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list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0707.1030 | Tom Gehrels | Tom Gehrels | The multiverse and the origin of our universe | 16 pages | null | null | null | astro-ph | null | The multiverse is a hierarchy in the number of universes, increasing stepwise
towards infinity. It is an evolutionary system, in which universes survive only
near critical mass. That mass is actually a factor of 1.94 less than the
critical mass, and this is found to be consistent with the baryon density
inferred from nucleosynthesis in our universe; it is also precisely verified as
a cosmological effect. That factor seems to have originated in the multiverse
for causing intersecting expansions of its universes, such that mixing occurs
of debris from aging galaxies (over proton-decaying time scales). It follows
that there is an inter-universal medium (IUM), probably having the demand of
new universes in balance with the supply of dark radiation and sub-atomic
particles from the decaying galaxies. The mixing causes the universes to have
the same quantum, relativity, gravity, and particle physics as our universe.
The making of a universe from the radiation and sub-atomic particles occurs
through re-vitalizing the protons, and other particles as well, by
gravitational energy obtained in accretion of the IUM. This process therefore
begins wherever the IUM space density reaches proton density, near 10 E18 kg m
E-3. The process continues quietly as the sweeping-up and gravitational
accretion proceeds, until the near-critical mass is reached. Some of the IUM
debris must also be pervading our present universe, steadily or in partially
accreted lumps. The model therefore predicts that the IUM sub-atomic particles
appear as our dark matter, and its radiation component as our dark energy, both
near 0 K temperatures. The dark energy may cause expansion phenomena, in
addition to the above non-flatness expansion, from an accretion lump that
arrived at our universe at age near 9 x 10 E9 y.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 19:14:03 GMT"
}
] | 2007-07-09T00:00:00 | [
[
"Gehrels",
"Tom",
""
]
] |
0707.1031 | Niklas Beisert | Niklas Beisert, Benjamin I. Zwiebel | On Symmetry Enhancement in the psu(1,1|2) Sector of N=4 SYM | 35 pages, v2: references added, sign inconsistency resolved in
(5.5,5.6), v3: Section 3.4 on Hamiltonian added, minor improvements, to
appear in JHEP | JHEP 0710:031,2007 | 10.1088/1126-6708/2007/10/031 | AEI-2007-096, PUTP-2232 | hep-th | null | Strong evidence indicates that the spectrum of planar anomalous dimensions of
N=4 super Yang-Mills theory is given asymptotically by Bethe equations. A
curious observation is that the Bethe equations for the psu(1,1|2) subsector
lead to very large degeneracies of 2^M multiplets, which apparently do not
follow from conventional integrable structures. In this article, we explain
such degeneracies by constructing suitable conserved nonlocal generators acting
on the spin chain. We propose that they generate a subalgebra of the loop
algebra for the su(2) automorphism of psu(1,1|2). Then the degenerate
multiplets of size 2^M transform in irreducible tensor products of M
two-dimensional evaluation representations of the loop algebra.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 19:28:28 GMT"
},
{
"version": "v2",
"created": "Thu, 16 Aug 2007 16:09:41 GMT"
},
{
"version": "v3",
"created": "Wed, 19 Sep 2007 11:55:17 GMT"
}
] | 2009-11-18T00:00:00 | [
[
"Beisert",
"Niklas",
""
],
[
"Zwiebel",
"Benjamin I.",
""
]
] |
0707.1032 | Liz Humphreys Dr | Jim Moran, Liz Humphreys, Lincoln Greenhill, Mark Reid and Alice Argon | The structure of the accretion disk in NGC 4258 derived from
observations of its water vapor masers | 8 pages, 5 figures, to appear in proceedings of IAU Symposium 242
"Astrophysical Masers and their Environments", held in Alice Springs, March
2007 | null | 10.1017/S1743921307013440 | null | astro-ph | null | A wealth of new information about the structure of the maser disk in NGC 4258
has been obtained from a series of 18 VLBA observations spanning three years,
as well as from 32 additional epochs of spectral monitoring data from 1994 to
the present, acquired with the VLA, Effelsberg, and GBT. The warp of the disk
has been defined precisely. The thickness of the maser disk has been measured
to be 12 microarcseconds (FWHM), which is slightly smaller than previously
quoted upper limits. Under the assumption that the masers trace the true
vertical distribution of material in the disk, from the condition of
hydrostatic equilibrium the sound speed is 1.5 km/s, corresponding to a thermal
temperature of 600K. The accelerations of the high velocity maser components
have been accurately measured for many features on both the blue and red side
of the spectrum. The azimuthal offsets of these masers from the midline (the
line through the disk in the plane of the sky) and derived projected offsets
from the midline based on the warp model correspond well with the measured
offsets. This result suggests that the masers are well described as discrete
clumps of masing gas, which accurately trace the Keplerian motion of the disk.
However, we have continued to search for evidence of apparent motions caused by
``phase effects.'' This work provides the foundation for refining the estimate
of the distance to NGC 4258 through measurements of feature acceleration and
proper motion. The refined estimate of this distance is expected to be
announced in the near future.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 19:29:13 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Moran",
"Jim",
""
],
[
"Humphreys",
"Liz",
""
],
[
"Greenhill",
"Lincoln",
""
],
[
"Reid",
"Mark",
""
],
[
"Argon",
"Alice",
""
]
] |
0707.1033 | Felipe Fanchini | F. F. Fanchini, J. E. M. Hornos, and R. d. J. Napolitano | Continuously decoupling a Hadamard quantum gate from independent classes
of errors | null | Phys. Rev. A 76, 032319 (2007) | 10.1103/PhysRevA.76.032319 | null | quant-ph | null | We consider protecting a Hadamard operation from independent dephasing, bit
flipping, and dissipation. These environment-induced errors are represented by
three uncorrelated reservoirs of thermalized bosons and we show that the
protection is achievable through continuous dynamical decoupling. We find that,
to decouple the Hadamard evolution from the environmental influence, we need a
control field of higher frequency if the boson spectral density is super-ohmic
than if it is ohmic. We also study the relevance of bit flipping and
dissipation to the gate fidelity when it is protected from dephasing, showing
how robust this partial protection is against these other perturbations.
Finally, we calculate an efficient field arrangement capable of protecting
simultaneously the gate operation from these three error classes.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 19:30:23 GMT"
}
] | 2012-10-22T00:00:00 | [
[
"Fanchini",
"F. F.",
""
],
[
"Hornos",
"J. E. M.",
""
],
[
"Napolitano",
"R. d. J.",
""
]
] |
0707.1034 | Oskar Painter J | Matthew Borselli, Thomas J. Johnson, and Oskar Painter | Accurate measurement of scattering and absorption loss in microphotonic
devices | 3 pages, 3 figures | null | 10.1364/OL.32.002954 | null | physics.optics | null | We present a simple measurement and analysis technique to determine the
fraction of optical loss due to both radiation (scattering) and linear
absorption in microphotonic components. The method is generally applicable to
optical materials in which both nonlinear and linear absorption are present,
and requires only limited knowledge of absolute optical power levels, material
parameters, and the structure geometry. The technique is applied to high
quality factor (Q=1-5 X 10^6) silicon-on-insulator microdisk resonators. It is
determined that linear absorption can account for more than half the total
optical loss in the high-Q regime of these devices.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 19:37:04 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Borselli",
"Matthew",
""
],
[
"Johnson",
"Thomas J.",
""
],
[
"Painter",
"Oskar",
""
]
] |
0707.1035 | Harald Ita | Z. Bern, J.J. Carrasco, D. Forde, H. Ita, H. Johansson | Unexpected Cancellations in Gravity Theories | 40 pages, 6 figures. v2 minor corrections, removed comment on absence
of rational terms in N=4 supergravity | Phys.Rev.D77:025010,2008 | 10.1103/PhysRevD.77.025010 | UCLA/07/TEP/16, SLAC-PUB-12609 | hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recent computations of scattering amplitudes show that N=8 supergravity is
surprisingly well behaved in the ultraviolet and may even be ultraviolet finite
in perturbation theory. The novel cancellations necessary for ultraviolet
finiteness first appear at one loop in the guise of the "no-triangle
hypothesis". We study one-loop amplitudes in pure Einstein gravity and point
out the existence of cancellations similar to those found previously in N=8
supergravity. These cancellations go beyond those found in the one-loop
effective action. Using unitarity, this suggests that generic theories of
quantum gravity based on the Einstein-Hilbert action may be better behaved in
the ultraviolet at higher loops than suggested by naive power counting, though
without additional (supersymmetric) cancellations they diverge. We comment on
future studies that should be performed to support this proposal.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 22:41:47 GMT"
},
{
"version": "v2",
"created": "Sun, 30 Jan 2011 22:53:35 GMT"
}
] | 2015-03-13T00:00:00 | [
[
"Bern",
"Z.",
""
],
[
"Carrasco",
"J. J.",
""
],
[
"Forde",
"D.",
""
],
[
"Ita",
"H.",
""
],
[
"Johansson",
"H.",
""
]
] |
0707.1036 | Jun Liang Song | Jun Liang Song, Fei Zhou (UBC) | Tunable Quantum Fluctuation-Controlled Coherent Spin Dynamics | 14 pages, 12 figures included; including detailed discussions on
thermal effects, trapping potentials and spin exchange losses. (To appear in
PRA) | Phys. Rev. A 77, 033628 (2008) | 10.1103/PhysRevA.77.033628 | null | cond-mat.other | null | Temporal evolution of a macroscopic condensate of ultra cold atoms is usually
driven by mean field potentials, either due to scattering between atoms or due
to coupling to external fields; and coherent quantum dynamics have been
observed in various cold-atom experiments. In this article, we report results
of studies of a class of quantum spin dynamics which are purely driven by zero
point quantum fluctuations of spin collective coordinates. Unlike the usual
mean-field coherent dynamics, quantum fluctuation-controlled spin dynamics or
QFCSD studied here are very sensitive to variation of quantum fluctuations and
can be tuned by four to five order of magnitude using optical lattices. They
have unique dependence on optical lattice potential depths and quadratic Zeeman
fields. QFCSD can be potentially used to calibrate quantum fluctuations and
investigate correlated fluctuations and various universal scaling properties
near quantum critical points.
| [
{
"version": "v1",
"created": "Mon, 9 Jul 2007 19:36:22 GMT"
},
{
"version": "v2",
"created": "Thu, 12 Jul 2007 19:56:18 GMT"
},
{
"version": "v3",
"created": "Fri, 29 Feb 2008 03:01:37 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Song",
"Jun Liang",
"",
"UBC"
],
[
"Zhou",
"Fei",
"",
"UBC"
]
] |
0707.1037 | Wayne Witzel | W. M. Witzel and S. Das Sarma | Concatenated dynamical decoupling in a solid-state spin bath | null | Phys. Rev. B 76, 241303(R) (2007) | 10.1103/PhysRevB.76.241303 | null | cond-mat.mes-hall quant-ph | null | Concatenated dynamical decoupling (CDD) pulse sequences hold much promise as
a strategy to mitigate decoherence in quantum information processing. It is
important to investigate the actual performance of these dynamical decoupling
strategies in real systems that are promising qubit candidates. In this Rapid
Communication, we compute the echo decay of concatenations of the Hahn echo
sequence for a solid-state electronic spin qubit in a nuclear spin bath using a
cluster expansion technique. We find that each level of concatenation reverses
the effect of successive levels of intrabath fluctuations. On the one hand,
this advances CDD as a versatile and realistic decoupling strategy. On the
other hand, this invalidates, as overly optimistic, results of the simple pair
approximation used previously to study restoration, through CDD, of coherence
lost to a mesoscopic spin bath.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 19:42:26 GMT"
},
{
"version": "v2",
"created": "Thu, 13 Dec 2007 18:42:32 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Witzel",
"W. M.",
""
],
[
"Sarma",
"S. Das",
""
]
] |
0707.1038 | Paul Koerber | Paul Koerber and Luca Martucci | From ten to four and back again: how to generalize the geometry | LaTeX, 47 pages, v2, references, hyperref added, v3, correcting small
inaccuracies in eqs. (2.6a) and (5.16) | JHEP 0708:059,2007 | 10.1088/1126-6708/2007/08/059 | MPP-2007-92, KUL-TF-07/12 | hep-th | null | We discuss the four-dimensional N=1 effective approach in the study of warped
type II flux compactifications with SU(3)x SU(3)-structure to AdS_4 or flat
Minkowski space-time. The non-trivial warping makes it natural to use a
supergravity formulation invariant under local complexified Weyl
transformations. We obtain the classical superpotential from a standard
argument involving domain walls and generalized calibrations and show how the
resulting F-flatness and D-flatness equations exactly reproduce the full
ten-dimensional supersymmetry equations. Furthermore, we consider the effect of
non-perturbative corrections to this superpotential arising from gaugino
condensation or Euclidean D-brane instantons. For the latter we derive the
supersymmetry conditions in N=1 flux vacua in full generality. We find that the
non-perturbative corrections induce a quantum deformation of the internal
generalized geometry. Smeared instantons allow to understand KKLT-like AdS
vacua from a ten-dimensional point of view. On the other hand, non-smeared
instantons in IIB warped Calabi-Yau compactifications 'destabilize' the
Calabi-Yau complex structure into a genuine generalized complex one. This
deformation gives a geometrical explanation of the non-trivial superpotential
for mobile D3-branes induced by the non-perturbative corrections.
| [
{
"version": "v1",
"created": "Mon, 9 Jul 2007 09:54:15 GMT"
},
{
"version": "v2",
"created": "Tue, 31 Jul 2007 11:29:42 GMT"
},
{
"version": "v3",
"created": "Thu, 22 Nov 2007 12:01:10 GMT"
}
] | 2009-11-18T00:00:00 | [
[
"Koerber",
"Paul",
""
],
[
"Martucci",
"Luca",
""
]
] |
0707.1039 | Paul Tupper | P. F. Tupper, Martin Grant | Phase Field Crystals as a Coarse-Graining in Time of Molecular Dynamics | 5 pages, 4 figures, typos corrected, more explanation in parts,
equilib vs non-equilib clarified | null | 10.1209/0295-5075/81/40007 | null | cond-mat.mtrl-sci | null | Phase field crystals (PFC) are a tool for simulating materials at the atomic
level. They combine the small length-scale resolution of molecular dynamics
(MD) with the ability to simulate dynamics on mesoscopic time scales. We show
how PFC can be interpreted as the result of applying coarse-graining in time to
the microscopic density field of molecular dynamics simulations. We take the
form of the free energy for the phase field from the classical density
functional theory of inhomogeneous liquids and then choose coefficients to
match the structure factor of the time coarse-grained microscopic density
field. As an example, we show how to construct a PFC free energy for Weber and
Stillinger's two-dimensional square crystal potential which models a system of
proteins suspended in a membrane.
| [
{
"version": "v1",
"created": "Mon, 9 Jul 2007 18:49:58 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Jul 2007 15:52:20 GMT"
},
{
"version": "v3",
"created": "Fri, 21 Dec 2007 19:54:41 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Tupper",
"P. F.",
""
],
[
"Grant",
"Martin",
""
]
] |
0707.1040 | Andrew Norris | Andrew N. Norris | Diffuse wave density and directionality in anisotropic solids | 11 pages, 2 figures | Journal of the Acoustical Society of America, 123, 3, 1399-1408
(2008) | 10.1121/1.2836755 | null | cond-mat.mtrl-sci | null | Several general results are derived for diffuse waves in anisotropic solids,
including concise expressions for the modal density per unit volume and for the
participation factor matrix G. The latter is a second order tensor which
describes the orientational distribution of diffuse wave or reverberant energy,
and reduces to the identity I under isotropy. Calculations of G for a variety
of example materials show significant deviation from I even under moderate
levels of anisotropy.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 20:31:59 GMT"
},
{
"version": "v2",
"created": "Sun, 4 Nov 2007 00:46:41 GMT"
}
] | 2008-04-15T00:00:00 | [
[
"Norris",
"Andrew N.",
""
]
] |
0707.1041 | Mario Garavaglia | Leopoldo Garavaglia and Mario Garavaglia | On the location and classification of all prime numbers | 15 pages, 8 tables, no figures | null | null | null | math.GM | null | We will describe an algorithm to arrange all the positive and negative
integer numbers. This array of numbers permits grouping them in six different
Classes, $\alpha$, $\beta$, $\gamma$, $\delta$, $\epsilon$, and $\zeta$.
Particularly, numbers belong to Class $\alpha$ are defined as $\alpha=1+6 n$,
and those of Class $\beta$, as $\beta=5+6n$, where
$n=0,\pm1,\pm2,\pm3,\pm4,...$ These two Classes $\alpha$ and $\beta$,contain:
i) all prime numbers, except + 2, -2 and $\pm$3, which belong to $\epsilon$,
$\delta$, and $\gamma$ Classes, respectively, and ii) all the other odd
numbers, except those that are multiple of $\pm$3, according to the sequence
$\pm$9, $\pm$15, $\pm$21, $\pm$27, ... Besides, products between numbers of the
Class $\alpha$, and also those between numbers of the Class $\beta$, generates
numbers belonging to the Class $\alpha$. On the other side, products between
numbers of Class $\alpha$ with numbers of Class $\beta$, result in numbers of
Class $\beta$. Then, both Classes $\alpha$ and $\beta$ include: i) all the
prime numbers except $\pm$2 and $\pm$3, and ii) all the products between
$\alpha$ numbers, as $\alpha\cdot\alpha^{\prime}$; all the products between
$\beta$ numbers, as $\beta\cdot\beta^{\prime}$; and also all the products
between numbers of Classes $\alpha$ and $\beta$, as $\alpha\cdot\beta$, which
necessarily are composite numbers, whose factorization is completely
determined.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 20:33:03 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Garavaglia",
"Leopoldo",
""
],
[
"Garavaglia",
"Mario",
""
]
] |
0707.1042 | Arti Chamoli | Arti Chamoli and C. M. Bhandari | Grover's algorithm based multi-qubit secret sharing scheme | 14 pages, 2 figures, 2 tables | null | null | null | quant-ph | null | Some of the secret sharing schemes having unique quantum features like
parallelism and entanglement are supposed to be relatively secure. Different
schemes proposed by various researchers over the years have features which
could be specific to the nature and need of a situation. Following Hsu's
proposed scheme we propose a secret sharing scheme using Grover's search
algorithm for a four qubit system with several marked states. Further, the
scheme has been generalised to an n-qubit syatem.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 20:54:15 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Chamoli",
"Arti",
""
],
[
"Bhandari",
"C. M.",
""
]
] |
0707.1043 | Ada Rubin | The BABAR Collaboration: B. Aubert, et al | Observation of tree-level B decays with $s\bar{s}$ Production from Gluon
Radiation | 7 pages, 9 postscript figures, submitted to PRL | Phys.Rev.Lett.100:171803,2008 | 10.1103/PhysRevLett.100.171803 | null | hep-ex | null | We report on our search for $B^- \to D^{(*)+}_s K^- \pi^-$, $\bar{B^0} \to
D_s^{(*)+} K_S^0 \pi^-$, and $B^- \to D^{(*)+}_s K^- K^-$ decays in 383 million
$\FourS \to B \Bbar$ events collected by the Babar detector at the PEP2
asymmetric-energy $B$-factory. The decays proceed via a tree-level $b\to c$
quark transition in which a gluon radiates into an $s\bar{s}$ pair. Their
branching fractions are measured to be ${\cal B}(B^- \to D^+_s K^- \pi^-) =
(2.02 \pm 0.13_{stat} \pm 0.38_{syst}) \times 10^{-4},$ ${\cal B}(B^- \to
D^{*+}_s K^- \pi^-)= (1.67 \pm 0.16_{stat} \pm 0.35_{syst}) \times 10^{-4},$
${\cal B}(\bar{B^0} \to D_s^{+} K_S^0 \pi^-)= (0.55 \pm 0.13_{stat} \pm
0.10_{syst}) \times 10^{-4},$ and ${\cal B}(B^- \to D_s^{+} K^- K^-) = (0.11
\pm 0.04_{stat} \pm 0.02_{syst}) \times 10^{-4}$. Upper limits at the 90% C.L.
are set on ${\cal B}(\bar{B^0} \to D_s^{*+} K_S^0 \pi^-)< 0.55 \times 10^{-4}$
and ${\cal B}(B^- \to D_s^{*+} K^- K^-) < 0.15 \times 10^{-4}$. We present
evidence that the invariant mass distributions of $D^{(*)+}_s K^-$ pairs from
$B^- \to D^{(*)+}_s K^- \pi^-$ decays are inconsistent with the phase-space
model, suggesting the presence of charm resonances lying below the $D^{(*)+}_s
K^-$ threshold.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 20:37:20 GMT"
},
{
"version": "v2",
"created": "Mon, 23 Jul 2007 19:24:13 GMT"
},
{
"version": "v3",
"created": "Fri, 15 Feb 2008 23:44:09 GMT"
}
] | 2010-04-12T00:00:00 | [
[
"The BABAR Collaboration",
"",
""
],
[
"Aubert",
"B.",
""
]
] |
0707.1044 | Kevin France | Kevin France (1), Aki Roberge (2), Roxana E. Lupu (3), Seth Redfield
(4), and Paul D. Feldman (3) (1-CITA/U Toronto, 2-NASA GSFC, 3-JHU, 4-U
Texas-Austin) | A Low-Mass H2 Component to the AU Microscopii Circumstellar Disk | ApJ, accepted. 9 pages, 4 figures, emulateapj | null | 10.1086/521348 | null | astro-ph | null | We present a determination of the molecular gas mass in the AU Microscopii
circumstellar disk. Direct detection of a gas component to the AU Mic disk has
proven elusive, with upper limits derived from ultraviolet absorption line and
submillimeter CO emission studies. Fluorescent emission lines of H2, pumped by
the OVI 1032 resonance line through the C-X (1 -- 1) Q(3) 1031.87 \AA\
transition, are detected by the Far Ultraviolet Spectroscopic Explorer. These
lines are used to derive the H2 column density associated with the AU Mic
system. The derived column density is in the range N(H2) = 1.9 x 10^{17} - 2.8
x 10^{15} cm^{-2}, roughly two orders of magnitude lower than the upper limit
inferred from absorption line studies. This range of column densities reflects
the range of H2 excitation temperature consistent with the observations, T(H2)
= 800 -- 2000 K, derived from the presence of emission lines excited by OVI in
the absence of those excited by LyA. Within the observational uncertainties,
the data are consistent with the H2 gas residing in the disk. The inferred
N(H2) range corresponds to H2-to-dust ratios of < 1/30:1 and a total M(H2) =
4.0 x 10^{-4} - 5.8 x 10^{-6} Earth masses. We use these results to predict the
intensity of the associated rovibrational emission lines of H2 at infrared
wavelengths covered by ground-based instruments, HST-NICMOS, and the
Spitzer-IRS.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 20:42:09 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"France",
"Kevin",
""
],
[
"Roberge",
"Aki",
""
],
[
"Lupu",
"Roxana E.",
""
],
[
"Redfield",
"Seth",
""
],
[
"Feldman",
"Paul D.",
""
]
] |
0707.1045 | Nacho Pascual | I. Fernandez-Torrente, S. Monturet, K.J. Franke, J. Fraxedas, N.
Lorente, and J.I. Pascual | Long-range repulsive interaction between TTF molecules on a metal
surface induced by charge transfer | null | Phys. Rev. Lett. 99, 176103 (2007) | 10.1103/PhysRevLett.99.176103 | null | cond-mat.mtrl-sci | null | The low-coverage adsorption of a molecular electron donor,
tetrathiafulvalene, on Au(111) is characterized by the spontaneous formation of
superlattice of monomers, whose spacing exceeds the equilibrium distance of
non-covalent interactions and depends on coverage. The origin of this peculiar
growth mode is due to a long-range repulsive interaction between molecules. The
analysis of molecular-pair distributions obtained by scanning tunneling
microscopy measurements permits us to determine that the nature of TTF
intermolecular interactions on Au (111) is electrostatic. A repulsion between
molecules is caused by the accumulation of charge due to electron donation into
the metal surface, as pictured through density functional theory calculations.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 21:08:25 GMT"
}
] | 2008-02-11T00:00:00 | [
[
"Fernandez-Torrente",
"I.",
""
],
[
"Monturet",
"S.",
""
],
[
"Franke",
"K. J.",
""
],
[
"Fraxedas",
"J.",
""
],
[
"Lorente",
"N.",
""
],
[
"Pascual",
"J. I.",
""
]
] |
0707.1046 | Elizabeth McGrath | Elizabeth J. McGrath, Alan Stockton, and Gabriela Canalizo | Stellar Populations of Luminous Evolved Galaxies at z~1.5 | 10 pages, 3 figures (2 in color), accepted for publication in ApJ | Astrophys.J.669:241-250,2007 | 10.1086/521433 | null | astro-ph | null | Observational evidence has been mounting over the past decade that at least
some luminous (~2 L*) galaxies have formed nearly all of their stars within a
short period of time only 1-2x10^9 years after the Big Bang. These are examples
of the first major episodes of star formation in the Universe and provide
insights into the formation of the earliest massive galaxies. We have examined
in detail the stellar populations of six z~1.5 galaxies that appear to be
passively evolving, using both ground and space-based photometry covering
rest-frame UV to visible wavelengths. In addition, we have obtained
medium-resolution spectroscopy for five of the six galaxies, covering the
rest-frame UV portion of the spectrum. Spectral synthesis modeling for four of
these galaxies favors a single burst of star formation more than 1 Gyr before
the observed epoch. The other two exhibit slightly younger ages with a higher
dust content and evidence for a small contribution from either recent star
formation or active nuclei. The implied formation redshifts for the oldest of
these sources are consistent with previous studies of passive galaxies at high
redshift, and improved stellar modeling has shown these results to be quite
robust. It now seems clear that any valid galaxy formation scenario must be
able to account for these massive (2x10^11 M_sun) galaxies at very early times
in the Universe.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 21:02:27 GMT"
}
] | 2010-11-11T00:00:00 | [
[
"McGrath",
"Elizabeth J.",
""
],
[
"Stockton",
"Alan",
""
],
[
"Canalizo",
"Gabriela",
""
]
] |
0707.1047 | James Stotz | J. A. H. Stotz, P. V. Santos, R. Hey, K. H. Ploog | Mesoscopic spin confinement during acoustically induced transport | 10 pages, 2 figures | null | 10.1038/nmat1430 | null | cond-mat.mes-hall cond-mat.mtrl-sci | null | Long coherence lifetimes of electron spins transported using moving potential
dots are shown to result from the mesoscopic confinement of the spin vector.
The confinement dimensions required for spin control are governed by the
characteristic spin-orbit length of the electron spins, which must be larger
than the dimensions of the dot potential. We show that the coherence lifetime
of the electron spins is independent of the local carrier densities within each
potential dot and that the precession frequency, which is determined by the
Dresselhaus contribution to the spin-orbit coupling, can be modified by varying
the sample dimensions resulting in predictable changes in the spin-orbit length
and, consequently, in the spin coherence lifetime.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 21:04:35 GMT"
}
] | 2019-10-29T00:00:00 | [
[
"Stotz",
"J. A. H.",
""
],
[
"Santos",
"P. V.",
""
],
[
"Hey",
"R.",
""
],
[
"Ploog",
"K. H.",
""
]
] |
0707.1048 | Serge Tabachnikov | Dmitry Fuchs, Serge Tabachnikov | Self-dual polygons and self-dual curves | null | null | null | null | math.DG | null | We study projectively self-dual polygons and curves in the projective plane.
Our results provide a partial answer to problem No 1994-17 in the book of
Arnold's problems.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 21:06:24 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Fuchs",
"Dmitry",
""
],
[
"Tabachnikov",
"Serge",
""
]
] |
0707.1049 | Lucian Covaci | Lucian Covaci and Mona Berciu | Holstein polaron: the effect of multiple phonon modes | null | Europhysics Lett. 80, 67001 (2007) | 10.1209/0295-5075/80/67001 | null | cond-mat.supr-con cond-mat.str-el | null | We generalize the Momentum Average approximations MA$^{(0)}$ and MA$^{(1)}$
to study the effects of coupling to multiple optical phonons on the properties
of a Holstein polaron. As for a single phonon mode, these approximations are
numerically very efficient. They become exact for very weak or very strong
couplings, and are highly accurate in the intermediate regimes, {\em e.g.} the
spectral weights obey exactly the first six, respectively eight, sum rules. Our
results show that the effect on ground-state properties is cumulative in
nature. In particular, if the effective coupling to one mode is much larger
than to the others, this mode effectively determines the GS properties.
However, even very weak coupling to a second phonon mode has important
non-perturbational effects on the higher energy spectrum, in particular on the
dispersion and the phonon statistics of the polaron band.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 21:14:41 GMT"
}
] | 2008-11-06T00:00:00 | [
[
"Covaci",
"Lucian",
""
],
[
"Berciu",
"Mona",
""
]
] |
0707.1050 | Elizabeth McGrath | Elizabeth J. McGrath, Alan Stockton, Gabriela Canalizo, Masanori Iye,
Toshinori Maihara | Morphologies and Color Gradients of Luminous Evolved Galaxies at z~1.5 | 16 pages, 9 figures (8 in color), accepted for publication in ApJ | Astrophys.J.682:303-318,2008 | 10.1086/589631 | null | astro-ph | null | We have examined in detail the morphologies of seven z~1.5 passively evolving
luminous red galaxies using high resolution HST NICMOS and ACS imaging data.
Almost all of these galaxies appear to be relaxed systems, with smooth
morphologies at both rest-frame UV and visible wavelengths. Previous results
from spectral synthesis modeling favor a single burst of star formation more
than 1 Gyr before the observed epoch. The prevalence of old stellar
populations, however, does not correlate exclusively with early-type
morphologies as it does in the local universe; the light profiles for some of
these galaxies appear to be dominated by massive exponential disks. This
evidence for massive old disks, along with the apparent uniformity of stellar
age across the disk, suggests formation by a mechanism better described as a
form of monolithic collapse than as a hierarchical merger. These galaxies could
not have undergone a single major merging event since the bulk of their stars
were formed, more than 1 Gyr earlier. There is at least one case, however, that
appears to be undergoing a "dry merger", which may be an example of the process
that converts these unusual galaxies into the familiar spheroids that dominate
galaxies comprising old stellar populations at the present epoch.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 21:12:59 GMT"
},
{
"version": "v2",
"created": "Wed, 23 Apr 2008 23:31:30 GMT"
}
] | 2008-11-07T00:00:00 | [
[
"McGrath",
"Elizabeth J.",
""
],
[
"Stockton",
"Alan",
""
],
[
"Canalizo",
"Gabriela",
""
],
[
"Iye",
"Masanori",
""
],
[
"Maihara",
"Toshinori",
""
]
] |
0707.1051 | Mark Braverman | Mark Braverman, Elchanan Mossel | Noisy Sorting Without Resampling | null | null | null | null | cs.DS | null | In this paper we study noisy sorting without re-sampling. In this problem
there is an unknown order $a_{\pi(1)} < ... < a_{\pi(n)}$ where $\pi$ is a
permutation on $n$ elements. The input is the status of $n \choose 2$ queries
of the form $q(a_i,x_j)$, where $q(a_i,a_j) = +$ with probability at least
$1/2+\ga$ if $\pi(i) > \pi(j)$ for all pairs $i \neq j$, where $\ga > 0$ is a
constant and $q(a_i,a_j) = -q(a_j,a_i)$ for all $i$ and $j$. It is assumed that
the errors are independent. Given the status of the queries the goal is to find
the maximum likelihood order. In other words, the goal is find a permutation
$\sigma$ that minimizes the number of pairs $\sigma(i) > \sigma(j)$ where
$q(\sigma(i),\sigma(j)) = -$. The problem so defined is the feedback arc set
problem on distributions of inputs, each of which is a tournament obtained as a
noisy perturbations of a linear order. Note that when $\ga < 1/2$ and $n$ is
large, it is impossible to recover the original order $\pi$.
It is known that the weighted feedback are set problem on tournaments is
NP-hard in general. Here we present an algorithm of running time
$n^{O(\gamma^{-4})}$ and sampling complexity $O_{\gamma}(n \log n)$ that with
high probability solves the noisy sorting without re-sampling problem. We also
show that if $a_{\sigma(1)},a_{\sigma(2)},...,a_{\sigma(n)}$ is an optimal
solution of the problem then it is ``close'' to the original order. More
formally, with high probability it holds that $\sum_i |\sigma(i) - \pi(i)| =
\Theta(n)$ and $\max_i |\sigma(i) - \pi(i)| = \Theta(\log n)$.
Our results are of interest in applications to ranking, such as ranking in
sports, or ranking of search items based on comparisons by experts.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 21:30:24 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Braverman",
"Mark",
""
],
[
"Mossel",
"Elchanan",
""
]
] |
0707.1052 | Bruce E. Sagan | Bruce E. Sagan (Michigan State U.) | Compositions inside a rectangle and unimodality | 9 pages, 1 figure, see related papers at
http://www.math.msu.edu/~sagan | null | null | null | math.CO | null | Let c^{k,l}(n) be the number of compositions (ordered partitions) of the
integer n whose Ferrers diagram fits inside a k-by-l rectangle. The purpose of
this note is to give a simple, algebraic proof of a conjecture of Vatter that
the sequence c^{k,l}(0), c^{k,l}(1), ..., c^{k,l}(kl) is unimodal. The problem
of giving a combinatorial proof of this fact is discussed, but is still open.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 22:07:31 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Sagan",
"Bruce E.",
"",
"Michigan State U."
]
] |
0707.1053 | Sudhir Kumar Singh | Sudhir Kumar Singh, Vwani P. Roychowdhury, Milan Bradonji\'c, Behnam
A. Rezaei | Exploration via design and the cost of uncertainty in keyword auctions | 19 pages, presentation improved, references added, title changed | null | null | null | cs.GT | null | We present a deterministic exploration mechanism for sponsored search
auctions, which enables the auctioneer to learn the relevance scores of
advertisers, and allows advertisers to estimate the true value of clicks
generated at the auction site. This exploratory mechanism deviates only
minimally from the mechanism being currently used by Google and Yahoo! in the
sense that it retains the same pricing rule, similar ranking scheme, as well
as, similar mathematical structure of payoffs. In particular, the estimations
of the relevance scores and true-values are achieved by providing a chance to
lower ranked advertisers to obtain better slots. This allows the search engine
to potentially test a new pool of advertisers, and correspondingly, enables new
advertisers to estimate the value of clicks/leads generated via the auction.
Both these quantities are unknown a priori, and their knowledge is necessary
for the auction to operate efficiently. We show that such an exploration policy
can be incorporated without any significant loss in revenue for the auctioneer.
We compare the revenue of the new mechanism to that of the standard mechanism
at their corresponding symmetric Nash equilibria and compute the cost of
uncertainty, which is defined as the relative loss in expected revenue per
impression. We also bound the loss in efficiency, as well as, in user
experience due to exploration, under the same solution concept (i.e. SNE). Thus
the proposed exploration mechanism learns the relevance scores while
incorporating the incentive constraints from the advertisers who are selfish
and are trying to maximize their own profits, and therefore, the exploration is
essentially achieved via mechanism design. We also discuss variations of the
new mechanism such as truthful implementations.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 22:11:17 GMT"
},
{
"version": "v2",
"created": "Fri, 2 Nov 2007 07:02:26 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Singh",
"Sudhir Kumar",
""
],
[
"Roychowdhury",
"Vwani P.",
""
],
[
"Bradonjić",
"Milan",
""
],
[
"Rezaei",
"Behnam A.",
""
]
] |
0707.1054 | David Hilton | D. J. Hilton (1), R. P. Prasankumar (1), S. Fourmaux (2), A. Cavalleri
(3), D. Brassard (2), M. A. El Khakani (2), J. C. Kieffer (2), A. J. Taylor
(1), and R. D. Averitt (1) ((1) Center for Integrated Nanotechnologies, Los
Alamos National Laboratory, Los Alamos, NM (2) Universit\'e du Qu\'ebec,
INRS-\'Energie et Mat\'eriaux et T\'el\'ecommunications, Varennes, Qu\'ebec,
Canada (3) Department of Physics, University of Oxford, Oxford, United
Kingdom) | Softening of the insulating phase near Tc for the photo-induced
insulator-to-metal phase transition in vanadium dioxide | accepted for publication in Physical Review Letters | null | 10.1103/PhysRevLett.100.019906 | null | cond-mat.str-el cond-mat.mtrl-sci | null | We use optical-pump terahertz-probe spectroscopy to investigate the
near-threshold behavior of the photoinduced insulator-to-metal (IM) transition
in vanadium dioxide thin films. Upon approaching Tc a reduction in the fluence
required to drive the IM transition is observed, consistent with a softening of
the insulating state due to an increasing metallic volume fraction (below the
percolation limit). This phase coexistence facilitates the growth of a
homogeneous metallic conducting phase following superheating via
photoexcitation. A simple dynamic model using Bruggeman effective medium theory
describes the observed initial condition sensitivity.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 22:21:07 GMT"
},
{
"version": "v2",
"created": "Wed, 17 Oct 2007 00:38:13 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Hilton",
"D. J.",
""
],
[
"Prasankumar",
"R. P.",
""
],
[
"Fourmaux",
"S.",
""
],
[
"Cavalleri",
"A.",
""
],
[
"Brassard",
"D.",
""
],
[
"Khakani",
"M. A. El",
""
],
[
"Kieffer",
"J. C.",
""
],
[
"Taylor",
"A. J.",
""
],
[
"Averitt",
"R. D.",
""
]
] |
0707.1055 | Konstantin Goulianos | Konstantin Goulianos | Diffractive and Total Cross Sections at Tevatron and LHC | Presented at Hadron Collider Physics Symposium 2006, May 22-26, Duke
University, Durham NC, USA (5 pages, 4 figures) | null | null | null | hep-ex | null | Results from the Fermilab Tevatron pbar-p collider on diffractive and total
cross sections are reviewed with emphasis on physics significance and
properties pointing to expectations at the LHC.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 15:51:36 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Goulianos",
"Konstantin",
""
]
] |
0707.1056 | Fabrizio Canfora | Fabrizio Canfora, Alex Giacomini, Ricardo Troncoso | Black holes, parallelizable horizons and half-BPS states for the
Einstein-Gauss-Bonnet theory in five dimensions | 11 pages, no figures, notation clarified; version accepted for
publication in Physical Review D | Phys.Rev.D77:024002,2008 | 10.1103/PhysRevD.77.024002 | CECS-PHY-07/14 | hep-th gr-qc | null | Exact vacuum solutions with a nontrivial torsion for the
Einstein-Gauss-Bonnet theory in five dimensions are constructed. We consider a
class of static metrics whose spacelike section is a warped product of the real
line with a nontrivial base manifold endowed with a fully antisymmetric
torsion. It is shown requiring solutions of this sort to exist, fixes the
Gauss-Bonnet coupling such that the Lagrangian can be written as a Chern-Simons
form. The metric describes black holes with an arbitrary, but fixed, base
manifold. It is shown that requiring its ground state to possess unbroken
supersymmetries, fixes the base manifold to be locally a parallelized
three-sphere. The ground state turns out to be half-BPS, which could not be
achieved in the absence of torsion in vacuum. The Killing spinors are
explicitly found.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 22:38:23 GMT"
},
{
"version": "v2",
"created": "Thu, 19 Jul 2007 02:30:56 GMT"
},
{
"version": "v3",
"created": "Fri, 16 Nov 2007 16:55:56 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Canfora",
"Fabrizio",
""
],
[
"Giacomini",
"Alex",
""
],
[
"Troncoso",
"Ricardo",
""
]
] |
0707.1057 | Sudhir Kumar Singh | Sudhir Kumar Singh, Vwani P. Roychowdhury, Himawan Gunadhi, Behnam A.
Rezaei | For-profit mediators in sponsored search advertising | 6 pages | null | null | null | cs.GT | null | A mediator is a well-known construct in game theory, and is an entity that
plays on behalf of some of the agents who choose to use its services, while the
rest of the agents participate in the game directly. We initiate a game
theoretic study of sponsored search auctions, such as those used by Google and
Yahoo!, involving {\em incentive driven} mediators. We refer to such mediators
as {\em for-profit} mediators, so as to distinguish them from mediators
introduced in prior work, who have no monetary incentives, and are driven by
the altruistic goal of implementing certain desired outcomes. We show that in
our model, (i) players/advertisers can improve their payoffs by choosing to use
the services of the mediator, compared to directly participating in the
auction; (ii) the mediator can obtain monetary benefit by managing the
advertising burden of its group of advertisers; and (iii) the payoffs of the
mediator and the advertisers it plays for are compatible with the incentive
constraints from the advertisers who do dot use its services. A simple
intuition behind the above result comes from the observation that the mediator
has more information about and more control over the bid profile than any
individual advertiser, allowing her to reduce the payments made to the
auctioneer, while still maintaining incentive constraints. Further, our results
indicate that there are significant opportunities for diversification in the
internet economy and we should expect it to continue to develop richer
structure, with room for different types of agents to coexist.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 03:18:26 GMT"
},
{
"version": "v2",
"created": "Mon, 3 Sep 2007 12:19:30 GMT"
}
] | 2007-09-03T00:00:00 | [
[
"Singh",
"Sudhir Kumar",
""
],
[
"Roychowdhury",
"Vwani P.",
""
],
[
"Gunadhi",
"Himawan",
""
],
[
"Rezaei",
"Behnam A.",
""
]
] |
0707.1058 | Daniel Allcock | Daniel Allcock, James A. Carlson and Domingo Toledo | Hyperbolic geometry and moduli of real cubic surfaces | Major revision, including several new or completely rewritten
sections. 56 pages | null | null | null | math.AG math.GR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Let M_0^R be the moduli space of smooth real cubic surfaces. We show that
each of its components admits a real hyperbolic structure. More precisely, one
can remove some lower-dimensional geodesic subspaces from a real hyperbolic
space H^4 and form the quotient by an arithmetic group to obtain an orbifold
isomorphic to a component of the moduli space. There are five components. For
each we describe the corresponding lattices in PO(4,1). We also derive several
new and several old results on the topology of M_0^R. Let M_s^R be the moduli
space of real cubic surfaces that are stable in the sense of geometric
invariant theory. We show that this space carries a hyperbolic structure whose
restriction to M_0^R is that just mentioned. The corresponding lattice in
PO(4,1), for which we find an explicit fundamental domain, is nonarithmetic.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 22:52:24 GMT"
},
{
"version": "v2",
"created": "Mon, 11 May 2009 18:20:13 GMT"
}
] | 2009-05-11T00:00:00 | [
[
"Allcock",
"Daniel",
""
],
[
"Carlson",
"James A.",
""
],
[
"Toledo",
"Domingo",
""
]
] |
0707.1059 | Alban Ponse | Jan A. Bergstra and Alban Ponse | Projection semantics for rigid loops | 20 pages | null | null | PRG0604 | cs.PL | null | A rigid loop is a for-loop with a counter not accessible to the loop body or
any other part of a program. Special instructions for rigid loops are
introduced on top of the syntax of the program algebra PGA. Two different
semantic projections are provided and proven equivalent. One of these is taken
to have definitional status on the basis of two criteria: `normative semantic
adequacy' and `indicative algorithmic adequacy'.
| [
{
"version": "v1",
"created": "Fri, 6 Jul 2007 23:58:45 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Bergstra",
"Jan A.",
""
],
[
"Ponse",
"Alban",
""
]
] |
0707.1060 | Valerie Coffman | Valerie R. Coffman, James P. Sethna | Grain boundary energies and cohesive strength as a function of geometry | 12 pages, 19 figures, changed title | null | 10.1103/PhysRevB.77.144111 | null | cond-mat.mtrl-sci | null | Cohesive laws are stress-strain curves used in finite element calculations to
describe the debonding of interfaces such as grain boundaries. It would be
convenient to describe grain boundary cohesive laws as a function of the
parameters needed to describe the grain boundary geometry; two parameters in 2D
and 5 parameters in 3D. However, we find that the cohesive law is not a smooth
function of these parameters. In fact, it is discontinuous at geometries for
which the two grains have repeat distances that are rational with respect to
one another. Using atomistic simulations, we extract grain boundary energies
and cohesive laws of grain boundary fracture in 2D with a Lennard-Jones
potential for all possible geometries which can be simulated within periodic
boundary conditions with a maximum box size. We introduce a model where grain
boundaries are represented as high symmetry boundaries decorated by extra
dislocations. Using it, we develop a functional form for the symmetric grain
boundary energies, which have cusps at all high symmetry angles. We also find
the asymptotic form of the fracture toughness near the discontinuities at high
symmetry grain boundaries using our dislocation decoration model.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 00:52:14 GMT"
},
{
"version": "v2",
"created": "Thu, 6 Mar 2008 21:59:01 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Coffman",
"Valerie R.",
""
],
[
"Sethna",
"James P.",
""
]
] |
0707.1061 | Jirina Stone | J.R.Stone, G.Goldring, N.J.Stone, N.Severijns, M.Hass, D.Zakoucky,
T.Giles, U.K\"oster, I.S.Kraev, S.Lakshmi, M.Lindroos, F.Wauters | Confirmation of Parity Violation in the Gamma Decay of $^{180}Hf^{m}$ | 28 pages, 9 figures, accepted for publication in Physical Review C | Phys.Rev.C76:025502,2007 | 10.1103/PhysRevC.76.025502 | null | nucl-ex | null | This paper reports measurements using the technique of On Line Nuclear
Orientation (OLNO) which reexamine the gamma decay of isomeric $^{\rm
180}$Hf$^{\rm m}$ and specifically the 501 keV 8$^{\rm -}$ -- 6$^{\rm +}$
transition. The irregular admixture of E2 to M2/E3 multipolarity in this
transition, deduced from the forward-backward asymmetry of its angular
distribution, has for decades stood as the prime evidence for parity mixing in
nuclear states. The experiment, based on ion implantation of the newly
developed mass-separated $^{\rm 180}$Hf$^{\rm m}$ beam at ISOLDE, CERN into an
iron foil maintained at millikelvin temperatures, produces higher degrees of
polarization than were achieved in previous studies of this system. The value
found for the E2/M2 mixing ratio, $\epsilon$ = -0.0324(16)(17), is in close
agreement with the previous published average value $\epsilon$ = - 0.030(2), in
full confirmation of the presence of the irregular E2 admixture in the 501 keV
transition. The temperature dependence of the forward-backward asymmetry has
been measured over a more extended range of nuclear polarization than
previously possible, giving further evidence for parity mixing of the 8$^{\rm
-}$ and 8$^{\rm +}$ levels and the deduced E2/M2 mixing ratio.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 01:10:43 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Stone",
"J. R.",
""
],
[
"Goldring",
"G.",
""
],
[
"Stone",
"N. J.",
""
],
[
"Severijns",
"N.",
""
],
[
"Hass",
"M.",
""
],
[
"Zakoucky",
"D.",
""
],
[
"Giles",
"T.",
""
],
[
"Köster",
"U.",
""
],
[
"Kraev",
"I. S.",
""
],
[
"Lakshmi",
"S.",
""
],
[
"Lindroos",
"M.",
""
],
[
"Wauters",
"F.",
""
]
] |
0707.1062 | Janna Levin | Brian R. Greene and Janna Levin | Dark Energy and Stabilization of Extra Dimensions | Comments added, typo corrected, version to be published in JHEP | JHEP 0711:096,2007 | 10.1088/1126-6708/2007/11/096 | null | hep-th astro-ph gr-qc | null | We discuss the role Casimir energies may play in addressing issues of moduli
stabilization and dark energy. In particular, we examine a (non-supersymmetric)
brane world scenario with toroidal extra dimensions in which Casimir energies
of bulk fields generate a stabilizing potential for the toroidal volume while
driving accelerated expansion in the non-compact directions. We speculate that
such a scenario might establish a link between asymmetric topology and
asymmetric geometry; that is, asymmetric topology could be linked to the
hierarchy between large and small dimensions.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 01:34:16 GMT"
},
{
"version": "v2",
"created": "Mon, 3 Dec 2007 17:47:08 GMT"
}
] | 2009-11-18T00:00:00 | [
[
"Greene",
"Brian R.",
""
],
[
"Levin",
"Janna",
""
]
] |
0707.1063 | Animesh Kumar | Animesh Kumar, Prakash Ishwar, and Kannan Ramchandran | High-resolution distributed sampling of bandlimited fields with
low-precision sensors | 17 pages, 6 figures; paper withdrawn from IEEE Transactions on Signal
Processing and re-submitted to the IEEE Transactions on Information Theory | null | 10.1109/TIT.2010.2090194 | null | cs.IT math.IT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The problem of sampling a discrete-time sequence of spatially bandlimited
fields with a bounded dynamic range, in a distributed,
communication-constrained, processing environment is addressed. A central unit,
having access to the data gathered by a dense network of fixed-precision
sensors, operating under stringent inter-node communication constraints, is
required to reconstruct the field snapshots to maximum accuracy. Both
deterministic and stochastic field models are considered. For stochastic
fields, results are established in the almost-sure sense. The feasibility of
having a flexible tradeoff between the oversampling rate (sensor density) and
the analog-to-digital converter (ADC) precision, while achieving an exponential
accuracy in the number of bits per Nyquist-interval per snapshot is
demonstrated. This exposes an underlying ``conservation of bits'' principle:
the bit-budget per Nyquist-interval per snapshot (the rate) can be distributed
along the amplitude axis (sensor-precision) and space (sensor density) in an
almost arbitrary discrete-valued manner, while retaining the same (exponential)
distortion-rate characteristics. Achievable information scaling laws for field
reconstruction over a bounded region are also derived: With N one-bit sensors
per Nyquist-interval, $\Theta(\log N)$ Nyquist-intervals, and total network
bitrate $R_{net} = \Theta((\log N)^2)$ (per-sensor bitrate $\Theta((\log
N)/N)$), the maximum pointwise distortion goes to zero as $D = O((\log N)^2/N)$
or $D = O(R_{net} 2^{-\beta \sqrt{R_{net}}})$. This is shown to be possible
with only nearest-neighbor communication, distributed coding, and appropriate
interpolation algorithms. For a fixed, nonzero target distortion, the number of
fixed-precision sensors and the network rate needed is always finite.
| [
{
"version": "v1",
"created": "Mon, 9 Jul 2007 16:17:20 GMT"
},
{
"version": "v2",
"created": "Mon, 30 Jul 2007 17:36:43 GMT"
},
{
"version": "v3",
"created": "Sat, 25 Aug 2007 20:40:03 GMT"
},
{
"version": "v4",
"created": "Thu, 11 Dec 2008 01:59:46 GMT"
}
] | 2016-11-18T00:00:00 | [
[
"Kumar",
"Animesh",
""
],
[
"Ishwar",
"Prakash",
""
],
[
"Ramchandran",
"Kannan",
""
]
] |
0707.1064 | Krishna Srikanth Gomadam | Krishna S. Gomadam and Syed A. Jafar | The Effect of Noise Correlation in AF Relay Networks | 32 pages | null | null | null | cs.IT math.IT | null | In wireless relay networks, noise at the relays can be correlated possibly
due to common interference or noise propagation from preceding hops. In this
work we consider a parallel relay network with noise correlation. For the relay
strategy of amplify-and-forward (AF), we determine the optimal rate maximizing
relay gains when correlation knowledge is available at the relays. The effect
of correlation on the performance of the relay networks is analyzed for the
cases where full knowledge of correlation is available at the relays and when
there is no knowledge about the correlation structure. Interestingly we find
that, on the average, noise correlation is beneficial regardless of whether the
relays know the noise covariance matrix or not. However, the knowledge of
correlation can greatly improve the performance. Typically, the performance
improvement from correlation knowledge increases with the relay power and the
number of relays. With perfect correlation knowledge the system is capable of
canceling interference if the number of interferers is less than the number of
relays.
For a dual-hop multiple access parallel network, we obtain closed form
expressions for the maximum sum-rate and the optimal relay strategy. The relay
optimization for networks with three hops is also considered. For any relay
gains for the first stage relays, this represents a parallel relay network with
correlated noise. Based on the result of two hop networks with noise
correlation, we propose an algorithm for solving the relay optimization problem
for three-hop networks.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 18:43:22 GMT"
}
] | 2007-07-13T00:00:00 | [
[
"Gomadam",
"Krishna S.",
""
],
[
"Jafar",
"Syed A.",
""
]
] |
0707.1065 | Vladimir Dzhunushaliev | Vladimir Dzhunushaliev | Connection between some nonperturbative approaches in QCD | 9 pages, 5 fig's | null | null | null | hep-ph | null | The connection between two nonperturbative approaches in quantum
chromodynamics is considered. The first one is based on a collective coordinate
method, the second one on a spin-charge separation. It is shown that both
approaches have some close connection: the existence of two condensates which
are necessary to confinement.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 03:55:09 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Dzhunushaliev",
"Vladimir",
""
]
] |
0707.1066 | Max Chaves | Max Chaves | The quantization of gravity and the vacuum energy of quantum fields | 18 pages & no figures | null | null | null | gr-qc hep-th | null | We construct a unified covariant derivative that contains the sum of an
affine connection and a Yang-Mills field. With it we construct a lagrangian
that is invariant both under diffeomorphisms and Yang-Mills gauge
transformations. We assume that metric and symmetric affine connection are
independent quantities, and make the observation that the metric must be able
to generate curvature, just as the connection, so there should be an extra
tensor similar to Riemann's in the equations but constructed from metrics and
not connections. We find the equations generated by the lagrangian and
introduce the huge natural scale due to the vacuum energy of quantum fields.
This scale allows for a perturbative solution of the equations of motion. We
prove the system has a vacuum state that forces the metricity of the metric and
results in General Relativity for low energies. The vacuum energy of the
quantum fields cancels, becoming unobservable. At very high energies, the
metric does not appear differentiated in the lagrangian and so it is not a
quantum field, just a background classical field. The true quantum fields are
the connections. The theory becomes very similar to a Yang-Mills, with affine
connections taking the place of Yang-Mills vector fields. It should be
renormalizable since it has a coupling constant with no units and correct
propagators after fixing the gauge (diffeomorphisms). The weakness of gravity
turns out to be due to the large vacuum energy of the quantum fields.
| [
{
"version": "v1",
"created": "Mon, 9 Jul 2007 14:35:27 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Chaves",
"Max",
""
]
] |
0707.1067 | Chin-Sheng Wu | Chin-Sheng Wu | Commutation Relations for Double Tensors of Two Equivalent D Electrons | null | null | null | null | math-ph math.MP | null | We apply the Clebsch-Gordan and Racah coefficients to calculate the double
tensors for two equivalent d electrons. We also obtain the commutation
relations for these double tensors and choose certain quantum numbers, which
produce a subgroup. From the root vectors of the commutation relations, we
identify them with Lie algebra B2. Once we have the correct Lie algebra, it is
feasible to use the Wigner-Eckart theorem to find matrix elements for
transition states among atomic spectra or nuclear shell models.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 04:18:51 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Wu",
"Chin-Sheng",
""
]
] |
0707.1068 | Kai Cieliebak | F. Bourgeois, K. Cieliebak, T. Ekholm | A note on Reeb dynamics on the tight 3-sphere | 20 pages, no figures | null | null | null | math.SG math.DS | null | We show that a nondegenerate tight contact form on the 3-sphere has exactly
two simple closed Reeb orbits if and only if the differential in linearized
contact homology vanishes. Moreover, in this case the Floquet multipliers and
Conley-Zehnder indices of the two Reeb orbits agree with those of a suitable
irrational ellipsoid in 4-space.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 04:32:41 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Bourgeois",
"F.",
""
],
[
"Cieliebak",
"K.",
""
],
[
"Ekholm",
"T.",
""
]
] |
0707.1069 | Landon Rabern | Landon Rabern | Coloring and The Lonely Graph | null | null | null | null | math.CO | null | We improve upper bounds on the chromatic number proven independently in
\cite{reedNote} and \cite{ingo}. Our main lemma gives a sufficient condition
for two paths in graph to be completely joined. Using this, we prove that if a
graph has an optimal coloring with more than $\frac{\omega}{2}$ singleton color
classes, then it satisfies $\chi \leq \frac{\omega + \Delta + 1}{2}$. It
follows that a graph satisfying $n - \Delta < \alpha + \frac{\omega - 1}{2}$
must also satisfy $\chi \leq \frac{\omega + \Delta + 1}{2}$, improving the
bounds in \cite{reedNote} and \cite{ingo}. We then give a simple argument
showing that if a graph satisfies $\chi > \frac{n + 3 - \alpha}{2}$, then it
also satisfies $\chi(G) \leq \left\lceil\frac{\omega(G) + \Delta(G) +
1}{2}\right\rceil$. From this it follows that a graph satisfying $n - \Delta <
\alpha + \omega$ also satisfies $\chi(G) \leq \left\lceil\frac{\omega(G) +
\Delta(G) + 1}{2}\right\rceil$ improving the bounds in \cite{reedNote} and
\cite{ingo} even further at the cost of a ceiling. In the next sections, we
generalize our main lemma to constrained colorings (e.g. r-bounded colorings).
We present a generalization of Reed's conjecture to r-bounded colorings and
prove the conjecture for graphs with maximal degree close to their order.
Finally, we outline some applications (in \cite{BorodinKostochka} and
\cite{ColoringWithDoublyCriticalEdge}) of the theory presented here to the
Borodin-Kostochka conjecture and coloring graphs containing a doubly critical
edge.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 04:38:14 GMT"
},
{
"version": "v2",
"created": "Fri, 13 Jul 2007 04:14:12 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Rabern",
"Landon",
""
]
] |
0707.1070 | Dr. Kalobaran Maiti | S.K. Pandey, Ashwani Kumar, S. Patil, V.R.R. Medicherla, R.S. Singh,
K. Maiti, D. Prabhakaran, A.T. Boothroyd, and A.V. Pimpale | Investigation of the spin state of Co in LaCoO3 at room temperature | 7 figures, 2 tables | null | null | null | cond-mat.str-el cond-mat.mtrl-sci | null | We investigate the spin state of LaCoO3 using state-of-the-art photoemission
spectroscopy and ab initio band structure calculations. The GGA+U calculations
provide a good description of the ground state for the experimentally estimated
value of electron correlation strength, U. In addition to the correlation
effect, spin-orbit interaction is observed to play a significant role in the
case of intermediate spin and high spin configurations. The comparison of the
calculated Co 3d and O 2p partial density of states with the experimental
valence band spectra indicates that at room temperature, Co has dominant
intermediate spin state configuration and that the high spin configuration may
not be significant at this temperature. The lineshape of the La 5p and O 2s
core level spectra could be reproduced well within these ab initio
calculations.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 04:58:22 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Pandey",
"S. K.",
""
],
[
"Kumar",
"Ashwani",
""
],
[
"Patil",
"S.",
""
],
[
"Medicherla",
"V. R. R.",
""
],
[
"Singh",
"R. S.",
""
],
[
"Maiti",
"K.",
""
],
[
"Prabhakaran",
"D.",
""
],
[
"Boothroyd",
"A. T.",
""
],
[
"Pimpale",
"A. V.",
""
]
] |
0707.1071 | Yun Lai | Ying Wu, Yun Lai, and Zhao-Qing Zhang | A Dynamical Effective Medium Theory for Elastic Metamaterials | 5 figures, 1 table | null | null | null | cond-mat.mtrl-sci | null | We develop a dynamical effective medium theory to accurately predict the
unusual properties of elastic metamaterials in two dimensions near the resonant
frequencies. The theory shows that the effective bulk modulus, shear modulus,
and mass density can be made negative by choosing proper resonant scatterers,
leading to 8 possible types of wave propagation. The theory not only provides a
convenient tool to search for various metamaterials with desired properties,
but also gives a unified physical picture of these properties. Here we
demonstrate two examples. One possesses large band gaps at low frequencies. The
other exhibits two regions of negative refraction: one for both longitudinal
and transverse waves and the other for longitudinal waves only.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 04:39:24 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Wu",
"Ying",
""
],
[
"Lai",
"Yun",
""
],
[
"Zhang",
"Zhao-Qing",
""
]
] |
0707.1072 | Mario Maican | Mario Maican | A few remarks concerning the geometry of the moduli spaces of semistable
sheaves supported on plane curves of multiplicity four | This paper has been withdrawn by the author due to a crucial error in
the proofs. The error has been corrected and the paper has been expanded in
arXiv:0910.5327 | null | null | null | math.AG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper has been withdrawn by the author due to a crucial error in the
proofs. The error has been corrected and the paper has been expanded in
arXiv:0910.5327
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 06:46:02 GMT"
},
{
"version": "v2",
"created": "Mon, 30 Jul 2007 03:58:04 GMT"
},
{
"version": "v3",
"created": "Thu, 14 Jan 2010 16:51:10 GMT"
}
] | 2010-01-14T00:00:00 | [
[
"Maican",
"Mario",
""
]
] |
0707.1073 | Xavier Leoncini | Romain Bachelard (CPT), Tounsia Benzekri (CPT), Cristel Chandre (CPT),
Xavier Leoncini (CPT), Michel Vittot (CPT) | Targeted mixing in an array of alternating vortices | null | Physical Review E: Statistical, Nonlinear, and Soft Matter Physics
76 (2007) 046217 | 10.1103/PhysRevE.76.046217 | null | nlin.CD | null | Transport and mixing properties of passive particles advected by an array of
vortices are investigated. Starting from the integrable case, it is shown that
a special class of perturbations allows one to preserve separatrices which act
as effective transport barriers, while triggering chaotic advection. In this
setting, mixing within the two dynamical barriers is enhanced while long range
transport is prevented. A numerical analysis of mixing properties depending on
parameter values is performed; regions for which optimal mixing is achieved are
proposed. Robustness of the targeted mixing properties regarding errors in the
applied perturbation are considered, as well as slip/no-slip boundary
conditions for the flow.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 06:53:45 GMT"
},
{
"version": "v2",
"created": "Tue, 30 Oct 2007 07:43:10 GMT"
}
] | 2007-10-30T00:00:00 | [
[
"Bachelard",
"Romain",
"",
"CPT"
],
[
"Benzekri",
"Tounsia",
"",
"CPT"
],
[
"Chandre",
"Cristel",
"",
"CPT"
],
[
"Leoncini",
"Xavier",
"",
"CPT"
],
[
"Vittot",
"Michel",
"",
"CPT"
]
] |
0707.1074 | Matthew R. James | Matthew R. James and John Gough | Quantum Dissipative Systems and Feedback Control Design by
Interconnection | null | null | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The purpose of this paper is to extend J.C. Willems' theory of dissipative
systems to the quantum domain. This general theory, which combines perspectives
from the quantum physics and control engineering communities, provides useful
methods for analysis and design of dissipative quantum systems. We describe the
interaction of the plant and a class of exosystems in general quantum feedback
network terms. Our results include an infinitesimal characterization of the
dissipation property, which generalizes the well-known Positive Real and
Bounded Real Lemmas, and is used to study some properties of quantum
dissipative systems. We also show how to formulate control design problems
using quantum network models, which implements Willems' `control by
interconnection' for open quantum systems. This control design formulation
includes, for example, standard problems of stabilization, regulation, and
robust control.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 07:10:06 GMT"
},
{
"version": "v2",
"created": "Mon, 1 Dec 2008 04:36:56 GMT"
},
{
"version": "v3",
"created": "Thu, 7 May 2009 01:04:34 GMT"
}
] | 2009-05-07T00:00:00 | [
[
"James",
"Matthew R.",
""
],
[
"Gough",
"John",
""
]
] |
0707.1075 | John Kovac | J. M. Kovac and D. Barkats (Caltech) | CMB from the South Pole: Past, Present, and Future | 8 pages, 23 figure panels and photos, invited review for the
Proceedings of the 6th Rencontres du Vietnam 2006 | null | null | null | astro-ph | null | South Pole Station offers a unique combination of high, dry, stable
conditions and well-developed support facilities. Over the past 20 years, a
sequence of increasingly sophisticated CMB experiments at Pole have built on
the experience of early pioneering efforts, producing a number of landmark
contributions to the field. Telescopes at the South Pole were among the first
to make repeated detections of degree-scale CMB temperature anisotropy and to
map out the harmonic structure of its acoustic peaks. More recent achievements
include the first detection of polarization of the CMB and the most precise
measurements of the temperature power spectrum at small angular scales. New CMB
telescopes at the South Pole are now making ultra-deep observations of the
large-scale polarization of the CMB and of its secondary temperature
anisotropies on arcminute scales. These two observing goals represent the
current frontiers of CMB research, focused on constraining Inflation and the
nature of Dark Energy. The South Pole now hosts an array of CMB observing
platforms covering a wide range of angular scales and supporting very long
integration times on the cleanest sky available, and thus should play an
increasing role in pushing these frontiers of CMB research.
| [
{
"version": "v1",
"created": "Mon, 9 Jul 2007 14:03:37 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Kovac",
"J. M.",
"",
"Caltech"
],
[
"Barkats",
"D.",
"",
"Caltech"
]
] |
0707.1076 | Javier Fresan | J. M. Ancochea Bermudez, J. Fresan, J. Sanchez Hernandez | On the variety of two dimensional real associative algebras | 13 pages, 1 figure | null | null | null | math.RA | null | This paper consists of a description of the variety of two dimensional
associative algebras within the framework of Nonstandard Analysis. By
decomposing each algebra in A^2 as sum of a Jordan algebra and a Lie algebra,
we calculate the isomorphism classes of two dimensional real associative
algebras over the field of real numbers and determine the components and the
contractions of the variety.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 08:22:46 GMT"
},
{
"version": "v2",
"created": "Thu, 9 Aug 2007 07:15:48 GMT"
},
{
"version": "v3",
"created": "Fri, 12 Oct 2007 12:17:10 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Bermudez",
"J. M. Ancochea",
""
],
[
"Fresan",
"J.",
""
],
[
"Hernandez",
"J. Sanchez",
""
]
] |
0707.1077 | Giuseppe Bimonte | Giuseppe Bimonte, Enrico Calloni and Luigi Rosa | The gravity of magnetic stresses and energy | 10 pages, final version accepted for publication in PRD | Phys.Rev.D77:044026,2008 | 10.1103/PhysRevD.77.044026 | DSF 2008/3 | gr-qc hep-th | null | In the framework of designing laboratory tests of relativistic gravity, we
investigate the gravitational field produced by the magnetic field of a
solenoid. Observing this field might provide a mean of testing whether stresses
gravitate as predicted by Einstein's theory. A previous study of this problem
by Braginsky, Caves and Thorne predicted that the contribution to the
gravitational field resulting from the stresses of the magnetic field and of
the solenoid walls would cancel the gravitational field produced by the
mass-energy of the magnetic field, resulting in a null magnetically-generated
gravitational force outside the solenoid. They claim that this null result,
once proved experimentally, would demonstrate the stress contribution to
gravity. We show that this result is incorrect, as it arises from an incomplete
analysis of the stresses, which neglects the axial stresses in the walls. Once
the stresses are properly evaluated, we find that the gravitational field
outside a long solenoid is in fact independent of Maxwell and material
stresses, and it coincides with the newtonian field produced by the linear mass
distribution equivalent to the density of magnetic energy stored in a unit
length of the solenoid. We argue that the gravity of Maxwell stress can be
directly measured in the vacuum region inside the solenoid, where the newtonian
noise is absent in principle, and the gravity generated by Maxwell stresses is
not screened by the negative gravity of magnetic-induced stresses in the
solenoid walls.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 10:30:37 GMT"
},
{
"version": "v2",
"created": "Wed, 16 Jan 2008 09:49:41 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Bimonte",
"Giuseppe",
""
],
[
"Calloni",
"Enrico",
""
],
[
"Rosa",
"Luigi",
""
]
] |
0707.1078 | Vito Domenico Pietro Servedio | Paolo Butt\`a, Fiammetta Cerreti, Vito D. P. Servedio, Livio Triolo | Molecular Dynamics Simulation of Vascular Network Formation | 10 pages, 3 figures, 2 of which composite with 8 pictures each.
Accepted on J.Stat.Mech. (2009). Appeared at the poster session of
StatPhys23, Genoa, Italy, July 13 (2007) | Journal of Statistical Mechanics: Theory and Experiments (2009)
P05013, 10 pages | 10.1088/1742-5468/2009/05/P05013 | Roma01.Math.MP | cond-mat.soft q-bio.CB | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Endothelial cells are responsible for the formation of the capillary blood
vessel network. We describe a system of endothelial cells by means of
two-dimensional molecular dynamics simulations of point-like particles. Cells'
motion is governed by the gradient of the concentration of a chemical substance
that they produce (chemotaxis). The typical time of degradation of the chemical
substance introduces a characteristic length in the system. We show that
point-like model cells form network resembling structures tuned by this
characteristic length, before collapsing altogether. Successively, we improve
the non-realistic point-like model cells by introducing an isotropic strong
repulsive force between them and a velocity dependent force mimicking the
observed peculiarity of endothelial cells to preserve the direction of their
motion (persistence). This more realistic model does not show a clear network
formation. We ascribe this partial fault in reproducing the experiments to the
static geometry of our model cells that, in reality, change their shapes by
elongating toward neighboring cells.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 09:30:22 GMT"
},
{
"version": "v2",
"created": "Wed, 29 Apr 2009 13:23:59 GMT"
}
] | 2022-12-22T00:00:00 | [
[
"Buttà",
"Paolo",
""
],
[
"Cerreti",
"Fiammetta",
""
],
[
"Servedio",
"Vito D. P.",
""
],
[
"Triolo",
"Livio",
""
]
] |
0707.1079 | M Hossain Ali | M. Hossain Ali | Charged Particles' Tunneling from Hot-NUT-Kerr-Newman-Kasuya Spacetime | To appear in: Int. J. Theor. Phys | Int J Theor Phys (2008) 47: 2203--2217 | 10.1007/s10773-008-9652-y | null | gr-qc hep-th | null | We study the Hawking radiation as charged particles' tunneling across the
horizons of the Hot-NUT-Kerr-Newman-Kasuya spacetime by considering the
spacetime background as dynamical and incorporating the self-gravitation effect
of the emitted particles when the energy conservation, the angular momentum
conservation, and the electric charge conservation are taken into account. Our
result shows that the tunneling rate is related to the change of
Bekenstein-Hawking entropy and the radiant spectrum is not pure thermal, but is
consistent with an underlying unitary theory. The emission process is a
reversible one, and the information is preserved as a natural result of the
first law of black hole thermodynamics.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 10:18:18 GMT"
},
{
"version": "v2",
"created": "Sat, 10 Nov 2007 06:59:03 GMT"
},
{
"version": "v3",
"created": "Tue, 13 May 2008 04:30:53 GMT"
}
] | 2008-08-11T00:00:00 | [
[
"Ali",
"M. Hossain",
""
]
] |
0707.1080 | Kourosh Nozari | Kourosh Nozari and S. Hamid Mehdipour | Noncommutative Inspired Reissner-Nordstr\"om Black Holes in Large Extra
Dimensions | 24 pages, 12 figures, revised version to appear in Commun. Theor.
Phys | Commun.Theor.Phys.53:503-513,2010 | 10.1088/0253-6102/53/3/20 | null | hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, a new noncommutative geometry inspired solution of the coupled
Einstein-Maxwell field equations including black holes in 4-dimension is found.
In this paper, we generalize some aspects of this model to the
Reissner-Nordstr\"om (RN) like geometries with large extra dimensions. We
discuss Hawking radiation process based on noncommutative inspired solutions.
In this framework, existence of black hole remnant and possibility of its
detection in LHC are investigated.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 05:24:36 GMT"
},
{
"version": "v2",
"created": "Fri, 26 Jun 2009 06:21:32 GMT"
}
] | 2010-04-22T00:00:00 | [
[
"Nozari",
"Kourosh",
""
],
[
"Mehdipour",
"S. Hamid",
""
]
] |
0707.1081 | Alex Kirillov | A.A. Kirillov and E.P. Savelova | Dark Matter from a gas of wormholes | minor corrections (eq. 18) | Phys.Lett.B660:93-99,2008 | 10.1016/j.physletb.2007.12.034 | null | astro-ph gr-qc hep-th | null | The simplistic model of the classical spacetime foam is considered, which
consists of static wormholes embedded in Minkowski spacetime. We explicitly
demonstrate that such a foam structure leads to a topological bias of
point-like sources which can equally be interpreted as the presence of a dark
halo around any point source. It is shown that a non-trivial halo appears on
scales where the topological structure possesses a local inhomogeneity, while
the homogeneous structure reduces to a constant renormalization of the
intensity of sources. We also show that in general dark halos possess both
(positive and negative) signs depending on scales and specific properties of
topological structure of space.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 10:39:11 GMT"
},
{
"version": "v2",
"created": "Sat, 3 Nov 2007 00:56:01 GMT"
},
{
"version": "v3",
"created": "Fri, 21 Dec 2007 08:10:36 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kirillov",
"A. A.",
""
],
[
"Savelova",
"E. P.",
""
]
] |
0707.1082 | B{\l}a\.zej Szablikowski | Blazej M. Szablikowski, Maciej Blaszak | Dispersionful analogue of the Whitham hierarchy | 21 pages | J. Math. Phys. 49 (2008) 082701 | 10.1063/1.2970774 | null | nlin.SI math-ph math.MP | null | The dispersionful analogue, by means of Lax formalism, of the zero-genus
universal Whitham hierarchy together with its algebraic orbit finite-field
reductions is considered. The theory is illustrated by several significant
examples.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 11:38:02 GMT"
}
] | 2016-02-18T00:00:00 | [
[
"Szablikowski",
"Blazej M.",
""
],
[
"Blaszak",
"Maciej",
""
]
] |
0707.1083 | Viktoria Rojkova | Viktoria Rojkova, Mehmed Kantardzic | Delayed Correlations in Inter-Domain Network Traffic | submitted to CoNext 2007 | null | null | null | cs.NI cs.IR | null | To observe the evolution of network traffic correlations we analyze the
eigenvalue spectra and eigenvectors statistics of delayed correlation matrices
of network traffic counts time series. Delayed correlation matrix D is composed
of the correlations between one variable in the multivariable time series and
another at a time delay \tau . Inverse participation ratio (IPR) of
eigenvectors of D deviates substantially from the IPR of eigenvectors of the
equal time correlation matrix C. We relate this finding to the localization and
discuss its importance for network congestion control. The time-lagged
correlation pattern between network time series is preserved over a long time,
up to 100\tau, where \tau=300 sec. The largest eigenvalue \lambda_{max} of D
and the corresponding IPR oscillate with two characteristic periods of 3\tau
and 6\tau . The existence of delayed correlations between network time series
fits well into the long range dependence (LRD) property of the network traffic.
The ability to monitor and control the long memory processes is crucial since
they impact the network performance. Injecting the random traffic counts
between non-randomly correlated time series, we were able to break the picture
of periodicity of \lambda_{max}. In addition, we investigated influence of the
periodic injections on both largest eigenvalue and the IPR, and addressed
relevance of these indicators for the LRD and self-similarity of the network
traffic.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 19:01:51 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Rojkova",
"Viktoria",
""
],
[
"Kantardzic",
"Mehmed",
""
]
] |
0707.1084 | B{\l}a\.zej Szablikowski | Maciej Blaszak, Metin Gurses, Burcu Silindir, Blazej M. Szablikowski | Integrable discrete systems on R and related dispersionless systems | 19 pages | J. Math. Phys. 49 (2008) 072702 | 10.1063/1.2948962 | null | nlin.SI math-ph math.MP | null | The general framework for integrable discrete systems on R in particular
containing lattice soliton systems and their q-deformed analogues is presented.
The concept of regular grain structures on R, generated by discrete
one-parameter groups of diffeomorphisms, through which one can define algebras
of shift operators is introduced. Two integrable hierarchies of discrete chains
together with bi-Hamiltonian structures are constructed. Their continuous limit
and the inverse problem based on the deformation quantization scheme are
considered.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 11:45:27 GMT"
}
] | 2016-02-18T00:00:00 | [
[
"Blaszak",
"Maciej",
""
],
[
"Gurses",
"Metin",
""
],
[
"Silindir",
"Burcu",
""
],
[
"Szablikowski",
"Blazej M.",
""
]
] |
0707.1085 | Mikhail Vasiliev a | M. A. Vasiliev | On Conformal, SL(4,R) and Sp(8,R) Symmetries of 4d Massless Fields | 66 pages, V2: minor corrections, references and acknowledgments
added, coefficients and typos corrected, V3: typos corrected, version to
appear in Nucl. Phys. B | Nucl.Phys.B793:469-526,2008 | 10.1016/j.nuclphysb.2007.10.017 | null | hep-th | null | The $sp(8, R)$ invariant formulation of free field equations of massless
fields of all spins in $AdS_4$ available previously in terms of gauge invariant
field strengths is extended to gauge potentials. As a by-product, free field
equations for a massless gauge field are shown to possess both $su(2,2)\sim
o(4,2)$ and $sl(4,R)\sim o(3,3)$ symmetry. The proposed formulation is
well-defined in the $AdS_4$ background but experiences certain degeneracy in
the flat limit that does not allow conformal invariant field equations for spin
$s>1$ gauge fields in Minkowski space. The basis model involves the doubled set
of fields of all spins. It is manifestly invariant under U(1) electric-magnetic
duality extended to higher spins. Reduction to a single massless field contains
the equations that relate its electric and magnetic potentials which are mixed
by the conformal transformations for s>1. We use the unfolded formulation
approach recalled in the paper with some emphasis on the role of
Chevalley-Eilenberg cohomology of a Lie algebra $g$ in $g$-invariant field
equations. This method makes it easy to guess a form of the 4d $sp(8, R)$
invariant massless field equations and then to extend them to the ten
dimensional $sp(8,R)$ invariant space-time. Dynamical content of the field
equations is analyzed in terms of $\sigma_-$ cohomology.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 19:06:54 GMT"
},
{
"version": "v2",
"created": "Thu, 23 Aug 2007 21:25:57 GMT"
},
{
"version": "v3",
"created": "Fri, 16 Nov 2007 21:52:31 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Vasiliev",
"M. A.",
""
]
] |
0707.1086 | Matts Roos | M. Roos | A model of accelerating dark energy in decelerating gravity | 4 pages. Three misprints in v1 corrected | null | null | null | astro-ph | null | The expansion of the Universe is accelerated as testified by observations of
SNeIa at varying redshifts. Explanations of this acceleration are of two kinds:
modifications of Einstein gravity or new forms of energy. An example of
modified gravity is the braneworld Dvali-Gabadadze-Porrati (DGP) model, an
example of dark energy is Chaplygin gas. Both are characterized by a cross-over
length scale $r_c$ which marks the transition between physics occurring on our
four-dimensional brane, and in a five-dimensional bulk space. Assuming that the
scales $r_c$ in the two models are the same, we study Chaplygin gas dark energy
in flat DGP geometries. The self-accelerating branch does not give a viable
model, it causes too much acceleration. We derive the Hubble function and the
luminosity distance for the self-decelerating branch, and then fit a
compilation of 192 SNeIa magnitudes and redshifts in the space of the three
parameters of the model. Our model with the self-decelerating branch fits the
supernova data as successfully as does the $\Lambda CDM$ model, and with only
one additional parameter. In contrast to the $\Lambda CDM$ model, this model
needs no fine-tuning, and it can explain the coincidence problem. It is unique
in the sense that it cannot be reduced to a cosmological constant model in any
other limit of the parameter space than in the distant future. If later tests
with other cosmological data are successful, we have here a first indication
that we live in a five-dimensional braneworld.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 12:39:54 GMT"
},
{
"version": "v2",
"created": "Fri, 13 Jul 2007 10:06:10 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Roos",
"M.",
""
]
] |
0707.1087 | S{\o}ren Meibom | S. Meibom, R. D. Mathieu, and K. G. Stassun | The Effect of Binarity on Stellar Rotation - Beyond the Reach of Tides | 10 pages, 1 figure, accepted to ApJL | null | 10.1086/521437 | null | astro-ph | null | We present a comparison between the rotation period distributions of
solar-type single stars and primary stars in close binaries (0.1 AU ~< a ~< 5
AU) in the young (150 Myr) open cluster M35 (NGC 2168). We find that the
primary stars in the close binaries rotate faster than the single stars, on
average. The differences in the means and medians between the period
distributions are statistically significant at the 99.9% level or higher. The
faster rotation among the primary stars in close binaries is not due to tidal
synchronization as tidally evolved stars are excluded from the comparison. We
discuss this result in the context of different early-evolution accretion
processes and star-disk interactions for single stars and stars in close
binaries.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 13:35:17 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Meibom",
"S.",
""
],
[
"Mathieu",
"R. D.",
""
],
[
"Stassun",
"K. G.",
""
]
] |
0707.1088 | Eduardo Sergio Santini | Felipe T. Falciano (IAP and Icra/CBPF), Nelson Pinto-Neto (ICRA/CBPF)
and E. Sergio Santini (ICRA/CBPF and Cnen) | An Inflationary Non-singular Quantum Cosmological Model | 10 pages, 5 figures. Some changes in the conclusion, some references
added. Last version, accepted for publication in PRD | Phys.Rev.D76:083521,2007 | 10.1103/PhysRevD.76.083521 | null | gr-qc | null | A stiff matter-dominated universe modeled by a free massless scalar field
minimally coupled to gravity in a Friedmann-Lema\^{\i}tre-Robertson-Walker
(FLRW) geometry is quantized. Generalized complex-width gaussian superpositions
of the solutions of the Wheeler-DeWitt equation are constructed and the Bohm-de
Broglie interpretation of quantum cosmology is applied. A planar dynamical
system is found in which a diversity of quantum bohmian trajectories are
obtained and discussed. One class of solutions represents non-singular
inflationary models starting at infinity past from flat space-time with
Planckian size spacelike hypersurfaces, which inflates without inflaton but due
to a quantum cosmological effect, until it makes an analytical graceful exit
from this inflationary epoch to a decelerated classical stiff matter expansion
phase.
| [
{
"version": "v1",
"created": "Mon, 9 Jul 2007 19:19:30 GMT"
},
{
"version": "v2",
"created": "Tue, 11 Sep 2007 21:17:13 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Falciano",
"Felipe T.",
"",
"IAP and Icra/CBPF"
],
[
"Pinto-Neto",
"Nelson",
"",
"ICRA/CBPF"
],
[
"Santini",
"E. Sergio",
"",
"ICRA/CBPF and Cnen"
]
] |
0707.1089 | Ivan Veseli\'c | Ton\'ci Antunovi\'c and Ivan Veseli\'c | Sharpness of the phase transition and exponential decay of the
subcritical cluster size for percolation on quasi-transitive graphs | Latex 2e; 25 pages (a4wide); small editorial corrections; one
reference added | Journal of Statistical Physics March 2008, Volume 130, Issue 5, pp
983-1009 | 10.1007/s10955-007-9459-x | null | math.PR math-ph math.GR math.MP | null | We study homogeneous, independent percolation on general quasi-transitive
graphs. We prove that in the disorder regime where all clusters are finite
almost surely, in fact the expectation of the cluster size is finite. This
extends a well-known theorem by Menshikov and Aizenman & Barsky to all
quasi-transitive graphs. Moreover we deduce that in this disorder regime the
cluster size distribution decays exponentially, extending a result of Aizenman
& Newman. Our results apply to both edge and site percolation, as well as long
range (edge) percolation. The proof is based on a modification of the Aizenman
& Barsky method.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 13:34:02 GMT"
},
{
"version": "v2",
"created": "Thu, 18 Oct 2007 14:52:27 GMT"
},
{
"version": "v3",
"created": "Mon, 12 Nov 2007 13:56:36 GMT"
}
] | 2016-01-07T00:00:00 | [
[
"Antunović",
"Tonći",
""
],
[
"Veselić",
"Ivan",
""
]
] |
0707.1090 | Rakesh Kumar | Rakesh Kumar, C.V. Tomy, R. Nagarajan, P.L. Paulose and S.K. Malik | Magnetization and heat capacity studies of double perovskite compounds
Ba2SmRuO6 and Ba2DyRuO6 | 13pages,7fig | null | null | null | cond-mat.mtrl-sci cond-mat.str-el | null | Here we report the magnetic and heat capacity studies of the double
perovskite com-pounds Ba2SmRuO6 and Ba2DyRuO6. Antiferromagnetic transitions
are inferred at 54 K and 47 K in Ba2SmRuO6 and Ba2DyRuO6, respectively in the
magnetization measure-ments. Heat capacity measurements show large jumps at the
corresponding temperatures and confirm the bulk magnetic ordering. Both the
measurements provide clear indication of the ordering of the rare earth moments
also along with the Ruthenium moments. How-ever, the heat capacity results
suggest that the ordering of rare earth magnetic moments is spread over a large
temperature range and is affected by a large crystal field effect on Ru and
rare earth ions. The anomaly observed in the magnetization measurements at 42 K
(below the magnetic ordering) in Ba2SmRuO6 is discerned as a reorientation of
Sm3+ moments
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 13:41:59 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Kumar",
"Rakesh",
""
],
[
"Tomy",
"C. V.",
""
],
[
"Nagarajan",
"R.",
""
],
[
"Paulose",
"P. L.",
""
],
[
"Malik",
"S. K.",
""
]
] |
0707.1091 | Arun Kenath Mr | C Sivaram (1) ((1) Indian Institute of Astrophysics) | Smashnova Model | null | null | null | null | astro-ph | null | An alternate model for gamma ray bursts is suggested. For a white dwarf (WD)
and neutron star (NS) very close binary system, the WD (close to Mch) can
detonate due to tidal heating, leading to a SN. Material falling on to the NS
at relativistic velocities can cause its collapse to a magnetar or quark star
or black hole leading to a GRB. As the material smashes on to the NS, it is
dubbed the Smashnova model. Here the SN is followed by a GRB. NS impacting a RG
(or RSG) (like in Thorne-Zytkow objects) can also cause a SN outburst followed
by a GRB. Other variations are explored.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 13:54:54 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Sivaram",
"C",
"",
"Indian Institute of Astrophysics"
]
] |
0707.1092 | Pierre Bayard | Pierre Bayard, Philippe Delano\"e | Entire spacelike radial graphs in the Minkowski space, asymptotic to the
light-cone, with prescribed scalar curvature | 13 pages | null | null | null | math.AP math.DG | null | Existence and uniqueness in ${\Bbb R}^{n,1}$ of entire spacelike
hypersurfaces contained in the future of the origin $O$ and asymptotic to the
light-cone, with scalar curvature prescribed at their generic point $M$ as a
negative function of the unit vector $\overrightarrow{Om}$ pointing in the
direction of $\overrightarrow{OM}$, divided by the square of the norm of
$\overrightarrow{OM}$ (a dilation invariant problem). The solutions are seeked
as graphs over the future unit-hyperboloid emanating from $O$ (the hyperbolic
space); radial upper and lower solutions are constructed which, relying on a
previous result in the Cartesian setting, imply their existence.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 14:18:49 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Bayard",
"Pierre",
""
],
[
"Delanoë",
"Philippe",
""
]
] |
0707.1093 | Lawrence R. Pratt | J. K. Shah, D. Asthagiri, L. R. Pratt, M. E. Paulaitis | Balancing Local Order and Long-Ranged Interactions in the Molecular
Theory of Liquid Water | 8 pages, 6 figures | null | 10.1063/1.2766940 | LA-UR-07-3494 | physics.chem-ph physics.bio-ph | null | A molecular theory of liquid water is identified and studied on the basis of
computer simulation of the TIP3P model of liquid water. This theory would be
exact for models of liquid water in which the intermolecular interactions
vanish outside a finite spatial range, and therefore provides a precise
analysis tool for investigating the effects of longer-ranged intermolecular
interactions. We show how local order can be introduced through quasi-chemical
theory. Long-ranged interactions are characterized generally by a conditional
distribution of binding energies, and this formulation is interpreted as a
regularization of the primitive statistical thermodynamic problem. These
binding-energy distributions for liquid water are observed to be unimodal. The
gaussian approximation proposed is remarkably successful in predicting the
Gibbs free energy and the molar entropy of liquid water, as judged by
comparison with numerically exact results. The remaining discrepancies are
subtle quantitative problems that do have significant consequences for the
thermodynamic properties that distinguish water from many other liquids. The
basic subtlety of liquid water is found then in the competition of several
effects which must be quantitatively balanced for realistic results.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 14:18:58 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Shah",
"J. K.",
""
],
[
"Asthagiri",
"D.",
""
],
[
"Pratt",
"L. R.",
""
],
[
"Paulaitis",
"M. E.",
""
]
] |
0707.1094 | Jose' P. S. Lemos | Jos\'e P. S. Lemos, Oleg B. Zaslavskii | Quasi-black holes: definition and general properties | 29 pages, minor changes | Phys.Rev.D76:084030,2007 | 10.1103/PhysRevD.76.084030 | null | gr-qc astro-ph hep-th | null | Objects that are on the verge of being extremal black holes but actually are
distinct in many ways are called quasi-black holes. Quasi-black holes are
defined here and treated in a unified way through the displaying of their
properties. The main ones are (i) there are infinite redshift whole regions,
(ii) the spacetimes exhibit degenerate, almost singular, features but their
curvature invariants remain perfectly regular everywhere, (iii) in the limit
under discussion, outer and inner regions become mutually impenetrable and
disjoint, although, in contrast to the usual black holes, this separation is of
a dynamical nature, rather than purely causal, (iv) for external far away
observers the spacetime is virtually indistinguishable from that of extremal
black holes. It is shown, in addition, that quasi-black holes must be extremal.
Connections with black hole and wormhole physics are also drawn.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 15:01:18 GMT"
},
{
"version": "v2",
"created": "Sat, 6 Oct 2007 19:31:02 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Lemos",
"José P. S.",
""
],
[
"Zaslavskii",
"Oleg B.",
""
]
] |
0707.1095 | Gregory Gutin | Noga Alon, Fedor V. Fomin, Gregory Gutin, Michael Krivelevich, Saket
Saurabh | Better Algorithms and Bounds for Directed Maximum Leaf Problems | null | null | null | null | cs.DS cs.DM | null | The {\sc Directed Maximum Leaf Out-Branching} problem is to find an
out-branching (i.e. a rooted oriented spanning tree) in a given digraph with
the maximum number of leaves. In this paper, we improve known parameterized
algorithms and combinatorial bounds on the number of leaves in out-branchings.
We show that
\begin{itemize} \item every strongly connected digraph $D$ of order $n$ with
minimum in-degree at least 3 has an out-branching with at least $(n/4)^{1/3}-1$
leaves; \item if a strongly connected digraph $D$ does not contain an
out-branching with $k$ leaves, then the pathwidth of its underlying graph is
$O(k\log k)$; \item it can be decided in time $2^{O(k\log^2 k)}\cdot n^{O(1)}$
whether a strongly connected digraph on $n$ vertices has an out-branching with
at least $k$ leaves. \end{itemize}
All improvements use properties of extremal structures obtained after
applying local search and of some out-branching decompositions.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 15:52:29 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Alon",
"Noga",
""
],
[
"Fomin",
"Fedor V.",
""
],
[
"Gutin",
"Gregory",
""
],
[
"Krivelevich",
"Michael",
""
],
[
"Saurabh",
"Saket",
""
]
] |
0707.1096 | Gu Jiapu | Gu Jiapu | Study on the energy criterion of cuprate superconductivity | 10 pages, 2 figures | null | null | null | physics.gen-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we use the variation of spontaneous magnetization to describe
the influence of electron holes in cuprate superconductors, and use competitive
energy relations to explore the superconductivity rule and energy criterion, on
this basis, we can deduce a clear physical image of superconducting phase
diagram and superconducting mechanism.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 16:04:44 GMT"
},
{
"version": "v2",
"created": "Sat, 24 Oct 2009 10:14:59 GMT"
},
{
"version": "v3",
"created": "Tue, 27 Oct 2009 13:31:06 GMT"
},
{
"version": "v4",
"created": "Tue, 9 Feb 2010 16:49:18 GMT"
}
] | 2010-02-09T00:00:00 | [
[
"Jiapu",
"Gu",
""
]
] |
0707.1097 | Grigori Amosov | Grigori G. Amosov | The strong superadditivity conjecture holds for the quantum depolarizing
channel in any dimension | 3 pages | Physical Review A 75 (2007) no. 6, P. 060304 | 10.1103/PhysRevA.75.060304 | null | quant-ph | null | Given a quantum channel $\Phi $ in a Hilbert space $H$ put $\hat
H_{\Phi}(\rho)=\min \limits_{\rho_{av}=\rho}\Sigma_{j=1}^{k}\pi_{j}S(\Phi
(\rho_{j}))$, where $\rho_{av}=\Sigma_{j=1}^{k}\pi_{j}\rho_{j}$, the minimum is
taken over all probability distributions $\pi =\{\pi_{j}\}$ and states
$\rho_{j}$ in $H$, $S(\rho)=-Tr\rho\log\rho$ is the von Neumann entropy of a
state $\rho$. The strong superadditivity conjecture states that $\hat H_{\Phi
\otimes \Psi}(\rho)\ge \hat H_{\Phi}(Tr_{K}(\rho))+\hat H_{\Psi}(Tr_{H}(\rho))$
for two channels $\Phi $ and $\Psi $ in Hilbert spaces $H$ and $K$,
respectively. We have proved the strong superadditivity conjecture for the
quantum depolarizing channel in any dimensions.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 16:07:21 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Amosov",
"Grigori G.",
""
]
] |
0707.1098 | Antonio Alarcon | Antonio Alarcon | On the Calabi-Yau problem for maximal surfaces in L^3 | 12 pages, 2 figures. Revised version. To appear in Differ. Geom. Appl | null | null | null | math.DG | null | In this paper we construct an example of a weakly complete maximal surface in
the Lorentz-Minkowski space L^3, which is bounded by a hyperboloid. Moreover,
all the singularities of our example are of lightlike type.
| [
{
"version": "v1",
"created": "Mon, 9 Jul 2007 18:48:33 GMT"
},
{
"version": "v2",
"created": "Tue, 4 Dec 2007 12:39:23 GMT"
}
] | 2007-12-04T00:00:00 | [
[
"Alarcon",
"Antonio",
""
]
] |
0707.1099 | Samar Agnihotri | Samar Agnihotri and Pavan Nuggehalli | Worst-Case Interactive Communication and Enhancing Sensor Network
Lifetime | Minor revision: fixed some typos and reorganized some portions. 12
pages, 3 figures | null | null | null | cs.IT math.IT | null | We are concerned with the problem of maximizing the worst-case lifetime of a
data-gathering wireless sensor network consisting of a set of sensor nodes
directly communicating with a base-station.We propose to solve this problem by
modeling sensor node and base-station communication as the interactive
communication between multiple correlated informants (sensor nodes) and a
recipient (base-station). We provide practical and scalable interactive
communication protocols for data gathering in sensor networks and demonstrate
their efficiency compared to traditional approaches.
In this paper, we first develop a formalism to address the problem of
worst-case interactive communication between a set of multiple correlated
informants and a recipient. We realize that there can be different objectives
to achieve in such a communication scenario and compute the optimal number of
messages and bits exchanged to realize these objectives. Then, we propose to
adapt these results in the context of single-hop data-gathering sensor
networks. Finally, based on this proposed formalism, we propose a clustering
based communication protocol for large sensor networks and demonstrate its
superiority over a traditional clustering protocol.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 18:06:36 GMT"
},
{
"version": "v2",
"created": "Tue, 31 Jul 2007 10:41:29 GMT"
},
{
"version": "v3",
"created": "Sat, 3 Nov 2007 13:30:47 GMT"
}
] | 2007-11-03T00:00:00 | [
[
"Agnihotri",
"Samar",
""
],
[
"Nuggehalli",
"Pavan",
""
]
] |
0707.1100 | Petter Holme | Petter Holme | Efficiency of navigation in indexed networks | null | Dynamics on and of networks. N. Ganguly, A. Mukherjee and A.
Deutsch, eds., (Birkauser, Boston, 2009), pp. 189-198. | 10.1007/978-0-8176-4751-3_11 | null | physics.comp-ph | null | We investigate efficient methods for packets to navigate in complex networks.
The packets are assumed to have memory, but no previous knowledge of the graph.
We assume the graph to be indexed, i.e. every vertex is associated with a
number (accessible to the packets) between one and the size of the graph. We
test different schemes to assign indices and utilize them in packet navigation.
Four different network models with very different topological characteristics
are used for testing the schemes. We find that one scheme outperform the
others, and has an efficiency close to the theoretical optimum. We discuss the
use of indexed-graph navigation in peer-to-peer networking and other
distributed information systems.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 18:08:06 GMT"
}
] | 2009-06-09T00:00:00 | [
[
"Holme",
"Petter",
""
]
] |
0707.1101 | Thomas Mehen | Ahmad Idilbi (Duke U.), Thomas Mehen (Duke U. & Jefferson Lab) | Demonstration of the Equivalence of Soft and Zero-Bin Subtractions | 14 pages, 3 figures | Phys.Rev.D76:094015,2007 | 10.1103/PhysRevD.76.094015 | null | hep-ph | null | Calculations of collinear correlation functions in perturbative QCD and
Soft-Collinear Effective Theory (SCET) require a prescription for subtracting
soft or zero-bin contributions in order to avoid double counting the
contributions from soft modes. At leading order in $\lambda$, where $\lambda$
is the SCET expansion parameter, the zero-bin subtractions have been argued to
be equivalent to convolution with soft Wilson lines. We give a proof of the
factorization of naive collinear Wilson lines that is crucial for the
derivation of the equivalence. We then check the equivalence by computing the
non-Abelian two-loop mixed collinear-soft contribution to the jet function in
the quark form factor. These results provide strong support for the
equivalence, which can be used to give a nonperturbative definition of the
zero-bin subtraction at lowest order in $\lambda$.
| [
{
"version": "v1",
"created": "Mon, 9 Jul 2007 14:03:55 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Idilbi",
"Ahmad",
"",
"Duke U."
],
[
"Mehen",
"Thomas",
"",
"Duke U. & Jefferson Lab"
]
] |
0707.1102 | Michael Zieve | Ariane M. Masuda and Michael E. Zieve | Nonexistence of permutation binomials of certain shapes | 6 pages | Electronic J. Combinatorics 14 (2007), N12 | null | null | math.NT | null | Suppose x^m + c*x^n is a permutation polynomial over GF(p), where p>5 is
prime, m>n>0, and c is in GF(p)^*. We prove that gcd(m-n,p-1) is not 2 or 4. In
the special case that either (p-1)/2 or (p-1)/4 is prime, this was conjectured
in a recent paper by Masuda, Panario and Wang.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 20:07:10 GMT"
}
] | 2008-06-09T00:00:00 | [
[
"Masuda",
"Ariane M.",
""
],
[
"Zieve",
"Michael E.",
""
]
] |
0707.1103 | Achyut Bora | Achyut Bora and A.K. Raychaudhuri | Scanning Thermal Microscope Study of a Metal Film Under Current
Stressing: Role of Temperature Inhomogeneity in Damage Process | 25 pages, 9 figures | null | null | null | cond-mat.other | null | We report direct observation of the evolution of local temperature
inhomogeneity and the resulting atomic migration in a metal film (Ag on Si)
stressed by a current by using a Scanning Thermal Microscope that allows
simultaneous temperature mapping and topography imaging. The experimental
observation is analyzed using a model based simulation. The experimental
observation and the simulation show that due to current stressing the
temperature of the film becomes significantly inhomogeneous over time (with
local temperature deviating strongly from the mean). This creates local stress
as well as local temperature gradient that lead to mass migration in addition
to the electromigration. We show that the local temperature inhomogeneity
serves as one of the main agents for local atomic migration which leads to
change in film microstructure. The migration leads to damage and eventual
failure as simultaneously monitored by in-situ resistance measurement.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 19:14:27 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Bora",
"Achyut",
""
],
[
"Raychaudhuri",
"A. K.",
""
]
] |
0707.1104 | Hans Vernaeve | Claudia Garetto and Hans Vernaeve | Hilbert $\widetilde{\C}$-modules: structural properties and applications
to variational problems | null | Trans. Amer. Math. Soc. (2011) 363: 2047-2090 | null | null | math.FA | null | We develop a theory of Hilbert $\widetilde{\C}$-modules by investigating
their structural and functional analytic properties. Particular attention is
given to finitely generated submodules, projection operators, representation
theorems for $\widetilde{\C}$-linear functionals and
$\widetilde{\C}$-sesquilinear forms. By making use of a generalized Lax-Milgram
theorem, we provide some existence and uniqueness theorems for variational
problems involving a generalized bilinear or sesquilinear form.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 19:40:13 GMT"
}
] | 2014-04-01T00:00:00 | [
[
"Garetto",
"Claudia",
""
],
[
"Vernaeve",
"Hans",
""
]
] |
0707.1105 | Jose Antonio Martins Simoes | F. M. L. de Almeida Jr., Y. A.Coutinho, J. A. Martins Sim\~oes, A. J.
Ramalho, S. Wulck, M. A. B. do Vale | Right-handed heavy neutrinos in the littlest Higgs model | 9 pages, 4 figures. Revised version | null | null | null | hep-ph | null | In this paper we discuss the consequences of including a new heavy
right-handed neutrino singlet $N_R$ in the littlest Higgs model. This new state
is not connected with the light neutrinos {\it via} the seesaw mechanism. A
very interesting property of this extended model is the full coupling of the
new neutral gauge boson $A_H$ to $N_R$, giving large total cross sections and
suggesting a wide range of experimental search for the $N_R$ at the p p
collider CERN-LHC and future electron-positron collider ILC.
| [
{
"version": "v1",
"created": "Mon, 9 Jul 2007 16:53:21 GMT"
},
{
"version": "v2",
"created": "Mon, 1 Oct 2007 17:23:27 GMT"
}
] | 2007-10-01T00:00:00 | [
[
"Almeida",
"F. M. L. de",
"Jr."
],
[
"Coutinho",
"Y. A.",
""
],
[
"Simões",
"J. A. Martins",
""
],
[
"Ramalho",
"A. J.",
""
],
[
"Wulck",
"S.",
""
],
[
"Vale",
"M. A. B. do",
""
]
] |
0707.1106 | Dmitry Novikov | D. S. Novikov | Numbers of donors and acceptors from transport measurements in graphene | 3 pages, 1 figure | Appl. Phys. Lett. 91, 102102 (2007) | 10.1063/1.2779107 | null | cond-mat.mes-hall cond-mat.mtrl-sci | null | A method is suggested to separately determine the surface density of
positively and negatively charged impurities that limit the mobility in a
graphene monolayer. The method is based on the exact result for the transport
cross-section, according to which the massless carriers are scattered more
strongly when they are attracted to a charged impurity than when they are
repelled from it.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 19:23:27 GMT"
}
] | 2007-09-05T00:00:00 | [
[
"Novikov",
"D. S.",
""
]
] |
0707.1107 | Adilson Enio Motter | Adilson E. Motter and Zoltan Toroczkai | Optimization in Networks | Opening article of the CHAOS Focus Issue "Optimization in Networks",
available at http://link.aip.org/link/?CHA/17/2/htmltoc | Chaos 17, 026101 (2007) | 10.1063/1.2751266 | null | cond-mat.dis-nn nlin.CD | null | The recent surge in the network modeling of complex systems has set the stage
for a new era in the study of fundamental and applied aspects of optimization
in collective behavior. This Focus Issue presents an extended view of the state
of the art in this field and includes articles from a large variety of domains
where optimization manifests itself, including physical, biological, social,
and technological networked systems.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 19:28:14 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Motter",
"Adilson E.",
""
],
[
"Toroczkai",
"Zoltan",
""
]
] |
0707.1108 | Michael Zieve | Ariane M. Masuda and Michael E. Zieve | Permutation binomials over finite fields | 12 pages; various minor changes | Trans. Amer. Math. Soc. 361 (2009) 4169-4180 | null | null | math.NT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove that if x^m + c*x^n permutes the prime field GF(p), where m>n>0 and
c is in GF(p)^*, then gcd(m-n,p-1) > sqrt{p} - 1. Conversely, we prove that if
q>=4 and m>n>0 are fixed and satisfy gcd(m-n,q-1) > 2q*(log log q)/(log q),
then there exist permutation binomials over GF(q) of the form x^m + c*x^n if
and only if gcd(m,n,q-1) = 1.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 19:43:00 GMT"
},
{
"version": "v2",
"created": "Thu, 19 Jul 2007 17:33:33 GMT"
},
{
"version": "v3",
"created": "Wed, 24 Dec 2008 03:35:54 GMT"
}
] | 2013-10-08T00:00:00 | [
[
"Masuda",
"Ariane M.",
""
],
[
"Zieve",
"Michael E.",
""
]
] |
0707.1109 | Anatoly Vershik | A.V.Malyutin, A.M.Vershik | Boundary of the braid groups and Markov--Ivanovsky normal form | P.25, Ref 21, Fig 3 | null | null | null | math.GT math.GR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We describe random walk boundaries (in particular, the Poisson--Furstenberg,
or PF-boundary) for a vast family of groups in terms of the hyperbolic boundary
of a special free subgroup. We prove that almost all trajectories of the random
walk (with respect to an arbitrary nondegenerate measure on the group) converge
to points of that boundary. This implies the stability (in the sense of
\cite{Ver}) of the so-called Markov--Ivanovsky normal form for braids.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 19:44:29 GMT"
},
{
"version": "v2",
"created": "Sat, 13 Sep 2008 16:42:43 GMT"
}
] | 2008-09-15T00:00:00 | [
[
"Malyutin",
"A. V.",
""
],
[
"Vershik",
"A. M.",
""
]
] |
0707.1110 | Michael Zieve | Michael E. Zieve | On some permutation polynomials over F_q of the form x^r*h(x^((q-1)/d))) | 10 pages | Proc. Amer. Math. Soc. 137 (2009) 2209-2216 | null | null | math.NT | null | In a recent paper, Akbary and Wang gave a sufficient condition for x^u + x^r
to permute GF(q), in terms of the period of a certain sequence involving sums
of cosines. As an application they gave necessary and sufficient conditions in
case u,r,q satisfy certain special properties. We show that the Akbary-Wang
sufficient condition follows from a more general sufficient condition which
does not involve sums of cosines. This leads to vastly simpler proofs of the
Akbary-Wang results, as well as generalizations to polynomials of the form
x^r*h(x^{(q-1)/d}).
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 20:04:17 GMT"
}
] | 2013-10-08T00:00:00 | [
[
"Zieve",
"Michael E.",
""
]
] |
0707.1111 | Michael Zieve | Michael E. Zieve | Some families of permutation polynomials over finite fields | 7 pages | Int. J. Number Theory 4 (2008), 851-857 | null | null | math.NT | null | We give necessary and sufficient conditions for a polynomial of the form
x^r*(1+x^v+x^(2v)+...+x^(kv))^t to permute the elements of the finite field
GF(q). Our results yield especially simple criteria in case (q-1)/gcd(q-1,v) is
a small prime.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 20:18:30 GMT"
}
] | 2013-10-08T00:00:00 | [
[
"Zieve",
"Michael E.",
""
]
] |
0707.1112 | Yuri Obukhov | Yuri N. Obukhov and Friedrich W. Hehl | On the boundary-value problems and the validity of the Post constraint
in modern electromagnetism | Revtex, 7 pages, no figures | null | null | null | physics.class-ph physics.optics | null | We recall that the theory of electromagnetism consists of three building
blocks: (a) the inhomogeneous Maxwell equations for the electric and magnetic
excitations $(D,H)$ (which reflects charge conservation), (b) the homogeneous
Maxwell equations for the electric and magnetic field strengths $(E,B)$ (which
reflects flux conservation), and (c) the constitutive relation between $(D,H)$
and $(E,B)$. In the recent paper \cite{Lakhtakia1}, Lakhtakia proposed to
change the standard boundary conditions in electrodynamics in order to exclude
certain constitutive parameters. We show that this is inadmissible both from
the macroscopic and the microscopic points of view.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 20:22:57 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Obukhov",
"Yuri N.",
""
],
[
"Hehl",
"Friedrich W.",
""
]
] |
0707.1113 | Krzysztof Marciniak | Krzysztof Marciniak and Maciej Blaszak | Non-Hamiltonian systems separable by Hamilton-Jacobi method | 20 pages, LaTeX, no figures | null | 10.1016/j.geomphys.2007.12.008 | null | nlin.SI | null | We show that with every separable calssical Stackel system of Benenti type on
a Riemannian space one can associate, by a proper deformation of the metric
tensor, a multi-parameter family of non-Hamiltonian systems on the same space,
sharing the same trajectories and related to the seed system by appropriate
reciprocal transformations. These system are known as bi-cofactor systems and
are integrable in quadratures as the seed Hamiltonian system is. We show that
with each class of bi-cofactor systems a pair of separation curves can be
related. We also investigate conditions under which a given flat bi-cofactor
system can be deformed to a family of geodesically equivalent flat bi-cofactor
systems.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 20:24:28 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Marciniak",
"Krzysztof",
""
],
[
"Blaszak",
"Maciej",
""
]
] |
0707.1114 | Elena Kazantseva V. | Elena V. Kazantseva, Andrei I. Maimistov | Wide defect in a Resonantly Absorbing Bragg Grating as a nonlinear
microresonator for polaritons | 6 figures | null | null | null | nlin.PS | null | The nonlinear polariton transmission, reflection and trapping by a defect in
the resonantly absorbing Bragg grating (RABG) is demonstrated in numerical
simulation. It is shown that the wide defect under some conditions could
effectively serve as microresonator for polaritonic wave storage. The three
types of the defect such as microcavity, groove and stripe are considered.
Capture the electromagnetic field inside the microcavity (with no resonant
nanoparticles) placed in the RABG is observed, as well as stuck of trapped
polarization modes to the defect edges for the groove (defect span with reduced
density of nanoparticles) and for the stripe with relatively increased density.
Strong radiation reflection and adhered propagation of the polarization mode
along the first edge of the stripe with high density of resonant atoms is
exhibited by numerical computation.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 20:51:30 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Kazantseva",
"Elena V.",
""
],
[
"Maimistov",
"Andrei I.",
""
]
] |
0707.1115 | Hirohisa Tanaka | H.A. Tanaka (for the MiniBooNE Collaboration) | The Search for $\nu_\mu \to \nu_e$ Oscillations at MiniBooNE | Flavor Physics & CP Violation Conference, Bled, 2007 | ECONF C070512:004,2007 | null | fpcp07_122 | hep-ex | null | MiniBooNE (Mini Booster Neutrino Experiment) searches for the
$\nu_\mu\to\nu_e$ oscillations with $\Delta m^2 \sim 1 \eV^2/c^4$ indicated by
the LSND experiment. The LSND evidence, when taken with the solar and
atmospheric neutrino oscillations, suggests new physics beyond the Standard
Model. However, this evidence has not been confirmed by other experiments.
MiniBooNE has completed its first $\nu_\mu\to\nu_e$ oscillation search using a
sample of $\sim 1$ GeV neutrino events obtained with $5.58\times 10^{20}$
protons delivered to the Booster Neutrino Beamline. The analysis finds no
significant excess of $\nu_e$ events in the analysis region of 475-3000 MeV.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 23:02:18 GMT"
}
] | 2019-08-13T00:00:00 | [
[
"Tanaka",
"H. A.",
"",
"for the MiniBooNE Collaboration"
]
] |
0707.1116 | James Dufty | James W. Dufty | Fourier's Law for a Granular Fluid | submitted for publication in a Special Issue of Journal of Physical
Chemistry B in honor of the 70th birthday of Keith Gubbins | null | null | null | cond-mat.stat-mech cond-mat.soft | null | Newton' viscosity law for the momentum flux and Fourier's law for the heat
flux define Navier-Stokes hydrodynamics for a simple, one component fluid.
There is ample evidence that a hydrodynamic description applies as well to a
mesoscopic granular fluid with the same form for Newton's viscosity law.
However, theory predicts a qualitative difference for Fourier's law with an
additional contribution from density gradients even at uniform temperature. The
reasons for the absence of such terms for normal fluids are indicated, and a
related microscopic explanation for their existence in granular fluids is
presented.
| [
{
"version": "v1",
"created": "Sat, 7 Jul 2007 23:27:20 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Dufty",
"James W.",
""
]
] |
0707.1117 | Terence C. Tao | Terence Tao | Norm convergence of multiple ergodic averages for commuting
transformations | 32 pages, no figures, to appear, Ergod. Thy. Dynam. Sys. Referee
comments incorporated, some additional explanations given | null | null | null | math.DS math.CO | null | Let $T_1, ..., T_l: X \to X$ be commuting measure-preserving transformations
on a probability space $(X, \X, \mu)$. We show that the multiple ergodic
averages $\frac{1}{N} \sum_{n=0}^{N-1} f_1(T_1^n x) ... f_l(T_l^n x)$ are
convergent in $L^2(X,\X,\mu)$ as $N \to \infty$ for all $f_1,...,f_l \in
L^\infty(X,\X,\mu)$; this was previously established for $l=2$ by Conze and
Lesigne and for general $l$ assuming some additional ergodicity hypotheses on
the maps $T_i$ and $T_i T_j^{-1}$ by Frantzikinakis and Kra (with the $l=3$
case of this result established earlier by Zhang). Our approach is
combinatorial and finitary in nature, inspired by recent developments regarding
the hypergraph regularity and removal lemmas, although we will not need the
full strength of those lemmas. In particular, the $l=2$ case of our arguments
are a finitary analogue of those of Conze and Lesigne.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 00:13:47 GMT"
},
{
"version": "v2",
"created": "Tue, 4 Sep 2007 18:59:35 GMT"
},
{
"version": "v3",
"created": "Wed, 24 Oct 2007 17:48:50 GMT"
}
] | 2007-10-24T00:00:00 | [
[
"Tao",
"Terence",
""
]
] |
0707.1118 | Hugh Hudson | Hugh S. Hudson | The Unpredictability of the Most Energetic Solar Events | 4 pages | Astrophys.J.663:L45-L48,2007 | 10.1086/519923 | null | astro-ph | null | Observations over the past two solar cycles show a highly irregular pattern
of occurrence for major solar flares, gamma-ray events, and solar energetic
particle (SEP) fluences. Such phenomena do not appear to follow the direct
indices of solar magnetic activity, such as the sunspot number. I show that
this results from the non-Poisson occurrence for the most energetic events.
This Letter also points out a particularly striking example of this
irregularity in a comparison between the declining phases of the recent two
solar cycles (1993-1995 and 2004-2006, respectively) and traces it through the
radiated energies of the flares, the associated SEP fluences, and the sunspot
areas. These factors suggest that processes in the solar interior involved with
the supply of magnetic flux up to the surface of the Sun have strong
correlations in space and time, leading to a complex occurrence pattern that is
presently unpredictable on timescales longer than active region lifetimes
(weeks) and not correlated well with the solar cycle itself.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 01:02:18 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hudson",
"Hugh S.",
""
]
] |
0707.1119 | Jason Twamley | J. Fitzsimons and J. Twamley | Globally controlled fault tolerant quantum computation | 4 Pages, 3 figures | null | null | null | quant-ph | null | We describe a method to execute globally controlled quantum information
processing which admits a fault tolerant quantum error correction scheme. Our
scheme nominally uses three species of addressable two-level systems which are
arranged in a one dimensional array in a specific periodic arrangement. We show
that the scheme possesses a fault tolerant error threshold.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 07:41:56 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Fitzsimons",
"J.",
""
],
[
"Twamley",
"J.",
""
]
] |
0707.1120 | Laura Felicia Matusevich | Laura Felicia Matusevich | Weyl closure of hypergeometric systems | Changes in Section 2: Proposition 2.5 from version 1 was incorrectly
proven; this has now been removed, and the proof of Theorem 2.7 no longer
relies on that fact | null | null | null | math.AG math.AC math.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that A-hypergeometric systems and Horn hypergeometric systems are
Weyl closed for very generic parameters.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 01:35:14 GMT"
},
{
"version": "v2",
"created": "Mon, 19 Jan 2009 05:58:16 GMT"
}
] | 2009-01-19T00:00:00 | [
[
"Matusevich",
"Laura Felicia",
""
]
] |
0707.1121 | Gregory W. Hammett | N. F. Loureiro and G. W. Hammett | An iterative semi-implicit scheme with robust damping | Submitted to the Journal of Computational Physics. Clarifications and
caveats in response to referees, numerical demonstration of convergence rate,
generalized symplectic proof | J. Comp. Phys. 227, 4518 (2008) | 10.1016/j.jcp.2008.01.015 | null | physics.comp-ph physics.plasm-ph | null | An efficient, iterative semi-implicit (SI) numerical method for the time
integration of stiff wave systems is presented. Physics-based assumptions are
used to derive a convergent iterative formulation of the SI scheme which
enables the monitoring and control of the error introduced by the SI operator.
This iteration essentially turns a semi-implicit method into a fully implicit
method. Accuracy, rather than stability, determines the timestep. The scheme is
second-order accurate and shown to be equivalent to a simple preconditioning
method. We show how the diffusion operators can be handled so as to yield the
property of robust damping, i.e., dissipating the solution at all values of the
parameter $\mathcal D\dt$, where $\mathcal D$ is a diffusion operator and $\dt$
the timestep. The overall scheme remains second-order accurate even if the
advection and diffusion operators do not commute. In the limit of no physical
dissipation, and for a linear test wave problem, the method is shown to be
symplectic. The method is tested on the problem of Kinetic Alfv\'en wave
mediated magnetic reconnection. A Fourier (pseudo-spectral) representation is
used. A 2-field gyrofluid model is used and an efficacious k-space SI operator
for this problem is demonstrated. CPU speed-up factors over a CFL-limited
explicit algorithm ranging from $\sim20$ to several hundreds are obtained,
while accurately capturing the results of an explicit integration. Possible
extension of these results to a real-space (grid) discretization is discussed.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 03:56:15 GMT"
},
{
"version": "v2",
"created": "Mon, 7 Jan 2008 03:23:50 GMT"
}
] | 2008-07-02T00:00:00 | [
[
"Loureiro",
"N. F.",
""
],
[
"Hammett",
"G. W.",
""
]
] |
0707.1122 | Rituparno Goswami | Rituparno Goswami | Gravitational collapse of dustlike matter with heat flux | 5 pages, Revtex4, 2 figures | null | null | null | gr-qc astro-ph hep-th | null | We present a new class of solutions to Einstein equations for the spherical
collapse of dustlike matter coupled with heat flux. In this family of solutions
spacetime shear is necessarily non-zero. Also these solutions have an
interesting property that there is always a bounce before the singularity,
which is caused entirely due to the dissipative processes. We show there exist
open sets of initial data for which the bounce occurs before any trapped
surface formation, making the star explode away to infinity. We also discuss
the role of heat flow in generating spacetime shear and in modifying the
effective inertial mass of the matter cloud.
| [
{
"version": "v1",
"created": "Mon, 9 Jul 2007 19:37:52 GMT"
}
] | 2007-07-11T00:00:00 | [
[
"Goswami",
"Rituparno",
""
]
] |
0707.1123 | Afif Siddiki Dr. | Afif Siddiki | The spin-split incompressible edge states within empirical Hartree
approximation at intermediately large Hall samples | EP2DS-17 Proceedings, 6 Pages, 2 Figures | null | 10.1016/j.physe.2007.08.153 | null | cond-mat.mes-hall | null | A self-consistent Thomas-Fermi-Poisson based calculation scheme is used to
achieve spin resolved incompressible strips (ISs). The effect of exchange and
correlation is incorporated by an empirically induced g factor. A local version
of the Ohm's law describes the imposed fixed current, where the discrepancies
of this model are resolved by a relevant spatial averaging process. The
longitudinal resistance is obtained as a function of the perpendicular (strong)
magnetic field at filling factor one and two plateaus. Interrelation between
the ISs and the longitudinal zeros is explicitly shown.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 07:41:06 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Siddiki",
"Afif",
""
]
] |
0707.1124 | Efim Zasavitsky | E. Zasavitsky | Tensoresistive Effect in Single Crystal Microwires of Pbte Doped with Tl | 5 pages, 2 figures | null | null | null | cond-mat.mtrl-sci cond-mat.mes-hall | null | Results of room temperature measurements of tensoresistive effect of thin
single crystal microwires of Pb1-xTlxTe (x=0.0000 - 0.0025, d = 5 - 20
micrometers) obtained from the melted compound of corresponding composition by
the filling of quartz capillary with the following crystallization of material
are presented. For the samples corresponding to chemical composition with
concentration of thallium x ~0,0025 an essential increase of tensoresistive
effect (resistance changes for elastic elongations per unit length of a
crystal) in comparison with nondoped samples is observed. Various mechanisms
which can lead to observable anomalies, including resonance scattering are
discussed. Obtained experimental results allow us to suppose that the observed
peculiarities can be interpreted on the basis of model of an impurity band of
Tl in PbTe.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 07:44:50 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Zasavitsky",
"E.",
""
]
] |
0707.1125 | Afif Siddiki Dr. | A. Siddiki, A. E. Kavruk, T. Ozturk, U. Atav M. Sahin and T. Hakioglu | The self-consistent calculation of the edge states at quantum Hall
effect (QHE) based Mach-Zehnder interferometers (MZI) | EP2DS-17 Proceedings, 6 Pages, 2 Figures | null | 10.1016/j.physe.2007.09.063 | null | cond-mat.mes-hall | null | The spatial distribution of the incompressible edge states (IES) is obtained
for a geometry which is topologically equivalent to an electronic Mach-Zehnder
interferometer, taking into account the electron-electron interactions within a
Hartree type self-consistent model. The magnetic field dependence of these IES
is investigated and it is found that an interference pattern may be observed if
two IES merge or come very close, near the quantum point contacts. Our
calculations demonstrate that, being in a quantized Hall plateau does not
guarantee observing the interference behavior.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 08:17:04 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Siddiki",
"A.",
""
],
[
"Kavruk",
"A. E.",
""
],
[
"Ozturk",
"T.",
""
],
[
"Sahin",
"U. Atav M.",
""
],
[
"Hakioglu",
"T.",
""
]
] |
0707.1126 | Huanyang Chen | Huanyang Chen, Xunya Jiang and C. T. Chan | On some constraints that limit the design of an invisibility cloak | null | Phys. Rev. B 76, 241104(R) (2007) | 10.1103/PhysRevB.76.241104 | null | physics.optics | null | Using the idea of transformation medium, a cloak can be designed to make a
domain invisible for one target frequency. In this article, we examine the
possibility to extend the bandwidth of such a cloak. We obtained a constraint
of the band width, which is summarized as a simple inequality that states that
limits the bandwidth of operation. The constraint originates from causality
requirements. We suggest a simple strategy that can get around the constraint.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 08:17:05 GMT"
},
{
"version": "v2",
"created": "Wed, 11 Jul 2007 02:24:27 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Chen",
"Huanyang",
""
],
[
"Jiang",
"Xunya",
""
],
[
"Chan",
"C. T.",
""
]
] |
0707.1127 | Xinping Xu | BES Collaboration: M. Ablikim, et al | Measurements of $J/\psi$ and $\psi(2S)$ decays into $\Lambda
\bar{\Lambda}\pi^0$ and $\Lambda \bar{\Lambda}\eta$ | 7 pages, 10 figures. Phys.Rev.D comments considered | Phys.Rev.D76:092003,2007 | 10.1103/PhysRevD.76.092003 | null | hep-ex | null | Using 58 million $J/\psi$ and 14 million $\psi(2S)$ events collected by the
BESII detector at the BEPC, branching fractions or upper limits for the decays
$J/\psi$ and $\psi(2S) \to \Lambda \bar{\Lambda}\pi^0$ and $\Lambda
\bar{\Lambda}\eta$ are measured. For the isospin violating decays, the upper
limits are determined to be ${\cal B}(J/\psi \to \Lambda
\bar{\Lambda}\pi^0)<6.4\times 10^{-5}$ and ${\cal B}(\psi(2S) \to \Lambda
\bar{\Lambda}\pi^0)<4.9\times 10^{-5}$ at the 90% confidence level. The isospin
conserving process $J/\psi \to \Lambda \bar{\Lambda}\eta$ is observed for the
first time, and its branching fraction is measured to be ${\cal B}(J/\psi \to
\Lambda \bar{\Lambda}\eta)=(2.62\pm 0.60\pm 0.44)\times 10^{-4}$, where the
first error is statistical and the second one is systematic. No $\Lambda
\bar{\Lambda}\eta$ signal is observed in $\psi(2S)$ decays, and ${\cal
B}(\psi(2S) \to \Lambda \bar{\Lambda}\eta)<1.2\times 10^{-4}$ is set at the 90%
confidence level. Branching fractions of $J/\psi$ decays into $\Sigma^+ \pi^-
bar{\Lambda}$ and $\bar{\Sigma}^- \pi^+ \Lambda$ are also reported, and the sum
of these branching fractions is determined to be ${\cal B}(J/\psi \to
\Sigma^+\pi^- \bar{\Lambda} + c.c.)=(1.52\pm 0.08\pm 0.16)\times 10^{-3}$.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 08:30:03 GMT"
},
{
"version": "v2",
"created": "Sat, 1 Sep 2007 14:52:58 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"BES Collaboration",
"",
""
],
[
"Ablikim",
"M.",
""
]
] |
0707.1128 | Tiberiu Harko | T. Harko, K. S. Cheng | The virial theorem and the dynamics of clusters of galaxies in the brane
world models | 29 pages, no figures, accepted for publication in PRD | Phys.Rev.D76:044013,2007 | 10.1103/PhysRevD.76.044013 | null | gr-qc astro-ph hep-th | null | A version of the virial theorem, which takes into account the effects of the
non-compact extra-dimensions, is derived in the framework of the brane world
models. In the braneworld scenario, the four dimensional effective Einstein
equation has some extra terms, called dark radiation and dark pressure,
respectively, which arise from the embedding of the 3-brane in the bulk. To
derive the generalized virial theorem we use a method based on the
collisionless Boltzmann equation. The dark radiation term generates an
equivalent mass term (the dark mass), which gives an effective contribution to
the gravitational energy. This term may account for the well-known virial
theorem mass discrepancy in actual clusters of galaxies. An approximate
solution of the vacuum field equations on the brane, corresponding to weak
gravitational fields, is also obtained, and the expressions for the dark
radiation and dark mass are derived. The qualitative behavior of the dark mass
is similar to that of the observed virial mass in clusters of galaxies. We
compare our model with the observational data for galaxy clusters, and we
express all the physical parameters of the model in terms of observable
quantities. In particular, we predict that the dark mass must extend far beyond
the presently considered virial radius. The behavior of the galaxy cluster
velocity dispersion in brane world models is also considered. Therefore the
study of the matter distribution and velocity dispersion at the extragalactic
scales could provide an efficient method for testing the multi-dimensional
physical models.
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 09:08:45 GMT"
},
{
"version": "v2",
"created": "Sat, 11 Aug 2007 02:15:42 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Harko",
"T.",
""
],
[
"Cheng",
"K. S.",
""
]
] |
0707.1129 | Andrei Khrennikov | Andrei Khrennikov | The Quantum-Like Brain Operating on Subcognitive and Cognitive Time
Scales | null | J. Consciousness Studies 15, N 7, 39-77 (2008) | null | null | physics.gen-ph | null | We propose a {\it quantum-like} (QL) model of the functioning of the brain.
It should be sharply distinguished from the reductionist {\it quantum} model.
By the latter cognition is created by {\it physical quantum processes} in the
brain. The crucial point of our modelling is that discovery of the mathematical
formalism of quantum mechanics (QM) was in fact discovery of a very general
formalism describing {\it consistent processing of incomplete information}
about contexts (physical, mental, economic, social). The brain is an advanced
device which developed the ability to create a QL representation of contexts.
Therefore its functioning can also be described by the mathematical formalism
of QM. The possibility of such a description has nothing to do with composing
of the brain of quantum systems (photons, electrons, protons,...). Moreover, we
shall propose a model in that the QL representation is based on conventional
neurophysiological model of the functioning of the brain. The brain uses the QL
rule (given by von Neumann trace formula) for calculation of {\it approximative
averages} for mental functions, but the physical basis of mental functions is
given by neural networks in the brain. The QL representation has a {\it
temporal basis.} Any cognitive process is based on (at least) two time scales:
subcognitive time scale (which is very fine) and cognitive time scale (which is
essentially coarser).
| [
{
"version": "v1",
"created": "Sun, 8 Jul 2007 09:03:35 GMT"
}
] | 2010-11-30T00:00:00 | [
[
"Khrennikov",
"Andrei",
""
]
] |
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