title:
Stellar Population Models and Individual Element Abundances I:
  Sensitivity of Stellar Evolution Models

abstract:
  Integrated light from distant galaxies is often compared to stellar
population models via the equivalent widths of spectral features--spectral
indices--whose strengths rely on the abundances of one or more elements. Such
comparisons hinge not only on the overall metal abundance but also on relative
abundances. Studies have examined the influence of individual elements on
synthetic spectra but little has been done to address similar issues in the
stellar evolution models that underlie most stellar population models. Stellar
evolution models will primarily be influenced by changes in opacities. In order
to explore this issue in detail, twelve sets of stellar evolution tracks and
isochrones have been created at constant heavy element mass fraction Z that
self-consistently account for varying heavy element mixtures. These sets
include scaled-solar, alpha-enhanced, and individual cases where the elements
C, N, O, Ne, Mg, Si, S, Ca, Ti, and Fe have been enhanced above their
scaled-solar values. The variations that arise between scaled-solar and the
other cases are examined with respect to the H-R diagram and main sequence
lifetimes.


title: The ultra-compact binary candidate KUV 23182+1007 is a bright quasar

abstract:
  KUV 23182+1007 was identified as a blue object in the Kiso UV Survey in the
1980s. Classification-dispersion spectroscopy showed a featureless continuum
except for a strong emission line in the region of He II 4686 A. This is a
hallmark of the rare AM CVn class of cataclysmic variable star, so we have
obtained a high-S/N blue spectrum of this object to check its classification.
Instead, the spectrum shows a strong quasar-like emission line centred on 4662
A. Comparison with the SDSS quasar template spectra confirms that KUV
23182+1007 is a quasar with a redshift of z = 0.665.


title:
Lyman Break Galaxies at z~1 and the evolution of the dust attenuation in
  star-forming galaxies with the redshift

abstract:
  Ultraviolet (UV) galaxies have been selected from GALEX. The presence of a
FUV-dropout in their spectral energy distributions proved to be a very complete
(83.3%) but not very efficient (21.4%) tool for identifying Lyman Break
Galaxies (LBGs) at z~1. We divide the LBG sample into two sub-classes: red LBGs
(RLBGs) detected at 24 micron which are mainly Luminous IR Galaxies (LIRGs) and
blue LBGs (BLBGs) undetected at 24 microns down to 83 microJy. Two of the RLBGs
are also detected at 70 micron. The median SED of the RLBGs is similar (above
lambda~1 micron) to the dusty starburst HR10. However, unlike local (U)LIRGs,
RLBGs are UV bright objects. We suggest that these objects contain a large
amount of dust but that some bare stellar populations are also directly
visible. The median SED of the BLBGs is consistent with their containing the
same stellar population as the RLBGs but with a lower dust content. The
luminosity function of our LBG sample at z~1 is similar to the luminosity
function of NUV-selected galaxies at the same redshift. The integrated
luminosity densities of z~1 LBGs and NUV-selected galaxies are very consistent.
We show that star formation rates (SFRs) estimated from UV measurements and
corrected using the IRX-beta method provide average total SFR_TOT in agreement
with SFR_UV + SFR_dust. However, IRX-beta-based SFR_TOT shows a large
dispersion. Summing up the detected UV (1150A rest-frame) and IR-based star
formation rates of the detected objects, we find that only one third of the
total (i.e. UV + dust) LBG SFR resides in BLBGs and two thirds in RLBGs, even
though most LBGs at z~1 are BLBGs. On the other hand, the total SFR of LBGs
accounts for only 11% of the total SFR at z~1. Finally, we observe a regular
decrease of L_TIR / L_FUV from z=0 to z~2 for UV-selected samples.


title:
First CO J=6-5, 4-3 detections in local ULIRGs: the dense gas in Mrk231,
  and its colling budget

abstract:
  We report on detections of the high-excitation CO J=6-5, J=4-3 lines in
Mrk231, a prototypical Ultra Luminous Infrared Galaxy (ULIRG) and Seyfert 1
QSO. These observations are combined with CO J=3-2, HCN J=4-3 (this work), and
CO J=2-1, J=1-0, 13CO J=2-1, HCN J=1-0 measurements taken from the literature
to provide better constraints on the properties of the molecular gas in an
extreme starburst/QSO in the local Universe. We find that the CO J=4-3 and
J=6-5 transitions trace a different gas phase from that dominating the lower
three CO transitions, with n(H_2) ~ (1-3)x10^4 cm-3 and Tk ~ (40-70) K. This
phase is responsible for the luminous HCN emission, and contains most of the H2
gas mass of this galaxy. The total CO line cooling emanating from this dense
phase is found similar to that of the [CII] line at 158 micron, suggesting a
very different thermal balance to that seen in lower IR-luminosity galaxies,
and one likely dominated by dense photon-dominated regions. Our dense
"sampling" of the CO rotational ladder and the HCN lines enables us to produce
well-constrained Spectral Line Energy Distributions (SLEDs) for the dense
molecular gas in Mrk231 and compare them to those of high redshift starbursts,
many of which have SLEDs that may be affected by strong lensing. Finally, we
use our local molecular line excitation template to assess the capabilities of
future cm and mm/sub-mm arrays in detecting CO and HCN transitions in similar
systems throughout the local and distant universe.


title: Spectral coarse-graining of complex networks

abstract:
  Reducing the complexity of large systems described as complex networks is key
to understand them and a crucial issue is to know which properties of the
initial system are preserved in the reduced one. Here we use random walks to
design a coarse-graining scheme for complex networks. By construction the
coarse-graining preserves the slow modes of the walk, while reducing
significantly the size and the complexity of the network. In this sense our
coarse-graining allows to approximate large networks by smaller ones, keeping
most of their relevant spectral properties.


title: Crystallization of the Wahnstr\"om Binary Lennard-Jones Liquid

abstract:
  We report observation of crystallization of the glass-forming binary
Lennard-Jones liquid first used by Wahnstr\"om [G. Wahnstr\"om, Phys. Rev. A
44, 3752 (1991)]. Molecular dynamics simulations of the metastable liquid on a
timescale of microseconds were performed. The liquid crystallized
spontaneously. The crystal structure was identified as MgZn_2. Formation of
transient crystallites is observed in the liquid. The crystallization is
investigate at different temperatures and compositions. At high temperature the
rate of crystallite formation is the limiting factor, while at low temperature
the limiting factor is growth rate. The melting temperature of the crystal is
estimated to be T_m=0.93 at rho=0.82. The maximum crystallization rate of the
A_2B composition is T=0.60+/-0.02.


title:
New conditional symmetries and exact solutions of nonlinear
  reaction-diffusion-convection equations. II

abstract:
  In the first part of this paper math-ph/0612078, a complete description of
Q-conditional symmetries for two classes of reaction-diffusion-convection
equations with power diffusivities is derived. It was shown that all the known
results for reaction-diffusion equations with power diffusivities follow as
particular cases from those obtained in math-ph/0612078 but not vise versa. In
the second part the symmetries obtained in are successfully applied for
constructing exact solutions of the relevant equations. In the particular case,
new exact solutions of nonlinear reaction-diffusion-convection (RDC) equations
arising in application and their natural generalizations are found.


title: Energy Current Correlations For Weakly Anharmonic Lattices

abstract:
  We discuss energy current correlations in thermal equilibrium and point out
the linkage to the fluctuating Peierls equation.


title: Nonlocal Phenomenology for anisotropic MHD turbulence

abstract:
  A non-local cascade model for anisotropic MHD turbulence in the presence of a
guiding magnetic field is proposed. The model takes into account that (a)
energy cascades in an anisotropic manner and as a result a different estimate
for the cascade rate in the direction parallel and perpendicular to the guiding
field is made. (b) the interactions that result in the cascade are between
different scales. Eddies with wave numbers $k_\|$ and $k_\perp$ interact with
eddies with wave numbers $q_\|,q_\perp$ such that a resonance condition between
the wave numbers $q_\|,q_\perp$ and $k_\|,k_\perp$ holds. As a consequence
energy from the eddy with wave numbers $k_\|$ and $k_\perp$ cascades due to
interactions with eddies located in the resonant manifold whose wavenumbers are
determined by: $q_\|\simeq \epsilon^{{1}/{3}}k_\perp^{2/3}/B$,
$q_\perp=k_\perp$ and energy will cascade along the lines $k_\|\sim
C+k_\perp^{2/3} \epsilon^{1/3}/B_0$. For a uniform energy injection rate in the
parallel direction the resulting energy spectrum is $E(k_\|,k_\perp)\simeq
\epsilon^{2/3}k_\|^{-1}k_\perp^{-5/3}$. For a general forcing however the model
suggests a non-universal behavior. The connections with previous models,
numerical simulations and weak turbulence theory are discussed.


title: Measure-valued stochastic recurrences and the stability of queues

abstract:
  In this paper we present a stability criterion for finite measure-valued
stochastic recursions, generalizing Loynes's Theorem to spaces of measures.
This result provides conditions for the reach of a "total stationary state" for
the queue with an infinity of servers and the single-server SRPT queue. Indeed,
we give in both cases a condition of existence of a stationary measure-valued
recursive sequence characterizing the queueing system exhaustively.


title:
Spitzer Quasar and ULIRG Evolution Study (QUEST): II. The Spectral
  Energy Distributions of Palomar-Green Quasars

abstract:
  This is the second paper studying the QSOs in the spitzer QUEST sample.
Previously we presented new PAH measurements and argued that most of the
observed far infrared (FIR) radiation is due to star-forming activity. Here we
present spectral energy distributions (SEDs) by supplementing our data with
optical, NIR and FIR observations. We define two sub-groups of ``weak FIR'' and
``strong FIR'' QSOs, and a third group of FIR non-detections. Assuming a
starburst origin for the FIR, we obtain ``intrinsic'' AGN SEDs by subtracting a
starburst template from the mean SEDs. The resulting SEDs are remarkably
similar for all groups. They show three distinct peaks corresponding to two
silicate emission features and a 3mic bump that we interpret as the signature
of the hottest AGN dust. They also display drops beyond 20mic that we interpret
as the signature of the minimum temperature (about 200K) dust. This component
must be optically thin to explain the silicate emission and the slope of the
long wavelength continuum. We discuss the merits of an alternative model where
most of the FIR emission is due to AGN heating. Such models are unlikely to
explain the properties of our QSOs but they cannot be ruled out for more
luminous objects. We also find correlations between the luminosity at 5100A and
two infrared starburst indicators: L(60mic) and L(PAH 7.7mic). The correlation
of L(5100A) with L(60mic) can be used to measure the relative growth rates and
lifetimes of the black hole and the new stars.


title:
On the Dirac delta as initial condition for nonlinear Schr\"odinger
  equations

abstract:
  In this article we will study the initial value problem for some
Schr\"odinger equations with Diraclike initial data and therefore with infinite
L2 mass, obtaining positive results for subcritical nonlinearities. In the
critical case and in one dimension we prove that after some renormalization the
corresponding solution has finite energy. This allows us to conclude a
stability result in the defocusing setting. These problems are related to the
existence of a singular dynamics for Schr\"odinger maps through the so called
Hasimoto transformation.


title: On the Poisson-Lie T-plurality of boundary conditions

abstract:
  Conditions for the gluing matrix defining consistent boundary conditions of
two-dimensional nonlinear sigma-models are analyzed and reformulated.
Transformation properties of the right-invariant fields under Poisson-Lie
T-plurality are used to derive a formula for the transformation of the boundary
conditions. Examples of transformation of D-branes in two and three dimensions
are presented. We investigate obstacles arising in this procedure and propose
possible solutions.


title:
Magnetic dead layers in La2/3Ca1/3MnO3 thin films probed by X-ray
  magnetic circular dichroism in reflection

abstract:
  Surface magnetic properties of perovskite manganites have been a recurrent
topic during last years since they play a major role in the implementation of
magnetoelectronic devices. Magneto-optical techniques, such as X-ray magnetic
circular dichroism, turn out to be a very efficient tool to study surface
magnetism due to their sensitivity to magnetic and chemical variations across
the sample depth. Nevertheless, the application of the sum rules for the
determination of the spin magnetic moment might lead to uncertainties as large
as 40% in case of Mn ions. To overcome this problem we present an alternative
approach consisting of using X-ray magnetic circular dichroism in reflection
geometry. Fit of the data by using a computer code based in a 4X4 matrix
formalism leads to realistic results. In particular, we show that surface and
interface roughness are of major relevance for a proper description of the
experimental data and a correct interpretation of the results. By using such an
approach we demonstrate the presence of a narrow surface region with strongly
depressed magnetic properties in La2/3Ca1/3MnO3 thin films.


title: Mutations for quivers with potentials: Oberwolfach talk, April 2007

abstract:
  This is an extended abstract of my talk at the Oberwolfach Workshop
"Algebraic Groups" (April 22 - 28, 2007). It is based on a joint work with
H.Derksen and J.Weyman (arXiv:0704.0649v2 [math.RA]).


title:
Dynamics of Localization Phenomena for Hardcore Bosons in Optical
  Lattices

abstract:
  We investigate the behavior of ultracold bosons in optical lattices with a
disorder potential generated via a secondary species frozen in random
configurations. The statistics of disorder is associated with the physical
state in which the secondary species is prepared. The resulting random
potential, albeit displaying algebraic correlations, is found to lead to
localization of all single-particle states. We then investigate the real-time
dynamics of localization for a hardcore gas of mobile bosons which are brought
into sudden interaction with the random potential. Regardless of their initial
state and for any disorder strength, the mobile particles are found to reach a
steady state characterized by exponentially decaying off-diagonal correlations
and by the absence of quasi-condensation; when the mobile particles are
initially confined in a tight trap and then released in the disorder potential,
their expansion is stopped and the steady state is exponentially localized in
real space, clearly revealing Anderson localization.


title: Quantum evolution across singularities

abstract:
  Attempts to consider evolution across space-time singularities often lead to
quantum systems with time-dependent Hamiltonians developing an isolated
singularity as a function of time. Examples include matrix theory in certain
singular time-dependent backgounds and free quantum fields on the
two-dimensional compactified Milne universe. Due to the presence of the
singularities in the time dependence, the conventional quantum-mechanical
evolution is not well-defined for such systems. We propose a natural way,
mathematically analogous to renormalization in conventional quantum field
theory, to construct unitary quantum evolution across the singularity. We carry
out this procedure explicitly for free fields on the compactified Milne
universe and compare our results with the matching conditions considered in
earlier work (which were based on the covering Minkowski space).


title:
Incidence of the boundary shape in the effective theory of fractional
  quantum Hall edges

abstract:
  Starting from a microscopic description of a system of strongly interacting
electrons in a strong magnetic field in a finite geometry, we construct the
boundary low energy effective theory for a fractional quantum Hall droplet
taking into account the effects of a smooth edge. The effective theory obtained
is the standard chiral boson theory (chiral Luttinger theory) with an
additional self-interacting term which is induced by the boundary. As an
example of the consequences of this model, we show that such modification leads
to a non-universal reduction in the tunnelling exponent which is independent of
the filling fraction. This is in qualitative agreement with experiments, that
systematically found exponents smaller than those predicted by the ordinary
chiral Luttinger liquid theory.


title:
Central limit theorems in linear structural error-in-variables models
  with explanatory variables in the domain of attraction of the normal law

abstract:
  Linear structural error-in-variables models with univariate observations are
revisited for studying modified least squares estimators of the slope and
intercept. New marginal central limit theorems (CLT's) are established for
these estimators, assuming the existence of four moments for the measurement
errors and that the explanatory variables are in the domain of attraction of
the normal law. The latter condition for the explanatory variables is used the
first time, and is so far the most general in this context. It is also optimal,
or nearly optimal, for our CLT's. Moreover, due to the obtained CLT's being in
Studentized and self-normalized forms to begin with, they are a priori nearly,
or completely, data-based, and free of unknown parameters of the joint
distribution of the error and explanatory variables. Consequently, they lead to
a variety of readily available, or easily derivable, large-sample approximate
confidence intervals (CI's) for the slope and intercept. In contrast, in
related CLT's in the literature so far, the variances of the limiting normal
distributions, in general, are complicated and depend on various, typically
unknown, moments of the error and explanatory variables. Thus, the
corresponding CI's for the slope and intercept in the literature, unlike those
of the present paper, are available only under some additional model
assumptions.


title:
Limited validity of West and Yennie integral formula for elastic
  scattering of hadrons

abstract:
  The commonly used West and Yennie integral formula for the relative phase
between the Coulomb and elastic hadronic amplitudes might be consistently
applied to only if the hadronic amplitude had the constant ratio of the real to
the imaginary parts al all kinematically allowed values of four momentum
transfer squared.


title: On the Magnetic Prandtl Number Behavior of Accretion Disks

abstract:
  We investigate the behavior of the magnetic Prandtl number (ratio of
microscopic viscosity to resistivity) for accretion sources. Generally this
number is very small in standard accretion disk models, but can become larger
than unity within $\sim 50$ Schwarzschild radii of the central mass. Recent
numerical investigations suggest a marked dependence of the level of MHD
turbulence on the value of the Prandtl number. Hence, black hole and neutron
star accretors, i.e. compact X-ray sources, are affected. The astrophysical
consequences of this could be significant, including a possible route to
understanding the mysterious state changes that have long characterized these
sources.


title: Generalized superstatistics of nonequilibrium Markovian systems

abstract:
  The paper is devoted to the construction of the superstatistical description
for nonequilibrium Markovian systems. It is based on Kirchhoff's diagram
technique and the assumption on the system under consideration to possess a
wide variety of cycles with vanishing probability fluxes. The latter feature
enables us to introduce equivalence classes called channels within which
detailed balance holds individually. Then stationary probability as well as
flux distributions are represented as some sums over the channels. The latter
construction actually forms the superstatistical description, which, however,
deals with a certain superposition of equilibrium subsystems rather then is a
formal expansion of the nonequilibrium steady state distribution into terms of
the Boltzmann type.


title:
The importance of the merging activity for the kinetic polarization of
  the Sunyaev-Zel'dovich signal from galaxy clusters

abstract:
  The polarization sensitivity of the upcoming millimetric observatories will
open new possibilities for studying the properties of galaxy clusters and for
using them as powerful cosmological probes. For this reason it is necessary to
investigate in detail the characteristics of the polarization signals produced
by their highly ionized intra-cluster medium (ICM). This work is focussed on
the polarization effect induced by the ICM bulk motions, the so-called kpSZ
signal, which has an amplitude proportional to the optical depth and to the
square of the tangential velocity. In particular we study how this polarization
signal is affected by the internal dynamics of galaxy clusters and what is its
dependence on the physical modelling adopted to describe the baryonic
component. This is done by producing realistic kpSZ maps starting from the
outputs of two different sets of high-resolution hydrodynamical N-body
simulations. The first set (17 objects) follows only non-radiative
hydrodynamics, while for each of 9 objects of the second set we implement four
different kinds of physical processes. Our results shows that the kpSZ signal
turns out to be a very sensitive probe of the dynamical status of galaxy
clusters. We find that major merger events can amplify the signal up to one
order of magnitude with respect to relaxed clusters, reaching amplitude up to
about 100 nuK. This result implies that the internal ICM dynamics must be taken
into account when evaluating this signal because simplicistic models, based on
spherical rigid bodies, may provide wrong estimates. Finally we find that the
dependence on the physical modelling of the baryonic component is relevant only
in the very inner regions of clusters.


title:
Possible evolution of dim radio quiet neutron star 1E 1207.4-5209 based
  on a B-decay model

abstract:
  Dim radio-quiet neutron star (DRQNS) 1E 1207.4-5209 is one of the most
heavily examined isolated neutron stars. Wide absorption lines were observed in
its spectrum obtained by both XMM-Newton and Chandra X-ray satellites. These
absorption lines can be interpreted as a principal frequency centered at 0.7
keV and its harmonics at 1.4, 2.1 and possibly 2.8 keV. The principal line can
be formed by resonant proton cyclotron scattering leading to a magnetic field
which is two orders of magnitude larger than the perpendicular component of the
surface dipole magnetic field (B) found from the rotation period (P) and the
time rate of change in the rotation period (\.{P}) of 1E 1207.4-5209. Besides,
age of the supernova remnant (SNR) G296.5+10.0 which is physically connected to
1E 1207.4-5209 is two orders of magnitude smaller than the characteristic age
($\tau$=P/2\.{P}) of the neutron star. These huge differences between the
magnetic field values and the ages can be explained based on a B-decay model.
If the decay is assumed to be exponential, the characteristic decay time turns
out to be several thousand years which is three orders of magnitude smaller
than the characteristic decay time of radio pulsars represented in an earlier
work. The lack of detection of radio emission from DRQNSs and the lack of point
sources and pulsar wind nebulae in most of the observed SNRs can also be partly
explained by such a very rapid exponential decay. The large difference between
the characteristic decay times of DRQNSs and radio pulsars must be related to
the differences in the magnetic fields, equation of states and masses of these
isolated neutron stars.


title: INTEGRAL high energy monitoring of the X-ray burster KS 1741-293

abstract:
  KS 1741-293, discovered in 1989 by the X-ray camera TTM in the Kvant module
of the Mir space station and identified as an X-ray burster, has not been
detected in the hard X band until the advent of the INTEGRAL observatory.
Moreover this source has been recently object of scientific discussion, being
also associated to a nearby extended radio source that in principle could be
the supernova remnant produced by the accretion induced collapse in the binary
system. Our long term monitoring with INTEGRAL, covering the period from
February 2003 to May 2005, confirms that KS 1741-293 is transient in soft and
hard X band. When the source is active, from a simultaneous JEM-X and IBIS data
analysis, we provide a wide band spectrum from 5 to 100 keV, that can be fit by
a two component model, a multiple blackbody for the soft emission and a
Comptonized or a cut-off power law model for the hard component. Finally, by
the detection of two X-ray bursters with JEM-X, we confirm the bursting nature
of KS 1741-293, including this source in the class of the hard tailed X-ray
bursters.


title:
Functional Integral Representation of the Pauli-Fierz Model with Spin
  1/2

abstract:
  A Feynman-Kac-type formula for a L\'evy and an infinite dimensional Gaussian
random process associated with a quantized radiation field is derived. In
particular, a functional integral representation of $e^{-t\PF}$ generated by
the Pauli-Fierz Hamiltonian with spin $\han$ in non-relativistic quantum
electrodynamics is constructed. When no external potential is applied $\PF$
turns translation invariant and it is decomposed as a direct integral $\PF =
\int_\BR^\oplus \PF(P) dP$. The functional integral representation of
$e^{-t\PF(P)}$ is also given. Although all these Hamiltonians include spin,
nevertheless the kernels obtained for the path measures are scalar rather than
matrix expressions. As an application of the functional integral
representations energy comparison inequalities are derived.


title: Resonant Scattering of Ultracold Atoms in Low Dimensions

abstract:
  Low energy scattering amplitudes for two atoms in one- and two-dimensional
atomic wave guides are derived for short range isotropic and resonant
interactions in high partial wave channels. Taking into account the finite
width of the resonance which was neglected in previous works is shown to have
important implications in the properties of the confinement induced resonances.
For spin polarized fermions in quasi-1D wave guides it imposes a strong
constraint on the atomic density for achieving the Fermi Tonks Girardeau gas.
For a planar wave guide, the charateristics of the 2D induced scattering
resonances in $p$- and d-wave are determined as a function of the 3D scattering
parameters and of the wave guide frequency.


title: Tunnelling in alkanes anchored to gold electrodes via amine end groups

abstract:
  For investigation of electron transport on the nanoscale, a system possessing
a simple to interpret electronic structure is composed of alkane chains
bridging two electrodes via end groups; to date the majority of experiments and
theoretical investigations on such structures have considered thiols bonding to
gold electrodes. Recently experiments show that well defined molecular
conductances may be resolved if the thiol end groups are replaced by amines. In
this theoretical study, we investigate the bonding of amine groups to gold
clusters and calculate electron transport across the resulting tunnel
junctions. We find very good agreement with recent experiments for alkane
diamines and discuss differences with respect to the alkane dithiol system.


title: EVN observations of an OH maser burst in OH17.7-2.0

abstract:
  We have observed the OH 1612-MHz maser emission towards the proto-planetary
nebula candidate OH17.7-2.0 that underwent a very strong and unusual outburst
in 2003. Phase-referencing data were obtained with the EVN in order to localize
the outburst and to examine its possible causes. The majority of the emission
comes from an incomplete spherical shell with inner and outer radii of 220 and
850 mas, respectively. There is a strong evidence for maser components that
arise due to the interaction of a jet-like post-AGB outflow with the remnant
outer AGB shell. The most prominent signature of such an interaction is the
strongly bursting polarized emission near 73.3km/s coming from two unresolved
components of brightness temperature up to 10^11K located at the edge of the
biconal region 2500 AU from the central star. It is remarkable that this OH
biconal region is well-aligned with the polar outflow inferred from the
near-infrared image.


title:
Saturation effects in the sub-Doppler spectroscopy of Cesium vapor
  confined in an Extremely Thin Cell

abstract:
  Saturation effects affecting absorption and fluorescence spectra of an atomic
vapor confined in an Extremely Thin Cell (cell thickness $L < 1 \mu m$) are
investigated experimentally and theoretically. The study is performed on the
$D_{2}$ line ($\lambda ~= ~852 nm)$ of $Cs$ and concentrates on the two
situations $L = \lambda /2$ and $L =\lambda$, the most contrasted ones with
respect to the length dependence of the coherent Dicke narrowing. For $L =
\lambda /2$, the Dicke-narrowed absorption profile simply broadens and
saturates in amplitude when increasing the light intensity, while for $L
=\lambda$, sub-Doppler dips of reduced absorption at line-center appear on the
broad absorption profile. For a fluorescence detection at $L =\lambda$,
saturation induces narrow dips, but only for hyperfine components undergoing a
population loss through optical pumping. These experimental results are
interpreted with the help of the various existing models, and are compared with
numerical calculations based upon a two-level modelling that considers both a
closed and an open system.


title: Periodicity of ~155 days in solar electron fluence

abstract:
  In this paper we have investigated the occurrence rate of high energetic(E>10
MeV) solar electron flares measured by IMP-8 spacecraft of NASA for solar cycle
21 (June, 1976 to August, 1986) first time by three different methods to detect
periodicities accurately. Power-spectrum analysis confirms a periodicity ~155
days which is in consistent with the result of Chowdhury and Ray (2006), that
"Rieger periodicity" was operated throughout the cycle 21 and it is independent
on the energy of the electron fluxes.


title:
Correlated bosons on a lattice: Dynamical mean-field theory for
  Bose-Einstein condensed and normal phases

abstract:
  We formulate a bosonic dynamical mean-field theory (B-DMFT) which provides a
comprehensive, thermodynamically consistent framework for the theoretical
investigation of correlated lattice bosons. The B-DMFT is applicable for
arbitrary values of the coupling parameters and temperature and becomes exact
in the limit of high spatial dimensions d or coordination number Z of the
lattice. In contrast to its fermionic counterpart the construction of the
B-DMFT requires different scalings of the hopping amplitudes with Z depending
on whether the bosons are in their normal state or in the Bose-Einstein
condensate. A detailed discussion of how this conceptual problem can be
overcome by performing the scaling in the action rather than in the Hamiltonian
itself is presented. The B-DMFT treats normal and condensed bosons on equal
footing and thus includes the effects caused by their dynamic coupling. It
reproduces all previously investigated limits in parameter space such as the
Beliaev-Popov and Hartree-Fock-Bogoliubov approximations and generalizes the
existing mean-field theories of interacting bosons. The self-consistency
equations of the B-DMFT are those of a bosonic single-impurity coupled to two
reservoirs corresponding to bosons in the condensate and in the normal state,
respectively. We employ the B-DMFT to solve a model of itinerant and localized,
interacting bosons analytically. The local correlations are found to enhance
the condensate density and the Bose-Einstein condensate (BEC) transition
temperature T_{BEC}. This effect may be used experimentally to increase T_{BEC}
of bosonic atoms in optical lattices.


title:
Up-conversion injection in Rubrene/Perylene-diimide-heterostructure
  electroluminescent diodes

abstract:
  We implement and demonstrate a scheme that permits to drive
electroluminescence with an extremely low turn-on voltage. The device behaves
like compound semiconductors, in which the electroluminescence turn-on voltage
is about the same as the open circuit voltage for the photovoltaic effect.
However, the electroluminescence turn-on voltage is about half of the band gap
of the emitting material, that cannot be explained using current models of
charge injection in organic semiconductors. We hereby propose explanation
through an Auger-type two-step injection mechanism (Auger-fountain).


title:
Almost sure convergence of randomly truncated stochastic algorithms
  under verifiable conditions

abstract:
  We study the almost sure convergence of randomly truncated stochastic
algorithms. We present a new convergence theorem which extends the already
known results by making vanish the classical condition on the noise terms. The
aim of this work is to prove an almost sure convergence result of randomly
truncated stochastic algorithms under easily verifiable conditions


title:
Using quantum computing models for graviton communication/information
  processing in cosmological evolution

abstract:
  In 2001, Seth Lloyd presented a radical new critique of the universe as a
quantum computing device, with an upper limit of bit calculations of the order
of 10 to the 120 power. We find that his calculations permit us to reconcile
the existance of a huge cosmological constant 10 to the minus 43 seconds after
the big bang, with a resulting huge relic graviton flux, with the existance of
a CMBR observational barrier of z = 1100 years after the big bang. Lloyd's
calculations pre suppose the existence of a huge entropy value during the
nucleation of a new universe, a datum we think helps shed light on the
cosmological landscape problem.


title:
Maximal probabilities of convolution powers of discrete uniform
  distributions

abstract:
  We prove optimal constant over root $n$ upper bounds for the maximal
probabilities of $n$th convolution powers of discrete uniform distributions.


title: Two multivariate central limit theorems

abstract:
  In this paper, explicit error bounds are derived in the approximation of rank
$k$ projections of certain $n$-dimensional random vectors by standard
$k$-dimensional Gaussian random vectors. The bounds are given in terms of $k$,
$n$, and a basis of the $k$-dimensional space onto which we project. The random
vectors considered are two generalizations of the case of a vector with
independent, identically distributed components. In the first case, the random
vector has components which are independent but need not have the same
distribution. The second case deals with finite exchangeable sequences of
random variables.


title: Holomorphic Extension of CR Functions from Quadratic Cones

abstract:
  It is proved that CR functions on a quadratic cone M in $\C^n$, n>1, admit
one-sided holomorphic extension if and only if M does not have two-sided
support, a geometric condition on M which generalizes minimality in the sense
of Tumanov. A biholomorphic classification of quadratic cones in $\C^2$ is also
given.


title: Why does wurtzite form in nanowires of III-V zinc-blende semiconductors?

abstract:
  We develop a nucleation-based model to explain the formation of the wurtzite
(WZ) crystalline phase during the vapor-liquid-solid growth of free-standing
nanowires of zinc-blende (ZB) semiconductors. We first show that, in nanowires,
nucleation generally occurs at the outer edge of the solid/liquid interface
(the triple phase line) rather than elsewhere at the solid/liquid interface. In
the present case, this entails major differences between ZB and WZ nuclei.
Depending on the pertinent interface energies, WZ nucleation is favored at high
liquid supersaturation. This explains our systematic observation of ZB during
the early stages of nanowire growth.


title:
The ACS Survey of Galactic Globular Clusters. II. Stellar Evolution
  Tracks, Isochrones, Luminosity Functions, and Synthetic Horizontal-Branch
  Models

abstract:
  The ACS Survey of Galactic Globular Clusters, an HST Treasury Project, will
deliver high quality, homogeneous photometry of 65 globular clusters. This
paper introduces a new collection of stellar evolution tracks and isochrones
suitable for analyzing the ACS Survey data. Stellar evolution models were
computed at [Fe/H]= -2.5, -2.0, -1.5, -1.0, -0.5, and 0; [alpha/Fe]= -0.2, 0,
0.2, 0.4, 0.6, and 0.8; and three initial He abundances for masses from 0.1 to
1.8 Msun and ages from 2 to 15 Gyr. Each isochrone spans a wide range in
luminosity from Mv~14 up to the tip of the red giant branch. These are
complemented by a set of He-burning tracks that extend from the zero age
horizontal branch to the onset of thermal pulsations on the asymptotic giant
branch. In addition, a set of computer programs are provided that make it
possible to interpolate the isochrones in [Fe/H], generate luminosity functions
from the isochrones, and create synthetic horizontal branch models. The tracks
and isochrones have been converted to the observational plane with two
different color-Teff transformations, one synthetic and one semi-empirical, in
ground-based B, V, and I, and F606W and F814W for both ACS-WFC and WFPC2
systems. All models and programs presented in this paper are available from
http://stellar.dartmouth.edu/~models/


title:
Generation of different Bell states within the SPDC phase-matching
  bandwidth

abstract:
  We study the frequency-angular lineshape for a phase-matched nonlinear
process producing entangled states and show that there is a continuous variety
of maximally-entangled states generated for different mismatch values within
the natural bandwidth. Detailed considerations are made for two specific
methods of polarization entanglement preparation, based on type-II spontaneous
parametric down-conversion (SPDC) and on SPDC in two subsequent type-I crystals
producing orthogonally polarized photon pairs. It turns out that different Bell
states are produced at the center of the SPDC line and on its slopes,
corresponding to about half-maximum intensity level. These Bell states can be
filtered out by either frequency selection or angular selection, or both. Our
theoretical calculations are confirmed by a series of experiments, performed
for the two above-mentioned schemes of producing polarization-entangled photon
pairs and with two kinds of measurements: frequency-selective and
angular-selective.


title:
Imaging the Cosmic Matter Distribution using Gravitational Lensing of
  Pregalactic HI

abstract:
  21-cm emission from neutral hydrogen during and before the epoch of cosmic
reionisation is gravitationally lensed by material at all lower redshifts.
Low-frequency radio observations of this emission can be used to reconstruct
the projected mass distribution of foreground material, both light and dark. We
compare the potential imaging capabilities of such 21-cm lensing with those of
future galaxy lensing surveys. We use the Millennium Simulation to simulate
large-area maps of the lensing convergence with the noise, resolution and
redshift-weighting achievable with a variety of idealised observation
programmes. We find that the signal-to-noise of 21-cm lens maps can far exceed
that of any map made using galaxy lensing. If the irreducible noise limit can
be reached with a sufficiently large radio telescope, the projected convergence
map provides a high-fidelity image of the true matter distribution, allowing
the dark matter halos of individual galaxies to be viewed directly, and giving
a wealth of statistical and morphological information about the relative
distributions of mass and light. For instrumental designs like that planned for
the Square Kilometer Array (SKA), high-fidelity mass imaging may be possible
near the resolution limit of the core array of the telescope.


title: Unparticle phase effects

abstract:
  Unparticles proposed by Georgi carry CP conserving phases in their
propagators. We demonstrate that these peculiar phases have an important impact
on CP violation. Without including the strong QCD phases, we study the
unparticle phase effects on the direct CP asymmetries in the exclusive decays
of $\bar B_d\to \pi^{+} \pi^{-}$ and $B\to \pi K$, in which the flavor changing
neutral currents are forbidden at tree level but induced by one-loop diagrams.
Interesting and consistent results comparing to the data are obtained. In
addition, we find that unparticles will significantly enhance the differential
branching ratio of $b\to s \ell^{+} \ell^{-}$ at the small invariant mass of
$\ell^{+} \ell^{-}$. The forward-backward asymmetries for $b\to s \ell^{+}
\ell^{-}$ due to unparticles are also explored.


title: Electroweak measurements at the Tevatron

abstract:
  The increasing size of the data samples recorded by the CDF and DO
experiments at the Tevatron enables studies of a wide range of processes
involving the electroweak bosons W and Z. Single boson production is now looked
at in terms of differential cross sections such as rapidity or transverse
momentum dependence. Diboson production cross-sections are several orders of
magnitude smaller than single boson production cross-sections, but all
combinations Wgamma, Zgamma, WW and WZ have been observed. ZZ production is
expected at a rate just below the observation threshold with current data
sample sizes, but this channel is expected to be accessible to the Tevatron
experiments soon.


title: Searches for Particle Dark Matter with the GLAST Large Area Telescope

abstract:
  The Large Area Telescope (LAT), one of two instruments on the Gamma-ray Large
Area Space Telescope (GLAST) mission, scheduled for launch by NASA in 2007, is
an imaging, wide field-of-view, high-energy gamma-ray telescope, covering the
approximate energy range from 20 MeV to more than 300 GeV. Annihilation of
Weakly Interacting Massive Particles (WIMP), predicted in many extensions of
the Standard Model of Particle Physics, may give rise to a signal in gamma-ray
spectra from many cosmic sources. In this contribution we give an overview of
the searches for WIMP Dark Matter performed by the GLAST-LAT collaboration.


title:
Controlling the polarisation correlation of photon pairs from a
  charge-tuneable quantum dot

abstract:
  Correlation between the rectilinear polarisations of the photons emitted from
the biexciton decay in a single quantum dot is investigated in a device which
allows the charge-state of the dot to be controlled. Optimising emission from
the neutral exciton states maximises the operating efficiency of the biexciton
decay. This is important for single dot applications such as a triggered source
of entangled photons. As the bias on the device is reduced correlation between
the two photons is found to fall dramatically as emission from the negatively
charged exciton becomes significant. Lifetime measurements demonstrate that
electronic spin-scattering is the likely cause.


title:
On the zero set of the Kobayashi--Royden pseudometric of the spectral
  unit ball

abstract:
  Given $A\in\Omega_n,$ the $n^2$-dimensional spectral unit ball, we show that
$B$ is a "generalized" tangent vector at $A$ to an entire curve in $\Omega_n$
if and only if $B$ is in the tangent cone $C_A$ to the isospectral variety at
$A.$ In the case of $\Omega_3,$ the zero set of this metric is completely
described.


title: On the Boltzmann Equation for Weakly Nonlinear Wave Equations

abstract:
  We explain how the kinetic theory of L. Boltzmann is applied to weakly
nonlinear wave equations.


title: Is the Concentration of Dark Matter Halos at Virialization Universal ?

abstract:
  Several recent studies suggest a correlation between dark matter halo mass
and the shape of the density profile. We re-analyze simulations from Ricotti
(2003) in which such a correlation was proposed. We use a standard analysis of
the halo density profiles and compare the old simulations to new ones performed
with Gadget2, including higher resolution runs. We confirm Ricotti's result
that, at virialization, the central log slopes alpha, at 5%-10% of the virial
radius are correlated with the halo mass and that the halo concentration is a
universal constant. Our results do not contradict the majority of published
papers: when using a split power law to fit the density profiles, due to the
alpha-concentration degeneracy, the fits are consistent with halos having a
universal shape with alpha=1 or 1.5 and concentrations that depend on the mass,
in agreement with results published elsewhere.
  Recently, several groups have found no evidence for convergence of the inner
halo profile to a constant power law. The choice of a split power law
parameterization used in this letter is motivated by the need to compare our
results to previous ones and is formally valid because we are not able to
resolve regions where the slope of the fitting function reaches its asymptotic
constant value. Using a non-parameterized technique, we also show that the
density profiles of dwarf galaxies at z ~ 10 have a log slope shallower than
0.5 within 5% of the virial radius.


title: Stealth Acceleration and Modified Gravity

abstract:
  We show how to construct consistent braneworld models which exhibit late time
acceleration. Unlike self-acceleration, which has a de Sitter vacuum state, our
models have the standard Minkowski vacuum and accelerate only in the presence
of matter, which we dub ``stealth-acceleration''. We use an effective action
for the brane which includes an induced gravity term, and allow for an
asymmetric set-up. We study the linear stability of flat brane vacua and find
the regions of parameter space where the set-up is stable. The 4-dimensional
graviton is only quasi-localised in this set-up and as a result gravity is
modified at late times. One of the two regions is strongly coupled and the
scalar mode is eaten up by an extra symmetry that arises in this limit. Having
filtered the well-defined theories we then focus on their cosmology. When the
graviton is quasi-localised we find two main examples of acceleration. In each
case, we provide an illustrative model and compare it to LambdaCDM.


title: Two-photon coherent polarization flipping of confined excitons

abstract:
  A two-photon process leading to coherent transitions between the two
circularly polarized exciton states in a quantum dot is studied. It is shown
that optical flipping of the exciton polarization is possible with picosecond
laser pulses. The process is closely related to two-photon Rabi oscillations of
a biexciton but it is much more stable against shifts of the laser frequency.


title:
Profinite complexes of curves, their automorphisms and anabelian
  properties of moduli stacks of curves

abstract:
  Let ${\cal M}_{g,[n]}$, for $2g-2+n>0$, be the D-M moduli stack of smooth
curves of genus $g$ labeled by $n$ unordered distinct points. The main result
of the paper is that a finite, connected \'etale cover ${\cal M}^\l$ of ${\cal
M}_{g,[n]}$, defined over a sub-$p$-adic field $k$, is "almost" anabelian in
the sense conjectured by Grothendieck for curves and their moduli spaces.
  The precise result is the following. Let $\pi_1({\cal M}^\l_{\ol{k}})$ be the
geometric algebraic fundamental group of ${\cal M}^\l$ and let
${Out}^*(\pi_1({\cal M}^\l_{\ol{k}}))$ be the group of its exterior
automorphisms which preserve the conjugacy classes of elements corresponding to
simple loops around the Deligne-Mumford boundary of ${\cal M}^\l$ (this is the
"$\ast$-condition" motivating the "almost" above). Let us denote by
${Out}^*_{G_k}(\pi_1({\cal M}^\l_{\ol{k}}))$ the subgroup consisting of
elements which commute with the natural action of the absolute Galois group
$G_k$ of $k$. Let us assume, moreover, that the generic point of the D-M stack
${\cal M}^\l$ has a trivial automorphisms group. Then, there is a natural
isomorphism: $${Aut}_k({\cal M}^\l)\cong{Out}^*_{G_k}(\pi_1({\cal
M}^\l_{\ol{k}})).$$ This partially extends to moduli spaces of curves the
anabelian properties proved by Mochizuki for hyperbolic curves over
sub-$p$-adic fields.


title: Non SUSY Searches at the Tevatron

abstract:
  Recent searches for non-SUSY exotics in $p\bar{p}$ collisions at a
center-of-mass energy of 1.96 TeV at the Tevatron Run II are reported. The
emphasis is put on the results of model-driven analyses which were updated to
the full Run IIA datasets corresponding to integrated luminosities of about 1
$fb^{-1}$.


title: Four wave mixing spectroscopy of quantum dot molecules

abstract:
  We study theoretically the nonlinear four wave mixing (FWM) response of an
ensemble of coupled pairs of quantum dots (quantum dot molecules). We discuss
the shape of the FWM echo signal depending on the parameters of the ensemble:
the statistics of transition energies and the degree of size correlations
between the dots forming the molecules.


title: Phonon-assisted excitation transfer in quantum dot molecules

abstract:
  We derive a quantum-kinetic description of phonon-assisted F{\"o}rster
transfer between two coupled quantum dots (a quantum dot molecule). We show
that the exciton state decays to the ground state of the QDM via a combination
of the Rabi rotation and exponential decay. For moderately spaced dots this
process takes place on a picosecond time scale.


title: First principles study of magnetism in nanographenes

abstract:
  Magnetism in nanographenes (also know as polycyclic aromatic hydrocarbons, or
PAHs) are studied with first principles density functional calculations. We
find that an antiferromagnetic (AFM) phase appears as the PAH reaches a certain
size. This AFM phase in PAHs has the same origin as the one in infinitely long
zigzag-edged graphene nanoribbons, namely, from the localized electronic state
at the zigzag edge. The smallest PAH still having an AFM ground state is
identified. With increased length of the zigzag edge, PAHs approach an
infinitely long ribbon in terms of (1) the energetic ordering and difference
among the AFM, ferromagnetic (FM), and nonmagnetic (NM) phases and (2) the
average local magnetic moment at the zigzag edges. These PAHs serve as ideal
targets for chemical synthesis of nanographenes that possess magnetic
properties. Moreover, our calculations support the interpretation that
experimentally observed magnetism in activated carbon fibers originates from
the zigzag edges of the nanographenes.


title: Bondi accretion in the early universe

abstract:
  This paper presents a study of quasi-steady spherical accretion in the early
Universe, before the formation of the first stars and galaxies. The main
motivation is to derive the basic formulas that will be used in a companion
paper to calculate the accretion luminosity of primordial black holes and their
effect on the cosmic ionization history.
  The following cosmological effects are investigated: the coupling of the gas
to the CMB photon fluid (i.e., Compton drag), Hubble expansion, and the growth
of the dark matter halo seeded by the gravitational potential of the central
point mass. The gas equations of motion are solved assuming either a polytropic
or an isothermal equation of state. We consider the cases in which the
accreting object is a point mass or a spherical dark matter halo with power-law
density profile, as predicted by the theory of "secondary infall''. Analytical
solutions for the sonic radius and fitting formulas for the accretion rate are
provided.
  Different accretion regimes exist depending on the mass of the accreting
object. If the black hole mass is smaller than 50-100 Msun, gas accretion is
unaffected by Compton drag. A point mass and an extended dark halo of equal
mass accrete at the same rate if M>5000 Msun, while smaller mass dark halos
accrete less efficiently than the equivalent point mass. For masses M>3 x 10^4
Msun, the viscous term due to the Hubble expansion becomes important and the
assumption of quasi-steady flow fails. Hence, the steady Bondi solutions
transition to the time-dependent self-similar solutions for "cold cosmological
infall".


title: Skyrmions in the presence of isospin chemical potential

abstract:
  We analyze the existence of localized finite energy topological excitations
on top of the perturbative pion vacuum within the Skyrme model at finite
isospin chemical potential and finite pion mass. We show that there is a
critical isospin chemical potential $\mu_I^c$ above which such solutions cease
to exist. We find that $\mu_I^c$ is closely related to the value of the pion
mass. In particular for vanishing pion mass we obtain $\mu_I^c=0$ in
contradiction with some results recently reported in the literature. We also
find that below $\mui^c$ the skyrmion mass and baryon radius show, at least for
the case of the hedgehog ansatz, only a mild dependence on the isospin chemical
potential.


title: Coherent spin transport through a 350-micron-thick Silicon wafer

abstract:
  We use all-electrical methods to inject, transport, and detect spin-polarized
electrons vertically through a 350-micron-thick undoped single-crystal silicon
wafer. Spin precession measurements in a perpendicular magnetic field at
different accelerating electric fields reveal high spin coherence with at least
13pi precession angles. The magnetic-field spacing of precession extrema are
used to determine the injector-to-detector electron transit time. These transit
time values are associated with output magnetocurrent changes (from in-plane
spin-valve measurements), which are proportional to final spin polarization.
Fitting the results to a simple exponential spin-decay model yields a
conduction electron spin lifetime (T1) lower bound in silicon of over 500ns at
60K.


title: Imaging the Surface of Altair

abstract:
  Spatially resolving the surfaces of nearby stars promises to advance our
knowledge of stellar physics. Using optical long-baseline interferometry, we
present here a near-infrared image of the rapidly rotating hot star Altair with
<1 milliarcsecond resolution. The image clearly reveals the strong effect of
gravity darkening on the highly-distorted stellar photosphere. Standard models
for a uniformly rotating star can not explain our results, requiring
differential rotation, alternative gravity darkening laws, or both.


title: Simulation of time evolution with the MERA

abstract:
  We describe an algorithm to simulate time evolution using the Multi-scale
Entanglement Renormalization Ansatz (MERA) and test it by studying a critical
Ising chain with periodic boundary conditions and with up to L ~ 10^6 quantum
spins. The cost of a simulation, which scales as L log(L), is reduced to log(L)
when the system is invariant under translations. By simulating an evolution in
imaginary time, we compute the ground state of the system. The errors in the
ground state energy display no evident dependence on the system size. The
algorithm can be extended to lattice systems in higher spatial dimensions.


title: Position Coding

abstract:
  A position coding pattern is an array of symbols in which subarrays of a
certain fixed size appear at most once. So, each subarray uniquely identifies a
location in the larger array, which means there is a bijection of some sort
from this set of subarrays to a set of coordinates. The key to Fly Pentop
Computer paper and other examples of position codes is a method to read the
subarray and then convert it to coordinates. Position coding makes use of ideas
from discrete mathematics and number theory. In this paper, we will describe
the underlying mathematics of two position codes, one being the Anoto code that
is the basis of "Fly paper". Then, we will present two new codes, one which
uses binary wavelets as part of the bijection.


title: Inferring the Composition of a Trader Population in a Financial Market

abstract:
  We discuss a method for predicting financial movements and finding pockets of
predictability in the price-series, which is built around inferring the
heterogeneity of trading strategies in a multi-agent trader population. This
work explores extensions to our previous framework (arXiv:physics/0506134).
Here we allow for more intelligent agents possessing a richer strategy set, and
we no longer constrain the estimate for the heterogeneity of the agents to a
probability space. We also introduce a scheme which allows the incorporation of
models with a wide variety of agent types, and discuss a mechanism for the
removal of bias from relevant parameters.


title: Experimental Realization of Quantum-Resonance Ratchets

abstract:
  Quantum-resonance ratchets associated with the periodically kicked particle
are experimentally realized for the first time. This is achieved by using a
Bose-Einstein condensate exposed to a pulsed standing light wave and prepared
in an initial state differing from the usual plane wave. Both the standing-wave
potential and the initial state have a point symmetry around some center and
the ratchet arises from the non-coincidence of the two centers. The dependence
of the directed quantum transport on the quasimomentum is studied. A detailed
theoretical analysis is used to explain the experimental results.


title:
Classical simulability and the significance of modular exponentiation in
  Shor's algorithm

abstract:
  We show that a classical algorithm efficiently simulating the modular
exponentiation circuit, for certain product state input and with measurements
in a general product state basis at the output, can efficiently simulate Shor's
factoring algorithm. This is done by using the notion of the semi-classical
Fourier transform due to Griffith and Niu, and further discussed in the context
of Shor's algorithm by Browne.


title: Shape derivative of the first eigenvalue of the 1-Laplacian

abstract:
  We compute the shape derivative of the first eigenvalue of the 1-Laplacian.
As an application, we find that a ball is critical among all volume-preserving
deformations.


title:
Enhanced optical communication and broadband sub-shot-noise
  interferometry with a stable free-running periodically-poled-KTiOPO4 squeezer

abstract:
  An intrinsically stable type-I optical parametric oscillator was built with a
periodically poled KTiOPO4 (PPKTP) crystal to generate a stable bright,
continuous-wave, broadband phase-squeezed beam. A 3.2 dB sensitivity
enhancement of optical interferometry was demonstrated on weak electrooptic
modulation signals within a 20 MHz squeezing bandwidth. This also realized a
channel capacity increase beyond that of coherent optical communication.


title: MOND and the mass discrepancies in tidal dwarf galaxies

abstract:
  I consider in light of MOND the three debris galaxies discussed recently by
Bournaud et al.. These exhibit mass discrepancies of a factor of a few within
several scale lengths of the visible galaxy, which, arguably, flies in the face
of the cold dark matter paradigm. I show here that the rotational velocities
predicted by MOND agree well with the observed velocities for each of the three
galaxies, with only the observed baryonic matter as the source of gravity.
There is thus no need to invoke a new form of baryonic, yet-undetected matter
that dominates the disc of spiral galaxies, as advocated by Bournaud et al. I
argue on other grounds that the presence of such ubiquitous disc dark matter,
in addition to cold dark matter, is not likely.


title:
Schrodinger equations and Hamiltonian systems of PDEs with selfdual
  boundary conditions

abstract:
  Selfdual variational calculus is further refined and used to address
questions of existence of local and global solutions for various parabolic
semi-linear equations, Hamiltonian systems of PDEs, as well as certain
nonlinear Schrodinger evolutions. This allows for the resolution of such
equations under general time boundary conditions which include the more
traditional ones such as initial value problems, periodic and anti-periodic
orbits, but also yield new ones such as "periodic orbits up to an isometry" for
evolution equations that may not have periodic solutions. In the process, we
introduce a method for perturbing selfdual functionals in order to induce
coercivity and compactness, while keeping the system selfdual.


title:
Chandra Observations of the Gamma-ray Binary LSI+61303: Extended X-ray
  Structure?

abstract:
  We present a 50 ks observation of the gamma-ray binary LSI+61303 carried out
with the ACIS-I array aboard the Chandra X-ray Observatory. This is the highest
resolution X-ray observation of the source conducted so far. Possible evidence
of an extended structure at a distance between 5 and 12 arcsec towards the
North of LSI+61303 have been found at a significance level of 3.2 sigma. The
asymmetry of the extended emission excludes an interpretation in the context of
a dust-scattered halo, suggesting an intrinsic nature. On the other hand, while
the obtained source flux, of F_{0.3-10 keV}=7.1^{+1.8}_{-1.4} x 10^{-12}
ergs/cm^2/s, and hydrogen column density, N_{H}=0.70+/-0.06 x 10^{22} cm^{-2},
are compatible with previous results, the photon index Gamma=1.25+/-0.09 is the
hardest ever found. In light of these new results, we briefly discuss the
physics behind the X-ray emission, the location of the emitter, and the
possible origin of the extended emission ~0.1 pc away from LSI+61303.


title:
On the spectrum of the twisted Dolbeault Laplacian over K\"ahler
  manifolds

abstract:
  We use Dirac operator techniques to a establish sharp lower bound for the
first eigenvalue of the Dolbeault Laplacian twisted by Hermitian-Einstein
connections on vector bundles of negative degree over compact K\"ahler
manifolds.


title: On the optimality of Stein factors

abstract:
  The application of Stein's method for distributional approximation often
involves so called Stein factors (also called 'magic factors') in the bound of
the solutions to Stein equations. However, in some cases these factors contain
additional (undesirable) logarithmic terms. It has been shown for many Stein
factors that the known bounds are sharp and thus that these additional
logarithmic terms cannot be avoided in general. However, no probabilistic
examples have appeared in the literature that would show that these terms in
the Stein factors are not just unavoidable artefacts, but that they are there
for a good reason. In this article we close this gap by constructing such
examples. This also leads to a new interpretation of the solutions to Stein
equations.


title: On the X-Ray emission of Gamma Ray Bursts

abstract:
  Recent data gathered and triggered by the SWIFT satellite have greatly
improved our knowledge of long-duration gamma ray bursts (GRBs) and X-ray
flashes (XRFs). This is particularly the case for the X-ray data at all times.
We show that the entire X-ray observations are in excellent agreement with the
predictions of the `cannonball' model of GRBs and XRFs, which are based on
simple physics and were published long before the launch of SWIFT. Two
mechanisms underlie these predictions: inverse Compton scattering and
synchrotron radiation, generally dominant at early and late times,
respectively. The former mechanism provides a unified description of the
gamma-ray peaks, X-ray flares and even the optical `humps' seen in some
favourable cases; i.e. their very different durations, fluxes and peak-times
are related precisely as predicted. The observed smooth or bumpy fast decay of
the X-ray light curve is correctly described case-by-case, in minute detail.
The `canonical' X-ray plateau, as well as the subsequent gradual steepening of
the afterglow to an asymptotic power-law decay, are as foretold. So are the
chromatic and achromatic properties of the light-curves.


title:
Adaptive Optimal Nonparametric Regression and Density Estimation Based
  on Fourier-Legendre Expansion

abstract:
  Motivated by finance and technical applications, the objective of this paper
is to consider adaptive estimation of regression and density distribution based
on Fourier-Legendre expansion, and construction of confidence intervals - also
adaptive. The estimators are asymptotically optimal and adaptive in the sense
that they can adapt to unknown smoothness.


title: Measuring 10-1000 GeV Cosmic Ray Electrons with GLAST/LAT

abstract:
  We present here the capabilities of the GLAST Large Area Telescope to detect
cosmic ray high-energy (HE) electrons in the energy range from 10 GeV to 1 TeV.
We also discuss the science topics that can be investigated with HE electron
data and quantify the results with LAT instrument simulations. The science
topics include CR propagation, calibration of the IC gamma-ray model, testing
hypotheses regarding the origin of HE energy cosmic-ray electrons, searching
for any signature of Kaluza Klein Dark Matter annihilation, and measuring the
HE electron anisotropy. We expect to detect ~ 107 electrons above 20 GeV per
year of LAT operation.


title: Survey on eigenvalues of the Dirac operator and geometric structures

abstract:
  We give a survey of results relating the restricted holonomy of a Riemannian
spin manifold with lower bounds on the spectrum of its Dirac operator, giving a
new proof of a result originally due to Kirchberg.


title: A Yangian Double for the AdS/CFT Classical r-matrix

abstract:
  We express the classical r-matrix of AdS/CFT in terms of tensor products
involving an infinite family of generators, which takes a form suggestive of
the universal expression obtained from a Yangian double. This should provide an
insight into the structure of the infinite dimensional symmetry algebra
underlying the integrability of the model, and give a clue to the construction
of its universal R-matrix. We derive the commutation relations under which the
algebra of these new generators close.


title: Validity of the Adiabatic Approximation

abstract:
  We analyze the validity of the adiabatic approximation, and in particular the
reliability of what has been called the "standard criterion" for validity of
this approximation. Recently, this criterion has been found to be insufficient.
We will argue that the criterion is sufficient only when it agrees with the
intuitive notion of slowness of evolution of the Hamiltonian. However, it can
be insufficient in cases where the Hamiltonian varies rapidly but only by a
small amount. We also emphasize the distinction between the adiabatic {\em
theorem} and the adiabatic {\em approximation}, two quite different although
closely related ideas.


title: Stability of Localized Patterns in Neural Fields

abstract:
  We investigate two-dimensional neural fields as a model of the dynamics of
macroscopic activations in a cortex-like neural system. While the
one-dimensional case has been treated comprehensively by Amari 30 years ago,
two-dimensional neural fields are much less understood. We derive conditions
for the stability for the main classes of localized solutions of the neural
field equation and study their behavior beyond parameter-controlled
destabilization. We show that a slight modification of original model yields an
equation whose stationary states are guaranteed to satisfy the original problem
and numerically demonstrate that it admits localized non-circular solutions.
Generically, however, only periodic spatial tessellations emerge upon
destabilization of rotationally-invariant solutions.


title: Outbursts of EX Hydrae Revisited

abstract:
  We present optical spectroscopy of EX Hya during its 1991 outburst. This
outburst is characterised by strong irradiation of the front face of the
secondary star by the white dwarf, an overflowing stream which is seen strongly
in HeII and by a dip in the light curves, which extends from 0.1-0.6 in the
binary and spin phases. Strong irradiation of the accretion curtain and that of
the inner regions of the disc led to strong emission of HeII and to the
suppression of the Hg and Hb emission.
  Disc overflow was observed in quiescence in earlier studies, where the
overflow stream material was modulated at high velocities close to 1000 km/s.
In outburst, the overflowing material is modulated at even higher velocities
(~1500 km/s). These are streaming velocities down the field lines close to the
white dwarf. Evidence for material collecting near the outer edge of the disc
and corotating with the accretion curtain was observed. In decline, this
material and the accretion curtain obscured almost all the emission near binary
phase 0.4, causing a dip. The dip minimum nearly corresponds with spin pulse
minimum. This has provided additional evidence for an extended accretion
curtain, and for the corotation of material with the accretion curtain at the
outer edge of the disc. From these observations we suggest that a mechanism
similar to that of Spruit & Taam, where outbursts result due to the storage and
release of matter outside the magnetosphere, triggers the outbursts of EX Hya.
This is followed by the irradiation of the secondary star due to accretion
induced radiation.


title:
Some remarks on the generalized Tanaka-Webster connection of a contact
  metric manifold

abstract:
  We find necessary and sufficient conditions for the bi-Legendrian connection
$\nabla$ associated to a bi-Legendrian structure $(\cal F,\cal G)$ on a contact
metric manifold $(M,\phi,\xi,\eta,g)$ being a metric connection and then we
give conditions ensuring that $\nabla$ coincides with the (generalized)
Tanaka-Webster connection of $(M,\phi,\xi,\eta,g)$. Using these results, we
give some interpretations of the Tanaka-Webster connection and we study the
interactions between the Tanaka-Webster, the bi-Legendrian and the Levi Civita
connection in a Sasakian manifold.


title: Expected gaps between prime numbers

abstract:
  We study the gaps between consecutive prime numbers directly through
Eratosthenes sieve. Using elementary methods, we identify a recursive relation
for these gaps and for specific sequences of consecutive gaps, known as
constellations. Using this recursion we can estimate the numbers of a gap or of
a constellation that occur between a prime and its square. This recursion also
has explicit implications for open questions about gaps between prime numbers,
including three questions posed by Erd\"os and Tur\'an.


title: Holographic Mixing Quantified

abstract:
  We compute the precise elementary/composite field content of mass eigenstates
in holographic duals of warped models in a slice of AdS_5. This is accomplished
by decomposing the bulk fields not in the usual Kaluza-Klein basis, but rather
into a holographic basis of 4D fields, corresponding to purely elementary
source or CFT composite fields. Generically, this decomposition yields kinetic
and mass mixing between the elementary and composite sectors of the holographic
theory. Depending on where the bulk zero mode is localized, the
elementary/composite content may differ radically, which we show explicitly for
several examples including the bulk Randall-Sundrum graviton, bulk gauge boson,
and Higgs boson.


title: Recent UBVJH Photometry of Epsilon Aurigae

abstract:
  Since first observed in the early 1980s, the Hopkins Phoenix Observatory
continues its UBV band observations of the long period (27.1 years) eclipsing
binary star system epsilon Aurigae. The UBV observations routinely produce
standard deviations or data spread better than 0.01 magnitudes many times
approaching 0.001 magnitudes. A new infrared photometer has allowed the
addition of near-infrared observations for the JH bands. Typical near-infrared
observations approach a standard deviation of data spread of 0.01 magnitudes.
The 2003 - 2005 seasons (Fall through Spring) of epsilon Aurigae observations
showed a 66.2 day variation that gradually increases in average and peak
magnitude in the UBV bands. The 2006 season (Fall 2006 to Spring 2007) data
show what appears to be a fall-back to a quiet period near maximum amplitude of
V= 3.00. This paper presents the data and compares the current season to the
past several seasons. The next eclipse is predicted to begin in 2009 and an
international campaign has been organized to coordinate new observations. These
website links are: [http://www. hposoft.com/Campaign09.html ] and [
http://www.du.edu/~rstencel/epsaur.htm ] .


title: Upsilon measurement in STAR

abstract:
  We present preliminary results of Upsilon production in p+p collisions at
sqrt(s)=200 GeV at central rapidity. This measurement was performed at the STAR
experiment through the Upsilon->e^+e^- decay channel. In this manuscript we
describe the experimental details, from the development of a specially designed
trigger setup to the analysis methods used to discriminate electrons from
hadrons. The production cross-section obtained B*{(dsigma/dy)|(y=0)}=91(28)(22)
pb is compatible with our expectations based on pQCD calculations.


title: Clustering of Lyman alpha emitters at z ~ 4.5

abstract:
  We present the clustering properties of 151 Lyman alpha emitting galaxies at
z ~ 4.5 selected from the Large Area Lyman Alpha (LALA) survey. Our catalog
covers an area of 36' x 36' observed with five narrowband filters. We assume
that the angular correlation function w(theta) is well represented by a power
law A_w = Theta^(-beta) with slope beta = 0.8, and we find A_w = 6.73 +/- 1.80.
We then calculate the correlation length r_0 of the real-space two-point
correlation function xi(r) = (r/r_0)^(-1.8) from A_w through the Limber
transformation, assuming a flat, Lambda-dominated universe. Neglecting
contamination, we find r_0 = 3.20 +/- 0.42 Mpc/h. Taking into account a
possible 28% contamination by randomly distributed sources, we find r_0 = 4.61
+/- 0.6 Mpc/h. We compare these results with the expectations for the
clustering of dark matter halos at this redshift in a Cold Dark Matter model,
and find that the measured clustering strength can be reproduced if these
objects reside in halos with a minimum mass of 1-2 times 10^11 Solar masses/h.
Our estimated correlation length implies a bias of b ~ 3.7, similar to that of
Lyman-break galaxies (LBG) at z ~ 3.8-4.9. However, Lyman alpha emitters are a
factor of ~ 2-16 rarer than LBGs with a similar bias value and implied host
halo mass. Therefore, one plausible scenario seems to be that Lyman alpha
emitters occupy host halos of roughly the same mass as LBGs, but shine with a
relatively low duty cycle of 6-50%.


title:
Transverse coincidence-structures in spontaneous parametric
  down-conversion with orbital angular momentum: Theory

abstract:
  Coincidence-structures in the transverse plane of Type-II spontaneous
parametric down-conversion carrying orbital angular momentum are obtained.
Azimuthal symmetry breaking around the pump beam direction reveals itself on
these quantum images. Analytical expressions for the amplitude probability of
the down conversion process are shown including the nonlinear polarizability
components.


title:
Radiative Transfer Effect on Ultraviolet Pumping of the 21cm Line in the
  High Redshift Universe

abstract:
  During the epoch of reionization the 21cm signal is sensitive to the
scattering rate of the ultraviolet photons, redshifting across the Lyman_alpha
resonance. Here we calculate the photon scattering rate profile for a single
ultraviolet source. After taking into account previously neglected natural
broadening of the resonance line, we find that photons approach the resonance
frequency and experience most scatterings at a significantly smaller distance
from the source than naively expected r=(dnu/nu_0)(c/H), where dnu=nu-nu_0 is
the initial frequency offset, and the discrepancy increases as the initial
frequency offset decreases. As a consequence, the scattering rate P(r) drops
much faster with increasing distance than the previously assumed 1/r^2 profile.
Near the source (r<1Mpc comoving), the scattering rate of photons that redshift
into the Ly_alpha resonance converges to P(r) \propto r^{-7/3}. The scattering
rate of Ly_alpha photons produced by splitting of photons that redshift into a
higher resonance (Ly_gamma, Ly_delta, etc.) is only weakly affected by the
radiative transfer, while the sum of scattering rates of Ly_alpha photons
produced from all higher resonances also converges to P(r) \propto r^{-7/3}
near the source. At 15<z<35, on scales of ~0.01-20Mpc/h (comoving), the total
scattering rate of Ly_alpha photons from all Lyman resonances is found to be
higher by a factor of ~1+0.3[(1+z)/20]^{2/3} than obtained without full
radiative transfer. Consequently, during the early stage of reionization, the
differential brightness of 21cm signal against the cosmic microwave background
is also boosted by a similar factor.


title: Constraining Warm Dark Matter using QSO gravitational lensing

abstract:
  Warm Dark Matter (WDM) has been invoked to resolve apparent conflicts of Cold
Dark Matter (CDM) models with observations on subgalactic scales. In this work
we provide a new and independent lower limit for the WDM particle mass (e.g.
sterile neutrino) through the analysis of image fluxes in gravitationally
lensed QSOs.
  Starting from a theoretical unperturbed cusp configuration we analyze the
effects of intergalactic haloes in modifying the fluxes of QSO multiple images,
giving rise to the so-called anomalous flux ratio. We found that the global
effect of such haloes strongly depends on their mass/abundance ratio and it is
maximized for haloes in the mass range $10^6-10^8 \Msun$.
  This result opens up a new possibility to constrain CDM predictions on small
scales and test different warm candidates, since free streaming of warm dark
matter particles can considerably dampen the matter power spectrum in this mass
range. As a consequence, while a ($\Lambda$)CDM model is able to produce flux
anomalies at a level similar to those observed, a WDM model, with an
insufficiently massive particle, fails to reproduce the observational
evidences.
  Our analysis suggests a lower limit of a few keV ($m_{\nu} \sim 10$) for the
mass of warm dark matter candidates in the form of a sterile neutrino. This
result makes sterile neutrino Warm Dark Matter less attractive as an
alternative to Cold Dark Matter, in good agreement with previous findings from
Lyman-$\alpha$ forest and Cosmic Microwave Background analysis.


title: Exact relativistic beta decay endpoint spectrum

abstract:
  The exact relativistic form for the beta decay endpoint spectrum is derived
and presented in a simple factorized form. We show that our exact formula can
be well approximated to yield the endpoint form used in the fit method of the
KATRIN collaboration. We also discuss the three neutrino case and how
information from neutrino oscillation experiments may be useful in analyzing
future beta decay endpoint experiments.


title:
Lensing, reddening and extinction effects of MgII absorbers from z=0.4
  to z=2

abstract:
  Using a sample of almost 7000 strong MgII absorbers with 0.4 < z < 2.2
detected in the SDSS DR4 dataset, we investigate the gravitational lensing and
dust extinction effects they induce on background quasars. After carefully
quantifying several selection biases, we isolate the reddening effects as a
function of redshift and absorber rest equivalent width, W_0. We find the
amount of dust to increase with cosmic time as (1+z)^(-1.1 +/- 0.4), following
the evolution of cosmic star density or integrated star formation rate. We
measure the reddening effects over a factor 30 in E(B-V) and we find the dust
column density to be proportional to W_0^(1.9 +/- 0.2), which provides an
important scaling for theoretical modeling of metal absorbers. We also measure
the dust-to-metals ratio and find it similar to that of the Milky Way.
  In contrast to previous studies, we do not detect any gravitational
magnification by MgII systems. We measure the upper limit \mu<1.10 and discuss
the origin of the discrepancy. Finally, we estimate the fraction of absorbers
missed due to extinction effects and show that it rises from 1 to 50% in the
range 1<W_0<6 Angstrom. We parametrize this effect and provide a correction for
recovering the intrinsic distribution of absorber rest equivalent widths.


title: High Sensitivity Array Observations of the $z = 4.4$ QSO BRI 1335-0417

abstract:
  We present sensitive phase-referenced VLBI results on the radio continuum
emission from the $z=4.4$ QSO BRI 1335--0417. The observations were carried out
at 1.4 GHz using the High Sensitivity Array (HSA). Our sensitive VLBI image at
$189 \times 113$ mas ($1.25 \times 0.75$ kpc) resolution shows continuum
emission in BRI 1335--0417 with a total flux density of $208 \pm 46 \mu$Jy,
consistent with the flux density measured with the VLA. The size of the source
at FWHM is $255 \times 138$ mas ($1.7 \times 0.9$ kpc) and the derived
intrinsic brightness temperature is $\sim 3.5\times 10^4$ K. No continuum
emission is detected at the full VLBI resolution ($32 \times 7$ mas, $211
\times 46$ pc), with a 4$\sigma$ point source upper limit of 34 $\mu$Jy
beam$^{-1}$, or an upper limit to the intrinsic brightness temperature of
$5.6\times 10^5$ K. The highest angular resolution with at least a 4.5$\sigma$
detection of the radio continuum emission is $53 \times 27$ mas ($0.35 \times
0.18$ kpc). At this resolution, the image shows a continuum feature in BRI
1335--0417 with a size of $64 \times 35$ mas ($0.42 \times 0.23$ kpc) at FWHM,
and intrinsic brightness temperature of $\sim 2\times 10^5$ K. The extent of
the observed continuum sources at 1.4 GHz and the derived brightness
temperatures show that the radio emission (and thus presumably the far-infrared
emission) in BRI 1335--0417 is powered by a major starburst, with a massive
star formation rate of order a few thousand M_{\odot} {\rm yr}^{-1}$. Moreover,
the absence of any compact high-brightness temperature source suggests that
there is no radio-loud AGN in this $z=4.4$ QSO.


title: Constraining white-dwarf kicks in globular clusters

abstract:
  The wind of an asymptotic-giant-branch stars is sufficiently strong that if
it is slightly asymmetric, it can propel the star outside of the open cluster
of its birth or significantly alter its trajectory through a globular cluster;
therefore, if these stellar winds are asymmetric, one would expect a deficit of
white dwarfs of all ages in open clusters and for young white dwarfs to be less
radially concentrated than either their progenitors or older white dwarfs in
globular clusters. This latter effect has recently been observed. Hence,
detailed studies of the radial distribution of young white dwarfs in globular
clusters could provide a unique probe of mass loss on the asymptotic giant
branch and during the formation of planetary nebulae both as a function of
metallicity and a limited range of stellar mass.


title: The Ultraluminous X-ray Sources near the Center of M82

abstract:
  We report the identification of a recurrent ultraluminous X-ray source (ULX),
a highly absorbed X-ray source (possibly a background AGN), and a young
supernova remnant near the center of the starburst galaxy M82. From a series of
Chandra observations taken from 1999 to 2005, we found that the transient ULX
first appeared in 1999 October. The source turned off in 2000 January, but
later reappeared and has been active since then. The X-ray luminosity of this
source varies from below the detection level (~2.5e38 erg/s) to its active
state in between ~7e39 erg/s and 1.3e40 erg/s (in the 0.5-10 keV energy band)
and shows unusual spectral changes. The X-ray spectra of some Chandra
observations are best fitted with an absorbed power-law model with photon index
ranging from 1.3 to 1.7. These spectra are similar to those of Galactic black
hole binary candidates seen in the low/hard state except that a very hard
spectrum was seen in one of the observations. By comparing with near infrared
images taken with the Hubble Space Telescope, the ULX is found to be located
within a young star cluster. Radio imaging indicates that it is associated with
a H II region. We suggest that the ULX is likely to be a > 100 solar mass
intermediate-mass black hole in the low/hard state. In addition to the
transient ULX, we also found a highly absorbed hard X-ray source which is
likely to be an AGN and an ultraluminous X-ray emitting young supernova remnant
which may be related to a 100-year old gamma-ray burst event, within 2 arcsec
of the transient ULX.


title:
Dynamic facilitation explains democratic particle motion of metabasin
  transitions

abstract:
  Transitions between metabasins in supercooled liquids seem to occur through
rapid "democratic" collective particle rearrangements. Here we show that this
apparent homogeneous particle motion is a direct consequence of dynamic
facilitation. We do so by studying metabasin transitions in facilitated spin
models and constrained lattice gases. We find that metabasin transitions occur
through a sequence of locally facilitated events taking place over a relatively
short time frame. When observed on small enough spatial windows these events
appear sudden and homogeneous. Our results indicate that metabasin transitions
are essentially "non-democratic" in origin and yet another manifestation of
dynamical heterogeneity in glass formers.


title:
Families of traveling impulses and fronts in some models with
  cross-diffusion

abstract:
  An analysis of traveling wave solutions of partial differential equation
(PDE) systems with cross-diffusion is presented. The systems under study fall
in a general class of the classical Keller-Segel models to describe chemotaxis.
The analysis is conducted using the theory of the phase plane analysis of the
corresponding wave systems without a priory restrictions on the boundary
conditions of the initial PDE. Special attention is paid to families of
traveling wave solutions. Conditions for existence of front-impulse,
impulse-front, and front-front traveling wave solutions are formulated. In
particular, the simplest mathematical model is presented that has an
impulse-impulse solution; we also show that a non-isolated singular point in
the ordinary differential equation (ODE) wave system implies existence of
free-boundary fronts. The results can be used for construction and analysis of
different mathematical models describing systems with chemotaxis.


title:
Reducing eccentricity in black-hole binary evolutions with initial
  parameters from post-Newtonian inspiral

abstract:
  Standard choices of quasi-circular orbit parameters for black-hole binary
evolutions result in eccentric inspiral. We introduce a conceptually simple
method, which is to integrate the post-Newtonian equations of motion through
hundreds of orbits, and read off the values of the momenta at the separation at
which we wish to start a fully general relativistic numerical evolution. For
the particular case of non-spinning equal-mass inspiral with an initial
coordinate separation of $D = 11M$ we show that this approach reduces the
eccentricity by at least a factor of five to $e < 0.002$ as compared to using
standard quasi-circular initial parameters.


title:
LCHO-CI method for the voltage control of exchange interaction in gated
  lateral quantum dot networks

abstract:
  We present a computational LCHO-CI approach allowing for the simulation of
exchange interactions in gated lateral quantum dot networks. The approach is
based on single-particle states calculated using a linear combination of
harmonic orbitals (LCHO) of each of the dots, and a configuration interaction
(CI) approach to the interacting electron problem. The LCHO-CI method is
applied to a network of three quantum dots with one electron spin per dot, and
a Heisenberg spin Hamiltonian is derived. The manipulation of spin states of a
three-spin molecule by applying bias to one of the dots is demonstrated and
related to the bias dependence of effective exchange interaction parameters.


title: Nonclassical Rotational Inertia in Single Crystal Helium

abstract:
  It has been proposed that the observed nonclassical rotational inertia (NCRI)
in solid helium results from the superflow of thin liquid films along
interconnected grain boundaries within the sample. We have carried out new
torsional oscillator measurements on large helium crystals grown under constant
temperature and pressure. We observe NCRI in all samples, indicating that the
phenomenon cannot be explained by a superfluid film flowing along grain
boundaries.


title: Latin Square Thue-Morse Sequences are Overlap-Free

abstract:
  We define a morphism based upon a Latin square that generalizes the
Thue-Morse morphism. We prove that fixed points of this morphism are
overlap-free sequences generalizing results of Allouche - Shallit and Frid.


title: Entropy and Variational principles for holonomic probabilities of IFS

abstract:
  Associated to a IFS one can consider a continuous map $\hat{\sigma} :
[0,1]\times \Sigma \to [0,1]\times \Sigma$, defined by
$\hat{\sigma}(x,w)=(\tau_{X_{1}(w)}(x), \sigma(w))$ were $\Sigma=\{0,1, ...,
d-1\}^{\mathbb{N}}$, $\sigma: \Sigma \to \Sigma$ is given
by$\sigma(w_{1},w_{2},w_{3},...)=(w_{2},w_{3},w_{4}...)$ and $X_{k} : \Sigma
\to \{0,1, ..., n-1\}$ is the projection on the coordinate $k$. A
$\rho$-weighted system, $\rho \geq 0$, is a weighted system $([0,1], \tau_{i},
u_{i})$ such that there exists a positive bounded function $h : [0,1] \to
\mathbb{R}$ and probability $\nu $ on $[0,1]$ satisfying $ P_{u}(h)=\rho h,
\quad P_{u}^{*}(\nu)=\rho\nu$. A probability $\hat{\nu}$ on $[0,1]\times
\Sigma$ is called holonomic for $\hat{\sigma}$ if $ \int g \circ \hat{\sigma}
d\hat{\nu}= \int g d\hat{\nu}, \forall g \in C([0,1])$. We denote the set of
holonomic probabilities by ${\cal H}$. Via disintegration, holonomic
probabilities $\hat{\nu}$ on $[0,1]\times \Sigma$ are naturally associated to a
$\rho$-weighted system. More precisely, there exist a probability $\nu$ on
$[0,1]$ and $u_i, i\in\{0, 1,2,..,d-1\}$ on $[0,1]$, such that is
$P_{u}^*(\nu)=\nu$. We consider holonomic ergodic probabilities. For a
holonomic probability we define entropy. Finally, we analyze the problem: given
$\phi \in \mathbb{B}^{+}$, find the solution of the maximization pressure
problem $$p(\phi)=$$


title: Color Octet Scalar Production at the LHC

abstract:
  New physics at the weak scale that can couple to quarks typically gives rise
to unacceptably large flavor changing neutral currents. An attractive way to
avoid this problem is to impose the principal of minimal flavor violation
(MFV). Recently it was noted that in MFV only scalars with the same gauge
quantum numbers as the standard model Higgs doublet or color octet scalars with
the same weak quantum numbers as the Higgs doublet can couple to quarks. In
this paper we compute the one-loop rate for production of a single color octet
scalar through gluon fusion at the LHC, which can become greater than the tree
level pair production rate for octet scalar masses around a TeV. We also
calculate the precision electroweak constraint from Z decays to a b and anti-b
quark; this constraint on color octet mass and Yukawa coupling affects the
allowed range for single octet scalar production through gluon fusion.


title:
Universal inequalities for the eigenvalues of Laplace and Schr\"odinger
  operators on submanifolds,

abstract:
  We establish inequalities for the eigenvalues of Schr\"{o}dinger operators on
compact submanifolds (possibly with nonempty boundary) of Euclidean spaces, of
spheres, and of real, complex and quaternionic projective spaces, which are
related to inequalities for the Laplacian on Euclidean domains due to Payne,
P\'olya, and Weinberger and to Yang, but which depend in an explicit way on the
mean curvature. In later sections, we prove similar results for Schr\"{o}dinger
operators on homogeneous Riemannian spaces and, more generally, on any
Riemannian manifold that admits an eigenmap into a sphere, as well as for the
Kohn Laplacian on subdomains of the Heisenberg group.
  Among the consequences of this analysis are an extension of Reilly's
inequality, bounding any eigenvalue of the Laplacian in terms of the mean
curvature, and spectral criteria for the immersibility of manifolds in
homogeneous spaces.


title:
Optical readout of charge and spin in a self-assembled quantum dot in a
  strong magnetic field

abstract:
  We present a theory and experiment demonstrating optical readout of charge
and spin in a single InAs/GaAs self-assembled quantum dot. By applying a
magnetic field we create the filling factor 2 quantum Hall singlet phase of the
charged exciton. Increasing or decreasing the magnetic field leads to
electronic spin-flip transitions and increasing spin polarization. The
increasing total spin of electrons appears as a manifold of closely spaced
emission lines, while spin flips appear as discontinuities of emission lines.
The number of multiplets and discontinuities measures the number of carriers
and their spin. We present a complete analysis of the emission spectrum of a
single quantum dot with N=4 electrons and a single hole, calculated and
measured in magnetic fields up to 23 Tesla.


title: Orbital evolution with white-dwarf kicks

abstract:
  Recent observations of white dwarfs in globular clusters indicate that these
stars may get a velocity kick during their time as giants. This velocity kick
could originate naturally if the mass loss while on the asymptotic giant branch
is slightly asymmetric. If white dwarfs get a kick comparable to the orbital
velocity of the binary, the initial Runge-Lenz vector (eccentricity vector) of
the orbit is damped to be replaced by a component pointing toward the cross
product of the initial angular momentum and the force. The final eccentricity
may be of order unity and if the kick is sufficiently large, the system may be
disrupted. These results may have important ramifications for the evolution of
binary stars and planetary systems


title: Zipf's law in Nuclear Multifragmentation and Percolation Theory

abstract:
  We investigate the average sizes of the $n$ largest fragments in nuclear
multifragmentation events near the critical point of the nuclear matter phase
diagram. We perform analytic calculations employing Poisson statistics as well
as Monte Carlo simulations of the percolation type. We find that previous
claims of manifestations of Zipf's Law in the rank-ordered fragment size
distributions are not born out in our result, neither in finite nor infinite
systems. Instead, we find that Zipf-Mandelbrot distributions are needed to
describe the results, and we show how one can derive them in the infinite size
limit. However, we agree with previous authors that the investigation of
rank-ordered fragment size distributions is an alternative way to look for the
critical point in the nuclear matter diagram.


title:
Four quasars above redshift 6 discovered by the Canada-France High-z
  Quasar Survey

abstract:
  The Canada-France High-z Quasar Survey (CFHQS) is an optical survey designed
to locate quasars during the epoch of reionization. In this paper we present
the discovery of the first four CFHQS quasars at redshift greater than 6,
including the most distant known quasar, CFHQS J2329-0301 at z=6.43. We
describe the observational method used to identify the quasars and present
optical, infrared, and millimeter photometry and optical and near-infrared
spectroscopy. We investigate the dust properties of these quasars finding an
unusual dust extinction curve for one quasar and a high far-infrared luminosity
due to dust emission for another. The mean millimeter continuum flux for CFHQS
quasars is substantially lower than that for SDSS quasars at the same redshift,
likely due to a correlation with quasar UV luminosity. For two quasars with
sufficiently high signal-to-noise optical spectra, we use the spectra to
investigate the ionization state of hydrogen at z>5. For CFHQS J1509-1749 at
z=6.12, we find significant evolution (beyond a simple extrapolation of lower
redshift data) in the Gunn-Peterson optical depth at z>5.4. The line-of-sight
to this quasar has one of the highest known optical depths at z~5.8. An
analysis of the sizes of the highly-ionized near-zones in the spectra of two
quasars at z=6.12 and z=6.43 suggest the IGM surrounding these quasars was
substantially ionized before these quasars turned on. Together, these
observations point towards an extended reionization process, but we caution
that cosmic variance is still a major limitation in z>6 quasar observations.


title:
On the fixed point property in direct sums of Banach spaces with
  strictly monotone norms

abstract:
  It is shown that if a Banach space X has the weak Banach-Saks property and
the weak fixed point property for nonexpansive mappings and Y satisfies
property asymptotic (P) (which is weaker than the condition WCS(Y)>1), then the
direct sum of X and Y endowed with a strictly monotone norm enjoys the weak
fixed point property. The same conclusion is valid if X admits a
1-unconditional basis.


title:
Optical properties of graphene nanoribbons: the role of many-body
  effects

abstract:
  We investigate from first principles the optoelectronic properties of
nanometer-sized armchair graphene nanoribbons (GNRs). We show that many-body
effects are essential to correctly describe both energy gaps and optical
response. As a signature of the confined geometry, we observe strongly bound
excitons dominating the optical spectra, with a clear family dependent binding
energy. Our results demonstrate that GNRs constitute 1D nanostructures whose
absorption and luminescence performance can be controlled by changing both
family and edge termination.