title:
Rapidly detecting disorder in rhythmic biological signals: A spectral
  entropy measure to identify cardiac arrhythmias

abstract:
  We consider the use of a running measure of power spectrum disorder to
distinguish between the normal sinus rhythm of the heart and two forms of
cardiac arrhythmia: atrial fibrillation and atrial flutter. This spectral
entropy measure is motivated by characteristic differences in the spectra of
beat timings during the three rhythms. We plot patient data derived from
ten-beat windows on a "disorder map" and identify rhythm-defining ranges in the
level and variance of spectral entropy values. Employing the spectral entropy
within an automatic arrhythmia detection algorithm enables the classification
of periods of atrial fibrillation from the time series of patients' beats. When
the algorithm is set to identify abnormal rhythms within 6 s it agrees with
85.7% of the annotations of professional rhythm assessors; for a response time
of 30 s this becomes 89.5%, and with 60 s it is 90.3%. The algorithm provides a
rapid way to detect atrial fibrillation, demonstrating usable response times as
low as 6 s. Measures of disorder in the frequency domain have practical
significance in a range of biological signals: the techniques described in this
paper have potential application for the rapid identification of disorder in
other rhythmic signals.


title:
A stroll among effective temperatures in aging systems: limits and
  perspectives

abstract:
  In this paper we present a short survey on the concept of effective
temperature, on its onset as a glass former vitrifies, on the various
definitions in literature and their limits of applicability. An exactly
solvable model glass is employed to compare effective temperatures among them
and to set a criterion for the occurrence of a universal extra temperature in
the framework of a "two temperature thermodynamics" for off-equilibrium aging
systems. It will be shown that aging in glass formers is not a sufficient
requirement. As an instance, memory effects typical of glasses are not
compatible with a unique effective temperature. Yet, a reduced range of
applicability can still be established and investigated.


title:
Isospin dependence of the eta prime meson production in nucleon-nucleon
  collisions

abstract:
  A comparison of the close-to-threshold total cross section for the eta prime
production in pp --> pp eta prime and pn --> pn eta prime reactions constitutes
a tool to investigate the eta prime meson structure and the reaction mechanism
in the channels of isospin I=0 and I=1 and may provide insight into the
flavour-singlet (perhaps also into gluonium) content of the eta prime meson. In
this contribution we present preliminary results of measurement of the
quasi-free production of the eta prime meson in the proton-neutron collisions
conducted using the COSY-11 facility.


title: Self-induced parametric resonance in collective neutrino oscillations

abstract:
  We identify a generic new form of collective flavor oscillations in dense
neutrino gases that amounts to a self-induced parametric resonance. It occurs
in a homogeneous and isotropic ensemble when a range of neutrino modes is
prepared in a different flavor than the neighboring modes with lower and higher
energies. The flavor content of the intermediate spectral part librates
relative to the other parts with a frequency corresponding to a typical Delta
m^2/2E. This libration persists in the limit of an arbitrarily large neutrino
density where one would have expected synchronized flavor oscillations.


title:
The rough path associated to the multidimensional analytic fbm with any
  Hurst parameter

abstract:
  In this paper, we consider a complex-valued d-dimensional fractional Brownian
motion defined on the closure of the complex upper half-plane, called analytic
fractional Brownian motion. This process has been introduced by the second
author of the article, and both its real and imaginary parts, restricted on the
real axis, are usual fractional Brownian motions. The current note is devoted
to prove that a rough path based on the analytic fBm can be constructed for any
value of the Hurst parameter in (0,1/2). This allows in particular to solve
differential equations driven by this process in a neighborhood of 0 of the
complex upper half-plane, thanks to a variant of the usual rough path theory
due to Gubinelli.


title:
Optical and near-IR photometric study of the open cluster NGC 637 and
  NGC 957

abstract:
  We present UBVRI CCD photometry in the region of the open clusters NGC 637
and NGC 957. The radii are found to be 4.2 arcmin and 4.3 arcmin. Their
reddenings E(B-V) are 0.64+/-0.05 mag and 0.71+/-0.05 mag and their distances,
from main sequence fitting are 2.5+/-0.2 kpc and 2.2+/-0.2 kpc. Comparison with
Z=0.02 isochrones leads to an age of 10+/-5 Myr for both clusters. Combining
our photometry with 2MASS JHK shows the reddening law in these directions to be
normal. Mass function slopes of x=1.65+/-0.20 and 1.31+/-0.50 are derived for
the clusters, both of which are found to be dynamically relaxed. Spectral and
photometric characteristics of three Be stars, two in NGC 957 and one (newly
discovered) in NGC 637 indicate them to be of Classical Be type.


title:
Role of dynamical non-double-occupancy excitations on the quasiparticle
  damping of the $t-J$ model in the large-$N$ limit

abstract:
  One-electron self-energy in the $t$-$J$ model was computed using a recently
developed large-$N$ method based on the path integral representation for
Hubbard operators. One of the main features of the self-energy is its strong
asymmetry with respect to the Fermi level, showing the spectra mostly
concentrated at high negative energy. This asymmetry is responsible for the
existence of incoherent structures at high negative energy in the spectral
functions. It is shown that dynamical non-double-occupancy excitations are
relevant for the behavior of the self-energy. It is difficult to understand the
asymmetry shown by the self-energy from weak coupling treatments. We compare
our results with others in recent literature. Finally, the possible relevance
of our results for the recent high energy features observed in photoemission
experiments is discussed.


title:
On the density of states and extinction mean free path of waves in
  random media: Dispersion relations and sum rules

abstract:
  We establish a fundamental relationship between the averaged density of
states and the extinction mean free path of wave propagating in random media.
  From the principle of causality and the Kramers-Kronig relations, we show
that both quantities are connected by dispersion relations and are constrained
by a frequency sum rule. The results are valid under very general conditions
and should be helpful in the analysis of measurements of wave transport through
complex systems and in the design of randomly or periodically structured
materials with specific transport properties.


title: The Path-Integral Approach to Spontaneous Symmetry Breaking

abstract:
  We will investigate two models which exhibit SSB in the canonical approach:
the N=1 and N=2 linear sigma model. In both models the Green's functions and
the effective potential will be computed in the path-integral approach. We will
demonstrate how we get different results than in the canonical approach.


title:
Spin-dephasing anisotropy for electrons in a diffusive quasi-1D GaAs
  wire

abstract:
  We present a numerical study of dephasing of electron spin ensembles in a
diffusive quasi-one-dimensional GaAs wire due to the D'yakonov-Perel'
spin-dephasing mechanism. For widths of the wire below the spin precession
length and for equal strength of Rashba and linear Dresselhaus spin-orbit
fields a strong suppression of spin-dephasing is found. This suppression of
spin-dephasing shows a strong dependence on the wire orientation with respect
to the crystal lattice. The relevance for realistic cases is evaluated by
studying how this effect degrades for deviating strength of Rashba and linear
Dresselhaus fields, and with the inclusion of the cubic Dresselhaus term.


title:
Critical exponents of one-dimensional quantum critical models by means
  of MERA tensor network

abstract:
  An algorithm for optimizing the MERA tensor network in an infinite system is
presented. Using this technique we compute the critical exponents of Ising and
XXZ model.


title: Magnetic Braiding and Parallel Electric Fields

abstract:
  The braiding of the solar coronal magnetic field via photospheric motions -
with subsequent relaxation and magnetic reconnection -- is one of the most
widely debated ideas of solar physics. We readdress the theory in the light of
developments in three-dimensional magnetic reconnection theory. It is known
that the integrated parallel electric field along field lines is the key
quantity determining the rate of reconnection, in contrast with the
two-dimensional case where the electric field itself is the important quantity.
We demonstrate that this difference becomes crucial for sufficiently complex
magnetic field structures.
  A numerical method is used to relax a braided magnetic field to an ideal
force-free equilibrium; that equilibrium is found to be smooth, with only
large- scale current structures. However, the equilibrium is shown to have a
highly filamentary integrated parallel current structure with extremely short
length- scales. An analytical model is developed to show that, in a coronal
situation, the length scales associated with the integrated parallel current
structures will rapidly decrease with increasing complexity, or degree of
braiding, of the magnetic field. Analysis shows the decrease in these length
scales will, for any finite resistivity, eventually become inconsistent with
the stability of a force- free field. Thus the inevitable consequence of the
magnetic braiding process is shown to be a loss of equilibrium of the coronal
field, probably via magnetic reconnection events.


title:
Neutrino detection of transient sources with optical follow-up
  observations

abstract:
  The ANTARES telescope has the opportunity to detect transient neutrino
sources, such as gamma-ray bursts (GRBs), core-collapse supernovae (SNe),
flares of active galactic nuclei (AGNs)... To enhance the sensitivity to these
sources, we are developing a new detection method based on the observation of
neutrino bursts followed by an optical detection. The ANTARES Collaboration is
implementing a fast on-line event reconstruction with a good angular
resolution. These characteristics allow to trigger an optical telescope network
in order to identify the nature of the neutrinos (and high energy cosmic-rays)
sources. This follow-up can be done with a network of small automatic
telescopes and required a small observation time. An optical follow-up of
special events, such as neutrino doublets in coincidence in time and space or
single neutrino having a very high energy, would not only give access to the
nature of the sources but also improve the sensitivity for neutrino detection
from SNe or GRBs.


title: Optimal purification of a generic n-qudit state

abstract:
  We propose a quantum algorithm for the purification of a generic mixed state
$\rho$ of a $n$-qudit system by using an ancillary $n$-qudit system. The
algorithm is optimal in that (i) the number of ancillary qudits cannot be
reduced, (ii) the number of parameters which determine the purification state
$|\Psi>$ exactly equals the number of degrees of freedom of $\rho$, and (iii)
$|\Psi>$ is easily determined from the density matrix $\rho$. Moreover, we
introduce a quantum circuit in which the quantum gates are unitary
transformations acting on a $2n$-qudit system. These transformations are
determined by parameters that can be tuned to generate, once the ancillary
qudits are disregarded, any given mixed $n$-qudit state.


title:
Synthesizing and characterization of hole doped nickel based
  superconductor (La$_{1-x}$Sr$_{x}$)NiAsO

abstract:
  We report the synthesizing and characterization of the hole doped Ni-based
superconductor ($La_{1-x}Sr_{x})NiAsO$. By substituting La with Sr, the
superconducting transition temperature $T_c$ is increased from 2.4 K of the
parent phase $LaNiAsO$ to 3.7 K at the doping levels x= 0.1 - 0.2. The curve
$T_c$ versus hole concentration shows a symmetric behavior as the electron
doped samples $LaNiAs(O_{1-x}F_{x})$. The normal state resistivity in Ni-based
samples shows a good metallic behavior and reveals the absence of spin density
wave induced anomaly which appears in the Fe-based system at about 150 K. Hall
effect measurements indicate that the electron conduction in the parent phase
$LaNiAsO$ is dominated by electron-like charge carriers, while with more Sr
doping, a hole-like band will emerge and finally prevail over the conduction,
such a phenomenon reflects that the Fermi surface of $LaNiAsO$ comprises of
electron pockets and hole pockets, thus the sign of charge carriers could be
changed once the contribution of hole pockets overwhelms that of electron
pockets. Magnetoresistance measurements and the violation of Kohler rule
provide further proof that multiband effect dominate the normal state transport
of ($La_{1-x}Sr_{x})NiAsO$.


title:
Hamiltonian inclusions with convex dissipation with a view towards
  applications

abstract:
  We propose a generalization of hamiltonian mechanics, as a hamiltonian
inclusion with convex dissipation function. We obtain a dynamical version of
the approach of Mielke to quasistatic rate-independent processes. Then we show
that a class of models of dynamical brittle damage can be formulated in this
setting.


title: Search for contact interactions at HERA

abstract:
  The H1 and ZEUS collaborations at HERA have searched for signatures of
physics beyond the Standard Model using high Q^2 neutral current deep inelastic
electron-proton and positron-proton scattering events. No significant
deviations from Standard Model predictions were observed. Various eeqq contact
interaction models have been considered. Limits on the compositeness scale in
general eeqq contact interaction models, mass to the Yukawa coupling ratio for
heavy leptoquarks, the effective Planck mass scale in models with large extra
dimensions and the effective quark charge radius are presented.


title: Theoretical Overview of Neutrino Properties

abstract:
  I give an overview of some basic properties of massive neutrinos. The first
part of this talk is devoted to three fundamental questions about three known
neutrinos and to their flavor issues -- the mass spectrum, mixing pattern and
CP violation. The second part of this talk is to highlight a few hot topics at
the frontiers of neutrino physics and neutrino astrophysics, including the
naturalness and testability of TeV seesaw mechanisms at the LHC, effects of
non-standard interactions on neutrino oscillations, flavor distributions of
ultrahigh-energy cosmic neutrinos at neutrino telescopes, collective flavor
oscillations of supernova neutrinos, flavor effects in thermal leptogenesis,
the GSI anomaly and Moessbauer neutrino oscillations, and so on. I finally make
some concluding remarks for the road ahead.


title:
A bijection between noncrossing and nonnesting partitions of types A and
  B

abstract:
  The total number of noncrossing partitions of type $\Psi$ is the $n$th
Catalan number $\frac{1}{n+1}\binom{2n}{n}$ when $\Psi=A_{n-1}$, and the
binomial $\binom{2n}{n}$ when $\Psi=B_n$, and these numbers coincide with the
correspondent number of nonnesting partitions. For type A, there are several
bijective proofs of this equality, being the intuitive map that locally
converts each crossing to a nesting one of them. In this paper we present a
bijection between nonnesting and noncrossing partitions of types A and B that
generalizes the type A bijection that locally converts each crossing to a
nesting.


title: Multi-particle correlation function to study short-lived nuclei

abstract:
  Unstable 10C nuclei are produced as quasi-projectiles in 12C+24Mg collisions
at E/A = 53 and 95 MeV. The decay of their short-lived states is studied with
the INDRA multidetector array via multi-particle correlation functions. The
obtained results show that heavy-ion collisions can be used as a tool to access
spectroscopic information of unbound states in exotic nuclei, such as their
energies and the relative importance of different sequential decay widths.


title: "Real" Slepian-Wolf Codes

abstract:
  We provide a novel achievability proof of the Slepian-Wolf theorem for i.i.d.
sources over finite alphabets. We demonstrate that random codes that are linear
over the real field achieve the classical Slepian-Wolf rate-region. For finite
alphabets we show that typicality decoding is equivalent to solving an integer
program. Minimum entropy decoding is also shown to achieve exponentially small
probability of error. The techniques used may be of independent interest for
code design for a wide class of information theory problems, and for the field
of compressed sensing.


title:
Hodge polynomials and birational types of moduli spaces of coherent
  systems on elliptic curves

abstract:
  In this paper we consider moduli spaces of coherent systems on an elliptic
curve. We compute their Hodge polynomials and determine their birational types
in some cases. Moreover we prove that certain moduli spaces of coherent systems
are isomorphic. This last result uses the Fourier-Mukai transform of coherent
systems introduced by Hern\'andez Ruiperez and Tejero Prieto.


title: Modeling a Century of Citation Distributions

abstract:
  Changes in citation distributions over 100 years can reveal much about the
evolution of the scientific communities or disciplines. The prevalence of
uncited papers or of highly-cited papers, with respect to the bulk of
publications, provides important clues as to the dynamics of scientific
research. Using 25 million papers and 600 million references from the Web of
Science over the 1900-2006 period, this paper proposes a simple model based on
a random selection process to explain the "uncitedness" phenomenon and its
decline in recent years. We show that the proportion of uncited papers is a
function of 1) the number of articles published in a given year (the competing
papers) and 2) the number of articles subsequently published (the citing
papers) and the number of references they contain. Using uncitedness as a
departure point, we demonstrate the utility of the stretched-exponential
function and a form of the Tsallis function to fit complete citation
distributions over the 20th century. As opposed to simple power-law fits, for
instance, both these approaches are shown to be empirically well-grounded and
robust enough to better understand citation dynamics at the aggregate level.
Based on an expansion of these models, on our new understanding of uncitedness
and on our large dataset, we are able provide clear quantitative evidence and
provisional explanations for an important shift in citation practices around
1960, unmatched in the 20th century. We also propose a revision of the
"citation classic" category as a set of articles which is clearly
distinguishable from the rest of the field.


title:
A Non-minimally Coupled Quintom Dark Energy Model on the Warped DGP
  Brane

abstract:
  We study dynamics of equation of state parameter for a non-minimally coupled
quintom dark energy component on the warped DGP brane. We investigate crossing
of the cosmological constant line in this scenario. This crossing occurs in
both DGP$^{\pm}$ branches of the model.


title: Shortest path discovery of complex networks

abstract:
  In this paper we present an analytic study of sampled networks in the case of
some important shortest-path sampling models. We present analytic formulas for
the probability of edge discovery in the case of an evolving and a static
network model. We also show that the number of discovered edges in a finite
network scales much slower than predicted by earlier mean field models.
Finally, we calculate the degree distribution of sampled networks, and we
demonstrate that they are analogous to a destructed network obtained by
randomly removing edges from the original network.


title: An Alternative Origin for Hypervelocity Stars

abstract:
  Halo stars with unusually high radial velocity ("hypervelocity" stars, or
HVS) are thought to be stars unbound to the Milky Way that originate from the
gravitational interaction of stellar systems with the supermassive black hole
at the Galactic center. We examine the latest HVS compilation and find
peculiarities that are unexpected in this black hole-ejection scenario. For
example, a large fraction of HVS cluster around the constellation of Leo and
share a common travel time of $\sim 100$-200 Myr. Furthermore, their velocities
are not really extreme if, as suggested by recent galaxy formation models, the
Milky Way is embedded within a $2.5\times 10^{12} h^{-1} M_{\odot}$ dark halo
with virial velocity of $\sim 220$ km/s. In this case, the escape velocity at
$\sim 50$ kpc would be $\sim 600$ km/s and very few HVS would be truly unbound.
We use numerical simulations to show that disrupting dwarf galaxies may
contribute halo stars with velocities up to and sometimes exceeding the nominal
escape speed of the system. These stars are arranged in a thinly-collimated
outgoing ``tidal tail'' stripped from the dwarf during its latest pericentric
passage. We speculate that some HVS may therefore be tidal debris from a dwarf
recently disrupted near the center of the Galaxy. In this interpretation, the
angular clustering of HVS results because from our perspective the tail is seen
nearly ``end on'', whereas the common travel time simply reflects the fact that
these stars were stripped simultaneously from the dwarf during a single
pericentric passage. This proposal is eminently falsifiable, since it makes a
number of predictions that are distinct from the black-hole ejection mechanism
and that should be testable with improved HVS datasets.


title: Blind Cognitive MAC Protocols

abstract:
  We consider the design of cognitive Medium Access Control (MAC) protocols
enabling an unlicensed (secondary) transmitter-receiver pair to communicate
over the idle periods of a set of licensed channels, i.e., the primary network.
The objective is to maximize data throughput while maintaining the
synchronization between secondary users and avoiding interference with licensed
(primary) users. No statistical information about the primary traffic is
assumed to be available a-priori to the secondary user. We investigate two
distinct sensing scenarios. In the first, the secondary transmitter is capable
of sensing all the primary channels, whereas it senses one channel only in the
second scenario. In both cases, we propose MAC protocols that efficiently learn
the statistics of the primary traffic online. Our simulation results
demonstrate that the proposed blind protocols asymptotically achieve the
throughput obtained when prior knowledge of primary traffic statistics is
available.


title: The Embedding of Schwarzschild in Braneworld

abstract:
  The braneworlds models were inspired partly by Kaluza-Klein's theory, where
both the gravitational and the gauge fields are obtained from the geometry of a
higher dimensional space. The positive aspects of these models consist in
perspectives of modifications it could bring in to particle physics, such as:
unification in a TeV scale, quantum gravity in this scale and deviation of
Newton's law for small distances. One of the principles of these models is to
suppose that all space-times can be embedded in a bulk of higher dimension. The
main result in these notes is a theorem showing a mathematical inconsistency of
the Randall-Sundrum braneworld model, namely that the Schwarzschild space-time
cannot be embedded locally and isometrically in a five dimensional bulk with
constant curvature,(for example AdS-5). From the point of view of
semi-Riemannian geometry this last result represents a serious restriction to
the Randall-Sundrum's braneworld model.


title: Dynamics of a FitzHugh-Nagumo system subjected to autocorrelated noise

abstract:
  We analyze the dynamics of the FitzHugh-Nagumo (FHN) model in the presence of
colored noise and a periodic signal. Two cases are considered: (i) the dynamics
of the membrane potential is affected by the noise, (ii) the slow dynamics of
the recovery variable is subject to noise. We investigate the role of the
colored noise on the neuron dynamics by the mean response time (MRT) of the
neuron. We find meaningful modifications of the resonant activation (RA) and
noise enhanced stability (NES) phenomena due to the correlation time of the
noise. For strongly correlated noise we observe suppression of NES effect and
persistence of RA phenomenon, with an efficiency enhancement of the neuronal
response. Finally we show that the self-correlation of the colored noise causes
a reduction of the effective noise intensity, which appears as a rescaling of
the fluctuations affecting the FHN system.


title: On extensions of d.c. functions and convex functions

abstract:
  We show how our recent results on compositions of d.c. functions (and
mappings) imply positive results on extensions of d.c. functions (and
mappings). Examples answering two natural relevant questions are presented. Two
further theorems, concerning extendability of continuous convex functions from
a closed subspace of a normed linear space, complement recent results of
J.Borwein, V.Montesinos and J.Vanderwerff.


title:
Optical identification of a new cataclysmic variable from integral all
  sky survey: IGR J08390--4833

abstract:
  We have optically identified a recently discovered INTEGRAL source, IGR
J08390--4833, with a cataclysmic variable, i.e. an accreting white dwarf in a
binary system. The spectrum exhibits a rising blue continuum together with
Balmer and HeII emission lines. Analysis of the light curve of the source shows
clear presence of intrinsic variability on a time scale of the order of an
hour, although we do not claim that this variability is periodic. Therefore we
are not yet able to classify the object into a specific CV subclass.


title:
Uniqueness results for convex Hamilton-Jacobi equations under $p>1$
  growth conditions on data

abstract:
  Unbounded stochastic control problems may lead to Hamilton-Jacobi-Bellman
equations whose Hamiltonians are not always defined, especially when the
diffusion term is unbounded with respect to the control. We obtain existence
and uniqueness of viscosity solutions growing at most like $o(1+|x|^p)$ at
infinity for such HJB equations and more generally for degenerate parabolic
equations with a superlinear convex gradient nonlinearity. If the corresponding
control problem has a bounded diffusion with respect to the control, then our
results apply to a larger class of solutions, namely those growing like
$O(1+|x|^p)$ at infinity. This latter case encompasses some equations related
to backward stochastic differential equations.


title:
Systems with two symmetric absorbing states: relating the microscopic
  dynamics with the macroscopic behavior

abstract:
  We propose a general approach to study spin models with two symmetric
absorbing states. Starting from the microscopic dynamics on a square lattice,
we derive a Langevin equation for the time evolution of the magnetization
field, that successfully explains coarsening properties of a wide range of
nonlinear voter models and systems with intermediate states. We find that the
macroscopic behavior only depends on the first derivatives of the spin-flip
probabilities. Moreover, an analysis of the mean-field term reveals the three
types of transitions commonly observed in these systems -generalized voter,
Ising and directed percolation-. Monte Carlo simulations of the spin dynamics
qualitatively agree with theoretical predictions.


title: A note on 3-colorable plane graphs without 5- and 7-cycles

abstract:
  Borodin et al figured out a gap of the paper published at J. Combinatorial
Theory Ser. B (Vol.96 (2006) 958--963), and gave a new proof with the similar
technique. The purpose of this note is to fix the gap by slightly revising the
definition of special faces, and adding a few lines of explanation in the
proofs (new added text are all in black font).


title: Dyadosphere formed in gravitational collapse

abstract:
  We first recall the concept of Dyadosphere (electron-positron-photon plasma
around a formed black holes) and its motivation, and recall on (i) the Dirac
process: annihilation of electron-positron pairs to photons; (ii) the
Breit-Wheeler process: production of electron-positron pairs by photons with
the energy larger than electron-positron mass threshold; the
Sauter-Euler-Heisenberg effective Lagrangian and rate for the process of
electron-positron production in a constant electric field. We present a general
formula for the pair-production rate in the semi-classical treatment of quantum
mechanical tunneling. We also present in the Quantum Electro-Dynamics
framework, the calculations of the Schwinger rate and effective Lagrangian for
constant electromagnetic fields. We give a review on the electron-positron
plasma oscillation in constant electric fields, and its interaction with
photons leading to energy and number equipartition of photons, electrons and
positrons. The possibility of creating an overcritical field in astrophysical
condition is pointed out. We present the discussions and calculations on (i)
energy extraction from gravitational collapse; (ii) the formation of
Dyadosphere in gravitational collapsing process, and (iii) its hydrodynamical
expansion in Reissner Nordstr\"om geometry. We calculate the spectrum and flux
of photon radiation at the point of transparency, and make predictions for
short Gamma-Ray Bursts.


title:
Fulton-MacPherson compactification, cyclohedra, and the polygonal pegs
  problem

abstract:
  The cyclohedron (Bott-Taubes polytope) arises both as the polyhedral
realization of the poset of all cyclic bracketings of a circular word and as an
essential part of the Fulton-MacPherson compactification of the configuration
space of n distinct, labelled points on the circle S^1. The "polygonal pegs
problem" asks whether every simple, closed curve in the plane or in the higher
dimensional space admits an inscribed polygon of a given shape. We develop a
new approach to the polygonal pegs problem based on the Fulton-MacPherson
(Axelrod-Singer, Kontsevich) compactification of the configuration space of
(cyclically) ordered n-element subsets in S^1. Among the results obtained by
this method are proofs of Grunbaum's conjecture about affine regular hexagons
inscribed in smooth Jordan curves and a new proof of the conjecture of Hadwiger
about inscribed parallelograms in smooth, simple, closed curves in the 3-space
(originally established by Victor Makeev).


title:
Prospects and synergies between future atmospheric and long-baseline
  experiments

abstract:
  In this talk we will discuss the physics reach of the atmospheric neutrino
data collected by a future megaton-class neutrino detector. First we will
discuss the potentialities of atmospheric neutrinos on general basis,
presenting our results in the form of neutrino oscillograms of the Earth:
contour plots in the neutrino energy--nadir angle plane. In this context we
will analyze in detail the various signatures related to theta_13, to the
neutrino mass hierarchy, to the octant of theta_23 and to the delta_CP phase
which appear for different values of the neutrino energy and baseline. Then we
will consider concrete experimental setups, showing that synergic effects exist
between atmospheric and long-baseline neutrino data: the combination of the two
data sets is much more powerful than the simple sum of the sensitivity of each
individual data sample.


title: Metal-insulator transition in $(LaMnO_3)_{2n}/(SrMnO_3)_n$ superlattices

abstract:
  The modulation of charge density and spin order in
(LaMnO$_3$)$_{2n}$/(SrMnO$_3$)$_n$ ($n$=1-4) superlattices is studied via Monte
Carlo simulations of the double-exchange model. G-type antiferromagnetic
barriers in the SrMnO$_{3}$ regions with low charge density are found to
separate ferromagnetic LaMnO$_{3}$ layers with high charge density. The
recently experimentally observed metal-insulator transition with increasing $n$
is reproduced in our studies, and $n=3$ is found to be the critical value.


title: Higher-dimensional categories with finite derivation type

abstract:
  We study convergent (terminating and confluent) presentations of
n-categories. Using the notion of polygraph (or computad), we introduce the
homotopical property of finite derivation type for n-categories, generalizing
the one introduced by Squier for word rewriting systems. We characterize this
property by using the notion of critical branching. In particular, we define
sufficient conditions for an n-category to have finite derivation type. Through
examples, we present several techniques based on derivations of 2-categories to
study convergent presentations by 3-polygraphs.


title: Do all Flares have White Light Emission?

abstract:
  High-cadence, multiwavelength optical observations of a solar active region
(NOAA 10969), obtained with the Swedish Solar Telescope, are presented.
Difference imaging of white light continuum data reveals a white light
brightening, 2 min in duration, linked to a co-temporal and co-spatial C2.0
flare event. The flare kernel observed in the white light images has a diameter
of 300 km, thus rendering it below the resolution limit of most space-based
telescopes. Continuum emission is present only during the impulsive stage of
the flare, with the effects of chromospheric emission subsequently delayed by
approximately 2 min. The localized flare emission peaks at 300% above the
quiescent flux. This large, yet tightly confined, increase in emission is only
resolvable due to the high spatial resolution of the Swedish Solar Telescope.
An investigation of the line-of-sight magnetic field derived from simultaneous
MDI data shows that the continuum brightening is located very close to a
magnetic polarity inversion line. Additionally, an H-alpha flare ribbon is
directed along a region of rapid magnetic energy change, with the footpoints of
the ribbon remaining co-spatial with the observed white light brightening
throughout the duration of the flare. The observed flare parameters are
compared with current observations and theoretical models for M- and X-class
events and we determine the observed white-light emission is caused by
radiative back warming. We suggest that the creation of white-light emission is
a common feature of all solar flares.


title:
On the resolution of cosmic coincidence problem and phantom crossing
  with triple interacting fluids

abstract:
  We here investigate a cosmological model in which three fluids interact with
each other involving certain coupling parameters and energy exchange rates. The
motivation of the problem stems from the puzzling `triple coincidence problem'
which naively asks why the cosmic energy densities of matter, radiation and
dark energy are almost of the same order of magnitude at the present time. In
our model, we determine the conditions under triple interacting fluids will
cross the phantom divide.


title: Character of magnetic instabilities in CaFe2As2

abstract:
  The density functional non-interacting susceptibility has been analyzed in
different phases of CaFe2As2 and compared with similar data for pure d-metals.
The conditions for the "no local moment" itinerant state with large
frustrations are found for the "collapsed" phase (corresponding to
superconducting phase). This itineracy determines the instability versus the
incommensurate magnetic order for the narrow region of wave vectors. For the
ambient pressure phase, the local moments on Fe atoms with much less frustrated
antiferromagnetic interactions are stabilized and a magnetic short or long
range order for all wave vectors is developed.


title: New indirect bounds on Lorentz violation in the photon sector

abstract:
  Direct laboratory bounds on the 9 nonbirefringent Lorentz-violating
dimensionless parameters of modified-Maxwell theory range from the 10^{-7}
level to the 10^{-16} level. The detection of air showers initiated by charged
primaries (ultrahigh-energy cosmic-rays) and neutral primaries (TeV gamma-rays)
allows us to obtain new indirect bounds ranging from the 10^{-15} level to the
10^{-19} level. Possible physics implications are briefly discussed.


title:
Superconducting properties of Nb thin films deposited on porous silicon
  templates

abstract:
  Porous silicon, obtained by electrochemical etching, has been used as a
substrate for the growth of nanoperforated Nb thin films. The films, deposited
by UHV magnetron sputtering on the porous Si substrates, inherited their
structure made of holes of 5 or 10 nm diameter and of 10 to 40 nm spacing,
which provide an artificial pinning structure. The superconducting properties
were investigated by transport measurements performed in the presence of
magnetic field for different film thickness and substrates with different
interpore spacing. Perpendicular upper critical fields measurements present
peculiar features such as a change in the H_c2(T) curvature and oscillations in
the field dependence of the superconducting resistive transition width at H=1
Tesla. This field value is much higher than typical matching fields in
perforated superconductors, as a consequence of the small interpore distance.


title: Work fluctuations in a nematic liquid crystal

abstract:
  The orientation fluctuations of the director of a liquid crystal are
measured, by a sensitive polarization interferometer, close to the
Fr\'eedericksz transition, which is a second order transition driven by an
electric field. Using mean field theory, we define the work injected into the
system by a change of the electric field and we calibrate it using
Fluctuation-Dissipation Theorem. We show that the work fluctuations satisfy the
Transient Fluctuation Theorem. An analytical justification of this result is
given. The open problems for the out of equilibrium case are finally discussed.


title: Theoretical Perspectives: XLIII Rencontres de Moriond - QCD

abstract:
  I offer a brief summary, with commentary, of theoretical contributions to
Moriond QCD 2008.


title: Recent results on semileptonic decays at Babar

abstract:
  Some recent Babar results on semileptonic decays are presented. They focus on
the determination of the CKM matrix elements |V_{ub}| and |V_{cb}| in inclusive
and exclusive b --> u l nu and b--> c l nu decays, and on form factors
measurement in exclusive c--> s l nu decays.


title:
Optical transition in self-assembled InAs/GaAs quantum lens under high
  hydrostatic pressure

abstract:
  We present a simulation to characterize the dependence on hydrostatic
pressure for the photoluminescence spectra in self-assembled quantum dots with
lens shape geometry. We have tested the physical effects of the band offset and
electron-hole effective masses on the optical emission in dot lens. The model
could be implemented to get qualitative information of the parameters involved
in the quantum dot or the measured optical properties as function of pressure.


title:
Individual GRB sensitivity of a cubic-kilometer deep-sea neutrino
  telescope KM3NeT

abstract:
  Gamma-ray bursts (GRB) are powerful and highly variable sources of gamma rays
that indicate the existence of cosmic particle accelerators. Under the
assumption of hadronic acceleration in the jet, the expected neutrino energy
spectrum is derived according to the intrinsic fireball model parameters and to
the observed electromagnetic data of GRBs measured with ground-based and
satellite observations. Using the performance characteristics of a
cubic-kilometre scale neutrino detector placed in the Mediterranean Sea, the
number of events is calculated individually for all the GRBs having a known
redshift below the horizon of this detector. The good angular resolution of
this detector and the narrow time windows around the GRB detection time allow
suppression of almost all the atmospheric neutrino background. From the SWIFT
GRB catalogue, we have derived the mean characteristics of a burst in order to
be detected as an individual point source by a cubic-kilometre detector.


title: Search for long-lived particles in ATLAS and CMS

abstract:
  The ATLAS and CMS detectors can be used to search for heavy long-lived
particles which might signal physics beyond the Standard Model. Such new states
can be distinguished from Standard Model particles by exploiting their unique
signatures, ranging from multi-leptons and/or jets pro- duction anywhere within
the detector volume, to minimum ionizing particles with low velocity and high
momentum. Here are reviewed the strategies proposed by ATLAS and CMS to search
for these signals, with particular emphasis on possible challenges to the
trigger and detector operations.


title:
Analytical obtention of eigen-energies for lens-shaped quantum dot with
  finite barriers

abstract:
  The bound states of a particle in a lens-shaped quantum dot with finite
confinement potential are obtained in the envelope function approximation. The
quantum dot has circular base with radius $a$ and maximum cap height $b$, and
the effective mass of the particle is considered different inside and outside
the dot. A 2D Fourier expansion is used in a semi-sphere domain with infinite
walls which contains the geometry of the original potential. Electron energies
for different values of lens deformation $b/a$, lens radius $a$ and barrier
height $V_o$ are calculated. In the very high confinement potential limit, the
results for the infinite barrier case are recovered.


title:
Magnetic particle hyperthermia: Neel relaxation in magnetic
  nanoparticles under circularly polarized field

abstract:
  The mechanism of magnetization reversal in single-domain ferromagnetic
particles is of interest in many applications, in most of which losses must be
minimized. In cancer therapy by hyperthermia the opposite requirement prevails:
the specific loss power should be maximized. Of the mechanisms of dissipation,
here we study the effect of Neel relaxation on magnetic nanoparticles unable to
move or rotate and compare the losses in linearly and circularly polarized
field. We present exact analytical solutions of the Landau-Lifshitz equation as
derived from the Gilbert equation and use the calculated time-dependent
magnetizations to find the energy loss per cycle. In frequencies lower than the
Larmor frequency linear polarization is found to be the better source of heat
power, at high frequencies (beyond the Larmor frequency) circular polarization
is preferable.


title: Hilbert Space Average Method and adiabatic quantum search

abstract:
  We discuss some aspects related to the so-called Hilbert space Average
Method, as an alternative to describe the dynamics of open quantum systems.
First we present a derivation of the method which does not make use of the
algebra satisfied by the operators involved in the dynamics, and extend the
method to systems subject to a Hamiltonian that changes with time. Next we
examine the performance of the adiabatic quantum search algorithm with a
particular model for the environment. We relate our results to the criteria
discussed in the literature for the validity of the above-mentioned method for
similar environments.


title: Positive phase space transformation incompatible with classical physics

abstract:
  Bell conjectured that a positive Wigner function does not allow violation of
the inequalities imposed by local hidden variable theories. A requirement for
this conjecture is "when phase space measurements are performed". We introduce
the theory-independent concept of "operationally local transformations" which
refers to the change of the switch on a local measurement apparatus. We show
that two separated parties, performing only phase space measurements on a
composite quantum system with a positive Wigner function and performing only
operationally local transformations that preserve this positivity, can
nonetheless violate Bell's inequality. Such operationally local transformations
are realized using entangled ancillae.


title: Characteristic polynomials in real Ginibre ensembles

abstract:
  We calculate the average of two characteristic polynomials for the real
Ginibre ensemble of asymmetric random matrices, and its chiral counterpart.
Considered as quadratic forms they determine a skew-symmetric kernel from which
all complex eigenvalue correlations can be derived. Our results are obtained in
a very simple fashion without going to an eigenvalue representation, and are
completely new in the chiral case. They hold for Gaussian ensembles which are
partly symmetric, with kernels given in terms of Hermite and Laguerre
polynomials respectively, depending on an asymmetry parameter. This allows us
to interpolate between the maximally asymmetric real Ginibre and the Gaussian
Orthogonal Ensemble, as well as their chiral counterparts.

categories: math-ph cond-mat.stat-mech hep-th math.MP


title: Prospects for Large Relativity Violations in Matter-Gravity Couplings

abstract:
  Deviations from relativity are tightly constrained by numerous experiments. A
class of unmeasured and potentially large violations is presented that can be
tested in the laboratory only via weak gravity couplings. Specialized highly
sensitive experiments could achieve measurements of the corresponding effects.
A single constraint of 1 x 10^{-11} GeV is extracted on one combination of the
12 possible effects in ordinary matter. Estimates are provided for attainable
sensitivities in existing and future experiments.


title: Timelike $B_2$-slant helices in Minkowski space $E_1^4$

abstract:
  We consider a unit speed timelike curve $\alpha$ in Minkowski 4-space $E_1^4$
and denote the Frenet frame of $\alpha$ by $\{T,N,B_1,B_2\}$. We say that
$\alpha$ is a generalized helix if one of the unit vector fields of the Frenet
frame has constant scalar product with a fixed direction $U$ of $E_1^4$. In
this work we study those helices where the function $<B_2,U>$ is constant and
we give different characterizations of such curves.


title: Three-particle cumulant Study of Conical Emission

abstract:
  We discuss the sensitivity of the three-particle azimuthal cumulant method
for a search and study of conical emission in central relativistic $A+A $
collisions. Our study is based on a multi-component Monte Carlo model which
include flow background, Gaussian mono-jets, jet-flow, and Gaussian conical
signals. We find the observation of conical emission is hindered by the
presence of flow harmonics of fourth order ($v_4 $) but remains feasible even
in the presence of a substantial background. We consider the use of probability
cumulants for the suppression of 2$^{nd}$ order flow harmonics. We find that
while probability cumulant significantly reduce $v_2^2$ contributions, they
also complicate the cumulant of jets, and conical emission. The use of
probability cumulants is therefore not particularly advantageous in searches
for conical emission. We find the sensitivity of the (density) cumulant method
depends inextricably on strengths of
  $v_2 $, $v_4 $, background and non-Poisson character of particle production.
It thus cannot be expressed in a simple form, and without specific assumptions
about the values of these parameters.


title: Extensions of Lie Brackets

abstract:
  We provide a framework for extensions of Lie algebroids, including
non-abelian extensions and Lie algebroids over different bases. Our approach
involves Ehresmann connections, which allows straight generalizations of
classical constructions. We exhibit a filtration in cohomology and explain the
associated spectral sequence. We also give a description of the groupoid
integrating an extension in case a complete connection can be fixed. The
problem of integrability is also studied.


title: Symmetries and dynamics in an AC-driven self-assembled quantum dot lens

abstract:
  Theoretical results for a single electron in multi-level system given by a
lens-shape self-assembled quantum dot in the presence of an intense harmonic
electric field are presented. A non-perturbative Floquet approach is used to
study the dynamical localization of the particle when going beyond the
two-level approach by introducing the full spectral level structure. It is
discussed the role of the different quasi-energy sidebands as the parameters of
the system change. It is found that the contribution of different drive
harmonics is controlled by fine tuning of field intensity. It is also shown
that avoided crossings in the quasi-energy spectrum are correlated with the
spectral force of the sidebands and dynamical state localization.


title: On slant helices in Minkowski space $E_1^3$

abstract:
  We consider a curve $\alpha=\alpha(s)$ in Minkowski 3-space $E_1^3$ and
denote by $\{T,N,B}$ the Frenet frame of $\alpha$. We say that $\alpha$ is a
slant helix if there exists a fixed direction $U$ of $E_1^3$ such that the
function $<N(s),U>$ is constant. In this work we give characterizations of
slant helices in terms of the curvature and torsion of $\alpha$.


title: Arithmetic groups and the affine E8 Dynkin diagram

abstract:
  Several decades ago, John McKay suggested a correspondence between nodes of
the affine E8 Dynkin diagram and certain conjugacy classes in the Monster
group. Thanks to Monstrous Moonshine, this correspondence can be recast as an
assignment of discrete subgroups of PSL2 to nodes of the affine E8 Dynkin
diagram. The purpose of this article is to give an explanation for this latter
correspondence using elementary properties of the group PSL2. We also obtain a
super analogue of McKay's observation, in which conjugacy classes of the
Monster are replaced by conjugacy classes of Conway's group -- the automorphism
group of the Leech lattice.


title: L^2-Torsion and Bounded Measure Equivalence of Groups

abstract:
  This paper has been withdrawn by the author due to an error in the proof of
Proposition 4.8.


title:
A Study of the X-Ray Dust Scattering Halo of Cyg X-1 with a
  Cross-Correlation Method

abstract:
  X-ray photons scattered by the interstellar medium carry information about
dust distribution, dust grain model, scattering cross section, and the distance
of the source; they also take longer time than unscattered photons to reach the
observer. Using a cross-correlation method, we study the light curves of the
X-ray dust scattering halo of Cyg X-1, observed with the \textit{Chandra X-ray
Observatory}. Significant time lags are found between the light curves of the
point source and its halo. This time lag increases with the angular distance
from Cyg X-1, implying a dust concentration at a distance along the line of
sight (LOS) of 2.0 kpc $\times$ (0.876 $\pm$ 0.002) from the Earth. By fitting
the observed light curves of the halo at different radii with simulated light
curves, we obtain a width of $\mathit{\Delta L}=33_{-13}^{+18}$ pc of this dust
concentration. The origin of this dust concentration is still not clearly
known. The advantage of our method is that we need no assumption of scattering
cross section, dust grain model, or dust distribution along the LOS. Combining
the derived dust distribution from the cross-correlation study with the surface
brightness distribution of the halo, we conclude that the two commonly accepted
models of dust grain size distribution need to be modified significantly.


title:
Discovery Potential for the SM Higgs Boson in the H -> WW* -> 2l2nu
  channel at LHC

abstract:
  A prospective analysis for the search of the Standard Model (SM) Higgs boson
with the CMS detector is presented in the context of the early LHC data. The
aim is to establish an analysis strategy for inclusive production of the Higgs
boson decaying in WW* pairs in the context of the early LHC data. Higgs mass
region between 120-200 GeV, in which this signature was proposed as highly
sensitive, has been studied. The W decays into lnu are considered, where l
stands for e or mu. The final states are characterized by two, opposite-sign,
high transverse momentum leptons, missing energy, carried out by the undetected
neutrinos, and little jet activity. This study uses Monte Carlo (MC) events
with full detector simulation, including limited calibration and alignment
precision as expected at the LHC startup. Sets of sequential cuts are applied
to each of the three topologies, in order to isolate a signal which exceeds the
tt and continuum WW backgrounds. Alternatively, an artificial neural network
multi-variate analysis technique is used.


title: Stochastic All-to-All Propagators for Baryon Correlators

abstract:
  The effectiveness of various dilution schemes in the evaluation of baryonic
two-point functions is compared. The error of a representative set of
observables as a function of the number of Dirac matrix inversions is used as a
basis for comparison. To achieve an equivalent reduction in error, we
demonstrate that an increase in the number of dilution projectors on a single
noise source usually requires fewer inversions than the use of multiple noise
sources. This exploratory study was performed on 100 quenched gauge
configurations and will be applied to the calculation of low-lying hadron
spectra.


title:
Measurement of sub-shot-noise spatial correlations without subtraction
  of background

abstract:
  In this paper we present the first measurement of sub-shot-noise spatial
correlations without any subtraction of background, a result opening the way to
realize sub-shot-noise imaging of weak objects


title: The formation and assembly of a typical star-forming galaxy at z~3

abstract:
  Recent studies of galaxies ~2-3 Gyr after the Big Bang have revealed large,
turbulent rotating systems. The existence of well-ordered rotation in galaxies
during this peak epoch of cosmic star formation may suggest that gas accretion
through cold streams is likely to be the dominant mode by which most
star-forming galaxies at high redshift since major mergers can completely
disrupt the observed velocity fields. However poor spatial resolution and
sensitivity have hampered this interpretation, limiting the study to the
largest and most luminous galaxies, which may have fundamentally different
modes of assembly than more typical star forming galaxies. Here we report
observations of a typical star forming galaxy at z=3.07 with a linear
resolution of ~100 parsec. This spatial sampling is made possible by the
combination of gravitational lensing and laser guide star adaptive optics. We
find a well-ordered compact source in which molecular gas is being converted
efficiently into stars, likely assembling a spheroidal bulge and disk similar
to those seen in spiral galaxies at the present day.


title: Indirect Dark Matter Signals

abstract:
  Dark Matter annihilation (DMA) may yield an excess of gamma rays and
antimatter particles, like antiprotons and positrons, above the background from
cosmic ray interactions. Several signatures, ranging from the positron excess,
as observed by HEAT, AMS-01 and PAMELA, the gamma ray excess, as observed by
the EGRET spectrometer, the WMAP-haze, and constraints from antiprotons, as
observed by CAPRICE, BESS and PAMELA, have been discussed in the literature.
Unfortunately, the different signatures all lead to different WIMP masses,
indicating that at least some of these interpretations are likely to be
incorrect. Here we review them and discuss their relative merits and
uncertainties. New x-ray data from ROSAT suggests non-negligible convection in
our Galaxy, which leads to an order of magnitude uncertainty in the yield of
charged particles from DMA, since even a rather small convection will let drift
the charged particles in the halo to outer space.


title: On the K-stability of complete intersections in polarized manifolds

abstract:
  We consider the problem of existence of constant scalar curvature Kaehler
metrics on complete intersections of sections of vector bundles. In particular
we give general formulas relating the Futaki invariant of such a manifold to
the weight of sections defining it and to the Futaki invariant of the ambient
manifold. As applications we give a new Mukai-Umemura-Tian like example of Fano
5-fold admitting no Kaehler-Einstein metric and a strong evidence of
K-stability of complete intersections on Grassmannians.


title: Two counterexamples in rational and interval dynamics

abstract:
  In rational dynamics, we prove the existence of a polynomial that satisfies
the Topological Collet-Eckmann condition, but which has a recurrent critical
orbit that is not Collet-Eckmann. This shows that the converse of the main
theorem in [11] does not hold.
  In interval dynamics, we show that the Collet-Eckmann property for recurrent
critical orbits is not a topological invariant for real polynomials with
negative Schwarzian derivative. This contradicts a conjecture of Swiatek [22].


title:
Discontinuous Galerkin Methods for the Helmholtz Equation with Large
  Wave Number

abstract:
  This paper develops and analyzes some interior penalty discontinuous Galerkin
methods using piecewise linear polynomials for the Helmholtz equation with the
first order absorbing boundary condition in the two and three dimensions. It is
proved that the proposed discontinuous Galerkin methods are stable (hence
well-posed) without any mesh constraint. For each fixed wave number $k$,
optimal order (with respect to $h$) error estimate in the broken $H^1$-norm and
sub-optimal order estimate in the $L^2$-norm are derived without any mesh
constraint. The latter estimate improves to optimal order when the mesh size
$h$ is restricted to the preasymptotic regime (i.e., $k^2 h \gtrsim 1$).
Numerical experiments are also presented to gauge the theoretical result and to
numerically examine the pollution effect (with respect to $k$) in the error
bounds. The novelties of the proposed interior penalty discontinuous Galerkin
methods include: first, the methods penalize not only the jumps of the function
values across the element edges but also the jumps of the normal and tangential
derivatives; second, the penalty parameters are taken as complex numbers of
positive imaginary parts so essentially and practically no constraint is
imposed on the penalty parameters. Since the Helmholtz problem is a
non-Hermitian and indefinite linear problem, as expected, the crucial and the
most difficult part of the whole analysis is to establish the stability
estimates (i.e., a priori estimates) for the numerical solutions. To the end,
the cruxes of our analysis are to establish and to make use of a local version
of the Rellich identity (for the Laplacian) and to mimic the stability analysis
for the PDE solutions given in \cite{cummings00,Cummings_Feng06,hetmaniuk07}.


title: Interband superconductivity: contrasts between BCS and Eliashberg theory

abstract:
  The newly discovered iron pnictide superconductors apparently present an
unusual case of interband-channel pairing superconductivity. Here we show that,
in the limit where the pairing occurs within the interband channel, several
surprising effects occur quite naturally and generally: different
density-of-states on the two bands lead to several unusual properties,
including a gap ratio which behaves inversely to the ratio of
density-of-states; the weak-coupling limit of the Eliashberg and the BCS
theory, commonly taken as equivalent, in fact predict qualitatively different
dependence of the $\Delta_{1}/\Delta_{2}$ and $\Delta/T_{c}$ ratios on coupling
constants. We show analytically that these effects follow directly from the
interband character of superconductivity. Our results show that in the
interband-only pairing model the maximal gap ratio is $\sqrt{N_{2}/N_{1}}$ as
strong-coupling effects act only to reduce this ratio. This suggests that if
the large experimentally reported gap ratios (up to a factor 2) are correct,
the pairing mechanism must include more intraband interaction than is usually
assumed.


title:
Evidence of stochastic resonance in the mating behavior of Nezara
  viridula (L.)

abstract:
  We investigate the role of the noise in the mating behavior between
individuals of Nezara viridula (L.), by analyzing the temporal and spectral
features of the non-pulsed type female calling song emitted by single
individuals. We have measured the threshold level for the signal detection, by
performing experiments with the calling signal at different intensities and
analyzing the insect response by directionality tests performed on a group of
male individuals. By using a sub-threshold signal and an acoustic Gaussian
noise source, we have investigated the insect response for different levels of
noise, finding behavioral activation for suitable noise intensities. In
particular, the percentage of insects which react to the sub-threshold signal,
shows a non-monotonic behavior, characterized by the presence of a maximum, for
increasing levels of the noise intensity. This constructive interplay between
external noise and calling signal is the signature of the non-dynamical
stochastic resonance phenomenon. Finally, we describe the behavioral activation
statistics by a soft threshold model which shows stochastic resonance. We find
that the maximum of the ensemble average of the input-output cross-correlation
occurs at a value of the noise intensity very close to that for which the
behavioral response has a maximum.


title: SN 2001em: Not so Fast

abstract:
  SN 2001em is a peculiar supernova, originally classified as Type Ib/c. About
two years after the SN it was detected in the radio, showing a rising radio
flux with an optically thin spectral slope, and it also displayed a large X-ray
luminosity (~10^{41} erg/s). Thus it was suspected to harbor a decelerating (by
then, mildly) relativistic jet pointing away from us. About 3 years after its
discovery the optical spectrum of SN 2001em showed a broad H-alpha line, and it
was therefore reclassified as Type IIn. Here we constrain its proper motion and
expansion velocity by analyzing four epochs of VLBI observations, extending out
to 5.4 years after the SN. The supernova is still unresolved 5.4 years after
the explosion. For the proper motion we obtain (23,000 +/- 30,000) km/s while
our 2-sigma upper limit on the expansion velocity is 6000 km/s. These limits
are somewhat tighter than those derived by Bietenholz & Bartel, and confirm
their conclusion that late time emission from SN 2001em, a few years after the
explosion, is not driven by a relativistic jet. VLA observations of the radio
flux density, at 8.46 GHz, show a decay as t^{-1.23 +/- 0.40} starting ~2.7
years after the SN. Collectively, the observations suggest interaction of the
SN ejecta with a very dense circumstellar medium, though the implied opacity
constraints still present a challenge.


title:
A modified characteristic finite element method for a fully nonlinear
  formulation of the semigeostrophic flow equations

abstract:
  This paper develops a fully discrete modified characteristic finite element
method for a coupled system consisting of the fully nonlinear Monge-Amp\'ere
equation and a transport equation. The system is the Eulerian formulation in
the dual space for the B. J. Hoskins' semigeostrophic flow equations, which are
widely used in meteorology to model slowly varying flows constrained by
rotation and stratification. To overcome the difficulty caused by the strong
nonlinearity, we first formulate (at the differential level) a vanishing moment
approximation of the semigeostrophic flow equations, a methodology recently
proposed by the authors \cite{Feng1,Feng2}, which involves approximating the
fully nonlinear Monge-Amp\'ere equation by a family of fourth order quasilinear
equations. We then construct a fully discrete modified characteristic finite
element method for the regularized problem. It is shown that under certain mesh
and time stepping constraints, the proposed numerical method converges with an
optimal order rate of convergence. In particular, the obtained error bounds
show explicit dependence on the regularization parameter $\vepsi$. Numerical
tests are also presented to validate the theoretical results and to gauge the
efficiency of the proposed fully discrete modified characteristic finite
element method.


title: Multipartite Entanglement Criterion from Uncertainty Relations

abstract:
  We formulate an entanglement criterion using Peres-Horodecki positive partial
transpose operations combined with the Schr\"odinger-Robertson uncertainty
relation. We show that any pure entangled bipartite and tripartite state can be
detected by experimentally measuring mean values and variances of specific
observables. Those observables must satisfy a specific condition in order to be
used, and we show their general form in the $2\times 2$ (two qubits) dimension
case. The criterion is applied on a variety of physical systems including
bipartite and multipartite mixed states and reveals itself to be stronger than
the Bell inequalities and other criteria. The criterion also work on continuous
variable cat states and angular momentum states of the radiation field.


title: An Evidential Path Logic for Multi-Relational Networks

abstract:
  Multi-relational networks are used extensively to structure knowledge.
Perhaps the most popular instance, due to the widespread adoption of the
Semantic Web, is the Resource Description Framework (RDF). One of the primary
purposes of a knowledge network is to reason; that is, to alter the topology of
the network according to an algorithm that uses the existing topological
structure as its input. There exist many such reasoning algorithms. With
respect to the Semantic Web, the bivalent, monotonic reasoners of the RDF
Schema (RDFS) and the Web Ontology Language (OWL) are the most prevalent.
However, nothing prevents other forms of reasoning from existing in the
Semantic Web. This article presents a non-bivalent, non-monotonic, evidential
logic and reasoner that is an algebraic ring over a multi-relational network
equipped with two binary operations that can be composed to execute various
forms of inference. Given its multi-relational grounding, it is possible to use
the presented evidential framework as another method for structuring knowledge
and reasoning in the Semantic Web. The benefits of this framework are that it
works with arbitrary, partial, and contradictory knowledge while, at the same
time, it supports a tractable approximate reasoning process.


title: D-brane instantons and matrix models

abstract:
  We point out that in some situations it is possible to use matrix model
techniques a la Dijkgraaf-Vafa to perturbatively compute D-brane instanton
effects. This provides an explanation in terms of stringy instantons of the
results in hep-th/0311181. We check this proposal in some simple scenarios. We
point out some interesting consequences of this observation, such as the fact
that it gives a perturbative way of computing stringy multi-instanton effects.
It also provides a further interpretation of D-brane instantons as residual
instantons of higgsed supergroups.


title: A non-Markovian model of rill erosion

abstract:
  We introduce a new model for rill erosion. We start with a network similar to
that in the Discrete Web and instantiate a dynamics which makes the process
highly non-Markovian. The behavior of nodes in the streams is similar to the
behavior of Polya urns with time-dependent input. In this paper we use a
combination of rigorous arguments and simulation results to show that the model
exhibits many properties of rill erosion; in particular, nodes which are deeper
in the network tend to switch less quickly.


title: Half-BPS supergravity solutions and superalgebras

abstract:
  We establish a correspondence between certain Lie superalgebras with 16
fermionic generators, and half-BPS solutions to supergravities with 32
supersymmetries. Three cases are discussed. For Type IIB supergravity, we
relate semi-simple Lie superalgebras H with 16 fermionic generators which are
subalgebras of PSU(2,2|4), to families of half-BPS solutions which are
invariant under H, and locally asymptotic to AdS_5 x S^5. Similarly, for
M-theory, we relate semi-simple Lie superalgebras H with 16 fermionic
generators which are subalgebras of OSp(8^*|4) or OSp(8|4,R) to families of
half-BPS solutions which are invariant under H, and locally asymptotic to AdS_7
x S^4 or AdS_4 x S^7 respectively. Possible enhancements to more than 16
supersymmetries, such as 24, are also analyzed. The classification of
semi-simple subalgebras of PSU(2,2|4), OSp(8^*|4), and OSp(8|4,R) derived in
this paper, leads us to conjecture the existence of various new families of
half-BPS solutions to Type IIB supergravity and M-theory.


title: Sumsets and the convex hull

abstract:
  We extend Freiman's inequality on the cardinality of the sumset of a $d$
dimensional set. We consider different sets related by an inclusion of their
convex hull, and one of them added possibly several times.


abstract:
  Editorial of the International Conference on Critical Phenomena and Diffusion
in Complex Systems held on 5--7 December, 2006 in Nizhniy Novgorod State
University, Russia and was dedicated to the memory and 80th anniversary of
Professor Askold N. Malakhov.


title: Gerbal Representations of Double Loop Groups

abstract:
  A crucial role in representation theory of loop groups of reductive Lie
groups and their Lie algebras is played by their non-trivial second cohomology
classes which give rise to their central extensions (the affine Kac-Moody
groups and Lie algebras). Loop groups embed into the group GL_\infty of
continuous automorphisms of C((t)), and these classes come from a second
cohomology class of GL_\infty. In a similar way, double loop groups embed into
a group of automorphisms of C((t))((s)), denoted by GL_{\infty,\infty}, which
has a non-trivial third cohomology. In this paper we explain how to realize a
third cohomology class in representation theory of a group: it naturally arises
when we consider representations on categories rather than vector spaces. We
call them "gerbal representations." We then construct a gerbal representation
of GL_{\infty,\infty} (and hence of double loop groups), realizing its
non-trivial third cohomology class, on a category of modules over an
infinite-dimensional Clifford algebra. This is a two-dimensional analogue of
the fermionic Fock representations of the ordinary loop groups.


title: Plunnecke's inequality for different summands

abstract:
  The aim of this paper is to prove a general version of Pl\"unnecke's
inequality. Namely, assume that for finite sets $A$, $B_1, ... B_k$ we have
information on the size of the sumsets $A+B_{i_1}+... +B_{i_l}$ for all choices
of indices $i_1, ... i_l.$ Then we prove the existence of a non-empty subset
$X$ of $A$ such that we have `good control' over the size of the sumset
$X+B_1+... +B_k$. As an application of this result we generalize an inequality
of \cite{gymr} concerning the submultiplicativity of cardinalities of sumsets.


title:
Nova-Like Cataclysmic Variable TT Ari: QPO Behaviour Coming Back From
  Positive Superhumps

abstract:
  We study the variability of the nova-like cataclysmic variable TT Ari, on
time-scales of between minutes and months. The observations in the filter R
were obtained at the 40-cm telescope of the Chungbuk National University
(Korea). TT Ari was in the "negative superhump" state after its return from the
"positive superhump" state, which lasted 8 years. The ephemeris for 12 best
pronounced minima is $T_{min}=BJD 2453747.0700(47)+0.132322(53)E.$ where
numbers in digits are errors in units of the last digit. The phases of minima
may reach 0.2, indicating non-eclipse nature of these minima. The
quasi-periodic oscillations (QPO) are present with a mean "period" of 21.6 min
and mean semi-amplitude of 36 mmag. This value is consistent with the range
15-25 minutes reported for previous "negative superhump" states and does not
support the hypothesis of secular decrease of the QPO period.
  Either the period, or the semi-amplitude show significant night-to-night
variations. According to the position at the two-parameter diagrams, the
interval of observations was splitted into 5 parts, showing different
characteristics which are discussed in this paper. The system is an excellent
laboratory to study processes resulting in variations at time-scales from
seconds to decades and needs further monitoring at various states of activity.


title: The Geometry and Dynamics of Interacting Rigid Bodies and Point Vortices

abstract:
  We derive the equations of motion for a planar rigid body of circular shape
moving in a 2D perfect fluid with point vortices using symplectic reduction by
stages. After formulating the theory as a mechanical system on a configuration
space which is the product of a space of embeddings and the special Euclidian
group in two dimensions, we divide out by the particle relabelling symmetry and
then by the residual rotational and translational symmetry. The result of the
first stage reduction is that the system is described by a non-standard
magnetic symplectic form encoding the effects of the fluid, while at the second
stage, a careful analysis of the momentum map shows the existence of two
equivalent Poisson structures for this problem. For the solid-fluid system, we
hence recover the ad hoc Poisson structures calculated by Shashikanth, Marsden,
Burdick and Kelly on the one hand, and Borisov, Mamaev, and Ramodanov on the
other hand. As a side result, we obtain a convenient expression for the
symplectic leaves of the reduced system and we shed further light on the
interplay between curvatures and cocycles in the description of the dynamics.


title: The diagnostics subsystem on board LISA PathFinder and LISA

abstract:
  The Data and Diagnostics Subsystem of the LTP hardware and software are at
present essentially ready for delivery. In this presentation we intend to
describe the scientific and technical aspects of this subsystem, which includes
thermal diagnostics, magnetic diagnostics and a Radiation Monitor, as well as
the prospects for their integration within the rest of the LTP. We also sketch
a few lines of progress recently opened up towards the more demanding
diagnostics requirements which will be needed for LISA.


title: Levy Flight Superdiffusion: An Introduction

abstract:
  After a short excursion from discovery of Brownian motion to the Richardson
"law of four thirds" in turbulent diffusion, the article introduces the
L\'{e}vy flight superdiffusion as a self-similar L\'{e}vy process. The
condition of self-similarity converts the infinitely divisible characteristic
function of the L\'{e}vy process into a stable characteristic function of the
L\'{e}vy motion. The L\'{e}vy motion generalizes the Brownian motion on the
base of the $\alpha$-stable distributions theory and fractional order
derivatives. The further development of the idea lies on the generalization of
the Langevin equation with a non-Gaussian white noise source and the use of
functional approach. This leads to the Kolmogorov's equation for arbitrary
Markovian processes. As particular case we obtain the fractional Fokker-Planck
equation for L\'{e}vy flights. Some results concerning stationary probability
distributions of L\'{e}vy motion in symmetric smooth monostable potentials, and
a general expression to calculate the nonlinear relaxation time in barrier
crossing problems are derived. Finally we discuss results on the same
characteristics and barrier crossing problems with L\'{e}vy flights, recently
obtained with different approaches.


title:
Gravitinos, the Lithium problem, and DM production: Is there a
  corresponding neutrino physics linkage?

abstract:
  Studies are cited indicating that gravitino production acts as a natural
upper bound to Li6 and Li7 levels, based on what happens after hadronic decay
of relic 1 TeV into 100 GeV gravitinos at 1000 s. after the Big Bang. The
produced gravitinos contribute a large fraction of required dark matter
density. Whether or not gravitinos can be linked to neutrino production depends
on which model of dark matter (DM) is assumed or used. A model presented by the
author in 2008 links DM of about 100 GeV -- based on a phenomenological
Lagrangian creating different Neutrino masses without SUSY -- with a dark
matter candidate of about 100 GeV. This may tie in 100 GeV gravitinos with
neutrino physics.


title:
Quantum Hall Effect in Bilayer Graphene: Disorder Effect and Quantum
  Phase Transition

abstract:
  We numerically study the quantum Hall effect (QHE) in bilayer graphene based
on tight-binding model in the presence of disorder. Two distinct QHE regimes
are identified in the full energy band separated by a critical region with
non-quantized Hall Effect. The Hall conductivity around the band center (Dirac
point) shows an anomalous quantization proportional to the valley degeneracy,
but the $\nu=0$ plateau is markedly absent, which is in agreement with
experimental observation. In the presence of disorder, the Hall plateaus can be
destroyed through the float-up of extended levels toward the band center and
higher plateaus disappear first. The central two plateaus around the band
center are most robust against disorder scattering, which is separated by a
small critical region in between near the Dirac point. The longitudinal
conductance around the Dirac point is shown to be nearly a constant in a range
of disorder strength, till the last two QHE plateaus completely collapse.


title: Flavor Twisted Boundary Conditions and the Nucleon Vector Current

abstract:
  Using flavor twisted boundary conditions, we study nucleon matrix elements of
the vector current. We twist only the active quarks that couple to the current.
Finite volume corrections due to twisted boundary conditions are determined
using partially twisted, partially quenched, heavy baryon chiral perturbation
theory, which we develop for the graded group SU(7|5). Asymptotically these
corrections are exponentially small in the volume, but can become pronounced
for small twist angles. Utilizing the Breit frame does not mitigate volume
corrections to nucleon vector current matrix elements. The derived expressions
will allow for better controlled extractions of the isovector magnetic moment
and the electromagnetic radii from simulations at zero lattice momentum. Our
formalism, moreover, can be applied to any nucleon matrix elements.


title:
Theory of Cross Phase Modulation for the Vibrational Modes of Trapped
  Ions

abstract:
  We analyze nonlinear coupling between individual vibrational quanta for
trapped ions. The nonlinear Coulomb interaction causes a Kerr-type Hamiltonian,
for which we derive an analytical expression for the coupling constant. In
contrast to a previously published formula [1], our result is in close
agreement with experimental data.


title: LHC Signals for Warped Electroweak Charged Gauge Bosons

abstract:
  We study signals at the Large Hadron Collider (LHC) for the Kaluza-Klein (KK)
excitations of electroweak charged gauge bosons in the framework of the
Standard Model (SM) fields propagating in the bulk of a warped extra dimension.
Such a scenario can solve both the Planck-weak and flavor hierarchy problems of
the SM. There are two such charged states in this scenario with couplings to
light quarks and leptons being suppressed relative to those in the SM, whereas
the couplings to top/bottom quarks are enhanced, similar to the case of
electroweak neutral gauge bosons previously studied. However, unlike the case
of electroweak neutral gauge bosons, there is no irreducible QCD background
(including pollution from possibly degenerate KK gluons) for decays to top +
bottom final state so that this channel is useful for the discovery of the
charged states. Moreover, decays of electroweak charged gauge bosons to
longitudinal W, Z and Higgs are enhanced just as for the neutral bosons.
However, unlike for the neutral gauge bosons, the purely leptonic (and hence
clean) decay mode of the WZ are fully reconstructible so that the ratio of the
signal to the SM (electroweak) background can potentially be enhanced by
restricting to the resonance region more efficiently. We show that such final
states can give sensitivity to 2 (3) TeV masses with an integrated luminosity
of 100 (300) inverse fb. We emphasize that improvements in discriminating a
QCD-jet from a highly boosted hadronically decaying W, and a highly boosted
top-jet from a bottom-jet will enhance the reach for these KK particles, and
that the signals we study for the warped extra dimensional model might actually
be applicable also to a wider class of non-supersymmetric models of electroweak
symmetry breaking.


title:
Momentum average approximation for models with electron-phonon coupling
  dependent on the phonon momentum

abstract:
  We generalize the momentum average (MA) approximation to study the properties
of models with momentum-dependent electron-phonon coupling. As in the case of
the application of the original MA to the Holstein model, the results are
analytical, numerically trivial to evaluate, exact for both zero bandwidth and
for zero electron-phonon coupling, and are accurate everywhere in parameter
space. Comparison with available numerical data confirms this accuracy. We then
show that further improvements can be obtained based on variational
considerations, using the one-dimensional breathing-mode Hamiltonian as a
specific example. For example, by using this variational MA, we obtain ground
state energies within at most 0.3% error of the numerical data.


title: Constraint satisfaction problems with isolated solutions are hard

abstract:
  We study the phase diagram and the algorithmic hardness of the random
`locked' constraint satisfaction problems, and compare them to the commonly
studied 'non-locked' problems like satisfiability of boolean formulas or graph
coloring. The special property of the locked problems is that clusters of
solutions are isolated points. This simplifies significantly the determination
of the phase diagram, which makes the locked problems particularly appealing
from the mathematical point of view. On the other hand we show empirically that
the clustered phase of these problems is extremely hard from the algorithmic
point of view: the best known algorithms all fail to find solutions. Our
results suggest that the easy/hard transition (for currently known algorithms)
in the locked problems coincides with the clustering transition. These should
thus be regarded as new benchmarks of really hard constraint satisfaction
problems.

categories: cond-mat.dis-nn cond-mat.stat-mech cs.CC cs.DS


title: Extended Wreath Products

abstract:
  This paper has been withdrawn by the author, since proposed extensions are
equivalent at any k to either wreath or direct product.


title:
Algebraic Geometry Approach in Theories with Extra Dimensions I.
  Application of Lobachevsky Geometry

abstract:
  This present paper has the purpose to find certain physical appications of
Lobachevsky geometry and of the algebraic geometry approach in theories with
extra dimensions. It has been shown how the periodic properties of the
uniformization functions-solutions of cubic algebraic equations in gravity
theory enable the orbifold periodic identification of the points pr{c} and
-pr{c} under compactification. It has been speculated that corrections to the
extradimensional volume in theories with extra dimensions should be taken into
account due to the non-euclidean nature of the Lobachevsky space. It has been
demonstrated that in the Higgs mass generation model with two branes (a
"hidden" and a "visible" one), to any mass on the visible brane there could
correspond a number of physical masses. Algebraic equations for 4D
Schwarzschild Black Holes in higher dimensional brane worlds have been
obtained.


title: Astrophysical Signatures of Secluded Dark Matter

abstract:
  We analyze the indirect astrophysical signatures of secluded models of WIMP
dark matter, characterized by a weak-scale rate for annihilation into light
MeV-scale mediators which are metastable to decay into Standard Model states.
Such scenarios allow a significant enhancement of the annihilation cross
section in the galactic halo relative to its value at freeze-out, particularly
when the mediator is light enough for this process to proceed through radiative
capture to a metastable `WIMP-onium' bound state. For MeV-scale vector
mediators charged under a hidden U(1)' gauge group, the enhanced annihilation
rate leads predominantly to a sizable excess positron flux, even in the absence
of astrophysical boost factors.


title:
Algebraic Geometry Approach in Theories with Extra Dimensions II. Tensor
  Length Scale, Compactification and Rescaling

abstract:
  In this second part of the paper, dedicated to theories with extra
dimensions, a new physical notion about the "tensor length scale" is
introduced, based on the gravitational theories with covariant and
contravariant metric tensor components. Then the notion of "compactification"
in low energy type I string theory is supplemented by the operation of
"rescaling" of the contravariant metric components. For both the cases of
"rescaling + compactification" and "compactification + rescaling", quasilinear
differential equations in partial derivatives have been obtained and the
corresponding solutions have been found for the scale (length) function and for
the case of a flat 4D Minkowski space, embedded into a 5D space with an
exponential warp factor. A differential equation has been obtained and
investigated also from the equality of the "rescaled" scalar curvature with the
usual one.


title: A corollary of the b-function lemma

abstract:
  Let $X$ be an algebraic variety, $f$ a regular function, $j:U\subset X$ the
complement to the locus of vanishing of $f$, and $M$ a holonomic D-module on
$U$.
  Consider the $D_U[s]$-module $M\otimes "f^s"$. The goal of this note is to
describe all $D_X[s]$-submodules $N\subset j_*(M\otimes "f^s")$ such that
$j^*(N)\simeq M\otimes "f^s"$.


title: The star cluster system of the luminous elliptical galaxy NGC 1600

abstract:
  Luminous elliptical galaxies generally display a rich star cluster system,
whose properties provide strong constraints on the physics of galaxy formation
and evolution. Star cluster system studies, however, concentrate on galaxies
located in nearby or rich galaxy clusters. We acquired deep B and I images of
NGC 1600, a luminous elliptical in a galaxy group to study its star cluster
system. The images were obtained with the Optical Imager at the SOAR telescope.
The sample selection incompleteness was assessed as a function of magnitude and
image background level. Source counts were measured for different elliptical
annuli from the centre of NGC 1600, background subtracted, and fitted with a
Gaussian function. Colour distributions were derived as a function of
galactocentric distance for sources measured successfully in both filters.
Typical ages and metallicities were estimated based on single stellar
population models. A clear excess of point sources around NGC 1600 was found in
relation to the nearby field. The source counts were consistent with a Gaussian
distribution typical of other luminous ellipticals. The luminosity function
fits provided an estimate of the density of clusters at the different annuli
that could be integrated in solid angle, resulting in an estimated total
population of N_{GC} ~ 2850 star clusters. This yielded a specific frequency of
S_N ~ 1.6. The colour distributions show a hint of bimodality, especially at ~
20 kpc from the centre. Clusters in this region may be associated with a ring
or shell perturbation. Finally, the star cluster candidates were
cross-correlated to discrete X-ray sources and a coincidence rate of ~ 40% was
found. These are likely to be globular clusters harboring low-mass X-ray
binaries.


title:
Performance Enhancement of Multiuser Time Reversal UWB Communication
  System

abstract:
  UWB communication is a recent research area for indoor propagation channels.
Time Reversal (TR) communication in UWB has shown promising results for
improving the system performance. In multiuser environment, the system
performance is significantly degraded due to the interference among different
users. TR reduces the interference caused by multiusers due to its spatial
focusing property. The performance of a multiuser TR communication system is
further improved if the TR filter is modified. In this paper, multiuser TR in
UWB communication is investigated using simple TR filter and a modified TR
filter with circular shift operation. The concept of circular shift in TR is
analytically studied. Thereafter, the channel impulse responses (CIR) of a
typical indoor laboratory environment are measured. The measured CIRs are used
to analyze the received signal peak power and signal to interference ratio
(SIR) with and without performing the circular shift operation in a multiuser
environment.


title: Analysis of the parameter space and spectrum of the $\mu \nu$SSM

abstract:
  The $\mu\nu$SSM is a supersymmetric standard model that solves the $\mu$
problem of the MSSM using the R-parity breaking couplings between the
right-handed neutrino superfields and the Higgses in the superpotential,
$\lambda_{i} \hat \nu^c_i \hat H_d \hat H_u$. The $\mu$ term is generated
spontaneously through sneutrino vacuum expectation values, $\mu=\lambda_i <
\tilde \nu^c_i>$, once the electroweak symmetry is broken. In addition, the
couplings $\kappa_{ijk} \hat \nu^c_i\hat \nu^c_j\hat \nu^c_k$ forbid a global
U(1) symmetry avoiding the existence of a Goldstone boson, and also contribute
to spontaneously generate Majorana masses for neutrinos at the electroweak
scale. Following this proposal, we have analysed in detail the parameter space
of the $\mu\nu$SSM. In particular, we have studied viable regions avoiding
false minima and tachyons, as well as fulfilling the Landau pole constraint. We
have also computed the associated spectrum, paying special attention to the
mass of the lightest Higgs. The presence of right and left-handed sneutrino
vacuum expectation values leads to a peculiar structure for the mass matrices.
The most important consequence is that neutralinos are mixed with neutrinos,
and neutral Higgses with sneutrinos.


title: Pulsation in the atmosphere of roAp stars

abstract:
  High time resolution spectroscopy of roAp stars at large telescopes has led
to a major breakthrough in our understanding of magnetoacoustic pulsations in
these interesting objects. New observations have allowed to uncover a number of
intricate relations between stellar oscillations, magnetic field, and chemical
inhomogeneities. It is now understood that unusual pulsational characteristics
of roAp stars arise from an interplay between short vertical length of
pulsation waves and extreme chemical stratification. Here I review results of
recent studies which utilize these unique properties to map 3D pulsation
geometry using a combination of Doppler imaging, vertical pulsation tomography,
interpretation of line profile variation, and ultraprecise space photometry. I
also describe recent attempts to interpret theoretically the complex
observational picture of roAp pulsations.


title: The fully residually F quotients of F*<x,y>

abstract:
  We describe the fully residually F; or limit groups relative to F; (where F
is a free group) that arise from systems of equations in two variables over F
that have coefficients in F.


title: On Thermostats: Isokinetic or Hamiltonian? finite or infinite?

abstract:
  The relation between finite isokinetic thermostats and infinite Hamiltonian
thermostats is studied and their equivalence is heuristically discussed.


title:
Systemic Proper Motions of Milky Way Satellites from Stellar Redshifts:
  the Carina, Fornax, Sculptor and Sextans Dwarf Spheroidals

abstract:
  The transverse motions of nearby dwarf spheroidal (dSph) galaxies contribute
line-of-sight components that increase with angular distance from the dSph
centers, inducing detectable gradients in stellar redshift. In the absence of
an intrinsic velocity gradient (e.g., due to rotation or streaming), an
observed gradient in the heliocentric rest frame (HRF) relates simply to a
dSph's systemic proper motion (PM). Kinematic samples for the Milky Way's
brightest dSph satellites are now sufficiently large that we can use stellar
redshifts to constrain systemic PMs independently of astrometric data. Data
from our Michigan/MIKE Fiber System (MMFS) Survey reveal significant HRF
velocity gradients in Carina, Fornax and Sculptor, and no significant gradient
in Sextans. Assuming there are no intrinsic gradients, the data provide a
relatively tight constraint on the PM of Fornax,
(mu_{alpha}^{HRF},mu_{delta}^{HRF})=(+48 +/- 15,-25 +/- 14) mas/century, that
agrees with published HST astrometric measurements. Smaller data sets yield
weaker constraints in the remaining galaxies, but our Carina measurement,
(mu_{alpha}^{HRF},mu_{delta}^{HRF})=(+25 +/- 36,+16 +/- 43) mas/century, agrees
with the published astrometric value. The disagreement of our Sculptor
measurement, (mu_{alpha}^{HRF},mu_{delta}^{HRF})= (-40 +/- 29, -69 +/- 47)
mas/century, with astrometric measurements is expected if Sculptor has a
rotational component as reported by Battaglia et al. (2008). For Sextans, which
at present lacks an astrometric measurement, we measure
(mu_{alpha}^{HRF},mu_{delta}^{HRF})=(-26 +/- 41, +10 +/- 44) mas/century.


title: On the birthrates of Galactic neutron stars

abstract:
  In light of the recently discovered neutron star populations we discuss the
various estimates for the birthrates of these populations. We revisit the
question as to whether the Galactic supernova rate can account for all of the
known groups of isolated neutron stars. After reviewing the rates and
population estimates we find that, if the estimates are in fact accurate, the
current birthrate and population estimates are not consistent with the Galactic
supernova rate. We discuss possible solutions to this problem including whether
or not some of the birthrates are hugely over-estimated. We also consider a
possible evolutionary scenario between some of the known neutron star classes
which could solve this potential birthrate problem.


title: A DCCP Congestion Control Mechanism for Wired- cum-Wireless Environments

abstract:
  Existing transport protocols, be it TCP, SCTP or DCCP, do not provide an
efficient congestion control mechanism for heterogeneous wired-cum-wireless
networks. Solutions involving implicit loss discrimination schemes have been
proposed but were never implemented. Appropriate mechanisms can dramatically
improve bandwidth usage over the Internet, especially for multimedia transport
based on partial reliability. In this paper we have implemented and evaluated a
congestion control mechanism that implicitly discriminates congestion and
wireless losses in the datagram congestion control protocol (DCCP) congestion
control identification (CCID) framework. The new CCID was implemented as a NS-2
module. Comparisons were made with the TCP-like CCID and showed that the
bandwidth utilization was improved by more than 30% and up to 50% in
significant setups.


title: The star clusters of the Magellanic System

abstract:
  More than 50 years have elapsed since the first studies of star clusters in
the Magellanic Clouds. The wealth of data accumulated since then has not only
revealed a large cluster system, but also a diversified one, filling loci in
the age, mass and chemical abundance parameter space which are complementary to
Galactic clusters. Catalogs and photometric samples currently available cover
most of the cluster mass range. The expectations of relatively long cluster
disruption timescales in the Clouds have been confirmed, allowing reliable
assessments of the cluster initial mass function and of the cluster formation
rate in the Clouds. Due to their proximity to the Galaxy, Magellanic clusters
are also well resolved into stars. Analysis of colour-magnitude diagrams (CMDs)
of clusters with different ages, masses and metallicities are useful tools to
test dynamical effects such as mass loss due to stellar evolution, two-body
relaxation, stellar evaporation, cluster interactions and tidal effects. The
existence of massive and young Magellanic clusters has provided insight into
the physics of cluster formation. The magnitudes and colours of different
stellar types are confronted with stellar evolutionary tracks, thus
constraining processes such as convective overshooting, stellar mass-loss,
rotation and pre main-sequence evolution. Finally, the Magellanic cluster
system may contribute with nearby and well studied counterparts of the recently
proposed types of extragalactic clusters, such as Faint Fuzzies and Diffuse
Star Clusters.


title: Fluctuations of Chromodynamic Fields in Quark-Gluon Plasma

abstract:
  Chromodynamic fluctuations in the collisionless quark-gluon plasma are found
as a solution of the initial value linearized problem. The stable and unstable
plasmas are discussed.


title:
High-Resolution Timing Observations of Spin-Powered Pulsars with the
  AGILE Gamma-Ray Telescope

abstract:
  AGILE is a small gamma-ray astronomy satellite mission of the Italian Space
Agency dedicated to high-energy astrophysics launched in 2007 April. Its 1
microsecond absolute time tagging capability coupled with a good sensitivity in
the 30 MeV-30 GeV range, with simultaneous X-ray monitoring in the 18-60 keV
band, makes it perfectly suited for the study of gamma-ray pulsars following up
on the CGRO/EGRET heritage. In this paper we present the first AGILE timing
results on the known gamma-ray pulsars Vela, Crab, Geminga and B 1706-44. The
data were collected from 2007 July to 2008 April, exploiting the mission
Science Verification Phase, the Instrument Timing Calibration and the early
Observing Pointing Program. Thanks to its large field of view, AGILE collected
a large number of gamma-ray photons from these pulsars (about 10,000 pulsed
counts for Vela) in only few months of observations. The coupling of AGILE
timing capabilities, simultaneous radio/X-ray monitoring and new tools aimed at
precise photon phasing, exploiting also timing noise correction, unveiled new
interesting features at sub-millisecond level in the pulsars' high-energy
light-curves.