title: Annealed vs Quenched Critical Points for a Random Walk Pinning Model

abstract:
  We study a random walk pinning model, where conditioned on a simple random
walk Y on Z^d acting as a random medium, the path measure of a second
independent simple random walk X up to time t is Gibbs transformed with
Hamiltonian -L_t(X,Y), where L_t(X,Y) is the collision local time between X and
Y up to time t. This model arises naturally in various contexts, including the
study of the parabolic Anderson model with moving catalysts, the parabolic
Anderson model with Brownian noise, and the directed polymer model. It falls in
the same framework as the pinning and copolymer models, and exhibits a
localization-delocalization transition as the inverse temperature \beta varies.
We show that in dimensions d=1,2, the annealed and quenched critical values of
\beta are both 0, while in dimensions d\geq 4, the quenched critical value of
\beta is strictly larger than the annealed critical value (which is positive).
This implies the existence of certain intermediate regimes for the parabolic
Anderson model with Brownian noise and the directed polymer model. For d\geq 5,
the same result has recently been established by Birkner, Greven and den
Hollander via a quenched large deviation principle. Our proof is based on a
fractional moment method used recently by Derrida, Giacomin, Lacoin and
Toninelli to establish the non-coincidence of annealed and quenched critical
points for the pinning model in the disorder-relevant regime. The critical case
d=3 remains open.


title:
Mapping Dark Matter in Galaxy Clusters: Gravitational Lensing &
  Numerical Simulations

abstract:
  The different regimes of gravitational lensing constitutes an interesting
tool in order to map the mass distribution in galaxy clusters on different
scales. In this proceedings article, I review some work I have performed on
this topic. More precisely, I will focus on : (i) galaxy scale substructures,
using weak galaxy-galaxy lensing in order to study how does the environment
shape their properties; (ii) the mass profile of Abell~1689 as probed combining
strong and weak lensing; (iii) the slope of the inner dark matter distribution
in Abell~1703 as measured by strong lensing. The lensing results will be
compared to the expectations from numerical simulations, when available.


title:
The influence of the Alfv\'enic drift on the shape of cosmic ray spectra
  in SNRs

abstract:
  Cosmic ray acceleration in SNRs in the presence of the Alfv\'enic drift is
considered. It is shown that spectra of accelerated particles may be
considerably softer in the presence of amplified magnetic fields.


title: Chemical potential and the gap equation

abstract:
  In general the kernel of QCD's gap equation possesses a domain of analyticity
upon which the equation's solution at nonzero chemical potential is simply
obtained from the in-vacuum result through analytic continuation. On this
domain the single-quark number- and scalar-density distribution functions are
mu-independent. This is illustrated via two models for the gap equation's
kernel. The models are alike in concentrating support in the infrared. They
differ in the form of the vertex but qualitatively the results are largely
insensitive to the Ansatz. In vacuum both models realise chiral symmetry in the
Nambu-Goldstone mode and in the chiral limit, with increasing chemical
potential, exhibit a first-order chiral symmetry restoring transition at
mu~M(0), where M(p^2) is the dressed-quark mass function. There is evidence to
suggest that any associated deconfinement transition is coincident and also of
first-order.


title: Fast fluorescence dynamics in non-ratiometric calcium indicators

abstract:
  A fluorescence decay of high-affinity non-ratiometric Ca2+ indicator Oregon
Green BAPTA-1 (OGB-1) is analyzed with unprecedented temporal resolution in the
two-photon excitation regime. A triple exponential decay is shown to best fit
the fluorescence dynamics of OGB-1. We provide a new model for accurate
measurements of the free Ca2+ concentration and dissociation constants of
non-ratiometric calcium indicators.


title:
Phase Diagram of Vortices in High-T_c Superconductors with a Melting
  Line in the deep H_{c2} Region

abstract:
  We use a simple elastic Hamiltonian for the vortex lattice in a weak impurity
background which includes defects in the form of integer-valued fields to
calculate the free energy of a vortex lattice in the deep H_{c2} region. The
phase diagram in this regime is obtained by applying the variational approach
of M{\'e}zard and Parisi developed for random manifolds. We find a first-order
line between the Bragg-glass and vortex-glass phase as a continuation of the
melting line. In the liquid phase, we obtain an almost vertical third-order
glass transition line near the critical temperature in the H-T plane.
Furthermore, we find an almost vertical second-order phase transition line in
the Bragg-glass as well as the vortex-glass phases which crosses the
first-order Bragg-glass, vortex-glass transition line. We calculate the jump of
the temperature derivate of the induction field across this second-order line
as well as the entropy and magnetic field jumps across the first-order line.


title: Simultaneous Communication Protocols with Quantum and Classical Messages

abstract:
  We study the simultaneous message passing (SMP) model of communication
complexity, for the case where one party is quantum and the other is classical.
We show that in an SMP protocol that computes some function with the first
party sending q qubits and the second sending c classical bits, the quantum
message can be replaced by a randomized message of O(qc) classical bits, as
well as by a deterministic message of O(q c log q) classical bits. Our proofs
rely heavily on earlier results due to Scott Aaronson.
  In particular, our results imply that quantum-classical protocols need to
send Omega(sqrt{n/log n}) bits/qubits to compute Equality on n-bit strings, and
hence are not significantly better than classical-classical protocols (and are
much worse than quantum-quantum protocols such as quantum fingerprinting). This
essentially answers a recent question of Wim van Dam. Our results also imply,
more generally, that there are no superpolynomial separations between
quantum-classical and classical-classical SMP protocols for functional
problems. This contrasts with the situation for relational problems, where
exponential gaps between quantum-classical and classical-classical SMP
protocols are known. We show that this surprising situation cannot arise in
purely classical models: there, an exponential separation for a relational
problem can be converted into an exponential separation for a functional
problem.


title:
Resolving the Mass Hierarchy with Atmospheric Neutrinos using a Liquid
  Argon Detector

abstract:
  We explore the potential offered by large-mass Liquid Argon detectors for
determination of the sign of Delta m_{31}^2, or the neutrino mass hierarchy,
through interactions of atmospheric neutrinos. We give results for a 100 kT
sized magnetized detector which provides separate sensitivity to \nu_\mu,
\bar{\nu}_\mu and, over a limited energy range, to \nu_e, \bar{\nu}_e.We also
discuss the sensitivity for the unmagnetized version of such a detector. After
including the effect of smearing in neutrino energy and direction and
incorporating the relevant statistical,theoretical and systematic errors, we
perform a binned \chi^2 analysis of simulated data. The \chi^2 is marginalized
over the presently allowed ranges of neutrino parameters and determined as a
function of \theta_{13}. We find that such a detector offers superior
capabilities for hierarchy resolution, allowing a > 4\sigma determination for a
100 kT detector over a 10 year running period for values of \sin^2 2\theta_{13}
\ge 0.05. For an unmagnetized detector, a 2.5\sigma hierarchy sensitivity is
possible for \sin^2 2\theta_{13} = 0.04.


title:
Evidence for recent star formation in BCGs: a correspondence between
  blue cores and UV excess

abstract:
  We present a joint analysis of near-ultraviolet (NUV) data from the GALEX
mission and (optical) colour profiles for a sample of 7 Brightest Cluster
Galaxies (BCGs) in the Canadian Cluster Comparison Project. We find that every
BCG which has a blue rest-frame UV colour also shows a blue-core in its optical
colour profile. Conversely, BCGs that lack blue cores and show monotonic colour
gradients typical of old elliptical galaxies, are red in the UV. We interpret
this as evidence that the NUV enhancement in the blue BCGs is driven by recent
star formation and not from old evolved stellar populations such as horizontal
branch stars. The recent star formation in the blue BCGs typically has an age
less than 200 Myrs and contributes mass fractions of less than a percent.
Although the sample studied here is small, we demonstrate, for the first time,
a one-to-one correspondence between blue cores in elliptical galaxies (in
particular BCGs) and a NUV-enhancement observed using GALEX. The combination of
this one-to-one correspondence and the consistently young age of recent star
formation, coupled with additional correlations with the host cluster's X-ray
properties, strongly suggests that the star formation is fueled by gas cooling
out of the intracluster medium. In turn, this implies that any AGN heating of
the intracluster medium in massive clusters only acts to reduce the magnitude
of the cooling flow and that once this flow starts, it is nearly always active.
(abridged)


title:
Thornhill, de Broglie and the kinetic theory of electromagnetic
  radiation

abstract:
  In 1983, Thornhill showed that Planck's energy distribution for a black-body
radiation field could be derived for a gas-like aether with Maxwellian
statistics. Further, it was shown that the frequency of electromagnetic waves
correlates with the energy per unit mass of the particles, not with their
energy, thus differing from Planck's quantum hypothesis. He pointed out that de
Broglie, in a paper of 1922, was on the way to achieving this result but did
not pursue the matter to its logical conclusion. Here a translation of de
Broglie's paper is presented to draw attention to this point. Some brief
additional comments are included also.


title: PHOTOS Monte Carlo and its theoretical accuracy

abstract:
  Because of properties of QED, the bremsstrahlung corrections to decays of
particles or resonances can be calculated, with a good precision, separately
from other effects. Thanks to the widespread use of event records such
calculations can be embodied into a separate module of Monte Carlo simulation
chains, as used in High Energy Experiments of today. The PHOTOS Monte Carlo
program is used for this purpose since nearly 20 years now. In the following
talk let us review the main ideas and constraints which shaped the program
version of today and enabled it widespread use. Finally, we will underline
importance of aspects related to reliability of program results: event record
contents and implementation of channel specific matrix elements.


title:
Laser-induced nonsequential double ionization in diatomic molecules: one
  and two-center rescattering scenarios

abstract:
  We investigate laser-induced nonsequential double ionization from aligned
diatomic molecules, using the strong-field approximation in its length and
velocity gauge formulations. Throughout, we consider that the first electron
dislodges the second by electron-impact ionization. Employing modified
saddle-point equations, we single out the contributions of different scattering
scenarios to the maxima and minima observed in the differential electron
momentum distributions. We show that the quantum interference between the
electron orbits starting and ending at a specific center $C_{j}$%, and those
starting at $C_{j}$ and ending at a different center $C_{\nu}$ leads to the
same maxima as minima as if all possible scenarios are taken. There exist,
however, quantitative differences as far as the gauge choice is concerned.
Indeed, while the velocity-gauge distributions obtained employing only the
above-mentioned processes are practically identical to the overall
distributions, their length-gauge counterparts exhibit an asymmetry in the
positive and negative momentum regions. This asymmetry is due to additional
potential-energy shifts which are only present in the length-gauge formulation,
and which, depending on the center, sink or increase the potential barrier
through which the first electron tunnels. In contrast, the interference between
topologically similar scenarios leads at most to patterns whose positions, in
momentum space, do not agree with the overall interference condition, neither
in the length nor in the velocity gauge.


title: The red clump absolute magnitude based on revised Hipparcos parallaxes

abstract:
  Over the past decade the use of the red clump (RC) as distance indicator has
increased in importance as this evolutionary phase is well populated and a good
local calibration exists.
  The absolute calibration of the RC in the $I$ and $K$ band is investigated
again based on the recently published revised Hipparcos parallaxes.
  A numerical model is developed that takes the various selection criteria and
the properties of the Hipparcos catalogue into account. The biases involved in
applying certain selections are estimated with this model.
  The absolute magnitudes that are found are $M_{\rm I} = -0.22 \pm 0.03$ and
$M_{\rm K} = -1.54 \pm 0.04$ (on the 2MASS system). The $I$-band value is in
good agreement with previous determinations, the $K$-band value is fainter than
previously quoted, and this seems to be related to a selection bias whereby
accurate $K$-magnitudes are only available for relatively few bright stars.
Applying population corrections to the absolute $K$ magnitude of RC stars in
clusters supports the fainter magnitude scale.


title:
QM/MM Lineshape Simulation of the Hydrogen-bonded Uracil NH Stretching
  Vibration of the Adenine:Uracil Base Pair in CDCl$_3$

abstract:
  A hybrid Car-Parrinello QM/MM molecular dynamics simulation has been carried
out for the Watson-Crick base pair of 9-ethyl-8-phenyladenine and
1-cyclohexyluracil in deuterochloroform solution at room temperature. The
resulting trajectory is analyzed putting emphasis on the N-H$...$N Hydrogen
bond geometry. Using an empirical correlation between the $\NN$-distance and
the fundamental NH-stretching frequency, the time-dependence of this energy gap
along the trajectory is obtained. From the gap-correlation function we
determine the infrared absorption spectrum using lineshape theory in
combination with a multimode oscillator model. The obtained average transition
frequency and the width of the spectrum is in reasonable agreement with recent
experimental data.


title: Contorted Flavors in Grand Unification and Proton Decay

abstract:
  Conventionally we collect electron and up/down-quarks (u,d)+(nu_e,e) to form
unified generations, and collect the left-handed and the right-handed fermions
of the same flavors (nu_e,e)+e^c. We can alternatively have a contorted
multiplet, made by pairing different quarks and leptons, like (u,d)+(nu_mu,mu)
or (u,d)+(nu_tau,tau), and/or between different left and right handed fermions
to (nu_e,e)+mu^c, etc. These can suppress proton decay, due to its high flavor
dependence, while having the correct fermion masses.


title: ABC likelihood-freee methods for model choice in Gibbs random fields

abstract:
  Gibbs random fields (GRF) are polymorphous statistical models that can be
used to analyse different types of dependence, in particular for spatially
correlated data. However, when those models are faced with the challenge of
selecting a dependence structure from many, the use of standard model choice
methods is hampered by the unavailability of the normalising constant in the
Gibbs likelihood. In particular, from a Bayesian perspective, the computation
of the posterior probabilities of the models under competition requires special
likelihood-free simulation techniques like the Approximate Bayesian Computation
(ABC) algorithm that is intensively used in population genetics. We show in
this paper how to implement an ABC algorithm geared towards model choice in the
general setting of Gibbs random fields, demonstrating in particular that there
exists a sufficient statistic across models. The accuracy of the approximation
to the posterior probabilities can be further improved by importance sampling
on the distribution of the models. The practical aspects of the method are
detailed through two applications, the test of an iid Bernoulli model versus a
first-order Markov chain, and the choice of a folding structure for two
proteins.


title: Quantum Information and Wave function Collapse

abstract:
  Inofrmation-theoretical restrictions on information transferred in the
measurement of object S by information system O are studied. It is shown that
such constraints, induced by Heisenberg commutation relations, result in the
loss of information about the purity of S state. Consequently, it becomes
impossible for O to discriminate pure and mixed S states. In individual events
this effect is manifested by the stochastic outcomes of pure S state
measurement, i.e. the collapse of pure S state.


title:
Minimax state estimation for linear discrete-time differential-algebraic
  equations

abstract:
  This paper presents a state estimation approach for an uncertain linear
equation with a non-invertible operator in Hilbert space. The approach
addresses linear equations with uncertain deterministic input and noise in the
measurements, which belong to a given convex closed bounded set. A new notion
of a minimax observable subspace is introduced. By means of the presented
approach, new equations describing the dynamics of a minimax recursive
estimator for discrete-time non-causal differential-algebraic equations (DAEs)
are presented. For the case of regular DAEs it is proved that the estimator's
equation coincides with the equation describing the seminal Kalman filter. The
properties of the estimator are illustrated by a numerical example.


title: Dirac Cones and Minigaps for Graphene on Ir(111)

abstract:
  Epitaxial graphene on Ir(111) prepared in excellent structural quality is
investigated by angle-resolved photoelectron spectroscopy. It clearly displays
a Dirac cone with the Dirac point shifted only slightly above the Fermi level.
The moire resulting from the overlaid graphene and Ir(111) surface lattices
imposes a superperiodic potential giving rise to Dirac cone replicas and the
opening of minigaps in the band structure.


title:
Multiscale modeling of plastic deformation of molybdenum and tungsten:
  II. Yield criterion for single crystals based on atomistic studies of glide
  of 1/2<111> screw dislocations

abstract:
  Based on the atomistic studies presented in Part I we develop analytical
yield criteria for single crystals that capture the effect of shear stresses
other than the Schmid stress (non-glide stresses) on the shear stress needed
for dislocation glide (Peierls stress). These yield criteria characterize a
non-associated plastic flow that originates owing to the complex response of
1/2<111> screw dislocations to an applied stress tensor. Employing these
criteria we identify the operative slip systems for tensile/compressive loading
along various axes within the standard stereographic triangle and determine the
ensuing tension-compression asymmetry. This result is in an excellent
qualitative agreement with available experimental data. Moreover, using the
constructed yield criteria within the Taylor homogenization procedure, we
demonstrate that effects associated with non-planar cores of screw dislocations
persist in random polycrystals. This affects significantly critical phenomena
such as shear localization, which is demonstrated by analyzing the cavitation
in a ductile plastic solid.


title:
Multiscale modeling of plastic deformation of molybdenum and tungsten:
  III. Effects of temperature and plastic strain rate

abstract:
  In this paper we develop a link between the atomic-level modeling of the
glide of 1/2<111> screw dislocations at 0 K and the thermally activated motion
of these dislocations via nucleation of pairs of kinks. For this purpose, we
introduce the concept of a hypothetical Peierls barrier, which reproduces all
the aspects of the dislocation glide at 0 K resulting from the complex response
to non-glide stresses and is expressed in a compact form by the yield criteria
advanced in Part II. To achieve this the barrier is dependent not only on the
crystal symmetry and interatomic bonding but also on the applied stress tensor.
Standard models are then employed to evaluate the activation enthalpy of
kink-pairs formation, which is now also a function of the full applied stress
tensor. The transition states theory links then this mechanism with the
temperature and strain rate dependence of the yield stress.


title:
In search of the true vacuum: natural ordering, $\gamma$ condensate and
  the last renormalization

abstract:
  With the idea of canceling the leading divergence in vacuum energy of
$\varphi^4$ field theory a parameter is introduced that interpolates between
free Hamiltonian with or without normal ordering. This leads to a condensate
ground state having an arbitrary number of particle-particle pairs. In addition
to the usual states, the condensate supports the states of negative energy and
negative norm. An explicit expression for the condensate state is derived and
perturbation theory with this state investigated. The propagator is modified
off the mass shell while unchanged on the mass shell. Lowest order correction
to the vacuum energy is calculated and conditions for cancelation of the
leading divergence investigated. One possible solution is that all radiative
corrections in this formulation vanish. The other possible solution implies a
phase transition above the coupling of $\frac{(2\pi)^2}{3}$ and the condensate
non-analytical in the coupling constant. Possible implications are discussed.


title:
Search for exotic matter from gravitational microlensing observations of
  stars

abstract:
  We consider small-scale spheroidal clusters of weakly interacting massive
particles in our Galaxy as non-compact gravitational microlenses and predict
the appearance of caustics in the plane of a lensed source. The crossing of
these caustics by a lensed star can produce a large variety of light curves,
including some observed in actual microlensing events that have been
interpreted as manifestations of binary gravitational lenses. We consider also
observable effects during the gravitational microlensing of stars of non-zero
angular size with a given brightness distribution across their disks by such an
exotic objects as natural wormholes and objects whose space-time environment is
described with the NUT metric. We demonstrate that, under certain conditions,
the microlensing light curves, chromatic and polarizational effects due to the
properties of the lens and the star disk brightness distributions can differ
considerably from those observed for a Schwarzschild gravitational lens, so
that their analysis can facilitate the identification of such objects.


title:
Historical and mathematical aspects of iterative solutions for Monte
  Carlo simulations

abstract:
  Over the last 25 years Monte Carlo programs were being developped in Cracow
in the group guided by Prof. Stanislaw Jadach. Many of those programs became
standard in their application domains. In the following let us review some
aspects of such projects which were probably at the foundation of their
success. We will concentrate on mathematical aspects of their design and
history of their construction. It is rather difficult to cover 25 years of the
research in a single talk. That is why, I have organized my presentation around
Monte Carlo PHOTOS but stressing its relation to other activities and projects
often realized together with Prof. Jadach. Many of omitted aspects will find
their way into other perentations collected in this volume.
  I will concentrate on issues related to phasespace parametrization and spin
amplitudes as used in our Monte Carlo programs such as MUSTRAAL, TAUOLA or KKMC
and their similarities and differences with respect to solution used in PHOTOS.


title:
Color Profiles of Spiral Galaxies: Clues on Outer-Disk Formation
  Scenarios

abstract:
  We have explored radial color and stellar surface mass density profiles for a
sample of 85 late-type spiral galaxies with deep (down to ~27 mag arcsec^-2)
SDSS g'- and r'-band surface brightness profiles. About 90% of the light
profiles have been classified as broken exponentials, exhibiting either
truncations (Type II galaxies) or antitruncations (Type III galaxies). The
color profiles of Type II galaxies show a "U shape" with a minimum of (g' - r')
= 0.47 +- 0.02 mag at the break radius. Around the break radius, Type III
galaxies have a plateau region with a color of (g' - r') = 0.57 +- 0.02. Using
the color to calculate the stellar surface mass density profiles reveals a
surprising result. The breaks, well established in the light profiles of the
truncated galaxies, are almost gone, and the mass profiles resemble now those
of the pure exponential (Type I) galaxies. This result suggests that the origin
of the break in Type II galaxies is more likely due to a radial change in
stellar population than being associated to an actual drop in the distribution
of mass. Type III galaxies, however, seem to preserve their shape in the
stellar mass density profiles. We find that the stellar surface mass density at
the break for truncated galaxies is 13.6 +- 1.6 Msun pc^-2 and for the
antitruncated ones is 9.9 +- 1.3 Msun pc^-2 . We estimate that the fraction of
stellar mass outside the break radius is ~15% for truncated galaxies and ~9%
for antitruncated galaxies.


title: Formal analogies between gravitation and electrodynamics

abstract:
  We develop a theoretical framework that allows us to compare electromagnetism
and gravitation in a fully covariant way. This new scenario does not rely on
any kind of approximation nor associate objects with different operational
meaning as it's sometime done in the literature. We construct the
electromagnetic analogue to the Riemann and Weyl tensors and develop the
equations of motion for these objects. In particular, we are able to identify
precisely how and in what conditions gravity can be mapped to electrodynamics.
As a consequence, many of the gemometrical tools of General Relativity can be
applied to Electromagnetism and vice-versa. We hope our results would shed new
light in the nature of electromagnetic and gravitational theories.


title: Low Temperature Transport in Undoped Mesoscopic Structures

abstract:
  Using high quality undoped GaAs/AlGaAs heterostructures with optically
patterned insulation between two layers of gates, it is possible to investigate
very low density mesoscopic regions where the number of impurities is well
quantified. Signature appearances of the scattering length scale arise in
confined two dimensional regions, where the zero-bias anomaly (ZBA) is also
observed. These results explicitly outline the molecular beam epitaxy growth
parameters necessary to obtain ultra low density large two dimensional regions
as well as clean reproducible mesoscopic devices.


title:
Parametric representation of a translation-invariant renormalizable
  noncommutative model

abstract:
  We construct here the parametric representation of a translation-invariant
renormalizable scalar model on the noncommutative Moyal space of even dimension
$D$. This representation of the Feynman amplitudes is based on some integral
form of the noncommutative propagator. All types of graphs (planar and
non-planar) are analyzed. The r\^ole played by noncommutativity is explicitly
shown. This parametric representation established allows to calculate the power
counting of the model. Furthermore, the space dimension $D$ is just a parameter
in the formulas obtained. This paves the road for the dimensional
regularization of this noncommutative model.


title: Group infall of substructures on to a Milky Way-like dark halo

abstract:
  We report the discovery that substructures/subhaloes of a galaxy-size halo
tend to fall in together in groups in cosmological simulations, something that
may explain the oddity of the MW satellite distribution. The original
clustering at the time of infall is still discernible in the angular momenta of
the subhaloes even for events which took place up to eight Gyrs ago, $z \sim
1$. This phenomenon appears to be rather common since at least 1/3 of the
present-day subhaloes have fallen in groups in our simulations. Hence, this may
well explain the Lynden-Bell & Lynden-Bell ghostly streams. We have also found
that the probability of building up a flattened distribution similar to the MW
satellites is as high as $\sim 80%$ if the MW satellites were from only one
group and $\sim 20%$ when five groups are involved. Therefore, we conclude that
the `peculiar' distribution of satellites around the MW can be expected with
the CDM structure formation theory. This non-random assignment of satellites to
subhaloes implies an environmental dependence on whether these low-mass objects
are able to form stars, possibly related to the nature of reionization in the
early Universe.


title: Codistances of 3-spherical buildings

abstract:
  We show that a 3-spherical building in which each rank 2 residue is connected
far away from a chamber, and each rank 3 residue is simply 2-connected far away
from a chamber, admits a twinning (i.e., is one half of a twin building) as
soon as it admits a codistance, i.e., a twinning with a single chamber.


title: NICMOS Spectrophotometry and Models for A-Stars

abstract:
  Absolute flux distributions for eight stars are well measured from 0.8-2.5mu
m with NICMOS grism spectrophotometry at a resolution of R~100 and an accuracy
of 1-2%. These SEDs are fit with Castelli & Kurucz model atmospheres; and the
results are compared with the Cohen-Walker-Witteborn (CWW) template models for
the same stars. In some cases, the T_{eff}, log g, and log z parameters of the
best fitting model differ by up to 1000 K from the earlier CWW model. However,
differences in the continua of the modeled IR flux distributions from 0.4-40mu
m are always less than the quoted CWW uncertainty of 5% because of compensating
changes in the measured extinction. At wavelengths longward of the 2.5mu m
NICMOS limit, uncertainties still approach 5%, because A-star models are not
yet perfect. All of these A stars lie in the JWST continuous viewing zone and
will be important absolute flux standards for the 0.8-30mu m JWST wavelength
range.


title:
Controlling entanglement sudden death in cavity QED by classical driving
  fields

abstract:
  We investigate the entanglement dynamics of a quantum system consisting of
two-level atoms interacting with vacuum or thermal fields with classical
driving fields. We find that the entanglement of the system can be improved by
adjusting the classical driving field. The influence of the classical field and
the purity of the initial state on the entanglement sudden death is also
studied. It is shown that the time of entanglement sudden death can be
controlled by the classical driving fields. Particularly, the entanglement
sudden death phenomenon will disappear if the classical driving fields are
strong enough.


title:
The Bifurcation Theory of Magnetic Monopoles in a Charged Two-Condensate
  Bose-Einstein System

abstract:
  Magnetic monopoles, that are particle-like field configurations with which
one can associate a topological charge, widely exist in various three
dimensional condensate systems. In this paper, by making use of \emph{Duan}'s
topological current theory, we obtain the charge density of magnetic monopoles
and their bifurcation theory in a charged two condensate Bose-Einstein system.
The evolution of magnetic monopoles is studied from the topological properties
of a three-dimensional vector field. The magnetic monopoles are found
generating or annihilating at the limit points and encountering, splitting, or
merging at the bifurcation points.


title:
Pair Production Beyond the Schwinger Formula in Time-Dependent Electric
  Fields

abstract:
  We investigate electron-positron pair production in pulse-shaped electric
background fields using a non-Markovian quantum kinetic equation. We identify a
pulse-length range for subcritical fields still in the nonperturbative regime
where the number of produced pairs significantly exceeds that of a naive
expectation based on the Schwinger formula. From a conceptual viewpoint, we
find a remarkable quantitative agreement between the (real-time) quantum
kinetic approach and the (imaginary-time) effective action approach.


title: On the connectedness of Deligne-Lusztig varieties

abstract:
  We give a criterion which determines when a union of one-dimensional
Deligne-Lusztig varieties has a connected closure. We also obtain a new, short
proof of the connectedness criterion for Deligne-Lusztig varieties due to
Lusztig.


title:
Ab initio study of element segregation and oxygen adsorption on PtPd and
  CoCr binary alloy surfaces

abstract:
  The segregation behavior of the bimetallic alloys PtPd and CoCr in the case
of bare surfaces and in the presence of an oxygen ad-layer has been studied by
means of first-principles modeling based on density-functional theory (DFT).
For both systems, change of the d-band filling due to charge transfer between
the alloy components, resulting in a shift of the d-band center of surface
atoms compared to the pure components, drives the surface segregation and
governs the chemical reactivity of the bimetals. In contrast to previous
findings but consistent with analogous PtNi alloy systems, enrichment of Pt
atoms in the surface layer and of Pd atoms in the first subsurface layer has
been found in Pt-rich PtPd alloy, despite the lower surface energy of pure Pd
compared to pure Pt. Similarly, Co surface and Cr subsurface segregation occurs
in Co-rich CoCr alloys. However, in the presence of adsorbed oxygen, Pd and Cr
occupy preferentially surface sites due to their lower electronegativity and
thus stronger oxygen affinity compared to Pt and Co, respectively. In either
cases, the calculated oxygen adsorption energies on the alloy surfaces are
larger than on the pure components when the more noble components are present
in the subsurface layers.


title: Transverse depinning in weakly-pinned vortices

abstract:
  We present experiments on weakly-pinned vortices, which exhibit a large
critical transverse depinning force. These results are obtained in the
superconducting metallic glasses Fe$_{x}$Ni$_{1-x}$Zr$_{2}$ using crossed ac
and dc driving currents. We study the vortex depinning force due to the
transverse ac drive as a function of a longitudinal dc drive; the ac/dc
combination permits the separation of the transverse drive from the
longitudinal one. We show that the force required for depinning in the
transverse direction is greatly enhanced by the longitudinal drive, which
demonstrates the existence of a large transverse critical force. The
measurements are performed as a function of magnetic field and temperature and
show that the transverse critical force exists in a large portion of the phase
diagram. Hysteresis observed at the transverse depinning threshold is
consistent with a first-order transverse depinning transition.


title:
Structure of Quasiparticles and Their Fusion Algebra in Fractional
  Quantum Hall States

abstract:
  It was recently discovered that fractional quantum Hall (FQH) states can be
classified by the way ground state wave functions go to zero when electrons are
brought close together. Quasiparticles in the FQH states can be classified in a
similar way, by the pattern of zeros that result when electrons are brought
close to the quasiparticles. In this paper we combine the pattern-of-zero
approach and the conformal-field-theory (CFT) approach to calculate the
topological properties of quasiparticles. We discuss how the quasiparticles in
FQH states naturally form representations of a magnetic translation algebra,
with members of a representation differing from each other by Abelian
quasiparticles. We find that this structure dramatically simplifies topological
properties of the quasiparticles, such as their fusion rules, charges, and
scaling dimensions, and has consequences for the ground state degeneracy of FQH
states on higher genus surfaces. We find constraints on the pattern of zeros of
quasiparticles that can fuse together, which allow us to obtain the fusion
rules of quasiparticles from their pattern of zeros, at least in the case of
the (generalized and composite) parafermion states. We also calculate from CFT
the number of quasiparticle types in the generalized and composite parafermion
states, which confirm the result obtained previously through a completely
different approach.


title:
One-loop graviton corrections to the curvature perturbation from
  inflation

abstract:
  We compute one-loop corrections to the power spectrum of the curvature
perturbation in single-field slow-roll inflation arising from gravitons and
inflaton interactions. The quantum corrections due to gravitons to the power
spectrum of the inflaton field are computed around the time of horizon crossing
and their effect on the curvature perturbation is obtained on superhorizon
scales through the delta-N formalism. We point out that one-loop corrections
from the tensor modes are of the same magnitude as those coming from scalar
self-interactions, therefore they cannot be neglected in a self-consistent
calculation.


title:
Using an old method of Jacobi to derive Lagrangians: a nonlinear
  dynamical system with variable coefficients

abstract:
  We present a method devised by Jacobi to derive Lagrangians of any
second-order differential equation: it consists in finding a Jacobi Last
Multiplier. We illustrate the easiness and the power of Jacobi's method by
applying it to the same equation studied by Musielak et al. with their own
method [Musielak ZE, Roy D and Swift LD. Method to derive Lagrangian and
Hamiltonian for a nonlinear dynamical system with variable coefficients. Chaos,
Solitons & Fractals, 2008;58:894-902]. While they were able to find one
particular Lagrangian after lengthy calculations, Jacobi Last Multiplier method
yields two different Lagrangians (and many others), of which one is that found
by Musielak et al, and the other(s) is(are) quite new.


title: Electrovacuum Static Counterrotating Relativistic Dust Disks

abstract:
  A detailed study is presented of the counterrotating model (CRM) for generic
electrovacuum static axially symmetric relativistic thin disks without radial
pressure. We find a general constraint over the counterrotating tangential
velocities needed to cast the surface energy-momentum tensor of the disk as the
superposition of two counterrotating charged dust fluids. We also find explicit
expressions for the energy densities, charge densities and velocities of the
counterrotating fluids. We then show that this constraint can be satisfied if
we take the two counterrotating streams as circulating along electro-geodesics.
However, we show that, in general, it is not possible to take the two
counterrotating fluids as circulating along electro-geodesics nor take the two
counterrotating tangential velocities as equal and opposite. Four simple
families of models of counterrotating charged disks based on Chazy-Curzon-like,
Zipoy-Voorhees-like, Bonnor-Sackfield-like and Kerr-like electrovacuum
solutions are considered where we obtain some disks with a CRM well behaved.
The models are constructed using the well-known ``displace, cut and reflect''
method extended to solutions of vacuum Einstein-Maxwell equations.


title: Periodic orbits in the logarithmic potential

abstract:
  Analytic methods to investigate periodic orbits in galactic potentials. To
evaluate the quality of the approximation of periodic orbits in the logarithmic
potential constructed using perturbation theory based on Hamiltonian normal
forms. The solutions of the equations of motion corresponding to periodic
orbits are obtained as series expansions computed by inverting the normalizing
canonical transformation. To improve the convergence of the series a
resummation based on a continued fraction may be performed. This method is
analogous to that looking for approximate rational solutions (Prendergast
method). It is shown that with a normal form truncated at the lowest order
incorporating the relevant resonance it is possible to construct quite accurate
solutions both for normal modes and periodic orbits in general position.


title: Heavy-quark pair production at two loops in QCD

abstract:
  We present updated predictions for the total cross section of top-quark pair
production at Tevatron and LHC. For the LHC we also provide results at sqrt(s)
= 10 TeV, in view of the anticipated run in 2008 and quote numbers for the
production of new heavy-quark pairs with mass in the range 0.5 - 2 TeV. Our
two-loop results incorporate all logarithmically enhanced terms near threshold
including Coulomb corrections as well as the exact dependence on the
renormalization and factorization scale through next-to-next-to-leading order
in QCD.


title: Mie, Einstein and the Poynting-Robertson effect

abstract:
  A paradox associated with the astrophysical Poynting-Robertson effect is
presented. The paradox arises when relativity theory and Mie's solution of
Maxwell's equations are confronted with the statements on the
Poynting-Robertson effect. Although the relevant physics has been known already
for a century (Poynting 1903, Einstein 1905, Mie 1908), nobody has been aware
of the inconsistency between the theories.


title: An old Method of Jacobi to find Lagrangians

abstract:
  In a recent paper by Ibragimov [N. H. Ibragimov, Invariant Lagrangians and a
new method of integration of nonlinear equations, J. Math. Anal. Appl. 304
(2005) 212--235] a method was presented in order to find Lagrangians of certain
second-order ordinary differential equations admitting a two-dimensional Lie
symmetry algebra. We present a method devised by Jacobi which enables to derive
(many) Lagrangians of any second-order differential equation. The method is
based on the search of the Jacobi Last Multipliers of the equations. We
exemplify the simplicity and elegance of Jacobi's method by applying it to the
same two equations as did Ibragimov. We show that the Lagrangians obtained by
Ibragimov are particular cases of some of the many Lagrangians that can be
obtained by Jacobi's method.


title:
Weak-strong uniqueness for the isentropic compressible Navier-Stokes
  system

abstract:
  We prove weak-strong uniqueness results for the isentropic compressible
Navier-Stokes system on the torus. In other words, we give conditions on a
strong solution so that it is unique in a class of weak solutions. Known
weak-strong uniqueness results are improved. Classical uniqueness results for
this equation follow naturally.


title:
Luminosity-Diameter Relations for Globular Clusters and Dwarf Spheroidal
  Galaxies

abstract:
  It is shown that globular clusters and the dwarf spheroidal companions of the
Galaxy have a different distribution of flattening values, and appear to occupy
adjacent regions of the M_v versus log R_h plane that can be separated by what
will be referred to as the Shapley line. Surprisingly, typical dwarf spheroidal
companions to the Milky Way System are fainter than the average Galactic
globular cluster.


title: HeII Reionization and its Effect on the IGM

abstract:
  Observations of the intergalactic medium (IGM) suggest that quasars reionize
HeII in the IGM at z ~ 3. We have run a set of 190 and 430 comoving Mpc
simulations of HeII being reionized by quasars to develop an understanding of
the nature of HeII reionization and its potential impact on observables. We
find that HeII reionization heats regions in the IGM by as much as 25,000 K
above the temperature that is expected otherwise, with the volume-averaged
temperature increasing by ~ 12,000 K and with large temperature fluctuations on
~ 50 Mpc scales. Much of the heating occurs far from QSOs by hard photons. We
find a temperature-density equation of state of gamma -1 ~ 0.3 during HeII
reionization, but with a wide dispersion in this relation having sigma ~ 10^4
K. HeII reionization by the observed population of quasars cannot produce an
inverted relation (gamma - 1 < 0). Our simulations are consistent with the
observed evolution in the mean transmission of the HeII Ly-alpha forest. We
argue that the heat input due to HeII reionization is unable to cause the
observed depression at z = 3.2 in the HI Ly-alpha forest opacity as has been
suggested. We investigate how uncertainties in the properties of QSOs and of
HeII Lyman-limit systems influence our predictions.


title:
The effect of Magnetic Field on MQT Escape Time in "Small" Josephson
  Junctions

abstract:
  We study the phenomenon of macroscopic quantum tunneling (MQT) in a finite
size Josephson junction (JJ) with an externally applied magnetic field. As it
is well known, the problem of MQT in a point-like JJ is reduced to the study of
the under-barrier motion of a quantum particle in the washboard potential. In
the case of a finite size JJ placed in magnetic field, this problem is
considerably more complex since, besides the phase, the potential itself,
depends on space variables. We find the general expressions both for the
crossover temperature $T_{0}$ between thermally activated and macroscopic
quantum tunneling regimes and the escape time $\tau_{\mathrm{esc}}$. It turns
out that in proximity of particular values of magnetic field the crossover
temperature can vary non-monotonically.


title:
Opportunities for Neutrino Physics at the Spallation Neutron Source
  (SNS)

abstract:
  In this paper we discuss opportunities for a neutrino program at the
Spallation Neutrons Source (SNS) being commissioning at ORNL. Possible
investigations can include study of neutrino-nuclear cross sections in the
energy rage important for supernova dynamics and neutrino nucleosynthesis,
search for neutrino-nucleus coherent scattering, and various tests of the
standard model of electro-weak interactions.


title:
A novel large-volume Spherical Detector with Proportional Amplification
  read-out

abstract:
  A new type of radiation detector based on a spherical geometry is presented.
The detector consists of a large spherical gas volume with a central electrode
forming a radial electric field. Charges deposited in the conversion volume
drift to the central sensor where they are amplified and collected. We
introduce a small spherical sensor located at the center acting as a
proportional amplification structure. It allows high gas gains to be reached
and operates in a wide range of gas pressures. Signal development and the
absolute amplitude of the response are consistent with predictions. Sub-keV
energy threshold with good energy resolution is achieved. This new concept has
been proven to operate in a simple and robust way and allows reading large
volumes with a single read-out channel. The detector performance presently
achieved is already close to fulfill the demands of many challenging projects
from low energy neutrino physics to dark matter detection with applications in
neutron, alpha and gamma spectroscopy.


title:
Preliminary Results on HAT-P-4, TrES-3, XO-2, and GJ 436 from the NASA
  EPOXI Mission

abstract:
  EPOXI (EPOCh + DIXI) is a NASA Discovery Program Mission of Opportunity using
the Deep Impact flyby spacecraft. The EPOCh (Extrasolar Planet Observation and
Characterization) Science Investigation will gather photometric time series of
known transiting exoplanet systems from January through August 2008. Here we
describe the steps in the photometric extraction of the time series and present
preliminary results of the first four EPOCh targets.


title:
Co-existing chiral and collinear phases in a distorted triangular
  antiferromagnet

abstract:
  The entire magnetic phase diagram of the quasi two dimensional (2D) magnet on
a distorted triangular lattice KFe(MoO4)2 is outlined by means of
magnetization, specific heat, and neutron diffraction measurements. It is found
that the spin network breaks down into two almost independent magnetic
subsystems. One subsystem is a collinear antiferromagnet that shows a simple
spin-flop behavior in applied fields. The other is a helimagnet that instead
goes through a series of exotic commensurate-incommensurate phase
transformations. In the various phases one observes either true 3D order or
quasi-2D order. The experimental findings are compared to theoretical
predictions found in literature


title: The Micromechanics of Three Dimensional Collagen-I Gels

abstract:
  We study the micromechanics of collagen-I gel with the goal of bridging the
gap between theory and experiment in the study of biopolymer networks.
Three-dimensional images of fluorescently labeled collagen are obtained by
confocal microscopy and the network geometry is extracted using a 3d network
skeletonization algorithm. Each fiber is modeled as a worm-like-chain that
resists stretching and bending, and each cross-link is modeled as torsional
spring. The stress-strain curves of networks at three different densities are
compared to rheology measurements. The model shows good agreement with
experiment, confirming that strain stiffening of collagen can be explained
entirely by geometric realignment of the network, as opposed to entropic
stiffening of individual fibers. The model also suggests that at small strains,
cross-link deformation is the main contributer to network stiffness whereas at
large strains, fiber stretching dominates. Since this modeling effort uses
networks with realistic geometries, this analysis can ultimately serve as a
tool for understanding how the mechanics of fibers and cross-links at the
microscopic level produce the macroscopic properties of the network. While the
focus of this paper is on the mechanics of collagen, we demonstrate a framework
that can be applied to many biopolymer networks.


title: Phase space descriptions for simplicial 4d geometries

abstract:
  Starting from the canonical phase space for discretised (4d) BF-theory, we
implement a canonical version of the simplicity constraints and construct phase
spaces for simplicial geometries. Our construction allows us to study the
connection between different versions of Regge calculus and approaches using
connection variables, such as loop quantum gravity. We find that on a fixed
triangulation the (gauge invariant) phase space associated to loop quantum
gravity is genuinely larger than the one for length and even area Regge
calculus. Rather, it corresponds to the phase space of area-angle Regge
calculus, as defined by Dittrich and Speziale in [arXiv:0802.0864] (prior to
the imposition of gluing constraints, that ensure the metricity of the
triangulation). We argue that this is due to the fact that the simplicity
constraints are not fully implemented in canonical loop quantum gravity.
Finally, we show that for a subclass of triangulations one can construct first
class Hamiltonian and Diffeomorphism constraints leading to flat 4d
space-times.


title:
Evidence of a first-order quantum phase transition of excitons in
  electron double layers

abstract:
  Complexity in many-particle systems occurs through processes of qualitative
differentiation. These are described by concepts such as emerging states with
specific symmetries that are linked to order parameters. In quantum Hall phases
of electrons in semiconductor double layers with large inter-layer electron
correlation there is an emergent many body exciton phase with an order
parameter that measures the condensate fraction of excitons across the
tunneling gap. As the inter-layer coupling is reduced by application of an
in-plane magnetic field, this excitonic insulating state is brought in
competition with a Fermi-metal phase of composite fermions (loosely, electrons
with two magnetic flux quanta attached) stabilized by intra-layer electron
correlation. Here we show that the quantum phase transformation between
metallic and excitonic insulating states in the coupled bilayers becomes
discontinuous (first-order) by impacts of different terms of the
electron-electron interactions that prevail on weak residual disorder. The
evidence is based on precise determinations of the excitonic order parameter by
inelastic light scattering measurements close to the phase boundary. While
there is marked softening of low-lying excitations, our experiments underpin
the roles of competing orders linked to quasi-particle correlations in removing
the divergence of quantum fluctuations.


title:
Emergent diffeomorphism invariance in a discrete loop quantum gravity
  model

abstract:
  Several approaches to the dynamics of loop quantum gravity involve
discretizing the equations of motion. The resulting discrete theories are known
to be problematic since the first class algebra of constraints of the continuum
theory becomes second class upon discretization. If one treats the second class
constraints properly, the resulting theories have very different dynamics and
number of degrees of freedom than those of the continuum theory. It is
therefore questionable how these theories could be considered a starting point
for quantization and the definition of a continuum theory through a continuum
limit. We show explicitly in a model that the {\em uniform discretizations}
approach to the quantization of constrained systems overcomes these
difficulties. We consider here a simple diffeomorphism invariant one
dimensional model and complete the quantization using {\em uniform
discretizations}. The model can be viewed as a spherically symmetric reduction
of the well known Husain--Kucha\v{r} model of diffeomorphism invariant theory.
We show that the correct quantum continuum limit can be satisfactorily
constructed for this model. This opens the possibility of treating 1+1
dimensional dynamical situations of great interest in quantum gravity taking
into account the full dynamics of the theory and preserving the space-time
covariance at a quantum level.


title: Zariski decomposition of b-divisors

abstract:
  Based on a recent work by Thomas Bauer reproving the existence of Zariski
decompositions for surfaces, we construct a b-divisorial analogue of Zariski
decomposition in all dimensions.


title: Boundaries for Banach spaces determine weak compactness

abstract:
  A boundary for a Banach space is a subset of the dual unit sphere with the
property that each element of the Banach space attains its norm on an element
of that subset. Trivially, the pointwise convergence with respect to such a
boundary is coarser than the weak topology on the Banach space. Godefroy's
Boundary Problem asks whether nevertheless both topologies have the same
bounded compact sets. This paper contains the answer in the positive.


title: Phase Transition on The Degree Sequence of a Mixed Random Graph Process

abstract:
  This paper focuses on the problem of the degree sequence for a mixed random
graph process which continuously combines the {\it classical} model and the BA
model. Note that the number of step added edges for the mixed model is random
and non-uniformly bounded. By developing a comparing argument, phase transition
on the degree distributions of the mixed model is revealed: while the {\it
pure} classical model possesses a {\it exponential} degree sequence, the {\it
pure} BA model and the mixed model possess {\it power law} degree sequences. As
an application of the methodology, phase transition on the degree sequence of
{\it another} mixed model with {\it hard copying} is also studied, especially,
in the power law region, the inverse power can take any value greater than 1.


title: Play Ground for Victor's Magic Squares

abstract:
  This article presents a new development of magic squares with a simple set
up.


title:
Symmetry of standing waves generated by a point defect in epitaxial
  graphene

abstract:
  Using scanning tunneling microscopy (STM) and Fourier Transform STM (FT-STM),
we have studied a point defect in an epitaxial graphene sample grown on silicon
carbide substrate. This analysis allows us to extract the quasiparticle energy
dispersion, and to give a first experimental proof of the validity of Fermi
liquid theory in graphene for a wide range of energies from -800 meV to +800
meV. We also find evidence of a strong threefold anisotropy in the standing
waves generated by the defect. We discuss possible relations between this
anisotropy, the chirality of the electrons, and the asymmetry between
graphene's two sublattices. All experimental measurements are compared and
related to theoretical T-matrix calculations.


title: Latest Results from HiRes

abstract:
  HiRes has made the first statistically significant observation of the
Griessen-Zatsepin-Kuzmin suppression, by fitting the ultra high energy cosmic
ray spectrum observed in monocular mode by the two HiRes detectors to a broken
power law model. We find the break to be at an energy of $5.6\times10^{19}$ eV,
with a significance of $5.3\sigma$;. The significance is determined by Poisson
statistics where we expect 43.2 events above the break point, but observe only
13. We have also looked for correlations between HiRes stereo events and active
galactic nuclei. We observe no statistically significant correlation in a
number of different tests. We have performed a search for upward going showers,
which would be indicative of neutrinos propagating through the Earth and
interacting just below the surface. Observing no such events, we set a limit on
the electron neutrino flux. This limit is significantly lower in this topology
than limits on the other types of neutrinos due to the LPM effect greatly
increasing the available target mass for neutrino interactions. Finally we look
forward to improving these and other results in our work in the Telescope
Array.


title: Permutation classes of every growth rate above 2.48188

abstract:
  We prove that there are permutation classes (hereditary properties of
permutations) of every growth rate (Stanley-Wilf limit) at least \lambda
\approx 2.48187, the unique real root of x^5-2x^4-2x^2-2x-1, thereby
establishing a conjecture of Albert and Linton.


title:
Comparison of three different self-interaction corrections for an
  exactly solvable model system

abstract:
  A systematic comparison of three approximate self-interaction corrections
(SICs), Perdew-Zunger SIC, Lundin-Eriksson SIC and extended Fermi-Amaldi SIC,
is performed for a model Hamiltonian whose exact many-body solution and exact
local-density approximation (LDA) are known. For each of the three proposals we
compare its implementation only for the potential, only for the energy, i.e., a
post-LDA evaluation of the SIC energy), to none of them, i.e., a standard LDA
calculation) and to both. Each of the resulting 10 permutations of
methodologies is applied to 420 Hubbard chains differing in size, particle
number and interaction strength. A statistical analysis of the resulting data
set reveals trends and permits to assess the performance of each methodology.
Overall, but not in each individual case, a post-LDA application of
Perdew-Zunger SIC emerges as the recommended methodology.


title: Dynamics of D3-D7 Brane Inflation in Throats

abstract:
  Dynamics of D3-branes in models of warped D3-D7 inflationary set up is
studied where perturbative $\alpha'$ correction to the K\"ahler potential and
the nonperturbative corrections to the superpotential are included. It is shown
that a dS minimum can be obtained without introducing anti-branes. Some
specific configurations of D7-branes embedding were studied. After stabilizing
the angular directions, it is shown that the resulting D3-D7 potential of the
radial position of the D3-brane is too steep to allow slow-roll inflation.
Depending on D7-branes embedding and the stabilized angular directions, the
mobile D3-brane can move either towards the tip of the throat or towards the
D7-branes.


title: Trojan Stars in the Galactic Center

abstract:
  We performed, for the first time, the simulation of spiral-in of a star
cluster formed close to the Galactic center (GC) using a fully self-consistent
$N$-body model. In our model, the central super-massive black hole (SMBH) is
surrounded by stars and the star cluster. Not only are the orbits of stars and
the cluster stars integrated self-consistently, but the stellar evolution,
collisions and merging of the cluster stars are also included. We found that an
intermediate-mass black hole (IMBH) is formed in the star cluster and stars
escaped from the cluster are captured into a 1:1 mean motion resonance with the
IMBH. These "Trojan" stars are brought close to the SMBH by the IMBH, which
spirals into the GC due to the dynamical friction. Our results show that, once
the IMBH is formed, it brings the massive stars to the vicinity of the central
SMBH even after the star cluster itself is disrupted. Stars carried by the IMBH
form a disk similar to the observed disks and the core of the cluster including
the IMBH has properties similar to those of IRS13E, which is a compact assembly
of several young stars.


title:
The Degree Sequence of a Scale-Free Random Graph Process with Hard
  Copying

abstract:
  In this paper we consider a simple model of random graph process with {\it
hard} copying as follows: At each time step $t$, with probability $0<\alpha\leq
1$ a new vertex $v_t$ is added and $m$ edges incident with $v_t$ are added in
the manner of {\it preferential attachment}; or with probability $1-\alpha$ an
existing vertex is copied uniformly at random. In this way, while a vertex with
large degree is copied, the number of added edges is its degree and thus the
number of added edges is not upper bounded. We prove that, in the case of
$\alpha$ being large enough, the model possesses a mean degree sequence as $
d_{k}\sim Ck^{-(1+2\alpha)}$, where $d_k$ is the limit mean proportion of
vertices of degree $k$.


title:
Exploring compressed supersymmetry with same-sign top quarks at the
  Large Hadron Collider

abstract:
  In compressed supersymmetry, a light top squark naturally mediates efficient
neutralino pair annihilation to govern the thermal relic abundance of dark
matter. I study the LHC signal of same-sign leptonic top-quark decays from
gluino and squark production, which follows from gluino decays to top plus stop
followed by the stop decaying to a charm quark and the LSP in these models.
Measurements of the numbers of jets with heavy-flavor tags in the same-sign
lepton events can be used to confirm the origin of the signal. Summed
transverse momentum observables provide an estimate of an effective
superpartner mass, which is correlated with the gluino mass. Measurements of
invariant mass endpoints from the visible products of gluino decays do not
allow direct determination of superpartner masses, but can place constraints on
them, including lower bounds on the gluino mass as a function of the top-squark
mass.


title: On the spectroscopic nature of the cool evolved Am star HD151878

abstract:
  Recently, Tiwari, Chaubey, & Pandey (2007) detected the bright component of
the visual binary HD151878 to exhibit rapid photometric oscillations through a
Johnson B filter with a period of 6 min (2.78 mHz) and a high, modulated
amplitude up to 22 mmag peak-to-peak, making this star by far the highest
amplitude roAp star known. As a new roAp star, HD151878 is of additional
particular interest as a scarce example of the class in the northern sky, and
only the second known case of an evolved roAp star - the other being HD 116114.
We used the FIES spectrograph at the Nordic Optical Telescope to obtain high
time resolution spectra at high dispersion to attempt to verify the rapid
oscillations. We show here that the star at this epoch is spectroscopically
stable to rapid oscillations of no more than a few tens of m/s. The
high-resolution spectra furthermore show the star to be of type Am rather than
Ap and we show the star lacks most of the known characteristics for rapidly
oscillating Ap stars. We conclude that this is an Am star that does not pulsate
with a 6-min period. The original discovery of pulsation is likely to be an
instrumental artefact.


title:
Very-High-Energy Gamma Rays from a Distant Quasar: How Transparent Is
  the Universe?

abstract:
  The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a
low-energy threshold, has detected very-high-energy gamma rays from a giant
flare of the distant Quasi-Stellar Radio Source (in short: radio quasar) 3C
279, at a distance of more than 5 billion light-years (a redshift of 0.536). No
quasar has been observed previously in very-high-energy gamma radiation, and
this is also the most distant object detected emitting gamma rays above 50
gigaelectron volts. Since high-energy gamma rays may be stopped by interacting
with the diffuse background light in the universe, the observations by MAGIC
imply a low amount for such light, consistent with that known from galaxy
counts.


title: An Iterative Rejection Sampling Method

abstract:
  In the note we consider an iterative generalisation of the rejection sampling
method. In high energy physics, this sampling is frequently used for event
generation, i.e. preparation of phase space points distributed according to a
matrix element squared $|M|^2$ for a scattering process. In many realistic
cases $|M|^2$ is a complicated multi-dimensional function, so, the standard von
Neumann procedure has quite low efficiency, even if an error reducing
technique, like VEGAS, is applied. As a result of that, many of the $|M|^2$
calculations go to ``waste''. The considered iterative modification of the
procedure can extract more ``unweighted'' events, i.e. distributed according to
$|M|^2$. In several simple examples we show practical benefits of the technique
and obtain more events than the standard von Neumann method, without any extra
calculations of $|M|^2$.


title: Piecewise linear parametrization of canonical bases

abstract:
  We extend the known piecewise linear parametrization of the canonical basis
of the plus part of an enveloping algebra of type ADE to the nonsimplylaced
case.


title: Structure of the Nucleon Spin on the Light Cone

abstract:
  The spin structure of the nucleon is studied in a light-cone description of
the nucleon where the Fock expansion is truncated to consider only valence
quarks. Transverse momentum dependent parton distributions and transverse-spin
densities, defined through the generalized parton distributions in the
impact-parameter space, are investigated as new tools to reveal the spin-spin
and spin-orbit correlations for different quark and nucleon polarizations.


title:
On uniformization of N=2 superconformal and N=1 superanalytic DeWitt
  super-Riemann surfaces

abstract:
  We prove a general uniformization theorem for N=2 superconformal and N=1
superanalytic DeWitt super-Riemann surfaces, showing that in general an N=2
superconformal (resp. N=1 superanalytic) DeWitt super-Riemann surface is N=2
superconformally (resp., N=1 superanalytically) equivalent to a manifold with
transition functions containing no odd functions of the even variable if and
only if a certain cohomology group is trivial, namely the first Cech cohomology
group of the body Riemann surface with coefficients in the sheaf consisting of
the reciprocal of a line bundle tensor the holomorphic vector fields over the
body. In particular, this gives a general criteria for when a DeWitt N=1
superanalytic super-Riemann surface is N=1 superanalytically equivalent to a
ringed-space (1,1)-supermanifold, as studied in the algebro-geometric setting.
This general classification result implies there is a countably infinite family
of N=2 superconformal equivalence classes of N=2 superconformal DeWitt
super-Riemann surfaces with genus-zero compact body, and N=2 superconformal
DeWitt super-Riemann surfaces with simply connected body are classified up to
N=2 superconformal equivalence by conformal equivalence classes of holomorphic
line bundles over the underlying body Riemann surface. In addition, N=2
superconformal DeWitt super-Riemann surfaces with compact genus-one body and
transition functions which correspond to the trivial cocycle in the first Cech
cohomology group of the body Riemann surface with coefficients in the
reciprocal of a line bundle tensor the sheaf of holomorphic vector fields over
the body are classified up to N=2 superconformal equivalence by holomorphic
line bundles over the torus modulo conformal equivalence. The corresponding
results for the uniformization of N=1 superanalytic DeWitt super-Riemann
surfaces of genus zero or one are presented.


title:
Approximation properties and entropy estimates for crossed products by
  actions of amenable discrete quantum groups

abstract:
  We construct explicit approximating nets for crossed products of C*-algebras
by actions of discrete quantum groups. This implies that C*-algebraic
approximation properties such as nuclearity, exactness or completely bounded
approximation property are preserved by taking crossed products by actions of
amenable discrete quantum groups. We also show that the noncommutative
topological entropy of a transformation commuting with the quantum group action
does not change when we pass to the canonical extension to the crossed product.
Both these results are extended to twisted crossed products via a stabilisation
trick.


title:
Planetary Migration in Resonance, the question of the Eccentricities :
  Les Houches contribution

abstract:
  The formation of resonant planets pairs in exoplanetary systems involves
planetary migration inside the protoplanetary disc : an inwards migrating outer
planet captures in Mean Motion Resonance an inner planet. During the migration
of the resonant pair of planets, the eccentricities are expected to rise
excessively, if no damping mechanism is applied on the inner planet. We express
the required damping action to match the observations, and we show that the
inner disk can play this role. This result applies for instance to the system
GJ 876 : we reproduce the observed orbital elements through a fully
hydrodynamical simulation of the evolution of the resonant planets.


title:
Congestion Reduction Using Ad hoc Message Dissemination in Vehicular
  Networks

abstract:
  Vehicle-to-vehicle communications can be used effectively for intelligent
transport systems (ITS) and location-aware services. The ability to disseminate
information in an ad-hoc fashion allows pertinent information to propagate
faster through the network. In the realm of ITS, the ability to spread warning
information faster and further is of great advantage to the receivers of this
information. In this paper we propose and present a message-dissemination
procedure that uses vehicular wireless protocols for influencing traffic flow,
reducing congestion in road networks. The computational experiments presented
in this paper show how an intelligent driver model (IDM) and car-following
model can be adapted to 'react' to the reception of information. This model
also presents the advantages of coupling together traffic modelling tools and
network simulation tools.


title:
|V_{cd}|, |V_{cs}| and f_{D_s} from (semi) leptonic $D_{(s)}$-decays :
  signals of New Physics ?

abstract:
  We confront the recent improved measurements of the D_{(s)} (semi) leptonic
decays with lattice QCD (LQCD) with n_f=3 flavours and QCD spectral sum rules
(QSSR) predictions. D\to\mu\nu_\mu leptonic width data compared with
theoretical determinations of f_D, leads to the value of the CKM mixing angle :
|V_cd|= 0.230 (10)_exp (9)_th. Measured ratio of the D semi-leptonic widths
combined with LQCD and QSSR predictions leads to the average |V_cd|/|V_cs|=
0.2175(88), and then to |V_cs|= 1.068(47). We consider the previous
determinations as improvements of the existing estimates. Using the average
data of the D_s\to \mu\nu_\mu (resp. D_s\to \tau\nu_\tau) branching ratios, one
obtains : |V_cs|f_{D_s}^\mu= (259 +- 12) {MeV} (resp) |V_cs|f_{D_s}^\tau= (274
+- 13) {MeV}, which can be compared with the average of the Standard Model (SM)
values from LQCD and QSSR f_{D_s}=(240 +- 7) MeV. If one uses the present
determination of |V_cs|, there is an agreement with the SM prediction within
1\sigma. If instead, we impose the unitarity constraint |V_cs|< 1, or assume
(as frequently done) |V_cs|=|V_ud|, we would obtain a deviation from the SM
expectations ranging from 1.5 to 3 \sigma, eventually signaling some New
Physics beyond the SM.


title: Leo V: A Companion of a Companion of the Milky Way Galaxy

abstract:
  We report the discovery of a new Milky Way dwarf spheroidal galaxy in the
constellation of Leo identified in data from the Sloan Digital Sky Survey. Leo
V lies at a distance of about 180 kpc, and is separated by about 3 degrees from
another recent discovery, Leo IV. We present follow-up imaging from the Isaac
Newton Telescope and spectroscopy from the Hectochelle fiber spectrograph at
the Multiple Mirror Telescope. Leo V's heliocentric velocity is 173.4 km/s,
which is offset by about 40 km/s from that of Leo IV. A simple interpretation
of the kinematic data is that both objects may lie on the same stream, though
the implied orbit is only modestly eccentric (e = 0.2)


title:
Method of Moments Estimation of Ornstein-Uhlenbeck Processes Driven by
  General L\'{e}vy Process

abstract:
  Ornstein-Uhlenbeck processes driven by general L\'{e}vy process are
considered in this paper. We derive strongly consistent estimators for the
moments of the underlying L\'{e}vy process and for the mean reverting parameter
of the Ornstein-Uhlenbeck process. Moreover, we prove that the estimators are
asymptotically normal. Finally, we test the empirical performance of our
estimators in a simulation study and we fit the model to real data.


title:
Anisotropic superconducting properties of aligned
  Sm$_{0.95}$La$_{0.05}$FeAsO$_{0.85}$F$_{0.15}$ microcrystalline powder

abstract:
  The Sm$_{0.95}$La$_{0.05}$FeAsO$_{0.85}$F$_{0.15}$ compound is a quasi-2D
layered superconductor with a superconducting transition temperature T$_c$ = 52
K. Due to the Fe spin-orbital related anisotropic exchange coupling
(antiferromagnetic or ferromagnetic fluctuation), the tetragonal
microcrystalline powder can be aligned at room temperature using the
field-rotation method where the tetragonal $\it{ab}$-plane is parallel to the
aligned magnetic field B$_{a}$ and $\it{c}$-axis along the rotation axis.
Anisotropic superconducting properties with anisotropic diamagnetic ratio
$\chi_{c}/\chi_{ab}\sim$ 2.4 + 0.6 was observed from low field susceptibility
$\chi$(T) and magnetization M(B$_{a}$). The anisotropic low-field phase diagram
with the variation of lower critical field gives a zero-temperature penetration
depth $\lambda_{c}$(0) = 280 nm and $\lambda_{ab}$(0) = 120 nm. The magnetic
fluctuation used for powder alignment at 300 K may be related with the pairing
mechanism of superconductivity at lower temperature.


title: First joint search for gravitational-wave bursts in LIGO and GEO600 data

abstract:
  We present the results of the first joint search for gravitational-wave
bursts by the LIGO and GEO600 detectors. We search for bursts with
characteristic central frequencies in the band 768 to 2048 Hz in the data
acquired between the 22nd of February and the 23rd of March, 2005 (fourth LSC
Science Run - S4). We discuss the inclusion of the GEO600 data in the
Waveburst-CorrPower pipeline that first searches for coincident excess power
events without taking into account differences in the antenna responses or
strain sensitivities of the various detectors. We compare the performance of
this pipeline to that of the coherent Waveburst pipeline based on the maximum
likelihood statistic. This likelihood statistic is derived from a coherent sum
of the detector data streams that takes into account the antenna patterns and
sensitivities of the different detectors in the network. We find that the
coherentWaveburst pipeline is sensitive to signals of amplitude 30 - 50%
smaller than the Waveburst-CorrPower pipeline. We perform a search for
gravitational-wave bursts using both pipelines and find no detection candidates
in the S4 data set when all four instruments were operating stably.


title: Chaotic Diffusion of Resonant Kuiper Belt Objects

abstract:
  We carried out extensive numerical orbit integrations to probe the long-term
chaotic dynamics of the two strongest mean motion resonances of Neptune in the
Kuiper belt, the 3:2 (Plutinos) and 2:1 (Twotinos). Our primary results include
a computation of the relative volumes of phase space characterized by large-
and small-resonance libration amplitudes, and maps of resonance stability
measured by mean chaotic diffusion rate. We find that Neptune's 2:1 resonance
has weaker overall long-term stability than the 3:2 -- only ~15% of Twotinos
are projected to survive for 4 Gyr, compared to ~27% of Plutinos, based on an
extrapolation from our 1-Gyr integrations. We find that Pluto has only a modest
effect, causing a ~4% decrease in the Plutino population that survives to 4
Gyr. Given current observational estimates, and assuming an initial
distribution of particles proportional to the local phase space volume in the
resonance, we conclude that the primordial populations of Plutinos and Twotinos
formerly made up more than half the population of the classical and resonant
Kuiper Belt. We also conclude that Twotinos were originally nearly as numerous
as Plutinos; this is consistent with predictions from early models of smooth
giant planet migration and resonance sweeping of the Kuiper Belt, and provides
a useful constraint for more detailed models.


title:
Ordinateur port\'e support de r\'ealit\'e augment\'ee pour des
  activit\'es de maintenance et de d\'epannage

abstract:
  In this paper we present a case study of use of wearable computer within the
framework of activities of maintenance and repairing. Besides the study of
configuration of this wearable computer and its peripherals, we show the
integration of context, in-situ storage, traceability and regulation in these
activities. This case study is in the scope of a huge project called HMTD (Help
Me To Do) which aim is to apply MOCOCO (Mobility, COoperation,
COntextualisation) and IMERA (Mobile Interaction in the Augmented Real
Environment) principles for better use, maintenance and repairing of equipments
in the domestic, public and professional situations.


title: Variations on a theme of Heisenberg, Pauli and Weyl

abstract:
  The parentage between Weyl pairs, generalized Pauli group and unitary group
is investigated in detail. We start from an abstract definition of the
Heisenberg-Weyl group on the field R and then switch to the discrete
Heisenberg-Weyl group or generalized Pauli group on a finite ring Z_d. The main
characteristics of the latter group, an abstract group of order d**3 noted P_d,
are given (conjugacy classes and irreducible representation classes or
equivalently Lie algebra of dimension d**3 associated with P_d). Leaving the
abstract sector, a set of Weyl pairs in dimension d is derived from a polar
decomposition of SU(2) closely connected to angular momentum theory. Then, a
realization of the generalized Pauli group P_d and the construction of
generalized Pauli matrices in dimension d are revisited in terms of Weyl pairs.
Finally, the Lie algebra of the unitary group U(d) is obtained as a subalgebra
of the Lie algebra associated with P_d. This leads to a development of the Lie
algebra of U(d) in a basis consisting of d**2 generalized Pauli matrices. In
the case where d is a power of a prime integer, the Lie algebra of SU(d) can be
decomposed into d-1 Cartan subalgebras.


title: A Bi-Metric Theory with Exchange Symmetry

abstract:
  We propose an extension of General Relativity with two different metrics. To
each metric we define a Levi-Cevita connection and a curvature tensor. We then
consider two types of fields, each of which moves according to one of the
metrics and its connection. To obtain the field equations for the second metric
we impose an exchange symmetry on the action. As a consequence of this ansatz,
additional source terms for Einstein's field equations are generated. We
discuss the properties of these additional fields, and consider the examples of
the Schwarzschild solution, and the Friedmann-Robertson-Walker metric.


title: Uneven Splitting of Ham Sandwiches

abstract:
  Let m_1,...,m_n be continuous probability measures on R^n and a_1,...,a_n in
[0,1]. When does there exist an oriented hyperplane H such that the positive
half-space H^+ has m_i(H^+)=a_i for all i in [n]? It is well known that such a
hyperplane does not exist in general. The famous ham sandwich theorem states
that if a_i=1/2 for all i, then such a hyperplane always exists.
  In this paper we give sufficient criteria for the existence of H for general
a_i in [0,1]. Let f_1,...,f_n:S^{n-1}->R^n denote auxiliary functions with the
property that for all i the unique hyperplane H_i with normal v that contains
the point f_i(v) has m_i(H_i^+)=a_i. Our main result is that if
Im(f_1),...,Im(f_n) are bounded and can be separated by hyperplanes, then there
exists a hyperplane H with m_i(H^+)=a_i for all i. This gives rise to several
corollaries, for instance if the supports of m_1,...,m_n are bounded and can be
separated by hyperplanes, then H exists for any choice of a_1,...,a_n in [0,1].
We also obtain results that can be applied if the supports of m_1,...,m_n
overlap.


title: Paired fermionic superfluids with s- and p-wave interactions

abstract:
  This thesis presents theoretical work in s- and p-wave resonantly paired
Fermi gases at zero temperature. In the BEC regime of the wide-resonance s-wave
BCS-BEC crossover, the chemical potential, speed of sound, condensate
depletion, and ground state energy are computed. The quantities are calculated
in a low density approximation. The bosonic scattering length is computed
diagrammatically to be approximately 0.60a with a the fermionic scattering
length, confirming a well-known result. The perturbative approach breaks down
in the intermediate BCS-BEC crossover regime which is not investigated. Quantum
corrections are computed in the low density expansion, and the mass-imbalanced
two-species Fermi gas is investigated. For identical fermions, it is discussed
how p-wave Feshbach resonances naturally fall into two classes of "weak" and
"strong", depending on the short-distance physics. It is shown how bound
fermionic trimers appear in the strongly-resonant superfluid. The appearance of
the trimer under the strengthening of the resonance is investigated, and the
lifetime of p-wave diatomic molecules due to collisional relaxation into
trimers is estimated.


title: The Superconformal Gaugings in Three Dimensions

abstract:
  We show how three-dimensional superconformal theories for any number N <= 8
of supersymmetries can be obtained by taking a conformal limit of the
corresponding three-dimensional gauged supergravity models. The superconformal
theories are characterized by an embedding tensor that satisfies a linear and
quadratic constraint. We analyze these constraints and give the general
solutions for all cases. We find new N = 4,5 superconformal theories based on
the exceptional Lie superalgebras F(4), G(3) and D(2|1;\alpha). Using the
supergravity connection we discuss which massive deformations to expect. As an
example we work out the details for the case of N = 6 supersymmetry.


title:
The sign of electron g-factor in GaAs(1-x)N(x) measured by using the
  Hanle effect

abstract:
  Positive signs of the effective g-factors for free electrons in the
conduction band and electrons localized on deep paramagnetic centers have been
measured in nitrogen dilute alloy GaAs{0.979}N{0.021} at room temperature. The
g-factor signs have been determined from an asymmetry in the depolarization of
edge photoluminescence in a transverse magnetic field (Hanle effect) at the
oblique incidence of the exciting radiation and oblique-angle detection of the
luminescence. The tilted spin polarization of free electrons is induced under
interband absorption of circularly polarized light, and the paramagnetic
centers acquire spin polarization because of spin-dependent capture of free
spin-polarized electrons by these centers. The measured Hanle curve is a
superposition of two lines, narrow and broad, with the widths ~400 G and ~50000
G, arising due to the depolarization of localized and free electrons,
respectively. The magnitude and direction of the asymmetry in the measured
Hanle curve have been found to depend on the partial contributions to the
photoluminecsence from the heavy- and light-hole subbands split by a uniaxial
deformation of the GaAs{1-x}N{x} film grown on a GaAs substrate. We have
extended the theory of optical orientation in order to calculate the excitation
spectrum of the photoelectron tilted-spin polarization and the
circularly-polarized luminescence spectrum taking into account that, in the
strained samples under study, the light-hole subband lies above the heavy-hole
one. The results have further been used to calculate the shape of Hanle curve
as a function of the excitation and registration energies as well as the
incidence and detection angles and to compare the theory with experiment.


title: Virasoro constraints for Kontsevich-Hurwitz partition function

abstract:
  M.Kazarian and S.Lando found a 1-parametric interpolation between Kontsevich
and Hurwitz partition functions, which entirely lies within the space of KP
tau-functions. V.Bouchard and M.Marino suggested that this interpolation
satisfies some deformed Virasoro constraints. However, they described the
constraints in a somewhat sophisticated form of AMM-Eynard equations for the
rather involved Lambert spectral curve. Here we present the relevant family of
Virasoro constraints explicitly. They differ from the conventional continuous
Virasoro constraints in the simplest possible way: by a constant shift u^2/24
of the L_{-1} operator, where u is an interpolation parameter between
Kontsevich and Hurwitz models. This trivial modification of the string equation
gives rise to the entire deformation which is a conjugation of the Virasoro
constraints L_m -> U L_m U^{-1} and "twists" the partition function, Z_{KH}= U
Z_K. The conjugation U is expressed through the previously unnoticed operators
which annihilate the quasiclassical (planar) free energy of the Kontsevich
model, but do not belong to the symmetry group GL(\infty) of the universal
Grassmannian.


title: On the Performance of Selection Relaying

abstract:
  Interest in selection relaying is growing. The recent developments in this
area have largely focused on information theoretic analyses such as outage
performance. Some of these analyses are accurate only at high SNR regimes. In
this paper error rate analyses that are sufficiently accurate over a wide range
of SNR regimes are provided. The motivations for this work are that practical
systems operate at far lower SNR values than those supported by the high SNR
analysis. To enable designers to make informed decisions regarding network
design and deployment, it is imperative that system performance is evaluated
with a reasonable degree of accuracy over practical SNR regimes. Simulations
have been used to corroborate the analytical results, as close agreement
between the two is observed.


title:
Direct observation of a localization transition in quasi-periodic
  photonic lattices

abstract:
  The localization of waves in non-periodic media is a universal phenomenon,
occurring in a variety of different quantum and classical systems, including
condensed-matter, Bose-Einstein condensates in optical lattices, quantum
chaotic systems, sound waves and light. A localization phase transition is
expected to occur in three dimensional disordered systems as the strength of
disorder crosses a critical value. Recently, a crossover from an extended to a
localized phase has been observed in low-dimensional photonic lattices and
Bose-Einstein condensates. Other experiments studied the critical behaviour
near the transition in three dimensions via transmission measurements. However,
no direct observation of a localization transition for light has been reported.
In 1979 Aubry and Andre predicted that for a certain class of quasi-periodic
potentials, a localization phase transition can occur already in one-dimension.
This strongly correlated potential is markedly different from the disordered
case were the potential is uncorrelated. Here we report an experiment that
realizes the Aubry-Andre model in quasi-periodic photonic lattices. We observe
the signature of a localization phase transition by directly measuring the
expansion rates of initially narrow wave packets propagating in the lattice.
Below the transition point, all the modes of the system are extended and
therefore an initially narrow wave-packet eventually spreads across the entire
lattice. Above the critical point, all modes are localized and expansion is
suppressed. In addition, we study the effect of weak nonlinear interactions on
light propagation below and above the transition.


title:
Collapse models with non-white noises II: particle-density coupled
  noises

abstract:
  We continue the analysis of models of spontaneous wave function collapse with
stochastic dynamics driven by non-white Gaussian noise. We specialize to a
model in which a classical "noise" field, with specified autocorrelator, is
coupled to a local nonrelativistic particle density. We derive general results
in this model for the rates of density matrix diagonalization and of state
vector reduction, and show that (in the absence of decoherence) both processes
are governed by essentially the same rate parameters. As an alternative route
to our reduction results, we also derive the Fokker-Planck equations that
correspond to the initial stochastic Schr\"odinger equation. For specific
models of the noise autocorrelator, including ones motivated by the structure
of thermal Green's functions, we discuss the qualitative and qantitative
dependence on model parameters, with particular emphasis on possible
cosmological sources of the noise field.


title: Stable flatness of nonarchimedean hyperenveloping algebras

abstract:
  Let L be a p-adic local field and g a finite dimensional Lie algebra over L.
We show that its hyperenveloping algebra F(g) is a stably flat completion of
its universal enveloping algebra. As a consequence the relative cohomology for
the locally convex algebra F(g) coincides with the underlying Lie algebra
cohomology. Final version. Some minor items corrected. Appeared in Journal of
Algebra (2010).


title:
High pressure behavior of Ga-doped LaMnO_3: a combined X-ray diffraction
  and optical spectroscopy study

abstract:
  The pressure effects on the JT distortion of three representative compounds
belonging to the LaMn_1-xGa_xO_3 (x= 0.2, 0.3, 0.4) family was widely
investigated by means of X-ray diffraction and Raman spectroscopy. A compound
with a fully JT distorted structure (x=0.2), one with regular octahedra (x=0.6)
and one in an intermediate configuration (x=0.3) were selected. A pressure
induced transitions from the orthorhombic Pbnm phase towards structures with
higher symmetry were observed in all the samples. Both Raman and X-ray data
confirm that the most important structural effect of pressure is that of
reducing the octahedral distortion. The appearance of a feature in the lattice
parameter behavior connected to a structural instability was also detected,
pointing out the key role of the JT distortion in stabilizing the manganite
structures. On the other hand, the complete suppression of the JT distortion in
the high-pressure phases cannot be claimed. The Raman spectra collected from
more distorted compounds (x=0.2, 0.3) reveal clearly the coexistence of domains
of distorted and more regular octahedra in a certain pressure range. The first
sketch of the Pressure vs. Ga-content phase diagram was drawn.


title: On a Furstenberg-Katznelson-Weiss type theorem over finite fields

abstract:
  Using Fourier analysis, Covert, Hart, Iosevich and Uriarte-Tuero (2008)
showed that if the cardinality of a subset of the 2-dimensional vector space
over a finite field with q elements is >= rq^2, with q^{-1/2} << r <= 1 then it
contains an isometric copy of >= crq^3 triangles. In this note, we give a graph
theoretic proof of this result.


title:
Comment on Conjugate heat transfer of mixed convection for viscoelastic
  fluid past a stretching sheet, by Hsiao and Chen, Mathematical Problems in
  Engineering

abstract:
  Comment on Conjugate heat transfer of mixed convection for viscoelastic fluid
past a stretching sheet, by Kai-Long Hsiao and Guan-Bang Chen, Mathematical
Problems in Engineering, Volume 2007, article 17058, 21 pages


title:
Production of medium-mass neutron-rich nuclei in reactions induced by
  136Xe projectiles at 1 A GeV on a beryllium target

abstract:
  Production cross sections of medium-mass neutron-rich nuclei obtained in the
fragmentation of 136Xe projectiles at 1 A GeV have been measured with the
FRagment Separator (FRS) at GSI. 125Pd was identified for the first time. The
measured cross sections are compared to 238U fission yields and model
calculations in order to determine the optimum reaction mechanism to extend the
limits of the chart of the nuclides around the r-process waiting point at N=82.


title:
The NASA EPOXI mission of opportunity to gather ultraprecise photometry
  of known transiting exoplanets

abstract:
  The NASA Discovery mission EPOXI, utilizing the Deep Impact flyby spacecraft,
comprises two phases: EPOCh (Extrasolar Planet Observation and
Characterization) and DIXI (Deep Impact eXtended Investigation). With EPOCh, we
use the 30-cm high resolution visible imager to obtain ultraprecise photometric
light curves of known transiting planet systems. We will analyze these data for
evidence of additional planets, via transit timing variations or transits; for
planetary moons or rings; for detection of secondary eclipses and the
constraint of geometric planetary albedos; and for refinement of the system
parameters. Over a period of four months, EPOCh observed four known transiting
planet systems, with each system observed continuously for several weeks. Here
we present an overview of EPOCh, including the spacecraft and science goals,
and preliminary photometry results.


title:
Connecting high-redshift galaxy populations through observations of
  local Damped Lyman Alpha dwarf galaxies

abstract:
  I report on observations of the z=0.01 dwarf galaxy SBS1543+593 which is
projected onto the background QSO HS1543+5921. As a star-forming galaxy first
noted in emission, this dwarf is playing a pivotal role in our understanding of
high-redshift galaxy populations, because it also gives rise to a Damped Lyman
Alpha system. This enabled us to analyze, for the first time, the chemical
abundance of $\alpha$ elements in a Damped Lyman Alpha galaxy using both,
emission and absorption diagnostics. We find that the abundances agree with one
another within the observational uncertainties. I discuss the implications of
this result for the interpretation of high-redshift galaxy observations. A
catalog of dwarf-galaxy--QSO projections culled from the Sloan Digital Sky
Survey is provided to stimulate future work.


title:
Emergence of Particle-Hole Symmetry near Optimal Doping in
  High-Temperature Copper Oxide Superconductors

abstract:
  High-temperature copper oxide superconductors (cuprates) display
unconventional physics when they are lightly doped whereas the standard theory
of metals prevails in the opposite regime. For example, the thermoelectric
power, that is the voltage that develops across a sample in response to a
temperature gradient, changes sign abruptly near optimal doping in a wide class
of cuprates, a stark departure from the standard theory of metals in which the
thermopower vanishes only when one electron exists per site. We show that this
effect arises from proximity to a state in which particle-hole symmetry is
dynamically generated. The operative mechanism is dynamical spectral weight
transfer from states that lie at least 2eV away from the chemical potential. We
show that the sign change is reproduced quantitatively within the Hubbard model
for moderate values of the on-site repulsion, $U$. For sufficiently large
values of on-site repulsion, for example, $U=20t$, ($t$ the hopping matrix
element), dynamical spectral weight transfer attenuates and our calculated
results for the thermopower are in prefect agreement with exact atomic limit.
The emergent particle-hole symmetry close to optimal doping points to pairing
in the cuprates being driven by high-energy electronic states.


title: Gearing Up for Epsilon Aurigae's First Eclipse of the Millennium

abstract:
  The mysterious 3rd magnitude long period eclipsing binary star system epsilon
Aurigae is predicted to be starting its 2 year eclipse in the late summer of
2009. While this is when the real excitement starts, much is to be learned
before first contact. This paper discusses current observational results that
have accumulated thus far, using photometric monitoring, H-alpha spectroscopy
and with other data sources. Key among the findings are that (1) the low
amplitude light variation quasi-period has decreased significantly over the
past 20 years, and (2) that the duration of egress, eclipse-to-eclipse has been
decreasing, while the duration of total eclipse has been increasing. The
website for the observing campaign is: www.du.edu/~rstencel/epsaur.htm .