title:
Solutions for the constant quantum Yang-Baxter equation from Lie
  (super)algebras

abstract:
  We present a systematic procedure to obtain singular solutions of the
constant quantum Yang-Baxter equation in arbitrary dimension. This approach,
inspired in the Lie (super)algebra structure, is explicitly applied to the
particular case of (graded) contractions of the orthogonal real algebra
${\mathfrak{so}}(N+1)$. In this way we show that "classical" contraction
parameters which appear in the commutation relations of the contracted Lie
algebras, become quantum deformation parameters, arising as entries of the
resulting quantum $R$-matrices.


title:
Lift of noninvariant solutions of heavenly equations from three to four
  dimensions and new ultra-hyperbolic metrics

abstract:
  We demonstrate that partner symmetries provide a lift of noninvariant
solutions of three-dimensional Boyer-Finley equation to noninvariant solutions
of four-dimensional hyperbolic complex Monge-Ampere equation. The lift is
applied to noninvariant solutions of the Boyer-Finley equation, obtained
earlier by the method of group foliation, to yield noninvariant solutions of
the hyperbolic complex Monge-Ampere equation. Using these solutions we
construct new Ricci-flat ultra-hyperbolic metrics with non-zero curvature
tensor that have no Killing vectors.


title: Revisiting the effect of nearby supernova remnants on local cosmic rays

abstract:
  In an earlier paper, the effect of the nearby known supernova remnants (SNRs)
on the local cosmic-rays (CRs) was studied, considering different possible
forms of the particle injection time. The present work is a continuation of the
previous work, but assumes a more realistic model of CR propagation in the
Galaxy. The previous work assumed an unbounded three-dimensional diffusion
region, whereas the present one considers a flat cylindrical disc bounded in
both the radial and vertical directions. The study has found that the effect of
the vertical halo boundary $H$ on the local SNR contribution to the observed CR
anisotropy is negligible as long as $H\gtrsim 2kpc$. Considering the values of
the halo height $H\gtrsim 2kpc$ obtained by different authors, the present work
suggests that the study of the effect of local sources on the CR anisotropy can
be carried out without having much information on $H$ and hence, using the much
simpler three-dimentional unbounded solution. Finally, the present work
discusses about the possibility of explaining the observed anisotropy below the
knee by a single dominant source with properly chosen source parameters, and
claims that the source may be an \textit{undetected} old SNR with a
characteristic age of $\sim 1.5\times 10^5 yr$ located at a distance of $\sim
0.57 kpc$ from the Sun.


title:
The Blazhko behaviour of RR Geminorum II -- long-term photometric
  results

abstract:
  Context. RR Gem is one of the few Blazhko RR Lyrae that has photometric
observations available extended enough to study the long-term courses of its
pulsation and modulation properties in detail.
  Aims. We investigate the pulsation and modulation properties and the
relations between them in RR Gem using photometric observations from the past
70 years in order to gain further insight into the nature of the Blazhko
modulation.
  Methods. We studied the photographic, photoelectric, and CCD light curves
obtained at the Konkoly Observatory and other authors' published maxima
observations. Detailed analysis of the light curves, maximum brightness, and
O-C data are carried out.
  Results. RR Gem showed modulation most of the time it was observed. The
modulation amplitude showed strong variations from the undetectable level (less
than 0.04 mag in maximum brightness) to about 0.20 mag. The amplitudes of the
amplitude and phase modulations showed parallel changes, thus the total 'power'
of the modulation have changed during the past 70 years. Parallel changes in
the pulsation and modulation periods occur with a d P_mod / d P_puls = 1.6 +/-
0.8 * 10^3 ratio. We also detected 0.05-0.1 mag changes in the mean maximum
brightness and mean pulsation amplitude.


title: Gravitomagnetism, Frame-Dragging and Lunar Laser Ranging

abstract:
  We discuss here the measurement of gravitomagnetism and frame dragging with
Lunar Laser Ranging, LAGEOS and LARES Satellites, and Gravity Probe B.


title: Generators of Jacobians of Hyperelliptic Curves

abstract:
  This paper provides a probabilistic algorithm to determine generators of the
m-torsion subgroup of the Jacobian of a hyperelliptic curve of genus two.


title:
Production of Higgs boson excitations of universal extra dimension at
  the Large Hadron Collider

abstract:
  The Kaluza-Klein excitations of the Higgs bosons of the universal extra
dimension model are extremely challenging to detect. We discuss the production
and possible detection mechanisms of such excited scalars at the LHC. The
dominant production mechanism of such scalars is from the decay of the excited
third generation quarks. In particular, the charged Higgs boson has a large
production cross-section over most of the parameter space. We highlight how one
may detect these excited scalars. We also comment on the production and
detection of excited neutral scalars.


title:
Studying Blazhko RR Lyrae stars with the 24-inch telescope of the
  Konkoly Observatory

abstract:
  About a dozen field RR Lyrae stars have been observed with the 24-inch
Heyde-Zeiss telescope of the Konkoly Observatory at Sv\'abhegy, Budapest, since
its refurbishment in 2003. Most of the observing time is allocated for the
investigation of the Blazhko modulation, a phenomenon that still does not have
a satisfactory explanation. The obtained multicolour CCD observations are
unique in extent. The accuracy of the measurements makes it possible to detect
low amplitude modulation of the light curve as well. The discovery of Blazhko
stars with low modulation amplitudes warns that the incidence rate of the
Blazhko modulation is, in fact, much larger than it was previously expected.
This makes the efforts exploring the cause of the modulation even more
important. A summary of our measurements and results achieved during the last 3
years is presented.


title:
Multiplets of representations, twisted Dirac operators and Vogan's
  conjecture in affine setting

abstract:
  We extend classical results of Kostant and al. on multiplets of
representations of finite-dimensional Lie algebras and on the cubic Dirac
operator to the setting of affine Lie algebras and twisted affine cubic Dirac
operator. We prove in this setting an analogue of Vogan's conjecture on
infinitesimal characters of Harish-Chandra modules in terms of Dirac
cohomology. For our calculations we use the machinery of Lie conformal and
vertex algebras.


title:
Kaluza-Klein Induced Supersymmetry Breaking for Braneworlds in Type IIB
  Supergravity

abstract:
  We consider Z_2-symmetric braneworlds arising from 5-sphere compactifications
with 5-form flux in type IIB supergravity. This Kaluza-Klein reduction produces
a D=5 theory which supports 1/2-supersymmetric Z_2-symmetric domain-wall
solutions. However, upon lifting such solutions back to D=10, one finds that
supersymmetry is broken by 5-sphere Kaluza-Klein effects. This happens owing to
the action on the Killing spinor of the Z_2 \subset SO(1,9) symmetry, which
requires an orientation-reversing transformation in the 5-sphere directions
together with the flip of the orbifold coordinate. We study the consequences of
this supersymmetry breaking for the masses of fermion fluctuation modes about
the brane background and find a natural two-scale hierarchy: some bulk modes
have characteristic masses of order 1/L_5 but other modes more closely
associated to the branes have an additional factor exp(-\rho/L_5), where L_5 is
the AdS_5 length parameter and \rho is the orbifold size.


title: Solving the QCD NLO evolution equations with a Markovian Monte Carlo

abstract:
  We discuss precision Monte Carlo (MC) calculations for solving the QCD
evolution equations up to the next-to-leading-order (NLO) level. They employ
forward Markovian Monte Carlo algorithms, which provide rigorous solutions of
the above equations. These algorithms are implemented in the form of the Monte
Carlo program EvolFMC. This program has been cross-checked with independent,
non-MC, programs (QCDNum16 and APCheb33) and the numerical agreement at the
level of 0.1% has been found.


title: (Erratum) An f(R) gravitation for galactic environments

abstract: Without abstract.


title: Higher-dimensional Temperley-Lieb algebras

abstract:
  A category which generalises to higher dimensions many of the features of the
Temperley-Lieb category is introduced.


title:
Universal dynamical decoherence control of noisy single-and multi-qubit
  systems

abstract:
  In this article we develop, step by step, the framework for universal
dynamical control of two-level systems (TLS) or qubits experiencing amplitude-
or phase-noise (AN or PN) due to coupling to a thermal bath. A comprehensive
arsenal of modulation schemes is introduced and applied to either AN or PN,
resulting in completely analogous formulae for the decoherence rates, thus
underscoring the unified nature of this universal formalism. We then address
the extension of this formalism to multipartite decoherence control, where
symmetries are exploited to overcome decoherence.


title:
Extreme points of the set of density matrices with positive partial
  transpose

abstract:
  We present a necessary and sufficient condition for a finite dimensional
density matrix to be an extreme point of the convex set of density matrices
with positive partial transpose with respect to a subsystem. We also give an
algorithm for finding such extreme points and illustrate this by some examples.


title:
J-class weighted shifts on the space of bounded sequences of complex
  numbers

abstract:
  We provide a characterization of $J$-class and $J^{mix}$-class unilateral
weighted shifts on $l^{\infty}(\mathbb{N})$ in terms of their weight sequences.
In contrast to the previously mentioned result we show that a bilateral
weighted shift on $l^{\infty}(\mathbb{Z})$ cannot be a $J$-class operator.


title:
The Statistics of the Points Where Nodal Lines Intersect a Reference
  Curve

abstract:
  We study the intersection points of a fixed planar curve $\Gamma$ with the
nodal set of a translationally invariant and isotropic Gaussian random field
$\Psi(\bi{r})$ and the zeros of its normal derivative across the curve. The
intersection points form a discrete random process which is the object of this
study. The field probability distribution function is completely specified by
the correlation $G(|\bi{r}-\bi{r}'|) = <\Psi(\bi{r}) \Psi(\bi{r}')>$.
  Given an arbitrary $G(|\bi{r}-\bi{r}'|)$, we compute the two point
correlation function of the point process on the line, and derive other
statistical measures (repulsion, rigidity) which characterize the short and
long range correlations of the intersection points. We use these statistical
measures to quantitatively characterize the complex patterns displayed by
various kinds of nodal networks. We apply these statistics in particular to
nodal patterns of random waves and of eigenfunctions of chaotic billiards. Of
special interest is the observation that for monochromatic random waves, the
number variance of the intersections with long straight segments grows like $L
\ln L$, as opposed to the linear growth predicted by the percolation model,
which was successfully used to predict other long range nodal properties of
that field.


title: Symbolic sensors : one solution to the numerical-symbolic interface

abstract:
  This paper introduces the concept of symbolic sensor as an extension of the
smart sensor one. Then, the links between the physical world and the symbolic
one are introduced. The creation of symbols is proposed within the frame of the
pretopology theory. In order to adapt the sensor to the measurement context, a
learning process has been used to provide an adaptive interpretation of the
measurement. Finally, an example is presented in the case of a temperature
measurement.


title:
Theory of weakly damped free-surface flows: a new formulation based on
  potential flow solutions

abstract:
  Several theories for weakly damped free-surface flows have been formulated.
In this paper we use the linear approximation to the Navier-Stokes equations to
derive a new set of equations for potential flow which include dissipation due
to viscosity. A viscous correction is added not only to the irrotational
pressure (Bernoulli's equation), but also to the kinematic boundary condition.
The nonlinear Schr\"odinger (NLS) equation that one can derive from the new set
of equations to describe the modulations of weakly nonlinear, weakly damped
deep-water gravity waves turns out to be the classical damped version of the
NLS equation that has been used by many authors without rigorous justification.


title: Symbolic sensors

abstract:
  This paper deals with sensors which compute and report linguistic assessments
of their values.Such sensors, called symbolic sensors are a natural extension
of smart ones when working with control systems which use artificial
intelligence based technics. After having recalled the smart sensor concepts,
this paper introduces the symbolic sensor ones. Links between the physical
world and the symbolic one are described. It is then shown how Zadeh's
approximate reasoning theory provides a smart way to implement symbolic
sensors. Finally, since the symbolic sensor is a general component, a
functional adaptation to the measurement context is proposed.


title: J-class operators and hypercyclicity

abstract:
  The purpose of the present work is to treat a new notion related to linear
dynamics, which can be viewed as a "localization" of the notion of
hypercyclicity. In particular, let $T$ be a bounded linear operator acting on a
Banach space $X$ and let $x$ be a non-zero vector in $X$ such that for every
open neighborhood $U\subset X$ of $x$ and every non-empty open set $V\subset X$
there exists a positive integer $n$ such that $T^{n}U\cap V\neq\emptyset$. In
this case $T$ will be called a $J$-class operator. We investigate the class of
operators satisfying the above property and provide various examples. It is
worthwhile to mention that many results from the theory of hypercyclic
operators have their analogues in this setting. For example we establish
results related to the Bourdon-Feldman theorem and we characterize the
$J$-class weighted shifts. We would also like to stress that even non-separable
Banach spaces which do not support topologically transitive operators, as for
example $l^{\infty}(\mathbb{N})$, do admit $J$-class operators.


title: Wreath products in modular group algebras of some finite 2-groups

abstract:
  Let $K$ be field of characteristic 2 and let $G$ be a finite non-abelian
2-group with the cyclic derived subgroup $G'$, and there exists a central
element $z$ of order 2 in $Z(G) \backslash G'$. We prove that the unit group of
the group algebra $KG$ possesses a section isomorphic to the wreath product of
a group of order 2 with the derived subgroup of the group $G$, giving for such
groups a positive answer to the question of A. Shalev.


title:
Pr\'evention des escarres chez les parapl\'egiques : une nouvelle
  approche par \'electrostimulation linguale

abstract:
  Pressure ulcers are recognized as a major health issue in individuals with
spinal cord injuries and new approaches to prevent this pathology are
necessary. An innovative health strategy is being developed through the use of
computer and sensory substitution via the tongue in order to compensate for the
sensory loss in the buttock area for individuals with paraplegia. This sensory
compensation will enable individuals with spinal cord injuries to be aware of a
localized excess of pressure at the skin/seat interface and, consequently, will
enable them to prevent the formation of pressure ulcers by relieving the
cutaneous area of suffering. This work reports an initial evaluation of this
approach and the feasibility of creating an adapted behavior, with a change in
pressure as a response to electro-stimulated information on the tongue.
Obtained during a clinical study in 10 healthy seated subjects, the first
results are encouraging, with 92% success in 100 performed tests. These
results, which have to be completed and validated in the paraplegic population,
may lead to a new approach to education in health to prevent the formation of
pressure ulcers within this population. Keywords: Spinal Cord Injuries,
Pressure Ulcer, Sensory Substitution, Health Education, Biomedical Informatics.


title: Statistical-mechanical description of quantum entanglement

abstract:
  We present a description of finite dimensional quantum entanglement, based on
a study of the space of all convex decompositions of a given density matrix. On
this space we construct a system of real polynomial equations describing
separable states. We further study this system using statistical mechanical
methods. Finally, we apply our techniques to Werner states of two qubits and
obtain a sufficient criterion for separability.


title: A Class of pairwise-independent Joinings

abstract:
  We introduce a special class of pairwise-independent self-joinings for a
stationary process: Those for which one coordinate is a continuous function of
the two others. We investigate which properties on the process the existence of
such a joining entails. In particular, we prove that if the process is
aperiodic, then it has positive entropy. Our other results suggest that such
pairwise independent, non-independent self-joinings exist only in very specific
situations: Essentially when the process is a subshift of finite type
topologically conjugate to a full-shift. This provides an argument in favor of
the conjecture that 2-fold mixing implies 3-fold-mixing.


title: Direct Optimization of Ranking Measures

abstract:
  Web page ranking and collaborative filtering require the optimization of
sophisticated performance measures. Current Support Vector approaches are
unable to optimize them directly and focus on pairwise comparisons instead. We
present a new approach which allows direct optimization of the relevant loss
functions. This is achieved via structured estimation in Hilbert spaces. It is
most related to Max-Margin-Markov networks optimization of multivariate
performance measures. Key to our approach is that during training the ranking
problem can be viewed as a linear assignment problem, which can be solved by
the Hungarian Marriage algorithm. At test time, a sort operation is sufficient,
as our algorithm assigns a relevance score to every (document, query) pair.
Experiments show that the our algorithm is fast and that it works very well.


title:
A double main sequence turn-off in the rich star cluster NGC 1846 in the
  Large Magellanic Cloud

abstract:
  We report on HST/ACS photometry of the rich intermediate-age star cluster NGC
1846 in the Large Magellanic Cloud, which clearly reveals the presence of a
double main sequence turn-off in this object. Despite this, the main sequence,
sub-giant branch, and red giant branch are all narrow and well-defined, and the
red clump is compact. We examine the spatial distribution of turn-off stars and
demonstrate that all belong to NGC 1846 rather than to any field star
population. In addition, the spatial distributions of the two sets of turn-off
stars may exhibit different central concentrations and some asymmetries. By
fitting isochrones, we show that the properties of the colour-magnitude diagram
can be explained if there are two stellar populations of equivalent metal
abundance in NGC 1846, differing in age by approximately 300 Myr. The absolute
ages of the two populations are ~1.9 and ~2.2 Gyr, although there may be a
systematic error of up to +/-0.4 Gyr in these values. The metal abundance
inferred from isochrone fitting is [M/H] ~ -0.40, consistent with spectroscopic
measurements of [Fe/H]. We propose that the observed properties of NGC 1846 can
be explained if this object originated via the tidal capture of two star
clusters formed separately in a star cluster group in a single giant molecular
cloud. This scenario accounts naturally for the age difference and uniform
metallicity of the two member populations, as well as the differences in their
spatial distributions.


title: Kinematic segregation of nearby disk stars from the Hipparcos database

abstract:
  To better understand our Galaxy, we investigate the pertinency of describing
the sys tem of nearby disk stars in terms of a two-components Schwarzschild
velocity distributio n.Using the proper motion and parallax information of
Hipparcos database, we determine t he parameters characterizing the local
stellar velocity field of a sample of 22000 disk stars. The sample we use is
essentially the same as the one described by the criteria ad opted to study the
LSR and the stream motion of the nearby stellar population


title: Eigenfunctions of the two-dimensional Moshinsky-Szczepaniak Oscillator

abstract:
  While the usual harmonic oscillator potential gives discrete energies in the
non-relativistic case, it does not however give genuine bound states in the
relativistic case if the potential is treated in the usual way. In the present
article, we have obtained the eigenfunctions of the Dirac oscillator in two
spatial dimensions, adapting the prescription of Moshinsky.


title: Topology and Factorization of Polynomials

abstract:
  For any polynomial $P \in \mathbb{C}[X_1,X_2,...,X_n]$, we describe a
$\mathbb{C}$-vector space $F(P)$ of solutions of a linear system of equations
coming from some algebraic partial differential equations such that the
dimension of $F(P)$ is the number of irreducible factors of $P$. Moreover, the
knowledge of $F(P)$ gives a complete factorization of the polynomial $P$ by
taking gcd's. This generalizes previous results by Ruppert and Gao in the case
$n=2$.


title: Upper limit on spontaneous supercurrents in Sr$_2$RuO$_4$

abstract:
  It is widely believed that the perovskite Sr$_2$RuO$_4$ is an unconventional
superconductor with broken time reversal symmetry. It has been predicted that
superconductors with broken time reversal symmetry should have spontaneously
generated supercurrents at edges and domain walls. We have done careful imaging
of the magnetic fields above Sr$_2$RuO$_4$ single crystals using scanning Hall
bar and SQUID microscopies, and see no evidence for such spontaneously
generated supercurrents. We use the results from our magnetic imaging to place
upper limits on the spontaneously generated supercurrents at edges and domain
walls as a function of domain size. For a single domain, this upper limit is
below the predicted signal by two orders of magnitude. We speculate on the
causes and implications of the lack of large spontaneous supercurrents in this
very interesting superconducting system.


title:
Wang-Landau molecular dynamics technique to search for low-energy
  conformational space of proteins

abstract:
  Multicanonical molecular dynamics (MD) is a powerful technique for sampling
conformations on rugged potential surfaces such as protein. However, it is
notoriously difficult to estimate the multicanonical temperature effectively.
Wang and Landau developed a convenient method for estimating the density of
states based on a multicanonical Monte Carlo method. In their method, the
density of states is calculated autonomously during a simulation. In this paper
we develop a set of techniques to effectively apply the Wang-Landau method to
MD simulations. In the multicanonical MD, the estimation of the derivative of
the density of states is critical. In order to estimate it accurately, we
devise two original improvements. First, the correction for the density of
states is made smooth by using the Gaussian distribution obtained by a short
canonical simulation. Second, an approximation is applied to the derivative,
which is based on the Gaussian distribution and the multiple weighted histogram
technique. A test of this method was performed with small polypeptides,
Met-enkephalin and Trp-cage, and it is demonstrated that Wang-Landau MD is
consistent with replica exchange MD but can sample much larger conformational
space.


title: Dynamics of a strongly interacting Fermi gas: the radial quadrupole mode

abstract:
  We report on measurements of an elementary surface mode in an ultracold,
strongly interacting Fermi gas of 6Li atoms. The radial quadrupole mode allows
us to probe hydrodynamic behavior in the BEC-BCS crossover without being
influenced by changes in the equation of state. We examine frequency and
damping of this mode, along with its expansion dynamics. In the unitarity limit
and on the BEC side of the resonance, the observed frequencies agree with
standard hydrodynamic theory. However, on the BCS side of the crossover, a
striking down shift of the oscillation frequency is observed in the
hydrodynamic regime as a precursor to an abrupt transition to collisionless
behavior; this indicates coupling of the oscillation to fermionic pairs.


title: Random walks of Wilson loops in the screening regime

abstract:
  Dynamics of Wilson loops in pure Yang-Mills theories is analyzed in terms of
random walks of the holonomies of the gauge field on the gauge group manifold.
It is shown that such random walks should necessarily be free. The distribution
of steps of these random walks is related to the spectrum of string tensions of
the theory and to certain cumulants of Yang-Mills curvature tensor. It turns
out that when colour charges are completely screened, the holonomies of the
gauge field can change only by the elements of the group center, which
indicates that in the screening regime confinement persists due to thin center
vortices. Thick center vortices are also considered and the emergence of such
stepwise changes in the limits of infinitely thin vortices and infinitely large
loops is demonstrated.


title:
Search for gravitational waves from binary inspirals in S3 and S4 LIGO
  data

abstract:
  We report on a search for gravitational waves from the coalescence of compact
binaries during the third and fourth LIGO science runs. The search focused on
gravitational waves generated during the inspiral phase of the binary
evolution. In our analysis, we considered three categories of compact binary
systems, ordered by mass: (i) primordial black hole binaries with masses in the
range 0.35 M(sun) < m1, m2 < 1.0 M(sun), (ii) binary neutron stars with masses
in the range 1.0 M(sun) < m1, m2 < 3.0 M(sun), and (iii) binary black holes
with masses in the range 3.0 M(sun)< m1, m2 < m_(max) with the additional
constraint m1+ m2 < m_(max), where m_(max) was set to 40.0 M(sun) and 80.0
M(sun) in the third and fourth science runs, respectively. Although the
detectors could probe to distances as far as tens of Mpc, no gravitational-wave
signals were identified in the 1364 hours of data we analyzed. Assuming a
binary population with a Gaussian distribution around 0.75-0.75 M(sun), 1.4-1.4
M(sun), and 5.0-5.0 M(sun), we derived 90%-confidence upper limit rates of 4.9
yr^(-1) L10^(-1) for primordial black hole binaries, 1.2 yr^(-1) L10^(-1) for
binary neutron stars, and 0.5 yr^(-1) L10^(-1) for stellar mass binary black
holes, where L10 is 10^(10) times the blue light luminosity of the Sun.


title: Planetary Migration to Large Radii

abstract:
  There is evidence for the existence of massive planets at orbital radii of
several hundred AU from their parent stars where the timescale for planet
formation by core accretion is longer than the disc lifetime. These planets
could have formed close to their star and then migrated outwards. We consider
how the transfer of angular momentum by viscous disc interactions from a
massive inner planet could cause significant outward migration of a smaller
outer planet. We find that it is in principle possible for planets to migrate
to large radii. We note, however, a number of effects which may render the
process somewhat problematic.


title: Natural boundary of Dirichlet series

abstract:
  We prove some conditions on the existence of natural boundaries of Dirichlet
series. We show that generically the presumed boundary is the natural one. We
also give an application of natural boundaries in determining asymptotic
results.


title: Some remarks on generalized roundness

abstract:
  By using the links between generalized roundness, negative type inequalities
and equivariant Hilbert space compressions, we obtain that the generalized
roundness of the usual Cayley graph of finitely generated free groups and free
abelian groups of rank $\geq 2$ equals 1. This answers a question of J-F.
Lafont and S. Prassidis.


title:
Shearfree perfect fluids with solenoidal magnetic curvature and a
  gamma-law equation of state

abstract:
  We show that shearfree perfect fluids obeying an equation of state p=(gamma
-1) mu are non-rotating or non-expanding under the assumption that the spatial
divergence of the magnetic part of the Weyl tensor is zero.


title: Extension of symmetries on Einstein manifolds with boundary

abstract:
  We investigate the validity of the isometry extension property for
(Riemannian) Einstein metrics on manifolds with boundary. Given a metric on the
boundary, this is the issue of whether any Killing field of the boundary metric
extends to a Killing field of any bulk or filling Einstein metric inducing the
given data on the boundary. Under a mild condition on the fundamental group,
this is proved to be the case at least when the Killing field preserves the
mean curvature of the boundary.


title: Geometry and Topology in Relativistic Cosmology

abstract:
  General relativity does not allow one to specify the topology of space,
leaving the possibility that space is multiply rather than simply connected. We
review the main mathematical properties of multiply connected spaces, and the
different tools to classify them and to analyse their properties. Following
their mathematical classification, we describe the different possible
muticonnected spaces which may be used to construct Friedmann-Lemaitre universe
models. Observational tests concern the distribution of images of discrete
cosmic objects or more global effects, mainly those concerning the Cosmic
Microwave Background. According to the 2003-2006 WMAP data releases, various
deviations from the flat infinite universe model predictions hint at a possible
non-trivial topology for the shape of space. In particular, a finite universe
with the topology of the Poincar\'e dodecahedral spherical space fits
remarkably well the data and is a good candidate for explaining both the local
curvature of space and the large angle anomalies in the temperature power
spectrum. Such a model of a small universe, whose volume would represent only
about 80% the volume of the observable universe, offers an observational
signature in the form of a predictable topological lens effect on one hand, and
rises new issues on the physics of the early universe on the other hand.


title:
Polarization effects for the reaction $e^++e^-\to \bar p+p $ in presence
  of two--photon exchange - Lecture Notes

abstract:
  The aim of this work is to give a pedagogical derivation of polarization
observables for the annihilation reaction $e^+ + e^- \to N+ \bar N$. The
reaction mechanism is one photon + two photon exchange, the last is described
by axial parametrization. After deriving the general expressions for the cross
section of a binary process, the matrix element is written in terms of three
complex amplitudes. The method to derive polarization observables is detailed
and all expressions are given in terms of generalized form factors. The
strategy for determining physical form factors in annihilation reactions in
presence of two photon exchange is suggested, on the basis of model independent
properties of the relevant observables.


title: Flow of autonomous traffic on a single multi-lane street

abstract:
  We investigate the behaviour of an original traffic model. The model
considers a single multi-lane street, populated by autonomous vehicles directed
from either end to the other. Lanes have no intrinsic directionality, and the
vehicles are inserted at random at either end and any lane. Collision avoidance
is fully automatic and, to enhance the transport capacity of the street,
vehicles form_trains_ in which they may travel at high speed quite close to the
vehicle in front.
  We report on the transit times for vehicles under a wide variety of
conditions: vehicle insertion probability & imbalance and their maximum speed
distribution. We also outline an interesting feature of the model, that the
complex interactions of many vehicles are considerably more powerful than a
simple "keep left" directive which each vehicle should obey.


title:
Halo-model signatures from 380,000 SDSS Luminous Red Galaxies with
  photometric redshifts

abstract:
  We analyze the small-scale clustering in "MegaZ-LRG", a large
photometric-redshift catalogue of Luminous Red Galaxies extracted from the
imaging dataset of the Sloan Digital Sky Survey. MegaZ-LRG, presented in a
companion paper, spans the redshift range 0.4 < z < 0.7 with an r.m.s. redshift
error dz ~ 0.03(1+z), covering 5,914 deg^2 to map out a total cosmic volume 2.5
h^-3 Gpc^3. In this study we use 380,000 photometric redshifts to measure
significant deviations from the canonical power-law fit to the angular
correlation function in a series of narrow redshift slices, in which we
construct volume-limited samples. These deviations are direct signatures of the
manner in which these galaxies populate the underlying network of dark matter
haloes. We cleanly delineate the separate contributions of the "1-halo" and
"2-halo" clustering terms and fit our measurements by parameterizing the halo
occupation distribution N(M) of the galaxies. Our results are successfully fit
by a "central" galaxy contribution with a "soft" transition from zero to one
galaxies, combined with a power-law "satellite" galaxy component, the slope of
which is a strong function of galaxy luminosity. The large majority of galaxies
are classified as central objects of their host dark matter haloes rather than
satellites in more massive systems. The effective halo mass of MegaZ-LRG
galaxies lies in the range log_10 (M_eff / h^-1 M_sol) = 13.61 - 13.8
(increasing with redshift, assuming large-scale normalization sigma_8 = 0.8)
for corresponding number densities in the range n_g = 5.03 - 0.56 x 10^-4 h^3
Mpc^-3. Our results confirm the usefulness of the halo model for gaining
physical insight into the patterns of galaxy clustering.


title:
Studies of the temperature and frequency dependent impedance of an
  electroceramic functional oxide thermistor

abstract:
  The charge transport mechanism and the macroscopic dielectric constant in
polycrystalline device materials commonly exhibit several components such as
electrode-sample interface, grain boundary and bulk contributions. In order to
gain precise understanding of the functionality of polycrystalline
electroceramic device materials it is essential to deconvolute these
contributions. The paradigm of functional thermistor ceramics based on thick
film spinel manganates has been studied by temperature dependent alternating
current impedance spectroscopy. Three typical relaxation phenomena were
detected, which all showed a separated temperature dependence of resistivity
consistent with thermally activated charge transport. The dominating grain
boundary and the interface contributions exhibited distinctively different
capacitance allowing clear identification. The composite nature of the
dielectric properties in polycrystalline functional ceramics was emphasized,
and impedance spectroscopy was shown to be a powerful tool to account for and
model such behaviour.


title: $A^\nabla$-tensors on lightlike hypersurfaces

abstract:
  This paper introduces $\anabla$-tensors on lightlike hypersurfaces $M^{n+1}$
of signature $(0,n)$, $(n\geq 1)$ and investigates on their properties in
connection with the null geometry of $M$. In particular, we show that there is
an interplay between existence of $\anabla$-tensors of certain type and
lightlike warped product structures.


title: VIMOS spectroscopy of extended emission line regions

abstract:
  We present the results of spectroscopic and imaging observations of the FRII
radio galaxies PKS2250-41 and PKS1932-46. Both sources display very extensive
emission line regions, and appear to be undergoing interactions with companion
bodies. In addition to disturbed gas kinematics associated with interactions
with the radio source, the more distant emitting material displays simple,
narrow emission line profiles, often at significant velocity offsets from the
system rest-frame, and may be associated with tidal debris.


title: Determinant Formulas Relating to Tableaux of Bounded Height

abstract:
  Chen et al. recently established bijections for $(d+1)$-noncrossing/
nonnesting matchings, oscillating tableaux of bounded height $d$, and
oscillating lattice walks in the $d$-dimensional Weyl chamber. Stanley asked
what is the total number of such tableaux of length $n$ and of any shape. We
find a determinant formula for the exponential generating function. The same
idea applies to prove Gessel's remarkable determinant formula for permutations
with bounded length of increasing subsequences. We also give short algebraic
derivations for some results of the reflection principle.


title: A note on conformal connections on lightlike hypersurfaces

abstract:
  Degenerate submanifolds of pseudo-Riemannian manifolds are quite difficult to
study because there is no prefered connection when the submanifold is not
totally geodesic. For the particular case of degenerate totally umbilical
hypersurfaces, we show that there are "Weyl" connections adapted to the induced
structure on the hypersurface. We begin the study of these with their holonomy.


title: Einstein-Weyl structures on lightike hypersurfaces

abstract:
  We study Weyl structures on lightlikes hypersurfaces endowed with a conformal
structure of certain type and specific screen distribution: the Weyl screen
structures. We investigate various differential geometric properties of
Einstein-Weyl screen structures on lightlike hypersurfaces and show that, for
ambiant Lorentzian space $\mathbb{R}^{n+2}_{1}$ and a totally umbilical screen
foliation, there is a strong interplay with the induced (Riemannian)
Weyl-structure on the leaves. Finally, we establish necessary and sufficient
conditions for a Weyl structure defined by the $1-$form of an almost contact
structure given by an additional complex structure in case of an ambiant
Kaehler manifold to be closed.


title: Decay channels and charmonium mass-shifts

abstract:
  The discovery in the last few years of the $X, Y$ and $Z$ states of the
extended charmonium family has highlighted the importance of the closeness of
decay channels to an understanding of these mesons. We aid this debate by
illustrating a simple calculational procedure for including the effect of open
and nearby closed channels.


title:
Constrained simulations of the local universe: I. Mass and motion in the
  Local Volume

abstract:
  It has been recently claimed that there is no correlation between the
distribution of galaxies and their peculiar velocities within the Local Volume
(LV), namely a sphere of R=7/h Mpc around the Local Group (LG). It has been
then stated that this implies that either locally dark matter is not
distributed in the same way as luminous matter, or peculiar velocities are not
due to fluctuations in mass. To test that statement a set of constrained N-body
cosmological simulations, designed to reproduce the main observed large scale
structure, have been analyzed. The simulations were performed within the
flat-Lambda, open and flat matter only CDM cosmogonies. Two unconstrained
simulations of the flat-Lambda and open CDM models were performed for
comparison. LG-like objects have been selected so as to mimic the real LG
environment. The local gravitational field due to all halos found within each
LV is compared with the exact gravitational field induced by all matter in the
simulation. We conclude that there is no correlation between the exact and the
local gravitational field obtained by pairwise newtonian forces between halos.
Moreover, the local gravitational field is uncorrelated with the peculiar
velocities of halos. The exact gravitational field has a linear correlation
with peculiar velocities but the proportionality constant relating the velocity
with gravitational field falls below the prediction of the linear theory. Upon
considering all matter inside the LVs, the exact and local gravitational
accelerations show a much better correlation, but with a considerable scatter
independent on the cosmological models. The main conclusion is that the lack of
correlation between the local gravitation and the peculiar velocity fields
around LG-like objects is naturally expected in the CDM cosmologies.


title: Four-dimensional Painlev\'e systems of types $D_5^{(1)}$ and $B_4^{(1)}$

abstract:
  We find and study a five-parameter family of four-dimensional coupled
Painlev\'e V systems with affine Weyl group symmetry of type $D_5^{(1)}$. We
then give an explicit description of a confluence from those systems to a
four-parameter family of four-dimensional coupled Painlev\'e III systems with
affine Weyl group symmetry of type $B_4^{(1)}$.


title: Noncommutative Berezin transforms and model theory

abstract:
  We initiate the study of a class of noncommutative domains of n-tuples of
bounded linear operators on a Hilbert space, which is generated by certain
positivity conditions on polynomials in n noncommutative indeterminates. We
obtain Fatou type results, functional calculi, and a model theory for n-tuples
of operators in these domains. The main role in this study is played by a class
of noncommutative Berezin transforms which is introduced in this paper. Our
results extend to noncommutative varieties.


title: L^2-Betti numbers of plane algebraic curves

abstract:
  In [DJL07] it was shown that if A is an affine hyperplane arrangement in C^n,
then at most one of the L^2-Betti numbers of its complement is non--zero. We
will prove an analogous statement for complements of any algebraic curve in
C^2. Furthermore we also recast and extend results of [LM06] in terms of
L^2-Betti numbers.


title:
Effect of selection on ancestry: an exactly soluble case and its
  phenomenological generalization

abstract:
  We consider a family of models describing the evolution under selection of a
population whose dynamics can be related to the propagation of noisy traveling
waves. For one particular model, that we shall call the exponential model, the
properties of the traveling wave front can be calculated exactly, as well as
the statistics of the genealogy of the population. One striking result is that,
for this particular model, the genealogical trees have the same statistics as
the trees of replicas in the Parisi mean-field theory of spin glasses. We also
find that in the exponential model, the coalescence times along these trees
grow like the logarithm of the population size. A phenomenological picture of
the propagation of wave fronts that we introduced in a previous work, as well
as our numerical data, suggest that these statistics remain valid for a larger
class of models, while the coalescence times grow like the cube of the
logarithm of the population size.


title: Realizations of Seifert matrices by hyperbolic knots

abstract:
  Recently Kearton showed that any Seifert matrix of a knot is S--equivalent to
the Seifert matrix of a prime knot. We show in this note that such a matrix is
in fact S--equivalent to the Seifert matrix of a hyperbolic knot. This result
follows from reinterpreting this problem in terms of Blanchfield pairings and
by applying results of Kawauchi.


title:
Lifetime Improvement in Wireless Sensor Networks via Collaborative
  Beamforming and Cooperative Transmission

abstract:
  Collaborative beamforming (CB) and cooperative transmission (CT) have
recently emerged as communication techniques that can make effective use of
collaborative/cooperative nodes to create a virtual
multiple-input/multiple-output (MIMO) system. Extending the lifetime of
networks composed of battery-operated nodes is a key issue in the design and
operation of wireless sensor networks. This paper considers the effects on
network lifetime of allowing closely located nodes to use CB/CT to reduce the
load or even to avoid packet-forwarding requests to nodes that have critical
battery life. First, the effectiveness of CB/CT in improving the signal
strength at a faraway destination using energy in nearby nodes is studied.
Then, the performance improvement obtained by this technique is analyzed for a
special 2D disk case. Further, for general networks in which
information-generation rates are fixed, a new routing problem is formulated as
a linear programming problem, while for other general networks, the cost for
routing is dynamically adjusted according to the amount of energy remaining and
the effectiveness of CB/CT. From the analysis and the simulation results, it is
seen that the proposed method can reduce the payloads of energy-depleting nodes
by about 90% in the special case network considered and improve the lifetimes
of general networks by about 10%, compared with existing techniques.


title: World Graph Formalism for Feynman Amplitudes

abstract:
  A unified treatment of Schwinger parametrised Feynman amplitudes is suggested
which addresses vertices of arbitrary order on the same footing as propagators.
Contributions from distinct diagrams are organised collectively. The scheme is
based on the continuous graph Laplacian. The analogy to a classical statistical
diffusion system of vector charges on the graph is explored.


title:
Exponential decay of correlation for the Stochastic Process associated
  to the Entropy Penalized Method

abstract:
  In this paper we present an upper bound for the decay of correlation for the
stationary stochastic process associated with the Entropy Penalized Method. Let
$L(x, v):\Tt^n\times\Rr^n\to \Rr$ be a Lagrangian of the form
  L(x,v) = {1/2}|v|^2 - U(x) + < P, v>.
  For each value of $\epsilon $ and $h$, consider the operator
  \Gg[\phi](x):= -\epsilon h {ln}[\int_{\re^N} e
^{-\frac{hL(x,v)+\phi(x+hv)}{\epsilon h}}dv], as well as the reversed operator
\bar \Gg[\phi](x):= -\epsilon h {ln}[\int_{\re^N}
e^{-\frac{hL(x+hv,-v)+\phi(x+hv)}{\epsilon h}}dv], both acting on continuous
functions $\phi:\Tt^n\to \Rr$. Denote by $\phi_{\epsilon,h} $ the solution of
$\Gg[\phi_{\epsilon,h}]=\phi_{\epsilon,h}+\lambda_{\epsilon,h}$, and by $\bar
\phi_{\epsilon,h} $ the solution of $\bar \Gg[\phi_{\epsilon,h}]=\bar
\phi_{\epsilon,h}+\lambda_{\epsilon,h}$. In order to analyze the decay of
correlation for this process we show that the operator $ {\cal L} (\phi) (x) =
\int e^{- \frac{h L (x,v)}{\epsilon}} \phi(x+h v) d v,$ has a maximal
eigenvalue isolated from the rest of the spectrum.


title:
Modelling the energy dependencies of high-frequency QPO in black hole
  X-ray binaries

abstract:
  We model energy dependencies of the quasi periodic oscillations (QPO) in the
model of disc epicyclic motions, with X-ray modulation caused by varying
relativistic effects. The model was proposed to explain the high frequency QPO
observed in X-ray binaries. We consider two specific scenarios for the geometry
of accretion flow and spectral formation. Firstly, a standard cold accretion
disc with an active X-ray emitting corona is assumed to oscillate. Secondly,
only a hot X-ray emitting accretion flow oscillates, while the cold disc is
absent at the QPO radius. We find that the QPO spectra are generally similar to
the spectrum of radiation emitted at the QPO radius, and they are broadened by
the relativistic effects. In particular, the QPO spectrum contains the disc
component in the oscillating disc with a corona scenario. We also review the
available data on energy dependencies of high frequency QPO, and we point out
that they appear to lack the disc component in their energy spectra. This would
suggest the hot flow geometry in the spectral states when high frequency QPO
are observed.


title: General-Purpose Computing on a Semantic Network Substrate

abstract:
  This article presents a model of general-purpose computing on a semantic
network substrate. The concepts presented are applicable to any semantic
network representation. However, due to the standards and technological
infrastructure devoted to the Semantic Web effort, this article is presented
from this point of view. In the proposed model of computing, the application
programming interface, the run-time program, and the state of the computing
virtual machine are all represented in the Resource Description Framework
(RDF). The implementation of the concepts presented provides a practical
computing paradigm that leverages the highly-distributed and standardized
representational-layer of the Semantic Web.


title:
Lifetime Improvement of Wireless Sensor Networks by Collaborative
  Beamforming and Cooperative Transmission

abstract:
  Extending network lifetime of battery-operated devices is a key design issue
that allows uninterrupted information exchange among distributive nodes in
wireless sensor networks. Collaborative beamforming (CB) and cooperative
transmission (CT) have recently emerged as new communication techniques that
enable and leverage effective resource sharing among collaborative/cooperative
nodes. In this paper, we seek to maximize the lifetime of sensor networks by
using the new idea that closely located nodes can use CB/CT to reduce the load
or even avoid packet forwarding requests to nodes that have critical battery
life. First, we study the effectiveness of CB/CT to improve the signal strength
at a faraway destination using energy in nearby nodes. Then, a 2D disk case is
analyzed to assess the resulting performance improvement. For general networks,
if information-generation rates are fixed, the new routing problem is
formulated as a linear programming problem; otherwise, the cost for routing is
dynamically adjusted according to the amount of energy remaining and the
effectiveness of CB/CT. From the analysis and simulation results, it is seen
that the proposed schemes can improve the lifetime by about 90% in the 2D disk
network and by about 10% in the general networks, compared to existing schemes.


title:
Quantized spin excitations in a ferromagnetic microstrip from microwave
  photovoltage measurements

abstract:
  Quantized spin excitations in a single ferromagnetic microstrip have been
measured using the microwave photovoltage technique. Several kinds of spin wave
modes due to different contributions of the dipole-dipole and the exchange
interactions are observed. Among them are a series of distinct dipole-exchange
spin wave modes, which allow us to determine precisely the subtle spin boundary
condition. A comprehensive picture for quantized spin excitations in a
ferromagnet with finite size is thereby established. The dispersions of the
quantized spin wave modes have two different branches separated by the
saturation magnetization.


title: Almost Product Evaluation of Hankel Determinants

abstract:
  An extensive literature exists describing various techniques for the
evaluation of Hankel determinants. The prevailing methods such as Dodgson
condensation, continued fraction expansion, LU decomposition, all produce
product formulas when they are applicable. We mention the classic case of the
Hankel determinants with binomial entries ${3k+2 \choose k}$ and those with
entries ${3k \choose k}$; both of these classes of Hankel determinants have
product form evaluations. The intermediate case, ${3k+1 \choose k}$ has not
been evaluated. There is a good reason for this: these latter determinants do
not have product form evaluations.
  In this paper we evaluate the Hankel determinant of ${3k+1 \choose k}$. The
evaluation is a sum of a small number of products, an almost product.
  The method actually provides more, and as applications, we present the
salient points for the evaluation of a number of other Hankel determinants with
polynomial entries, along with product and almost product form evaluations at
special points.


title:
Cooperative Transmission Protocols with High Spectral Efficiency and
  High Diversity Order Using Multiuser Detection and Network Coding

abstract:
  Cooperative transmission is an emerging communication technique that takes
advantages of the broadcast nature of wireless channels. However, due to low
spectral efficiency and the requirement of orthogonal channels, its potential
for use in future wireless networks is limited. In this paper, by making use of
multiuser detection (MUD) and network coding, cooperative transmission
protocols with high spectral efficiency, diversity order, and coding gain are
developed. Compared with the traditional cooperative transmission protocols
with single-user detection, in which the diversity gain is only for one source
user, the proposed MUD cooperative transmission protocols have the merits that
the improvement of one user's link can also benefit the other users. In
addition, using MUD at the relay provides an environment in which network
coding can be employed. The coding gain and high diversity order can be
obtained by fully utilizing the link between the relay and the destination.
  From the analysis and simulation results, it is seen that the proposed
protocols achieve higher diversity gain, better asymptotic efficiency, and
lower bit error rate, compared to traditional MUD and to existing cooperative
transmission protocols.


title:
Large deviation generating function for energy transport in the
  Pauli-Fierz model

abstract:
  We consider a finite quantum system coupled to quasifree thermal reservoirs
at different temperatures. Under the assumptions of small coupling and
exponential decay of the reservoir correlation function, the large deviation
generating function of energy transport into the reservoirs is shown to be
analytic on a bounded set. Our method is different from the spectral
deformation technique which was employed recently in the study of
spin-boson-like models. As a corollary, we derive the Gallavotti-Cohen
fluctuation relation for the entropy production and a central limit theorem for
energy transport.


title: Harmonic Generation from Laser-Irradiated Clusters

abstract:
  The harmonic emission from cluster nanoplasmas subject to short, intense
infrared laser pulses is analyzed by means of particle-in-cell simulations. A
pronounced resonant enhancement of the low-order harmonic yields is found when
the Mie plasma frequency of the ionizing and expanding cluster resonates with
the respective harmonic frequency. We show that a strong, nonlinear resonant
coupling of the cluster electrons with the laser field inhibits coherent
electron motion, suppressing the emitted radiation and restricting the spectrum
to only low-order harmonics. A pump-probe scheme is suggested to monitor the
ionization dynamics of the expanding clusters.


title: Diversity-Multiplexing Tradeoff in Selective-Fading MIMO Channels

abstract:
  We establish the optimal diversity-multiplexing (DM) tradeoff of coherent
time, frequency and time-frequency selective-fading MIMO channels and provide a
code design criterion for DM-tradeoff optimality. Our results are based on the
analysis of the "Jensen channel" associated to a given selective-fading MIMO
channel. While the original problem seems analytically intractable due to the
mutual information being a sum of correlated random variables, the Jensen
channel is equivalent to the original channel in the sense of the DM-tradeoff
and lends itself nicely to analytical treatment. Finally, as a consequence of
our results, we find that the classical rank criterion for space-time code
design (in selective-fading MIMO channels) ensures optimality in the sense of
the DM-tradeoff.


title:
Sparticle Spectra and LHC Signatures for Large Volume String
  Compactifications

abstract:
  We study the supersymmetric particle spectra and LHC collider observables for
the large-volume string models with a fundamental scale of 10^{11} GeV that
arise in moduli-fixed string compactifications with branes and fluxes. The
presence of magnetic fluxes on the brane world volume, required for chirality,
perturb the soft terms away from those previously computed in the dilute-flux
limit. We use the difference in high-scale gauge couplings to estimate the
magnitude of this perturbation and study the potential effects of the magnetic
fluxes by generating many random spectra with the soft terms perturbed around
the dilute flux limit. Even with a 40% variation in the high-scale soft terms
the low-energy spectra take a clear and predictive form. The resulting spectra
are broadly similar to those arising on the SPS1a slope, but more degenerate.
In their minimal version the models predict the ratios of gaugino masses to be
M_1 : M_2 : M_3=(1.5 - 2) : 2 : 6, different to both mSUGRA and mirage
mediation. Among the scalars, the squarks tend to be lighter and the sleptons
heavier than for comparable mSUGRA models. We generate 10 fb^{-1} of sample LHC
data for the random spectra in order to study the range of collider
phenomenology that can occur. We perform a detailed mass reconstruction on one
example large-volume string model spectrum. 100 fb^{-1} of integrated
luminosity is sufficient to discriminate the model from mSUGRA and aspects of
the sparticle spectrum can be accurately reconstructed.


title:
Smoothed Wigner transforms in the numerical simulation of semiclassical
  (high-frequency) wave propagation

abstract:
  The numerical simulation of wave propagation in semiclassical
(high-frequency) problems is well known to pose a formidable challenge. In this
work, a new phase-space approach for the numerical simulation of semiclassical
wave propagation, making use of the smoothed Wigner Transform (SWT), is
proposed. There are numerous works which use the Wigner Transform (WT) in the
study of a variety of wave propagation problems including high-frequency limits
for linear, nonlinear and/or random waves. The WT however is well known to
present significant difficulties in the formulation of numerical schemes.
Working with concrete examples for the semiclassical linear Schrodinger
equation it is seen that the SWT approach is indeed significantly faster (in a
well-defined sense) to work with than the WT and than full numerical solutions
of the original equation in the semiclassical regime. Comparisons with exact
and numerical solutions are used to keep track of numerical errors.


title: Estimation Diversity and Energy Efficiency in Distributed Sensing

abstract:
  Distributed estimation based on measurements from multiple wireless sensors
is investigated. It is assumed that a group of sensors observe the same
quantity in independent additive observation noises with possibly different
variances. The observations are transmitted using amplify-and-forward (analog)
transmissions over non-ideal fading wireless channels from the sensors to a
fusion center, where they are combined to generate an estimate of the observed
quantity. Assuming that the Best Linear Unbiased Estimator (BLUE) is used by
the fusion center, the equal-power transmission strategy is first discussed,
where the system performance is analyzed by introducing the concept of
estimation outage and estimation diversity, and it is shown that there is an
achievable diversity gain on the order of the number of sensors. The optimal
power allocation strategies are then considered for two cases: minimum
distortion under power constraints; and minimum power under distortion
constraints. In the first case, it is shown that by turning off bad sensors,
i.e., sensors with bad channels and bad observation quality, adaptive power
gain can be achieved without sacrificing diversity gain. Here, the adaptive
power gain is similar to the array gain achieved in Multiple-Input
Single-Output (MISO) multi-antenna systems when channel conditions are known to
the transmitter. In the second case, the sum power is minimized under
zero-outage estimation distortion constraint, and some related energy
efficiency issues in sensor networks are discussed.


title:
Propagation of external regulation and asynchronous dynamics in random
  Boolean networks

abstract:
  Boolean Networks and their dynamics are of great interest as abstract
modeling schemes in various disciplines, ranging from biology to computer
science. Whereas parallel update schemes have been studied extensively in past
years, the level of understanding of asynchronous updates schemes is still very
poor. In this paper we study the propagation of external information given by
regulatory input variables into a random Boolean network. We compute both
analytically and numerically the time evolution and the asymptotic behavior of
this propagation of external regulation (PER). In particular, this allows us to
identify variables which are completely determined by this external
information. All those variables in the network which are not directly fixed by
PER form a core which contains in particular all non-trivial feedback loops. We
design a message-passing approach allowing to characterize the statistical
properties of these cores in dependence of the Boolean network and the external
condition. At the end we establish a link between PER dynamics and the full
random asynchronous dynamics of a Boolean network.


title: On the generalized Freedman-Townsend model

abstract:
  Consistent interactions that can be added to a free, Abelian gauge theory
comprising a finite collection of BF models and a finite set of two-form gauge
fields (with the Lagrangian action written in first-order form as a sum of
Abelian Freedman-Townsend models) are constructed from the deformation of the
solution to the master equation based on specific cohomological techniques.
Under the hypotheses of smoothness in the coupling constant, locality, Lorentz
covariance, and Poincare invariance of the interactions, supplemented with the
requirement on the preservation of the number of derivatives on each field with
respect to the free theory, we obtain that the deformation procedure modifies
the Lagrangian action, the gauge transformations as well as the accompanying
algebra. The interacting Lagrangian action contains a generalized version of
non-Abelian Freedman-Townsend model. The consistency of interactions to all
orders in the coupling constant unfolds certain equations, which are shown to
have solutions.


title:
The Trade-off between Processing Gains of an Impulse Radio UWB System in
  the Presence of Timing Jitter

abstract:
  In time hopping impulse radio, $N_f$ pulses of duration $T_c$ are transmitted
for each information symbol. This gives rise to two types of processing gain:
(i) pulse combining gain, which is a factor $N_f$, and (ii) pulse spreading
gain, which is $N_c=T_f/T_c$, where $T_f$ is the mean interval between two
subsequent pulses. This paper investigates the trade-off between these two
types of processing gain in the presence of timing jitter. First, an additive
white Gaussian noise (AWGN) channel is considered and approximate closed form
expressions for bit error probability are derived for impulse radio systems
with and without pulse-based polarity randomization. Both symbol-synchronous
and chip-synchronous scenarios are considered. The effects of multiple-access
interference and timing jitter on the selection of optimal system parameters
are explained through theoretical analysis. Finally, a multipath scenario is
considered and the trade-off between processing gains of a synchronous impulse
radio system with pulse-based polarity randomization is analyzed. The effects
of the timing jitter, multiple-access interference and inter-frame interference
are investigated. Simulation studies support the theoretical results.


title:
Azimuthal decorrelation of Mueller-Navelet jets at the Tevatron and the
  LHC

abstract:
  We study the production of Mueller-Navelet jets at hadron colliders in the
Balitsky-Fadin-Kuraev-Lipatov (BFKL) framework. We show that a measurement of
the relative azimuthal angle \Delta\Phi between the jets can provide a good
testing ground for corrections due to next-leading logarithms (NLL). Besides
the well-known azimuthal decorrelation with increasing rapidity interval
\Delta\eta between the jets, we propose to also measure this effect as a
function of R=k_2/k_1, the ratio between the jets transverse momenta. Using
renormalisation-group improved NLL kernel, we obtain predictions for
d\sigma/d\Delta\eta dR d\Delta\Phi. We analyse NLL-scheme and
renormalisation-scale uncertainties, and energy-momentum conservation effects,
in order to motivate a measurement at the Tevatron and the LHC.


title: On the $p$-adic meromorphy of the function field height zeta function

abstract:
  In this brief note, we will investigate the number of points of bounded
(twisted) height in a projective variety defined over a function field, where
the function field comes from a projective variety of dimension greater than or
equal to 2. A first step in this investigation is to understand the $p$-adic
analytic properties of the height zeta function. In particular, we will show
that for a large class of projective varieties this function is $p$-adic
meromorphic.


title: Twisted conjugacy classes in R. Thompson's group F

abstract:
  In this short article, we prove that any automorphism of the R. Thompson's
group $F$ has infinitely many twisted conjugacy classes. The result follows
from the work of Matthew Brin, together with a standard facts on R. Thompson's
group $F$, and elementary properties of the Reidemeister numbers.


title:
The effect of dipole-dipole interactions between atoms in an active
  medium

abstract:
  Based on the results of numerical modeling, it is shown that dipole-dipole
interactions among atoms in the active medium influences strongly the character
of the associated superradiation. The main effect is to make the nuclear
subsystem behave chaotically. Its strength increases with the atom density, and
leads to the suppression of distant collective correlations and superradiation.
Near correlations between the atoms are established, causing a confinement
effect: a shielding of radiation in the active medium.


title: Constrained Supermanifolds for AdS M-Theory Backgrounds

abstract:
  A long standing problem is the supergauge completion of AdS_4 x (G/H)_7 or
AdS_5 x (G/H)_5 backgrounds which preserve less then maximal supersymmetry. In
parallel with the supersolvable realization of the AdS_4 x S^7 background based
on Kappa-symmetry, we develop a technique which amounts to solving the
above-mentioned problem in a way useful for pure spinor quantization for
supermembranes and superstrings. Instead of gauge fixing some of the superspace
coordinates to zero, we impose an additional constraint on them reproducing the
simplifications of the supersolvable representations. The constraints are
quadratic, homogeneous, Sp(4,R)-covariant, and consistent from the quantum
point of view in the pure spinor approach. Here we provide the geometrical
solution which, in a subsequent work, will be applied to the membrane and the
superstring sigma models.


title: Phantom field dynamics in loop quantum cosmology

abstract:
  We consider a dynamical system of phantom scalar field under exponential
potential in background of loop quantum cosmology. In our analysis, there is
neither stable node nor repeller unstable node but only two saddle points,
hence no Big Rip singularity. Physical solutions always possess potential
energy greater than magnitude of the negative kinetic energy. We found that the
universe bounces after accelerating even in the domination of the phantom
field. After bouncing, the universe finally enters oscillatory regime.


title: Quantum decoherence in the theory of open systems

abstract:
  In the framework of the Lindblad theory for open quantum systems, we
determine the degree of quantum decoherence of a harmonic oscillator
interacting with a thermal bath. It is found that the system manifests a
quantum decoherence which is more and more significant in time. We calculate
also the decoherence time scale and analyze the transition from quantum to
classical behaviour of the considered system.


title:
Complexity of Villamayor's algorithm in the non exceptional monomial
  case

abstract:
  We study monomial ideals, always locally given by a monomial, like a
reasonable first step to estimate in general the number of monoidal
transformations of Villamayor's algorithm of resolution of singularities. The
resolution of a monomial ideal $<X_1^{a_1}\cdot ... \cdot X_n^{a_n}>$ is
interesting due to its identification with the particular toric problem $<Z^c-
X_1^{a_1}\cdot ... \cdot X_n^{a_n}>$.
  In the special case, when all the exponents $a_i$ are greater than or equal
to the critical value $c$, we construct the largest branch of the resolution
tree which provides an upper bound involving partial sums of Catalan numbers.
This case will be called ``minimal codimensional case''. Partial sums of
Catalan numbers (starting $1,2,5,...$) are $1,3,8,22,...$ These partial sums
are well known in Combinatorics and count the number of paths starting from the
root in all ordered trees with $n+1$ edges. Catalan numbers appear in many
combinatorial problems, counting the number of ways to insert $n$ pairs of
parenthesis in a word of $n+1$ letters, plane trees with $n+1$ vertices, $...
$, etc.
  The non minimal case, when there exists some exponent $a_{i_0}$ smaller than
$c$, will be called ``case of higher codimension''. In this case, still
unresolved, we give an example to state the foremost troubles.
  Computation of examples has been helpful in both cases to study the behaviour
of the resolution invariant. Computations have been made in Singular (see
\cite{sing}) using the \emph{desing} package by G. Bodn\'ar and J. Schicho, see
\cite{lib}.


title: Cohomology of the minimal nilpotent orbit

abstract:
  We compute the integral cohomology of the minimal non-trivial nilpotent orbit
in a complex simple (or quasi-simple) Lie algebra. We find by a uniform
approach that the middle cohomology group is isomorphic to the fundamental
group of the sub-root system generated by the long simple roots. The modulo
$\ell$ reduction of the Springer correspondent representation involves the sign
representation exactly when $\ell$ divides the order of this cohomology group.
The primes dividing the torsion of the rest of the cohomology are bad primes.


title:
Fourteen New Companions from the Keck & Lick Radial Velocity Survey
  Including Five Brown Dwarf Candidates

abstract:
  We present radial velocities for 14 stars on the California & Carnegie Planet
Search target list that reveal new companions. One star, HD 167665, was fit
with a definitive Keplerian orbit leading to a minimum mass for the companion
of 50.3 Mjup at a separation from its host of ~5.5 AU. Incomplete or limited
phase coverage for the remaining 13 stars prevents us from assigning to them
unique orbital parameters. Instead, we fit their radial velocities with
Keplerian orbits across a grid of fixed values for Msini and period, P, and use
the resulting reduced chi-square surface to place constraints on Msini, P, and
semimajor axis, a. This technique allowed us to restrict Msini below the brown
dwarf -- stellar mass boundary for an additional 4 companions (HD 150554, HD
8765, HD 72780, HD 74014). If the combined 5 companions are confirmed as brown
dwarfs, these results would comprise the first major catch of such objects from
our survey beyond ~3 AU.


title:
Zakharov simulation study of spectral features of on-demand Langmuir
  turbulence in an inhomogeneous plasma

abstract:
  We have performed a simulation study of Langmuir turbulence in the Earth's
ionosphere by means of a Zakharov model with parameters relevant for the F
layer. The model includes dissipative terms to model collisions and Landau
damping of the electrons and ions, and a linear density profile, which models
the ionospheric plasma inhomogeneity whose length scale is of the order 10--100
km. The injection of energy into the system is modeled by a constant source
term in the Zakharov equation. Langmuir turbulence is excited ``on-demand'' in
controlled ionospheric modification experiments where the energy is provided by
an HF radio beam injected into the overhead ionospheric plasma. The ensuing
turbulence can be studied with radars and in the form of secondary radiation
recorded by ground-based receivers. We have analyzed spectral signatures of the
turbulence for different sets of parameters and different altitudes relative to
the turning point of the linear Langmuir mode where the Langmuir frequency
equals the local plasma frequency. By a parametric analysis, we have derived a
simple scaling law, which links the spectral width of the turbulent frequency
spectrum to the physical parameters in the ionosphere. The scaling law provides
a quantitative relation between the physical parameters (temperatures, electron
number density, ionospheric length scale, etc.) and the observed frequency
spectrum. This law may be useful for interpreting experimental results.


title: Lie fields revisited

abstract:
  A class of interacting classical random fields is constructed using deformed
*-algebras of creation and annihilation operators. The fields constructed are
classical random field versions of "Lie fields". A vacuum vector is used to
construct linear forms over the algebras, which are conjectured to be states
over the algebras. Assuming this conjecture is true, the fields constructed are
"quantum random fields" in the sense that they have Poincare invariant vacua
with a fluctuation scale determined by Planck's constant. A nonlocal particle
interpretation of the formalism is shown to be the same as a particle
interpretation of a quantum field theory.


title: Finite Gorenstein representation type implies simple singularity

abstract:
  Let R be a commutative noetherian local ring and consider the set of
isomorphism classes of indecomposable totally reflexive R-modules. We prove
that if this set is finite, then either it has exactly one element, represented
by the rank 1 free module, or R is Gorenstein and an isolated singularity (if R
is complete, then it is even a simple hypersurface singularity). The crux of
our proof is to argue that if the residue field has a totally reflexive cover,
then R is Gorenstein or every totally reflexive R-module is free.


title: Orthogonal complex structures on domains in R^4

abstract:
  An orthogonal complex structure on a domain in R^4 is a complex structure
which is integrable and is compatible with the Euclidean metric. This gives
rise to a first order system of partial differential equations which is
conformally invariant. We prove two Liouville-type uniqueness theorems for
solutions of this system, and use these to give an alternative proof of the
classification of compact locally conformally flat Hermitian surfaces first
proved by Pontecorvo. We also give a classification of non-degenerate quadrics
in CP^3 under the action of the conformal group. Using this classification, we
show that generic quadrics give rise to orthogonal complex structures defined
on the complement of unknotted solid tori which are smoothly embedded in R^4.


title:
Quantum Monte Carlo study of ring-shaped polariton parametric
  luminescence in a semiconductor microcavity

abstract:
  We present a quantum Monte Carlo study of the quantum correlations in the
parametric luminescence from semiconductor microcavities in the strong
exciton-photon coupling regime. As already demonstrated in recent experiments,
a ring-shaped emission is obtained by applying two identical pump beams with
opposite in-plane wavevectors, providing symmetrical signal and idler beams
with opposite in-plane wavevectors on the ring. We study the squeezing of the
signal-idler difference noise across the parametric instability threshold,
accounting for the radiative and non-radiative losses, multiple scattering and
static disorder. We compare the results of the complete multimode Monte Carlo
simulations with a simplified linearized quantum Langevin analytical model.


title: A New Proof of Pappus's Theorem

abstract:
  Any stretching of Ringel's non-Pappus pseudoline arrangement when projected
into the Euclidean plane, implicitly contains a particular arrangement of nine
triangles. This arrangement has a complex constraint involving the sines of its
angles. These constraints cannot be satisfied by any projection of the initial
arrangement. This is sufficient to prove Pappus's theorem. The derivation of
the constraint is via systems of inequalities arising from the polar
coordinates of the lines. These systems are linear in r for any given theta,
and their solubility can be analysed in terms of the signs of determinants. The
evaluation of the determinants is via a normal form for sums of products of
sines, giving a powerful system of trigonometric identities. The particular
result is generalized to arrangements derived from three edge connected totally
cyclic directed graphs, conjectured to be sufficient for a complete analysis of
angle constraining arrangements of lines, and thus a full response to Ringel's
slope conjecture. These methods are generally applicable to the realizability
problem for rank 3 oriented matroids.


title:
New Solvable Shape-Invariant Potentials for Position-Dependent Effective
  Mass

abstract:
  Four new exactly solvable, real and shape-invariant potentials associated
with a position-dependent effective mass are generated within the concept of
shape-invariant potentials using a specific ansatz for superpotential. The
accompanying energy spectra of the bound-state and the ground-state
wavefunction are obtained algebraically as a function of free parameters and
the results are compared with those of others works in the litterature.


title: Large Nongaussianity from Nonlocal Inflation

abstract:
  We study the possibility of obtaining large nongaussian signatures in the
Cosmic Microwave Background in a general class of single-field nonlocal
hill-top inflation models. We estimate the nonlinearity parameter f_{NL} which
characterizes nongaussianity in such models and show that large nongaussianity
is possible. For the recently proposed p-adic inflation model we find that
f_{NL} ~ 120 when the string coupling is order unity. We show that large
nongaussianity is also possible in a toy model with an action similar to those
which arise in string field theory.


title: Five-parameter family of partial differential systems in two variables

abstract:
  We find a five-parameter family of partial differential systems in two
variables with two polynomial Hamiltonians. We give its symmetry and holomorphy
conditions. These symmetries, holomorphy conditions and invariant divisors are
new.


title: Generation of strongly chaotic beats

abstract:
  The letter proposes a procedure for generation of strongly chaotic beats that
have been hardly obtainable hitherto. The beats are generated in a nonlinear
optical system governing second-harmonic generation of light. The proposition
is based on the concept of an optical coupler but can be easily adopted to
other nonlinear systems and Chua's circuits.


title: Light Propagation on Quantum Curved Spacetime and Back reaction effects

abstract:
  We study the electromagnetic field equations on an arbitrary quantum curved
background in the semiclassical approximation of Loop Quantum Gravity. The
effective interaction hamiltonian for the Maxwell and gravitational fields is
obtained and the corresponding field equations, which can be expressed as a
modified wave equation for the Maxwell potential, are derived. We use these
results to analyze electromagnetic wave propagation on a quantum
Robertson-Walker space time and show that Lorentz Invariance is not preserved.
The formalism developed can be applied to the case where back reaction effects
on the metric due to the electromagnetic field are taken into account, leading
to non covariant field equations.


title:
Prospects for precision measurements of atomic helium using direct
  frequency comb spectroscopy

abstract:
  We analyze several possibilities for precisely measuring electronic
transitions in atomic helium by the direct use of phase-stabilized femtosecond
frequency combs. Because the comb is self-calibrating and can be shifted into
the ultraviolet spectral region via harmonic generation, it offers the prospect
of greatly improved accuracy for UV and far-UV transitions. To take advantage
of this accuracy an ultracold helium sample is needed. For measurements of the
triplet spectrum a magneto-optical trap (MOT) can be used to cool and trap
metastable 2^3S state atoms. We analyze schemes for measuring the two-photon
$2^3S \to 4^3S$ interval, and for resonant two-photon excitation to high
Rydberg states, $2^3S \to 3^3P \to n^3S,D$. We also analyze experiments on the
singlet-state spectrum. To accomplish this we propose schemes for producing and
trapping ultracold helium in the 1^1S or 2^1S state via intercombination
transitions. A particularly intriguing scenario is the possibility of measuring
the $1^1S \to 2^1S$ transition with extremely high accuracy by use of
two-photon excitation in a magic wavelength trap that operates identically for
both states. We predict a ``triple magic wavelength'' at 412 nm that could
facilitate numerous experiments on trapped helium atoms, because here the
polarizabilities of the 1^1S, 2^1S and 2^3S states are all similar, small, and
positive.


title:
Suppressed radio emission in supercluster galaxies: enhanced ram
  pressure in merging clusters?

abstract:
  The environmental influence on the 1.4 GHz continuum radio emission of
galaxies is analyzed in a 600 deg2 region of the local Universe containing the
Shapley Supercluster (SSC). Galaxies in the FLASH and 6dFGS redshift surveys
are cross-identified with NVSS radio sources, selected in a subsample doubly
complete in volume and luminosity. Environmental effects are studied through a
smoothed density field (normalized with random catalogs with the same survey
edges and redshift selection function) and the distance to the nearest cluster
(R/r200, where r200 is the virial radius, whose relation to the aperture
velocity dispersion is quantified). The fraction of high radio loudness
(R_K=L_radio/L_K) galaxies in the 10 Mpc Abell 3558 cluster complex at the core
of the SSC (SSC-CR) is half as large than elsewhere. In the SSC-CR, R_K is
anti-correlated with the density of the large-scale environment and correlated
with R/r200: central brightest cluster galaxies (BCGs) in the SSC-CR are 10x
less radio-loud than BCGs elsewhere, with signs of suppressed radio loudness in
the SSC-CR also present beyond the BCGs, out to at least 0.3 r200. This
correlation is nearly as strong as the tight correlation of L_K with R/r200
(K-luminosity segregation), inside the SSC-CR. The suppression of radio
loudness in SSC-CR BCGs can be attributed to cluster-cluster mergers that
destroy the cool core and thus the supply of gas to the central AGN. We
analytically demonstrate that the low radio loudness of non-BCG galaxies within
SSC-CR clusters cannot be explained by direct major galaxy mergers or rapid
galaxy flyby collisions, but by the loss of gas supply through the enhanced ram
pressure felt when these galaxies cross the shock front between the 2 merging
clusters and are later subjected to the stronger wind from the 2nd cluster.


title:
Quantum simulators, continuous-time automata, and translationally
  invariant systems

abstract:
  The general problem of finding the ground state energy of lattice
Hamiltonians is known to be very hard, even for a quantum computer. We show
here that this is the case even for translationally invariant systems. We also
show that a quantum computer can be built in a 1D chain with a fixed,
translationally invariant Hamitonian consisting of nearest--neighbor
interactions only. The result of the computation is obtained after a prescribed
time with high probability.


title: Bayesian approach to rough set

abstract:
  This paper proposes an approach to training rough set models using Bayesian
framework trained using Markov Chain Monte Carlo (MCMC) method. The prior
probabilities are constructed from the prior knowledge that good rough set
models have fewer rules. Markov Chain Monte Carlo sampling is conducted through
sampling in the rough set granule space and Metropolis algorithm is used as an
acceptance criteria. The proposed method is tested to estimate the risk of HIV
given demographic data. The results obtained shows that the proposed approach
is able to achieve an average accuracy of 58% with the accuracy varying up to
66%. In addition the Bayesian rough set give the probabilities of the estimated
HIV status as well as the linguistic rules describing how the demographic
parameters drive the risk of HIV.


title:
On sensing capacity of sensor networks for the class of linear
  observation, fixed SNR models

abstract:
  In this paper we address the problem of finding the sensing capacity of
sensor networks for a class of linear observation models and a fixed SNR
regime. Sensing capacity is defined as the maximum number of signal dimensions
reliably identified per sensor observation. In this context sparsity of the
phenomena is a key feature that determines sensing capacity. Precluding the SNR
of the environment the effect of sparsity on the number of measurements
required for accurate reconstruction of a sparse phenomena has been widely
dealt with under compressed sensing. Nevertheless the development there was
motivated from an algorithmic perspective. In this paper our aim is to derive
these bounds in an information theoretic set-up and thus provide algorithm
independent conditions for reliable reconstruction of sparse signals. In this
direction we first generalize the Fano's inequality and provide lower bounds to
the probability of error in reconstruction subject to an arbitrary distortion
criteria. Using these lower bounds to the probability of error, we derive upper
bounds to sensing capacity and show that for fixed SNR regime sensing capacity
goes down to zero as sparsity goes down to zero. This means that
disproportionately more sensors are required to monitor very sparse events. Our
next main contribution is that we show the effect of sensing diversity on
sensing capacity, an effect that has not been considered before. Sensing
diversity is related to the effective \emph{coverage} of a sensor with respect
to the field. In this direction we show the following results (a) Sensing
capacity goes down as sensing diversity per sensor goes down; (b) Random
sampling (coverage) of the field by sensors is better than contiguous location
sampling (coverage).


title: Spontaneous chirality via long-range electrostatic forces

abstract:
  We consider a model for periodic patterns of charges constrained over a
cylindrical surface. In particular we focus on patterns of chiral helices,
achiral rings or vertical lamellae, with the constraint of global
electroneutrality. We study the dependence of the patterns' size and pitch
angle on the radius of the cylinder and salt concentration. We obtain a phase
diagram by using numerical and analytic techniques. For pure Coulomb
interactions, we find a ring phase for small radii and a chiral helical phase
for large radii. At a critical salt concentration, the characteristic domain
size diverges, resulting in macroscopic phase segregation of the components and
restoring chiral symmetry. We discuss possible consequences and generalizations
of our model.


title:
Mesoscopic fluctuations of the supercurrent in diffusive Josephson
  junctions

abstract:
  We study mesoscopic fluctuations and weak localization correction to the
supercurrent in Josephson junctions with coherent diffusive electron dynamics
in the normal part. Two kinds of junctions are considered: a chaotic dot
coupled to superconductors by tunnel barriers and a diffusive junction with
transparent normal--superconducting interfaces. The amplitude of current
fluctuations and the weak localization correction to the average current are
calculated as functions of the ratio between the superconducting gap and the
electron dwell energy, temperature, and superconducting phase difference across
the junction. Technically, fluctuations on top of the spatially inhomogeneous
proximity effect in the normal region are described by the replicated version
of the \sigma-model. For the case of diffusive junctions with transparent
interfaces, the magnitude of mesoscopic fluctuations of the critical current
appears to be nearly 3 times larger than the prediction of the previous theory
which did not take the proximity effect into account.


title:
Stellar kinematics in the remote Leo II dwarf spheroidal galaxy --
  Another brick in the wall

abstract:
  We present the projected velocity dispersion profile for the remote
(d=233kpc) Galactic dwarf spheroidal (dSph) galaxy Leo II, based on 171
discrete stellar radial velocities that were obtained from medium-resolution
spectroscopy using the FLAMES/GIRAFFE spectrograph at the European Southern
Observatory, Chile. The dispersion profile of those stars with good membership
probabilities is essentially flat with an amplitude of 6.6+-0.7 km/s over the
full radial extent of our data, which probe to the stellar boundary of this
galaxy. We find no evidence of any significant apparent rotation or velocity
asymmetry which suggests that tidal effects cannot be invoked to explain Leo
II's properties. From basic mass modeling, employing Jeans' equation, we derive
a mass out to the limiting radius of (2.7+-0.5) 10^7 Msun and a global mass to
light ratio of 27-45 in solar units, depending on the adopted total luminosity.
A cored halo profile and a mild amount of tangential velocity anisotropy is
found to account well for Leo II's observed kinematics, although we cannot
exclude the possibility of a cusped halo with radially varying velocity
anisotropy. All in all, this galaxy exhibits dark matter properties which
appear to be concordant with the other dSph satellites of the Milky Way, namely
a halo mass profile which is consistent with a central core and a total mass
which is similar to the common mass scale seen in other dSphs.


title: Black-body components in Gamma-Ray Bursts spectra?

abstract:
  We study 7 Gamma Ray Bursts (GRBs), detected both by the BATSE instrument,
on-board the Compton Gamma Ray Observatory, and by the Wide Field Camera (WFC),
on-board BeppoSAX. These bursts have measured spectroscopic redshifts and are a
sizeable fraction of the bursts defining the correlation between the peak
energy E_peak (i.e. the peak of the vFv spectrum) and the total prompt
isotropic energy E_iso (the so called "Amati" relation). Recent theoretical
interpretations of this correlation assume that black-body emission dominates
the time resolved spectra of GRBs, even if, in the time integrated spectrum,
its presence may be hidden by the change of its temperature and by the dilution
of a possible non-thermal power law component. We perform a time resolved
spectral analysis, and show that the sum of a power-law and a black-body gives
acceptable fits to the time dependent spectra within the BATSE energy range,
but overpredicts the flux in the WFC X-ray range. Moreover, a fit with a cutoff
power-law plus a black-body is consistent with the WFC data, but the black-body
component contributes a negligible fraction of the total flux. On the contrary,
we find that fitting the spectra with a Band model or a simple cutoff power-law
model yields an X-ray flux and spectral slope which well matches the WFC
spectra.


title: The symmetric heavy-light ansatz

abstract:
  The symmetric heavy-light ansatz is a method for finding the ground state of
any dilute unpolarized system of attractive two-component fermions.
Operationally it can be viewed as a generalization of the Kohn-Sham equations
in density functional theory applied to N-body density correlations. While the
original Hamiltonian has an exact Z_2 symmetry, the heavy-light ansatz breaks
this symmetry by skewing the mass ratio of the two components. In the limit
where one component is infinitely heavy, the many-body problem can be solved in
terms of single-particle orbitals. The original Z_2 symmetry is recovered by
enforcing Z_2 symmetry as a constraint on N-body density correlations for the
two components. For the 1D, 2D, and 3D attractive Hubbard models the method is
in very good agreement with exact Lanczos calculations for few-body systems at
arbitrary coupling. For the 3D attractive Hubbard model there is very good
agreement with lattice Monte Carlo results for many-body systems in the limit
of infinite scattering length.


title:
Dynamical models and the phase ordering kinetics of the s=1 spinor
  condensate

abstract:
  The $s=1$ spinor Bose condensate at zero temperature supports ferromagnetic
and polar phases that combine magnetic and superfluid ordering. We investigate
the formation of magnetic domains at finite temperature and magnetic field in
two dimensions in an optical trap. We study the general ground state phase
diagram of a spin-1 system and focus on a phase that has a magnetic Ising order
parameter and numerically determine the nature of the finite temperature
superfluid and magnetic phase transitions. We then study three different
dynamical models: model A, which has no conserved quantities, model F, which
has a conserved second sound mode and the Gross-Pitaevskii (GP) equation which
has a conserved density and magnetization. We find the dynamic critical
exponent to be the same for models A and F ($z=2$) but different for GP ($z
\approx 3$). Externally imposed magnetization conservation in models A and F
yields the value $z \approx 3$, which demonstrates that the only conserved
density relevant to domain formation is the magnetization density.


title:
Anisotropic Locations of Satellite Galaxies: Clues to the Orientations
  of Galaxies within their Dark Matter Halos

abstract:
  We investigate the locations of the satellites of relatively isolated host
galaxies in the Sloan Digital Sky Survey and the Millennium Run simulation.
Provided we use two distinct prescriptions to embed luminous galaxies within
the simulated dark matter halos (ellipticals share the shapes of their halos,
while disks have angular momenta that are aligned with the net angular momenta
of their halos), we find a fair agreement between observation and theory.
Averaged over scales r_p \le 500 kpc, the satellites of red, high-mass hosts
with low star formation rates are found preferentially near the major axes of
their hosts. In contrast, the satellites of blue, low-mass hosts with low star
formation rates show little to no anisotropy when averaged over the same scale.
The difference between the locations of the satellites of red and blue hosts
cannot be explained by the effects of interlopers in the data. Instead, it is
caused primarily by marked differences in the dependence of the mean satellite
location, <\phi>, on the projected distance at which the satellites are found.
We also find that the locations of red, high-mass satellites with low star
formation rates show considerably more anisotropy than do the locations of
blue, low--mass satellites with high star formation rates. There are two
contributors to this result. First, the blue satellites have only recently
arrived within their hosts' halos, while the red satellites arrived in the far
distant past. Second, the sample of blue satellites is heavily contaminated by
interlopers, which suppresses the measured anisotropy compared to the intrinsic
anisotropy.


title: 1/2-BPS states in M theory and defects in the dual CFTs

abstract:
  We study supersymmetric branes in AdS_7 x S^4 and AdS_4 x S^7. We show that
in the former case the membranes should be viewed as M5 branes with fluxes and
we identify two types of such fivebranes (they are analogous to giant gravitons
and to dual giants). In AdS_4 x S^7 we find both M5 branes with fluxes and
freestanding stacks of membranes. We also go beyond probe approximation and
construct regular supergravity solutions describing geometries produced by the
branes. The metrics are completely specified by one function which satisfies
either Laplace or Toda equation and we give a complete classification of
boundary conditions leading to smooth geometries. The brane configurations
discussed in this paper are dual to various defects in three- and
six-dimensional conformal field theories.


title: Corestrictions of algebras and splitting fields

abstract:
  Given a field $F$, an \'etale extension $L/F$ and an Azumaya algebra $A/L$,
one knows that there are extensions $E/F$ such that $A \otimes_F E$ is a split
algebra over $L \otimes_F E$. In this paper we bound the degree of a minimal
splitting field of this type from above and show that our bound is sharp in
certain situations, even in the case where $L/F$ is a split extension. This
gives in particular a number of generalizations of the classical fact that when
the tensor product of two quaternion algebras is not a division algebra, the
two quaternion algebras must share a common quadratic splitting field.
  In another direction, our constructions combined with results of Karpenko
also show that for any odd prime number $p$, the generic algebra of index
$p^n$, and exponent $p$ cannot be expressed nontrivially as the corestriction
of an algebra over any extension field if $n < p^2$.


title: A Symmetric Free Energy Based Multi-Component Lattice Boltzmann Method

abstract:
  We present a lattice Boltzmann algorithm based on an underlying free energy
that allows the simulation of the dynamics of a multicomponent system with an
arbitrary number of components. The thermodynamic properties, such as the
chemical potential of each component and the pressure of the overall system,
are incorporated in the model. We derived a symmetrical convection diffusion
equation for each component as well as the Navier Stokes equation and
continuity equation for the overall system. The algorithm was verified through
simulations of binary and ternary systems. The equilibrium concentrations of
components of binary and ternary systems simulated with our algorithm agree
well with theoretical expectations.


title: Lower Spectral Branches of a Spin-Boson Model

abstract:
  We study the structure of the spectrum of a two-level quantum system weakly
coupled to a boson field (spin-boson model). Our analysis allows to avoid the
cutoff in the number of bosons, if their spectrum is bounded below by a
positive constant. We show that, for small coupling constant, the lower part of
the spectrum of the spin-boson Hamiltonian contains (one or two) isolated
eigenvalues and (respectively, one or two) manifolds of atom $+ 1$-boson states
indexed by the boson momentum $q$. The dispersion laws and generalized
eigenfunctions of the latter are calculated.