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| versions
list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0707.2530 | Jozsef Vinko | K. Sziladi, J. Vinko, E. Poretti, L. Szabados, M. Kun | New homogeneous iron abundances of double-mode Cepheids from
high-resolution echelle spectroscopy | 10 pages, 7 figures, accepted in A&A | null | 10.1051/0004-6361:20077539 | null | astro-ph | null | Aims: We define the relationship between the double-mode pulsation of
Cepheids and metallicity in a more accurate way, determine the empirical
metallicities of double-mode Cepheids from homogeneous, high-resolution
spectroscopic data, and study of the period-ratio -- metallicity dependence.
Methods: The high S/N echelle spectra obtained with the FEROS spectrograph were
analyzed using a self-developed IRAF script, and the iron abundances were
determined by comparing with synthetic spectra assuming LTE. Results: Accurate
[Fe/H] values of 17 galactic beat Cepheids were determined. All these stars
have solar or slightly subsolar metallicity. Their period ratio P1/P0 shows
strong correlation with their derived [Fe/H] values. The corresponding period
ratio -- metallicity relation has been evaluated.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 14:37:28 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sziladi",
"K.",
""
],
[
"Vinko",
"J.",
""
],
[
"Poretti",
"E.",
""
],
[
"Szabados",
"L.",
""
],
[
"Kun",
"M.",
""
]
] |
0707.2531 | Bekir Can Lutfuoglu | B.C. Lutfuoglu and F. Taskin | Renormalization Group Analysis of a Gursey Model Inspired Field Theory
II | 10 pages, 10 figures, revtex4, typos corrected, published version | Phys.Rev.D76:105010,2007 | 10.1103/PhysRevD.76.105010 | null | hep-th | null | Recently a model, which is equivalent to the scalar form of Gursey model, is
shown to be a nontrivial field theoretical model when it is gauged with a SU(N)
field. In this paper we study another model that is equivalent to the vector
form of the Gursey model. We get a trivial theory when it is coupled with a
scalar field. This result changes drastically when it is coupled with an
additional SU(N) field. We find a nontrivial field theoretical model under
certain conditions.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 14:35:56 GMT"
},
{
"version": "v2",
"created": "Tue, 20 Nov 2007 12:26:01 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Lutfuoglu",
"B. C.",
""
],
[
"Taskin",
"F.",
""
]
] |
0707.2532 | Barbara Sciascia | The KLOE Collaboration | KLOE measurement of the charged kaon absolute semileptonic BR's | Contributed paper to Lepton Photon 2007, Daegu, Korea, 13-18 August
2007, 5 pages, 2 figures | PoS KAON:014,2008 | null | null | hep-ex | null | This paper is devoted to the measurement of the fully inclusive absolute
branching ratios of the charged kaon semileptonic decays,
$K^{\pm}\to\pi^0e^\pm\nu(\gamma)$ and $K^\pm \to \pi^0\mu^\pm\nu(\gamma)$. The
measurements have been done using a tag technique, employing the two-body
decays, $K^\pm \to \mu^\pm\nu$ and $K^\pm \to \pi^\pm\pi^0$, and using a sample
of about 410 pb$^{-1}$ collected during the 2001 and 2002 data taking of the
KLOE experiment at Daphne, the Frascati $\phi$-factory. The results obtained
are BR(K$^\pm_{e3}$) = $0.04965 (38)_{Stat} (37)_{Syst}$ and BR(K$^\pm_{\mu3}$)
= $0.03233 (29)_{Stat} (26)_{Syst}$.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 14:41:41 GMT"
}
] | 2012-08-27T00:00:00 | [
[
"The KLOE Collaboration",
"",
""
]
] |
0707.2533 | Takayuki Nakamura | J. Sugiyama (1), T. Nakamura (1), N. Ishii (2), T. Nishikawa (1), M.
Oka (1) ((1) Tokyo Inst. Tech., (2) Tsukuba U., RCCP) | Mixings of 4-quark components in light non-singlet scalar mesons in QCD
sum rules | 8 pages, 9 figures | Phys.Rev.D76:114010,2007 | 10.1103/PhysRevD.76.114010 | null | hep-ph | null | Mixings of 4-quark components in the non-singlet scalar mesons are studied in
the QCD sum rules. We propose a formulation to evaluate the cross correlators
of q\bar q and qq\bar q \bar q operators and to define the mixings of different
Fock states in the sum rule. It is applied to the non-singlet scalar mesons,
a_0 and K_0^\ast. It is found that the 4-quark operators predict lower masses
than the q\bar q operators and that the 4-quark states occupy about 70-90% of
the lowest mass states.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:09:39 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Sugiyama",
"J.",
"",
"Tokyo Inst. Tech"
],
[
"Nakamura",
"T.",
"",
"Tokyo Inst. Tech"
],
[
"Ishii",
"N.",
"",
"Tsukuba U., RCCP"
],
[
"Nishikawa",
"T.",
"",
"Tokyo Inst. Tech"
],
[
"Oka",
"M.",
"",
"Tokyo Inst. Tech"
]
] |
0707.2534 | Fabio Franchini | F. Franchini, A. R. Its and V. E. Korepin | Renyi Entropy of the XY Spin Chain | 28 Pages, 1 Figure | J. Phys. A: Math. Theor. 41 (2008) 025302 | 10.1088/1751-8113/41/2/025302 | null | quant-ph cond-mat.stat-mech hep-th | null | We consider the one-dimensional XY quantum spin chain in a transverse
magnetic field. We are interested in the Renyi entropy of a block of L
neighboring spins at zero temperature on an infinite lattice. The Renyi entropy
is essentially the trace of some power $\alpha$ of the density matrix of the
block. We calculate the asymptotic for $L \to \infty$ analytically in terms of
Klein's elliptic $\lambda$ - function. We study the limiting entropy as a
function of its parameter $\alpha$. We show that up to the trivial addition
terms and multiplicative factors, and after a proper re-scaling, the Renyi
entropy is an automorphic function with respect to a certain subgroup of the
modular group; moreover, the subgroup depends on whether the magnetic field is
above or below its critical value. Using this fact, we derive the
transformation properties of the Renyi entropy under the map $\alpha \to
\alpha^{-1}$ and show that the entropy becomes an elementary function of the
magnetic field and the anisotropy when $\alpha$ is a integer power of 2, this
includes the purity $tr \rho^2$. We also analyze the behavior of the entropy as
$\alpha \to 0$ and $\infty$ and at the critical magnetic field and in the
isotropic limit [XX model].
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 14:59:31 GMT"
},
{
"version": "v2",
"created": "Mon, 8 Oct 2007 12:11:36 GMT"
},
{
"version": "v3",
"created": "Wed, 14 Nov 2007 14:29:19 GMT"
},
{
"version": "v4",
"created": "Wed, 26 Dec 2007 07:07:55 GMT"
}
] | 2010-02-16T00:00:00 | [
[
"Franchini",
"F.",
""
],
[
"Its",
"A. R.",
""
],
[
"Korepin",
"V. E.",
""
]
] |
0707.2535 | Tamas Geszti | Jozsef Zsolt Bernad, Andras Bodor, Lajos Diosi and Tamas Geszti | Simple theory of the measured current through quantum dots | 4 pages, 2 figures | Phys.Rev. B77 (2008) 073311-(4) | 10.1103/PhysRevB.77.073311 | null | cond-mat.mes-hall | null | A simple theory of the detected current I(t) flowing through charge qubits --
quantum dots -- is proposed in terms of standard continuous measurement theory.
Applied to a double dot, our formalism easily confirms previous results on
quantum Zeno effect, driven by growing ammeter performance gamma. Due to the
transparent formalism, we can calculate the exact fluctuation spectrum S(omega)
of the detected current, containing a significant Lorentzian peak near the Rabi
frequency of the double dot.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:04:13 GMT"
}
] | 2013-05-29T00:00:00 | [
[
"Bernad",
"Jozsef Zsolt",
""
],
[
"Bodor",
"Andras",
""
],
[
"Diosi",
"Lajos",
""
],
[
"Geszti",
"Tamas",
""
]
] |
0707.2536 | Jean-Paul Auffray | Jean-Paul Auffray | On Lee Smolin's The Trouble with Physics | 6 pages | null | null | null | physics.gen-ph | null | Lee Smolin's casual accounting of special and general relativity in The
Trouble with Physics raises an interesting question: is it possible to develop
a legitimate argument concerning string theories starting from a shaky basis?
This is apparently what Lee Smolin succeeded in doing when he wrote The Trouble
with Physics. The book's shortcomings are nevertheless troublesome.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:04:40 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Auffray",
"Jean-Paul",
""
]
] |
0707.2537 | Elaine Winston | E. Winston, S. T. Megeath, S. J. Wolk, J. Muzerolle, R. Gutermuth, J.
L. Hora, L.E. Allen, B. Spitzbart, P. Myers, G. G. Fazio | A Combined Spitzer and Chandra Survey of Young Stellar Objects in the
Serpens Cloud Core | 69 pages, 16 figures, accepted to ApJ. Higher Resolution Figures at:
http://www.cfa.harvard.edu/~ewinston/ | Astrophys.J.669:493-518,2007 | 10.1086/521384 | null | astro-ph | null | We present Spitzer and Chandra observations of the nearby (~260 pc) embedded
stellar cluster in the Serpens Cloud Core. We observed, using Spitzer's IRAC
and MIPS instruments, in six wavelength bands from 3 to 70 ${\mu}m$, to detect
thermal emission from circumstellar disks and protostellar envelopes, and to
classify stars using color-color diagrams and spectral energy distributions
(SEDs). These data are combined with Chandra observations to examine the
effects of circumstellar disks on stellar X-ray properties. Young diskless
stars were also identified from their increased X-ray emission. We have
identified 138 YSOs in Serpens: 22 class 0/I, 16 flat spectrum, 62 class II, 17
transition disk, and 21 class III stars; 60 of which exhibit X-ray emission.
Our primary results are the following: 1.) ten protostars detected previously
in the sub-millimeter are detected at lambda < 24 microns, seven at lambda < 8
microns, 2.) the protostars are more closely grouped than more evolved YSOs
(median separation : ~0.024 pc, and 3.) the luminosity and temperature of the
X-ray emitting plasma around these YSOs does not show any significant
dependence on evolutionary class. We combine the infrared derived values of AK
and X-ray values of NH for 8 class III objects and find that the column density
of hydrogen gas per mag of extinctions is less than half the standard
interstellar value, for AK > 1. This may be the result of grain growth through
coagulation and/or the accretion of volatiles in the Serpens cloud core.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:07:02 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Winston",
"E.",
""
],
[
"Megeath",
"S. T.",
""
],
[
"Wolk",
"S. J.",
""
],
[
"Muzerolle",
"J.",
""
],
[
"Gutermuth",
"R.",
""
],
[
"Hora",
"J. L.",
""
],
[
"Allen",
"L. E.",
""
],
[
"Spitzbart",
"B.",
""
],
[
"Myers",
"P.",
""
],
[
"Fazio",
"G. G.",
""
]
] |
0707.2538 | Jori Liesenborgs | J. Liesenborgs, S. De Rijcke, H. Dejonghe, P. Bekaert | Non-parametric inversion of gravitational lensing systems with few
images using a multi-objective genetic algorithm | 9 pages, accepted for publication by MNRAS | null | 10.1111/j.1365-2966.2007.12236.x | null | astro-ph | null | Galaxies acting as gravitational lenses are surrounded by, at most, a handful
of images. This apparent paucity of information forces one to make the best
possible use of what information is available to invert the lens system. In
this paper, we explore the use of a genetic algorithm to invert in a
non-parametric way strong lensing systems containing only a small number of
images. Perhaps the most important conclusion of this paper is that it is
possible to infer the mass distribution of such gravitational lens systems
using a non-parametric technique. We show that including information about the
null space (i.e. the region where no images are found) is prerequisite to avoid
the prediction of a large number of spurious images, and to reliably
reconstruct the lens mass density. While the total mass of the lens is usually
constrained within a few percent, the fidelity of the reconstruction of the
lens mass distribution depends on the number and position of the images. The
technique employed to include null space information can be extended in a
straightforward way to add additional constraints, such as weak lensing data or
time delay information.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:12:57 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Liesenborgs",
"J.",
""
],
[
"De Rijcke",
"S.",
""
],
[
"Dejonghe",
"H.",
""
],
[
"Bekaert",
"P.",
""
]
] |
0707.2539 | Bassano Vacchini | Heinz-Peter Breuer and Bassano Vacchini | Three-dimensional Monte Carlo simulations of the quantum linear
Boltzmann equation | 11 pages, revtex, 11 figures | Phys. Rev. E 76 (2007) 036706 | 10.1103/PhysRevE.76.036706 | null | quant-ph cond-mat.stat-mech | null | Recently the general form of a translation-covariant quantum Boltzmann
equation has been derived which describes the dynamics of a tracer particle in
a quantum gas. We develop a stochastic wave function algorithm that enables
full three-dimensional Monte Carlo simulations of this equation. The simulation
method is used to study the approach to equilibrium for various scattering
cross sections and to determine dynamical deviations from Gaussian statistics
through an investigation of higher-order cumulants. Moreover, we examine the
loss of coherence of superpositions of momentum eigenstates and determine the
corresponding decoherence time scales to quantify the transition from quantum
to classical behavior of the state of the test particle.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:15:12 GMT"
}
] | 2007-09-24T00:00:00 | [
[
"Breuer",
"Heinz-Peter",
""
],
[
"Vacchini",
"Bassano",
""
]
] |
0707.2540 | Patrick Rinke | Biswajit Santra, Angelos Michaelides and Matthias Scheffler | On how good DFT exchange-correlation functionals are for H bonds in
small water clusters: Benchmarks approaching the complete basis set limit | 9 pages including 4 figures; related publications can be found at
http://www.fhi-berlin.mpg.de/th/th.html | J. Chem. Phys. 127, 184104 (2007) | 10.1063/1.2790009 | null | cond-mat.mtrl-sci | null | The ability of several density-functional theory (DFT) exchange-correlation
functionals to describe hydrogen bonds in small water clusters (dimer to
pentamer) in their global minimum energy structures is evaluated with reference
to second order Moeller Plesset perturbation theory (MP2). Errors from basis
set incompleteness have been minimized in both the MP2 reference data and the
DFT calculations, thus enabling a consistent systematic evaluation of the true
performance of the tested functionals. Among all the functionals considered,
the hybrid X3LYP and PBE0 functionals offer the best performance and among the
non-hybrid GGA functionals mPWLYP and PBE1W perform the best. The popular BLYP
and B3LYP functionals consistently underbind and PBE and PW91 display rather
variable performance with cluster size.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:15:14 GMT"
}
] | 2009-07-20T00:00:00 | [
[
"Santra",
"Biswajit",
""
],
[
"Michaelides",
"Angelos",
""
],
[
"Scheffler",
"Matthias",
""
]
] |
0707.2541 | Changzheng Yuan | Belle Collaboration: C. Z. Yuan, et al | Measurement of e^+e^- to pi^+pi^-J/psi Cross Section via Initial State
Radiation at Belle | 11 pages, 5 figures, 2 tables; version to appear in PRL | Phys.Rev.Lett.99:182004,2007 | 10.1103/PhysRevLett.99.182004 | Belle Preprint 2007-31; KEK Preprint 2007-23 | hep-ex hep-ph | null | The cross section for e^+e^- to pi^+pi^-J/psi between 3.8 and 5.5 GeV/c^2 is
measured using a 548 fb^{-1} data sample collected on or near the Upsilon(4S)
resonance with the Belle detector at KEKB. A peak near 4.25 GeV/c^2,
corresponding to the so called Y(4260), is observed. In addition, there is
another cluster of events at around 4.05 GeV/c^2. A fit using two interfering
Breit-Wigner shapes describes the data better than one that uses only the
Y(4260), especially for the lower mass side of the 4.25 GeV enhancement.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:18:54 GMT"
},
{
"version": "v2",
"created": "Fri, 21 Sep 2007 00:15:27 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Belle Collaboration",
"",
""
],
[
"Yuan",
"C. Z.",
""
]
] |
0707.2542 | St\'ephane Dugowson | St\'ephane Dugowson | Representation of finite connective spaces | 15 pages, 11 figures, in French | null | null | null | math.GN math.AT | null | After recalling the definition of connectivity spaces and some of their main
properties, a way is proposed to represent finite connectivity spaces by
directed simple graphs. Then a connectivity structure is associated to each
tame link. It is showed that all spaces of a certain class (the iterated
Brunnian ones) admit representations by links. Finally, I conjecture that every
finite connectivity space is representable by a link.
-----
Apres un rappel de la definition des espaces connectifs et de certaines de
leurs principales proprietes, nous proposons une maniere de representer les
espaces connectifs finis par des graphes simples orientes, puis nous associons
a tout entrelacs une structure connective. Nous montrons que tout espace d'une
certaine classe (les espaces brunniens iteres) admet une representation par
entrelacs, et nous conjecturons finalement que tout espace connectif fini est
representable par entrelacs.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 19:19:35 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Dugowson",
"Stéphane",
""
]
] |
0707.2543 | Frank Simon | F. Simon, B. Azmoun, U. Becker, L. Burns, D. Crary, K. Kearney, G.
Keeler, R. Majka, K. Paton, G. Saini, N. Smirnov, B. Surrow, C. Woody | Development of Tracking Detectors with industrially produced GEM Foils | 6 pages, 14 figures, published in IEEE Transactions on Nuclear
Science, v2 updated text and figures | IEEETrans.Nucl.Sci.54:2646-2652,2007 | 10.1109/TNS.2007.909912 | null | physics.ins-det | null | The planned tracking upgrade of the STAR experiment at RHIC includes a
large-area GEM tracker used to determine the charge sign of electrons and
positrons produced from W+(-) decays. For such a large-scale project commercial
availability of GEM foils is necessary. We report first results obtained with a
triple GEM detector using GEM foils produced by Tech-Etch Inc. of Plymouth, MA,
USA. Measurements of gain uniformity, long-term stability as well as
measurements of the energy resolution for X-Rays are compared to results
obtained with an identical detector using GEM foils produced at CERN. A quality
assurance procedure based on optical tests using an automated high-resolution
scanner has been established, allowing a study of the correlation of the
observed behavior of the detector and the geometrical properties of the GEM
foils. Detectors based on Tech-Etch and CERN produced foils both show good
uniformity of the gain over the active area and stable gain after an initial
charge-up period, making them well suited for precision tracking applications.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:32:07 GMT"
},
{
"version": "v2",
"created": "Sun, 16 Dec 2007 17:22:50 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Simon",
"F.",
""
],
[
"Azmoun",
"B.",
""
],
[
"Becker",
"U.",
""
],
[
"Burns",
"L.",
""
],
[
"Crary",
"D.",
""
],
[
"Kearney",
"K.",
""
],
[
"Keeler",
"G.",
""
],
[
"Majka",
"R.",
""
],
[
"Paton",
"K.",
""
],
[
"Saini",
"G.",
""
],
[
"Smirnov",
"N.",
""
],
[
"Surrow",
"B.",
""
],
[
"Woody",
"C.",
""
]
] |
0707.2544 | Vicente Bitrian | Vicente Bitri\'an and Joaquim Trull\`as | A polarizable ion model for the structure of molten AgI | 12 pages, 4 figures | The Journal of Chemical Physics 126, 021105 (2007) | 10.1063/1.2432346 | null | cond-mat.soft physics.chem-ph | null | The results are reported of the molecular dynamics simulations of the
coherent static structure factor of molten AgI at 923 K using a polarizable ion
model. This model is based on a rigid ion potential, to which the many body
interactions due to the anions induced polarization are added. The calculated
structure factor is in better agreement with recent neutron diffraction data
than that obtained by using simple rigid ion pair potentials. The
Voronoi-Delaunay method has been applied to study the relationship between
voids in the spatial distribution of cations and the prepeak of the structure
factor.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:37:37 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Bitrián",
"Vicente",
""
],
[
"Trullàs",
"Joaquim",
""
]
] |
0707.2545 | Javier L. Albacete | Javier L. Albacete | Particle multiplicities in Lead-Lead collisions at the LHC from
non-linear evolution with running coupling | Version accepted for publication by Phys. Rev. Lett. Typos corrected,
one figure removed and references updated | Phys.Rev.Lett.99:262301,2007 | 10.1103/PhysRevLett.99.262301 | null | hep-ph | null | We present predictions for the pseudo-rapidity density of charged particles
produced in central Pb-Pb collisions at the LHC. Particle production in such
collisions is calculated in the framework of k_t-factorization. The nuclear
unintegrated gluon distributions at LHC energies are determined from numerical
solutions of the Balitsky-Kovchegov equation including recently calculated
running coupling corrections. The initial conditions for the evolution are
fixed by fitting RHIC data at collision energies \sqrt{s}}=130 and 200 GeV per
nucleon. We obtain dN^{Pb-Pb}_{ch}/d\eta (\sqrt{s}=5.5 TeV, \eta=0)\approx
1290\div 1480.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:37:44 GMT"
},
{
"version": "v2",
"created": "Tue, 7 Aug 2007 18:19:32 GMT"
},
{
"version": "v3",
"created": "Mon, 22 Oct 2007 08:44:40 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Albacete",
"Javier L.",
""
]
] |
0707.2546 | Chen Yanjun | Y. J. Chen, and J. Liu | High-order harmonic generation from diatomic molecules with large
internuclear distance: The effect of two-center interference | 5 pages,4 figures | null | 10.1103/PhysRevA.77.013410 | null | physics.atom-ph | null | In the present paper, we investigate the high-order harmonic generation (HHG)
from diatomic molecules with large internuclear distance using a strong field
approximation (SFA) model. We find that the hump and dip structure emerges in
the plateau region of the harmonic spectrum, and the location of this striking
structure is sensitive to the laser intensity. Our model analysis reveals that
two-center interference as well as the interference between different
recombination electron trajectories are responsible for the unusual enhanced or
suppressed harmonic yield at a certain order, and these interference effects
are greatly influenced by the laser parameters such as intensity.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:39:08 GMT"
},
{
"version": "v2",
"created": "Sat, 1 Mar 2008 16:28:21 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Chen",
"Y. J.",
""
],
[
"Liu",
"J.",
""
]
] |
0707.2547 | Aris Karastergiou | A. Karastergiou, S. Johnston | An empirical model for the beams of radio pulsars | Accepted for publication in MNRAS | null | 10.1111/j.1365-2966.2007.12237.x | null | astro-ph | null | Motivated by recent results on the location of the radio emission in pulsar
magnetospheres, we have developed a model which can account for the large
diversity found in the average profile shapes of pulsars. At the centre of our
model lies the idea that radio emission at a particular frequency arises from a
wide range of altitudes above the surface of the star and that it is confined
to a region close to the last open field lines. We assert that the radial
height range over which emission occurs is responsible for the complex average
pulse shapes rather than the transverse (longitudinal) range proposed in most
current models. By implementing an abrupt change in the height range to
discriminate between young, short-period, highly-energetic pulsars and their
older counterparts, we obtain the observed transition between the simple and
complex average pulse profiles observed in each group respectively. Monte Carlo
simulations are used to demonstrate the match of our model to real
observations.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:47:24 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Karastergiou",
"A.",
""
],
[
"Johnston",
"S.",
""
]
] |
0707.2548 | Dah-Wei Chiou | Dah-Wei Chiou and Kevin Vandersloot | The behavior of non-linear anisotropies in bouncing Bianchi I models of
loop quantum cosmology | 15 pages, 10 figures | Phys.Rev.D76:084015,2007 | 10.1103/PhysRevD.76.084015 | IGPG-07/5-1 | gr-qc astro-ph | null | In homogeneous and isotropic loop quantum cosmology, gravity can behave
repulsively at Planckian energy densities leading to the replacement of the big
bang singularity with a big bounce. Yet in any bouncing scenario it is
important to include non-linear effects from anisotropies which typically grow
during the collapsing phase. We investigate the dynamics of a Bianchi I
anisotropic model within the framework of loop quantum cosmology. Using
effective semi-classical equations of motion to study the dynamics, we show
that the big bounce is still predicted with only differences in detail arising
from the inclusion of anisotropies. We show that the anisotropic shear term
grows during the collapsing phase, but remains finite through the bounce.
Immediately following the bounce, the anisotropies decay and with the inclusion
of matter with equation of state $w < +1$, the universe isotropizes in the
expanding phase.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:16:36 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Chiou",
"Dah-Wei",
""
],
[
"Vandersloot",
"Kevin",
""
]
] |
0707.2549 | Zlatko Koinov | Z. Koinov | Cavity polaritons in the presence of symmetry-breaking disorder:
closed-path time formalism | 13 pages | null | null | null | cond-mat.str-el cond-mat.dis-nn | null | According to the mean-field theory of Zittartz, when subject to a
symmetry-breaking disorder, the order parameter and the energy gap of an
excitonic insulator are gradually suppressed up to a critical disorder
strength. Recently, Marchetti, Simons, and Littlewood have used a replica trick
to investigate the effects of disorder on the condensation of cavity
polaritons. Within their nonlinear sigma model, it was found that the
saddle-point equations assume the form reported previously by Zittartz in the
contest of the symmetry broken excitonic insulator, but with an order
parameter, to which both photons and excitons contribute. In this paper, we
apply a closed-path time Green's function approach as an alternative to the
replica technique to formulate a nonperturbative description of cavity
polaritons in the presence of a symmetry-breaking disorder. A field theoretical
method is used to derive the Schwinger-Dyson equations for the average photon
field and the average single-particle Green's function. In contrast with the
nonlinear sigma model and the corresponding saddle-point equations, we obtain
that the exact Schwinger-Dyson equations cannot be mapped to the corresponding
equations derived by Zittartz. This result not only shows that the theory of
Zittartz cannot be applied to the excitons in a disordered quantum well coupled
to the cavity photons with only minor modifications, but arises a question
about the validity of the replica trick as well.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:54:53 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Koinov",
"Z.",
""
]
] |
0707.2550 | Thilo Kopp | J. Mannhart, T. Kopp and Y. S. Barash | How Large is the Intrinsic Flux Noise of a Magnetic Flux Quantum, of
Half a Flux Quantum and of a Vortex-Free Superconductor? | 11 pages, 3 figures. in: A. Bussmann-Holder, H. Keller (Eds.) High Tc
Superconductors and Related Transition Metal Oxides, Springer, 237-242; also
to be published in: Journal of Superconductivity (2007) | null | 10.1007/978-3-540-71023-3 | null | cond-mat.supr-con cond-mat.stat-mech | null | This article addresses the question whether the magnetic flux of stationary
vortices or of half flux quanta generated by frustrated superconducting rings
is noisy. It is found that the flux noise generated intrinsically by a
superconductor is, in good approximation, not enhanced by stationary vortices.
Half flux quanta generated by $\pi$-rings are characterized by considerably
larger noise.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:58:30 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Mannhart",
"J.",
""
],
[
"Kopp",
"T.",
""
],
[
"Barash",
"Y. S.",
""
]
] |
0707.2551 | Ulrich S. Schwarz | A. Besser and U. S. Schwarz (University of Heidelberg) | Coupling biochemistry and mechanics in cell adhesion: a model for
inhomogeneous stress fiber contraction | Revtex, 35 pages, 13 Postscript figures included, in press with New
Journal of Physics, Special Issue on The Physics of the Cytoskeleton | New J. Phys., 9:425, 2007 | 10.1088/1367-2630/9/11/425 | null | q-bio.SC q-bio.CB | null | Biochemistry and mechanics are closely coupled in cell adhesion. At sites of
cell-matrix adhesion, mechanical force triggers signaling through the
Rho-pathway, which leads to structural reinforcement and increased
contractility in the actin cytoskeleton. The resulting force acts back to the
sites of adhesion, resulting in a positive feedback loop for mature adhesion.
Here we model this biochemical-mechanical feedback loop for the special case
when the actin cytoskeleton is organized in stress fibers, which are
contractile bundles of actin filaments. Activation of myosin II molecular
motors through the Rho-pathway is described by a system of reaction-diffusion
equations, which are coupled into a viscoelastic model for a contractile actin
bundle. We find strong spatial gradients in the activation of contractility and
in the corresponding deformation pattern of the stress fiber, in good agreement
with experimental findings.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 15:58:57 GMT"
},
{
"version": "v2",
"created": "Wed, 24 Oct 2007 17:01:16 GMT"
}
] | 2010-02-24T00:00:00 | [
[
"Besser",
"A.",
"",
"University of Heidelberg"
],
[
"Schwarz",
"U. S.",
"",
"University of Heidelberg"
]
] |
0707.2552 | Jie Gao | Jie Gao, Pascal Heider, Charlton J. Chen, Xiaodong Yang, Chad A.
Husko, and Chee Wei Wong | Observations of interior whispering gallery modes in asymmetric optical
resonators with rational caustics | 11 pages, 4 figures | null | 10.1063/1.2800308 | null | physics.optics | null | We propose asymmetric resonant cavities with rational caustics and
experimentally demonstrate interior whispering gallery modes in monolithic
silicon mesoscopic microcavities. These microcavities demonstrate unique
robustness of cavity quality factor (Q) against roughness Rayleigh scattering.
Angle-resolved tapered fiber measurements and near-field images observe
distinct resonant families and asymmetric emission from interior whispering
gallery modes, which can be used for microcavity laser and CQED applications.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:01:31 GMT"
},
{
"version": "v2",
"created": "Sat, 25 Aug 2007 19:15:30 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Gao",
"Jie",
""
],
[
"Heider",
"Pascal",
""
],
[
"Chen",
"Charlton J.",
""
],
[
"Yang",
"Xiaodong",
""
],
[
"Husko",
"Chad A.",
""
],
[
"Wong",
"Chee Wei",
""
]
] |
0707.2553 | Bernd Kniehl | W. Hollik, T. Kasprzik, B.A. Kniehl | Electroweak corrections to W-boson hadroproduction at finite transverse
momentum | 27 pages, 13 figures; typos corrected, references added, matches
version to appear in Nucl. Phys. B | Nucl.Phys.B790:138-159,2008 | 10.1016/j.nuclphysb.2007.09.013 | DESY 07-103, MPP-2007-96 | hep-ph hep-ex | null | We calculate the full one-loop electroweak radiative corrections to the cross
section of single W-boson inclusive hadroproduction at finite transverse
momentum (p_T). This includes the O(alpha) corrections to W+j production, the
O(alpha_s) corrections to W+gamma production, and the tree-level contribution
from W+j photoproduction with one direct or resolved photon in the initial
state. We present the integrated cross section as a function of a minimum-p_T
cut as well as the p_T distribution for the experimental conditions at the
Fermilab Tevatron and the CERN LHC and estimate the theoretical uncertainties.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:05:47 GMT"
},
{
"version": "v2",
"created": "Fri, 12 Oct 2007 16:00:54 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hollik",
"W.",
""
],
[
"Kasprzik",
"T.",
""
],
[
"Kniehl",
"B. A.",
""
]
] |
0707.2554 | Jorge Rocha | M. Bessa and J. Rocha | On C1-robust transitivity of volume-preserving flows | null | null | null | null | math.DS | null | We prove that a divergence-free and C1-robustly transitive vector field has
no singularities. Moreover, if the vector field is C4 then the linear Poincare
flow associated to it admits a dominated splitting over M.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:08:01 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Bessa",
"M.",
""
],
[
"Rocha",
"J.",
""
]
] |
0707.2555 | Suman Kumar Banik | Jyotipratim Ray Chaudhuri, Sudip Chattopadhyay, and Suman Kumar Banik | Generalization of escape rate from a metastable state driven by external
cross-correlated noise processes | 9 pages, 1 figure | Phys. Rev. E 76, 021125 (2007) | 10.1103/PhysRevE.76.021125 | null | cond-mat.stat-mech cond-mat.soft | null | We propose generalization of escape rate from a metastable state for
externally driven correlated noise processes in one dimension. In addition to
the internal non-Markovian thermal fluctuations, the external correlated noise
processes we consider are Gaussian, stationary in nature and are of
Ornstein-Uhlenbeck type. Based on a Fokker-Planck description of the effective
noise processes with finite memory we derive the generalized escape rate from a
metastable state in the moderate to large damping limit and investigate the
effect of degree of correlation on the resulting rate. Comparison of the
theoretical expression with numerical simulation gives a satisfactory agreement
and shows that by increasing the degree of external noise correlation one can
enhance the escape rate through the dressed effective noise strength.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:08:54 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Chaudhuri",
"Jyotipratim Ray",
""
],
[
"Chattopadhyay",
"Sudip",
""
],
[
"Banik",
"Suman Kumar",
""
]
] |
0707.2556 | Anuj Purwar | Anuj K. Purwar | Study of Initial and Final State Effects in Ultrarelativistic Heavy Ion
Collisions Using Hadronic Probes | Dissertation submitted for PhD at Stony Brook University (December
2004) as part of the PHENIX collaboration | null | null | null | nucl-ex | null | It has been theorized that if heavy nuclei (e.g. Au, Pb) are collided at
sufficiently high energies, we might be to recreate the conditions that existed
in the universe a few microseconds after the Big Bang. The kinetic energy of
the colliding nuclei gets converted into heat, leading to a phase transition
into a new state of matter: the Quark-Gluon Plasma (QGP), in which quarks and
gluons are deconfined. However, we never directly get to see the QGP because as
the matter cools it recombines (hadronizes) into ordinary subatomic particles.
We can only hope to infer its existence from indirect experimental signatures,
after hadronization. In this dissertation we attempt to shed some light on:
Properties of the final state of produced matter in Au+Au collisions at
$\sqrt{s_{NN}}=200$ GeV. As the hot, dense system of particles from the
collision zone cools and expands, light nuclei like deuterons and
anti-deuterons can be formed, with a probability proportional to the product of
the phase space densities of its constituent nucleons. Thus, invariant yield of
deuterons, compared to the protons and neutrons from which they coalesce,
provides information about the size of the emitting system and its space-time
evolution.
The initial conditions that led to this. This is done by looking at the
nuclear modification factor $R_{cp}$ from particle production in forward and
backward directions in a ``control'' experiment using d+Au collisions at
$\sqrt{s_{NN}}=200$ GeV. This can allow us to distinguish between effects that
could potentially be due to deconfinement, versus effects of cold nuclear
matter.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 18:41:28 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Purwar",
"Anuj K.",
""
]
] |
0707.2557 | Philip Gressman | Philip T. Gressman | Uniform estimates for cubic oscillatory integrals | 22 pages; v2 added references | null | null | null | math.CA | null | This paper establishes the optimal decay rate for scalar oscillatory
integrals in $n$ variables which satisfy a nondegeneracy condition on the third
derivatives. The estimates proved are stable under small linear perturbations,
as encountered when computing the Fourier transform of surface-carried
measures. The main idea of the proof is to construct a nonisotropic family of
balls which locally capture the scales and directions in which cancellation
occurs.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:28:07 GMT"
},
{
"version": "v2",
"created": "Thu, 19 Jul 2007 16:33:34 GMT"
}
] | 2007-07-19T00:00:00 | [
[
"Gressman",
"Philip T.",
""
]
] |
0707.2558 | Andrew Norris | Andrew N. Norris | Faxen relations in solids - a generalized approach to particle motion in
elasticity and viscoelasticity | 11 pages, 4 figures | J. Acoust. Soc. Am. 123 (1), 99-108, 2008. | 10.1121/1.2817359 | null | cond-mat.mtrl-sci | null | A movable inclusion in an elastic material oscillates as a rigid body with
six degrees of freedom. Displacement/rotation and force/moment tensors which
express the motion of the inclusion in terms of the displacement and force at
arbitrary exterior points are introduced. Using reciprocity arguments two
general identities are derived relating these tensors. Applications of the
identities to spherical particles provide several new results, including simple
expressions for the force and moment on the particle due to plane wave
excitation.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:15:17 GMT"
},
{
"version": "v2",
"created": "Mon, 29 Oct 2007 19:30:09 GMT"
}
] | 2008-01-15T00:00:00 | [
[
"Norris",
"Andrew N.",
""
]
] |
0707.2559 | Ernst Nils Dorband | Denis Pollney, Christian Reisswig, Luciano Rezzolla, Bela Szilagyi,
Marcus Ansorg, Barrett Deris, Peter Diener, Ernst Nils Dorband, Michael
Koppitz, Alessandro Nagar and Erik Schnetter | Recoil velocities from equal-mass binary black-hole mergers: a
systematic investigation of spin-orbit aligned configurations | 24 pages, 15 figures, 5 tables | Phys.Rev.D76:124002,2007 | 10.1103/PhysRevD.76.124002 | null | gr-qc astro-ph | null | Binary black-hole systems with spins aligned with the orbital angular
momentum are of special interest, as studies indicate that this configuration
is preferred in nature. If the spins of the two bodies differ, there can be a
prominent beaming of the gravitational radiation during the late plunge,
causing a recoil of the final merged black hole. We perform an accurate and
systematic study of recoil velocities from a sequence of equal-mass black holes
whose spins are aligned with the orbital angular momentum, and whose individual
spins range from a = +0.584 to -0.584. In this way we extend and refine the
results of a previous study and arrive at a consistent maximum recoil of 448 +-
5 km/s for anti-aligned models as well as to a phenomenological expression for
the recoil velocity as a function of spin ratio. This relation highlights a
nonlinear behavior, not predicted by the PN estimates, and can be readily
employed in astrophysical studies on the evolution of binary black holes in
massive galaxies. An essential result of our analysis is the identification of
different stages in the waveform, including a transient due to lack of an
initial linear momentum in the initial data. Furthermore we are able to
identify a pair of terms which are largely responsible for the kick, indicating
that an accurate computation can be obtained from modes up to l=3. Finally, we
provide accurate measures of the radiated energy and angular momentum, finding
these to increase linearly with the spin ratio, and derive simple expressions
for the final spin and the radiated angular momentum which can be easily
implemented in N-body simulations of compact stellar systems. Our code is
calibrated with strict convergence tests and we verify the correctness of our
measurements by using multiple independent methods whenever possible.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:16:30 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Pollney",
"Denis",
""
],
[
"Reisswig",
"Christian",
""
],
[
"Rezzolla",
"Luciano",
""
],
[
"Szilagyi",
"Bela",
""
],
[
"Ansorg",
"Marcus",
""
],
[
"Deris",
"Barrett",
""
],
[
"Diener",
"Peter",
""
],
[
"Dorband",
"Ernst Nils",
""
],
[
"Koppitz",
"Michael",
""
],
[
"Nagar",
"Alessandro",
""
],
[
"Schnetter",
"Erik",
""
]
] |
0707.2560 | Alessandro Melchiorri dr. | Luca Pagano, Asantha Cooray, Alessandro Melchiorri, Marc Kamionkowski | Red Density Perturbations and Inflationary Gravitational Waves | 4 pages, 2 figures | JCAP 0804:009,2008 | 10.1088/1475-7516/2008/04/009 | null | astro-ph | null | We study the implications of recent indications for a red spectrum of
primordial density perturbations for the detection of inflationary
gravitational waves (IGWs) with forthcoming cosmic microwave background
experiments. We find that if inflation occurs with a single field with an
inflaton potential minimized at V=0, then Planck will be able to detect IGWs at
better than 2$\sigma$ confidence level, unless the inflaton potential is a
power law with a very weak power. The proposed satellite missions of the Cosmic
Vision and Inflation Probe programs will be able to detect IGWs from all the
models we have surveyed at better than 5$\sigma$ confidence level. We provide
an example of what is required if the IGW background is to remain undetected
even by these latter experiments.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:17:49 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Pagano",
"Luca",
""
],
[
"Cooray",
"Asantha",
""
],
[
"Melchiorri",
"Alessandro",
""
],
[
"Kamionkowski",
"Marc",
""
]
] |
0707.2561 | Courtney Lanier Ms | C. H. Lanier, A. van de Walle, N. Erdman, E. Landree, O. Warschkow, A.
Kazimirov, K. R. Poeppelmeier, J. Zegenhagen, M. Asta, L. D. Marks | Atomic-scale structure of the SrTiO3(001)-c(6x2) reconstruction:
Experiments and first-principles calculations | null | null | 10.1103/PhysRevB.76.045421 | null | cond-mat.mtrl-sci | null | The c(6x2) is a reconstruction of the SrTiO3(001) surface that is formed
between 1050-1100oC in oxidizing annealing conditions. This work proposes a
model for the atomic structure for the c(6x2) obtained through a combination of
results from transmission electron diffraction, surface x-ray diffraction,
direct methods analysis, computational combinational screening, and density
functional theory. As it is formed at high temperatures, the surface is complex
and can be described as a short-range ordered phase featuring microscopic
domains composed of four main structural motifs. Additionally, non-periodic
TiO2 units are present on the surface. Simulated scanning tunneling microscopy
images based on the electronic structure calculations are consistent with
experimental images.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:20:13 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Lanier",
"C. H.",
""
],
[
"van de Walle",
"A.",
""
],
[
"Erdman",
"N.",
""
],
[
"Landree",
"E.",
""
],
[
"Warschkow",
"O.",
""
],
[
"Kazimirov",
"A.",
""
],
[
"Poeppelmeier",
"K. R.",
""
],
[
"Zegenhagen",
"J.",
""
],
[
"Asta",
"M.",
""
],
[
"Marks",
"L. D.",
""
]
] |
0707.2562 | Claude Tardif | Benoit Larose, Cynthia Loten, Claude Tardif | A Characterisation of First-Order Constraint Satisfaction Problems | null | Logical Methods in Computer Science, Volume 3, Issue 4 (November
6, 2007) lmcs:1097 | 10.2168/LMCS-3(4:6)2007 | null | cs.LO cs.CC | null | We describe simple algebraic and combinatorial characterisations of finite
relational core structures admitting finitely many obstructions. As a
consequence, we show that it is decidable to determine whether a constraint
satisfaction problem is first-order definable: we show the general problem to
be NP-complete, and give a polynomial-time algorithm in the case of cores. A
slight modification of this algorithm provides, for first-order definable
CSP's, a simple poly-time algorithm to produce a solution when one exists. As
an application of our algebraic characterisation of first order CSP's, we
describe a large family of L-complete CSP's.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:23:45 GMT"
},
{
"version": "v2",
"created": "Tue, 6 Nov 2007 10:18:41 GMT"
}
] | 2015-07-01T00:00:00 | [
[
"Larose",
"Benoit",
""
],
[
"Loten",
"Cynthia",
""
],
[
"Tardif",
"Claude",
""
]
] |
0707.2563 | Vladimir Nikiforov | Vladimir Nikiforov | Stability for large forbidden subgraphs | Some polishing. Updated references | null | null | null | math.CO | null | We extend the classical stability theorem of Erdos and Simonovits for
forbidden graphs of logarithmic order.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:30:35 GMT"
},
{
"version": "v2",
"created": "Thu, 22 Nov 2007 00:19:45 GMT"
}
] | 2007-11-22T00:00:00 | [
[
"Nikiforov",
"Vladimir",
""
]
] |
0707.2564 | Grigori Vartanov | D. I. Kazakov and G. S. Vartanov | Renormalizable 1/N_f Expansion for Field Theories in Extra Dimensions | 32 pages, 20 figures | JHEP 0706:081,2007 | 10.1088/1126-6708/2007/06/081 | null | hep-th hep-ph | null | We demonstrate how one can construct renormalizable perturbative expansion in
formally nonrenormalizable higher dimensional field theories. It is based on
$1/N_f$-expansion and results in a logarithmically divergent perturbation
theory in arbitrary high space-time dimension. First, we consider a simple
example of $N$-component scalar filed theory and then extend this approach to
Abelian and non-Abelian gauge theories with $N_f$ fermions. In the latter case,
due to self-interaction of non-Abelian fields the proposed recipe requires some
modification which, however, does not change the main results. The resulting
effective coupling is dimensionless and is running in accordance with the usual
RG equations. The corresponding beta function is calculated in the leading
order and is nonpolynomial in effective coupling. It exhibits either UV
asymptotically free or IR free behaviour depending on the dimension of
space-time. The original dimensionful coupling plays a role of a mass and is
also logarithmically renormalized. We analyze also the analytical properties of
a resulting theory and demonstrate that in general it acquires several ghost
states with negative and/or complex masses. In the former case, the ghost state
can be removed by a proper choice of the coupling. As for the states with
complex conjugated masses, their contribution to physical amplitudes cancels so
that the theory appears to be unitary.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:31:52 GMT"
}
] | 2009-11-18T00:00:00 | [
[
"Kazakov",
"D. I.",
""
],
[
"Vartanov",
"G. S.",
""
]
] |
0707.2565 | Lyubov' Manakova A. | Yu. Kagan and L. A. Maksimov | Anomalous Hall effect for the phonon heat conductivity in paramagnetic
dielectric | 5 pages; typos and abstract corrected | null | 10.1103/PhysRevLett.100.145902 | null | cond-mat.other | null | The theory of anomalous Hall effect for the heat transfer in a paramagnetic
dielectric, discovered experimentally in [1], is developed. The appearance of
the phonon heat flux normal to both the temperature gradient and the magnetic
field is connected with the interaction of magnetic ions with the crystal field
oscillations. In crystals with an arbitrary phonon spectrum this interaction
creates the elliptical polarization of phonons. The kinetics related to phonon
scattering induced by the spin-phonon interaction determines an origin of the
off-diagonal phonon density matrix. The combination of the both factors is
decisive for the phenomenon under consideration.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:46:29 GMT"
},
{
"version": "v2",
"created": "Fri, 2 Nov 2007 11:07:59 GMT"
},
{
"version": "v3",
"created": "Thu, 15 Nov 2007 08:47:42 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kagan",
"Yu.",
""
],
[
"Maksimov",
"L. A.",
""
]
] |
0707.2566 | Matt Owers | Matt Owers, Chris Blake, Warrick Couch, Mike Pracy, Kenji Bekki | The environments and clustering properties of 2dFGRS-selected starburst
galaxies | 20 pages, 13 figures and 2 tables. Accepted for publication in MNRAS | null | 10.1111/j.1365-2966.2007.12239.x | null | astro-ph | null | We investigate the environments and clustering properties of starburst
galaxies selected from the 2dF Galaxy Redshift Survey (2dFGRS) in order to
determine which, if any, environmental factors play a role in triggering a
starburst. We quantify the local environments, clustering properties and
luminosity functions of our starburst galaxies and compare to random control
samples. The starburst galaxies are also classified morphologically in terms of
their broad Hubble type and evidence of tidal merger/interaction signatures. We
find the starburst galaxies to be much less clustered on large (5-15 Mpc)
scales compared to the overall 2dFGRS galaxy population. In terms of their
environments, we find just over half of the starburst galaxies to reside in low
to intermediate luminosity groups, and a further ~30 per cent residing in the
outskirts and infall regions of rich clusters. Their luminosity functions also
differ significantly from that of the overall 2dFGRS galaxy population, with
the sense of the difference being critically dependent on the way their star
formation rates are measured. In terms of pin-pointing what might trigger the
starburst, it would appear that factors relating to their local environment are
most germane. Specifically, we find clear evidence that the presence of a near
neighbour of comparable luminosity/mass within 20 kpc is likely to be important
in triggering a starburst. We also find that a significant fraction (20-30 per
cent) of our starburst galaxies have morphologies indicative of either an
ongoing or recent tidal interaction and/or merger. These findings
notwithstanding, there remain a significant portion of starburst galaxies where
local environmental influences are not in any obvious way playing a triggering
role, leading us to conclude that starbursts can also be internally driven.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:48:04 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Owers",
"Matt",
""
],
[
"Blake",
"Chris",
""
],
[
"Couch",
"Warrick",
""
],
[
"Pracy",
"Mike",
""
],
[
"Bekki",
"Kenji",
""
]
] |
0707.2567 | Song Ming Wang | CDF Collaboration: T. Aaltonen, et al | Searches for Direct Pair Production of Supersymmetric Top and
Supersymmetric Bottom Quarks in p-pbar Collisions at sqrt(s)=1.96 TeV | 12 pages, 5 figures, submitted to Phys. Rev. D | Phys.Rev.D76:072010,2007 | 10.1103/PhysRevD.76.072010 | FERMILAB-PUB-07-383-E | hep-ex | null | We search for direct pair production of supersymmetric top quarks and
supersymmetric bottom quarks in proton-antiproton collisions at sqrt(s)=1.96
TeV, using 295 pb^-1 of data recorded by the Collider Detector at Fermilab (CDF
II) experiment. The supersymmetric top (supersymmetric bottom) quarks are
selected by reconstructing their decay into a charm (bottom) quark and a
neutralino, which is assumed to be the lightest supersymmetric particle. The
signature of such processes is two energetic heavy-flavor jets and missing
transverse energy. The number of events that pass our selection for each search
process is consistent with the expected standard model background. By comparing
our results to the theoretical production cross sections of the supersymmetric
top and supersymmetric bottom quarks in the minimal supersymmetric standard
model, we exclude, at a 95% confidence level in the frame of that model, a
supersymmetric top quark mass up to 132 GeV/c^2 for a neutralino mass of 48
GeV/c^2, and a supersymmetric bottom quark mass up to 193 GeV/c^2 for a
neutralino mass of 40 GeV/c^2.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 16:54:54 GMT"
},
{
"version": "v2",
"created": "Sat, 8 Sep 2007 20:28:57 GMT"
}
] | 2010-05-12T00:00:00 | [
[
"CDF Collaboration",
"",
""
],
[
"Aaltonen",
"T.",
""
]
] |
0707.2568 | Isamu Iwanari | Isamu Iwanari | Logarithmic geometry, minimal free resolutions and toric algebraic
stacks | the last version | null | null | null | math.AG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we will introduce a certain type of morphisms of log schemes
(in the sense of Fontaine, Illusie, and Kato) and investigate their moduli.
Then by applying this we define a notion of toric algebraic stacks over
arbitrary schemes, which may be regarded as torus embeddings within the
framework of algebraic stacks, and study some basic properties. Furthermore, we
study the stack-theoretic analogue of toroidal embeddings.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 17:07:52 GMT"
},
{
"version": "v2",
"created": "Sat, 29 Aug 2009 15:57:07 GMT"
}
] | 2009-08-29T00:00:00 | [
[
"Iwanari",
"Isamu",
""
]
] |
0707.2569 | Seyed Alireza Ghasemi | S. Alireza Ghasemi, Alexey Neelov and Stefan Goedecker | A Particle-Particle, Particle-Density (P3D) algorithm for the
calculation of electrostatic interactions of particles with slab-like
geometry | It has 19 pages and 4 figures | null | 10.1063/1.2804382 | null | physics.comp-ph physics.chem-ph | null | We present a fast and accurate method to calculate the electrostatic energy
and forces of interacting particles with the boundary conditions appropriate to
surfaces, i.e periodic in the two directions parallel to the surface and free
in the perpendicular direction. In the spirit of the Ewald method the problem
is divided into a short range and long range part. The charge density
responsible for the long range part is represented by plane waves in the
periodic directions and by finite elements in the non-periodic direction. Our
method has computational complexity of O(N_g log(N_g)) with a very small
prefactor, where N_g is the number of grid points.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 17:06:26 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ghasemi",
"S. Alireza",
""
],
[
"Neelov",
"Alexey",
""
],
[
"Goedecker",
"Stefan",
""
]
] |
0707.2570 | Mohamad Ali Jafarizadeh | M. A. Jafarizadeh, R. Sufiani, S. Jafarizadeh | Evaluation of effective resistances in pseudo-distance-regular resistor
networks | 30 pages, 7 figures | null | 10.1088/1751-8113/40/19/002 | null | cond-mat.stat-mech cond-mat.other | null | In Refs.[1] and [2], calculation of effective resistances on distance-regular
networks was investigated, where in the first paper, the calculation was based
on the stratification of the network and Stieltjes function associated with the
network, whereas in the latter one a recursive formula for effective
resistances was given based on the Christoffel-Darboux identity. In this paper,
evaluation of effective resistances on more general networks called
pseudo-distance-regular networks [21] or QD type networks \cite{obata} is
investigated, where we use the stratification of these networks and show that
the effective resistances between a given node such as $\alpha$ and all of the
nodes $\beta$ belonging to the same stratum with respect to $\alpha$
($R_{\alpha\beta^{(m)}}$, $\beta$ belonging to the $m$-th stratum with respect
to the $\alpha$) are the same. Then, based on the spectral techniques, an
analytical formula for effective resistances $R_{\alpha\beta^{(m)}}$ such that
$L^{-1}_{\alpha\alpha}=L^{-1}_{\beta\beta}$ (those nodes $\alpha$, $\beta$ of
the network such that the network is symmetric with respect to them) is given
in terms of the first and second orthogonal polynomials associated with the
network, where $L^{-1}$ is the pseudo-inverse of the Laplacian of the network.
From the fact that in distance-regular networks,
$L^{-1}_{\alpha\alpha}=L^{-1}_{\beta\beta}$ is satisfied for all nodes
$\alpha,\beta$ of the network, the effective resistances
$R_{\alpha\beta^{(m)}}$ for $m=1,2,...,d$ ($d$ is diameter of the network which
is the same as the number of strata) are calculated directly, by using the
given formula.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 17:07:12 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Jafarizadeh",
"M. A.",
""
],
[
"Sufiani",
"R.",
""
],
[
"Jafarizadeh",
"S.",
""
]
] |
0707.2571 | Zachary Dutton | J. Ruostekoski and Zachary Dutton | Dynamical and energetic instabilities in multi-component Bose-Einstein
condensates in optical lattices | 17 pages, 12 figures. Submitted to Phys. Rev. A | Phys. Rev. A 76 (2007) 063607 | 10.1103/PhysRevA.76.063607 | null | cond-mat.other physics.optics quant-ph | null | We study dynamical and energetic instabilities in the transport properties of
Bloch waves for atomic multi-component Bose-Einstein condensates in optical
lattices in the tight-binding limit. We obtain stability criteria analytically,
as a function of superfluid velocities and interaction parameters, in several
cases for two-component and spinor condensates. In the two-species case we find
that the presence of the other condensate component can stabilize the
superfluid flow of an otherwise unstable condensate and that the free space
dynamical miscibility condition of the two species can be reversed by tuning
the superfluid flow velocities. In spin-1 condensates, we find the steady-state
Bloch wave solutions and characterize their stability criteria. We find
generally more regions of dynamical instability arise for the polar than for
the ferromagnetic solutions. In the presence of magnetic Zeeman shifts, we find
a richer variety of condensate solutions and find that the linear Zeeman shift
can stabilize the superfluid flow in several cases of interest.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 17:15:47 GMT"
},
{
"version": "v2",
"created": "Thu, 9 Aug 2007 16:42:35 GMT"
},
{
"version": "v3",
"created": "Thu, 9 Aug 2007 20:06:19 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ruostekoski",
"J.",
""
],
[
"Dutton",
"Zachary",
""
]
] |
0707.2572 | Horacio Wio | Jorge A. Revelli, Miguel A. Rodriguez and Horacio S. Wio (IFCA, Spain) | Noise effects in extended chaotic system: study on the Lorenz'96 model | To appear in Statistical Mechanics Research Focus, Special volume
(Nova Science Pub., NY, in press) (LaTex, 16 pgs, 14 figures) | null | null | null | nlin.CD cond-mat.stat-mech nlin.PS physics.ao-ph | null | We investigate the effects of a time-correlated noise on an extended chaotic
system. The chosen model is the Lorenz'96, a kind of toy model used for climate
studies. The system is subjected to both temporal and spatiotemporal
perturbations. Through the analysis of the system's time evolution and its time
correlations, we have obtained numerical evidence for two stochastic
resonance-like behaviors. Such behavior is seen when a generalized
signal-to-noise ratio function are depicted as a function of the external noise
intensity or as function of the system size. The underlying mechanism seems to
be associated to a noise-induced chaos reduction. The possible relevance of
those findings for an optimal climate prediction are discussed, using an
analysis of the noise effects on the evolution of finite perturbations and
errors.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 17:17:50 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Revelli",
"Jorge A.",
"",
"IFCA, Spain"
],
[
"Rodriguez",
"Miguel A.",
"",
"IFCA, Spain"
],
[
"Wio",
"Horacio S.",
"",
"IFCA, Spain"
]
] |
0707.2573 | F\`elix Campelo | F. Campelo and A. Hernandez-Machado | Model for curvature-driven pearling instability in membranes | Accepted for publication in Phys. Rev. Lett | Phys. Rev. Lett. 99, 088101 (2007) | 10.1103/PhysRevLett.99.088101 | null | q-bio.QM cond-mat.soft q-bio.CB | null | A phase-field model for dealing with dynamic instabilities in membranes is
presented. We use it to study curvature-driven pearling instability in vesicles
induced by the anchorage of amphiphilic polymers on the membrane. Within this
model, we obtain the morphological changes reported in recent experiments. The
formation of a homogeneous pearled structure is achieved by consequent pearling
of an initial cylindrical tube from the tip. For high enough concentration of
anchors, we show theoretically that the homogeneous pearled shape is
energetically less favorable than an inhomogeneous one, with a large sphere
connected to an array of smaller spheres.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 17:22:16 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Campelo",
"F.",
""
],
[
"Hernandez-Machado",
"A.",
""
]
] |
0707.2574 | J. E. Thomas | A. Turlapov, J. Kinast, B. Clancy, Le Luo, J. Joseph and J. E. Thomas | Is a gas of strongly interacting atomic fermions a nearly perfect fluid? | 10 pages, 5 figures | null | 10.1007/s10909-007-9589-1 | null | cond-mat.other | null | We use all-optical methods to produce a highly-degenerate Fermi gas of
spin-1/2 $^6$Li atoms. A magnetic field tunes the gas near a collisional
(Feshbach) resonance, producing strong interactions between spin-up and
spin-down atoms. This atomic gas is a paradigm for strong interactions in
nature, and provides tests of current quantum many-body calculational methods
for diverse systems, including very high temperature superconductors, nuclear
matter in neutron stars, and the quark-gluon plasma of the Big Bang. We have
measured properties of a breathing mode over a wide range of temperatures. At
temperatures both below and well above the superfluid transition, the frequency
of the mode is nearly constant and very close to the hydrodynamic value.
However, explaining both the frequency and the damping rate in the normal
collisional regime has not been achieved. Our measurements of the damping rate
as a function of the energy of the gas are used to estimate an upper bound on
the viscosity. Using our new measurements of the entropy of the gas, we
estimate the ratio of the shear viscosity to the entropy density, and compare
the result with the lower bound for quantum viscosity recently predicted using
string theory methods.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 17:23:03 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Turlapov",
"A.",
""
],
[
"Kinast",
"J.",
""
],
[
"Clancy",
"B.",
""
],
[
"Luo",
"Le",
""
],
[
"Joseph",
"J.",
""
],
[
"Thomas",
"J. E.",
""
]
] |
0707.2575 | Reghan Hill J | Reghan J. Hill and Martin Ostoja-Starzewski | Electric-field-induced displacement of a charged spherical colloid
embedded in an elastic Brinkman medium | null | null | 10.1103/PhysRevE.77.011404 | null | cond-mat.soft cond-mat.mtrl-sci | null | When an electric field is applied to an electrolyte-saturated polymer gel
embedded with charged colloidal particles, the force that must be exerted by
the hydrogel on each particle reflects a delicate balance of electrical,
hydrodynamic and elastic stresses. This paper examines the displacement of a
single charged spherical inclusion embedded in an uncharged hydrogel. We
present numerically exact solutions of coupled electrokinetic transport and
elastic-deformation equations, where the gel is treated as an incompressible,
elastic Brinkman medium. This model problem demonstrates how the displacement
depends on the particle size and charge, the electrolyte ionic strength, and
Young's modulus of the polymer skeleton. The numerics are verified, in part,
with an analytical (boundary-layer) theory valid when the Debye length is much
smaller than the particle radius. Further, we identify a close connection
between the displacement when a colloid is immobilized in a gel and its
velocity when dispersed in a Newtonian electrolyte. Finally, we describe an
experiment where nanometer-scale displacements might be accurately measured
using back-focal-plane interferometry. The purpose of such an experiment is to
probe physicochemical and rheological characteristics of hydrogel composites,
possibly during gelation.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 17:57:43 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Hill",
"Reghan J.",
""
],
[
"Ostoja-Starzewski",
"Martin",
""
]
] |
0707.2576 | Maksim Maydanskiy | Maksim Maydanskiy | A note on the incidence coloring of outerplanar graphs | added reference to bounds for planar and higher genus graphs | null | null | null | math.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A proof that every outerplanar graph is \Delta+2 colorable. This is slightly
stronger then an unpublished result of Wang Shudong, Ma Fangfang, Xu Jin, and
Yan Lijun proving the same for 2-connected outerplanar graphs.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 17:40:19 GMT"
},
{
"version": "v2",
"created": "Thu, 19 Jun 2008 19:46:08 GMT"
}
] | 2008-06-19T00:00:00 | [
[
"Maydanskiy",
"Maksim",
""
]
] |
0707.2577 | Kazimierz St{\ke}pie\'n | M. Kiraga and K. Stepien (Warsaw University Observatory, Warszawa,
Poland) | Age-Rotation-Activity Relations for M Dwarf Stars Based on ASAS
Photometric Data | 20 pages | Acta Astron.57:149-172,2007 | null | null | astro-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Based on analysis of photometric observations of nearby M type stars obtained
with ASAS, 31 periodic variables were detected. The determined periods are
assumed to be related to rotation periods of the investigated stars. Among them
10 new variables with periods longer than 10 days were found, which brings the
total number of slowly rotating M stars with known rotation periods to 12
objects.
X-ray activity and rotation evolution of M stars follows the trends observed
in G-K type stars. Rapidly rotating stars are very active and activity
decreases with increasing rotation period but the period-activity relation is
mass-dependent which suggests that the rotation period alone is not a proper
measure of activity. The investigated stars were grouped according to their
mass and the empirical turnover time was determined for each group. It
increases with decreasing mass more steeply than for K type stars for which a
flat dependence had been found. The resulting Rossby number-activity relation
shows an exponential decrease of activity with increasing Rossby number.
The analysis of space motions of 27 single stars showed that all rapidly
rotating and a few slowly rotating stars belong to young disk (YD) whereas all
old disk (OD) stars are slowly rotating. The median rotation period of YD stars
is about 2 days and that of OD stars is equal to 47 days, i.e. nearly 25 times
longer. The average X-ray flux of OD stars is about 1.7 dex lower than YD stars
in a good agreement with the derived Rossby number-activity formula
supplemented with rotation-age relation and in a fair agreement with recent
observations but in a disagreement with the Skumanich formula supplemented with
the activity-rotation relation.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 10:24:08 GMT"
},
{
"version": "v2",
"created": "Fri, 13 May 2011 07:28:41 GMT"
}
] | 2011-05-16T00:00:00 | [
[
"Kiraga",
"M.",
"",
"Warsaw University Observatory, Warszawa,\n Poland"
],
[
"Stepien",
"K.",
"",
"Warsaw University Observatory, Warszawa,\n Poland"
]
] |
0707.2578 | Barry Simon | Barry Simon | Weak convergence of CD kernels and applications | null | null | null | null | math.SP math-ph math.MP | null | We prove a general result on equality of the weak limits of the zero counting
measure, $d\nu_n$, of orthogonal polynomials (defined by a measure $d\mu$) and
$\frac{1}{n} K_n(x,x) d\mu(x)$. By combining this with Mate--Nevai and Totik
upper bounds on $n\lambda_n(x)$, we prove some general results on $\int_I
\frac{1}{n} K_n(x,x) d\mu_s\to 0$ for the singular part of $d\mu$ and $\int_I
|\rho_E(x) - \frac{w(x)}{n} K_n(x,x)| dx\to 0$, where $\rho_E$ is the density
of the equilibrium measure and $w(x)$ the density of $d\mu$.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 17:51:38 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Simon",
"Barry",
""
]
] |
0707.2579 | Marcelo Sarandy | M. S. Sarandy, E. I. Duzzioni, M. H. Y. Moussa | Dynamical invariants and nonadiabatic geometric phases in open quantum
systems | 9 pages, 3 figures. v2: minor corrections and subsection IV.D added.
Published version | Phys. Rev. A 76, 052112 (2007) | 10.1103/PhysRevA.76.052112 | null | quant-ph cond-mat.stat-mech hep-th | null | We introduce an operational framework to analyze non-adiabatic Abelian and
non-Abelian, cyclic and non-cyclic, geometric phases in open quantum systems.
In order to remove the adiabaticity condition, we generalize the theory of
dynamical invariants to the context of open systems evolving under arbitrary
convolutionless master equations. Geometric phases are then defined through the
Jordan canonical form of the dynamical invariant associated with the
super-operator that governs the master equation. As a by-product, we provide a
sufficient condition for the robustness of the phase against a given decohering
process. We illustrate our results by considering a two-level system in a
Markovian interaction with the environment, where we show that the
non-adiabatic geometric phase acquired by the system can be constructed in such
a way that it is robust against both dephasing and spontaneous emission.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 17:54:55 GMT"
},
{
"version": "v2",
"created": "Sun, 27 Jan 2008 20:18:40 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sarandy",
"M. S.",
""
],
[
"Duzzioni",
"E. I.",
""
],
[
"Moussa",
"M. H. Y.",
""
]
] |
0707.2580 | Patrice Martinez | P. Martinez, A. Boccaletti, M. Kasper, P. Baudoz and C. Cavarroc | Optimization of Apodized Pupil Lyot Coronagraph for ELTs | 9 pages, 17 figures, accepted for publication in Astronomy &
Astrophysics | null | 10.1051/0004-6361:20077708 | null | astro-ph | null | We study the optimization of the Apodized Pupil Lyot Coronagraph (APLC) in
the context of exoplanet imaging with ground-based telescopes. The APLC
combines an apodization in the pupil plane with a small Lyot mask in the focal
plane of the instrument. It has been intensively studied in the literature from
a theoretical point of view, and prototypes are currently being manufactured
for several projects. This analysis is focused on the case of Extremely Large
Telescopes, but is also relevant for other telescope designs.
We define a criterion to optimize the APLC with respect to telescope
characteristics like central obscuration, pupil shape, low order segment
aberrations and reflectivity as function of the APLC apodizer function and mask
diameter. Specifically, the method was applied to two possible designs of the
future European-Extremely Large Telescope (E-ELT).
Optimum configurations of the APLC were derived for different telescope
characteristics. We show that the optimum configuration is a stronger function
of central obscuration size than of other telescope parameters. We also show
that APLC performance is quite insensitive to the central obscuration ratio
when the APLC is operated in its optimum configuration, and demonstrate that
APLC optimization based on throughput alone is not appropriate.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 19:59:45 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Martinez",
"P.",
""
],
[
"Boccaletti",
"A.",
""
],
[
"Kasper",
"M.",
""
],
[
"Baudoz",
"P.",
""
],
[
"Cavarroc",
"C.",
""
]
] |
0707.2581 | Reghan Hill J | Reghan J. Hill | Electric-field-enhanced transport in polyacrylamide hydrogel
nano-composites | null | null | null | null | cond-mat.soft cond-mat.mtrl-sci | null | Electroosmotic pumping through uncharged hydrogels can be achieved by
embedding the polymer network with charged colloidal inclusions. Matos and
co-workers (2006) recently used the concept to enhance the diffusion-limited
flux of uncharged molecules across polyacrylamide hydrogel membraness for the
purpose of improving the performance of biosensors. This paper seeks to link
their reported macroscale diagnostics to physicochemical characteristics of the
composite microstructure. A mathematical model for the bulk electroosmotically
enhanced tracer flux is proposed, which is combined with the electrokinetic
model to ascertain the electroosmotic pumping velocity from measured flux
enhancements. Because the experiments are performed with a known current
density, but unknown bulk conductivity and electric field strength, theoretical
estimates of the bulk electrical conductivity are adopted. These account for
nano-particle polarization, added counterions, and non-specific adsorption.
Theoretical predictions of the flux enhancement, achieved without any fitting
parameters, are within a factor of two of the experiments. Alternatively, if
the Brinkman screening length of the polymer skeleton is treated as a fitting
parameter, then the best-fit values are bounded by the range 0.9-1.6 nm,
depending on the inclusion size and volume fraction. Independent
pressure-driven flow experiments reported in the literature for polyacrylamide
gels without inclusions suggest 0.4 or 0.8 nm. The comparison can be improved
by allowing for hindered ion migration, while uncertainties regarding the
inclusion surface charge are demonstrated to have a negligible influence on the
electroosmotic flow.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 18:47:39 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Hill",
"Reghan J.",
""
]
] |
0707.2582 | Guido Germano | Daniel Fulger, Enrico Scalas, Guido Germano | Monte Carlo simulation of uncoupled continuous-time random walks
yielding a stochastic solution of the space-time fractional diffusion
equation | 7 pages, 5 figures, 1 table. Presented at the Conference on Computing
in Economics and Finance in Montreal, 14-16 June 2007; at the conference
"Modelling anomalous diffusion and relaxation" in Jerusalem, 23-28 March
2008; etc | Physical Review E 77 (2), 021122:1-7, 2008 | 10.1103/PhysRevE.77.021122 | null | cond-mat.stat-mech | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a numerical method for the Monte Carlo simulation of uncoupled
continuous-time random walks with a Levy alpha-stable distribution of jumps in
space and a Mittag-Leffler distribution of waiting times, and apply it to the
stochastic solution of the Cauchy problem for a partial differential equation
with fractional derivatives both in space and in time. The one-parameter
Mittag-Leffler function is the natural survival probability leading to
time-fractional diffusion equations. Transformation methods for Mittag-Leffler
random variables were found later than the well-known transformation method by
Chambers, Mallows, and Stuck for Levy alpha-stable random variables and so far
have not received as much attention; nor have they been used together with the
latter in spite of their mathematical relationship due to the geometric
stability of the Mittag-Leffler distribution. Combining the two methods, we
obtain an accurate approximation of space- and time-fractional diffusion
processes almost as easy and fast to compute as for standard diffusion
processes.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 18:49:50 GMT"
},
{
"version": "v2",
"created": "Mon, 9 Mar 2009 19:53:30 GMT"
}
] | 2013-03-19T00:00:00 | [
[
"Fulger",
"Daniel",
""
],
[
"Scalas",
"Enrico",
""
],
[
"Germano",
"Guido",
""
]
] |
0707.2583 | Eugene Lim | Richard Easther, Eugene A. Lim | The Eternal Sunshine of the Spotless Mind | 18 pages, 5 figures | JCAP 0801:012,2008 | 10.1088/1475-7516/2008/01/012 | null | hep-th | null | We extend the worldline measure for pocket formation in eternal inflation to
allow for time-ordered bubble formation. Such a time-ordering is equivalent to
imposing a preferred time-slicing on the "parent" de Sitter space. Using this
measure, we describe a covariant version of the youngness paradox and show that
the youngness paradox is a gauge artifact if the parent spacetime is an
unbroken de Sitter space, due to the lack of an explicit time-ordering for the
bubble nucleation events. We then show that one can add a "clock" to the de
Sitter space, in the form of a vector field with a spontaneously broken
symmetry that defines a unique timelike direction accessible to all observers.
Once this is done, the existence of a preferred slicing means that the
youngness paradox cannot be easily resolved. We use this to elucidate the
apparent "persistence of memory" discussed recently by Garriga, Guth and
Vilenkin, for inflationary universes produced by bubble nucleation.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 18:38:28 GMT"
},
{
"version": "v2",
"created": "Fri, 21 Sep 2007 00:53:40 GMT"
}
] | 2009-11-18T00:00:00 | [
[
"Easther",
"Richard",
""
],
[
"Lim",
"Eugene A.",
""
]
] |
0707.2584 | Florentin Smarandache | Florentin Smarandache | Six Conjectures which Generalize or Are Related to Andrica's Conjecture | 3 pages | Octogon, Vol. 7, No. 1, 173-176, 1999 | null | null | math.GM | null | Six conjectures on pairs of consecutive primes are listed in this paper,
together with examples for each case.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 18:35:11 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Smarandache",
"Florentin",
""
]
] |
0707.2585 | Gunnar Carlsson | Gunnar Carlsson | Derived completions in stable homotopy theory | 33 pages | null | null | null | math.AT math.AC | null | We construct a notion of derived completion which applies to homomorphisms of
commutative S-algebras. We study the relationship of the construction with
other constructions of completions, and prove various invariance properties.
The construction is expected to have applications within algebraic K-theory.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 18:18:11 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Carlsson",
"Gunnar",
""
]
] |
0707.2586 | Konstantin Parchevsky | K. V. Parchevsky, A. G. Kosovichev | Effect of suppressed excitation on the amplitude distribution of 5-min
oscillations in sunspots | 12 pages, 5 figures, accepted to ApJL | null | 10.1086/521602 | null | astro-ph | null | Five-minute oscillations on the Sun (acoustic and surface gravity waves) are
excited by subsurface turbulent convection. However, in sunspots the excitation
is suppressed because strong magnetic field inhibits convection. We use 3D
simulations to investigate how the suppression of excitation sources affects
the distribution of the oscillation power in sunspot regions. The amplitude of
random acoustic sources was reduced in circular-shaped regions to simulate the
suppression in sunspots. The simulation results show that the amplitude of the
oscillations can be approximately 2-4 times lower in the sunspot regions in
comparison to the quiet Sun, just because of the suppressed sources. Using
SOHO/MDI data we measured the amplitude ratio for the same frequency bands
outside and inside sunspots, and found that this ratio is approximately 3-4.
Hence, the absence of excitation sources inside sunspots makes a significant
contribution (about 50% or higher) to the observed amplitude ratio and must be
taken into account in sunspot seismology.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 18:51:14 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Parchevsky",
"K. V.",
""
],
[
"Kosovichev",
"A. G.",
""
]
] |
0707.2587 | Jose A. Cuesta | J. A. Cuesta, R. Jimenez, H. Lugo and A. Sanchez | The Shared Reward Dilemma | Major rewriting, new appendix, new figures | Journal of Theoretical Biology 251, 253-263 (2008) | 10.1016/j.jtbi.2007.11.022 | null | q-bio.PE | null | One of the most direct human mechanisms of promoting cooperation is rewarding
it. We study the effect of sharing a reward among cooperators in the most
stringent form of social dilemma, namely the Prisoner's Dilemma. Specifically,
for a group of players that collect payoffs by playing a pairwise Prisoner's
Dilemma game with their partners, we consider an external entity that
distributes a fixed reward equally among all cooperators. Thus, individuals
confront a new dilemma: on the one hand, they may be inclined to choose the
shared reward despite the possibility of being exploited by defectors; on the
other hand, if too many players do that, cooperators will obtain a poor reward
and defectors will outperform them. By appropriately tuning the amount to be
shared a vast variety of scenarios arises, including traditional ones in the
study of cooperation as well as more complex situations where unexpected
behavior can occur. We provide a complete classification of the equilibria of
the $n$-player game as well as of its evolutionary dynamics.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 19:00:47 GMT"
},
{
"version": "v2",
"created": "Mon, 26 Nov 2007 09:13:09 GMT"
}
] | 2012-02-02T00:00:00 | [
[
"Cuesta",
"J. A.",
""
],
[
"Jimenez",
"R.",
""
],
[
"Lugo",
"H.",
""
],
[
"Sanchez",
"A.",
""
]
] |
0707.2588 | Zhaoqing Feng | Zhao-Qing Feng, Gen-Ming Jin, Jun-Qing Li, Werner Scheid | Formation of superheavy nuclei in cold fusion reactions | 18 pages, 8 figures | Phys.Rev.C76:044606,2007 | 10.1103/PhysRevC.76.044606 | null | nucl-th | null | Within the concept of the dinuclear system (DNS), a dynamical model is
proposed for describing the formation of superheavy nuclei in complete fusion
reactions by incorporating the coupling of the relative motion to the nucleon
transfer process. The capture of two heavy colliding nuclei, the formation of
the compound nucleus and the de-excitation process are calculated by using an
empirical coupled channel model, solving a master equation numerically and
applying statistical theory, respectively. Evaporation residue excitation
functions in cold fusion reactions are investigated systematically and compared
with available experimental data. Maximal production cross sections of
superheavy nuclei in cold fusion reactions with stable neutron-rich projectiles
are obtained. Isotopic trends in the production of the superheavy elements
Z=110, 112, 114, 116, 118 and 120 are analyzed systematically. Optimal
combinations and the corresponding excitation energies are proposed.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 19:10:10 GMT"
},
{
"version": "v2",
"created": "Wed, 18 Jul 2007 14:37:08 GMT"
},
{
"version": "v3",
"created": "Thu, 19 Jul 2007 14:15:05 GMT"
},
{
"version": "v4",
"created": "Wed, 17 Oct 2007 08:24:52 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Feng",
"Zhao-Qing",
""
],
[
"Jin",
"Gen-Ming",
""
],
[
"Li",
"Jun-Qing",
""
],
[
"Scheid",
"Werner",
""
]
] |
0707.2589 | Matthias Steinhauser | Johann H. Kuhn, Matthias Steinhauser, Thomas Teubner | Determination of the strong coupling constant from the CLEO measurement
of the total hadronic cross section in $e^+e^-$ annihilation below 10.56 GeV | 7 pages | Phys.Rev.D76:074003,2007 | 10.1103/PhysRevD.76.074003 | LTH 749, SFB/CPP-07-36, TTP07-16 | hep-ph | null | Using recent CLEO III results for the cross section for $e^+e^- \to {\rm
hadrons}$ at seven centre-of-mass energies between 6.964 and 10.538 GeV, we
derive a value for the strong coupling constant
$\alpha_s(M_Z^2)=0.110_{-0.012}^{-0.010}{}_{-0.011}^{+0.010}$ where the
uncertainties are uncorrelated and correlated, respectively. Our result differs
significantly from the one derived by CLEO III, as a consequence of inclusion
of quark mass effects and the proper matching between the effective theories
with four and five flavours. Combining this new result with an analysis based
on earlier cross section measurements in the energy region between 2 and 10.6
GeV, we obtain $\alpha_s(M_Z^2)=0.119^{+0.009}_{-0.011}$, well consistent with
the current world average.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 19:18:02 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kuhn",
"Johann H.",
""
],
[
"Steinhauser",
"Matthias",
""
],
[
"Teubner",
"Thomas",
""
]
] |
0707.2590 | Fernando T. C. Brandt | F. T. Brandt, J. Frenkel and D. G. C. McKeon | General Covariant Gauge Fixing for Massless Spin-Two Fields | 8 pages, 4 figures. Revised version to be published in Physical
Review D | Phys.Rev.D76:105029,2007 | 10.1103/PhysRevD.76.105029 | null | hep-th | null | The most general covariant gauge fixing Lagrangian is considered for a
spin-two gauge theory in the context of the Faddeev-Popov procedure. In
general, five parameters characterize this gauge fixing. Certain limiting
values for these parameters give rise to a spin-two propagator that is either
traceless or transverse, but for no values of these parameters is this
propagator simultaneously traceless and transverse. Having a
traceless-transverse (TT) propagator ensures that only the physical degrees of
freedom associated with the tensor field propagate, and hence it is analogous
to the Landau gauge in electrodynamics. To obtain such a traceless-transverse
propagator, a gauge fixing Lagrangian which is not quadratic must be employed;
this sort of gauge fixing Lagrangian is not encountered in the usual
Faddeev-Popov procedure. It is shown that when this non-quadratic gauge fixing
Lagrangian is used, two Fermionic and one Bosonic ghost arise. As a simple
application we discuss the energy-momentum tensor of the gravitational field at
finite temperature.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 19:17:55 GMT"
},
{
"version": "v2",
"created": "Fri, 28 Sep 2007 20:20:50 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Brandt",
"F. T.",
""
],
[
"Frenkel",
"J.",
""
],
[
"McKeon",
"D. G. C.",
""
]
] |
0707.2591 | Nathan Grigg | Nathan Grigg and Nathan Manwaring | An Elementary Proof of the Fundamental Theorem of Tropical Algebra | 8 pages | null | null | null | math.CO | null | In this paper we give an elementary proof of the Fundamental Theorem of
Algebra for polynomials over the rational tropical semi-ring. We prove that,
tropically, the rational numbers are algebraically closed. We provide a simple
algorithm for factoring tropical polynomials of a single variable. A central
idea is the concept of least-coefficient polynomials as representatives for
classes of functionally equivalent polynomials. This idea has importance far
beyond the proof of the Fundamental Theorem of Tropical Algebra.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 19:43:50 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Grigg",
"Nathan",
""
],
[
"Manwaring",
"Nathan",
""
]
] |
0707.2592 | Konrad Swanepoel | Horst Martini, Konrad J Swanepoel and Gunter Weiss | The Fermat-Torricelli problem in normed planes and spaces | null | J. Optim. Theory Appl. 115 (2002), no. 2, 283--314 | 10.1023/A:1020884004689 | null | math.OC math.MG | null | We investigate the Fermat-Torricelli problem in d-dimensional real normed
spaces or Minkowski spaces, mainly for d=2. Our approach is to study the
Fermat-Torricelli locus in a geometric way. We present many new results, as
well as give an exposition of known results that are scattered in various
sources, with proofs for some of them. Together, these results can be
considered to be a minitheory of the Fermat-Torricelli problem in Minkowski
spaces and especially in Minkowski planes. This demonstrates that substantial
results about locational problems valid for all norms can be found using a
geometric approach.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 19:59:39 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Jul 2007 20:03:46 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Martini",
"Horst",
""
],
[
"Swanepoel",
"Konrad J",
""
],
[
"Weiss",
"Gunter",
""
]
] |
0707.2593 | Max Tegmark | Max Tegmark (MIT) | Many lives in many worlds | Nature version with better graphics at
http://www.nature.com/nature/journal/v448/n7149/full/448023a.html Everett bio
and other links at http://space.mit.edu/home/tegmark/quantum.html | Nature 448:23,2007 | 10.1038/448023a | null | quant-ph hep-th | null | I argue that accepting quantum mechanics to be universally true means that
you should also believe in parallel universes. I give my assessment of
Everett's theory as it celebrates its 50th anniversary.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 18:59:12 GMT"
}
] | 2009-10-07T00:00:00 | [
[
"Tegmark",
"Max",
"",
"MIT"
]
] |
0707.2594 | Hsiao-Wen Chen | Hsiao-Wen Chen (U Chicago), Jason X. Prochaska (UCO/Lick Observatory)
and Nickolay Y. Gnedin (Fermilab) | A New Constraint on the Escape Fraction in Distant Galaxies Using
Gamma-ray Burst Afterglow Spectroscopy | Five journal pages, including one figure; ApJL in press | Astrophys.J.667:L125-L128,2007 | 10.1086/522306 | null | astro-ph | null | We describe a new method to measure the escape fraction fesc of ionizing
radiation from distant star-forming galaxies using the afterglow spectra of
long-duration gamma-ray bursts (GRBs). Optical spectra of GRB afterglows allow
us to evaluate the optical depth of the host ISM, according to the neutral
hydrogen column density N(HI) observed along the sightlines toward the
star-forming regions where the GRBs are found. Different from previous effort
in searching for faint, transmitted Lyman continuum photons, our method is not
subject to background subtraction uncertainties and does not require prior
knowledge of either the spectral shape of the host galaxy population or the IGM
Lya forest absorption along these GRB sightlines. Because most GRBs occur in
sub-L_* galaxies, our study also offers the first constraint on fesc for
distant low-mass galaxies that dominate the cosmic luminosity density. We have
compiled a sample of 27 GRBs at redshift z>2 for which the underlying N(HI) in
the host ISM are known. These GRBs together offer a statistical sampling of the
integrated optical depth to ionizing photons along random sightlines from
star-forming regions in the host galaxies, and allow us to estimate the mean
escape fraction <fesc> averaged over different viewing angles. We find
<fesc>=0.02\pm 0.02 and place a 95% c.l. upper limit <fesc> <= 0.075 for these
hosts. We discuss possible biases of our approach and implications of the
result. Finally, we propose to extend this technique for measuring <fesc> at
z~0.2 using spectra of core-collapse supernovae.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 20:01:29 GMT"
},
{
"version": "v2",
"created": "Mon, 13 Aug 2007 22:26:56 GMT"
}
] | 2010-11-11T00:00:00 | [
[
"Chen",
"Hsiao-Wen",
"",
"U Chicago"
],
[
"Prochaska",
"Jason X.",
"",
"UCO/Lick Observatory"
],
[
"Gnedin",
"Nickolay Y.",
"",
"Fermilab"
]
] |
0707.2595 | Vladimir Privman | Vladimir Privman | Mechanisms of Diffusional Nucleation of Nanocrystals and Their
Self-Assembly into Uniform Colloids | 26 pages in PDF, including 5 figures | Ann. N.Y. Acad. Sci. 1161, 508-525 (2009) | 10.1111/j.1749-6632.2008.04323.x | null | cond-mat.soft cond-mat.dis-nn cond-mat.mtrl-sci cond-mat.stat-mech | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We survey our research on modeling the mechanisms of control of uniformity in
growth of nanosize and colloid particles. The former are produced as
nanocrystals, by burst-nucleation from solution. The latter, colloid-size
particles, are formed by self-assembly (aggregation) of the nanocrystals. In
the colloid particle synthesis, the two dynamical processes are coupled, and
both are governed by diffusional transport of the respective building blocks
(monomers). The interrelation of the two processes allows for synthesis of
narrow size distribution colloid dispersions which are of importance in many
applications.
We first review a mathematical model of diffusive cluster growth by capture
of monomer "singlets." Burst nucleation of nanoparticles in solution is then
analyzed. Finally, we couple it to the secondary process of aggregation of
nanoparticles to form colloids, and we discuss various aspects of the modeling
of particle size distribution, as well as other features of the processes
considered.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 20:08:53 GMT"
},
{
"version": "v2",
"created": "Sat, 22 Dec 2007 01:00:29 GMT"
},
{
"version": "v3",
"created": "Mon, 30 Jun 2008 03:32:09 GMT"
}
] | 2010-10-12T00:00:00 | [
[
"Privman",
"Vladimir",
""
]
] |
0707.2596 | Alexander Burin L | A. L. Burin, I. Ya. Polishchuk | Effect of triple interaction on energy delocalization in the strongly
disordered system of interacting two-level defects | 4 pages, 1 figure | null | null | null | cond-mat.dis-nn cond-mat.soft | null | We accurately treat the effect of the double and triple interactions of
two-level systems (TLS) in glasses onto the energy delocalization due to the
long-range interaction of TLS. Although this work qualitatively reproduces the
estimates of our previous work we believe that it is important because in this
paper the estimates are done with quantitative accuracy. This work can serve as
the important step towards the development of quantitative theory of many-body
delocalization due to the long-range interaction. Our study is compared with
the recent work by Bodea et al claiming that the interaction of TLS triples
leads to the energy delocalization. We cannot agree with the mentioned work
because as we show the interaction of TLS triples was overestimated there and
therefore the result for the TLS relaxation rate obtained there is invalid.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 20:18:49 GMT"
}
] | 2007-07-19T00:00:00 | [
[
"Burin",
"A. L.",
""
],
[
"Polishchuk",
"I. Ya.",
""
]
] |
0707.2597 | Edward Pope | Edward C. D. Pope | Rapidly varying accretion and AGN feedback | Accepted for publication in MNRAS letters. 6 pages, 2 figures | null | 10.1111/j.1365-2966.2007.12443.x | null | astro-ph | null | Accretion rates onto AGN are likely to be extremely variable on short
timescales; much shorter than the typical cooling time of X-ray emitting gas in
elliptical galaxies and galaxy clusters. Using the Langevin approach it is
shown that, for a simple feedback system, this can induce variability in the
AGN power output that is of much larger amplitude, and persists for longer
timescales, than the initial fluctuations. An implication of this is that rich
galaxy clusters are expected to show the largest and longest-lived
fluctuations. Stochastic variations in the accretion rate also mean that the
AGN injects energy across a wide range of timescales. This allows the AGN to
maintain a much closer balance with its surroundings than if it was
periodically activated. The possible non-linear correlation between Bondi
accretion rate and jet power, found by Allen et al 2006, can be explained if
the instantaneous accretion rate, scaled by jet power, varies log-normally.
This explanation also implies that the duty cycle of AGN activity increases
with the radiative losses of the surroundings, in qualitative agreement with
Best et al 2005.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 20:30:11 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Pope",
"Edward C. D.",
""
]
] |
0707.2598 | Hideyuki Umeda | Hideyuki Umeda, Ken'ichi Nomoto | How much 56Ni can be produced in Core-Collapse Supernovae? : Evolution
and Explosions of 30 - 100 Msun Stars | 13 pages, 7 figures, accepted for publication in ApJ | null | 10.1086/524767 | null | astro-ph | null | Motivated by the discovery of extremely bright supernovae SNe1999as and
2006gy, we have investigated how much 56Ni mass can be synthesized in
core-collapse massive supernovae (SNe). We calculate the evolution of several
very massive stars with initial masses M <~ 100 Msun from the main-sequence to
the beginning of the Fe-core collapse and simulate their explosions and
nucleosynthesis. In order to avoid complications associated with strong
mass-loss, we only consider metal-poor stars with initial metallicity Z =
Zsun/200. However, our results are applicable to higher metallicity models with
similar C+O core masses. The C+O core mass for the 100Msun model is M_CO =
42.6Msun and this is the heaviest model in the literature for which Fe-core
collapse SN is explored. The synthesized 56Ni mass increases with the
increasing explosion energy and progenitor mass. For the explosion energy of
E_51 = E/10^{51} erg =30, for example, the 56Ni masses of M(56Ni) = 2.2, 2.3,
5.0, and 6.6 Msun can be produced for the progenitors with initial masses of
30, 50, 80 and 100 Msun (or C+O core masses M_CO = 11.4, 19.3, 34.0 and 42.6
Msun), respectively. We find that producing M(56Ni) ~ 4Msun as seen in SN1999as
is possible for M_CO >~ 34 Msun and E_{51} >~ 20. Producing M(56Ni) ~ 13Msun as
suggested for SN2006gy requires a too large explosion energy for M_CO <~
43Msun, but it may be possible with a reasonable explosion energy if M_CO >~
60Msun.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 20:31:58 GMT"
},
{
"version": "v2",
"created": "Mon, 22 Oct 2007 04:26:37 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Umeda",
"Hideyuki",
""
],
[
"Nomoto",
"Ken'ichi",
""
]
] |
0707.2599 | Sergio A. Cellone | Sergio A. Cellone (1), Gustavo E. Romero (1 and 2), Jorge A. Combi (2
and 3), Josep Marti (3) ((1) Facultad de Ciencias Astronomicas y Geofisicas,
Universidad Nacional de La Plata, Argentina, (2) Inst. Argentino de
Radioastronomia, (3) Universidad de Jaen, Spain) | Extreme photo-polarimetric behaviour of the blazar AO 0235+164 | Accepted by MNRAS (Letters), 5 pages | MNRAS (Letters) 381 (2007) L60-L64. | 10.1111/j.1745-3933.2007.00366.x | null | astro-ph | null | We present optical photo-polarimetric observations with high temporal
resolution of the blazar AO 0235+164. Our data, the first to test the
photo-polarimetric behaviour of this object at very short time-scales, show
significant micro-variability in total flux, colour index, linear polarization
degree, and position angle. Strong inter-night variations are also detected for
these parameters. Although no correlation between colour index and total flux
was found, our data seem to support the general bluer-when-brighter trend
already known for this object. The polarization degree, in turn, shows no
correlation with total flux, but a clear trend in the sense that colour index
is redder (the spectrum is softer) when the measured polarization is higher.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 20:35:15 GMT"
}
] | 2009-06-09T00:00:00 | [
[
"Cellone",
"Sergio A.",
"",
"1 and 2"
],
[
"Romero",
"Gustavo E.",
"",
"1 and 2"
],
[
"Combi",
"Jorge A.",
"",
"2\n and 3"
],
[
"Marti",
"Josep",
""
]
] |
0707.2600 | Jonas Fransson | J. Fransson | Subnanosecond switching of local spin-exchange coupled to ferromagnets | 5 pages, 3 figures | Phys. Rev. B, 77, 205316 (2008) | 10.1103/PhysRevB.77.205316 | null | cond-mat.mes-hall | null | The dynamics of a single spin embedded in a the tunnel junction between
ferromagnetic contacts is strongly affected by the exchange coupling to the
tunneling electrons. Using time-dependent equation of motion for the spin under
influence of the spin-polarized tunneling current, it is shown that the
magnetic field induced by bias voltage pulses allows for sub-nanosecond
switching of the local spin and the possibility of spin reversal is
illustrated. Furthermore, it is shown that the time-evolution of the Larmor
frequency sharply peaks around the spin-flip event, and it is argued that this
feature can be used as an indicator for the spin-flip.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 20:39:45 GMT"
},
{
"version": "v2",
"created": "Fri, 16 May 2008 06:52:51 GMT"
}
] | 2008-05-16T00:00:00 | [
[
"Fransson",
"J.",
""
]
] |
0707.2601 | Andr\'e Waelkens | A. Waelkens (1), M. Maturi (1 and 2), T. Ensslin (1) ((1) MPA
Garching, (2) ITA Heidelberg) | Camouflaged galactic CMB foregrounds: total and polarized contributions
of the kinetic Sunyaev Zeldovich effect | 9 pages, 6 figures, 2 tables. submitted | null | 10.1111/j.1365-2966.2007.12595.x | null | astro-ph | null | We consider the role of the galactic kinetic Sunyaev Zeldovich (SZ) effect as
a CMB foreground. While the galactic thermal Sunyaev Zeldovich effect has
previously been studied and discarded as a potential CMB foreground, we find
that the kinetic SZ effect is dominant in the galactic case. We analyse the
detectability of the kinetic SZ effect by means of an optimally matched filter
technique applied to a simulation of an ideal observation. We obtain no
detection, getting a S/N ratio of 0.1, thereby demonstrating that the kinetic
SZ effect can also safely be ignored as a CMB foreground. However we provide
maps of the expected signal for inclusion in future high precision data
processing. Furthermore, we rule out the significant contamination of the
polarised CMB signal by second scattering of galactic kinetic Sunyaev-Zeldovich
photons, since we show that the scattering of the CMB quadrupole photons by
galactic electrons is a stronger effect than the Sunyaev Zeldovich second
scattering, and has already been shown to produce no significant polarised
contamination. We confirm the latter assessment also by means of an optimally
matched filter.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 21:31:25 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Waelkens",
"A.",
"",
"1 and 2"
],
[
"Maturi",
"M.",
"",
"1 and 2"
],
[
"Ensslin",
"T.",
""
]
] |
0707.2602 | Wendy Lowen | Wendy Lowen | Hochschild cohomology, the characteristic morphism and derived
deformations | 24 pages | null | 10.1112/S0010437X08003655 | null | math.KT | null | A notion of Hochschild cohomology of an abelian category was defined by Lowen
and Van den Bergh (2005) and they showed the existence of a characteristic
morphism from the Hochschild cohomology into the graded centre of the (bounded)
derived category. An element in the second Hochschild cohomology group
corresponds to a first order deformation of the abelian category (Lowen and Van
den Bergh, 2006). The problem of deforming single objects of the bounded
derived category was treated by Lowen (2005). In this paper we show that the
image of the Hochschild cohomology element under the characteristic morphism
encodes precisely the obstructions to deforming single objects of the bounded
derived category. Hence this paper provides a missing link between the above
works. Finally we discuss some implications of these facts in the direction of
a ``derived deformation theory''.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 21:15:32 GMT"
}
] | 2014-01-14T00:00:00 | [
[
"Lowen",
"Wendy",
""
]
] |
0707.2603 | Artur Lopes O. | Diogo A. Gomes, Artur O. Lopes and Joana Mohr | The Mather measure and a Large Deviation Principle for the Entropy
Penalized Method | null | null | null | null | math.DS math.AP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a large deviation principle for the entropy penalized Mather
problem when the Lagrangian L is generic (in this case the Mather measure $\mu$
is unique and the support of $\mu$ is the Aubry set). Consider, for each value
of $\epsilon $ and h, the entropy penalized Mather problem $\min
\{\int_{\tn\times\rn}
L(x,v)d\mu(x,v)+\epsilon S[\mu]\},$ where the entropy S is given by
$S[\mu]=\int_{\tn\times\rn}\mu(x,v)\ln\frac{\mu(x,v)}{\int_{\rn}\mu(x,w)dw}dxdv,$
and the minimization is performed over the space of probability densities
$\mu(x,v)$ that satisfy the holonomy constraint It follows from D. Gomes and E.
Valdinoci that there exists a minimizing measure $\mu_{\epsilon, h}$ which
converges to the Mather measure $\mu$. We show a LDP $\lim_{\epsilon,h\to0}
\epsilon \ln \mu_{\epsilon,h}(A),$ where $A\subset
\mathbb{T}^N\times\mathbb{R}^N$. The deviation function I is given by $I(x,v)=
L(x,v)+\nabla\phi_0(x)(v)-\bar{H}_{0},$ where $\phi_0$ is the unique viscosity
solution for L.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 21:28:34 GMT"
},
{
"version": "v2",
"created": "Sun, 23 Nov 2008 17:42:13 GMT"
}
] | 2008-11-23T00:00:00 | [
[
"Gomes",
"Diogo A.",
""
],
[
"Lopes",
"Artur O.",
""
],
[
"Mohr",
"Joana",
""
]
] |
0707.2604 | Alan M. Watson | Arturo God\'inez-Mart\'inez, Alan M. Watson, Lynn D. Matthews and
Linda S. Sparke | Photometry of Polar-Ring Galaxies | To appear in RMxAA. 14 pages. 7 figures | null | null | null | astro-ph | null | We have obtained photometry in B and R for seven confirmed or probable
polar-ring galaxies from the Polar-Ring Catalog of Whitmore et al. (1990). The
rings show a range of colors from B-R \approx 0.6 to B-R \approx 1.7. The
bluest rings have bright HII regions, which are direct evidence for recent star
formation. The minimum age of the reddest ring, that in PRC B-20, is somewhat
uncertain because of a lack of knowledge of the internal reddening and
metallicity, but appears to be at least 1.2 Gyr. As such, this ring is likely
to be stable for at least several rotation periods. This ring is an excellent
candidate for future studies that might better determine if it is truly old.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 21:40:43 GMT"
}
] | 2007-07-19T00:00:00 | [
[
"Godínez-Martínez",
"Arturo",
""
],
[
"Watson",
"Alan M.",
""
],
[
"Matthews",
"Lynn D.",
""
],
[
"Sparke",
"Linda S.",
""
]
] |
0707.2605 | Wendy Lowen | Wendy Lowen | A sheaf of Hochschild complexes on quasi-compact opens | 7 pages. To appear in Proc. Amer. Math. Soc | null | null | null | math.AG | null | For a scheme X, we construct a sheaf C of complexes on X such that for every
quasi-compact open subset U of X, C(U) is quasi-isomorphic to the Hochschild
complex of the scheme U. Since C is moreover acyclic for taking sections on
quasi-compact opens, we obtain a local to global spectral sequence for
Hochschild cohomology if X is quasi-compact.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 21:57:35 GMT"
}
] | 2007-07-19T00:00:00 | [
[
"Lowen",
"Wendy",
""
]
] |
0707.2606 | William Welsh | William F. Welsh, Danielle L. Martino, Go Kawaguchi and Wolfram
Kollatschny | Measuring H-beta BLR Flows in NGC 5548 | 2 pages, 2 figures; conference proceedings to appear in "The Central
Engine of Active Galactic Nuclei", ed. L. C. Ho and J.-M. Wang (San
Francisco: ASP) | null | null | null | astro-ph | null | Using archival International AGN Watch observations we find a correlation
between the asymmetry of the H-beta line and the system luminosity: the line
becomes bluer as the system gets brighter. We also find a differential lag
between the red and blue wings of the line: the blue wing lags the red by ~4
days, suggesting an inflow component of the BLR.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 23:05:35 GMT"
}
] | 2007-07-19T00:00:00 | [
[
"Welsh",
"William F.",
""
],
[
"Martino",
"Danielle L.",
""
],
[
"Kawaguchi",
"Go",
""
],
[
"Kollatschny",
"Wolfram",
""
]
] |
0707.2607 | Emilio Romano-Diaz | Emilio Romano-Diaz (3,2,1), Rien van de Weygaert (1) ((1) Kapteyn
Institute RuG, (2) Hebrew U., Israel, (3) U. of Kentucky, USA) | DTFE analysis of the PSCz local Universe: Density Field and Cosmic Flow | 32 pages, 16 figures. Accepted for publication in MNRAS. Full ps
version available at http://www.astro.rug.nl/~weygaert/dtfepscz.html | null | null | null | astro-ph | null | We apply the Delaunay Tessellation Field Estimator (DTFE) to reconstruct and
analyze the matter distribution and cosmic velocity flows in the Local Universe
on the basis of the PSCz galaxy survey. The prime objective of this study is
the production of optimal resolution three-dimensional maps fully
volume-covering of the volume-weighted velocity and density fields throughout
the nearby Universe, out to a distance of 150 Mpc/h. Based on the Voronoi and
Delaunay tessellation defined by the spatial galaxy sample, DTFE involves the
estimate of density values on the basis of the volume of the related Delaunay
tetrahedra and the subsequent use of theDelaunay tessellation as natural
multidimensional (linear) interpolation grid for the corresponding density and
velocity fields throughout the sample volume. The linearized model of the
spatial galaxy distribution and the corresponding peculiar velocities of the
PSCz galaxy sample, produced by Brachini et al. (1999), forms the input sample
for the DTFE study. The DTFE maps reproduce the high-density supercluster
regions in optimal detail, both their internal structure as well as their
elongated or flattened shape. The corresponding velocity flows trace the bulk
and shear flows marking the region extending from the Pisces-Perseus
supercluster, via the Local superclusters, towards the Hydra-Centaurus and the
Shapley concentration. The most outstanding and unique feature of the DTFE maps
is the sharply defined radial outflow regions in and around underdense voids,
marking the dynamical importance of voids in the Local Universe. The maximum
expansion rate of voids defines a sharp cutoff in the DTFE velocity divergence
pdf. We found that on the basis of this cutoff DTFE manages to consistently
reproduce the value of O_m ~ 0.35 underlying the linearized velocity dataset.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 22:18:32 GMT"
}
] | 2007-07-19T00:00:00 | [
[
"Romano-Diaz",
"Emilio",
""
],
[
"van de Weygaert",
"Rien",
""
]
] |
0707.2608 | Alan M. Watson | Alan M. Watson, Karl R. Stapelfeldt, Kenneth Wood, and Fran\c{c}ois
M\'enard | Multi-Wavelength Imaging of Young Stellar Object Disks: Toward an
Understanding of Disk Structure and Dust Evolution | Invited review at the Protostars and Planets V conference | null | null | null | astro-ph | null | We review recent progress in high-resolution imaging of scattered light from
disks around young stellar objects. Many new disks have been discovered or
imaged in scattered light, and improved instrumentation and observing
techniques have led to better disk images at optical, near-infrared, and
thermal-infrared wavelengths. Multi-wavelength datasets are particularly
valuable, as dust particle properties have wavelength dependencies. Modeling
the changes in scattered-light images with wavelength gives direct information
on the dust properties. This has now been done for several different disks. The
results indicate that modest grain growth has taken place in some of these
systems. Scattered-light images also provide useful constraints on the disk
structure, especially when combined with long-wavelength SEDs. There are
tentative suggestions in some disks that the dust may have begun to settle. The
next few years should see this work extended to many more disks; this will
clarify our understanding of the evolution of protoplanetary dust and disks.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 22:27:25 GMT"
}
] | 2007-07-19T00:00:00 | [
[
"Watson",
"Alan M.",
""
],
[
"Stapelfeldt",
"Karl R.",
""
],
[
"Wood",
"Kenneth",
""
],
[
"Ménard",
"François",
""
]
] |
0707.2609 | Evelyne Alecian | E. Alecian, Y. Lebreton, M-J. Goupil, M-A. Dupret, C. Catala | Impact of the new solar abundances on the calibration of the PMS binary
system RS Cha | Research note accepted in A&A, 5 pages, 2 figures | null | 10.1051/0004-6361:20077332 | null | astro-ph | null | Context: In a recent work, we tried to obtain a calibration of the two
components of the pre-main sequence binary system RS Cha by means of
theoretical stellar models. We found that the only way to reproduce the
observational parameters of RS Cha with standard stellar models is to decrease
the initial abundances of carbon and nitrogen derived from the GN93 solar
mixture of heavy elements by a few tenths of dex.
Aims: In this work, we aim to reproduce the observational properties of the
RS Cha stars with stellar evolution models based on the new AGS05 solar mixture
recently derived from a three-dimensional solar model atmosphere. The AGS05
mixture is depleted in carbon, nitrogen and oxygen with respect to the GN93
mixture.
Methods: We calculated new stellar models of the RS Cha components using the
AGS05 mixture and appropriate opacity tables. We sought models that
simultaneously satisfy the observations of the two components (masses, radii,
luminosities, effective temperatures and metallicity).
Results: We find that it is possible to reproduce the observational data of
the RS Cha stars with AGS05 models based on standard input physics. From these
models, the initial helium content of the system is Y~0.255 and its age is
~9.13 +- 0.12 Myr.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 22:30:44 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Alecian",
"E.",
""
],
[
"Lebreton",
"Y.",
""
],
[
"Goupil",
"M-J.",
""
],
[
"Dupret",
"M-A.",
""
],
[
"Catala",
"C.",
""
]
] |
0707.2610 | Kristen Sellgren | Katia Cunha (1, 2), Kris Sellgren (3), Verne V. Smith (1), Solange V.
Ramirez (4), Robert D. Blum (1), Donald M. Terndrup (3) ((1) National Optical
Astronomy Observatory, (2) on leave from Observatorio Nacional, Rio de
Janeiro, Brazil, (3) Ohio State University, (4) IPAC/Caltech) | Chemical Abundances of Luminous Cool Stars in the Galactic Center from
High-Resolution Infrared Spectroscopy | ApJ, in press; 30 pages text + 9 color figures | ApJ, 669, 1011 (2007) | 10.1086/521813 | null | astro-ph | null | We present chemical abundances in a sample of luminous cool stars located
within 30 pc of the Galactic Center. Abundances of carbon, nitrogen, oxygen,
calcium, and iron were derived from high-resolution infrared spectra in the H-
and K-bands. The abundance results indicate that both [O/Fe] and [Ca/Fe] are
enhanced respectively by averages of +0.2 and +0.3 dex, relative to either the
Sun or the Milky Way disk at near solar Fe abundances. The Galactic Center
stars show a nearly uniform and nearly solar iron abundance. The mean value of
A(Fe) = 7.59 +- 0.06 agrees well with previous work. The total range in Fe
abundance among Galactic Center stars, 0.16 dex, is significantly narrower than
the iron abundance distributions found in the literature for the older bulge
population. Our snapshot of the current-day Fe abundance within 30 pc of the
Galactic Center samples stars with an age less than 1 Gyr; a larger sample in
time (or space) may find a wider spread in abundances.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 00:25:25 GMT"
}
] | 2009-03-20T00:00:00 | [
[
"Cunha",
"Katia",
""
],
[
"Sellgren",
"Kris",
""
],
[
"Smith",
"Verne V.",
""
],
[
"Ramirez",
"Solange V.",
""
],
[
"Blum",
"Robert D.",
""
],
[
"Terndrup",
"Donald M.",
""
]
] |
0707.2611 | Asma Al-Qasimi | Asma Al-Qasimi, Daniel F. V. James | Do all states undergo sudden death of entanglement at finite
temperature? | 4 pages, 3 figures | null | 10.1103/PhysRevA.77.012117 | null | quant-ph | null | In this paper we consider the decay of quantum entanglement, quantified by
the concurrence, of a pair of two-level systems each of which is interacting
with a reservoir at finite temperature T. For a broad class of initially
entangled states, we demonstrate that the system always becomes disentangled in
a finite time i.e."entanglement sudden death" (ESD) occurs. This class includes
all states which previously had been found to have long-lived entanglement in
zero temperature reservoirs. Our general result is illustrated by an example.
| [
{
"version": "v1",
"created": "Tue, 17 Jul 2007 23:43:00 GMT"
}
] | 2013-05-29T00:00:00 | [
[
"Al-Qasimi",
"Asma",
""
],
[
"James",
"Daniel F. V.",
""
]
] |
0707.2612 | Jeff Achter | Jeff Achter | Exceptional covers of surfaces | null | Canad Math Bull 53 (2010), no. 3, 385--393 | 10.4153/CMB-2010-049-7 | null | math.AG | null | Consider a finite morphism f:X -> Y of smooth projective varieties over a
finite field k. Suppose X is the vanishing locus in projective N-space of at
most r forms of degree at most d. We show there is a constant C, depending only
on N, r, d and deg(f) such that if #k > C, then f(k):X(k) -> Y(k) is injective
if and only if it's surjective.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 00:05:57 GMT"
},
{
"version": "v2",
"created": "Tue, 21 Aug 2007 17:16:05 GMT"
}
] | 2020-02-27T00:00:00 | [
[
"Achter",
"Jeff",
""
]
] |
0707.2613 | Hongwei Yu | Hongwei Yu, Wenting Zhou | Do static atoms outside a Schwarzschild black hole spontaneously excite? | 15 pages, no figures, to be published in PRD | Phys.Rev.D76:044023,2007 | 10.1103/PhysRevD.76.044023 | null | gr-qc hep-th | null | The spontaneous excitation of a two-level atom held static outside a four
dimensional Schwarzschild black hole and in interaction with a massless scalar
field in the Boulware, Unruh and Hartle-Hawking vacuum is investigated and the
contributions of the vacuum fluctuations and radiation reaction to the rate of
change of the mean atomic energy are calculated separately. We find that for
the Boulware vacuum, the spontaneous excitation does not occur and the ground
state atoms are stable, while the spontaneous emission rate for excited atoms
in the Boulware vacuum, which is well-behaved at the event horizon, is not the
same as that in the usual Minkowski vacuum. However, both for the Unruh vacuum
and the Hartle-Hawking vacuum, our results show that the atom would
spontaneously excite, as if there were an outgoing thermal flux of radiation or
as if it were in a thermal bath of radiation at a proper temperature which
reduces to the Hawking temperature in the spatial asymptotic region, depending
on whether the scalar field is in the Unruh or Hartle-Hawking vacuum.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 00:20:27 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Yu",
"Hongwei",
""
],
[
"Zhou",
"Wenting",
""
]
] |
0707.2614 | Elena Rasia | E. Rasia, P. Mazzotta, H. Bourdin, S. Borgani, L. Tornatore, S.
Ettori, K. Dolag and L. Moscardini | X-MAS2: Study Systematics on the ICM Metallicity Measurements | (e.g.: 17 pages, 8 figures, accepted for publication in the
Astrophysical Journal, updated discussion to match published version-new
section:6.3) | null | 10.1086/524345 | null | astro-ph | null | (Abridged)The X-ray measurements of the ICM metallicity are becoming more
frequent due to the availability of powerful X-ray telescope with excellent
spatial and spectral resolutions. The information which can be extracted from
the measurements of the alpha-elements, like Oxygen, Magnesium and Silicon with
respect to the Iron abundance is extremely important to better understand the
stellar formation and its evolutionary history. In this paper we investigate
possible source of bias connected to the plasma physics when recovering metal
abundances from X-ray spectra. To do this we analyze 6 simulated galaxy
clusters processed through the new version of our X-ray MAp Simulator, which
allows to create mock XMM-Newton EPIC MOS1 and MOS2 observations. By comparing
the spectroscopic results to the input values we find that: i) Fe is recovered
with high accuracy for both hot (T>3 keV) and cold (T<2 keV) systems; at
intermediate temperatures, however, we find a systematic overestimate which
depends on the number counts; ii) O is well recovered in cold clusters, while
in hot systems its measure may overestimate by a factor up to 2-3; iii) Being a
weak line, the measurement of Mg is always difficult; despite of this, for cold
systems (T<2 keV) we do not find any systematic behavior, while for very hot
systems (T>5 keV) the spectroscopic measurement may be strongly overestimated
up to a factor of 4; iv) Si is well recovered for all the clusters in our
sample. We investigate in detail the nature of the systematic effects and
biases found. We conclude that they are mainly connected with the
multi-temperature nature of the projected observed spectra and to the intrinsic
limitation of the XMM-Newton EPIC spectral resolution that does not always
allow to disentangle among the emission lines produced by different elements.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 00:22:17 GMT"
},
{
"version": "v2",
"created": "Thu, 1 Nov 2007 15:25:09 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Rasia",
"E.",
""
],
[
"Mazzotta",
"P.",
""
],
[
"Bourdin",
"H.",
""
],
[
"Borgani",
"S.",
""
],
[
"Tornatore",
"L.",
""
],
[
"Ettori",
"S.",
""
],
[
"Dolag",
"K.",
""
],
[
"Moscardini",
"L.",
""
]
] |
0707.2615 | Kazuya Miyagawa | Y. Hara, K. Miyagawa, K. Kanoda, M. Shimamura, A. Kobayashi and H.
Kobayashi | NMR Evidence for Antiferromagnetic Transition in the Single-Component
Molecular Conductor, [Au(tmdt)_{2}] at 110 K | 5pages, 6figures to be published in J. Phys. Soc. Jpn | null | 10.1143/JPSJ.77.053706 | null | cond-mat.str-el | null | We present the results of a ^{1}H NMR study of the single-component molecular
conductor, [Au(tmdt)_{2}].
A steep increase in the NMR line width and a peak formation of the nuclear
spin-lattice relaxation rate, 1/T_{1}, were observed at around 110 K.
This behavior provides clear and microscopic evidences for a magnetic phase
transition at considerably high temperature among organic conductors.
The observed variation in 1/T_{1} with respect to temperature indicates the
highly correlated nature of the metallic phase.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 01:37:22 GMT"
},
{
"version": "v2",
"created": "Wed, 18 Jul 2007 22:28:16 GMT"
},
{
"version": "v3",
"created": "Fri, 11 Apr 2008 04:55:06 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Hara",
"Y.",
""
],
[
"Miyagawa",
"K.",
""
],
[
"Kanoda",
"K.",
""
],
[
"Shimamura",
"M.",
""
],
[
"Kobayashi",
"A.",
""
],
[
"Kobayashi",
"H.",
""
]
] |
0707.2616 | Prateek Sharma | Prateek Sharma, Gregory W. Hammett | Preserving Monotonicity in Anisotropic Diffusion | accepted for publication in J. of Comp. Phys | J.Comput.Phys.227:123-142,2007 | 10.1016/j.jcp.2007.07.026 | null | astro-ph physics.comp-ph physics.plasm-ph | null | We show that standard algorithms for anisotropic diffusion based on centered
differencing (including the recent symmetric algorithm) do not preserve
monotonicity. In the context of anisotropic thermal conduction, this can lead
to the violation of the entropy constraints of the second law of
thermodynamics, causing heat to flow from regions of lower temperature to
higher temperature. In regions of large temperature variations, this can cause
the temperature to become negative. Test cases to illustrate this for centered
asymmetric and symmetric differencing are presented. Algorithms based on slope
limiters, analogous to those used in second order schemes for hyperbolic
equations, are proposed to fix these problems. While centered algorithms may be
good for many cases, the main advantage of limited methods is that they are
guaranteed to avoid negative temperature (which can cause numerical
instabilities) in the presence of large temperature gradients. In particular,
limited methods will be useful to simulate hot, dilute astrophysical plasmas
where conduction is anisotropic and the temperature gradients are enormous,
e.g., collisionless shocks and disk-corona interface.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 00:35:38 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Sharma",
"Prateek",
""
],
[
"Hammett",
"Gregory W.",
""
]
] |
0707.2617 | Jenny Greene | Jenny E. Greene (Princeton), Luis C. Ho (Carnegie Observatories) | A New Sample of Low-mass Black Holes in Active Galaxies | to appear in ApJ; 13 pages, 8 figures | null | 10.1086/522082 | null | astro-ph | null | We present an expanded sample of low-mass black holes (BHs) found in galactic
nuclei. Using standard virial mass techniques to estimate BH masses, we select
from the Fourth Data Release of the Sloan Digital Sky Survey all broad-line
active galaxies with masses < 2 x 10^6 M_sun. BHs in this mass regime provide
unique tests of the relationship between BHs and galaxies, since their
late-type galaxy hosts do not necessarily contain classical bulges.
Furthermore, they provide observational analogs of primordial seed BHs and are
expected, when merging, to provide strong gravitational signals for future
detectors such as LISA. From our preliminary sample of 19, we have increased
the total sample by an order of magnitude to 174, as well as an additional 55
(less secure) candidates. The sample has a median BH mass of <M_BH> = 1.3 x
10^6 M_sun, and in general the objects are radiating at high fractions of their
Eddington limits. We investigate the broad spectral properties of the sample;
55 are detected by \rosat, with soft X-ray luminosities in the range 10^40 to 7
x 10^43 ergs/sec. Much like the preliminary sample, these objects are
predominantly radio-quiet (R = f_6cm/f_4400A < 10), but 11 objects are detected
at 20 cm, with radio powers (10^21-10^23 W/Hz) that may arise from either star
formation or nuclear activity; only 1% of the sample is radio-loud. We further
confirm that, with <M_g>=-19.3 and <g-r> = 0.7 mag, the host galaxies are
low-mass, late-type systems. At least 40% show disk-like morphologies, and the
combination of host galaxy colors and higher-order Balmer absorption lines
indicate intermediate-age stellar populations in a subset of the sample.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 00:43:54 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Greene",
"Jenny E.",
"",
"Princeton"
],
[
"Ho",
"Luis C.",
"",
"Carnegie Observatories"
]
] |
0707.2618 | Costas Efthimiou | C.J. Efthimiou, M.D. Johnson | Domino Waves | 10 pages, 5 figures | SIAM Review 49 (2007) 111 | 10.1137/S0036144504414505 | null | math.DS math.HO | null | Motivated by a proposal of Daykin (Problem 71-19*, SIAM Review 13 (1971)
569), we study the wave that propagates along an infinite chain of dominoes and
find the limiting speed of the wave in an extreme case.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 01:08:44 GMT"
}
] | 2007-07-19T00:00:00 | [
[
"Efthimiou",
"C. J.",
""
],
[
"Johnson",
"M. D.",
""
]
] |
0707.2619 | Kenji Yonemitsu | Kenji Yonemitsu and Nobuya Maeshima | Photoinduced melting of charge order in a quarter-filled electron system
coupled with different types of phonons | 7 pages, 5 figures, accepted for publication in PRB | Phys. Rev. B 76, 075105 (2007) | 10.1103/PhysRevB.76.075105 | null | cond-mat.str-el | null | Photoinduced melting of charge order is calculated by using the exact
many-electron wave function coupled with classically treated phonons in the
one-dimensional quarter-filled Hubbard model with Peierls and Holstein types of
electron-phonon couplings. The model parameters are taken from recent
experiments on (EDO-TTF)_2PF_6 (EDO-TTF=ethylenedioxy-tetrathiafulvalene) with
(0110) charge order, where transfer integrals are modulated by molecular
displacements (bond-coupled phonons) and site energies by molecular
deformations (charge-coupled phonons). The charge-transfer photoexcitation from
(0110) to (0200) configurations and that from (0110) to (1010) configurations
have different energies. The corresponding excited states have different shapes
of adiabatic potentials as a function of these two phonon amplitudes. The
adiabatic potentials are shown to be useful in understanding differences in the
photoinduced charge dynamics and the efficiency of melting, which depend not
only on the excitation energy but also on the relative phonon frequency of the
bond- and charge-coupled phonons.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 01:13:34 GMT"
}
] | 2009-04-27T00:00:00 | [
[
"Yonemitsu",
"Kenji",
""
],
[
"Maeshima",
"Nobuya",
""
]
] |
0707.2620 | Jiren Liu | Jiren Liu and Li-Zhi Fang (UofA) | Non-Gaussianity of the Cosmic Baryon Fluid: Log-Poisson Hierarchy Model | 19 pages, 8 figures, accepted by ApJ | null | 10.1086/523684 | null | astro-ph | null | In the nonlinear regime of cosmic clustering, the mass density field of the
cosmic baryon fluid is highly non-Gaussian. It shows different dynamical
behavior from collisionless dark matter. Nevertheless, the evolved field of
baryon fluid is scale-covariant in the range from the Jeans length to a few ten
h^{-1} Mpc, in which the dynamical equations and initial perturbations are
scale free. We show that in the scale-free range, the non-Gaussian features of
the cosmic baryon fluid, governed by the Navier-Stokes equation in an expanding
universe, can be well described by a log-Poisson hierarchical cascade. The
log-Poisson scheme is a random multiplicative process (RMP), which causes
non-Gaussianity and intermittency even when the original field is Gaussian. The
log-Poisson RMP contains two dimensionless parameters: $\beta$ for the
intermittency and $\gamma$ for the most singular structure. All the predictions
given by the log-Poisson RMP model, including the hierarchical relation, the
order dependence of the intermittent exponent, the moments, and the scale-scale
correlation, are in good agreement with the results given by hydrodynamic
simulations of the standard cold dark matter model. The intermittent parameter
$\beta$ decreases slightly at low redshift and indicates that the density field
of baryon fluid contains more singular structures at lower redshifts. The
applicability of the model is addressed.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 01:43:36 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Liu",
"Jiren",
"",
"UofA"
],
[
"Fang",
"Li-Zhi",
"",
"UofA"
]
] |
0707.2621 | Sean Paul | Sean Timothy Paul | Higher Energies in Kahler Geometry I | 24 pages | null | null | null | math.DG math.AG | null | Let $X\hookrightarrow \cpn $ be a smooth complex projective variety of
dimension $n$. Let $\lambda$ be an algebraic one parameter subgroup of
$G:=\gc$. Let $ 0\leq l\leq n+1$. We associate to the coefficients
$F_{l}(\lambda)$ of the normalized weight of $\lambda$ on the $mth$ Hilbert
point of $X$ new energies $F_{\om,l}(\vp)$. The (logarithmic) asymptotics of
$F_{\om,l}(\vp)$ along the potential deduced from $\lambda$ is the weight
$F_{l}(\lambda)$. $F_{\om,l}(\vp)$ reduces to the Aubin energy when $l=0$ and
the K-Energy map of Mabuchi when $l=1$. When $l\geq 2$ $F_{\om,l}(\vp)$
coincides (modulo lower order terms) with the functional $E_{\om,l-1}(\vp)$
introduced by X.X. Chen and G.Tian.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 01:50:52 GMT"
}
] | 2007-07-19T00:00:00 | [
[
"Paul",
"Sean Timothy",
""
]
] |
0707.2622 | Andrew Walsh | Andrew J. Walsh, Jacqueline F. Chapman, Michael G. Burton, Mark
Wardle, T. J. Millar | ATCA 1.2 cm Observations of the Massive Star Forming Region G305.2+0.2 | 13 pages 11 figures | null | null | null | astro-ph | null | We report on Australia Telescope observations of the massive star forming
region G305.2+0.2 at 1.2 cm. We detected emission in five molecules towards
G305A, confirming its hot core nature. We determined a rotational temperature
of 26 K for methanol. A non-LTE excitation calculation suggests a kinematic
temperature of order 200 K. A time dependent chemical model is also used to
model the gas phase chemistry of the hot core associated with G305A. A
comparison with the observations suggest an age of between 2 x10^4 and 1.5
x10^5 years. We also report on a feature to the SE of G305A which may show weak
Class I methanol maser emission in the line at 24.933 GHz. The more evolved
source G305B does not show emission in any of the line tracers, but strong
Class I methanol maser emission at 24.933 GHz is found 3\arcsec to the east.
Radio continuum emission at 18.496 GHz is detected towards two \hii regions.
The implications of the non-detection of radio continuum emission toward G305A
and G305B are also discussed.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 02:09:52 GMT"
}
] | 2007-07-19T00:00:00 | [
[
"Walsh",
"Andrew J.",
""
],
[
"Chapman",
"Jacqueline F.",
""
],
[
"Burton",
"Michael G.",
""
],
[
"Wardle",
"Mark",
""
],
[
"Millar",
"T. J.",
""
]
] |
0707.2623 | Shi-Lin Zhu | Shi-Lin Zhu | Spectroscopy of Mesons with Heavy Quarks | Plenary talk at INPC2007, http://inpc2007.riken.jp/P/P5-zhu.pdf | Nucl.Phys.A805:221c-229c,2008 | 10.1016/j.nuclphysa.2008.02.251 | null | hep-ph hep-ex nucl-th | null | I will give a concise overview of mesons with heavy quarks including p-wave
charmed mesons and charmonium (or charmonium-like) states such as X(3872),
Y(4260), X(3940), Y(3940), Z(3930) etc. The effect from the nearby S-wave open
channels on the quark model spectrum is emphasized.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 02:03:49 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Zhu",
"Shi-Lin",
""
]
] |
0707.2624 | Toshiya Takami | Toshiya Takami and Hiroshi Fujisaki | Analytic Approach for Controlling Realistic Quantum Chaotic Systems | 4 pages with 4 PostScript figures, to appear in the Proceedings of
ICCMSE 2007 in a section of Symposium 8 "Quantum Control and Light-Matter
Interactions: Recent Computational and Theoretical Results" | AIP Conf. Proc. 963, 821-824 (2007) | 10.1063/1.2836218 | null | nlin.CD physics.chem-ph quant-ph | null | An analytic approach for controlling quantum states, which was originally
applied to fully random matrix systems [T. Takami and H. Fujisaki, Phys. Rev. E
75, 036219 (2007)], is extended to deal with more realistic quantum systems
with a banded random matrix (BRM). The validity of the new analytic field is
confirmed by directly solving the Schroedinger equation with a BRM interaction.
We find a threshold of the width of the BRM for the quantum control to be
successful.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 02:43:44 GMT"
}
] | 2008-01-10T00:00:00 | [
[
"Takami",
"Toshiya",
""
],
[
"Fujisaki",
"Hiroshi",
""
]
] |
0707.2625 | Qijin Chen | Yan He, Chih-Chun Chien, Qijin Chen, and K. Levin | Radio Frequency Spectroscopy of Trapped Fermi Gases with Population
Imbalance | 4 page, 3 figures, submitted to PRA Rapid | Phys. Rev. A 77, 011602(R) (2008) | 10.1103/PhysRevA.77.011602 | null | cond-mat.str-el cond-mat.quant-gas cond-mat.supr-con | null | Motivated by recent experiments, we address, in a fully self consistent
fashion, the behavior and evolution of radio frequency (RF) spectra as
temperature and polarization are varied in population imbalanced Fermi gases.
We discuss a series of scenarios for the experimentally observed zero
temperature pseudogap phase and show how present and future RF experiments may
help in its elucidation. We conclude that the MIT experiments at the lowest $T$
may well reflect ground state properties, but take issue with their claim that
the pairing gap survives up to temperatures of the order of the degeneracy
temperature $T_F$ at unitarity.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 03:09:49 GMT"
},
{
"version": "v2",
"created": "Mon, 10 Sep 2007 09:00:27 GMT"
}
] | 2011-09-13T00:00:00 | [
[
"He",
"Yan",
""
],
[
"Chien",
"Chih-Chun",
""
],
[
"Chen",
"Qijin",
""
],
[
"Levin",
"K.",
""
]
] |
0707.2626 | Michael Luke Walker | M. L. Walker | Higgs-free confinement hierarchy in five colour QCD | 9 pages, PTP class file, discussion at bottom of page 5 corrected | Prog.Theor.Phys.119:1,2008 | 10.1143/PTP.119.139 | null | hep-th | null | I consider the monopole condensate of five color QCD. The naive lowest energy
state is unobtainable at one-loop for five or more colors due to simple
geometric considerations. The consequent adjustment of the vacuum condensate
generates a hierarchy of confinement scales in a natural Higgs-free manner. The
accompanying symmetry hierarchy contains hints of standard model phenomenology.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 03:15:05 GMT"
},
{
"version": "v2",
"created": "Thu, 27 Sep 2007 04:19:46 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Walker",
"M. L.",
""
]
] |
0707.2627 | Litan Yan | Litan Yan, Yu Sun, Yunsheng Lu | On the linear fractional self-attracting diffusion | 14 Pages. To appear in Journal of Theoretical Probability | null | null | null | math.PR | null | In this paper, we introduce the linear fractional self-attracting diffusion
driven by a fractional Brownian motion with Hurst index 1/2<H<1, which is
analogous to the linear self-attracting diffusion. For 1-dimensional process we
study its convergence and the corresponding weighted local time. For
2-dimensional process, as a related problem, we show that the renormalized
self-intersection local time exists in L^2 if $\frac12<H<\frac3{4}$.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 03:09:21 GMT"
}
] | 2007-07-19T00:00:00 | [
[
"Yan",
"Litan",
""
],
[
"Sun",
"Yu",
""
],
[
"Lu",
"Yunsheng",
""
]
] |
0707.2628 | Chunyan Jiang | C. Y. Jiang, Y. P. Jing, A. Faltenbacher, W. P. Lin, Cheng Li | A fitting formula for the merger timescale of galaxies in hierarchical
clustering | 16 pages, 14 figures, accepted for publication in ApJ, minor changes
in the last few sentences of the discussion | null | 10.1086/526412 | null | astro-ph | null | We study galaxy mergers using a high-resolution cosmological hydro/N-body
simulation with star formation, and compare the measured merger timescales with
theoretical predictions based on the Chandrasekhar formula. In contrast to
Navarro et al., our numerical results indicate, that the commonly used equation
for the merger timescale given by Lacey and Cole, systematically underestimates
the merger timescales for minor mergers and overestimates those for major
mergers. This behavior is partly explained by the poor performance of their
expression for the Coulomb logarithm, \ln (m_pri/m_sat). The two alternative
forms \ln (1+m_pri/m_sat) and 1/2\ln [1+(m_pri/m_sat)^2] for the Coulomb
logarithm can account for the mass dependence of merger timescale successfully,
but both of them underestimate the merger time scale by a factor 2. Since \ln
(1+m_pri/m_sat) represents the mass dependence slightly better we adopt this
expression for the Coulomb logarithm. Furthermore, we find that the dependence
of the merger timescale on the circularity parameter \epsilon is much weaker
than the widely adopted power-law \epsilon^{0.78}, whereas
0.94*{\epsilon}^{0.60}+0.60 provides a good match to the data. Based on these
findings, we present an accurate and convenient fitting formula for the merger
timescale of galaxies in cold dark matter models.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 09:06:16 GMT"
},
{
"version": "v2",
"created": "Sat, 10 Nov 2007 15:01:00 GMT"
},
{
"version": "v3",
"created": "Fri, 30 Nov 2007 11:30:12 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Jiang",
"C. Y.",
""
],
[
"Jing",
"Y. P.",
""
],
[
"Faltenbacher",
"A.",
""
],
[
"Lin",
"W. P.",
""
],
[
"Li",
"Cheng",
""
]
] |
0707.2629 | Luis Ramon Bellot Rubio | D. Cabrera Solana, L.R. Bellot Rubio, C. Beck, and J.C. del Toro
Iniesta (IAA-CSIC, IAC) | Temporal evolution of the Evershed flow in sunspots. I. Observational
characterization of Evershed clouds | Accepted for publication in A&A | null | 10.1051/0004-6361:20077819 | null | astro-ph | null | [Abridged] The magnetic and kinematic properties of the photospheric Evershed
flow are relatively well known, but we are still far from a complete
understanding of its nature. The evolution of the flow with time, which is
mainly due to appearance of velocity packets called Evershed clouds (ECs), may
provide information to further constrain its origin. Here we undertake a
detailed analysis of the evolution of the Evershed flow by studying the
properties of ECs. In this first paper we determine the sizes, proper motions,
location in the penumbra, and frequency of appearance of ECs, as well as their
typical Doppler velocities, linear and circular polarization signals, Stokes V
area asymmetries, and continuum intensities. High-cadence, high-resolution,
full vector spectropolarimetric measurements in visible and infrared lines are
used to derive these parameters. We find that ECs appear in the mid penumbra
and propage outward along filaments with large linear polarization signals and
enhanced Evershed flows. The frequency of appearance of ECs varies between 15
and 40 minutes in different filaments. ECs exhibit the largest Doppler
velocities and linear-to-circular polarization ratios of the whole penumbra. In
addition, lines formed deeper in the atmosphere show larger Doppler velocities,
much in the same way as the ''quiescent'' Evershed flow. According to our
observations, ECs can be classified in two groups: type I ECs, which vanish in
the outer penumbra, and type II ECs, which cross the outer penumbral boundary
and enter the sunspot moat. Most of the observed ECs belong to type I. On
average, type II ECs can be detected as velocity structures outside of the spot
for only about 14 min. Their proper motions in the moat are significantly
reduced with respect to the ones they had in the penumbra.
| [
{
"version": "v1",
"created": "Wed, 18 Jul 2007 03:46:22 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Solana",
"D. Cabrera",
"",
"IAA-CSIC, IAC"
],
[
"Rubio",
"L. R. Bellot",
"",
"IAA-CSIC, IAC"
],
[
"Beck",
"C.",
"",
"IAA-CSIC, IAC"
],
[
"Iniesta",
"J. C. del Toro",
"",
"IAA-CSIC, IAC"
]
] |
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