some typos corrected and some remarks added | null | null | null | math.SP math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, a family of random Jacobi matrices, with off-diagonal terms
that exhibit power-law growth, is studied. Since the growth of the randomness
is slower than that of these terms, it is possible to use methods applied in
the study of Schr\"odinger operators with random decaying potentials. A
particular result of the analysis is the existence of operators with
arbitrarily fast transport whose spectral measure is zero dimensional. The
results are applied to the infinite Gaussian $\beta$ Ensembles and their
spectral properties are analyzed.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 12:38:35 GMT"
},
{
"version": "v2",
"created": "Mon, 16 Jun 2008 18:07:04 GMT"
}
] | 2008-06-16T00:00:00 | [
[
"Breuer",
"Jonathan",
""
]
] |
0708.0671 | Guohuai Zhu | Mingxing Luo, Wei Wu and Guohuai Zhu | Unparticle Physics and A_{FB}^b on the Z pole | Version to appear in Phys. Lett. B. 13 pages, 5 figures | Phys.Lett.B659:349-356,2008 | 10.1016/j.physletb.2007.10.085 | null | hep-ph | null | An attempt has been made to address the 3\sigma anomaly of the
forward-backward asymmetry of b quark in LEP data via an unparticle sector. For
most part of the parameter space except certain particular regions, the anomaly
could not be explained away plausibly, when constraints from other LEP
observables are taken into account.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 02:40:31 GMT"
},
{
"version": "v2",
"created": "Thu, 3 Jan 2008 02:56:35 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Luo",
"Mingxing",
""
],
[
"Wu",
"Wei",
""
],
[
"Zhu",
"Guohuai",
""
]
] |
0708.0672 | Juan Maldacena | Luis F. Alday and Juan Maldacena | Comments on operators with large spin | 33 pages, 1 figure,v2:reference to more recent work added, minor
corrections | JHEP0711:019,2007 | 10.1088/1126-6708/2007/11/019 | null | hep-th | null | We consider high spin operators. We give a general argument for the
logarithmic scaling of their anomalous dimensions which is based on the
symmetries of the problem. By an analytic continuation we can also see the
origin of the double logarithmic divergence in the Sudakov factor. We show that
the cusp anomalous dimension is the energy density for a flux configuration of
the gauge theory on $AdS_3 \times S^1$. We then focus on operators in ${\cal
N}=4$ super Yang Mills which carry large spin and SO(6) charge and show that in
a particular limit their properties are described in terms of a bosonic O(6)
sigma model. This can be used to make certain all loop computations in the
string theory.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 19:42:12 GMT"
},
{
"version": "v2",
"created": "Mon, 6 Aug 2007 21:54:04 GMT"
},
{
"version": "v3",
"created": "Fri, 26 Oct 2007 15:16:58 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Alday",
"Luis F.",
""
],
[
"Maldacena",
"Juan",
""
]
] |
0708.0673 | Tyrel McQueen | T. McQueen, Q. Xu, E. N. Andersen, H. W. Zandbergen, R. J. Cava | Structures of the reduced niobium oxides Nb12O29 and Nb22O54 | 19 pages, 4 figures, accepted to J. Sol. St. Chem | J. Sol. St. Chem. 180, 2864-2870 (2007) | 10.1016/j.jssc.2007.08.013 | null | cond-mat.mtrl-sci | null | The crystal structure of Nb22O54 is reported for the first time, and the
structure of orthorhombic Nb12O29 is reexamined, resolving previous
ambiguities. Single crystal x-ray and electron diffraction were employed. These
compounds were found to crystallize in the space groups P2/m (a = 15.7491(2) A,
b = 3.8236(3) A, c = 17.8521(2) A, beta = 102.029(3)) and Cmcm (a = 3.8320(2)
A, b = 20.7400(9) A, c = 28.8901(13) A) respectively and share a common
structural unit, a 4x3 block of corner sharing NbO6 octahedra. Despite
different constraints imposed by symmetry these blocks are very similar in both
compounds. Within a block, it is found that the niobium atoms are not located
in the centers of the oxygen octahedra, but rather are displaced inward toward
the center of the block forming an apparent antiferroelectric state. Bond
valence sums and bond lengths do not show the presence of charge ordering,
suggesting that all 4d electrons are delocalized in these compounds at the
temperature studied, T = 200 K.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 13:31:08 GMT"
}
] | 2009-02-02T00:00:00 | [
[
"McQueen",
"T.",
""
],
[
"Xu",
"Q.",
""
],
[
"Andersen",
"E. N.",
""
],
[
"Zandbergen",
"H. W.",
""
],
[
"Cava",
"R. J.",
""
]
] |
0708.0674 | Paolo Tozzi | Paolo Tozzi | Emission Lines in X-ray Spectra of Clusters of Galaxies | 8 pages, 3 figures, Proceedings of the VI Serbian Conference on
Spectral Line Shapes in Astrophysics, Sremski Karlovci, Serbia June 11-15
2007 | AIPConf.Proc.938:43-50,2007 | 10.1063/1.2800151 | null | astro-ph | null | Emission lines in X-ray spectra of clusters of galaxies reveal the presence
of heavy elements in the diffuse hot plasma (the Intra Cluster Medium, or ICM)
in virial equilibrium in the dark matter potential well. The relatively simple
physical state of the ICM allows us to estimate, with good accuracy, its
thermodynamical properties and chemical abundances. These measures put strong
constraints on the interaction processes between the galaxies and the
surrounding medium, and have significant impact on models of galaxy formation
as well. This field is rapidly evolving thanks to the X-ray satellites Chandra
and XMM-Newton. Among the most relevant progresses in the last years, we
briefly discuss the nature of cool cores and the measure of the Iron abundance
in high redshift clusters. Future X-ray missions with bolometers promise to
provide a substantial step forward to a more comprehensive understanding of the
complex physics of the ICM.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 17:00:39 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Tozzi",
"Paolo",
""
]
] |
0708.0675 | Angelo Tartaglia | A. Tartaglia, N. Radicella | Vector field theories in cosmology | 19 pages, 1 figure, to appear on Phys. Rev. D | Phys.Rev.D76:083501,2007 | 10.1103/PhysRevD.76.083501 | null | gr-qc | null | Recently proposed theories based on the cosmic presence of a vectorial field
are compared and contrasted. In particular the so called Einstein aether theory
is discussed in parallel with a recent proposal of a strained space-time theory
(Cosmic Defect theory). We show that the latter fits reasonably well the cosmic
observed data with only one, or at most two, adjustable parameters, whilst
other vector theories use much more. The Newtonian limits are also compared.
Finally we show that the CD theory may be considered as a special case of the
aether theories, corresponding to a more compact and consistent paradigm.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 15:17:23 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Tartaglia",
"A.",
""
],
[
"Radicella",
"N.",
""
]
] |
0708.0676 | S. Yang | S. Yang, D. L. Zhou, C. P. Sun | Mosaic spin models with topological order | 4 pages, 3 figures. Final version to appear in Phys. Rev. B as a
Rapid Communication | Phys. Rev. B 76, 180404(R) (2007) | 10.1103/PhysRevB.76.180404 | null | cond-mat.str-el quant-ph | null | We study a class of two-dimensional spin models with the Kitaev-type
couplings in mosaic structure lattices to implement topological orders. We show
that they are exactly solvable by reducing them to some free Majorana fermion
models with gauge symmetries. The typical case with a 4-8-8 close packing is
investigated in detail to display the quantum phases with Abelian and
non-Abelian anyons. Its topological properties characterized by Chern numbers
are revealed through the edge modes of its spectrum.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 03:24:50 GMT"
},
{
"version": "v2",
"created": "Tue, 14 Aug 2007 13:20:42 GMT"
},
{
"version": "v3",
"created": "Fri, 2 Nov 2007 12:23:55 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Yang",
"S.",
""
],
[
"Zhou",
"D. L.",
""
],
[
"Sun",
"C. P.",
""
]
] |
0708.0677 | Hans F. de Groote | Hans F. de Groote | Observables IV: The presheaf perspective | 35 pages | null | null | null | math-ph math.MP math.OA quant-ph | null | In this fourth of our series of papers on observables we show that one can
associate to each von Neumann algebra R a pair of isomorphic presheaves, the
upper presheaf O^{+}_{R} and the lower presheaf O^{-}_{R}, on the category of
abelian von Neumann subalgebras of R. Each $A \in R_{sa}$ induces a global
section of O^{+}_{R} and of O^{-}_{R} respectively. We call them \emph
{contextual observables}. But we show that, in general, not every global
section of these presheaves arises in this way. Moreover, we discuss states of
a von Neumann algebra in the presheaf context.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 16:43:44 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"de Groote",
"Hans F.",
""
]
] |
0708.0678 | Aparna Baskaran | Aparna Baskaran, James W. Dufty and J. Javier Brey | Kinetic Theory of Response Functions for the Hard Sphere Granular Fluid | Submitted to J. Stat. Mech | null | 10.1088/1742-5468/2007/12/P12002 | null | cond-mat.soft cond-mat.stat-mech | null | The response functions for small spatial perturbations of a homogeneous
granular fluid have been described recently. In appropriate dimensionless
variables, they have the form of stationary state time correlation functions.
Here, these functions are expressed in terms of reduced single particle
functions that are expected to obey a linear kinetic equation. The functional
assumption required for such a kinetic equation, and a Markov approximation for
its implementation are discussed. If, in addition, static velocity correlations
are neglected, a granular fluid version of the linearized Enskog kinetic theory
is obtained. The derivation makes no a priori limitation on the density, space
and time scale, nor degree of inelasticity. As an illustration, recently
derived Helfand and Green-Kubo expressions for the Navier-Stokes order
transport coefficients are evaluated with this kinetic theory. The results are
in agreement with those obtained from the Chapman-Enskog solution to the
nonlinear Enskog kinetic equation.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 17:12:31 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Baskaran",
"Aparna",
""
],
[
"Dufty",
"James W.",
""
],
[
"Brey",
"J. Javier",
""
]
] |
0708.0679 | Mark Fels | I.M. Anderson, M.E. Fels, P.J. Vassiliou | Superposition Formulas for Darboux Integrable Exterior Differential
Systems | 80 page report. Updated version with some new sections, and major
improvements to others | null | null | null | math.DG math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we present a far-reaching generalization of E. Vessiot's
analysis of the Darboux integrable partial differential equations in one
dependent and two independent variables. Our approach provides new insights
into this classical method, uncovers the fundamental geometric invariants of
Darboux integrable systems, and provides for systematic, algorithmic
integration of such systems. This work is formulated within the general
framework of Pfaffian exterior differential systems and, as such, has
applications well beyond those currently found in the literature. In
particular, our integration method is applicable to systems of hyperbolic PDE
such as the Toda lattice equations, 2 dimensional wave maps and systems of
overdetermined PDE.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 17:34:48 GMT"
},
{
"version": "v2",
"created": "Wed, 11 Jun 2008 17:16:10 GMT"
}
] | 2008-06-11T00:00:00 | [
[
"Anderson",
"I. M.",
""
],
[
"Fels",
"M. E.",
""
],
[
"Vassiliou",
"P. J.",
""
]
] |
0708.0680 | Saibal Ray | U. Mukhopadhyay, Saibal Ray and S. B. Dutta Choudhury | $\Lambda$-CDM Universe: A Phenomenological Approach With Many
Possibilities | 10 Latex pages; Corrected typos; To appear in Int. J. Mod. Phys. D | Int.J.Mod.Phys.D17:301-309,2008 | 10.1142/S0218271808012012 | null | gr-qc | null | A time-dependent phenomenological model of $\Lambda$, viz. $\dot \Lambda\sim
H^3$ is selected to investigate the $\Lambda$-CDM cosmology. Time-dependent
form of the equation of state parameter $\omega$ is derived and it has been
possible to obtain the sought for flip of sign of the deceleration parameter q.
Present age of the Universe, calculated for some specific values of the
parameters agrees very well with the observational data.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 18:03:45 GMT"
},
{
"version": "v2",
"created": "Wed, 12 Mar 2008 17:49:47 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Mukhopadhyay",
"U.",
""
],
[
"Ray",
"Saibal",
""
],
[
"Choudhury",
"S. B. Dutta",
""
]
] |
0708.0681 | Guenter Nimtz | G. Nimtz and A. A. Stahlhofen | Macroscopic violation of special relativity | 2 pages pdf-file, 2 figures | null | null | null | quant-ph | null | Feynman one of the founders of Quantum Electronic Dynamics (QED) introduced
in his diagrams virtual particles as intermediate states of an interaction
process. Such virtual particles are not observable, however, from the
theoretical point of view they represent necessary intermediate states between
observable real states. Such virtual particles were introduced for describing
the interaction process between an electron and a positron and for much more
complicated interaction processes. Other candidates for virtual photons are
evanescent modes known from optics. Evanescent modes have a purely imaginary
wave number, they represent the mathematical analogy of the tunneling solutions
of the Schr\"odinger equation. Evanescent modes are present in the optical
processes of total reflection and in undersized wave guides for instance. The
most prominent example of the occurrence of evanescent modes is frustrated
total internal reflection at double prisms. In 1949 Sommerfeld
\cite{Sommerfeld} pointed out that this optical phenomenon represents the
analogy of quantum mechanical tunneling. The evanescent modes and tunneling
violate the theory of special relativity, obviously, they represent the
exception which proves the special theory of relativity. We demonstrate the
quantum mechanical behavior of evanescent modes \textbf{with digital microwave}
signals at a macroscopic scale of the order of a meter and show that evanescent
modes are well described by virtual photons as predicted by former QED
calculations.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 18:16:37 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Nimtz",
"G.",
""
],
[
"Stahlhofen",
"A. A.",
""
]
] |
0708.0682 | Anton Zeitlin | Anton M. Zeitlin | Perturbed Beta-Gamma Systems and Complex Geometry | LaTeX2e, 27 pages | Nucl.Phys.B794:381-401,2008 | 10.1016/j.nuclphysb.2007.09.002 | null | hep-th math-ph math.DG math.MP | null | We consider the equations, arising as the conformal invariance conditions of
the perturbed curved beta-gamma system. These equations have the physical
meaning of Einstein equations with a B-field and a dilaton on a hermitian
manifold, where the B-field 2-form is imaginary and proportional to the
canonical form associated with hermitian metric. We show that they decompose
into linear and bilinear equations and lead to the vanishing of the first Chern
class of the manifold where the system is defined. We discuss the relation of
these equations to the generalized Maurer-Cartan structures related to BRST
operator. Finally we describe the relations of the generalized Maurer-Cartan
bilinear operation and the Courant/Dorfman brackets.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 18:25:14 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Zeitlin",
"Anton M.",
""
]
] |
0708.0683 | Creighton Thomas | Creighton K. Thomas, Olivia L. White, A. Alan Middleton | Persistence and Memory in Patchwork Dynamics for Glassy Models | 4 pages, 4 figures; reference correction | Physical Review B 77, 092415 (2008) | 10.1103/PhysRevB.77.092415 | null | cond-mat.dis-nn cond-mat.stat-mech | null | Slow dynamics in disordered materials prohibits direct simulation of their
rich nonequilibrium behavior at large scales. "Patchwork dynamics" is
introduced to mimic relaxation over a very broad range of time scales by
equilibrating or optimizing directly on successive length scales. This dynamics
is used to study coarsening and to replicate memory effects for spin glasses
and random ferromagnets. It is also used to find, with high confidence, exact
ground states in large or toroidal samples.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 21:39:32 GMT"
},
{
"version": "v2",
"created": "Fri, 10 Aug 2007 14:35:21 GMT"
}
] | 2009-06-30T00:00:00 | [
[
"Thomas",
"Creighton K.",
""
],
[
"White",
"Olivia L.",
""
],
[
"Middleton",
"A. Alan",
""
]
] |
0708.0684 | Madhurjya Bora | Madhurjya P Bora and Dipak Sarmah | Parametric excitation and chaos through dust-charge fluctuation in a
dusty plasma | 10 pages, 16 figures | null | null | null | nlin.CD physics.plasm-ph | null | We consider a van der Pol-Mathieu (vdPM) equation with parametric forcing,
which arises in a simplified model of dusty plasma with dust-charge
fluctuation. We make a detailed numerical investigation and show that the
system can be driven to chaos either through a period doubling cascade or
though a subcritical pitchfork bifurcation over an wide range of parameter
space. We also discuss the frequency entrainment or frequency-locked phase of
the dust-charge fluctuation dynamics and show that the system exhibits 2:1
parametric resonance away from the chaotic regime.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 19:08:43 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Bora",
"Madhurjya P",
""
],
[
"Sarmah",
"Dipak",
""
]
] |
0708.0685 | Manlio Tassieri | Manlio Tassieri, R. M. L. Evans, Lucian Barbu-Tudoran, G. Nasir Khan,
John Trinick, Tom A. Waigh | Dynamics of semi-flexible polymer solutions in the highly entangled
regime | 4 pages, 6 figures, Phys. Rev. Lett. (accepted) | null | 10.1103/PhysRevLett.101.198301 | null | cond-mat.soft | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present experimental evidence that the effective medium approximation
(EMA), developed by D.C. Morse [Phys. Rev. E {\bf 63}, 031502, (2001)],
provides the correct scaling law of the macroscopic plateau modulus
$G^{0}\propto\rho^{4/3}L^{-1/3}_{p}$ (where $\rho$ is the contour length per
unit volume and $L_{p}$ is the persistence length) of semi-flexible polymer
solutions, in the highly entangled concentration regime. Competing theories,
including a self-consistent binary collision approximation (BCA), have instead
predicted $G^{0}\propto\rho^{7/5}L^{-1/5}_{p}$. We have tested both the EMA and
BCA scaling predictions using actin filament (F-actin) solutions which permit
experimental control of $L_p$ independently of other parameters. A combination
of passive video particle tracking microrheology and dynamic light scattering
yields independent measurements of the elastic modulus $G$ and $L_{p}$
respectively. Thus we can distinguish between the two proposed laws, in
contrast to previous experimental studies, which focus on the (less
discriminating) concentration functionality of $G$.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 19:25:13 GMT"
},
{
"version": "v2",
"created": "Fri, 17 Oct 2008 16:27:18 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Tassieri",
"Manlio",
""
],
[
"Evans",
"R. M. L.",
""
],
[
"Barbu-Tudoran",
"Lucian",
""
],
[
"Khan",
"G. Nasir",
""
],
[
"Trinick",
"John",
""
],
[
"Waigh",
"Tom A.",
""
]
] |
0708.0686 | Stefano Isola | Claudio Bonanno, Sandro Graffi, Stefano Isola | Spectral analysis of transfer operators associated to Farey fractions | 28 pages, 1 figure | null | null | null | math-ph math.DS math.MP | null | The spectrum of a one-parameter family of signed transfer operators
associated to the Farey map is studied in detail. We show that when acting on a
suitable Hilbert space of analytic functions they are self-adjoint and exhibit
absolutely continuous spectrum and no non-zero point spectrum. Polynomial
eigenfunctions when the parameter is a negative half-integer are also
discussed.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 19:29:17 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Bonanno",
"Claudio",
""
],
[
"Graffi",
"Sandro",
""
],
[
"Isola",
"Stefano",
""
]
] |
0708.0687 | Subir Sachdev | Adrian del Maestro, Bernd Rosenow, Nayana Shah, and Subir Sachdev | Universal thermal and electrical transport near the superconductor-metal
quantum phase transition in nanowires | 4 pages, 1 figure | Physical Review B 77, 180501 (2008) | 10.1103/PhysRevB.77.180501 | null | cond-mat.supr-con cond-mat.str-el | null | We describe the thermal and electrical conductivities of quasi-one
dimensional wires, across a quantum phase transition from a superconductor to a
metal induced by pairbreaking perturbations. Fluctuation corrections to BCS
theory motivate a field theory for quantum criticality. We describe deviations
in the Wiedemann-Franz ratio from the Lorenz number, which can act as sensitive
tests of the theory. We also describe the crossovers out of the quantum
critical region into the metallic and superconducting phases.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 20:00:50 GMT"
}
] | 2008-05-09T00:00:00 | [
[
"del Maestro",
"Adrian",
""
],
[
"Rosenow",
"Bernd",
""
],
[
"Shah",
"Nayana",
""
],
[
"Sachdev",
"Subir",
""
]
] |
0708.0688 | Tal Alexander | Tal Alexander (Weizmann Institute of Science) | Stellar Relaxation Processes Near the Galactic Massive Black Hole | Invited talk. To appear in "2007 STScI spring symposium: Black
Holes", eds, M. Livio & A. M. Koekemoer, Cambridge University Press, in
press. 25 pages, 13 figures | null | null | null | astro-ph | null | The massive black hole (MBH) in the Galactic Center and the stars around it
form a unique stellar dynamics laboratory for studying how relaxation processes
affect the distribution of stars and compact remnants and lead to close
interactions between them and the MBH. Recent theoretical studies suggest that
processes beyond "minimal" two-body relaxation may operate and even dominate
relaxation and its consequences in the Galactic Center. I describe loss-cone
refilling by massive perturbers, strong mass segregation and resonant
relaxation; review observational evidence that these processes play a role in
the Galactic Center; and discuss some cosmic implications for the rates of
gravitational wave emission events from compact remnants inspiraling into MBHs,
and the coalescence timescales of binary MBHs.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 22:52:30 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Alexander",
"Tal",
"",
"Weizmann Institute of Science"
]
] |
0708.0689 | Nicholas Young | N. J. Young | The automorphism group of the tetrablock | 13 pages, 0 figures | null | 10.1112/jlms/jdn010 | null | math.CV | null | The tetrablock is a domain in 3-dimensional complex space that meets
3-dimensional Euclidean space in a regular tetrahedron. It is shown to be
inhomogeneous and its automorphism group is determined. A type of Schwarz lemma
for the tetrablock is proved. The action of the automorphism group is described
in terms of a certain natural foliation of the tetrablock by complex geodesic
discs.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 21:01:43 GMT"
}
] | 2014-02-26T00:00:00 | [
[
"Young",
"N. J.",
""
]
] |
0708.0690 | Henning Schomerus | Marten Kopp, Henning Schomerus, Stefan Rotter | Staggered repulsion of transmission eigenvalues in symmetric open
mesoscopic systems | 11 pages, 6 Figures, substantially extended | Phys. Rev. B 78, 075312 (2008) | 10.1103/PhysRevB.78.075312 | null | cond-mat.mes-hall | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum systems with discrete symmetries can usually be desymmetrized, but
this strategy fails when considering transport in open systems with a symmetry
that maps different openings onto each other. We investigate the joint
probability density of transmission eigenvalues for such systems in
random-matrix theory. In the orthogonal symmetry class we show that the
eigenvalue statistics manifests level repulsion between only every second
transmission eigenvalue. This finds its natural statistical interpretation as a
staggeredsuperposition of two eigenvalue sequences. For a large number of
channels, the statistics for a system with a lead-transposing symmetry
approaches that of a superposition of two uncorrelated sets of eigenvalues as
in systems with a lead-preserving symmetry (which can be desymmetrized). These
predictions are confirmed by numerical computations of the
transmission-eigenvalue spacing distribution for quantum billiards and for the
open kicked rotator.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 21:51:49 GMT"
},
{
"version": "v2",
"created": "Fri, 8 Aug 2008 19:55:08 GMT"
}
] | 2008-08-14T00:00:00 | [
[
"Kopp",
"Marten",
""
],
[
"Schomerus",
"Henning",
""
],
[
"Rotter",
"Stefan",
""
]
] |
0708.0691 | Kathrin Bringmann | Kathrin Bringmann | Asymptotics for rank partition functions | 19 pages Transactions of the AMS, accepted for publication | null | null | null | math.NT | null | In this paper, we obtain asymptotic formulas for an infinite class of rank
generating functions. As an application, we solve a conjecture of Andrews and
Lewis on inequalities between certain ranks.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 22:33:23 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Bringmann",
"Kathrin",
""
]
] |
0708.0692 | Kathrin Bringmann | Kathrin Bringmann and Jeremy Lovejoy | Dyson's Rank, overpartitions, and weak Maass forms | 24 pages IMRN, accepted for publication | null | null | null | math.NT | null | In a series of papers the first author and Ono connected the rank, a
partition statistic introduced by Dyson, to weak Maass forms, a new class of
functions which are related to modular forms. Naturally it is of wide interest
to find other explicit examples of Maass forms. Here we construct a new
infinite family of such forms, arising from overpartitions. As applications we
obtain combinatorial decompositions of Ramanujan-type congruences for
overpartitions as well as the modularity of rank differences in certain
arithmetic progressions.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 22:36:49 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Bringmann",
"Kathrin",
""
],
[
"Lovejoy",
"Jeremy",
""
]
] |
0708.0693 | L. C. Garcia de Andrade | Garcia de Andrade | Stretch fast dynamo mechanism via conformal mapping in Riemannian
manifolds | Depto de fisica terica, UERJ, Rio de Janeiro, Brasil | null | null | null | math-ph math.MP | null | Two new analytical solutions of self-induction equation, in Riemannian
manifolds are presented. The first represents a twisted magnetic flux tube or
flux rope in plasma astrophysics, which shows that the depending on rotation of
the flow the poloidal field is amplified from toroidal field which represents a
dynamo. The value of the amplification depends on the Frenet torsion of the
magnetic axis of the tube. Actually this result illustrates the Zeldovich
stretch, twist and fold (STF) method to generate dynamos from straight and
untwisted ropes. Motivated by the fact that this problem was treated using a
Riemannian geometry of twisted magnetic flux ropes recently developed (Phys
Plasmas (2006)), we investigated a second dynamo solution which is conformally
related to the Arnold kinematic fast dynamo. In this solution it is shown that
the conformal effect on the fast dynamo metric only enhances the Zeldovich
stretch, and therefore a new dynamo solution is obtained. When a conformal
mapping is performed in Arnold fast dynamo line element a uniform stretch is
obtained in the original line element.
| [
{
"version": "v1",
"created": "Sun, 5 Aug 2007 23:12:42 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"de Andrade",
"Garcia",
""
]
] |
0708.0694 | Maurice H. T. Ling | Maurice HT Ling, Christophe Lefevre, Kevin R. Nicholas, and Feng Lin | Reconstruction of Protein-Protein Interaction Pathways by Mining
Subject-Verb-Objects Intermediates | 2nd IAPR Workshop on Pattern Recognition in Bioinformatics (PRIB
2007). 14 pages, 4 figures | Ling, Maurice HT, Lefevre, Christophe, Nicholas, Kevin R, Lin,
Feng. 2007. In J.C. Ragapakse, B. Schmidt, and G. Volkert (Eds.), PRIB 2007.
Lecture Notes in Bioinformatics 4774: 286-299. Springer-Verlag. | null | null | cs.IR cs.CL cs.DL | null | The exponential increase in publication rate of new articles is limiting
access of researchers to relevant literature. This has prompted the use of text
mining tools to extract key biological information. Previous studies have
reported extensive modification of existing generic text processors to process
biological text. However, this requirement for modification had not been
examined. In this study, we have constructed Muscorian, using MontyLingua, a
generic text processor. It uses a two-layered generalization-specialization
paradigm previously proposed where text was generically processed to a suitable
intermediate format before domain-specific data extraction techniques are
applied at the specialization layer. Evaluation using a corpus and experts
indicated 86-90% precision and approximately 30% recall in extracting
protein-protein interactions, which was comparable to previous studies using
either specialized biological text processing tools or modified existing tools.
Our study had also demonstrated the flexibility of the two-layered
generalization-specialization paradigm by using the same generalization layer
for two specialized information extraction tasks.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 01:22:46 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Ling",
"Maurice HT",
""
],
[
"Lefevre",
"Christophe",
""
],
[
"Nicholas",
"Kevin R.",
""
],
[
"Lin",
"Feng",
""
]
] |
0708.0695 | Shunichi Arisawa | I. Iguchi, S. Arisawa, T. Uchiyama, K-S. Yun, T. Hatano and I. Tanaka | Direct observation of quantized interlayer vortex flow and vortex
pinning distribution in high-Tc La_(1.87)Sr_(0.13)CuO_4 single crystals | 16 pages, 4 figures | null | 10.1063/1.2815659 | null | cond-mat.supr-con | null | A scanning superconducting quantum interference device (SQUID) microscope
(SSM) is used to study the magnetic imaging of dynamic motion of quantized
interlayer vortices induced by the Lorentz force in anisotropic high-Tc
La_(1.87)Sr_(0.13)CuO_4 single crystals. It is found that 3 modes of flux
motion switch depending on the transport current. By increasing the current a
transition from the creep-like behavior of vortices to a steady flow of
vortices was observed. Even higher current induced a continuous expansion of
vortex-flow area indicating an inhomogeneous distribution of various pinning
centers.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 01:41:55 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Iguchi",
"I.",
""
],
[
"Arisawa",
"S.",
""
],
[
"Uchiyama",
"T.",
""
],
[
"Yun",
"K-S.",
""
],
[
"Hatano",
"T.",
""
],
[
"Tanaka",
"I.",
""
]
] |
0708.0696 | Xiang-Dong Li | Xiao-Jie Xu and Xiang-Dong Li | Thermal Timescale Mass Transfer Rates in Intermediate-Mass X-ray
Binaries | 13 pages, 4 figures, and 2 tables, accepted for publication in A&A | null | 10.1051/0004-6361:20077637 | null | astro-ph | null | Thermal timescale mass transfer generally occurs in close binaries where the
donor star is more massive than the accreting star. The mass transfer rates are
usually estimated in terms of the Kelvin-Helmholtz timescale of the donor star.
But recent investigations indicate that this method may overestimate the real
mass transfer rates in accreting white dwarf or neutron star binary systems. We
have systematically investigated the thermal-timescale mass transfer processes
in intermediate-mass X-ray binaries, by calculating binary evolution sequences
with various initial donor masses and orbital periods. From the calculated
results we find that on average the mass transfer rates are lower than
traditional estimates by a factor of $\sim 4$.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 02:01:21 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Xu",
"Xiao-Jie",
""
],
[
"Li",
"Xiang-Dong",
""
]
] |
0708.0697 | Nasir Ganikhodjaev | N. N. Ganikhodjaev, M. R. B. Wahiddin, D.V.Zanin | Regularity of some class of nonlinear transformations | 13 pages | null | null | null | math.DS | null | In this paper we consider quadratic stochastic operators designed on finite
Abelian groups. It is proved that such operators have the property of
regularity.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 02:26:48 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Ganikhodjaev",
"N. N.",
""
],
[
"Wahiddin",
"M. R. B.",
""
],
[
"Zanin",
"D. V.",
""
]
] |
0708.0698 | Yoshiaki Tanida | Yoshiaki Tanida, Masakatsu Ito, Hideaki Fujitani | Calculation of absolute free energy of binding for theophylline and its
analogs to RNA aptamer using nonequilibrium work values | 23 pages including 6 figures | null | 10.1016/j.chemphys.2007.07.014 | null | cond-mat.soft | null | The massively parallel computation of absolute binding free energy with a
well-equilibrated system (MP-CAFEE) has been developed [H. Fujitani, Y. Tanida,
M. Ito, G. Jayachandran, C. D. Snow, M. R. Shirts, E. J. Sorin, and V. S.
Pande, J. Chem. Phys. ${\bf 123}$, 084108 (2005)]. As an application, we
perform the binding affinity calculations of six theophylline-related ligands
with RNA aptamer. Basically, our method is applicable when using many compute
nodes to accelerate simulations, thus a parallel computing system is also
developed. To further reduce the computational cost, the adequate non-uniform
intervals of coupling constant $\lambda$, connecting two equilibrium states,
namely bound and unbound, are determined. The absolute binding energies $\Delta
G$ thus obtained have effective linear relation between the computed and
experimental values. If the results of two other different methods are
compared, thermodynamic integration (TI) and molecular mechanics
Poisson-Boltzmann surface area (MM-PBSA) by the paper of Gouda $et al$ [H.
Gouda, I. D. Kuntz, D. A. Case, and P. A. Kollman, Biopolymers ${\bf 68}$, 16
(2003)], the predictive accuracy of the relative values $\Delta\Delta G$ is
almost comparable to that of TI: the correlation coefficients (R) obtained are
0.99 (this work), 0.97 (TI), and 0.78 (MM-PBSA). On absolute binding energies
meanwhile, a constant energy shift of $\sim$ -7 kcal/mol against the
experimental values is evident. To solve this problem, several presumable
reasons are investigated.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 12:52:12 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Tanida",
"Yoshiaki",
""
],
[
"Ito",
"Masakatsu",
""
],
[
"Fujitani",
"Hideaki",
""
]
] |
0708.0699 | Kaspar von Braun | Kaspar von Braun (1), Gerard T. van Belle (1), David Ciardi (1),
Mercedes Lopez-Morales (2), D. W. Hoard (3), Stefanie Wachter (3) ((1)
Michelson Science Center, Caltech (2) Department of Terrestrial Magnetism,
Carnegie Institution of Washington (3) Spitzer Science Center, Caltech) | The Spitzer 24-micron Photometric Light Curve of the Eclipsing M-dwarf
Binary GU Bootis | 7 pages, 3 figures, 2 tables. To appear in the ASP Conference Series
"Cool Stars", editors G. T. van Belle and L. Rebull | null | null | null | astro-ph | null | We present a carefully controlled set of Spitzer 24 \micron MIPS time series
observations of the low mass eclipsing binary star GU Bo\"otis (GU Boo). Our
data cover three secondary eclipses of the system: two consecutive events and
an additional eclipse six weeks later. The study's main purpose is the long
wavelength characterization of GU Boo's light curve, independent of limb
darkening and less sensitive to surface features such as spots. Its analysis
allows for independent verification of the results of optical studies of GU
Boo. Our mid-infrared results show good agreement with previously obtained
system parameters. In addition, the analysis of light curves of other objects
in the field of view serves to characterize the photometric stability and
repeatability of {\it Spitzer's} MIPS-24 at flux densities between
approximately 300--2,000$\mu$Jy. We find that the light curve root mean square
about the median level falls into the 1--4% range for flux densities higher
than 1 mJy.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 03:03:52 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"von Braun",
"Kaspar",
""
],
[
"van Belle",
"Gerard T.",
""
],
[
"Ciardi",
"David",
""
],
[
"Lopez-Morales",
"Mercedes",
""
],
[
"Hoard",
"D. W.",
""
],
[
"Wachter",
"Stefanie",
""
]
] |
0708.0700 | Igor Tanski | Igor A. Tanski | Spectral decomposition approach to macroscopic parameters of
Fokker-Planck flows: Part 2 | Postscript, 10 pages. Changes: removed $a sub 1, a sub 2, a sub 3$
multiplier at (1), (3), (7) and (25) | null | null | null | nlin.CD | null | In this paper we proceed with investigation of connections between Fokker -
Planck equation and continuum mechanics. We base upon expressions from our work
[2], based upon the spectral decomposition of Fokker - Planck equation
solution. In this decomposition we preserve only terms with the smallest
degrees of damping. We find, that macroscopic parameters of Fokker-Planck
flows, obtained in this way, satisfy the set of conservation laws of classic
hydrodynamics. The expression for stresses (30) contains additional term - this
term is negligible in big times limit. We proved also, that the velocities
field alone satisfy Burgers equation without mass forces - but with some
additional term. This term is also negligible in big times limit. For the zero
degree theory, considered in [1], there are no additional terms. But this
theory is valid only for the potential velocities field, fully deductible from
density - the potential is proportional to density logarithm. In this theory we
can not specify initial conditions for velocities independently from density.
Taking in account of the next degree terms could partly solve this problem, but
result in some loss of exactness.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 03:24:28 GMT"
},
{
"version": "v2",
"created": "Mon, 17 Sep 2007 03:44:54 GMT"
}
] | 2007-09-17T00:00:00 | [
[
"Tanski",
"Igor A.",
""
]
] |
0708.0701 | Lars Kecke | Lars Kecke, Tsutomu Momoi, Akira Furusaki | Multi-magnon bound states in the frustrated ferromagnetic 1D chain | 5 pages, 3 figures | Phys. Rev. B 76, 060407(R) (2007) | 10.1103/PhysRevB.76.060407 | null | cond-mat.other | null | We study a one-dimensional Heisenberg chain with competing ferromagnetic
nearest-neighbor and antiferromagnetic next-nearest neighbor interactions in
magnetic field. Starting from the fully polarized high-field state, we
calculate the dispersions of the lowest-lying $n$-magnon excitations and the
saturation field (n=2,3,4). We show that the lowest-lying excitations are
always bound multi-magnon states with a total momentum of $\pi$ except for a
small parameter range. We argue that bose condensation of the bound $n$ magnons
leads to novel Tomonaga-Luttinger liquids with multi-polar correlations;
nematic and triatic ordered liquids correspond to n=2 and n=3.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 03:15:08 GMT"
}
] | 2007-08-27T00:00:00 | [
[
"Kecke",
"Lars",
""
],
[
"Momoi",
"Tsutomu",
""
],
[
"Furusaki",
"Akira",
""
]
] |
0708.0702 | Ryu Sasaki | Ryu Sasaki | Quasi Exactly Solvable Difference Equations | LaTeX with amsfonts, no figure, 17 pages, a few typos corrected, a
reference renewed, 3/2 pages comments on hermiticity added | null | 10.1063/1.2818560 | YITP-07-42 | nlin.SI hep-th math-ph math.MP quant-ph | null | Several explicit examples of quasi exactly solvable `discrete' quantum
mechanical Hamiltonians are derived by deforming the well-known exactly
solvable Hamiltonians of one degree of freedom. These are difference analogues
of the well-known quasi exactly solvable systems, the harmonic oscillator
(with/without the centrifugal potential) deformed by a sextic potential and the
1/sin^2x potential deformed by a cos2x potential. They have a finite number of
exactly calculable eigenvalues and eigenfunctions.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 03:49:35 GMT"
},
{
"version": "v2",
"created": "Thu, 11 Oct 2007 06:04:20 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sasaki",
"Ryu",
""
]
] |
0708.0703 | Yong Chen | Yong Chen, Lianchun Yu, and Shao-Meng Qin | Detection of subthreshold pulses in neurons with channel noise | 14 pages, 9 figures | Physcial Review E 78, 051909 (2008) | 10.1103/PhysRevE.78.051909 | null | q-bio.NC q-bio.SC | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Neurons are subject to various kinds of noise. In addition to synaptic noise,
the stochastic opening and closing of ion channels represents an intrinsic
source of noise that affects the signal processing properties of the neuron. In
this paper, we studied the response of a stochastic Hodgkin-Huxley neuron to
transient input subthreshold pulses. It was found that the average response
time decreases but variance increases as the amplitude of channel noise
increases. In the case of single pulse detection, we show that channel noise
enables one neuron to detect the subthreshold signals and an optimal membrane
area (or channel noise intensity) exists for a single neuron to achieve optimal
performance. However, the detection ability of a single neuron is limited by
large errors. Here, we test a simple neuronal network that can enhance the
pulse detecting abilities of neurons and find dozens of neurons can perfectly
detect subthreshold pulses. The phenomenon of intrinsic stochastic resonance is
also found both at the level of single neurons and at the level of networks. At
the network level, the detection ability of networks can be optimized for the
number of neurons comprising the network.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 05:15:44 GMT"
},
{
"version": "v2",
"created": "Fri, 14 Nov 2008 00:25:11 GMT"
}
] | 2008-11-14T00:00:00 | [
[
"Chen",
"Yong",
""
],
[
"Yu",
"Lianchun",
""
],
[
"Qin",
"Shao-Meng",
""
]
] |
0708.0704 | Hossein Hajiabolhassan | Hossein Hajiabolhassan | On Colorings of Graph Powers | null | null | null | null | math.CO | null | In this paper, some results concerning the colorings of graph powers are
presented. The notion of helical graphs is introduced. We show that such graphs
are hom-universal with respect to high odd-girth graphs whose $(2t+1)$st power
is bounded by a Kneser graph. Also, we consider the problem of existence of
homomorphism to odd cycles. We prove that such homomorphism to a $(2k+1)$-cycle
exists if and only if the chromatic number of the $(2k+1)$st power of $S_2(G)$
is less than or equal to 3, where $S_2(G)$ is the 2-subdivision of $G$. We also
consider Ne\v{s}et\v{r}il's Pentagon problem. This problem is about the
existence of high girth cubic graphs which are not homomorphic to the cycle of
size five. Several problems which are closely related to Ne\v{s}et\v{r}il's
problem are introduced and their relations are presented.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 18:51:44 GMT"
},
{
"version": "v2",
"created": "Tue, 7 Aug 2007 10:04:48 GMT"
},
{
"version": "v3",
"created": "Wed, 8 Aug 2007 08:23:33 GMT"
},
{
"version": "v4",
"created": "Thu, 23 Aug 2007 18:58:08 GMT"
},
{
"version": "v5",
"created": "Fri, 28 Mar 2008 21:19:05 GMT"
}
] | 2008-03-31T00:00:00 | [
[
"Hajiabolhassan",
"Hossein",
""
]
] |
0708.0705 | Taichiro Takagi | Taichiro Takagi | Creation of ballot sequences in a periodic cellular automaton | 31 pages. Section 1 changed and section 5 added | J. Phys. Soc. Jpn. 78 (2009) 024003 | 10.1143/JPSJ.78.024003 | null | nlin.SI math.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by an attempt to develop a method for solving initial value
problems in a class of one dimensional periodic cellular automata (CA)
associated with crystal bases and soliton equations, we consider a
generalization of a simple proposition in elementary mathematics. The original
proposition says that any sequence of letters 1 and 2, having no less 1's than
2's, can be changed into a ballot sequence via cyclic shifts only. We
generalize it to treat sequences of cells of common capacity s > 1, each of
them containing consecutive 2's (left) and 1's (right), and show that these
sequences can be changed into a ballot sequence via two manipulations, cyclic
and "quasi-cyclic" shifts. The latter is a new CA rule and we find that various
kink-like structures are traveling along the system like particles under the
time evolution of this rule.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 07:31:38 GMT"
},
{
"version": "v2",
"created": "Mon, 13 Aug 2007 14:06:31 GMT"
},
{
"version": "v3",
"created": "Tue, 28 Aug 2007 07:10:50 GMT"
},
{
"version": "v4",
"created": "Tue, 10 Feb 2009 03:01:14 GMT"
}
] | 2009-02-10T00:00:00 | [
[
"Takagi",
"Taichiro",
""
]
] |
0708.0706 | Hou Ian | H. Ian, Z. R. Gong, C. P. Sun | Noise Suppression for Micromechanical Resonator via Intrinsic Dynamic
Feedback | 11 pages, 7 figures | Front. Phys. China 3, 294 (2008) | 10.1007/s11467-008-0025-z | null | cond-mat.mes-hall quant-ph | null | We study a dynamic mechanism to passively suppress the thermal noise of a
micromechanical resonator through an intrinsic self-feedback that is genuinely
non-Markovian. We use two coupled resonators, one as the target resonator and
the other as an ancillary resonator, to illustrate the mechanism and its noise
reduction effect. The intrinsic feedback is realized through the dynamics of
coupling between the two resonators: the motions of the target resonator and
the ancillary resonator mutually influence each other in a cyclic fashion.
Specifically, the states that the target resonator has attained earlier will
affect the state it attains later due to the presence of the ancillary
resonator. We show that the feedback mechanism will bring forth the effect of
noise suppression in the spectrum of displacement, but not in the spectrum of
momentum.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 06:19:22 GMT"
},
{
"version": "v2",
"created": "Mon, 5 Nov 2007 10:04:51 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ian",
"H.",
""
],
[
"Gong",
"Z. R.",
""
],
[
"Sun",
"C. P.",
""
]
] |
0708.0707 | Pulak Ranjan Giri | Pulak Ranjan Giri | Hidden scale in quantum mechanics | 4 pages, 5 figures | Mod.Phys.Lett.A24:2203-2211,2009 | 10.1142/S0217732309030102 | SINP/TNP/2007/19 | hep-th quant-ph | null | We show that the intriguing localization of a free particle wave-packet is
possible due to a hidden scale present in the system. Self-adjoint extensions
(SAE) is responsible for introducing this scale in quantum mechanical models
through the nontrivial boundary conditions. We discuss a couple of classically
scale invariant free particle systems to illustrate the issue. In this context
it has been shown that a free quantum particle moving on a full line may have
localized wave-packet around the origin. As a generalization, it has also been
shown that particles moving on a portion of a plane or on a portion of a three
dimensional space can have unusual localized wave-packet.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 06:22:14 GMT"
}
] | 2010-11-15T00:00:00 | [
[
"Giri",
"Pulak Ranjan",
""
]
] |
0708.0708 | Chul-Moon Yoo | Chul-Moon Yoo, Hideki Ishihara, Masashi Kimura, Ken Matsuno and Shinya
Tomizawa | Horizons of Coalescing Black Holes on Eguchi-Hanson Space | 20 pages, 11 figures CQG accepted version | Class.Quant.Grav.25:095017,2008 | 10.1088/0264-9381/25/9/095017 | OCU-PHYS-272, AP-GR-46,YITP-08-09 | gr-qc hep-th | null | Using the numerical method, we study dynamics of coalescing black holes on
the Eguchi-Hanson base space. Effects of a difference in spacetime topology on
the black hole dynamics is discussed. We analyze appearance and disappearance
process of marginal surfaces. In our calculation, the area of a coverall black
hole horizon at the creation time in the coalescing black holes solutions on
Eguchi-Hanson space is larger than that in the five-dimensional Kastor-Traschen
solutions. This fact suggests that the black hole production on the
Eguchi-Hanson space is easier than that on the flat space.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 06:37:33 GMT"
},
{
"version": "v2",
"created": "Wed, 9 Apr 2008 07:34:18 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Yoo",
"Chul-Moon",
""
],
[
"Ishihara",
"Hideki",
""
],
[
"Kimura",
"Masashi",
""
],
[
"Matsuno",
"Ken",
""
],
[
"Tomizawa",
"Shinya",
""
]
] |
0708.0709 | Valerio Scarani | Valerio Scarani, Renato Renner | Quantum cryptography with finite resources: unconditional security bound
for discrete-variable protocols with one-way post-processing | null | Phys. Rev. Lett. 100, 200501 (2008) | 10.1103/PhysRevLett.100.200501 | null | quant-ph | null | We derive a bound for the security of QKD with finite resources under one-way
post-processing, based on a definition of security that is composable and has
an operational meaning. While our proof relies on the assumption of collective
attacks, unconditional security follows immediately for standard protocols like
Bennett-Brassard 1984 and six-states. For single-qubit implementations of such
protocols, we find that the secret key rate becomes positive when at least
N\sim 10^5 signals are exchanged and processed. For any other discrete-variable
protocol, unconditional security can be obtained using the exponential de
Finetti theorem, but the additional overhead leads to very pessimistic
estimates.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 07:33:13 GMT"
},
{
"version": "v2",
"created": "Sun, 1 Jun 2008 02:23:31 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Scarani",
"Valerio",
""
],
[
"Renner",
"Renato",
""
]
] |
0708.0710 | Roberto De Renzi | S. Sanna, F. Coneri, A. Rigoldi, G. Concas and R. De Renzi | Evidence of two distinct charge carriers in underdoped high Tc cuprates | 4 pages, 4 figures | null | 10.1103/PhysRevB.77.224511 | null | cond-mat.str-el cond-mat.supr-con | null | We present results on heavily underdoped Y_1-xCa_xBa_2Cu_3O_6+y which provide
the evidence that the doping mechanism (cation substitution or oxygen loading)
directly determines whether the corresponding injected mobile holes contribute
to superconductivity or only to the normal metallic properties. We argue that
this hole tagging calls for a subtler description of the correlated bands than
the usual one. We also map in great detail the underdoped superconducting phase
diagram T_c vs. hole doping which shows that the number of mobile holes is not
the critical parameter for the superconductivity.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 17:03:06 GMT"
},
{
"version": "v2",
"created": "Fri, 26 Oct 2007 11:11:38 GMT"
}
] | 2013-05-29T00:00:00 | [
[
"Sanna",
"S.",
""
],
[
"Coneri",
"F.",
""
],
[
"Rigoldi",
"A.",
""
],
[
"Concas",
"G.",
""
],
[
"De Renzi",
"R.",
""
]
] |
0708.0711 | C. P. Robert | R. Douc, A. Guillin, J.-M. Marin, C. P. Robert | Convergence of adaptive mixtures of importance sampling schemes | Published at http://dx.doi.org/10.1214/009053606000001154 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, 420-448 | 10.1214/009053606000001154 | IMS-AOS-AOS0211 | math.ST stat.CO stat.TH | null | In the design of efficient simulation algorithms, one is often beset with a
poor choice of proposal distributions. Although the performance of a given
simulation kernel can clarify a posteriori how adequate this kernel is for the
problem at hand, a permanent on-line modification of kernels causes concerns
about the validity of the resulting algorithm. While the issue is most often
intractable for MCMC algorithms, the equivalent version for importance sampling
algorithms can be validated quite precisely. We derive sufficient convergence
conditions for adaptive mixtures of population Monte Carlo algorithms and show
that Rao--Blackwellized versions asymptotically achieve an optimum in terms of
a Kullback divergence criterion, while more rudimentary versions do not benefit
from repeated updating.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 07:39:35 GMT"
}
] | 2010-10-11T00:00:00 | [
[
"Douc",
"R.",
""
],
[
"Guillin",
"A.",
""
],
[
"Marin",
"J. -M.",
""
],
[
"Robert",
"C. P.",
""
]
] |
0708.0712 | Stephanie Gerbaud | St\'ephanie Gerbaud (IRISA), Nicolas Mollet (IRISA), Bruno Arnaldi
(IRISA) | Virtual Environments for Training: From Individual Learning to
Collaboration with Humanoids | null | Dans Edutainment (2007) | null | null | cs.GR | null | The next generation of virtual environments for training is oriented towards
collaborative aspects. Therefore, we have decided to enhance our platform for
virtual training environments, adding collaboration opportunities and
integrating humanoids. In this paper we put forward a model of humanoid that
suits both virtual humans and representations of real users, according to
collaborative training activities. We suggest adaptations to the scenario model
of our platform making it possible to write collaborative procedures. We
introduce a mechanism of action selection made up of a global repartition and
an individual choice. These models are currently being integrated and validated
in GVT, a virtual training tool for maintenance of military equipments,
developed in collaboration with the French company NEXTER-Group.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 07:42:56 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Gerbaud",
"Stéphanie",
"",
"IRISA"
],
[
"Mollet",
"Nicolas",
"",
"IRISA"
],
[
"Arnaldi",
"Bruno",
"",
"IRISA"
]
] |
0708.0713 | Radu Grigore | Radu Grigore and Micha{\l} Moskal | Edit and verify | null | null | null | null | cs.LO | null | Automated theorem provers are used in extended static checking, where they
are the performance bottleneck. Extended static checkers are run typically
after incremental changes to the code. We propose to exploit this usage pattern
to improve performance. We present two approaches of how to do so and a full
solution.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 07:47:34 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Grigore",
"Radu",
""
],
[
"Moskal",
"Michał",
""
]
] |
0708.0714 | Neil Saunders | Neil Saunders | A Strict Inequality for a Minimal Degree of a Direct Product | 8 pages | null | null | null | math.GR | null | The minimal faithful permutation degree of a finite group G is the least
non-negative integer n such that G embeds in the symmetric group Sym(n). Work
of Johnson and Wright established conditions for when the minimal degree of a
direct product equals the sum of the minimal degrees for two finite groups.
Wright asked whether this is true for all finite groups. A counter- example of
degree 15 was provided by the referee and was added as an addendum in a paper
of Wright. Here we provide a counter-example of degree 12.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 07:50:53 GMT"
},
{
"version": "v2",
"created": "Tue, 7 Aug 2007 09:23:29 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Saunders",
"Neil",
""
]
] |
0708.0715 | Samuel S. Wu | Samuel S. Wu, Weizhen Wang | Step-up simultaneous tests for identifying active effects in orthogonal
saturated designs | Published at http://dx.doi.org/10.1214/009053606000001136 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, 449-463 | 10.1214/009053606000001136 | IMS-AOS-AOS0209 | math.ST stat.TH | null | A sequence of null hypotheses regarding the number of negligible effects
(zero effects) in orthogonal saturated designs is formulated. Two step-up
simultaneous testing procedures are proposed to identify active effects
(nonzero effects) under the commonly used assumption of effect sparsity. It is
shown that each procedure controls the experimentwise error rate at a given
$\alpha$ level in the strong sense.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 07:51:34 GMT"
}
] | 2009-09-29T00:00:00 | [
[
"Wu",
"Samuel S.",
""
],
[
"Wang",
"Weizhen",
""
]
] |
0708.0716 | Ryu Sasaki | Satoru Odake and Ryu Sasaki | Multi-Particle Quasi Exactly Solvable Difference Equations | LaTeX with amsfonts, amssymb, amsmath, no figure, 12 pages | J.Math.Phys.48:122105,2007 | 10.1063/1.2818561 | DPSU-07-3, YITP-07-44 | nlin.SI hep-th math-ph math.MP quant-ph | null | Several explicit examples of multi-particle quasi exactly solvable `discrete'
quantum mechanical Hamiltonians are derived by deforming the well-known exactly
solvable multi-particle Hamiltonians, the Ruijsenaars-Schneider-van Diejen
systems. These are difference analogues of the quasi exactly solvable
multi-particle systems, the quantum Inozemtsev systems obtained by deforming
the well-known exactly solvable Calogero-Sutherland systems. They have a finite
number of exactly calculable eigenvalues and eigenfunctions. This paper is a
multi-particle extension of the recent paper by one of the authors on deriving
quasi exactly solvable difference equations of single degree of freedom.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 07:55:46 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Odake",
"Satoru",
""
],
[
"Sasaki",
"Ryu",
""
]
] |
0708.0717 | Eric Abel | E.T. Abel, K. Matan, F.C. Chou, E.D. Isaacs, D.E. Moncton, H. Sinn, A.
Alatas, Y.S. Lee | X-ray Scattering Study of the spin-Peierls transition and soft phonon
behavior in TiOCl | 14 pages, 14 figures | null | 10.1103/PhysRevB.76.214304 | null | cond-mat.str-el | null | We have studied the S=1/2 quasi-one-dimensional antiferromagnet TiOCl using
single crystal x-ray diffraction and inelastic x-ray scattering techniques. The
Ti ions form staggered spin chains which dimerize below Tc1 = 66 K and have an
incommensurate lattice distortion between Tc1 and Tc2 = 92 K. Based on our
measurements of the intensities, wave vectors, and harmonics of the
incommensurate superlattice peaks, we construct a model for the incommensurate
modulation. The results are in good agreement with a soliton lattice model,
though some quantitative discrepancies exist near Tc2. The behavior of the
phonons has been studied using inelastic x-ray scattering with ~2 meV energy
resolution. For the first time, a zone boundary phonon which softens at the
spin-Peierls temperature Tsp has been observed. Our results show reasonably
good quantitative agreement with the Cross-Fisher theory for the phonon
dynamics at wave vectors near the zone boundary and temperatures near Tsp.
However, not all aspects of the data can be described, such as the strong
overdamping of the soft mode above Tsp. Overall, our results show that TiOCl is
a good realization of a spin-Peierls system, where the phonon softening allows
us to identify the transition temperature as Tsp=Tc2=92 K
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 08:00:04 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Abel",
"E. T.",
""
],
[
"Matan",
"K.",
""
],
[
"Chou",
"F. C.",
""
],
[
"Isaacs",
"E. D.",
""
],
[
"Moncton",
"D. E.",
""
],
[
"Sinn",
"H.",
""
],
[
"Alatas",
"A.",
""
],
[
"Lee",
"Y. S.",
""
]
] |
0708.0718 | Junya Otsuki | J. Otsuki, H. Kusunose, P. Werner and Y. Kuramoto | Continuous-Time Quantum Monte Carlo Method for the Coqblin-Schrieffer
Model | 12 pages, 15 figures | J. Phys. Soc. Jpn. 76 (2007) 114707 | 10.1143/JPSJ.76.114707 | null | cond-mat.str-el | null | An impurity solver based on a continuous-time quantum Monte Carlo method is
developed for the Coqblin-Schrieffer model. The Monte Carlo simulation does not
encounter a sign problem for antiferromagnetic interactions, and accurately
reproduces the Kondo effect. Our algorithm can deal with an arbitrary number N
of local degrees of freedom, becomes more efficient for larger values of N, and
is hence suitable for models with orbital degeneracy. The dynamical
susceptibility and the impurity t-matrix are derived with the aid of the Pad\'e
approximation for various values of N, and good agreement is found with other
methods and available exact results. We point out that the Korringa-Shiba
relation needs correction for a finite value of the exchange interaction.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 08:05:35 GMT"
},
{
"version": "v2",
"created": "Tue, 7 Aug 2007 02:39:41 GMT"
}
] | 2007-10-25T00:00:00 | [
[
"Otsuki",
"J.",
""
],
[
"Kusunose",
"H.",
""
],
[
"Werner",
"P.",
""
],
[
"Kuramoto",
"Y.",
""
]
] |
0708.0719 | Luis Fernando Mello | Jorge Sotomayor, Luis Fernando Mello, Danilo Braun Santos, Denis de
Carvalho Braga | Hopf Bifurcation in a Model for Biological Control | 23 pages, 3 figures | null | null | null | math.DS math.CA | null | In this paper we study the Lyapunov stability and Hopf bifurcation in a
biological system which models the biological control of parasites of orange
plantations.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 08:21:24 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Sotomayor",
"Jorge",
""
],
[
"Mello",
"Luis Fernando",
""
],
[
"Santos",
"Danilo Braun",
""
],
[
"Braga",
"Denis de Carvalho",
""
]
] |
0708.0720 | Jose M. Isidro | J.M. Isidro | Quantum mechanics as a spontaneously broken gauge theory on a U(1) gerbe | null | Int.J.Geom.Meth.Mod.Phys.05:233-252,2008 | 10.1142/S0219887808002722 | null | math-ph hep-th math.MP quant-ph | null | Any quantum-mechanical system possesses a U(1) gerbe naturally defined on
configuration space. Acting on Feynman's kernel exp(iS/h), this U(1) symmetry
allows one to arbitrarily pick the origin for the classical action S, on a
point-by-point basis on configuration space. This is equivalent to the
statement that quantum mechanics is a U(1) gauge theory. Unlike Yang-Mills
theories, however, the geometry of this gauge symmetry is not given by a fibre
bundle, but rather by a gerbe. Since this gauge symmetry is spontaneously
broken, an analogue of the Higgs mechanism must be present. We prove that a
Heisenberg-like noncommutativity for the space coordinates is responsible for
the breaking. This allows to interpret the noncommutativity of space
coordinates as a Higgs mechanism on the quantum-mechanical U(1) gerbe.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 08:18:19 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Isidro",
"J. M.",
""
]
] |
0708.0721 | Antonio Sollima | A. Sollima, F. R. Ferraro, M. Bellazzini | The Mass Function of omega Centauri down to 0.15 M_s | 9 pages, 10 figures, accepted for publication by MNRAS | null | 10.1111/j.1365-2966.2007.12324.x | null | astro-ph | null | By means of deep FORS1@VLT and ACS@HST observations of a wide area in the
stellar system omega Cen we measured the luminosity function of main sequence
stars down to R=22.6 and I_{F814W}=24.5 . The luminosity functions obtained
have been converted into mass functions and compared with analytical Initial
Mass Functions (IMFs) available in the literature. The mass function obtained,
reaching M~0.15 M_s, can be well reproduced by a broken power-law with indices
alpha=-2.3 for M>0.5 M_s and alpha=-0.8 for M<0.5 M_s. Since the stellar
populations of omega Cen have been proved to be actually unaffected by
dynamical evolution processes, the mass function measured in this stellar
system should represent the best approximation of the IMF of a star cluster.
The comparison with the MF measured in other Galactic globular clusters
suggests that possible primordial differences in the slope of the low-mass end
of their MF could exist.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 08:50:37 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sollima",
"A.",
""
],
[
"Ferraro",
"F. R.",
""
],
[
"Bellazzini",
"M.",
""
]
] |
0708.0722 | John Gough | John Gough | Filtering of Wide Sense Stationary Quantum Stochastic Processes | 6 pages, no figures | Doklady. Math., 70, N0. 1, 664-7, 2004 | null | null | math-ph math.MP | null | We introduce a concept of a quantum wide sense stationary process taking
values in a C*-algebra and expected in a sub-algebra. The power spectrum of
such a process is defined, in analogy to classical theory, as a positive
measure on frequency space taking values in the expected algebra. The notion of
linear quantum filters is introduced as some simple examples mentioned.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 08:45:35 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Gough",
"John",
""
]
] |
0708.0723 | Salvatore Capozziello | S. Capozziello, A. Stabile, A. Troisi | The Newtonian Limit of F(R) gravity | 16 pages | Phys.Rev.D76:104019,2007 | 10.1103/PhysRevD.76.104019 | null | gr-qc astro-ph | null | A general analytic procedure is developed to deal with the Newtonian limit of
$f(R)$ gravity. A discussion comparing the Newtonian and the post-Newtonian
limit of these models is proposed in order to point out the differences between
the two approaches. We calculate the post-Newtonian parameters of such theories
without any redefinition of the degrees of freedom, in particular, without
adopting some scalar fields and without any change from Jordan to Einstein
frame. Considering the Taylor expansion of a generic $f(R)$ theory, it is
possible to obtain general solutions in term of the metric coefficients up to
the third order of approximation. In particular, the solution relative to the
$g_{tt}$ component gives a gravitational potential always corrected with
respect to the Newtonian one of the linear theory $f(R)=R$. Furthermore, we
show that the Birkhoff theorem is not a general result for $f(R)$-gravity since
time-dependent evolution for spherically symmetric solutions can be achieved
depending on the order of perturbations. Finally, we discuss the
post-Minkowskian limit and the emergence of massive gravitational wave
solutions.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 08:46:02 GMT"
},
{
"version": "v2",
"created": "Wed, 29 Aug 2007 08:22:24 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Capozziello",
"S.",
""
],
[
"Stabile",
"A.",
""
],
[
"Troisi",
"A.",
""
]
] |
0708.0724 | Kelly Patton | Kelly R. Patton | Current-Noise Spectroscopy with a Scanning Tunneling Microscope | This paper has been withdrawn | null | null | null | cond-mat.str-el | null | This paper has been withdrawn due to fundamental errors.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 08:47:38 GMT"
},
{
"version": "v2",
"created": "Thu, 9 Aug 2007 11:19:49 GMT"
},
{
"version": "v3",
"created": "Thu, 20 Mar 2008 12:23:01 GMT"
}
] | 2008-03-20T00:00:00 | [
[
"Patton",
"Kelly R.",
""
]
] |
0708.0725 | David Sing | D. K. Sing, E. M. Green, S. B. Howell, J. B. Holberg, M.
Lopez-Morales, J. S. Shaw, G. D. Schmidt | Discovery of a bright eclipsing cataclysmic variable | 10 pages, 13 figure, accepted for publication in A&A | null | 10.1051/0004-6361:20078026 | null | astro-ph | null | We report on the discovery of J0644+3344, a bright deeply eclipsing
cataclysmic variable (CV) binary. Spectral signatures of both binary components
and an accretion disk can be seen at optical wavelengths. The optical spectrum
shows broad H I, He I, and He II accretion disk emission lines with deep narrow
absorption components from H I, He I, Mg II and Ca II. The absorption lines are
seen throughout the orbital period, disappearing only during primary eclipse.
These absorption lines are either the the result of an optically-thick inner
accretion disk or from the photosphere of the primary star. Radial velocity
measurements show that the H I, He I, and Mg II absorption lines phase with the
the primary star, while weak absorption features in the continuum phase with
the secondary star. Radial velocity solutions give a 150+/-4 km/s
semi-amplitude for the primary star and 192.8+/-5.6 km/s for the secondary. The
individual stellar masses are 0.63-0.69 Mdot for the primary and 0.49-0.54 Mdot
for the secondary. The bright eclipsing nature of this binary has helped
provide masses for both components with an accuracy rarely achieved for CVs.
This binary most closely resembles a nova-like UX UMa or SW Sex type of CV.
J0644+3344, however, has a longer orbital period than most UX UMa or SW Sex
stars. Assuming an evolution toward shorter orbital periods, J0644+3344 is
therefore likely to be a young interacting binary. The secondary star is
consistent with the size and spectral type of a K8 star, but has an M0 mass.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 08:48:14 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sing",
"D. K.",
""
],
[
"Green",
"E. M.",
""
],
[
"Howell",
"S. B.",
""
],
[
"Holberg",
"J. B.",
""
],
[
"Lopez-Morales",
"M.",
""
],
[
"Shaw",
"J. S.",
""
],
[
"Schmidt",
"G. D.",
""
]
] |
0708.0726 | Guy Baruch | Guy Baruch (1) Gadi Fibich (1), Semyon V. Tsynkov (2) ((1) Tel Aviv
University, (2) North Carolina State University) | High-order numerical method for the nonlinear Helmholtz equation with
material discontinuities in one space dimension | 47 pages, 8 figures | Journal of Computational Physics, 227 1 (Nov. 2007) pp. 820-850 | 10.1016/j.jcp.2007.08.022 | null | math-ph math.MP | null | The nonlinear Helmholtz equation (NLH) models the propagation of
electromagnetic waves in Kerr media, and describes a range of important
phenomena in nonlinear optics and in other areas. In our previous work, we
developed a fourth order method for its numerical solution that involved an
iterative solver based on freezing the nonlinearity. The method enabled a
direct simulation of nonlinear self-focusing in the nonparaxial regime, and a
quantitative prediction of backscattering. However, our simulations showed that
there is a threshold value for the magnitude of the nonlinearity, above which
the iterations diverge. In this study, we numerically solve the one-dimensional
NLH using a Newton-type nonlinear solver. Because the Kerr nonlinearity
contains absolute values of the field, the NLH has to be recast as a system of
two real equations in order to apply Newton's method. Our numerical simulations
show that Newton's method converges rapidly and, in contradistinction with the
iterations based on freezing the nonlinearity, enables computations for very
high levels of nonlinearity. In addition, we introduce a novel compact
finite-volume fourth order discretization for the NLH with material
discontinuities.The one-dimensional results of the current paper create a
foundation for the analysis of multi-dimensional problems in the future.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 09:09:39 GMT"
},
{
"version": "v2",
"created": "Sun, 16 Sep 2007 14:36:26 GMT"
}
] | 2009-02-15T00:00:00 | [
[
"Baruch",
"Guy",
""
],
[
"Fibich",
"Gadi",
""
],
[
"Tsynkov",
"Semyon V.",
""
]
] |
0708.0727 | Stavros Papadakis | Stavros Argyrios Papadakis | Some calculations on type II_1 unprojection | 30 pages | null | null | null | math.AG math.AC | null | The type II_1 unprojection is, by definition, the generic complete
intersection type II unprojection, in the sense of [Papadakis, Type II
unprojection, J. Algebraic Geometry, 15 (2006) 399--414] Section 3.1, for the
parameter value k = 1, and depends on a parameter n greater or equal than 2.
Our main results are the explicit calculation of the linear relations of the
type II_1 unprojection for any value of n greater or equal than 2 (Theorem
3.16) and the explicit calculation of the quadratic equation for the case n = 3
(Theorem 4.1). In addition, Section 5 contains applications to algebraic
geometry while Section 6 contains the Macaulay 2 code for the type II_1
unprojection for the parameter value n = 3.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 09:14:14 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Papadakis",
"Stavros Argyrios",
""
]
] |
0708.0728 | Olaf Lenz | V. Ballenegger and J.J. Cerda and Ch. Holm and O. Lenz | The optimal P3M algorithm for computing electrostatic energies in
periodic systems | 31 pages, 3 figures | J. Chem. Phys. 128, 034109 (2008) | 10.1063/1.2816570 | null | physics.comp-ph | null | We optimize Hockney and Eastwood's Particle-Particle Particle-Mesh (P3M)
algorithm to achieve maximal accuracy in the electrostatic energies (instead of
forces) in 3D periodic charged systems. To this end we construct an optimal
influence function that minimizes the RMS errors in the energies. As a
by-product we derive a new real-space cut-off correction term, give a
transparent derivation of the systematic errors in terms of Madelung energies,
and provide an accurate analytical estimate for the RMS error of the energies.
This error estimate is a useful indicator of the accuracy of the computed
energies, and allows an easy and precise determination of the optimal values of
the various parameters in the algorithm (Ewald splitting parameter, mesh size
and charge assignment order).
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 09:24:26 GMT"
}
] | 2010-12-08T00:00:00 | [
[
"Ballenegger",
"V.",
""
],
[
"Cerda",
"J. J.",
""
],
[
"Holm",
"Ch.",
""
],
[
"Lenz",
"O.",
""
]
] |
0708.0729 | Hrvoje Nikolic | H. Nikolic | Black-hole information puzzle: A generic string-inspired approach | 8 pages, revised, title changed, to appear in Eur. Phys. J. C | Eur.Phys.J.C54:319-323,2008 | 10.1140/epjc/s10052-008-0529-2 | null | hep-th gr-qc | null | Given the insight steming from string theory, the origin of the black-hole
(BH) information puzzle is traced back to the assumption that it is physically
meaningful to trace out the density matrix over negative-frequency Hawking
particles. Instead, treating them as virtual particles necessarily absorbed by
the BH in a manner consistent with the laws of BH thermodynamics, and tracing
out the density matrix only over physical BH states, the complete evaporation
becomes compatible with unitarity.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 09:26:54 GMT"
},
{
"version": "v2",
"created": "Mon, 20 Aug 2007 11:16:15 GMT"
},
{
"version": "v3",
"created": "Tue, 8 Jan 2008 10:44:26 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Nikolic",
"H.",
""
]
] |
0708.0730 | Christian Schwinn | Christian Schwinn (RWTH Aachen) | Effective Theory Approach to W-Pair Production near Threshold | 7 pages (ilcws07.cls included), to appear in the proceedings of the
International Linear Collider Workshop (LCWS/ILC07), 30 May - 3 Jun 2007,
Hamburg, Germany | ECONF C0705302:LOOP03,2007 | null | SFB/CPP-07-44 | hep-ph | null | In this talk, I review the effective theory approach to unstable particle
production and present results of a calculation of the process e- e+ ->mu-
nubar_mu u dbar X near the W-pair production threshold up to next-to-leading
order in GammaW/MW ~ alpha ~ v^2. The remaining theoretical uncertainty and the
impact on the measurement of the W mass is discussed.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 09:33:20 GMT"
}
] | 2009-02-16T00:00:00 | [
[
"Schwinn",
"Christian",
"",
"RWTH Aachen"
]
] |
0708.0731 | Young-Chung Hsue | Young-Chung Hsue | Finding irreducible representation of symmetry operators linearly | null | null | null | NSC 95-2745-M-006-004- | math-ph math.MP | null | The main purpose of this paper is providing a simple method to generate the
matrices of irreducible representations because it is useful to reduce the
computational time of solving the eigenvalue problems. The only information we
need to provide for this method is the group-multiplication table, and the
proof of validity of this method is also shown in this paper.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 09:34:20 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Hsue",
"Young-Chung",
""
]
] |
0708.0732 | Cheikh Ndiaye birahim | Cheikh Birahim Ndiaye | Constant T-curvature conformal metrics on 4-manifolds with boundary | null | null | null | null | math.AP math.DG | null | In this paper we prove that, given a compact four dimensional smooth
Riemannian manifold (M,g) with smooth boundary there exists a metric conformal
to g with constant T-curvature, zero Q-curvature and zero mean curvature under
generic and conformally invariant assumptions. The problem amounts to solving a
fourth order nonlinear elliptic boundary value problem (BVP) with boundary
conditions given by a third-order pseudodifferential operator, and homogeneous
Neumann one. It has a variational structure, but since the corresponding
Euler-Lagrange functional is in general unbounded from below, we look for
saddle points. In order to do this, we use topological arguments and min-max
methods combined with a compactness result for the corresponding BVP.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 09:44:10 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Ndiaye",
"Cheikh Birahim",
""
]
] |
0708.0733 | Hiroshi Kaji | The Belle Collaboration: K. Abe, et al | Precise measurement of hadronic $\tau$-decays in modes with $\eta$
mesons | BELLE-CONF-0714; contributed to EPS 2007 and Lepton Photon 2007 | null | null | null | hep-ex | null | We have measured branching fractions of hadronic $\tau$ decays involving an
$\eta$ meson using 485 fb^{-1} of data collected with the Belle detector at the
KEKB asymmetric-energy e^+e^- collider. We obtain the following branching
fractions: ${\cal B}(\tau^-\to K^- \eta \nu_{\tau})=(1.62\pm 0.05 \pm
0.09)\times 10^{-4}$, ${\cal B}(\tau^-\to K^- \pi^0 \eta \nu_{\tau}) =(4.7\pm
1.1 \pm 0.4)\times 10^{-5}$, ${\cal B}(\tau^-\to \pi^- \pi^0 \eta
\nu_{\tau})=(1.39 \pm 0.03 \pm 0.07) \times 10^{-3}$, and ${\cal B}(\tau^-\to
K^{*-} \eta \nu_{\tau})=(1.13\pm 0.19 \pm 0.07)\times 10^{-4}$ improving the
accuracy compared to the best previous measurements by factors of six, eight,
four and four, respectively.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 09:54:13 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"The Belle Collaboration",
"",
""
],
[
"Abe",
"K.",
""
]
] |
0708.0734 | Ion I. Cot{\ba}escu | Ion I. Cotaescu | The Schr\" odinger picture of the Dirac quantum mechanics on spatially
flat Robertson-Walker backgrounds | 6 pages 0 figures | null | 10.1142/S0217732307026035 | null | gr-qc math-ph math.MP quant-ph | null | The Schr\" odinger picture of the Dirac quantum mechanics is defined in
charts with spatially flat Robertson-Walker metrics and Cartesian coordinates.
The main observables of this picture are identified, including the interacting
part of the Hamiltonian operator produced by the minimal coupling with the
gravitational field. It is shown that in this approach new Dirac quantum modes
on de Sitter spacetimes may be found analytically solving the Dirac equation.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 10:00:25 GMT"
}
] | 2014-10-07T00:00:00 | [
[
"Cotaescu",
"Ion I.",
""
]
] |
0708.0735 | Michaela Kraus | Michaela Kraus, Jiri Kubat, Jiri Krticka | Wind emission of OB supergiants and the influence of clumping | 3 pages, to appear in the workshop proceedings 'Clumping in Hot Star
Winds', eds. W.-R. Hamann, A. Feldmeier, & L. Oskinova | null | null | null | astro-ph | null | The influence of the wind to the total continuum of OB supergiants is
discussed. For wind velocity distributions with \beta > 1.0, the wind can have
strong influence to the total continuum emission, even at optical wavelengths.
Comparing the continuum emission of clumped and unclumped winds, especially for
stars with high \beta values, delivers flux differences of up to 30% with
maximum in the near-IR. Continuum observations at these wavelengths are
therefore an ideal tool to discriminate between clumped and unclumped winds of
OB supergiants.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 10:09:13 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Kraus",
"Michaela",
""
],
[
"Kubat",
"Jiri",
""
],
[
"Krticka",
"Jiri",
""
]
] |
0708.0736 | Phil Williams | Phillip Y. Williams | Overview document for: A weight function theory of basis function
interpolants and smoothers | Version 1: 9 pages, 0 figures, 1 bbl file. Version 2: Updated to
describe consolidated version 2 documents - now only two documents | null | null | null | math.NA | null | This document is a brief overview of two documents which continue to develop
the weight function theory of basis function smoothers and interpolants. One
document considers the zero order theory and one considers the positive order
theory.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 10:13:21 GMT"
},
{
"version": "v2",
"created": "Mon, 22 Oct 2007 11:30:42 GMT"
}
] | 2007-10-22T00:00:00 | [
[
"Williams",
"Phillip Y.",
""
]
] |
0708.0737 | Sergiy Maksymenko | Sergiy Maksymenko | $\infty$-jets of difeomorphisms preserving orbits of vector fields | 34 pages. version 5. Many misprints are corrected and some minor
changes are made | Central European Journal of Mathematics, vol. 7, no. 2 (2009)
272-298 | 10.2478/s11533-009-0010-y | null | math.DS | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Let $F$ be a smooth vector field defined in a neighborhood of the origin in
$\mathbb{R}^n$, $F(O)=0$, and let $F_t$ be its local flow. Denote by $E$ the
set of germs of diffeomorphisms $h:\mathbb{R}^n \to \mathbb{R}^n$ preserving
orbits of $F$ and let $E_{\mathrm{id}}^r$ be the identity component of $E$ with
respect to $C^r$-topology. Then every $E_{\mathrm{id}}^{r}$ contains a subset
$Sh$ consisting of mappings of the form $F_{f(x)}(x)$, where $f: \mathbb{R}^n
\to \mathbb{R}$ is a smooth function. It was proved earlier by the author that
if $F$ is a linear vector field, then $Sh=E_{\mathrm{id}}^0$. In this paper we
present a class of vector fields for which $Sh$ and $E_{\mathrm{id}}^1$
coincide on the level of $\infty$-jets. We also establish a parameter rigidity
of linear vector fields and "reduced" Hamiltonian vector fields of real
homogeneous polynomials in two variables.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 10:26:00 GMT"
},
{
"version": "v2",
"created": "Sun, 16 Sep 2007 20:18:54 GMT"
},
{
"version": "v3",
"created": "Mon, 4 Feb 2008 18:36:29 GMT"
},
{
"version": "v4",
"created": "Sun, 1 Jun 2008 17:07:30 GMT"
},
{
"version": "v5",
"created": "Mon, 6 Oct 2008 07:35:40 GMT"
},
{
"version": "v6",
"created": "Tue, 20 Jan 2009 12:13:12 GMT"
},
{
"version": "v7",
"created": "Thu, 24 Dec 2015 13:08:47 GMT"
}
] | 2015-12-25T00:00:00 | [
[
"Maksymenko",
"Sergiy",
""
]
] |
0708.0738 | Keigo Nitadori | Keigo Nitadori, Junichiro Makino | 6th and 8th Order Hermite Integrator for N-body Simulations | 21 pages, 6 figures, New Astronomy accepted | NewAstron.13:498-507,2008 | 10.1016/j.newast.2008.01.010 | null | astro-ph | null | We present sixth- and eighth-order Hermite integrators for astrophysical
$N$-body simulations, which use the derivatives of accelerations up to second
order ({\it snap}) and third order ({\it crackle}). These schemes do not
require previous values for the corrector, and require only one previous value
to construct the predictor. Thus, they are fairly easy to implemente. The
additional cost of the calculation of the higher order derivatives is not very
high. Even for the eighth-order scheme, the number of floating-point operations
for force calculation is only about two times larger than that for traditional
fourth-order Hermite scheme. The sixth order scheme is better than the
traditional fourth order scheme for most cases. When the required accuracy is
very high, the eighth-order one is the best. These high-order schemes have
several practical advantages. For example, they allow a larger number of
particles to be integrated in parallel than the fourth-order scheme does,
resulting in higher execution efficiency in both general-purpose parallel
computers and GRAPE systems.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 10:26:54 GMT"
},
{
"version": "v2",
"created": "Thu, 9 Aug 2007 15:21:57 GMT"
},
{
"version": "v3",
"created": "Sat, 1 Sep 2007 10:55:21 GMT"
},
{
"version": "v4",
"created": "Mon, 4 Feb 2008 11:04:04 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Nitadori",
"Keigo",
""
],
[
"Makino",
"Junichiro",
""
]
] |
0708.0739 | Magdalena Zaluska-Kotur A | Filip Krzyzewski, Magdalena Zaluska-Kotur | Segregation in noninteracting binary mixture | 5 pages, 4 figures | null | 10.1103/PhysRevE.77.031502 | null | cond-mat.stat-mech cond-mat.soft | null | Process of stripe formation is analyzed numerically in a binary mixture. The
system consists of particles of two sizes, without any direct mutual
interactions. Overlapping of large particles, surrounded by a dense system of
smaller particles induces indirect entropy driven interactions between large
particles. Under an influence of an external driving force the system orders
and stripes are formed. Mean width of stripes grows logarithmically with time,
in contrast to a typical power law temporal increase observed for driven
interacting lattice gas systems. We describe the mechanism responsible for this
behavior and attribute the logarithmic growth to a random walk of large
particles in a random potential due to the small ones.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 10:37:17 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Krzyzewski",
"Filip",
""
],
[
"Zaluska-Kotur",
"Magdalena",
""
]
] |
0708.0740 | Alberto Imparato | A. Imparato, L. Peliti | Work and heat probability distributions in out-of-equilibrium systems | Contribution to Proceedings of "Work, Dissipation, and Fluctuations
in Nonequilibrium Physics", Brussels, 2006 | Comptes Rendus Physique 8, (2007) 556-566 | 10.1016/j.crhy.2007.04.017 | null | cond-mat.stat-mech | null | We review and discuss the equations governing the distribution of work done
on a system which is driven out of equilibrium by external manipulation, as
well as those governing the entropy flow to a reservoir in a nonequilibrium
system. We take advantage of these equations to investigate the path phase
transition in a manipulated mean-field Ising model and the large-deviation
function for the heat flow in the asymmetric exclusion process with
periodically varying transition probabilities.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 10:51:27 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Imparato",
"A.",
""
],
[
"Peliti",
"L.",
""
]
] |
0708.0741 | Shi Zhou Dr. | Shi Zhou, Ingemar Cox and Vaclav Petricek | Characterising Web Site Link Structure | To appear at IEEE/WSE07 | null | 10.1109/WSE.2007.4380247 | null | cs.IR | null | The topological structures of the Internet and the Web have received
considerable attention. However, there has been little research on the
topological properties of individual web sites. In this paper, we consider
whether web sites (as opposed to the entire Web) exhibit structural
similarities. To do so, we exhaustively crawled 18 web sites as diverse as
governmental departments, commercial companies and university departments in
different countries. These web sites consisted of as little as a few thousand
pages to millions of pages. Statistical analysis of these 18 sites revealed
that the internal link structure of the web sites are significantly different
when measured with first and second-order topological properties, i.e.
properties based on the connectivity of an individual or a pairs of nodes.
However, examination of a third-order topological property that consider the
connectivity between three nodes that form a triangle, revealed a strong
correspondence across web sites, suggestive of an invariant. Comparison with
the Web, the AS Internet, and a citation network, showed that this third-order
property is not shared across other types of networks. Nor is the property
exhibited in generative network models such as that of Barabasi and Albert.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 11:00:58 GMT"
}
] | 2016-11-17T00:00:00 | [
[
"Zhou",
"Shi",
""
],
[
"Cox",
"Ingemar",
""
],
[
"Petricek",
"Vaclav",
""
]
] |
0708.0742 | Cathie Clarke | C. Clarke, E. Harper-Clark, G. Lodato | The response of self-graviting protostellar discs to slow reduction in
cooling timescale: the fragmentation boundary revisited | accepted for publication in MNRAS | null | 10.1111/j.1365-2966.2007.12322.x | null | astro-ph | null | A number of previous studies of the fragmentation of self-gravitating
protostellar discs have modeled radiative cooling with a cooling timescale
(t_{cool}) parameterised as a simple multiple (beta_{cool}) of the local
dynamical timescale. Such studies have delineated the `fragmentation boundary'
in terms of a critical value of beta_{cool} (beta_{crit}), where the disc
fragments if beta_{cool} < beta_{crit}. Such an approach however begs the
question of how in reality a disc could ever be assembled with beta_{cool} <
beta_{crit}. Here we adopt the more realistic approach of gradually reducing
beta_{cool}, as might correspond to changes in thermal regime due to secular
changes in the disc density profile. We find that when beta_{cool} is gradually
reduced (on a timescale longer than t_{cool}), the disc is stabilised against
fragmentation, compared with models in which beta_{cool} is reduced rapidly. We
therefore conclude that a disc's ability to remain in a self-regulated,
self-gravitating state (without fragmentation) is partly dependent on its
thermal history, as well as its current cooling rate. Nevertheless, a slow
reduction in t_{cool} appears only to lower the fragmentation boundary by about
a factor two in t_{cool} and thus only permits maximum alpha values
(parameterising the efficiency of angular momentum transfer in the disc) that
are about a factor two higher than determined hitherto. Our results therefore
do not undermine the notion of a fundamental upper limit to the heating rate
that can be delivered by gravitational instabilities before the disc is subject
to fragmentation. An important implication of this work, therefore, is that
self-gravitating discs can enter into the regime of fragmentation via secular
evolution and it is not necessary to invoke rapid (impulsive) events to trigger
fragmentation.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 11:03:00 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Clarke",
"C.",
""
],
[
"Harper-Clark",
"E.",
""
],
[
"Lodato",
"G.",
""
]
] |
0708.0743 | Jean-Luc Lehners | Jean-Luc Lehners and Neil Turok | Bouncing Negative-Tension Branes | 20 pages, 1 figure, discussion extended and references added; minor
mistake corrected | Phys.Rev.D77:023516,2008 | 10.1103/PhysRevD.77.023516 | DAMTP-2007-73 | hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Braneworlds, understood here as double domain wall spacetimes, can be
described in terms of a linear harmonic function, with kinks at the locations
of the boundary branes. In a dynamical setting, there is therefore the risk
that the boundary brane of negative tension, at whose location the value of the
harmonic function is always lowest, can encounter a zero of this harmonic
function, corresponding to the formation of a singularity. We show that for
certain types of brane-bound matter this singularity can be avoided, and the
negative-tension brane can shield the bulk spacetime from the singularity by
bouncing back smoothly before reaching the singularity. In our analysis we
compare the 5- and 4-dimensional descriptions of this phenomenon in order to
determine the validity of the moduli space approximation.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 11:08:15 GMT"
},
{
"version": "v2",
"created": "Tue, 15 Jan 2008 16:15:32 GMT"
},
{
"version": "v3",
"created": "Fri, 5 Sep 2008 16:32:29 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Lehners",
"Jean-Luc",
""
],
[
"Turok",
"Neil",
""
]
] |
0708.0744 | T. H. Lenagan | S Launois, T H Lenagan and L Rigal | Prime ideals in the quantum grassmannian | 25 pages | null | null | null | math.QA math.CO math.RA | null | We consider quantum Schubert cells in the quantum grassmannian and give a
cell decomposition of the prime spectrum via the Schubert cells. As a
consequence, we show that all primes are completely prime in the generic case
where the deformation parameter q is not a root of unity. There is a torus H
that acts naturally on the quantum grassmannian and the cell decomposition of
the set of H-primes leads to a parameterisation of the H-spectrum via certain
diagrams on partitions associated to the Schubert cells. Interestingly, the
same parameterisation occurs for the non-negative cells in recent studies
concerning the totally non-negative grassmannian. Finally, we use the cell
decomposition to establish that the quantum grassmannian satisfies normal
separation and catenarity.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 11:19:16 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Launois",
"S",
""
],
[
"Lenagan",
"T H",
""
],
[
"Rigal",
"L",
""
]
] |
0708.0745 | Grigori Kirilin | G.G. Kirilin, I.S. Terekhov | Coulomb corrections to the Delbrueck scattering amplitude at low
energies | 8 pages, 6 figures | null | 10.1103/PhysRevA.77.032118 | null | hep-ph | null | In this article, we study the Coulomb corrections to the Delbrueck scattering
amplitude. We consider the limit when the energy of the photon is much less
than the electron mass. The calculations are carried out in the coordinate
representation using the exact relativistic Green function of an electron in a
Coulomb field. The resulting relative corrections are of the order of a few
percent for scattering on for a large charge of the nucleus. We compare the
corrections with the corresponding ones calculated through the dispersion
integral of the pair production cross section and also with the magnetic loop
contribution to the g-factor of a bound electron. The last one is in a good
agreement with our results but the corrections calculated through the
dispersion relation are not.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 11:40:25 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kirilin",
"G. G.",
""
],
[
"Terekhov",
"I. S.",
""
]
] |
0708.0746 | C.N.R. Rao Prof | Claudy Rayan Serrao, A Sundaresan and C N R Rao | Multiferroic nature of charge-ordered rare earth manganites | null | null | 10.1088/0953-8984/19/49/496217 | null | cond-mat.mtrl-sci cond-mat.str-el | null | Charge-ordered rare earth manganites Nd0.5Ca0.5MnO3, La0.25Nd0.25Ca0.5MnO3,
Pr0.7Ca0.3MnO3 and Pr0.6Ca0.4MnO3 are found to exhibit dielectric constant
anomalies around the charge-ordering or the magnetic transition temperatures.
Magnetic fields have a marked effect on the dielectric properties, indicating
the presence of coupling between the magnetic and electrical order parameters.
The observation of magnetoferroelectricity in these manganites is in accord
with the recent theoretical predictions of Khomskii and coworkers.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 11:34:21 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Serrao",
"Claudy Rayan",
""
],
[
"Sundaresan",
"A",
""
],
[
"Rao",
"C N R",
""
]
] |
0708.0747 | Mathieu Dutour Sikiri\'c | Mathieu Dutour Sikiric and Viatcheslav Grishukhin | The decomposition of the hypermetric cone into L-domains | 20 pages 2 figures, 2 tables | null | null | null | math.CO math.MG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The hypermetric cone $\HYP_{n+1}$ is the parameter space of basic Delaunay
polytopes in n-dimensional lattice. The cone $\HYP_{n+1}$ is polyhedral; one
way of seeing this is that modulo image by the covariance map $\HYP_{n+1}$ is a
finite union of L-domains, i.e., of parameter space of full Delaunay
tessellations.
In this paper, we study this partition of the hypermetric cone into
L-domains. In particular, it is proved that the cone $\HYP_{n+1}$ of
hypermetrics on n+1 points contains exactly {1/2}n! principal L-domains. We
give a detailed description of the decomposition of $\HYP_{n+1}$ for n=2,3,4
and a computer result for n=5 (see Table \ref{TableDataHYPn}). Remarkable
properties of the root system $\mathsf{D}_4$ are key for the decomposition of
$\HYP_5$.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 11:36:27 GMT"
},
{
"version": "v2",
"created": "Fri, 14 Dec 2007 19:45:04 GMT"
},
{
"version": "v3",
"created": "Fri, 16 May 2008 08:51:13 GMT"
},
{
"version": "v4",
"created": "Mon, 11 Aug 2008 14:30:44 GMT"
}
] | 2008-08-11T00:00:00 | [
[
"Sikiric",
"Mathieu Dutour",
""
],
[
"Grishukhin",
"Viatcheslav",
""
]
] |
0708.0748 | Viktor Soshnikov | V. N. Soshnikov | Collisionless damping of electron waves in non-Maxwellian plasma | 10 pages, 1 figure, PDF. Correction of the case of waves in
Maxwellian plasma stream | null | null | null | physics.plasm-ph | null | In this paper we have criticized the so-called Landau damping theory. We have
analyzed solutions of the standard dispersion equations for longitudinal
(electric) and transversal (electromagnetic and electron) waves in
half-infinite slab of the uniform collisionless plasmas with non-Maxwellian and
Maxwellian-like electron energy distribution functions. One considered the most
typical cases of both the delta-function type distribution function (the plasma
stream with monochromatic electrons) and distribution functions, different from
Maxwellian ones as with a surplus as well as with a shortage in the Maxwellian
distribution function tail. It is shown that there are present for the
considered cases both collisionless damping and also non-damping electron waves
even in the case of non-Maxwellian distribution function.
| [
{
"version": "v1",
"created": "Mon, 6 Aug 2007 12:24:34 GMT"
},
{
"version": "v2",
"created": "Sat, 19 Jan 2008 18:06:14 GMT"
},
{
"version": "v3",
"created": "Sat, 9 Feb 2008 11:16:16 GMT"
},
{
"version": "v4",
"created": "Mon, 10 Mar 2008 14:37:36 GMT"
},
{
"version": "v5",
"created": "Sun, 30 Mar 2008 15:17:30 GMT"
}
] | 2008-03-30T00:00:00 | [
[
"Soshnikov",
"V. N.",
""
]
] |
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