title: Ferromagnetism and Lattice Distortions in the Perovskite YTiO$_3$

abstract:
  The thermodynamic properties of the ferromagnetic perovskite YTiO$_3$ are
investigated by thermal expansion, magnetostriction, specific heat, and
magnetization measurements. The low-temperature spin-wave contribution to the
specific heat, as well as an Arrott plot of the magnetization in the vicinity
of the Curie temperature $T_C\simeq27$ K, are consistent with a
three-dimensional Heisenberg model of ferromagnetism. However, a magnetic
contribution to the thermal expansion persists well above $T_C$, which
contrasts with typical three-dimensional Heisenberg ferromagnets, as shown by a
comparison with the corresponding model system EuS. The pressure dependences of
$T_C$ and of the spontaneous moment $M_s$ are extracted using thermodynamic
relationships. They indicate that ferromagnetism is strengthened by uniaxial
pressures $\mathbf{p}\parallel \mathbf{a}$ and is weakened by uniaxial
pressures $\mathbf{p}\parallel \mathbf{b},\mathbf{c}$ and hydrostatic pressure.
Our results show that the distortion along the $a$- and $b$-axes is further
increased by the magnetic transition, confirming that ferromagnetism is favored
by a large GdFeO$_3$-type distortion. The c-axis results however do not fit
into this simple picture, which may be explained by an additional
magnetoelastic effect, possibly related to a Jahn-Teller distortion.


title: Recent progress in lattice QCD at finite density

abstract:
  We review recent progress in lattice QCD at finite density. The phase diagram
of QCD and the equation of state at finite temperature and density are
discussed. In particular, we focus on the critical point terminating a first
order phase transition line in the high density region. The critical point is
one of the most interesting features that may be discovered in heavy-ion
collision experiments. We summarize the current discussion on the existence of
a critical point in the QCD phase diagram and discuss some attempts to find the
critical point by numerical simulations.


title: On combinatorial formulas for the characters of Hecke algebras

abstract:
  Hecke algebras are beautiful q-extensions of Coxeter groups. In this paper,
we prove several results on their characters, with an emphasis on characters
induced from trivial and sign representations of parabolic subalgebras. While
most of the results in type A are known, our proofs are of a combinatorial
nature, and generalize to (partial) results in types B and C. We also present
complete descriptions of such characters for type I.


title: Mountain trail formation and the active walker model

abstract:
  We extend the active walker model to address the formation of paths on
gradients, which have been observed to have a zigzag form. Our extension
includes a new rule which prohibits direct descent or ascent on steep inclines,
simulating aversion to falling. Further augmentation of the model stops walkers
from changing direction very rapidly as that would likely lead to a fall. The
extended model predicts paths with qualitatively similar forms to the observed
trails, but only if the terms suppressing sudden direction changes are
included. The need to include terms into the model that stop rapid direction
change when simulating mountain trails indicates that a similar rule should
also be included in the standard active walker model.


title:
Semiclassical analysis of the Loop Quantum Gravity volume operator: I.
  Flux Coherent States

abstract:
  The volume operator plays a pivotal role for the quantum dynamics of Loop
Quantum Gravity (LQG), both in the full theory and in truncated models adapted
to cosmological situations coined Loop Quantum Cosmology (LQC). It is therefore
crucial to check whether its semiclassical limit coincides with the classical
volume operator plus quantum corrections. In the present article we investigate
this question by generalizing and employing previously defined coherent states
for LQG which derive from a cylindrically consistently defined complexifier
operator which is the quantization of a known classical function. These
coherent states are not normalizable due to the non separability of the LQG
Hilbert space but they define uniquely define cut off states depending on a
finite graph. The result of our analysis is that the expectation value of the
volume operator with respect to coherent states depending on a graph with only
n valent verticies reproduces its classical value at the phase space point at
which the coherent state is peaked only if n = 6. In other words, the
semiclassical sector of LQG defined by those states is described by graphs with
cubic topology! This has some bearing on current spin foam models which are all
based on four valent boundary spin networks.


title:
Uniaxial Strain in Graphene by Raman Spectroscopy: G peak splitting,
  Gruneisen Parameters and Sample Orientation

abstract:
  Graphene is the two-dimensional building block for carbon allotropes of every
other dimensionality. Since its experimental discovery, graphene continues to
attract enormous interest, in particular as a new kind of matter, in which
electron transport is governed by a Dirac-like wave equation, and as a model
system for studying electronic and phonon properties of other, more complex,
graphitic materials[1-4]. Here, we uncover the constitutive relation of
graphene and probe new physics of its optical phonons, by studying its Raman
spectrum as a function of uniaxial strain. We find that the doubly degenerate
E2g optical mode splits in two components, one polarized along the strain and
the other perpendicular to it. This leads to the splitting of the G peak into
two bands, which we call G+ and G-, by analogy with the effect of curvature on
the nanotube G peak[5-7]. Both peaks red shift with increasing strain, and
their splitting increases, in excellent agreement with first-principles
calculations. Their relative intensities are found to depend on light
polarization, which provides a useful tool to probe the graphene
crystallographic orientation with respect to the strain. The singly degenerate
2D and 2D' bands also red shift, but do not split for small strains. We study
the Gruneisen parameters for the phonons responsible for the G, D and D' peaks.
These can be used to measure the amount of uniaxial or biaxial strain,
providing a fundamental tool for nanoelectronics, where strain monitoring is of
paramount importance[8, 9]


title: Comparison of Data Imputation Techniques and their Impact

abstract:
  Missing and incomplete information in surveys or databases can be imputed
using different statistical and soft-computing techniques. This paper
comprehensively compares auto-associative neural networks (NN), neuro-fuzzy
(NF) systems and the hybrid combinations the above methods with hot-deck
imputation. The tests are conducted on an eight category antenatal survey and
also under principal component analysis (PCA) conditions. The neural network
outperforms the neuro-fuzzy system for all tests by an average of 5.8%, while
the hybrid method is on average 15.9% more accurate yet 50% less
computationally efficient than the NN or NF systems acting alone. The global
impact assessment of the imputed data is performed by several statistical
tests. It is found that although the imputed accuracy is high, the global
effect of the imputed data causes the PCA inter-relationships between the
dataset to become altered. The standard deviation of the imputed dataset is on
average 36.7% lower than the actual dataset which may cause an incorrect
interpretation of the results.


title:
Nonuniform Center Bunching and the Genericity of Ergodicity among $C^1$
  Partially Hyperbolic Symplectomorphisms

abstract:
  We introduce the notion of nonuniform center bunching for partially
hyperbolic diffeomorphims, and extend previous results by Burns--Wilkinson and
Avila--Santamaria--Viana. Combining this new technique with other
constructions, we prove that $C^1$-generic partially hyperbolic
symplectomorphisms are ergodic. We also construct new examples of stably
ergodic partially hyperbolic diffeomorphisms.


title:
Hall equilibrium of thin Keplerian disks embedded in mixed poloidal and
  toroidal magnetic fields

abstract:
  Axisymmetric steady-state weakly ionized Hall-MHD Keplerian thin disks are
investigated by using asymptotic expansions in the small disk aspect ratio
\epsilon. The model incorporates the azimuthal and poloidal components of the
magnetic fields in the leading order in \epsilon. The disk structure is
described by an appropriate Grad-Shafranov equation for the poloidal flux
function \psi that involves two arbitrary functions of \psi for the toroidal
and poloidal currents. The flux function is symmetric about the midplane and
satisfies certain boundary conditions at the near-horizontal disk edges. The
boundary conditions model the combined effect of the primordial as well as the
dipole-like magnetic fields. An analytical solution for the Hall equilibrium is
achieved by further expanding the relevant equations in an additional small
parameter \delta that is inversely proportional to the Hall parameter. It is
thus found that the Hall equilibrium disks fall into two types: Keplerian disks
with (i) small (Rd ~\delta^0) and (ii) large (Rd > \delta^k, k > 0) radius of
the disk. The numerical examples that are presented demonstrate the richness
and great variety of magnetic and density configurations that may be achieved
under the Hall-MHD equilibrium.


title: On Coloring of graph fractional powers

abstract:
  \noindent Let $G$ be a simple graph. For any $k\in N$, the $k-$power of $G$
is a simple graph $G^k$ with vertex set $V(G)$ and edge set $\{xy:d_G(x,y)\leq
k\}$ and the $k-$subdivision of $G$ is a simple graph $G^{\frac{1}{k}}$, which
is constructed by replacing each edge of $G$ with a path of length $k$. So we
can introduce the $m-$power of the $n-$subdivision of $G$, as a fractional
power of $G$, that is denoted by $G^{\frac{m}{n}}$. In other words
$G^{\frac{m}{n}}:=(G^{\frac{1}{n}})^m$. \noindent In this paper some results
about the coloring of $G^{\frac{m}{n}}$ are presented when $G$ is a simple and
connected graph and $\frac{m}{n}<1$.


title:
The dissociation catastrophe in fluctuating-charge models and its
  implications for the concept of atomic electronegativity

abstract:
  We have recently developed the QTPIE (charge transfer with polarization
current equilibration) fluctuating-charge model, a new model with correct
dissociation behavior for nonequilibrium geometries. The correct asymptotics
originally came at the price of representing the solution in terms of
charge-transfer variables instead of atomic charges. However, we have found an
exact reformulation of fluctuating-charge models in terms of atomic charges
again, which is made possible by the symmetries of classical electrostatics. We
show how this leads to the distinguishing between two types of atomic
electronegativities in our model. While one is a intrinsic property of
individual atoms, the other takes into account the local electrical
surroundings. This suggests that this distinction could resolve some confusion
surrounding the concept of electronegativity as to whether it is an intrinsic
property of elements, or otherwise.


title:
Size-extensive polarizabilities with intermolecular charge transfer in a
  fluctuating-charge model

abstract:
  Fluctuating-charge models have been used to model polarization effects in
molecular mechanics methods. However, they overestimate polarizabilities in
large systems. Previous attempts to remedy this have been at the expense of
forbidding intermolecular charge-transfer. Here, we investigate this lack of
size-extensivity and show that the neglect of terms arising from charge
conservation is partly responsible; these terms are also vital for maintaining
the correct translational symmetries of the dipole moment and polarizability
that classical electrostatic theory requires. Also, QTPIE demonstrates
linear-scaling polarizabilities when coupling the external electric field in a
manner that treats its potential as a perturbation of the atomic
electronegativities. Thus for the first time, we have a fluctuating-charge
model that predicts size-extensive dipole polarizabilities, yet allows
intermolecular charge-transfer.


title:
Feshbach Shape Resonance for High Tc Pairing in Superlattices of Quantum
  Stripes and Quantum Wells

abstract:
  The Feshbach shape resonances in the interband pairing in superconducting
superlattices of quantum wells or quantum stripes is shown to provide the
mechanism for high Tc superconductivity. This mechanism provides the Tc
amplification driven by the architecture of material: superlattices of quantum
wells (intercalated graphite or diborides) and superlattices of quantum stripes
(doped high Tc cuprate perovskites) where the chemical potential is tuned to a
Van Hove-Lifshitz singularity (vHs) in the electronic energy spectrum of the
superlattice associated with the change of the Fermi surface dimensionality in
one of the subbands.


title: The Haar State on SU_q(N)

abstract:
  Using matrix corepresentations on SL_q(N) and SU_q(N) we derive a Haar state
on SU_q(N) which is nearly identical to that on SU_q(2). This allows us to
create an orthonormal basis for the vector space of coordinate functions on
SU_q(N).


title: Photoproduction of hypernuclei within the quark-meson coupling model

abstract:
  We study the photoproduction of the ^12{_Lambda}B hypernucleus within a fully
covariant effective Lagrangian based model, employing Lambda bound state
spinors derived from the latest quark-meson coupling model. The kaon production
vertex is described via creation, propagation and decay of N*(1650), N*(1710),
and N*(1720) intermediate baryonic resonant states in the initial collision of
the photon with a target proton in the incident channel. The parameters of the
resonance vertices are fixed by describing the total and differential cross
section data on the elementary gamma (p, K+) Lambda reaction in the energy
regime relevant to the hypernuclear production. It is found that the
hypernuclear production cross sections calculated with the quark model based
hyperon bound state spinors differ significantly from those obtained with the
phenomenological Dirac single particle wave functions.


title:
Emergent Time Scale in Entangled Quantum Dynamics of Ultracold Molecules
  in Optical Lattices

abstract:
  We derive a novel lattice Hamiltonian, the \emph{Molecular Hubbard
Hamiltonian} (MHH), which describes the essential many body physics of
closed-shell ultracold heteronuclear molecules in their absolute ground state
in a quasi-one-dimensional optical lattice. The MHH is explicitly
time-dependent, making a dynamic generalization of the concept of quantum phase
transitions necessary. Using the Time-Evolving Block Decimation (TEBD)
algorithm to study entangled dynamics, we demonstrate that, in the case of hard
core bosonic molecules at half filling, the MHH exhibits an emergent time scale
over which spatial entanglement grows, crystalline order appears, and
oscillations between rotational states self-damp into an asymptotic
superposition. We show that this time scale is a non-monotonic function of the
physical parameters describing the lattice. We also point out that experimental
mapping of the static phase boundaries of the MHH can be used to measure the
molecular polarizability tensor.


title:
A novel method for computing torus amplitudes for $\mathbb{Z}_{N}$
  orbifolds without the unfolding technique

abstract:
  A novel method for computing torus amplitudes in orbifold compactifications
is suggested. It applies universally for every Abelian $\mathbb{Z}_{N}$
orbifold without requiring the unfolding technique. This method follows from
the possibility of obtaining integrals over fundamental domains of every Hecke
congruence subgroup $\Gamma_{0}[N]$ by computing contour integrals over
one-dimensional curves uniformly distributed in these domains.


title:
Benchmark 3-Flavor Pattern and Small Universal Flavor-Electroweak
  Parameter

abstract:
  The electroweak theory contains too many empirical parameters. Most of them
are related to the flavor part of particle physics. In this paper we discuss a
relevant simple idea: the complicated system of actual dimensionless, small
versus large, quantities in elementary particle flavor phenomenology is small
deviated from an explicitly defined benchmark flavor pattern with no tuning
parameters. One small empirical universal dimensionless parameter measures this
deviation. Its possible physical connections are discussed. As inferences,
quasi-degenerate neutrino type with mass scale m = 0.16-0.18 eV, neutrino and
quark mixing matrices, large neutrino oscillation 3-flavor hierarchy and
quark-neutrino complementarity are predicted.


title:
From Majorana theory of atomic autoionization to Feshbach resonances in
  high temperature superconductors

abstract:
  The Ettore Majorana paper - Theory of incomplete P triplets- published in
1931, focuses on the role of selection rules for the non-radiative decay of two
electron excitations in atomic spectra, involving the configuration interaction
between discrete and continuum channels. This work is a key step for
understanding the 1935 work of Ugo Fano on the asymmetric lineshape of two
electron excitations and the 1958 Herman Feshbach paper on the shape resonances
in nuclear scattering arising from configuration interaction between many
different scattering channels. The Feshbach resonances are today of high
scientific interest in many different fields and in particular for ultracold
gases and high Tc superconductivity.


title:
Numerical Evidence of Small Coherent Subsystems at Low Temperatures in
  Light Harvesting Complex II

abstract:
  The extent of exciton coherence in protein-pigment complexes has significant
implications for the initial light harvesting step in photosynthetic organisms.
In this work we model the main antenna protein of photosystem II, namely light
harvesting complex II (LHC-II), with a single-exciton Hamiltonian with sites
coupled via dipole-dipole interaction, with linear coupling to a dissipative
phonon bath. With appropriate parameters, Monte Carlo path integral (MCPI)
results of the exciton coherence length from 1 K to 500 K show that at
thermodynamic equilibrium, an exciton in LHC-II is localized mostly on 2 single
chlorophyll pigment sites, with persistent short-range coherence over the A2-B2
pair, A3-B3 pair and B1-B5-B6 triplet. Quasi-adiabatic path integral (QUAPI)
calculations of the subsystems mentioned above show a smooth, incoherent
relaxation towards thermodynamic equilibrium. The results obtained imply that
with the exception of small coherent subsystems at cryogenic temperatures,
excitons in LHC-II are more localized than in the analogous light harvesting
complex II (LH-II) of the purple bacterium Rs. molischianum, which may be
expected from the lower symmetry of the former.


title: Analysis of Energy Efficiency in Fading Channels under QoS Constraints

abstract:
  Energy efficiency in fading channels in the presence of Quality of Service
(QoS) constraints is studied. Effective capacity, which provides the maximum
arrival rate that a wireless channel can sustain while satisfying statistical
QoS constraints, is considered. Spectral efficiency--bit energy tradeoff is
analyzed in the low-power and wideband regimes by employing the effective
capacity formulation, rather than the Shannon capacity. Through this analysis,
energy requirements under QoS constraints are identified. The analysis is
conducted under two assumptions: perfect channel side information (CSI)
available only at the receiver and perfect CSI available at both the receiver
and transmitter. In particular, it is shown in the low-power regime that the
minimum bit energy required under QoS constraints is the same as that attained
when there are no such limitations. However, this performance is achieved as
the transmitted power vanishes. Through the wideband slope analysis, the
increased energy requirements at low but nonzero power levels in the presence
of QoS constraints are determined. A similar analysis is also conducted in the
wideband regime, and minimum bit energy and wideband slope expressions are
obtained. In this regime, the required bit energy levels are found to be
strictly greater than those achieved when Shannon capacity is considered.
Overall, a characterization of the energy-bandwidth-delay tradeoff is provided.


title:
Molecular communication: Physically realistic models and achievable
  information rates

abstract:
  Molecular communication is a biologically-inspired method of communication
with attractive properties for microscale and nanoscale devices. In molecular
communication, messages are transmitted by releasing a pattern of molecules at
a transmitter, which propagate through a fluid medium towards a receiver. In
this paper, molecular communication is formulated as a mathematical
communication problem in an information-theoretic context. Physically realistic
models are obtained, with sufficient abstraction to allow manipulation by
communication and information theorists. Although mutual information in these
channels is intractable, we give sequences of upper and lower bounds on the
mutual information which trade off complexity and performance, and present
results to illustrate the feasibility of these bounds in estimating the true
mutual information.


title: Strongly Contracting Geodesics in Outer Space

abstract:
  We study the Lipschitz metric on Outer Space and prove that fully irreducible
elements of Out(F_n) act by hyperbolic isometries with axes which are strongly
contracting. As a corollary, we prove that the axes of fully irreducible
automorphisms in the Cayley graph of Out(F_n) are stable, meaning that a
quasi-geodesic with endpoints on the axis stays within a bounded distance from
the axis.


title:
Determinants of perfect complexes and Euler characteristics in relative
  K_0-groups

abstract:
  We study the K_0 and K_1-groups of exact and triangulated categories of
perfect complexes, and we apply the results to show how determinant functors on
triangulated categories can be used for the construction of Euler
characteristics in relative algebraic K_0-groups.


title: To Cooperate, or Not to Cooperate in Imperfectly-Known Fading Channels

abstract:
  In this paper, communication over imperfectly-known fading channels with
different degrees of cooperation is studied. The three-node relay channel is
considered. It is assumed that communication starts with the network training
phase in which the receivers estimate the fading coefficients of their
respective channels. In the data transmission phase, amplify-and-forward and
decode-and-forward relaying schemes are employed. For different cooperation
protocols, achievable rate expressions are obtained. These achievable rate
expressions are then used to find the optimal resource allocation strategies.
In particular, the fraction of total time or bandwidth that needs to be
allocated to the relay for best performance is identified. Under a total power
constraint, optimal allocation of power between the source and relay is
investigated. Finally, bit energy requirements in the low-power regime are
studied.


title:
Pilot-Symbol-Assisted Communications with Noncausal and Causal Wiener
  Filters

abstract:
  In this paper, pilot-assisted transmission over time-selective flat fading
channels is studied. It is assumed that noncausal and causal Wiener filters are
employed at the receiver to perform channel estimation with the aid of training
symbols sent periodically by the transmitter. For both filters, the variances
of estimate errors are obtained from the Doppler power spectrum of the channel.
Subsequently, achievable rate expressions are provided. The training period,
and data and training power allocations are jointly optimized by maximizing the
achievable rate expressions. Numerical results are obtained by modeling the
fading as a Gauss-Markov process. The achievable rates of causal and noncausal
filtering approaches are compared. For the particular ranges of parameters
considered in the paper, the performance loss incurred by using a causal filter
as opposed to a noncausal filter is shown to be small. The impact of aliasing
that occurs in the undersampled version of the channel Doppler spectrum due to
fast fading is analyzed. Finally, energy-per-bit requirements are investigated
in the presence of noncausal and causal Wiener filters.


title:
Investigating the potential of the Pan-Planets project using Monte Carlo
  simulations

abstract:
  Using Monte Carlo simulations we analyze the potential of the upcoming
transit survey Pan-Planets. The analysis covers the simulation of realistic
light curves (including the effects of ingress/egress and limb-darkening) with
both correlated and uncorrelated noise as well as the application of a
box-fitting-least-squares detection algorithm. In this work we show how
simulations can be a powerful tool in defining and optimizing the survey
strategy of a transiting planet survey. We find the Pan-Planets project to be
competitive with all other existing and planned transit surveys with the main
power being the large 7 square degree field of view. In the first year we
expect to find up to 25 Jupiter-sized planets with periods below 5 days around
stars brighter than V = 16.5 mag. The survey will also be sensitive to planets
with longer periods and planets with smaller radii. After the second year of
the survey, we expect to find up to 9 Warm Jupiters with periods between 5 and
9 days and 7 Very Hot Saturns around stars brighter than V = 16.5 mag as well
as 9 Very Hot Neptunes with periods from 1 to 3 days around stars brighter than
i' = 18.0 mag.


title:
Achievable Rates and Training Optimization for Fading Relay Channels
  with Memory

abstract:
  In this paper, transmission over time-selective, flat fading relay channels
is studied. It is assumed that channel fading coefficients are not known a
priori. Transmission takes place in two phases: network training phase and data
transmission phase. In the training phase, pilot symbols are sent and the
receivers employ single-pilot MMSE estimation or noncausal Wiener filter to
learn the channel. Amplify-and-Forward (AF) and Decode-and-Forward (DF)
techniques are considered in the data transmission phase and achievable rate
expressions are obtained. The training period, and data and training power
allocations are jointly optimized by using the achievable rate expressions.
Numerical results are obtained considering Gauss-Markov and lowpass fading
models. Achievable rates are computed and energy-per-bit requirements are
investigated. The optimal power distributions among pilot and data symbols are
provided.


title: Warping the young stellar disc in the Galactic Centre

abstract:
  We examine influence of the circum-nuclear disc (CND) upon the orbital
evolution of young stars in the Galactic Centre. We show that gravity of the
CND causes precession of the orbits which is highly sensitive upon the
semi-major axis and inclination. We consider such a differential precession
within the context of an ongoing discussion about the origin of the young stars
and suggest a possibility that all of them have originated in a thin disc which
was partially destroyed due to the influence of the CND during the period of
~6Myr.


title: [On the jet contribution to the AGN cosmic energy budget

abstract:
  Black holes release energy via the production of photons in their accretion
discs but also via the acceleration of jets. We investigate the relative
importance of these two paths over cosmic time by determining the mechanical
luminosity function (LF) of radio sources and by comparing it to a previous
determination of the bolometric LF of active galactic nuclei (AGN) from X-ray,
optical and infrared observations. The mechanical LF of radio sources is
computed in two steps: the determination of the mechanical luminosity as a
function of the radio luminosity and its convolution with the radio LF of radio
sources. Even with the large uncertainty deriving from the former, we can
conclude that the contribution of jets is unlikely to be much larger than 10%
of the AGN energy budget at any cosmic epoch.


title:
Stellar Population Models and Individual Element Abundances II: Stellar
  Spectra and Integrated Light Models

abstract:
  The first paper in this series explored the effects of altering the chemical
mixture of the stellar population on an element by element basis on stellar
evolutionary tracks and isochrones to the end of the red giant branch. This
paper extends the discussion by incorporating the fully consistent synthetic
stellar spectra with those isochrone models in predicting integrated colors,
Lick indices, and synthetic spectra. Older populations display element ratio
effects in their spectra at higher amplitude than younger populations. In
addition, spectral effects in the photospheres of stars tend to dominate over
effects from isochrone temperatures and lifetimes, but, further, the
isochrone-based effects that are present tend to fall along the age-metallicity
degeneracy vector, while the direct stellar spectral effects usually show
considerable orthogonality.


title: Interacting SUSY-singlet matter in non-relativistic Chern-Simons theory

abstract:
  We construct an example of supersymmetric Chern-Simons-matter theory with a
matter field transforming as a singlet representation of the supersymmetry
algebra, where the bosonic and fermionic degrees of freedom do not match. This
is obtained as a non-relativistic limit of the N=2 Chern-Simons-matter theory
in 1+2 dimensions, where the particle and anti-particle coexist. We also study
the index to investigate the mimatch of bosonic and fermionic degrees of
freedom.


title:
Discovery of very low amplitude 9-minute multiperiodic pulsations in the
  magnetic Ap star HD 75445

abstract:
  We present our discovery of pulsational radial-velocity variations in the
cool Ap star HD 75445, an object spectroscopically similar to the bright,
rapidly-oscillating Ap (roAp) star gamma Equ. Based on high-resolution
time-series spectroscopy obtained with the HARPS spectrometer at the European
Southern Observatory 3.6-m telescope, we detected oscillations in Nd II and Nd
III lines with a period close to 9 min and amplitudes of 20-30 m/s. Substantial
variation in the pulsational amplitude during our 3.8 h observing run reveals
the presence of at least three excited non-radial modes. The detection of
extremely low amplitude pulsations in HD 75445 indicates that the roAp
excitation mechanism produces variability in the radial velocity amplitude of
between a few tens m/s and several km/s. This supports the idea that many, if
not all, cool Ap stars occupying the roAp instability strip may harbour
non-radial pulsations, which currently remain undetected due to their small
photometric and radial-velocity amplitudes.


title: Reconstructing Patchy Reionization from the Cosmic Microwave Background

abstract:
  We introduce a new statistical technique for extracting the inhomogeneous
reionization signal from future high-sensitivity measurements of the cosmic
microwave background temperature and polarization fields. If reionization is
inhomogeneous, then the optical depth to recombination will be a function
tau(n) of position on the sky. Anisotropies in tau(n) alter the statistics of
the observed CMB via several physical mechanisms: screening of the surface of
last scattering, generation of new polarization via Thomson scattering from
reionization bubbles, and the kinetic Sunyaev-Zel'dovich effect. We construct a
quadratic estimator for the modes of the tau field. This estimator separates
the patchy reionization signal from the CMB in the form of a noisy map, which
can be cross-correlated with other probes of reionization or used as a
standalone probe. A future satellite experiment with sufficient sensitivity and
resolution to measure the lensed B-mode on most of the sky can constrain key
parameters of patchy reionization, such as the duration of the patchy epoch or
the mean bubble radius, at the ~10% level.


title: The warped young stellar disc in the Galactic Centre

abstract:
  Within the central parsec of the Galaxy, several tens of young stars orbiting
a central supermassive black hole are observed. A subset of these stars forms a
coherently rotating disc. Other observations reveal a massive molecular torus
which lies at a radius ~1.5pc from the centre. In this paper we consider the
gravitational influence of the molecular torus upon the stars of the stellar
disc. We derive an analytical formula for the rate of precession of individual
stellar orbits and we show that it is highly sensitive upon the orbital
semi-major axis and inclination with respect to the plane of the torus as well
as on the mass of the torus. Assuming that both the stellar disc and the
molecular torus are stable on the time-scale >6Myr, we constrain the mass of
the torus and its inclination with respect to the young stellar disc. We
further suggest that all young stars observed in the Galactic Centre may have a
common origin in a single coherently rotating structure with an opening angle
<5deg, which was partially destroyed (warped) during its lifetime by the
gravitational influence of the molecular torus.


title: Dilution Robustness for Mean Field Ferromagnets

abstract:
  In this work we compare two different random dilution of a mean field
ferromagnet: the first model is built on a Bernoulli-diluted network while the
second lives on a Poisson-diluted network. While it is known that the two
models have in the thermodynamic limit the same free energy we investigate on
the structural constraints that the two models must fulfill. We rigorously
derive for each model the set of identities for the multi-overlaps distribution
using different methods for the two dilutions: constraints in the former model
are obtained by studying the consequences of the self-averaging of the internal
energy density, while in the latter are obtained by a stochastic-stability
technique. Finally we prove that the identities emerging in the two models are
the same, showing "robustness" of the ferromagnetic properties of diluted
networks with respect to the details of dilution.


title:
Double quasars: probes of black hole scaling relationships and merger
  scenarios

abstract:
  We analyze the available sample of double quasars, and investigate their
physical properties. Our sample comprises 85 pairs, selected from the Sloan
Digital Sky Survey (SDSS). We derive physical parameters for the engine and the
host, and model the dynamical evolution of the pair. First, we compare
different scaling relationships between massive black holes and their hosts
(bulge mass, velocity dispersion, and their possible redshift dependences), and
discuss their consistency. We then compute dynamical friction timescales for
the double quasar systems to investigate their frequency and their agreement
with scenarios for quasar triggering. Comparing typical merging timescales to
expected quasar lifetimes, the fraction of double quasars should be roughly a
factor of 10 larger than observed. Additionally, we find that, depending on the
correlations between black holes and their hosts, the occurrence of double
quasars could be redshift-dependent. Comparison of our models to the SDSS
quasar catalog suggests that double quasars should be more common at high
redshift. We compare the typical separations at which double quasars are
observed to the predictions of merger simulations. We find that the
distribution of physical separations peaks at ~30 kpc, with a tail at larger
separations (~100-200 kpc). These large separation pairs are instead consistent
with unequal mass mergers where gas is dynamically perturbed during the first
pericentric passage, but the gas reaches the black hole only at the next
apocenter, where the pair is observed.


title:
Landau Damping and Alfven Eigenmodes of Neutron Star Torsion
  Oscillations

abstract:
  Torsion oscillations of the neutron star crust are Landau damped by the
Alfven continuum in the bulk. For strong magnetic fields (in magnetars),
undamped Alfven eigenmodes appear.


title: On exceptional nilpotents in semisimple Lie algebras

abstract:
  We classify all pairs (m,e), where m is a positive integer and e is a
nilpotent element of a semisimple Lie algebra, which arise in the
classification of simple rational W-algebras.


title: Bounding the dimension of bipartite quantum systems

abstract:
  Let us consider the set of joint quantum correlations arising from
two-outcome local measurements on a bipartite quantum system. We prove that no
finite dimension is sufficient to generate all these sets. We approach the
problem in two different ways by constructing explicit examples for every
dimension d, which demonstrates that there exist bipartite correlations that
necessitate d-dimensional local quantum systems in order to generate them. We
also show that at least 10 two-outcome measurements must be carried out by the
two parties altogether so as to generate bipartite joint correlations not
achievable by two-dimensional local systems. The smallest explicit example we
found involves 11 settings.


title:
Mean Curvature Motion of Graphs with Constant Contact Angle at a Free
  Boundary

abstract:
  We consider the motion by mean curvature of an $n$-dimensional graph over a
time-dependent domain in $\mathbb{R}^n$, intersecting $\mathbb{R}^n$ at a
constant angle. In the general case, we prove local existence for the
corresponding quasilinear parabolic equation with a free boundary, and derive a
continuation criterion based on the second fundamental form. If the initial
graph is concave, we show this is preserved, and that the solution exists only
for finite time. This corresponds to a symmetric version of mean curvature
motion of a network of hypersurfaces with triple junctions, with constant
contact angle at the junctions.


title:
Nonlinear gravitons in 4-D general relativity by expansion about the
  Kodama state

abstract:
  In this paper we provide a possible realization of Penrose's idea of
nonlinear gravitons using a new description of nonmetric general relativity. In
the addressal of issues surrounding the normalizability of the Kodama state and
its reliability as a ground state for gravity, we expand the theory in
fluctuations about the Kodama state. This produces a theory of complex gravity
with a well-defined Hilbert space structure, whose quantization we carry out
both at the linearized level and in the full nonlinear theory. The results of
this paper demonstrate the preservation of the physical degrees of freedom of
the full nonlinear theory under linearization, as well provide a Hilbert space
of states of the former annihilated by the quantum Hamiltonian constraint.


title: Reversible biholomorphic germs

abstract:
  Let $G$ be a group. We say that an element $f\in G$ is {\em reversible in}
$G$ if it is conjugate to its inverse, i.e. there exists $g\in G$ such that
$g^{-1}fg=f^{-1}$. We denote the set of reversible elements by $R(G)$. For
$f\in G$, we denote by $R_f(G)$ the set (possibly empty) of {\em reversers} of
$f$, i.e. the set of $g\in G$ such that $g^{-1}fg=f^{-1}$. We characterise the
elements of $R(G)$ and describe each $R_f(G)$, where $G$ is the the group of
biholomorphic germs in one complex variable. That is, we determine all
solutions to the equation $ f\circ g\circ f = g$, in which $f$ and $g$ are
holomorphic functions on some neighbourhood of the origin, with $f(0)=g(0)=0$
and $f'(0)\not=0\not=g'(0)$.


title:
Uniqueness of near-horizon geometries of rotating extremal AdS(4) black
  holes

abstract:
  We consider stationary extremal black hole solutions of the Einstein-Maxwell
equations with a negative cosmological constant in four dimensions. We
determine all non-static axisymmetric near-horizon geometries (with
non-toroidal horizon topology) and all static near-horizon geometries for black
holes of this kind. This allows us to deduce that the most general near-horizon
geometry of an asymptotically globally AdS(4) rotating extremal black hole, is
the near-horizon limit of extremal Kerr-Newman-AdS(4). We also identify the
subset of near-horizon geometries which are supersymmetric. Finally, we show
which physical quantities of extremal black holes may be computed from the
near-horizon limit alone, and point out a simple formula for the entropy of the
known supersymmetric AdS(4) black hole. Analogous results are presented in the
case of vanishing cosmological constant.


title:
Model for the magnetoresistance and Hall coefficient of inhomogeneous
  graphene

abstract:
  We show that when bulk graphene breaks into n-type and p-type puddles, the
in-plane resistivity becomes strongly field dependent in the presence of a
perpendicular magnetic field, even if homoge- neous graphene has a
field-independent resistivity. We calculate the longitudinal resistivity
\rho_{xx} and Hall resistivity \rho_{xy} as a function of field for this
system, using the effective-medium approximation. The conductivity tensors of
the individual puddles are calculated using a Boltzmann approach suit- able for
the band structure of graphene near the Dirac points. The resulting resistivity
agrees well with experiment, provided that the relaxation time is weakly
field-dependent. The calculated Hall resistivity has the sign of the majority
carrier and vanishes when there are equal number of n and p type puddles.


title: The Iron abundance in Galactic Planetary Nebulae

abstract:
  We constrain the iron abundance in a sample of 33 low-ionization Galactic
planetary nebulae (PNe) using [Fe III] lines and correcting for the
contribution of higher ionization states with ionization correction factors
(ICFs) that take into account uncertainties in the atomic data. We find very
low iron abundances in all the objects, suggesting that more than 90% of their
iron atoms are condensed onto dust grains. This number is based on the solar
iron abundance and implies a lower limit on the dust-to-gas mass ratio, due
solely to iron, of M_dust/M_gas>1.3x10^{-3} for our sample. The depletion
factors of different PNe cover about two orders of magnitude, probably
reflecting differences in the formation, growth, or destruction of their dust
grains. However, we do not find any systematic difference between the gaseous
iron abundances calculated for C-rich and O-rich PNe, suggesting similar iron
depletion efficiencies in both environments. The iron abundances of our sample
PNe are similar to those derived following the same procedure for a group of 10
Galactic H II regions. These high depletion factors argue for high depletion
efficiencies of refractory elements onto dust grains both in molecular clouds
and AGB stars, and low dust destruction efficiencies both in interstellar and
circumstellar ionized gas.


title:
Explicit soliton asymptotics for the Korteweg-de Vries equation on the
  half-line

abstract:
  Integrable PDEs on the line can be analyzed by the so-called Inverse
Scattering Transform (IST) method. A particularly powerful aspect of the IST is
its ability to predict the large $t$ behavior of the solution. Namely, starting
with initial data $u(x,0)$, IST implies that the solution $u(x,t)$ asymptotes
to a collection of solitons as $t \to \infty$, $x/t = O(1)$; moreover the
shapes and speeds of these solitons can be computed from $u(x,0)$ using only
{\it linear} operations. One of the most important developments in this area
has been the generalization of the IST from initial to initial-boundary value
(IBV) problems formulated on the half-line. It can be shown that again $u(x,t)$
asymptotes into a collection of solitons, where now the shapes and the speeds
of these solitons depend both on $u(x,0)$ and on the given boundary conditions
at $x = 0$. A major complication of IBV problems is that the computation of the
shapes and speeds of the solitons involves the solution of a {\it nonlinear}
Volterra integral equation. However, for a certain class of boundary
conditions, called linearizable, this complication can be bypassed and the
relevant computation is as effective as in the case of the problem on the line.
Here, after reviewing the general theory for KdV, we analyze three different
types of linearizable boundary conditions. For these cases, the initial
conditions are: (a) restrictions of one and two soliton solutions at $t = 0$;
(b) profiles of certain exponential type; (c) box-shaped profiles. For each of
these cases, by computing explicitly the shapes and the speeds of the
asymptotic solitons, we elucidate the influence of the boundary.


title:
Compact groups in theory and practice - III. Compact groups of galaxies
  in the Sixth Data Release of the Sloan Digital Sky Survey

abstract:
  We present the largest publicly available catalogue of compact groups of
galaxies identified using the original selection criteria of Hickson, selected
from the Sixth Data Release (DR6) of the Sloan Digital Sky Survey (SDSS). We
identify 2297 compact groups down to a limiting magnitude of r = 18
(~0.24groups degree^{-2}), and 74791 compact groups down to a limiting
magnitude of r = 21 (~6.7groups degree^{-2}). This represents 0.9% of all
galaxies in the SDSS DR6 at these magnitude levels. Contamination due to gross
photometric errors has been removed from the bright sample of groups, and we
estimate it is present in the large sample at the 14% level. Spectroscopic
information is available for 4131 galaxies in the bright catalogue (43%
completeness), and we find that the median redshift of these groups is z_{med}
= 0.09. The median line-of-sight velocity dispersion within the compact groups
from the bright catalogue is sigma_{LOS} ~ 230km/s and their typical
inter-galactic separations are of order 50 - 100kpc. We show that the fraction
of groups with interloping galaxies identified as members is in good agreement
with the predictions from our previous study of a mock galaxy catalogue, and we
demonstrate how to select compact groups such that the interloper fraction is
well defined and minimized. This observational dataset is ideal for large
statistical studies of compact groups, the role of environment on galaxy
evolution, and the effect of galaxy interactions in determining galaxy
morphology.


title:
Superconductivity close to the Mott state: From condensed-matter systems
  to superfluidity in optical lattices

abstract:
  Since the discovery of high-temperature superconductivity in 1986 by Bednorz
and Mueller, great efforts have been devoted to finding out how and why it
works. From the d-wave symmetry of the order parameter, the importance of
antiferromagnetic fluctuations, and the presence of a mysterious pseudogap
phase close to the Mott state, one can conclude that high-Tc superconductors
are clearly distinguishable from the well-understood BCS superconductors. The
d-wave superconducting state can be understood through a Gutzwiller-type
projected BCS wave-function. In this review article, we revisit the Hubbard
model at half-filling and focus on the emergence of exotic superconductivity
with d-wave symmetry in the vicinity of the Mott state, starting from ladder
systems and then studying the dimensional crossovers to higher dimensions. This
allows to confirm that short-range antiferromagnetic fluctuations can mediate
superconductivity with d-wave symmetry. Ladders are also nice prototype systems
allowing to demonstrate the truncation of the Fermi surface and the emergence
of a Resonating Valence Bond (RVB) state with preformed pairs in the vicinity
of the Mott state. In two dimensions, a similar scenario emerges from
renormalization group arguments. We also discuss theoretical predictions for
the d-wave superconducting phase as well as the pseudogap phase, and address
the crossover to the overdoped regime. Finally, cold atomic systems with
tunable parameters also provide a complementary insight into this outstanding
problem.


title:
Ten New and Updated Multi-planet Systems, and a Survey of Exoplanetary
  Systems

abstract:
  We present the latest velocities for 10 multi-planet systems, including a
re-analysis of archival Keck and Lick data, resulting in improved velocities
that supersede our previously published measurements. We derive updated orbital
fits for ten Lick and Keck systems, including two systems (HD 11964, HD 183263)
for which we provide confirmation of second planets only tentatively identified
elsewhere, and two others (HD 187123, and HD 217107) for which we provide a
major revision of the outer planet's orbit. We compile orbital elements from
the literature to generate a catalog of the 28 published multiple-planet
systems around stars within 200 pc. From this catalog we find several
intriguing patterns emerging: - Including those systems with long-term radial
velocity trends, at least 28% of known planetary systems appear to contain
multiple planets. - Planets in multiple-planet systems have somewhat smaller
eccentricities than single planets. - The distribution of orbital distances of
planets in multi-planet systems and single planets are inconsistent:
single-planet systems show a pile-up at P ~ 3 days and a jump near 1 AU, while
multi-planet systems show a more uniform distribution in log-period. In
addition, among all planetary systems we find: - There may be an emerging,
positive correlation between stellar mass and giant-planet semi-major axis. -
Exoplanets more massive than Jupiter have eccentricities broadly distributed
across 0 < e < 0.5, while lower-mass exoplanets exhibit a distribution peaked
near e = 0.


title: Diffractive Production of Jets and Vector Bosons at the Tevatron

abstract:
  Recent results on diffractive dijet and vector boson production and exclusive
dijet production from the Collider Detector at Fermilab (CDF) experiment are
presented.


title: On the structure of the category O for W-algebras

abstract:
  W-algebra (of finite type) W is a certain associative algebra associated with
a semisimple Lie algebra, say g, and its nilpotent element, say e. The goal of
this paper is to study the category O for W introduced by Brundan, Goodwin and
Kleshchev. We establish an equivalence of this category with certain category
of g-modules. In the case when e is of principal Levi type (this is always so
when g is of type A) the category of g-modules in interest is the category of
generalized Whittaker modules introduced McDowel and studied by Milicic-Soergel
and Backelin.


title: Directed Self-Assembly of Quantum Dots in a Nematic Liquid Crystal

abstract:
  Self organizing anisotropic nematic liquid crystals (LCs) induce
self-assembly on quantum dots (QDs) to form one-dimensional chains along the
nematic director. Spatial ordering of QDs, achieved in the nematic LC matrix,
can be controlled in a preferred direction on application of electric fields,
gaining better self-assembly. Once the field goes off, the LC+QD system relaxes
back to the original state, revealing the intrinsic dynamics. Due to the
dielectric anisotropy of the system, this dynamic response can be captured by
studying dielectric relaxation. The studied dynamic response reveals insights
on the field-induced self-assembly mechanism and the stability of the LC+QD
system.


title: Operation of Graphene Transistors at GHz Frequencies

abstract:
  Top-gated graphene transistors operating at high frequencies (GHz) have been
fabricated and their characteristics analyzed. The measured intrinsic current
gain shows an ideal 1/f frequency dependence, indicating an FET-like behavior
for graphene transistors. The cutoff frequency fT is found to be proportional
to the dc transconductance gm of the device. The peak fT increases with a
reduced gate length, and fT as high as 26 GHz is measured for a graphene
transistor with a gate length of 150 nm. The work represents a significant step
towards the realization of graphene-based electronics for high-frequency
applications.


title: Fast phylogeny reconstruction through learning of ancestral sequences

abstract:
  Given natural limitations on the length DNA sequences, designing phylogenetic
reconstruction methods which are reliable under limited information is a
crucial endeavor. There have been two approaches to this problem:
reconstructing partial but reliable information about the tree (\cite{Mo07,
DMR08,DHJ06,GMS08}), and reaching "deeper" in the tree through reconstruction
of ancestral sequences. In the latter category, \cite{DMR06} settled an
important conjecture of M.Steel, showing that, under the CFN model of
evolution, all trees on $n$ leaves with edge lengths bounded by the Ising model
phase transition can be recovered with high probability from genomes of length
$O(\log n)$ with a polynomial time algorithm. Their methods had a running time
of $O(n^{10})$.
  Here we enhance our methods from \cite{DHJ06} with the learning of ancestral
sequences and provide an algorithm for reconstructing a sub-forest of the tree
which is reliable given available data, without requiring a-priori known bounds
on the edge lengths of the tree. Our methods are based on an intuitive minimum
spanning tree approach and run in $O(n^3)$ time. For the case of full
reconstruction of trees with edges under the phase transition, we maintain the
same sequence length requirements as \cite{DMR06}, despite the considerably
faster running time.


title:
Two-loop massive fermionic operator matrix elements and intial state QED
  corrections to e^+e^- \to \gamma^*/Z^*

abstract:
  We describe the calculation of the two--loop massive operator matrix elements
for massive external fermions. These matrix elements are needed for the
calculation of the $O(\alpha^2)$ initial state radiative corrections to
$e^+e^-$ annihilation into a neutral virtual gauge boson, based on the
renormalization group technique.


title:
The Young, Massive, Star Cluster Sandage-96 After the Explosion of SN
  2004dj in NGC 2403

abstract:
  The bright Type II-plateau supernova (SN) 2004dj occurred within the young,
massive stellar cluster Sandage-96 in a spiral arm of NGC 2403. New
multi-wavelength observations obtained with several ground-based and
space-based telescopes are combined to study the radiation from Sandage-96
after SN 2004dj faded away. Sandage-96 started to dominate the flux in the
optical bands starting September 2006 (~800 d after explosion). The optical
fluxes are equal to the pre-explosion ones within the observational
uncertainties. An optical Keck spectrum obtained ~900 d after explosion shows
the dominant blue continuum from the cluster stars shortward of 6000 \AA as
well as strong SN nebular emission lines redward. The integrated spectral
energy distribution (SED) of the cluster has been extended into the ultraviolet
region by archival XMM-Newton and new Swift observations, and compared with
theoretical models. The outer parts of the cluster have been resolved by the
Hubble Space Telescope, allowing the construction of a color-magnitude diagram.
The fitting of the cluster SED with theoretical isochrones results in cluster
ages between 10--40 Myr, depending on metallicity and the model family. The
isochrone fitting indicates that the resolved part of the cluster has a bimodal
age distribution: a younger population at ~10--16 Myr, and an older one at
~32--100 Myr which is similar to the age distribution of the nearby field
stars. These stars may have been captured from the field during the cluster
formation. The young age of Sandage-96 suggest 12 < M_prog < 20 M_\odot as the
most probable mass range for the progenitor of SN 2004dj. This is consistent
with, but perhaps slightly higher than, most of the other Type II-plateau SN
progenitor masses determined so far.


title: Characterizing the Gravitational Wave Signature from Cosmic String Cusps

abstract:
  Cosmic strings are predicted to form kinks and cusps that travel along the
string at close to the speed of light. These disturbances are radiated away as
highly beamed gravitational waves that produce a burst like pulse as the cone
of emission sweeps past an observer. Gravitational wave detectors such as the
Laser Interferometer Space Antenna (LISA) and the Laser Interferometer
Gravitational wave Observatory (LIGO) will be capable of detecting these bursts
for a wide class of string models. Such a detection would illuminate the fields
of string theory, cosmology, and relativity. Here we develop template based
Markov Chain Monte Carlo (MCMC) techniques that can efficiently detect and
characterize the signals from cosmic string cusps. We estimate how well the
signal parameters can be recovered by the advanced LIGO-Virgo network and the
LISA detector using a combination of MCMC and Fisher matrix techniques. We also
consider joint detections by the ground and space based instruments. We show
that a parallel tempered MCMC approach can detect and characterize the signals
from cosmic string cusps, and we demonstrate the utility of this approach on
simulated data from the third round of Mock LISA Data Challenges (MLDCs).


title:
Distinguishing between Planetary and Binary Interpretations of
  Microlensing Central Perturbations under Severe Finite-Source Effect

abstract:
  In the current strategy of microlensing planet searches focusing on
high-magnification events, wide and close binaries pose important sources of
contamination that imitates planetary signals. For the purpose of finding
systematic differences, we compare the patterns of central perturbations
induced by a planet and a binary companion under severe finite-source effect.
We find that the most prominent difference shows up in the morphology of the
edge features with negative excess that appear at the edge of the circle with
its center located at the caustic center and a radius equivalent to the source
radius. It is found that the feature induced a binary companion forms a
complete annulus, while the feature induced by a planet appears as several arc
segments. This difference provides a useful diagnostic for immediate
iscrimination of a planet-induced perturbation from that induced by a binary
companion, where the absence of a well-developed dip in the residual from the
single-lensing light curve at both or either of the moments of the caustic
center's entrance into and exit from the source star surface indicates that the
perturbation is produced by a planetary companion. We find that that this
difference is basically caused by the difference between the shapes of the
central caustics induced by the two different types of companions.


title:
Interferometry with independent Bose-Einstein ondensates: parity as an
  EPR/Bell quantum variable

abstract:
  When independent Bose-Einstein condensates (BEC), described quantum
mechanically by Fock (number) states, are sent into interferometers, the
measurement of the output port at which the particles are detected provides a
binary measurement, with two possible results $\pm1$. With two interferometers
and two BEC's, the parity (product of all results obtained at each
interferometer) has all the features of an Einstein-Podolsky-Rosen quantity,
with perfect correlations predicted by quantum mechanics when the settings
(phase shifts of the interferometers) are the same. When they are different,
significant violations of Bell inequalities are obtained. These violations do
not tend to zero when the number $N$ of particles increases, and can therefore
be obtained with arbitrarily large systems, but a condition is that all
particles should be detected. We discuss the general experimental requirements
for observing such effects, the necessary detection of all particles in
correlation, the role of the pixels of the CCD detectors, and that of the
alignments of the interferometers in terms of matching of the wave fronts of
the sources in the detection regions. Another scheme involving three
interferometers and three BEC's is discussed; it leads to Greenberger Horne
Zeilinger (GHZ) sign contradictions, as in the usual GHZ case with three
particles, but for an arbitrarily large number of them. Finally,
generalizations of the Hardy impossibilities to an arbitrarily large number of
particles are introduced. BEC's provide a large versality for observing
violations of local realism in a variety of experimental arrangements.


title: A giant bar induced by a merger event at z=0.4?

abstract:
  (Aims) We present a physical model of the formation of J033239.72-275154.7, a
galaxy observed at z=0.41 and characterized by a big young bar of size 6 kpc.
The study of this system is particularly interesting for understanding the
connection between mergers and bars as well as the properties and fate of this
system as it relates to disk galaxy formation. (Methods) We compare the
morphological and kinematic properties of J033239.72-275154.7, the latter
obtained by the GIRAFFE spectrograph, to those derived from the merger of two
spiral galaxies described by idealized N-body simulations including a star
formation prescription. (Results) We found that the general morphological shape
and most of the dynamical properties of the object can be well reproduced by a
model in which the satellite is initially put in a retrograde orbit and the
mass ratio of the system is 1:3. In such a scenario, a bar forms in the host
galaxy after the first passage of the satellite where an important fraction of
available gas is consumed in an induced burst. In its later evolution, however,
we find that J033239.72-275154.7, whose major progenitor was an Sab galaxy,
will probably become a S0 galaxy. This is mainly due to the violent relaxation
and the angular momentum loss experienced by the host galaxy during the merger
process, which is caused by the adopted orbital parameters. This result
suggests that the building of the Hubble sequence is significantly influenced
by the last major collision. In the present case, the merger leads to a severe
damage of the disk of the progenitor, leading to an evolution towards a more
bulge dominated galaxy.


title:
Two-component spinor techniques and Feynman rules for quantum field
  theory and supersymmetry

abstract:
  Two-component spinors are the basic ingredients for describing fermions in
quantum field theory in four space-time dimensions. We develop and review the
techniques of the two-component spinor formalism and provide a complete set of
Feynman rules for fermions using two-component spinor notation. These rules are
suitable for practical calculations of cross-sections, decay rates, and
radiative corrections in the Standard Model and its extensions, including
supersymmetry, and many explicit examples are provided. The unified treatment
presented in this review applies to massless Weyl fermions and massive Dirac
and Majorana fermions. We exhibit the relation between the two-component spinor
formalism and the more traditional four-component spinor formalism, and
indicate their connections to the spinor helicity method and techniques for the
computation of helicity amplitudes.


title:
A quasi-polynomial time approximation scheme for Euclidean capacitated
  vehicle routing

abstract:
  In the capacitated vehicle routing problem, introduced by Dantzig and Ramser
in 1959, we are given the locations of n customers and a depot, along with a
vehicle of capacity k, and wish to find a minimum length collection of tours,
each starting from the depot and visiting at most k customers, whose union
covers all the customers. We give a quasi-polynomial time approximation scheme
for the setting where the customers and the depot are on the plane, and
distances are given by the Euclidean metric.


title: Reconstructing the f(R) gravity from the holographic principle

abstract:
  An holographic f(R) gravity model of dark energy is proposed. The
correspondence between the f(R) geometrical effective energy density with the
holographic density, allows the reconstruction of the f(R) gravity in flat FRW
background in the Einstein frame. The proposed infrared cut-off for the
holographic energy density depends on two parameters which are fit using the
luminosity versus redshift data, allowing a suitable reconstruction in two
representative cases of the EoS parameter: for $\omega>-1$ and $\omega<-1$.


title: Transmission Techniques for Relay-Interference Networks

abstract:
  In this paper we study the relay-interference wireless network, in which
relay (helper) nodes are to facilitate competing information flows over a
wireless network. We examine this in the context of a deterministic wireless
interaction model, which eliminates the channel noise and focuses on the signal
interactions. Using this model, we show that almost all the known schemes such
as interference suppression, interference alignment and interference separation
are necessary for relay-interference networks. In addition, we discover a new
interference management technique, which we call interference neutralization,
which allows for over-the-air interference removal, without the transmitters
having complete access the interfering signals. We show that interference
separation, suppression, and neutralization arise in a fundamental manner,
since we show complete characterizations for special configurations of the
relay-interference network.


title:
A New Feature in the Spectrum of the Superluminous LMC Supergiant HDE
  269896

abstract:
  We have found strong selective emission of the N II 5000A complex in the
spectrum of the LMC hypergiant HDE 269896, ON9.7 Ia$^+$. Since this object also
has anomalously strong He II $\lambda$4686 emission for its spectral type, an
unusually wide range of ionization in its extended atmosphere is indicated. The
published model of this spectrum does not reproduce these emission features,
but we show that increased nitrogen and helium abundances, together with small
changes in other model parameters, can do so. The morphological and possible
evolutionary relationships of HDE 269896, as illuminated by the new spectral
features, to other denizens of the OB Zoo are discussed. This object may be in
an immediate pre-WNVL (Very Late WN) state, which is in turn the quiescent
state of at least some Luminous Blue Variables.
  More generally, the N II spectrum in HDE 269896 provides a striking
demonstration of the occurrence of two distinctly different kinds of line
behavior in O-type spectra: normal absorption lines that develop P Cygni
profiles at high wind densities, and selective emission lines from the same
ions that do not. Further analysis of these features will advance understanding
of both atomic physics and extreme stellar atmospheres.


title: Multi-Agent Reinforcement Learning and Genetic Policy Sharing

abstract:
  The effects of policy sharing between agents in a multi-agent dynamical
system has not been studied extensively. I simulate a system of agents
optimizing the same task using reinforcement learning, to study the effects of
different population densities and policy sharing. I demonstrate that sharing
policies decreases the time to reach asymptotic behavior, and results in
improved asymptotic behavior.


title: K-trivials are NCR

abstract:
  We show that for every K-trivial real X, there is no representation of a
continuous probability measure m such that X is 1-random relative to m.


title: Scarf is Ppad-Complete

abstract:
  Scarf's lemma is one of the fundamental results in combinatorics, originally
introduced to study the core of an N-person game. Over the last four decades,
the usefulness of Scarf's lemma has been demonstrated in several important
combinatorial problems seeking "stable" solutions. However, the complexity of
the computational version of Scarf's lemma (SCARF) remained open. In this
paper, we prove that SCARF is complete for the complexity class PPAD. This
proves that SCARF is as hard as the computational versions of Brouwer's fixed
point theorem and Sperner's lemma. Hence, there is no polynomial-time algorithm
for SCARF unless PPAD \subseteq P. We also show that fractional stable paths
problem and finding strong fractional kernels in digraphs are PPAD-hard.


title:
Poisson structures on the Teichmueller space of hyperbolic surfaces with
  conical points

abstract:
  In this paper two Poisson structures on the moduli space of hyperbolic
surfaces with conical points are compared: the Weil-Petersson one and the \eta
coming from the representation variety. We show that they are multiple of each
other, if the angles do not exceed 2\pi. Moreover, we exhibit an explicit
formula for \eta in terms of hyperbolic lengths of a suitable system of arcs.


title: On the classification of certain fusion categories

abstract:
  We advance the classification of fusion categories in two directions.
Firstly, we completely classify integral fusion categories -- and consequently,
semi-simple Hopf algebras -- of dimension $pq^2$, where $p$ and $q$ are
distinct primes. This case is especially interesting because it is the simplest
class of dimensions where not all integral fusion categories are
group-theoretical. Secondly, we classify a certain family of $\ZZ/3\ZZ$-graded
fusion categories, which are generalizations of the $\ZZ/2\ZZ$-graded
Tambara-Yamagami categories. Our proofs are based on the recently developed
theory of extensions of fusion categories.


title: Dilaton as the Higgs boson

abstract:
  We propose a model where the role of the electroweak Higgs field is played by
the dilaton. The model contains terms which explicitly violate gauge
invariance, however it is shown that this violation is fictitious, so that the
model is a consistent low energy effective theory. In the simplest version of
the idea the resulting low energy effective theory is the same as the top mode
standard model.


title: Angular Momentum Decomposition for an Electron

abstract:
  We calculate the orbital angular momentum of the `quark' in the scalar
diquark model as well as that of the electron in QED (to order $\alpha$). We
compare the orbital angular momentum obtained from the Jaffe-Manohar
decomposition to that obtained from the Ji relation and estimate the importance
of the vector potential in the definition of orbital angular momentum.


title: Ultracold molecules: vehicles to scalable quantum information processing

abstract:
  We describe a novel scheme to implement scalable quantum information
processing using Li-Cs molecular state to entangle $^{6}$Li and $^{133}$Cs
ultracold atoms held in independent optical lattices. The $^{6}$Li atoms will
act as quantum bits to store information, and $^{133}$Cs atoms will serve as
messenger bits that aid in quantum gate operations and mediate entanglement
between distant qubit atoms. Each atomic species is held in a separate optical
lattice and the atoms can be overlapped by translating the lattices with
respect to each other. When the messenger and qubit atoms are overlapped,
targeted single spin operations and entangling operations can be performed by
coupling the atomic states to a molecular state with radio-frequency pulses. By
controlling the frequency and duration of the radio-frequency pulses,
entanglement can either be created or swapped between a qubit messenger pair.
We estimate operation fidelities for entangling two distant qubits and discuss
scalability of this scheme and constraints on the optical lattice lasers.


title: Heavy ions and parton saturation from RHIC to LHC

abstract:
  The phenomenology of gluon saturation at small parton momentum fraction,
Bjorken-x, in the proton and in the nucleus is introduced. The
experimentally-accessible kinematic domains at the nucleus-nucleus colliders
RHIC and LHC are discussed. Finally, the saturation hints emerging from
measurements at RHIC and the perspectives for LHC are described.


title:
The HARPS search for southern extra-solar planets. XVII. Super-Earth and
  Neptune-mass planets in multiple planet systems HD47186 and HD181433

abstract:
  This paper reports on the detection of two new multiple planet systems around
solar-like stars HD47186 and HD181433. The first system includes a hot Neptune
of 22.78 M_Earth at 4.08-days period and a Saturn of 0.35 M_Jup at 3.7-years
period. The second system includes a Super-Earth of 7.5 M_Earth at 9.4-days
period, a 0.64 M$_Jup at 2.6-years period as well as a third companion of 0.54
M_Jup with a period of about 6 years. These detections increase to 20 the
number of close-in low-mass exoplanets (below 0.1 M_Jup) and strengthen the
fact that 80% of these planets are in a multiple planetary systems.


title:
Spectra and radial flow at RHIC with Tsallis statistics in a Blast-Wave
  description

abstract:
  We have implemented the Tsallis statistics in a Blast-Wave model and applied
it to mid-rapidity transverse-momentum spectra of identified particles measured
at RHIC. This new Tsallis Blast-Wave function fits the RHIC data very well for
$p_T<$3 GeV/$c$. We observed that the collective flow velocity starts from zero
in p+p and peripheral Au+Au collisions growing to 0.470 $\pm$ 0.009($c$) in
central Au+Au collisions. The $(q-1)$ parameter, which characterizes the degree
of non-equilibrium in a system, changes from $0.100\pm0.003$ in p+p to
$0.015\pm0.005$ in central Au+Au collisions, indicating an evolution from a
highly non-equilibrated system in p+p collisions toward an almost thermalized
system in central Au+Au collisions. The temperature and collective velocity are
well described by a quadratic dependence on $(q-1)$. Two sets of parameters in
our Tsallis Blast-Wave model are required to describe the meson and baryon
groups separately in p+p collisions while one set of parameters appears to fit
all spectra in central Au+Au collisions.


title: Particle production and saturation at RHIC and LHC

abstract:
  The Color Glass Condensate picture of the nuclear wave function at small-x
successfully predicted the suppressed production of high-pT particles at
forward rapidities in deuteron-gold collisions at RHIC. This triggered more
efforts which resulted in theoretical improvements and predictions for
different observables which will provide further phenomenological tests. I
review recent theoretical developments and discuss the resulting predictions.


title: Instanton Theory of Burgers Shocks and Intermittency

abstract:
  A lagrangian approach to Burgers turbulence is carried out along the lines of
the field theoretical Martin-Siggia-Rose formalism of stochastic hydrodynamics.
We derive, from an analysis based on the hypothesis of unbroken galilean
invariance, the asymptotic form of the probability distribution function of
negative velocity-differences. The origin of Burgers intermittency is found to
rely on the dynamical coupling between shocks, identified to instantons, and
non-coherent background fluctuations, which, then, cannot be discarded in a
consistent statistical description of the flow.


title: Semiclassical limits of quantized coordinate rings

abstract:
  This paper offers an expository account of some ideas, methods, and
conjectures concerning quantized coordinate rings and their semiclassical
limits, with a particular focus on primitive ideal spaces. The semiclassical
limit of a family of quantized coordinate rings of an affine algebraic variety
V consists of the classical coordinate ring O(V) equipped with an associated
Poisson structure. Conjectured relationships between primitive ideals of a
generic quantized coordinate ring A and symplectic leaves in V (relative to a
semiclassical limit Poisson structure on O(V)) are discussed, as are breakdowns
in the connections when the symplectic leaves are not algebraic. This prompts
replacement of the differential-geometric concept of symplectic leaves with the
algebraic concept of symplectic cores, and a reformulated conjecture is
proposed: The primitive spectrum of A should be homeomorphic to the space of
symplectic cores in V, and to the Poisson-primitive spectrum of O(V). Various
examples, including both quantized coordinate rings and enveloping algebras of
solvable Lie algebras, are analyzed to support the choice of symplectic cores
to replace symplectic leaves.


title: Generalized twist deformations of Poincare and Galilei Hopf algebras

abstract:
  The three new deformed Poincare Hopf algebras are constructed with use of
twist procedure. The corresponding relativistic space-times providing the sum
of canonical and Lie-algebraic type of noncommutativity are proposed. Finally,
the nonrelativistic contraction limits to the corresponding Galilei Hopf
algebras are performed.


title: Pulling self-interacting polymers in two-dimensions

abstract:
  We investigate a two-dimensional problem of an isolated self-interacting
end-grafted polymer, pulled by one end. In the thermodynamic limit, we find
that the model has only two different phases, namely a collapsed phase and a
stretched phase. We show that the phase diagram obtained by Kumar {\it at al.\}
[Phys. Rev. Lett. {\bf 98}, 128101 (2007)] for small systems, where differences
between various statistical ensembles play an important role, differ from the
phase diagram obtained here in the thermodynamic limit.


title: Missing Data using Decision Forest and Computational Intelligence

abstract:
  Autoencoder neural network is implemented to estimate the missing data.
Genetic algorithm is implemented for network optimization and estimating the
missing data. Missing data is treated as Missing At Random mechanism by
implementing maximum likelihood algorithm. The network performance is
determined by calculating the mean square error of the network prediction. The
network is further optimized by implementing Decision Forest. The impact of
missing data is then investigated and decision forrests are found to improve
the results.


title: Program for calculating bounds on the minimum rank of a graph using Sage

abstract:
  The minimum rank of a simple graph $G$ is defined to be the smallest possible
rank over all symmetric real matrices whose $ij$th entry (for $i\neq j$) is
nonzero whenever $\{i,j\}$ is an edge in $G$ and is zero otherwise. Minimum
rank is a difficult parameter to compute. However, there are now a number of
known reduction techniques and bounds that can be programmed on a computer; we
have developed a program using the open-source mathematics software Sage to
implement several techniques. In this note, we provide the source code for this
program.


title:
Combined study of gamma p to eta p and pi-p to eta n in a chiral
  constituent quark approach

abstract:
  Within a chiral constituent quark model approach, $\eta$-meson production on
the proton {\it via} electromagnetic and hadron probes are studied. With few
parameters, differential cross-section and polarized beam asymmetry for \gamma
p \to \eta p$ and differential cross section for $\pi^- p\to \eta n$ processes
are calculated and successfully compared with the data in the center-of-mass
energy range from threshold up to 2 GeV. The five known resonances
$S_{11}(1535)$, $S_{11}(1650)$, $P_{13}(1720)$, $D_{13}(1520)$, and
$F_{15}(1680)$ are found to be dominant in the reaction mechanisms in both
channels. Possible roles plaied by new resonances are also investigated and in
the photoproduction channel, significant contribution from $S_{11}$- and
$D_{15}$-resonances, with masses around 1715 MeV and 2090 MeV, respectively,
are deduced. For the so-called missing resonances, no evidence is found within
the investigated reactions. The helicity amplitudes and decay widths of $N^*
\to \pi N, \eta N$ are also presented, and found consistent with the PDG
values.


title: Internal Extinction in the SDSS Late-Type Galaxies

abstract:
  We study internal extinction of late-type galaxies in the Sloan Digital Sky
Survey. We find that the degree of internal extinction depends on both the
concentration index c and K_s-band absolute magnitude M_K. We give simple
fitting functions for internal extinction. In particular, we present analytic
formulae giving the extinction-corrected magnitudes from the observed optical
parameters. For example, the extinction-corrected r-band absolute magnitude can
be obtained by M_{r,0}=-20.77 +(-1+\sqrt{1+4\Delta
(M_{r,obs}+20.77+4.93\Delta)})/2\Delta, where \Delta =
0.236\{1.35(c-2.48)^2-1.14\}\log(a/b), c=R_{90}/R_{50} is the the concentration
index, and a/b is the isophotal axis ratio of the 25 mag/arcsec^2 isophote in
the i-band. The 1\sigma error in M_{r,0} is 0.21{\rm log}(a/b). The late-type
galaxies with very different inclinations are found to trace almost the same
sequence in the (u-r)-$M_r$ diagram when our prescriptions for extinction
correction are applied. We also find that (u-r) color can be a third
independent parameter that determines the degree of internal extinction.


title: Heavy Ions at LHC: A Quest for Quark-Gluon Plasma

abstract:
  Quantum Chromo Dynamics (QCD), the theory of strong interactions, predicts a
transition of the usual matter to a new phase of matter, called Quark-Gluon
Plasma (QGP), at sufficiently high temperatures. The non-perturbative technique
of defining a theory on a space-time lattice has been used to obtain this and
other predictions about the nature of QGP. Heavy ion collisions at the Large
Hadron Collider in CERN can potentially test these predictions and thereby test
our theoretical understanding of confinement. This brief review aims at
providing a glimpse of both these aspects of QGP.


title: Quantum Group as Semi-infinite Cohomology

abstract:
  We obtain the quantum group $SL_q(2)$ as semi-infinite cohomology of the
Virasoro algebra with values in a tensor product of two braided vertex operator
algebras with complementary central charges $c+\bar{c}=26$. Each braided VOA is
constructed from the free Fock space realization of the Virasoro algebra with
an additional q-deformed harmonic oscillator degree of freedom. The braided VOA
structure arises from the theory of local systems over configuration spaces and
it yields an associative algebra structure on the cohomology. We explicitly
provide the four cohomology classes that serve as the generators of $SL_q(2)$
and verify their relations. We also discuss the possible extensions of our
construction and its connection to the Liouville model and minimal string
theory.


title:
D-dimensional Randall-Sundrum models from Brans-Dicke theory and
  Kaluza-Klein modes

abstract:
  We investigate the spectroscopy of scalar and vector Kaluza-Klein modes that
arise in a deformed Randall-Sundrum model that is constructed from Brans-Dicke
theory. The non-minimal coupling in the Brans Dicke theory translates into a
deformation of the Randall-Sundrum geometry that depends on the Brans-Dicke
parameter $\omega$. We find that the $\omega$ parameter has a non-trivial
effect in the spectroscopy of scalar and vector Kaluza-Klein modes. Our results
suggest the interpretation of $\omega$ as a fine-tuning parameter.


title: Topological Insulators at Room Temperature

abstract:
  Topological insulators are new states of quantum matter with surface states
protected by the time-reversal symmetry. In this work, we perform
first-principle electronic structure calculations for $Sb_2Te_3$, $Sb_2Se_3$,
$Bi_2Te_3$ and $Bi_2Se_3$ crystals. Our calculations predict that $Sb_2Te_3$,
$Bi_2Te_3$ and $Bi_2Se_3$ are topological insulators, while $Sb_2Se_3$ is not.
In particular, $Bi_2Se_3$ has a topologically non-trivial energy gap of $0.3
eV$, suitable for room temperature applications. We present a simple and
unified continuum model which captures the salient topological features of this
class of materials. These topological insulators have robust surface states
consisting of a single Dirac cone at the $\Gamma$ point.


title:
Separability of Gravitational Perturbation in Generalized Kerr-NUT-de
  Sitter Spacetime

abstract:
  Generalized Kerr-NUT-de Sitter spacetime is the most general spacetime which
admits a rank-2 closed conformal Killing-Yano tensor. It contains the
higher-dimensional Kerr-de Sitter black holes with partially equal angular
momenta. We study the separability of gravitational perturbations in the
generalized Kerr-NUT-de Sitter spacetime. We show that a certain type of tensor
perturbations admits the separation of variables. The linearized perturbation
equations for the Einstein condition are transformed into the ordinary
differential equations of Fuchs type.


title: Semidefinite geometry of the numerical range

abstract:
  The numerical range of a matrix is studied geometrically via the cone of
positive semidefinite matrices (or semidefinite cone for short). In particular
it is shown that the feasible set of a two-dimensional linear matrix inequality
(LMI), an affine section of the semidefinite cone, is always dual to the
numerical range of a matrix, which is therefore an affine projection of the
semidefinite cone. Both primal and dual sets can also be viewed as convex hulls
of explicit algebraic plane curve components. Several numerical examples
illustrate this interplay between algebra, geometry and semidefinite
programming duality. Finally, these techniques are used to revisit a theorem in
statistics on the independence of quadratic forms in a normally distributed
vector.


title:
Simultaneous confidence intervals for the population cell means, for
  two-by-two factorial data, that utilize uncertain prior information

abstract:
  Consider a two-by-two factorial experiment with more than 1 replicate.
Suppose that we have uncertain prior information that the two-factor
interaction is zero. We describe new simultaneous frequentist confidence
intervals for the 4 population cell means, with simultaneous confidence
coefficient 1-alpha, that utilize this prior information in the following
sense. These simultaneous confidence intervals define a cube with expected
volume that (a) is relatively small when the two-factor interaction is zero and
(b) has maximum value that is not too large. Also, these intervals coincide
with the standard simultaneous confidence intervals obtained by Tukey's method,
with simultaneous confidence coefficient 1-alpha, when the data strongly
contradict the prior information that the two-factor interaction is zero. We
illustrate the application of these new simultaneous confidence intervals to a
real data set.


title:
Generating "squeezed" superpositions of coherent states using photon
  addition and subtraction

abstract:
  We study how photon addition and subtraction can be used to generate squeezed
superpositions of coherent states in free-traveling fields (SSCSs) with high
fidelities and large amplitudes. It is shown that an arbitrary $N$-photon
subtraction results in the generation of a SSCS with nearly the perfect
fidelity ($F>0.999$) regardless of the number of photons subtracted. In this
case, the amplitude of the SSCS increases as the number of the subtracted
photons gets larger. For example, two-photon subtraction from a squeezed vacuum
state of 6.1dB can generate a SSCS of $\alpha=1.26$, while in the case of the
four-photon subtraction a SSCS of a larger amplitude $\alpha=1.65$ is obtained
under the same condition. When a photon is subtracted from a squeezed vacuum
state and another photon is added subsequently, a SSCS with a lower fidelity
($F\approx 0.96$) yet higher amplitude ($\alpha\approx2$) can be generated. We
analyze some experimental imperfections including inefficiency of the detector
used for the photon subtraction.


title: Long time behaviour of viscous scalar conservation laws

abstract:
  This paper is concerned with the stability of stationary solutions of the
conservation law $\partial_t u + \mathrm{div}_y A(y,u) -\Delta_y u=0$, where
the flux $A$ is periodic with respect to its first variable. Essentially two
kinds of asymptotic behaviours are studied here: the case when the equation is
set on $\R$, and the case when it is endowed with periodic boundary conditions.
In the whole space case, we first prove the existence of viscous stationary
shocks - also called standing shocks - which connect two different periodic
stationary solutions to one another. We prove that standing shocks are stable
in $L^1$, provided the initial disturbance satisfies some appropriate
boundedness conditions. We also extend this result to arbitrary initial data,
but with some restrictions on the flux $A$. In the periodic case, we prove that
periodic stationary solutions are always stable. The proof of this result
relies on the derivation of uniform $L^\infty$ bounds on the solution of the
conservation law, and on sub- and super-solution techniques.


title: Two Dimensional Connectivity for Vehicular Ad-Hoc Networks

abstract:
  In this paper, we focus on two-dimensional connectivity in sparse vehicular
ad hoc networks (VANETs). In this respect, we find thresholds for the arrival
rates of vehicles at entrances of a block of streets such that the connectivity
is guaranteed for any desired probability. To this end, we exploit a mobility
model recently proposed for sparse VANETs, based on BCMP open queuing networks
and solve the related traffic equations to find the traffic characteristics of
each street and use the results to compute the exact probability of
connectivity along these streets. Then, we use the results from percolation
theory and the proposed fast algorithms for evaluation of bond percolation
problem in a random graph corresponding to the block of the streets. We then
find sufficiently accurate two dimensional connectivity-related parameters,
such as the average number of intersections connected to each other and the
size of the largest set of inter-connected intersections. We have also proposed
lower bounds for the case of heterogeneous network with two transmission
ranges. In the last part of the paper, we apply our method to several numerical
examples and confirm our results by simulations.


title:
An application of the O'Nan-Scott theorem to the group generated by the
  round functions of an AES-like cipher

abstract:
  In a previous paper, we had proved that the permutation group generated by
the round functions of an AES-like cipher is primitive. Here we apply the O'Nan
Scott classification of primitive groups to prove that this group is the
alternating group.


title: Jets and multi-phase turbulence

abstract:
  Jets are observed to stir up multi-phase turbulence in the inter-stellar
medium as well as far beyond the host galaxy. Here we present detailed
simulations of this process. We evolve the hydrodynamics equations with
optically thin cooling for a 3D Kelvin Helmholtz setup with one initial cold
cloud. The cloud is quickly disrupted, but the fragments remain cold and are
spread throughout our simulation box. A scale free isotropic Kolmogorov power
spectrum is built up first on the large scales, and reaches almost down to the
grid scale after the simulation time of ten million years. We find a pronounced
peak in the temperature distribution at 14,000K. The luminosity of the gas in
this peak is correlated with the energy. We interpret this as a realisation of
the shock ionisation scenario. The interplay between shock heating and
radiative cooling establishes the equilibrium temperature. This is close to the
observed emission in some Narrow Line Regions. We also confirm the shift of the
phase equilibrium, i.e. a lower (higher) level of turbulence produces a higher
(lower) abundance of cold gas. The effect could plausibly lead to a high level
of cold gas condensation in the cocoons of extragalactic jets, explaining the
so called Alignment Effect.


title:
Comparison of transient horizontal magnetic fields in a plage region and
  in the quiet Sun

abstract:
  Properties of transient horizontal magnetic fields (THMFs) in both plage and
quiet Sun regions are obtained and compared. Spectro-polarimetric observations
with the Solar Optical Telescope (SOT) on the Hinode satellite were carried out
with a cadence of about 30 seconds for both plage and quiet regions located
near disk center. We select THMFs that have net linear polarization (LP) higher
than 0.22%, and an area larger than or equal to 3 pixels, and compare their
occurrence rates and distribution of magnetic field azimuth. We obtain
probability density functions (PDFs) of magnetic field strength and inclination
for both regions.The occurrence rate in the plage region is the same as for the
quiet Sun. The vertical magnetic flux in the plage region is ~8 times larger
than in the quiet Sun. There is essentially no preferred orientation for the
THMFs in either region. However, THMFs in the plage region with higher LP have
a preferred direction consistent with that of the plage-region's large-scale
vertical field pattern. PDFs show that there is no difference in the
distribution of field strength of horizontal fields between the quiet Sun and
the plage regions when we avoid the persistent large vertical flux
concentrations for the plage region. The similarity of the PDFs and of the
occurrence rates in plage and quiet regions suggests that a local dynamo
process due to the granular motion may generate THMFs all over the sun. The
preferred orientation for higher LP in the plage indicates that the THMFs are
somewhat influenced by the larger-scale magnetic field pattern of the plage.


title: Quantum particle displacement by a moving localized potential trap

abstract:
  We describe the dynamics of a bound state of an attractive $\delta$-well
under displacement of the potential. Exact analytical results are presented for
the suddenly moved potential. Since this is a quantum system, only a fraction
of the initially confined wavefunction remains confined to the moving
potential. However, it is shown that besides the probability to remain confined
to the moving barrier and the probability to remain in the initial position,
there is also a certain probability for the particle to move at double speed. A
quasi-classical interpretation for this effect is suggested. The temporal and
spectral dynamics of each one of the scenarios is investigated.


title: A simple asynchronous replica-exchange implementation

abstract:
  We discuss the possibility of implementing asynchronous replica-exchange (or
parallel tempering) molecular dynamics. In our scheme, the exchange attempts
are driven by asynchronous messages sent by one of the computing nodes, so that
different replicas are allowed to perform a different number of time-steps
between subsequent attempts. The implementation is simple and based on the
message-passing interface (MPI). We illustrate the advantages of our scheme
with respect to the standard synchronous algorithm and we benchmark it for a
model Lennard-Jones liquid on an IBM-LS21 blade center cluster.


title: Gonality of a general ACM curve in projective 3-space

abstract:
  Let C be an ACM (projectively normal) nondegenerate smooth curve in
projective 3-space, and suppose C is general in its Hilbert scheme - this is
irreducible once the postulation is fixed. Answering a question posed by
Peskine, we show the gonality of C is d-l, where d is the degree of the curve,
and l is the maximum order of a multisecant line of C. Furthermore l=4 except
for two series of cases, in which the postulation of C forces every surface of
minimum degree containing C to contain a line as well. We compute the value of
l in terms of the postulation of C in these exceptional cases. We also show the
Clifford index of C is equal to the gonality minus 2.


title: Storage of very cold neutrons in a trap with nano-structured walls

abstract:
  We report on storage of Very Cold Neutrons (VCN) in a trap with walls
containing powder of diamond nanoparticles. The efficient VCN reflection is
provided by multiple diffusive elastic scattering of VCN at single
nanoparticles in powder. The VCN storage times are sufficiently long for
accumulating large density of neutrons with complete VCN energy range of up to
a few times 10(-4) eV. Methods for further improvements of VCN storage times
are discussed.


title: Circumstellar disks around Herbig Be stars

abstract:
  We completed a search for circumstellar disks around Herbig Be stars using
the NRAO Very Large Array (VLA) and the IRAM Plateau de Bure (PdB)
interferometers. We present our new VLA and PdBI data for the three objects MWC
297, Z CMa, and LKHa 215. We constructed the SED from near-IR to centimeter
wavelengths by adding our millimeter and centimeter data to the available data
at other wavelengths, mainly Spitzer images. The entire SED was fitted using a
disk+envelope model. In addition, we compiled all the disk millimeter
observations in the literature and completed a statistical analysis of all the
data. We show that the disk mass is usually only a small percentage (less than
10%) of the mass of the entire envelope in HBe stars. For the disks, there are
large source-to-source variations. Two disks in our sample, R Mon and Z CMa,
have similar sizes and masses to those found in T Tauri and Herbig Ae stars.
The disks around MWC 1080 and MWC 297 are, however, smaller (rout<100 AU). We
did not detect the disks towards MWC 137 and LkHa 215 at millimeter
wavelengths, which limits the mass and the size of the possible circumstellar
disks. A comparison between our data and previous results for T Tauri and
Herbig Ae stars indicates that although massive disks (0.1 Msun) are found in
young objects (10^4 yr), the masses of the disks around Herbig Be stars are
usually 5-10 times lower than those around lower mass stars. We propose that
disk photoevaporation is responsible for this behavior. In Herbig Be stars, the
UV radiation disperses the gas in the outer disk on a timescale of a few 10^5
yr. Once the outer part of the disk has vanished, the entire gaseous disk is
photoevaporated on a very short timescale (10^5 yr) and only a small, dusty
disk consisting of large grains remains.


title: On nonlinear equations connected with six-dimensional Plebanski space

abstract:
  An examples of Monge-Ampere equations connected with six-dimensional
generalization of the Plebanski four-dimensional space are considered. Their
particular solutions are constructed.