title: GeV photon absorption in cosmologically evolving quasar environments

abstract:
  The question of a possible redshift-dependence of gamma-ray absorption due to
gamma-gamma pair production of jet photons in the accretion disk and BLR
radiation field in strong-line quasars is investigated. For this relevant
aspects of cosmological black hole and quasar evolution are applied to the
expected pair production opacity of GeV-photons in those sources. I demonstrate
that for positively evolving and non-evolving accretion rates over cosmological
time, detectable gamma-ray optical depths originating within the AGN system
will show a redshift-dependence in the LAT energy range with larger opacity
from sources at higher redshifts. This introduces ambiguities in the
interpretation of spectral absorption features, and complicates approaches for
estimating the evolution of the extragalactic background light by probing the
gamma-ray horizon when using blazars whose external photon fields are involved
in gamma-ray production.


title: Massive stars in colliding wind systems: the GLAST perspective

abstract:
  Colliding winds of massive stars in binary systems are considered as
candidate sites of high-energy non-thermal photon emission. They are already
among the suggested counterparts for a few individual unidentified EGRET
sources, but may constitute a detectable source population for the GLAST
observatory. The present work investigates such population study of massive
colliding wind systems at high-energy gamma-rays. Based on the recent detailed
model (Reimer et al. 2006) for non-thermal photon production in prime candidate
systems, we unveil the expected characteristics of this source class in the
observables accessible at LAT energies. Combining the broadband emission model
with the presently cataloged distribution of such systems and their individual
parameters allows us to conclude on the expected maximum number of
LAT-detections among massive stars in colliding wind binary systems.


title: A self-consistent theory for graphene transport

abstract:
  We demonstrate theoretically that most of the observed transport properties
of graphene sheets at zero magnetic field can be explained by scattering from
charged impurities. We find that, contrary to common perception, these
properties are not universal but depend on the concentration of charged
impurities $n_{\rm imp}$. For dirty samples ($250 \times 10^{10} {\rm cm}^{-2}
< n_{\rm imp} < 400 \times 10^{10} {\rm cm}^{-2}$), the value of the minimum
conductivity at low carrier density is indeed $4 e^2/h$ in agreement with early
experiments, with weak dependence on impurity concentration. For cleaner
samples, we predict that the minimum conductivity depends strongly on $n_{\rm
imp}$, increasing to $8 e^2/h$ for $n_{\rm imp} \sim 20 \times 10^{10}{\rm
cm}^{-2}$. A clear strategy to improve graphene mobility is to eliminate
charged impurities or use a substrate with a larger dielectric constant.


title: Unfolding Manhattan Towers

abstract:
  We provide an algorithm for unfolding the surface of any orthogonal
polyhedron that falls into a particular shape class we call Manhattan Towers,
to a nonoverlapping planar orthogonal polygon. The algorithm cuts along edges
of a 4x5x1 refinement of the vertex grid.


title:
Descriptor approach for eliminating spurious eigenvalues in hydrodynamic
  equations

abstract:
  We describe a general framework for avoiding spurious eigenvalues --
unphysical unstable eigenvalues that often occur in hydrodynamic stability
problems. In two example problems, we show that when system stability is
analyzed numerically using {\em descriptor} notation, spurious eigenvalues are
eliminated. Descriptor notation is a generalized eigenvalue formulation for
differential-algebraic equations that explicitly retains algebraic constraints.
We propose that spurious eigenvalues are likely to occur when algebraic
constraints are used to analytically reduce the number of independent variables
in a differential-algebraic system of equations before the system is
approximated numerically. In contrast, the simple and easily generalizable
descriptor framework simultaneously solves the differential equations and
algebraic constraints and is well-suited to stability analysis in these
systems.


title: Universal Periods in Quantum Hall Droplets

abstract:
  Using the hierarchy picture of the fractional quantum Hall effect, we study
the the ground state periodicity of a finite size quantum Hall droplet in a
quantum Hall fluid of a different filling factor. The droplet edge charge is
periodically modulated with flux through the droplet and will lead to a
periodic variation in the conductance of a nearby point contact, such as occurs
in some quantum Hall interferometers. Our model is consistent with experiment
and predicts that superperiods can be observed in geometries where no
interfering trajectories occur. The model may also provide an experimentally
feasible method of detecting elusive neutral modes and otherwise obtaining
information about the microscopic edge structure in fractional quantum Hall
states.


title:
On the optical counterpart of NGC300 X-1 and the global Wolf-Rayet
  content of NGC300

abstract:
  (Conext:) Surveys of Wolf-Rayet (WR) populations in nearby galaxies provide
tests of evolutionary models plus Type Ib/c supernova progenitors. This
spectroscopic study complements the recent imaging survey of the spiral galaxy
NGC 300 by Schild et al. (Aims): Revisions to the known WR content of NGC 300
are presented. We investigate the WR nature of candidate #41 from Schild et al.
which is spatially coincident with the bright X-ray point source NGC 300 X-1;
(Methods:) VLT/FORS2 multi-object spectroscopy of WR candidates in NGC 300 is
obtained; (Results:) We establish an early-type WN nature of #41, i.e. similar
to the optical counterpart of IC 10 X-1, which closely resembles NGC 300 X-1.
We confirm 9 new WR stars, bringing the current WR census of the inner disk to
31, with N(WC)/N(WN)~0.9. (Conclusions:) If #41 is the optical counterpart for
NGC 300 X-1, we estimate a WR mass of 38 Msun based upon ground-based
photometry, from which a black hole mass of > 10 Msun results from the 32.8 hr
period of the system and WR wind velocity of 1250 km/s. We estimate an 95%
completeness among WC stars and 70% among WN stars, such that the total WR
content is ~40, with N(WC)/N(WN)~0.7. From the Halpha-derived star formation
rate of the inner galaxy, we infer N(WR)/N(O)~0.04


title: GLAST Prospects for Swift-Era Afterglows

abstract:
  We calculate the GeV spectra of GRB afterglows produced by inverse Compton
scattering of the sub-MeV emission of these objects. We improve on earlier
treatments by using refined afterglow parameters and new model developments
motivated by recent Swift observations. We present time-dependent GeV spectra
for standard, constant parameter models, as well as for models with energy
injection and with time-varying parameters, for a range of burst parameters. We
evaluate the limiting redshift to which such afterglows can be detected by the
GLAST LAT, as well as AGILE.


title: Outflows and the Physical Properties of Quasars

abstract:
  We have investigated a sample of 5088 quasars from the Sloan Digital Sky
Survey Second Data Release in order to determine how the frequency and
properties of broad absorptions lines (BALs) depend on black hole mass,
bolometric luminosity, Eddington fraction (L/L_Edd), and spectral slope. We
focus only on high-ionization BALs and find a number of significant results.
While quasars accreting near the Eddington limit are more likely to show BALs
than lower $L/L_{Edd}$ systems, BALs are present in quasars accreting at only a
few percent Eddington. We find a stronger effect with bolometric luminosity,
such that the most luminous quasars are more likely to show BALs. There is an
additional effect, previously known, that BAL quasars are redder on average
than unabsorbed quasars. The strongest effects involving the quasar physical
properties and BAL properties are related to terminal outflow velocity. Maximum
observed outflow velocities increase with both the bolometric luminosity and
the blueness of the spectral slope, suggesting that the ultraviolet luminosity
to a great extent determines the acceleration. These results support the idea
of outflow acceleration via ultraviolet line scattering.


title:
Numerical evaluation of the upper critical dimension of percolation in
  scale-free networks

abstract:
  We propose a numerical method to evaluate the upper critical dimension $d_c$
of random percolation clusters in Erd\H{o}s-R\'{e}nyi networks and in
scale-free networks with degree distribution ${\cal P}(k) \sim k^{-\lambda}$,
where $k$ is the degree of a node and $\lambda$ is the broadness of the degree
distribution. Our results report the theoretical prediction, $d_c = 2(\lambda -
1)/(\lambda - 3)$ for scale-free networks with $3 < \lambda < 4$ and $d_c = 6$
for Erd\H{o}s-R\'{e}nyi networks and scale-free networks with $\lambda > 4$.
When the removal of nodes is not random but targeted on removing the highest
degree nodes we obtain $d_c = 6$ for all $\lambda > 2$. Our method also yields
a better numerical evaluation of the critical percolation threshold, $p_c$, for
scale-free networks. Our results suggest that the finite size effects increases
when $\lambda$ approaches 3 from above.


title: Dimensionality and dynamics in the behavior of C. elegans

abstract:
  A major challenge in analyzing animal behavior is to discover some underlying
simplicity in complex motor actions. Here we show that the space of shapes
adopted by the nematode C. elegans is surprisingly low dimensional, with just
four dimensions accounting for 95% of the shape variance, and we partially
reconstruct "equations of motion" for the dynamics in this space. These
dynamics have multiple attractors, and we find that the worm visits these in a
rapid and almost completely deterministic response to weak thermal stimuli.
Stimulus-dependent correlations among the different modes suggest that one can
generate more reliable behaviors by synchronizing stimuli to the state of the
worm in shape space. We confirm this prediction, effectively "steering" the
worm in real time.


title: Cluster-type entangled coherent states

abstract:
  We present the cluster-type entangled coherent states (CTECS) and discuss
their properties. A cavity QED generation scheme using suitable choices of
atom-cavity interactions, obtained via detunings adjustments and the
application of classical external fields, is also presented. After the
realization of simple atomic measurements, CTECS representing nonlocal
electromagnetic fields in separate cavities can be generated.


title:
Zgamma production and limits on anomalous ZZgamma and Zgammagamma
  couplings in ppbar collisions at sqrt(s) = 1.96 TeV

abstract:
  We present a study of eegamma and mumugamma events using 1109 (1009) pb-1 of
data in the electron (muon) channel, respectively. These data were collected
with the D0 detector at the Fermilab Tevatron ppbar Collider at sqrt(s) = 1.96
TeV. Having observed 453 (515) candidates in the eegamma (mumugamma) final
state, we measure the Zgamma production cross section for a photon with
transverse energy ET > 7 GeV, separation between the photon and leptons Delta
R(lgamma) > 0.7, and invariant mass of the di-lepton pair M(ll) > 30 GeV/c^2,
to be 4.96 +/- 0.30(stat. + syst.) +/- 0.30(lumi.) pb, in agreement with the
standard model prediction of 4.74 +/- 0.22 pb. This is the most precise Zgamma
cross section measurement at a hadron collider. We set limits on anomalous
trilinear Zgammagamma and ZZgamma gauge boson couplings of -0.085 <
h(30)^(gamma) < 0.084, -0.0053 < h(40)^(gamma) < 0.0054 and -0.083 < h(30)^(Z)
< 0.082, -0.0053 < h(40)^(Z) < 0.0054 at the 95% C.L. for the form-factor scale
Lambda = 1.2 TeV.


title:
Beryllium in Ultra-Lithium-Deficient Halo Stars - The Blue Straggler
  Connection

abstract:
  There are nine metal-deficient stars that have Li abundances well below the
Li plateau that is defined by over 100 unevolved stars with temperatures above
5800 K and values of [Fe/H] $<$ $-$1.0. Abundances of Be have been determined
for most of these ultra-Li-deficient stars in order to investigate the cause of
the Li deficiencies. High-resolution and high signal-to-noise spectra have been
obtained in the Be II spectral region near 3130 \AA for six ultra-Li-deficient
stars with the Keck I telescope and its new uv-sensitive CCD on the upgraded
HIRES. The spectrum synthesis technique has been used to determine Be
abundances. All six stars are found to have Be deficiencies also. Two have
measurable - but reduced - Be and four have only upper limits on Be. These
results are consistent with the idea that these Li- and Be-deficient stars are
analogous to blue stragglers. The stars have undergone mass transfer events (or
mergers) which destroy or dilute both Li and Be. The findings cannot be matched
by the models that predict that the deficiencies are due to extra-mixing in a
subset of halo stars that were initially rapid rotators, with the possible
exception of one star, G 139-8. Because the ultra-Li-deficient stars are also
Be-deficient, they appear to be genuine outliers in population of halo stars
used to determine the value of primordial Li; they no longer have the Li in
their atmospheres that was produced in the Big Bang.


title:
Stability transitions for axisymmetric relative equilibria of Euclidean
  symmetric Hamiltonian systems

abstract:
  In the presence of noncompact symmetry, the stability of relative equilibria
under momentum-preserving perturbations does not generally imply robust
stability under momentum-changing perturbations. For axisymmetric relative
equilibria of Hamiltonian systems with Euclidean symmetry, we investigate
different mechanisms of stability: stability by energy-momentum confinement,
KAM, and Nekhoroshev stability, and we explain the transitions between these.
We apply our results to the Kirchhoff model for the motion of an axisymmetric
underwater vehicle, and we numerically study dissipation induced instability of
KAM stable relative equilibria for this system.


title:
Effect of Orbital Angular Momentum on Valence-Quark Helicity
  Distributions

abstract:
  We study the quark helicity distributions at large x in perturbative QCD,
taking into account contributions from the valence Fock states of the nucleon
which have nonzero orbital angular momentum. These states are necessary to have
a nonzero anomalous magnetic moment. We find that the quark orbital angular
momentum contributes a large logarithm to the negative helicity quark
distributions in addition to its power behavior, scaling as (1-x)^5\log^2(1-x)
in the limit of x\to 1. Our analysis shows that the ratio of the polarized over
unpolarized down quark distributions, \Delta d/d, will still approach 1 in this
limit. By comparing with the experimental data, we find that this ratio should
cross zero at x\approx 0.75.


title:
Milagro Constraints on Very High Energy Emission from Short Duration
  Gamma-Ray Bursts

abstract:
  Recent rapid localizations of short, hard gamma-ray bursts (GRBs) by the
Swift and HETE satellites have led to the observation of the first afterglows
and the measurement of the first redshifts from this type of burst. Detection
of >100 GeV counterparts would place powerful constraints on GRB mechanisms.
Seventeen short duration (< 5 s) GRBs detected by satellites occurred within
the field of view of the Milagro gamma-ray observatory between 2000 January and
2006 December. We have searched the Milagro data for >100 GeV counterparts to
these GRBs and find no significant emission correlated with these bursts. Due
to the absorption of high-energy gamma rays by the extragalactic background
light (EBL), detections are only expected for redshifts less than ~0.5. While
most long duration GRBs occur at redshifts higher than 0.5, the opposite is
thought to be true of short GRBs. Lack of a detected VHE signal thus allows
setting meaningful fluence limits. One GRB in the sample (050509b) has a likely
association with a galaxy at a redshift of 0.225, while another (051103) has
been tentatively linked to the nearby galaxy M81. Fluence limits are corrected
for EBL absorption, either using the known measured redshift, or computing the
corresponding absorption for a redshift of 0.1 and 0.5, as well as for the case
of z=0.


title:
Effective anisotropy of thin nanomagnets: beyond the surface anisotropy
  approach

abstract:
  We study the effective anisotropy induced in thin nanomagnets by the nonlocal
demagnetization field (dipole-dipole interaction). Assuming a magnetization
independent of the thickness coordinate, we reduce the energy to an
inhomogeneneous onsite anisotropy. Vortex solutions exist and are ground states
for this model. We illustrate our approach for a disk and a square geometry. In
particular, we obtain good agreement between spin-lattice simulations with this
effective anisotropy and micromagnetic simulations.


title: Simulating Cosmological Evolution with Enzo

abstract:
  In this paper we describe our massively parallel version of Enzo, a
multiphysics, parallel, AMR application for simulating cosmological structure
formation developed at UCSD and Columbia. We describe its physics, numerical
algorithms, implementation, and performance on current terascale platforms. We
also discuss our future plans and some of the challenges we face as we move to
the petascale.


title: Lifetime of Stringy de Sitter Vacua

abstract:
  In this note we perform a synopsis of the life-times from vacuum decay of
several de Sitter vacuum constructions in string/M-theory which have a single
dS minimum arising from lifting a pre-existing AdS extremum and no other local
minima existent after lifting. For these vacua the decay proceeds via a
Coleman--De Luccia instanton towards the universal Minkowski minimum at
infinite volume. This can be calculated using the thin--wall approximation,
provided the cosmological constant of the local dS minimum is tuned
sufficiently small. We compare the estimates for the different model classes
and find them all stable in the sense of exponentially long life times as long
as they have a very small cosmological constant and a scale of supersymmetry
breaking > TeV.


title:
The Interaction Between a Pulsed Astrophysical Jet and Small-Scale
  Heterogeneous Media

abstract:
  We have performed 2D hydrodynamic simulations of a pulsed astrophysical jet
propagating through a medium that is populated with spherical inhomogeneities,
or "clumps," which are smaller than the jet radius. The clumps are seen to
affect the jet in several ways, such as impeding jet propagation and deflecting
the jet off-axis. While there has been some debate as to the prevalence of
these types of condensations in the ISM or in molecular clouds, the exploration
of this region of parameter space nonetheless both shows the potential for
these clumps to disrupt astrophysical jets and yields results which recover
aspects of recent observations of Herbig-Haro objects. We find that the
propagation of the jet and the vorticity induced in the clump/ambient medium
correlate well with a "dynamic filling function" $f_d$ across all the
simulations.


title: Effects of crosslinks on motor-mediated filament organization

abstract:
  Crosslinks and molecular motors play an important role in the organization of
cytoskeletal filament networks. Here we incorporate the effect of crosslinks
into our model of polar motor-filament organization [Phys. Rev. E {\bf 71},
050901 (2005)], through suppressing the relative sliding of filaments in the
course of motor-mediated alignment. We show that this modification leads to a
nontrivial macroscopic behavior, namely the oriented state exhibits a
transverse instability in contrast to the isotropic instability that occurs
without crosslinks. This transverse instability leads to the formation of dense
extended bundles of oriented filaments, similar to recently observed structures
in actomyosin. This model also can be applied to situations with two oppositely
directed motor species or motors with different processing speeds.


title: Spin Star as Switch for Quantum Networks

abstract:
  Quantum state transfer is an important task in quantum information
processing. It is known that one can engineer the couplings of a
one-dimensional spin chain to achieve the goal of perfect state transfer. To
leverage the value of these spin chains, a spin star is potentially useful for
connecting different parts of a quantum network. In this work, we extend the
spin-chain engineering problem to the problems with a topology of a star
network. We show that a permanently coupled spin star can function as a network
switch for transferring quantum states selectively from one node to another by
varying the local potentials only. Together with one-dimensional chains, this
result allows applications of quantum state transfer be applied to more general
quantum networks.


title: Graviton Propagator in a Covariant Massive Gravity Theory

abstract:
  We study the massive gravity theory proposed by Arkani-Hamed, Georgi and
Schwartz. In this theory, the graviton becomes massive when general covariance
is spontaneously broken through the introduction of a field that links two
metrics, one of the which will eventually decouple. The excitation of this
"link" field acts like a Goldstone boson in giving mass to the graviton. We
work out the graviton and Goldstone boson propagators explicitly by means of
gauge fixing terms similar to the renormalizability gauges used in gauge
theories. With these propagators, we calculate the lowest order tree-level
interaction between two external energy momentum tensors. The result is
independent of the gauge parameter, but different from the prediction of
massless gravity theory, i.e., general relativity. This difference remains even
if the mass of the graviton goes to zero, in which case it gives the van
Dam-Veltman-Zakharov (vDVZ) discontinuity between the propagators of a massive
and massless linearized graviton. Moreover, we show that the Fierz-Pauli
graviton mass term can be considered as the ``unitary gauge'' of a more general
theory with an extra scalar field. We explicitly construct such a theory in
which the vDVZ discontinuity arises with a graviton mass term that is different
from the Fierz-Pauli mass term. This theory has a local Weyl symmetry under
conformal transformations of the metric. In the case when the mass goes to
zero, the Weyl summetry becomes a global symmetry. It is possible that the
local Weyl symmetry will give a hint as to the form of the corresponding fully
nonlinear theory having a nonzero graviton mass.


title: The Rotor-Router Model on Regular Trees

abstract:
  The rotor-router model is a deterministic analogue of random walk. It can be
used to define a deterministic growth model analogous to internal DLA. We show
that the set of occupied sites for this model on an infinite regular tree is a
perfect ball whenever it can be, provided the initial rotor configuration is
acyclic (that is, no two neighboring vertices have rotors pointing to one
another). This is proved by defining the rotor-router group of a graph, which
we show is isomorphic to the sandpile group. We also address the question of
recurrence and transience: We give two rotor configurations on the infinite
ternary tree, one for which chips exactly alternate escaping to infinity with
returning to the origin, and one for which every chip returns to the origin.
Further, we characterize the possible "escape sequences" for the ternary tree,
that is, binary words a_1 ... a_n for which there exists a rotor configuration
so that the k-th chip escapes to infinity if and only if a_k=1.


title:
Growth and migration of solids in evolving protostellar disks I: Methods
  and Analytical tests

abstract:
  This series of papers investigates the early stages of planet formation by
modeling the evolution of the gas and solid content of protostellar disks from
the early T Tauri phase until complete dispersal of the gas. In this first
paper, I present a new set of simplified equations modeling the growth and
migration of various species of grains in a gaseous protostellar disk evolving
as a result of the combined effects of viscous accretion and photo-evaporation
from the central star. Using the assumption that the grain size distribution
function always maintains a power-law structure approximating the average
outcome of the exact coagulation/shattering equation, the model focuses on the
calculation of the growth rate of the largest grains only. The coupled
evolution equations for the maximum grain size, the surface density of the gas
and the surface density of solids are then presented and solved
self-consistently using a standard 1+1 dimensional formalism. I show that the
global evolution of solids is controlled by a leaky reservoir of small grains
at large radii, and propose an empirically derived evolution equation for the
total mass of solids, which can be used to estimate the total heavy element
retention efficiency in the planet formation paradigm. Consistency with
observation of the total mass of solids in the Minimum Solar Nebula augmented
with the mass of the Oort cloud sets strong upper limit on the initial grain
size distribution, as well as on the turbulent parameter $\alphat$. Detailed
comparisons with SED observations are presented in a following paper.


title:
Unambiguous discrimination between mixed quantum states based on
  programmable quantum state discriminators

abstract:
  We discuss the problem of designing an unambiguous programmable discriminator
for mixed quantum states. We prove that there does not exist such a universal
unambiguous programmable discriminator for mixed quantum states that has two
program registers and one data register. However, we find that we can use the
idea of programmable discriminator to unambiguously discriminate mixed quantum
states. The research shows that by using such an idea, when the success
probability for discrimination reaches the upper bound, the success probability
is better than what we do not use the idea to do, except for some special
cases.


title: Neutron stars in Einstein-aether theory

abstract:
  As current and future experiments probe strong gravitational regimes around
neutron stars and black holes, it is desirable to have theoretically sound
alternatives to general relativity against which to test observations. Here we
study the consequences of one such generalization, Einstein-aether theory, for
the properties of non-rotating neutron stars. This theory has a parameter range
that satisfies all current weak-field tests. We find that within this range it
leads to lower maximum neutron star masses, as well as larger surface redshifts
at a particular mass, for a given nuclear equation of state. For non-rotating
black holes and neutron stars, the innermost stable circular orbit is only
slightly modified in this theory.


title:
Evolution of the Fermi surface in phase fluctuating d-wave
  superconductors

abstract:
  One of the most puzzling aspects of the high $T_c$ superconductors is the
appearance of Fermi arcs in the normal state of the underdoped cuprate
materials. These are loci of low energy excitations covering part of the fermi
surface, that suddenly appear above $T_c$ instead of the nodal quasiparticles.
Based on a semiclassical theory, we argue that partial Fermi surfaces arise
naturally in a d-wave superconductor that is destroyed by thermal phase
fluctuations. Specifically, we show that the electron spectral function
develops a square root singularity at low frequencies for wave-vectors
positioned on the bare Fermi surface. We predict a temperature dependence of
the arc length that can partially account for results of recent angle resolved
photo emission (ARPES) experiments.


title: On the square root of the centre of the Hecke algebra of type A

abstract:
  In this paper we investigate non-central elements of the Iwahori-Hecke
algebra of the symmetric group whose squares are central.
  In particular, we describe a commutative subalgebra generated by certain
non-central square roots of central elements, and the generic existence of a
rank-three submodule of the Hecke algebra contained in the square root of the
centre but not in the centre. The generators for this commutative subalgebra
include the longest word and elements related to trivial and sign characters of
the Hecke algebra. We find elegant expressions for the squares of such
generators in terms of both the minimal basis of the centre and the elementary
symmetric functions of Murphy elements.


title:
Ab-initio formulation of the 4-point conductance of interacting
  electronic systems

abstract:
  We derive an expression for the 4-point conductance of a general quantum
junction in terms of the density response function. Our formulation allows us
to show that the 4-point conductance of an interacting electronic system
possessing either a geometrical constriction and/or an opaque barrier becomes
identical to the macroscopically measurable 2-point conductance. Within
time-dependent density-functional theory the formulation leads to a direct
identification of the functional form of the exchange-correlation kernel that
is important for the conductance. We demonstrate the practical implementationof
our formula for a metal-vacuum-metal interface.


title:
Dynamical 3-Space: Supernovae and the Hubble Expansion - Older Universe
  and End of Dark Energy

abstract:
  We apply the new dynamics of 3-space to cosmology by deriving a Hubble
expansion solution. This dynamics involves two constants; G and alpha - the
fine structure constant. This solution gives an excellent parameter-free fit to
the recent supernova and gamma-ray burst data without the need for `dark
energy' or `dark matter'. The data and theory together imply an older age for
the universe of some 14.7Gyrs. Various problems such as fine tuning, the event
horizon problem etc are now resolved. A brief review discusses the origin of
the 3-space dynamics and how that dynamics explained the bore hole anomaly,
spiral galaxy flat rotation speeds, the masses of black holes in spherical
galaxies, gravitational light bending and lensing, all without invoking `dark
matter' or `dark energy'. These developments imply that a new understanding of
the universe is now available.


title: Interior of Distorted Black Holes

abstract:
  We study the interior of distorted static axisymmetric black holes. We obtain
a general interior solution and study its asymptotics both near the horizon and
singularity. As a special example, we apply the obtained results to the case of
the so-called `caged' black holes.


title:
The Energy-Level Shifts of a Stationary Hydrogen Atom in Static External
  Gravitational Field with Schwarzschild Geometry

abstract:
  The first order perturbations of the energy levels of a stationary hydrogen
atom in static external gravitational field, with Schwarzschild metric, are
investigated. The energy shifts are calculated for the relativistic 1S, 2S, 2P,
3S, 3P, 3D, 4S, 4P, 4D and 4F levels. The results show that the energy-level
shifts of the states with total angular momentum quantum number 1/2 are all
zero, and the ratio of absolute energy shifts with total angular momentum
quantum number 5/2 is 1:4:5. This feature can be used to help us to distinguish
the gravitational effect from other effect.


title: Searching for Gravitational Waves from Binary Inspirals with LIGO

abstract:
  We describe the current status of the search for gravitational waves from
inspiralling compact binary systems in LIGO data. We review the result from the
first scientific run of LIGO (S1). We present the goals of the search of data
taken in the second scientific run (S2) and describe the differences between
the methods used in S1 and S2.


title: Are all Boer-Mulders functions alike?

abstract:
  Chirally odd generalized parton distributions (GPDs) and the Boer-Mulders
function provide valuable information about spin-orbit correlations for quarks
in nucleons and other hadrons. We compare results for the relevant GPD
$\bar{E}^q_T$ from a variety of phenomenological models as well as recent
lattice results. We find that $\bar{E}^q_T>0$ for nucleons as well as the pion
and for both $u$ and $d$ quark. As a result, the corresponding Boer Mulders
functions are all expected to be negative. The sign of $\bar{E}^q_T$ arises
from the relative sign between the upper and lower Dirac components for the
quark wave functions.


title: Quantum Error Correction of Observables

abstract:
  A formalism for quantum error correction based on operator algebras was
introduced in [1] via consideration of the Heisenberg picture for quantum
dynamics. The resulting theory allows for the correction of hybrid
quantum-classical information and does not require an encoded state to be
entirely in one of the corresponding subspaces or subsystems. Here, we provide
detailed proofs for the results of [1], derive a number of new results, and we
elucidate key points with expanded discussions. We also present several
examples and indicate how the theory can be extended to operator spaces and
general positive operator-valued measures.


title: QCD Approach to B->D \pi Decays and CP Violation

abstract:
  The branching ratios and CP violations of the $B\to D\pi$ decays, including
both the color-allowed and the color-suppressed modes, are investigated in
detail within QCD framework by considering all diagrams which lead to three
effective currents of two quarks. An intrinsic mass scale as a dynamical gluon
mass is introduced to treat the infrared divergence caused by the soft
collinear approximation in the endpoint regions, and the Cutkosky rule is
adopted to deal with a physical-region singularity of the on mass-shell quark
propagators. When the dynamical gluon mass $\mu_g$ is regarded as a universal
scale, it is extracted to be around $\mu_g = 440$ MeV from one of the
well-measured $B\to D\pi$ decay modes. The resulting predictions for all
branching ratios are in agreement with the current experimental measurements.
As these decays have no penguin contributions, there are no direct $CP$
asymmetries. Due to interference between the Cabibbo-suppressed and the
Cabibbo-favored amplitudes, mixing-induced CP violations are predicted in the
$B\to D^{\pm}\pi^{\mp}$ decays to be consistent with the experimental data at
1-$\sigma$ level. More precise measurements will be helpful to extract weak
angle $2\beta+\gamma$.


title: On Shalika Periods and a Theorem of Jacquet-Martin

abstract:
  Let \pi be a cuspidal automorphic representation of GL_4 with central
character \mu^2. It is known that \pi has Shalika period with respect to \mu if
and only if the L-function L^S(s, \pi, \bigwedge^2\otimes\mu^{-1}) has a pole
at s=1. Recentlt, Jacquet and Martin considered the analogous question for
cuspidal representations \pi_D of the inner form GL_2(D)(\A), and obtained a
partial result via the relative trace formula. In this paper, we provide a
complete solution to this problem via the method of theta correspondence, and
give necessary and sufficient conditions for the existence of Shalika period
for \pi_D. We also resolve the analogous question in the local setting.


title: A New Approach to Quintessence and a Solution of Multiple Attractors

abstract:
  We take a new approach to construct Quintessential models. With this
approach, we first easily obtain a tracker solution that is different from
those discovered before and straightforwardly find a solution of multiple
attractors, i.e., a solution with more than one attractor for a given set of
parameters. Then we propose a scenario of Quintessence where the field jumps
out of the scaling attractor to the de-Sitter-like attractor, by introducing a
field whose value changes a certain amount in a short time, leading to the
current acceleration. We also calculate the change the field needs for a
successful jump and suggest a possible mechanism that involves spontaneous
symmetry breaking to realize the sudden change of the field value.


title: Axiomatic theory of divergent series and cohomological equations

abstract:
  A general theory of summation of divergent series based on the
Hardy-Kolmogorov axioms is developed. A class of functional series is
investigated by means of ergodic theory. The results are formulated in terms of
solvability of some cohomological equations, all solutions to which are
nonmeasurable. In particular, this realizes a construction of a nonmeasurable
function as first conjectured by Kolmogorov.


title:
Levitation and percolation in quantum Hall systems with correlated
  disorder

abstract:
  We investigate the integer quantum Hall system in a two dimensional lattice
model with spatially correlated disorder by using the efficient method to
calculate the Chern number proposed by Fukui \textit{et al}. Distribution of
charge density indicates that the extended states at the center of each Landau
band have percolating current paths, which are topologically equivalent to the
edge states that exist in a system with boundaries. As increasing the strength
of disorder, floating feature is observed in an averaged Hall conductance as a
function of filling factor. Its relation to the observed experiments is also
discussed.


title: Composite Interstellar Grains

abstract:
  The composite grain is made up of a host silicate spheroid and graphite
inclusions. The extinction efficiencies of the composite spheroidal grains for
three axial ratios are computed using the discrete dipole approximation (DDA).
The interstellar extinction curve is evaluated in the spectral region
3.40--0.10$\mu m$ using the extinction efficiencies of the composite spheroidal
grains. The model extinction curves are then compared with the average observed
interstellar extinction curve. We also calculate the linear polarization for
the spheroidal composite grains at three orientation angles and find the
wavelength of maximum polarization. Further, we estimate the volume extinction
factor, an important parameter from the point of view of cosmic abundance, for
the composite grain models that reproduce the average observed interstellar
extinction. The estimated abundances derived from the composite grain models
for both carbon and silicon are found to be lower than that are predicted by
the bare silicate/graphite grain models but these values are still higher than
that are implied from the recent ISM values.


title: A new integral basis for the centre of the Hecke algebra of type A

abstract:
  We describe a recursive algorithm that produces an integral basis for the
centre of the Hecke algebra of type A consisting of linear combinations of
monomial symmetric polynomials of Jucys--Murphy elements. We also discuss the
existence of integral bases for the centre of the Hecke algebra that consist
solely of monomial symmetric polynomials of Jucys--Murphy elements. Finally,
for n=3, we show that only one such basis exists for the centre of the Hecke
algebra, by proving that there are exactly four bases for the centre of the
corresponding symmetric group algebra which consist solely of monomial
symmetric polynomials of Jucys--Murphy elements.


title:
Measurement of the spin polarization of the magnetic semiconductor EuS
  with zero-field and Zeeman-split Andreev reflection spectroscopy

abstract:
  We report measurements of the spin polarization (\textbf{\textit{P}}) of the
concentrated magnetic semiconductor EuS using both zero-field and Zeeman-split
Andreev reflection spectroscopy (ARS) with EuS/Al planar junctions. The
zero-field ARS spectra are well described by the modified (spin-polarized) BTK
model with expected superconducting energy gap and actual measurement
temperature (no additional spectral broadening). The fittings consistently
yield \textbf{\textit{P}} close to 80% regardless of the barrier strength.
Moreover, we performed ARS in the presence of a Zeeman-splitting of the
quasiparticle density of states in Al. To describe the Zeeman-split ARS
spectra, we develop a theoretical model which incorporates the solution to the
Maki-Fulde equations into the modified BTK analysis. The method enables the
determination of the magnitude as well as the sign of \textbf{\textit{P}} with
ARS, and the results are consistent with those from the zero-field ARS. The
experiments extend the utility of field-split superconducting spectroscopy from
tunnel junctions to Andreev junctions of arbitrary barrier strengths.


title:
Wireless Networking to Support Data and Voice Communication Using Spread
  Spectrum Technology in The Physical Layer

abstract:
  Wireless networking is rapidly growing and becomes an inexpensive technology
which allows multiple users to simultaneously access the network and the
internet while roaming about the campus. In the present work, the software
development of a wireless LAN(WLAN) is highlighted. This WLAN utilizes direct
sequence spread spectrum (DSSS) technology at 902MHz RF carrier frequency in
its physical layer. Cost effective installation and antijaming property of
spread spectrum technology are the major advantages of this work.


title: The standard model on a domain-wall brane?

abstract:
  We propose a 4+1-dimensional action that is a candidate for realising a
standard-model-like effective theory for fields dynamically localised to a
domain-wall brane. Our construction is based in part on the conjecture that the
Dvali-Shifman mechanism for dynamically localising gauge bosons works correctly
in 4+1-d. Assuming this to be so, we require the gauge symmetry to be SU(5)in
the bulk, spontaneously breaking to SU(3)xSU(2)xU(1) inside the domain wall,
thus dynamically localising the standard model gauge bosons provided that the
SU(5) theory in the bulk exhibits confinement. The wall is created jointly by a
real singlet-Higgs field eta configured as a kink, and an SU(5) adjoint-Higgs
field chi that takes nonzero values inside the wall. Chiral 3+1-dimensional
quarks and leptons are confined and split along the bulk direction via their
Yukawa couplings to eta and chi. The Higgs doublet and its colour triplet SU(5)
partner are similarly localised and split. The splittings suppress
coloured-Higgs-induced proton decay and, because of the different localisation
profiles, the usual SU(5) mass relation m_e = m_d does not arise. Localised
gravity is generated via the Randall-Sundrum alternative to compactification.


title:
HMM Speaker Identification Using Linear and Non-linear Merging
  Techniques

abstract:
  Speaker identification is a powerful, non-invasive and in-expensive biometric
technique. The recognition accuracy, however, deteriorates when noise levels
affect a specific band of frequency. In this paper, we present a sub-band based
speaker identification that intends to improve the live testing performance.
Each frequency sub-band is processed and classified independently. We also
compare the linear and non-linear merging techniques for the sub-bands
recognizer. Support vector machines and Gaussian Mixture models are the
non-linear merging techniques that are investigated. Results showed that the
sub-band based method used with linear merging techniques enormously improved
the performance of the speaker identification over the performance of wide-band
recognizers when tested live. A live testing improvement of 9.78% was achieved


title: Spacetime Emergence in the Robertson-Walker Universe from a Matrix model

abstract:
  Using a novel, string theory-inspired formalism based on a Hamiltonian
constraint, we obtain a conformal mechanical system for the spatially flat
four-dimensional Robertson-Walker Universe. Depending on parameter choices,
this system describes either a relativistic particle in the Robertson-Walker
background, or metric fluctuations of the Robertson-Walker geometry. Moreover
we derive a tree-level M-theory matrix model in this time-dependent background.
Imposing the Hamiltonian constraint forces the spacetime geometry to be fuzzy
near the big bang, while the classical Robertson-Walker geometry emerges as the
Universe expands. From our approach we also derive the temperature of the
Universe interpolating between the radiation and matter dominated eras.


title:
Mueller's Exchange-Correlation Energy in Density-Matrix-Functional
  Theory

abstract:
  The increasing interest in the Mueller density-matrix-functional theory has
led us to a systematic mathematical investigation of its properties. This
functional is similar to the Hartree-Fock functional, but with a modified
exchange term in which the square of the density matrix \gamma(X, X') is
replaced by the square of \gamma^{1/2}(X, X'). After an extensive introductory
discussion of density-matrix-functional theory we show, among other things,
that this functional is convex (unlike the HF functional) and that energy
minimizing \gamma's have unique densities \rho(x), which is a physically
desirable property often absent in HF theory. We show that minimizers exist if
N \leq Z, and derive various properties of the minimal energy and the
corresponding minimizers. We also give a precise statement about the equation
for the orbitals of \gamma, which is more complex than for HF theory. We state
some open mathematical questions about the theory together with conjectured
solutions.

categories: cond-mat.str-el cond-mat.mtrl-sci math-ph math.MP


title: Mean Field Spin Glass in the Observable Representation

abstract:
  The state space for the $N$-spin mean field (SK) spin glass--nominally an
$N$-cube--is embedded in a low dimensional continuous space in such a way that
metastable and stable phases can easily be discerned, a concept of nearness of
configurations defined, and peaks in the Parisi $q$-parameter overlap
distribution identified. The dynamical and partly hierarchical interrelation of
these phases can be directly imaged.


title:
Characteristic Scales of Baryon Acoustic Oscillations from Perturbation
  Theory: Non-linearity and Redshift-Space Distortion Effects

abstract:
  An acoustic oscillation of the primeval photon-baryon fluid around the
decoupling time imprints a characteristic scale in the galaxy distribution
today, known as the baryon acoustic oscillation (BAO) scale. Several on-going
and/or future galaxy surveys aim at detecting and precisely determining the BAO
scale so as to trace the expansion history of the universe. We consider
nonlinear and redshift-space distortion effects on the shifts of the BAO scale
in $k$-space using perturbation theory. The resulting shifts are indeed
sensitive to different choices of the definition of the BAO scale, which needs
to be kept in mind in the data analysis. We present a toy model to explain the
physical behavior of the shifts. We find that the BAO scale defined as in
Percival et al. (2007) indeed shows very small shifts ($\lesssim$ 1%) relative
to the prediction in {\it linear theory} in real space. The shifts can be
predicted accurately for scales where the perturbation theory is reliable.


title: Flavoured Leptogenesis

abstract:
  Thermal leptogenesis, in the seesaw model, is a popular mechanism for
generating the Baryon Asymmetry of the Universe. It was noticed recently, that
including lepton flavour can modify significantly the results. These
proceedings aim to discuss why and when flavour matters, in the thermal
leptogenesis scenario for hierarchical right-handed neutrinos. No Boltzmann
Equations are introduced.


title:
Thermal photon to dilepton ratio in ultra-relativistic heavy ion
  collisions

abstract:
  The ratio of transverse momentum distribution of thermal photons to dilepton
has been evaluated. It is observed that this ratio reaches a plateau beyond a
certain value of transverse momentum. We argue that this ratio can be used to
estimate the initial temperature of the system by selecting the transverse
momentum and invariance mass windows judiciously. It is demonstrated that if
the radial flow is large then the plateau disappear and hence a deviation from
the plateau can be used as an indicator of large radial flow. The sensitivity
of the results on various input parameters has been studied.


title: Cepheid Parallaxes and the Hubble Constant

abstract:
  Revised Hipparcos parallaxes for classical Cepheids are analysed together
with 10 HST-based parallaxes (Benedict et al.). In a reddening-free V,I
relation we find that the coefficient of logP is the same within the
uncertainties in our Galaxy as in the LMC, contrary to some previous
suggestions. Cepheids in the inner region of NGC4258 with near solar
metallicities (Macri et al.) confirm this result. We obtain a zero-point for
the reddening-free relation and apply it to Cepheids in galaxies used by
Sandage et al. to calibrate the absolute magnitudes of SNIa and to derive the
Hubble constant. We revise their result from 62 to 70+/-5 km/s/Mpc. The
Freedman et al. 2001 value is revised from 72 to 76+/-8 km/s/Mpc. These results
are insensitive to Cepheid metallicity corrections. The Cepheids in the inner
region of NGC4258 yield a modulus of 29.22+/-0.03(int) compared with a
maser-based modulus of 29.29+/-0.15. Distance moduli for the LMC, uncorrected
for any metallicity effects, are; 18.52+/-0.03 from a reddening-free relation
in V,I; 18.47+/-0.03 from a period-luminosity relation at K; 18.45+/-0.04 from
a period-luminosity-colour relation in J,K. Adopting a metallicity correction
in V,I from Marci et al. leads to a true LMC modulus of 18.39+/-0.05.


title:
Electrical transport and optical studies of ferromagnetic Cobalt doped
  ZnO nanoparticles exhibiting a metal-insulator transition

abstract:
  The observed correlation of oxygen vacancies and room temperature
ferromagnetic ordering in Co doped ZnO1-o nanoparticles reported earlier (Naeem
et al Nanotechnology 17, 2675-2680) has been further explored by transport and
optical measurements. In these particles room temperature ferromagnetic
ordering had been observed to occur only after annealing in forming gas. In the
current work the optical properties have been studied by diffuse reflection
spectroscopy in the UV-Vis region and the band gap of the Co doped compositions
has been found to decrease with Co addition. Reflections minima are observed at
the energies characteristic of Co+2 d-d (tethrahedral symmetry) crystal field
transitions, further establishing the presence of Co in substitutional sites.
Electrical transport measurements on palletized samples of the nanoparticles
show that the effect of a forming gas is to strongly decrease the resistivity
with increasing Co concentration. For the air annealed and non-ferromagnetic
samples the variation in the resistivity as a function of Co content are
opposite to those observed in the particles prepared in forming gas. The
ferromagnetic samples exhibit an apparent change from insulator to metal with
increasing temperatures for T>380K and this change becomes more pronounced with
increasing Co content. The magnetic and resistive behaviors are correlated by
considering the model by Calderon et al [M. J. Calderon and S. D. Sarma, Annals
of Physics 2007 (Accepted doi: 10.1016/j.aop.2007.01.010] where the
ferromagnetism changes from being mediated by polarons in the low temperature
insulating region to being mediated by the carriers released from the weakly
bound states in the higher temperature metallic region.


title:
Measurement of the top-quark mass using missing $E_T$+jets events with
  secondary vertex $b$-tagging at CDF II

abstract:
  We present a measurement of the top-quark mass in $p\bar p$ collisions at
\hbox{$\sqrt{s}=1.96$} TeV which uses events with an inclusive signature of
missing transverse energy and jets. % The event selection is sensitive to
$t\bar t\to W^+bW^-\bar b\to l\nu b q q^\prime \bar b$ independent of the
lepton flavor, and results in a large acceptance for $W\to\tau\nu$ decays. %
All-hadronic $t\bar t$ decays and events with identified electrons or muons are
vetoed to provide a statistically independent sample with respect to all
previous measurements. % The top-quark mass is inferred from the distribution
of the scalar sum of all jet transverse energies and the missing transverse
energy. Using 311 pb$^{-1}$ of integrated luminosity recorded by the Collider
Detector at Fermilab, we measure a top-quark mass $m_t = 172.3
^{+10.8}_{-9.6}$(stat.)$\pm 10.8$(syst.) GeV/$c^2$. While the uncertainty on
$m_t$ is larger than that of other measurements, the result is statistically
uncorrelated with those of other methods, and thus can help to reduce the
overall $m_t$ uncertainty when combined with other existing measurements.


title: Bauer-Furuta invariants under Z_2-actions

abstract:
  S.Bauer and M.Furuta defined a stable cohomotopy refinement of the
Seiberg-Witten invariants. In this paper, we prove a vanishing theorem of
Bauer-Furuta invariants for 4-manifolds with smooth Z/2-actions. As an
application, we give a constraint on smooth Z/2-actions on homotopy K3#K3, and
construct a nonsmoothable locally linear Z/2-action on K3#K3. We also construct
a nonsmoothable locally linear Z/2-action on $K3$.


title: Gluon shadowing in the Glauber-Gribov model at HERA

abstract:
  We calculate shadowing using new data on the gluon density of the Pomeron
recently measured with high precision at HERA. The calculations are made in a
Glauber-Gribov framework and Pomeron tree-diagrams are summed up within a
unitarity-conserving procedure. The total cross section of $\vphot A$
interaction is then found in a parameter-free description, employing gluon
diffractive and inclusive distribution functions as input. A strong shadowing
effect is obtained, in good agreement with several other models. Impact
parameter dependence of gluon shadowing is also presented.


title:
Weight 2 blocks of general linear groups and modular Alvis-Curtis
  duality

abstract:
  We obtain the structure of weight 2 blocks and [2:1]-pairs of q-Schur
algebras, and compute explicitly the modular Alvis-Curtis duality for weight 2
blocks of finite general linear groups in non-defining characteristic.


title:
Application of Girsanov Theorem to Particle Filtering of Discretely
  Observed Continuous-Time Non-Linear Systems

abstract:
  This article considers the application of particle filtering to
continuous-discrete optimal filtering problems, where the system model is a
stochastic differential equation, and noisy measurements of the system are
obtained at discrete instances of time. It is shown how the Girsanov theorem
can be used for evaluating the likelihood ratios needed in importance sampling.
It is also shown how the methodology can be applied to a class of models, where
the driving noise process is lower in the dimensionality than the state and
thus the laws of state and noise are not absolutely continuous.
Rao-Blackwellization of conditionally Gaussian models and unknown static
parameter models is also considered.


title: Is There a Universal Mass Function?

abstract:
  Following an old idea of Fritz Zwicky, we make an attempt to establish a
universal mass function for astronomical objects on all scales. The object
classes considered are: solar system planets and small bodies, exoplanets,
brown dwarfs, stars and stellar remnants, open and globular clusters, molecular
clouds, galaxies, groups and clusters of galaxies. For comparison we also
include CDM halos taken from numerical simulations. We show that the mass
functions of individual object classes, when properly normalized, can indeed be
concatenated to build a surprisingly continuous mass function of the universe,
from approximately M = 10^(-20)Msun (sub-kilometer size asteroids) up to M =
10^(16)Msun (rich clusters of galaxies), covering 36 orders of magnitude in
mass. Most individual mass functions roughly follow a power law of the form
phi(M) propto M^(-2). A notable exception are planets and small bodies which
seem to obey a flatter distribution. CDM halos from high-resolution numerical
simulations show a very similar relation, again of universal slope -2, from
clusters of galaxies all the way down to the planetary mass scale. On the scale
of stars and star clusters this is a remarkable coincidence, as the formation
processes involved are thought to be totally different (bottom-up gravitational
clustering of DM halos versus top-down gravoturbulent fragmentation of gas
clouds).


title:
A mathematical criterion for single photon sources used in quantum
  cryptography

abstract:
  A single photon source (SPS) is very important for quantum computation. In
particular, it is essential for secured quantum cryptography. But there is no
perfect SPS in reality. Therefore, probabilistic SPS where probability of
simultaneous emission of two, three, four and more photon is less than the
emission of a single photon are used. Since classical photon always comes in
bunch, the required single photon source must be nonclassical. In the
well-known antibunched state the rate of simultaneous emission of two photon is
less than that of single photon. But the requirement of quantum cryptography is
a multiphoton version of the antibunched state or the higher order antibunched
state. Recently we have reported a mathematical criterion for higher order
antibunching. Here we have shown that any proposal for SPS to be used in
quantum cryptography should satisfy this criterion. We have studied four wave
mixing as a possible candidate of single photon source.


title: Proof of the Double Bubble Conjecture in R^n

abstract:
  The least-area hypersurface enclosing and separating two given volumes in R^n
is the standard double bubble.


title:
Localized Superconductivity in the Quantum-Critical Region of the
  Disorder-Driven Superconductor-Insulator Transition in TiN Thin Films

abstract:
  We investigate low-temperature transport properties of thin TiN
superconducting films in the vicinity of the disorder-driven
superconductor-insulator transition. In a zero magnetic field, we find an
extremely sharp separation between superconducting and insulating phases,
evidencing a direct superconductor-insulator transition without an intermediate
metallic phase. At moderate temperatures, in the insulating films we reveal
thermally activated conductivity with the magnetic field-dependent activation
energy. At very low temperatures, we observe a zero-conductivity state, which
is destroyed at some depinning threshold voltage V_T. These findings indicate
formation of a distinct collective state of the localized Cooper pairs in the
critical region at both sides of the transition.


title: Neutron-proton mass difference in isospin asymmetric nuclear matter

abstract:
  Isospin-breaking effects in the baryonic sector are studied in the framework
of a medium-modified Skyrme model. The neutron-proton mass difference in
infinite, asymmetric nuclear matter is discussed. In order to describe the
influence of the nuclear environment on the skyrmions, we include
energy-dependent charged and neutral pion optical potentials in the s- and
p-wave channels. The present approach predicts that the neutron-proton mass
difference is mainly dictated by its strong part and that it strongly decreases
in neutron matter.


title:
Accurate long-range coefficients for two excited like isotope He atoms:
  He($2 ^1P$)--He($2 ^1P$), He($2 ^1P$)--He($2 ^3P$), and He($2 ^3P$)--He($2
  ^3P$)

abstract:
  A general formalism is used to express the long-range potential energies in
inverse powers of the separation distance between two like atomic or molecular
systems with $P$ symmetries. The long-range molecular interaction coefficients
are calculated for the molecular symmetries $\Delta$, $\Pi$, and $\Sigma$,
arising from the following interactions: He($2 ^1P$)--He($2 ^1P$), He($2
^1P$)--He($2 ^3P$), and He($2 ^3P$)--He($2 ^3P$). The electric
quadrupole-quadrupole term, $C_{5}$, the van der Waals (dispersion) term
$C_{6}$, and higher-order terms, $C_{8}$, and $C_{10}$, are calculated
\textit{ab initio} using accurate variational wave functions in Hylleraas
coordinates with finite nuclear mass effects. A comparison is made with
previously published results where available.


title:
Discovery of two candidate pulsar wind nebulae in very-high-energy gamma
  rays

abstract:
  We present the discovery of two very-high-energy gamma-ray sources in an
ongoing systematic search for emission above 100 GeV from pulsar wind nebulae
in survey data from the H.E.S.S. telescope array. Imaging Atmospheric Cherenkov
Telescopes are ideal tools for searching for extended emission from pulsar wind
nebulae in the very-high-energy regime. H.E.S.S., with its large field of view
of 5 degrees and high sensitivity, gives new prospects for the search for these
objects. An ongoing systematic search for very-high-energy emission from
energetic pulsars over the region of the Galactic plane between -60 degrees < l
< 30 degrees, -2 degrees < b < 2 degrees is performed. For the resulting
candidates, the standard H.E.S.S. analysis was applied and a search for
multi-wavelength counterparts was performed. We present the discovery of two
new candidate gamma-ray pulsar wind nebulae, HESS J1718-385 and HESS J1809-193.
H.E.S.S. has proven to be a suitable instrument for pulsar wind nebula
searches.


title: Microscale swimming: The molecular dynamics approach

abstract:
  The self-propelled motion of microscopic bodies immersed in a fluid medium is
studied using molecular dynamics simulation. The advantage of the atomistic
approach is that the detailed level of description allows complete freedom in
specifying the swimmer design and its coupling with the surrounding fluid. A
series of two-dimensional swimming bodies employing a variety of propulsion
mechanisms -- motivated by biological and microrobotic designs -- is
investigated, including the use of moving limbs, changing body shapes and fluid
jets. The swimming efficiency and the nature of the induced, time-dependent
flow fields are found to differ widely among body designs and propulsion
mechanisms.


title: Topological delocalization of two-dimensional massless Dirac fermions

abstract:
  The beta function of a two-dimensional massless Dirac Hamiltonian subject to
a random scalar potential, which e.g., underlies the theoretical description of
graphene, is computed numerically. Although it belongs to, from a symmetry
standpoint, the two-dimensional symplectic class, the beta function
monotonically increases with decreasing $g$. We also provide an argument based
on the spectral flows under twisting boundary conditions, which shows that none
of states of the massless Dirac Hamiltonian can be localized.


title:
Quantum transport on small-world networks: A continuous-time quantum
  walk approach

abstract:
  We consider the quantum mechanical transport of (coherent) excitons on
small-world networks (SWN). The SWN are build from a one-dimensional ring of N
nodes by randomly introducing B additional bonds between them. The exciton
dynamics is modeled by continuous-time quantum walks and we evaluate
numerically the ensemble averaged transition probability to reach any node of
the network from the initially excited one. For sufficiently large B we find
that the quantum mechanical transport through the SWN is, first, very fast,
given that the limiting value of the transition probability is reached very
quickly; second, that the transport does not lead to equipartition, given that
on average the exciton is most likely to be found at the initial node.


title: Perturbations of quadratic centers of genus one

abstract:
  We propose a program for finding the cyclicity of period annuli of quadratic
systems with centers of genus one. As a first step, we classify all such
systems and determine the essential one-parameter quadratic perturbations which
produce the maximal number of limit cycles. We compute the associated
Poincare-Pontryagin-Melnikov functions whose zeros control the number of limit
cycles. To illustrate our approach, we determine the cyclicity of the annuli of
two particular reversible systems.


title:
Estimates of the topological entropy from below for continuous self-maps
  on some compact manifolds

abstract:
  Extending our results in "Entropy conjecture for continuous maps of
nilmanifolds", to appear in Israel Jour. of Math., we confirm that Entropy
Conjecture holds for every continuous self-map of a compact $K(\pi,1)$ manifold
with the fundamental group $\pi$ torsion free and virtually nilpotent, in
particular for every continuous map of an infra-nilmanifold. In fact we prove a
stronger version, a lower estimate of the topological entropy of a map by
logarithm of the spectral radius of an associated "linearization matrix" with
integer entries.
  From this, referring to known estimates of Mahler measure of polynomials, we
deduce some absolute lower bounds for the entropy.


title:
Bosonization study of quantum phase transitions in the one-dimensional
  asymmetric Hubbard model

abstract:
  The quantum phase transitions in the one-dimensional asymmetric Hubbard model
are investigated with the bosonization approach. The conditions for the phase
transition from density wave to phase separation, the correlation functions and
their exponents are obtained analytically. Our results show that the difference
between the hopping integrals for up- and down-spin electrons is crucial for
the happening of the phase separation. When the difference is large enough, the
phase separation will appear even if the on-site interaction is small.


title:
A Class of LDPC Erasure Distributions with Closed-Form Threshold
  Expression

abstract:
  In this paper, a family of low-density parity-check (LDPC) degree
distributions, whose decoding threshold on the binary erasure channel (BEC)
admits a simple closed form, is presented. These degree distributions are a
subset of the check regular distributions (i.e. all the check nodes have the
same degree), and are referred to as $p$-positive distributions. It is given
proof that the threshold for a $p$-positive distribution is simply expressed by
$[\lambda'(0)\rho'(1)]^{-1}$. Besides this closed form threshold expression,
the $p$-positive distributions exhibit three additional properties. First, for
given code rate, check degree and maximum variable degree, they are in some
cases characterized by a threshold which is extremely close to that of the best
known check regular distributions, under the same set of constraints. Second,
the threshold optimization problem within the $p$-positive class can be solved
in some cases with analytic methods, without using any numerical optimization
tool. Third, these distributions can achieve the BEC capacity. The last
property is shown by proving that the well-known binomial degree distributions
belong to the $p$-positive family.


title: Determining full conditional independence by low-order conditioning

abstract:
  A concentration graph associated with a random vector is an undirected graph
where each vertex corresponds to one random variable in the vector. The absence
of an edge between any pair of vertices (or variables) is equivalent to full
conditional independence between these two variables given all the other
variables. In the multivariate Gaussian case, the absence of an edge
corresponds to a zero coefficient in the precision matrix, which is the inverse
of the covariance matrix. It is well known that this concentration graph
represents some of the conditional independencies in the distribution of the
associated random vector. These conditional independencies correspond to the
"separations" or absence of edges in that graph. In this paper we assume that
there are no other independencies present in the probability distribution than
those represented by the graph. This property is called the perfect
Markovianity of the probability distribution with respect to the associated
concentration graph. We prove in this paper that this particular concentration
graph, the one associated with a perfect Markov distribution, can be determined
by only conditioning on a limited number of variables. We demonstrate that this
number is equal to the maximum size of the minimal separators in the
concentration graph.


title: Boundary Harnack inequalities for regional fractional Laplacian

abstract:
  We consider boundary Harnack inequalities for regional fractional Laplacian
which are generators of censored stable-like processes on G taking
\kappa(x,y)/|x-y|^{n+\alpha}dxdy, x,y\in G as the jumping measure. When G is a
C^{1,\beta-1} open set, 1<\alpha<\beta\leq 2 and \kappa\in
C^{1}(\overline{G}\times \overline{G}) bounded between two positive numbers, we
prove a boundary Harnack inequality giving dist(x,\partial G)^{\alpha-1} order
decay for harmonic functions near the boundary. For a C^{1,\beta-1} open set
D\subset \overline{D}\subset G, 0<\alpha\leq (1\vee\alpha)<\beta\leq 2, we
prove a boundary Harnack inequality giving dist(x,\partial D)^{\alpha/2} order
decay for harmonic functions near the boundary. These inequalities are
generalizations of the known results for the homogeneous case on C^{1,1} open
sets. We also prove the boundary Harnack inequality for regional fractional
Laplacian on Lipschitz domain.


title: Searching for non Gaussian signals in the BOOMERanG 2003 CMB maps

abstract:
  We analyze the BOOMERanG 2003 (B03) 145 GHz temperature map to constrain the
amplitude of a non Gaussian, primordial contribution to CMB fluctuations. We
perform a pixel space analysis restricted to a portion of the map chosen in
view of high sensitivity, very low foreground contamination and tight control
of systematic effects. We set up an estimator based on the three Minkowski
functionals which relies on high quality simulated data, including non Gaussian
CMB maps. We find good agreement with the Gaussian hypothesis and derive the
first limits based on BOOMERanG data for the non linear coupling parameter f_NL
as -300<f_NL<650 at 68% CL and -800<f_NL<1050 at 95% CL.


title:
Non-Markovian dynamics in atom-laser outcoupling from a double-well
  Bose-Einstein condensate

abstract:
  We investigate the dynamics of a continuous atom laser based on the merging
of independently formed atomic condensates. In a first attempt to understand
the dynamics of the system, we consider two independent elongated Bose-Einstein
condensates which approach each other and focus on intermediate inter-trap
distances so that a two-mode model is well justified. In the framework of a
mean-field theory, we discuss the quasi steady-state population of the traps as
well as the energy distribution of the outcoupled atoms.


title: Non-Computability of Consciousness

abstract:
  With the great success in simulating many intelligent behaviors using
computing devices, there has been an ongoing debate whether all conscious
activities are computational processes. In this paper, the answer to this
question is shown to be no. A certain phenomenon of consciousness is
demonstrated to be fully represented as a computational process using a quantum
computer. Based on the computability criterion discussed with Turing machines,
the model constructed is shown to necessarily involve a non-computable element.
The concept that this is solely a quantum effect and does not work for a
classical case is also discussed.


title: Finite Just Non-Dedekind Groups

abstract:
  A group is just non-Dedekind (JND) if it is not a Dedekind group but all of
whose proper homomorphic images are Dedekind groups. The aim of the paper is to
classify finite JND-groups.


title:
Non-Abelian states with negative flux: a new series of quantum Hall
  states

abstract:
  By applying the idea of parafermionic clustering to composite bosons with
positive as well as negative flux, a new series of trial wavefunctions to
describe fractional quantum Hall states is proposed. These non-Abelian states
compete at filling factors k/(3k +/- 2) with other ground states like stripes
or composite fermion states. These two series contain all the states recently
discovered by Pan et al. [Phys. Rev. Lett. 90, 016801 (2003)] including the
even denominator cases. Exact diagonalization studies on the sphere and torus
point to their possible relevance for filling factors 3/7, 3/11, and 3/8.


title:
Comment on "Structure factors of harmonic and anharmonic Fibonacci
  chains by molecular dynamics simulations"

abstract:
  Recently, Engel et al. discussed phonon broadening as observed in 3D
quasicrystals on the basis of calculations on the Fibonacci chain. We show that
the paper contains several statements and assumptions that are contradicted by
factual truth.


title: The Spreading Layer of GX 9+9

abstract:
  The spreading layer (SL) on neutron star surface of GX 9+9 during the upper
banana state was studied using INTEGRAL and RXTE observations. The SL-area
becomes larger with increasing accretion rate while the SL-temperature remains
close to the critical Eddington value, confirming predictions by Inogamov and
Sunyaev (1999) and Suleimanov and Poutanen (2006). However, at low accretion
rate the observed temperature is higher and SL-belt shallower than those
predicted, requiring confirmation and theoretical explananation.


title: Triaxial Analytical Potential-Density Pairs for Galaxies

abstract:
  We present two triaxial analytical potential-density pairs that can be viewed
as generalized versions of the axisymmetric Miyamoto and Nagai and Satoh
galactic models. These potential-density pairs may be useful models for
galaxies with box-shaped bulges. The resulting mass density distributions are
everywhere non-negative and free from singularities. Also, a few numerically
calculated orbits for the Miyamoto and Nagai-like triaxial potential are
presented.


title:
A simple model for predicting crystallization and melting temperatures,
  and its implications for phase transitions in confined volumes

abstract:
  We present a simple unifying model for crystallization and melting
temperatures by showing that homogeneous nucleation and phase transformations
driven by thickening of pre-existing surface layers are limiting conditions of
the more general heterogeneous nucleation case. Furthermore, to a first
approximation all these processes can be described by an extended classical
nucleation theory. The model can also be applied to phase transition
temperatures in confined volumes, provided reliable values for the interfacial
tensions within the systems are determinable. The expected melting and
crystallization temperature for any transformation pathway can then be
predicted.


title: Searching for New Physics in b to s Hadronic Penguin Decays

abstract:
  We review the theoretical status of b to s hadronic penguin decays in the
Standard Model and beyond. We summarize the main theoretical tools to compute
Branching Ratios and CP asymmetries for b to s penguin dominated nonleptonic
decays, and discuss the theoretical uncertainties in the prediction of
time-dependent CP asymmetries in this processes. We consider general aspects of
b to s transitions beyond the Standard Model. Then we present detailed
predictions in supersymmetric models with new sources of flavor and CP
violation.


title:
Thermal Stability of Metallic Single-Walled Carbon Nanotubes: An O(N)
  Tight-Binding Molecular Dynamics Simulation Study

abstract:
  Order(N) Tight-Binding Molecular Dynamics (TBMD) simulations are performed to
investigate the thermal stability of (10,10) metallic Single-Walled Carbon
Nanotubes (SWCNT). Periodic boundary conditions (PBC) are applied in axial
direction. Velocity Verlet algorithm along with the canonical ensemble
molecular dynamics (NVT) is used to simulate the tubes at the targeted
temperatures. The effects of slow and rapid temperature increases on the
physical characteristics, structural stability and the energetics of the tube
are investigated and compared. Simulations are carried out starting from room
temperature and the temperature is raised in steps of 300K. Stability of the
simulated metallic SWCNT is examined at each step before it is heated to higher
temperatures. First indication of structural deformation is observed at 600K.
For higher heat treatments the deformations are more pronounced and the bond
breaking temperature is reached around 2500K. Gradual (slow) heating and
thermal equilibrium (fast heating) methods give the value of radial thermal
expansion coefficient in the temperature range between 300K-600K as
0.31x10^{-5}(1/K) and 0.089x10^{-5}(1/K), respectively. After 600K, both
methods give the same value of 0.089x10^{-5}(1/K). The ratio of the total
energy per atom with respect to temperature is found to be 3x10^{-4} eV/K.


title:
Phase analysis of the cosmic microwave background from an incomplete sky
  coverage

abstract:
  Phases of the spherical harmonic analysis of full-sky cosmic microwave
background (CMB) temperature data contain useful information complementary to
the ubiquitous angular power spectrum. In this letter we present a new method
of phase analysis on incomplete sky maps. It is based on Fourier phases of
equal-latitude pixel rings of the map, which are related to the mean angle of
the trigonometric moments from the full-sky phases. They have an advantage for
probing regions of interest without tapping polluted Galactic plane area, and
can localize non-Gaussian features and departure from statistical isotropy in
the CMB.


title: Nonlinear coherent destruction of tunneling

abstract:
  We study theoretically two coupled periodically-curved optical waveguides
with Kerr nonlinearity. We find that the tunneling between the waveguides can
be suppressed in a wide range of parameters due to nonlinearity. Such
suppression of tunneling is different from the coherent destruction of
tunneling in a linear medium, which occurs only at the isolated degeneracy
point of the quasienergies. We call this novel suppression nonlinear coherent
destruction of tunneling.


title: The Plasma Emission Model of RX J1856.5-3754

abstract:
  A spectral analysis of the nearby isolated neutron star RX J1856.5-3754 is
presented. Applying the kinetic approach, the distribution functions of
emitting electrons are derived and the entire spectra is fitted. It is found
that waves excited by the cyclotron mechanism, come in the radio domain. We
confirm that the cyclotron instability is quite efficient, since the
estimations show that the time of wave-particle interaction is long enough for
particles to acquire perpendicular momentum and generate observed radiation.
The lack of rotational modulation is discussed and the pulsar spin period is
estimated.


title: Lie antialgebras: premices

abstract:
  The main purpose of this work is to develop the basic notions of the Lie
theory for commutative algebras. We introduce a class of $\mathbbZ_2$-graded
commutative but not associative algebras that we call ``Lie antialgebras''.
These algebras are closely related to Lie (super)algebras and, in some sense,
link together commutative and Lie algebras. The main notions we define in this
paper are: representations of Lie antialgebras, an analog of the Lie-Poisson
bivector (which is not Poisson) and central extensions. We also classify simple
finite-dimensional Lie antialgebras.


title: A coarse graining for the Fortuin-Kasteleyn measure in random media

abstract:
  By means of a multi-scale analysis we describe the typical geometrical
structure of the clusters under the FK measure in random media. Our result
holds in any dimension greater or equal to 2 provided that slab percolation
occurs under the averaged measure, which should be the case in the whole
supercritical phase. This work extends the one of Pisztora and provides an
essential tool for the analysis of the supercritical regime in disordered FK
models and in the corresponding disordered Ising and Potts models.


title:
Transverse magnetization and transient oscillations in the quantum
  tunneling of molecular magnets

abstract:
  We calculate the response of a molecular magnet subject to a time-varying
magnetic field and coupled to a heat bath. We propose that observations of
calculated oscillations transverse to the field direction may be an effective
way of demonstrating quantum tunneling and thus probing the details of level
repulsion. The effective model of a triangle of Heisenberg spins and weak
anisotropies, as has been used to model the molecular magnets V15 and Cu3, is
used to illustrate this.


title: Circularly polarized waves in a plasma with vacuum polarization effects

abstract:
  The theory for large amplitude circularly polarized waves propagating along
an external magnetic field is extended in order to include also vacuum
polarization effects. A general dispersion relation, which unites previous
results, is derived.


title:
The baryon density at z=0.9-1.9 - Tracing the warm-hot intergalactic
  medium with broad Lyman alpha absorption

abstract:
  We present an analysis of the Lyman alpha forests of five quasar spectra in
the near UV. Properties of the intergalactic medium (IGM) at an intermediate
redshift interval (0.9 < z < 1.9) are studied. The amount of baryons in the
diffuse photoionised IGM and the warm-hot intergalactic medium (WHIM) are
traced to get constraints on the redshift evolution of the different phases of
the intergalactic gas. The baryon density of the diffuse IGM is determined with
photoionisation calculations under the assumption of local hydrostatic
equilibrium. We assume that the gas is ionised by a metagalactic background
radiation with a Haardt & Madau (2001) spectrum. The WHIM is traced with broad
Lyman alpha (BLA) absorption. The properties of a number of BLA detections are
studied. Under the assumption of collisional ionisation equilibrium a lower
limit to the baryon density could be estimated. It is found that the diffuse
photoionised IGM contains at least 25% of the total baryonic matter at
redshifts 1 < z < 2. For the WHIM a lower limit of 2.4% could be determined.
Furthermore the data indicates that the intergalactic gas is in a state of
evolution at z=1.5. We confirm that a considerable part of the WHIM is created
between z=1 and z=2.


title:
Relativistic BCS-BEC Crossover at Finite Temperature and Its Application
  to Color Superconductivity

abstract:
  The non-relativistic $G_0 G$ formalism of BCS-BEC crossover at finite
temperature is extended to relativistic fermion systems. The uncondensed pairs
contribute a pseudogap to the fermion excitations. The theory recovers the BCS
mean field approximation at zero temperature and the non-relativistic results
in a proper limit. For massive fermions, when the coupling strength increases,
there exist two crossovers from the weak coupling BCS superfluid to the
non-relativistic BEC state and then to the relativistic BEC state. For color
superconductivity at moderate baryon density, the matter is in the BCS-BEC
crossover region, and the behavior of the pseudogap is quite similar to that
found in high temperature superconductors.

categories: hep-ph astro-ph cond-mat.supr-con nucl-th


title:
Formation of hydrogen impurity states in silicon and insulators at low
  implantation energies

abstract:
  The formation of hydrogen-like muonium (Mu) has been studied as a function of
implantation energy in intrinsic Si, thin films of condensed van der Waals
gases (N2, Ne, Ar, Xe), fused and crystalline quartz and sapphire. By varying
the initial energy of positive muons (mu+) between 1 and 30 keV the number of
electron-hole pairs generated in the ionization track of the mu+ can be tuned
between a few and several thousand. The results show the strong suppression of
the formation of those Mu states that depend on the availability of excess
electrons. This indicates, that the role of H-impurity states in determining
electric properties of semiconductors and insulators depends on the way how
atomic H is introduced into the material.


title: AMBER on the VLTI: data processing and calibration issues

abstract:
  We present here the current performances of the AMBER / VLTI instrument for
standard use and compare these with the offered modes of the instrument. We
show that the instrument is able to reach its specified precision only for
medium and high spectral resolution modes, differential observables and bright
objects. For absolute observables, the current achievable accuracy is strongly
limited by the vibrations of the Unit Telescopes, and also by the observing
procedure which does not take into account the night-long transfer function
monitoring. For low-resolution mode, the current limitation is more in the data
reduction side, since several effects negligible at medium spectral resolution
are not taken into account in the current pipeline. Finally, for faint objects
(SNR around 1 per spectral channel), electromagnetic interferences in the VLTI
interferometric laboratory with the detector electronics prevents currently to
get unbiased measurements. Ideas are under study to correct in the data
processing side this effect, but a hardware fix should be investigated
seriously since it limits seriously the effective limiting magnitude of the
instrument.


title:
Comparative study of complex N- and O-bearing molecules in hot molecular
  cores

abstract:
  We have observed several emission lines of two Nitrogen-bearing (C2H5CN and
C2H3CN) and two Oxygen-bearing (CH3OCH3 and HCOOCH3) molecules towards a sample
of well-known hot molecular cores (HMCs) in order to check whether the chemical
differentiation seen in the Orion-HMC and W3(H_2O) between O- and N-bearing
molecules is a general property of HMCs. With the IRAM-30m telescope we have
observed 12 HMCs in 21 bands, centered at frequencies from 86250 to 258280 MHz.
The rotational temperatures obtained range from ~100 to ~150 K in these HMCs.
Single Gaussian fits performed to unblended lines show a marginal difference in
the line peak velocities of the C2H5CN and CH3OCH3 lines, indicating a possible
spatial separation between the region traced by the two molecules. On the other
hand, neither the linewidths nor the rotational temperatures and column
densities confirm such a result. By comparing the abundance ratio of the pair
C2H5CN/C2H3CN with the predictions of theoretical models, we derive that the
age of our cores ranges between 3.7 and 5.9x10^{4} yrs. The abundances of
C2H5CN and C2H3CN are strongly correlated, as expected from theory which
predicts that C2H3CN is formed through gas phase reactions involving C2H5CN. A
correlation is also found between the abundances of C2H3CN and CH3OCH3, and
C2H5CN and CH3OCH3. In all tracers the fractional abundances increase with the
H_2 column density while they are not correlated with the gas temperature.


title:
Possible manifestation of spin fluctuations in the temperature behavior
  of resistivity in Sm_{1.85}Ce_{0.15}CuO_4 thin films

abstract:
  A pronounced step-like (kink) behavior in the temperature dependence of
resistivity $\rho (T)$ is observed in the optimally-doped
$Sm_{1.85}Ce_{0.15}CuO_4$ thin films around $T_{sf}=87K$ and attributed to
manifestation of strong spin fluctuations induced by $Sm^{3+}$ moments with the
energy $\hbar \omega_{sf}=k_BT_{sf}\simeq 7meV$. In addition to fluctuation
induced contribution $\rho_{sf}(T)$ due to thermal broadening effects (of the
width $\omega_{sf}$), the experimental data are found to be well fitted
accounting for residual (zero-temperature) $\rho_{res}$, electron-phonon $\rho
_{e-ph}(T)=AT$ and electron-electron $\rho_{e-e}(T)=BT^2$ contributions. The
best fits produced $\omega_p=2.1meV$, $\tau_0^{-1}=9.5\times 10^{-14}s^{-1}$,
$\lambda =1.2$, and $E_F=0.2eV$ for estimates of the plasmon frequency, the
impurity scattering rate, electron-phonon coupling constant, and the Fermi
energy, respectively.


title: Modeling of orbital modulation of Cygnus X-3 by particle simulations

abstract:
  The formation of the circumbinary envelope of Cygnus X-3 was studied by
particle simulations of the WR (Wolf Rayet) companion wind. Light curves
resulting from electron scattering absorption in this envelope were computed
and compared with observed IBIS/ISGRI and BATSE light curves. The matching was
relatively good. For reasonable values of binary parameters (masses,
inclination) and wind velocities, a stable envelope was formed during a few
binary orbits. Assuming approximately 10^-6 solar mass/year for the rate of the
WR-wind, the observed light curves and accretion luminosity can be re-produced
(assuming Thomson scattering opacity in the ionized He-rich envelope). The
illuminated envelope can also model the CHANDRA-spectrum using the
photoionizing XSTAR-code. Furthermore, we discuss observed radial velocity
curves of IR emission lines in the context of simulated velocity fields and
find good agreement.


title: Spinor calculus for q-deformed quantum spaces I

abstract:
  The article is dedicated to q-deformed versions of spinor calculus. As a kind
of review, the most relevant properties of the two-dimensional quantum plane
are summarized. Additionally, the relationship between the quantum plane and
higher-dimensional quantum spaces like the q-deformed Euclidean space in four
dimensions or the q-deformed Minkowski space is outlined. These considerations
are continued by introducing q-analogs of the Pauli matrices. Their main
properties are discussed in detail and numerous relations that could prove
useful in physical applications are presented. In this respect, q-deformed
versions of the important Fierz identities are written down.


title: Unitary spaces on Clifford algebras

abstract:
  For the complex Clifford algebra Cl(p,q) of dimension n=p+q we define a
Hermitian scalar product. This scalar product depends on the signature (p,q) of
Clifford algebra. So, we arrive at unitary spaces on Clifford algebras. With
the aid of Hermitian idempotents we suggest a new construction of, so called,
normal matrix representations of Clifford algebra elements. These
representations take into account the structure of unitary space on Clifford
algebra.


title: Covariant calculation of strange decays of baryon resonances

abstract:
  We present results for kaon decay widths of baryon resonances from a
relativistic study with constituent quark models. The calculations are done in
the point-form of Poincare-invariant quantum mechanics with a spectator-model
decay operator. We obtain covariant predictions of the Goldstone-boson-exchange
and a variant of the one-gluon-exchange constituent quark models for all kaon
decay widths of established baryon resonances. They are generally characterized
by underestimating the available experimental data. In particular, the widths
of kaon decays with increasing strangeness in the baryon turn out to be
extremely small. We also consider the nonrelativistic limit, leading to the
familiar elementary emission model, and demonstrate the importance of
relativistic effects. It is found that the nonrelativistic approach evidently
misses sensible influences from Lorentz boosts and some essential spin-coupling
terms.


title:
Two-dimensional Ising model with competing interactions and its
  application to clusters and arrays of $\pi$-rings and adiabatic quantum
  computing

abstract:
  We study planar clusters consisting of loops including a Josephson
$\pi$-junction ($\pi$-rings). Each $\pi$-ring carries a persistent current and
behaves as a classical orbital moment. The type of particular state associated
with the orientation of orbital moments at the cluster depends on the
interaction between these orbital moments and can be easily controlled, i.e. by
a bias current or by other means. We show that these systems can be described
by the two-dimensional Ising model with competing nearest-neighbor and diagonal
interactions and investigate the phase diagram of this model. The
characteristic features of the model are analyzed based on the exact solutions
for small clusters such as a 5-site square plaquette as well as on a mean-field
type approach for the infinite square lattice of Ising spins. The results are
compared with spin patterns obtained by Monte Carlo simulations for the 100
$\times$ 100 square lattice and with experiment. We show that the $\pi$-ring
clusters may be used as a new type of superconducting memory elements. The
obtained results may be verified in experiments and are applicable to adiabatic
quantum computing where the states are switched adiabatically with the slow
change of coupling constants.


title: Statistical Mechanics Analysis of LDPC Coding in MIMO Gaussian Channels

abstract:
  Using analytical methods of statistical mechanics, we analyse the typical
behaviour of a multiple-input multiple-output (MIMO) Gaussian channel with
binary inputs under LDPC network coding and joint decoding. The saddle point
equations for the replica symmetric solution are found in particular
realizations of this channel, including a small and large number of
transmitters and receivers. In particular, we examine the cases of a single
transmitter, a single receiver and the symmetric and asymmetric interference
channels. Both dynamical and thermodynamical transitions from the ferromagnetic
solution of perfect decoding to a non-ferromagnetic solution are identified for
the cases considered, marking the practical and theoretical limits of the
system under the current coding scheme. Numerical results are provided, showing
the typical level of improvement/deterioration achieved with respect to the
single transmitter/receiver result, for the various cases.


title: Dimer Models, Free Fermions and Super Quantum Mechanics

abstract:
  This note relates topics in statistical mechanics, graph theory and
combinatorics, lattice quantum field theory, super quantum mechanics and string
theory. We give a precise relation between the dimer model on a graph embedded
on a torus and the massless free Majorana fermion living on the same lattice. A
loop expansion of the fermion determinant is performed, where the loops turn
out to be compositions of two perfect matchings. These loop states are sorted
into co-chain groups using categorification techniques similar to the ones used
for categorifying knot polynomials. The Euler characteristic of the resulting
co-chain complex recovers the Newton polynomial of the dimer model. We
re-interpret this system as supersymmetric quantum mechanics, where
configurations with vanishing net winding number form the ground states.
Finally, we make use of the quiver gauge theory - dimer model correspondence to
obtain an interpretation of the loops in terms of the physics of D-branes
probing a toric Calabi-Yau singularity.


title: Deligne-Lusztig varieties and period domains over finite fields

abstract:
  We prove that the Drinfeld halfspace is essentially the only Deligne-Lusztig
variety which is at the same time a period domain over a finite field. This is
done by comparing a cohomology vanishing theorem for DL-varieties, due to
Digne, Michel, and Rouquier, with a non-vanishing theorem for PD, due to the
first author. We also discuss an affineness criterion for DL-varieties.


title: FPU phenomenon for generic initial data

abstract:
  The well known FPU phenomenon (lack of attainment of equipartition of the
mode--energies at low energies, for some exceptional initial data) suggests
that the FPU model does not have the mixing property at low energies. We give
numerical indications that this is actually the case. This we show by computing
orbits for sets of initial data of full measure, sampled out from the
microcanonical ensemble by standard Montecarlo techniques. Mixing is tested by
looking at the decay of the autocorrelations of the mode--energies, and it is
found that the high--frequency modes have autocorrelations that tend instead to
positive values. Indications are given that such a nonmixing property survives
in the thermodynamic limit. It is left as an open problem whether mixing
obtains within time--scales much longer than the presently available ones.


title: An Extra Long X-Ray Plateau in a Gamma-Ray Burst and the Spinar Paradigm

abstract:
  The recently discovered gamma-ray burst GRB 070110 displayed an extraordinary
X-ray afterglow with Xray radiation-i.e., an X-ray plateau-observed for 20,000
s. We show that the observed properties of the plateau can be naturally
interpreted in terms of the model with a spinar-a quasi-equilibrium collapsing
object whose equilibrium is maintained by the balance of centrifugal and
gravitational forces and whose evolution is determined by its magnetic field.
If this model is true, then for 1 hr, the Swift X-ray telescopes recorded
radiation from an object with a size smaller than the Schwarzschild radius!


title:
Quantum Measurement as a Final-State Interaction with a Macroscopic
  External System

abstract:
  A small quantum scattering system (the microsystem) is studied in interaction
with a large system (the macrosystem) described by unknown stochastic
variables. The interaction between the two systems is diagonal for the
microsystem in a certain orthonormal basis, and the interaction gives an
imprint on the macrosystem. Moreover, the interaction is assumed to involve
only small transfers of energy and momentum between the two systems (as
compared to typical energies/momenta within the microsystem). The analysis is
carried out within scattering theory. Calculated in the conventional way, the
transition amplitude for the whole system factorizes. The interaction taking
place within the macrosystem is assumed to depend on the stochastic variables
in such a way that, on the average, no particular basis vector state of the
microsystem is favoured. The density matrix is studied in a formalism which
includes generation of the ingoing state and absorption of the final state.
Then the dependence of the final state on the conventional scattering amplitude
for the microsystem is highly non-linear.
  In the thermodynamic limit of the macrosystem, the density matrix of the
ensemble (of microsystem plus macrosystem) develops into a final state which
involves a set of macroscopically distinguishable states, each with the
microsystem in one of the basis vector states and the macrosystem in an
entangled state.
  For an element of the ensemble, i.e., for a single measurement, the result is
instead a random walk, where the microsystem ends up in one of the basis vector
states (reduction of the wave packet).