title: Confining vacua and Q-state Potts models with Q<1

abstract:
  In most Yang-Mills models the vacuum where magnetic monopoles condense
coincides with that where center vortices percolate, thus it is not clear which
of these two properties is most directly involved in producing confinement. It
is pointed out that there is a class of 3D gauge models, which can be though of
as duals of Q-state Potts models with Q < 1, where the magnetic monopole
condensation is a necessary but not sufficient condition for percolation of
center vortices. A set of numerical tests at Q=1/10 shows that there is a
vacuum in which the magnetic monopole condensate does not yield confinement, in
the sense that large Wilson loops obey a perimeter law. In such a vacuum the
center vortices form a dilute gas of loops. At stronger coupling there is also
a truly confining vacuum where both confining mechanisms are present.


title: Projective Ring Line of a Specific Qudit

abstract:
  A very particular connection between the commutation relations of the
elements of the generalized Pauli group of a $d$-dimensional qudit, $d$ being a
product of distinct primes, and the structure of the projective line over the
(modular) ring $\bZ_{d}$ is established, where the integer exponents of the
generating shift ($X$) and clock ($Z$) operators are associated with submodules
of $\bZ^{2}_{d}$. Under this correspondence, the set of operators commuting
with a given one -- a perp-set -- represents a $\bZ_{d}$-submodule of
$\bZ^{2}_{d}$. A crucial novel feature here is that the operators are also
represented by {\it non}-admissible pairs of $\bZ^{2}_{d}$. This additional
degree of freedom makes it possible to view any perp-set as a {\it
set-theoretic} union of the corresponding points of the associated projective
line.


title: Hard Discs on the Hyperbolic Plane

abstract:
  We examine a simple hard disc fluid with no long range interactions on the
two dimensional space of constant negative Gaussian curvature, the hyperbolic
plane. This geometry provides a natural mechanism by which global crystalline
order is frustrated, allowing us to construct a tractable model of disordered
monodisperse hard discs. We extend free area theory and the virial expansion to
this regime, deriving the equation of state for the system, and compare its
predictions with simulation near an isostatic packing in the curved space.


title: Random wave functions and percolation

abstract:
  Recently it was conjectured that nodal domains of random wave functions are
adequately described by critical percolation theory. In this paper we
strengthen this conjecture in two respects. First, we show that, though wave
function correlations decay slowly, a careful use of Harris' criterion confirms
that these correlations are unessential and nodal domains of random wave
functions belong to the same universality class as non critical percolation.
Second, we argue that level domains of random wave functions are described by
the non-critical percolation model.


title:
Anti-phase Modulation of Electron- and Hole-like States in Vortex Core
  of Bi2Sr2CaCu2Ox Probed by Scanning Tunneling Spectroscopy

abstract:
  In the vortex core of slightly overdoped Bi2Sr2CaCu2Ox, the electron-like and
hole-like states have been found to exhibit spatial modulations in anti-phase
with each other along the Cu-O bonding direction. Some kind of
one-dimensionality has been observed in the vortex core, and it is more clearly
seen in differential conductance maps at lower biases below +-9 mV.


title:
A statistical approach to simultaneous mapping and localization for
  mobile robots

abstract:
  Mobile robots require basic information to navigate through an environment:
they need to know where they are (localization) and they need to know where
they are going. For the latter, robots need a map of the environment. Using
sensors of a variety of forms, robots gather information as they move through
an environment in order to build a map. In this paper we present a novel
sampling algorithm to solving the simultaneous mapping and localization (SLAM)
problem in indoor environments. We approach the problem from a Bayesian
statistics perspective. The data correspond to a set of range finder and
odometer measurements, obtained at discrete time instants. We focus on the
estimation of the posterior distribution over the space of possible maps given
the data. By exploiting different factorizations of this distribution, we
derive three sampling algorithms based on importance sampling. We illustrate
the results of our approach by testing the algorithms with two real data sets
obtained through robot navigation inside office buildings at Carnegie Mellon
University and the Pontificia Universidad Catolica de Chile.


title:
Search for exoplanets with the radial-velocity technique: quantitative
  diagnostics of stellar activity

abstract:
  Aims: Stellar activity may complicate the analysis of high-precision
radial-velocity spectroscopic data when looking for exoplanets signatures. We
aim at quantifying the impact of stellar spots on stars with various spectral
types and rotational velocities and comparing the simulations with data
obtained with the HARPS spectrograph. Methods: We have developed detailed
simulations of stellar spots and estimated their effects on a number of
observables commonly used in the analysis of radial-velocity data when looking
for extrasolar planets, such as radial-velocity curves, cross-correlation
functions, bisector spans and photometric curves. The computed stellar spectra
are then analyzed in the same way as when searching for exoplanets. Results: 1)
A first grid of simulation results is built for F-K type stars, with different
stellar and spot properties. 2) It is shown quantitatively that star spots with
typical sizes of 1% can mimic both radial-velocity curves and the bisector
behavior of short-period giant planets around G-K type stars with a vsini lower
than the spectrograph resolution. For stars with intermediate vsini, smaller
spots may produce similar features. In these cases, additional observables
(e.g., photometry, spectroscopic diagnostics) are mandatory to confirm the
presence of short-period planets. We show that, in some cases, photometric
variations may not be enough to clearly rule out spots as explanations of the
observed radial-velocity variations. This is particularly important when
searching for super-Earth planets. 3) It is also stressed that quantitative
values obtained for radial-velocity and bisector span amplitudes depend
strongly on the detailed star properties, on the spectrograph used, on the set
of lines used, and on the way they are measured.


title: Astro Unparticle Physics

abstract:
  We investigate the effects of all flavor blind CP-conserving unparticle
operators on 5th force experiments, stellar cooling, supernova explosions and
compare the limits with each other and with those obtainable from collider
experiments. In general, astrophysical bounds are considerably stronger,
however they depend strongly on the dimension d_U of the unparticle operator.
While for d_U=1, 5th force experiments yield exceedingly strong bounds, the
bounds from stellar and supernova cooling are more comparable for d_U=2, with
stellar cooling being most restrictive. Bounds on vectorial unparticle
couplings are generally stronger than those on scalar ones.


title: Uniqueness of the 2-universality Criterion

abstract:
  Kim, Kim, and Oh gave a minimal criterion for the 2-universality of
positive-definite integer-matrix quadratic forms. We show that this
2-universality criterion is unique in the sense of the uniqueness of the
Conway-Schneeberger Fifteen Theorem.


title: Planetary nebulae, tracers of stellar nucleosynthesis

abstract:
  We review the information that planetary nebulae and their immediate
progenitors, the post-AGB objects, can provide to probe the nucleosynthesis and
mixing in low and intermediate mass stars. We emphasize new approaches based on
high signal-to-noise spectroscopy of planetary nebulae and of their central
stars. We mention some of the problems still to overcome. We emphasize that, as
found by several authors, planetary nebulae in low metallicity environments
cannot be used to probe the oxygen abundance in the interstellar medium out of
which their progenitors were formed, because of abundance modification during
stellar evolution.


title:
Form-factors in the Baxter-Bazhanov-Stroganov model I: Norms and matrix
  elements

abstract:
  We continue our investigation of the Z_N-Baxter-Bazhanov-Stroganov model
using the method of separation of variables [nlin/0603028]. In this paper we
calculate the norms and matrix elements of a local Z_N-spin operator between
eigenvectors of the auxiliary problem. For the norm the multiple sums over the
intermediate states are performed explicitly. In the case N=2 we solve the
Baxter equation and obtain form-factors of the spin operator of the periodic
Ising model on a finite lattice.

categories: nlin.SI cond-mat.stat-mech math-ph math.MP


title:
Order preservation in a generalized version of Krause's opinion dynamics
  model

abstract:
  Krause's model of opinion dynamics has recently been the object of several
studies, partly because it is one of the simplest multi-agent systems involving
position-dependent changing topologies. In this model, agents have an opinion
represented by a real number and they update it by averaging those agent
opinions distant from their opinion by less than a certain interaction radius.
Some results obtained on this model rely on the fact that the opinion orders
remain unchanged under iteration, a property that is consistent with the
intuition in models with simultaneous updating on a fully connected
communication topology. Several variations of this model have been proposed. We
show that some natural variations are not order preserving and therefore cause
potential problems with the theoretical analysis and the consistence with the
intuition. We consider a generic version of Krause's model parameterized by an
influence function that encapsulates most of the variations proposed in the
literature. We then derive a necessary and sufficient condition on this
function for the opinion order to be preserved.


title: Two-dimensional Hubbard Model in the presence of lattice distortions

abstract:
  The two-dimensional Hubbard model on the square lattice is studied in the
presence of lattice distortions in the adiabatic approximation. The self energy
is computed within perturbation theory up to second order, which provides a way
for studying the quasiparticle dispersion. We compute numerically the second
order contribution to the self-energy using a standard Fast Fourier Transform
Algorithm for finite system sizes. The stability of the lattice distortions is
investigated and a schematic phase diagram is drawn. The Fermi surface is
analyzed for densities near to half filling, the presence of lattice distortion
change some spectral properties of the model and gives an anisotropic
interacting FS. The spectral function is calculated along several lines in
momentum space and the renormalized quasiparticle dispersion is obtained. The
behavior of the density of states is shown for different values of the
intrasite repulsion U in the different phases.


title: Boiling of nuclear liquid in core-collapse supernova explosions

abstract:
  We investigate the possibility of boiling instability of nuclear liquid in
the inner core of the proto-neutron star formed in the core collapse of a type
II supernova. We derive a simple criterion for boiling to occur. Using this
criterion for one of best described equations of state of supernova matter, we
find that boiling is quite possible under the conditions realized inside the
proto-neutron star. We discuss consequences of this process such as the
increase of heat transfer rate and pressure in the boiling region. We expect
that taking this effect into account in the conventional neutrino-driven
delayed-shock mechanism of type II supernova explosions can increase the
explosion energy and reduce the mass of the neutron-star remnant.


title:
Continuation unique a partir de l'infini conforme pour les metriques
  d'Einstein

abstract:
  We prove the unique continuation property at the conformal infinity for
asymptotically hyperbolic Einstein metrics.


title: World currency exchange rate cross-correlations

abstract:
  World currency network constitutes one of the most complex structures that is
associated with the contemporary civilization. On a way towards quantifying its
characteristics we study the cross correlations in changes of the daily foreign
exchange rates within the basket of 60 currencies in the period December 1998
-- May 2005. Such a dynamics turns out to predominantly involve one outstanding
eigenvalue of the correlation matrix. The magnitude of this eigenvalue depends
however crucially on which currency is used as a base currency for the
remaining ones. Most prominent it looks from the perspective of a peripheral
currency. This largest eigenvalue is seen to systematically decrease and thus
the structure of correlations becomes more heterogeneous, when more significant
currencies are used as reference. An extreme case in this later respect is the
USD in the period considered. Besides providing further insight into subtle
nature of complexity, these observations point to a formal procedure that in
general can be used for practical purposes of measuring the relative currencies
significance on various time horizons.


title: An optimized algebraic basis for molecular potentials

abstract:
  The computation of vibrational spectra of diatomic molecules through the
exact diagonalization of algebraically determined matrixes based on powers of
Morse coordinates is made substantially more efficient by choosing a properly
adapted quantum-mechanical basis, specifically tuned to the molecular
potential. A substantial improvement is achieved while still retaining the full
advantage of the simplicity and numerical light-weightedness of an algebraic
approach. In the scheme we propose, the basis is parameterized by two
quantities which can be adjusted to best suit the molecular potential through a
simple minimization procedure.


title:
Detecting unstable periodic spatio-temporal states of spatial extended
  chaotic systems

abstract:
  The method of detection of the unstable periodic spatio-temporal states of
spatial extended chaotic systems has been proposed. The application of this
method is illustrated by the consideration of two different systems: i) the
fluid model of Pierce diode being one of the fundamental system of the physics
of plasmas and microwave electronics and ii) the complex one-dimensional
Ginzburg-Landau equation demonstrating different regimes of spatio-temporal
chaos.


title:
Random-set methods identify distinct aspects of the enrichment signal in
  gene-set analysis

abstract:
  A prespecified set of genes may be enriched, to varying degrees, for genes
that have altered expression levels relative to two or more states of a cell.
Knowing the enrichment of gene sets defined by functional categories, such as
gene ontology (GO) annotations, is valuable for analyzing the biological
signals in microarray expression data. A common approach to measuring
enrichment is by cross-classifying genes according to membership in a
functional category and membership on a selected list of significantly altered
genes. A small Fisher's exact test $p$-value, for example, in this $2\times2$
table is indicative of enrichment. Other category analysis methods retain the
quantitative gene-level scores and measure significance by referring a
category-level statistic to a permutation distribution associated with the
original differential expression problem. We describe a class of random-set
scoring methods that measure distinct components of the enrichment signal. The
class includes Fisher's test based on selected genes and also tests that
average gene-level evidence across the category. Averaging and selection
methods are compared empirically using Affymetrix data on expression in
nasopharyngeal cancer tissue, and theoretically using a location model of
differential expression. We find that each method has a domain of superiority
in the state space of enrichment problems, and that both methods have benefits
in practice. Our analysis also addresses two problems related to
multiple-category inference, namely, that equally enriched categories are not
detected with equal probability if they are of different sizes, and also that
there is dependence among category statistics owing to shared genes. Random-set
enrichment calculations do not require Monte Carlo for implementation. They are
made available in the R package allez.


title: A path integral leading to higher-order Lagrangians

abstract:
  We consider a simple modification of standard phase-space path integrals and
show that it leads in configuration space to Lagrangians depending also on
accelerations.


title: Jordan algebras over algebraic varieties

abstract:
  We construct Jordan algebras over a locally ringed space using
generalizations of the Tits process and the first Tits construction by
Achhammer. Some general results on the structure of these algebras are
obtained. Examples of Albert algebras over a Brauer-Severi variety with
associated central simple algebra of degree 3 are given.


title: Scaling properties of delay times in one-dimensional random media

abstract:
  The scaling properties of the inverse moments of Wigner delay times are
investigated in finite one-dimensional (1D) random media with one channel
attached to the boundary of the sample. We find that they follow a simple
scaling law which is independent of the microscopic details of the random
potential. Our theoretical considerations are confirmed numerically for systems
as diverse as 1D disordered wires and optical lattices to microwave waveguides
with correlated scatterers.


title: G-functions and multisum versus holonomic sequences

abstract:
  The purpose of the paper is three-fold: (a) we prove that every sequence
which is a multidimensional sum of a balanced hypergeometric term has an
asymptotic expansion of Gevrey type-1 with rational exponents, (b) we construct
a class of $G$-functions that come from enumerative combinatorics, and (c) we
give a counterexample to a question of Zeilberger that asks whether holonomic
sequences can be written as multisums of balanced hypergeometric terms. The
proofs utilize the notion of a $G$-function, introduced by Siegel, and its
analytic/arithmetic properties shown recently by Andr\'e.


title: Quantum tunneling in ^{277}112 and its alpha-decay chain

abstract:
  The $\alpha$-decay half lives of nuclei in the decay from element $^{277}112$
are calculated in a WKB framework using DDM3Y interaction and experimental
Q-values. Theoretical estimation of half lives in the same quantum tunneling
model, using Q-values from the mass formula of
Muntian-Hofmann-Patyk-Sobiczewski, are also presented. Calculated results
furnish corroborating evidence for the experimental findings at RIKEN and GSI.
Certain discrepancies indicate necessity of a better mass formula. Further
experimental data with higher statistics would also be useful.


title:
Phase stability of hafnium oxide and zirconium oxide on silicon
  substrate

abstract:
  Phase stabilities of Hf-Si-O and Zr-Si-O have been studied with
first-principles and thermodynamic modeling. From the obtained thermodynamic
descriptions, phase diagrams pertinent to thin film processing were calculated.
We found that the relative stability of the metal silicates with respect to
their binary oxides plays a critical role in silicide formation. It was
observed that both the HfO$_2$/Si and ZrO$_2$/Si interfaces are stable in a
wide temperature range and silicide may form at low temperatures, partially at
the HfO$_2$/Si interface.


title:
Bifurcation of standing waves into a pair of oppositely traveling waves
  with oscillating amplitudes caused by a three-mode interaction

abstract:
  A novel flow state consisting of two oppositely travelling waves (TWs) with
oscillating amplitudes has been found in the counterrotating Taylor-Couette
system by full numerical simulations. This structure bifurcates out of axially
standing waves that are nonlinear superpositions of left and right handed
spiral vortex waves with equal time-independent amplitudes. Beyond a critical
driving the two spiral TW modes start to oscillate in counterphase due to a
Hopf bifurcation. The trigger for this bifurcation is provided by a nonlinearly
excited mode of different symmetry than the spiral TWs. A three-mode coupled
amplitude equation model is presented that captures this bifurcation scenario.
The mode-coupling between two symmetry degenerate critical modes and a
nonlinearly excited one that is contained in the model can be expected to occur
in other structure forming systems as well.


title:
Elevated soil lead: Statistical modeling and apportionment of
  contributions from lead-based paint and leaded gasoline

abstract:
  While it is widely accepted that lead-based paint and leaded gasoline are
primary sources of elevated concentrations of lead in residential soils,
conclusions regarding their relative contributions are mixed and generally
study specific. We develop a novel nonlinear regression for soil lead
concentrations over time. It is argued that this methodology provides useful
insights into the partitioning of the average soil lead concentration by source
and time over large residential areas. The methodology is used to investigate
soil lead concentrations from the 1987 Minnesota Lead Study and the 1990
National Lead Survey. Potential litigation issues are discussed briefly.


title:
On the Topological Properties of the World Trade Web: A Weighted Network
  Analysis

abstract:
  This paper studies the topological properties of the World Trade Web (WTW)
and its evolution over time by employing a weighted network analysis. We show
that the WTW, viewed as a weighted network, displays statistical features that
are very different from those obtained by using a traditional binary-network
approach. In particular, we find that: (i) the majority of existing links are
associated to weak trade relationships; (ii) the weighted WTW is only weakly
disassortative; (iii) countries holding more intense trade relationships are
more clustered.


title: Modeling urban street patterns

abstract:
  Urban streets patterns form planar networks whose empirical properties cannot
be accounted for by simple models such as regular grids or Voronoi
tesselations. Striking statistical regularities across different cities have
been recently empirically found, suggesting that a general and
details-independent mechanism may be in action. We propose a simple model based
on a local optimization process combined with ideas previously proposed in
studies of leaf pattern formation. The statistical properties of this model are
in good agreement with the observed empirical patterns. Our results thus
suggests that in the absence of a global design strategy, the evolution of many
different transportation networks indeed follow a simple universal mechanism.


title: Fundamental Constants

abstract:
  The notion of ``fundamental constant'' is heavily theory-laden. A natural,
fairly precise formulation is possible in the context of the standard model
(here defined to include gravity). Some fundamental constants have profound
geometric meaning. The ordinary gravitational constant parameterizes the
stiffness, or resistance to curvature, of space-time. The cosmological term
parameterizes space-time's resistance to expansion -- which may be, and
apparently is at present, a {\it negative} resistance, i.e. a tendency toward
expansion. The three gauge couplings of the strong, electromagnetic, and weak
interactions parameterize resistance to curvature in internal spaces. The
remaining fundamental couplings, of which there are a few dozen, supply an
ungainly accommodation of inertia. The multiplicity and variety of fundamental
constants are esthetic and conceptual shortcomings in our present understanding
of foundational physics. I discuss some ideas for improving the situation. I
then briefly discuss additional constants, primarily cosmological, that enter
into our best established present-day world model. Those constants presently
appear as macroscopic state parameters, i.e. as empirical ``material
constants'' of the Universe. I mention a few ideas for how they might become
fundamental constants in a future theory. In the course of this essay I've
advertised several of my favorite speculations, including a few that might be
tested soon.


title: The Metallicity of Intergalactic Gas in Cosmic Voids

abstract:
  We have used the Hubble/STIS and FUSE archives of ultraviolet spectra of
bright AGN to identify intergalactic Lya absorbers in nearby (z < 0.1) voids.
  From a parent sample of 651 Lya absorbers, we identified 61 void absorbers
located more than 1.4/h_70 Mpc from the nearest L* or brighter galaxy.
Searching for metal absorption in high-quality (S/N > 10) spectra at the
location of three diagnostic metal lines (O VI 1032, C IV 1548, Si III 1206),
we detected no metal lines in any individual absorber, or in any group of
absorbers using pixel co-addition techniques. The best limits on metal-line
absorption in voids were set using four strong Lya absorbers with N(H I) >
10^{14} cm^-2, with 3-sigma equivalent-width limits ranging from 8 mA (O VI),
7-15 mA (C IV), and 4-10 mA (Si III). Photoionization modeling yields
metallicity limits Z < 10^{-1.8+/-0.4} Z_sun, from non-detections of C IV and O
VI, some 6 times lower than those seen in Lya and OVI absorbers at z < 0.1.
Although the void Lya absorbers could be pristine material, considerably deeper
spectra are required to rule out a universal metallicity floor produced by
bursts of early star formation, with no subsequent star formation in the voids.
The most consistent conclusion derived from these low-z results, and similar
searches at z = 3-5, is that galaxy filaments have increased their mean IGM
metallicity by factors of 30-100 since z = 3.


title: The Influence of Metallicity on Star Formation in Protogalaxies

abstract:
  In cold dark matter cosmological models, the first stars to form are believed
to do so within small protogalaxies. We wish to understand how the evolution of
these early protogalaxies changes once the gas forming them has been enriched
with small quantities of heavy elements, which are produced and dispersed into
the intergalactic medium by the first supernovae. Our initial conditions
represent protogalaxies forming within a fossil H II region, a previously
ionized region that has not yet had time to cool and recombine. We study the
influence of low levels of metal enrichment on the cooling and collapse of
ionized gas in small protogalactic halos using three-dimensional, smoothed
particle hydrodynamics (SPH) simulations that incorporate the effects of the
appropriate chemical and thermal processes. Our previous simulations
demonstrated that for metallicities Z < 0.001 Z_sun, metal line cooling alters
the density and temperature evolution of the gas by less than 1% compared to
the metal-free case at densities below 1 cm-3) and temperatures above 2000 K.
Here, we present the results of high-resolution simulations using particle
splitting to improve resolution in regions of interest. These simulations allow
us to address the question of whether there is a critical metallicity above
which fine structure cooling from metals allows efficient fragmentation to
occur, producing an initial mass function (IMF) resembling the local Salpeter
IMF, rather than only high-mass stars.


title:
Compton dragged supercritical piles: The GRB prompt and afterglow
  scenario

abstract:
  We examine the prompt and afterglow emission within the context of the
Supercritical Pile model for GRBs. For this we have performed self-consistent
calculations, by solving three time-dependent kinetic equations for protons,
electrons and photons in addition to the usual mass and energy conservation
equations. We follow the evolution of the RBW as it sweeps up circumstellar
matter and assume that the swept-up electrons and protons have energies equal
to the Lorentz factor of the flow. While the electrons radiate their energies
through synchrotron and inverse Compton radiation on short timescales, the
protons, at least initially, start accumulating without any dissipation. As the
accumulated mass of relativistic protons increases, however, they can become
supercritical to the `proton-photon pair-production - synchrotron radiation'
network, and, as a consequence, they transfer explosively their stored energy
to secondary electron-positron pairs and radiation. This results in a burst
which has many features similar to the ones observed in GRB prompt emission. We
have included in our calculations the radiation drag force exerted on the flow
from the scattered radiation of the prompt emission on the circumstellar
material. We find that this can decelerate the flow on timescales which are
much faster than the ones related to the usual adiabatic/radiative ones. As a
result the emission exhibits a steep drop just after the prompt phase, in
agreement with the Swift afterglow observations.


title: Nonabelian localization for gauge theory on the fuzzy sphere

abstract:
  We apply nonabelian equivariant localization techniques to Yang-Mills theory
on the fuzzy sphere to write the partition function entirely as a sum over
local contributions from critical points of the action. The contributions of
the classical saddle-points are evaluated explicitly, and the partition
function of ordinary Yang-Mills theory on the sphere is recovered in the
commutative limit.


title: $G$-stable pieces and partial flag varieties

abstract:
  We will use the combinatorics of the $G$-stable pieces to describe the
closure relation of the partition of partial flag varieties in \cite[section
4]{L3}.


title: All-sky incoherent search for periodic signals with Explorer 2005 data

abstract:
  The data collected during 2005 by the resonant bar Explorer are divided into
segments and incoherently summed in order to perform an all-sky search for
periodic gravitational wave signals. The parameter space of the search spanned
about 40 Hz in frequency, over 23927 positions in the sky. Neither source
orbital corrections nor spindown parameters have been included, with the result
that the search was sensible to isolated neutron stars with a frequency drift
less than 6 X 10^{-11} Hz/s.
  No gravitational wave candidates have been found by means of the present
analysis, which led to a best upper limit of 3.1 X 10^{-23} for the
dimensionless strain amplitude.


title: Parabolic dunes in north-eastern Brazil

abstract:
  In this work we present measurements of vegetation cover over parabolic dunes
with different degree of activation along the north-eastern Brazilian coast. We
are able to extend the local values of the vegetation cover density to the
whole dune by correlating measurements with the gray-scale levels of a high
resolution satellite image of the dune field. The empirical vegetation
distribution is finally used to validate the results of a recent continuous
model of dune motion coupling sand erosion and vegetation growth.


title: The size of a pond in 2D invasion percolation

abstract:
  We consider invasion percolation on the square lattice. It has been proved by
van den Berg, Peres, Sidoravicius and Vares, that the probability that the
radius of a so-called pond is larger than n, differs at most a factor of order
log n from the probability that in critical Bernoulli percolation the radius of
an open cluster is larger than n. We show that these two probabilities are, in
fact, of the same order. Moreover, we prove an analogous result for the volume
of a pond.


title: Fibonacci-like sequences and shift spaces in symbolic dynamics

abstract:
  We afford the problem of counting the blocks of a given length made with
symbols drawn from an alphabet and relate this number to Fibonacci-like
recurrent relations. The recurrence polynomia allows to calculate the limit
ratio of two adjacent terms and this information is used to determine the
topological entropy of a discrete numbers of associate shift spaces. We then
describe a scheme to build a shift space with a pre-selected entropy.


title:
Bernoulli free-boundary problems in strip-like domains and a property of
  permanent waves in water of finite depth

abstract:
  We study weak solutions for a class of free boundary problems which includes
as a special case the classical problem of traveling waves on water of finite
depth. We show that such problems are equivalent to problems in fixed domains
and study the regularity of their solutions. We also prove that in very general
situations the free boundary is necessarily the graph of a function.


title: Non-Equilibrium Quantum Dissipation

abstract:
  Dissipative processes in non-equilibrium many-body systems are fundamentally
different than their equilibrium counterparts. Such processes are of great
importance for the understanding of relaxation in single molecule devices. As a
detailed case study, we investigate here a generic spin-fermion model, where a
two-level system couples to two metallic leads with different chemical
potentials. We present results for the spin relaxation rate in the nonadiabatic
limit for an arbitrary coupling to the leads, using both analytical and exact
numerical methods. The non-equilibrium dynamics is reflected by an exponential
relaxation at long times and via complex phase shifts, leading in some cases to
an "anti-orthogonality" effect. In the limit of strong system-lead coupling at
zero temperature we demonstrate the onset of a Marcus-like Gaussian decay with
{\it voltage difference} activation. This is analogous to the equilibrium
spin-boson model, where at strong coupling and high temperatures the spin
excitation rate manifests temperature activated Gaussian behavior. We find that
there is no simple linear relationship between the role of the temperature in
the bosonic system and a voltage drop in a non-equilibrium electronic case. The
two models also differ by the orthogonality-catastrophe factor existing in a
fermionic system, which modifies the resulting lineshapes. Implications for
current characteristics are discussed. We demonstrate the violation of
pair-wise Coulomb gas behavior for strong coupling to the leads. The results
presented in this paper form the basis of an exact, non-perturbative
description of steady-state quantum dissipative systems.


title:
Systematic calculation of molecular vibrational spectra through a
  complete Morse expansion

abstract:
  We propose an accurate and efficient method to compute vibrational spectra of
molecules, based on exact diagonalization of an algebraically calculated matrix
based on powers of Morse coordinate. The present work focuses on the 1D
potential of diatomic molecules: as typical examples, we apply this method to
the standard Lennard-Jones oscillator, and to the ab initio potential of the H2
molecule. Global cm-1 accuracy is exhibited through the H2 spectrum, obtained
through the diagonalization of a 30 x 30 matrix. This theory is at the root of
a new method to obtain globally accurate vibrational spectral data in the
context of the multi-dimensional potential of polyatomic molecules, at an
affordable computational cost.


title: A Renormalization Group Approach to the Cosmological Constant Problem

abstract:
  In an earlier paper, it is proposed that, due to resonance tunneling effect,
tunneling from a large cosmological constant $\Lambda$ site in the stringy
comic landscape can be fast, while tunneling from a small $\Lambda$ site may
take exponentially long time. Borrowing the renormalization group analysis of
the conductance in the Anderson localization transition, we treat the landscape
as a multi-dimensional random potential and find that the vastness of the
landscape leads to a sharp transition at a small critical value $\Lambda_{c}$
from fast tunneling for $\Lambda > \Lambda_{c} $ to suppressed tunneling for
$\Lambda_{c} > \Lambda >0$. Mobility in the landscape makes eternal inflation
highly unlikely. As an illustration, we find that $\Lambda_{c}$ can easily be
exponentially small compared to the string/Planck scale. These properties may
help us in finding a qualitative understanding why today's dark energy is so
small.


title: Rapid Tunneling and Percolation in the Landscape

abstract:
  Motivated by the possibility of a string landscape, we reexamine tunneling of
a scalar field across single/multiple barriers. Recent investigations have
suggested modifications to the usual picture of false vacuum decay that lead to
efficient and rapid tunneling in the landscape when certain conditions are met.
This can be due to stringy effects (e.g. tunneling via the DBI action), or by
effects arising due to the presence of multiple vacua (e.g. resonance
tunneling). In this paper we discuss both DBI tunneling and resonance
tunneling. We provide a QFT treatment of resonance tunneling using the
Schr\"odinger functional approach. We also show how DBI tunneling for
supercritical barriers can naturally lead to conditions suitable for resonance
tunneling. We argue using basic ideas from percolation theory that tunneling
can be rapid in a landscape where a typical vacuum has multiple decay channels
and discuss various cosmological implications. This rapidity vacuum decay can
happen even if there are no resonance/DBI tunneling enhancements, solely due to
the presence of a large number of decay channels. Finally, we consider various
ways of circumventing a recent no-go theorem for resonance tunneling in quantum
field theory.


title: Fast estimation of multivariate stochastic volatility

abstract:
  In this paper we develop a Bayesian procedure for estimating multivariate
stochastic volatility (MSV) using state space models. A multiplicative model
based on inverted Wishart and multivariate singular beta distributions is
proposed for the evolution of the volatility, and a flexible sequential
volatility updating is employed. Being computationally fast, the resulting
estimation procedure is particularly suitable for on-line forecasting. Three
performance measures are discussed in the context of model selection: the
log-likelihood criterion, the mean of standardized one-step forecast errors,
and sequential Bayes factors. Finally, the proposed methods are applied to a
data set comprising eight exchange rates vis-a-vis the US dollar.


title: Harmonic contact metric structures, and submersions

abstract:
  We study harmonic almost contact structures in the context of contact metric
manifolds, and an analysis is carried out when such a manifold fibres over an
almost Hermitian manifold, as exemplified by the Boothby-Wang fibration. Two
types of almost contact metric warped products are also studied, relating their
harmonicity to that of the almost Hermitian structure on the base or fibre.


title:
A rate-independent model for the isothermal quasi-static evolution of
  shape-memory materials

abstract:
  This note addresses a three-dimensional model for isothermal stress-induced
transformation in shape-memory polycrystalline materials. We treat the problem
within the framework of the energetic formulation of rate-independent processes
and investigate existence and continuous dependence issues at both the
constitutive relation and quasi-static evolution level. Moreover, we focus on
time and space approximation as well as on regularization and parameter
asymptotics.


title:
A system for the simulation of simultaneous moves between two
  noncolocational players

abstract:
  We describe a new system for the simulation of simultaneous moves between
noncolocational players. This has applications in the burgeoning
Rock-Paper-Scissors by mail movement.


title: Computer Assembly of Cluster-Forming Amphiphilic Dendrimers

abstract:
  Recent theoretical studies have predicted a new clustering mechanism for soft
matter particles that interact via a certain kind of purely repulsive, bounded
potentials. At sufficiently high densities, clusters of overlapping particles
are formed in the fluid, which upon further compression crystallize into cubic
lattices with density-independent lattice constants. In this work we show that
amphiphilic dendrimers are suitable colloids for the experimental realization
of this phenomenon. Thereby, we pave the way for the synthesis of such
macromolecules, which form the basis for a novel class of materials with
unusual properties.


title: Automorphisms of Galois Coverings of Generic $m$-Canonical Projections

abstract:
  The automorphism group of the Galois covering induced by a pluri-canonical
generic covering of a projective space is investigated. It is shown that by
means of such coverings one obtains, in dimensions one and two, serieses of
specific actions of the symmetric groups $S_d$ on curves and surfaces not
deformable to an action of $S_d$ which is not the full automorphism group. As
an application, new DIF $\ne$ DEF examples for $G$-varieties in complex and
real geometry are given.


title:
Sensitivity of photonic crystal fiber grating sensors: biosensing,
  refractive index, strain, and temperature sensing

abstract:
  We study the sensitivity of fiber grating sensors in the applications of
strain, temperature, internal label-free biosensing, and internal refractive
index sensing. It is shown that optical dispersion plays a central role in
determining the sensitivity, and the dispersion may enhance or suppress
sensitivity as well as change the sign of the resonant wavelength shifts. We
propose a quality factor, $Q$, for characterizing LPGs.


title: ILC Sensitivity on Generic New Physics in Quartic Gauge Couplings

abstract:
  We investigate the potential of the ILC for measuring anomalous quartic gauge
couplings, both in production of three electroweak gauge bosons as well as in
vector boson scattering. Any new physics that could possibly couple to the
electroweak gauge bosons is classified according to its spin and isospin
quantum numbers and parameterized in terms of resonance parameters like masses,
widths, magnetic moment form factors etc. By a maximum log-likelihood fit, the
discovery reach of a 1 TeV ILC for scalar, vector and tensor resonances is
examined.


title: Thermohaline mixing in low-mass giants: RGB and beyond

abstract:
  Thermohaline mixing has recently been proposed to occur in low mass red
giants, with large consequence for the chemical yields of low mass stars. We
investigate the role of thermohaline mixing during the evolution of stars
between 1 Msun and 3 Msun. We use a stellar evolution code which includes
rotational mixing and internal magnetic fields. We confirm that thermohaline
mixing has the potential to destroy most of the helium 3 which is produced
earlier on the main sequence during the red giant stage, in stars below
1.5Msun. We find this process to continue during core helium burning and
beyond. We find rotational and magnetic mixing to be negligible compared to the
thermohaline mixing in the relevant layers, even if the interaction of
thermohaline motions with the differential rotation may be essential to
establish the time scale of thermohaline mixing in red giants.


title: Stellar Models and Yields of Asymptotic Giant Branch Stars

abstract:
  We present stellar yields calculated from detailed models of low and
intermediate-mass asymptotic giant branch (AGB) stars. We evolve models with a
range of mass from 1 to 6Msun, and initial metallicities from solar to 1/200th
of the solar metallicity. Each model was evolved from the zero age main
sequence to near the end of the thermally-pulsing AGB phase, and through all
intermediate phases including the core He-flash for stars initially less
massive than 2.5Msun. For each mass and metallicity, we provide tables
containing structural details of the stellar models during the TP-AGB phase,
and tables of the stellar yields for 74 species from hydrogen through to
sulphur, and for a small number of iron-group nuclei. All tables are available
for download. Our results have many applications including use in population
synthesis studies and the chemical evolution of galaxies and stellar systems,
and for comparison to the composition of AGB and post-AGB stars and planetary
nebulae.


title: A sufficient criterion for homotopy cartesianess

abstract:
  Suppose given a commutative quadrangle in a Verdier triangulated category
such that there exists an induced isomorphism on the horizontally taken cones.
Suppose that the endomorphism ring of the initial or the terminal corner object
of this quadrangle satisfies a finiteness condition. Then this quadrangle is
homotopy cartesian.


title: Conjugates of characteristic Sturmian words generated by morphisms

abstract:
  This article is concerned with characteristic Sturmian words of slope
$\alpha$ and $1-\alpha$ (denoted by $c_\alpha$ and $c_{1-\alpha}$
respectively), where $\alpha \in (0,1)$ is an irrational number such that
$\alpha = [0;1+d_1,\bar{d_2,...,d_n}]$ with $d_n \geq d_1 \geq 1$. It is known
that both $c_\alpha$ and $c_{1-\alpha}$ are fixed points of non-trivial
(standard) morphisms $\sigma$ and $\hat{\sigma}$, respectively, if and only if
$\alpha$ has a continued fraction expansion as above. Accordingly, such words
$c_\alpha$ and $c_{1-\alpha}$ are generated by the respective morphisms
$\sigma$ and $\hat{\sigma}$. For the particular case when $\alpha =
[0;2,\bar{r}]$ ($r\geq1$), we give a decomposition of each conjugate of
$c_\alpha$ (and hence $c_{1-\alpha}$) into generalized adjoining singular
words, by considering conjugates of powers of the standard morphism $\sigma$ by
which it is generated. This extends a recent result of Lev\'{e} and S\ee bold
on conjugates of the infinite Fibonacci word.


title: Quasi-local definitions of energy in general relativity

abstract:
  The problem of defining energy in general relativity is reviewed very
briefly, and the properties of Brown-York-like expressions are discussed.


title: Occurrences of palindromes in characteristic Sturmian words

abstract:
  This paper is concerned with palindromes occurring in characteristic Sturmian
words $c_\alpha$ of slope $\alpha$, where $\alpha \in (0,1)$ is an irrational.
As $c_\alpha$ is a uniformly recurrent infinite word, any (palindromic) factor
of $c_\alpha$ occurs infinitely many times in $c_\alpha$ with bounded gaps. Our
aim is to completely describe where palindromes occur in $c_\alpha$. In
particular, given any palindromic factor $u$ of $c_\alpha$, we shall establish
a decomposition of $c_\alpha$ with respect to the occurrences of $u$. Such a
decomposition shows precisely where $u$ occurs in $c_\alpha$, and this is
directly related to the continued fraction expansion of $\alpha$.


title:
Herwig++ Monte Carlo At Next-To-Leading Order for e+e- annihilation and
  lepton pair production

abstract:
  This paper describes the MC@NLO method for matching next-to-leading order
(NLO) perturbative QCD with the parton shower and hadronization model of the
Monte Carlo (MC) event generator tt Herwig++, for e+e- annihilation and
Drell-Yan lepton pair production. Details of the event generation method as
well as spin, flavour, momentum and colour assignments are presented. We obtain
predictions for various distributions which arecompared with experimental data.


title: CMB Cluster Lensing: Cosmography with the Longest Lever Arm

abstract:
  We discuss combining gravitational lensing of galaxies and the cosmic
microwave background (CMB) by clusters to measure cosmographic distance ratios,
and hence dark energy parameters. Advantages to using the CMB as the second
source plane, instead of galaxies, include: a well-determined source distance,
a longer lever arm for distance ratios, typically up to an order of magnitude
higher sensitivity to dark energy parameters, and a decreased sensitivity to
photometric redshift accuracy of the lens and galaxy sources. Disadvantages
include: higher statistical errors, potential systematic errors, and the need
for disparate surveys that overlap on the sky. Ongoing and planned surveys,
such as the South Pol Telescope in conjunction with the Dark Energy Survey, can
potentially reach the statistical sensitivity to make interesting consistency
tests of the standard cosmological constant model. Future measurements that
reach 1% or better precision in the convergences can provide sharp tests for
future supernovae distance measurements.


title: On the Gr\"obner complexity of matrices

abstract:
  In this paper we show that if for an integer matrix A the universal Gr\"obner
basis of the associated toric ideal \Ideal_A coincides with the Graver basis of
A, then the Gr\"obner complexity u(A) and the Graver complexity g(A) of its
higher Lawrence liftings agree, too. We conclude that for the matrices
A_{3\times 3} and A_{3\times 4}, defining the 3\times 3 and 3\times 4
transportation problems, we have u(A_{3\times 3})=g(A_{3\times 3})=9 and
u(A_{3\times 4})=g(A_{3\times 4})\geq 27. Moreover, we prove
u(A_{a,b})=g(A_{a,b})=2(a+b)/\gcd(a,b) for positive integers a,b and
A_{a,b}=(\begin{smallmatrix} 1 & 1 & 1 & 1 0 & a & b & a+b \end{smallmatrix}).


title:
Evidence for Accretion in the High-resolution X-ray Spectrum of the T
  Tauri Star System Hen 3-600

abstract:
  We present high-resolution X-ray spectra of the multiple T Tauri star system
Hen 3-600, obtained with the High Energy Transmission Grating Spectrograph on
the Chandra X-ray Observatory. Two binary components were detected in the
zeroth-order image. Hen 3-600-A, which has a large mid-infrared excess, is a
2-3 times fainter in X-rays than Hen 3-600-B, due to a large flare on B. The
dispersed X-ray spectra of the two primary components overlap spatially;
spectral analysis was performed on the combined system. Analysis of the
individual spectra was limited to regions where the contributions of A and B
can be disentangled. This analysis results in two lines of evidence indicating
that the X-ray emission from Hen 3-600 is derived from accretion processes:
line ratios of O VII indicate that the characteristic density of its
X-ray-emitting plasma is large; a significant component of low-temperature
plasma is present and is stronger in component A. These results are consistent
with results obtained from X-ray gratings spectroscopy of more rapidly
accreting systems. All of the signatures of Hen 3-600 that are potential
diagnostics of accretion activity -- X-ray emission, UV excess, H-alpha
emission, and weak infrared excess -- suggest that its components represent a
transition phase between rapidly accreting, classical T Tauri stars and
non-accreting, weak-lined T Tauri stars.


title:
Studies of Spin Effects in Charged Higgs Boson Production with an
  Iterative Discriminant Analysis at the Tevatron and LHC

abstract:
  We report on detailed Monte Carlo comparisons of selection variables to
separate tbH+ signal events from the Standard Model ttbar background using an
Iterative Discriminant Analysis (IDA) method. While kinematic differences exist
between the two processes whenever m(H+).ne.m(W+), the exploration of the spin
difference between the charged Higgs and the W+ gauge boson becomes crucial in
the particularly challenging case of near degeneracy of the charged Higgs boson
mass with the W+ mass. The TAUOLA package is used to decay the tau leptons
emerging from the charged Higgs and W+ boson decays taking the spin difference
properly into account. We demonstrate that, even if the individual selection
variables have limited discriminant power, the IDA method achieves a
significant separation between the expected signal and background. For both
Tevatron and LHC energies, the impact of the spin effects and H+ mass on the
separation of signal and background has been studied quantitatively. The effect
of a hard transverse momentum cut to remove QCD background has been studied and
it is found that the spin effects remain important. The separation is expressed
in purity versus efficiency curves. The study is performed for charged Higgs
boson masses between the W+ mass and near the top mass.


title:
Influence of the environment and probes on rapid DNA sequencing via
  transverse electronic transport

abstract:
  We study theoretically the feasibility of using transverse electronic
transport within a nanopore for rapid DNA sequencing. Specifically, we examine
the effects of the environment and detection probes on the distinguishability
of the DNA bases. We find that the intrinsic measurement bandwidth of the
electrodes helps the detection of single bases by averaging over the current
distributions of each base. We also find that although the overall magnitude of
the current may change dramatically with different detection conditions, the
intrinsic distinguishability of the bases is not significantly affected by pore
size and transverse field strength. The latter is the result of very effective
stabilization of the DNA by the transverse field induced by the probes, so long
as that field is much larger than the field that drives DNA through the pore.
In addition, the ions and water together effectively screen the charge on the
nucleotides, so that the electron states participating in the transport
properties of the latter ones resemble those of the uncharged species. Finally,
water in the environment has negligible direct influence on the transverse
electrical current.


title:
The computation of the classes of some tori in the Grothendieck ring of
  varieties

abstract:
  We establish a formula for the classes of certain tori in the Grothendieck
ring of varieties, in terms of its lambda-structure. More explicitly, we will
see that if L* is the torus of invertible elements in the n-dimensional
separable k-algebra L, then the class of L* can be expressed as an alternating
sum of the images of the spectrum of L under the lambda-operations, multiplied
by powers of the Lefschetz class. This formula is suggested from the cohomology
of the torus, illustrating a heuristic method that can be used in other
situations. To prove the formula will require some rather explicit calculations
in the Grothendieck ring. To be able to make these we introduce a homomorphism
from the Burnside ring of the absolute Galois group of k, to the Grothendieck
ring of varieties over k. In the process we obtain some information about the
structure of the subring generated by zero-dimensional varieties.


title:
Cyclic odd degree base change lifting for unitary groups in three
  variables

abstract:
  Let E/F be a quadratic number (resp. p-adic) field extension, and F' an odd
degree cyclic field extension of F. We establish a base-change functorial
lifting of automorphic (resp. admissible) representations from the unitary
group U(3,E/F) associated with E/F to the unitary group U(3,F'E/F'). As a
consequence, we classify the invariant packets of U(3,F'E/F'), namely those
which contain (irreducible) automorphic (resp. admissible) representations
which are invariant under the action of the Galois group Gal(F'E/E). To do this
we use the trace formula technique, and well-known results on the base-change
lifting from U(3,E/F) to GL(3,E) and on the base-change lifting for the general
linear groups. We also determine the invariance of individual representations,
using Howe correspondence. This work is the first study of base change into an
algebraic group whose packets are not all singletons, and which does not
satisfy the "strong multiplicity one theorem." Novel phenomena are encountered:
e.g. there are invariant packets where not every irreducible automorphic (resp.
admissible) member is Galois-invariant. We also obtain local twisted character
identities with respect to this base-change lifting.


title:
Hadronic Dijet Imbalance and Transverse-Momentum Dependent Parton
  Distributions

abstract:
  We compare several recent theoretical studies of the single transverse spin
asymmetry in dijet-correlations at hadron colliders. We show that the results
of these studies are all consistent. To establish this, we investigate in
particular the two-gluon exchange contributions to the relevant initial and
final state interactions in the context of a simplifying model. Overall, the
results confirm that the dijet imbalance obeys at best a non-standard or
"generalized" transverse-momentum-dependent factorization.


title:
Type-IV DCT, DST, and MDCT algorithms with reduced numbers of arithmetic
  operations

abstract:
  We present algorithms for the type-IV discrete cosine transform (DCT-IV) and
discrete sine transform (DST-IV), as well as for the modified discrete cosine
transform (MDCT) and its inverse, that achieve a lower count of real
multiplications and additions than previously published algorithms, without
sacrificing numerical accuracy. Asymptotically, the operation count is reduced
from ~2NlogN to ~(17/9)NlogN for a power-of-two transform size N, and the exact
count is strictly lowered for all N > 4. These results are derived by
considering the DCT to be a special case of a DFT of length 8N, with certain
symmetries, and then pruning redundant operations from a recent improved fast
Fourier transform algorithm (based on a recursive rescaling of the
conjugate-pair split radix algorithm). The improved algorithms for DST-IV and
MDCT follow immediately from the improved count for the DCT-IV.


title: Powers in a class of A-strict standard episturmian words

abstract:
  This paper concerns a specific class of strict standard episturmian words
whose directive words resemble those of characteristic Sturmian words. In
particular, we explicitly determine all integer powers occurring in such
infinite words, extending recent results of Damanik and Lenz (2003), who
studied powers in Sturmian words. The key tools in our analysis are canonical
decompositions and a generalization of singular words, which were originally
defined for the ubiquitous Fibonacci word. Our main results are demonstrated
via some examples, including the $k$-bonacci word: a generalization of the
Fibonacci word to a $k$-letter alphabet ($k\geq2$).


title: 2-gerbes and 2-Tate spaces

abstract:
  We construct a central extension of the group of automorphisms of a 2-Tate
vector space viewed as a discrete 2-group. This is done using an action of this
2-group on a 2-gerbe of gerbel theories. This central extension is used to
define central extensions of double loop groups.


title: Mirror symmetry and tropical geometry

abstract:
  Using tropical geometry we propose a mirror construction for monomial
degenerations of Calabi-Yau varieties in toric Fano varieties. The construction
reproduces the mirror constructions by Batyrev for Calabi-Yau hypersurfaces and
by Batyrev and Borisov for Calabi-Yau complete intersections. We apply the
construction to Pfaffian examples and recover the mirror given by Rodland for
the degree 14 Calabi-Yau threefold in PP^6 defined by the Pfaffians of a
general linear 7x7 skew-symmetric matrix.
  We provide the necessary background knowledge entering into the tropical
mirror construction such as toric geometry, Groebner bases, tropical geometry,
Hilbert schemes and deformations. The tropical approach yields an algorithm
which we illustrate in a series of explicit examples.


title:
VLBA determination of the distance to nearby star-forming regions II.
  Hubble 4 and HDE 283572 in Taurus

abstract:
  The non-thermal 3.6 cm radio continuum emission from the naked T Tauri stars
Hubble 4 and HDE 283572 in Taurus has been observed with the Very Long Baseline
Array (VLBA) at 6 epochs between September 2004 and December 2005 with a
typical separation between successive observations of 3 months. Thanks to the
remarkably accurate astrometry delivered by the VLBA, the trajectory described
by both stars on the plane of the sky could be traced very precisely, and
modeled as the superposition of their trigonometric parallax and uniform proper
motion. The best fits yield distances to Hubble 4 and HDE 283572 of 132.8 +/-
0.5 and 128.5 +/- 0.6 pc, respectively. Combining these results with the other
two existing VLBI distance determinations in Taurus, we estimate the mean
distance to the Taurus association to be 137 pc with a dispersion (most
probably reflecting the depth of the complex) of about 20 pc.


title:
The largest component in a subcritical random graph with a power law
  degree distribution

abstract:
  It is shown that in a subcritical random graph with given vertex degrees
satisfying a power law degree distribution with exponent $\gamma>3$, the
largest component is of order $n^{1/(\gamma-1)}$. More precisely, the order of
the largest component is approximatively given by a simple constant times the
largest vertex degree. These results are extended to several other random graph
models with power law degree distributions. This proves a conjecture by
Durrett.


title: Unparticle Physics And Gauge Coupling Unification

abstract:
  Unparticle physics from a hidden conformal sector can alter the evolution of
the Standard Model (SM) gauge couplings via TeV scale threshold corrections. We
discuss how this may lead to gauge coupling unification at M_{GUT}\approx 2
\times 10^{15} GeV -- 5 \times 10^{17} GeV without introducing new particles in
the SM sector.


title: A characterization of fine words over a finite alphabet

abstract:
  To any infinite word w over a finite alphabet A we can associate two infinite
words min(w) and max(w) such that any prefix of min(w) (resp. max(w)) is the
lexicographically smallest (resp. greatest) amongst the factors of w of the
same length. We say that an infinite word w over A is "fine" if there exists an
infinite word u such that, for any lexicographic order, min(w) = au where a =
min(A). In this paper, we characterize fine words; specifically, we prove that
an infinite word w is fine if and only if w is either a "strict episturmian
word" or a strict "skew episturmian word''. This characterization generalizes a
recent result of G. Pirillo, who proved that a fine word over a 2-letter
alphabet is either an (aperiodic) Sturmian word, or an ultimately periodic (but
not periodic) infinite word, all of whose factors are (finite) Sturmian.


title:
Algebraic Distributed Differential Space-Time Codes with Low Decoding
  Complexity

abstract:
  The differential encoding/decoding setup introduced by Kiran et al,
Oggier-Hassibi and Jing-Jafarkhani for wireless relay networks that use
codebooks consisting of unitary matrices is extended to allow codebooks
consisting of scaled unitary matrices. For such codebooks to be usable in the
Jing-Hassibi protocol for cooperative diversity, the conditions involving the
relay matrices and the codebook that need to be satisfied are identified. Using
the algebraic framework of extended Clifford algebras, a new class of
Distributed Differential Space-Time Codes satisfying these conditions for power
of two number of relays and also achieving full cooperative diversity with a
low complexity sub-optimal receiver is proposed. Simulation results indicate
that the proposed codes outperform both the cyclic codes as well as the
circulant codes. Furthermore, these codes can also be applied as Differential
Space-Time codes for non-coherent communication in classical point to point
multiple antenna systems.


title:
Moments and distribution of the local times of a transient random walk
  on $\Z^d$

abstract:
  Consider an arbitrary transient random walk on $\Z^d$ with $d\in\N$. Pick
$\alpha\in[0,\infty)$ and let $L_n(\alpha)$ be the spatial sum of the
$\alpha$-th power of the $n$-step local times of the walk. Hence, $L_n(0)$ is
the range, $L_n(1)=n+1$, and for integers $\alpha$, $L_n(\alpha)$ is the number
of the $\alpha$-fold self-intersections of the walk. We prove a strong law of
large numbers for $L_n(\alpha)$ as $n\to\infty$. Furthermore, we identify the
asymptotic law of the local time in a random site uniformly distributed over
the range. These results complement and contrast analogous results for
recurrent walks in two dimensions recently derived by \v{C}ern\'y \cite{Ce07}.
Although these assertions are certainly known to experts, we could find no
proof in the literature in this generality.


title:
Characterizations of finite and infinite episturmian words via
  lexicographic orderings

abstract:
  In this paper, we characterize by lexicographic order all finite Sturmian and
episturmian words, i.e., all (finite) factors of such infinite words.
Consequently, we obtain a characterization of infinite episturmian words in a
"wide sense" (episturmian and episkew infinite words). That is, we characterize
the set of all infinite words whose factors are (finite) episturmian.
Similarly, we characterize by lexicographic order all balanced infinite words
over a 2-letter alphabet; in other words, all Sturmian and skew infinite words,
the factors of which are (finite) Sturmian.


title: 2-soft-gluon exchange and factorization breaking

abstract:
  A previous counterexample to disprove k_T-factorization for H_1+H_2 -->
H_3+H_4+X is extended calculationally to one higher order in gluon exchange.
The result is that, by explicit calculation, standard k_T-factorization fails
for the unpolarized cross-section for the production of hadrons of high
transverse momentum in hadron-hadron collisions.


title: Pauli Paramagnetic Effects on Vortices in Superconducting TmNi2B2C

abstract:
  The magnetic field distribution around the vortices in TmNi2B2C in the
paramagnetic phase was studied experimentally as well as theoretically. The
vortex form factor, measured by small-angle neutron scattering, is found to be
field independent up to 0.6 Hc2 followed by a sharp decrease at higher fields.
The data are fitted well by solutions to the Eilenberger equations when
paramagnetic effects due to the exchange interaction with the localized 4f Tm
moments are included. The induced paramagnetic moments around the vortex cores
act to maintain the field contrast probed by the form factor.


title: Increasing the Efficiency of Energy Scavengers

abstract:
  In this paper, a methodology for designing efficient energy scavengers is
proposed. The scavenger consists of a cantilever beam on which piezoelectric
films and a mass are mounted. The mass at the tip of the beam is known as the
proof mass and the device is called either an energy scavenger or a beam-mass
system. The proof mass is a permanent magnet, where in its vicinity attracting
permanent magnets are placed. It is shown that when the magnets have
appropriate strengths and are placed appropriately, the vibration of the
beam-mass system can be amplified, thereby the scavenged energy is increased.
Examples are given throughout the paper.


title: IC 4406: a radio-infrared comparison

abstract:
  IC 4406 is a large (about 100'' x 30'') southern bipolar planetary nebula,
composed by two elongated lobes, extending from a bright central region, where
there is evidence for the presence of a large torus of gas and dust. In this
poster we show new observations of this source performed with IRAC (Spitzer
Space Telescope) and the Australia Telescope Compact Array. Although the
possibility for faint extended emission to be missing in the radio maps cannot
be ruled out, flux from the ionized gas appears to be concentrated in the
bright central region. Comparing ATCA to IRAC images, it seems that, like in
other planetary nebulae, ionized and neutral components spatially co-exist in
IC 4406.


title: Large Gravitational Waves and Lyth Bound in Multi Brane Inflation

abstract:
  It is shown that multi M5-brane inflation in heterotic M-theory gives rise to
a detectable gravitational wave power spectrum with tensor fraction $r$
typically larger than the projected experimental sensitivity, $r_{exp} = 0.01$.
A measurable gravitational wave power spectrum entails a large inflationary
energy scale and a super-Planckian inflaton variation. They present serious
problems for particle theory model building resp. a reliable effective field
theory description. These problems are eased or even absent in multi-brane
inflation models and multi M5-brane inflation, in particular.


title: Highest weight state description of the isotropic spin-1 chain

abstract:
  We introduce an overcomplete highest weight state basis as a calculational
tool for the description of the isotropic spin-1 chain with bilinear exchange
coupling J1 and biquadratic coupling J2. The ground state can be expressed
exactly at the three special points in the phase diagram where the Hamiltonian
corresponds to a sum of nearest neighbor total spin projection operators
(J1=0>J2, J1=-J2<0, and J1=-J2/3<0). In particular, at the phase transition
point J1=-J2<0 it is possible to exactly compute the ground states, excited
states, expectation values, and correlation functions by using the new total
spin basis.


title:
Searching for Inflation in Simple String Theory Models: An Astrophysical
  Perspective

abstract:
  Attempts to connect string theory with astrophysical observation are hampered
by a jargon barrier, where an intimidating profusion of orientifolds, Kahler
potentials, etc. dissuades cosmologists from attempting to work out the
astrophysical observables of specific string theory solutions from the recent
literature. We attempt to help bridge this gap by giving a pedagogical
exposition with detailed examples, aimed at astrophysicists and high energy
theorists alike, of how to compute predictions for familiar cosmological
parameters when starting with a 10-dimensional string theory action. This is
done by investigating inflation in string theory, since inflation is the
dominant paradigm for how early universe physics determines cosmological
parameters.
  We analyze three explicit string models from the recent literature, each
containing an infinite number of "vacuum" solutions. Our numerical
investigation of some natural candidate inflatons, the so-called "moduli
fields", fails to find inflation. We also find in the simplest models that,
after suitable field redefinitions, vast numbers of these vacua differ only in
an overall constant multiplying the effective inflaton potential, a difference
which affects neither the potential's shape nor its ability to support
slow-roll inflation. This illustrates that even having an infinite number of
vacua does not guarantee having inflating ones. This may be an artifact of the
simplicity of the models that we study. Instead, more complicated string theory
models appear to be required, suggesting that explicitly identifying the
inflating subset of the string landscape will be challenging.


title: Probing Gravity with Spacetime Sirens

abstract:
  A gravitational observatory such as LISA will detect coalescing pairs of
massive black holes, accurately measure their luminosity distance and help
identify a host galaxy or an electromagnetic counterpart. If dark energy is a
manifestation of modified gravity on large scales, gravitational waves from
cosmologically-distant spacetime sirens are direct probes of this new physics.
For example, a gravitational Hubble diagram based on black hole pair luminosity
distances and host galaxy redshifts could reveal a large distance
extra-dimensional leakage of gravity. Various additional signatures may be
expected in a gravitational signal propagated over cosmological scales.


title: Spectropolarimetry of SN 2006aj at 9.6 days

abstract:
  The observational technique of spectropolarimetry has been used to directly
measure the asymmetries of Supernovae (SNe), Gamma-Ray Bursts (GRBs) and X-Ray
Flashes (XRFs). We wish to determine if non-axial asymmetries are present in
SNe that are associated with GRBs and XRFs, given the particular alignment of
the jet axis and axis of symmetry with the line of sight in these cases. We
performed spectropolarimetry with the Very Large Telescope (VLT) FORS1
instrument of the Type Ic SN 2006aj, associated with the XRF 060218, at V-band
maximum at 9.6 rest frame days after the detection of the XRF. Due to
observations at only 3 retarder plate angles, the data were reduced assuming
that the instrumental signature correction for the $U$ Stokes parameter was
identical to the correction measured for $Q$. We find SN 2006aj to be highly
polarized at wavelengths corresponding to the absorption minima of certain
spectral lines, particularly strong for O I 7774\AA and Fe II, observed at
4200\AA with a polarization 3%. The value of the Interstellar Polarization is
not well constrained by these observations and, considering the low
polarization observed between 6000-6500\AA, the global asymmetry of the SN is
$\lesssim 15%$. O I and Fe II lines share a polarization angle that differs
from Ca II. SN 2006aj exhibits a higher degree of line polarization than other
SNe associated with GRBs and XRFs. The polarization associated with spectral
lines implies significant asymmetries of these elements with respect to each
other and to the line of sight. This is contrary to the standard picture of SNe
associated with GRBs/XRFs, where the axis of symmetry of the SN is aligned with
the GRB jet axis and the line of sight.


title:
A resonant-term-based model including a nascent disk, precession, and
  oblateness: application to GJ 876

abstract:
  Investigations of two resonant planets orbiting a star or two resonant
satellites orbiting a planet often rely on a few resonant and secular terms in
order to obtain a representative quantitative description of the system's
dynamical evolution. We present a semianalytic model which traces the orbital
evolution of any two resonant bodies in a first- through fourth-order
eccentricity or inclination-based resonance dominated by the resonant and
secular arguments of the user's choosing. By considering the variation of
libration width with different orbital parameters, we identify regions of phase
space which give rise to different resonant ''depths,'' and propose methods to
model libration profiles. We apply the model to the GJ 876 extrasolar planetary
system, quantify the relative importance of the relevant resonant and secular
contributions, and thereby assess the goodness of the common approximation of
representing the system by just the presumably dominant terms. We highlight the
danger in using ''order'' as the metric for accuracy in the orbital solution by
revealing the unnatural libration centers produced by the second-order, but not
first-order, solution, and by demonstrating that the true orbital solution lies
somewhere ''in-between'' the third- and fourth-order solutions. We also present
formulas used to incorporate perturbations from central-body oblateness and
precession, and a protoplanetary or protosatellite thin disk with gaps, into a
resonant system. We quantify these contributions to the GJ 876 system, and
thereby highlight the conditions which must exist for multi-planet exosystems
to be significantly influenced by such factors. We find that massive enough
disks may convert resonant libration into circulation; such disk-induced
signatures may provide constraints for future studies of exoplanet systems.


title: Local Unitary Quantum Cellular Automata

abstract:
  In this paper we present a quantization of Cellular Automata. Our formalism
is based on a lattice of qudits, and an update rule consisting of local unitary
operators that commute with their own lattice translations. One purpose of this
model is to act as a theoretical model of quantum computation, similar to the
quantum circuit model. It is also shown to be an appropriate abstraction for
space-homogeneous quantum phenomena, such as quantum lattice gases, spin chains
and others. Some results that show the benefits of basing the model on local
unitary operators are shown: universality, strong connections to the circuit
model, simple implementation on quantum hardware, and a wealth of applications.


title: LHC Signals for Warped Electroweak Neutral Gauge Bosons

abstract:
  We study signals at the Large Hadron Collider (LHC) for Kaluza-Klein (KK)
excitations of the electroweak gauge bosons in the framework with the Standard
Model (SM) gauge and fermion fields propagating in a warped extra dimension.
Such a framework addresses both the Planck-weak and flavor hierarchy problems
of the SM. Unlike the often studied Z' cases, in this framework, there are
three neutral gauge bosons due to the underlying SU(2)_L x SU(2)_R x U(1)_X
gauge group in the bulk. Furthermore, couplings of these KK states to light
quarks and leptons are suppressed, whereas those to top and bottom quarks are
enhanced compared to the SM gauge couplings. Therefore, the production of light
quark and lepton states is suppressed relative to other beyond the SM
constructions, and the fermionic decays of these states are dominated by the
top and bottom quarks, which are, though, overwhelmed by KK gluons dominantly
decaying into them. However, as we emphasize in this paper, decays of these
states to longitudinal W, Z and Higgs are also enhanced similarly to the case
of top and bottom quarks. We show that the W, Z and Higgs final states can give
significant sensitivity at the LHC to 2 (3) TeV KK scale with an integrated
luminosity of 100 invfb (1 invab). Since current theoretical framework(s) favor
KK masses greater than about 3 TeV, luminosity upgrade of LHC is likely to be
crucial in observing these states.


title: Lattice QCD determination of patterns of excited baryon states

abstract:
  Energies for excited isospin I=1/2 and I=3/2 states that include the nucleon
and Delta families of baryons are computed using quenched, anisotropic
lattices. Baryon interpolating field operators that are used include nonlocal
operators that provide G_2 irreducible representations of the octahedral group.
The decomposition of spin 5/2 or higher spin states is realized for the first
time in a lattice QCD calculation. We observe patterns of degenerate energies
in the irreducible representations of the octahedral group that correspond to
the subduction of the continuum spin 5/2 or higher. The overall pattern of
low-lying excited states corresponds well to the pattern of physical states
subduced to the irreducible representations of the octahedral group.


title: Consequences of a Cosmic Scalar with Kinetic Coupling to Curvature

abstract:
  The classical gravitational theory of a scalar field with a gradient coupling
to the Ricci tensor is examined. This is a scalar-vector-tensor gravitational
theory, but in the case that the coupling is weak and the scalar evolves like a
quintessence field on cosmological time scales, the field equations within the
solar system are similar to a vector-tensor theory predicting
tightly-constrained preferred-frame effects. In the early universe, it is shown
that strong coupling effects can damp the evolution of the scalar field rolling
down a potential to help drive an inflationary epoch. In the absence of a
potential, the strong coupling effects drive a coasting expansion epoch which
ultimately terminates in a sudden singularity.


title:
Generation of four-qubit cluster of entangled coherent states in bimodal
  QED cavities

abstract:
  A recent work [1] proposed a type of cluster entangled coherent states and
its generation. Here we present an alternative experimental arrangement for its
generation in bimodal QED cavities. The scheme employs a single two-level atom
that interacts dispersively with cavity modes initially prepared in coherent
states. The fidelity and success probability of the state preparation are
obtained considering the influence of atomic velocity spread and atomic
efficiency detection.


title:
Freeness with amalgamation, limit theorems and S-transform in
  non-commutative probability spaces of type B

abstract:
  The present material addresses several problems left open in the Trans. AMS
paper " Non-crossing cumulants of type B" of P. Biane, F. Goodman and A. Nica.
The main result is that a type B non-commutative probability space can be
studied in the framework of freeness with amalgamation. This view allows easy
ways of constructing a version of the S-transform as well as proving analogue
results to Central Limit Theorem and Poisson Limit Theorem.


title:
Observation of persistent flow of a Bose-Einstein condensate in a
  toroidal trap

abstract:
  We have observed the persistent flow of Bose-condensed atoms in a toroidal
trap. The flow persists without decay for up to 10 s, limited only by
experimental factors such as drift and trap lifetime. The quantized rotation
was initiated by transferring one unit, $\hbar$, of the orbital angular
momentum from Laguerre-Gaussian photons to each atom. Stable flow was only
possible when the trap was multiply-connected, and was observed with a BEC
fraction as small as 15%. We also created flow with two units of angular
momentum, and observed its splitting into two singly-charged vortices when the
trap geometry was changed from multiply- to simply-connected.


title: On Selfadjoint Subspace of One-Speed Boltzmann Operator

abstract:
  The aim of the paper is to obtain a description of the selfadjoint subspace
of the one-speed Boltzmann operator. It is proved that this subspace is
nontrivial if the collision integral is polynomial and the multiplication
coefficient has a lattice of gaps. A similar result is shown to hold for the
3-dimensional transport operator.
  Keywords: completely nonselfadjoint, Boltzmann operator, uncertainly
principle.


title:
Accurate determination of electric-dipole matrix elements in K and Rb
  from Stark shift measurements

abstract:
  Stark shifts of potassium and rubidium D1 lines have been measured with high
precision by Miller et al [1]. In this work, we combine these measurements with
our all-order calculations to determine the values of the electric-dipole
matrix elements for the 4p_j-3d_j' transitions in K and for the 5p_j-4d_j'
transitions in Rb to high precision. The 4p_1/2-3d_3/2 and 5p_1/2-4d_3/2
transitions contribute on the order of 90% to the respective polarizabilities
of the np_1/2 states in K and Rb, and the remaining 10% can be accurately
calculated using the relativistic all-order method. Therefore, the combination
of the experimental data and theoretical calculations allows us to determine
the np-(n-1)d matrix elements and their uncertainties. We compare these values
with our all-order calculations of the np-(n-1)d matrix elements in K and Rb
for a benchmark test of the accuracy of the all-order method for transitions
involving nd states. Such matrix elements are of special interest for many
applications, such as determination of magic wavelengths in alkali-metal atoms
for state-insensitive cooling and trapping and determination of blackbody
radiation shifts in optical frequency standards with ions.


title: Noncommutative Einstein Equations

abstract:
  We study a noncommutative deformation of general relativity where the
gravitational field is described by a matrix-valued symmetric two-tensor field.
The equations of motion are derived in the framework of this new theory by
varying a diffeomorphisms and gauge invariant action constructed by using a
matrix-valued scalar curvature. Interestingly the genuine noncommutative part
of the dynamical equations is described only in terms of a particular tensor
density that vanishes identically in the commutative limit. A noncommutative
generalization of the energy-momentum tensor for the matter field is studied as
well.


title: Generalized Parton Distributions from Hadronic Observables

abstract:
  We propose a physically motivated parametrization for the unpolarized
generalized parton distributions, H and E, valid at both zero and non-zero
values of the skewness variable, \zeta. At \zeta=0, H and E are determined
using constraints from simultaneous fits of experimental data on both the
nucleon elastic form factors and the deep inelastic structure functions.
Lattice calculations of the higher moments constrain the parametrization at
\zeta > 0. Our method provides a step towards a model independent extraction of
generalized distributions from the data that is alternative to the mathematical
ansatz of double distributions.


title:
Brownian motion of a charged particle driven internally by correlated
  noise

abstract:
  We give an exact solution to the generalized Langevin equation of motion of a
charged Brownian particle in a uniform magnetic field that is driven internally
by an exponentially-correlated stochastic force. A strong dissipation regime is
described in which the ensemble-averaged fluctuations of the velocity exhibit
transient oscillations that arise from memory effects. Also, we calculate
generalized diffusion coefficients describing the transport of these particles
and briefly discuss how they are affected by the magnetic field strength and
correlation time. Our asymptotic results are extended to the general case of
internal driving by correlated Gaussian stochastic forces with finite
autocorrelation times.


title:
Arithmetical and geometrical means of generalized logarithmic and
  exponential functions: generalized sum and product operators

abstract:
  One-parameter generalizations of the logarithmic and exponential functions
have been obtained as well as algebraic operators to retrieve extensivity.
Analytical expressions for the successive applications of the sum or product
operators on several values of a variable are obtained here. Applications of
the above formalism are considered.


title:
Strongly Correlated Superconductivity: a plaquette Dynamical mean field
  theory study

abstract:
  We use cluster Dynamical Mean Field Theory to study the simplest models of
correlated electrons, the Hubbard model and the t-J model. We use a plaquette
embedded in a medium as a reference frame to compute and interpret the physical
properties of these models. We study various observables such as electronic
lifetimes, one electron spectra, optical conductivities, superconducting
stiffness, and the spin response in both the normal and the superconducting
state in terms of correlation functions of the embedded cluster. We find that
the shortest electron lifetime occurs near optimal doping where the
superconducting critical temperature is maximal. A second critical doping
connected to the change of topology of the Fermi surface is also identified.
The mean field theory provides a simple physical picture of three doping
regimes, the underdoped, the overdoped and the optimally doped regime in terms
of the physics of the quantum plaquette impurity model. We compare the
plaquette Dynamical Mean Field Theory results with earlier resonating valence
bond mean field theories, noting the improved description of the momentum space
anisotropy of the normal state properties and the doping dependence of the
coefficient of the linear temperature dependence of the superfluid density in
the superconducting state.


title:
Real Space Multiple Scattering Calculations of Relativistic Electron
  Energy Loss Spectra

abstract:
  {\it Ab initio} calculations of relativistic electron energy loss spectra
(REELS) are carried out using a generalization of the real-space Green's
function code FEFF8 which is applicable to general aperiodic materials. Our
approach incorporates relativistic effects in terms of the cross-section tensor
within the dipole selection rule. In particular the approach explains
relativistic corrections to the magic angle in polarized EELS experiments. Our
generalization includes instrumental effects, such as the integral of the cross
section over the impulse transfer dependence, to account for a finite detector
aperture and electron beam width. The approach is illustrated with an
application to the graphite C K edge.


title:
Methods for Producing Decoherence-Free States and Noiseless Subsystems
  Using Photonic Qutrits

abstract:
  We outline a proposal for a method of preparing an encoded two-state system
(logical qubit) that is immune to collective noise acting on the Hilbert space
of the states supporting it. The logical qubit is comprised of three photonic
three-state systems (qutrits) and is generated by the process of spontaneous
parametric down conversion. The states are constructed using linear optical
elements along with three down-conversion sources, and are deemed successful by
the simultaneous detection of six events. We also show how to select a
maximally entangled state of two qutrits by similar methods. For this maximally
entangled state we describe conditions for the state to be decoherence-free
which do not correspond to collective errors.


title: Critical Metallicities for Second-Generation Stars

abstract:
  The first massive stars may influence the formation of second-generation
stars, in part by their metal enrichment of the surrounding gas. We investigate
the "critical metallicity", defined as the the value, Z_crit, at which
primordial gas cools more efficiently by fine-structure lines of O I (63.18
microns, Si II 34.8 microns, Fe II (25.99 and 35.35 microns), and C II (157.74
microns) than by either H I or H2 line emission. We explore the time-dependent
thermodynamics and fragmentation of cooling gas at redshifts z = 10-30, seeded
by trace heavy elements expelled from early supernovae. Because different modes
of nucleosynthesis (alpha-process, Fe-group) produce abundance ratios far from
solar values, these early stellar populations are likely to be influenced by O,
Si, and Fe cooling. Our models also include radiative coupling of the fine
structure lines and H2 to the cosmic microwave background (CMB), which sets a
temperature floor (70-80K at z = 25-30) that may increase the Jeans mass. The
H2 forms from catalytic effects of electrons left over from the recombination
epoch or produced during virialization. These electrons form the H^- ion (H + e
-> H- + gamma), which in turn forms H2 through associative detachment (H- + H
-> H2 + e). In virialized halos at z = 10-30, the gas densities (n = 1-100
cm^{-3}) are well below the critical densities, n_cr = 10^{5-6} cm^{-3}, at
which (O, Si, Fe) fine-structure lines reach LTE populations and produce their
most efficient cooling. Thus, Z_crit may initially exceed 0.01 Z_sun at n =
1-100 cm^{-3}, and then drop to 10^{-3.5} Z_sun at n = 10^6 cm^{-3}, where the
Jeans mass may be imprinted on the stellar mass function. Primordial clouds of
10^8 M_sun at 0.01 Z_sun and 200K will produce redshifted fine structure lines,
with fluxes between 10^{-22} and 10^{-21} Watts/m^2 at z = 4.


title: A note on the Verlinde bundles on elliptic curves

abstract:
  We study the splitting properties of the Verlinde bundles over elliptic
curves. Our methods rely on the explicit description of the moduli space of
semistable vector bundles on elliptic curves, and on the analysis of the
symmetric powers of the Schrodinger representation of the Theta group.


title:
Population Dynamics of Children and Adolescents without Problematic
  Behavior

abstract:
  In this work we suggest a simple mathematical model for the dynamics of the
population of children and adolescents without problematic behavior (criminal
activities etc.). This model represents a typical population growth equation
but with time dependent (linearly decreasing) population growth coefficient.
Given equation admits definition of the half-life time of the non-problematic
children behavior as well as a criterion for estimation of the social
regulation of the children behavior.


title: Borges Dilemma, Fundamental Laws, and Systems Biology

abstract:
  I reason here that the known folk law in biology that there is no general law
in biology because of exceptions is false. The (quantitative) systems biology
offers the potential to solve the Borges Dilemma, by transcending it. There
have already a plenty of indications on this trend.


title: Sofic groups and profinite topology on free groups

abstract:
  We give a definition of weakly sofic groups (w-sofic groups). Our definition
is rather natural extension of the definition of sofic groups where instead of
Hamming metric on symmetric groups we use general bi-invariant metrics on
finite groups. The existence of non w-sofic groups is equivalent to some
conjecture about profinite topology on free groups.


title:
Robustness of entangled states that are positive under partial
  transposition

abstract:
  We study robustness of bipartite entangled states that are positive under
partial transposition (PPT). It is shown that almost all PPT entangled states
are unconditionally robust, in the sense, both inseparability and positivity
are preserved under sufficiently small perturbations in its immediate
neighborhood. Such unconditionally robust PPT entangled states lie inside an
open PPT entangled ball. We construct examples of such balls whose radii are
shown to be finite and can be explicitly calculated. This provides a lower
bound on the volume of all PPT entangled states. Multipartite generalization of
our constructions are also outlined.


title: Hidden Life of Riemann's Zeta Function 2. Electrons and Trains

abstract:
  The Riemann Hypothesis can be reformulated as statements about the
eigenvalues of certain matrices whose entries are defined in terms of the
Taylor coefficients of the zeta function. These eigenvalues exhibit interesting
visual patterns allowing one to state a number of conjectures.
  The Hankel matrices introduced here are obtained, by rearranging of columns,
from Toeplitz matrices whose eigenvalues were considered in arXiv:0707.1983 .
The present paper is a continuation of that publication.


title: New Extremely Metal-Poor Stars in the Galactic Halo

abstract:
  We present a detailed abundance analysis based on high resolution and high
signal-to-noise spectra of eight extremely metal poor (EMP) stars with [Fe/H] <
-3.5$ dex, four of which are new. Only stars with 4900 < Teff< 5650 K are
included. Two stars of the eight are outliers in each of several abundance
ratios. The most metal poor star in this sample, HE1424-0241, has [Fe/H] ~ -4
dex and is thus among the most metal poor stars known in the Galaxy. It has
highly anomalous abundance ratios unlike those of any other known EMP giant,
with very low Si, Ca and Ti relative to Fe, and enhanced Mn and Co, again
relative to Fe. Only (low) upper limits for C and N can be derived from the
non-detection of the CH and NH molecular bands. HE0132$-$2429, another sample
star, has excesses of N and Sc with respect to Fe. The strong outliers in
abundance ratios among the Fe-peak elements in these C-normal stars, not found
at somewhat higher metallicities, are definitely real. They suggest that at
such low metallicities we are beginning to see the anticipated and long sought
stochastic effects of individual supernova events contributing to the Fe-peak
material within a single star. A detailed comparison of the results of the
analysis procedures adopted by our 0Z project compared to those of the First
Stars VLT Large Project finds a systematic difference for [Fe/H] of ~0.3 dex,
our values always being higher.


title:
Local atomic arrangement and martensitic transformation in
  Ni$_{50}$Mn$_{35}$In$_{15}$: An EXAFS Study

abstract:
  Heusler alloys that undergo martensitic transformation in ferromagnetic state
are of increasing scientific and technological interest. These alloys show
large magnetic field induced strains upon martensitic phase change thus making
it a potential candidate for magneto-mechanical actuation. The crystal
structure of martensite is an important factor that affects both the magnetic
anisotropy and mechanical properties of such materials. Moreover, the local
chemical arrangement of constituent atoms is vital in determining the overall
physical properties. Ni$_{50}$Mn$_{35}$In$_{15}$ is one such ferromagnetic
shape memory alloy that displays exotic properties like large magnetoresistance
at moderate field values. In this work, we present the extended x-ray
absorption fine-structure measurements (EXAFS) on the bulk
Ni$_{50}$Mn$_{35}$In$_{15}$ which reveal the local structural change that
occurs upon phase transformation. The change in the bond lengths between
different atomic species helps in understanding the type of hybridization which
is an important factor in driving such Ni-Mn based systems towards martensitic
transformation.


title:
Alexander Duality and Serre's Property $(S_i)$ for Square-free Monomial
  Ideals

abstract:
  In this note, we study Serre's property $(S_i)$, and its relation to
Alexander duality for monomial ideals in a polynomial ring over a field. We
describe ideals that define the non-Cohen-Macaulay- and the non-$(S_i)$-loci of
finitely generated modules over regular rings, and show that minimal prime
ideals in these loci are homogeneous, in the graded case. We show that a
square-free monomial ideal has property $(S_i)$ if and only if its Alexander
dual has a linear resolution up to homological degree $i-1$. We prove that for
square-free monomial ideals, having property $(S_2)$ is equivalent to being
locally connected in codimension 1.


title: Thermal Logic Gates: Computation with phonons

abstract:
  Logic gates are basic digital elements for computers. We build up thermal
logic gates that can perform similar operations as their electronic
counterparts. The thermal logic gates are based on the nonlinear lattices,
which exhibit very intriguing phenomena due to their temperature dependent
power spectra. We demonstrate that phonons, the heat carriers, can be also used
to carry information and processed accordingly. The possibility of nanoscale
experiment is discussed.


title: Generalized Quantum Hydrodynamics and Principles of non-Local Physics

abstract:
  This paper addresses the fundamental principles of generalized Boltzmann
physical kinetics, as a part of non-local physics. It is shown that the theory
of transport processes (including quantum mechanics) can be considered in the
frame of unified theory based on the non-local physical description. The paper
can be considered also as comments and prolongation of the materials published
in the known author's monograph (Boris V. Alexeev, Generalized Boltzmann
Physical Kinetics. Elsevier. 2004).


title: Chern classes of Deligne-Mumford stacks and their coarse moduli spaces

abstract:
  Let $X$ be a complex projective algebraic variety with Gorenstein quotient
singularities and $\X$ a smooth Deligne-Mumford stack having $X$ as its coarse
moduli space. We show that the CSM class $c^{SM}(X)$ coincides with the
pushforward to $X$ of the total Chern class $c(T_{I\X})$ of the inertia stack
$I\X$. We also show that the stringy Chern class $c_{str}(X)$ of $X$, whenever
is defined, coincides with the pushforward to $X$ of the total Chern class
$c(T_{II\X})$ of the double inertia stack $II\X$. Some consequences concerning
stringy/orbifold Hodge numbers are deduced.