title:
A new comprehensive set of elemental abundances in DLAs III. Star
  formation histories

abstract:
  We obtained comprehensive sets of elemental abundances for eleven damped
Ly-alpha systems (DLAs) at z_DLA=1.7-2.5. In Paper I of this series, we showed
for three DLA galaxies that we can derive their star formation histories and
ages from a detailed comparison of their intrinsic abundance patterns with
chemical evolution models. We determine in this paper the star formation
properties of six additional DLA galaxies. The derived results confirm that no
single star formation history explains the diverse sets of abundance patterns
in DLAs. We demonstrate that the various star formation histories reproducing
the DLA abundance patterns are typical of local irregular, dwarf starburst and
quiescent spiral galaxies. Independent of the star formation history, the DLAs
have a common characteristic of being weak star forming galaxies; models with
high star formation efficiencies are ruled out. All the derived DLA star
formation rates per unit area are moderate or low, with values between -3.2 <
log SFR < -1.1 M_sol yr^{-1} kpc^{-2}. The DLA abundance patterns require a
large spread in ages ranging from 20 Myr up to 3 Gyr. The oldest DLA in our
sample is observed at z_DLA=1.864 with an age estimated to more than 3 Gyr; it
nicely indicates that galaxies were already forming at z_f>10. But, most of the
DLAs show ages much younger than that of the Universe at the epoch of
observation. Young galaxies thus seem to populate the high redshift Universe at
z>2, suggesting relatively low redshifts of formation (z~3) for most
high-redshift galaxies. The DLA star formation properties are compared with
those of other high-redshift galaxies identified in deep imaging surveys with
the aim of obtaining a global picture of high-redshift objects.


title:
Switching Current Measurements of EuBa2Cu3Oy Intrinsic Josephson
  Junctions

abstract:
  We investigated the switching dynamics of two kinds of EuBa2Cu3Oy (Eu123)
intrinsic Josephson junctions (IJJs) with different anisotropy parameters gamma
(= (m*c/m*ab)1/2) tuned to 37 and 22. In contrast to weakly-coupled IJJs in
Bi2212, significant deviations from the thermally activated escape model of a
single-stack Josephson junction were observed in their switching current
distributions, P(I), due to the strongly-coupled nature of the Eu123 IJJs, The
P(I) of the two IJJs are found to be independent of temperature, below 1.4 K
and 4.2 K, respectively; which indicates the observation of macroscopic quantum
tunneling at high temperatures of liquid He.


title: Chen's double sieve, Goldbach's conjecture and the twin prime problem

abstract:
  We give a more comrehensive treatment of Chen's double sieve and improve
related constants in Goldbach's conjecture and the twin prime problem.


title: Gromov-Witten theory and Noether-Lefschetz theory

abstract:
  Noether-Lefschetz divisors in the moduli of K3 surfaces are the loci
corresponding to Picard rank at least 2. We relate the degrees of the
Noether-Lefschetz divisors in 1-parameter families of K3 surfaces to the
Gromov-Witten theory of the 3-fold total space. The reduced K3 theory and the
Yau-Zaslow formula play an important role. We use results of Borcherds and
Kudla-Millson for O(2,19) lattices to determine the Noether-Lefschetz degrees
in classical families of K3 surfaces of degrees 2, 4, 6 and 8. For the quartic
K3 surfaces, the Noether-Lefschetz degrees are proven to be the Fourier
coefficients of an explicitly computed modular form of weight 21/2 and level 8.
The interplay with mirror symmetry is discussed. We close with a conjecture on
the Picard ranks of moduli spaces of K3 surfaces.


title: Momentum Transfer to Nanoobjects between Parallel Heated Plates

abstract:
  A small-scale, trapezoidal rigid body in the gas-filled gap between two
parallel plates at different temperatures is considered. An analytical
expression for the force onto the body in the direction parallel to the plates
valid for an infinite Knudsen number is derived. Simultaneously, Monte-Carlo
simulations are performed allowing to extend the analysis to Knudsen numbers of
the order of one. The numerical and the analytical results show excellent
agreement, indicating that a temperature gradient orthogonal to the plates can
induce a significant force in parallel direction. This force is only slightly
reduced when a Knudsen number of one is considered. In the future, the
discovered effect may be exploited for the conversion of thermal into
mechanical energy in nanomachines.


title: Existence of extremal Beltrami coefficients with non-constant modulus

abstract:
  Suppose $[\mu]_{T(\Delta)}$ is a point of the universal Teichm\"uller space
$T(\Delta)$. In 1998, it was shown by Bo\v{z}in et al. that there exists $\mu$
such that $\mu$ has non-constant modulus and is uniquely extremal in
$[\mu]_{T(\Delta)}$. It is a natural problem whether there is always an
extremal Beltrmai coefficient of constant modulus in $[\mu]_{T(\Delta)}$ if
$[\mu]_{T(\Delta)}$ admits more than one extremal Beltrami coefficient. The
purpose of this paper is to show that the answer is negative. An infinitesimal
version is also obtained. Extremal sets of extremal Beltrami coefficients are
considered and an open problem is proposed.


title: Chromatin Folding in Relation to Human Genome Function

abstract:
  Three-dimensional (3D) chromatin structure is closely related to genome
function, in particular transcription. However, the folding path of the
chromatin fiber in the interphase nucleus is unknown. Here, we systematically
measured the 3D physical distance between pairwise labeled genomic positions in
gene-dense, highly transcribed domains and gene-poor less active areas on
chromosomes 1 and 11 in G1 nuclei of human primary fibroblasts, using
fluorescence in situ hybridization. Interpretation of our results and those
published by others, based on polymer physics, shows that the folding of the
chromatin fiber can be described as a polymer in a globular state (GS),
maintained by intra-polymer attractive interactions that counteract
self-avoidance forces. The GS polymer model is able to describe chromatin
folding in as well the highly expressed domains as the lowly expressed ones,
indicating that they differ in Kuhn length and chromatin compaction. Each type
of genomic domain constitutes an ensemble of relatively compact globular
folding states, resulting in a considerable cellto- cell variation between
otherwise identical cells. We present evidence for different polymer folding
regimes of the chromatin fiber on the length scale of a few mega base pairs and
on that of complete chromosome arms (several tens of Mb). Our results present a
novel view on the folding of the chromatin fiber in interphase and open the
possibility to explore the nature of the intra-chromatin fiber interactions.


title: P-term Potentials from 4-D Supergravity

abstract:
  P-term inflation arises in some models of brane inflation. Within N=2
supersymmetry the scalar potential contains a vector of Fayet-Iliopoulos (FI)
terms $\xi_i$. Depending on the direction of this vector it is possible to get
D-term and F-term inflation or a mix of these models. In this paper we review
the problems of embedding the P-term model in supergravity and show how these
can be solved by considering the truncation from an N=2 theory to N=1. We show
that with a simple gauging the scalar potential can include F-term or D-term
parts but not both. The gauging can be altered so that both F-terms and D-terms
containing FI constants can be included. In all cases we display the
inflationary trajectory and, if it exists, the supersymmetric minimum.


title: The analyticity region of the hard sphere gas. Improved bounds

abstract:
  We find an improved estimate of the radius of analyticity of the pressure of
the hard-sphere gas in $d$ dimensions. The estimates are determined by the
volume of multidimensional regions that can be numerically computed. For $d=2$,
for instance, our estimate is about 40% larger than the classical one.


title:
Star Formation, Radio Sources, Cooling X-ray Gas, and Galaxy
  Interactions in the Brightest Cluster Galaxy in 2A0335+096

abstract:
  We present deep emission-line imaging taken with the SOAR Optical Imaging
Camera of the brightest cluster galaxy (BCG) in the nearby (z=0.035) X-ray
cluster 2A0335+096. We analyze long-slit optical spectroscopy, archival VLA,
Chandra X-ray, and XMM UV data. 2A0335+096 is a bright, cool-core X-ray
cluster, once known as a cooling flow. Within the highly disturbed core
revealed by Chandra X-ray observations, 2A0335+096 hosts a highly structured
optical emission-line system. The redshift of the companion is within 100 km/s
of the BCG and has certainly interacted with the BCG, and is likely bound to
it. The comparison of optical and radio images shows curved filaments in
H-alpha emission surrounding the resolved radio source. The velocity structure
of the emission-line bar between the BCG nucleus and the companion galaxy
provides strong evidence for an interaction between the two in the last ~50
Myrs. The age of the radio source is similar to the interaction time, so this
interaction may have provoked an episode of radio activity. We estimate a star
formation rate of >7 solar mass/yr based on the Halpha and archival UV data, a
rate similar to, but somewhat lower than, the revised X-ray cooling rate of
10-30 solar masses/year estimated from XMM spectra by Peterson & workers. The
Halpha nebula is limited to a region of high X-ray surface brightness and cool
X-ray temperature. The detailed structures of H-alpha and X-ray gas differ. The
peak of the X-ray emission is not the peak of H-alpha emission, nor does it lie
in the BCG. The estimated age of the radio lobes and their interaction with the
optical emission-line gas, the estimated timescale for depletion and
accumulation of cold gas, and the dynamical time in the system are all similar,
suggesting a common trigger mechanism.


title: The Contextual Character of Modal Interpretations of Quantum Mechanics

abstract:
  In this article we discuss the contextual character of quantum mechanics in
the framework of modal interpretations. We investigate its historical origin
and relate contemporary modal interpretations to those proposed by M. Born and
W. Heisenberg. We present then a general characterization of what we consider
to be a modal interpretation. Following previous papers in which we have
introduced modalities in the Kochen-Specker theorem, we investigate the
consequences of these theorems in relation to the modal interpretations of
quantum mechanics.


title:
Functional renormalization for quantum phase transitions with
  non-relativistic bosons

abstract:
  Functional renormalization yields a simple unified description of bosons at
zero temperature, in arbitrary space dimension $d$ and for $M$ complex fields.
We concentrate on nonrelativistic bosons and an action with a linear time
derivative. The ordered phase can be associated with a nonzero density of
(quasi) particles $n$. The behavior of observables and correlation functions in
the ordered phase depends crucially on the momentum $k_{ph}$, which is
characteristic for a given experiment. For the dilute regime $k_{ph}\gtrsim
n^{1/d}$ the quantum phase transition is simple, with the same ``mean field''
critical exponents for all $d$ and $M$. On the other hand, the dense regime
$k_{ph}\ll n^{1/d}$ reveals a rather rich spectrum of features, depending on
$d$ and $M$. In this regime one observes for $d\leq 3$ a crossover to a
relativistic action with second time derivatives. This admits order for $d>1$,
whereas $d=1$ shows a behavior similar to the low temperature phase of the
classical two-dimensional $O(2M)$-models.

categories: cond-mat.supr-con astro-ph cond-mat.str-el hep-th


title:
13 New Eclipsing Binaries with Additional Variability in the ASAS
  Catalogue

abstract:
  We present 13 new ASAS eclipsing binaries that exhibit additional periodic
variability due to pulsations, eclipses with another period or spots. All
contact and semi-detached binaries from the ASAS Catalogue were investigated.


title:
Discrete nonlinear hyperbolic equations. Classification of integrable
  cases

abstract:
  We consider discrete nonlinear hyperbolic equations on quad-graphs, in
particular on the square lattice. The fields are associated to the vertices and
an equation Q(x_1,x_2,x_3,x_4)=0 relates four fields at one quad. Integrability
of equations is understood as 3D-consistency. The latter is a possibility to
consistently impose equations of the same type on all the faces of a
three-dimensional cube. This allows to set these equations also on
multidimensional lattices Z^N. We classify integrable equations with complex
fields x, and Q affine-linear with respect to all arguments. The method is
based on analysis of singular solutions.


title: Minimal Walking on the Lattice

abstract:
  We provide the first evidence of a walking dynamics for two color lattice
Yang-Mills theory with two Dirac flavors in the symmetric representation of the
gauge group.


title:
Spin-dependent three-nucleon force effects on nucleon-deuteron
  scattering

abstract:
  We construct a phenomenological three-nucleon force (3NF) model that gives a
good description of polarization observables in elastic nucleon-deuteron
(N-$d$) scattering at a low energy together with a realistic nucleon-nucleon
force and a 3NF arising from the exchange of two pions. Parameters of the
model, which consists of spin-independent, spin-orbit, and tensor components,
are determined to reproduce the three-nucleon binding energy and polarization
observables in N-d scattering at 3 MeV. Predictions of the model 3NF on N-d
polarization observables at higher energies are examined, and effects of each
component on the observables are investigated.


title:
Semi-soft Nematic Elastomers and Nematics in Crossed Electric and
  Magnetic Fields

abstract:
  Nematic elastomers with a locked-in anisotropy direction exhibit semi-soft
elastic response characterized by a plateau in the stress-strain curve in which
stress does not change with strain. We calculate the global phase diagram for a
minimal model, which is equivalent to one describing a nematic in crossed
electric and magnetic fields, and show that semi-soft behavior is associated
with a broken symmetry biaxial phase and that it persists well into the
supercritical regime. We also consider generalizations beyond the minimal model
and find similar results.


title: Prospects for measuring the moment of inertia of pulsar PSR J0737-3039A

abstract:
  Here we consider the possibility of measuring at 10% or better the moment of
inertia I of the J0737-3039A via the gravitomagnetic spin-orbit periastron
precession. It turns out that the prospect of measuring the moment of inertia
of PSR J0737-3039A at 10% accuracy or better seems unlikely given the
limitations to the precision with which the system's basic binary and
post-Keplerian parameters can be measured via radio timing.


title: Dipolar gases in quasi one-dimensional geometries

abstract:
  We analyze the physics of cold dipolar gases in quasi one-dimensional
geometries, showing that the confinement-induced scattering resonances produced
by the transversal trapping are crucially affected by the dipole-dipole
interaction. As a consequence, the dipolar interaction may drastically change
the properties of quasi-1D dipolar condensates, even for situations in which
the dipolar interaction would be completely overwhelmed by the short-range
interactions in a 3D environment.


title: Spherically symmetric solutions of Einstein + non-polynomial gravities

abstract:
  We obtain the static spherically symmetric solutions of a class of
gravitational models whose additions to the General Relativity (GR) action
forbid Ricci-flat, in particular, Schwarzschild geometries. These theories are
selected to maintain the (first) derivative order of the Einstein equations in
Schwarzschild gauge. Generically, the solutions exhibit both horizons and a
singularity at the origin, except for one model that forbids spherical symmetry
altogether. Extensions to arbitrary dimension with a cosmological constant,
Maxwell source and Gauss-Bonnet terms are also considered.


title:
Artifact of the phonon-induced localization by variational calculations
  in the spin-boson model

abstract:
  We present energy and free energy analyses on all variational schemes used in
the spin-boson model at both T=0 and $T\neq0$. It is found that all the
variational schemes have fail points, at where the variational schemes fail to
provide a lower energy (or a lower free energy at $T\neq0$) than the
displaced-oscillator ground state and therefore the variational ground state
becomes unstable, which results in a transition from a variational ground state
to a displaced oscillator ground state when the fail point is reached. Such
transitions are always misidentied as crossover from a delocalized to localized
phases in variational calculations, leading to an artifact of phonon-induced
localization. Physics origin of the fail points and explanations for different
transition behaviors with different spectral functions are found by studying
the fail points of the variational schemes in the single mode case.


title:
All optical sensor for automated magnetometry based on Coherent
  Population Trapping

abstract:
  An automated magnetometer suitable for long lasting measurement under stable
and controllable experimental conditions has been implemented. The device is
based on Coherent Population Trapping (CPT) produced by a multi-frequency
excitation. CPT resonance is observed when a frequency comb, generated by diode
laser current modulation, excites Cs atoms confined in a
$\pi/4\times(2.5)^2\times1 \textrm{cm}^3$, 2 Torr $N_2$ buffered cell. A fully
optical sensor is connected through an optical fiber to the laser head allowing
for truly remote sensing and minimization of the field perturbation. A detailed
analysis of the CPT resonance parameters as a function of the optical detuning
has been made in order to get high sensitivity measurements. The magnetic field
monitoring performances and the best sensitivity obtained in a balanced
differential configuration of the sensor are presented.


title:
Principal Component Analysis and Automatic Relevance Determination in
  Damage Identification

abstract:
  This paper compares two neural network input selection schemes, the Principal
Component Analysis (PCA) and the Automatic Relevance Determination (ARD) based
on Mac-Kay's evidence framework. The PCA takes all the input data and projects
it onto a lower dimension space, thereby reduc-ing the dimension of the input
space. This input reduction method often results with parameters that have
significant influence on the dynamics of the data being diluted by those that
do not influence the dynamics of the data. The ARD selects the most relevant
input parameters and discards those that do not contribute significantly to the
dynamics of the data being modelled. The ARD sometimes results with important
input parameters being discarded thereby compromising the dynamics of the data.
The PCA and ARD methods are implemented together with a Multi-Layer-Perceptron
(MLP) network for fault identification in structures and the performance of the
two methods is as-sessed. It is observed that ARD and PCA give similar
accu-racy levels when used as input-selection schemes. There-fore, the choice
of input-selection scheme is dependent on the nature of the data being
processed.


title:
Using artificial intelligence for data reduction in mechanical
  engineering

abstract:
  In this paper artificial neural networks and support vector machines are used
to reduce the amount of vibration data that is required to estimate the Time
Domain Average of a gear vibration signal. Two models for estimating the time
domain average of a gear vibration signal are proposed. The models are tested
on data from an accelerated gear life test rig. Experimental results indicate
that the required data for calculating the Time Domain Average of a gear
vibration signal can be reduced by up to 75% when the proposed models are
implemented.


title: Evolutionary Optimisation Methods for Template Based Image Registration

abstract:
  This paper investigates the use of evolutionary optimisation techniques to
register a template with a scene image. An error function is created to measure
the correspondence of the template to the image. The problem presented here is
to optimise the horizontal, vertical and scaling parameters that register the
template with the scene. The Genetic Algorithm, Simulated Annealing and
Particle Swarm Optimisations are compared to a Nelder-Mead Simplex optimisation
with starting points chosen in a pre-processing stage. The paper investigates
the precision and accuracy of each method and shows that all four methods
perform favourably for image registration. SA is the most precise, GA is the
most accurate. PSO is a good mix of both and the Simplex method returns local
minima the most. A pre-processing stage should be investigated for the
evolutionary methods in order to improve performance. Discrete versions of the
optimisation methods should be investigated to further improve computational
performance.


title: Spinor calculus for q-deformed quantum spaces II

abstract:
  This is the second part of an article about q-deformed analogs of spinor
calculus. The considerations refer to quantum spaces of physical interest, i.e.
q-deformed Euclidean space in three or four dimensions as well as q-deformed
Minkowski space. The Clifford algebras corresponding to these quantum spaces
are treated. Especially, their commutation relations and their Hopf structures
are written down. Bases of the four-dimensional Clifford algebras are
constructed and their properties are discussed. Matrix representations of the
Clifford algebras lead to q-deformed Dirac-matrices for the four-dimensional
quantum spaces. Moreover, q-analogs of the four-dimensional spin matrices are
presented. A very complete set of trace relations and rearrangement formulae
concerning spin and Dirac-matrices is given. Dirac spinors together with their
bilinear covariants are defined. Their behavior under q-deformed Lorentz
transformation is discussed in detail.


title: Thermal Equilibrium as an Initial State for Quantum Computation by NMR

abstract:
  We present a method of using a nuclear magnetic resonance computer to solve
the Deutsch-Jozsa problem in which: (1) the number of molecules in the NMR
sample is irrelevant to the number of qubits available to an NMR quantum
computer, and (2) the initial state is chosen to be the state of thermal
equilibrium, thereby avoiding the preparation of pseudopure states and the
resulting exponential loss of signal as the number of qubits increases. The
algorithm is described along with its experimental implementation using four
active qubits. As expected, measured spectra demonstrate a clear distinction
between constant and balanced functions.


title: WASP-1: A lithium- and metal-rich star with an oversized planet

abstract:
  In this paper we present our results of a comprehensive spectroscopicanalysis
of WASP-1, the host star to the exoplanet WASP-1b. We derive T_eff = 6110 +/-
45 K, log g = 4.28 +/- 0.15, and [M/H] = 0.23 +/- 0.08, and also a high
abundance of lithium, log n(Li) = 2.91 +/- 0.05. These parameters suggests an
age for the system of 1-3 Gyr and a stellar mass of 1.25-1.35 M_sun. This means
that WASP-1 has properties very similar to those of HD 149026, the host star
for the highest density planet yet detected. Moreover, their planets orbit at
comparable distances and receive comparable irradiating fluxes from their host
stars. However, despite the similarity of WASP-1 with HD 149026, their planets
have strongly different densities. This suggests that gas-giant planet density
is not a simple function of host-star metallicity or of radiation environment
at ages of ~2 Gyr.


title:
alpha-particle production in the scattering of 6He by 208Pb at energies
  around the Coulomb barrier

abstract:
  New experimental data from the scattering of 6He+208Pb at energies around and
below the Coulomb barrier are presented. The yield of breakup products coming
from projectile fragmentation is dominated by a strong group of $\alpha$
particles.
  The energy and angular distributions of this group have been analyzed and
compared with theoretical calculations. This analysis indicates that the
$\alpha$ particles emitted at backward angles in this reaction are mainly due
to two-neutron transfer to weakly bound states of the final nucleus.


title: Extracting the hierarchical organization of complex systems

abstract:
  Extracting understanding from the growing ``sea'' of biological and
socio-economic data is one of the most pressing scientific challenges facing
us. Here, we introduce and validate an unsupervised method that is able to
accurately extract the hierarchical organization of complex biological, social,
and technological networks. We define an ensemble of hierarchically nested
random graphs, which we use to validate the method. We then apply our method to
real-world networks, including the air-transportation network, an electronic
circuit, an email exchange network, and metabolic networks. We find that our
method enables us to obtain an accurate multi-scale descriptions of a complex
system.


title: Option Pricing Using Bayesian Neural Networks

abstract:
  Options have provided a field of much study because of the complexity
involved in pricing them. The Black-Scholes equations were developed to price
options but they are only valid for European styled options. There is added
complexity when trying to price American styled options and this is why the use
of neural networks has been proposed. Neural Networks are able to predict
outcomes based on past data. The inputs to the networks here are stock
volatility, strike price and time to maturity with the output of the network
being the call option price. There are two techniques for Bayesian neural
networks used. One is Automatic Relevance Determination (for Gaussian
Approximation) and one is a Hybrid Monte Carlo method, both used with
Multi-Layer Perceptrons.


title: Atomic Electric Dipole Moments: The Schiff Theorem and Its Corrections

abstract:
  Searches for the permanent electric dipole moments (EDMs) of diamagnetic
atoms provide powerful probes of CP-violating hadronic and semileptonic
interactions. The theoretical interpretation of such experiments, however,
requires careful implementation of a well-known theorem by Schiff that implies
a vanishing net EDM for an atom built entirely from point-like, nonrelativistic
constituents that interact only electrostatically. Any experimental observation
of a nonzero atomic EDM would result from corrections to the point-like,
nonrelativistic, electrostatic assumption. We reformulate Schiff's theorem at
the operator level and delineate the electronic and nuclear operators whose
atomic matrix elements generate corrections to "Schiff screening". We obtain a
form for the operator responsible for the leading correction associated with
finite nuclear size -- the so-called "Schiff moment" operator -- and observe
that it differs from the corresponding operator used in previous Schiff moment
computations. We show that the more general Schiff moment operator reduces to
the previously employed operator only under certain approximations that are not
generally justified. We also identify other corrections to Schiff screening
that may not be included properly in previous theoretical treatments. We
discuss practical considerations for obtaining a complete computation of
corrections to Schiff screening in atomic EDM calculations.


title:
Capacity of Underspread Noncoherent WSSUS Fading Channels under Peak
  Signal Constraints

abstract:
  We characterize the capacity of the general class of noncoherent underspread
wide-sense stationary uncorrelated scattering (WSSUS) time-frequency-selective
Rayleigh fading channels, under peak constraints in time and frequency and in
time only. Capacity upper and lower bounds are found which are explicit in the
channel's scattering function and allow to identify the capacity-maximizing
bandwidth for a given scattering function and a given peak-to-average power
ratio.


title: q-Deformed Superalgebras

abstract:
  The article deals with q-analogs of the three- and four-dimensional Euclidean
superalgebra and the Poincare superalgebra.


title:
Demonstration of Shor's quantum factoring algorithm using photonic
  qubits

abstract:
  We report an experimental demonstration of a complied version of Shor's
algorithm using four photonic qubits. We choose the simplest instance of this
algorithm, that is, factorization of N=15 in the case that the period $r=2$ and
exploit a simplified linear optical network to coherently implement the quantum
circuits of the modular exponential execution and semi-classical quantum
Fourier transformation. During this computation, genuine multiparticle
entanglement is observed which well supports its quantum nature. This
experiment represents a step toward full realization of Shor's algorithm and
scalable linear optics quantum computation.


title: Scalar perturbations in braneworld cosmology

abstract:
  We study the behaviour of scalar perturbations in the radiation-dominated era
of Randall-Sundrum braneworld cosmology by numerically solving the coupled bulk
and brane master wave equations. We find that density perturbations with
wavelengths less than a critical value (set by the bulk curvature length) are
amplified during horizon re-entry. This means that the radiation era matter
power spectrum will be at least an order of magnitude larger than the
predictions of general relativity (GR) on small scales. Conversely, we
explicitly confirm from simulations that the spectrum is identical to GR on
large scales. Although this magnification is not relevant for the cosmic
microwave background or measurements of large scale structure, it will have
some bearing on the formation of primordial black holes in Randall-Sundrum
models.


title: Forced accretion in stochastically fed AGN and quasars

abstract:
  Steady state accretion discs larger than ~ 0.01-0.1 pc are known to be
gravitationally unstable for the accretion rates needed to explain
super-massive black hole (SMBH) activity. We propose that SMBH are fed by a
succession of mass deposition events with randomly directed angular momenta.
Because of incomplete angular momentum cancellation a warped accretion disc
forms in the inner few parsec. The orientation of the disc performs a random
walk. Deposition of new material promotes SMBH accretion at rates much faster
than viscous. Observational implications of this picture include: (i) lighter
accretion discs that can fuel AGN and quasars and yet avoid star formation at R
>> 0.1 pc; (ii) star formation inside the disc is not a function of mass
accretion rate only. It can take place at high or low accretion rates, e.g.,
when too few clouds arrive in the inner region. An example of this might be the
central parsec of our Galaxy. (iii) The discs can form Compton-thick obscuring
structures of ~ parsec size as required in AGN unification models; (iv) faster
black hole growth resulting from misalignment of the disc and the black hole
spin in the early Universe; (v) Isotropic deposition of SMBH energy and
momentum feedback in the galaxy bulge. This may help explain the high
efficiency with which it seems to be operating in the Universe. (vi) No
correlation between SMBH activity and the presence of kiloparsec scale bars or
gaseous discs in galactic bulges; (vii) Bodily collisions between gaseous
components of merging galaxies facilitate production of gas streams feeding the
centre of the combined galaxy. Mergers should thus be catalysts of SMBH growth.
(viii) Conversely, galaxies experiencing fewer mergers are more likely to form
massive nuclear star clusters than feed their SMBHs.


title: Existence results for mean field equations with turbulence

abstract:
  In this paper we consider the following form of the so-called Mean field
equation arising from the statistical mechanics description of two dimensional
turbulence \begin{equation}\label{eq:study} - \D_g u = \rho_1
  (\frac{e^{u}}{\int_\Sig e^{u} dV_g}-1)-\rho_2
  (\frac{e^{-u}}{\int_\Sig e^{-u} dV_g} - 1) \end{equation} on a given closed
orientable Riemannian surface ($\Sigma, g$) with volume 1, where $\rho_1,
\rho_2$ are real parameters. Exploiting the variational structure of the
problem and running a min-max scheme introduced by Djadli and Malchiodi, we
prove that if $k$ is a positive integer, $\rho_1$ and
  $\rho_2$ two real numbers such that $\rho_1\in (8k\pi, 8(k+1)\pi)$ and
$\rho_2<4\pi$ then $\eqref{eq:study}$ is solvable.


title: Quantum cosmology with big-brake singularity

abstract:
  We investigate a cosmological model with a big-brake singularity in the
future: while the first time derivative of the scale factor goes to zero, its
second time derivative tends to minus infinity. Although we also discuss the
classical version of the model in some detail, our main interest lies in its
quantization. We formulate the Wheeler-DeWitt equation and derive solutions
describing wave packets. We show that all such solutions vanish in the region
of the classical singularity, a behaviour which we interpret as singularity
avoidance. We then discuss the same situation in loop quantum cosmology. While
this leads to a different factor ordering, the singularity is there avoided,
too.


title:
Effective anisotropies and energy barriers of magnetic nanoparticles
  with Neel surface anisotropy

abstract:
  Magnetic nanoparticles with Neel surface anisotropy, different internal
structures, surface arrangements and elongation are modelled as many-spin
systems. The results suggest that the energy of many-spin nanoparticles cut
from cubic lattices can be represented by an effective one-spin potential
containing uniaxial and cubic anisotropies. It is shown that the values and
signs of the corresponding constants depend strongly on the particle's surface
arrangement, internal structure and elongation. Particles cut from a simple
cubic lattice have the opposite sign of the effective cubic term, as compared
to particles cut from the face-centered cubic lattice. Furthermore, other
remarkable phenomena are observed in nanoparticles with relatively strong
surface effects: (i) In elongated particles surface effects can change the sign
of the uniaxial anisotropy. (ii) In symmetric particles (spherical and
truncated octahedral) with cubic core anisotropy surface effects can change its
sign. We also show that the competition between the core and surface
anisotropies leads to a new energy that contributes to both the 2nd- and
4th-order effective anisotropies.


title: Generalized Brjuno functions associated to $\alpha$-continued fractions

abstract:
  For \alpha in the interval [0,1], we consider the one-parameter family of
\alpha-continued fraction maps, which include the Gauss map (\alpha=1) and the
nearest integer (\alpha=1/2) and by-excess (\alpha=0) continued fraction maps.
To each of these expansions, and to each choice of a positive function u on the
interval I_\alpha=(0,max(\alpha,1-\alpha)) we associate a generalized Brjuno
function B_(\alpha,u)(x). For \alpha=1/2 or \alpha=1, and u(x)=-\log(x), these
functions were introduced by Yoccoz in his work on the linearization of
holomorphic maps. Their regularity properties, including BMO regularity and
their extension to the complex plane, have been thoroughly investigated. We
compare the functions obtained with different values of \alpha and we prove
that the set of (\alpha,u)-Brjuno numbers does not depend on the choice of
\alpha provided that \alpha>0. We then consider the case \alpha=0,
u(x)=-\log(x) and we prove that x is a Brjuno number (for \alpha> 0) if and
only if both x and -x are Brjuno numbers for \alpha=0.


title: Global polarization measurement in Au+Au collisions

abstract:
  The system created in non-central relativistic nucleus-nucleus collisions
possesses large orbital angular momentum. Due to spin-orbit coupling, particles
produced in such a system could become globally polarized along the direction
of the system angular momentum. We present the results of Lambda and
anti-Lambda hyperon global polarization measurements in Au+Au collisions at
sqrt{s_NN}=62.4 GeV and 200 GeV performed with the STAR detector at RHIC. The
observed global polarization of Lambda and anti-Lambda hyperons in the STAR
acceptance is consistent with zero within the precision of the measurements.
The obtained upper limit, |P_{Lambda,anti-Lambda}| <= 0.02, is compared to the
theoretical values discussed recently in the literature.


title: NiO: Correlated Bandstructure of a Charge-Transfer Insulator

abstract:
  The bandstructure of the prototypical charge-transfer insulator NiO is
computed by using a combination of an {\it ab initio} bandstructure method and
the dynamical mean-field theory with a quantum Monte-Carlo impurity solver.
Employing a Hamiltonian which includes both Ni-d and O-p orbitals we find
excellent agreement with the energy bands determined from angle-resolved
photoemission spectroscopy. This solves a long-standing problem in solid state
theory. Most notably we obtain the low-energy Zhang-Rice bands with strongly
k-dependent orbital character discussed previously in the context of low-energy
model theories.


title:
BRST Invariant Theory Of A Generalized 1+1 Dimensional Nonlinear Sigma
  Model With Topological Term

abstract:
  We give a generalized Lagrangian density of 1+1 Dimensional O(3) nonlinear
sigma model with subsidiary constraints, different Lagrange multiplier fields
and topological term, find a lost intrinsic constraint condition, convert the
subsidiary constraints into inner constraints in the nonlinear sigma model,
give the example of not introducing the lost constraint, by comparing the
example with the case of introducing the lost constraint, we obtain that when
not introducing the lost constraint, one has to obtain a lot of various
non-intrinsic constraints. We further deduce the gauge generator, give general
BRST transformation of the model under the general conditions. It is discovered
that there exists a gauge parameter originating from the freedom degree of BRST
transformation in a general O(3) nonlinear sigma model, and we gain the general
commutation relations of ghost field.


title: Note on Schmidt Decomposition in Infinite Dimensional Hilbert Spaces

abstract: This paper has been withdrawn by the author.


title: QCD coupling below 1 GeV from quarkonium spectrum

abstract:
  In this paper we extend the work synthetically presented in Ref.[1] and give
theoretical details and complete tables of numerical results. We exploit
calculations within a Bethe-Salpeter (BS) formalism adjusted for QCD, in order
to extract an ``experimental'' strong coupling \alpha_s^{exp}(Q^2) below 1 GeV
by comparison with the meson spectrum. The BS potential follows from a proper
ansatz on the Wilson loop to encode confinement and is the sum of a
one-gluon-exchange and a confinement terms. Besides, the common perturbative
strong coupling is replaced by the ghost-free expression \alpha_E(Q^2)
according to the prescription of Analytic Perturbation Theory (APT). The
agreement of \alpha_s^{exp}(Q^2) with the APT coupling \alpha_E(Q^2) turns out
to be reasonable from 1 GeV down to the 200 MeV scale, thus confirming
quantitatively the validity of the APT prescription. Below this scale, the
experimental points could give a hint on the vanishing of \alpha_s(Q^2) as Q
approaches zero. This infrared behaviour would be consistent with some lattice
results and a ``massive'' generalization of the APT approach. As a main result,
we claim that the combined BS-APT theoretical scheme provides us with a rather
satisfactory correlated understanding of very high and rather low energy
phenomena from few hundreds MeV to few hundreds GeV.


title: Subelliptic Spin_C Dirac operators, I

abstract:
  We consider modifications of the classical dbar-Neumann conditions that
define Fredholm problems for the Spin_C Dirac operator. In part II, we use
boundary layer methods to obtain subelliptic estimates for these boundary value
problems. Using these results, we obtain an expression for the finite part of
the holomorphic Euler characteristic of a strictly pseudoconvex manifold as the
index of a Spin_C-Dirac operator with a subelliptic boundary condition. We also
prove an analogue of the Agranovich-Dynin formula expressing the change in the
index in terms of a relative index on the boundary. If X is a complex manifold
partitioned by a strictly pseudoconvex hypersurface, then we obtain formulae
for the holomorphic Euler characteristic of X as sums of indices of
Spin_C-Dirac operators on the components. This is a subelliptic analogue of
Bojarski's formula in the elliptic case.


title: $D_{sJ}$(2317) meson production at RHIC

abstract:
  Production of $D_{sJ}$(2317) mesons in relativistic heavy ion collisions at
RHIC is studied. Using the quark coalescence model, we first determine the
initial number of $D_{sJ}$(2317) mesons produced during hadronization of
created quark-gluon plasma. The predicted $D_{sJ}$(2317) abundance depends
sensitively on the quark structure of the $D_{sJ}$(2317) meson. An
order-of-magnitude larger yield is obtained for a conventional two-quark than
for an exotic four-quark $D_{sJ}$(2317) meson. To include the hadronic effect
on the $D_{sJ}$(2317) meson yield, we have evaluated the absorption cross
sections of the $D_{sJ}$(2317) meson by pion, rho, anti-kaon, and vector
anti-kaon in a phenomenological hadronic model. Taking into consideration the
absorption and production of $D_{sJ}$(2317) mesons during the hadronic stage of
heavy ion collisions via a kinetic model, we find that the final yield of
$D_{sJ}$(2317) mesons remains sensitive to its initial number produced from the
quark-gluon plasma, providing thus the possibility of studying the quark
structure of the $D_{sJ}$(2317) meson and its production mechanism in
relativistic heavy ion collisions.


title: Hives and the fibres of the convolution morphism

abstract:
  By the geometric Satake correspondence, the number of components of certain
fibres of the affine Grassmannian convolution morphism equals the tensor
product multiplicity for representations of the Langlands dual group. On the
other hand, in the case of GL_n, combinatorial objects called hives also count
tensor product multiplicities. The purpose of this paper is to give a simple
bijection between hives and the components of these fibres. In particular, we
give a description of the individual components. We also describe a conjectural
generalization involving the octahedron recurrence.


title: Subelliptic Spin_C Dirac operators, II Basic Estimates

abstract:
  We assume that the manifold with boundary, X, has a Spin_C-structure with
spinor bundle S. Along the boundary, this structure agrees with the structure
defined by an infinite order integrable almost complex structure and the metric
is Kahler. The induced CR-structure on bX is integrable and either strictly
pseudoconvex or strictly pseudoconcave. We assume that E->X is a complex vector
bundle, which has an infinite order integrable complex structure along bX,
compatible with that defined along bX. In this paper use boundary layer methods
to prove subelliptic estimates for the twisted Spin_C- Dirac operator acting on
sections on S\otimes E. We use boundary conditions that are modifications of
the classical dbar-Neumann condition. These results are proved by using the
extended Heisenberg calculus.


title: Synthesis of Taylor Phase Screens with Karhunen-Loeve Basis Functions

abstract:
  Phase screens above a telescope pupil represent the variation of the phase of
the electromagnetic field induced by atmospheric turbulence. Instances drawn
from such statistics are represented by a vector of random phase amplitudes
which are coefficients of a linear superposition of two-dimensional basis
functions across the pupil. This work shortly reviews Fried's analysis of this
modal decomposition for the case of Kolmogorov statistics of the phase
covariance as a function of separation in the pupil plane.
  We focus on the numerical synthesis of phase screens. The statistically
independent modes are transformed into the eigen-modes of a gradient matrix as
time-dependence is introduced such that on short time scales the instances of
the phase screens are rigidly shifted into a direction imposed by some wind
velocity - known as the Taylor frozen screen approximation. This simple
technique factorizes spatial and temporal variables and aims at binding the
time dependence of the phase screens to the few expansion coefficients of the
basis functions that obey a stochastic time-dependent differential equation.


title:
Universality results for largest eigenvalues of some sample covariance
  matrix ensembles

abstract:
  For sample covariance matrices with iid entries with sub-Gaussian tails, when
both the number of samples and the number of variables become large and the
ratio approaches to one, it is a well-known result of A. Soshnikov that the
limiting distribution of the largest eigenvalue is same as the of Gaussian
samples. In this paper, we extend this result to two cases. The first case is
when the ratio approaches to an arbitrary finite value. The second case is when
the ratio becomes infinity or arbitrarily small.


title: Cobordism, Relative Indices and Stein Fillings

abstract:
  In this paper we build on the framework developed in "Subelliptic Boundary
Value Problems for the Spin_C Dirac Operator, I, II, III" to obtain a more
complete understanding of the gluing properties for indices of boundary value
problems for the SpinC-Dirac operator with sub-elliptic boundary conditions. We
extend our analytic results for sub-elliptic boundary value problems for the
SpinC-Dirac operator, and gluing results for the indices of these boundary
problems to SpinC-manifolds with several pseudoconvex (pseudoconcave) boundary
components. These results are applied to study Stein fillability for compact,
3-dimensional, contact manifolds.


title: Structural Disorder and Properties of the Stuffed Pyrochlore Ho2TiO5

abstract:
  We report a structural and thermodynamic study of the "stuffed spin ice"
material Ho2TiO5 (i.e., Ho2(Ti1.33Ho0.67)O6.67), comparing samples synthesized
through two different routes. Neutron powder diffraction and electron
diffraction reveal that the previously reported defect fluorite phase has
short-range pyrochlore ordering, in that there are domains in which the Ho and
Ho/Ti sublattices are distinct. By contrast, a sample prepared through a
floating zone method has long range ordering of these sublattices. Despite the
differences in crystal structures, the two versions of Ho2TiO5 display similar
magnetic susceptibilities. Field dependent magnetization and measured recovered
entropies, however, show a difference between the two forms, suggesting that
the magnetic properties of the stuffed pyrochlores depend on the local
structure.


title: Observation of higher-order solitons in defocusing waveguide arrays

abstract:
  We observe experimentally higher-order solitons in waveguide arrays with
defocusing saturable nonlinearity. Such solitons can comprise several in-phase
bright spots and are stable above a critical power threshold. We elucidate the
impact of the nonlinearity saturation on the domains of existence and stability
of the observed complex soliton states.


title: On the nature of the short duration GRB 050906

abstract:
  We present deep optical and infrared observations of the short duration GRB
050906. Although no X-ray or optical/IR afterglow was discovered to deep
limits, the error circle of the GRB (as derived from the Swift BAT) is unusual
incontaining the relatively local starburst galaxy IC328. This makes GRB 050906
a candidate burst from a soft-gamma repeater, similar to the giant flare from
SGR 1806-20. The probability of chance alignment of a given BAT position with
such a galaxy is small (<1%), although the size of the error circle (2.6
arcminute radius) is such that a higher-z origin can't be ruled out. Indeed,
the error circle also includes a moderately rich galaxy cluster at z=0.43,
which is a plausible location for the burst given the apparent preference that
short GRBs have for regions of high mass density. No residual optical or
infrared emission has been observed, either in the form of an afterglow or
later time emission from any associated supernova-like event. We discuss the
constraints these limits place on the progenitor of GRB 050906 based on the
expected optical signatures from both SGRs and merging compact object systems.


title: Slicing, skinning, and grafting

abstract:
  We prove that a Bers slice is never algebraic, meaning that its Zariski
closure in the character variety has strictly larger dimension. A corollary is
that skinning maps are never constant.
  The proof uses grafting and the theory of complex projective structures.


title: A lower bound for the density of states of the lattice Anderson model

abstract:
  We consider the Anderson model on the multi-dimensional cubic lattice and
prove a positive lower bound on the density of states under certain conditions.
For example, if the random variables are independently and identically
distributed and the probability measure has a bounded Lebesgue density with
compact support, and if this density is essentially bounded away from zero on
its support, then we prove that the density of states is strictly positive for
Lebesgue-almost every energy in the deterministic spectrum.


title: A homotopy method for finding eigenvalues and eigenvectors

abstract:
  Suppose we want to find the eigenvalues and eigenvectors for the linear
operator L, and suppose that we have solved this problem for some other
"nearby" operator K. In this paper we show how to represent the eigenvalues and
eigenvectors of L in terms of the corresponding properties of K.


title: Differential operators on toric varieties and Fourier transform

abstract:
  We show that Fourier transforms on the Weyl algebras have a geometric
counterpart in the framework of toric varieties, namely they induce
isomorphisms between twisted rings of differential operators on regular toric
varieties, whose fans are related to each other by reflections of
one-dimensional cones. The simplest class of examples is provided by the toric
varieties related by such reflections to projective spaces. It includes the
blow-up at a point in affine space and resolution of singularities of varieties
appearing in the study of the minimal orbit of sl(n+1).


title: Highly Entangled Ground States in Tripartite Qubit Systems

abstract:
  We investigate the creation of highly entangled ground states in a system of
three exchange-coupled qubits arranged in a ring geometry. Suitable magnetic
field configurations yielding approximate GHZ and exact W ground states are
identified. The entanglement in the system is studied at finite temperature in
terms of the mixed-state tangle tau. By adapting a steepest-descent
optimization algorithm we demonstrate that tau can be evaluated efficiently and
with high precision. We identify the parameter regime for which the equilibrium
entanglement of the tripartite system reaches its maximum.


title: Measurement of electro-magnetic radiation at PHENIX

abstract:
  Recent results on direct photons and dileptons from the PHENIX xperiment
opened up a possibility of landscaping electro-magnetic radiation over various
kinetic energies in heavy ion collisions. A detail discussion is given based on
a review of the results.


title: Heaviness of Heavy Quarkonia in Heavy Ion Collisions

abstract:
  High energy heavy ion collisions at the Relativistic Heavy Ion Collider
(RHIC) produce a novel medium characterized by an initial energy density over
an order of magnitude above the expected phase transformation value and that
then evolves as a nearly inviscid liquid. Probing the medium with
auto-generated particles is a key methodology to quantitatively determine the
medium properties. Pairs of heavy quarks are an excellent probe since their
spatial separation to form various quarkonia states spans the relevant range of
color screening lengths in the medium. In this proceedings, we describe results
from the PHENIX experiment on $J/\psi$ production and discuss initial physics
implications of the measurements.


title:
From bubbles to foam: dilute to dense evolution of hadronic wave
  function at high energy

abstract:
  We derive the evolution of a hadronic light cone wave function with energy at
weak coupling. Our derivation is valid both in the high and the low partonic
density limit, and thus encompasses both the JIMWLK and the KLWMIJ evolution.
The hadronic wave function is shown to evolve by the action of the
Bogoliubov-type operator, which diagonalizes on the soft gluon sector the
light-cone hamiltonian in the presence of an arbitrary valence charge density.
We find explicitly the action of this operator on the soft as well as the
valence degrees of freedom of the theory.


title: Selfsimilar Equivalence of Porous Medium and p-Laplacian Flows

abstract:
  We demonstrate the equivalence between the two popular models of nonlinear
diffusion, the porous medium equation and the p-Laplacian equation. The
equivalence is shown at the level of selfsimilar solutions.


title: Holomorphic fiber bundle with Stein base and Stein fibers

abstract:
  In this article, we prove that if $\Pi: X\to \Omega$ is a surjective
holomorphic map, with $\Omega$ a Stein space and $X$ a complex manifold of
dimension $n\geq 3,$ and if, for every $x\in \Omega$ there exists an open
neighborhood $U$ such that $\Pi^{-1}(U)$ is Stein, then $X$ is Stein


title: Wormholes, Void Bubbles and Vacuum Energy Suppression

abstract:
  The gargantuan discrepancy between the value of the observed cosmological
constant and that expected from the zero-point energy of known matter fields
can be eliminated by supposing that on macroscopic scales the overwhelming
majority of any volume of spacetime is literal nothingness. This nothingness or
void results from the proliferative nucleation of tiny void bubbles (a.k.a.
"bubbles of nothing" or "semi wormholes") that expand until their surfaces,
presumed to be 2-branes, collide. This process results in a dense packing of
void bubbles of various sizes that leaves only the vanishing interstitial
regions between bubbles for spacetime to occupy. This vast reduction in the
amount of actual space contained within any apparent volume, reduces
correspondingly the effective zero-point energy density. Unlike previous
wormhole-based attempts at vacuum energy suppression, the current approach is
entirely Lorentzian and results in a nonzero value for the cosmological
constant.


title:
Relation between exchange-only optimized potential and Kohn-Sham methods
  with finite basis sets; solution of a paradox

abstract:
  Arguments showing that exchange-only optimized effective potential (xOEP)
methods, with finite basis sets, cannot in general yield the Hartree-Fock (HF)
ground state energy, but a higher one, are given. While the orbital products of
a complete basis are linearly dependent, the HF ground state energy can only be
obtained via a basis set xOEP scheme in the special case that all products of
occupied and unoccupied orbitals emerging from the employed orbital basis set
are linearly independent from each other. In this case, however, exchange
potentials leading to the HF ground state energy exhibit unphysical
oscillations and do not represent a Kohn-Sham (KS) exchange potential. These
findings solve the seemingly paradoxical results of Staroverov, Scuseria and
Davidson that certain finite basis set xOEP calculations lead to the HF ground
state energy despite the fact that within a real space (or complete basis)
representation the xOEP ground state energy is always higher than the HF
energy. Moreover, whether or not the occupied and unoccupied orbital products
are linearly independent, it is shown that basis set xOEP methods only
represent exact exchange-only (EXX) KS methods, i.e., proper density-functional
methods, if the orbital basis set and the auxiliary basis set representing the
exchange potential are balanced to each other, i.e., if the orbital basis is
comprehensive enough for a given auxiliary basis. Otherwise xOEP methods do not
represent EXX KS methods and yield unphysical exchange potentials.


title:
Cosmological Constraints from Type Ia Supernovae Peculiar Velocity
  Measurements

abstract:
  We detect the correlated peculiar velocities of nearby type Ia supernovae
(SNe), while highlighting an error in some of the literature. We find
sigma_8=0.79 +/- 0.22 from SNe, and examine the potential of this method to
constrain cosmological parameters in the future. We demonstrate that a survey
of 300 low-z SNe (such as the nearby SNfactory) will underestimate the errors
on w by about 35% if the coherent peculiar velocities are not included.


title: Gaining analytic control of parton showers

abstract:
  Parton showers are widely used to generate fully exclusive final states
needed to compare theoretical models to experimental observations. While, in
general, parton showers give a good description of the experimental data, the
precise functional form of the probability distribution underlying the event
generation is generally not known. The reason is that realistic parton showers
are required to conserve four-momentum at each vertex. In this paper we
investigate in detail how four-momentum conservation is enforced in a standard
parton shower and why this destroys the analytic control of the probability
distribution. We show how to modify a parton shower algorithm such that it
conserves four-momentum at each vertex, but for which the full analytic form of
the probability distribution is known. We then comment how this analytic
control can be used to match matrix element calculations with parton showers,
and to estimate effects of power corrections and other uncertainties in parton
showers.


title:
Separation of the visible and dark matter in the Einstein ring LBG
  J213512.73-010143

abstract:
  We model the mass distribution in the recently discovered Einstein ring LBG
J213512.73-010143 (the `Cosmic Eye') using archival Hubble Space Telescope
imaging. We reconstruct the mass density profile of the z=0.73 lens and the
surface brightness distribution of the z=3.07 source and find that the observed
ring is best fit with a dual-component lens model consisting of a baryonic
Sersic component nested within a dark matter halo. The dark matter halo has an
inner slope of 1.42+/-0.23, consistent with CDM simulations after allowing for
baryon contraction. The baryonic component has a B-band mass-to-light ratio of
1.71+0.28-0.38 (solar units) which when evolved to the present day is in
agreement with local ellipticals. Within the Einstein radius of 0.77'' (5.6
kpc), the baryons account for (46+/-11)% of the total lens mass. External shear
from a nearby foreground cluster is accurately predicted by the model. The
reconstructed surface brightness distribution in the source plane clearly shows
two peaks. Through a generalisation of our lens inversion method, we conclude
that the redshifts of both peaks are consistent with each other, suggesting
that we are seeing structure within a single galaxy.


title:
A Detailed Study of Gas and Star Formation in a Highly Magnified Lyman
  Break Galaxy at z=3.07

abstract:
  We report the detection of CO(3-2) emission from a bright, gravitationally
lensed Lyman Break Galaxy, LBGJ213512.73-010143 (the 'Cosmic Eye'), at z=3.07
using the Plateau de Bure Interferometer. This is only the second detection of
molecular gas emission from an LBG and yields an intrinsic molecular gas mass
of (2.4+/-0.4)x10^9 Mo. The lens reconstruction of the UV morphology of the LBG
indicates that it comprises two components separated by ~2 kpc. The CO emission
is unresolved, and appears to be centered on the intrinsically fainter (and
also less highly magnified) of the two UV components. The width of the CO line
indicates a dynamical mass of (8+/-2)x10^9csc(i)^2 Mo within the central 2 kpc.
Employing mid-infrared observations from Spitzer we derive a stellar mass of
~(6+/-2)x10^9 Mo and a star-formation rate of ~60 Mo/yr, indicating that the
molecular gas will be consumed in ~40 Myr. The gas fractions, star-formation
efficiencies and line widths suggests that LBGJ213512 is a high-redshift,
gas-rich analog of a local luminous infrared galaxy. This galaxy has a similar
gas-to-dynamical mass fraction as observed in the submillimeter-selected
population, although the gas surface density and star-formation efficiency is a
factor of 3x less, suggesting less vigorous activity. We discuss the
uncertainties in our conclusions arising from adopting a CO-to-H2 conversion
factor appropriate for either the Milky Way or local luminous infrared
galaxies. These observations demonstrate that current facilities, when aided by
fortuitous gravitational magnification, can study 'ordinary' galaxies at
high-redshift and so act as pathfinders for ALMA.


title: Advances in Reverberation Mapping

abstract:
  This contribution briefly reviews the reverberation mapping technique which
leads to determination of black hole masses. I focus on the emerging relation
between the broad-line region size and the active galactic nucleus (AGN)
luminosity, and on an overview of recent results of reverberation mapping
studies which are starting to cover the full AGN luminosity range. Preliminary
results and time lag determination from a reverberation mapping program of
high-luminosity quasars are also presented.


title:
Neutrinos from Cosmic Ray Accelerators in the Cygnus Region of the
  Galaxy

abstract:
  While supernova remnants have been identified as the most likely sources of
the galactic cosmic rays, no conclusive observational evidence for this
association exists. We show here that IceCube has the possibility of producing
incontrovertible evidence by detecting neutrinos produced by the cosmic ray
beam interacting with the hydrogen in the vicinity of the supernova shock
expanding into the interstellar medium. We show that the observational
information on gamma ray fluxes from the Cygnus region, although limited, is
sufficient to pinpoint the expected event rate of the neutrinos associated with
a single source of 0.5 Crab at the TeV level to within a factor of two, between
2 and 3.8 neutrinos per year. Finally, we note that recent gamma-ray
observations reveal the presence of at least three and possibly up to eight
such sources, raising the possibility of seeing more than 10 neutrinos per year
from these sources alone.


title:
Observation of Competing Order in a High-$T_{c}$ Superconductor with
  Femtosecond Optical Pulses

abstract:
  We present studies of the photoexcited quasiparticle dynamics in
Tl$_{2}$Ba$_{2}$Ca$_{2}$Cu$_{3}$O$_{y}$ (Tl-2223) using femtosecond optical
techniques. Deep into the superconducting state (below 40 K), a dramatic change
occurs in the temporal dynamics associated with photoexcited quasiparticles
rejoining the condensate. This is suggestive of entry into a coexistence phase
which, as our analysis reveals, opens a gap in the density of states (in
addition to the superconducting gap), and furthermore, competes with
superconductivity resulting in a depression of the superconducting gap.


title: Kerr quasinormal modes and Hod's time-temperature bound

abstract:
  We give an explicit expression for the frequencies of slowly damped
quasinormal modes of near-extreme Kerr black holes. It follows from this
expression that the near-extreme Kerr holes obey the Hod's bound: in the limit
of maximal rotation, $\lim \sup \omega_{IS}/T\leq \pi / \hbar$, where $\omega
_{IS}$ is the decay rate of the slowest decaying quasinormal mode, $T$ is the
black hole temperature. On the other hand, the bound is not saturated in the
sense that $\lim \inf \omega_{IS}/T< \pi /\hbar$ is a strict inequality. {\it
It remains unclear} whether the bound is saturated in the sense that $\lim \sup
\omega_{IS}/T= \pi /\hbar$.


title: A Census of Baryons in Galaxy Clusters and Groups

abstract:
  We determine the contribution of stars in galaxies, intracluster stars, and
the intracluster medium to the total baryon budget in nearby galaxy clusters
and groups. We find that the baryon mass fraction (f_b) within r500 is constant
for systems with M500 between 6e13 and 1e15 Msun. Although f_b is lower than
the WMAP value, the shortfall is on the order of both the observational
systematic uncertainties and the depletion of baryons within r500 that is
predicted by simulations. The data therefore provide no compelling evidence for
undetected baryonic components, particularly any that vary in importance with
cluster mass. A unique feature of the current analysis is direct inclusion of
the contribution of intracluster light (ICL) in the baryon budget. The increase
in X-ray gas mass fraction with increasing total mass is entirely accounted for
by a decrease in the total stellar mass fraction, supporting the argument that
the behavior of both the stellar and X-ray gas components is dominated by a
decrease in star formation efficiency in more massive environments. Within just
the stellar component, the fraction of the total stellar luminosity in the BCG
and ICL decreases as velocity dispersion increases, suggesting that the BCG+ICL
component, and in particular the dominant ICL component, grows less efficiently
in higher mass environments. The degree to which this behavior arises from our
sample selection, which favored systems with central, giant elliptical
galaxies, remains unclear. A more robust result is the identification of low
mass groups with large BCG+ICL components, demonstrating that the creation of
intracluster stars does not require a massive cluster environment. Within r500
and r200, the BCG+ICL contributes on average 40% and 33% of the total stellar
light, respectively.


title: On Vojta's $1+\epsilon$ Conjecture

abstract:
  I gave a geometric proof of Vojta's 1 + epsilon conjecture.
  Some gaps in the published paper were spotted and kindly pointed out to me by
Paul Vojta. These were addressed in "Erratum".


title:
Ground-state cooling of a micromechanical oscillator: generalized
  framework for cold damping and cavity-assisted cooling schemes

abstract:
  We provide a general framework to describe cooling of a micromechanical
oscillator to its quantum ground state by means of radiation-pressure coupling
with a driven optical cavity. We apply it to two experimentally realized
schemes, back-action cooling via a detuned cavity and cold-damping
quantum-feedback cooling, and we determine the ultimate quantum limits of both
schemes for the full parameter range of a stable cavity. While both allow to
reach the oscillator's quantum ground state, we find that back-action cooling
is more efficient in the good cavity limit, i.e. when the cavity bandwidth is
smaller than the mechanical frequency, while cold damping is more suitable for
the bad cavity limit. The results of previous treatments are recovered as
limiting cases of specific parameter regimes.

categories: quant-ph cond-mat.mes-hall gr-qc physics.optics


title: How to find neutral leptons of the nuMSM?

abstract:
  An extension of the Standard Model by three singlet fermions with masses
smaller than the electroweak scale allows to explain simultaneously neutrino
oscillations, dark matter and baryon asymmetry of the Universe. We discuss the
properties of neutral leptons in this model and the ways they can be searched
for in particle physics experiments. We establish, in particular, a lower and
an upper bound on the strength of interaction of neutral leptons coming from
cosmological considerations and from the data on neutrino oscillations. We
analyse the production of neutral leptons in the decays of different mesons and
in $pp$ collisions. We study in detail decays of neutral leptons and establish
a lower bound on their mass coming from existing experimental data and Big Bang
Nucleosynthesis. We argue that the search for a specific missing energy signal
in kaon decays would allow to strengthen considerably the bounds on neutral
fermion couplings and to find or definitely exclude them below the kaon
threshold. To enter into cosmologically interesting parameter range for masses
above kaon mass the dedicated searches similar to CERN PS191 experiment would
be needed with the use of intensive proton beams. We argue that the use of
CNGS, NuMI, T2K or NuTeV beams could allow to search for singlet leptons below
charm in a large portion of the parameter space of the nuMSM. The search of
singlet fermions in the mass interval 2-5 GeV would require a considerable
increase of the intensity of proton accelerators or the detailed analysis of
kinematics of more than 10^{10} B-meson decays.


title: Astrophysics in 2006

abstract:
  The fastest pulsar and the slowest nova; the oldest galaxies and the youngest
stars; the weirdest life forms and the commonest dwarfs; the highest energy
particles and the lowest energy photons. These were some of the extremes of
Astrophysics 2006. We attempt also to bring you updates on things of which
there is currently only one (habitable planets, the Sun, and the universe) and
others of which there are always many, like meteors and molecules, black holes
and binaries.


title: Imaging the Two Gaps of the High-TC Superconductor Pb-Bi2Sr2CuO6+x

abstract:
  The nature of the pseudogap state, observed above the superconducting
transition temperature TC in many high temperature superconductors, is the
center of much debate. Recently, this discussion has focused on the number of
energy gaps in these materials. Some experiments indicate a single energy gap,
implying that the pseudogap is a precursor state. Others indicate two,
suggesting that it is a competing or coexisting phase. Here we report on
temperature dependent scanning tunneling spectroscopy of Pb-Bi2Sr2CuO6+x. We
have found a new, narrow, homogeneous gap that vanishes near TC, superimposed
on the typically observed, inhomogeneous, broad gap, which is only weakly
temperature dependent. These results not only support the two gap picture, but
also explain previously troubling differences between scanning tunneling
microscopy and other experimental measurements.


title: Fibers of tropicalization

abstract:
  We use functoriality of tropicalization and the geometry of projections of
subvarieties of tori to show that the fibers of the tropicalization map are
dense in the Zariski topology. For subvarieties of tori over fields of
generalized power series, points in each tropical fiber are obtained
"constructively" using Kedlaya's transfinite version of Newton's method.


title: The Spectrum of Gravitational Radiation from Primordial Turbulence

abstract:
  Energy injection into the early universe can induce turbulent motions of the
primordial plasma, which in turn act as a source for gravitational radiation.
Earlier work computed the amplitude and characteristic frequency of the relic
gravitational wave background, as a function of the total energy injected and
the stirring scale of the turbulence. This paper computes the frequency
spectrum of relic gravitational radiation from a turbulent source of the
stationary Kolmogoroff form which acts for a given duration, making no other
approximations. We also show that the limit of long source wavelengths,
commonly employed in aeroacoustic problems, is an excellent approximation. The
gravitational waves from cosmological turbulence around the electroweak energy
scale will be detectable by future space-based laser interferometers for a
substantial range of turbulence parameters.


title:
Itinerant to localized transition of f electrons in antiferromagnetic
  superconductor UPd2Al3

abstract:
  Electrons in solids have been conventionally classified as either band-like
itinerant ones or atomic-like localized ones depending on their properties. For
heavy Fermion (HF) compounds, however, the f electrons show both itinerant and
localized behaviours depending on temperature. Above the characteristic
temperature T*, which is typically of the order of few K to few tens K, their
magnetic properties are well described by the ionic f-electron models,
suggesting that the f-electrons behave as 'localized' electrons. On the other
hand, well below T*, their Fermi surfaces (FS's) have been observed by
magneto-oscillatory techniques, and generally they can be explained well by the
'itinerant' f-electron model. These two models assume totally different natures
of felectrons, and how they transform between localized and itinerant state as
a function of temperatures has never been understood on the level of their
electronic structures. Here we have studied the band structure of the HF
antiferromagnetic superconductor UPd2Al3 well below and above T* by
angle-resolved photoelectron spectroscopy (ARPES), and revealed the temperature
dependence of the electronic structure. We have found that the f-bands, which
form the FS's at low temperatures are excluded from FS's at high temperatures.
The present results demonstrate how the same f-electrons show both itinerant
and localized behaviours on the level of electronic structure, and provide an
important information for the unified description of the localized and
itinerant nature of HF compounds.


title: Two-dimensional two-component plasma with adsorbing impurities

abstract:
  We study the behavior of the two-dimensional two-component plasma in the
presence of some adsorbing impurities. Using a solvable model, we find analytic
expressions for the thermodynamic properties of the plasma such as the $n$-body
densities, the grand potential, and the pressure. We specialize in the case
where there are one or two adsorbing point impurities in the plasma, and in the
case where there are one or two parallel adsorbing lines. In the former case we
study the effective interaction between the impurities, due to the charge
redistribution around them. The latter case is a model for electrodes with
adsorbing sticky sites on their surface.


title: The heavy quark search at the LHC

abstract:
  We explore further the discovery potential for heavy quarks at the LHC, with
emphasis on the $t'$ and $b'$ of a sequential fourth family associated with
electroweak symmetry breaking. We consider QCD multijets, $t\bar{t}+\rm{jets}$,
$W+\rm{jets}$ and single $t$ backgrounds using event generation based on
improved matrix elements and low sensitivity to the modeling of initial state
radiation. We exploit a jet mass technique for the identification of
hadronically decaying $W$'s and $t$'s, to be used in the reconstruction of the
$t'$ or $b'$ mass. This along with other aspects of event selection can reduce
backgrounds to very manageable levels. It even allows a search for both $t'$
and $b'$ in the absence of $b$-tagging, of interest for the early running of
the LHC. A heavy quark mass of order 600 GeV is motivated by the connection to
electroweak symmetry breaking, but our analysis is relevant for any new heavy
quarks with weak decay modes.


title: Melting tungsten nanoparticles: a molecular dynamics study

abstract:
  We report a molecular dynamics simulation of melting of tungsten (W)
nanoparticles. The modified embedded atom method (MEAM) interatomic potentials
are used to describe the interaction between tungsten atoms. The melting
temperature of unsupported tungsten nanoparticles of different sizes are found
to decrease as the size of the particles decreases. The melting temperature
obtained in the present study is approximately a decreasing function of inverse
radius, in a good agreement with the predictions of thermodynamic models. We
also observed that the melting of a W nanoparticle is preceded by the
premelting of its outer skin at a temperature lower than its melting
temperature.


title:
Equation of state of isospin-asymmetric nuclear matter in relativistic
  mean-field models with chiral limits

abstract:
  Using in-medium hadron properties according to the Brown-Rho scaling due to
the chiral symmetry restoration at high densities and considering naturalness
of the coupling constants, we have newly constructed several relativistic
mean-field Lagrangians with chiral limits. The model parameters are adjusted
such that the symmetric part of the resulting equation of state at supra-normal
densities is consistent with that required by the collective flow data from
high energy heavy-ion reactions, while the resulting density dependence of the
symmetry energy at sub-saturation densities agrees with that extracted from the
recent isospin diffusion data from intermediate energy heavy-ion reactions. The
resulting equations of state have the special feature of being soft at
intermediate densities but stiff at high densities naturally. With these
constrained equations of state, it is found that the radius of a 1.4$M_\odot$
canonical neutron star is in the range of 11.9 km$\leq$R$\leq$13.1 km, and the
maximum neutron star mass is around 2.0$M_\odot$ close to the recent
observations.


title: The Large Sieve Inequality for Quadratic Polynomial Amplitudes

abstract:
  We provide here a modest improvement upon a large sieve inequality for
quadratic polynomial amplitudes orginally due to Liangyi Zhao.


title:
General Quantum Modeling of Combining Concepts: A Quantum Field Model in
  Fock Space

abstract:
  We extend a quantum model in Hilbert space developed in Aerts (2007a) into a
quantum field theoric model in Fock space for the modeling of the combination
of concepts. Items and concepts are represented by vectors in Fock space and
membership weights of items are modeled by quantum probabilities. We apply this
theory to model the disjunction of concepts and show that the predictions of
our theory for the membership weights of items regarding the disjunction of
concepts match with great accuracy the complete set of results of an experiment
conducted by Hampton (1988b). It are the quantum effects of interference and
superposition of that are at the origin of the effects of overextension and
underextension observed by Hampton as deviations from a classical use of the
disjunction. It is essential for the perfect matches we obtain between the
predictions of the quantum field model and Hampton's experimental data that
items can be in superpositions of `different numbers states' which proves that
the genuine structure of quantum field theory is needed to match predictions
with experimental data.


title:
Magnetic focusing of charge carriers from spin-split bands: Semiclassics
  of a Zitterbewegung effect

abstract:
  We present a theoretical study of the interplay between cyclotron motion and
spin splitting of charge carriers in solids. While many of our results apply
more generally, we focus especially on discussing the Rashba model describing
electrons in the conduction band of asymmetric semiconductor heterostructures.
Appropriate semiclassical limits are distinguished that describe various
situations of experimental interest. Our analytical fomulae, which take full
account of Zeeman splitting, are used to analyse recent magnetic-focusing data.
Surprisingly, it turns out that the Rashba effect can dominate the splitting of
cyclotron orbits even when the Rashba and Zeeman spin-splitting energies are of
the same order. We also find that the origin of spin-dependent cyclotron motion
can be traced back to Zitterbewegung-like oscillatory dynamics of charge
carriers from spin-split bands. The relation between the two phenomena is
discussed, and we estimate the effect of Zitterbewegung-related corrections to
the charge carriers' canonical position.


title:
Magnetar Driven Bubbles and the Origin of Collimated Outflows in
  Gamma-ray Bursts

abstract:
  We model the interaction between the wind from a newly formed rapidly
rotating magnetar and the surrounding supernova shock and host star. The
dynamics is modeled using the two-dimensional, axisymmetric thin-shell
equations. In the first ~10-100 seconds after core collapse the magnetar
inflates a bubble of plasma and magnetic fields behind the supernova shock. The
bubble expands asymmetrically because of the pinching effect of the toroidal
magnetic field, just as in the analogous problem of the evolution of pulsar
wind nebulae. The degree of asymmetry depends on E_mag/E_tot. The correct value
of E_mag/E_tot is uncertain because of uncertainties in the conversion of
magnetic energy into kinetic energy at large radii in relativistic winds; we
argue, however, that bubbles inflated by newly formed magnetars are likely to
be significantly more magnetized than their pulsar counterparts. We show that
for a ratio of magnetic to total power supplied by the central magnetar
L_mag/L_tot ~ 0.1 the bubble expands relatively spherically. For L_mag/L_tot ~
0.3, however, most of the pressure in the bubble is exerted close to the
rotation axis, driving a collimated outflow out through the host star. This can
account for the collimation inferred from observations of long-duration
gamma-ray bursts (GRBs). Outflows from magnetars become increasingly
magnetically dominated at late times, due to the decrease in neutrino-driven
mass loss as the young neutron star cools. We thus suggest that the
magnetar-driven bubble initially expands relatively spherically, enhancing the
energy of the associated supernova, while at late times it becomes
progressively more collimated, producing the GRB.


title: Gravitational Corrections to the Energy-Levels of a Hydrogen Atom

abstract:
  The first order perturbations of the energy levels of a hydrogen atom in
central internal gravitational field are investigated. The internal
gravitational field is produced by the mass of the atomic nucleus. The energy
shifts are calculated for the relativistic 1S, 2S, 2P, 3S, 3P, 3D, 4S and 4P
levels with Schwarzschild metric. The calculated results show that the
gravitational corrections are sensitive to the total angular momentum quantum
number.


title: Statistics of jamming in the discharge of a 2-D Silo

abstract:
  Jamming and avalanche statistics are studied in a simulation of the discharge
of a polydisperse ensemble of disks from a 2-D silo. Exponential distributions
are found for the avalanche sizes for all sizes of the exit opening, in
agreement with reported experiments. The average avalanche size grows quite
fast with the size of the exit opening. Data for this growth agree better with
a critical divergence with a large critical exponent, as reported for 3-D
experiments, than with the exponential growth reported for 2-D experiments.


title: Nonlocal Double-Slit Interference with Pseudothermal Light

abstract:
  We perform a nonlocal double-slit interference experiment with pseudothermal
light. The experimental result exhibits a typical double-slit interference
fringe in the intensity correlation measurement, in agreement with the
theoretical analysis by means of the property of the second-order spatial
correlation of field.


title:
Secure quantum key distribution network with Bell states and local
  unitary operations

abstract:
  We propose a theoretical scheme for secure quantum key distribution network
following the ideas in quantum dense coding. In this scheme, the server of the
network provides the service for preparing and measuring the Bell states, and
the users encodes the states with local unitary operations. For preventing the
server from eavesdropping, we design a decoy when the particle is transmitted
between the users. It has high capacity as one particle carries two bits of
information and its efficiency for qubits approaches 100%. Moreover, it is not
necessary for the users to store the quantum states, which makes this scheme
more convenient for application than others.


title:
The Detection and Characterization of cm Radio Continuum Emission from
  the Low-mass Protostar L1014-IRS

abstract:
  Observations by the Cores to Disk Legacy Team with the Spitzer Space
Telescope have identified a low luminosity, mid-infrared source within the
dense core, Lynds 1014, which was previously thought to harbor no internal
source. Followup near-infrared and submillimeter interferometric observations
have confirmed the protostellar nature of this source by detecting scattered
light from an outflow cavity and a weak molecular outflow. In this paper, we
report the detection of cm continuum emission with the VLA. The emission is
characterized by a quiescent, unresolved 90 uJy 6 cm source within 0.2" of the
Spitzer source. The spectral index of the quiescent component is $\alpha =
0.37\pm 0.34$ between 6 cm and 3.6 cm. A factor of two increase in 6 cm
emission was detected during one epoch and circular polarization was marginally
detected at the $5\sigma$ level with Stokes {V/I} $= 48 \pm 16$% . We have
searched for 22 GHz H2O maser emission toward L1014-IRS, but no masers were
detected during 7 epochs of observations between June 2004 and December 2006.
L1014-IRS appears to be a low-mass, accreting protostar which exhibits cm
emission from a thermal jet or a wind, with a variable non-thermal emission
component. The quiescent cm radio emission is noticeably above the correlation
of 3.6 cm and 6 cm luminosity versus bolometric luminosity, indicating more
radio emission than expected. We characterize the cm continuum emission in
terms of observations of other low-mass protostars, including updated
correlations of centimeter continuum emission with bolometric luminosity and
outflow force, and discuss the implications of recent larger distance estimates
on the physical attributes of the protostar and dense molecular core.


title:
Efficient quantum cryptography network without entanglement and quantum
  memory

abstract:
  An efficient quantum cryptography network protocol is proposed with
d-dimension polarized photons, without resorting to entanglement and quantum
memory. A server on the network, say Alice, provides the service for preparing
and measuring single photons whose initial state are |0>. The users code the
information on the single photons with some unitary operations. For preventing
the untrustworthy server Alice from eavesdropping the quantum lines, a
nonorthogonal-coding technique (decoy-photon technique) is used in the process
that the quantum signal is transmitted between the users. This protocol does
not require the servers and the users to store the quantum state and almost all
of the single photons can be used for carrying the information, which makes it
more convenient for application than others with present technology. We also
discuss the case with a faint laser pulse.


title: Warped Leptogenesis with Dirac Neutrino Masses

abstract:
  We show how leptogenesis can occur at the TeV scale with neutrinos that
possess almost purely Dirac masses and negligible Majorana mass contributions
as a consequence of the small wavefunction overlap in a warped fifth dimension.
Lepton number violation at the Planck scale is introduced via a Majorana mass
term on the Planck brane. Such a Majorana mass operator leads to the small mass
splitting of otherwise degenerate Kaluza-Klein excited states on the TeV brane.
This tiny mass splitting can compensate for the small Yukawa couplings to give
a CP asymmetry large enough to produce the sufficient baryon asymmetry from the
decay of the nearly degenerate neutrino Kaluza-Klein states. In this way the
standard baryogenesis via leptogenesis scenario can naturally occur at the TeV
scale without the need for a high mass scale.


title: A Tighter Analysis of Setcover Greedy Algorithm for Test Set

abstract:
  Setcover greedy algorithm is a natural approximation algorithm for test set
problem. This paper gives a precise and tighter analysis of performance
guarantee of this algorithm. The author improves the performance guarantee
$2\ln n$ which derives from set cover problem to $1.1354\ln n$ by applying the
potential function technique. In addition, the author gives a nontrivial lower
bound $1.0004609\ln n$ of performance guarantee of this algorithm. This lower
bound, together with the matching bound of information content heuristic,
confirms the fact information content heuristic is slightly better than
setcover greedy algorithm in worst case.


title: Nonlinarity of Boolean functions and hyperelliptic curves

abstract:
  We study the nonlinearity of functions defined on a finite field with 2^m
elements which are the trace of a polynomial of degree 7 or more general
polynomials. We show that for m odd such functions have rather good
nonlinearity properties. We use for that recent results of Maisner and Nart
about zeta functions of supersingular curves of genus 2. We give some criterion
for a vectorial function not to be almost perfect nonlinear.


title: Measurement of Dust Optical Properties in Coalsack

abstract:
  We have used FUSE and Voyager observations of dust scattered starlight in the
neighborhood of the Coalsack Nebula to derive the optical constants of the dust
grains. The albedo is consistent with a value of $0.28 \pm 0.04$ and the phase
function asymmetry factor with a value of $0.61 \pm 0.07$ throughout the
spectral range from 900 -- 1200 \AA, in agreement with previous determinations
as well as theoretical predictions. We have now observed two regions (Ophiuchus
and Coalsack) with intense diffuse background radiation and in both cases have
found that the emission is due to light from nearby hot stars scattered by a
relatively thin foreground cloud, with negligible contribution from the
background molecular cloud.


title:
Search for low lying dipole strength in the neutron rich nucleus
  $^{26}$Ne

abstract:
  Coulomb excitation of the exotic neutron-rich nucleus $^{26}$Ne on a
$^{nat}$Pb target was measured at 58 A.MeV in order to search for low-lying E1
strength above the neutron emission threshold. Data were also taken on an
$^{nat}$Al target to estimate the nuclear contribution. The radioactive beam
was produced by fragmentation of a 95 A.MeV $^{40}$Ar beam delivered by the
RIKEN Research Facility. The set-up included a NaI gamma-ray array, a charged
fragment hodoscope and a neutron wall. Using the invariant mass method in the
$^{25}$Ne+n channel, we observe a sizable amount of E1 strength between 6 and
10 MeV. The reconstructed $^{26}$Ne angular distribution confirms its E1
nature. A reduced dipole transition probability of B(E1)=0.49$\pm$0.16
$e^2fm^2$ is deduced. For the first time, the decay pattern of low-lying
strength in a neutron-rich nucleus is obtained. The results are discussed in
terms of a pygmy resonance centered around 9 MeV.


title: GRI: The Gamma-Ray Imager mission

abstract:
  With the INTEGRAL observatory, ESA has provided a unique tool to the
astronomical community revealing hundreds of sources, new classes of objects,
extraordinary views of antimatter annihilation in our Galaxy, and fingerprints
of recent nucleosynthesis processes. While INTEGRAL provides the global
overview over the soft gamma-ray sky, there is a growing need to perform
deeper, more focused investigations of gamma-ray sources. In soft X-rays a
comparable step was taken going from the Einstein and the EXOSAT satellites to
the Chandra and XMM/Newton observatories. Technological advances in the past
years in the domain of gamma-ray focusing using Laue diffraction have paved the
way towards a new gamma-ray mission, providing major improvements regarding
sensitivity and angular resolution. Such a future Gamma-Ray Imager will allow
studies of particle acceleration processes and explosion physics in
unprecedented detail, providing essential clues on the innermost nature of the
most violent and most energetic processes in the Universe.


title: Non-radial oscillations of the rapidly rotating Be star HD 163868

abstract:
  We study the pulsational stability of the rapidly rotating Be star HD 163868
using a newly developed 2D oscillation code which takes the Coriolis force
fully into account and compare our results with observations (MOST) and recent
other stability analyses of this ~ 6 Msun star. We find both prograde and
retrograde overstable modes (although more prograde than retrograde modes) and
confirm the existence of low degree odd r-modes destabilised by the
kappa-mechanism. The ultra-low frequency modes that could not be explained in a
previous analysis are interpreted as high degree, retrograde m=1 modes. A
reasonably good fit to the observed oscillation spectrum is possible if we
assume that only even modes are observed. This requires a nearly equator-on
view of the observed star, consistent with the measured high v sin i value of
250 km/s.


title: On Einstein clusters as galactic dark matter halos

abstract:
  We consider global and gravitational lensing properties of the recently
suggested Einstein clusters of WIMPs as galactic dark matter halos. Being
tangential pressure dominated, Einstein clusters are strongly anisotropic
systems which can describe any galactic rotation curve by specifying the
anisotropy. Due to this property, Einstein clusters may be considered as dark
matter candidates. We analyse the stability of the Einstein clusters against
both radial and non-radial pulsations, and we show that the Einstein clusters
are dynamically stable. With the use of the Buchdahl type inequalities for
anisotropic bodies, we derive upper limits on the velocity of the particles
defining the cluster. These limits are consistent with those obtained from
stability considerations. The study of light deflection shows that the
gravitational lensing effect is slightly smaller for the Einstein clusters, as
compared to the singular isothermal density sphere model for dark matter.
Therefore lensing observations may discriminate, at least in principle, between
Einstein cluster and other dark matter models.


title:
Scalability and Optimisation of a Committee of Agents Using Genetic
  Algorithm

abstract:
  A population of committees of agents that learn by using neural networks is
implemented to simulate the stock market. Each committee of agents, which is
regarded as a player in a game, is optimised by continually adapting the
architecture of the agents using genetic algorithms. The committees of agents
buy and sell stocks by following this procedure: (1) obtain the current price
of stocks; (2) predict the future price of stocks; (3) and for a given price
trade until all the players are mutually satisfied. The trading of stocks is
conducted by following these rules: (1) if a player expects an increase in
price then it tries to buy the stock; (2) else if it expects a drop in the
price, it sells the stock; (3)and the order in which a player participates in
the game is random. The proposed procedure is implemented to simulate trading
of three stocks, namely, the Dow Jones, the Nasdaq and the S&P 500. A linear
relationship between the number of players and agents versus the computational
time to run the complete simulation is observed. It is also found that no
player has a monopolistic advantage.


title: The supermassive black hole in NGC4486a detected with SINFONI at the VLT

abstract:
  The near-infrared integral field spectrograph SINFONI at the ESO VLT opens a
new window for the study of central supermassive black holes. With a near-IR
spatial resolution similar to HST optical and the ability to penetrate dust it
provides the possibility to explore the low-mass end of the M-sigma relation
(sigma<120km/s) where so far very few black hole masses were measured with
stellar dynamics. With SINFONI we observed the central region of the
low-luminosity elliptical galaxy NGC4486a at a spatial resolution of ~0.1arcsec
in the K band. The stellar kinematics was measured with a maximum penalised
likelihood method considering the region around the CO absorption band heads.
We determined a black hole mass of M_BH=1.25^{+0.75}_{-0.79} x 10^7 M_sun (90%
C.L.) using the Schwarzschild orbit superposition method including the full
2-dimensional spatial information. This mass agrees with the predictions of the
M-sigma relation, strengthening its validity at the lower sigma end.


title: Finite Element Model Updating Using Response Surface Method

abstract:
  This paper proposes the response surface method for finite element model
updating. The response surface method is implemented by approximating the
finite element model surface response equation by a multi-layer perceptron. The
updated parameters of the finite element model were calculated using genetic
algorithm by optimizing the surface response equation. The proposed method was
compared to the existing methods that use simulated annealing or genetic
algorithm together with a full finite element model for finite element model
updating. The proposed method was tested on an unsymmetri-cal H-shaped
structure. It was observed that the proposed method gave the updated natural
frequen-cies and mode shapes that were of the same order of accuracy as those
given by simulated annealing and genetic algorithm. Furthermore, it was
observed that the response surface method achieved these results at a
computational speed that was more than 2.5 times as fast as the genetic
algorithm and a full finite element model and 24 times faster than the
simulated annealing.


title: Dynamic Model Updating Using Particle Swarm Optimization Method

abstract:
  This paper proposes the use of particle swarm optimization method (PSO) for
finite element (FE) model updating. The PSO method is compared to the existing
methods that use simulated annealing (SA) or genetic algorithms (GA) for FE
model for model updating. The proposed method is tested on an unsymmetrical
H-shaped structure. It is observed that the proposed method gives updated
natural frequencies the most accurate and followed by those given by an updated
model that was obtained using the GA and a full FE model. It is also observed
that the proposed method gives updated mode shapes that are best correlated to
the measured ones, followed by those given by an updated model that was
obtained using the SA and a full FE model. Furthermore, it is observed that the
PSO achieves this accuracy at a computational speed that is faster than that by
the GA and a full FE model which is faster than the SA and a full FE model.


title: Modeling and Controlling Interstate Conflict

abstract:
  Bayesian neural networks were used to model the relationship between input
parameters, Democracy, Allies, Contingency, Distance, Capability, Dependency
and Major Power, and the output parameter which is either peace or conflict.
The automatic relevance determination was used to rank the importance of input
variables. Control theory approach was used to identify input variables that
would give a peaceful outcome. It was found that using all four controllable
variables Democracy, Allies, Capability and Dependency; or using only
Dependency or only Capabilities avoids all the predicted conflicts.