title: Rule Generalisation in Intrusion Detection Systems using Snort

abstract:
  Intrusion Detection Systems (ids)provide an important layer of security for
computer systems and networks, and are becoming more and more necessary as
reliance on Internet services increases and systems with sensitive data are
more commonly open to Internet access. An ids responsibility is to detect
suspicious or unacceptable system and network activity and to alert a systems
administrator to this activity. The majority of ids use a set of signatures
that define what suspicious traffic is, and Snort is one popular and actively
developing open-source ids that uses such a set of signatures known as Snort
rules. Our aim is to identify a way in which Snort could be developed further
by generalising rules to identify novel attacks. In particular, we attempted to
relax and vary the conditions and parameters of current Snort rules, using a
similar approach to classic rule learning operators such as generalisation and
specialisation. We demonstrate the effectiveness of our approach through
experiments with standard datasets and show that we are able to detect
previously undeleted variants of various attacks. We conclude by discussing the
general effectiveness and appropriateness of generalisation in Snort based ids
rule processing.


title: Mixed metric 3-contact manifolds and paraquaternionic K\"ahler manifolds

abstract:
  We study manifolds endowed with mixed metric 3--contact structures, proving
that the distribution spanned by the Reeb vector fields is integrable, with
totally geodesic integral manifolds, of constant sectional curvature $k=\pm1$.
We also prove a result of projectability of such structures onto
paraquaternionic K\"ahlerian structures.


title: An Estimation of Distribution Algorithm for Nurse Scheduling

abstract:
  Schedules can be built in a similar way to a human scheduler by using a set
of rules that involve domain knowledge. This paper presents an Estimation of
Distribution Algorithm (eda) for the nurse scheduling problem, which involves
choosing a suitable scheduling rule from a set for the assignment of each
nurse. Unlike previous work that used Genetic Algorithms (ga) to implement
implicit learning, the learning in the proposed algorithm is explicit, i.e. we
identify and mix building blocks directly. The eda is applied to implement such
explicit learning by building a Bayesian network of the joint distribution of
solutions. The conditional probability of each variable in the network is
computed according to an initial set of promising solutions. Subsequently, each
new instance for each variable is generated by using the corresponding
conditional probabilities, until all variables have been generated, i.e. in our
case, a new rule string has been obtained. Another set of rule strings will be
generated in this way, some of which will replace previous strings based on
fitness selection. If stopping conditions are not met, the conditional
probabilities for all nodes in the Bayesian network are updated again using the
current set of promising rule strings. Computational results from 52 real data
instances demonstrate the success of this approach. It is also suggested that
the learning mechanism in the proposed approach might be suitable for other
scheduling problems.


title: Quantum Learning Machine

abstract:
  We propose a novel notion of a quantum learning machine for automatically
controlling quantum coherence and for developing quantum algorithms. A quantum
learning machine can be trained to learn a certain task with no a priori
knowledge on its algorithm. As an example, it is demonstrated that the quantum
learning machine learns Deutsch's task and finds itself a quantum algorithm,
that is different from but equivalent to the original one.


title: A Hidden Valley model of cold dark matter with photonic portal

abstract:
  In the discussed model, the cold dark matter consists of Dirac spin-1/2
fermions, sterile from all Standard Model charges, where masses are generated
by a nonzero vacuum expectation value of a field of scalar bosons, also assumed
to be sterile. For convenience, these sterile particles have beeen called
sterinos and sterons, respectively. It has been conjectured that our sterile
world of sterinos and sterons can communicate with the familiar Standard Model
world not only through gravity, but also through a photonic portal provided by
a very weak effective interaction involving the electromagnetic field F_{\mu
\nu} = \partial_\mu A_\nu - \partial_\nu A_\mu coupled to the sterino and
steron fields.


title:
A very simple, robust and fast method for estimating and displaying
  average time constants of T2 decays from multiecho MRI images using color
  intensity projections

abstract:
  While the multiexponential nature of T2 decays measured in vivo is well
known, characterizing T2 decays by a single time constant is still very useful
when differentiating among structures and pathologies in MRI images. A novel,
robust, fast and very simple method is presented for both estimating and
displaying the average time constant for the T2 decay of each pixel from a
multiecho MRI sequence. The average time constant is calculated from the
average of the values measured from the T2 decay over many echoes. For a
monoexponential decay, the normalized decay average varies monotonically with
the time constant. Therefore, it is simple to map any normalized decay average
to an average time constant. This method takes advantage of the robustness of
the normalized decay average to both artifacts and multiexponential decays.
Color intensity projections (CIPs) were used to display 32 echoes acquired at a
10ms spacing as a single color image. The brightness of each pixel in each
color image was determined by the intensity of the corresponding pixel in the
earliest image and the hue was determined by the normalized decay average.
Examples demonstrate the effectiveness of using CIPs to display the results of
a multiecho sequence for a healthy subject and a multiple sclerosis patient.


title: A Markov dilation for self-adjoint Schur multipliers

abstract:
  We give a formula for Markov dilation in the sense of Anantharaman-Delaroche
for real positive Schur multipliers on $\B(H)$


title: A Note on Tachyon Moduli and Closed Strings

abstract:
  The collective behavior of the SL(2,R) covariant brane states of non-critical
c=1 string theory found in a previous work, is studied in the Fermi liquid
approximation. It is found that such states mimick the coset WZW model, whereas
only by further restrictions one recovers the double-scaling limit which was
purported to be equivalent to closed string models. Another limit is proposed,
inspired by the tachyon condensation ideas, where the spectrum is the same of
two-dimensional string theory. We close by noting some strange connections
between vacuum states of the theory in their different interpretations.


title: Idiotypic Immune Networks in Mobile Robot Control

abstract:
  Jerne's idiotypic network theory postulates that the immune response involves
inter-antibody stimulation and suppression as well as matching to antigens. The
theory has proved the most popular Artificial Immune System (ais) model for
incorporation into behavior-based robotics but guidelines for implementing
idiotypic selection are scarce. Furthermore, the direct effects of employing
the technique have not been demonstrated in the form of a comparison with
non-idiotypic systems. This paper aims to address these issues. A method for
integrating an idiotypic ais network with a Reinforcement Learning based
control system (rl) is described and the mechanisms underlying antibody
stimulation and suppression are explained in detail. Some hypotheses that
account for the network advantage are put forward and tested using three
systems with increasing idiotypic complexity. The basic rl, a simplified hybrid
ais-rl that implements idiotypic selection independently of derived
concentration levels and a full hybrid ais-rl scheme are examined. The test bed
takes the form of a simulated Pioneer robot that is required to navigate
through maze worlds detecting and tracking door markers.


title: Local implementation of nonlocal operations of block forms

abstract:
  We investigate the local implementation of nonlocal operations with the block
matrix form, and propose a protocol for any diagonal or offdiagonal block
operation. This method can be directly generalized to the two-party multiqubit
case and the multiparty case. Especially, in the multiparty cases, any diagonal
block operation can be locally implemented using the same resources as the
multiparty control-U operation discussed in Ref. [Eisert et al., Phys. Rev. A
62, 052317(2000)]. Although in the bipartite case, this kind of operations can
be transformed to control-U operation using local operations, these
transformations are impossible in the multiparty cases. We also compare the
local implementation of nonlocal block operations with the remote
implementation of local operations, and point out a relation between them.


title: High Resolution Radio Astronomy Using Very Long Baseline Interferometry

abstract:
  Very Long Baseline Interferometry, or VLBI, is the observing technique
yielding the highest-resolution images today. Whilst a traditionally large
fraction of VLBI observations is concentrating on Active Galactic Nuclei, the
number of observations concerned with other astronomical objects such as stars
and masers, and with astrometric applications, is significant. In the last
decade, much progress has been made in all of these fields. We give a brief
introduction into the technique of radio interferometry, focussing on the
particularities of VLBI observations, and review recent results which would not
have been possible without VLBI observations.


title: Conditional density estimation in a regression setting

abstract:
  Regression problems are traditionally analyzed via univariate characteristics
like the regression function, scale function and marginal density of regression
errors. These characteristics are useful and informative whenever the
association between the predictor and the response is relatively simple. More
detailed information about the association can be provided by the conditional
density of the response given the predictor. For the first time in the
literature, this article develops the theory of minimax estimation of the
conditional density for regression settings with fixed and random designs of
predictors, bounded and unbounded responses and a vast set of anisotropic
classes of conditional densities. The study of fixed design regression is of
special interest and novelty because the known literature is devoted to the
case of random predictors. For the aforementioned models, the paper suggests a
universal adaptive estimator which (i) matches performance of an oracle that
knows both an underlying model and an estimated conditional density; (ii) is
sharp minimax over a vast class of anisotropic conditional densities; (iii) is
at least rate minimax when the response is independent of the predictor and
thus a bivariate conditional density becomes a univariate density; (iv) is
adaptive to an underlying design (fixed or random) of predictors.


title: Driven particle in a cloud of mobile impurities

abstract:
  The dynamics of a test particle interacting with diffusing impurities in one
dimension is investigated analytically and numerically. In the absence of an
applied external force, the dynamics of the particle can be characterized by a
distribution of monotonic excursions $\Delta x$, which scales as a power law
with an exponent $\tau_{\Delta x} = 4/3$. When the particle is driven at a slow
constant velocity, there is again a power law distribution for the monotonic
changes of the force $\Delta F$, which is characterized by a similar exponent
$\tau_{\Delta F}=4/3$. These results can be understood from the theory of
random walks.


title:
Perturbation selection and influence measures in local influence
  analysis

abstract:
  Cook's [J. Roy. Statist. Soc. Ser. B 48 (1986) 133--169] local influence
approach based on normal curvature is an important diagnostic tool for
assessing local influence of minor perturbations to a statistical model.
However, no rigorous approach has been developed to address two fundamental
issues: the selection of an appropriate perturbation and the development of
influence measures for objective functions at a point with a nonzero first
derivative. The aim of this paper is to develop a differential--geometrical
framework of a perturbation model (called the perturbation manifold) and
utilize associated metric tensor and affine curvatures to resolve these issues.
We will show that the metric tensor of the perturbation manifold provides
important information about selecting an appropriate perturbation of a model.
Moreover, we will introduce new influence measures that are applicable to
objective functions at any point. Examples including linear regression models
and linear mixed models are examined to demonstrate the effectiveness of using
new influence measures for the identification of influential observations.


title: Examples of Calabi-Yau 3-manifolds with complex multiplication

abstract:
  We give some concrete examples of Calabi-Yau 3-manifolds with complex
multiplication.


title:
Electronic charge and orbital reconstruction at cuprate-titanate
  interfaces

abstract:
  In complex transition metal oxide heterostructures of physically dissimilar
perovskite compounds, interface phenomena can lead to novel physical properties
not observed in either of their constituents. This remarkable feature opens new
prospects for technological applications in oxide electronic devices based on
nm-thin oxide films. Here we report on a significant electronic charge and
orbital reconstruction at interfaces between YBa2Cu3O6 and SrTiO3 studied using
local spin density approximation (LSDA) with intra-atomic Coulomb repulsion
(LSDA+U). We show that the interface polarity results in the metallicity of
cuprate-titanate superlattices with the hole carriers concentrated
predominantly in the CuO2 and BaO layers and in the first interface TiO2 and
SrO planes. We also find that the interface structural relaxation causes a
strong change of orbital occupation of Cu 3d orbitals in the CuO2 layers. The
concomitant change of Cu valency from +2 to +3 is related to the partial
occupation of the Cu $3d_{3z^2-r^2}$ orbitals at the interface with SrO planes
terminating SrTiO3. Interface-induced predoping and orbital reconstruction in
CuO2 layers are key mechanisms which control the superconducting properties of
field-effect devices developed on the basis of cuprate-titanate
heterostructures.


title: A Note on E11 and Three-dimensional Gauged Supergravity

abstract:
  We determine the gauge symmetries of all p-forms in maximal three-dimensional
gauged supergravity by requiring invariance of the Lagrangian. It is shown that
in a particular ungauged limit these symmetries are in precise correspondence
to those predicted by the very-extended Kac-Moody algebra E11. We demonstrate
that whereas in the ungauged limit the bosonic gauge algebra closes off-shell,
the closure is only on-shell in the full gauged theory. This underlines the
importance of dynamics for understanding the Kac-Moody origin of the symmetries
of gauged supergravity.


title: A derived approach to geometric McKay correspondence in dimension three

abstract:
  We propose a three dimensional generalization of the geometric McKay
correspondence described by Gonzales-Sprinberg and Verdier in dimension two. We
work it out in detail when G is abelian and C^3/G has a single isolated
singularity. More precisely, we show that the Bridgeland-King-Reid derived
category equivalence induces a natural geometric correspondence between
irreducible representations of G and subschemes of the exceptional set of
G-Hilb (C^3). This correspondence appears to be related to Reid's recipe.


title: Short chaotic strings and their behaviour in the scaling region

abstract:
  Coupled map lattices are a paradigm of higher-dimensional dynamical systems
exhibiting spatio-temporal chaos. A special case of non-hyperbolic maps are
one-dimensional map lattices of coupled Chebyshev maps with periodic boundary
conditions, called chaotic strings. In this short note we show that the fine
structure of the self energy of this chaotic string in the scaling region (i.e.
for very small coupling) is retained if we reduce the length of the string to
three lattice points.


title: Axigluon signatures at hadron colliders

abstract:
  Axigluons are colored heavy neutral gauge boson that are predicted by some
theories. The most important model-independent manifestation of axigluons is
the generation of a forward--backward asymmetry in top-antitop quark production
at $p\bar{p}$ collisions which originates from the charge asymmetry. We update
our previous analysis for the inclusive QCD induced forward--backward asymmetry
and define a new observable which is more sensitive to the effect than the
forward--backward asymmetry. We find a lower limit of 1.4 TeV at 90% C.L. on
the axigluon mass from recent measurements of the asymmetry at Tevatron, and
extend the analysis to LHC in suitably selected samples. Like at Tevatron, the
charge asymmetry can probe larger values of the axigluon mass than the dijet
mass distribution.


title:
Measurement of Parton Distributions of Strange Quarks in the Nucleon
  from Charged-Kaon Production in Deep-Inelastic Scattering on the Deuteron

abstract:
  The momentum and helicity density distributions of the strange quark sea in
the nucleon are obtained in leading order from charged-kaon production in
deep-inelastic scattering on the deuteron. The distributions are extracted from
spin-averaged K+/- multiplicities, and from K+/- and inclusive double-spin
asymmetries for scattering of polarized positrons by a polarized deuterium
target. The shape of the momentum distribution is softer than that of the
average of the ubar and dbar quarks. In the region of measurement 0.02 < x <
0.6 and Q^2 > 1.0 GeV^2, the helicity distribution is zero within experimental
uncertainties.


title: Condensation of MgS in outflows from carbon stars

abstract:
  The basic mechanism responsible for the widespread condensation of MgS in the
outflows from carbon rich stars on the tip of the AGB is discussed with the aim
of developing a condensation model that can be applied in model calculations of
dust formation in stellar winds.
  The different possibilities how MgS may be formed in the chemical environment
of outflows from carbon stars are explored by some thermochemical calculations
and by a detailed analysis of the growth kinetics of grains in stellar winds.
The optical properties of core-mantle grains with a MgS mantle are calculated
to demonstrate that such grains reproduce the structure of the observed 30
$\mu$m feature. These considerations are complemented by model calculations of
circumstellar dust shells around carbon stars.
  It is argued that MgS is formed via precipitation on silicon carbide grains.
This formation mechanism explains some of the basic observed features of MgS
condensation in dust shells around carbon stars. A weak secondary peak at about
33 ... 36 $\mu$m is shown to exist in certain cases if MgS forms a coating on
SiC.


title: The Role of Management Practices in Closing the Productivity Gap

abstract:
  There is no doubt that management practices are linked to the productivity
and performance of a company. However, research findings are mixed. This paper
provides a multi-disciplinary review of the current evidence of such a
relationship and offers suggestions for further exploration. We provide an
extensive review of the literature in terms of research findings from studies
that have been trying to measure and understand the impact that individual
management practices and clusters of management practices have on productivity
at different levels of analysis. We focus our review on Operations Management
(om) and Human Resource Management (hrm) practices as well as joint
applications of these practices. In conclusion, we can say that taken as a
whole, the research findings are equivocal. Some studies have found a positive
relationship between the adoption of management practices and productivity,
some negative and some no association whatsoever. We believe that the lack of
universal consensus on the effect of the adoption of complementary management
practices might be driven either by measurement issues or by the level of
analysis. Consequently, there is a need for further research. In particular,
for a multi-level approach from the lowest possible level of aggregation up to
the firm-level of analysis in order to assess the impact of management
practices upon the productivity of firms.


title:
The virtues and vices of equilibrium and the future of financial
  economics

abstract:
  The use of equilibrium models in economics springs from the desire for
parsimonious models of economic phenomena that take human reasoning into
account. This approach has been the cornerstone of modern economic theory. We
explain why this is so, extolling the virtues of equilibrium theory; then we
present a critique and describe why this approach is inherently limited, and
why economics needs to move in new directions if it is to continue to make
progress. We stress that this shouldn't be a question of dogma, but should be
resolved empirically. There are situations where equilibrium models provide
useful predictions and there are situations where they can never provide useful
predictions. There are also many situations where the jury is still out, i.e.,
where so far they fail to provide a good description of the world, but where
proper extensions might change this. Our goal is to convince the skeptics that
equilibrium models can be useful, but also to make traditional economists more
aware of the limitations of equilibrium models. We sketch some alternative
approaches and discuss why they should play an important role in future
research in economics.


title:
Mode-locking and mode-competition in a non-equilibrium solid-state
  condensate

abstract:
  A trapped polariton condensate with continuous pumping and decay is analyzed
using a generalized Gross-Pitaevskii model. Whereas an equilibrium condensate
is characterized by a macroscopic occupation of a ground state, here the
steady-states take more general forms. Some are characterized by a large
population in an excited state, and others by large populations in several
states. In the latter case, the highly-populated states synchronize to a common
frequency above a critical density. Estimates for the critical density of this
synchronization transition are consistent with experiments.


title: Extremal vacuum black holes in higher dimensions

abstract:
  We consider extremal black hole solutions to the vacuum Einstein equations in
dimensions greater than five. We prove that the near-horizon geometry of any
such black hole must possess an SO(2,1) symmetry in a special case where one
has an enhanced rotational symmetry group. We construct examples of vacuum
near-horizon geometries using the extremal Myers-Perry black holes and boosted
Myers-Perry strings. The latter lead to near-horizon geometries of black ring
topology, which in odd spacetime dimensions have the correct number rotational
symmetries to describe an asymptotically flat black object. We argue that a
subset of these correspond to the near-horizon limit of asymptotically flat
extremal black rings. Using this identification we provide a conjecture for the
exact ``phase diagram'' of extremal vacuum black rings with a connected horizon
in odd spacetime dimensions greater than five.


title:
Rate-optimal estimation for a general class of nonparametric regression
  models with unknown link functions

abstract:
  This paper discusses a nonparametric regression model that naturally
generalizes neural network models. The model is based on a finite number of
one-dimensional transformations and can be estimated with a one-dimensional
rate of convergence. The model contains the generalized additive model with
unknown link function as a special case. For this case, it is shown that the
additive components and link function can be estimated with the optimal rate by
a smoothing spline that is the solution of a penalized least squares criterion.


title:
Tracing the [FeII]/[NeII] ratio and its relationship with other ISM
  indicators within star forming dwarf galaxies: a Spitzer IRS archival study

abstract:
  Archival Spitzer observations of 41 starburst galaxies that span a wide range
in metallicity reveal for the first time a correlation between the
[FeII]/[NeII] 26.0/12.8 micron ratio and the electron gas density as traced by
the 18.7/33.4 micron [SIII] ratio, with the [FeII]/[NeII] ratio decreasing with
increasing gas density. The correlations of the [FeII]/[NeII] ratio, the PAH
peak to continuum strength & metallicity found in an earlier paper were
confirmed for a larger sample. We also find a strong correlation between the
gas density and the PAH peak to continuum strength. Using shock and
photoionization models, we see the driver of the observed [FeII]/[NeII] ratios
is metallicity. The majority of [FeII] emission in low metallicity galaxies may
be shock-derived, whilst at high metallicity, the [FeII] emission may be
instead dominated by contributions from HII and in particular from dense PDR
regions. However, the observed [FeII]/[NeII] ratios may instead be following a
metallicity-abundance relationship, with iron being less depleted onto grains
in low metallicity galaxies - a result that would have profound implications
for the use of iron emission lines as unambiguous tracers of shocks.


title: Minors in random regular graphs

abstract:
  We show that there is a constant c>0 so that for any fixed r which is at
least 3 a.a.s. an r-regular graph on n vertices contains a complete graph on c
n^{1/2} vertices as a minor. This confirms a conjecture of Markstrom. Since any
minor of an r-regular graph on n vertices has at most rn/2 edges, our bound is
clearly best possible up to the value of the constant c. As a corollary, we
also obtain the likely order of magnitude of the largest complete minor in a
random graph G(n,p) during the phase transition (i.e. when pn is close to 1).


title:
IMAGES-III: The evolution of the Near-Infrared Tully-Fisher relation
  over the last 6 Gyr

abstract:
  Using the multi-integral field spectrograph GIRAFFE at VLT, we have derived
the K-band Tully-Fisher relation (TFR) at z~0.6 for a representative sample of
65 galaxies with emission lines. We confirm that the scatter in the z~0.6 TFR
is caused by galaxies with anomalous kinematics, and find a positive and strong
correlation between the complexity of the kinematics and the scatter that they
contribute to the TFR. Considering only relaxed-rotating disks, the scatter,
and possibly also the slope of the TFR, do not appear to evolve with z. We
detect an evolution of the K-band TFR zero point between z~0.6 and z=0, which,
if interpreted as an evolution of the K-band luminosity of rotating disks,
would imply that a brightening of 0.66+/-0.14 mag occurs between z~0.6 and z=0.
Any disagreement with the results of Flores et al. (2006) are attributed to
both an improvement of the local TFR and the more detailed accurate measurement
of the rotation velocities in the distant sample. Most of the uncertainty can
be explained by the relatively coarse spatial-resolution of the kinematical
data. Because most rotating disks at z~0.6 are unlikely to experience further
merging events, one may assume that their rotational velocity does not evolve
dramatically. If true, our result implies that rotating disks observed at z~0.6
are rapidly transforming their gas into stars, to be able to double their
stellar masses and be observed on the TFR at z=0. The rotating disks observed
are indeed emission-line galaxies that are either starbursts or LIRGs, which
implies that they are forming stars at a high rate. Thus, a significant
fraction of the rotating disks are forming the bulk of their stars within 6 to
8 Gyr, in good agreement with former studies of the evolution of the M-Z
relation.


title:
Detection of X-ray elongated emission from a ultraluminous X-ray source
  in the interacting pair of galaxies NGC 5953/5954

abstract:
  We present radio through X-ray results of a bright (10^{40} erg/s in the 0.5
to 8.0 keV band) ultraluminous X-ray source (ULX), CXOU J153434.9+151149, in
the starburst, interacting pair of galaxies NGC 5953/5954. Chandra image of
this ULX shows that it is elongated. From HST/WFPC2/F606W data we have detected
a counterpart of the ULX system with M_{F606W} ~-7.1 \pm 0.7 mag. This optical
counterpart may be either an O-type supergiant star or a young star cluster.
From our Fabry-Perot interferometric observations, we have detected Halpha and
[NII](6584 A) diffuse emission, with velocity gradients up to 60 km/s at the
astrometric corrected Chandra position of the ULX. Different scenarios have
been invoked as to explain the possible nature of CXOU J153434.9+151149. Based
on the observed X-ray morphology of the ULX, we determine that the inclination
angle to the elongated emission will be ~53 deg. Beaming with this geometry
from a stellar-mass black hole system will be inadequate to explain the
observed X-ray luminosity of this ULX. Finally, we suggest that mild-beaming
from a binary black hole with mass more than 50 solar masses, associated with a
young star cluster, is the most favorable scenario that describes the
multiwavelength properties of this ULX. Future observations are highly
essential to determine the nature of this rare object.


title:
A Numerical Renormalization Group approach to Non-Equilibrium Green's
  Functions for Quantum Impurity Models

abstract:
  We present a method for the calculation of dynamical correlation functions of
quantum impurity systems out of equilibrium using Wilson's numerical
renormalization group. Our formulation is based on a complete basis set of the
Wilson chain and embeds the recently derived algorithm for equilibrium spectral
functions. Our method fulfills the spectral weight conserving sum-rule exactly
by construction. A local Coulomb repulsion $U>0$ is switched on at $t=0$, and
the asymptotic steady-state spectral functions are obtained for various values
of $U$ as well as magnetic field strength $H$ and temperature $T$. These
benchmark tests show excellent agreement between the time-evolved and the
directly calculated equilibrium NRG spectra for finite $U$. This method could
be used for calculating steady-state non-equilibrium spectral functions at
finite bias through interacting nano-devices.


title: Fundamental group for the complement of the Cayley's singularities

abstract:
  Given a singular surface X, one can extract information on it by
investigating the fundamental group $\pi_1(X - Sing_X)$. However, calculation
of this group is non-trivial, but it can be simplified if a certain invariant
of the branch curve of X - called the braid monodromy factorization - is known.
This paper shows, taking the Cayley cubic as an example, how this fundamental
group can be computed by using braid monodromy techniques and their liftings.
This is one of the first examples that uses these techniques to calculate this
sort of fundamental group.


title: Unveiling extremely veiled T Tauri stars

abstract:
  Photospheric absorption lines in classical T Tauri stars (CTTS) are weak
compared to normal stars. This so-called veiling is normally identified with an
excess continuous emission formed in shock-heated gas at the stellar surface
below the accretion streams. We have selected four stars (RW Aur A, RU Lup, S
CrA NW and S CrA SE) with unusually strong veiling to make a detailed
investigation of veiling versus stellar brightness and emission line strengths
for comparisons to standard accretion models. We have monitored the stars
photometrically and spectroscopically at several epochs. In standard accretion
models a variable accretion rate will lead to a variable excess emission.
Consequently, the stellar brightness should vary accordingly. We find that the
veiling of absorption lines in these stars is strongly variable and usually so
large that it would require the release of several stellar luminosities of
potential energy. At states of very large line dilution, the correspondingly
large veiling factors derived correlate only weakly with brightness. Moreover,
the emission line strengths violate the expected trend of veiling versus line
strength. The veiling can change dramatically in one night, and is not
correlated with the phase of the rotation periods found for two stars. We show
that in at least three of the stars, when the veiling becomes high, the
photospheric lines become filled-in by line emission, which produces large
veiling factors unrelated to changes in any continuous emission from shocked
regions. We also consider to what extent extinction by dust and electron
scattering in the accretion stream may affect veiling measures in CTTS. We
conclude that the degree of veiling cannot be used as a measure of accretion
rates in CTTS with rich emission line spectra.


title:
Testing the suitability of polynomial models in errors-in-variables
  problems

abstract:
  A low-degree polynomial model for a response curve is used commonly in
practice. It generally incorporates a linear or quadratic function of the
covariate. In this paper we suggest methods for testing the goodness of fit of
a general polynomial model when there are errors in the covariates. There, the
true covariates are not directly observed, and conventional bootstrap methods
for testing are not applicable. We develop a new approach, in which
deconvolution methods are used to estimate the distribution of the covariates
under the null hypothesis, and a ``wild'' or moment-matching bootstrap argument
is employed to estimate the distribution of the experimental errors (distinct
from the distribution of the errors in covariates). Most of our attention is
directed at the case where the distribution of the errors in covariates is
known, although we also discuss methods for estimation and testing when the
covariate error distribution is estimated. No assumptions are made about the
distribution of experimental error, and, in particular, we depart substantially
from conventional parametric models for errors-in-variables problems.


title: A characterization of surfaces whose universal cover is the bidisk

abstract:
  We show that the universal cover of a compact complex surface $X$ is the
bidisk $\HH \times \HH$, or $X$ is biholomorphic to $\PP^1 \times \PP^1$, if
and only if $K_X^2 > 0$ and there exists an invertible sheaf $\eta$ such that
$\eta^2\cong \hol_X$ and $H^0(X, S^2\Omega^1_X (-K_X) \otimes \eta) \neq 0$.
The two cases are distinguished by the second plurigenus, $P_2(X)\geq 2$ in the
former case, $P_2(X)= 0$ in the latter. We also discuss related questions.


title: Decreasing excitation gap in Andreev billiards by disorder scattering

abstract:
  We investigate the distribution of the lowest-lying energy states in a
disordered Andreev billiard by solving the Bogoliubov-de Gennes equation
numerically. Contrary to conventional predictions we find a decrease rather
than an increase of the excitation gap relative to its clean ballistic limit.
We relate this finding to the eigenvalue spectrum of the Wigner-Smith time
delay matrix between successive Andreev reflections. We show that the longest
rather than the mean time delay determines the size of the excitation gap. With
increasing disorder strength the values of the longest delay times increase,
thereby, in turn, reducing the excitation gap.


title: Coxeter covers of the classical Coxeter groups

abstract:
  Let $C(T)$ be a generalized Coxeter group, which has a natural map onto one
of the classical Coxeter groups, either $B_n$ or $D_n$. Let $C_Y(T)$ be a
natural quotient of $C(T)$, and if $C(T)$ is simply-laced (which means all the
relations between the generators has order 2 or 3), $C_Y(T)$ is a generalized
Coxeter group, too . Let $A_{t,n}$ be a group which contains $t$ Abelian groups
generated by $n$ elements. The main result in this paper is that $C_Y(T)$ is
isomorphic to $A_{t,n} \semidirect B_n$ or $A_{t,n} \semidirect D_n$, depends
on whether the signed graph $T$ contains loops or not, or in other words C(T)
is simply-laced or not, and $t$ is the number of the cycles in $T$. This result
extends the results of Rowen, Teicher and Vishne to generalized Coxeter groups
which have a natural map onto one of the classical Coxeter groups.


title:
The flavor-changing top-charm quark production in the littlest Higgs
  model with T parity at the ILC

abstract:
  With high luminosity and energy at the ILC and clean SM backgrounds, the
top-charm production at the ILC should have powerful potential to probe new
physics. The littlest Higgs model with discrete symmetry named "T-parity"(LHT)
is one of the most promising new physics models. In this paper, we study the FC
processes $e^+e^-(\gamma\gamma)\to t\bar{c}$ at the ILC in the LHT model. Our
study shows that the LHT model can make a significant contribution to these
processes. When the masses of mirror quarks become large, these two processes
are accessible at the ILC. So the top-charm production at the ILC provides a
unique way to study the properties of the FC couplings in the LHT model and
furthermore test the model.


title:
On a Possible Mechanism of the Production of Pentaquark States
  $\Theta(ud\bar{s}ud)$

abstract:
  A new mechanism of the production of hypothetical $\Theta(ud\bar{s}ud)^+$
pentaquark state is suggested. The considered mechanism is based on the
exchange by exotic Regge trajectories in the $t$ channel. It is shown that the
momentum distributions of $\Theta^+$ baryons can differ significantly from the
ones of the ordinary hyperons.


title: Resummation in (F)APT

abstract:
  We present new results on the summation of nonpower-series expansions in QCD
Analytic Perturbation Theory (APT) in the one-loop approximation. We show how
to generalize the approach suggested by one of us earlier to the cases of APT
and Fractional APT (FAPT) with heavy-quark thresholds. Using this approach we
analyze the Higgs boson decay $H^0\to\bar{b}b$. We produce estimations of the
higher-order corrections importance in (F)APT and present a very transparent
interpretation of the resummation results in terms of $\Lambda_\text{QCD}$
shifts.


title: Lithium abundances in exoplanet-hosts stars

abstract:
  Exoplanet-host stars (EHS) are known to present surface chemical abundances
different from those of stars without any detected planet (NEHS). EHS are, on
the average, overmetallic compared to the Sun. The observations also show that,
for cool stars, lithium is more depleted in EHS than in NEHS. The
overmetallicity of EHS may be studied in the framework of two different
scenarii. We have computed main sequence stellar models with various masses,
metallicities and accretion rates. The results show different profiles for the
lithium destruction according to the scenario. We compare these results to the
spectroscopic observations of lithium.


title: Interplay between magnetic and lattice excitations in BiFeO$_3$

abstract:
  We have performed Raman scattering investigations on the high energy magnetic
excitations in a BiFeO$_3$ single crystal as a function of both temperature and
laser excitation energy. A strong feature observed at 1250 cm$^{-1}$ in the
Raman spectra has been previously assigned to two phonon overtone. We show here
that its unusual frequency shift with the excitation energy and its asymmetric
temperature dependent Fano lineshape reveal a strong coupling to magnetic
excitations. In the same energy range, we have also identified the two-magnon
excitation with a temperature dependence very similar to $\alpha$-Fe$_2$O$_3$
hematite.


title: The role of massive stars in galactic chemical evolution

abstract:
  I will review the role of massive stars in galactic evolution both from the
nucleosynthesis and energetics point of view. In particular, I will highlight
some important observational facts explained by means of massive stars in
galaxies of different morphological type: the Milky Way, ellipticals and dwarf
spheroidals. I will describe first the time-delay model and its interpretation
in terms of abundance ratios in galaxies, then I will discuss the importance of
mass loss in massive stars to reproduce the data in the Galactic bulge and
disk. I will discuss also how massive stars can be important producers of
primary nitrogen if rotation in stellar models is taken into account.
Concerning elliptical galaxies, I will show that to reproduce the observed
[Mg/Fe] versus Mass relation in these galaxies it is necessary to assume a more
important role of massive stars in more massive galaxies and that this can be
achieved by means of downsizing in star formation. I will discuss how massive
stars are responsible in triggering galactic winds both in ellipticals and
dwarf spheroidals. These latter systems show a low overabundance of
alpha-elements relative to Fe with respect to Galactic stars of the same
[Fe/H]: this is interpreted as due to a slow star formation coupled with very
efficient galactic winds. Finally, I will show a comparison between the
predicted Type Ib/c rates in galaxies and the observed GRB rate and how we can
impose constraints on the mechanism of galaxy formation by studying the GRB
rate at high redshift.


title:
Accelerated convergence for nonparametric regression with coarsened
  predictors

abstract:
  We consider nonparametric estimation of a regression function for a situation
where precisely measured predictors are used to estimate the regression curve
for coarsened, that is, less precise or contaminated predictors. Specifically,
while one has available a sample $(W_1,Y_1),...,(W_n,Y_n)$ of independent and
identically distributed data, representing observations with precisely measured
predictors, where $\mathrm{E}(Y_i|W_i)=g(W_i)$, instead of the smooth
regression function $g$, the target of interest is another smooth regression
function $m$ that pertains to predictors $X_i$ that are noisy versions of the
$W_i$. Our target is then the regression function $m(x)=E(Y|X=x)$, where $X$ is
a contaminated version of $W$, that is, $X=W+\delta$. It is assumed that either
the density of the errors is known, or replicated data are available
resembling, but not necessarily the same as, the variables $X$. In either case,
and under suitable conditions, we obtain $\sqrt{n}$-rates of convergence of the
proposed estimator and its derivatives, and establish a functional limit
theorem. Weak convergence to a Gaussian limit process implies pointwise and
uniform confidence intervals and $\sqrt{n}$-consistent estimators of extrema
and zeros of $m$. It is shown that these results are preserved under more
general models in which $X$ is determined by an explanatory variable. Finite
sample performance is investigated in simulations and illustrated by a real
data example.


title: An Exploration of the Physics of Spherically Symmetric Dynamic Horizons

abstract:
  Geometries with horizons offer insights into relationships between general
relativity and quantum physics. For static spherically symmetric space-times,
the event horizon is coincident with a coordinate anomaly that introduces
complications in descriptions of near horizon physics. Naive introduction of
dynamics using coordinates with anomalous behavior coincident with the horizon
also introduces invariant singular physical content at that horizon. However,
the introduction of a temporal coordinate that is non-orthogonal to spatial
coordinates near the horizon, but asymptotically orthogonal, provides a dynamic
description without singular physical content at the horizon itself. Penrose
diagrams will be presented exhibiting temporal dependencies for accreting and
evaporating black holes, and near horizon light-like trajectories will be
examined. In addition, the quantum mechanics of simple quantum fields will be
explored. Finally, a two-fluid cosmology will be suggested to describe dynamic
coherent aspects of the universe as a whole.


title: Further discussion of Tomboulis' approach to the confinement problem

abstract:
  We discuss in some detail certain gaps and open problems in the recent paper
by E. T. Tomboulis, which claims to give a rigorous proof of quark confinement
in 4D lattice Yang-Mills theory for all values of the bare coupling. We also
discuss what would be needed to fill the gaps in his proof.


title: First Lattice Study of the $N$-$P_{11}(1440)$ Transition Form Factors

abstract:
  Experiments at Jefferson Laboratory, MIT-Bates, LEGS, Mainz, Bonn, GRAAL, and
Spring-8 offer new opportunities to understand in detail how nucleon resonance
($N^*$) properties emerge from the nonperturbative aspects of QCD. Preliminary
data from CLAS collaboration, which cover a large range of photon virtuality
$Q^2$ show interesting behavior with respect to $Q^2$ dependence: in the region
$Q^2 \le 1.5 {GeV}^2$, both the transverse amplitude, $A_{1/2}(Q^2)$, and the
longitudinal amplitude, $S_{1/2}(Q^2)$, decrease rapidly. In this work, we
attempt to use first-principles lattice QCD (for the first time) to provide a
model-independent study of the Roper-nucleon transition form factor.


title: Superconductivity at 25 K in hole doped $(La_{1-x}Sr_x)OFeAs$

abstract:
  By partially substituting the tri-valence element La with di-valence element
Sr in $LaOFeAs$, we introduced holes into the system. For the first time, we
successfully synthesized the hole doped new superconductors
$(La_{1-x}Sr_x)OFeAs$. The maximum superconducting transition temperature at
about 25 K was observed at a doping level of x = 0.13. It is evidenced by Hall
effect measurements that the conduction in this type of material is dominated
by hole-like charge carriers, rather than electron-like ones. Together with the
data of the electron doped system $La(O_{1-x}F_x)FeAs$, a generic phase diagram
is depicted and is revealed to be similar to that of the cuprate
superconductors.


title: Averaging of Nonlinearity Management with Dissipation

abstract:
  Motivated by recent experiments in optics and atomic physics, we derive an
averaged nonlinear partial differential equation describing the dynamics of the
complex field in a nonlinear Schroedinger model in the presence of a periodic
nonlinearity and a periodically-varying dissipation coefficient. The
incorporation of dissipation is motivated by experimental considerations. We
test the numerical behavior of the derived averaged equation by comparing it to
the original nonautonomous model in a prototypical case scenario and observe
good agreement between the two.


title: Magneto-optical properties of multilayer graphenes

abstract:
  The magneto-optical absorption properties of graphene multilayers are
theoretically studied. It is shown that the spectrum can be decomposed into
sub-components effectively identical to the monolayer or bilayer graphene,
allowing us to understand the spectrum systematically as a function of the
layer number. Odd-layered graphenes always exhibit absorption peaks which
shifts in proportion to sqrt(B), with B being the magnetic field, due to the
existence of an effective monolayer-like subband. We propose a possibility of
observing the monolayer-like spectrum even in a mixture of multilayer graphene
films with various layers numbers.


title: The cohomology of superspace, pure spinors and invariant integrals

abstract:
  The superform construction of supersymmetric invariants, which consists of
integrating the top component of a closed superform over spacetime, is
reviewed. The cohomological methods necessary for the analysis of closed
superforms are discussed and some further theoretical developments presented.
The method is applied to higher-order corrections in heterotic string theory up
to $\a'^3$. Some partial results on $N=2,d=10$ and $N=1,d=11$ are also given.


title: Bimodality in low luminosity E and S0 galaxies

abstract:
  Stellar population characteristics are presented for a sample of low
luminosity early-type galaxies (LLEs) in order to compare them with their more
luminous counterparts. Long-slit spectra of a sample of 10 LLEs were taken with
the ESO New Technology Telescope, selected for their low luminosities. Line
strengths were measured on the Lick standard system. Lick indices for these
LLEs were correlated with velocity dispersion (sigma), alongside published data
for a variety of Hubble types. The LLEs were found to fall below an
extrapolation of the correlation for luminous ellipticals and were consistent
with the locations of spiral bulges in plots of line strengths versus sigma.
Luminosity weighted average ages, metallicities and abundance ratios were
estimated from chi-squared fitting of 19 Lick indices to predictions from
simple stellar population models. The LLEs appear younger than luminous
ellipticals and of comparable ages to spiral bulges. These LLEs show a bimodal
metallicity distribution, consisting of a low metallicity group (possibly
misclassified dwarf spheroidal galaxies) and a high metallicity group (similar
to spiral bulges). Finally, they have low alpha-element to iron-peak abundance
ratios indicative of slow, extended star formation.


title: Pressure-driven magnetic moment collapse in the ground state of MnO

abstract:
  The zero temperature Mott transition region in antiferromagnetic, spin S=5/2
MnO is probed using the correlated band theory LSDA+U method. The first
transition encountered is an insulator-insulator volume collapse within the
rocksalt structure that is characterized by an unexpected Hund's rule violating
`spin-flip' moment collapse. This spin-flip to S=1/2 takes fullest advantage of
the anisotropy of the Coulomb repulsion, allowing gain in the kinetic energy
(which increases with decreasing volume) while retaining a sizable amount of
the magnetic exchange energy. While transition pressures vary with the
interaction strength, the spin-flip state is robust over a range of interaction
strengths and for both B1 and B8 structures.


title:
Towards a Symbolic-Numeric Method to Compute Puiseux Series: The Modular
  Part

abstract:
  We have designed a new symbolic-numeric strategy to compute efficiently and
accurately floating point Puiseux series defined by a bivariate polynomial over
an algebraic number field. In essence, computations modulo a well chosen prime
$p$ are used to obtain the exact information required to guide floating point
computations. In this paper, we detail the symbolic part of our algorithm:
First of all, we study modular reduction of Puiseux series and give a good
reduction criterion to ensure that the information required by the numerical
part is preserved. To establish our results, we introduce a simple modification
of classical Newton polygons, that we call "generic Newton polygons", which
happen to be very convenient. Then, we estimate the arithmetic complexity of
computing Puiseux series over finite fields and improve known bounds. Finally,
we give bit-complexity bounds for deterministic and randomized versions of the
symbolic part. The details of the numerical part will be described in a
forthcoming paper.


title:
Evaluation of Effective Thermal Conductivities of Porous Textile
  Composites

abstract:
  An uncoupled multi-scale homogenization approach is used to estimate the
effective thermal conductivities of plain weave C/C composites with a high
degree of porosity. The geometrical complexity of the material system on
individual scales is taken into account through the construction of a suitable
representative volume element (RVE), a periodic unit cell, exploiting the
information provided by the image analysis of a real composite system on every
scale. Two different solution procedures are examined. The first one draws on
the classical first order homogenization technique assuming steady state
conditions and periodic distribution of the fluctuation part of the temperature
field. The second approach is concerned with the solution of a transient flow
problem. Although more complex, the latter approach allows for a detailed
simulation of heat transfer in the porous system. Effective thermal
conductivities of the laminate derived from both approaches through a
consistent homogenization on individual scales are then compared with those
obtained experimentally. A reasonably close agreement between individual
results then promotes the use of the proposed multi-scale computational
approach combined with the image analysis of real material systems.


title: Eigenvectors in the Superintegrable Model II: Ground State Sector

abstract:
  In 1993, Baxter gave $2^{m_Q}$ eigenvalues of the transfer matrix of the
$N$-state superintegrable chiral Potts model with spin-translation quantum
number $Q$, where $m_Q=\lfloor(NL-L-Q)/N\rfloor$. In our previous paper we
studied the Q=0 ground state sector, when the size $L$ of the transfer matrix
is chosen to be a multiple of $N$. It was shown that the corresponding $\tau_2$
matrix has a degenerate eigenspace generated by the generators of $r=m_0$
simple $sl_2$ algebras. These results enable us to express the transfer matrix
in the subspace in terms of these generators $E_m^{\pm}$ and $H_m$ for
$m=1,...,r$. Moreover, the corresponding $2^r$ eigenvectors of the transfer
matrix are expressed in terms of rotated eigenvectors of $H_m$.


title: Projectile interactions in granular impact cratering

abstract:
  We present evidence for the interactions between a ball and the container
boundaries, as well as between two balls, that are mediated by the granular
medium during impact cratering. The presence of the bottom boundary affects the
final penetration depth only for low drop heights with shallow filling, in
which case, surprisingly, the penetration becomes deeper. By contrast the
presence of the side wall causes less penetration and also an effective
repulsion. Repulsion is also found for two balls dropped side-by-side.


title: Graphene-Based Liquid Crystal Device

abstract:
  Graphene is only one atom thick, optically transparent, chemically inert and
an excellent conductor. These properties seem to make this material an
excellent candidate for applications in various photonic devices that require
conducting but transparent thin films. In this letter we demonstrate liquid
crystal devices with electrodes made of graphene which show excellent
performance with a high contrast ratio. We also discuss the advantages of
graphene compared to conventionally-used metal oxides in terms of low
resistivity, high transparency and chemical stability.


title:
Galactic fountains and their connection with high and intermediate
  velocity clouds

abstract:
  The aim of this paper is to calculate the expansion law and chemical
enrichment of a supershell powered by the energetic feedback of a typical
Galactic OB association at various galactocentric radii. We study then the
orbits of the fragments created when the supershell breaks out and we compare
their kinetic and chemical properties with the available observations of high -
and intermediate - velocity clouds. We use the Kompaneets (1960) approximation
for the evolution of the superbubble driven by sequential supernova explosions
and we compute the abundances of oxygen and iron residing in the thin cold
supershell. We assume that supershells are fragmented by means of
Rayleigh-Taylor instabilities and we follow the orbit of the clouds either
ballistically or by means of a hybrid model considering viscous interaction
between the clouds and the extra-planar gas.Given the self-similarity of the
Kompaneets solutions, clouds are always formed ~ 448 pc above the plane. If the
initial metallicity is solar, the pollution from dying stars of the OB
association has a negligible effect on the chemical composition of the clouds.
The maximum height reached by the clouds above the plane seldom exceeds 2 kpc
and when averaging over different throwing angles, the landing coordinate
differs from the throwing coordinate ~ 1 kpc at most. The range of heights and
[O/Fe] ratios spun by our clouds suggest us that the high velocity clouds
cannot have a Galactic origin, whereas intermediate velocity clouds have
kinematic properties similar to our modeled clouds but overabundance observed
for the [O/Fe] ratios which can be reproduced only with initial metallicities
which are too low compared for those of the Galaxy disk.


title: A modified peak-bagging technique for fitting low-$\ell$ solar p-modes

abstract:
  We introduce a modified version of a standard power spectrum `peak-bagging'
technique which is designed to gain some of the advantages that fitting the
entire low-degree p-mode power spectrum simultaneously would bring, but without
the problems involved in fitting a model incorporating many hundreds of
parameters. Employing Monte-Carlo simulations we show that by using this
modified fitting code it is possible to determine the true background level in
the vicinity of the p-mode peaks. In addition to this we show how small biases
in other mode parameters, which are related to inaccurate estimates of the true
background, are also consequently removed.


title: A Covariant model for the nucleon and the $\Delta$

abstract:
  The covariant spectator formalism is used to model the nucleon and the
$\Delta$(1232) as a system of three constituent quarks with their own
electromagnetic structure. The definition of the ``fixed-axis'' polarization
states for the diquark emitted from the initial state vertex and absorbed into
the final state vertex is discussed. The helicity sum over those states is
evaluated and seen to be covariant. Using this approach, all four
electromagnetic form factors of the nucleon, together with the {\it magnetic}
form factor, $G_M^*$, for the $\gamma N \to \Delta$ transition, can be
described using manifestly covariant nucleon and $\Delta$ wave functions with
{\it zero} orbital angular momentum $L$, but a successful description of
$G_M^*$ near $Q^2=0$ requires the addition of a pion cloud term not included in
the class of valence quark models considered here. We also show that the pure
$S$-wave model gives electric, $G_E^*$, and coulomb, $G^*_C$, transition form
factors that are identically zero, showing that these form factors are
sensitive to wave function components with $L>0$.


title: On the vacuum states for noncommutative gauge theory

abstract:
  Candidates for renormalisable gauge theory models on Moyal spaces constructed
recently have non trivial vacua. We show that these models support vacuum
states that are invariant under both global rotations and symplectic
isomorphisms which form a global symmetry group for the action. We compute the
explicit expression in the position space for these vacuum configurations in
two and four dimensions.


title: Interacting Dark Energy with Inhomogeneous Equation of State

abstract:
  We have investigated the model of dark energy interacting with dark matter by
choosing inhomogeneous equations of state for dark energy and a non-linear
interaction term for the underlying interaction. The equation of state have
dependencies either on the energy densities, redshift, Hubble parameter and its
derivatives or the bulk viscosity. We have considered these possibilities and
have derived the effective equations of state for the dark energy in each case.


title: Liquid bridges and black strings in higher dimensions

abstract:
  Analyzing a capillary minimizing problem for a higher-dimensional extended
fluid, we find that there exist startling similarities between the black
hole-black string system (the Gregory-Laflamme instability) and the liquid
drop-liquid bridge system (the Rayleigh-Plateau instability), which were first
suggested by a perturbative approach. In the extended fluid system, we confirm
the existence of the critical dimension above which the non-uniform bridge
(NUB, i.e., {\it Delaunay unduloid}) serves as the global minimizer of surface
area. We also find a variety of phase structures (one or two cusps in the
volume-area phase diagram) near the critical dimension. Applying a catastrophe
theory, we predict that in the 9 dimensional (9D) space and below, we have the
first order transition from a uniform bridge (UB) to a spherical drop (SD),
while in the 10D space and above, we expect the transition such that UB $\to$
NUB $\to$ SD. This gives an important indication for a transition in the black
hole-black string system.

categories: hep-th gr-qc math-ph math.MP physics.flu-dyn


title: Response of a ferrofluid to traveling-stripe forcing

abstract:
  We observe the dynamics of waves propagating on the surface of a ferrofluid
under the influence of a spatially and temporarily modulated field. In
particular, we excite plane waves by a travelling lamellar modulation of the
magnetization. By this external driving both the wavelength and the propagation
velocity of the waves can be controlled. The amplitude of the excited waves
exhibits a resonance phenomenon similar to that of a forced harmonic
oscillator. Its analysis reveals the dispersion relation of the free surface
waves, from which the critical magnetic field for the onset of the Rosensweig
instability can be extrapolated.


title:
The Nonlinear Dirac Equation in Bose-Einstein Condensates: Foundation
  and Symmetries

abstract:
  We show that Bose-Einstein condensates in a honeycomb optical lattice are
described by a nonlinear Dirac equation in the long wavelength, mean field
limit. Unlike nonlinear Dirac equations posited by particle theorists, which
are designed to preserve the principle of relativity, i.e., Poincar\'e
covariance, the nonlinear Dirac equation for Bose-Einstein condensates breaks
this symmetry. We present a rigorous derivation of the nonlinear Dirac equation
from first principles. We provide a thorough discussion of all symmetries
broken and maintained.


title: Astronomy with ultra high-energy particles

abstract:
  Recent measurements of the properties of cosmic rays above 10^17 eV are
summarized and implications on our contemporary understanding of their origin
are discussed. Cosmic rays with energies exceeding 10^20 eV have been measured,
they are the highest-energy particles in the Universe. Particles at highest
energies are expected to be only marginally deflected by magnetic fields and
they should point towards their sources on the sky. Recent results of the
Pierre Auger Observatory have opened a new window to the Universe - astronomy
with ultra high-energy particles.


title: Non-minimally coupled vector curvaton

abstract:
  It is shown that a massive Abelian vector boson field can generate the
curvature perturbation in the Universe, when coupled non-minimally to gravity,
through an RA^2 coupling. The vector boson acts as a curvaton field imposing
the curvature perturbation after the end of inflation, without generating a
large-scale anisotropy. The parameter space of the model is fully explored,
obtaining the relevant bounds on the inflation scale and the decay constant of
the vector curvaton.


title:
Product-form stationary distributions for deficiency zero chemical
  reaction networks

abstract:
  We consider stochastically modeled chemical reaction systems with mass-action
kinetics and prove that a product-form stationary distribution exists for each
closed, irreducible subset of the state space if an analogous deterministically
modeled system with mass-action kinetics admits a complex balanced equilibrium.
Feinberg's deficiency zero theorem then implies that such a distribution exists
so long as the corresponding chemical network is weakly reversible and has a
deficiency of zero. The main parameter of the stationary distribution for the
stochastically modeled system is a complex balanced equilibrium value for the
corresponding deterministically modeled system. We also generalize our main
result to some non-mass-action kinetics.


title:
Gaussian effective potential for the standard model SU(2)xU(1)
  electroweak theory

abstract:
  The Gaussian Effective Potential (GEP) is derived for the non-Abelian
SU(2)xU(1) gauge theory of electroweak interactions. First the problem of gauge
invariance is addressed in the Abelian U(1) theory, where an optimized GEP is
shown to be gauge invariant. The method is then extended to the full
non-Abelian gauge theory where, at variance with naive derivations, the GEP is
proven to be a genuine variational tool in any gauge. The role of ghosts is
discussed and the unitarity gauge is shown to be the only choice which allows
calculability without insertion of further approximations. The GEP for the
standard model is derived and its predictions are compared to the known
phenomenology, thus showing that the GEP provides an alternative
non-perturbative description of the known experimental data. By a consistent
renormalization of masses the full non-Abelian calculation confirms the
existence of a light Higgs boson in the non-perturbative strong coupling regime
of the Higgs sector.


title: Neutrino mass hierarchy extraction using atmospheric neutrinos in ice

abstract:
  We show that the measurements of 10 GeV atmospheric neutrinos by an upcoming
array of densely packed phototubes buried deep inside the IceCube detector at
the South Pole can be used to determine the neutrino mass hierarchy for values
of sin^2(2theta13) close to the present bound, if the hierarchy is normal.
These results are obtained for an exposure of 100 Mton years and systematic
uncertainties up to 10%.


title:
Kinematics of Stars in Kapteyn Selected Area 71: Sampling the Monoceros
  and Sagittarius Tidal Streams

abstract:
  We present a 3D kinematical analysis of stars located in Kapteyn Selected
Area 71 (l = 167.1, b = -34.7), where previously a stellar excess was found
(Dinescu et al. 2002, Newberg et al. 2002). Previous findings indicated that
the stellar excess has a cold kinematical signature as inferred from proper
motions, and was initially associated with debris from the Sagittarius dwarf
galaxy (Sgr) -- namely the southern trailing tail. We have obtained radial
velocities using the Hydra multiobject spectrograph on the WIYN 3.5 m
telescope. Results for 183 proper-motion selected stars indicate that the
dominant population in this stellar excess is not debris from Sgr, but rather a
population that kinematically belongs to the ring-like stream that is now known
as the Monoceros stream. The orbit determined for this population agrees very
well with the predictions for the Monoceros stream from Penarrubia et al.
(2005). The radial-velocity dispersion of this population is between 20 and 30
km/s, lower than that of the Galactic field. Also, the shape of the
radial-velocity distribution shows a sharp cut-off on one side, which is more
in line with model predictions of the disruption of a satellite rather than
with the distribution of the Galactic field. Despite the fact that we now
believe most of the stars in the stellar excess to be part of Monoceros, about
ten stars in this stellar excess have highly negative radial velocities, which
is a clear indication of their membership to the Sgr trailing tidal tail.


title: Collective orbital excitations in orbitally ordered YVO3 and HoVO3

abstract:
  We study orbital excitations in the optical absorption spectra of YVO3 and
HoVO3. We focus on an orbital absorption band observed at 0.4 eV for
polarization E parallel c. This feature is only observed in the intermediate,
monoclinic phase. By comparison with the local crystal-field excitations in
VOCl and with recent theoretical predictions for the crystal-field levels we
show that this absorption band cannot be interpreted in terms of a local
crystal-field excitation. We discuss a microscopic model which attributes this
absorption band to the exchange of two orbitals on adjacent sites, i.e., to the
direct excitation of two orbitons. This model is strongly supported by the
observed dependence on polarization and temperature. Moreover, the calculated
spectral weight is in good agreement with the experimental result.


title:
A functional clustering algorithm for the analysis of dynamic network
  data

abstract:
  We formulate a novel technique for the detection of functional clusters in
discrete event data. The advantage of this algorithm is that no prior knowledge
of the number of functional groups is needed, as our procedure progressively
combines data traces and derives the optimal clustering cutoff in a simple and
intuitive manner through the use of surrogate data sets. In order to
demonstrate the power of this algorithm to detect changes in network dynamics
and connectivity, we apply it to both simulated neural spike train data and
real neural data obtained from the mouse hippocampus during exploration and
slow-wave sleep. Using the simulated data, we show that our algorithm performs
better than existing methods. In the experimental data, we observe
state-dependent clustering patterns consistent with known neurophysiological
processes involved in memory consolidation.


title: Low density Neutron Matter at Finite and Zero Temperatures

abstract:
  This report concerns the energy of neutron-matter for densities below $0.15
fm^{-3}$ and temperatures at and below $10 MeV$. Separable NN-interactions are
obtained by inverse scattering from the experimental phase-shifts with
specified momentum cut-offs $\Lambda$. Results of Brueckner-Bloch-DeDomicis as
well as finite temperature Green's function calculations show independence of
cut-off for $\Lambda \geq 3$. Agreement with the low-density virial expansion
is found. Results of Hartree-Fock as well as second order calculations show
considerable $\Lambda$-dependence and the agreement with the virial expansion
is lost. The "best" first-order choice of $\Lambda$ is found to be $\sim 2.5
fm^{-1}$, which agrees with $V_{low k}$ studies. Reasonable agreement between
the second order and the Brueckner results is also found for this value of
$\Lambda$ except at low density. Only 2-body forces are used in this study.


title: Geometric phase in external electromagnetic fields

abstract:
  Variations of polarization of the electronic field is a dielectric property
quantified by Resta et al. and discovered to be a Berry phase of the electronic
subsystem. In order to continue the previous research we wrote a scalar phase
\Phi as the circulation of the polarization field or in alternative and in a
more general form as the flux of a new vector field called macroscopic rotonic
field. The latter shows to be a more general scalar Berry phase concerning the
interaction of the electronic subsystem with an external electromagnetic field.


title: Intensity correlations in resonance nonlinear magneto-optical rotation

abstract:
  We have studied the intensity correlations between two orthogonally linearly
polarized components of a laser field propagating through a resonant atomic
medium. These experiments have been performed in a Rubidium atomic vapor. We
observe that the correlations between the orthogonally polarized components of
the laser beam are maximal in the absence of a magnetic field. The magnitude of
the correlations depends on the applied magnetic field, and the magnitude first
decreases and then increases with increasing magnetic field. Minimal
correlations and maximal rotation angles are observed at the same magnetic
fields. The width of the correlation function is directly proportional to the
excited state lifetime and inversely proportional to the Rabi frequency of
laser field. These results can be useful for improving optical magnetometers
and for optical field or atomic spin squeezing.


title: Scientific Evidence for Hydrostatic Shock

abstract:
  This paper reviews the scientific support for a ballistic pressure wave
radiating outward from a penetrating projectile and causing injury and
incapacitation. This phenomenon is known colloquially as "hydrostatic shock."
The idea apparently originates with Col. Frank Chamberlin, a World War II
trauma surgeon and wound ballistics researcher. The paper reviews claims that
hydrostatic shock is a myth and considers supporting evidence through parallels
with blast, describing the physics of the pressure wave, evidence for remote
cerebral effects, and remote effects in the spine and other internal organs.
Finally, the review considers the levels of energy transfer required for the
phenomenon to be readily observed.


title:
Evidence for pairing above Tc from the dispersion in the pseudogap phase
  of cuprates

abstract:
  In the underdoped high temperature superconductors, instead of a complete
Fermi surface above Tc, only disconnected Fermi arcs appear, separated by
regions that still exhibit an energy gap. We show that in this pseudogap phase,
the energy-momentum relation of electronic excitations near E_F behaves like
the dispersion of a normal metal on the Fermi arcs, but like that of a
superconductor in the gapped regions. We argue that this dichotomy in the
dispersion is hard to reconcile with a competing order parameter, but is
consistent with pairing without condensation.


title: The Ballistic Pressure Wave Theory of Handgun Bullet Incapacitation

abstract:
  This paper presents a summary of seven distinct chains of evidence, which,
taken together, provide compelling support for the theory that a ballistic
pressure wave radiating outward from the penetrating projectile can contribute
to wounding and incapacitating effects of handgun bullets. These chains of
evidence include the fluid percussion model of traumatic brain injury,
observations of remote ballistic pressure wave injury in animal models,
observations of rapid incapacitation highly correlated with pressure magnitude
in animal models, epidemiological data from human shootings showing that the
probability of incapacitation increases with peak pressure magnitude, case
studies in humans showing remote pressure wave damage in the brain and spinal
cord, and observations of blast waves causing remote brain injury.


title: A multi-frequency high-field pulsed EPR / ENDOR spectrometer

abstract:
  We describe a pulsed multi-frequency electron paramagnetic resonance
spectrometer operating at several frequencies in the range of 110-336 GHz. The
microwave source at all frequencies consists of a multiplier chain starting
from a solid state synthesizer in the 12-15 GHz range. A fast PIN-switch at the
base frequency creates the pulses. At all frequencies a Fabry-Perot resonator
is employed and the pi/2 pulse length ranges from ~100 ns at 110 GHz to ~600 ns
at 334 GHz. Measurements of a single crystal containing dilute Mn2+ impurities
at 12 T illustrate the effects of large electron spin polarizations. The
capabilities also allow for pulsed electron nuclear double resonance
experiments as demonstrated by Mims ENDOR of 39K nuclei in Cr:K3NbO8.


title:
Limit Cycles of a Quadratic System with Two Parallel Straight
  Line-Isoclines

abstract:
  In this paper, a quadratic system with two parallel straight line-isoclines
is considered. This system corresponds to the system of class II in the
classification of Ye Yanqian. Using the field rotation parameters of the
constructed canonical system and geometric properties of the spirals filling
the interior and exterior domains of its limit cycles, we prove that the
maximum number of limit cycles in a quadratic system with two parallel straight
line-isoclines and two finite singular points is equal to two. Besides, we
obtain the same result in a different way: applying the Wintner-Perko
termination principle for multiple limit cycles and using the methods of global
bifurcation theory developed earlier by the author.


title:
Hidden magnetic frustration by quantum relaxation in anisotropic
  Nd-langasite

abstract:
  The static and dynamic magnetic properties of the Nd$_3$Ga$_5$SiO$_{14}$
compound, which appears as the first materialization of a rare-earth
kagome-type lattice, were re-examined, owing to contradictory results in the
previous studies. Neutron scattering, magnetization and specific heat
measurements were performed and analyzed, in particular by fully taking account
of the crystal electric field effects on the Nd$^{3+}$ ions. One of the novel
findings is that the peculiar temperature independent spin dynamics observed
below 10 K expresses single-ion quantum processes. This would short-circuit the
frustration induced cooperative dynamics, which would emerge only at very low
temperature.


title: Edge connectivity in graphs: an expansion theorem

abstract:
  We show that if a graph is k-edge-connected, and we adjoin to it another
graph satisfying a "contracted diameter less or equal to 2" condition, with
minimal degree greater or equal to k, and some natural hypothesis on the edges
connecting one graph to the other, the resulting graph is also
k-edge-connected.


title:
Colossal spin fluctuations in a molecular quantum dot magnet with
  ferromagnetic electrodes

abstract:
  We study electronic transport through a magnetic molecule with an intrinsic
spin $S$ coupled to two magnetic electrodes, in the incoherent regime. The
molecule is modeled as a single resonant level with large Coulomb repulsion (no
double occupancy). The molecular spin is isotropic and it interacts with the
electronic spin through an exchange interaction. Using an alternative method to
the usual master equation approach, we are able to obtain analytical formulas
for various physical quantities of interest, such as the mean current and the
current fluctuations, but also the mean value of $J_z$ -the $z$ component of
the total spin on the molecule- and its fluctuations. This allows us to
understand how the electronic current between the magnetized electrodes can
control the polarization of the molecular spin. We observe in particular that
the fluctuations of $J_z$ reach unexpectedly high values.


title:
Repeated quantum interactions Quantum Langevin equation and the low
  density limit

abstract:
  We consider a repeated quantum interaction model describing a small system
$\Hh_S$ in interaction with each one of the identical copies of the chain
$\bigotimes_{\N^*}\C^{n+1}$, modeling a heat bath, one after another during the
same short time intervals $[0,h]$. We suppose that the repeated quantum
interaction Hamiltonian is split in two parts: a free part and an interaction
part with time scale of order $h$. After giving the GNS representation, we
establish the relation between the time scale $h$ and the classical low density
limit. We introduce a chemical potential $\mu$ related to the time $h$ as
follows: $h^2=e^{\beta\mu}$. We further prove that the solution of the
associated discrete evolution equation converges strongly, when $h$ tends to 0,
to the unitary solution of a quantum Langevin equation directed by Poisson
processes.


title: A Lindblad model for a spin chain coupled to heat baths

abstract:
  We study a XY model which consists of a spin chain coupled to heat baths. We
give a repeated quantum interaction Hamiltonian describing this model. We
compute the explicit form of the associated Lindblad generator in the case of
the spin chain coupled to one, two and several heat baths. We further study the
properties of quantum master equation such as approach to equilibrium, local
equilibrium states, entropy production and quantum detailed balance condition.


title:
Constraint satisfaction problems and neural networks: a statistical
  physics perspective

abstract:
  A new field of research is rapidly expanding at the crossroad between
statistical physics, information theory and combinatorial optimization. In
particular, the use of cutting edge statistical physics concepts and methods
allow one to solve very large constraint satisfaction problems like random
satisfiability, coloring, or error correction. Several aspects of these
developments should be relevant for the understanding of functional complexity
in neural networks. On the one hand the message passing procedures which are
used in these new algorithms are based on local exchange of information, and
succeed in solving some of the hardest computational problems. On the other
hand some crucial inference problems in neurobiology, like those generated in
multi-electrode recordings, naturally translate into hard constraint
satisfaction problems. This paper gives a non-technical introduction to this
field, emphasizing the main ideas at work in message passing strategies and
their possible relevance to neural networks modeling. It also introduces a new
message passing algorithm for inferring interactions between variables from
correlation data, which could be useful in the analysis of multi-electrode
recording data.


title:
A support theorem for the geodesic ray transform of symmetric tensor
  fields

abstract:
  Let $(M,g)$ be a simple Riemannian manifold with boundary and consider the
geodesic ray transform of symmetric 2-tensor fields. Let the integral of $f$
along maximal geodesics vanish on an appropriate open subset of the space of
geodesics in $M$. Under the assumption that the metric $g$ is real-analytic, it
is shown that there exists a vector field $v$ satisfying $f=dv$ on the set of
points lying on these geodesics and $v=0$ on the intersection of this set with
the boundary $\PD M$ of the manifold $M$. Using this result, a Helgason's type
of a support theorem for the geodesic ray transform is proven. The approach is
based on analytic microlocal techniques.


title: Arithmetic E_8 lattices with maximal Galois action

abstract:
  We construct explicit examples of E_8 lattices occurring in arithmetic for
which the natural Galois action is equal to the full group of automorphisms of
the lattice, i.e., the Weyl group of E_8. In particular, we give explicit
elliptic curves over Q(t) whose Mordell-Weil lattices are isomorphic to E_8 and
have maximal Galois action.
  Our main objects of study are del Pezzo surfaces of degree 1 over number
fields. The geometric Picard group, considered as a lattice via the negative of
the intersection pairing, contains a sublattice isomorphic to E_8. We construct
examples of such surfaces for which the action of Galois on the geometric
Picard group is maximal.


title: Star Models with Dark Energy

abstract:
  We have constructed star models consisting of four parts: (i) a homogeneous
inner core with anisotropic pressure (ii) an infinitesimal thin shell
separating the core and the envelope; (iii) an envelope of inhomogeneous
density and isotropic pressure; (iv) an infinitesimal thin shell matching the
envelope boundary and the exterior Schwarzschild spacetime. We have analyzed
all the energy conditions for the core, envelope and the two thin shells. We
have found that, in order to have static solutions, at least one of the regions
must be constituted by dark energy. The results show that there is no physical
reason to have a superior limit for the mass of these objects but for the ratio
of mass and radius.


title:
The two-loop QCD amplitude gg -> h,H in the Minimal Supersymmetric
  Standard Model

abstract:
  We present the two-loop QCD amplitude for the interaction of two gluons and a
CP-even Higgs boson in the Minimal Supersymmetric Standard Model. We apply a
novel numerical method for the evaluation of Feynman diagrams with infrared,
ultraviolet and threshold singularities. We discuss subtleties in the
ultraviolet renormalization of the amplitude with conventional dimensional
regularization, dimensional reduction, and the four dimensional helicity
scheme. Finally, we show numerical results for scenarios of supersymmetry
breaking with a rather challenging phenomenology in which the Higgs signal in
the MSSM is suppressed in comparison to the Standard Model.


title:
A communication-efficient nonlocal measurement with application to
  communication complexity and bipartite gate capacities

abstract:
  Two dual questions in quantum information theory are to determine the
communication cost of simulating a bipartite unitary gate, and to determine
their communication capacities. We present a bipartite unitary gate with two
surprising properties: 1) simulating it with the assistance of unlimited EPR
pairs requires far more communication than with a better choice of entangled
state, and 2) its communication capacity is far lower than its capacity to
create entanglement. This suggests that 1) unlimited EPR pairs are not the most
general model of entanglement assistance for two-party communication tasks, and
2) the entangling and communicating abilities of a unitary interaction can vary
nearly independently. The technical contribution behind these results is a
communication-efficient protocol for measuring whether an unknown shared state
lies in a specified rank-one subspace or its orthogonal complement.


title: Effects of Metallicity on the Chemical Composition of Carbon Stars

abstract:
  We present \emph{Spitzer} IRS data on 19 asymptotic giant branch (AGB) stars
in the Large Magellanic Cloud, complementing existing published data sets of
carbon stars in both Magellanic Clouds and the Milky Way, to investigate the
effects of metallicity on dust and molecular spectral features arising from the
circumstellar envelope. We find that the C$_2$H$_2$ P and R branches at 7.5
micron are affected by dust dilution at higher mass-loss rates -- albeit to a
lesser extent for sources in the Magellanic Clouds, compared to the Milky Way
-- while the narrow 13.7 micron C$_2$H$_2$ Q branch only shows the effect of
dust dilution at low mass-loss rates. A strong metallicity dependence is not
observed for the Q branch. Independent of metallicity, we also provide an
explanation for the observed shifts in the central wavelength of the SiC
emission feature, as we show that these are largely caused by molecular band
absorption on either side of the dust emission feature, dominating over shifts
in the central wavelength caused by self-absorption. We have devised a method
to study the dust condensation history in carbon-rich AGB stars in different
metallicity environments, by measuring the strength of the 11.3 \um SiC and 30
\um MgS features with respect to the continuum, as a function of mass-loss
rate. With this method, it is possible to distinguish in what order SiC and
graphite condense, which is believed to be sensitive to the metallicity, prior
to the eventual deposit of the MgS layer.


title: Dynamics of Warped Flux Compactifications

abstract:
  We discuss the four dimensional effective action for type IIB flux
compactifications, and obtain the quadratic terms taking warp effects into
account. The analysis includes both the 4-d zero modes and their KK
excitations, which become light at large warping. We identify an `axial' type
gauge for the supergravity fluctuations, which makes the four dimensional
degrees of freedom manifest. The other key ingredient is the existence of
constraints coming from the ten dimensional equations of motion. Applying these
conditions leads to considerable simplifications, enabling us to obtain the low
energy lagrangian explicitly. In particular, the warped K\"ahler potential for
metric moduli is computed and it is shown that there are no mixings with the KK
fluctuations and the result differs from previous proposals. The four
dimensional potential contains a generalization of the Gukov-Vafa-Witten term,
plus usual mass terms for KK modes.


title: Fuel for Galaxy Disks

abstract:
  Halo clouds have been found about the three largest galaxies of the Local
Group and in the halos of nearby spirals. This suggests they are a relatively
generic feature of the galaxy evolution process and a source of fuel for galaxy
disks. In this review, two main sources of disk star formation fuel, satellite
material and clouds condensing from the hot halo medium, are discussed and
their contribution to fueling the Galaxy quantified. The origin of the halo gas
of M31 and M33 is also discussed.


title:
Acceleration, Energy Loss and Screening in Strongly-Coupled Gauge
  Theories

abstract:
  We explore various aspects of the motion of heavy quarks in strongly-coupled
gauge theories, employing the AdS/CFT correspondence. Building on earlier work
by Mikhailov, we study the dispersion relation and energy loss of an
accelerating finite-mass quark in N=4 super-Yang-Mills, both in vacuum and in
the presence of a thermal plasma. In the former case, we notice that the
application of an external force modifies the dispersion relation. In the
latter case, we find in particular that when a static heavy quark is
accelerated by an external force, its rate of energy loss is initially
insensitive to the plasma, and there is a delay before this rate approaches the
value derived previously from the analysis of stationary or late-time
configurations.
  Following up on work by Herzog et al., we also consider the evolution of a
quark and antiquark as they separate from one another after formation, learning
how the AdS/CFT setup distinguishes between the singlet and adjoint
configurations, and locating the transition to the stage where the deceleration
of each particle is properly accounted for by a constant friction coefficient.
Additionally, we examine the way in which the energy of a quark-antiquark pair
moving jointly through the plasma scales with the quark mass. We find that the
velocity-dependence of the screening length is drastically modified in the
ultra-relativistic region, and is comparable with that of the transition
distance mentioned above.


title: Evidence for metallicity spreads in three massive M31 globular clusters

abstract:
  We quantify the intrinsic width of the red giant branches of three massive
globular clusters in M31 in a search for metallicity spreads within these
objects. We present HST/ACS observations of three massive clusters in M31, G78,
G213, and G280. A thorough description of the photometry extraction and
calibration is presented. After derivation of the color-magnitude diagrams, we
quantify the intrinsic width of the red giant branch of each cluster. This
width translates into a metallicity dispersion that indicates a complex star
formation history for this type of system. For G78, sigma_[Fe/H]}=0.86 \pm
0.37; for G213, 0.89 \pm 0.20; and for G280, 1.03 \pm 0.26. We find that the
metallicity dispersion of the clusters does not scale with mean metallicity. We
also find no trend with the cluster mass. We discuss some possible formation
scenarios that would explain our results.


title:
Robin-to-Robin Maps and Krein-Type Resolvent Formulas for Schr\"odinger
  Operators on Bounded Lipschitz Domains

abstract:
  We study Robin-to-Robin maps, and Krein-type resolvent formulas for
Schr\"odinger operators on bounded Lipschitz domains in $\bbR^n$, $n\ge 2$,
with generalized Robin boundary conditions.


title: Three notions of effective computation on $\mathbb{R}$

abstract:
  We compare three notions of effectiveness on uncountable structures. The
first notion is that of a $\real$-computable structure, based on a model of
computation proposed by Blum, Shub, and Smale, which uses full-precision real
arithmetic. The second notion is that of an $F$-parameterizable structure,
defined by Morozov and based on Mal'tsev's notion of a constructive structure.
The third is $\Sigma$-definability over $HF(\real)$, defined by Ershov as a
generalization of the observation that the computably enumerable sets are
exactly those $\Sigma_1$-definable in $HF(\mathbb{N})$.
  We show that every $\real$-computable structure has an $F$-parameterization,
but that the expansion of the real field by the exponential function is
$F$-parameterizable but not $\real$-computable. We also show that the
structures with $\real$-computable copies are exactly the structures with
copies $\Sigma$-definable over $HF(\real)$. One consequence of this equivalence
is a method of approximating certain $\real$-computable structures by Turing
computable structures.


title:
Fundamental Solutions for the Klein-Gordon Equation in de Sitter
  Spacetime

abstract:
  In this article we construct the fundamental solutions for the Klein-Gordon
equation in de Sitter spacetime. We use these fundamental solutions to
represent solutions of the Cauchy problem and to prove $L^p-L^q$ estimates for
the solutions of the equation with and without a source term.


title:
A shallow though extensive H2 2.12 micron imaging survey of
  Taurus-Auriga-Perseus: I. NGC1333, L1455, L1448 and B1

abstract:
  We discuss wide-field near-IR imaging of the NGC1333, L1448, L1455 and B1
star forming regions in Perseus. The observations have been extracted from a
much larger narrow-band imaging survey of the Taurus-Auriga-Perseus complex.
These H2 2.12 micron observations are complemented by broad-band K imaging,
mid-IR imaging and photometry from the Spitzer Space Telescope, and published
submillimetre CO J=3-2 maps of high-velocity molecular outflows. We detect and
label 85 H2 features and associate these with 26 molecular outflows. Three are
parsec-scale flows, with a mean flow lobe length exceeding 11.5 arcmin. 37
(44%) of the detected H2 features are associated with a known Herbig-Haro
object, while 72 (46%) of catalogued HH objects are detected in H2 emission.
Embedded Spitzer sources are identified for all but two of the 26 molecular
outflows. These candidate outflow sources all have high near-to-mid-IR spectral
indices (mean value of alpha ~ 1.4) as well as red IRAC 3.6-4.5 micron and
IRAC/MIPS 4.5-24.0 micron colours: 80% have [3.6]-[4.5] > 1.0 and [4.5]-[24] >
1.5. These criteria - high alpha and red [4.5]-[24] and [3.6]-[4.5] colours -
are powerful discriminants when searching for molecular outflow sources.
However, we find no correlation between alpha and flow length or opening angle,
and the outflows appear randomly orientated in each region. The more massive
clouds are associated with a greater number of outflows, which suggests that
the star formation efficiency is roughly the same in each region.


title: Digital holography with ultimate sensitivity

abstract:
  We propose a variant of the heterodyne holography scheme that combines the
properties of off-axis and phase-shifting holography. This scheme makes it
possible to filter off numerically the zero-order image alias and the technical
noise of the reference. It is then possible to record and reconstruct
holographic images at an extremely low signal level. We show experimentally
that the sensitivity of the method is limited only by the quantum nature of
photons.


title:
The close circumstellar environment of the semi-regular S-type star Pi^1
  Gruis

abstract:
  We study the close circumstellar environment of the nearby S-type star Pi^1
Gruis using high spatial-resolution, mid-infrared observations from the
ESO/VLTI. Spectra and visibilities were obtained with the MIDI interferometer
on the VLT Auxiliary Telescopes. The cool M5III giant Beta Gruis was used as
bright primary calibrator, and a dedicated spectro-interferometric study was
undertaken to determine its angular diameter accurately. The MIDI measurements
were fitted with the 1D numerical radiative transfer code DUSTY to determine
the dust shell parameters of Pi^1 Gruis. Taking into account the low spatial
extension of the model in the 8-9 $\mu$m spectral band for the smallest
projected baselines, we consider the possibility of a supplementary molecular
shell. The MIDI visibility and phase data are mostly dominated by the spherical
21 mas (694 Rsol) central star, while the extended dusty environment is
over-resolved even with the shortest baselines. No obvious departure from
spherical symmetry is found on the milliarcsecond scale. The
spectro-interferometric observations are well-fitted by an optically thin
(tau(dust)<0.01 in the band) dust shell that is located at about 14 stellar
radii with a typical temperature of 700 K and composed of 70% silicate and 30%
of amorphous alumina grains. An optically thin (tau(mol)<0.1 in the N band)
H2O+SiO molecular shell extending from the photosphere of the star up to 4.4
stellar radii with a typical temperature of 1000 K is added to the model to
improve the fit in the 8-9 $\mu$m spectral band. We discuss the probable binary
origin of asymmetries as revealed by millimetric observations.


title:
Generalized Hunter-Saxton equation and the geometry of the group of
  circle diffeomorphisms

abstract:
  We study an equation lying `mid-way' between the periodic Hunter-Saxton and
Camassa-Holm equations, and which describes evolution of rotators in liquid
crystals with external magnetic field and self-interaction. We prove that it is
an Euler equation on the diffeomorphism group of the circle corresponding to a
natural right-invariant Sobolev metric. We show that the equation is
bihamiltonian and admits both cusped, as well as smooth, traveling-wave
solutions which are natural candidates for solitons. We also prove that it is
locally well-posed and establish results on the lifespan of its solutions.
Throughout the paper we argue that despite similarities to the KdV, CH and HS
equations, the new equation manifests several distinctive features that set it
apart from the other three.


title: Graph polynomials and their applications I: The Tutte polynomial

abstract:
  In this survey of graph polynomials, we emphasize the Tutte polynomial and a
selection of closely related graph polynomials. We explore some of the Tutte
polynomial's many properties and applications and we use the Tutte polynomial
to showcase a variety of principles and techniques for graph polynomials in
general. These include several ways in which a graph polynomial may be defined
and methods for extracting combinatorial information and algebraic properties
from a graph polynomial. We also use the Tutte polynomial to demonstrate how
graph polynomials may be both specialized and generalized, and how they can
encode information relevant to physical applications. We conclude with a brief
discussion of computational complexity considerations.


title: Electrodynamics in Superconductors Explained by Proca Equations

abstract:
  A fully consistent model to study electrodynamics for superconductors in the
stationary and non-stationary regime has been developed based on Proca
equations and a massive photon. In particular, this approach has been applied
to study the electric field penetration depth in superconductors. The model
shows a deviation from the charge contribution to an internal electric field
compared to previous approaches.


title:
Comment on "Nonlinearity of the Field Induced by a Rotating
  Superconducting Shell"

abstract:
  An extension to the model from Berger is proposed to analyse the nonlinearity
of the magnetic field from a rotating superconducting shell, taking into
account the effect of the London penetration depth.