title:
Polar Kerr Effect Measurements of YBa2Cu3O6+x: Evidence for Broken
  Symmetry Near the Pseudogap Temperature

abstract:
  Polar Kerr effect in the high-Tc superconductor \YBCO was measured at zero
magnetic field with high precision using a cyogenic Sagnac fiber
interferometer. We observed non-zero Kerr rotations of order $\sim 1 \mu$rad
appearing near the pseudogap temperature $T^*$, and marking what appears to be
a true phase transition. Anomalous magnetic behavior in magnetic-field training
of the effect suggests that time reversal symmetry is already broken above room
temperature.


title: Weak homogeneity in generalized function algebras

abstract:
  In this paper, weakly homogeneous generalized functions in the special
Colombeau algebras are determined up to equality in the sense of generalized
distributions. This yields characterizations that are formally similar to
distribution theory. Further, we give several characterizations of equality in
the sense of generalized distributions in these algebras.


title: The two flavour Schwinger model: scaling of the scalar condensate

abstract:
  We investigate the continuum limit scaling of the scalar condensate in the
$N_f=2$ Schwinger model on the lattice. We employ maximally twisted mass Wilson
fermions and overlap fermions. We compute the scalar condensate by taking the
trace of the propagator (direct method) and by utilizing the integrated
Ward-Takahashi identity. While the scalar condensate comes out consistent using
these two methods for a given kind of lattice fermions, we find --quite
surprisingly-- large discrepancies for the scalar condensate between twisted
mass and overlap fermions. These discrepancies are only resolved when using the
point split current for twisted mass fermions.


title: Exponential sensitivity of noise-driven switching in genetic networks

abstract:
  Cells are known to utilize biochemical noise to probabilistically switch
between distinct gene expression states. We demonstrate that such noise-driven
switching is dominated by tails of probability distributions and is therefore
exponentially sensitive to changes in physiological parameters such as
transcription and translation rates. However, provided mRNA lifetimes are
short, switching can still be accurately simulated using protein-only models of
gene expression. Exponential sensitivity limits the robustness of noise-driven
switching, suggesting cells may use other mechanisms in order to switch
reliably.


title: On the Coupling Problem of Higher Spin Fields in 2+1 Dimension

abstract:
  The coupling problem of higher spin fields with a non dynamical background is
revisited, focussing our attention in 2+1 dimensional space-time. Starting with
a suitable Lagrangian field formulation, we study causality and the
conservation of local degrees of freedom in a theory with gravitational (no
dynamical) interaction, verifying that this type of theories must be consistent
only in some space-time (i.e., dS/AdS). On the other hand, we consider the
gravitational field as a dynamical object coupled with material fields as
sources, from the point of view of a Yang-Mills gauge formulation for gravity.
There we found some constraints on the shape of material fields and we show
that introduction of auxiliary fields coupled with gauge connection does
eliminate those constraints. The model of a Yang-Mills gauge formulation for
topological massive gravity with cosmological constant is briefly introduced
and we show that its field equations are consistent with the well known
cosmologically extended topological massive gravity of Deser at the torsionless
limit.


title: Electromagnetic wave-particle with spin and magnetic moment

abstract:
  An axisymmetric static solution of a nonlinear electrodynamics is considered
as a massive charged particle with spin and magnetic moment. A linearization of
the nonlinear electrodynamics around the static solution is investigated. The
appropriate problem for linear waves around the static solution is considered.
This wave part of the particle solution is considered to provide the
appropriate wave properties for the particle. It has been found that the right
(experimentally proved) formula for frequency of this wave appears
theoretically for the static solution with ring singularity.


title:
Mesonic interactions and their contribution to strong phases in flavor
  physics

abstract:
  We analyze the contributions of hadronic final-state interactions to the
strong phases generated in the B -> Kpipi weak decays. To this end, we develop
an alternative approach to the commonly employed isobar model based upon scalar
and vector form factors for pion-pion and pion-kaon interactions.


title:
Error Exponents of Erasure/List Decoding Revisited via Moments of
  Distance Enumerators

abstract:
  The analysis of random coding error exponents pertaining to erasure/list
decoding, due to Forney, is revisited. Instead of using Jensen's inequality as
well as some other inequalities in the derivation, we demonstrate that an
exponentially tight analysis can be carried out by assessing the relevant
moments of a certain distance enumerator. The resulting bound has the following
advantages: (i) it is at least as tight as Forney's bound, (ii) under certain
symmetry conditions associated with the channel and the random coding
distribution, it is simpler than Forney's bound in the sense that it involves
an optimization over one parameter only (rather than two), and (iii) in certain
special cases, like the binary symmetric channel (BSC), the optimum value of
this parameter can be found in closed form, and so, there is no need to conduct
a numerical search. We have not found yet, however, a numerical example where
this new bound is strictly better than Forney's bound. This may provide an
additional evidence to support Forney's conjecture that his bound is tight for
the average code. We believe that the technique we suggest in this paper can be
useful in simplifying, and hopefully also improving, exponential error bounds
in other problem settings as well.


title:
Cohomology of groups in o-minimal structures: acyclicity of the
  infinitesimal subgroup

abstract:
  By recent work on some conjectures of Pillay, each definably compact group in
a saturated o-minimal structure is an expansion of a compact Lie group by a
torsion free normal divisible subgroup, called its infinitesimal subgroup. We
show that the infinitesimal subgroup is cohomologically acyclic. This implies
that the functorial correspondence between definably compact groups and Lie
groups preserves the cohomology.


title: Sparsity in time-frequency representations

abstract:
  We consider signals and operators in finite dimension which have sparse
time-frequency representations. As main result we show that an $S$-sparse Gabor
representation in $\mathbb{C}^n$ with respect to a random unimodular window can
be recovered by Basis Pursuit with high probability provided that $S\leq
Cn/\log(n)$. Our results are applicable to the channel estimation problem in
wireless communications and they establish the usefulness of a class of
measurement matrices for compressive sensing.


title: Isotopic Anomalies in CP Stars: Helium, Mercury, Platinum, and Calcium

abstract:
  We review the classical observational results for isotopic abundance
variations for several elements in CP stars. We concentrate on the "newest"
anomaly, in calcium. The cosmically very rare isotope, Ca-48 can rival and even
dominate the more common, alpha nuclide, Ca-40. Relevant examples are found in
the hot, non-magnetic HgMn stars, and the field horizontal-branch star, Feige
86. The calcium anomaly is also present in cool, magnetic stars, including the
notorious HD 101065, Przybylski's star.


title: Star Spot Induced Radial Velocity Variability in LkCa 19

abstract:
  We describe a new radial velocity survey of T Tauri stars and present the
first results. Our search is motivated by an interest in detecting massive
young planets, as well as investigating the origin of the brown dwarf desert.
As part of this survey, we discovered large-amplitude, periodic, radial
velocity variations in the spectrum of the weak line T Tauri star LkCa 19.
Using line bisector analysis and a new simulation of the effect of star spots
on the photometric and radial velocity variability of T Tauri stars, we show
that our measured radial velocities for LkCa19 are fully consistent with
variations caused by the presence of large star spots on this rapidly rotating
young star. These results illustrate the level of activity-induced radial
velocity noise associated with at least some very young stars. This
activity-induced noise will set lower limits on the mass of a companion
detectable around LkCa 19, and similarly active young stars.


title: Effect of initial configuration on network-based recommendation

abstract:
  In this paper, based on a weighted object network, we propose a
recommendation algorithm, which is sensitive to the configuration of initial
resource distribution. Even under the simplest case with binary resource, the
current algorithm has remarkably higher accuracy than the widely applied global
ranking method and collaborative filtering. Furthermore, we introduce a free
parameter $\beta$ to regulate the initial configuration of resource. The
numerical results indicate that decreasing the initial resource located on
popular objects can further improve the algorithmic accuracy. More
significantly, we argue that a better algorithm should simultaneously have
higher accuracy and be more personal. According to a newly proposed measure
about the degree of personalization, we demonstrate that a degree-dependent
initial configuration can outperform the uniform case for both accuracy and
personalization strength.


title:
A singular stochastic differential equation driven by fractional
  Brownian motion

abstract:
  In this paper we study a singular stochastic differential equation driven by
an additive fractional Brownian motion with Hurst parameter $H>\frac 12$. Under
some assumptions on the drift, we show that there is a unique solution, which
has moments of all orders. We also apply the techniques of Malliavin calculus
to prove that the solution has an absolutely continuous law at any time $t>0$.


title: Finding Planets Around White Dwarf Remnants of Massive Stars

abstract:
  Planet frequency shows a strong positive correlation with host mass from the
hydrogen-burning limit to M ~ 2Msun. No search has yet been conducted for
planets of higher-mass hosts because all existing techniques are insensitive to
these planets. We show that infrared observations of the white-dwarf (WD)
remnants of massive stars 3Msun < M < 7Msun would be sensitive to these planets
for reasons that are closely connected to the insensitivity of other methods.
We identify 49 reasonably bright, young, massive WDs from the Palomar-Green
survey and discuss methods for detecting planets and for distinguishing between
planet and disk explanations for any excess flux observed. The young, bright,
massive WD sample could be expanded by a factor 4-5 by surveying the remainder
of the sky for bright UV-excess objects.


title: Shrinkage Estimation of the Power Spectrum Covariance Matrix

abstract:
  We seek to improve estimates of the power spectrum covariance matrix from a
limited number of simulations by employing a novel statistical technique known
as shrinkage estimation. The shrinkage technique optimally combines an
empirical estimate of the covariance with a model (the target) to minimize the
total mean squared error compared to the true underlying covariance. We test
this technique on N-body simulations and evaluate its performance by estimating
cosmological parameters. Using a simple diagonal target, we show that the
shrinkage estimator significantly outperforms both the empirical covariance and
the target individually when using a small number of simulations. We find that
reducing noise in the covariance estimate is essential for properly estimating
the values of cosmological parameters as well as their confidence intervals. We
extend our method to the jackknife covariance estimator and again find
significant improvement, though simulations give better results. Even for
thousands of simulations we still find evidence that our method improves
estimation of the covariance matrix. Because our method is simple, requires
negligible additional numerical effort, and produces superior results, we
always advocate shrinkage estimation for the covariance of the power spectrum
and other large-scale structure measurements when purely theoretical modeling
of the covariance is insufficient.


title: Dusty disks at the bottom of the IMF

abstract:
  'Isolated planetary mass objects' (IPMOs) have masses close to or below the
Deuterium-burning mass limit (~15 Jupiter masses) -- at the bottom of the
stellar initial mass function. We present an exploratory survey for disks in
this mass regime, based on a dedicated observing campaign with the Spitzer
Space Telescope. Our targets include the full sample of spectroscopically
confirmed IPMOs in the Sigma Orionis cluster, a total of 18 sources. In the
mass range 8... 20 MJup, we identify 4 objects with >3sigma colour excess at a
wavelength of 8.0mu, interpreted as emission from dusty disks. We thus
establish that a substantial fraction of IPMOs harbour disks with lifetimes of
at least 2-4 Myr (the likely age of the cluster), indicating an origin from
core collapse and fragmentation processes. The disk frequency in the IPMO
sample is 29% (16-45%) at 8.0mu, very similar to what has been found for stars
and brown dwarfs (~30%). The object SOri70, a candidate 3 MJup object in this
cluster, shows IRAC colours in excess of the typical values for field T dwarfs
(on a 2sigma level), possibly due to disk emission or low gravity. This is a
new indication for youth and thus an extremely low mass for SOri70.


title: Dynamics of Non-renormalizable Electroweak Symmetry Breaking

abstract:
  We compute the complete one-loop finite temperature effective potential for
electroweak symmetry breaking in the Standard Model with a Higgs potential
supplemented by higher dimensional operators as generated for instance in
composite Higgs and Little Higgs models. We detail the resolution of several
issues that arise, such as the cancellation of infrared divergences at higher
order and imaginary contributions to the potential. We follow the dynamics of
the phase transition, including the nucleation of bubbles and the effects of
supercooling. We characterize the region of parameter space consistent with a
strong first-order phase transition which may be relevant to electroweak
baryogenesis. Finally, we investigate the prospects of present and future
gravity wave detectors to see the effects of a strong first-order electroweak
phase transition.


title: Inflationary Constraints on Type IIA String Theory

abstract:
  We prove that inflation is forbidden in the most well understood class of
semi-realistic type IIA string compactifications: Calabi-Yau compactifications
with only standard NS-NS 3-form flux, R-R fluxes, D6-branes and O6-planes at
large volume and small string coupling. With these ingredients, the first
slow-roll parameter satisfies epsilon >= 27/13 whenever V > 0, ruling out both
inflation (including brane/anti-brane inflation) and de Sitter vacua in this
limit. Our proof is based on the dependence of the 4-dimensional potential on
the volume and dilaton moduli in the presence of fluxes and branes. We also
describe broader classes of IIA models which may include cosmologies with
inflation and/or de Sitter vacua. The inclusion of extra ingredients, such as
NS 5-branes and geometric or non-geometric NS-NS fluxes, evades the assumptions
used in deriving the no-go theorem. We focus on NS 5-branes and outline how
such ingredients may prove fruitful for cosmology, but we do not provide an
explicit model. We contrast the results of our IIA analysis with the rather
different situation in IIB.


title:
Large Scale Structure Formation of Normal Branch in DGP Brane World
  Model

abstract:
  In this paper, we study the large scale structure formation of the normal
branch in DGP model (Dvail, Gabadadze and Porrati brane world model) by
applying the scaling method developed by Sawicki, Song and Hu for solving the
coupled perturbed equations of motion of on-brane and off-brane. There is
detectable departure of perturbed gravitational potential from LCDM even at the
minimal deviation of the effective equation of state w_eff below -1. The
modified perturbed gravitational potential weakens the integrated Sachs-Wolfe
effect which is strengthened in the self-accelerating branch DGP model.
Additionally, we discuss the validity of the scaling solution in the de Sitter
limit at late times.


title: The Entropy Function for the Black Holes of Nariai Class

abstract:
  Based on the fact that the near horizon geometry of the extremal
Schwarzschild-de Sitter black holes is Nariai geometry, we define the black
holes of Nariai class as the configuration whose near-horizon geometry is
factorized as two dimensional de Sitter space-time and some compact topology,
that is Nariai geometry. We extend the entropy function formalism to the case
of the black holes of Nariai class. The conventional entropy function (for the
extremal black holes) is defined as Legendre transformation of Lagrangian
density, thus the `Routhian density', over two dimensional anti-de Sitter. As
for the black holes of Nariai class, it is defined as {\em minus} `Routhian
density' over two dimensional de Sitter space-time. We found an exact agreement
of the result with Bekenstein-Hawking entropy. The higher order corrections are
nontrivial only when the space-time dimension is over four, that is, $d>4$.
There is a subtlety as regards the temperature of the black holes of Nariai
class. We show that in order to be consistent with the near horizon geometry,
the temperature should be non-vanishing despite the extremality of the black
holes.


title:
Light-Cone Distortion of the Clustering and Abundance of Massive
  Galaxies at High-Redshifts

abstract:
  Observational surveys of galaxies are not trivially related to single-epoch
snapshots from computer simulations. Observationally, an increase in the
distance along the line-of-sight corresponds to an earlier cosmic time at which
the properties of the surveyed galaxy population may change. The effect of
observing a survey volume along the light-cone must be considered in the regime
where the mass function of galaxies varies exponentially with redshift. This
occurs when the halos under consideration are rare, that is either when they
are very massive or observed at high-redshift. While the effect of the
light-cone is negligible for narrow-band surveys of Lyman-alpha emitters, it
can be significant for drop-out surveys of Lyman-break galaxies (LBGs) where
the selection functions of the photometric bands are broad. Since there are
exponentially more halos at the low-redshift end of the survey, the
low-redshift tail of the selection function contains a disproportionate
fraction of the galaxies observed in the survey. This leads to a redshift
probability distribution (RPD) for the dropout LBGs with a mean less than that
of the photometric selection function (PHSF) by an amount of order the standard
deviation of the PHSF. The inferred mass function of galaxies is then shallower
than the true mass function at a single redshift with the abundance at the
high-mass end being twice or more as large as expected. Moreover, the
statistical moments of the count of galaxies calculated ignoring the light-cone
effect, deviate from the actual values.


title: Unitarity Bounds for New Physics from Axial Coupling at LHC

abstract:
  If a new massive vector boson with nonzero axial couplings to fermions will
be observed at LHC, then an upper limit on the scale of new physics could be
derived from unitarity of $\mathcal{S}$-matrix. The new physics will involve
either new massive fermions, or scalars, or even a strongly coupled sector. We
derive a model independent bound on the scale of new physics. If $M_{G}/ g_{A}
< 3$ TeV and the fermion is a top quark, the upper limit is 78 TeV.


title: Deep-Survey Constraints on X-ray Outbursts from Galactic Nuclei

abstract:
  Luminous X-ray outbursts with variability amplitudes as high as ~1000 have
been detected from a small number of galactic nuclei. These events are likely
associated with transient fueling of nuclear supermassive black holes. In this
paper, we constrain X-ray outbursts with harder spectra, higher redshifts, and
lower luminosities than have been studied previously. We performed a systematic
survey of 24668 optical galaxies in the Chandra Deep Fields to search for such
X-ray outbursts; the median redshift of these galaxies is ~0.8. The survey
spans 798 days for the Chandra Deep Field-North, and 1828 days for the Chandra
Deep Field-South. No outbursts were found, and thus we set upper limits on the
rate of such events in the Universe, which depend upon the adopted outburst
X-ray luminosity. For an outburst with X-ray luminosity $\ga 10^{43}$ ergs/s
and a duration of 6 months, the upper limit on its event rate is ~10^{-4}
/galaxy/yr, roughly consistent with theoretical predictions. Compared to
previous survey results, our harder-band and deeper survey suggests that the
outburst rate may increase by a maximum factor of 10 when considering both
obscured X-ray outbursts and redshift evolution from z~0 to z~0.8. Our results
also suggest that the X-ray luminosity function for moderate-luminosity active
galactic nuclei is not primarily due to stellar tidal disruptions.


title: The spectrum of large powers of the Laplacian in bounded domains

abstract:
  We present exact results for the spectrum of the Nth power of the Laplacian
in a bounded domain. We begin with the one dimensional case and show that the
whole spectrum can be obtained in the limit of large N. We also show that it is
a useful numerical approach valid for any N. Finally, we discuss implications
of this work and present its possible extensions for non integer N and for 3D
Laplacian problems.

categories: cond-mat.stat-mech cond-mat.dis-nn cond-mat.other cond-mat.soft math-ph math.MP nlin.SI


title: Spontaneous Lorentz Violation and Baryogenesis

abstract:
  In the presence of background fields that spontaneously violate Lorentz
invariance, a matter-antimatter asymmetry can be generated even in thermal
equilibrium. In this paper we systematically investigate models of this type,
showing that either high-energy or electroweak versions of baryogenesis are
possible, depending on the dynamics of the Lorentz-violating fields. We
identify two scenarios of interest: baryogenesis from a weak-scale
pseudo-Nambu-Goldstone boson with intermediate-scale baryon-number violation,
and sphaleron-induced baryogenesis driven by a constant-magnitude vector with a
late-time phase transition.


title: Mixed membership analysis of genome-wide expression data

abstract:
  Learning latent expression themes that best express complex patterns in a
sample is a central problem in data mining and scientific research. For
example, in computational biology we seek a set of salient gene expression
themes that explain a biological process, extracting them from a large pool of
gene expression profiles. In this paper, we introduce probabilistic models to
learn such latent themes in an unsupervised fashion. Our models capture
contagion, i.e., dependence among multiple occurrences of the same feature,
using a hierarchical Bayesian scheme. Contagion is a convenient analytical
formalism to characterize semantic themes underlying observed feature patterns,
such as biological context. We present model variants tailored to different
properties of biological data, and we outline a general variational inference
scheme for approximate posterior inference. We validate our methods on both
simulated data and realistic high-throughput gene expression profiles via SAGE.
Our results show improved predictions of gene functions over existing methods
based on stronger independence assumptions, and demonstrate feasibility of a
promising hierarchical Bayesian formalism for soft clustering and latent
aspects analysis.


title:
Resumming Cosmological Perturbations via the Lagrangian Picture:
  One-loop Results in Real Space and in Redshift Space

abstract:
  We develop a new approach to study the nonlinear evolution in the large-scale
structure of the Universe both in real space and in redshift space, extending
the standard perturbation theory of gravitational instability. Infinite series
of terms in standard Eulerian perturbation theory are resummed as a result of
our starting from a Lagrangian description of perturbations. Delicate nonlinear
effects on scales of the baryon acoustic oscillations are more accurately
described by our method than the standard one. Our approach differs from other
resummation techniques recently proposed, such as the renormalized perturbation
theory, etc., in that we use simple techniques and thus resulting equations are
undemanding to evaluate, and in that our approach is capable of quantifying the
nonlinear effects in redshift space. The power spectrum and correlation
function of our approach are in good agreement with numerical simulations in
literature on scales of baryon acoustic oscillations. Especially, nonlinear
effects on the baryon acoustic peak of the correlation function are accurately
described both in real space and in redshift space. Our approach provides a
unique opportunity to analytically investigate the nonlinear effects on baryon
acoustic scales in observable redshift space, which is requisite in
constraining the nature of dark energy, the curvature of the Universe, etc., by
redshift surveys.


title:
On Iwahori--Hecke algebras with unequal parameters and Lusztig's
  isomorphism theorem

abstract:
  By Tits' deformation argument, a generic Iwahori--Hecke algebra $H$
associated to a finite Coxeter group $W$ is abstractly isomorphic to the group
algebra of $W$. Lusztig has shown how one can construct an explicit
isomorphism, provided that the Kazhdan--Lusztig basis of $H$ satisfies certain
deep properties. If $W$ is crystallographic and $H$ is a one-parameter algebra,
then these properties are known to hold thanks to a geometric interpretation.
In this paper, we develop some new general methods for verifying these
properties, and we do verify them for two-parameter algebras of type $I_2(m)$
and $F_4$ (where no geometric interpretation is available in general). Combined
with previous work by Alvis, Bonnaf\'e, DuCloux, Iancu and the author, we can
then extend Lusztig's construction of an explicit isomorphism to all types of
$W$, without any restriction on the parameters of $H$.


title:
Imaging the interface of epitaxial graphene with silicon carbide via
  scanning tunneling microscopy

abstract:
  Graphene grown epitaxially on SiC has been proposed as a material for
carbon-based electronics. Understanding the interface between graphene and the
SiC substrate will be important for future applications. We report the ability
to image the interface structure beneath single-layer graphene using scanning
tunneling microscopy. Such imaging is possible because the graphene appears
transparent at energies of 1 eV above or below the Fermi energy. Our analysis
of calculations based on density functional theory shows how this transparency
arises from the electronic structure of a graphene layer on a SiC substrate.


title: Finite-temperature lineshapes in gapped quantum spin chains

abstract:
  We consider the finite-temperature dynamical structure factor (DSF) of gapped
quantum spin chains such as the spin one Heisenberg model and the transverse
field Ising model in the disordered phase. At zero temperature the DSF in these
models is dominated by a delta-function line arising from the coherent
propagation of single particle modes. Using methods of integrable quantum field
theory we determine the evolution of the lineshape at low temperatures. We show
that the line shape is in general asymmetric in energy and becomes Lorentzian
only at temperatures far below the gap. We discuss the relevance of our results
for the analysis of inelastic neutron scattering experiments on gapped spin
chain systems such as CsNiCl_3 and YBaNiO_5.


title:
Thermodynamic behavior of short oligonucleotides in microarray
  hybridizations can be described using Gibbs free energy in a nearest-neighbor
  model

abstract:
  While designing oligonucleotide-based microarrays, cross-hybridization
between surface-bound oligos and non-intended labeled targets is probably the
most difficult parameter to predict. Although literature describes
rules-of-thumb concerning oligo length, overall similarity, and continuous
stretches, the final behavior is difficult to predict. The aim of this study
was to investigate the effect of well-defined mismatches on hybridization
specificity using CodeLink Activated Slides, and to study quantitatively the
relation between hybridization intensity and Gibbs free energy (Delta G),
taking the mismatches into account. Our data clearly showed a correlation
between the hybridization intensity and Delta G of the oligos over three orders
of magnitude for the hybridization intensity, which could be described by the
Langmuir model. As Delta G was calculated according to the nearest-neighbor
model, using values related to DNA hybridizations in solution, this study
clearly shows that target-probe hybridizations on microarrays with a
three-dimensional coating are in quantitative agreement with the corresponding
reaction in solution. These results can be interesting for some practical
applications. The correlation between intensity and Delta G can be used in
quality control of microarray hybridizations by designing probes and
corresponding RNA spikes with a range of Delta G values. Furthermore, this
correlation might be of use to fine-tune oligonucleotide design algorithms in a
way to improve the prediction of the influence of mismatching targets on
microarray hybridizations.


title: Complexity of spectral sequences: semiclassical approach

abstract:
  It has been long recognized that the task of semiclassical evaluation of
quantum spectra for the classically nonintegrable systems is fundamentally more
complex than for the classically integrable ones. Below it is argued that the
quantum spectra of the chaotic systems can differ among themselves by level of
their complexity.


title: Remarks on topological algebras

abstract: The note complements topological aspects of the theory of chiral algebras.


title: Production of Neutrinos and Secondary Electrons in Cosmic Sources

abstract:
  We study the individual contribution to secondary lepton production in
hadronic interactions of cosmic rays (CRs) including resonances and heavier
secondaries. For this purpose we use the same ethodology discussed earlier
\cite{Huang07}, namely the Monte Carlo particle collision code DPMJET3.04 to
determine the multiplicity spectra of various secondary particles with leptons
as the final decay states, that result from inelastic collisions of cosmic-ray
protons and Helium nuclei with the interstellar medium of standard composition.
By combining the simulation results with parametric models for secondary
particle (with resonances included) for incident cosmic-ray energies below a
few GeV, where DPMJET appears unreliable, we thus derive production matrices
for all stable secondary particles in cosmic-ray interactions with energies up
to about 10 PeV. We apply the production matrices to calculate the radio
synchrotron radiation of secondary electrons in a young shell-type SNR, RX
J1713.7-3946, which is a measure of the age, the spectral index of hadronic
cosmic rays, and most importantly the magnetic field strength. We find that the
multi-mG fields recently invoked to explain the X-ray flux variations are
unlikely to extend over a large fraction of the radio-emitting region,
otherwise the spectrum of hadronic cosmic rays in the energy window 0.1-100 GeV
must be unusually hard. We also use the production matrices to calculate the
muon event rate in an IceCube-like detector that are induced by muon neutrinos
from high-energy $\gamma$-ray sources such as RX J1713.7-3946, Vela Jr. and
MGRO J2019+37. At muon energies of a few TeV, or in other word, about 10 TeV
neutrino energy, an accumulation of data over about five to ten years would
allow testing the hadronic origin of TeV $\gamma$-rays.


title: The Effect of Large-Scale Power on Simulated Spectra of the Lya forest

abstract:
  We study the effects of box size on ENZO simulations of the intergalactic
medium (IGM) at z = 2. We follow statistics of the cold dark matter (CDM) and
the Lya absorption. We find that the larger boxes have fewer pixels with
significant absorption (flux < 0.96) and more pixels in longer stretches with
little or no absorption, and they have wider Lya lines. We trace these effect
back to the additional power in larger boxes from longer wavelength modes. The
IGM in our larger boxes is hotter, from increased pressure heating due to
faster hydrodynamical infall. When we increase the photoheating in smaller
boxes to compensate, their Lya statistics change to mimic those of a box of
twice the size. Statistics converge towards their value in the largest (76.8
Mpc) box, except for the most common value of the CDM density which continues
to rise. When we compare to errors with data, we find that our 76.8 Mpc box is
larger than we need for the mean flux, barely large enough for the column
density distribution and the power spectrum of the flux, and too small for the
line widths. This box with 75 kpc cells has approximately the same mean flux as
QSO spectra, but the Lya lines are too wide by 2.6 km/s, there are too few
lines with log H I column densities > 10^17 cm^-2, and the power of the flux is
too low by 20 - 50%, from small to large scales. Four times smaller cell size
does not resolve these differences, nor do simple changes to the ultraviolet
background that drives the H and He II ionization. It is hard to see how
simulations using popular cosmological and astrophysical parameters can match
Lyman-alpha forest data at z=2.


title:
Beta Cephei stars in the ASAS-3 data. II. 103 new Beta Cephei stars and
  a discussion of low-frequency modes

abstract:
  We analysed ASAS-3 photometry of bright early-type stars with the goal of
finding new Beta Cephei stars. We were particularly interested in stars that
would be good for seismic analysis, i.e., stars that (i) have a large number of
excited modes, (ii) show rotationally split modes, (iii) are components of
eclipsing binary systems, (iv) have low-frequency modes, that is, are hybrid
Beta Cephei/SPB stars. Our study was made with a homogeneous sample of over
4100 stars having MK spectral type B5 or earlier. For these stars, the ASAS-3
photometry was analysed by means of a Fourier periodogram. We have discovered
103 Beta Cephei stars, nearly doubling the number of previously known stars of
this type. Among these stars, four are components of eclipsing binaries, seven
have modes equidistant or nearly equidistant in frequency. In addition, we
found five Beta Cephei stars that show low-frequency periodic variations, very
likely due to pulsations. We therefore regard them as candidate hybrid Beta
Cephei/SPB pulsators. All these stars are potentially very useful for seismic
modeling. Moreover, we found Beta Cephei-type pulsations in three late O-type
stars and fast period changes in one, HD 168050.


title:
Multimodal pattern formation in phenotype distributions of sexual
  populations

abstract:
  During bouts of evolutionary diversification, such as adaptive radiations,
the emerging species cluster around different locations in phenotype space, How
such multimodal patterns in phenotype space can emerge from a single ancestral
species is a fundamental question in biology. Frequency-dependent competition
is one potential mechanism for such pattern formation, as has previously been
shown in models based on the theory of adaptive dynamics. Here we demonstrate
that also in models similar to those used in quantitative genetics, phenotype
distributions can split into multiple modes under the force of
frequency-dependent competition. In sexual populations, this requires
assortative mating, and we show that the multimodal splitting of initially
unimodal distributions occurs over a range of assortment parameters. In
addition, assortative mating can be favoured evolutionarily even if it incurs
costs, because it provides a means of alleviating the effects of frequency
dependence. Our results reveal that models at both ends of the spectrum between
essentially monomorphic (adaptive dynamics) and fully polymorphic (quantitative
genetics) yield similar results. This underscores that frequency-dependent
selection is a strong agent of pattern formation in phenotype distributions,
potentially resulting in adaptive speciation.


title: Hecke duality relations of Jacobi forms

abstract:
  In this paper we introduce a new subspace of Jacobi forms of higher degree
via certain relations among Fourier coefficients. We prove that this space can
also be characterized by duality properties of certain distinguished embedded
Hecke operators. We then show that this space is Hecke invariant with respect
to all good Hecke operators.
  As explicit examples we give Eisenstein series.
  Conversely we show the existence of forms that are not contained in this
space.


title: Splitting formulas for certain Waldhausen Nil-groups

abstract:
  For a group G that splits as an amalgamation of A and B over a common
subgroup C, there is an associated Waldhausen Nil-group, measuring the
"failure" of Mayer-Vietoris for algebraic K-theory. Assume that (1) the
amalgamation is acylindrical, and (2) the groups A,B,G satisfy the
Farrell-Jones isomorphism conjecture. Then we show that the Waldhausen
Nil-group splits as a direct sum of Nil-groups associated to certain
(explicitly describable) infinite virtually cyclic subgroups of G. We note that
a special case of an acylindrical amalgamation includes any amalgamation over a
finite group C.


title: SQCD Vacua and Geometrical Engineering

abstract:
  We consider the geometrical engineering constructions for the N = 1 SQCD
vacua recently proposed by Giveon and Kutasov. After one T-duality, the
geometries with wrapped D5 branes become N = 1 brane configurations with NS
branes and D4 branes. The field theories encoded by the geometries contain
extra massive adjoint fields for the flavor group. After performing a flop, the
geometries contain branes, antibranes and branes wrapped on non-holomorphic
cycles. The various tachyon condensations between pairs of wrapped D5 branes
and anti D5 branes together with deformations of the cycles give rise to a
variety of supersymmetric and metastable non-supersymmetric vacua.


title: Limits on the Detection of Transients Imposed by Scattering

abstract:
  The author has recognized an error in the section of the text regarding
induced Compton scattering. The paper has been withdrawn pending a revision to
this section.


title:
The Efficiency of Grain Alignment in Dense Interstellar Clouds: A
  Reassessment of Constraints from Near Infrared Polarization

abstract:
  A detailed study of interstellar polarization efficiency toward molecular
clouds is used to attempt discrimination between grain alignment mechanisms in
dense regions of the ISM. Background field stars are used to probe polarization
efficiency in quiescent regions of dark clouds, yielding a dependence on visual
extinction well-represented by a power law. No significant change in this
behavior is observed in the transition region between the diffuse outer layers
and dense inner regions of clouds, where icy mantles are formed, and we
conclude that mantle formation has little or no effect on the efficiency of
grain alignment. Young stellar objects generally exhibit greater polarization
efficiency compared with field stars at comparable extinctions, displaying
enhancements by factors of up to 6. Of the proposed alignment mechanisms, that
based on radiative torques appears best able to explain the data. The
attenuated external radiation field accounts for the observed polarization in
quiescent regions, and radiation from the embedded stars themselves may enhance
alignment in the lines of sight to YSOs. Enhancements in polarization
efficiency observed in the ice features toward several YSOs are of greatest
significance, as they demonstrate efficient alignment in cold molecular clouds
associated with star formation.


title:
Effects of galaxy-halo alignment and adiabatic contraction on
  gravitational lens statistics

abstract:
  We study the strong gravitational lens statistics of triaxial cold dark
matter (CDM) halos occupied by central early-type galaxies. We calculate the
image separation distribution for double, cusp and quad configurations. The
ratios of image multiplicities at large separations are consistent with the
triaxial NFW model, and at small separations are consistent with the singular
isothermal ellipsoid (SIE) model. At all separations, the total lensing
probability is enhanced by adiabatic contraction. If no adiabatic contraction
is assumed, naked cusp configurations become dominant at approximately 2.5'',
which is inconsistent with the data. We also show that at small-to-moderate
separations, the image multiplicities depend sensitively on the alignment of
the shapes of the luminous and dark matter projected density profiles. In
constrast to other properties that affect these ratios, the degree of alignment
does not have a significant effect on the total lensing probability. These
correlations may therefore be constrained by comparing the theoretical image
separation distribution to a sufficiently large lens sample from future wide
and deep sky surveys such as Pan-Starrs, LSST and JDEM. Understanding the
correlations in the shapes of galaxies and their dark matter halo is important
for future weak lensing surveys.


title: Diffusion limited reactions in confined environments

abstract:
  We study the effect of confinement on diffusion limited bimolecular reactions
within a lattice model where a small number of reactants diffuse amongst a much
larger number of inert particles. When the number of inert particles is held
constant the rate of the reaction is slow for small reaction volumes due to
limited mobility from crowding, and for large reaction volumes due to the
reduced concentration of the reactants. The reaction rate proceeds fastest at
an intermediate confinement corresponding to volume fraction near 1/2 and 1/3
in two and three dimensions, respectively. We generalize the model to
off-lattice systems with hydrodynamic coupling and predict that the optimal
reaction rate for monodisperse colloidal systems occurs when the volume
fraction is ~0.18. Finally, we discuss the application of our model to
bimolecular reactions inside cells as well as the dynamics of confined
polymers.


title:
First-principles study of the lattice and electronic structures of
  TbMn$_2$O$_5$

abstract:
  The structural, electronic and lattice dielectric properties of multiferroic
TbMn$_2$O$_5$ are investigated using density functional theory within the
generalized gradient approximation (GGA). We use collinear spin approximations
and ignore the spin-orbit coupling. The calculated structural parameters are in
excellent agreement with the experiments. We confirm that the ground state
structure of TbMn$_2$O$_5$ is of space group $Pb2_1m$, allowing polarizations
along the b-axis. The spontaneous electric polarization is calculated to be
1187 $nC\cdot$cm$^{-2}$. The calculated zone-center optical phonons frequencies
and the oscillator strengths of IR phonons agree very well with the
experimental values. We then derive an effective Hamiltonian to explain the
magnetically-induced ferroelectricity in this compound. Our results strongly
suggest that the ferroelectricity in TbMn$_2$O$_5$ is driven by the magnetic
ordering that breaks the the inversion symmetry, without invoking the
spin-orbit coupling.


title: Open clusters: their kinematics and metellicities

abstract:
  We review our work on Galactic open clusters in recent years, and introduce
our proposed large program for the LOCS (LAMOST Open Cluster Survey). First,
based on the most complete open clusters sample with metallicity, age and
distance data as well as kinematic information, some preliminary statistical
analysis regarding the spatial and metallicity distributions is presented. In
particular, a radial abundance gradient of - 0.058$\pm$ 0.006 dex kpc$^{-1}$
was derived, and by dividing clusters into age groups we show that the disk
abundance gradient was steeper in the past. Secondly, proper motions,
membership probabilities, and velocity dispersions of stars in the regions of
two very young open clusters are derived. Both clusters show clear evidence of
mass segregation, which provides support for the ``primordial'' mass
segregation scenarios. Based on the great advantages of the forthcoming LAMOST
facility, we have proposed a detailed open cluster survey with LAMOST (the
LOCS). The aim, feasibility, and the present development of the LOCS are
briefly summarized.


title:
Schubert calculus and cohomology of Lie groups. Part I. 1-connected Lie
  groups

abstract:
  Let $G$ be a compact and $1$--connected Lie group with a maximal torus $T$.
Based on Schubert calculus on the flag manifold $G/T$ [15] we construct the
integral cohomology ring $H^{\ast}(G)$ uniformly for all $G$.


title: Abelian-Higgs Phase of SU(2) QCD and Glueball Energy

abstract:
  It is shown that SU(2) QCD admits an dual Abelian-Higgs phase, with a Higgs
vacuum type of type-II superconductor. This is done by using connection
decomposition for the gluon field and the random-direction approximation. Using
bag picture with soft wall, we presented a calculational procedure for glueball
energy based on the recent proof for wall-vortices [Nucl. Phys. B 741(2006)1].


title: A Canonical Analysis of the First Order Einstein-Hilbert Action

abstract:
  The Dirac constraint formalism is applied to the d(d>2) dimensional
Einstein-Hilbert action when written in first order form, using the metric
density and affine connection as independent fields. Field equations not
involving time derivatives are not used to eliminate fields. Primary, secondary
and tertiary constraints arise, leaving d(d-3) degrees of freedom in phase
space. The Poisson Bracket algebra of these constraints is given.


title: Perturbation Theory

abstract: A review article on perturbation theory


title:
A spectral collocation approximation for the radial-infall of a compact
  object into a Schwarzschild black hole

abstract:
  The inhomogeneous Zerilli equation is solved in time-domain numerically with
the Chebyshev spectral collocation method to investigate a radial-infall of the
point particle towards a Schwarzschild black hole. Singular source terms due to
the point particle appear in the equation in the form of the Dirac
$\delta$-function and its derivative. For the approximation of singular source
terms, we use the direct derivative projection method without any
regularization. The gravitational waveforms are evaluated as a function of
time. We compare the results of the spectral collocation method with those of
the explicit second-order central-difference method. The numerical results show
that the spectral collocation approximation with the direct projection method
is accurate and converges rapidly when compared with the finite-difference
method.


title: Normalization of IZF with Replacement

abstract:
  ZF is a well investigated impredicative constructive version of
Zermelo-Fraenkel set theory. Using set terms, we axiomatize IZF with
Replacement, which we call \izfr, along with its intensional counterpart
\iizfr. We define a typed lambda calculus $\li$ corresponding to proofs in
\iizfr according to the Curry-Howard isomorphism principle. Using realizability
for \iizfr, we show weak normalization of $\li$. We use normalization to prove
the disjunction, numerical existence and term existence properties. An inner
extensional model is used to show these properties, along with the set
existence property, for full, extensional \izfr.


title:
Interference Alignment on the Deterministic Channel and Application to
  Fully Connected AWGN Interference Networks

abstract:
  An interference alignment example is constructed for the deterministic
channel model of the $K$ user interference channel. The deterministic channel
example is then translated into the Gaussian setting, creating the first known
example of a fully connected Gaussian $K$ user interference network with single
antenna nodes, real, non-zero and contant channel coefficients, and no
propagation delays where the degrees of freedom outerbound is achieved. An
analogy is drawn between the propagation delay based interference alignment
examples and the deterministic channel model which also allows similar
constructions for the 2 user $X$ channel as well.


title:
Cosmic ray spectrum by energy scattered by EAS particles in the
  atmosphere and galactic model

abstract:
  The differential energy spectrum of cosmic rays from Cherenkov radiation
measurements in EAS in the energy range of 10^15-10^20eV has been compared with
an anomalous diffusion model for the particles in interstellar space having
fractal properties (Lagutin et al, 2001). The close association between
experimental data and calculated "all particle" spectra in form at E(0)
(10^15-10^18)eV is found. In this case, the average mass composition of cosmic
rays calculated by five components does not contradict the average mass
composition from experimental data which was obtained by several of EAS
characteristics in that energy region.


title:
General Connections, Exponential Maps, and Second-order Differential
  Equations

abstract:
  The main purpose of this article is to introduce a comprehensive, unified
theory of the geometry of all connections. We show that one can study a
connection via a certain, closely associated second-order differential
equation. One of the most important results is our extended
Ambrose-Palais-Singer correspondence. We extend the theory of geodesic sprays
to certain second-order differential equations, show that locally diffeomorphic
exponential maps can be defined for all, and give a full theory of (possibly
nonlinear) covariant derivatives for (possibly nonlinear) connections. In the
process, we introduce vertically homogeneous connections. Unlike homogeneous
connections, these complete our theory and allow us to include Finsler spaces
in a completely consistent manner.
  This is an expanded version of the article published in Differ. Geom. Dyn.
Syst. 13 (2011) 72--90. Included are the proof published in Nonlinear Anal. 63
(2005) e501--e510 (for the reader's convenience) and some new material on
homogeneity.


title:
Effective multifractal features and l-variability diagrams of
  high-frequency price fluctuations time series

abstract:
  In this manuscript we present a comprehensive study on the multifractal
properties of high-frequency price fluctuations and instantaneous volatility of
the equities that compose Dow Jones Industrial Average. The analysis consists
about quantification of dependence and non-Gaussianity on the multifractal
character of financial quantities. Our results point out an equivalent
influence of dependence and non-Gaussianity on the multifractality of time
series. Moreover, we analyse l-diagrams of price fluctuations. In the latter
case, we show that the fractal dimension of these maps is basically independent
of the lag between price fluctuations that we assume.


title: Coherent quantum LQG control

abstract:
  Based on a recently developed notion of physical realizability for quantum
linear stochastic systems, we formulate a quantum LQG optimal control problem
for quantum linear stochastic systems where the controller itself may also be a
quantum system and the plant output signal can be fully quantum. Such a control
scheme is often referred to in the quantum control literature as "coherent
feedback control.'' It distinguishes the present work from previous works on
the quantum LQG problem where measurement is performed on the plant and the
measurement signals are used as input to a fully classical controller with no
quantum degrees of freedom. The difference in our formulation is the presence
of additional non-linear and linear constraints on the coefficients of the
sought after controller, rendering the problem as a type of constrained
controller design problem. Due to the presence of these constraints our problem
is inherently computationally hard and this also distinguishes it in an
important way from the standard LQG problem. We propose a numerical procedure
for solving this problem based on an alternating projections algorithm and, as
initial demonstration of the feasibility of this approach, we provide fully
quantum controller design examples in which numerical solutions to the problem
were successfully obtained. For comparison, we also consider the case of
classical linear controllers that use direct or indirect measurements, and show
that there exists a fully quantum linear controller which offers an improvement
in performance over the classical ones.


title: Large-sphere and small-sphere limits of the Brown-York mass

abstract:
  In this paper, we will study the limiting behavior of the Brown-York mass of
the coordinate spheres in an asymptotically flat manifold. Limiting behaviors
of volumes of regions related to coordinate spheres are also obtained,
including a discussion on the isoperimetric mass introduced by Huisken
\cite{Huisken}. We will also study expansions of the Brown-York mass and the
Hawking mass of geodesic spheres with center at a fixed point $p$ of a three
manifold. Some geometric consequences will be derived.


title:
Hydrogen atom in a magnetic field: electromagnetic transitions of the
  lowest states

abstract:
  A detailed study of the lowest states $1s_0, 2p_{-1}, 2p_0$ of the hydrogen
atom placed in a magnetic field $B\in(0-4.414\times 10^{13} {\rm G})$ and their
electromagnetic transitions ($1s_{0} \leftrightarrow 2p_{-1}$ and $ 1s_{0}
\leftrightarrow 2p_{0}$) is carried out in the Born Oppenheimer approximation.
The variational method is used with a physically motivated recipe to design
simple trial functions applicable to the whole domain of magnetic fields. We
show that the proposed functions yield very accurate results for the ionization
(binding) energies. Dipole and oscillator strengths are in good agreement with
results by Ruder {\em et al.} \cite{Ruderbook} although we observe deviations
up to $\sim 30%$ for the oscillator strength of the (linearly polarized)
electromagnetic transition $1s_{0} \leftrightarrow 2p_{0}$ at strong magnetic
fields $B\gtrsim 1000$ a.u.


title:
On the estimation of the convergence rate in the Janashia-Lagvilava
  spectral factorization algorithm

abstract:
  In the present paper, we estimate the convergence rate in the
Janashia-Lagvilava spectral factorization algorithm (see Studia Mathematica,
137, 1999, 93-100) under the restriction on a spectral density matrix that its
inverse is integrable.


title: The Chains of Left-invariant CR-structures on SU(2)

abstract:
  We compute the chains associated to the left-invariant CR structures on the
three-sphere. These structures are characterized by a single real modulus $a$.
For the standard structure $a=1$, the chains are well-known and are closed
curves. We show that for almost all other values of the modulus $a$ either two
or three types of chains are simultaneously present : (I) closed curves, (II)
quasi-periodic curves dense on two-torii, or (III) chains homoclinic between
closed curves. For $1 < a < \sqrt{3}$ no curves of the last type occur.
  A bifurcation occurs at $a = \sqrt{3}$ and from that point on all three types
of chains are guaranteed to exist, and exhaust all chains. The method of proof
is to use the Fefferman metric characterization of chains, combined with tools
from geometric mechanics. The key to the computation is a reduced Hamiltonian
system, similar to Euler's rigid body system, and depending on $a$, which is
integrable.


title: Universal geometric entanglement close to quantum phase transitions

abstract:
  Under successive Renormalization Group transformations applied to a quantum
state $\ket{\Psi}$ of finite correlation length $\xi$, there is typically a
loss of entanglement after each iteration. How good it is then to replace
$\ket{\Psi}$ by a product state at every step of the process? In this paper we
give a quantitative answer to this question by providing first analytical and
general proofs that, for translationally invariant quantum systems in one
spatial dimension, the global geometric entanglement per region of size $L \gg
\xi$ diverges with the correlation length as $(c/12) \log{(\xi/\epsilon)}$
close to a quantum critical point with central charge $c$, where $\epsilon$ is
a cut-off at short distances. Moreover, the situation at criticality is also
discussed and an upper bound on the critical global geometric entanglement is
provided in terms of a logarithmic function of $L$.


title: Global NLO Analysis of Nuclear Parton Distribution Functions

abstract:
  Nuclear parton distribution functions (NPDFs) are determined by a global
analysis of experimental measurements on structure-function ratios
F_2^A/F_2^{A'} and Drell-Yan cross section ratios
\sigma_{DY}^A/\sigma_{DY}^{A'}, and their uncertainties are estimated by the
Hessian method. The NPDFs are obtained in both leading order (LO) and
next-to-leading order (NLO) of \alpha_s. As a result, valence-quark
distributions are relatively well determined, whereas antiquark distributions
at x>0.2 and gluon distributions in the whole x region have large
uncertainties. The NLO uncertainties are slightly smaller than the LO ones;
however, such a NLO improvement is not as significant as the nucleonic case.


title: Iterated dynamical maps in an ion trap

abstract:
  Iterated dynamical maps offer an ideal setting to investigate quantum
dynamical bifurcations and are well adapted to few-qubit quantum computer
realisations. We show that a single trapped ion, subject to periodic impulsive
forces, exhibits a rich structure of dynamical bifurcations derived from the
Jahn-Teller Hamiltonian flow model. We show that the entanglement between the
oscillator and electronic degrees of freedom reflects the underlying dynamical
bifurcation in a Floquet eigenstate.


title: Prediction and explanation in the multiverse

abstract:
  Probabilities in the multiverse can be calculated by assuming that we are
typical representatives in a given reference class. But is this class well
defined? What should be included in the ensemble in which we are supposed to be
typical? There is a widespread belief that this question is inherently vague,
and that there are various possible choices for the types of reference objects
which should be counted in. Here we argue that the ``ideal'' reference class
(for the purpose of making predictions) can be defined unambiguously in a
rather precise way, as the set of all observers with identical information
content. When the observers in a given class perform an experiment, the class
branches into subclasses who learn different information from the outcome of
that experiment. The probabilities for the different outcomes are defined as
the relative numbers of observers in each subclass. For practical purposes,
wider reference classes can be used, where we trace over all information which
is uncorrelated to the outcome of the experiment, or whose correlation with it
is beyond our current understanding. We argue that, once we have gathered all
practically available evidence, the optimal strategy for making predictions is
to consider ourselves typical in any reference class we belong to, unless we
have evidence to the contrary. In the latter case, the class must be
correspondingly narrowed.


title:
Warped String Compactification via Singular Calabi-Yau Conformal Field
  Theory

abstract:
  We construct spacetime supersymmetric, modular invariant partition functions
of strings on the conifold-type singularities which include contributions from
the discrete-series representations of SL(2, R). The discrete spectrum is
automatically consistent with the GSO projection in the continuous sector, and
contains massless matter fields localized on a four-dimensional submanifold at
the tip of a cigar. In particular, they are in the 27+1 of E6 for the E8 x E8
heterotic string. We speculate about a possible realization of local E6 GUT by
using this framework.


title: Starburst galaxies in cluster-feeding filaments unveiled by Spitzer

abstract:
  We report the first direct detection with Spitzer of galaxy filaments. Using
Spitzer and ancillary optical data, we have discovered two filamentary
structures in the outskirts of the cluster Abell 1763. Both filaments point
toward Abell 1770 which lies at the same redshift as Abell 1763 (z=0.23), at a
projected distance of ~13 Mpc. The X-ray cluster emission is elongated along
the same direction. Most of the far-infrared emission is powered by star
formation. According to the optical spectra, only one of the cluster members is
classified as an active galactic nucleus. Star formation is clearly enhanced in
galaxies along the filaments: the fraction of starburst galaxies in the
filaments is more than twice than that in other cluster regions. We speculate
that these filaments are feeding the cluster Abell 1763 by the infall of
galaxies and galaxy groups. Evidence for one of these groups is provided by the
analysis of galaxy kinematics in the central cluster region.


title: Algorithmic Arithmetic Fewnomial Theory I: One Variable

abstract:
  Withdrawn by the authors due to an error in the proof of the finite field
result (Thm. 1.5): The random primes used in the proof need NOT avoid the
exceptional primes from Lemma 2.7, thus leaving Thm. 1.5 unproved.


title: Cosmological perturbations in the DGP braneworld: numeric solution

abstract:
  We solve for the behaviour of cosmological perturbations in the
Dvali-Gabadadze-Porrati (DGP) braneworld model using a new numerical method.
Unlike some other approaches in the literature, our method uses no
approximations other than linear theory and is valid on large scales. We
examine the behaviour of late-universe density perturbations for both the
self-accelerating and normal branches of DGP cosmology. Our numerical results
can form the basis of a detailed comparison between the DGP model and
cosmological observations.


title:
Conditional independence relations and log-linear models for random
  permutations

abstract:
  We propose a new class of models for random permutations, which we call
log-linear models, by the analogy with log-linear models used in the analysis
of contingency tables. As a special case, we study the family of all
Luce-decomposable distributions, and the family of those random permutations,
for which the distribution of both the permutation and its inverse is
Luce-decomposable. We show that these latter models can be described by
conditional independence relations. We calculate the number of free parameters
in these models, and describe an iterative algorithm for maximum likelihood
estimation, which enables us to test if a set of data satisfies the conditional
independence relations or not.


title:
Correlation between Thermal Properties, Electrical Conductivity and
  Crystal Structure in the BaCe0.80Y0.20O2.9 Proton Conductor

abstract:
  In this paper we report an extensive neutron diffraction investigation at
high temperature on the BaCe0.80Y0.20O2.9 proton conducting material. Our
results precisely define the structural evolution of the compound as a function
of temperature which is from a monoclinic (room temperature) to a cubic (800C)
structure. Neutron data have been correlated to calorimetric measurements (TGA
and DSC) and conductivity properties of the material.


title: Resonances in Ps-H scattering

abstract:
  The best 3-channel projectile-inelastic [H(1s)+Ps(1s,2s,2p)] close-coupling
approximation (CCA) is performed for positronium (Ps) and hydrogen (H)
collision considering both the atoms in ground states at the incident channel.
The s-wave elastic phase shifts and cross sections in the singlet and triplet
channels and the total (or integrated) cross section are studied below
inelastic threshold. Resonances in singlet channel using 2-channel and
3-channel projectile-inelastic CCAs confirm earlier prediction [1]. A resonance
in triplet channel using 3-channel projectile-inelastic CCA is a new addition.


title: Fractional Derivative as Fractional Power of Derivative

abstract:
  Definitions of fractional derivatives as fractional powers of derivative
operators are suggested. The Taylor series and Fourier series are used to
define fractional power of self-adjoint derivative operator. The Fourier
integrals and Weyl quantization procedure are applied to derive the definition
of fractional derivative operator. Fractional generalization of concept of
stability is considered.


title:
Computational and qualitative aspects of motion of plane curves with a
  curvature adjusted tangential velocity

abstract:
  In this paper we investigate a time dependent family of plane closed Jordan
curves evolving in the normal direction with a velocity which is assumed to be
a function of the curvature, tangential angle and position vector of a curve.
We follow the direct approach and analyze the system of governing PDEs for
relevant geometric quantities. We focus on a class of the so-called curvature
adjusted tangential velocities for computation of the curvature driven flow of
plane closed curves. Such a curvature adjusted tangential velocity depends on
the modulus of the curvature and its curve average. Using the theory of
abstract parabolic equations we prove local existence, uniqueness and
continuation of classical solutions to the system of governing equations. We
furthermore analyze geometric flows for which normal velocity may depend on
global curve quantities like the length, enclosed area or total elastic energy
of a curve. We also propose a stable numerical approximation scheme based on
the flowing finite volume method. Several computational examples of various
nonlocal geometric flows are also presented in this paper.


title:
High-Velocity Estimates for the Scattering Operator and Aharonov-Bohm
  Effect in Three Dimensions

abstract:
  We obtain high-velocity estimates with error bounds for the scattering
operator of the Schr\"odinger equation in three dimensions with electromagnetic
potentials in the exterior of bounded obstacles that are handlebodies. A
particular case is a finite number of tori. We prove our results with
time-dependent methods. We consider high-velocity estimates where the direction
of the velocity of the incoming electrons is kept fixed as its absolute value
goes to infinity. In the case of one torus our results give a rigorous proof
that quantum mechanics predicts the interference patterns observed in the
fundamental experiments of Tonomura et al. that gave a conclusive evidence of
the existence of the Aharonov-Bohm effect using a toroidal magnet. We give a
method for the reconstruction of the flux of the magnetic field over a
cross-section of the torus modulo $2\pi$. Equivalently, we determine modulo
$2\pi$ the difference in phase for two electrons that travel to infinity, when
one goes inside the hole and the other outside it. For this purpose we only
need the high-velocity limit of the scattering operator for one direction of
the velocity of the incoming electrons. When there are several tori -or more
generally handlebodies- the information that we obtain in the fluxes, and on
the difference of phases, depends on the relative position of the tori and on
the direction of the velocities when we take the high-velocity limit of the
incoming electrons. For some locations of the tori we can determine all the
fluxes modulo 2$\pi$ by taking the high-velocity limit in only one direction.
We also give a method for the unique reconstruction of the electric potential
and the magnetic field outside the handlebodies from the high-velocity limit of
the scattering operator.


title: The Detection of a Light Echo from the Type Ia Supernova 2006X in M100

abstract:
  We report the discovery of a light echo (LE) from the Type Ia supernova (SN)
2006X in the nearby galaxy M100. The presence of the LE is supported by
analysis of both the Advanced Camera for Surveys (ACS) images taken with the
{\it Hubble Space Telescope (HST)} at $\sim$300 d after maximum brightness and
the Keck optical spectrum obtained at a similar phase. In the image procedure,
both the radial-profile analysis and the point-spread-function (PSF)
subtraction method resolve significant excess emission at 2--5 ACS pixels
($\sim0.05''-0.13''$) from the center. In particular, the PSF-subtracted ACS
images distinctly appear to have an extended, ring-like echo. Due to
limitations of the image resolution, we cannot confirm any structure or flux
within 2 ACS pixels from the SN. The late-time spectrum of SN 2006X can be
reasonably fit with two components: a nebular spectrum of a normal SN Ia and a
synthetic LE spectrum. Both image and spectral analysis show a rather blue
color for the emission of the LE, suggestive of a small average grain size for
the scattering dust. Using the Cepheid distance to M100 of 15.2 Mpc, we find
that the dust illuminated by the resolved LE is $\sim$27--170 pc from the SN.
The echo inferred from the nebular spectrum appears to be more luminous than
that resolved in the images (at the $\sim2\sigma$ level), perhaps suggesting
the presence of an inner echo at $<$2 ACS pixels ($\sim0.05''$). It is not
clear, however, whether this possible local echo was produced by a distinct
dust component (i.e., the local circumstellar dust) or by a continuous, larger
distribution of dust as with the outer component. Nevertheless, our detection
of a significant echo in SN 2006X confirms that this supernova was produced in
a dusty environment having unusual dust properties.


title: On the Ramsey numbers for a combination of paths and Jahangirs

abstract:
  For given graphs $G$ and $H,$ the \emph{Ramsey number} $R(G,H)$ is the least
natural number $n$ such that for every graph $F$ of order $n$ the following
condition holds: either $F$ contains $G$ or the complement of $F$ contains $H.$
In this paper, we improve the Surahmat and Tomescu's result \cite{ST:06} on the
Ramsey number of paths versus Jahangirs. We also determine the Ramsey number
$R(\cup G,H)$, where $G$ is a path and $H$ is a Jahangir graph.


title: Constraining the neutron star equation of state using XMM-Newton

abstract:
  We have identified three possible ways in which future XMM-Newton
observations can provide significant constraints on the equation of state of
neutron stars. First, using a long observation of the neutron star X-ray
transient CenX-4 in quiescence one can use the RGS spectrum to constrain the
interstellar extinction to the source. This removes this parameter from the
X-ray spectral fitting of the pn and MOS spectra and allows us to investigate
whether the variability observed in the quiescent X-ray spectrum of this source
is due to variations in the soft thermal spectral component or variations in
the power law spectral component coupled with variations in N_H. This will test
whether the soft thermal spectral component can indeed be due to the hot
thermal glow of the neutron star. Potentially such an observation could also
reveal redshifted spectral lines from the neutron star surface. Second,
XMM-Newton observations of radius expansion type I X-ray bursts might reveal
redshifted absorption lines from the surface of the neutron star. Third,
XMM-Newton observations of eclipsing quiescent low-mass X-ray binaries provide
the eclipse duration. With this the system inclination can be determined
accurately. The inclination determined from the X-ray eclipse duration in
quiescence, the rotational velocity of the companion star and the
semi-amplitude of the radial velocity curve determined through optical
spectroscopy, yield the neutron star mass.


title: Spinning particles in scalar-tensor gravity

abstract:
  We develop a new model of a spinning particle in Brans-Dicke spacetime using
a metric-compatible connection with torsion. The particle's spin vector is
shown to be Fermi-parallel (by the Levi-Civita connection) along its worldline
(an autoparallel of the metric-compatible connection) when neglecting
spin-curvature coupling.


title:
Upper limit for gamma-ray emission above 140 GeV from the dwarf
  spheroidal galaxy Draco

abstract:
  The nearby dwarf spheroidal galaxy Draco with its high mass to light ratio is
one of the most auspicious targets for indirect dark matter searches.
Annihilation of hypothetical DM particles can result in high-energy gamma-rays,
e.g. from neutralino annihilation in the supersymmetric framework. With the
MAGIC telescope a search for a possible DM signal originating from Draco was
performed during 2007. The analysis of the data results in a flux upper limit
of 1.1x10^-11 photons cm^-2 sec^-1 for photon energies above 140 GeV, assuming
a point like source. Furthermore, a comparison with predictions from
supersymmetric models is given. While our results do not constrain the mSUGRA
phase parameter space, a very high flux enhancement can be ruled out.


title:
Coupling of conduction electrons to two-level systems formed by
  hydrogen: A scattering approach

abstract:
  An effective Hamiltonian which could model the interaction between a
tunneling proton and the conduction electrons of a metal is investigated. A
remarkably simple correlation between the motion of the $TLS$-atom and an
angular-momentum change of scattering electron is deduced, at the first-order
Born level, by using a momentum-space representation with plane waves for
initial and final states. It is shown that the angular average of the
scattering amplitude-change at the Fermi surface depends solely on the
difference of the first two phase shifts, for small-distance displacements of
the heavy particle. For such a limit of displacement, and within a
distorted-wave Born approximation for initial and final states, the change in
the scattering amplitude is expressed via trigonometric functions of scattering
phase shifts at the Fermi energy. The numerical value of this change is
analyzed in the framework of a self-consistent screening description for
impurity-embedding in a paramagnetic electron gas. In order to discuss the
so-called antiabatic limit on the same footing, a comparison with matrix
elements obtained by the potential-gradient of an unscreened Coulomb field is
given as well. The coupling of the tunneling proton to a free-electron-like
electron gas is in the typical range obtained, by ultrasound experiments for
different metallic glasses, from scattering rates for a Korringa-type
relaxation process. That coupling is too weak to be in the range required for
realization of the two-channel Kondo effect.


title:
A short note on small deviations of sequences of i.i.d. random variables
  with exponentially decreasing weights

abstract:
  We obtain some new results concerning the small deviation problem for
$S=\sum_n q^n X_n$ and $M=\sup_n q^n X_n$, where $0<q<1$ and $(X_n)$ are i.i.d.
non-negative random variables. In particular, the asymptotics is shown to be
the same for $S$ and $M$ in some cases.


title:
Monte Carlo Simulation and Experimental Characterization of a Dual Head
  Gamma Camera

abstract:
  The GEANT4 Monte Carlo simulation and experimental characterization of the
Siemens E.Cam Dual Head gamma camera hosted in the Particular Hospital of
Algarve have been done. Imaging tests of thyroid and other phantoms have been
made "in situ" and compared with the results obtained with the Monte Carlo
simulation.


title: Target-ionization with exchange in Ps-atom scattering

abstract:
  A proposal is made by the University College of London Group [1] for
measuring the target-ionization cross sections in Ps and atom scattering. We
calculate the corresponding theoretical data for Ps-H and Ps-He systems
including the effect of exchange on Coulomb-Born approximation for the
projectile-elastic and projectile-inelastic processes and report the total
target-ionization cross sections for the first time.


title:
Constraining the neutron star equation of state using quiescent low-mass
  X-ray binaries

abstract:
  Chandra or XMM-Newton observations of quiescent low-mass X-ray binaries can
provide important constraints on the equation of state of neutron stars. The
mass and radius of the neutron star can potentially be determined from fitting
a neutron star atmosphere model to the observed X-ray spectrum. For a radius
measurement it is of critical importance that the distance to the source is
well constrained since the fractional uncertainty in the radius is at least as
large as the fractional uncertainty in the distance. Uncertainties in modelling
the neutron star atmosphere remain. At this stage it is not yet clear if the
soft thermal component in the spectra of many quiescent X-ray binaries is
variable on timescales too short to be accommodated by the cooling neutron star
scenario. This can be tested with a long XMM-Newton observation of the neutron
star X-ray transient CenX-4 in quiescence. With such an observation one can use
the Reflection Grating Spectrometer spectrum to constrain the interstellar
extinction to the source. This removes this parameter from the X-ray spectral
fitting of the EPIC pn and MOS spectra and allows one to investigate whether
the variability observed in the quiescent X-ray spectrum of this source is due
to variations in the soft thermal spectral component or variations in the power
law spectral component coupled with variations in N_H. This will test whether
the soft thermal component can indeed be due to the hot thermal glow of the
neutron star. Irrespective of the outcome of such a study, the observed cooling
in quiescence in sources for which the crust is significantly out of thermal
equilibrium with the core due to a prolonged outburst, such as KS 1731-260,
seem excellent candidates for mass and radius determinations through modelling
the observed X-rays with a neutron star atmosphere model.


title:
High-energy neutrinos from reverse shocks in choked and successful
  relativistic jets

abstract:
  Highly relativistic jets are a key element of current gamma-ray burst models,
where the jet kinetic energy is converted to radiation energy at optically thin
shocks. High-energy neutrinos are also expected, from interactions of protons
accelerated in the same shocks. Here we revisit the early evolution of a
relativistic jet, while the jet is still inside the star, and investigate its
neutrino emission. In particular we study propagation of mildly relativistic
and ultrarelativistic jets through a type Ib progenitor, and follow reverse
shocks as the jets cross the star. We show that protons can be accelerated to
10^4-10^5 GeV at reverse shocks, and efficiently produce mesons. The mesons
experience significant cooling, suppressing subsequent neutrino emission. We
show, however, that the neutrino yield from the reverse shock is still
reasonably large, especially for low-luminosity and long-duration jets, where
meson cooling is less severe. We discuss implications of our results in the
context of neutrinos from choked jets, which are completely shock heated and do
not break out of the star. From a choked jet with isotropic equivalent energy
of 10^{53} erg at 10 Mpc, we expect ~20 neutrino events at IceCube.


title: SuperWASP-N Extra-solar Planet Candidates from Fields 06hr < RA < 16hr

abstract:
  The Wide Angle Search for Planets (WASP) survey currently operates two
installations, designated SuperWASP-N and SuperWASP-S, located in the northern
and southern hemispheres respectively. These installations are designed to
provide high time-resolution photometry for the purpose of detecting transiting
extra-solar planets, asteroids, and transient events. Here we present results
from a transit-hunting observing campaign using SuperWASP-N covering a right
ascension range of 06hr < RA < 16hr. This paper represents the fifth and final
in the series of transit candidates released from the 2004 observing season. In
total, 729,335 stars from 33 fields were monitored with 130,566 having
sufficient precision to be scanned for transit signatures. Using a robust
transit detection algorithm and selection criteria, 6 stars were found to have
events consistent with the signature of a transiting extra-solar planet based
upon the photometry, including the known transiting planet XO-1b. These transit
candidates are presented here along with discussion of follow-up observations
and the expected number of candidates in relation to the overall observing
strategy.


title: On multiply connected wandering domains of meromorphic functions

abstract:
  We describe conditions under which a multiply connected wandering domain of a
transcendental meromorphic function with a finite number of poles must be a
Baker wandering domain, and we discuss the possible eventual connectivity of
Fatou components of transcendental meromorphic functions. We also show that if
$f$ is meromorphic, $U$ is a bounded component of $F(f)$ and $V$ is the
component of $F(f)$ such that $f(U)\subset V$, then $f$ maps each component of
$\partial U$ onto a component of the boundary of $V$ in $\hat{\C}$. We give
examples which show that our results are sharp; for example, we prove that a
multiply connected wandering domain can map to a simply connected wandering
domain, and vice versa.


title: Geometric Phase and Chiral Anomaly in Path Integral Formulation

abstract:
  All the geometric phases, adiabatic and non-adiabatic, are formulated in a
unified manner in the second quantized path integral formulation. The exact
hidden local symmetry inherent in the Schr\"{o}dinger equation defines the
holonomy. All the geometric phases are shown to be topologically trivial. The
geometric phases are briefly compared to the chiral anomaly which is naturally
formulated in the path integral.


title:
Remote Sensing of Chromospheric Magnetic Fields via the Hanle and Zeeman
  Effects

abstract:
  The only way to obtain reliable empirical information on the intensity and
topology of the weak magnetic fields of the quiet solar chromosphere is via the
measurement and rigorous physical interpretation of polarization signals in
chromospheric spectral lines. The observed Stokes profiles reported here are
due to the Hanle and Zeeman effects operating in a weakly magnetized plasma
that is in a state far from local thermodynamic equilibrium. The physical
origin of their enigmatic linear polarization Q and U components is the
existence of atomic polarization in their metastable lower-levels, which
permits the action of a dichroism mechanism that has nothing to do with the
transverse Zeeman effect. It is also pointed out that the population imbalances
and coherences among the Zeeman sublevels of such long-lived atomic levels can
survive in the presence of horizontal magnetic fields having intensities in the
gauss range, and produce significant polarization signals. Finally, it is shown
how the most recent developments in the observation and theoretical modelling
of weak polarization signals are facilitating fundamental new advances in our
ability to investigate the magnetism of the outer solar atmosphere via
spectropolarimetry.


title: Computing the Tutte polynomial in vertex-exponential time

abstract:
  The deletion--contraction algorithm is perhaps the most popular method for
computing a host of fundamental graph invariants such as the chromatic, flow,
and reliability polynomials in graph theory, the Jones polynomial of an
alternating link in knot theory, and the partition functions of the models of
Ising, Potts, and Fortuin--Kasteleyn in statistical physics. Prior to this
work, deletion--contraction was also the fastest known general-purpose
algorithm for these invariants, running in time roughly proportional to the
number of spanning trees in the input graph. Here, we give a substantially
faster algorithm that computes the Tutte polynomial--and hence, all the
aforementioned invariants and more--of an arbitrary graph in time within a
polynomial factor of the number of connected vertex sets. The algorithm
actually evaluates a multivariate generalization of the Tutte polynomial by
making use of an identity due to Fortuin and Kasteleyn. We also provide a
polynomial-space variant of the algorithm and give an analogous result for
Chung and Graham's cover polynomial. An implementation of the algorithm
outperforms deletion--contraction also in practice.


title: Pressure Induced Quantum Phase Transitions

abstract:
  A quantum critical point is approached by applying pressure in a number of
magnetic metals. The observed dependence of Tc on pressure necessarily means
that the magnetic energy is coupled to the lattice. A first order phase
transition occurs if this coupling exceeds a critical value: this is inevitable
if diverges as Tc approaches zero. It is argued that this is the cause of the
first order transition that is observed in many systems. Using Landau theory we
obtain expressions for the boundaries of the region where phase separation
occurs that agree well with experiments done on MnSi and other materials. The
theory can be used to obtain very approximate values for the temperature and
pressure at the tricritical point in terms of quantities measured at ambient
pressure and the measured values of along the second order line. The values of
the tricritical temperature for various materials obtained from Landau theory
are too low but it is shown that the predicted values will rise if the effects
of fluctuations are included.


title:
Inter-comparison of the g-, f- and p-modes calculated using different
  oscillation codes for a given stellar model

abstract:
  In order to make astroseismology a powerful tool to explore stellar
interiors, different numerical codes should give the same oscillation
frequencies for the same input physics. This work is devoted to test, compare
and, if needed, optimize the seismic codes used to calculate the
eigenfrequencies to be finally compared with observations. The oscillation
codes of nine research groups in the field have been used in this study. The
same physics has been imposed for all the codes in order to isolate the
non-physical dependence of any possible difference. Two equilibrium models with
different grids, 2172 and 4042 mesh points, have been used, and the latter
model includes an explicit modelling of semiconvection just outside the
convective core. Comparing the results for these two models illustrates the
effect of the number of mesh points and their distribution in particularly
critical parts of the model, such as the steep composition gradient outside the
convective core. A comprehensive study of the frequency differences found for
the different codes is given as well. These differences are mainly due to the
use of different numerical integration schemes. The use of a second-order
integration scheme plus a Richardson extrapolation provides similar results to
a fourth-order integration scheme. The proper numerical description of the
Brunt-Vaisala frequency in the equilibrium model is also critical for some
modes. An unexpected result of this study is the high sensitivity of the
frequency differences to the inconsistent use of values of the gravitational
constant (G) in the oscillation codes, within the range of the experimentally
determined ones, which differ from the value used to compute the equilibrium
model.


title: Noncommutative Riemann Surfaces

abstract:
  We introduce C-Algebras of compact Riemann surfaces $\Sigma$ as
non-commutative analogues of the Poisson algebra of smooth functions on
$\Sigma$. Representations of these algebras give rise to sequences of
matrix-algebras for which matrix-commutators converge to Poisson-brackets as
$N\to\infty$. For a particular class of surfaces, nicely interpolating between
spheres and tori, we completely characterize (even for the intermediate
singular surface) all finite dimensional representations of the corresponding
C-algebras.


title: Gauge-Higgs Unification at LHC

abstract:
  Higgs boson production by the gluon fusion and its decay into two photons at
the LHC are investigated in the context of the gauge-Higgs unification
scenario. The qualitative behaviors for these processes in the gauge-Higgs
unification are quite distinguishable from those of the Standard Model and the
universal extra dimension scenario because of the overall sign difference for
the effective couplings induced by one-loop corrections through Kaluza-Klein
(KK) modes. For the KK mode mass smaller than 1 TeV, the Higgs productions
cross section and its branching ratio into two photons are sizably deviated
from those in the Standard Model. Associated with the discovery of Higgs boson,
this deviation may be measured at the LHC.


title: Granada oscillation Code (GraCo)

abstract:
  Granada oscillation code (GraCo) is a software constructed to compute
adiabatic and non-adiabatic oscillation eigenfunctions and eigenvalues. The
adiabatic version gives the standard numerical resolution, and also the
Richardson extrapolation, different sets of eigenfunctions, different outer
mechanical boundary conditions or different integration variables. The
non-adiabatic version can include the atmosphere-pulsation interaction. The
code has been used for intensive studies of \delta Scuti, \gamma Doradus, \beta
Ceph., SdO and, SdB stars. The non adiabatic observables ``phase-lag'' (the
phase between the effective temperature variations and the radial displacement)
and \delta T_{eff}/ T_{eff} (relative surface temperature variation) can help
to the modal identification. These quantities together with the energy balance
(``growth rate'') provide useful additional information to the adiabatic
resolution (eigenfrequencies and eigenfunctions).


title: Large Cardinals and Definable Well-Orderings of the Universe

abstract:
  We use a reverse Easton forcing iteration to obtain a universe with a
definable well-ordering, while preserving the GCH and proper classes of a
variety of very large cardinals. This is achieved by coding using the principle
diamond star at a proper class of successor cardinals.


title:
Electronic excitations of a single molecule contacted in a
  three-terminal configuration

abstract:
  Low-temperature three-terminal transport measurements through a thiol
end-capped Pi -conjugated molecule have been carried out. Electronic
excitations, including zero and finite-bias Kondo-effects have been observed
and studied as a function of magnetic field. Using a simplified two-orbital
model we have accounted for the spin and the electronic configuration of the
first four charge states of the molecule. The charge-dependent couplings to
gate, source and drain electrodes suggest a scenario in which charges and spins
are localized at the ends of the molecule, close to the electrodes.


title:
Gravitational wave generation from bubble collisions in first-order
  phase transitions: an analytic approach

abstract:
  Gravitational wave production from bubble collisions was calculated in the
early nineties using numerical simulations. In this paper, we present an
alternative analytic estimate, relying on a different treatment of
stochasticity. In our approach, we provide a model for the bubble velocity
power spectrum, suitable for both detonations and deflagrations. From this, we
derive the anisotropic stress and analytically solve the gravitational wave
equation. We provide analytical formulae for the peak frequency and the shape
of the spectrum which we compare with numerical estimates. In contrast to the
previous analysis, we do not work in the envelope approximation. This paper
focuses on a particular source of gravitational waves from phase transitions.
In a companion article, we will add together the different sources of
gravitational wave signals from phase transitions: bubble collisions,
turbulence and magnetic fields and discuss the prospects for probing the
electroweak phase transition at LISA.


title:
Quasideterminant solutions of a non-Abelian Toda lattice and kink
  solutions of a matrix sine-Gordon equation

abstract:
  Two families of solutions of a generalized non-Abelian Toda lattice are
considered. These solutions are expressed in terms of quasideterminants,
constructed by means of Darboux and binary Darboux transformations. As an
example of the application of these solutions, we consider the 2-periodic
reduction to a matrix sine-Gordon equation. In particular, we investigate the
interaction properties of polarized kink solutions.


title:
Effects of photophoresis on the evolution of transitional circumstellar
  disks

abstract:
  Although known for almost a century, the photophoretic force has only
recently been considered in astrophysical context for the first time. In our
work, we have examined the effect of photophoresis, acting together with
stellar gravity, radiation pressure, and gas drag, on the evolution of solids
in transitional circumstellar disks. We have applied our calculations to four
different systems: the disks of HR 4796A and HD 141569A, which are several Myr
old AB-type stars, and two hypothetical systems that correspond to the solar
nebula after disk dispersal has progressed sufficiently for the disk to become
optically thin. Our results suggest that solid objects migrate inward or
outward, until they reach a certain size-dependent stability distance from the
star. The larger the bodies, the closer to the star they tend to accumulate.
Photophoresis increases the stability radii, moving objects to larger
distances. What is more, photophoresis may cause formation of a belt of
objects, but only in a certain range of sizes and only around low-luminosity
stars. The effects of photophoresis are noticeable in the size range from
several micrometers to several centimeters (for older transitional disks) or
even several meters (for younger, more gaseous, ones). We argue that due to gas
damping, rotation does not substantially inhibit photophoresis.


title:
Tracing the origins of permitted emission lines in RU Lupi down to AU
  scales

abstract:
  Most of the observed emission lines and continuum excess from young accreting
low mass stars (Classical T Tauri stars -- CTTSs) take place in the star-disk
or inner disk region. These regions have a complex emission topology still
largely unknown. In this paper the magnetospheric accretion and inner wind
contributions to the observed permitted He and H near infrared (NIR) lines of
the bright southern CTTS RU Lupi are investigated for the first time. Previous
optical observations of RU Lupi showed a large H-alpha profile, due to the
emission from a wind in the line wings, and a micro-jet detected in forbidden
lines. We extend this analysis to NIR lines through seeing-limited high
spectral resolution spectra taken with VLT/ISAAC, and adaptive optics (AO)
aided narrow-band imaging and low spectral resolution spectroscopy with
VLT/NACO. Using spectro-astrometric analysis we investigate the presence of
extended emission down to very low spatial scales (a few AU). The HeI 10830
line presents a P Cygni profile whose absorption feature indicates the presence
of an inner stellar wind. Moreover the spectro-astrometric analysis evidences
the presence of an extended emission superimposed to the absorption feature and
likely coming from the micro-jet detected in the optical. On the contrary, the
origin of the Hydrogen Paschen and Brackett lines is difficult to address. We
tried tentatively to explain the observed line profiles and flux ratios with
both accretion and wind models showing the limits of both approaches. The lack
of spectro-astrometric signal indicates that the HI emission is either compact
or symmetric. Our analysis confirms the sensitivity of the HeI line to the
presence of faint extended emission regions in the close proximity of the star.


title:
A note on groups with the minimal conditions for nonabelian and abelian
  subgroups

abstract:
  We give a new proof of the known Shunkov's Theorem on locally finite groups
with the minimal condition for nonabelian subgroups and also an extension of
the known Suchkova-Shunkov Theorem on Shunkov groups with the minimal condition
for abelian subgroups.


title: Magnetic trapping of a cold Rb-Cs atomic mixture

abstract:
  We present an apparatus for the study of an ultracold gaseous atomic mixture
of 133Cs and 87Rb. The mixture is prepared using a double magneto-optical trap
(MOT) system in which a two-species pyramid MOT acts as a source of cold atoms
for a `science' MOT. Measurements of the interspecies trap loss rate
coefficients beta_RbCs and beta_CsRb in the science MOT are reported. After the
initial MOT phase, atoms in the mixture are optically pumped into the
magnetically trappable |F=3,m_F=-3> and |F=1,m_F=-1> states of Cs and Rb
(respectively) and loaded into an Ioffe-Pritchard magnetic trap. We demonstrate
a novel technique for limiting the interspecies loss rate in the science MOT by
spatially separating the two trapped atom clouds, which greatly enhances the
number of atoms which can be loaded into the magnetic trap.


title: On Properties of Hamiltonian Structures for a Class of Evolutionary PDEs

abstract:
  In \cite{LZ2} it is proved that for certain class of perturbations of the
hyperbolic equation $u_t=f(u) u_x$, there exist changes of coordinate, called
quasi-Miura transformations, that reduce the perturbed equations to the
unperturbed one. We prove in the present paper that if in addition the
perturbed equations possess Hamiltonian structures of certain type, the same
quasi-Miura transformations also reduce the Hamiltonian structures to their
leading terms. By applying this result, we obtain a criterion of the existence
of Hamiltonian structures for a class of scalar evolutionary PDEs and an
algorithm to find out the Hamiltonian structures.


title:
The neutrino masses and the change of allowed parameter region in
  universal extra dimension models

abstract:
  Relic abundance of dark matter is investigated in the framework of universal
extra dimension models with right-handed neutrinos. These models are free from
the serious Kaluza-Klein (KK) graviton problem that the original universal
extra dimension model possesses. The first KK particle of the right-handed
neutrino is a candidate for dark matter in this framework. When ordinary
neutrino masses are large enough such as the degenerate mass spectrum case, the
dark matter relic abundance can change significantly. The scale of the extra
dimension consistent with cosmological observations can be 500 GeV in the
minimal setup of universal extra dimension models with right-handed neutrinos.