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list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0708.2049 | Rainer Grauer | L. Arnold, J. Dreher, R. Grauer, H. Soltwisch and H. Stein | Three-dimensional MHD simulation of expanding magnetic flux ropes | 9 figures | null | 10.1063/1.2903904 | null | physics.plasm-ph physics.flu-dyn | null | Three-dimensional, time-dependent numerical simulations of the dynamics of
magnetic flux ropes are presented. The simulations are targeted towards an
experiment previously conducted at CalTech (Bellan, P. M. and J. F. Hansen,
Phys. Plasmas, 5, 1991 (1998)) which aimed at simulating Solar prominence
eruptions in the laboratory. The plasma dynamics is described by ideal MHD
using different models for the evolution of the mass density. Key features of
the reported experimental observations like pinching of the current loop, its
expansion and distortion into helical shape are reproduced in the numerical
simulations. Details of the final structure depend on the choice of a specific
model for the mass density.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 13:46:27 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Arnold",
"L.",
""
],
[
"Dreher",
"J.",
""
],
[
"Grauer",
"R.",
""
],
[
"Soltwisch",
"H.",
""
],
[
"Stein",
"H.",
""
]
] |
0708.2050 | Alexandre Zenchuk | A. I. Zenchuk | Matrix equations of hydrodynamic type as lower-dimensional reductions of
Self-dual type $S$-integrable systems | 44 pages | null | null | null | nlin.SI | null | We show that matrix $Q\times Q$ Self-dual type $S$-integrable Partial
Differential
Equations (PDEs) possess a family of lower-dimensional reductions represented
by the matrix $ Q \times n_0 Q$ quasilinear first order PDEs solved in
\cite{SZ1} by the method of characteristics. In turn, these PDEs admit two
types of available particular solutions: (a) explicit solutions and (b)
solutions described implicitly by a system of non-differential equations. The
later solutions, in particular, exhibit the wave profile breaking. Only first
type of solutions is available for (1+1)-dimensional nonlinear $S$-integrable
PDEs. (1+1)-dimensional $N$-wave equation, (2+1)- and (3+1)-dimensional
Pohlmeyer equations are represented as examples. We also represent a new
version of the dressing method which supplies both classical solutions and
solutions with wave profile breaking to the above $S$-integrable PDEs.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 13:49:45 GMT"
},
{
"version": "v2",
"created": "Sun, 2 Sep 2007 12:13:54 GMT"
},
{
"version": "v3",
"created": "Fri, 11 Jan 2008 08:12:34 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Zenchuk",
"A. I.",
""
]
] |
0708.2051 | Gwenael Massuyeau | Gwenael Massuyeau, Alexandru Oancea, Dietmar A. Salamon | Lefschetz fibrations, intersection numbers, and representations of the
framed braid group | 62 pages, 7 figures; v5: minor modifications with respect to v4 | Bull. Math. Soc. Sci. Math. Roumanie 56(104):4 (2013) 435-486 | null | null | math.GT math.SG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the action of the fundamental group $\Gamma$ of a Riemann surface
with $m$ punctures on the middle dimensional homology of a regular fiber in a
Lefschetz fibration, and describe to what extent this action can be recovered
from the intersection numbers of vanishing cycles. Basis changes for the
vanishing cycles result in a nonlinear action of the framed braid group
$\widetilde{\mathcal B}$ on $m$ strings on a suitable space of $m\times m$
matrices. This action is determined by a family of cohomologous 1-cocycles
${\mathcal S}_c:\widetilde{\mathcal B}\to GL_m({\mathbb{Z}}[\Gamma])$
parametrized by distinguished configurations $c$ of embedded paths from the
regular value to the critical values. In the case of the disc, we compare this
family of cocycles with the Magnus cocycles given by Fox calculus and consider
some abelian reductions giving rise to linear representations of braid groups.
We also prove that, still in the case of the disc, the intersection numbers
along straight lines, which conjecturally make sense in infinite dimensional
situations, carry all the relevant information.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 13:52:08 GMT"
},
{
"version": "v2",
"created": "Tue, 11 Sep 2007 09:32:32 GMT"
},
{
"version": "v3",
"created": "Sun, 23 Mar 2008 15:09:41 GMT"
},
{
"version": "v4",
"created": "Wed, 28 Jul 2010 14:41:56 GMT"
},
{
"version": "v5",
"created": "Thu, 5 Sep 2013 07:29:23 GMT"
}
] | 2014-01-03T00:00:00 | [
[
"Massuyeau",
"Gwenael",
""
],
[
"Oancea",
"Alexandru",
""
],
[
"Salamon",
"Dietmar A.",
""
]
] |
0708.2052 | Patricio S. Letelier | Paulo M. Pitelli and Patricio S. Letelier | Quantum Singularities in Spacetimes with Spherical and Cylindrical
Topological Defects | 7 page,1 fig., Revtex, J. Math. Phys, in press | J.Math.Phys.48:092501,2007 | 10.1063/1.2779952 | null | gr-qc | null | Exact solutions of Einstein equations with null Riemman-Christoffel curvature
tensor everywhere, except on a hypersurface, are studied using quantum
particles obeying the Klein-Gordon equation. We consider the particular cases
when the curvature is represented by a Dirac delta function with support either
on a sphere or on a cylinder (spherical and cylindrical shells). In particular,
we analyze the necessity of extra boundary conditions on the shells.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 14:06:13 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Pitelli",
"Paulo M.",
""
],
[
"Letelier",
"Patricio S.",
""
]
] |
0708.2053 | Zolt\'an Eisler | Zoltan Eisler, Imre Bartos, Janos Kertesz | Fluctuation scaling in complex systems: Taylor's law and beyond | 33 pages, 20 figures, 2 tables, submitted to Advances in Physics | Advances in Physics 57, 89-142 (2008) | 10.1080/00018730801893043 | null | physics.soc-ph | null | Complex systems consist of many interacting elements which participate in
some dynamical process. The activity of various elements is often different and
the fluctuation in the activity of an element grows monotonically with the
average activity. This relationship is often of the form "$fluctuations \approx
const.\times average^\alpha$", where the exponent $\alpha$ is predominantly in
the range $[1/2, 1]$. This power law has been observed in a very wide range of
disciplines, ranging from population dynamics through the Internet to the stock
market and it is often treated under the names \emph{Taylor's law} or
\emph{fluctuation scaling}. This review attempts to show how general the above
scaling relationship is by surveying the literature, as well as by reporting
some new empirical data and model calculations. We also show some basic
principles that can underlie the generality of the phenomenon. This is followed
by a mean-field framework based on sums of random variables. In this context
the emergence of fluctuation scaling is equivalent to some corresponding limit
theorems. In certain physical systems fluctuation scaling can be related to
finite size scaling.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 15:33:31 GMT"
},
{
"version": "v2",
"created": "Wed, 26 Dec 2007 10:33:41 GMT"
}
] | 2008-04-24T00:00:00 | [
[
"Eisler",
"Zoltan",
""
],
[
"Bartos",
"Imre",
""
],
[
"Kertesz",
"Janos",
""
]
] |
0708.2054 | Svjetlana Terzic | Victor M. Buchstaber, Svjetlana Terzic | Complex cobordism classes of homogeneous spaces | improvements in subsections 7.1 and 7.2; some small comments are
added or revised and some typos corrected | null | null | null | math.AT math.GT | null | We consider compact homogeneous spaces G/H of positive Euler characteristic
endowed with an invariant almost complex structure J and the canonical action
\theta of the maximal torus T ^{k} on G/H. We obtain explicit formula for the
cobordism class of such manifold through the weights of the action \theta at
the identity fixed point eH by an action of the quotient group W_G/W_H of the
Weyl groups for G and H. In this way we show that the cobordism class for such
manifolds can be computed explicitly without information on their cohomology.
We also show that formula for cobordism class provides an explicit way for
computing the classical Chern numbers for (G/H, J). As a consequence we obtain
that the Chern numbers for (G/H, J) can be computed without information on
cohomology for G/H. As an application we provide an explicit formula for
cobordism classes and characteristic numbers of the flag manifolds U(n)/T^n,
Grassmann manifolds G_{n,k}=U(n)/(U(k)\times U(n-k)) and some particular
interesting examples.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 16:36:29 GMT"
},
{
"version": "v2",
"created": "Mon, 3 Sep 2007 18:09:01 GMT"
}
] | 2007-09-03T00:00:00 | [
[
"Buchstaber",
"Victor M.",
""
],
[
"Terzic",
"Svjetlana",
""
]
] |
0708.2055 | David Gfeller | David Gfeller, Paolo De Los Rios | Spectral Coarse Graining and Synchronization in Oscillator Networks | 4 pages, 3 figures | null | 10.1103/PhysRevLett.100.174104 | null | cond-mat.dis-nn | null | Coarse graining techniques offer a promising alternative to large-scale
simulations of complex dynamical systems, as long as the coarse-grained system
is truly representative of the initial one. Here, we investigate how the
dynamical properties of oscillator networks are affected when some nodes are
merged together to form a coarse-grained network. Moreover, we show that there
exists a way of grouping nodes preserving as much as possible some crucial
aspects of the network dynamics. This coarse graining approach provides a
useful method to simplify complex oscillator networks, and more generally any
network whose dynamics involves a Laplacian matrix.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 14:35:45 GMT"
},
{
"version": "v2",
"created": "Tue, 11 Mar 2008 15:50:35 GMT"
},
{
"version": "v3",
"created": "Thu, 13 Mar 2008 13:01:54 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Gfeller",
"David",
""
],
[
"Rios",
"Paolo De Los",
""
]
] |
0708.2056 | Victor Chulaevsky | Victor Chulaevsky, Yuri M. Suhov | Wegner bounds for a two-particle tight binding model | null | null | 10.1007/s00220-008-0508-3 | null | math-ph math.MP | null | We consider a quantum two-particle system on a d-dimensional lattice with
interaction and in presence of an IID external potential. We establish
Wegner-typer estimates for such a model. The main tool used is Stollmann's
lemma.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 18:58:39 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Chulaevsky",
"Victor",
""
],
[
"Suhov",
"Yuri M.",
""
]
] |
0708.2057 | Zaqarashvili | T. V. Zaqarashvili, E. Khutsishvili, V. Kukhianidze and G. Ramishvili | Doppler shift oscillations in solar spicules | 7 pages, 8 figures, accepted in A&A | null | 10.1051/0004-6361:20077661 | null | astro-ph | null | Consecutive height series of Ha spectra in solar limb spicules taken on the
53 cm coronagraph of Abastumani Astrophysical Observatory at the heights of
3800-8700 km above the photosphere have been analyzed. The aim is to observe
oscillatory phenomena in spicules and consequently to trace wave propagations
through the chromosphere. The Discrete Fourier Transform analysis of Ha Doppler
shift time series constructed from the observed spectra at each height is used.
Doppler velocities of solar limb spicules show oscillations with periods of
20-55 and 75-110 s. There is also the clear evidence of 3-min oscillations at
the observed heights. The oscillations can be caused by wave propagations in
thin magnetic flux tubes anchored in the photosphere. We suggest the
granulation as a possible source for the wave excitation. Observed waves can be
used as a tool for spicule seismology; the magnetic field strength in spicules
at the height of about 6000 km above the photosphere is estimated as 12-15 G.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 14:58:03 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Zaqarashvili",
"T. V.",
""
],
[
"Khutsishvili",
"E.",
""
],
[
"Kukhianidze",
"V.",
""
],
[
"Ramishvili",
"G.",
""
]
] |
0708.2058 | Mohammad M. Sheikh-Jabbari | M. Ali-Akbari, M. M. Sheikh-Jabbari | Electrified BPS Giants: BPS configurations on Giant Gravitons with
Static Electric Field | 32 pages, 1 eps figure; v2: Presentation of derivation of light-cone
Hamiltonian improved, Refs added | JHEP 0710:043,2007 | 10.1088/1126-6708/2007/10/043 | IPM/P-2007/039, SUT-P-07-2a | hep-th | null | We consider D3-brane action in the maximally supersymmetric type IIB
plane-wave background. Upon fixing the light-cone gauge, we obtain the
light-cone Hamiltonian which is manifestly supersymmetric. The 1/2 BPS
solutions of this theory (solutions which preserve 16 supercharges) are either
of the form of spherical three branes, the giant gravitons, or zero size point
like branes. We then construct specific classes of 1/4 BPS solutions of this
theory in which static electric field on the brane is turned on. These
solutions are deformations about either of the two 1/2 BPS solutions. In
particular, we study in some detail 1/4 BPS configurations with electric dipole
on the three sphere giant, i.e. BIons on the giant gravitons, which we hence
call BIGGons. We also study BPS configurations corresponding to turning on a
background uniform constant electric field. As a result of this background
electric field the three sphere giant is deformed to squashed sphere, while the
zero size point like branes turn into circular or straight fundamental strings
in the plane-wave background, with their tension equal to the background
electric field.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 15:16:45 GMT"
},
{
"version": "v2",
"created": "Sat, 25 Aug 2007 13:26:34 GMT"
}
] | 2009-06-11T00:00:00 | [
[
"Ali-Akbari",
"M.",
""
],
[
"Sheikh-Jabbari",
"M. M.",
""
]
] |
0708.2059 | Robert Pelcovits | Robert A. Pelcovits, J.-B. Lee and R. B. Meyer | Dynamics of the molecular orientation field coupled to ions in
two-dimensional ferroelectric liquid crystals | null | null | 10.1103/PhysRevE.76.021704 | null | cond-mat.soft cond-mat.stat-mech | null | Molecular orientation fluctuations in ferroelectric smectic liquid crystals
produce space charges, due to the divergence of the spontaneous polarization.
These space charges interact with mobile ions, so that one must consider the
coupled dynamics of the orientation and ionic degrees of freedom. Previous
theory and light scattering experiments on thin free-standing films of
ferroelectric liquid crystals have not included this coupling, possibly
invalidating their quantitative conclusions. We consider the most important
case of very slow ionic dynamics, compared to rapid orientational fluctuations,
and focus on the use of a short electric field pulse to quench orientational
fluctuations. We find that the resulting change in scattered light intensity
must include a term due to the quasistatic ionic configuration, which has
previously been ignored. In addition to developing the general theory, we
present a simple model to demonstrate the role of this added term.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 18:53:05 GMT"
}
] | 2007-08-16T00:00:00 | [
[
"Pelcovits",
"Robert A.",
""
],
[
"Lee",
"J. -B.",
""
],
[
"Meyer",
"R. B.",
""
]
] |
0708.2060 | Babiker Hassanain | Babiker Hassanain, John March-Russell and Martin Schvellinger | Warped Deformed Throats have Faster (Electroweak) Phase Transitions | published version, 18 pages, minor typo corrected, reference added | JHEP 0710:089,2007 | 10.1088/1126-6708/2007/10/089 | null | hep-th | null | We study the dynamics of the finite-temperature phase transition for warped
Randall-Sundrum(RS)-like throat models related to the Klebanov-Tseytlin
solution. We find that, for infrared branes stabilized near the tip of the
throat, the bounce action has a mild N^2 dependence, where N(y) \sim [M_5
L(y)]^{3/2} is the effective number of degrees of freedom of the holographic
dual QFT, and where L(y) is the local curvature radius, which decreases in the
infrared. In addition, the bounce action is not enhanced by large numbers.
These features allow the transition to successfully complete over a wider
parameter range than for Goldberger-Wise stabilized RS models. Due to the
increase of L(y) in the ultraviolet, the throat has a reliable gravitational
description even when the number of infrared degrees of freedom is small. We
also comment on aspects of the thermal phase transition in Higgsless models,
where the gauge symmetry breaking is achieved via boundary conditions. Such
models include orbifold-GUT models and the Higgsless electroweak symmetry
breaking theories of Csaki et al., with Standard Model gauge fields living in
the bulk.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 15:17:43 GMT"
},
{
"version": "v2",
"created": "Thu, 1 Nov 2007 12:17:14 GMT"
}
] | 2009-03-27T00:00:00 | [
[
"Hassanain",
"Babiker",
""
],
[
"March-Russell",
"John",
""
],
[
"Schvellinger",
"Martin",
""
]
] |
0708.2061 | Eduardo Candelario-Jalil | E. Candelario-Jalil, S. M. Al-Dalain, R. Castillo, G. Martinez, O. S.
Fernandez | Selective vulnerability to kainate-induced oxidative damage in different
rat brain regions | null | Journal of Applied Toxicology 21(5): 403-407 (2001) | null | null | q-bio.TO | null | Some markers of oxidative injury were measured in different rat brain areas
(hippocampus, cerebral cortex, striatum, hypothalamus, amygdala/piriform cortex
and cerebellum) after the systemic administration of an excitotoxic dose of
kainic acid (KA, 9 mg kg(-1) i.p.) at two different sampling times (24 and 48
h). Kainic acid was able to lower markedly (P < 0.05) the glutathione (GSH)
levels in hippocampus, cerebellum and amygdala/piriform cortex (maximal
reduction at 24 h). In a similar way, lipid peroxidation, as assessed by
malonaldehyde and 4-hydroxyalkenal levels, significantly increased (P < 0.05)
in hippocampus, cerebellum and amygdala/piriform cortex mainly at 24 h after
KA. In addition, hippocampal superoxide dismutase (SOD) activity decreased
significantly (P < 0.05) with respect to basal levels by 24 h after KA
application. On the other hand, brain areas such as hypothalamus, striatum and
cerebral cortex seem to be less susceptible to KA excitotoxicity. According to
these findings, the pattern of oxidative injury induced by systemically
administered KA seems to be highly region-specific. Further, our results have
shown that a lower antioxidant status (GSH and SOD) seems not to play an
important role in the selective vulnerability of certain brain regions because
it correlates poorly with increases in markers of oxidative damage.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 15:31:13 GMT"
}
] | 2007-08-16T00:00:00 | [
[
"Candelario-Jalil",
"E.",
""
],
[
"Al-Dalain",
"S. M.",
""
],
[
"Castillo",
"R.",
""
],
[
"Martinez",
"G.",
""
],
[
"Fernandez",
"O. S.",
""
]
] |
0708.2062 | Davide Marenduzzo | D. Marenduzzo, E. Orlandini, M. E. Cates, J. M. Yeomans | Steady-state hydrodynamic instabilities of active liquid crystals:
Hybrid lattice Boltzmann simulations | 18 eps figures, accepted for publication in Phys. Rev. E | null | 10.1103/PhysRevE.76.031921 | null | cond-mat.soft | null | We report hybrid lattice Boltzmann (HLB) simulations of the hydrodynamics of
an active nematic liquid crystal sandwiched between confining walls with
various anchoring conditions. We confirm the existence of a transition between
a passive phase and an active phase, in which there is spontaneous flow in the
steady state. This transition is attained for sufficiently ``extensile'' rods,
in the case of flow-aligning liquid crystals, and for sufficiently
``contractile'' ones for flow-tumbling materials. In a quasi-1D geometry, deep
in the active phase of flow-aligning materials, our simulations give evidence
of hysteresis and history-dependent steady states, as well as of spontaneous
banded flow. Flow-tumbling materials, in contrast, re-arrange themselves so
that only the two boundary layers flow in steady state. Two-dimensional
simulations, with periodic boundary conditions, show additional instabilities,
with the spontaneous flow appearing as patterns made up of ``convection
rolls''. These results demonstrate a remarkable richness (including dependence
on anchoring conditions) in the steady-state phase behaviour of active
materials, even in the absence of external forcing; they have no counterpart
for passive nematics. Our HLB methodology, which combines lattice Boltzmann for
momentum transport with a finite difference scheme for the order parameter
dynamics, offers a robust and efficient method for probing the complex
hydrodynamic behaviour of active nematics.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 15:31:56 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Marenduzzo",
"D.",
""
],
[
"Orlandini",
"E.",
""
],
[
"Cates",
"M. E.",
""
],
[
"Yeomans",
"J. M.",
""
]
] |
0708.2063 | Ericson Lopez I. | Ericsson D. Lopez | Pulsar Radio Emission Cutoffs | 8 pages, no figures | Published in: CP784, Magnetic Fields in the Universe: From
Laboratory and Stars to Primordial Structures, edited by E.M. de Gouveia Dal
ino, G. Lugones and A. Lazarian, (2005), 697 | 10.1063/1.2077237 | null | astro-ph | null | The propagation of radio emission in pulsar magnetospheres is discussed. We
follow a kinematics model in order to derive dispersion relations for
electromagnetic oscillations and transversal waves, propagating in a cold
moving plasma. We have included relativistic corrections on the dispersion
properties, involved with the relativistic motion of the emitting plasma. The
occurrence of plasma instabilities is analyzed beside the conditions which
should be fulfilled in order to permit the wave propagation and conversion in
regions close to the cutoffs of the system. The existence of various
frequencies of resonance has been predicted and we are working out these
results in order to explain the low-frequency cutoffs observed in radio pulsar
spectra.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 15:39:44 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Lopez",
"Ericsson D.",
""
]
] |
0708.2064 | Manoj Puravankara | P. Manoj (ASIAA, Taiwan), Paul T. P. Ho (SAO/ASIAA), Nagayoshi Ohashi
(ASIAA), Qizhou Zhang (CfA), T. Hasegawa (ASIAA), Huei-Ru Chen (NTHU,
Taiwan), H. C. Bhatt (IIA, Bangalore, India), N. M. Ashok (PRL, Ahmedabad,
India) | An evolved disk surrounding the massive main sequence star MWC 297? | 4 pages, 3 Figures, accepted for publication in ApJL | null | 10.1086/522424 | null | astro-ph | null | We present the results of the interferometric observations of the
circumstellar disk surrounding MWC 297 in the continuum at 230 GHz (1.3 mm) and
in the (J=2-1) rotational transitions of $^{12}$CO,$^{13}$CO and C$^{18}$O
using the Submillimeter Array. At a distance of 250 pc, MWC 297 is one of the
closest, young massive stars (M$_{\star}$ $\sim$10 M$_{\odot}$) to us. Compact
continuum emission is detected towards MWC 297 from which we estimate a disk
mass (gas+dust) of 0.07 M$_{\odot}$ and a disk radius of $\le$ 80 AU. Our
result demonstrates that circumstellar disks can survive around massive stars
well into their main sequence phase even after they have become optically
visible. Complementing our observations with the data compiled from the
literature, we find the submm dust opacity index $\beta$ to be between 0.1 and
0.3. If the emission is optically thin, the low value of $\beta$ indicates the
presence of relatively large grains in the disk, possibly because of grain
growth. We do not detect any CO emission associated with the continuum source.
We argue that the $^{13}$CO emission from the disk is likely optically thin, in
which case, we derive an upper limit to the gas mass which implies significant
depletion of molecular gas in the disk. The mass of this disk and the
evolutionary trends observed are similar to those found for intermediate mass
Herbig Ae stars and low mass T Tauri stars.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 15:46:20 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Manoj",
"P.",
"",
"ASIAA, Taiwan"
],
[
"Ho",
"Paul T. P.",
"",
"SAO/ASIAA"
],
[
"Ohashi",
"Nagayoshi",
"",
"ASIAA"
],
[
"Zhang",
"Qizhou",
"",
"CfA"
],
[
"Hasegawa",
"T.",
"",
"ASIAA"
],
[
"Chen",
"Huei-Ru",
"",
"NTHU,\n Taiwan"
],
[
"Bhatt",
"H. C.",
"",
"IIA, Bangalore, India"
],
[
"Ashok",
"N. M.",
"",
"PRL, Ahmedabad,\n India"
]
] |
0708.2065 | Rodrigo D\'iaz Mr. | Rodrigo F. D\'iaz (1), Jorge F. Gonz\'alez (2), Carolina Cincunegui
(1), Pablo J.D. Mauas (1) ((1) IAFE, Buenos Aires, Argentina; (2) CASLEO, San
Juan, Argentina) | The spectroscopic binary system Gl 375. I. Orbital parameters and
chromospheric activity | 10 pages, including 11 figures and 3 tables. Accepted for publication
in Astronomy & Astrophysics | null | 10.1051/0004-6361:20078195 | null | astro-ph | null | We study the spectroscopic binary system Gl 375. We employ medium resolution
echelle spectra obtained at the 2.15 m telescope at the Argentinian observatory
CASLEO and photometric observations obtained from the ASAS database. We
separate the composite spectra into those corresponding to both components. The
separated spectra allow us to confirm that the spectral types of both
components are similar (dMe3.5) and to obtain precise measurements of the
orbital period (P = 1.87844 days), minimum masses (M_1 sin^3 i = 0.35 M_sun and
M_2 sin^3 i =0.33 M_sun) and other orbital parameters. The photometric
observations exhibit a sinusoidal variation with the same period as the orbital
period. We interpret this as signs of active regions carried along with
rotation in a tidally synchronized system, and study the evolution of the
amplitude of the modulation in longer timescales. Together with the mean
magnitude, the modulation exhibits a roughly cyclic variation with a period of
around 800 days. This periodicity is also found in the flux of the Ca II K
lines of both components, which seem to be in phase. The periodic changes in
the three observables are interpreted as a sign of a stellar activity cycle.
Both components appear to be in phase, which implies that they are magnetically
connected. The measured cycle of approximately 2.2 years (800 days) is
consistent with previous determinations of activity cycles in similar stars.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 16:00:17 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Díaz",
"Rodrigo F.",
""
],
[
"González",
"Jorge F.",
""
],
[
"Cincunegui",
"Carolina",
""
],
[
"Mauas",
"Pablo J. D.",
""
]
] |
0708.2066 | Jorick S. Vink | Jorick S. Vink, P. Benaglia, B. Davies, A. de Koter and R. D.
Oudmaijer | Advances in mass-loss predictions | 3 pages, 3 figures, to appear in the proceedings of workshop
'Clumping in Hot Star Winds', eds. W.-R. Hamann, A. Feldmeier, & L. Oskinova | null | null | null | astro-ph | null | We present the results of Monte Carlo mass-loss predictions for massive stars
covering a wide range of stellar parameters. We critically test our predictions
against a range of observed mass-loss rates -- in light of the recent
discussions on wind clumping. We also present a model to compute the
clumping-induced polarimetric variability of hot stars and we compare this with
observations of Luminous Blue Variables, for which polarimetric variability is
larger than for O and Wolf-Rayet stars. Luminous Blue Variables comprise an
ideal testbed for studies of wind clumping and wind geometry, as well as for
wind strength calculations, and we propose they may be direct supernova
progenitors.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 16:06:05 GMT"
}
] | 2007-08-16T00:00:00 | [
[
"Vink",
"Jorick S.",
""
],
[
"Benaglia",
"P.",
""
],
[
"Davies",
"B.",
""
],
[
"de Koter",
"A.",
""
],
[
"Oudmaijer",
"R. D.",
""
]
] |
0708.2067 | Clark Barwick | Clark Barwick | On (Enriched) Left Bousfield Localization of Model Categories | 40 pages. Comments sincerely welcomed | null | null | null | math.AT math.CT | null | I verify the existence of left Bousfield localizations and of enriched left
Bousfield localizations, and I prove a collection of useful technical results
characterizing certain fibrations of (enriched) left Bousfield localizations. I
also use such Bousfield localizations to construct a number of new model
categories, including models for the homotopy limit of right Quillen
presheaves, for Postnikov towers in model categories, and for presheaves valued
in a symmetric monoidal model category satisfying a homotopy-coherent descent
condition.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 16:10:09 GMT"
},
{
"version": "v2",
"created": "Thu, 29 Nov 2007 15:59:27 GMT"
}
] | 2007-11-29T00:00:00 | [
[
"Barwick",
"Clark",
""
]
] |
0708.2068 | Kazem Azizi | K. Azizi, V. Bashiry | QCD sum rules analysis of the rare radiative Bc -> D*_s gamma decay | 29 pages, Three Figures and two Tables | Phys.Rev.D76:114007,2007. | 10.1103/PhysRevD.76.114007 | null | hep-ph | null | In this work, the radiative Bc -> D*_s gamma decay is investigated in the
framework of QCD sum rules. The transition form factors responsible for the
decay are calculated. The branching ratio for this decay is estimated to be
order of 10^-5 which can be measurable at LHC.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 16:39:17 GMT"
},
{
"version": "v2",
"created": "Mon, 22 Oct 2007 14:37:32 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Azizi",
"K.",
""
],
[
"Bashiry",
"V.",
""
]
] |
0708.2069 | Friedrich W. Hehl | Friedrich W. Hehl, Yuri N. Obukhov, Jean-Pierre Rivera, Hans Schmid | Relativistic analysis of magnetoelectric crystals: extracting a new
4-dimensional P odd and T odd pseudoscalar from Cr_2 O_3 data | 6 pages latex, 3 figures, accepted by Physics Letters A | null | 10.1016/j.physleta.2007.08.069 | null | gr-qc hep-th physics.class-ph | null | Earlier, the linear magnetoelectric effect of chromium sesquioxide Cr_2 O_3
has been determined experimentally as a function of temperature. One measures
the electric field-induced magnetization on Cr_2 O_3 crystals or the magnetic
field-induced polarization. From the magnetoelectric moduli of Cr_2 O_3 we
extract a 4-dimensional relativistic invariant pseudoscalar \tilde\alpha. It is
temperature dependent and of the order of ~ 10^{-4} Y_0, with Y_0 as vacuum
admittance. We show that the new pseudoscalar \tilde\alpha is odd under parity
transformation and odd under time inversion. Moreover, \tilde\alpha is for Cr_2
O_3 what Tellegen's gyrator is for two port theory, the axion field for axion
electrodynamics, and the PEMC (perfect electromagnetic conductor) for
electrical engineering.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 16:45:52 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Hehl",
"Friedrich W.",
""
],
[
"Obukhov",
"Yuri N.",
""
],
[
"Rivera",
"Jean-Pierre",
""
],
[
"Schmid",
"Hans",
""
]
] |
0708.2070 | Ettore Minguzzi | E. Minguzzi | The causal ladder and the strength of K-causality. I | 16 pages, one figure. Old title: ``On the relationship between
K-causality and infinite A-causality''. Some typos fixed; small change in the
proof of lemma 4.2 | Class.Quant.Grav.25:015009,2008 | 10.1088/0264-9381/25/1/015009 | null | gr-qc | null | A unifying framework for the study of causal relations is presented. The
causal relations are regarded as subsets of M x M and the role of the
corresponding antisymmetry conditions in the construction of the causal ladder
is stressed. The causal hierarchy of spacetime is built from chronology up to
K-causality and new characterizations of the distinction and strong causality
properties are obtained. The closure of the causal future is not transitive, as
a consequence its repeated composition leads to an infinite causal subladder
between strong causality and K-causality - the A-causality subladder. A
spacetime example is given which proves that K-causality differs from infinite
A-causality.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 16:58:23 GMT"
},
{
"version": "v2",
"created": "Mon, 19 Nov 2007 17:00:21 GMT"
},
{
"version": "v3",
"created": "Mon, 3 Dec 2007 16:16:59 GMT"
}
] | 2011-07-08T00:00:00 | [
[
"Minguzzi",
"E.",
""
]
] |
0708.2071 | Hanns-Ulrich Habermeier | H.-U. Habermeier | Eduction and Economy -- An Analysis of Statistical Data | 15 pages | Journal of Materials Education Vol. 29 (1-2): 55-70 (2007) | null | null | physics.soc-ph physics.ed-ph q-fin.GN | null | In this paper the correlation between education, research and macroeconomic
strength of countries at a global scale is analyzed on the basis of statistical
data published by the UNIDO and OECD. It uses sets of composite indicators
describing the economical performance and competitiveness as well as those
relevant for human development, education, knowledge and technology achievement
and correlates them. It turns out that for countries with a human development
index (HDI) below 0.7 the basic education and technology achievement indices
are the driving force for further development, whereas for the industrialized
countries the knowledge index as a composite education and communication index
has the strongest effect on the economic strength of a country as measured by
the gross domestic product.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 17:09:14 GMT"
}
] | 2008-12-02T00:00:00 | [
[
"Habermeier",
"H. -U.",
""
]
] |
0708.2072 | Adam Lichtl | John Bulava, Robert Edwards, George Fleming, K. Jimmy Juge, Adam C.
Lichtl, Nilmani Mathur, Colin Morningstar, David Richards, Stephen J. Wallace | Hadronic Resonances from Lattice QCD | 8 pages, VII Latin American Symposium on Nuclear Physics and
Applications | AIP Conf.Proc.947:77-84,2007 | 10.1063/1.2813876 | null | hep-lat nucl-th | null | The determination of the pattern of hadronic resonances as predicted by
Quantum Chromodynamics requires the use of non-perturbative techniques. Lattice
QCD has emerged as the dominant tool for such calculations, and has produced
many QCD predictions which can be directly compared to experiment. The concepts
underlying lattice QCD are outlined, methods for calculating excited states are
discussed, and results from an exploratory Nucleon and Delta baryon spectrum
study are presented.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 17:19:23 GMT"
},
{
"version": "v2",
"created": "Thu, 16 Aug 2007 01:03:38 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Bulava",
"John",
""
],
[
"Edwards",
"Robert",
""
],
[
"Fleming",
"George",
""
],
[
"Juge",
"K. Jimmy",
""
],
[
"Lichtl",
"Adam C.",
""
],
[
"Mathur",
"Nilmani",
""
],
[
"Morningstar",
"Colin",
""
],
[
"Richards",
"David",
""
],
[
"Wallace",
"Stephen J.",
""
]
] |
0708.2073 | Patricia Lee | M. Anderlini, P. J. Lee, B. L. Brown, J. Sebby-Strabley, W. D.
Phillips, J. V. Porto | Controlled exchange interaction between pairs of neutral atoms in an
optical lattice | null | Nature 448, 452-456 (2007) | 10.1038/nature06011 | null | quant-ph | null | Ultra-cold atoms trapped by light, with their robust quantum coherence and
controllability, provide an attractive system for quantum information
processing and for simulation of complex problems in condensed matter physics.
Many quantum information processing schemes require that individual qubits be
manipulated and deterministically entangled with one another, a process that
would typically be accomplished by controlled, state-dependent, coherent
interactions among qubits. Recent experiments have made progress toward this
goal by demonstrating entanglement among an ensemble of atoms confined in an
optical lattice. Until now, however, there has been no demonstration of a key
operation: controlled entanglement between atoms in isolated pairs. We have
used an optical lattice of double-well potentials to isolate and manipulate
arrays of paired atoms, inducing controlled entangling interactions within each
pair. Our experiment is the first realization of proposals to use controlled
exchange coupling in a system of neutral atoms. Although 87Rb atoms have nearly
state-independent interactions, when we force two atoms into the same physical
location, the wavefunction exchange symmetry of these identical bosons leads to
state-dependent dynamics. We observe repeated interchange of spin between atoms
occupying different vibrational levels, with a coherence time of more than ten
milliseconds. This observation represents the first demonstration of the
essential component of a quantum SWAP gate in neutral atoms. The "half
implementation" of SWAP, the sqrt(SWAP) gate, is entangling, and together with
single qubit rotations form a set of universal gates for quantum computation.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 17:19:17 GMT"
}
] | 2007-08-16T00:00:00 | [
[
"Anderlini",
"M.",
""
],
[
"Lee",
"P. J.",
""
],
[
"Brown",
"B. L.",
""
],
[
"Sebby-Strabley",
"J.",
""
],
[
"Phillips",
"W. D.",
""
],
[
"Porto",
"J. V.",
""
]
] |
0708.2074 | Sergei Kozyrev | S. Albeverio, S. V. Kozyrev | Multidimensional ultrametric pseudodifferential equations | 20 pages | Proceedings of the Steklov Institute of Mathematics, 2009, 265,
13--29 | null | null | math-ph math.MP | null | We develop an analysis of wavelets and pseudodifferential operators on
multidimensional ultrametric spaces which are defined as products of locally
compact ultrametric spaces. We introduce bases of wavelets, spaces of
generalized functions and Lizorkin generalized functions on multidimensional
ultrametric spaces.
We also consider some family of pseudodifferential operators on
multidimensional ultrametric spaces. The notions of Cauchy problem for
ultrametric pseudodifferential equations and of ultrametric characteristics are
introduced. A theorem about existence and uniqueness of the solution for the
Cauchy problem (the analogue of the Kovalevskaya theorem) is proven.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 17:34:01 GMT"
}
] | 2011-05-10T00:00:00 | [
[
"Albeverio",
"S.",
""
],
[
"Kozyrev",
"S. V.",
""
]
] |
0708.2075 | Puru Gujrati | P. D. Gujrati | Entropy Crisis, Defects and the Role of Competition in Monatomic Glass
Formers | 4 pages, 3 figures | null | null | UATP/07-01 | cond-mat.soft cond-mat.stat-mech | null | We establish the existence of an entropy crisis in monatomic glass formers.
The work finally shows that the entropy crisis is ubiqutous in all supercooled
liquids. We also study the roles of defects and energetic competition on the
ideal glass.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 17:58:53 GMT"
}
] | 2007-08-16T00:00:00 | [
[
"Gujrati",
"P. D.",
""
]
] |
0708.2076 | Loreto Bravo | Loreto Bravo, James Cheney and Irini Fundulaki | Repairing Inconsistent XML Write-Access Control Policies | 25 pages. To appear in Proceedings of DBPL 2007 | null | null | null | cs.DB | null | XML access control policies involving updates may contain security flaws,
here called inconsistencies, in which a forbidden operation may be simulated by
performing a sequence of allowed operations. This paper investigates the
problem of deciding whether a policy is consistent, and if not, how its
inconsistencies can be repaired. We consider policies expressed in terms of
annotated DTDs defining which operations are allowed or denied for the XML
trees that are instances of the DTD. We show that consistency is decidable in
PTIME for such policies and that consistent partial policies can be extended to
unique "least-privilege" consistent total policies. We also consider repair
problems based on deleting privileges to restore consistency, show that finding
minimal repairs is NP-complete, and give heuristics for finding repairs.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 18:31:48 GMT"
}
] | 2007-08-16T00:00:00 | [
[
"Bravo",
"Loreto",
""
],
[
"Cheney",
"James",
""
],
[
"Fundulaki",
"Irini",
""
]
] |
0708.2077 | Greg Morrison | Ngo Minh Toan, Greg Morrison, Changbong Hyeon and D. Thirumalai | Kinetics of Loop Formation in Polymer Chains | 30 pages, 9 figures. Revised version includes a new figure (8) and
minor changes to the text | null | null | null | cond-mat.soft | null | We investigate the kinetics of loop formation in flexible ideal polymer
chains (Rouse model), and polymers in good and poor solvents. We show for the
Rouse model, using a modification of the theory of Szabo, Schulten, and
Schulten, that the time scale for cyclization is $\tau_c\sim \tau_0 N^2$ (where
$\tau_0$ is a microscopic time scale and $N$ is the number of monomers),
provided the coupling between the relaxation dynamics of the end-to-end vector
and the looping dynamics is taken into account. The resulting analytic
expression fits the simulation results accurately when $a$, the capture radius
for contact formation, exceeds $b$, the average distance between two connected
beads. Simulations also show that, when $a < b$, $\tau_c\sim N^{\alpha_\tau}$,
where $1.5<{\alpha_\tau}\le 2$ in the range $7<N<200$ used in the simulations.
By using a diffusion coefficient that is dependent on the length scales $a$ and
$b$ (with $a<b$), which captures the two-stage mechanism by which looping
occurs when $a < b$, we obtain an analytic expression for $\tau_c$ that fits
the simulation results well. The kinetics of contact formation between the ends
of the chain are profoundly affected when interactions between monomers are
taken into account. Remarkably, for $N < 100$ the values of $\tau_c$ decrease
by more than two orders of magnitude when the solvent quality changes from good
to poor. Fits of the simulation data for $\tau_c$ to a power law in $N$
($\tau_c\sim N^{\alpha_\tau}$) show that $\alpha_\tau$ varies from about 2.4 in
a good solvent to about 1.0 in poor solvents. Loop formation in poor solvents,
in which the polymer adopts dense, compact globular conformations, occurs by a
reptation-like mechanism of the ends of the chain.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 18:33:55 GMT"
},
{
"version": "v2",
"created": "Tue, 13 Nov 2007 21:14:45 GMT"
}
] | 2007-11-13T00:00:00 | [
[
"Toan",
"Ngo Minh",
""
],
[
"Morrison",
"Greg",
""
],
[
"Hyeon",
"Changbong",
""
],
[
"Thirumalai",
"D.",
""
]
] |
0708.2078 | Viktor Levandovskyy | Viktor Levandovskyy and Eva Zerz | Obstructions to Genericity in Study of Parametric Problems in Control
Theory | 20 pages | null | null | null | math.OC cs.SC math.RA | null | We investigate systems of equations, involving parameters from the point of
view of both control theory and computer algebra. The equations might involve
linear operators such as partial (q-)differentiation, (q-)shift, (q-)difference
as well as more complicated ones, which act trivially on the parameters. Such a
system can be identified algebraically with a certain left module over a
non-commutative algebra, where the operators commute with the parameters. We
develop, implement and use in practice the algorithm for revealing all the
expressions in parameters, for which e.g. homological properties of a system
differ from the generic properties. We use Groebner bases and Groebner basics
in rings of solvable type as main tools. In particular, we demonstrate an
optimized algorithm for computing the left inverse of a matrix over a ring of
solvable type. We illustrate the article with interesting examples. In
particular, we provide a complete solution to the "two pendula, mounted on a
cart" problem from the classical book of Polderman and Willems, including the
case, where the friction at the joints is essential . To the best of our
knowledge, the latter example has not been solved before in a complete way.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 19:12:15 GMT"
}
] | 2010-03-22T00:00:00 | [
[
"Levandovskyy",
"Viktor",
""
],
[
"Zerz",
"Eva",
""
]
] |
0708.2079 | Apostolos Pilaftsis | John Ellis, Jae Sik Lee and Apostolos Pilaftsis | B-Meson Observables in the Maximally CP-Violating MSSM with Minimal
Flavour Violation | 47 pages, 8 eps figures, comments and references added, accepted for
publication in Physical Review D, Eq.(3.2) corrected | Phys.Rev.D76:115011,2007 | 10.1103/PhysRevD.76.115011 | CERN-PH-TH/2007-136, MAN/HEP/2007/13 | hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Additional sources of CP violation in the MSSM may affect B-meson mixings and
decays, even in scenarios with minimal flavour violation (MFV). We formulate
the maximally CP-violating and minimally flavour-violating (MCPMFV) variant of
the MSSM, which has 19 parameters, including 6 phases that violate CP. We then
develop a manifestly flavour-covariant effective Lagrangian formalism for
calculating Higgs-mediated FCNC observables in the MSSM at large tan(beta), and
analyze within the MCPMFV framework FCNC and other processes involving B
mesons. We include a new class of dominant subleading contributions due to
non-decoupling effects of the third-generation quarks. We present illustrative
numerical results that include effects of the CP-odd MCPMFV parameters on Higgs
and sparticle masses, the B_s and B_d mass differences, and on the decays B_s
--> mu+ mu-, B_u --> tau nu and b --> s gamma. We use these results to derive
illustrative constraints on the MCPMFV parameters imposed by D0, CDF, BELLE and
BABAR measurements of B mesons, demonstrating how a potentially observable
contribution to the CP asymmetry in the b --> s gamma decay may arise in the
MSSM with MCPMFV.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 18:47:54 GMT"
},
{
"version": "v2",
"created": "Sat, 27 Oct 2007 06:38:24 GMT"
},
{
"version": "v3",
"created": "Tue, 20 Nov 2007 04:56:49 GMT"
},
{
"version": "v4",
"created": "Fri, 12 Sep 2008 15:15:47 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Ellis",
"John",
""
],
[
"Lee",
"Jae Sik",
""
],
[
"Pilaftsis",
"Apostolos",
""
]
] |
0708.2080 | Tabare Gallardo | Tabare Gallardo | Evaluating the Signatures of the Mean Motion Resonances in the Solar
System | 15 pages, 1 table, 7 figures | null | null | null | astro-ph | null | The characteristics of the resonant disturbing function for an asteroid
perturbed by a planet in circular orbit are discussed. The location of the
libration centers and their dependence with the orbital elements of the
resonant orbit are analyzed. A proposed numerical method (Gallardo 2006a) for
computing the strengths of the resonances is revised and applied to the region
of the main belt of asteroids showing the relevance of several mean motion
resonances (MMR) with several planets.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 18:36:54 GMT"
}
] | 2007-08-16T00:00:00 | [
[
"Gallardo",
"Tabare",
""
]
] |
0708.2081 | Laurent Loinard | Laurent Loinard (CRyA-UNAM), Rosa M. Torres (CRyA-UNAM), Amy J.
Mioduszewski (AOC-NRAO), Luis F. Rodriguez (CRyA-UNAM), Rosa A.
Gonzalez-Lopezlira (CRyA-UNAM), Regis Lachaume (CRyA-UNAM), Virgilio Vazquez
(Univ. Mixteca), Erandy Gonzalez (Univ. Mixteca) | VLBA determination of the distance to nearby star-forming regions I. The
distance to T Tauri with 0.4% accuracy | 24 pages, 3 pages, AASTEX format, accepted for publication in ApJ | null | 10.1086/522493 | null | astro-ph | null | In this article, we present the results of a series of twelve 3.6-cm radio
continuum observations of T Tau Sb, one of the companions of the famous young
stellar object T Tauri. The data were collected roughly every two months
between September 2003 and July 2005 with the Very Long Baseline Array (VLBA).
Thanks to the remarkably accurate astrometry delivered by the VLBA, the
absolute position of T Tau Sb could be measured with a precision typically
better than about 100 micro-arcseconds at each of the twelve observed epochs.
The trajectory of T Tau Sb on the plane of the sky could, therefore, be traced
very precisely, and modeled as the superposition of the trigonometric parallax
of the source and an accelerated proper motion. The best fit yields a distance
to T Tau Sb of 147.6 +/- 0.6 pc. The observed positions of T Tau Sb are in good
agreement with recent infrared measurements, but seem to favor a somewhat
longer orbital period than that recently reported by Duchene et al. (2006) for
the T Tau Sa/T Tau Sb system.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 18:46:48 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Loinard",
"Laurent",
"",
"CRyA-UNAM"
],
[
"Torres",
"Rosa M.",
"",
"CRyA-UNAM"
],
[
"Mioduszewski",
"Amy J.",
"",
"AOC-NRAO"
],
[
"Rodriguez",
"Luis F.",
"",
"CRyA-UNAM"
],
[
"Gonzalez-Lopezlira",
"Rosa A.",
"",
"CRyA-UNAM"
],
[
"Lachaume",
"Regis",
"",
"CRyA-UNAM"
],
[
"Vazquez",
"Virgilio",
"",
"Univ. Mixteca"
],
[
"Gonzalez",
"Erandy",
"",
"Univ. Mixteca"
]
] |
0708.2082 | Francesca Aicardi | Francesca Aicardi | Symmetries of quadratic forms classes and of quadratic surds continued
fractions. Part II: Classification of the periods' palindromes | 37 pages, 6 figures | null | null | null | math.GM math.NT | null | The continue fractions of quadratic surds are periodic, according to a
theorem by Lagrange. Their periods may have differing types of symmetries. This
work relates these types of symmetries to the symmetries of the classes of the
corresponding indefinite quadratic forms. This allows to classify the periods
of quadratic surds and at the same time to find, for an arbitrary indefinite
quadratic form, the symmetry type of its class and the number of integer
points, for that class, contained in each domain of the Poincare' model of the
de Sitter world, introduced in Part I. Moreover, we obtain the same information
for every class of forms representing zero, by the finite continue fraction
related to a special representative of that class. We will see finally the
relation between the reduction procedure for indefinite quadratic forms,
defined by the continued fractions, and the classical reduction theory, which
acquires a geometrical description by the results of Part I.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 18:43:37 GMT"
},
{
"version": "v2",
"created": "Thu, 16 Aug 2007 07:38:38 GMT"
},
{
"version": "v3",
"created": "Thu, 27 Mar 2008 08:48:28 GMT"
}
] | 2008-03-27T00:00:00 | [
[
"Aicardi",
"Francesca",
""
]
] |
0708.2083 | Jie Chen | Jie Chen, Ruxandra I. Dima and D. Thirumalai | Allosteric communication in Dihydrofolate Reductase: Signaling network
and pathways for closed to occluded transition and back | 43 pages, 12 figures | null | null | null | q-bio.BM | null | E. Coli. dihydrofolate reductase (DHFR) undergoes conformational transitions
between the closed (CS) and occluded (OS) states which, respectively, describe
whether the active site is closed or occluded by the Met20 loop. A
sequence-based approach is used to identify a network of residues that
represents the allostery wiring diagram. We also use a self-organized polymer
model to monitor the kinetics of the CS->OS and the reverse transitions. a
sliding motion of Met20 loop is observed. The residues that facilitate the
Met20 loop motion are part of the network of residues that transmit allosteric
signals during the CS->OS transition.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 18:46:17 GMT"
}
] | 2007-08-16T00:00:00 | [
[
"Chen",
"Jie",
""
],
[
"Dima",
"Ruxandra I.",
""
],
[
"Thirumalai",
"D.",
""
]
] |
0708.2084 | Travis Gagie | Travis Gagie | Empirical entropy in context | A survey of some results related to empirical entropy, written in the
spring of 2007 as part of an introduction to a PhD thesis | null | null | null | cs.IT math.IT | null | We trace the history of empirical entropy, touching briefly on its relation
to Markov processes, normal numbers, Shannon entropy, the Chomsky hierarchy,
Kolmogorov complexity, Ziv-Lempel compression, de Bruijn sequences and
stochastic complexity.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 19:00:10 GMT"
}
] | 2007-08-16T00:00:00 | [
[
"Gagie",
"Travis",
""
]
] |
0708.2085 | Simon Rose | S. C. F. Rose | A hyperbolic approach to exp_3(S^1) | null | null | null | null | math.GT math.AT | null | In this paper we investigate a new geometric method of studying exp_k(S^1),
the set of all non-empty subsets of the circle of cardinality at most k. By
considering the circle as the boundary of the hyperbolic plane we are able to
use its group of isometries to determine explicitely the structure of its first
few configuration spaces. We then study how these configuration spaces fit
together in their union, exp_3(S^1), to reprove an old theorem of Bott as well
as to offer a new proof (following that of E. Shchepin) of the fact that the
embedding exp_1(S^1) into exp_3(S^1) is the trefoil knot.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 19:03:46 GMT"
}
] | 2007-08-16T00:00:00 | [
[
"Rose",
"S. C. F.",
""
]
] |
0708.2086 | Nigel Hussey | M. Abdel-Jawad, J. G. Analytis, L. Balicas, A. Carrington, J. P. H.
Charmant, M. M. J. French and N. E. Hussey | Correlation between $T_c$ and anisotropic scattering in
Tl$_2$Ba$_2$CuO$_{6+\delta}$ | 5 pages, 3 figures, accepted for publication in Physical Review
Letters | Phys. Rev. Lett. vol. 99, 107002 (2007) | 10.1103/PhysRevLett.99.107002 | null | cond-mat.supr-con cond-mat.str-el | null | Angle-dependent magnetoresistance measurements are used to determine the
isotropic and anisotropic components of the transport scattering rate in
overdoped Tl$_2$Ba$_2$CuO$_{6+\delta}$ for a range of $T_c$ values between 15K
and 35K. The size of the anisotropic scattering term is found to scale linearly
with $T_c$, establishing a link between the superconducting and normal state
physics. Comparison with results from angle resolved photoemission spectroscopy
indicates that the transport and quasiparticle lifetimes are distinct.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 19:03:48 GMT"
}
] | 2007-09-18T00:00:00 | [
[
"Abdel-Jawad",
"M.",
""
],
[
"Analytis",
"J. G.",
""
],
[
"Balicas",
"L.",
""
],
[
"Carrington",
"A.",
""
],
[
"Charmant",
"J. P. H.",
""
],
[
"French",
"M. M. J.",
""
],
[
"Hussey",
"N. E.",
""
]
] |
0708.2087 | Nikolai Moshchevitin | Nikolai G. Moshchevitin | A version of the proof for Peres-Schlag's theorem on lacunary sequences | 9 pages | null | null | null | math.NT | null | We present a proof of a multidimensional version of Peres-Schlag's theorem on
Diophantine approximations with lacunary sequences.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 19:20:33 GMT"
},
{
"version": "v2",
"created": "Wed, 15 Aug 2007 20:51:23 GMT"
}
] | 2007-08-16T00:00:00 | [
[
"Moshchevitin",
"Nikolai G.",
""
]
] |
0708.2088 | Vladislav Kataev | A. Moller, T. Taetz, N. Hollmann, J. A. Mydosh, V. Kataev, M. Yehia,
E. Vavilova and B. Buchner | Insulator to semiconductor transition and magnetic properties of the
one-dimensional S = 1/2 system In_2VO_5 | submitted to Phys. Rev. B | null | 10.1103/PhysRevB.76.134411 | null | cond-mat.str-el cond-mat.mtrl-sci | null | We report structural, magnetization, electrical resistivity and nuclear- and
electron spin resonance data of the complex transition metal oxide In_2VO_5 in
which structurally well-defined V-O chains are realized. An itinerant character
of the vanadium d-electrons and ferromagnetic correlations, revealed at high
temperatures, are contrasted with the insulating behavior and predominantly
antiferromagnetic exchange between the localized V^{4+} S = 1/2-magnetic
moments which develop below a certain characteristic temperature T* ~ 120 K.
Eventually the compound exhibits short-range magnetic order at $T_SRO ~ 20 K.
We attribute this crossover occurring around T* to the unusual anisotropic
thermal contraction of the lattice which changes significantly the overlap
integrals and the character of magnetic intra- and interchain interactions.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 19:08:11 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Moller",
"A.",
""
],
[
"Taetz",
"T.",
""
],
[
"Hollmann",
"N.",
""
],
[
"Mydosh",
"J. A.",
""
],
[
"Kataev",
"V.",
""
],
[
"Yehia",
"M.",
""
],
[
"Vavilova",
"E.",
""
],
[
"Buchner",
"B.",
""
]
] |
0708.2089 | Justin Vandenbroucke | S. B\"oser, C. Bohm, F. Descamps, J. Fischer, A. Hallgren, R. Heller,
S. Hundertmark, K. Krieger, R. Nahnhauer, M. Pohl, P. B. Price, K.-H.
Sulanke, D. Tosi and J. Vandenbroucke | Feasibility of acoustic neutrino detection in ice: First results from
the South Pole Acoustic Test Setup (SPATS) | To appear in the Proceedings of the International Cosmic Ray
Conference, 2007 | null | null | null | astro-ph | null | Astrophysical neutrinos in the EeV range (particularly those generated by the
interaction of cosmic rays with the cosmic microwave background) promise to be
a valuable tool to study astrophysics and particle physics at the highest
energies. Much could be learned from temporal, spectral, and angular
distributions of ~100 events, which could be collected by a detector with ~100
km^3 effective volume in a few years. Scaling the optical Cherenkov technique
to this scale is prohibitive. However, using the thick ice sheet available at
the South Pole, the radio and acoustic techniques promise to provide sufficient
sensitivity with sparse instrumentation. The best strategy may be a hybrid
approach combining all three techniques. A new array of acoustic transmitters
and sensors, the South Pole Acoustic Test Setup, was installed in three IceCube
holes in January 2007. The purpose of SPATS is to measure the attenuation
length, background noise, and sound speed for 10-100 kHz acoustic waves.
Favorable results would pave the way for a large hybrid array. SPATS is the
first array to study the possibility of acoustic neutrino detection in ice, the
medium expected to be best for the purpose. First results from SPATS are
presented.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 19:10:41 GMT"
}
] | 2007-08-16T00:00:00 | [
[
"Böser",
"S.",
""
],
[
"Bohm",
"C.",
""
],
[
"Descamps",
"F.",
""
],
[
"Fischer",
"J.",
""
],
[
"Hallgren",
"A.",
""
],
[
"Heller",
"R.",
""
],
[
"Hundertmark",
"S.",
""
],
[
"Krieger",
"K.",
""
],
[
"Nahnhauer",
"R.",
""
],
[
"Pohl",
"M.",
""
],
[
"Price",
"P. B.",
""
],
[
"Sulanke",
"K. -H.",
""
],
[
"Tosi",
"D.",
""
],
[
"Vandenbroucke",
"J.",
""
]
] |
0708.2090 | Cesar Hidalgo | C. A. Hidalgo, B. Klinger, A.-L. Barabasi, R. Hausmann | The Product Space Conditions the Development of Nations | This version is slightly different from the one published in Science | Science 317, 482 (2007) | 10.1126/science.1144581 | null | q-fin.GN physics.data-an | null | Economies grow by upgrading the type of products they produce and export. The
technology, capital, institutions and skills needed to make such new products
are more easily adapted from some products than others. We study the network of
relatedness between products, or product space, finding that most upscale
products are located in a densely connected core while lower income products
occupy a less connected periphery. We show that countries tend to move to goods
close to those they are currently specialized in, allowing nations located in
more connected parts of the product space to upgrade their exports basket more
quickly. Most countries can reach the core only if they jump over empirically
infrequent distances in the product space. This may help explain why poor
countries have trouble developing more competitive exports, failing to converge
to the income levels of rich countries.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 19:20:01 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Hidalgo",
"C. A.",
""
],
[
"Klinger",
"B.",
""
],
[
"Barabasi",
"A. -L.",
""
],
[
"Hausmann",
"R.",
""
]
] |
0708.2091 | Mircea Trif | Mircea Trif, Vitaly N. Golovach and Daniel Loss | Spin dynamics in InAs-nanowire quantum-dots coupled to a transmission
line | null | null | 10.1103/PhysRevB.77.045434 | null | cond-mat.mes-hall | null | We study theoretically electron spins in nanowire quantum dots placed inside
a transmission line resonator. Because of the spin-orbit interaction, the spins
couple to the electric component of the resonator electromagnetic field and
enable coherent manipulation, storage, and read-out of quantum information in
an all-electrical fashion. Coupling between distant quantum-dot spins, in one
and the same or different nanowires, can be efficiently performed via the
resonator mode either in real time or through virtual processes. For the latter
case we derive an effective spin-entangling interaction and suggest means to
turn it on and off. We consider both transverse and longitudinal types of
nanowire quantum-dots and compare their manipulation timescales against the
spin relaxation times. For this, we evaluate the rates for spin relaxation
induced by the nanowire vibrations (phonons) and show that, as a result of
phonon confinement in the nanowire, this rate is a strongly varying function of
the spin operation frequency and thus can be drastically reduced compared to
lateral quantum dots in GaAs. Our scheme is a step forward to the formation of
hybrid structures where qubits of different nature can be integrated in a
single device.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 19:39:26 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Trif",
"Mircea",
""
],
[
"Golovach",
"Vitaly N.",
""
],
[
"Loss",
"Daniel",
""
]
] |
0708.2092 | Nitin Samarth | M. Zhu, M. J. Wilson, B. L. Sheu, P. Mitra, P. Schiffer and N. Samarth | Spin Valve Effect in Self-exchange Biased Ferromagnetic
Metal/Semiconductor Bilayers | null | Appl. Phys. Lett. 91, art. no. 192503 (2007) | 10.1063/1.2806966 | null | cond-mat.mtrl-sci | null | We report magnetization and magetoresistance measurements in hybrid
ferromagnetic metal/semiconductor heterostructures comprised of MnAs/(Ga,Mn)As
bilayers. Our measurements show that the (metallic) MnAs and (semiconducting)
(Ga,Mn)As layers are exchange coupled, re- sulting in an exchange biasing of
the magnetically softer (Ga,Mn)As layer that weakens with layer thickness.
Magnetoresistance measurements in the current-perpendicular-to-the-plane
geometry show a spin valve effect in these self-exchange biased bilayers.
Similar measurements in MnAs/p- GaAs/(Ga,Mn)As trilayers show that the exchange
coupling diminishes with spatial separation between the layers.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 19:40:04 GMT"
}
] | 2010-07-14T00:00:00 | [
[
"Zhu",
"M.",
""
],
[
"Wilson",
"M. J.",
""
],
[
"Sheu",
"B. L.",
""
],
[
"Mitra",
"P.",
""
],
[
"Schiffer",
"P.",
""
],
[
"Samarth",
"N.",
""
]
] |
0708.2093 | Gusakov Michael | E. M. Kantor, M. E. Gusakov (Ioffe Institute) | The neutrino emission due to plasmon decay and neutrino luminosity of
white dwarfs | 19 pages, 3 figures, accepted for publication in MNRAS | Mon.Not.Roy.Astron.Soc. 381 (2007) 1702-1710 | 10.1111/j.1365-2966.2007.12342.x | null | astro-ph | null | One of the effective mechanisms of neutrino energy losses in red giants,
presupernovae and in the cores of white dwarfs is the emission of
neutrino-antineutrino pairs in the process of plasmon decay. In this paper, we
numerically calculate the emissivity due to plasmon decay in a wide range of
temperatures (10^7-10^11) K and densities (200-10^14) g cm^-3. Numerical
results are approximated by convenient analytical expressions. We also
calculate and approximate by analytical expressions the neutrino luminosity of
white dwarfs due to plasmon decay, as a function of their mass and internal
temperature. This neutrino luminosity depends on the chemical composition of
white dwarfs only through the parameter mu_e (the net number of baryons per
electron) and is the dominant neutrino luminosity in all white dwarfs at the
neutrino cooling stage.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 19:40:10 GMT"
}
] | 2008-11-20T00:00:00 | [
[
"Kantor",
"E. M.",
"",
"Ioffe Institute"
],
[
"Gusakov",
"M. E.",
"",
"Ioffe Institute"
]
] |
0708.2094 | Brendan Casey | D0 Collaboration, V. Abazov, et al | Search for flavor-changing-neutral-current D meson decays | Submitted to Phys. Rev. Lett | Phys.Rev.Lett.100:101801,2008 | 10.1103/PhysRevLett.100.101801 | Fermilab-Pub-07/423-E | hep-ex | null | We study the flavor-changing-neutral-current process c to u mu+ mu- using 1.3
fb^-1 of p p bar collisions at sqrt(s) = 1.96 TeV recorded by the D0 detector
operating at the Fermilab Tevatron Collider. We see clear indications of the
Ds+ and D+ to phi pi+ to mu+ mu- pi+ final states with significance greater
than four standard deviations above background for the D+ state. We search for
the continuum decay of D+ to pi+mu+mu- in the dimuon invariant mass spectrum
away from the phi resonance. We see no evidence of signal above background and
set a limit of B(D+ to pi+mu+mu-) < 3.9 x 10^-6 at the 90% C.L. This limit
places the most stringent constraint on new phenomena in the c to u mu+ mu-
transition.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 19:42:55 GMT"
}
] | 2011-01-28T00:00:00 | [
[
"D0 Collaboration",
"",
""
],
[
"Abazov",
"V.",
""
]
] |
0708.2095 | A Bratkovsky | Evgenia Kim, Wei Wu, Ekaterina Ponizovskaya, Zhaoning Yu, Alexander M.
Bratkovsky, Shih-Yuang Wang, R. Stanley Williams and Y. Ron Shen | Modulation of Negative Index Metamaterials in the Near-IR Range | 11 figures, 4 figures | null | 10.1063/1.2801701 | null | cond-mat.mtrl-sci | null | Optical modulation of the effective refractive properties of a "fishnet"
metamaterial with a Ag/Si/Ag heterostructure is demonstrated in the near-IR
range and the associated fast dynamics of negative refractive index is studied
by pump-probe method. Photo excitation of the amorphous Si layer at visible
wavelength and corresponding modification of its optical parameters is found to
be responsible for the observed modulation of negative refractive index in
near-IR.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 20:04:53 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kim",
"Evgenia",
""
],
[
"Wu",
"Wei",
""
],
[
"Ponizovskaya",
"Ekaterina",
""
],
[
"Yu",
"Zhaoning",
""
],
[
"Bratkovsky",
"Alexander M.",
""
],
[
"Wang",
"Shih-Yuang",
""
],
[
"Williams",
"R. Stanley",
""
],
[
"Shen",
"Y. Ron",
""
]
] |
0708.2096 | Christino Tamon | William Adamczak, Kevin Andrew, Leon Bergen, Dillon Ethier, Peter
Hernberg, Jennifer Lin, Christino Tamon | Non-uniform mixing of quantum walk on cycles | 12 pages, 1 figure | International Journal of Quantum Information 5(6):781-793, 2007 | null | null | quant-ph | null | A classical lazy random walk on cycles is known to mix to the uniform
distribution. In contrast, we show that a continuous-time quantum walk on
cycles exhibit strong non-uniform mixing properties. Our results include the
following:
- The instantaneous distribution of a quantum walk on most even-length cycles
is never uniform. - The average distribution of a quantum walk on any Abelian
circulant graph is never uniform. As a corollary, the average distribution of a
quantum walk on any standard circulant graph, such as the cycles, complete
graphs, and even hypercubes, is never uniform.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 20:12:04 GMT"
}
] | 2011-08-02T00:00:00 | [
[
"Adamczak",
"William",
""
],
[
"Andrew",
"Kevin",
""
],
[
"Bergen",
"Leon",
""
],
[
"Ethier",
"Dillon",
""
],
[
"Hernberg",
"Peter",
""
],
[
"Lin",
"Jennifer",
""
],
[
"Tamon",
"Christino",
""
]
] |
0708.2097 | Eli Ben-Haim | The BABAR Collaboration: B. Aubert, et al | Time-dependent Dalitz Plot Analysis of B0 --> Ks pi+ pi- | 29 pages, 19 postscript figures, submitted to Lepton-Photon 2007 | null | null | BABAR-CONF-2007/07/010, SLAC-PUB-12729 | hep-ex | null | We perform a time-dependent Dalitz plot analysis of $B^0 \to
K^0_{\scriptscriptstyle S}\pi^+\pi^-$ in order to extract the ${CP}$ violation
parameters of $f_0(980) K^0_{\scriptscriptstyle S}$ and $\rho^0(770)
K^0_{\scriptscriptstyle S}$ and direct ${CP}$-asymmetries of $K^{*+}(892)
\pi^-$. The results are obtained from a data sample of $(383\pm3)\times10^{6}$
$B \bar{B}$ decays, collected with the BaBar detector at the PEP2
asymmetric--energy $B$ factory at SLAC. The measured values of $2\beta_{\rm
eff}$ in $B^0$ decays to $f_0(980)K^0_{\scriptscriptstyle S}$ and $\rho^0(770)
K^0_{\scriptscriptstyle S}$ are $(89^{+22}_{-20} \pm 5 \pm 8)^\circ$ and $(37
^{+19}_{-17} \pm 5 \pm 6)^\circ$, respectively, where the first quoted
uncertainty is statistical, the second is systematic and the third is Dalitz
plot signal model uncertainty. We measure the significance of $2\beta_{\rm
eff}(f_0(980)K^0_{\scriptscriptstyle S})\neq 0$ to be $4.3 \sigma$. In decays
to $K^*(892) \pi$ we find $A_{{CP}} = -0.18 \pm 0.10 \pm 0.03 \pm 0.03$. The
measured phase difference between the decay amplitudes of $B^0 \to K^{*+}(892)
\pi^-$ and $\bar{B}^0 \to K^{*-}(892) \pi^+$ is $(-164 \pm 24 \pm 12 \pm
15)^\circ$. All results are preliminary.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 21:51:18 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"The BABAR Collaboration",
"",
""
],
[
"Aubert",
"B.",
""
]
] |
0708.2098 | Sourav Sur | Saurya Das (Lethbridge U.), S. Shankaranarayanan (Potsdam, Max Planck
Inst.), Sourav Sur (Lethbridge U.) | Where are the degrees of freedom responsible for black hole entropy? | 6 pages, 4 figures, Invited talk at Theory Canada III, Edmonton,
Alberta, Canada, June 16, 2007 | Can.J.Phys.86:653-658,2008 | 10.1139/P07-183 | null | gr-qc hep-th | null | Considering the entanglement between quantum field degrees of freedom inside
and outside the horizon as a plausible source of black hole entropy, we address
the question: {\it where are the degrees of freedom that give rise to this
entropy located?} When the field is in ground state, the black hole area law is
obeyed and the degrees of freedom near the horizon contribute most to the
entropy. However, for excited state, or a superposition of ground state and
excited state, power-law corrections to the area law are obtained, and more
significant contributions from the degrees of freedom far from the horizon are
shown.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 20:17:08 GMT"
}
] | 2008-11-07T00:00:00 | [
[
"Das",
"Saurya",
"",
"Lethbridge U."
],
[
"Shankaranarayanan",
"S.",
"",
"Potsdam, Max Planck\n Inst."
],
[
"Sur",
"Sourav",
"",
"Lethbridge U."
]
] |
0708.2099 | Axel Arnold | A. Arnold, B. Bozorgui, D. Frenkel, B.-Y. Ha, S. Jun | Unexpected relaxation dynamics of a self-avoiding polymer in cylindrical
confinement | 10 pages, 11 figures | null | 10.1063/1.2799513 | null | cond-mat.soft cond-mat.stat-mech | null | We report extensive simulations of the relaxation dynamics of a self-avoiding
polymer confined inside a cylindrical pore. In particular, we concentrate on
examining how confinement influences the scaling behavior of the global
relaxation time of the chain, t, with the chain length N and pore diameter D.
An earlier scaling analysis based on the de Gennes blob picture led to t ~
N^2D^(1/3). Our numerical effort that combines molecular dynamics and Monte
Carlo simulations, however, consistently produces different t-results for N up
to 2000. We argue that the previous scaling prediction is only asymptotically
valid in the limit N >> D^(5/3) >> 1, which is currently inaccessible to
computer simulations and, more interestingly, is also difficult to reach in
experiments. Our results are thus relevant for the interpretation of recent
experiments with DNA in nano- and micro-channels.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 20:27:06 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Arnold",
"A.",
""
],
[
"Bozorgui",
"B.",
""
],
[
"Frenkel",
"D.",
""
],
[
"Ha",
"B. -Y.",
""
],
[
"Jun",
"S.",
""
]
] |
0708.2100 | Shay Zucker | Shay Zucker (1), Tsevi Mazeh (1) and Tal Alexander (2) ((1) Tel Aviv
University, Tel Aviv, Israel, (2) Weizmann Institute of Science, Rehovot,
Israel) | Beaming Binaries - a New Observational Category of Photometric Binary
Stars | 15 pages, 4 figures, accpeted for publication in The Astrophysical
Journal | Astrophys. J., 670: 1326-1330, 2007 | 10.1086/521389 | null | astro-ph | null | The new photometric space-borne survey missions CoRoT and Kepler will be able
to detect minute flux variations in binary stars due to relativistic beaming
caused by the line-of-sight motion of their components. In all but very short
period binaries (P>10d), these variations will dominate over the ellipsoidal
and reflection periodic variability. Thus, CoRoT and Kepler will discover a new
observational class: photometric beaming binary stars. We examine this new
category and the information that the photometric variations can provide. The
variations that result from the observatory heliocentric velocity can be used
to extract some spectral information even for single stars.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 20:41:36 GMT"
}
] | 2016-01-07T00:00:00 | [
[
"Zucker",
"Shay",
""
],
[
"Mazeh",
"Tsevi",
""
],
[
"Alexander",
"Tal",
""
]
] |
0708.2101 | Julien Randon-Furling | Julien Randon-Furling (LPTMS), Satya N. Majumdar (LPTMS) | Distribution of the time at which the deviation of a Brownian motion is
maximum before its first-passage time | 13 pages, 5 figures. Published in Journal of Statistical Mechanics:
Theory and Experiment (J. Stat. Mech. (2007) P10008,
doi:10.1088/1742-5468/2007/10/P10008) | Journal of Statistical Mechanics: Theory and Experiment (2007)
P10008 | 10.1088/1742-5468/2007/10/P10008 | null | cond-mat.stat-mech math.PR | null | We calculate analytically the probability density $P(t_m)$ of the time $t_m$
at which a continuous-time Brownian motion (with and without drift) attains its
maximum before passing through the origin for the first time. We also compute
the joint probability density $P(M,t_m)$ of the maximum $M$ and $t_m$. In the
driftless case, we find that $P(t_m)$ has power-law tails: $P(t_m)\sim
t_m^{-3/2}$ for large $t_m$ and $P(t_m)\sim t_m^{-1/2}$ for small $t_m$. In
presence of a drift towards the origin, $P(t_m)$ decays exponentially for large
$t_m$. The results from numerical simulations are in excellent agreement with
our analytical predictions.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 20:41:26 GMT"
},
{
"version": "v2",
"created": "Wed, 19 Sep 2007 16:51:35 GMT"
},
{
"version": "v3",
"created": "Tue, 9 Oct 2007 13:26:24 GMT"
},
{
"version": "v4",
"created": "Mon, 25 Feb 2008 15:44:58 GMT"
}
] | 2008-02-25T00:00:00 | [
[
"Randon-Furling",
"Julien",
"",
"LPTMS"
],
[
"Majumdar",
"Satya N.",
"",
"LPTMS"
]
] |
0708.2102 | Mauricio Sepulveda | Julie Levandosky, Mauricio Sepulveda (DIM), Octavio Vera | Gain of Regularity for the KP-I Equation | null | Journal of Differential Equations 245, 3 (2008) 762-808 | 10.1016/j.jde.2008.01.016 | null | math.AP | null | In this paper we study the smoothness properties of solutions to the KP-I
equation. We show that the equation's dispersive nature leads to a gain in
regularity for the solution. In particular, if the initial data $\phi$
possesses certain regularity and sufficient decay as $x \to \infty$, then the
solution $u(t)$ will be smoother than $\phi$ for $0 < t \leq T$ where $T$ is
the existence time of the solution.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 20:42:13 GMT"
}
] | 2023-01-24T00:00:00 | [
[
"Levandosky",
"Julie",
"",
"DIM"
],
[
"Sepulveda",
"Mauricio",
"",
"DIM"
],
[
"Vera",
"Octavio",
""
]
] |
0708.2103 | Janet P. Simpson | Janet P. Simpson (1 and 2), Sean W. J. Colgan (1), Angela S. Cotera
(2), Edwin F. Erickson (1), David J. Hollenbach (3), Michael J. Kaufman (4),
Robert H. Rubin (1 and 5) ((1) NASA Ames Research Center, (2) SETI Institute,
(3) NASA Ames Research Center, (4) Dept of Physics, San Jose State
University, (5) Orion Enterprises) | Spitzer IRS Observations of the Galactic Center: Shocked Gas in the
Radio Arc Bubble | 51 pages, 17 figures To be published in the Astrophysical Journal | null | 10.1086/522295 | null | astro-ph | null | We present Spitzer IRS spectra (R ~600, 10 - 38 micron) of 38 positions in
the Galactic Center (GC), all at the same Galactic longitude and spanning
plus/minus 0.3 degrees in latitude. Our positions include the Arches Cluster,
the Arched Filaments, regions near the Quintuplet Cluster, the ``Bubble'' lying
along the same line-of-sight as the molecular cloud G0.11-0.11, and the diffuse
interstellar gas along the line-of-sight at higher Galactic latitudes. From
measurements of the [O IV], [Ne II], [Ne III], [Si II], [S III], [S IV], [Fe
II], [Fe III], and H_2 S(0), S(1), and S(2) lines we determine the gas
excitation and ionic abundance ratios. The Ne/H and S/H abundance ratios are ~
1.6 times that of the Orion Nebula. The main source of excitation is
photoionization, with the Arches Cluster ionizing the Arched Filaments and the
Quintuplet Cluster ionizing the gas nearby and at lower Galactic latitudes
including the far side of the Bubble. In addition, strong shocks ionize gas to
O^{+3} and destroy dust grains, releasing iron into the gas phase (Fe/H ~ 1.3
times 10^{-6} in the Arched Filaments and Fe/H ~ 8.8 times 10^{-6} in the
Bubble). The shock effects are particularly noticeable in the center of the
Bubble, but O$^{+3}$ is present in all positions. We suggest that the shocks
are due to the winds from the Quintuplet Cluster Wolf-Rayet stars. On the other
hand, the H_2 line ratios can be explained with multi-component models of warm
molecular gas in photodissociation regions without the need for H_2 production
in shocks.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 20:44:33 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Simpson",
"Janet P.",
"",
"1 and 2"
],
[
"Colgan",
"Sean W. J.",
"",
"1 and 5"
],
[
"Cotera",
"Angela S.",
"",
"1 and 5"
],
[
"Erickson",
"Edwin F.",
"",
"1 and 5"
],
[
"Hollenbach",
"David J.",
"",
"1 and 5"
],
[
"Kaufman",
"Michael J.",
"",
"1 and 5"
],
[
"Rubin",
"Robert H.",
"",
"1 and 5"
]
] |
0708.2104 | Mark Cornell | John Kormendy | Internal Secular Evolution in Disk Galaxies: The Growth of Pseudobulges | 6 pages, 7 Postscript figures; requires iaus.cls; to appear in
Formation and Evolution of Galaxy Bulges, Proceedings IAU Symposium No. 245,
2007, M. Bureau et al. eds., in press | null | 10.1017/S1743921308017407 | null | astro-ph | null | Observational and theoretical evidence that internal, slow ("secular")
evolution reshapes galaxy disks is reviewed in Kormendy & Kennicutt (2004,
ARAA, 42, 603). This update has three aims. First, I emphasize that this
evolution is very general -- it is as fundamental to the evolution of galaxy
disks as (e.g.) core collapse is to globular clusters, as the production of hot
Jupiters is to the evolution of protoplanetary disks, and as evolution to red
giants containing proto-white-dwarfs is to stellar evolution. One consequence
for disk galaxies is the buildup of dense central components that get mistaken
for classical (i.e., merger-built) bulges but that were grown out of disk stars
and gas. We call these pseudobulges. Second, I review new results on
pseudobulge star formation and structure and on the distinction between boxy
and disky pseudobulges. Finally, I highlight how these results make a galaxy
formation problem more acute. How can hierarchical clustering produce so many
pure disk galaxies with no evidence for merger-built bulges?
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 20:56:18 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kormendy",
"John",
""
]
] |
0708.2105 | Nicholas Pippenger | Krzysztof Majewski and Nicholas Pippenger | Attribute Estimation and Testing Quasi-Symmetry | null | null | null | null | cs.CC | null | A Boolean function is symmetric if it is invariant under all permutations of
its arguments; it is quasi-symmetric if it is symmetric with respect to the
arguments on which it actually depends. We present a test that accepts every
quasi-symmetric function and, except with an error probability at most delta>0,
rejects every function that differs from every quasi-symmetric function on at
least a fraction epsilon>0 of the inputs. For a function of n arguments, the
test probes the function at O((n/epsilon)\log(n/delta)) inputs. Our
quasi-symmetry test acquires information concerning the arguments on which the
function actually depends. To do this, it employs a generalization of the
property testing paradigm that we call attribute estimation. Like property
testing, attribute estimation uses random sampling to obtain results that have
only "one-sided'' errors and that are close to accurate with high probability.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 20:56:22 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"Majewski",
"Krzysztof",
""
],
[
"Pippenger",
"Nicholas",
""
]
] |
0708.2106 | Robert Chapman | Robert Chapman (1), Nial R. Tanvir (2), Robert S. Priddey (1) and
Andrew J. Levan (3) ((1) University of Hertfordshire, (2) University of
Leicester, (3) University of Warwick) | How common are long Gamma-Ray Bursts in the Local Universe? | 6 pages, 4 figures. Accepted for publication in MNRAS | null | 10.1111/j.1745-3933.2007.00381.x | null | astro-ph | null | The two closest Gamma-Ray Bursts so far detected (GRBs 980425 & 060218) were
both under-luminous, spectrally soft, long duration bursts with smooth,
single-peaked light curves. Only of the order of 100 GRBs have measured
redshifts, and there are, for example, 2704 GRBs in the BATSE catalogue alone.
It is therefore plausible that other nearby GRBs have been observed but not
identified as relatively nearby. Here we search for statistical correlations
between BATSE long duration GRBs and galaxy samples with recession velocities v
<= 11,000 km/s (z = 0.0367, ~ 155 Mpc) selected from two catalogues of nearby
galaxies. We also examine the correlations using burst sub-samples restricted
to those with properties similar to the two known nearby bursts. Our results
show correlation of the entire long GRB sample to remain consistent with zero
out to the highest radii considered whereas a sub-sample selected to be low
fluence, spectrally soft, with smooth single-peaked light curves (177 bursts)
demonstrates increased correlation with galaxies within ~ 155 Mpc. The measured
correlation (28% +/- 16% of the sample) suggests that BATSE observed between 2
and 9 long duration GRBs per year similar to, and from within similar distances
to GRBs 980425 and 060218. This implies an observed local rate density (to
BATSE limits) of 700 +/- 360 Gpc^{-3}yr^{-1} within 155 Mpc.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 14:45:39 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Chapman",
"Robert",
""
],
[
"Tanvir",
"Nial R.",
""
],
[
"Priddey",
"Robert S.",
""
],
[
"Levan",
"Andrew J.",
""
]
] |
0708.2107 | Pinaki Sengupta | Pinaki Sengupta and Stephan Haas | Quantum glass phases in the disordered Bose-Hubbard model | null | Phys. Rev. Lett. 99, 050403 (2007) | 10.1103/PhysRevLett.99.050403 | null | cond-mat.dis-nn | null | The phase diagram of the Bose-Hubbard model in the presence of off-diagonal
disorder is determined using Quantum Monte Carlo simulations. A sequence of
quantum glass phases intervene at the interface between the Mott insulating and
the Superfluid phases of the clean system. In addition to the standard Bose
glass phase, the coexistence of gapless and gapped regions close to the Mott
insulating phase leads to a novel Mott glass regime which is incompressible yet
gapless. Numerical evidence for the properties of these phases is given in
terms of global (compressibility, superfluid stiffness) and local
(compressibility, momentum distribution) observables.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 21:15:54 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sengupta",
"Pinaki",
""
],
[
"Haas",
"Stephan",
""
]
] |
0708.2108 | Akhlesh Lakhtakia | John A. Polo Jr and Akhlesh Lakhtakia | Morphological effects on surface plasmon polaritons at the planar
interface of a metal and a columnar thin film The Planar Interface Of A Metal
And A Columnar Thin Film | null | Asian Journal of Physics, Vol. 17, pp. 185-191 (2008) | null | null | physics.optics | null | Surface plasmon polaritons (SPPs) at the interface of a columnar thin film
(CTF) and metal exist over a range of propagation directions relative to the
morphology of the CTF which depends on the tilt of the columns in the CTF. The
phase speed of the SPP wave varies mainly as a function of the tilt of the CTF
columns. Both the confinement of the SPP wave to the interface and the decay of
the SPP wave along the direction of propagation depend strongly on the
direction of propagation relative to the morphologically significant plane of
the CTF. The greater the columnar tilt in relation to the interface, the
shorter is the range of propagation. Because of its porosity and the ability to
engineer this biaxial dielectric material, the CTF-metal interface may be more
attractive than traditional methods of producing SPPs.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 21:20:39 GMT"
},
{
"version": "v2",
"created": "Sat, 18 Aug 2007 04:17:16 GMT"
}
] | 2019-06-07T00:00:00 | [
[
"Polo",
"John A.",
"Jr"
],
[
"Lakhtakia",
"Akhlesh",
""
]
] |
0708.2109 | Roland Roeder | Omar Antolin-Camarena, Gregory R. Maloney, and Roland K. W. Roeder | Computing arithmetic invariants for hyperbolic reflection groups | 34 pages, nice color figures illustrating commensurable polyhedral
groups. Submitted to book commemorating J. H. Hubbard's 60th birthday.
Includes reference to computer scripts used for calculations | null | null | null | math.GT math.DG | null | We describe a collection of computer scripts written in PARI/GP to compute,
for reflection groups determined by finite-volume polyhedra in $\mathbb{H}^3$,
the commensurability invariants known as the invariant trace field and
invariant quaternion algebra. Our scripts also allow one to determine
arithmeticity of such groups and the isomorphism class of the invariant
quaternion algebra by analyzing its ramification.
We present many computed examples of these invariants. This is enough to show
that most of the groups that we consider are pairwise incommensurable. For
pairs of groups with identical invariants, not all is lost: when both groups
are arithmetic, having identical invariants guarantees commensurability. We
discover many ``unexpected'' commensurable pairs this way. We also present a
non-arithmetic pair with identical invariants for which we cannot determine
commensurability.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 21:56:58 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"Antolin-Camarena",
"Omar",
""
],
[
"Maloney",
"Gregory R.",
""
],
[
"Roeder",
"Roland K. W.",
""
]
] |
0708.2110 | Byung Kyu Park | B. K. Park, A. O. Sushkov, D. Budker | Precision polarimetry with real-time mitigation of optical-window
birefringence | null | Rev. Sci. Instrum. 79, 013108 (2008) | 10.1063/1.2835902 | null | physics.optics | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Optical-window birefringence is frequently a major obstacle in experiments
measuring changes in the polarization state of light traversing a sample under
investigation. It can contribute a signal indistinguishable from that due to
the sample and complicate the analysis. Here, we explore a method to measure
and compensate for the birefringence of an optical window using the reflection
from the last optical surface before the sample. We demonstrate that this
arrangement can cancel out false signals due to the optical-window
birefringence-induced ellipticity drift to about 1%, for the values of total
ellipticity less than 0.25 rad.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 01:16:52 GMT"
},
{
"version": "v2",
"created": "Tue, 1 Jan 2008 19:41:36 GMT"
},
{
"version": "v3",
"created": "Tue, 5 Feb 2008 10:14:21 GMT"
},
{
"version": "v4",
"created": "Mon, 2 Aug 2010 04:04:00 GMT"
}
] | 2010-08-03T00:00:00 | [
[
"Park",
"B. K.",
""
],
[
"Sushkov",
"A. O.",
""
],
[
"Budker",
"D.",
""
]
] |
0708.2111 | Bryan W. Miller | Bryan W. Miller (Gemini Observatory) | 3D Spectroscopy and the Virtual Observatory | 8 pages, 4 figures, invited review to appear in Astronomical
Spectroscopy and the Virtual Observatory | null | null | null | astro-ph | null | Integral field, or 3D, spectroscopy is the technique of obtaining spectral
information over a two-dimensional, hopefully contiguous, field of view. While
there is some form of astronomical 3D spectroscopy at all wavelengths, there
has been a rapid increase in interest in optical and near-infrared 3D
spectroscopy. This has resulted in the deployment of a large variety of
integral-field spectrographs on most of the large optical/infrared telescopes.
The amount of IFU data available in observatory archives is large and growing
rapidly. The complications of treating IFU data as both imaging and
spectroscopy make it a special challenge for the virtual observatory. This
article describes the various techniques of optical and near-infrared
spectroscopy and some of the general needs and issues related to the handling
of 3D data by the virtual observatory.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 22:06:20 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"Miller",
"Bryan W.",
"",
"Gemini Observatory"
]
] |
0708.2112 | Francesca Sammarruca | F. Sammarruca | In-Medium Hadronic Interactions and the Nuclear Equation of State | Talk given at the International Symposium on Exotic States of Nuclear
Matter, Catania (Italy), June 11-15, 2007. 9 pages, 5 figures | null | 10.1142/9789812797049_0002 | null | nucl-th | null | Microscopic studies of nuclear matter under diverse conditions of density and
asymmetry are of great contemporary interest. Concerning terrestrial
applications, they relate to future experimental facilities that will make it
possible to study systems with extreme neutron-to-proton ratio. In this talk, I
will review recent efforts of my group aimed at exploring nuclear interactions
in the medium through the nuclear equation of state (EoS). The approach we take
is microscopic and relativistic, with the predicted EoS properties derived from
realistic nucleon-nucleon potentials. I will also discuss work in progress.
Most recently, we completed a DBHF calculation of the $\Lambda$ hyperon binding
energy in nuclear matter.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 22:17:31 GMT"
}
] | 2017-08-23T00:00:00 | [
[
"Sammarruca",
"F.",
""
]
] |
0708.2113 | Federico Spedalieri | Federico M. Spedalieri | Detecting separable states via semidefinite programs | 8 pages, accepted for publication in Physical Review A | Physical Review A 76, 032318 (2007) | 10.1103/PhysRevA.76.032318 | null | quant-ph | null | We introduce a new technique to detect separable states using semidefinite
programs. This approach provides a sufficient condition for separability of a
state that is based on the existence of a certain local linear map applied to a
known separable state. When a state is shown to be separable, a proof of this
fact is provided in the form of an explicit convex decomposition of the state
in terms of product states. All states in the interior of the set of separable
states can be detected in this way, except maybe for a set of measure zero.
Even though this technique is more suited for a numerical approach, a new
analytical criterion for separability can also be derived.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 22:22:14 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Spedalieri",
"Federico M.",
""
]
] |
0708.2114 | Francisco Santos | Pilar Sabariego and Francisco Santos | On the Number of Facets of Three-Dimensional Dirichlet Stereohedra IV:
Quarter Cubic Groups | 23 pages, 10 figures, 14 tables. Changes from v1: editing and
typographic correction | Contributions to Algebra and Geometry 52:2 (2011), 237-263 | 10.1007/s13366-011-0010-5 | null | math.CO math.MG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we finish the intensive study of three-dimensional Dirichlet
stereohedra started by the second author and D. Bochis, who showed that they
cannot have more than 80 facets, except perhaps for crystallographic space
groups in the cubic system.
Taking advantage of the recent, simpler classification of three-dimensional
crystallographic groups by Conway, Delgado-Friedrichs, Huson and Thurston, in a
previous paper we proved that Dirichlet stereohedra for any of the 27 "full"
cubic groups cannot have more than 25 facets. Here we study the remaining
"quarter" cubic groups. With a computer-assisted method, our main result is
that Dirichlet stereohedra for the 8 quarter groups, hence for all
three-dimensional crystallographic groups, cannot have more than 92 facets.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 22:30:38 GMT"
},
{
"version": "v2",
"created": "Fri, 16 Jul 2010 10:06:36 GMT"
}
] | 2011-09-20T00:00:00 | [
[
"Sabariego",
"Pilar",
""
],
[
"Santos",
"Francisco",
""
]
] |
0708.2115 | Patrick A. Lee | Patrick A. Lee | From high temperature supercondutivity to quantum spin liquid: progress
in strong correlation physics | Submitted as "Key Issue" essay for Report of Progress in Physics; v2:
References are added and typos corrected | null | 10.1088/0034-4885/71/1/012501 | null | cond-mat.str-el cond-mat.supr-con | null | This review gives a rather general discussion of high temperature
superconductors as an example of a strongly correlated material. The argument
is made that in view of the many examples of unconventional superconductors
discovered in the past twenty years, we should no longer be surprised that
superconductivity emerges as a highly competitive ground state in systems where
Coulomb repulsion plays a dominant role. The physics of the cuprates is
discussed, emphasizing the unusual pseudogap phase in the underdoped region. It
is argued that the resonating valence bond (RVB) picture, as formulated using
gauge theory with fermionic and bosonic matter fields, gives an adequate
physical understanding, even though many details are beyond the powers of
current calculational tools. The recent discovery of quantum oscillations in a
high magnetic field is discussed in this context. Meanwhile, the problem of the
quantum spin liquid (a spin system with antiferromagnetic coupling which
refuses to order even at zero temperature) is a somewhat simpler version of the
high $T_c$ problem where significant progress has been made recently. It is
understood that the existence of matter fields can lead to de-confinement of
the U(1) gauge theory in 2+1 dimensions, and novel new particles (called
fractionalized particles), such as fermionic spinons which carry spin ${1\over
2}$ and no charge, and gapless gauge bosons can emerge to create a new critical
state at low energies. We even have a couple of real materials where such a
scenario may be realized experimentally. The article ends with answers to
questions such as: what limits $T_c$ if pairing is driven by an electronic
energy scale? why is the high $T_c$ problem hard? why is there no consensus?
and why is the high $T_c$ problem important?
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 22:45:53 GMT"
},
{
"version": "v2",
"created": "Thu, 13 Sep 2007 18:38:15 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Lee",
"Patrick A.",
""
]
] |
0708.2116 | Xiaobing Feng Dr. | Xiaobing Feng and Haijun Wu | A posteriori error estimates for finite element approximations of the
Cahn-Hilliard equation and the Hele-Shaw flow | 29 pages and 7 figures | null | null | null | math.NA math.AP | null | This paper develops a posteriori error estimates of residual type for
conforming and mixed finite element approximations of the fourth order
Cahn-Hilliard equation $u_t+\De\bigl(\eps \De u-\eps^{-1} f(u)\bigr)=0$. It is
shown that the {\it a posteriori} error bounds depends on $\eps^{-1}$ only in
some low polynomial order, instead of exponential order. Using these a
posteriori error estimates, we construct an adaptive algorithm for computing
the solution of the Cahn-Hilliard equation and its sharp interface limit, the
Hele-Shaw flow. Numerical experiments are presented to show the robustness and
effectiveness of the new error estimators and the proposed adaptive algorithm.
| [
{
"version": "v1",
"created": "Wed, 15 Aug 2007 23:21:09 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"Feng",
"Xiaobing",
""
],
[
"Wu",
"Haijun",
""
]
] |
0708.2117 | James S. Schilling | T. Matsuoka, M. Debessai, J. J. Hamlin, A. K. Gangopadhyay and J. S.
Schilling | Pressure-induced Superconductivity in CaLi2 | bulk superconductivity in CaLi2 now confirmed | Phys. Rev. Lett. 100, 197003 (2008) | 10.1103/PhysRevLett.100.197003 | null | cond-mat.supr-con | null | A search for superconductivity has been carried out on the hexagonal
polymorph of Laves-phase CaLi2, a compound for which Feng, Ashcroft, and
Hoffmann predict highly anomalous behavior under pressure. No superconductivity
is observed above 1.10 K at ambient pressure. However, high-pressure ac
susceptibility and electrical resistivity studies to 81 GPa reveal bulk
superconductivity in CaLi2 at temperatures as high as 13 K. The normal-state
resistivity shows a dramatic increase with pressure.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 00:18:30 GMT"
},
{
"version": "v2",
"created": "Wed, 20 Feb 2008 23:11:03 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Matsuoka",
"T.",
""
],
[
"Debessai",
"M.",
""
],
[
"Hamlin",
"J. J.",
""
],
[
"Gangopadhyay",
"A. K.",
""
],
[
"Schilling",
"J. S.",
""
]
] |
0708.2118 | Re-Bing Wu | Rebing Wu, Raj Chakrabarti, Herschel Rabitz | Optimal Control Theory for Continuous Variable Quantum Gates | 39 pages, 11 figures | null | 10.1103/PhysRevA.77.052303 | null | quant-ph | null | We apply the methodology of optimal control theory to the problem of
implementing quantum gates in continuous variable systems with quadratic
Hamiltonians. We demonstrate that it is possible to define a fidelity measure
for continuous variable (CV) gate optimization that is devoid of traps, such
that the search for optimal control fields using local algorithms will not be
hindered. The optimal control of several quantum computing gates, as well as
that of algorithms composed of these primitives, is investigated using several
typical physical models and compared for discrete and continuous quantum
systems. Numerical simulations indicate that the optimization of generic CV
quantum gates is inherently more expensive than that of generic discrete
variable quantum gates, and that the exact-time controllability of CV systems
plays an important role in determining the maximum achievable gate fidelity.
The resulting optimal control fields typically display more complicated Fourier
spectra that suggest a richer variety of possible control mechanisms. Moreover,
the ability to control interactions between qunits is important for delimiting
the total control fluence. The comparative ability of current experimental
protocols to implement such time-dependent controls may help determine which
physical incarnations of CV quantum information processing will be the easiest
to implement with optimal fidelity.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 00:52:35 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Wu",
"Rebing",
""
],
[
"Chakrabarti",
"Raj",
""
],
[
"Rabitz",
"Herschel",
""
]
] |
0708.2119 | Re-Bing Wu | Rebing Wu, Alexander Pechen, Herschel Rabitz, Michael Hsieh, Benjamin
Tsou | Control Landscapes for Observable Preparation with Open Quantum Systems | null | J. Math. Phys. 49, 022108 (2008) | 10.1063/1.2883738 | null | quant-ph math-ph math.MP | null | A quantum control landscape is defined as the observable as a function(al) of
the system control variables. Such landscapes were introduced to provide a
basis to understand the increasing number of successful experiments controlling
quantum dynamics phenomena. This paper extends the concept to encompass the
broader context of the environment having an influence. For the case that the
open system dynamics are fully controllable, it is shown that the control
landscape for open systems can be lifted to the analysis of an equivalent
auxiliary landscape of a closed composite system that contains the
environmental interactions. This inherent connection can be analyzed to provide
relevant information about the topology of the original open system landscape.
Application to the optimization of an observable expectation value reveals the
same landscape simplicity observed in former studies on closed systems. In
particular, no false sub-optimal traps exist in the system control landscape
when seeking to optimize an observable, even in the presence of complex
environments. Moreover, a quantitative study of the control landscape of a
system interacting with a thermal environment shows that the enhanced
controllability attainable with open dynamics significantly broadens the range
of the achievable observable values over the control landscape.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 01:10:36 GMT"
}
] | 2009-05-04T00:00:00 | [
[
"Wu",
"Rebing",
""
],
[
"Pechen",
"Alexander",
""
],
[
"Rabitz",
"Herschel",
""
],
[
"Hsieh",
"Michael",
""
],
[
"Tsou",
"Benjamin",
""
]
] |
0708.2120 | Shigeru Kuroda | Shigeru Kuroda | Automorphisms of a polynomial ring which admit reductions of type I | Question 4.1 of the first version was answered | null | null | null | math.AC math.AG | null | Recently, Shestakov-Umirbaev solved Nagata's conjecture on an automorphism of
a polynomial ring. To solve the conjecture, they defined notions called
reductions of types I--IV for automorphisms of a polynomial ring. An
automorphism admitting a reduction of type I was first found by
Shestakov-Umirbaev. Using a computer, van den Essen--Makar-Limanov--Willems
gave a family of such automorphisms. In this paper, we present a new
construction of such automorphisms using locally nilpotent derivations. As a
consequence, we discover that there exists an automorphism admitting a
reduction of type I which satisfies some degree condition for each possible
value.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 01:23:06 GMT"
},
{
"version": "v2",
"created": "Mon, 10 Sep 2007 08:34:31 GMT"
}
] | 2007-09-10T00:00:00 | [
[
"Kuroda",
"Shigeru",
""
]
] |
0708.2121 | Ashok Palaniappan | Ashok Palaniappan | Detection of an ancient principle and an elegant solution to the protein
classification problem | 13p | null | null | null | q-bio.GN q-bio.BM q-bio.QM | null | This work is concerned with the development of a well-founded, theoretically
justified, and least complicated metric for the classification of proteins with
reference to enzymes. As the signature of an enzyme family, a catalytic domain
is easily fingerprinted. Given that the classification problem has so far
seemed intractable, a classification schema derived from the catalytic domain
would be satisfying. Here I show that there exists a natural ab initio if
nonobvious basis to theorize that the catalytic domain of an enzyme is uniquely
informative about its regulation. This annotates its function. Based on this
hypothesis, a method that correctly classifies potassium ion channels into
their respective subfamilies is described. To put the principle on firmer
ground, extra validation was sought and obtained through co-evolutionary
analyses. The co-evolutionary analyses reveal a departure from the notion that
potassium ion channel proteins are functionally modular. This finding is
discussed in light of the prevailing notion of domain. These studies establish
that significant co-evolution of the catalytic domain of a gene with its
conjoint domain is a specialized, necessary process following fusion and
swapping events in evolution. Instances of this discovery are likely to be
found pervasive in protein science.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 16:58:25 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"Palaniappan",
"Ashok",
""
]
] |
0708.2122 | Paul Sommers | Paul Sommers | Prospects for Charged Particle Astronomy | 28 pages, submitted to Astroparticle Physics | null | null | null | astro-ph | null | The likelihood of detecting individual discrete sources of cosmic rays
depends on the mean separation between sources. The analysis here derives the
minimum separation that makes it likely that the closest source is detectable.
For super-GZK energies, detection is signal limited and magnetic fields should
not matter. For sub-GZK energies, detection is background limited, and
intergalactic magnetic fields enter the analysis through one adjustable
parameter. Both super-GZK and sub-GZK results are presented for four different
types of sources: steady isotropic sources, steady jet sources, isotropic
bursts, and jet bursts.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 02:08:36 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"Sommers",
"Paul",
""
]
] |
0708.2123 | Wen-Yu Wen | Wen-Yu Wen | Multi-quark potential from AdS/QCD | 15 pages, 5 figures, REVTex4 | Int.J.Mod.Phys.A23:4533-4543,2008 | 10.1142/S0217751X08041475 | null | hep-th hep-ph | null | Heavy multi-quark potential in the SU(N) color group using hard-wall AdS/QCD
at both zero and finite temperature is studied. A Cornell-like potential is
obtained for baryons and other exotic configurations and compared with those in
the quenched lattice calculation in N=3 case. At the end we also discuss
possible improvements in the UV region of potential.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 06:12:40 GMT"
},
{
"version": "v2",
"created": "Tue, 28 Aug 2007 09:01:48 GMT"
},
{
"version": "v3",
"created": "Wed, 14 May 2008 03:57:41 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Wen",
"Wen-Yu",
""
]
] |
0708.2124 | Mike Steel Prof. | Mike Steel and Allen Rodrigo | Maximum Likelihood Supertrees | 13 pages, 0 figures | null | null | null | q-bio.PE q-bio.QM | null | We analyse a maximum-likelihood approach for combining phylogenetic trees
into a larger `supertree'. This is based on a simple exponential model of
phylogenetic error, which ensures that ML supertrees have a simple
combinatorial description (as a median tree, minimising a weighted sum of
distances to the input trees). We show that this approach to ML supertree
reconstruction is statistically consistent (it converges on the true species
supertree as more input trees are combined), in contrast to the widely-used MRP
method, which we show can be statistically inconsistent under the exponential
error model. We also show that this statistical consistency extends to an ML
approach for constructing species supertrees from gene trees. In this setting,
incomplete lineage sorting (due to coalescence rates of homologous genes being
lower than speciation rates) has been shown to lead to gene trees that are
frequently different from species trees, and this can confound efforts to
reconstruct the species phylogeny correctly.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 03:11:01 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"Steel",
"Mike",
""
],
[
"Rodrigo",
"Allen",
""
]
] |
0708.2125 | Radoslaw Bialczak | Radoslaw C. Bialczak, R. McDermott, M. Ansmann, M. Hofheinz, N. Katz,
Erik Lucero, Matthew Neeley, A. D. O'Connell, H. Wang, A. N. Cleland and John
M. Martinis | 1/f Flux Noise in Josephson Phase Qubits | 4 pages, 3 figures | null | 10.1103/PhysRevLett.99.187006 | null | cond-mat.supr-con cond-mat.mes-hall | null | We present a new method to measure 1/f noise in Josephson quantum bits
(qubits) that yields low-frequency spectra below 1Hz. Comparison of noise taken
at positive and negative bias of a phase qubit shows the dominant noise source
to be flux noise and not junction critical-current noise, with a magnitude
similar to that measured previously in other systems. Theoretical calculations
show that the level of flux noise is not compatible with the standard model of
noise from two-level state defects in the surface oxides of the films.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 03:16:10 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Bialczak",
"Radoslaw C.",
""
],
[
"McDermott",
"R.",
""
],
[
"Ansmann",
"M.",
""
],
[
"Hofheinz",
"M.",
""
],
[
"Katz",
"N.",
""
],
[
"Lucero",
"Erik",
""
],
[
"Neeley",
"Matthew",
""
],
[
"O'Connell",
"A. D.",
""
],
[
"Wang",
"H.",
""
],
[
"Cleland",
"A. N.",
""
],
[
"Martinis",
"John M.",
""
]
] |
0708.2126 | Juan E Rolon | Juan E. Rolon, Sergio E. Ulloa | Forster signatures and qubits in optically driven quantum dot molecules | Paper presented in the International Conference on Electronic
Properties of Two-dimensional Systems and Modulated Semiconductor Structures
Genova Magazzini del Cotone, July 15-20 2007 | null | 10.1016/j.physe.2007.09.141 | null | cond-mat.mes-hall | null | An interesting approach to achieve quantum gate operations in a solid state
device is to implement an optically driven quantum gate using two vertically
coupled self-assembled quantum dots, a quantum dot molecule (QDM). We present a
realistic model for exciton dynamics in InGaAs/GaAs QDMs under intense laser
excitation and applied electric fields. The dynamics is obtained by solutions
of the Lindblad master equation. A map of the dressed ground state as function
of laser energy and applied electric field exhibits rich structure that
includes excitonic anticrossings that permit the identification of the relevant
couplings. The optical signatures of the dipole-dipole Forster energy transfer
mechanism show as splittings of several (spatially) indirect excitonic lines.
Moreover, we construct a model for exciton qubit rotations by adiabatic
electric field cyclic sweeps into a Forster-tunneling regime which induces
level anticrossings. The proposed qubit exhibits Rabi oscillations among two
well defined exciton pairs as function of the residence time at the
anticrossing.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 03:18:27 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Rolon",
"Juan E.",
""
],
[
"Ulloa",
"Sergio E.",
""
]
] |
0708.2127 | Ken-Ji Hamada | Ken-ji Hamada (KEK), Azusa Minamizaki (Ochanomizu Univ.) and Akio
Sugamoto (Ochanomizu Univ.) | Baryogenesis by Quantum Gravity | 10 pages, 2 figures | Mod.Phys.Lett.A23:237-244,2008 | 10.1142/S021773230802639X | null | hep-ph gr-qc hep-th | null | A novel mechanism of baryogenesis is proposed on the basis of the phase
transition from the conformal invariant space-time to the Einstein space-time
in quantum gravity. Strong-coupling gravitational excitations with dynamical
mass about 10^17 GeV are generated at the transition. They eventually decay
into ordinary matters. As a realization of unparticle physics we show that the
low energy effective interactions between the gravitational potential
describing the excitation and the non-conserving matter currents by the axial
anomalies can explain matter asymmetry out of thermal equilibrium.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 03:39:20 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hamada",
"Ken-ji",
"",
"KEK"
],
[
"Minamizaki",
"Azusa",
"",
"Ochanomizu Univ."
],
[
"Sugamoto",
"Akio",
"",
"Ochanomizu Univ."
]
] |
0708.2128 | Jie Liu | Ju-Kui Xue, Ai-Xia Zhang, Jie Liu | Self-Trapping of Bose-Einstein Condensates in an Optical Lattice: the
Effect of the System Dimension | 8pages, 9 figures | Phys. Rev. A 77, 013602 (2008) | 10.1103/PhysRevA.77.013602 | null | cond-mat.mes-hall | null | In the present paper, we investigate the dynamics of a Bose-Einstein
condensates (BEC) loaded into an deep optical lattice of 1D, 2D and 3D, both
analytically and numerically. We focus on the self-trapping state and the
effect of the system dimension. Under the tight-binding approximation we obtain
an analytical criterion for the self-trapping state of BEC using time-dependent
variational method. The phase diagram for self-trapping, soliton, breather, or
diffusion of the BEC cloud is obtained accordingly and verified by directly
solving the discrete Gross-Pitaevskii equation (GPE) numerically. In
particular, we find that the criterion and the phase diagrams are modified
dramatically by the dimension of the lattices.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 03:41:57 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Xue",
"Ju-Kui",
""
],
[
"Zhang",
"Ai-Xia",
""
],
[
"Liu",
"Jie",
""
]
] |
0708.2129 | Xijia Miao | Xijia Miao | Unitarily manipulating in time and space a Gaussian wave-packet motional
state of a single atom in a quadratic potential field | 47 pages, no figure, a modified version with an important correction
in subsection 2.3 and section 3 | null | null | null | quant-ph | null | The paper first discusses theoretically the off-resonance selective
excitation method that is dependent on the atomic internal states and used to
generate approximately a standard coherent state of harmonic oscillator. The
coherent average method then is proposed to construct the state-selective
trigger pulse. A state-selective trigger pulse can keep Gaussian shape
unchanged but change in an internal-state-dependent form the center-of-mass
position and/or momentum of an atomic Gaussian wave-packet motional state. A
Gaussian wave-packet state is one of the simplest wave-packet states that can
be easily manipulated and controlled in time and space. The paper also
investigates how to manipulate in time and space an atomic Gaussian wave-packet
motional state by a generalized quadratic potential field. A general quadratic
Hamiltonian can affect not only the center-of-mass position and momentum but
also the complex linewidth of a Gaussian wave-packet motional state while keep
Gaussian shape of the motional state unchanged. It is shown that generally
quadratic terms of a quadratic Hamiltonian can control directly the complex
linewidth, while linear terms of a quadratic Hamiltonian can affect only the
center-of-mass position and momentum of a Gaussian wave-packet motional state.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 04:09:13 GMT"
},
{
"version": "v2",
"created": "Wed, 19 Sep 2007 13:42:10 GMT"
},
{
"version": "v3",
"created": "Fri, 12 Oct 2007 12:41:28 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Miao",
"Xijia",
""
]
] |
0708.2130 | Igor Shparlinski | Igor E. Shparlinski | On The Solvability of Bilinear Equations in Finite Fields | null | null | null | null | math.NT math.CO | null | We consider the equation $$ ab + cd = \lambda, \qquad a\in A, b \in B, c\in
C, d \in D, $$ over a finite field $F_q$ of $q$ elements, with variables from
arbitrary sets $ A, B, C, D \subseteq F_q$. The question of solvability of such
and more general equations has recently been considered by D. Hart and A.
Iosevich, who, in particular, proved that if $$ #A #B #C #D \gg q^3, $$ then
above equation has a solution for any $\lambda \in F_q^*$. Here we show that
using bounds of multiplicative character sums allows us to extend the class of
sets which satisfy this property.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 05:06:18 GMT"
},
{
"version": "v2",
"created": "Sun, 16 Sep 2007 14:29:17 GMT"
}
] | 2007-09-16T00:00:00 | [
[
"Shparlinski",
"Igor E.",
""
]
] |
0708.2131 | Kristof Petrovay | K. Petrovay | On the possibility of a bimodal solar dynamo | 4 pages, 1 figure; Astr. Nachr., in press | Astr. Nachr. 328, 777-780 (2007) | 10.1002/asna.200710804 | null | astro-ph | null | A simple way to couple an interface dynamo model to a fast tachocline model
is presented, under the assumption that the dynamo saturation is due to a
quadratic process and that the effect of finite shear layer thickness on the
dynamo wave frequency is analoguous to the effect of finite water depth on
surface gravity waves. The model contains one free parameter which is fixed by
the requirement that a solution should reproduce the helioseismically
determined thickness of the tachocline. In this case it is found that, in
addition to this solution, another steady solution exists, characterized by a
four times thicker tachocline and 4-5 times weaker magnetic fields. It is
tempting to relate the existence of this second solution to the occurrence of
grand minima in solar activity.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 03:56:47 GMT"
}
] | 2008-06-05T00:00:00 | [
[
"Petrovay",
"K.",
""
]
] |
0708.2132 | Jie Liu | Di-Fa Ye, Jing Chen, Jie Liu | Classical Trajectory Perspective on Double Ionization Dynamics of
Diatomic Molecules Irradiated by Ultrashort Intense Laser Pulses | 8 pages, 9 figures | Phys. Rev. A 77, 013403 (2008) | 10.1103/PhysRevA.77.013403 | null | physics.atm-clus | null | In the present paper, we develop a semiclassical quasi-static model
accounting for molecular double ionization in an intense laser pulse. With this
model, we achieve insight into the dynamics of two highly-correlated valence
electrons under the combined influence of a two-center Coulomb potential and an
intense laser field, and reveal the significant influence of molecular
alignment on the ratio of double over single ion yield. Analysis on the
classical trajectories unveils sub-cycle dynamics of the molecular double
ionization. Many interesting features, such as the accumulation of emitted
electrons in the first and third quadrants of parallel momentum plane, the
regular pattern of correlated momentum with respect to the time delay between
closest collision and ionization moment, are revealed and successfully
explained by back analyzing the classical trajectories. Quantitative agreement
with experimental data over a wide range of laser intensities from tunneling to
over-the-barrier regime is presented.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 04:00:51 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ye",
"Di-Fa",
""
],
[
"Chen",
"Jing",
""
],
[
"Liu",
"Jie",
""
]
] |
0708.2133 | Magno Machado | M. V. T. Machado | Hard diffractive quarkonium hadroproduction at high energies | 7 pages, 3 figures, 1 table. Final version to be published in
European Physical Journal C | Eur.Phys.J.C54:443-449,2008 | 10.1140/epjc/s10052-008-0526-5 | null | hep-ph hep-ex nucl-th | null | We present a study of heavy quarkonium production in hard diffractive process
by the Pomeron exchange for Tevatron and LHC energies. The numerical results
are computed using recent experimental determination of the diffractive parton
density functions in Pomeron and are corrected by unitarity corrections through
gap survival probability factor. We give predictions for single as well as
central diffractive ratios. These processes are sensitive to the gluon content
of the Pomeron at small Bjorken-x and may be particularly useful in studying
the small-x physics. They may also be a good place to test the different
available mechanisms for quarkonium production at hadron colliders.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 04:01:27 GMT"
},
{
"version": "v2",
"created": "Wed, 22 Aug 2007 19:24:02 GMT"
},
{
"version": "v3",
"created": "Thu, 23 Aug 2007 20:49:29 GMT"
},
{
"version": "v4",
"created": "Fri, 21 Dec 2007 17:08:50 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Machado",
"M. V. T.",
""
]
] |
0708.2134 | Mark J. Reid | M. J. Reid and Karl M. Menten | Imaging the Radio Photospheres of Mira Variables | 14 pages; 3 figures | null | 10.1086/523085 | null | astro-ph | null | We have used the VLA at 43 GHz to image the radio continuum emission from o
Ceti, R Leo, and W Hya and to precisely locate their SiO maser emission with
respect to the star. The radio continuum emission region for all three stars
has a diameter close to 5.6 AU. These diameters are similar to those measured
at infrared wavelengths in bands containing strong molecular opacity and about
twice those measured in line-free regions of the infrared spectrum. Thus, the
radio photosphere and the infrared molecular layer appear to be coextensive.
The 43 GHz continuum emission is consistent with temperatures near 1600 K and
opacity from H-minus free-free interactions. While the continuum image of o
Ceti appears nearly circular, both R Leo and W Hya display significant
elongations. The SiO masers for all three stars show partial rings with
diameters close to 8 AU.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 04:16:13 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Reid",
"M. J.",
""
],
[
"Menten",
"Karl M.",
""
]
] |
0708.2135 | Koji Kawabata | K. S. Kawabata, Y. Ikeda, H. Akitaya, M. Isogai, K. Matsuda, M.
Matsumura, O. Nagae and M. Seki | Spectropolarimetry of R Coronae Borealis in 1998--2003: Discovery of
Transient Polarization at Maximum Brightness | 22 pages, 10 figures, accepted for publication in AJ | Astron.J.134:1877-1889,2007 | 10.1086/522629 | null | astro-ph | null | We present an extended optical spectropolarimetry of R CrB from 1998 January
to 2003 September. The polarization was almost constant in the phase of maximum
brightness, being consistent with past observations. We detected, however,
temporal changes of polarization ($\sim 0.5$ %) in 2001 March and August, which
were the first detection of large polarization variability in R CrB near
maximum brightness. The amplitude and the position angle of the `transient
polarization' were almost constant with wavelength in both two events. There
was a difference by about 20 degrees in the position angle between the two
events. Each event could be explained by light scattering due to short-lived
dust puff occasionally ejected off the line of sight. The flatness of the
polarization against the wavelength suggests that the scatterer is a mixture of
dust grains having various sizes. The rapid growth and fading of the transient
polarization favors the phenomenological model of dust formation near the
stellar photosphere (e.g., within two stellar radii) proposed for the time
evolution of brightness and chromospheric emission lines during deeply
declining periods, although the fading timescale can hardly be explained by a
simple dispersal of expanding dust puff with a velocity of $\sim 200-350$ km s
$^{-1}$. Higher expansion velocity or some mechanism to destroy the dust grains
should be needed.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 04:16:40 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Kawabata",
"K. S.",
""
],
[
"Ikeda",
"Y.",
""
],
[
"Akitaya",
"H.",
""
],
[
"Isogai",
"M.",
""
],
[
"Matsuda",
"K.",
""
],
[
"Matsumura",
"M.",
""
],
[
"Nagae",
"O.",
""
],
[
"Seki",
"M.",
""
]
] |
0708.2136 | Timothy Speer | Timothy Speer | A Short Study of Alexandroff Spaces | 10 pages | null | null | null | math.GN | null | In this paper, we discuss the basic properties of Alexandroff spaces. Several
examples of Alexandroff spaces are given. We show how to construct new
Alexandroff spaces from given ones. Finally, two invariants for compact
Alexandroff spaces are defined and calculated for the given examples.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 04:54:06 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"Speer",
"Timothy",
""
]
] |
0708.2137 | Ryusuke Ikeda | Ryusuke Ikeda and Hidehumi Nawata | Josephson vortex lattices with modulation perpendicular to an in-plane
magnetic field in layered superconductor | 8 figures | null | null | null | cond-mat.supr-con | null | In quasi low dimensional superconductors under {\it parallel} magnetic fields
applied along a conducting direction, vortex lattices with a modulation of
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) type {\it perpendicular} to the field
may occur due to an enhanced paramagnetic depairing. As the strength of an
in-plane field is varied in a Q2D material, the Josephson vortex lattices
accompanied by nodal planes are formed in higher Landau level (LL) modes of the
superconducting (SC) order parameter and show field-induced structural
transitions. A change of orientation of nodal planes induced by these
transitions should be observed in transport measurements for an out-of-plane
current in real superconductors with point disorder effective on the SC layers.
Further, the $H_{c2}$-transition from this higher LL state to the normal phase
is of second order for moderately strong paramagnetic effects but, in the case
with a strong enough paramagnetic effect, becomes discontinuous as well as the
transition between this modulated state and an ordinary Abrikosov vortex
lattice in the lowest LL. Relevance of these results to recent observations in
organic superconductors suggesting the presence of an FFLO state are discussed.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 05:05:56 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"Ikeda",
"Ryusuke",
""
],
[
"Nawata",
"Hidehumi",
""
]
] |
0708.2138 | Senthamrai Kannan S | S. S. Kannan, Pranab Sardar | Torus quotients of homogeneous spaces of the general linear group and
the standard representation of certain symmetric groups | 19 pages | null | null | null | math.AG math.RT | null | We give a stratification of the GIT quotient of the Grassmannian $G_{2,n}$
modulo the normaliser of a maximal torus of $SL_{n}(k)$ with respect to the
ample generator of the Picard group of $G_{2,n}$. We also prove that the flag
variety $GL_{n}(k)/B_{n}$ can be obtained as a GIT quotient of
$GL_{n+1}(k)/B_{n+1}$ modulo a maximal torus of $SL_{n+1}(k)$ for a suitable
choice of an ample line bundle on $GL_{n+1}(k)/B_{n+1}$.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 05:41:41 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"Kannan",
"S. S.",
""
],
[
"Sardar",
"Pranab",
""
]
] |
0708.2139 | R. Rajesh | Colm Connaughton, R. Rajesh, Oleg Zaboronski | Constant flux relation for aggregation models with desorption and
fragmentation | 5 pages 2 figures, To appear in Physica A | Physica A Vol. 384, pg 108 (2007). | 10.1016/j.physa.2007.04.074 | null | cond-mat.stat-mech | null | We study mass fluxes in aggregation models where mass transfer to large
scales by aggregation occurs alongside desorption or fragmentation. Two models
are considered. (1) A system of diffusing, aggregating particles with influx
and outflux of particles (in-out model) (2) A system of diffusing aggregating
particles with fragmentation (chipping model). Both these models can exist in
phases where probability distributions are power laws. In these power law
phases, we argue that the two point correlation function should have a certain
homogeneity exponent. These arguments are based on the exact constant flux
scaling valid for simple aggregation with input. Predictions are compared with
Monte Carlo simulations.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 05:45:23 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Connaughton",
"Colm",
""
],
[
"Rajesh",
"R.",
""
],
[
"Zaboronski",
"Oleg",
""
]
] |
0708.2140 | Zorica Konstantinovic | Z Konstantinovic, M Garcia del Muro, X Batlle, and A Labarta, M.
Varela | The nanostructural origin of the ac conductance in dielectric granular
metals: the case study of Co_20(ZrO_2)_80 | Available online at:
http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=APPLAB000091000005052108000001&idtype=cvips&gifs=yes | Appl. Phys. Lett. 91, 052108 (2007) | 10.1063/1.2766858 | null | cond-mat.mtrl-sci cond-mat.dis-nn | null | We show which is the nanostructure required in granular Co20(ZrO2)80 thin
films to produce an ac response such as the one that is universally observed in
a very wide variety of dielectric materials. A bimodal size distribution of Co
particles yields randomly competing conductance channels which allow both
thermally assisted tunneling through small particles and capacitive conductance
among larger particles that are further apart. A model consisting on a simple
cubic random resistance-capacitor network describes quantitatively the
experimental results as functions of temperature and frequency, and enables the
determination of the microscopic parameters controlling the ac response of the
samples.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 06:32:51 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"Konstantinovic",
"Z",
""
],
[
"del Muro",
"M Garcia",
""
],
[
"Batlle",
"X",
""
],
[
"Labarta",
"A",
""
],
[
"Varela",
"M.",
""
]
] |
0708.2141 | Shyamal Lakshminarayanan | Shyamal Lakshminarayanan | A model for exploring bird morphology | 7 pages, 1 table, 3 figures | null | null | null | q-bio.OT | null | A simplified model of the bird skeleton along with elongation parameters for
the flight feathers is used to explore the diversity of bird shapes. Varying a
small number of parameters simulates a wide range of observed bird silhouettes.
The model may serve to examine developmental factors involved, help museum
curators develop computational approaches to bird morphometry and has
applications in computer generated illustration.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 06:34:53 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"Lakshminarayanan",
"Shyamal",
""
]
] |
0708.2142 | Minhsiu Hsieh | Min-Hsiu Hsieh, Igor Devetak and Todd Brun | General entanglement-assisted quantum error-correcting codes | 7 pages, no figure | Phys. Rev. A 76, 062313 (2007) | 10.1103/PhysRevA.76.062313 | null | quant-ph | null | Entanglement-assisted quantum error-correcting codes (EAQECCs) make use of
pre-existing entanglement between the sender and receiver to boost the rate of
transmission. It is possible to construct an EAQECC from any classical linear
code, unlike standard QECCs which can only be constructed from dual-containing
codes. Operator quantum error-correcting codes (OQECCs) allow certain errors to
be corrected (or prevented) passively, reducing the complexity of the
correction procedure. We combine these two extensions of standard quantum error
correction into a unified entanglement-assisted quantum error correction
formalism. This new scheme, which we call entanglement-assisted operator
quantum error correction (EAOQEC), is the most general and powerful quantum
error-correcting technique known, retaining the advantages of both
entanglement-assistance and passive correction. We present the formalism, show
the considerable freedom in constructing EAOQECCs from classical codes, and
demonstrate the construction with examples.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 06:40:58 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Hsieh",
"Min-Hsiu",
""
],
[
"Devetak",
"Igor",
""
],
[
"Brun",
"Todd",
""
]
] |
0708.2143 | Yuan Xu | Yuan Xu, Shuai Wang and Ke Xia | Spin-transfer torques in anti-ferromagnetic metals from first principles | The paper has substantially been rewritten, 4 pages, 5 figures | Physical Review Letters, 100, 226602 (2008) | 10.1103/PhysRevLett.100.226602 | null | cond-mat.mtrl-sci | null | In spite of the absence of a macroscopic magnetic moment, an anti-ferromagnet
is spin-polarized on an atomic scale. The electric current passing through a
conducting anti-ferromagnet is polarized as well, leading to spin-transfer
torques when the order parameter is textured, such as in anti-ferromagnetic
non-collinear spin valves and domain walls. We report a first principles study
on the electronic transport properties of anti-ferromagnetic systems. The
current-induced spin torques acting on the magnetic moments are comparable with
those in conventional ferromagnetic materials, leading to measurable angular
resistances and current-induced magnetization dynamics. In contrast to
ferromagnets, spin torques in anti-ferromagnets are very nonlocal. The torques
acting far away from the center of an anti-ferromagnetic domain wall should
facilitate current-induced domain wall motion.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 07:55:58 GMT"
},
{
"version": "v2",
"created": "Wed, 4 Jun 2008 02:22:57 GMT"
}
] | 2009-09-29T00:00:00 | [
[
"Xu",
"Yuan",
""
],
[
"Wang",
"Shuai",
""
],
[
"Xia",
"Ke",
""
]
] |
0708.2144 | Eric Woolgar | E. Woolgar | Some Applications of Ricci Flow in Physics | Minor corrections in Sections IV and VI. Invited talk at Theory
Canada III meeting, June 2007; submitted to Proceedings. Dedicated to Rafael
D Sorkin on the occasion of his 60th birthday | Can.J.Phys.86:645,2008 | 10.1139/P07-146 | null | hep-th gr-qc math.DG | null | I discuss certain applications of the Ricci flow in physics. I first review
how it arises in the renormalization group (RG) flow of a nonlinear sigma
model. I then review the concept of a Ricci soliton and recall how a soliton
was used to discuss the RG flow of mass in 2-dimensions. I then present recent
results obtained with Oliynyk on the flow of mass in higher dimensions. The
final section discusses one way in which Ricci flow may arise in general
relativity, particularly for static metrics.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 06:50:14 GMT"
},
{
"version": "v2",
"created": "Mon, 27 Aug 2007 04:52:23 GMT"
},
{
"version": "v3",
"created": "Mon, 31 Dec 2007 04:03:04 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Woolgar",
"E.",
""
]
] |
0708.2145 | John Bulava | John Bulava, Robert Edwards, George Fleming, K. Jimmy Juge, Adam C.
Lichtl, Nilmani Mathur, Colin Morningstar, David Richards, Stephen J. Wallace | Results and Frontiers in Lattice Baryon Spectroscopy | To appear in the proceedings for the VII Latin American Symposium of
Nuclear Physics and Applications | AIP Conf.Proc.947:137-140,2007 | 10.1063/1.2813791 | null | hep-lat | null | The Lattice Hadron Physics Collaboration (LHPC) baryon spectroscopy effort is
reviewed. To date the LHPC has performed exploratory Lattice QCD calculations
of the low-lying spectrum of Nucleon and Delta baryons. These calculations
demonstrate the effectiveness of our method by obtaining the masses of an
unprecedented number of excited states with definite quantum numbers. Future
work of the project is outlined.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 07:03:27 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Bulava",
"John",
""
],
[
"Edwards",
"Robert",
""
],
[
"Fleming",
"George",
""
],
[
"Juge",
"K. Jimmy",
""
],
[
"Lichtl",
"Adam C.",
""
],
[
"Mathur",
"Nilmani",
""
],
[
"Morningstar",
"Colin",
""
],
[
"Richards",
"David",
""
],
[
"Wallace",
"Stephen J.",
""
]
] |
0708.2146 | Kaptari Leonid | S. M. Dorkin (International University Dubna, Dubna), M. Beyer (Inst.
of Phys. Univ. of Rostock), S. S. Semikh and L. P. Kaptari (Bogoliubov Lab.
Theor. Phys., JINR, Dubna) | Two-Fermion Bound States within the Bethe-Salpeter Approach | 32 pages, XIII Tables, 8 figures | FewBodySyst.42:1-32,2008 | 10.1007/s00601-008-0196-8 | null | nucl-th hep-ph | null | To solve the spinor-spinor Bethe-Salpeter equation in Euclidean space we
propose a novel method related to the use of hyperspherical harmonics. We
suggest an appropriate extension to form a new basis of spin-angular harmonics
that is suitable for a representation of the vertex functions. We present a
numerical algorithm to solve the Bethe-Salpeter equation and investigate in
detail the properties of the solution for the scalar, pseudoscalar and vector
meson exchange kernels including the stability of bound states. We also compare
our results to the non relativistic ones and to the results given by light
front dynamics.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 07:08:20 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Dorkin",
"S. M.",
"",
"International University Dubna, Dubna"
],
[
"Beyer",
"M.",
"",
"Inst.\n of Phys. Univ. of Rostock"
],
[
"Semikh",
"S. S.",
"",
"Bogoliubov Lab.\n Theor. Phys., JINR, Dubna"
],
[
"Kaptari",
"L. P.",
"",
"Bogoliubov Lab.\n Theor. Phys., JINR, Dubna"
]
] |
0708.2147 | Dalius Balciunas | Dalius Balciunas | The logistic equation and a critique of the theory of natural selection | 31 pages, 5 figures, appendix | null | null | null | q-bio.PE | null | Species coexistence is one of the central themes in modern ecology.
Coexistence is a prerequisite of biological diversity. However, the question
arises how biodiversity can be reconciled with the statement of competition
theory, which asserts that competing species cannot coexist. To solve this
problem natural selection theory is rejected because it contradicts kinetic
models of interacting populations. Biological evolution is presented as a
process equivalent to a chemical reaction. The main point is that interactions
occur between self-replicating units. Under these assumptions biodiversity is
possible if and only if species are identical with respect to the patterns of
energy flow in which individuals are involved.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 07:15:04 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"Balciunas",
"Dalius",
""
]
] |
0708.2148 | Reza Nourafkan | R. Nourafkan and N. Nafari | Kondo lattice model at half-filling | 11 pages, 5 figures | null | 10.1088/0953-8984/20/25/255231 | null | cond-mat.str-el | null | The single- and two-channel Kondo lattice model consisting of localized spins
interacting antiferromagnetically with the itinerent electrons, are studied
using dynamical mean field theory. As an impurity solver for the effective
single impurity Anderson model we used the exact diagonalization (ED) method.
Using ED allowed us to perform calculations for low temperatures and couplings
of arbitrary large strength. Our results for the single-channel case confirm
and extend the recent investigations. In the two-channel case we find a
symmetry breaking phase transition with increasing coupling strength.
| [
{
"version": "v1",
"created": "Thu, 16 Aug 2007 07:21:03 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Nourafkan",
"R.",
""
],
[
"Nafari",
"N.",
""
]
] |
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