title: Universality behind Basquin's law of fatigue

abstract:
  One of the most important scaling laws of time dependent fracture is
Basquin's law of fatigue, namely, that the lifetime of the system increases as
a power law with decreasing external load amplitude, $t_f\sim
\sigma_0^{-\alpha}$, where the exponent $\alpha$ has a strong material
dependence. We show that in spite of the broad scatter of the Basquin exponent
$\alpha$, the fatigue fracture of heterogeneous materials exhibits intriguing
universal features. Based on stochastic fracture models we propose a generic
scaling form for the macroscopic deformation and show that at the fatigue limit
the system undergoes a continuous phase transition when changing the external
load. On the microlevel, the fatigue fracture proceeds in bursts characterized
by universal power law distributions. We demonstrate that in a range of
systems, including deformation of asphalt, a realistic model of deformation,
and a fiber bundle model, the system dependent details are contained in
Basquin's exponent for time to failure, and once this is taken into account,
remaining features of failure are universal.


title: The Age of Cluster Galaxies from Continuum Colors

abstract:
  We determine the age of 1,104 early-type galaxies in eight rich clusters ($z
= 0.0046$ to $0.175$) using a new continuum color technique. We find that
galaxies in clusters divide into two populations, an old population with a mean
age similar to the age of the Universe (12 Gyrs) and a younger population with
a mean age of 9 Gyrs. The older population follows the expected relations for
mass and metallicity that imply a classic monolithic collapse origin. Although
total galaxy metallicity is correlated with galaxy mass, it is uncorrelated
with age. It is impossible, with the current data, to distinguish between a
later epoch of star formation, longer duration of star formation or late bursts
of star formation to explain the difference between the old and young
populations. However, the global properties of this younger population are
correlated with cluster environmental factors, which implies secondary
processes, post-formation epoch, operate on the internal stellar population of
a significant fraction of cluster galaxies. In addition, the mean age of the
oldest galaxies in a cluster are correlated with cluster velocity dispersion
implying that galaxy formation in massive clusters begins at earlier epochs
than less massive clusters.


title:
Measuring Smuon-Selectron Mass Splitting at the LHC and Patterns of
  Supersymmetry Breaking

abstract:
  With sufficient data, Large Hadron Collider (LHC) experiments can constrain
the selectron-smuon mass splitting through differences in the di-electron and
di-muon edges from supersymmetry (SUSY) cascade decays. We study the
sensitivity of the LHC to this mass splitting, which within mSUGRA may be
constrained down to O(10^{-4}) for 30 fb^{-1} of integrated luminosity. Over
substantial regions of SUSY breaking parameter space the fractional edge
splitting can be significantly enhanced over the fractional mass splitting.
Within models where the selectron and smuon are constrained to be universal at
a high scale, edge splittings up to a few percent may be induced by
renormalisation group effects and may be significantly discriminated from zero.
The edge splitting provides important information about high-scale SUSY
breaking terms and should be included in any fit of LHC data to high-scale
models.


title: Emission and power of blazar jets

abstract:
  Through the modelling of the Spectral Energy Distribution of blazars we can
infer the physical parameters required to originate the flux we see. Then we
can estimate the power of blazar jets in the form of matter and fields. These
estimates are rather robust for all classes of blazars, although they are in
part dependent of the chosen model (i.e. leptonic rather than adronic). The
indication is that, in almost all cases, the carried Poynting flux is not
dominant, while protons should carry most of the power. In emission line
blazars the jet has a comparable, and often larger, power than the luminosity
of the accretion disk. This is even more true for line-less BL Lacs. If the jet
is structured at the sub-pc scale, with a fast spine surrounded by a slower
layer, then one component sees the radiation of the other boosted, and this
interplay enhances the Inverse Compton flux of both. Since the layer emission
is less beamed, it can be seen also at large viewing angles, making
radio-galaxies very interesting GLAST candidates. Such structures need not be
stable components, and can form and disappear rapidly. Ultrafast TeV
variability is challenging all existing models, suggesting that at least parts
of the jets are moving with large bulk Lorentz factors and at extremely small
viewing angles. However, these fast "bullets" are not necessarily challenging
our main ideas about the energetics and the composition of the bulk of the jet.


title: Magnetic properties of the extended periodic Anderson model

abstract:
  We study magnetic properties of the extended periodic Anderson model, which
includes electron correlations within and between itinerant and localized
bands. By combining dynamical mean-field theory with the numerical
renormalization group we calculate the sublattice magnetization and the
staggered susceptibility to determine the phase diagram in the particle-hole
symmetric case. We find that two kinds of magnetically ordered states compete
with the Kondo insulating state at zero temperature, which induces
non-monotonic behavior in the temperature-dependent magnetization. It is
furthermore clarified that a novel magnetic metallic state is stabilized at
half filling by the competition between Hund's coupling and the hybridization.


title:
Merkle's Key Agreement Protocol is Optimal: An $O(n^2)$ Attack on any
  Key Agreement from Random Oracles

abstract:
  We prove that every key agreement protocol in the random oracle model in
which the honest users make at most $n$ queries to the oracle can be broken by
an adversary who makes $O(n^2)$ queries to the oracle. This improves on the
previous $\widetilde{\Omega}(n^6)$ query attack given by Impagliazzo and Rudich
(STOC '89) and resolves an open question posed by them.
  Our bound is optimal up to a constant factor since Merkle proposed a key
agreement protocol in 1974 that can be easily implemented with $n$ queries to a
random oracle and cannot be broken by any adversary who asks $o(n^2)$ queries.


title: A holographic charged preon model

abstract:
  The Standard Model (SM) is a successful approach to particle physics
calculations. However, there are indications that the SM is only a good
approximation to an underlying non-local reality involving fundamental entities
(preons) that are not point particles. Furthermore, our universe seems to be
dominated by a vacuum energy/cosmological constant. The holographic principle
then indicates only a finite number of bits of information will ever be
available to describe the observable universe, and that requires a holographic
preon model linking the (0,1) holographic bits to SM particles. All SM
particles have charges 0, 1/3, 2/3 or 1 in units of the electron charge, so the
bits in a holographic preon model must be identified with fractional electric
charge. Such holographic charged preon models require baryon asymmetry and also
suggest a mechanism for stationary action. This paper outlines a holographic
charged preon model where preons are strands with finite energy density
specified by bits of information identifying the charge on each end. In the
model, SM particles consist of three strands with spin states corresponding to
wrapped states of the strands. SM particles in this wrapped preon model can be
approximated by preon bound states in non-local dynamics based on three-preon
Bethe-Salpeter equations with instantaneous three-preon interactions. The model
can be falsified by data from the Large Hadron Collider because it generates
baryon asymmetry without axions, and does not allow more than three generations
of SM fermions.


title: Quantum Wrapped Giant Magnon

abstract:
  Understanding the finite-size corrections to the fundamental excitations of a
theory is the first step towards completely solving for the spectrum in finite
volume. We compute the leading exponential correction to the quantum energy of
the fundamental excitation of the light-cone gauged string in AdS(5) x S(5),
which is the giant magnon solution. We present two independent ways to obtain
this correction: the first approach makes use of the algebraic curve
description of the giant magnon. The second relies on the purely
field-theoretical Luscher formulas, which depend on the world-sheet S-matrix.
We demonstrate the agreement to all orders in g/Delta of these approaches,
which in particular presents a further test of the S-matrix. We comment on
generalizations of this method of computation to other string configurations.


title:
Cellular automata for the spreading of technologies in socio-economic
  systems

abstract:
  We introduce an agent-based model for the spreading of technological
developments in socio-economic systems where the technology is mainly used for
the collaboration/interaction of agents. Agents use products of different
technologies to collaborate with each other which induce costs proportional to
the difference of technological levels. Additional costs arise when
technologies of different providers are used. Agents can adopt technologies and
providers of their interacting partners in order to reduce their costs leading
to microscopic rearrangements of the system. Analytical calculations and
computer simulations revealed that starting from a random configuration of
different technological levels a complex time evolution emerges where the
spreading of advanced technologies and the overall technological progress of
the system are determined by the amount of advantages more advanced
technologies provide, and by the structure of the social environment of agents.
We show that agents tend to form clusters of identical technological level with
a power law size distribution. When technological progress arises, the
spreading of technologies in the system can be described by extreme order
statistics.


title: Variational Functionals for Excited States

abstract:
  Functionals that have local minima at the excited states of a non degenerate
Hamiltonian are presented. Then, improved mutually orthogonal approximants of
the ground and the first excited state are reported.


title:
A Study of Structure Formation and Reheating in the D3/D7 Brane
  Inflation Model

abstract:
  We study the spectrum of cosmological fluctuations in the D3/D7 brane
inflationary universe with particular attention to the parametric excitation of
entropy modes during the reheating stage. The same tachyonic instability which
renders reheating in this model very rapid leads to an exponential growth of
entropy fluctuations during the preheating stage which in turn may induce a
large contribution to the large-scale curvature fluctuations. We take into
account the effects of long wavelength quantum fluctuations in the matter
fields. As part of this work, we perform an analytical analysis of the
reheating process. We find that the initial stage of preheating proceeds by the
tachyonic instability channel. An upper bound on the time it takes for the
energy initially stored in the inflaton field to convert into fluctuations is
obtained by neglecting the local fluctuations produced during the period of
tachyonic decay and analyzing the decay of the residual homogeneous field
oscillations, which proceeds by parametric resonance. We show that in spite of
the fact that the resonance is of narrow-band type, it is sufficiently
efficient to rapidly convert most of the energy of the background fields into
matter fluctuations.


title:
Faster exact Markovian probability functions for motif occurrences: a
  DFA-only approach

abstract:
  Background: The computation of the statistical properties of motif
occurrences has an obviously relevant practical application: for example,
patterns that are significantly over- or under-represented in the genome are
interesting candidates for biological roles. However, the problem is
computationally hard; as a result, virtually all the existing pipelines use
fast but approximate scoring functions, in spite of the fact that they have
been shown to systematically produce incorrect results. A few interesting exact
approaches are known, but they are very slow and hence not practical in the
case of realistic sequences. Results: We give an exact solution, solely based
on deterministic finite-state automata (DFAs), to the problem of finding not
only the p-value, but the whole relevant part of the Markovian probability
distribution function of a motif in a biological sequence. In particular, the
time complexity of the algorithm in the most interesting regimes is far better
than that of Nuel (2006), which was the fastest similar exact algorithm known
to date; in many cases, even approximate methods are outperformed. Conclusions:
DFAs are a standard tool of computer science for the study of patterns, but so
far they have been sparingly used in the study of biological motifs. Previous
works do propose algorithms involving automata, but there they are used
respectively as a first step to build a Finite Markov Chain Imbedding (FMCI),
or to write a generating function: whereas we only rely on the concept of DFA
to perform the calculations. This innovative approach can realistically be used
for exact statistical studies of very long genomes and protein sequences, as we
illustrate with some examples on the scale of the human genome.


title: Anisotropic Dark Energy: Dynamics of Background and Perturbations

abstract:
  We investigate cosmologies where the accelerated expansion of the Universe is
driven by a field with an anisotropic equation of state. We model such
scenarios within the Bianchi I framework, introducing two skewness parameters
to quantify the deviation of pressure from isotropy. We study the dynamics of
the background expansion in these models. A special case of anisotropic
cosmological constant is analyzed in detail. The anisotropic expansion is then
confronted with the redshift and angular distribution of the supernovae type
Ia. In addition, we investigate the effects on the cosmic microwave background
(CMB) anisotropies for which the main signature appears to be a quadrupole
contribution. We find that the two skewness parameters can be very well
constrained. Tightest bounds are imposed by the CMB quadrupole, but there are
anisotropic models which avoid this bound completely. Within these bounds, the
anisotropy can be beneficial as a potential explanation of various anomalous
cosmological observations, especially in the CMB at the largest angles. We also
consider the dynamics of linear perturbations in these models. The covariant
approach is used to derive the general evolution equations for cosmological
perturbations taking into account imperfect sources in an anisotropic
background. The implications for the galaxy formation are then studied. These
results might help to make contact between the observed anomalies in CMB and
large scale structure and fundamental theories exhibiting Lorentz violation.


title: Link concordance and generalized doubling operators

abstract:
  We introduce a technique for showing classical knots and links are not slice.
As one application we show that the iterated Bing doubles of many algebraically
slice knots are not topologically slice. Some of the proofs do not use the
existence of the Cheeger-Gromov bound, a deep analytical tool used by
Cochran-Teichner. We define generalized doubling operators, of which Bing
doubling is an instance, and prove our nontriviality results in this more
general context. Our main examples are boundary links that cannot be detected
in the algebraic boundary link concordance group.


title:
Regulation and the Integrity of Spreadsheets in the Information Supply
  Chain

abstract:
  Spreadsheets provide many of the key links between information systems,
closing the gap between business needs and the capability of central systems.
Recent regulations have brought these vulnerable parts of information supply
chains into focus. The risk they present to the organisation depends on the
role that they fulfil, with generic differences between their use as modeling
tools and as operational applications. Four sections of the Sarbanes-Oxley Act
(SOX) are particularly relevant to the use of spreadsheets. Compliance with
each of these sections is dependent on maintaining the integrity of those
spreadsheets acting as operational applications. This can be achieved manually
but at high cost. There are a range of commercially available off-the-shelf
solutions that can reduce this cost. These may be divided into those that
assist in the debugging of logic and more recently the arrival of solutions
that monitor the change and user activity taking place in business-critical
spreadsheets. ClusterSeven provides one of these monitoring solutions,
highlighting areas of operational risk whilst also establishing a database of
information to deliver new business intelligence.


title: The young star cluster system of the Antennae galaxies

abstract:
  The study of young star cluster (YSC) systems, preferentially in starburst
and merging galaxies, has seen great interest in the recent past, as it
provides important input to models of star formation. However, even some basic
properties (like the luminosity function [LF]) of YSC systems are still under
debate. Here we study the photometric properties of the YSC system in the
nearest major merger system, the Antennae galaxies. We find evidence for the
existence of a statistically significant turnover in the LF.


title: Lower Bounds on Signatures from Symmetric Primitives

abstract:
  We show that every construction of one-time signature schemes from a random
oracle achieves black-box security at most $2^{(1+o(1))q}$, where $q$ is the
total number of oracle queries asked by the key generation, signing, and
verification algorithms. That is, any such scheme can be broken with
probability close to $1$ by a (computationally unbounded) adversary making
$2^{(1+o(1))q}$ queries to the oracle. This is tight up to a constant factor in
the number of queries, since a simple modification of Lamport's one-time
signatures (Lamport '79) achieves $2^{(0.812-o(1))q}$ black-box security using
$q$ queries to the oracle.
  Our result extends (with a loss of a constant factor in the number of
queries) also to the random permutation and ideal-cipher oracles. Since the
symmetric primitives (e.g. block ciphers, hash functions, and message
authentication codes) can be constructed by a constant number of queries to the
mentioned oracles, as corollary we get lower bounds on the efficiency of
signature schemes from symmetric primitives when the construction is black-box.
This can be taken as evidence of an inherent efficiency gap between signature
schemes and symmetric primitives.


title: Single-copy entanglement in a gapped quantum spin chain

abstract:
  The single-copy entanglement of a given many-body system is defined [J.
Eisert and M. Cramer, Phys. Rev. A. 72, 042112 (2005)] as the maximal
entanglement deterministically distillable from a bipartition of a single
specimen of that system. For critical (gapless) spin chains, it was recently
shown that this is exactly half the von Neumann entropy [R. Orus, J. I.
Latorre, J. Eisert, and M. Cramer, Phys. Rev. A 73, 060303(R) (2006)], itself
defined as the entanglement distillable in the asymptotic limit: i.e. given an
infinite number of copies of the system. It is an open question as to what the
equivalent behaviour for gapped systems is. In this paper, I show that for the
paradigmatic spin-S Affleck-Kennedy-Lieb-Tasaki chain (the archetypal gapped
chain), the single-copy entanglement is equal to the von Neumann entropy: i.e.
all the entanglement present may be distilled from a single specimen.


title:
Molecular hydrogen in high-redshift Damped Lyman-alpha systems: The
  VLT/UVES database

abstract:
  We present the current status of ongoing searches for molecular hydrogen in
high-redshift (1.8 < zabs <= 4.2) Damped Lyman-alpha systems (DLAs)
capitalising on observations performed with the ESO Very Large Telescope (VLT)
Ultraviolet and Visual Echelle Spectrograph (UVES). We identify 77 DLAs/strong
sub-DLAs, with log N(HI) >= 20 and z_abs > 1.8, which have data that include
redshifted H2 Lyman and/or Werner-band absorption lines. This sample of HI, H2
and metal line measurements, performed in an homogeneous manner, is more than
twice as large as our previous sample (Ledoux et al. 2003) and considers every
system in which searches for H2 could be completed so far, including all
non-detections. H2 is detected in thirteen of the systems with molecular
fractions of values between f=5x10^-7 and f=0.1, where f=2N(H2)/(2N(H2)+N(HI)).
Upper limits are measured for the remaining 64 systems with detection limits of
typically log N(H2)=14.3, corresponding to log f<-5. We find that about 35% of
the DLAs with metallicities relative to solar [X/H]>=-1.3 (i.e., 1/20th solar),
with X = Zn, S or Si, have molecular fractions log f>-4.5, while H2 is detected
-- regardless of the molecular fraction -- in 50% of them. In contrast, only
about 4% of the [X/H]<-1.3 DLAs have log f>-4.5. We show that the presence of
H2 does not strongly depend on the total neutral hydrogen column density,
although the probability of finding log f>-4.5 is higher for log N(HI)>=20.8
than below this limit (19% and 7% respectively). The overall H2 detection rate
in log N(HI)>=20 DLAs is found to be about 16% (10% considering only log f>-4.5
detections) after correction for a slight bias towards large N(HI). [truncated]


title:
Observer dependence of the quasi-local energy and momentum in
  Schwarzschild space-time

abstract:
  The observer dependence of the quasi-local energy (QLE) and momentum in the
Schwarzschild geometry is illustrated. Using the Brown-York prescription, the
QLE for families of non-geodesic and geodesic observers penetrating the event
horizon is obtained. An explicit shell-building process is presented and the
binding energy is computed in terms of the QLE measured by a static observer
field at a radius outside the horizon radius. The QLE for a radially geodesic
observer field freely-falling from infinity is shown to vanish. Finally, a
simple relation for the dynamics of the quasi-local momentum density for a
geodesic observer field is noted.


title:
Disks, young stars, and radio waves: the quest for forming planetary
  systems

abstract:
  Kant and Laplace suggested the Solar System formed from a rotating gaseous
disk in the 18th century, but convincing evidence that young stars are indeed
surrounded by such disks was not presented for another 200 years. As we move
into the 21st century the emphasis is now on disk formation, the role of disks
in star formation, and on how planets form in those disks. Radio wavelengths
play a key role in these studies, currently providing some of the highest
spatial resolution images of disks, along with evidence of the growth of dust
grains into planetesimals. The future capabilities of EVLA and ALMA provide
extremely exciting prospects for resolving disk structure and kinematics,
studying disk chemistry, directly detecting proto-planets, and imaging disks in
formation.


title:
Inverse approach to atomistic modeling: Applications to a-Si:H and
  g-GeSe2

abstract:
  We discuss an inverse approach for atomistic modeling of glassy materials.
The focus is on structural modeling and electronic properties of hydrogenated
amorphous silicon and glassy GeSe2 alloy. The work is based upon a new approach
"experimentally constrained molecular relaxation (ECMR)". Unlike conventional
approaches (such as molecular dynamics (MD) and Monte Carlo simulations(MC),
where a potential function is specified and the system evolves either
deterministically (MD) or stochastically (MC), we develop a novel scheme to
model structural configurations using experimental data in association with
density functional calculations. We have applied this approach to model
hydrogenated amorphous silicon and glassy GeSe2. The electronic and structural
properties of these models are compared with experimental data and models
obtained from conventional molecular dynamics simulation.


title: A Natural Supersymmetric Model with MeV Dark Matter

abstract:
  It has previously been proposed that annihilating dark matter particles with
MeV-scale masses could be responsible for the flux of 511 keV photons observed
from the region of the Galactic Bulge. The conventional wisdom, however, is
that it is very challenging to construct a viable particle physics model
containing MeV dark matter. In this letter, we challenge this conclusion by
describing a simple and natural supersymmetric model in which the lightest
supersymmetric particle naturally has a MeV-scale mass and the other
phenomenological properties required to generate the 511 keV emission. In
particular, the small ($\sim$ $10^{-5}$) effective couplings between dark
matter and the Standard Model fermions required in this scenario naturally lead
to radiative corrections that generate MeV-scale masses for both the dark
matter candidate and the mediator particle.


title:
Short Distance Operator Product Expansion of the 1D, N = 4 Extended GR
  Super Virasoro Algebra by Use of Coadjoint Representations

abstract:
  Using the previous construction of the geometrical representation (GR) of the
centerless 1D, N = 4 extended Super Virasoro algebra, we construct the
corresponding Short Distance Operation Product Expansions for the deformed
version of the algebra. This algebra differs from the regular algebra by the
addition of terms containing the Levi-Civita tensor. How this addition changes
the super-commutation relations and affects the Short Distance Operation
Product Expansions (OPEs) of the associated fields is investigated. The Method
of Coadjoint Orbits, which removes the need first to find Lagrangians invariant
under the action of the symmetries, is used to calculate the expansions.
Finally, an alternative method involving Clifford algebras is investigated for
comparison.


title: One-Dimensional Bose Gases with N-Body Attractive Interactions

abstract:
  We study the ground state properties of a one-dimensional Bose gas with
N-body attractive contact interactions. By using the explicit form of the
bright soliton solution of a generalized nonlinear Schroedinger equation, we
compute the chemical potential and the ground state energy. For N=3, a
localized soliton wave-function exists only for a critical value of the
interaction strength: in this case the ground state has an infinite degeneracy
that can be parameterized by the chemical potential. The stabilization of the
bright soliton solution by an external harmonic trap is also discussed, and a
comparison with the effect of N-body attractive contact interactions in higher
dimensions is presented.


title: The smallest multistationary mass-preserving chemical reaction network

abstract:
  Biochemical models that exhibit bistability are of interest to biologists and
mathematicians alike. Chemical reaction network theory can provide sufficient
conditions for the existence of bistability, and on the other hand can rule out
the possibility of multiple steady states. Understanding small networks is
important because the existence of multiple steady states in a subnetwork of a
biochemical model can sometimes be lifted to establish multistationarity in the
larger network. This paper establishes the smallest reversible, mass-preserving
network that admits bistability and determines the semi-algebraic set of
parameters for which more than one steady state exists.


title: Ensuring Spreadsheet Integrity with Model Master

abstract:
  We have developed the Model Master (MM) language for describing spreadsheets,
and tools for converting MM programs to and from spreadsheets. The MM
decompiler translates a spreadsheet into an MM program which gives a concise
summary of its calculations, layout, and styling. This is valuable when trying
to understand spreadsheets one has not seen before, and when checking for
errors. The MM compiler goes the other way, translating an MM program into a
spreadsheet. This makes possible a new style of development, in which
spreadsheets are generated from textual specifications. This can reduce error
rates compared to working directly with the raw spreadsheet, and gives
important facilities for code reuse. MM programs also offer advantages over
Excel files for the interchange of spreadsheets.


title: Asymptotics of degenerating Eisenstein series

abstract:
  We give some estimates for the asymptotic orders of degenerating Eisenstein
series for some families of degenerating punctured Riemann surfaces, which is
motivated by the question identifying $L_{2}$-cohomology of the
Takhtajan-Zograf metric that is originally asked by To and Weng.


title: The two dimensional distribution of values of $\zeta(1+it)$

abstract:
  We prove several results on the distribution function of $\zeta(1+it)$ in the
complex plane, that is the joint distribution function of $\arg\zeta(1+it)$ and
$|\zeta(1+it)|$. Similar results are also given for $L(1,\chi)$ (as $\chi$
varies over non-principal characters modulo a large prime $q$).


title: Aspects of Z'-mediated Supersymmetry Breaking

abstract:
  In a recent paper, we proposed the possibility that supersymmetry breaking is
communicated dominantly via a U(1)' vector multiplet. We also required that the
U(1)' plays a crucial role in solving the mu problem. We discuss here in detail
both the construction and the phenomenology of one class of such models. The
low energy spectrum generically contains heavy sfermions, Higgsinos and exotics
~10-100 TeV; an intermediate M_Z' ~ 3-30 TeV; light gauginos ~100-1000 GeV, of
which the lightest can be wino-like; a light Higgs with a mass of ~140 GeV; and
a singlino which can be very light. We present a set of possible consistent
charge choices. Several benchmark models are used to demonstrate characteristic
phenomenological features. Special attention is devoted to interesting LHC
signatures such as gluino decay and the decay patterns of the electroweak-inos.
Implications for neutrino masses, exotic decays, R-parity, gauge unification,
and the gravitino mass are briefly discussed.


title: How to make a bilayer exciton condensate flow

abstract:
  Bose condensation is responsible for many of the most spectacular effects in
physics because it can promote quantum behavior from the microscopic to the
macroscopic world. Bose condensates can be distinguished by the condensing
object; electron-electron Cooper-pairs are responsible for superconductivity,
Helium atoms for superfluidity, and ultracold alkali atoms in vapors for
coherent matter waves. Electron-hole pair (exciton) condensation has maintained
special interest because it has been difficult to realize experimentally, and
because exciton phase coherence is never perfectly spontaneous. Although ideal
condensates can support an exciton supercurrent, it has not been clear how such
a current could be induced or detected, or how its experimental manifestation
would be altered by the phase-fixing exciton creation and annhilation processes
which are inevitably present. In this article we explain how to induce an
exciton supercurrent in separately contacted bilayer condensates, and predict
electrical effects which enable unambiguous detection.


title:
Stochastic Depletion Problems: Effective Myopic Policies for a class of
  Dynamic Optimization Problems

abstract:
  This paper presents a general class of dynamic stochastic optimization
problems we refer to as Stochastic Depletion Problems. A number of challenging
dynamic optimization problems of practical interest are stochastic depletion
problems. Optimal solutions for such problems are difficult to obtain, both
from a pragmatic computational perspective as also from a theoretical
perspective. As such, simple heuristics are highly desirable. We isolate two
simple properties that, if satisfied by a problem within this class, guarantee
that a myopic policy incurs a performance loss of at most 50 % relative to the
optimal adaptive control policy for that problem. We are able to verify that
these two properties are satisfied for several interesting families of
stochastic depletion problems and as a consequence identify efficient
near-optimal control policies for a number of interesting dynamic stochastic
optimization problems.


title: Hyperbolic Graphs of Surface Groups

abstract:
  We give a sufficient condition under which the fundamental group of a reglued
graph of surfaces is hyperbolic. A reglued graph of surfaces is constructed by
cutting a fixed graph of surfaces along the edge surfaces, then regluing by
pseudo-Anosov homeomorphisms of the edge surfaces. By carefully choosing the
regluing homeomorphism, we construct an example of such a reglued graph of
surfaces, whose fundamental group is not abstractly commensurate to any
surface-by-free group, i.e., which is different from all the examples given in
Mosher's paper 'A hyperbolic-by-hyperbolic hyperbolic group'.


title: The mathematics of Septoku

abstract:
  Septoku is a Sudoku variant invented by Bruce Oberg, played on a hexagonal
grid of 37 cells. We show that up to rotations, reflections, and symbol
permutations, there are only six valid Septoku boards. In order to have a
unique solution, we show that the minimum number of given values is six. We
generalize the puzzle to other board shapes, and devise a puzzle on a
star-shaped board with 73 cells with six givens which has a unique solution. We
show how this puzzle relates to the unsolved Hadwiger-Nelson problem in
combinatorial geometry.


title: The Destruction of Cosmological Minihalos by Primordial Supernovae

abstract:
  We present numerical simulations of primordial supernovae in cosmological
minihalos at $z \sim$ 20. We consider Type II supernovae, hypernovae, and pair
instability supernovae (PISN) in halos from 6.9 $\times$ 10$^5$ - 1.2 $\times$
10$^7$ $\Ms$, those in which Population III stars are expected to form via
H$_2$ cooling. The supernovae evolve along two evolutionary paths according to
whether they explode in \ion{H}{2} regions or neutral halos. Those in
\ion{H}{2} regions first expand adiabatically and then radiate strongly upon
collision with baryons ejected from the halo during its photoevaporation by the
progenitor. Explosions in neutral halos promptly emit most of their kinetic
energy as x-rays, but retain enough momentum to seriously disrupt the halo. We
find that the least energetic of the supernovae are capable of destroying halos
$\lesssim$ 10$^7$ $\Ms$, while a single PISN can destroy even more massive
halos. Blasts in \ion{H}{2} regions disperse heavy elements into the IGM, but
neutral halos confine the explosion and its metals. In \ion{H}{2} regions, a
prompt second generation of stars may form in the remnant at radii of 100 - 200
pc in the halo. Explosions confined by large halos instead recollapse, with
infall rates in excess of 10$^{-2}$ $\Ms$ yr$^{-1}$ that heavily contaminate
their interior. This fallback may either fuel massive black hole growth at very
high redshifts or create the first globular cluster with a radius of 10 - 20 pc
at the center of the halo. Our findings allow the possibility that the first
primitive galaxies formed sooner, with greater numbers of stars and distinct
chemical abundance patterns, than in current models.


title:
Critical Networks Exhibit Maximal Information Diversity in
  Structure-Dynamics Relationships

abstract:
  Network structure strongly constrains the range of dynamic behaviors
available to a complex system. These system dynamics can be classified based on
their response to perturbations over time into two distinct regimes, ordered or
chaotic, separated by a critical phase transition. Numerous studies have shown
that the most complex dynamics arise near the critical regime. Here we use an
information theoretic approach to study structure-dynamics relationships within
a unified framework and how that these relationships are most diverse in the
critical regime.


title: On the derivation of an effective Higgs field

abstract:
  In one respect, the massive vector-boson shows its difference from a massless
vector-boson by one more physical polarization, known as longitudinal
polarization. In another respect, the quantized boson acquires its mass by
Higgs mechanism. In this paper we study the effect of the longitudinal
polarization in U(1) case by substituting it into the primary Yang-Mills
Lagrangian $-\frac 14F_{\mu \nu}F^{\mu \nu}$. Under a hypothesis of strong
transversal condition for free vector boson, it is found that in the Lagrangian
the scalar field for the Higgs mechanism can automatically arise after we
separate a part equivalent to the contribution of a massless boson. In
addition, a criterion is obtained to infer whether the boson is massive or not:
if $\mathbf{E}^2-\mathbf{B}^2\neq 0$, where $\mathbf{E}$ and $\mathbf{B}$ are
field strengths, then it is massive. The analysis also pertains to SU(2) case.
The method in this paper is performed before any quantizations.


title: Entropy Current in Conformal Hydrodynamics

abstract:
  In recent work (arXiv:0712.2456, arXiv:0712.2451) the energy-momentum tensor
for the N=4 SYM fluid was computed up to second derivative terms using
holographic methods. The aim of this note is to propose an entropy current
(accurate up to second derivative terms) consistent with this energy-momentum
tensor and to explicate its relation with the existing theories of relativistic
hydrodynamics. In order to achieve this, we first develop a Weyl-covariant
formalism which simplifies the study of conformal hydrodynamics. This naturally
leads us to a proposal for the entropy current of an arbitrary conformal fluid
in any spacetime (with d>3). In particular, this proposal translates into a
definite expression for the entropy flux in the case of N=4 SYM fluid. We
conclude this note by comparing the formalism presented here with the
conventional Israel-Stewart formalism.


title:
Joint source and channel coding for MIMO systems: Is it better to be
  robust or quick?

abstract:
  We develop a framework to optimize the tradeoff between diversity,
multiplexing, and delay in MIMO systems to minimize end-to-end distortion. We
first focus on the diversity-multiplexing tradeoff in MIMO systems, and develop
analytical results to minimize distortion of a vector quantizer concatenated
with a space-time MIMO channel code. In the high SNR regime we obtain a
closed-form expression for the end-to-end distortion as a function of the
optimal point on the diversity-multiplexing tradeoff curve. For large but
finite SNR we find this optimal point via convex optimization. We then consider
MIMO systems using ARQ retransmission to provide additional diversity at the
expense of delay. For sources without a delay constraint, distortion is
minimized by maximizing the ARQ window size. This results in an ARQ-enhanced
multiplexing-diversity tradeoff region, with distortion minimized over this
region in the same manner as without ARQ. Under a source delay constraint the
problem formulation changes to account for delay distortion associated with
random message arrival and random ARQ completion times. We use a dynamic
programming formulation to capture the channel diversity-multiplexing tradeoff
at finite SNR as well as the random arrival and retransmission dynamics; we
solve for the optimal multiplexing-diversity-delay tradeoff to minimize
end-to-end distortion associated with the source encoder, channel, and ARQ
retransmissions. Our results show that a delay-sensitive system should adapt
its operating point on the diversity-multiplexing-delay tradeoff region to the
system dynamics. We provide numerical results that demonstrate significant
performance gains of this adaptive policy over a static allocation of
diversity/multiplexing in the channel code and a static ARQ window size.


title: On minimality of convolutional ring encoders

abstract:
  Convolutional codes are considered with code sequences modelled as
semi-infinite Laurent series. It is wellknown that a convolutional code C over
a finite group G has a minimal trellis representation that can be derived from
code sequences. It is also wellknown that, for the case that G is a finite
field, any polynomial encoder of C can be algebraically manipulated to yield a
minimal polynomial encoder whose controller canonical realization is a minimal
trellis. In this paper we seek to extend this result to the finite ring case G
= Z_{p^r} by introducing a socalled "p-encoder". We show how to manipulate a
polynomial encoding of a noncatastrophic convolutional code over Z_{p^r} to
produce a particular type of p-encoder ("minimal p-encoder") whose controller
canonical realization is a minimal trellis with nonlinear features. The minimum
number of trellis states is then expressed as p^gamma, where gamma is the sum
of the row degrees of the minimal p-encoder. In particular, we show that any
convolutional code over Z_{p^r} admits a delay-free p-encoder which implies the
novel result that delay-freeness is not a property of the code but of the
encoder, just as in the field case. We conjecture that a similar result holds
with respect to catastrophicity, i.e., any catastrophic convolutional code over
Z_{p^r} admits a noncatastrophic p-encoder.


title: $q$-Chaos

abstract:
  We consider the $L_p$ norm estimates for homogeneous polynomials of
$q$-gaussian variables ($-1\leq q\leq 1$). When $-1<q<1$ the $L_p$ estimates
for $1\leq p \leq 2$ are essentially the same as the free case ($q=0$), whilst
the $L_p$ estimates for $2\leq p \leq \infty$ show a strong $q$-dependence.
Moreover, the extremal cases $q = \pm 1$ produce decisively different formulae.


title:
Gravitational energy from a combination of a tetrad expression and
  Einstein's pseudotensor

abstract:
  The energy-momentum for a gravitating system can be considered by the tetard
teleparalle gauge current in orthonormal frames. Whereas the Einstein
pseudotensor used holonomic frames. Tetrad expression itself gives a better
result for gravitational energy than Einstein's. Inspired by an idea of Deser,
we found a gravitational energy expression which enjoys the positive energy
property by combining the tetrad expression and the Einstein pseudotensor,
i.e., the connection coefficient has a form appropriate to a suitable
intermediate between orthonormal and holonomic frames.


title: Spherical two-distance sets

abstract:
  A set S of unit vectors in n-dimensional Euclidean space is called spherical
two-distance set, if there are two numbers a and b, and inner products of
distinct vectors of S are either a or b. The largest cardinality g(n) of
spherical two-distance sets is not exceed n(n+3)/2. This upper bound is known
to be tight for n=2,6,22. The set of mid-points of the edges of a regular
simplex gives the lower bound L(n)=n(n+1)/2 for g(n.
  In this paper using the so-called polynomial method it is proved that for
nonnegative a+b the largest cardinality of S is not greater than L(n). For the
case a+b<0 we propose upper bounds on |S| which are based on Delsarte's method.
Using this we show that g(n)=L(n) for 6<n<22, 23<n<40, and g(23)=276 or 277.


title: Deformations of nilpotent cones and Springer correspondences

abstract:
  Let G = Sp (2n) be the symplectic group over Z. We present a certain kind of
deformation of the nilpotent cone of G with G-action. This enables us to make
direct links between the Springer correspondence of sp_{2n} over C, that over
characteristic two, and our exotic Springer correspondence. As a by-product, we
obtain a complete description of our exotic Springer correspondence.


title: Topology of polar weighted homogeneous hypersurfaces

abstract:
  Polar weighted homogeneous polynomials are the class of special polynomials
of real variables $x_i,y_i, i=1,..., n$ with $z_i=x_i+\sqrt{-1} y_i$, which
enjoys a "polar action". In many aspects, their behavior looks like that of
complex weighted homogeneous polynomials. We study basic properties of
hypersurfaces which are defined by polar weighted homogeneous polynomials.


title:
Monte Carlo Simulations of Star Clusters - IV. Calibration of the Monte
  Carlo Code and Comparison with Observations for the Open Cluster M67

abstract:
  We outline the steps needed in order to incorporate the evolution of single
and binary stars into a particular Monte Carlo code for the dynamical evolution
of a star cluster. We calibrate the results against N-body simulations, and
present models for the evolution of the old open cluster M67 (which has been
studied thoroughly in the literature with N-body techniques). The calibration
is done by choosing appropriate free code parameters. We describe in particular
the evolution of the binary, white dwarf and blue straggler populations, though
not all channels for blue straggler formation are represented yet in our
simulations. Calibrated Monte Carlo runs show good agreement with results of
N-body simulations not only for global cluster parameters, but also for e.g.
binary fraction, luminosity function and surface brightness. Comparison of
Monte Carlo simulations with observational data for M67 shows that is possible
to get reasonably good agreement between them. Unfortunately, because of the
large statistical fluctuations of the numerical data and uncertainties in the
observational data the inferred conclusions about the cluster initial
conditions are not firm.


title: Picking up the Pieces: Self-Healing in Reconfigurable Networks

abstract:
  We consider the problem of self-healing in networks that are reconfigurable
in the sense that they can change their topology during an attack. Our goal is
to maintain connectivity in these networks, even in the presence of repeated
adversarial node deletion, by carefully adding edges after each attack. We
present a new algorithm, DASH, that provably ensures that: 1) the network stays
connected even if an adversary deletes up to all nodes in the network; and 2)
no node ever increases its degree by more than 2 log n, where n is the number
of nodes initially in the network. DASH is fully distributed; adds new edges
only among neighbors of deleted nodes; and has average latency and bandwidth
costs that are at most logarithmic in n. DASH has these properties irrespective
of the topology of the initial network, and is thus orthogonal and
complementary to traditional topology-based approaches to defending against
attack.
  We also prove lower-bounds showing that DASH is asymptotically optimal in
terms of minimizing maximum degree increase over multiple attacks. Finally, we
present empirical results on power-law graphs that show that DASH performs well
in practice, and that it significantly outperforms naive algorithms in reducing
maximum degree increase. We also present empirical results on performance of
our algorithms and a new heuristic with regard to stretch (increase in shortest
path lengths).


title:
3D-Ultrasound probe calibration for computer-guided diagnosis and
  therapy

abstract:
  With the emergence of swept-volume ultrasound (US) probes, precise and almost
real-time US volume imaging has become available. This offers many new
opportunities for computer guided diagnosis and therapy, 3-D images containing
significantly more information than 2-D slices. However, computer guidance
often requires knowledge about the exact position of US voxels relative to a
tracking reference, which can only be achieved through probe calibration. In
this paper we present a 3-D US probe calibration system based on a membrane
phantom. The calibration matrix is retrieved by detection of a membrane plane
in a dozen of US acquisitions of the phantom. Plane detection is robustly
performed with the 2-D Hough transformation. The feature extraction process is
fully automated, calibration requires about 20 minutes and the calibration
system can be used in a clinical context. The precision of the system was
evaluated to a root mean square (RMS) distance error of 1.15mm and to an RMS
angular error of 0.61 degrees. The point reconstruction accuracy was evaluated
to 0.9mm and the angular reconstruction accuracy to 1.79 degrees.


title:
Empirical shape function of limit-order books in the Chinese stock
  market

abstract:
  We have analyzed the statistical probabilities of limit-order book (LOB)
shape through building the book using the ultra-high-frequency data from 23
liquid stocks traded on the Shenzhen Stock Exchange in 2003. We find that the
averaged LOB shape has a maximum away from the same best price for both buy and
sell LOBs. The LOB shape function has nice exponential form in the right tail.
The buy LOB is found to be abnormally thicker for the price levels close to the
same best although there are much more sell orders on the book. We also find
that the LOB shape functions for both buy and sell sides have periodic peaks
with a period of five. The 1-min averaged volumes at fixed tick level follow
lognormal distributions, except for the left tails which display power-law
behaviors, and exhibit long memory. Academic implications of our empirical
results are also discussed briefly.


title:
Contact identification for assembly-disassembly simulation with a haptic
  device

abstract:
  Assembly/Disassembly (A/D) simulations using haptic devices are facing
difficulties while simulating insertion/extraction operations such as removing
cylinders from holes. In order to address this configuration as well as others,
an approach based on contact identification between components is presented in
this paper. This approach can efficiently contribute either to a new A/D
simulation preparation process relying on two types of shape representations
(mesh and CAD NURBS models), or directly to the real time simulation process
when it is performed with 6D haptic devices. The model processing pipeline is
described and illustrated to show how information can be propagated and used
for contact detection. Then, the contact identification process is introduced
and illustrated through an example


title: 5-cycles and the Petersen graph

abstract:
  We show that if G is a connected bridgeless cubic graph whose every 2-factor
is comprised of cycles of length five then G is the Petersen graph.


title: Modular Compilation of a Synchronous Language

abstract:
  Synchronous languages rely on formal methods to ease the development of
applications in an efficient and reusable way. Formal methods have been
advocated as a means of increasing the reliability of systems, especially those
which are safety or business critical. It is still difficult to develop
automatic specification and verification tools due to limitations like state
explosion, undecidability, etc... In this work, we design a new specification
model based on a reactive synchronous approach. Then, we benefit from a formal
framework well suited to perform compilation and formal validation of systems.
In practice, we design and implement a special purpose language (LE) and its
two semantics: the ehavioral semantics helps us to define a program by the set
of its behaviors and avoid ambiguousness in programs' interpretation; the
execution equational semantics allows the modular compilation of programs into
software and hardware targets (c code, vhdl code, fpga synthesis, observers).
Our approach is pertinent considering the two main requirements of critical
realistic applications: the modular compilation allows us to deal with large
systems, the model-based approach provides us with formal validation.


title: Anatomy of Top-Mode Extended Technicolor Model

abstract:
  We analyze two versions of the extended technicolor (ETC) incorporating the
top quark condensate via the flavor-universal coloron type topcolor $SU(3)_1
\times SU(3)_2$: A straightforward top-mode ETC having quarks and techniquarks
assigned to a single (strong) $SU(3)_1$, and a ``twisted model'' with
techniquarks carrying the weak $SU(3)_2$ while quarks the strong $SU(3)_1$. The
straightforward model has the same ETC structure as that of Appelquist et al.
without topcolor which we first analyze to find that it yields only too small
ETC-induced mass for the third generation. In contrast, our model having
topcolor takes the form of a version of the topcolor-assisted technicolor (TC2)
after ETC breakings, which triggers the top quark condensate giving rise to a
realistic top mass. However, techniquarks have the strong topcolor $SU(3)_1$ in
addition to the already strong walking/conformal technicolor, which triggers
the techniquark condensate at scale much higher than the weak scale, a
disaster. We then consider a ``twisted model'' of TC2, though not an explicit
ETC. We find a new feature that ``ETC''-induced quark mass is enhanced to the
realistic value by the large anomalous dimension $\gamma_m \simeq 2$ of
Nambu-Jona-Lasinio-type topcolor interactions. The result roughly reproduces
the realistic quark masses. We further find a novel effect of the above large
anomalous dimension $\gamma_m \simeq 2$: The top-pion mass has a universal
upper bound, $m_{\pi_t} < 70 \GeV$, in the generic TC2 model.


title: Kolmogorov scaling from random force fields

abstract:
  We show that the classical Kolmogorov and Richardson scaling laws in fully
developed turbulence are consistent with a random Gaussian force field.
Numerical simulations of a shell model approximation to the Navier-Stokes
equations suggest that the fluctuations in the force (acceleration) field are
scale independent throughout the inertial regime. We conjecture that Lagrangian
statistics of the relative velocity in a turbulent flow is determined by the
typical force field, whereas the multiscaling is associated to extreme events
in the force field fluctuations.


title:
Construction and Uniqueness for reflected BSDE under linear increasing
  condition

abstract:
  In this paper, we study the uniqueness of the solution of reflected BSDE with
one or two barriers, under continuous and linear increasing condition of
generator $g$. Before that we study the construction of solution of of
reflected BSDE with one or two barriers.


title: Damage process of a fiber bundle with a strain gradient

abstract:
  We study the damage process of fiber bundles in a wedge-shape geometry which
ensures a constant strain gradient. To obtain the wedge geometry we consider
the three-point bending of a bar, which is modelled as two rigid blocks glued
together by a thin elastic interface. The interface is discretized by parallel
fibers with random failure thresholds, which get elongated when the bar is
bent. Analyzing the progressive damage of the system we show that the strain
gradient results in a rich spectrum of novel behavior of fiber bundles. We find
that for weak disorder an interface crack is formed as a continuous region of
failed fibers. Ahead the crack a process zone develops which proved to shrink
with increasing deformation making the crack tip sharper as the crack advances.
For strong disorder, failure of the system occurs as a spatially random
sequence of breakings. Damage of the fiber bundle proceeds in bursts whose size
distribution shows a power law behavior with a crossover from an exponent 2.5
to 2.0 as the disorder is weakened. The size of the largest burst increases as
a power law of the strength of disorder with an exponent 2/3 and saturates for
strongly disordered bundles.


title: Weak Localization of Dirac Fermions in Graphene

abstract:
  In the presence of the charged impurities, we study the weak localization
(WL) effect by evaluating the quantum interference correction (QIC) to the
conductivity of Dirac fermions in graphene. With the inelastic scattering rate
due to electron-electron interactions obtained from our previous work, we
investigate the dependence of QIC on the carrier concentration, the
temperature, the magnetic field and the size of the sample. It is found that WL
is present in large size samples at finite carrier doping. Its strength becomes
weakened/quenched when the sample size is less than a few microns at low
temperatures as studied in the experiments. In the region close to zero doping,
the system may become delocalized. The minimum conductivity at low temperature
for experimental sample sizes is found to be close to the data.


title:
Self-similar solutions and translating solitons for Lagrangian mean
  curvature flow

abstract:
  We construct many self-similar and translating solitons for Lagrangian mean
curvature flow, including self-expanders and translating solitons with
arbitrarily small oscillation on the Lagrangian angle. Our translating solitons
play the same role as cigar solitons in Ricci flow, and are important in
studying the regularity of Lagrangian mean curvature flow.
  Given two transverse Lagrangian planes R^n in C^n with sum of characteristic
angles less than pi, we show there exists a Lagrangian self-expander asymptotic
to this pair of planes. The Maslov class of these self-expanders is zero. Thus
they can serve as local models for surgeries on Lagrangian mean curvature flow.
Families of self-shrinkers and self-expanders with different topologies are
also constructed. This paper generalizes the work of Anciaux, Joyce, Lawlor,
and Lee and Wang.


title:
Establishment of the Coulomb law in the layer phase of a pure U(1)
  lattice gauge theory

abstract:
  In this article we examine the Layer phase of the five dimensional,
anisotropic, Abelian gauge model. Our results are to be compared with the ones
of the 4D U(1) gauge model in an attempt to verify that four dimensional
physics governs the four dimensional layers. The main results are: i) From the
analysis of Wilson loops we verified the $\frac{1}{R}$ behavior, in the layered
phase, for the potential between heavy charges. The renormalized fine structure
constant in the layer phase is found to be equal to that of 4D Coulomb
phase,$\alpha_{layer}$=$\alpha_{4D}$. ii) Based on the helicity modulus
analysis we show that the layers are in the Coulomb phase while the transverse
bulk space is in the confining phase. We also calculated the renormalized
coupling $\beta_{R}$ and found results compatible with those obtained from the
Coulomb potential. Finally we calculated the potential in the 5D Coulomb phase
and found $\frac{1}{R^{2}}$ behavior for the static $q \bar{q}$ potential. From
the study of the helicity modulus we have a possible estimate for the five
dimensional renormalized fine structure constant in the region of the critical
value of the bare gauge coupling.


title: Non-Markovian signatures in the current noise of a charge qubit

abstract:
  We investigate the current noise of a charge qubit coupled to a phonon bath
in different parameter regimes. We find, using the theory of Full Counting
Statistics of non-Markovian systems, that the current fluctuations are strongly
influenced by memory effects generated from the interplay between quantum
coherence and the dynamics of the phonon bath.


title: Outer edges of debris discs: how sharp is sharp?

abstract:
  Ring-like features have been observed in several debris discs. Outside the
main ring, while some systems exhibit smooth surface brightness profiles (SB)
that fall off roughly as r**-3.5, others display large luminosity drops at the
ring's outer edge and steeper radial SB profiles. We seek to understand this
diversity of outer edge profiles under the ``natural'' collisional evolution of
the system, without invoking external agents such as planets or gas. We use a
statistical code to follow the evolution of a collisional population, ranging
from dust grains (submitted to radiation pressure) to planetesimals and
initially confined within a belt (the 'birth ring'). The system typically
evolves toward a "standard" steady state, with no sharp edge and SB \propto
r**-3.5 outside the birth ring. Deviations from this standard profile, in the
form of a sharp outer edge and a steeper fall-off, occur only when two
parameters take their extreme values: 1) When the birth ring is so massive that
it becomes radially optically thick for the smallest grains. However, the
required disc mass is here probably too high to be realistic. 2) When the
dynamical excitation of the dust-producing planetesimals is so low (<e> <0.01)
that the smallest grains, which otherwise dominate the total optical depth, are
preferentially depleted. This low-excitation case, although possibly not
generic, cannot be ruled out by observations. Our "standard" profile provides a
satisfactory explanation for a large group of debris discs with outer edges and
SB falling as r**-3.5. Systems with sharper outer edges, barring other
confining agents, could still be explained by ``natural'' collisional evolution
if their dynamical excitation is very low. We show that such a dynamically-cold
case provides a satisfactory fit for HR4796A


title:
A unifying formulation of the Fokker-Planck-Kolmogorov equation for
  general stochastic hybrid systems

abstract:
  A general formulation of the Fokker-Planck-Kolmogorov (FPK) equation for
stochastic hybrid systems is presented, within the framework of Generalized
Stochastic Hybrid Systems (GSHS). The FPK equation describes the time evolution
of the probability law of the hybrid state. Our derivation is based on the
concept of mean jump intensity, which is related to both the usual stochastic
intensity (in the case of spontaneous jumps) and the notion of probability
current (in the case of forced jumps). This work unifies all previously known
instances of the FPK equation for stochastic hybrid systems, and provides GSHS
practitioners with a tool to derive the correct evolution equation for the
probability law of the state in any given example.


title:
Controlling Kerr nonlinearity with electric fields in asymmetric double
  quantum-dots

abstract:
  The control of Kerr nonlinearity with electric fields in an asymmetric double
quantum-dot systems coupling with tunneling is investigated theoretically. It
is found that,by proper tuning of two light beams and tunneling via a bias
voltage, the Kerr nonlinearity can be enhanced and varied within a wide scale.


title: Plasma treatment advantages for textiles

abstract:
  The textile industry is searching for innovative production techniques to
improve the product quality, as well as society requires new finishing
techniques working in environmental respect. Plasma surface treatments show
distinct advantages, because they are able to modify the surface properties of
inert materials, sometimes with environment friendly devices. For fabrics, cold
plasma treatments require the development of reliable and large systems. Such
systems are now existing and the use of plasma physics in industrial problems
is rapidly increasing. On textile surfaces, three main effects can be obtained
depending on the treatment conditions: the cleaning effect, the increase of
microroughness (anti-pilling finishing of wool) and the production of radicals
to obtain hydrophilic surfaces. Plasma polymerisation, that is the deposition
of solid polymeric materials with desired properties on textile substrates, is
under development. The advantage of such plasma treatments is that the
modification turns out to be restricted in the uppermost layers of the
substrate, thus not affecting the overall desirable bulk properties. Here, we
present the research results on the use of plasma physics in textile properties
modification. Treatments on natural, wool and cotton, and on synthetic polymers
to improve wetting are shown. Hydrophilic-hydrophobic treatments,
dirt-repellent coatings are presented. Low-pressure and atmospheric-pressure
glow discharge systems are also discussed.


title: Heat Transfer Through Near-Field Interactions in Nanofluids

abstract:
  Using the Landauer-Buttiker theory we calculate the thermal conductance
associated to plasmons modes in one dimensional arrays of nanoparticles closely
spaced in a host fluid. Our numerical simulations show that the near-field
interactions between particles have a negligible effect on the thermal
conductivity of nanoparticles colloidal solutions (nanofluids).


title: Optical monitoring of the z=4.40 quasar Q 2203+292

abstract:
  We report Cousins R-band monitoring of the high-redshift (z=4.40) radio quiet
quasar Q 2203+292 from May 1999 to October 2007. The quasar shows maximum
peak-to-peak light curve amplitude of ~0.3 mag during the time of our
monitoring, and ~0.9 mag when combined with older literature data. The rms of a
fit to the light curve with a constant is 0.08 mag and 0.2 mag, respectively.
The detected changes are at ~3-sigma level. The quasar was in a stable state
during the recent years and it might have undergone a brightening event in the
past. The structure function analysis concluded that the object shows
variability properties similar to those of the lower redshift quasars. We set a
lower limit to the Q 2203+292 broad line region mass of 0.3-0.4 M_odot.
Narrow-band imaging search for redshifted Ly_alpha from other emission line
objects at the same redshift shows no emission line objects in the quasar
vicinity.


title: All-optical switch with two periodically curved nonlinear waveguides

abstract:
  We propose a type of all-optical switch which consists of two periodically
curved nonlinear optical waveguides placed in parallel. Compared to the
all-optical switch based on the traditional nonlinear directional coupler with
straight waveguides, this all-optical switch has much lower switching threshold
power and sharper switching width.


title: Seesaw and noncommutative geometry

abstract:
  The 1-loop corrections to the seesaw mechanism in the noncommutative standard
model are computed. Other consequences of the Lorentzian signature in the inner
space are summarised.


title: The first XMM-Newton slew survey catalogue: XMMSL1

abstract:
  We report on the production of a large area, shallow, sky survey, from
XMM-Newton slews. The great collecting area of the mirrors coupled with the
high quantum efficiency of the EPIC detectors have made XMM-Newton the most
sensitive X-ray observatory flown to date. We use data taken with the EPIC-pn
camera during slewing manoeuvres to perform an X-ray survey of the sky. Data
from 218 slews have been subdivided into small images and source searched. This
has been done in three distinct energy bands; a soft (0.2-2 keV) band, a hard
(2-12 keV) band and a total XMM-Newton band (0.2-12 keV). Detected sources,
have been quality controlled to remove artifacts and a catalogue has been drawn
from the remaining sources. A 'full' catalogue, containing 4710 detections and
a 'clean' catalogue containing 2692 sources have been produced, from 14% of the
sky. In the hard X-ray band (2-12 keV) 257 sources are detected in the clean
catalogue to a flux limit of 4x10^-12 ergs/s/cm2. The flux limit for the soft
(0.2-2 keV) band is 6x10^-13 ergs/s/cm2 and for the total (0.2-12 keV) band is
1.2x10^-12 ergs/s/cm2. The source positions are shown to have an uncertainty of
8" (1-sigma confidence).


title:
Consistent simulations of substellar atmospheres and non-equilibrium
  dust-cloud formation

abstract:
  We aim to understand cloud formation in substellar objects. We combined the
non-equilibrium, stationary cloud model of Helling, Woitke & Thi (2008; seed
formation, growth, evaporation, gravitational settling, element conservation)
with the general-purpose model atmosphere code PHOENIX (radiative transfer,
hydrostatic equilibrium, mixing length theory, chemical equilibrium) in order
to consistently calculate cloud formation and radiative transfer with their
feedback on convection and gas phase depletion. We calculate the complete 1D
model atmosphere structure and the chemical details of the cloud layers. The
DRIFT-PHOENIX models enable the first stellar atmosphere simulation that is
based on the actual cloud formation process. The resulting (T,p) profiles
differ considerably from the previous limiting PHOENIX cases DUSTY and COND. A
tentative comparison with observations demonstrates that the determination of
effective temperatures based on simple cloud models has to be applied with
care. Based on our new models, we suggest a mean Teff=1800K for the L-dwarf
twin-binary system DENIS J0205-1159 which is up to 500K hotter than suggested
in the literature. We show transition spectra for gas-giant planets which form
dust clouds in their atmospheres and evaluate photometric fluxes for a WASP-1
type system.


title:
Enhanced Thermal Conductivity in Nanofluids Under the Action of
  Oscillating Force Fields

abstract:
  The thermal conductivity of nanoparticles colloidal suspensions, submitted to
the action of an external force field has been calculated by non equilibrium
molecular dynamics simulations. For driven forces in the radio frequency and
microwave ranges, we show that the thermal conductivity of nanofluids can be
strongly enhanced without cluster formation.


title:
Measuring the distribution of current fluctuations through a Josephson
  junction with very short current pulses

abstract:
  We propose to probe the distribution of current fluctuations by means of the
escape probability histogram of a Josephson junction (JJ), obtained using very
short bias current pulses in the adiabatic regime, where the low-frequency
component of the current fluctuations plays a crucial role. We analyze the
effect of the third cumulant on the histogram in the small skewness limit, and
address two concrete examples assuming realistic parameters for the JJ. In the
first one we study the effects due to fluctuations produced by a tunnel
junction, finding that the signature of higher cumulants can be detected by
taking the derivative of the escape probability with respect to current. In
such a realistic situation, though, the determination of the whole distribution
of current fluctuations requires an amplification of the cumulants. As a second
example we consider magnetic flux fluctuations acting on a SQUID produced by a
random telegraph source of noise.


title: Stable patterns of membrane domains at corrugated substrates

abstract:
  Multi-component membranes such as ternary mixtures of lipids and cholesterol
can exhibit coexistence regions between two liquid phases. When such membranes
adhere to a corrugated substrate, the phase separation process strongly depends
on the interplay between substrate topography, bending rigidities, and line
tension of the membrane domains as we show theoretically via energy
minimization and Monte Carlo simulations. For sufficiently large bending
rigidity contrast between the two membrane phases, the corrugated substrate
truncates the phase separation process and leads to a stable pattern of
membrane domains. Our theory is consistent with recent experimental
observations and provides a possible control mechanism for domain patterns in
biological membranes.


title:
Raman scattering studies of temperature- and field-induced melting of
  charge order in (La,Pr,Ca)MnO$_{3}$

abstract:
  We present Raman scattering studies of the structural and magnetic phases
that accompany temperature- and field-dependent melting of charge- and
orbital-order (COO) in La0.5Ca0.5MnO3 and La0.25Pr0.375Ca0.375MnO3. Our results
show that thermal and field-induced COO melting in La0.5Ca0.5MnO3 exhibits
three stages in a heterogeneous melting process associated with a structural
change: a long-range, strongly JT distorted/COO regime; a coexistence regime;
and weakly JT distorted/PM or FM phase. We provide a complete structural phase
diagram of La0.5Ca0.5MnO3 for the temperature and field ranges 6<=T<=170 K and
0<=H<=9 T. We also investigate thermal and field-induced melting in
La0.25Pr0.375Ca0.375MnO3 to elucidate the role of disorder in melting of COO.
We find that while thermal melting of COO in La0.25Pr0.375Ca0.375MnO3 is quite
similar to that in La0.5Ca0.5MnO3, the field-induced transition from the COO
phase to the weakly JT-distorted/FM phase in La0.25Pr0.375Ca0.375MnO3 is very
abrupt, and occurs at significantly lower fields (H~2 T at T~0 K) than in
La0.5Ca0.5MnO3 (H~30 T at T=0 K). Moreover, the critical field H_c increases
with increasing temperature in La0.25Pr0.375Ca0.375MnO3 in contrast to
La0.5Ca0.5MnO3. To explain these differences, we propose that field-induced
melting of COO in La0.25Pr0.375Ca0.375MnO3 is best described as the
field-induced percolation of FM domains, and we suggest that Griffiths phase
physics may be an appropriate theoretical model for describing the unusual
temperature- and field- dependent transitions observed in
La0.25Pr0.375Ca0.375MnO3.


title: Laser Guide Star Adaptive Optics without Tip-tilt

abstract:
  Adaptive optics (AO) systems allow a telescope to reach its diffraction limit
at near infrared wavelengths. But to achieve this, a bright natural guide star
(NGS) is needed for the wavefront sensing, severely limiting the fraction of
the sky over which AO can be used. To some extent this can be overcome with a
laser guide star (LGS). While the laser can be pointed anywhere in the sky, one
still needs to have a natural star, albeit fainter, reasonably close to correct
the image motion (tip-tilt) to which laser guide stars are insensitive. There
are in fact many astronomical targets without suitable tip-tilt stars, but for
which the enhanced resolution obtained with the Laser Guide Star Facility
(LGSF) would still be very beneficial. This article explores what adaptive
optics performance one might expect if one dispenses with the tip-tilt star,
and in what situations this mode of observing might be needed.


title:
Heat Transport Through Plasmonic Interactions in Closely Spaced Metallic
  Nanoparticles Chains

abstract:
  We report a numerical investigation on the heat transfer through one
dimensional arrays of metallic nanoparticles closely spaced in a host material.
Our simulations show that the multipolar interactions play a crucial role in
the heat transport via collective plasmons. Calculations of the plasmonic
thermal conductance and of the thermal conductivity in ballistic and diffusive
regime, respectively have been carried out. (a) Using the Landauer-Buttiker
formalism we have found that, when the host material dielectric constant takes
positive values, the multipolar interactions drastically enhance by several
order of magnitude the ballistic thermal conductance of collective plasmons
compared with that of a classical dipolar chain. On the contrary, when the host
material dielectric constant takes negative values, we have demonstrated the
existence of non-ballistic multipolar modes which annihilate the heat transfer
through the chains. (b) Using the kinetic theory we have also examined the
thermal behavior of chains in the diffusion approximation. We have shown that
the plasmonic thermal conductivity of metallic nanoparticle chains can reach 1%
of the bulk metal thermal conductivity . This result could explain the
anomalously high thermal conductivity observed in many collo\"idal suspensions,
the so called nanofluids.


title:
Reception frequency bandwidth of a gravitational resonant detector with
  optical readout

abstract:
  A gravitational resonant bar detector with a large scale Fabry-Perot cavity
as an optical read out and a mechanical displacement transformer is considered.
We calculate, in a fully analytical way, the final receiver bandwidth in which
the potential sensitivity, limited only by the bar thermal noise, is maintained
despite the additional thermal noise of the transformer and the additive noise
of the optical readout. We discuss also an application to the OGRAN project,
where the bar is instrumented with a 2m long FP cavity.


title:
Rectifiability of sets of finite perimeter in Carnot groups: existence
  of a tangent hyperplane

abstract:
  We consider sets of locally finite perimeter in Carnot groups. We show that
if E is a set of locally finite perimeter in a Carnot group G, then for almost
every x in G with respect to the perimeter measure of E, some tangent of E at x
is a vertical halfspace. This is a partial extension of a theorem of
Franchi-Serapioni-Serra Cassano in step 2 Carnot groups: they have shown that,
for almost every x, E has a unique tangent at x, and this tangent is a vertical
halfspace.


title: The effect of primordial fluctuations on neutrino oscillations

abstract:
  Recent work has shown that neutrino oscillations in matter can be greatly
enhanced by flips between mass eigenstates if the medium is fluctuating with a
period equal to the neutrino oscillation length. Here we investigate the effect
of the primordial fluctuations on the neutrino oscillations in the early
universe. We calculate the oscillation probability in the case of a general
power law fluctuation spectrum and for a more realistic spectrum predicted by
inflation. We also include the effect of the amplification of fluctuations
resulting from the QCD phase transition. We find that there is a region of
parameter space where this mechanism would be the dominant mechanism for
producing sterile neutrinos. However this conclusion does not take account of
the damping of fluctuations on the neutrino oscillation scale when the
neutrinos decouple from the plasma. We find that this reduces the probability
of flips between the mass eigenstates to an unobservable level.


title: Efficiency of molecular motors at maximum power

abstract:
  Molecular motors transduce chemical energy obtained from hydrolizing ATP into
mechanical work exerted against an external force. We calculate their
efficiency at maximum power output for two simple generic models and show that
the qualitative behaviour depends crucially on the position of the transition
state. Specifically, we find a transition state near the initial state
(sometimes characterized as a "power stroke") to be most favorable with respect
to both high power output and high efficiency at maximum power. In this regime,
driving the motor further out of equilibrium by applying higher chemical
potential differences can even, counter-intuitively, increase the efficiency.


title:
Attenuation of small-amplitude oscillations in a prominence-corona model
  with a transverse magnetic field

abstract:
  Small-amplitude prominence oscillations are usually damped after a few
periods. We study the attenuation of non-adiabatic magnetoacoustic waves in a
slab prominence embedded in the coronal medium. We assume an equilibrium
configuration with a transverse magnetic field to the slab axis and investigate
wave damping by thermal conduction and radiative losses. The differential MHD
equations that govern linear slow and fast modes are numerically solved to
obtain the complex oscillatory frequency and the corresponding eigenfunctions.
We find that coronal thermal conduction and radiative losses from the
prominence plasma reveal as the most relevant damping mechanisms. Both
mechanisms govern together the attenuation of hybrid modes, whereas prominence
radiation is responsible for the damping of internal modes and coronal
conduction essentially dominates the attenuation of external modes. In
addition, the energy transfer between the prominence and the corona caused by
thermal conduction has a noticeable effect on the wave stability, radiative
losses from the prominence plasma being of paramount importance for the thermal
stability of fast modes. We conclude that slow modes are efficiently damped,
with damping times compatible with observations. On the contrary, fast modes
are less attenuated by non-adiabatic effects and their damping times are
several orders of magnitude larger than those observed. The presence of the
corona causes a decrease of the damping times with respect to those of an
isolated prominence slab, but its effect is still insufficient to obtain
damping times of the order of the period in the case of fast modes.


title: The HST/ACS Coma Cluster Survey: I - Survey Objectives and Design

abstract:
  We describe the HST ACS Coma cluster Treasury survey, a deep two-passband
imaging survey of one of the nearest rich clusters of galaxies, the Coma
cluster (Abell 1656).
  The survey was designed to cover an area of 740 square arcmin in regions of
different density of both galaxies and intergalactic medium within the cluster.
The ACS failure of January 27th 2007 leaves the survey 28% complete, with 21
ACS pointings (230 square arcmin) complete, and partial data for a further 4
pointings (44 square arcmin).
  Predicted survey depth for 10 sigma detections for optimal photometry of
point sources is g' = 27.6 in the F475W filter, and IC=26.8 mag in F814 (AB
magnitudes). Initial simulations with artificially injected point sources show
90% recovered at magnitude limits of g' = 27.55 and IC = 26.65. For extended
sources, the predicted 10 sigma limits for a 1 square arcsecond region are g' =
25.8 mag/sq. arcsec and IC = 25.0 mag/sq. arcsec.
  We highlight several motivating science goals of the survey, including study
of the faint end of the cluster galaxy luminosity function, structural
parameters of dwarf galaxies, stellar populations and their effect on colors
and color gradients, evolution of morphological components in a dense
environment, the nature of ultra compact dwarf galaxies, and globular cluster
populations of cluster galaxies of a range of luminosities and types. This
survey will also provide a local rich cluster benchmark for various well known
global scaling relations and explore new relations pertaining to the nuclear
properties of galaxies.


title: Geometrization of Classical Wave Fields

abstract:
  Geometrical model for material Dirac wave field and for Maxwell
electromagnetic field is suggested where above fields are considered as
propagating regions of the space itself with distorted euclidean geometry. It
is shown that equations for these fields can be considered as relations
describing the space topological defects. These defects, being closed
topological manifolds, are embedded in the outer five-dimensional space, and
observable objects appear to be intersections of above defects with the
physical space. This interpretation explains irrational properties of quantum
objects such as wave-corpuscular duality, stochastic behavior, instantaneous
nonlocal correlation in EPR-paradox, the light velocity invariance and so on.
Wave-corpuscular properties arise as a result of the defect periodical movement
in the outer space relative to its intersection with the physical space, and
just this periodical movement attributes phase to the propagating object.
Appearance of probabilities within the formalism is a consequence of
uncertainty of the closed topological manifold shape, and ensemble of all
possible shapes for the same object can be considered as an ensemble of hidden
variables that leads to probabilistic description. Embedded in the outer space
topological defects provide channels for nonlocal correlations between their
intersections-- noninteracting particles in EPR-experiments, and this means
that the proposed approach can be considered as a nonlocal model with hidden
variables.


title: Inverse zero-sum problems II

abstract:
  Let $G$ be an additive finite abelian group. A sequence over $G$ is called a
minimal zero-sum sequence if the sum of its terms is zero and no proper
subsequence has this property. Davenport's constant of $G$ is the maximum of
the lengths of the minimal zero-sum sequences over $G$. Its value is well-known
for groups of rank two. We investigate the structure of minimal zero-sum
sequences of maximal length for groups of rank two. Assuming a well-supported
conjecture on this problem for groups of the form $C_m \oplus C_m$, we
determine the structure of these sequences for groups of rank two. Combining
our result and partial results on this conjecture, yields unconditional results
for certain groups of rank two.


title:
Bounded H_\infty-calculus for pseudodifferential Douglis-Nirenberg
  systems of mild regularity

abstract:
  Parameter-ellipticity with respect to a closed subsector of the complex plane
for pseudodifferential Douglis-Nirenberg systems is discussed and shown to
imply the existence of a bounded H_\infty-calculus in suitable scales of
Sobolev, Besov, and Hoelder spaces. We also admit non pseudodifferential
perturbations. Applications concern systems with coefficients of mild Hoelder
regularity and the generalized thermoelastic plate equations.


title:
The Exciting Star of the Berkeley 59/Cepheus OB4 Complex and Other
  Chance Variable Star Discoveries

abstract:
  A study is presented regarding the nature of several variable stars sampled
during a campaign of photometric monitoring from the Abbey Ridge Observatory: 3
eclipsing binaries, 2 semiregulars, a luminous Be star, and a star of uncertain
classification. For one of the eclipsing systems, BD+66 1673, spectroscopic
observations reveal it to be an O5 V((f))n star and the probable ionizing star
of the Berkeley 59/Cep OB4 complex. An analysis of spectroscopic observations
and BV photometry for Berkeley 59 members in conjunction with published
observations imply a cluster age of ~2 Myr, a distance of d = 883+-43 pc, and a
reddening of E(B-V) =1.38+-0.02. Two of the eclipsing systems are Algol-type,
but one appears to be a cataclysmic variable associated with an X-ray source.
ALS 10588, a B3 IVn star associated with the Cepheid SV Vul, is of uncertain
classification, although consideration is given to it being a slowly pulsating
B star. The environmental context of the variables is examined using
spectroscopic parallax, 2MASS photometry, and proper motion data, the latter to
evaluate the membership of the variable B2 Iabe star HDE 229059 in Berkeley 87,
an open cluster that could offer a unique opportunity to constrain empirically
the evolutionary lineage of young massive stars. Also presented are our null
results for observations of a sample of northern stars listed as Cepheid
candidates in the Catalogue of Newly Suspected Variables.


title:
Bethe approximation for the hydrogen-bonding self-avoiding walk in a
  solvent

abstract:
  A square-lattice model for the formation of secondary structures in proteins,
the hydrogen-bonding model, extended to include the effects of solvent quality,
is examined in the framework of the Bethe approximation.


title:
Higher Accuracy for Bayesian and Frequentist Inference: Large Sample
  Theory for Small Sample Likelihood

abstract:
  Recent likelihood theory produces $p$-values that have remarkable accuracy
and wide applicability. The calculations use familiar tools such as maximum
likelihood values (MLEs), observed information and parameter rescaling. The
usual evaluation of such $p$-values is by simulations, and such simulations do
verify that the global distribution of the $p$-values is uniform(0, 1), to high
accuracy in repeated sampling. The derivation of the $p$-values, however,
asserts a stronger statement, that they have a uniform(0, 1) distribution
conditionally, given identified precision information provided by the data. We
take a simple regression example that involves exact precision information and
use large sample techniques to extract highly accurate information as to the
statistical position of the data point with respect to the parameter:
specifically, we examine various $p$-values and Bayesian posterior survivor
$s$-values for validity. With observed data we numerically evaluate the various
$p$-values and $s$-values, and we also record the related general formulas. We
then assess the numerical values for accuracy using Markov chain Monte Carlo
(McMC) methods. We also propose some third-order likelihood-based procedures
for obtaining means and variances of Bayesian posterior distributions, again
followed by McMC assessment. Finally we propose some adaptive McMC methods to
improve the simulation acceptance rates. All these methods are based on
asymptotic analysis that derives from the effect of additional data. And the
methods use simple calculations based on familiar maximizing values and related
informations. The example illustrates the general formulas and the ease of
calculations, while the McMC assessments demonstrate the numerical validity of
the $p$-values as percentage position of a data point. The example, however, is
very simple and transparent, and thus gives little indication that in a wide
generality of models the formulas do accurately separate information for almost
any parameter of interest, and then do give accurate $p$-value determinations
from that information. As illustration an enigmatic problem in the literature
is discussed and simulations are recorded; various examples in the literature
are cited.


title: A coronal explosion on the flare star CN Leonis

abstract:
  We present simultaneous high-temporal and high-spectral resolution
observations at optical and soft X-ray wavelengths of the nearby flare star CN
Leo. During our observing campaign a major flare occurred, raising the star's
instantaneous energy output by almost three orders of magnitude. The flare
shows the often observed impulsive behavior, with a rapid rise and slow decay
in the optical and a broad soft X-ray maximum about 200 seconds after the
optical flare peak. However, in addition to this usually encountered flare
phenomenology we find an extremely short (~2 sec) soft X-ray peak, which is
very likely of thermal, rather than non-thermal nature and temporally coincides
with the optical flare peak. While at hard X-ray energies non-thermal bursts
are routinely observed on the Sun at flare onset, thermal soft X-ray bursts on
time scales of seconds have never been observed in a solar nor stellar context.
Time-dependent, one-dimensional hydrodynamic modeling of this event requires an
extremely short energy deposition time scale of a few seconds to reconcile
theory with observations, thus suggesting that we are witnessing the results of
a coronal explosion on CN Leo. Thus the flare on CN Leo provides the
opportunity to observationally study the physics of the long-sought
"micro-flares" thought to be responsible for coronal heating.


title:
The massive binary HD 152218 revisited: A new colliding wind system in
  NGC 6231

abstract:
  We present the results of an optical and X-ray monitoring campaign on the
short-period massive SB2 binary HD 152218. Combining our HiRes spectroscopic
data with previous observations, we unveil the contradictions between the
published orbital solutions. In particular, we solve the aliasing on the period
and derive a value close to 5.604 d. Our eccentricity e = 0.259 +/- 0.006 is
slightly lower than previously admitted. We show that HD 152218 is probably
undergoing a relatively rapid apsidal motion of about 3deg/yr and we confirm
the O9IV + O9.7V classification. We derive minimal masses of 15.82 +/- 0.26
Msol operator and 12.00 +/- 0.19 Msol operator and constrain the radius of the
components to R1 = 10.3 +/- 1.3 Rsol and R2 = 7.8 +/- 1.7 Rsol. We also report
the results of an XMM-Newton monitoring of the HD 152218 X-ray emission
throughout its orbital motion. The averaged X-ray spectrum is relatively soft
and it is well reproduced by a 2-T optically thin thermal plasma model with
component temperatures about 0.3 and 0.7 keV. The system presents an increase
of its X-ray flux by about 30% near apastron compared to periastron, which is
interpreted as the signature of an ongoing wind-wind interaction process
occurring within the wind acceleration region.


title: Representation of nonnegative convex polynomials

abstract:
  We provide a specific representation of convex polynomials nonnegative on a
convex (not necessarily compact) basic closed semi-algebraic subset K of Rn.
Namely, they belong to a specific subset of the quadratic module generated by
the concave polynomials that define K.


title:
Generalized iteration, catastrophes and generalized Sharkovsky's
  ordering

abstract:
  We define iteration of functions that map n-dimensional vector spaces into
m-dimensional vector spaces (m at most equal to n). It happens that usual
iteration and Fibonacci iterative methods become special cases of this
generalized iteration. Mathematical objects such as orbits, bifurcations,
chaos, Feigenbaum constant, (generalized) Sharkovsky ordering, (generalized)
Julia and Mandelbrot sets and a new kind of catastrophe can be found and
studied in this enlarged context.


title:
Tracing the distribution and evolution of Iron in the IntraCluster
  Medium

abstract:
  Emission lines in X-ray spectra of clusters of galaxies reveal the presence
of heavy elements in the diffuse hot plasma (ICM) in virial equilibrium in the
dark matter potential well. Thanks to the X-ray satellites Chandra and
XMM-Newton we are now able to measure with good accuracy the distribution and
evolution of Iron up to redshift z ~ 1.3. The capability of studying the
chemical and thermodynamical properties of the ICM in high redshift clusters is
an efficient tool to constrain the interaction processes between the cluster
galaxies and the surrounding medium. We confirm that the ICM is already
significantly enriched at a look-back time of 9 Gyr, and find that the Iron
abundance change with redshift as (1+z)^(-1.25), implying an increase of a
factor of ~2 with respect to z=1.3. This result can be explained by a prompt
enrichment by star formation processes in massive ellipticals at z>2, followed
by a slower release of enriched gas from disk galaxies into the ICM, associated
to a morphological transition from disk to S0.


title:
Spin-driven ferroelectricity and possible antiferroelectricity in
  triangular lattice antiferromagnets ACrO2 (A = Cu, Ag, Li, or Na)

abstract:
  Correlation between dielectric and magnetic properties was investigated on
the triangular lattice antiferromagnets ACrO2 (A= Cu, Ag, Li, or Na) showing
120-degree spiral spin structure with easy-axis anisotropy. For the A= Cu and
Ag compounds with delafossite structure, ferroelectric polarization emerges
upon the spiral spin order, implying the strong coupling between the
ferroelectricity and spiral spin structure. On the other hand, for the A = Li
and Na compounds with ordered rock salt structure, no polarization but only
clear anomalies in dielectric constant can be observed upon the spiral spin
order. The absence of polarization can be interpreted as the antiferroelectric
state induced by the alternate stacking of Cr3+ layer with opposite spin vector
chirality. These results imply that a vast range of trigonally stacked
triangular-lattice systems with 120-degree spin structure can be multiferroic,
irrespective of their magnetic anisotropy.


title: From planes to spheres: About gravitational lens magnifications

abstract:
  We discuss the classic theorem according to which a gravitational lens always
produces a total magnification greater than unity. This theorem seems to
contradict the conservation of total flux from a lensed source. The standard
solution to this paradox is based on the exact definition of the reference
'unlensed' situation.
  We calculate magnifications and amplifications for general lensing scenarios
not limited to regions close to the optical axis. In this way the formalism is
naturally extended from tangential planes for the source and lensed images to
complete spheres. We derive the lensing potential theory on the sphere and find
that the Poisson equation is modified by an additional source term that is
related to the mean density and to the Newtonian potential at the positions of
observer and source. This new term generally reduces the magnification, to
below unity far from the optical axis, and ensures conservation of the total
photon number received on a sphere around the source.
  This discussion does not affect the validity of the 'focusing theorem', in
which the unlensed situation is defined to have an unchanged affine distance
between source and observer. The focusing theorem does not contradict flux
conservation, because the mean total magnification directly corresponds to
different areas of the source sphere in the lensed and unlensed situation. We
argue that a constant affine distance does not define an astronomically
meaningful reference.
  By exchanging source and observer, we confirm that magnification and
amplification differ according to Etherington's reciprocity law, so that
surface brightness is no longer strictly conserved. [ abridged ]


title:
On the influence of ram-pressure stripping on the star formation of
  simulated spiral galaxies

abstract:
  We investigate the influence of ram-pressure stripping on the star formation
and the mass distribution in simulated spiral galaxies. Special emphasis is put
on the question where the newly formed stars are located. The stripping radius
from the simulation is compared to analytical estimates. Disc galaxies are
modelled in combined N-body/hydrodynamic simulations (GADGET-2) with
prescriptions for cooling, star formation, stellar feedback, and galactic
winds. These model galaxies move through a constant density and temperature
gas, which has parameters comparable to the intra-cluster medium (ICM) in the
outskirts of a galaxy cluster (T=3 keV ~3.6x10^7 K and rho=10^-28 g/cm^3). With
this numerical setup we analyse the influence of ram-pressure stripping on the
star formation rate of the model galaxy. We find that the star formation rate
is significantly enhanced by the ram-pressure effect (up to a factor of 3).
Stars form in the compressed central region of the galaxy as well as in the
stripped gas behind the galaxy. Newly formed stars can be found up to hundred
kpc behind the disc, forming structures with sizes of roughly 1 kpc in diameter
and with masses of up to 10^7 M_sun. As they do not possess a dark matter halo
due to their formation history, we name them 'stripped baryonic dwarf'
galaxies. We also find that the analytical estimate for the stripping radius
from a Gunn & Gott (1972) criterion is in good agreement with the numerical
value from the simulation. Like in former investigations, edge-on systems lose
less gas than face-on systems and the resulting spatial distribution of the gas
and the newly formed stars is different.


title:
Disassembling the Nuclear Matrix Elements of the Neutrinoless double
  beta Decay

abstract:
  In this article we analyze the nuclear matrix elements (NME) of the
neutrinoless double beta decays of the nuclei 48-Ca, 76-Ge, 82-Se, 124-Sn,
130-Te and 136-Xe in the framework of the Interacting Shell Model (ISM). We
study the relative value of the different contributions to them, such as higher
order terms in the nuclear current, finite nuclear size effects and short range
correlations, as well as their evolution with the maximum seniority permitted
in the wave functions. We discuss also the build-up of the NME's as a function
of the distance between the decaying neutrons. We calculate the decays to final
0+ first excited states and find that these decays are at least 25 times more
supressed with respect to the ground state to ground state transition.