title: Astrobiological Effects of F, G, K and M Main-Sequence Stars

abstract:
  We focus on the astrobiological effects of photospheric radiation produced by
main-sequence stars of spectral types F, G, K, and M. The photospheric
radiation is represented by using realistic spectra, taking into account
millions or hundred of millions of lines for atoms and molecules. DNA is taken
as a proxy for carbon-based macromolecules, assumed to be the chemical
centerpiece of extraterrestrial life forms. Emphasis is placed on the
investigation of the radiative environment in conservative as well as
generalized habitable zones.


title:
Systematic Numerical Study of the Propagation of Monochromatic Radiation
  through a Stationary Atmosphere in a Model of Plane Plane-Parallel Layers

abstract:
  In this paper, the authors compare the security bounds for different quantum
communication protocols with the numerically evaluated losses in the
transmission channel, due to the interaction between the atmosphere and the
photon, which is the information carrier. The analysis is carried out using a
free-source library, which can solve the radiative transfer equation for a
parallel-plane atmosphere.


title: Electronic properties of bilayer and multilayer graphene

abstract:
  We study the effects of site dilution disorder on the electronic properties
in graphene multilayers, in particular the bilayer and the infinite stack. The
simplicity of the model allows for an easy implementation of the coherent
potential approximation and some analytical results. Within the model we
compute the self-energies, the density of states and the spectral functions.
Moreover, we obtain the frequency and temperature dependence of the
conductivity as well as the DC conductivity. The c-axis response is
unconventional in the sense that impurities increase the response for low
enough doping. We also study the problem of impurities in the biased graphene
bilayer.


title:
Astrobiology in the Environments of Main-Sequence Stars: Effects of
  Photospheric Radiation

abstract:
  We explore if carbon-based macromolecules (such as DNA) in the environments
of stars other than the Sun are able to survive the effects of photospheric
stellar radiation, such as UV-C. Therefore, we focus on main-sequence stars of
spectral types F, G, K, and M. Emphasis is placed on investigating the
radiative environment in the stellar habitable zones. Stellar habitable zones
are relevant to astrobiology because they constitute circumstellar regions in
which a planet of suitable size can maintain surface temperatures for water to
exist in fluid form, thus increasing the likelihood of Earth-type life.


title: Algebraic approximation of analytic sets and mappings

abstract:
  Let {X_n} be a sequence of analytic sets converging to some analytic set X in
the sense of holomorphic chains. We introduce a condition which implies that
every irreducible component of X is the limit of a sequence of irreducible
components of the sets from {X_n}. Next we apply the condition to approximate a
holomorphic solution y=f(x) of a system Q(x,y)=0 of Nash equations by Nash
solutions. Presented methods allow to construct an algorithm of approximation
of the holomorphic solutions.


title:
Structure-dependent exchange in the organic magnets Cu(II)Pc and
  Mn(II)Pc

abstract:
  We study exchange couplings in the organic magnets copper(II) phthalocyanine
(Cu(II)Pc) and manganese(II) phthalocyanine (Mn(II)Pc) by a combination of
Green's function perturbation theory and \textsl{ab initio} density-functional
theory (DFT). Based on the indirect exchange model our perturbation-theory
calculation of Cu(II)Pc qualitatively agrees with the experimental
observations. DFT calculations performed on Cu(II)Pc dimer show a very good
quantitative agreement with exchange couplings that we extract by using a
global fitting for the magnetization measurements to a spin-1/2 Bonner-Fisher
model. These two methods give us remarkably consistent trends for the exchange
couplings in Cu(II)Pc when changing the stacking angles. The situation is more
complex for Mn(II)Pc owing to the competition between super-exchange and
indirect exchange.


title: Dimension and natural parametrization for SLE curves

abstract:
  Some possible definitions for the natural parametrization of SLE
(Schramm-Loewner evolution) paths are proposed in terms of various limits. One
of the definitions is used to give a new proof of the Hausdorff dimension of
SLE paths.


title:
Using Gradual Numbers to Analyze Non-Monotonic Functions of Fuzzy
  Intervals

abstract:
  Gradual numbers have been introduced recently as a means of extending
standard interval computation methods to fuzzy intervals. The literature treats
monotonic functions of fuzzy intervals. In this paper, we combine the concepts
of gradual numbers and optimization, which allows for the evaluation of any
differentiable function on fuzzy intervals, with no monotonicity requirement.


title:
SusyBSG: a fortran code for BR[B -> Xs gamma] in the MSSM with Minimal
  Flavor Violation

abstract:
  We present the fortran code SusyBSG version 1.1, which computes the branching
ratio for the decay B -> Xs gamma in the MSSM with Minimal Flavor Violation.
The computation takes into account all the available NLO contributions,
including the complete supersymmetric QCD corrections to the Wilson
coefficients of the magnetic and chromomagnetic operators.


title: Orbital Stability of Earth-Type Planets in Binary Systems

abstract:
  About half of all known stellar systems with Sun-like stars consist of two or
more stars, significantly affecting the orbital stability of any planet in
these systems. Here we study the onset of instability for an Earth-type planet
that is part of a binary system. Our investigation makes use of previous
analytical work allowing to describe the permissible region of planetary
motion. This allows us to establish a criterion for the orbital stability of
planets that may be useful in the context of future observational and
theoretical studies.


title:
Direct evidence of overdamped Peierls-coupled modes in TTF-CA
  temperature-induced phase transition

abstract:
  In this paper we elucidate the optical response resulting from the interplay
of charge distribution (ionicity) and Peierls instability (dimerization) in the
neutral-ionic, ferroelectric phase transition of tetrathiafulvalene-chloranil
(TTF-CA), a mixed-stack quasi-one-dimensional charge-transfer crystal. We
present far-infrared reflectivity measurements down to 5 cm-1 as a function of
temperature above the phase transition (300 - 82 K). The coupling between
electrons and lattice phonons in the pre-transitional regime is analyzed on the
basis of phonon eigenvectors and polarizability calculations of the
one-dimensional Peierls-Hubbard model. We find a multi-phonon Peierls coupling,
but on approaching the transition the spectral weight and the coupling shift
progressively towards the phonons at lower frequencies, resulting in a
soft-mode behavior only for the lowest frequency phonon near the transition
temperature. Moreover, in the proximity of the phase transition, the
lowest-frequency phonon becomes overdamped, due to anharmonicity induced by its
coupling to electrons. The implications of these findings for the neutral-ionic
transition mechanism is shortly discussed.


title:
Necessary and sufficient detection efficiency for the Mermin
  inequalities

abstract:
  We prove that the threshold detection efficiency for a loophole-free Bell
experiment using an $n$-qubit Greenberger-Horne-Zeilinger state and the
correlations appearing in the $n$-partite Mermin inequality is $n/(2n-2)$. If
the detection efficiency is equal to or lower than this value, there are local
hidden variable models that can simulate all the quantum predictions. If the
detection efficiency is above this value, there is no local hidden variable
model that can simulate all the quantum predictions.


title:
GRB 060607A: A GRB with Bright Asynchronous Early $X$-ray and Optical
  Emissions

abstract:
  The early optical emission of the moderately high redshift ($z=3.08$) GRB
060607A shows a remarkable broad and strong peak with a rapid rise and a
relatively slow power-law decay. It is not coincident with the strong
early-time flares seen in the X-ray and gamma-ray energy bands. There is weak
evidence for variability superposed on this dominant component in several
optical bands that can be related to flares in high energy bands. While for a
small number of GRBs, well-sampled optical flares have been observed
simultaneously with X-ray and gamma ray pulses, GRB 060607A is one of the few
cases where the early optical emission shows no significant evidence for
correlation with the prompt emission. In this work we first report in detail
the broad band observations of this burst by Swift. Then by applying a simple
model for the dynamics and the synchrotron radiation of a relativistic shock,
we show that the dominant component of the early emissions in optical
wavelengths has the same origin as the tail emission produced after the main
gamma ray activity. The most plausible explanation for the peak in the optical
light curve seems to be the cooling of the prompt after the main collisions,
shifting the characteristic synchrotron frequency to the optical bands. It
seems that the cooling process requires a steepening of the electron energy
distribution and/or a break in this distribution at high energies. The sharp
break in the X-ray light curve at few thousands of seconds after the trigger,
is not observed in the IR/optical/UV bands, and therefore can not be a jet
break. Either the X-ray break is due to a change in the spectrum of the
accelerated electrons or the lack of an optical break is due to the presence of
a related delayed response component (Abbreviated).


title: First Observation of Planet-Induced X-ray Emission: The System HD 179949

abstract:
  We present the first observation of planet-induced stellar X-ray activity,
identified for the HD 179949 system, using Chandra / ACIS-S. The HD 179949
system consists of a close-in giant planet orbiting an F9V star. Previous
ground-based observations already showed enhancements in Ca II K in phase with
the planetary orbit. We find an ~30% increase in the X-ray flux over quiescent
levels coincident with the phase of the Ca II enhancements. There is also a
trend for the emission to be hotter at increased fluxes, confirmed by modeling,
showing the enhancement at ~1 keV compared to ~0.4 keV for the background star.


title: Disentanglement of Source and Target and the Laser Quantum State

abstract:
  Disentanglement of a laser source from its target qubit is proposed as a
criterion establishing the laser quantum state as a coherent state. It is shown
that the source-target density operator has a unique factorization in coherent
states when the environmental record monitoring laser pump quanta is ignored.
The source-target state conditioned upon the complete environmental record is
entangled, though, as a state of known total quanta number (source plus
target).


title: Half-Twisted Correlators from the Coulomb Branch

abstract:
  We compute correlators of chiral operators in half-twisted (0,2)
supersymmetric gauged linear sigma models. Our results give simple algebraic
formulas for a (0,2) generalization of genus zero Gromov-Witten invariants of
compact toric varieties. We derive compact expressions for deformed quantum
cohomology relations and apply our general method to several examples.


title:
First Measurement of the Fraction of Top Quark Pair Production Through
  Gluon-Gluon Fusion

abstract:
  We present the first measurement of the fraction of top quark pair production
through gluon-gluon fusion. We use 0.96/fb of s**(1/2)=1.96 TeV p-pbar
collision data recorded with the CDF II detector at Fermilab. We identify the
candidate t-tbar events with a high-energy charged lepton, a neutrino
candidate, and four or more jets. Using charged particles with low transverse
momentum in t-tbar events, we find the fraction of top quark pair production
through gluon-gluon fusion to be 0.07+/-0.14(stat)+/-0.07(syst), corresponding
to a 95% confidence level upper limit of 0.33, in agreement with the standard
model NLO prediction of 0.15+/-0.05.


title: Parameter curves for the regular representations of tame bimodules

abstract:
  We present results and examples which show that the consideration of a
certain tubular mutation is advantageous in the study of noncommutative curves
which parametrize the simple regular representations of a tame bimodule. We
classify all tame bimodules where such a curve is actually commutative, or in
different words, where the unique generic module has a commutative endomorphism
ring. This extends results from [14] to arbitrary characteristic; in
characteristic two additionally inseparable cases occur. Further results are
concerned with autoequivalences fixing all objects but not isomorphic to the
identity functor.


title: Relations between semidualizing complexes

abstract:
  We study the following question: Given two semidualizing complexes B and C
over a commutative noetherian ring R, does the vanishing of Ext^n_R(B,C) for
n>>0 imply that B is C-reflexive? This question is a natural generalization of
one studied by Avramov, Buchweitz, and Sega. We begin by providing conditions
equivalent to B being C-reflexive, each of which is slightly stronger than the
condition Ext^n_R(B,C)=0 for all n>>0. We introduce and investigate an
equivalence relation \approx on the set of isomorphism classes of semidualizing
complexes. This relation is defined in terms of a natural action of the derived
Picard group and is well-suited for the study of semidualizing complexes over
nonlocal rings. We identify numerous alternate characterizations of this
relation, each of which includes the condition Ext^n_R(B,C)=0 for all n>>0.
Finally, we answer our original question in some special cases.


title: Stable skyrmions from extra dimensions

abstract:
  We show that skyrmions arising from compact five dimensional models have
stable sizes. We numerically obtain the skyrmion configurations and calculate
their size and energy. Although their size strongly depends on the magnitude of
localized kinetic-terms, their energy is quite model-independent ranging
between 50-65 times F_pi^2/m_rho, where F_pi is the Goldstone decay constant
and m_rho the lowest Kaluza-Klein mass. These skyrmion configurations
interpolate between small 4D YM instantons and 4D skyrmions made of Goldstones
and a massive vector boson. Contrary to the original 4D skyrmion and previous
5D extensions, these configurations have sizes larger than the inverse of the
cut-off scale and therefore they are trustable within our effective 5D
approach. Such solitonic particles can have interesting phenomenological
consequences as they carry a conserved topological charge analogous to baryon
number.


title:
On the Capacity and Energy Efficiency of Training-Based Transmissions
  over Fading Channels

abstract:
  In this paper, the capacity and energy efficiency of training-based
communication schemes employed for transmission over a-priori unknown Rayleigh
block fading channels are studied. In these schemes, periodically transmitted
training symbols are used at the receiver to obtain the minimum
mean-square-error (MMSE) estimate of the channel fading coefficients.
Initially, the case in which the product of the estimate error and transmitted
signal is assumed to be Gaussian noise is considered. In this case, it is shown
that bit energy requirements grow without bound as the signal-to-noise ratio
(SNR) goes to zero, and the minimum bit energy is achieved at a nonzero SNR
value below which one should not operate. The effect of the block length on
both the minimum bit energy and the SNR value at which the minimum is achieved
is investigated. Flash training and transmission schemes are analyzed and shown
to improve the energy efficiency in the low-SNR regime.
  In the second part of the paper, the capacity and energy efficiency of
training-based schemes are investigated when the channel input is subject to
peak power constraints. The capacity-achieving input structure is characterized
and the magnitude distribution of the optimal input is shown to be discrete
with a finite number of mass points. The capacity, bit energy requirements, and
optimal resource allocation strategies are obtained through numerical analysis.
The bit energy is again shown to grow without bound as SNR decreases to zero
due to the presence of peakedness constraints. The improvements in energy
efficiency when on-off keying with fixed peak power and vanishing duty cycle is
employed are studied. Comparisons of the performances of training-based and
noncoherent transmission schemes are provided.


title:
On geometrical representation of the Jacobian in a path integral
  reduction problem

abstract:
  The geometrical representation of the Jacobian in the path integral reduction
problem which describes a motion of the scalar particle on a smooth compact
Riemannian manifold with the given free isometric action of the compact
semisimple Lie group is obtained. By using the formula for the scalar curvature
of the manifold with the Kaluza--Klein metric, we present the Jacobian as
difference of the scalar curvature of the total space of the principal fibre
bundle and the terms that are the scalar curvature of the orbit space, the
scalar curvature of the orbit, the second fundamental form of the orbit and the
square of the principle fibre bundle curvature.


title: Quantum Pump for Fractional Charge

abstract:
  We propose a theoretical scenario for pumping of fractionally charged
quasi-particle in the context of $\nu=1/3$ fractional quantum Hall liquid. We
consider quasi-particle pumping across an anti-dot level tuned close to the
resonance. Fractional charge pumping is achieved by slow and periodic
modulation of coupling of the anti-dot level to left and right moving edges of
a Hall bar set-up. This is attained by periodically modulating the gate
voltages controlling the couplings. In order to obtain quantization of pumped
charge in the unit of the electronic charge fraction ($\nu e$) per pumping
cycle in the adiabatic limit, we argue that the only possibility is to tune the
quasi-particle operator to be irrelevant from being relevant in the
renormalization group sense, which can be accomplished by invoking quantum Hall
line junctions into the Hall bar geometry. We also comment on possibility for
experimental realization of the above scenario.


title:
The Bose-Fermi Kondo model with a singular dissipative spectrum: Exact
  solutions and their implications

abstract:
  Quantum dissipation induces a critical destruction of a Kondo screened state,
which is of interest in the contexts of quantum critical heavy fermion metals
and magnetic nanostructures. The sub-ohmic Bose-Fermi Kondo model provides a
setting to study this effect. We find that this many-body problem is exactly
solvable when the spectrum of the dissipative bosonic bath, J(\omega), is
singular, corresponding to J(\tau)=const.. We determine the local spin
correlation functions, showing that the singular LONGITUDINAL fluctuations of
the bosonic bath dominate over the transverse ones. Our results provide
evidence that the local quantum critical solution, derived within the extended
dynamical mean field approach to the Kondo lattice model, has a zero residual
entropy.


title:
Bifurcations of Free Thermal Vibrational Convection in Cylindrical Fluid
  Layer in Micro-Gravity: Numerical and Analytical Research

abstract:
  The analysis of vibration effect on non-isothermal fluid in closed cavity is
important for planning technological experiments in space. Control and
optimization of these processes critically depend on the understanding of
liquid response to the vibrations. With this aim the theoretical investigation
for infinite plane and cylindrical fluid layers are performed. We investigated
simple case of the fluid response-thermal vibrational convection in a
cylindrical fluid layer with rigid conducting boundaries. It is found that
steady modes of thermal vibrational convection are subjected to various
bifurcations. Bifurcations cause sharp changes in heat transfer. The Lorenz
model is generalized (GLM) and used to conduct the analysis of bifurcations
caused by the changing of the cavity shape and vibrational Rayleigh number. The
shape of steady-state surface in 3D space of the streamfunction of mean flow,
vibrational Rayleigh number and the cavity curvature is found. The numerical 2D
solution is performed for plane and cylindrical fluid layers. The results of
the analysis based on the GLM model are compared with the data obtained by
direct numerical simulation. The bifurcation curve with extremum is found.
Thus, bifurcations of complex shape could be observed. Comparisons with space
experiments and its discussions are presented.


title: Parton Momentum Distribution at the Moment of Jet-Parton Collision

abstract:
  We extract the early parton momentum distribution using the STAR
Collaboration data of ridge particles associated with a near-side jet in
central AuAu collisions at \sqrt{s_{NN}}=200 GeV. The ridge particles are
identified as medium partons kicked by the jet near the surface and they carry
direct information on the parton momentum distribution at the moment of
jet-parton collisions. The extracted parton momentum distribution has a
thermal-like transverse momentum distribution but a rapidity plateau structure
with a relatively flat rapidity distribution at mid-rapidities with sharp
kinematic boundaries at large rapidities that depend on the transverse
momentum.


title: Complex Organic Materials in the Circumstellar Disk of HR 4796A

abstract:
  We combine HST/NICMOS imaging photometry of the HR 4796A disk at previously
unobserved wavelengths between 1.71-2.22\micron with reprocessed archival
observations to produce a measure of the dust's scattering efficiency as a
function of wavelength. The spectrum of the dust, synthesized from the seven
photometric measures, is characterized by a steep red slope increasing from 0.5
\micron to 1.6 \micron followed by a flattening of the spectrum at wavelengths
$>$ 1.6 \micron. We fit the spectrum with a model population of dust grains
made of tholins, materials comprised of complex organic materials seen
throughout the outer parts of our Solar System. The presence of organic
material around a star that may be in the later stages of giant planet
formation implies that the basic building blocks for life may be common in
planetary systems.


title:
Localized Solutions of the Non-Linear Klein-Gordon Equation in Many
  Dimensions

abstract:
  We present a new complex non-stationary particle-like solution of the
non-linear Klein-Gordon equation with several spatial variables. The
construction is based on reduction to an ordinary differential equation.


title: The role of stellar feedback in the formation of galaxies

abstract:
  We develop a new realistic prescription for modeling the stellar feedback,
which minimizes any ad hoc assumptions about sub-grid physics. We start with
developing high resolution models of the ISM and formulate the conditions
required for its realistic functionality: formation of multi-phase medium with
hot chimneys, super-bubbles, cold molecular phase, and very slow consumption of
gas. Another important ingredient is the runaway stars. They greatly facilitate
the feedback. Once these effects are implemented into cosmological simulations,
we do not have the overcooling problem and the angular momentum problem
(resulting in a too massive bulge) is also reduced substantially: the rotation
curves are nearly flat. Just as it is often observed in QSO absorption lines,
our models produce substantial outflows from forming and active galaxies. At
high redshifts we routinely find gas with few hundred km/s and occasionally
1000-2000 km/s. The density profile of dark matter is still consistent with a
cuspy profile. The simulations reproduce this picture only if the resolution is
very high: better than 50 pc, which is much better than the typical resolution
in previous cosmological simulations. Our simulations of galaxy formation reach
the resolution of 35 pc. (Abridged)


title: Error Rate Analysis for Peaky Signaling over Fading Channels

abstract:
  In this paper, the performance of signaling strategies with high
peak-to-average power ratio is analyzed over both coherent and noncoherent
fading channels. Two modulation schemes, namely on-off phase-shift keying
(OOPSK) and on-off frequency-shift keying (OOFSK), are considered. Initially,
uncoded systems are analyzed. For OOPSK and OOFSK, the optimal detector
structures are identified and analytical expressions for the error
probabilities are obtained for arbitrary constellation sizes. Numerical
techniques are employed to compute the error probabilities. It is concluded
that increasing the peakedness of the signals results in reduced error rates
for a given power level and hence equivalently improves the energy efficiency
for fixed error probabilities. The coded performance is also studied by
analyzing the random coding error exponents achieved by OOPSK and OOFSK
signaling.


title:
Dworkin's argument revisited: point processes, dynamics, diffraction,
  and correlations

abstract:
  The paper studies the relationship between diffraction and dynamics for
uniformly discrete ergodic point processes in real spaces. This relationship
takes the form of an isometric embedding of two L^2 spaces. Diffraction (or
equivalently the 2-point correlations) usually cannot determine the dynamics
entirely, but we prove that knowledge of all the higher correlations (2-point,
3-point, ...) does. A square-mean form of the Bombieri-Taylor conjecture is
proved. A quantitative relation between autocorrelation, diffraction, and
epsilon dual characters is derived. Most results of the paper are proved in the
setting of multi-colour points and assignable scattering strengths.


title: On admissibility criteria for weak solutions of the Euler equations

abstract:
  We consider solutions to the Cauchy problem for the incompressible Euler
equations satisfying several additional requirements, like the global and local
energy inequalities. Using some techniques introduced in an earlier paper we
show that, for some bounded compactly supported initial data, none of these
admissibility criteria singles out a unique weak solution.
  As a byproduct we show bounded initial data for which admissible solutions to
the p-system of isentropic gas dynamics in Eulerian coordinates are not unique
in more than one space dimension.


title: Is AGN feedback necessary to form red elliptical galaxies?

abstract:
  We have used GADGET2 to simulate the formation of an elliptical galaxy in a
cosmological dark matter halo with mass 3x10^12M_Sun/h. Using a stellar
population synthesis model has allowed us to compute magnitudes, colours and
surface brightness profiles. We have included a model to follow the growth of a
central black hole and we have compared the results of simulations with and
without feedback from AGNs. We have studied the interplay between cold gas
accretion and merging in the development of galactic morphologies, the link
between colour and morphology evolution, the effect of AGN feedback on the
photometry of early type galaxies, the redshift evolution in the properties of
quasar hosts, and the impact of AGN winds on the chemical enrichment of the
intergalactic medium (IGM). We have found that the early phases of galaxy
formation are driven by the accretion of cold filamentary flows, which form a
disc at the centre of the dark matter halo. When the dark matter halo is
sufficiently massive to support the propagation of a stable shock, cold
accretion is shut down, and the star formation rate begins to decline. Mergers
transform the disc into an elliptical galaxy, but also bring gas into the
galaxy. Without a mechanism that removes gas from the merger remnants, the
galaxy ends up with blue colours, atypical for its elliptical morphology. AGN
feedback can solve this problem even with a fairly low heating efficiency. We
have also demonstrated that AGN winds are potentially important for the metal
enrichment of the IGM a high redshift.(abridged)


title:
Swift and Chandra Detections of Supernova 2006jc: Evidence for
  Interaction of the Supernova Shock with a Circumstellar Shell

abstract:
  The peculiar Type Ib supernova (SN) 2006jc has been observed with the
UV/Optical Telescope (UVOT) and X-Ray Telescope (XRT) on board the Swift
observatory over a period of 19 to 183 days after the explosion. Signatures of
interaction of the outgoing SN shock with dense circumstellar material (CSM)
are detected, such as strong X-ray emission (L_{0.2-10} > E39 erg/s) and the
presence of MgII 2800A line emission visible in the UV spectra. In combination
with a Chandra observation obtained on day 40 after the explosion, the X-ray
light curve is constructed, which shows a unique rise of the X-ray emission by
a factor of ~5 over a period of ~4 months, followed by a rapid decline. We
interpret the unique X-ray and UV properties as a result of the SN shock
interacting with a shell of material that was deposited by an outburst of the
SN progenitor two years prior to the explosion. Our results are consistent with
the explosion of a Wolf-Rayet star that underwent an episodic mass ejection
qualitatively similar to those of luminous blue variable stars prior to its
explosion. This led to the formation of a dense (>E7 cm**-3) shell at a
distance of ~E16 cm from the site of the explosion, which expands with the WR
wind at a velocity of (1300+/-300) km/s.


title: Mixed Weil cohomologies

abstract:
  We define, for a regular scheme $S$ and a given field of characteristic zero
$\KK$, the notion of $\KK$-linear mixed Weil cohomology on smooth $S$-schemes
by a simple set of properties, mainly: Nisnevich descent, homotopy invariance,
stability (which means that the cohomology of $\GG_{m}$ behaves correctly), and
K\"unneth formula. We prove that any mixed Weil cohomology defined on smooth
$S$-schemes induces a symmetric monoidal realization of some suitable
triangulated category of motives over $S$ to the derived category of the field
$\KK$. This implies a finiteness theorem and a Poincar\'e duality theorem for
such a cohomology with respect to smooth and projective $S$-schemes (which can
be extended to smooth $S$-schemes when $S$ is the spectrum of a perfect field).
This formalism also provides a convenient tool to understand the comparison of
such cohomology theories. Our main examples are algebraic de Rham cohomology
and rigid cohomology, and the Berthelot-Ogus isomorphism relating them.


title:
Fragment formation in proton induced reactions within a BUU transport
  model

abstract:
  The formation of fragments in proton-induced reactions at low relativistic
energies within a combination of a covariant dynamical transport model and a
statistical approach is investigated. In particular, we discuss in detail the
applicability and limitations of such a hybrid model by comparing data on
fragmentation at low relativistic $SIS/GSI$-energies.


title: Combined analysis of weak lensing and X-ray blind surveys

abstract:
  We present a joint weak lensing and X-ray analysis of 4 deg$^2$ from the
CFHTLS and XMM-LSS surveys. Our weak lensing analysis is the first analysis of
a real survey using shapelets, a new generation weak lensing analysis method.
We create projected mass maps of the images, and extract 6
weak-lensing-detected clusters of galaxies. We show that their counts can be
used to constrain the power spectrum normalisation $\sigma_8
=0.92_{-0.30}^{+0.26}$ for $\Omega_m=0.24$. We show that despite the large
scatter generally observed in the M-T relation derived from lensing masses,
tight constraints on both its slope and normalisation $M_*$ can be obtained
with a moderate number of sources provided that the covered mass range is large
enough. Adding clusters from Bardeau et al. (2007) to our sample, we measure
$M_* = 2.71_{-0.61}^{+0.79} 10^{14} h^{-1} M_\odot$. Although they are
dominated by shot noise and sample variance, our measurements are consistent
with currently favoured values, and set the stage for future surveys. We thus
investigate the dependence of those estimates on survey size, depth, and
integration time, for joint weak lensing and X-ray surveys. We show that deep
surveys should be dedicated to the study of the physics of clusters and groups
of galaxies. For a given exposure time, wide surveys provide a larger number of
detected clusters and are therefore preferred for the measurement of
cosmological parameters such as $\sigma_8$ and $M_*$. We show that a wide
survey of a few hundred square degrees is needed to improve upon current
measurements of these parameters. More ambitious surveys covering 7000 deg$^2$
will provide the 1% accuracy in the estimation of the power spectrum and the
M-T relation normalisations.


title:
Photometric properties of magnetic elements: resolved and unresolved
  features

abstract:
  We investigate, by numerical simulations, the photometric signature of
magnetic flux tubes in the solar photosphere. We show that the observed
contrast profiles are determined not only by the physical properties of the
tube and its surroundings, but also by the peculiarities of the observations,
including the line/continuum formation height and the spatial and spectral
resolution. The aim is to understand these contributions well enough so that
multi-wavelength observations can begin to disentangle them.


title:
High performance NbN nanowire superconducting single photon detectors
  fabricated on MgO substrates

abstract:
  We demonstrate high-performance nanowire superconducting single photon
detectors (SSPDs) on ultrathin NbN films grown at a temperature compatible with
monolithic integration. NbN films ranging from 150nm to 3nm in thickness were
deposited by dc magnetron sputtering on MgO substrates at 400C. The
superconducting properties of NbN films were optimized studying the effects of
deposition parameters on film properties. SSPDs were fabricated on high quality
NbN films of different thickness (7 to 3nm) deposited under optimal conditions.
Electrical and optical characterizations were performed on the SSPDs. The
highest QE value measured at 4.2K is 20% at 1300nm.


title: Local and stable homological algebra in Grothendieck abelian categories

abstract:
  We define model category structures on the category of chain complexes over a
Grothendieck abelian category depending on the choice of a generating family,
and we study their behaviour with respect to tensor products and stabilization.
This gives convenient tools to construct and understand triangulated categories
of motives and we consider here the case of mixed motives over a regular base
scheme.


title: Ricci and Scalar Curvature Rigidity of the Hemisphere

abstract:
  We retract the scalar curvature rigidity theorem as there is a mistake in the
proof. We thank S. Montiel for pointing out the mistake.


title: CLAIRLIB Documentation v1.03

abstract:
  The Clair library is intended to simplify a number of generic tasks in
Natural Language Processing (NLP), Information Retrieval (IR), and Network
Analysis. Its architecture also allows for external software to be plugged in
with very little effort. Functionality native to Clairlib includes
Tokenization, Summarization, LexRank, Biased LexRank, Document Clustering,
Document Indexing, PageRank, Biased PageRank, Web Graph Analysis, Network
Generation, Power Law Distribution Analysis, Network Analysis (clustering
coefficient, degree distribution plotting, average shortest path, diameter,
triangles, shortest path matrices, connected components), Cosine Similarity,
Random Walks on Graphs, Statistics (distributions, tests), Tf, Idf, Community
Finding.


title: Computer- and robot-assisted urological surgery

abstract:
  The author reviews the computer and robotic tools available to urologists to
help in diagnosis and technical procedures. The first part concerns the
contribution of robotics and presents several systems at various stages of
development (laboratory prototypes, systems under validation or marketed
systems). The second part describes image fusion tools and navigation systems
currently under development or evaluation. Several studies on computerized
simulation of urological procedures are also presented.


title: Supersymmetric Model Building (and Sweet Spot Supersymmetry)

abstract:
  It has been more than twenty years since theorists started discussing
supersymmetric model building/phenomenology. We review mechanisms of
supersymmetry breaking/mediation and problems in each scenario. We propose a
simple model to address those problems and discuss its phenomenology.


title:
Baxterization of GL_q(2) and its application to the Liouville model and
  some other models on a lattice

abstract:
  We develop the Baxterization approach to (an extension of) the quantum group
GL_q(2). We introduce two matrices which play the role of spectral parameter
dependent L-matrices and observe that they are naturally related to two
different comultiplications. Using these comultiplication structures, we find
the related fundamental R-operators in terms of powers of coproducts and also
give their equivalent forms in terms of quantum dilogarithms. The corresponding
quantum local Hamiltonians are given in terms of logarithms of positive
operators. An analogous construction is developed for the q-oscillator and Weyl
algebras using that their algebraic and coalgebraic structures can be obtained
as reductions of those for the quantum group. As an application, the lattice
Liouville model, the q-DST model, the Volterra model, a lattice regularization
of the free field, and the relativistic Toda model are considered.


title: Using dust particle vertical chains for wakefield investigation

abstract:
  Dust particles often form vertical chains due to the influence of the
wakefield produced by the streaming ions in the plasma sheath. These particle
chains are proving useful as a unique diagnostic tool for investigating the
physics behind the basic properties of the ion wakefield within the plasma
sheath. In this paper, an experimental method is presented for investigating
the ion wakefield which employs a new oscillation technique designed to perturb
a two-particle vertical chain. Using this technique, damped free fall
oscillations are generated via an external DC bias to the lower electrode. A
fast Fourier transformation is then used to produce a spectrum from the
collected oscillation data and a center of mass oscillation is identified.


title:
The Spitzer Gould Belt Survey of Large Nearby Interstellar Clouds:
  Discovery of a Dense Embedded Cluster in the Serpens-Aquila Rift

abstract:
  We report the discovery of a nearby, embedded cluster of young stellar
objects, associated filamentary infrared dark cloud, and 4.5 micron shock
emission knots from outflows detected in Spitzer/IRAC mid-infrared imaging of
the Serpens-Aquila Rift obtained as part of the Spitzer Gould Belt Legacy
Survey. We also present radial velocity measurements of the region from
molecular line observations obtained with the Submillimeter Array (SMA) that
suggest the cluster is co-moving with the Serpens Main embedded cluster 3
degrees to the north. We therefore assign it the same distance, 260 pc. The
core of the new cluster, which we call Serpens South, is composed of an
unusually large fraction of protostars (77%) at high mean surface density (>430
pc^-2) and short median nearest neighbor spacing (3700 AU). We perform basic
cluster structure characterization using nearest neighbor surface density
mapping of the YSOs and compare our findings to other known clusters with
equivalent analyses available in the literature.


title:
A comparison of sexual and asexual replication strategies in a
  simplified model based on the yeast life cycle

abstract:
  This paper develops simplified mathematical models describing the
mutation-selection balance for the asexual and sexual replication pathways in
{\it Saccharomyces cerevisiae}. We assume diploid genomes consisting of two
chromosomes, and we assume that each chromosome is functional if and only if
its base sequence is identical to some master sequence. The growth and
replication of the yeast cells is modeled as a first-order process, with
first-order growth rate constants that are determined by whether a given genome
consists of zero, one, or two functional chromosomes. In the asexual pathway,
we assume that a given diploid cell divides into two diploids. In the sexual
pathway, we assume that a given diploid cell divides into two diploids, each of
which then divide into two haploids. The resulting four haploids enter a
haploid pool, where they grow and replicate until they meet another haploid
with which to fuse. When the cost for sex is low, we find that the selective
mating strategy leads to the highest mean fitness of the population, when
compared to all of the other strategies. We also show that, at low to
intermediate replication fidelities, sexual replication with random mating has
a higher mean fitness than asexual replication, as long as the cost for sex is
low. This is consistent with previous work suggesting that sexual replication
is advantageous at high population densities, low replication rates, and
intermediate replication fidelities. The results of this paper also suggest
that {\it S. cerevisiae} switches from asexual to sexual replication when
stressed, because stressful growth conditions provide an opportunity for the
yeast to clear out deleterious mutations from their genomes.


title:
Metastable Vacua in Perturbed Seiberg-Witten Theories, Part 2:
  Fayet-Iliopoulos Terms and K\"ahler Normal Coordinates

abstract:
  We show that the perturbation of an N=2 supersymmetric gauge theory by a
superpotential linear in the Kahler normal coordinates of the Coulomb branch,
discussed in arXiv:0704.3613, is equivalent to the perturbation by
Fayet-Iliopoulos terms. It follows that the would-be meta-stable vacuum at the
origin of the normal coordinates in fact preserves N=1 supersymmetry unless the
superpotential is truncated to a finite-degree polynomial of the adjoint scalar
fields. We examine the criteria for supersymmetry breaking under a perturbation
by Fayet-Iliopoulos terms and present a general classification of
non-supersymmetric critical points. In some explicit examples, we are also able
to study local stability of these points and demonstrate that, if the
perturbation is chosen appropriately, they indeed correspond to
supersymmetry-breaking vacua. Relations of these constructions to flux
compactifications and geometric meta-stability are also discussed.


title: Lie algebra F-normalisers are intravariant

abstract:
  Let F be a saturated formation of soluble Lie algebras and let U be an
F-normaliser of the soluble Lie algebra L. Then U is intravariant in L.


title:
Density of state and non-magnetic impurity effects in electron-doped
  cuprates

abstract:
  We analyze the density of state (DOS) and a non-magnetic impurity effect in
electron-doped cuprates starting from two different scenarios: the
$d_{x^{2}-y^{2}}$-wave superconductivity coexisting with antiferromagnetic spin
density wave (SDW) order versus $d_{x^{2}-y^{2}}$-wave superconductivity with a
higher harmonic. We find that in both cases the local density of state (LDOS)
exhibits two impurity-induced resonance states at low energies. We also find
that for the intermediate value of the SDW gap, the DOS looks similar to that
obtained from the scenario of the $d_{x^{2}-y^{2}}$-wave gap with a higher
harmonic, suggesting the presence of a non-monotonic $d_{x^{2}-y^{2}}$-wave
gap. However, if the SDW gap is sufficiently large the DOS looks more
conventional s-wave like. This obvious difference from the DOS resulted from
the $d_{x^{2}-y^{2}}$-wave gap with a higher harmonic model, could
differentiate the two above scenarios and is needed to be proved in the further
doping dependence of tunneling spectrum measurement.


title: Supersymmetric isolated horizons

abstract:
  We construct a covariant phase space for rotating weakly isolated horizons in
Einstein-Maxwell-Chern-Simons theory in all (odd) $D\geq5$ dimensions. In
particular, we show that horizons on the corresponding phase space satisfy the
zeroth and first laws of black-hole mechanics. We show that the existence of a
Killing spinor on an isolated horizon in four dimensions (when the Chern-Simons
term is dropped) and in five dimensions requires that the induced (normal)
connection on the horizon has to vanish, and this in turn implies that the
surface gravity and rotation one-form are zero. This means that the
gravitational component of the horizon angular momentum is zero, while the
electromagnetic component (which is attributed to the bulk radiation field) is
unconstrained. It follows that an isolated horizon is supersymmetric only if it
is extremal and nonrotating. A remarkable property of these horizons is that
the Killing spinor only has to exist on the horizon itself. It does not have to
exist off the horizon. In addition, we find that the limit when the surface
gravity of the horizon goes to zero provides a topological constraint.
Specifically, the integral of the scalar curvature of the cross sections of the
horizon has to be positive when the dominant energy condition is satisfied and
the cosmological constant $\Lambda$ is zero or positive, and in particular
rules out the torus topology for supersymmetric isolated horizons (unless
$\Lambda<0$) if and only if the stress-energy tensor $T_{ab}$ is of the form
such that $T_{ab}\ell^{a}n^{b}=0$ for any two null vectors $\ell$ and $n$ with
normalization $\ell_{a}n^{a}=-1$ on the horizon.


title:
Short-Hard Gamma-Ray Bursts in Young Host Galaxies: the Effect of Prompt
  Twins

abstract:
  We investigate the effect of including a significant ``binary twin''
population (binaries with almost equal mass stars, q = M2/M1 > 0.95) for the
production of double compact objects and some resulting consequences, including
LIGO inspiral rate and some properties of short-hard gamma-ray bursts. We
employ very optimistic assumptions on the twin fraction (50%) among all
binaries, and therefore our calculations place an upper limits on the influence
of twins on double compact object populations. We show that for LIGO the effect
of including twins is relatively minor: although the merger rates does indeed
increase when twins are considered, the rate increase is fairly small (1.5).
Also, chirp mass distribution for double compact objects formed with or without
twins are almost indistinguishable. If double compact object are short-hard GRB
progenitors, including twins in population synthesis calculations does not
alter significantly the earlier rate predictions for the event rate. However,
for one channel of binary evolution, introducing twins more than doubles the
rate of ``very prompt'' NS-NS mergers (time to merger less than 1 Myr) compared
to models with the ``flat'' q distribution. In that case, 70% of all NS-NS
binaries merge within 100 Myr after their formation, indicating a possibility
of a very significant population of ``prompt'' short-hard gamma-ray bursts,
associated with star forming galaxies. We also point out that, independent of
assumptions, fraction of such prompt neutron star mergers is always high,
35--70%. We note that recent observations (e.g., Berger et al.) indicate that
fraction of short-hard GRBs found in young hosts is at least 40% and possibly
even 80%.


title:
Unidirectional rotary nanomotors powered by an electrochemical potential
  gradient

abstract:
  We examine the dynamics of biological nanomotors within a simple model of a
rotor having three ion-binding sites. It is shown that in the presence of an
external dc electric field in the plane of the rotor, the loading of the ion
from the positive side of a membrane (rotor charging) provides a torque leading
to the motor rotation. We derive equations for the proton populations of the
sites and solve these equations numerically jointly with the Langevin-type
equation for the rotor angle. Using parameters for biological systems, we
demonstrate that the sequential loading and unloading of the sites lead to the
unidirectional rotation of the motor. The previously unexplained phenomenon of
fast direction-switching in the rotation of a bacterial flagellar motor can
also be understood within our model.


title: A Les Houches Interface for BSM Generators

abstract:
  We propose to combine and slightly extend two existing "Les Houches Accords"
to provide a simple generic interface between beyond-the-standard-model
parton-level and event-level generators. All relevant information - particle
content, quantum numbers of new states, masses, cross sections, parton-level
events, etc - is collected in one single file, which adheres to the Les Houches
Event File (LHEF) standard.


title: Graph Compression -- Save Information by Exploiting Redundancy

abstract:
  In this paper we raise the question of how to compress sparse graphs. By
introducing the idea of redundancy, we find a way to measure the overlap of
neighbors between nodes in networks. We exploit symmetry and information by
making use of the overlap in neighbors and analyzing how information is reduced
by shrinking the network and using the specific data structure we created, we
generalize the problem of compression as an optimization problem on the
possible choices of orbits. To find a reasonably good solution to this problem
we use a greedy algorithm to determine the orbit of symmetry identifications,
to achieve compression. Some example implementations of our algorithm are
illustrated and analyzed.


title:
Effect of Singwi-Tosi-Land-Sj\"{o}lander local field correction on spin
  relaxation in $n$-type GaAs quantum wells at low temperature

abstract:
  We study the effect of the Singwi-Tosi-Land-Sj\"{o}lander local field
correction on spin relaxation/dephasing in $n$-type GaAs quantum wells at low
temperature by constructing and numerically solving the kinetic spin Bloch
equations. We calculate the local field factor $G(q)$ in quantum wells by
numerically solving three equations which link the local field factor, the
structure factor, and the dielectric function, self-consistently. Such a
correction reduces both the electron-electron Coulomb scattering and the
Coulomb Hartree-Fock term. We compare the spin relaxation times with and
without this correction under different conditions such as temperature,
electron density, well width and spin polarization. We find that this
correction leads to a decrease/increase of the spin relaxation time in the
strong/weak scattering limit. At high spin polarization, it reduces the
Hartree-Fock term and consequently tends to decrease the spin relaxation time.
The modification of the spin relaxation time by the local field correction is
more or less moderate either due to the coexistence of scattering other than
the Coulomb scattering at low spin polarization and/or due to the competing
effects from the Coulomb scattering and the Coulomb Hartree-Fock term at high
polarization.


title:
A novel mechanism for outbursts of Comet 17P/Holmes and other
  short-period comets

abstract:
  A mechanism is proposed to explain the outburst of comet 17P/Holmes based on;
(a) oxidation of water within the porous surface of the comet nucleus to form
hydrogen peroxide (H2O2) through exposure to UV radiation, to energetic
solar-wind particles and to cosmic radiation, (b) concentration of the H2O2
component through solid-, liquid- and gas-phase processes involving
sublimation, evaporation, fractional crystallization, diffusion, supercooling,
capillary wetting and migration in voids within the nucleus, and (c) rapid
exothermic decomposition of aqueous H2O2 liberating oxygen gas via a surface
catalytic reaction through interaction with finely-dispersed transition metals,
metal compounds and minerals, in particular those containing Fe, localised
within a differentiated multi-component comet nucleus. An accelerated release
of gaseous oxygen, concomitant self-heating and volatilisation of hydrocarbons
within the nucleus results in its explosive disruption. This mechanism may also
explain the observation of a repeat outburst of this comet in 1893. Laboratory
studies to investigate H2O2 formation in simulated cometary environments and to
evaluate H2O2 decomposition on meteoritic samples are recommended.


title:
Thermodynamics of Schwarzschild-de Sitter black hole: thermal stability
  of Nariai black hole

abstract:
  We study thermodynamics of the Schwarzschild-de Sitter black hole in five
dimensions by introducing two temperatures based on the standard and
Bousso-Hawking normalizations. We use the first-law of thermodynamics to derive
thermodynamic quantities. The two temperatures indicate that the Nariai black
hole is thermodynamically unstable. However, it seems that black hole
thermodynamics favors the standard normalization, and does not favor the
Bousso-Hawking normalization.


title: Site-resolved Bragg scattering

abstract:
  We numerically calculate the reliability with which one can optically
determine the presence or absence of an individual scatterer in a randomly
occupied 3D array of well-localized, coherently radiating scatterers. The
reliability depends in a complicated way on the ratio of lattice spacing to
wavelength and the numerical aperture of the imaging system. The behavior can
be qualitatively understood by considering the dependence of Bragg scattering
modes on lattice spacing. These results are of interest for atomic
implementations of quantum information processing.


title:
The Hydrogen Ionization Front-Stellar Photosphere Interaction and the
  Period-Color Relations of Variable Stars

abstract:
  Recent evidence has emerged that the Cepheid PL relation in the LMC is
nonlinear in the sense that the existing data are more consistent with two
lines of differing slope with a break at a period of 10 days. We review the
statistical evidence for this, the implications for the extra-galactic distance
scale and CMB independent estimations of Hubble's constant and briefly outline
one possible physical mechanism which could cause this nonlinearity.


title: Locality Estimates for Quantum Spin Systems

abstract:
  We review some recent results that express or rely on the locality properties
of the dynamics of quantum spin systems. In particular, we present a slightly
sharper version of the recently obtained Lieb-Robinson bound on the group
velocity for such systems on a large class of metric graphs. Using this bound
we provide expressions of the quasi-locality of the dynamics in various forms,
present a proof of the Exponential Clustering Theorem, and discuss a
multi-dimensional Lieb-Schultz-Mattis Theorem.

categories: math-ph cond-mat.stat-mech math.MP quant-ph


title:
Determination of Topology Skeleton of Magnetic Fields in a Solar Active
  Region

abstract:
  The knowledge of magnetic topology is the key to understand magnetic energy
release in astrophysics. Based on observed vector magnetograms, we have
determined threedimensional (3D) topology skeleton of the magnetic fields in
active region NOAA 10720. The skeleton consists of six 3D magnetic nulls and a
network of corresponding spines, fans, and null-null lines. For the first time,
we have identified a spiral magnetic null in Sun's corona. The magnetic lines
of force twisted around the spine of the null, forming a 'magnetic wreath' with
excess of free magnetic energy and resembling observed brightening structures
at extraultraviolet (EUV) wavebands. We found clear evidence of topology
eruptions which are referred to as the catastrophic changes of topology
skeleton associated with a coronal mass ejection (CME) and an explosive X-ray
flare. These results shed new lights in exploring the structural complexity and
its role in explosive magnetic activity. In solar astrophysics and space
science, the concept of flux rope has been widely used in modelling explosive
magnetic activity, although their observational identity is obscure or, at
least, lacking of necessary details. The current work suggests that the
magnetic wreath associated with the 3D spiral null is likely an important class
of the physical entity of flux ropes.


title:
rho^0 Photoproduction in Ultra-Peripheral Relativistic Heavy Ion
  Collisions with STAR

abstract:
  Photoproduction reactions occur when the electromagnetic field of a
relativistic heavy ion interacts with another heavy ion. The STAR collaboration
presents a measurement of rho^0 and direct pi^+pi^- photoproduction in
ultra-peripheral relativistic heavy ion collisions at sqrt(s_{NN})=200 GeV. We
observe both exclusive photoproduction and photoproduction accompanied by
mutual Coulomb excitation. We find a coherent cross-section of sigma(AuAu) ->
Au^*Au^*rho^0 = 530 pm 19 (stat.) pm 57 (syst.) mb, in accord with theoretical
calculations based on a Glauber approach, but considerably below the
predictions of a color dipole model. The rho^0 transverse momentum spectrum
(p_{T}^2) is fit by a double exponential curve including both coherent and
incoherent coupling to the target nucleus; we find sigma_{inc}/sigma_{coh} =
0.29 pm 0.03 (stat.) pm 0.08 (syst.). The ratio of direct pi^+pi^- to rho^0
production is comparable to that observed in gamma p collisions at HERA, and
appears to be independent of photon energy. Finally, the measured rho^0 spin
helicity matrix elements agree within errors with the expected s-channel
helicity conservation.


title:
Non-equilibrium vertex correction: disorder scattering in magnetic
  tunnel junctions

abstract:
  We report a first principles formalism and its numerical implementation for
treating quantum transport properties of nanoelectronic devices with atomistic
disorder. We developed a nonequilibrium vertex correction (NVC) theory to
handle the configurational average of random disorder at the density matrix
level so that disorder effects to nonlinear and nonequilibrium quantum
transport can be calculated from atomic first principles in a self-consistent
and efficient manner. We implemented the NVC into a Keldysh non-equilibrium
Green's function (NEGF) based density functional theory (DFT) and applied the
NEGF-DFT-NVC formalism to magnetic tunnel junctions with interface roughness
disorder. Our results show that disorder has dramatic effects to nonlinear spin
injection and tunnel magneto-resistance ratio.


title: Red Noise in Anomalous X-ray Pulsar Timing Residuals

abstract:
  Anomalous X-ray Pulsars (AXPs), thought to be magnetars, exhibit poorly
understood deviations from a simple spin-down called "timing noise". AXP timing
noise has strong low-frequency components which pose significant challenges for
quantification. We describe a procedure for extracting two quantities of
interest, the intensity and power spectral index of timing noise. We apply this
procedure to timing data from three sources: a monitoring campaign of five
AXPs, observations of five young pulsars, and the stable rotator PSR B1937+21.


title:
Analysis of the optimal exercise boundary of American options for jump
  diffusions

abstract:
  In this paper we show that the optimal exercise boundary / free boundary of
the American put option pricing problem for jump diffusions is continuously
differentiable (except at the maturity). This differentiability result has been
established by Yang et al. (European Journal of Applied Mathematics,
17(1):95-127, 2006) in the case where the condition $r\geq q+ \lambda
\int_{\R_+} (e^z-1) \nu(dz)$ is satisfied. We extend the result to the case
where the condition fails using a unified approach that treats both cases
simultaneously. We also show that the boundary is infinitely differentiable
under a regularity assumption on the jump distribution.


title: Boltzmann babies in the proper time measure

abstract:
  After commenting briefly on the role of the typicality assumption in science,
we advocate a phenomenological approach to the cosmological measure problem.
Like any other theory, a measure should be simple, general, well-defined, and
consistent with observation. This allows us to proceed by elimination. As an
example, we consider the proper time cutoff on a geodesic congruence. It
predicts that typical observers are quantum fluctuations in the early universe,
or Boltzmann babies. We sharpen this well-known youngness problem by taking
into account the expansion and open spatial geometry of pocket universes.
Moreover, we relate the youngness problem directly to the probability
distribution for observables, such as the temperature of the cosmic background
radiation. We consider a number of modifications of the proper time measure,
but find none that would make it compatible with observation.


title: Dynamic Nuclear Polarization in a Quantum Hall Corbino Disk

abstract:
  Electrical polarization of nuclear spins is studied in a Corbino disk under a
breakdown regime of the quantum Hall effect (QHE). Since the edge channels are
completely absent in the Corbino disk, we conclude that the electric current
flowing in the bulk channel of a quantum Hall conductor is relevant to dynamic
nuclear polarization (DNP). A pump and probe measurement demonstrates that DNP
emerges near the critical voltage of the QHE breakdown. The agreement of the
onset voltage of DNP with that of the QHE breakdown indicates that the
underlying origin of DNP is closely related to that of the QHE breakdown.


title: Spontaneous formation of complex micelles from homogeneous solution

abstract:
  We present an extensive computer simulation study of structure formation in
amphiphilic block copolymer solutions after a quench from a homogeneous state.
By using a mesoscopic field-based simulation method, we are able to access time
scales in the range of a second. A phase diagram of final structures is mapped
out as a function of the concentration and solvent-philicity of the copolymers.
A rich spectrum of structures is observed, ranging from spherical and rodlike
micelles and vesicles to toroidal and net-cage micelles. The dynamical pathways
leading to these structures are analyzed in detail, and possible ways to
control the structures are discussed briefly.


title:
The capacity of a class of 3-receiver broadcast channels with degraded
  message sets

abstract:
  Korner and Marton established the capacity region for the 2-receiver
broadcast channel with degraded message sets. Recent results and conjectures
suggest that a straightforward extension of the Korner-Marton region to more
than 2 receivers is optimal. This paper shows that this is not the case. We
establish the capacity region for a class of 3-receiver broadcast channels with
2 degraded message sets and show that it can be strictly larger than the
straightforward extension of the Korner-Marton region. The key new idea is
indirect decoding, whereby a receiver who cannot directly decode a cloud
center, finds it indirectly by decoding satellite codewords. This idea is then
used to establish new inner and outer bounds on the capacity region of the
general 3-receiver broadcast channel with 2 and 3 degraded message sets. We
show that these bounds are tight for some nontrivial cases. The results suggest
that the capacity of the 3-receiver broadcast channel with degraded message
sets is as at least as hard to find as the capacity of the general 2-receiver
broadcast channel with common and private message.


title: "Phantom" Inflation in Warped Compactification

abstract:
  In this paper, in a class of warped compactifications with the brane/flux
annihilation, we find that the inflation may be driven by a flat direction
identified as that along the number p of anti D3-branes located at the tip of
the Klebanov-Strassler throat. The spectrum of adiabatic perturbation generated
during inflation is nearly scale invariant, which may be obtained by using the
results shown in the phantom inflation, since in a four-dimension effective
description the evolution of energy density along the $p$ direction is slowly
increasing.


title: Universal Intelligence: A Definition of Machine Intelligence

abstract:
  A fundamental problem in artificial intelligence is that nobody really knows
what intelligence is. The problem is especially acute when we need to consider
artificial systems which are significantly different to humans. In this paper
we approach this problem in the following way: We take a number of well known
informal definitions of human intelligence that have been given by experts, and
extract their essential features. These are then mathematically formalised to
produce a general measure of intelligence for arbitrary machines. We believe
that this equation formally captures the concept of machine intelligence in the
broadest reasonable sense. We then show how this formal definition is related
to the theory of universal optimal learning agents. Finally, we survey the many
other tests and definitions of intelligence that have been proposed for
machines.


title:
Role of Higher Multipole Excitations in the Electromagnetic Dissociation
  of One Neutron Halo Nuclei

abstract:
  We investigate the role of higher multipole excitations in the
electromagnetic dissociation of one-neutron halo nuclei within two different
theoretical models -- a finite range distorted wave Born approximation and
another in a more analytical method with a finite range potential. We also
show, within a simple picture, how the presence of a weakly bound state affects
the breakup cross section.


title: How to Complete a Doubling Metric

abstract:
  In recent years, considerable advances have been made in the study of
properties of metric spaces in terms of their doubling dimension. This line of
research has not only enhanced our understanding of finite metrics, but has
also resulted in many algorithmic applications. However, we still do not
understand the interaction between various graph-theoretic (topological)
properties of graphs, and the doubling (geometric) properties of the
shortest-path metrics induced by them. For instance, the following natural
question suggests itself: \emph{given a finite doubling metric $(V,d)$, is
there always an \underline{unweighted} graph $(V',E')$ with $V\subseteq V'$
such that the shortest path metric $d'$ on $V'$ is still doubling, and which
agrees with $d$ on $V$.} This is often useful, given that unweighted graphs are
often easier to reason about.
  We show that for any metric space $(V,d)$, there is an \emph{unweighted}
graph $(V',E')$ with shortest-path metric $d':V'\times V' \to \R_{\geq 0}$ such
that
  -- for all $x,y \in V$, the distances $d(x,y) \leq d'(x,y) \leq (1+\eps)
\cdot d(x,y)$, and
  -- the doubling dimension for $d'$ is not much more than that of $d$, where
this change depends only on $\e$ and not on the size of the graph.
  We show a similar result when both $(V,d)$ and $(V',E')$ are restricted to be
trees: this gives a simpler proof that doubling trees embed into constant
dimensional Euclidean space with constant distortion. We also show that our
results are tight in terms of the tradeoff between distortion and dimension
blowup.


title:
Extreme genetic code optimality from a molecular dynamics calculation of
  amino acid polar requirement

abstract:
  A molecular dynamics calculation of the amino acid polar requirement is
presented and used to score the canonical genetic code. Monte Carlo simulation
shows that this computational polar requirement has been optimized by the
canonical genetic code more than any previously-known measure. These results
strongly support the idea that the genetic code evolved from a communal state
of life prior to the root of the modern ribosomal tree of life.


title: On the approximability of the vertex cover and related problems

abstract:
  In this paper we show that the problem of identifying an edge $(i,j)$ in a
graph $G$ such that there exists an optimal vertex cover $S$ of $G$ containing
exactly one of the nodes $i$ and $j$ is NP-hard. Such an edge is called a weak
edge. We then develop a polynomial time approximation algorithm for the vertex
cover problem with performance guarantee $2-\frac{1}{1+\sigma}$, where $\sigma$
is an upper bound on a measure related to a weak edge of a graph. Further, we
discuss a new relaxation of the vertex cover problem which is used in our
approximation algorithm to obtain smaller values of $\sigma$. We also obtain
linear programming representations of the vertex cover problem for special
graphs. Our results provide new insights into the approximability of the vertex
cover problem - a long standing open problem.


title:
The center of some braid groups and the Farrell cohomology of certain
  pure mapping class groups

abstract:
  In this paper we first show that many braid groups of low genus surfaces have
their centers as direct factors. We then give a description of centralizers and
normalizers of prime order elements in pure mapping class groups of surfaces
with spherical quotients using automorphism groups of fundamental groups of the
quotient surfaces. As an application, we use these to show that the $p$-primary
part of the Farrell cohomology groups of certain mapping class groups are
elementary abelian groups. At the end we compute the $p$-primary part of the
Farrell cohomology of a few pure mapping class groups.


title:
A polynomial time $\frac 3 2$ -approximation algorithm for the vertex
  cover problem on a class of graphs

abstract:
  We develop a polynomial time 3/2-approximation algorithm to solve the vertex
cover problem on a class of graphs satisfying a property called ``active edge
hypothesis''. The algorithm also guarantees an optimal solution on specially
structured graphs. Further, we give an extended algorithm which guarantees a
vertex cover $S_1$ on an arbitrary graph such that $|S_1|\leq {3/2} |S^*|+\xi$
where $S^*$ is an optimal vertex cover and $\xi$ is an error bound identified
by the algorithm. We obtained $\xi = 0$ for all the test problems we have
considered which include specially constructed instances that were expected to
be hard. So far we could not construct a graph that gives $\xi \not= 0$.


title: Cardiac Alternans Arising from an Unfolded Border-Collision Bifurcation

abstract:
  Following an electrical stimulus, the transmembrane voltage of cardiac tissue
rises rapidly and remains at a constant value before returning to the resting
value, a phenomenon known as an action potential. When the pacing rate of a
periodic train of stimuli is increased above a critical value, the action
potential undergoes a period-doubling bifurcation, where the resulting
alternation of the action potential duration is known as alternans in the
medical literature. Existing cardiac models treat alternans either as a smooth
or as a border-collision bifurcation. However, recent experiments in paced
cardiac tissue reveal that the bifurcation to alternans exhibits hybrid
smooth/nonsmooth behaviors, which can be qualitatively described by a model of
so-called unfolded border-collision bifurcation. In this paper, we obtain
analytical solutions of the unfolded border-collision model and use it to
explore the crossover between smooth and nonsmooth behaviors. Our analysis
shows that the hybrid smooth/nonsmooth behavior is due to large variations in
the system's properties over a small interval of the bifurcation parameter,
providing guidance for the development of future models.


title: Q value of the 100Mo Double-Beta Decay

abstract:
  Penning trap measurements using mixed beams of 100Mo - 100Ru and 76Ge - 76Se
have been utilized to determine the double-beta decay Q-values of 100Mo and
76Ge with uncertainties less than 200 eV. The value for 76Ge, 2039.04(16) keV
is in agreement with the published SMILETRAP value. The new value for 100Mo,
3034.40(17) keV is 30 times more precise than the previous literature value,
sufficient for the ongoing neutrinoless double-beta decay searches in 100Mo.
Moreover, the precise Q-value is used to calculate the phase-space integrals
and the experimental nuclear matrix element of double-beta decay.


title: Duality properties of Gorringe-Leach equations

abstract:
  In the category of motions preserving the angular momentum's direction,
Gorringe and Leach exhibited two classes of differential equations having
elliptical orbits. After enlarging slightly these classes, we show that they
are related by a duality correspondence of the Arnold-Vassiliev type. The
specific associated conserved quantities (Laplace-Runge-Lenz vector and
Fradkin-Jauch-Hill tensor) are then dual reflections one of the other


title:
Rectification in synthetic conical nanopores: a one-dimensional
  Poisson-Nernst-Planck modeling

abstract:
  Ion transport in biological and synthetic nanochannels is characterized by
phenomena such as ion current fluctuations and rectification. Recently, it has
been demonstrated that nanofabricated synthetic pores can mimic transport
properties of biological ion channels [P. Yu. Apel, {\it et al.}, Nucl. Instr.
Meth. B {\bf 184}, 337 (2001); Z. Siwy, {\it et al.}, Europhys. Lett. {\bf 60},
349 (2002)]. Here, the ion current rectification is studied within a reduced 1D
Poisson-Nernst-Planck (PNP) model of synthetic nanopores. A conical channel of
a few $\mathrm{nm}$ to a few hundred of nm in diameter, and of few $\mu$m long
is considered in the limit where the channel length considerably exceeds the
Debye screening length. The rigid channel wall is assumed to be weakly charged.
A one-dimensional reduction of the three-dimensional problem in terms of
corresponding entropic effects is put forward. The ion transport is described
by the non-equilibrium steady-state solution of the 1D Poisson-Nernst-Planck
system within a singular perturbation treatment. An analytic formula for the
approximate rectification current in the lowest order perturbation theory is
derived. A detailed comparison between numerical results and the singular
perturbation theory is presented. The crucial importance of the asymmetry in
the potential jumps at the pore ends on the rectification effect is
demonstrated. This so constructed 1D theory is shown to describe well the
experimental data in the regime of small-to-moderate electric currents.


title: Using Monte Carlo to optimize variable cuts

abstract:
  A Monte Carlo method to optimize cuts on variables is presented and
evaluated. The method gives a much higher signal to noise ratio than does a
manual choice of cuts.


title:
Comment on "Spatial line nodes and fractional vortex pairs in the
  Fulde-Ferrell-Larkin-Ovchinnikov phase"

abstract: This is a Comment on Phys.Rev.Lett. 100, 017001 (2008).


title:
Are there indications of compositeness of leptons and quarks in CERN LEP
  data?

abstract:
  The ``preon-trinity'' model for the compositeness of leptons, quarks and
heavy vector bosons predicts several new heavy leptons and quarks. Three of
them can be produced in $e^{+}e^{-}$ annihilations at CERN LEP energies, since
they can be created out of a system of three preons and their antipreons, where
three preons form a heavy lepton or quark, while the other three go into a
normal lepton or quark. In fact, these new particles are predicted to be
lighter than the top quark, while the top itself cannot be produced this way,
due to its particular preon substructure. The empirical situation is analyzed,
and the most likely masses are estimated.


title:
Stellar dynamics in young clusters: the formation of massive runaways
  and very massive runaway mergers

abstract:
  In the present paper we combine an N-body code that simulates the dynamics of
young dense stellar systems with a massive star evolution handler that accounts
in a realistic way for the effects of stellar wind mass loss. We discuss two
topics:
  1. The formation and the evolution of very massive stars (with a mass >120
Mo) is followed in detail. These very massive stars are formed in the cluster
core as a consequence of the successive (physical) collison of 10-20 most
massive stars of the cluster (the process is known as runaway merging). The
further evolution is governed by stellar wind mass loss during core hydrogen
burning and during core helium burning (the WR phase of very massive stars).
Our simulations reveal that as a consequence of runaway merging in clusters
with solar and supersolar values, massive black holes can be formed but with a
maximum mass of 70 Mo. In small metallicity clusters however, it cannot be
excluded that the runaway merging process is responsible for pair instability
supernovae or for the formation of intermediate mass black holes with a mass of
several 100 Mo.
  2. Massive runaways can be formed via the supernova explosion of one of the
components in a binary (the Blaauw scenario) or via dynamical interaction of a
single star and a binary or between two binaries in a star cluster. We explore
the possibility that the most massive runaways (e.g., zeta Pup, lambda Cep,
BD+433654) are the product of the collision and merger of 2 or 3 massive stars.


title: A study of local approximation for polarization potentials

abstract:
  We discuss the derivation of an equivalent \textit{l}-independent
polarization potential for use in the optical Schr\"{o}dinger equation that
describes the elastic scattering of heavy ions. Three diffferent methods are
used for this purpose. Application of our theory to the low energy scattering
of the halo nucleus $^{11}$Li from a $^{12}$C target is made. It is found that
the notion of \textit{l}-independent polarization potential has some validity
but can not be a good substitute for the \textit{l}-dependent local equivalent
Feshbach polarization potential.


title:
UVES radial velocity accuracy from asteroid observations. Implications
  for the fine structure constant variability

abstract:
  High resolution observations of the asteroids Iris and Juno have been
performed by means of the UVES spectrograph at the ESO VLT to obtain the
effective accurac y of the spectrograph's radial velocity. The knowledge of
this quantity has impo rtant bearings on studies searching for a variability of
the fine structure cons tant carried on with this instrument. Asteroids provide
a precise radial velocit y reference at the level of 1 m/s which allows
instrumental calibration and the recognition of small instrumental drifts and
calibration systematics. In particu lar, radial velocity drifts due to non
uniform slit illumination and slit optica l misalignment in the two UVES
spectrograph arms can be investigated. The positi on of the solar spectrum
reflected by the asteroids are compared with the solar wavelength positions or
with that of asteroid observations at other epochs or wi th the twilight to
asses UVES instrumental accuracy . Radial velocities offsets in the range
10--50 m/s are generally observed likely due to a non uniform slit
illumination. However, no radial velocity patterns with wavelength are detected
and the two UVES arms provide consistent radial velocities. These results
suggest that the detected alpha variability by Levshakov et al. (2007) deduced
from a drift of -180 (+/- 85) m/s at z =1.84, between two sets of FeII lines
falling in the two UVES arms may be real or induced by other kinds of
systematics than those investigated here. The proposed technique allows real
time quality check of the spectrograph and should be followed for very accurate
measurements.


title: Pion electromagnetic form factor at finite density

abstract:
  In this talk, we introduce an effective chiral action, derived from the
instanton QCD vacuum configuration, in order to study the modification of
mesonic properties in medium. We present our recent theoretical results on the
electromagnetic from factor and rho-meson mass shift at finite density. We
observe that the rho-meson mass is dropped by about 10%: m*_rho/m_rho ~ 1-0.12
mu_B/mu_0, which is compatible with that estimated by the QCD sum rule as well
as by Brown and Rho.


title:
Structure of the Lambda(1405) baryon resonance from its large Nc
  behavior

abstract:
  We study the behavior with the number of colors (Nc) of the two poles
associated to the Lambda(1405) resonance obtained dynamically within the chiral
unitary approach. The leading order chiral meson-baryon interaction manifests a
nontrivial Nc dependence for SU(3) baryons, which gives a finite attractive
interaction in some channels in the large Nc limit. As a consequence, the SU(3)
singlet (Kbar N) component of the Lambda(1405) survives in the large Nc limit
as a bound state, while the other components dissolve into the continuum. The
Nc dependence of the decay widths shows different behavior from the general
counting rule for a qqq state, indicating the dynamical origin of the two poles
for the Lambda(1405) resonance.


title: On Exponential Time Lower Bound of Knapsack under Backtracking

abstract:
  M.Aleknovich et al. have recently proposed a model of algorithms, called BT
model, which generalizes both the priority model of Borodin, Nielson and
Rackoff, as well as a simple dynamic programming model by Woeginger. BT model
can be further divided into three kinds of fixed, adaptive and fully adaptive
ones. They have proved exponential time lower bounds of exact and approximation
algorithms under adaptive BT model for Knapsack problem. Their exact lower
bound is $\Omega(2^{0.5n}/\sqrt{n})$, in this paper, we slightly improve the
exact lower bound to about $\Omega(2^{0.69n}/\sqrt{n})$, by the same technique,
with related parameters optimized.


title: Surfaces with maximal constant mean curvature

abstract:
  In this note we consider asymptotically flat manifolds with non-negative
scalar curvature and an inner boundary which is an outermost minimal surface.
We show that there exists an upper bound on the mean curvature of a constant
mean curvature surface homologous to a subset of the interior boundary
components. This bound allows us to find a maximizer for the constant mean
curvature of a surface homologous to the inner boundary.
  With this maximizer at hand, we can construct an increasing family of sets
with boundaries of increasing constant mean curvature. We interpret this
familiy as a weak version of a CMC foliation.


title: Market Model with Heterogeneous Buyers

abstract:
  In market modeling, one often treats buyers as a homogeneous group. In this
paper we consider buyers with heterogeneous preferences and products available
in many variants. Such a framework allows us to successfully model various
market phenomena. In particular, we investigate how is the vendor's behavior
influenced by the amount of available information and by the presence of
correlations in the system.


title: Spin-dependent diffraction at ferromagnetic/spin spiral interface

abstract:
  Spin-dependent transport is investigated in ballistic regime through the
interface between a ferromagnet and a spin spiral. We show that spin-dependent
interferences lead to a new type of diffraction called "spin-diffraction". It
is shown that this spin-diffraction leads to local spin and electrical currents
along the interface. This study also shows that in highly non homogeneous
magnetic configuration (non adiabatic limit), the contribution of the
diffracted electrons is crucial to describe spin transport in such structures.


title: Gamma-ray Astronomy

abstract:
  The relevance of gamma-ray astronomy to the search for the origin of the
galactic and, to a lesser extent, the ultra-high-energy cosmic rays has long
been recognised. The current renaissance in the TeV gamma-ray field has
resulted in a wealth of new data on galactic and extragalactic particle
accelerators, and almost all the new results in this field were presented at
the recent International Cosmic Ray Conference (ICRC). Here I summarise the 175
papers submitted on the topic of gamma-ray astronomy to the 30th ICRC in
Merida, Mexico in July 2007.


title: Rapid paths in von Neumann-Gale dynamical systems

abstract:
  The paper examines random dynamical systems related to the classical von
Neumann and Gale models of economic growth. Such systems are defined in terms
of multivalued operators in spaces of random vectors, possessing certain
properties of convexity and homogeneity. A central role in the theory of von
Neumann-Gale dynamics is played by a special class of paths called rapid (they
maximize properly defined growth rates). Up to now the theory lacked quite
satisfactory results on the existence of such paths. This work provides a
general existence theorem holding under assumptions analogous to the standard
deterministic ones. The result solves a problem that remained open for more
than three decades.


title:
Prospects for Observations of Transient UV Events with the TAUVEX UV
  Observatory

abstract:
  Transient events have posed special problems in astronomy because of the
intrinsic difficulty of their detection, and a new class of observatories such
as the Pan-STARRS and LSST are coming up specifically to observe these
energetic events. In this paper we discuss the UV transient events from two
specific sources, such as possible collisions in extrasolar planetary systems
and M dwarf flares, to find the probability of their detection by space UV
observatories, in particular, by the Tel Aviv University Explorer (TAUVEX).
TAUVEX is an UV imaging experiment that will image large parts of the sky in
the wavelength region between 120 and 350 nm. TAUVEX is a collaborative effort
between the Indian Institute of Astrophysics (IIA) and Tel Aviv University, and
is scheduled for an early-2009 launch with at least three years of operations.
The scientific instrument has been fabricated at El-Op in Israel, with the
satellite interfaces, launch and flight operations provided by the Indian Space
Research Organization (ISRO). The ground-based software development is the
responsibility of the IIA while other aspects of the mission are the joint
responsibility of IIA and Tel Aviv University. TAUVEX Science Team (TST) have
created a coherent observing program to address several Key Areas science
objectives, one of them is a program to study short-scale UV transient events.
We have estimated that in one year of TAUVEX observations we can expect about
90-350 short-scale transient events. Because we obtain real-time telemetry with
TAUVEX, we will be able to catch transients early in their evolution and to
alert other observatories. We also present a description of TAUVEX mission,
including instrument design and its estimated performance.


title: Optimized Gaussian exponents for Goedecker-Teter-Hutter pseudopotentials

abstract:
  We have optimized the exponents of Gaussian s and p basis functions for the
elements H, B-F, and Al-Cl using the pseudopotentials of Goedecker, Teter, and
Hutter [Phys. Rev. B 54, 1703 (1996)] by minimizing the total energy of dimers.
We found that this procedure causes the Gaussian to be somewhat more localized
than the usual procedure, where the exponents are optimized for atoms. We
further found that three exponents, equal for s and p orbitals, are sufficient
to reasonably describe the electronic structure of all elements that we have
studied. For Li and Be results are presented for pseudopotentials of Hartwigsen
et al. [Phys. Rev. B 58, 3641 (1998)]. We expect that our exponents will be
useful for density functional theory studies where speed is important.


title: Cosmological model: from initial conditions to structure formation

abstract:
  Observational cosmology is on the verge of new discoveries that will change
the essence of our world-view. The matter concerns origin of initial conditions
and physics of dark matter.


title:
Effects of geometrical fluctuations on the transition temperature of
  disordered quasi-one-dimensional superconductors

abstract:
  We study the superconducting transition temperature, T_c, of an array of
fluctuating, maximally gapped interacting ladders, embedded in a disordered
plane. Renormalization group analysis indicates that geometrical fluctuations
mitigate the suppression of the intra-ladder pairing correlations by the
disorder. In addition, the fluctuations enhance the Josephson tunneling between
the ladders. Both effects lead to an increase of T_c in the Josephson coupled
array. These findings may be relevant to the understanding of the 1/8 anomaly
in the lanthanum based high-temperature superconductors.


title:
Non-equilibrium dynamics of polymers and interfaces in random media :
  conjecture $\psi=d_s/2$ for the barrier exponent

abstract:
  We consider various random models (directed polymer, random ferromagnets,
spin-glasses) in their disorder-dominated phases, where the free-energy cost
$F(L)$ of an excitation of length $L$ presents fluctuations that grow as a
power-law $\Delta F(L) \sim L^{\theta}$ with the 'droplet' exponent $\theta$.
Within the droplet theory, the energy and entropy of such excitations present
fluctuations that grow as $\Delta E(L) \sim \Delta S(L) \sim L^{d_s/2}$ where
$d_s$ is the dimension of the surface of the excitation. These systems usually
present a positive 'chaos' exponent $\zeta=d_s/2-\theta>0$, meaning that the
free-energy fluctuation of order $L^{\theta}$ is a near-cancellation of much
bigger energy and entropy fluctuations of order $L^{d_s/2}$. Within the
standard droplet theory, the dynamics is characterized by a barrier exponent
$\psi$ satisfying the bounds $\theta \leq \psi \leq d-1$. In this paper, we
argue that a natural value for this barrier exponent is $\psi=d_s/2$ : (i) for
the directed polymer where $d_s=1$, this corresponds to $\psi=1/2$ in all
dimensions; (ii) for disordered ferromagnets where $d_s=d-1$, this corresponds
to $\psi=(d-1)/2$; (iii) for spin-glasses where interfaces have a non-trivial
dimension $d_s$ known numerically, our conjecture $\psi=d_s/2$ gives numerical
predictions in $d=2$ and $d=3$. We compare these values with the available
numerical results for each case, in particular with the measure $\psi \simeq
0.49$ of Kolton, Rosso, Giamarchi, Phys. Rev. Lett. 95, 180604 (2005) for the
non-equilibrium dynamics of a directed elastic string.


title: Comment on the "extended eikonal" unitarization

abstract:
  This is a comment on the recent paper by O.V. Selyugin, J.-R. Cudell, and E.
Predazzi "Analytic properties of different unitarization schemes" arXiv:
0712.0621v2, [hep-ph]


title: Compressed Text Indexes:From Theory to Practice!

abstract:
  A compressed full-text self-index represents a text in a compressed form and
still answers queries efficiently. This technology represents a breakthrough
over the text indexing techniques of the previous decade, whose indexes
required several times the size of the text. Although it is relatively new,
this technology has matured up to a point where theoretical research is giving
way to practical developments. Nonetheless this requires significant
programming skills, a deep engineering effort, and a strong algorithmic
background to dig into the research results. To date only isolated
implementations and focused comparisons of compressed indexes have been
reported, and they missed a common API, which prevented their re-use or
deployment within other applications.
  The goal of this paper is to fill this gap. First, we present the existing
implementations of compressed indexes from a practitioner's point of view.
Second, we introduce the Pizza&Chili site, which offers tuned implementations
and a standardized API for the most successful compressed full-text
self-indexes, together with effective testbeds and scripts for their automatic
validation and test. Third, we show the results of our extensive experiments on
these codes with the aim of demonstrating the practical relevance of this novel
and exciting technology.


title:
Dynamic probes of quantum spin chains with the Dzyaloshinskii-Moriya
  interaction

abstract:
  We consider the spin-1/2 anisotropic XY chain in a transverse (z) field with
the Dzyaloshinskii-Moriya interaction directed along z-axis in spin space to
examine the effect of the Dzyaloshinskii-Moriya interaction on the zz, xx and
yy dynamic structure factors. Using the Jordan-Wigner fermionization approach
we analytically calculate the dynamic transverse spin structure factor. It is
governed by a two-fermion excitation continuum. We analyze the effect of the
Dzyaloshinskii-Moriya interaction on the two-fermion excitation continuum.
Other dynamic structure factors which are governed by many-fermion excitations
are calculated numerically. We discuss how the Dzyaloshinskii-Moriya
interaction manifests itself in the dynamic properties of the quantum spin
chain at various fields and temperatures.


title:
First results from the OSQAR photon regeneration experiment: No light
  shining through a wall

abstract:
  A new method to amplify the photon-axion conversions in magnetic field is
proposed using a buffer gas at a specific pressure. As a first result, new
bounds for mass and coupling constant for purely laboratory experiments aiming
to detect any hypothetical scalars and pseudo-scalars which can couple to
photons were obtained at 95% confidence level, excluding the PVLAS result newly
disclaimed.


title: Incorporating exchange rate risk into PDs and asset correlations

abstract:
  Intuitively, the default risk of a single borrower is higher when her or his
assets and debt are denominated in different currencies. Additionally, the
default dependence of borrowers with assets and debt in different currencies
should be stronger than in the one-currency case. By combining well-known
models by Merton (1974), Garman and Kohlhagen (1983), and Vasicek (2002) we
develop simple representations of PDs and asset correlations that take into
account exchange rate risk. From these results, consistency conditions can be
derived that link the changes in PD and asset correlation and do not require
knowledge of hard-to-estimate parameters like asset value volatility.


title:
Fulde-Ferrell-Larkin-Ovchinnikov superfluidity in one-dimensional
  optical lattices

abstract:
  Spin-polarized attractive Fermi gases in one-dimensional (1D) optical
lattices are expected to be remarkably good candidates for the observation of
the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase. We model these systems with
an attractive Hubbard model with population imbalance. By means of the
density-matrix renormalization-group method we compute the pairing correlations
as well as the static spin and charge structure factors in the whole range from
weak to strong coupling. We demonstrate that pairing correlations exhibit
quasi-long range order and oscillations at the wave number expected from FFLO
theory. However, we also show by numerically computing the mixed spin-charge
static structure factor that charge and spin degrees of freedom appear to be
coupled already for small imbalance. We discuss the consequences of this
coupling for the observation of the FFLO phase, as well as for the
stabilization of the quasi-long range order into long-range order by coupling
many identical 1D systems, as in quasi-1D optical lattices.


title: {\it Ab--initio} finite temperature excitons

abstract:
  The coupling with the lattice vibrations is shown to drastically modify the
state--of--the--art picture of the excitonic states based on a frozen atom
approximation. The zero--point vibrations renormalize the bare energies and
optical strengths. Excitons acquire a non--radiative lifetime that decreases
with increasing temperature. The optical brightness and efficiency turn out to
be strongly temperature dependent such as to induce bright to dark (and vice
versa) transitions. The finite temperature experimental optical absorption
spectra of bulk Si and hexagonal BN are successfully explained without using
any external parameter.


title:
Probing the fuzzy sphere regularisation in simulations of the 3d \lambda
  \phi^4 model

abstract:
  We regularise the 3d \lambda \phi^4 model by discretising the Euclidean time
and representing the spatial part on a fuzzy sphere. The latter involves a
truncated expansion of the field in spherical harmonics. This yields a
numerically tractable formulation, which constitutes an unconventional
alternative to the lattice. In contrast to the 2d version, the radius R plays
an independent r\^{o}le. We explore the phase diagram in terms of R and the
cutoff, as well as the parameters m^2 and \lambda. Thus we identify the phases
of disorder, uniform order and non-uniform order. We compare the result to the
phase diagrams of the 3d model on a non-commutative torus, and of the 2d model
on a fuzzy sphere. Our data at strong coupling reproduce accurately the
behaviour of a matrix chain, which corresponds to the c=1-model in string
theory. This observation enables a conjecture about the thermodynamic limit.


title: Topics in Hadronic B Decays

abstract:
  We discuss some topics concerning exclusive non-leptonic B decays. In
particular we focus on Bs->KK decays, for which we present complementary
predictions within the SM, as well as the impact that SUSY would have on the CP
observables. We also present an analysis of Bs->VV decays that allows to
measure the mixing angle of the Bs system. We make special emphasis on the
control of hadronic uncertainties.


title:
Comment on the PRL "Large-Scale Monte Carlo Study of a Realistic Lattice
  Model for Ga_(1-x)Mn_xAs"

abstract:
  We comment on the recent paper "Large-Scale Monte Carlo Study of a Realistic
Lattice Model for Ga_(1-x)Mn_xAs" by Y. Yildirim, G. Alvarez, A. Moreo and E.
Dagotto", Phys Rev. Lett.{\bf 99}, 057207 (2007); cond-mat/0612002


title: On some low dimensional quantum groups

abstract:
  This paper is an adaptation of a chapter from an upcoming monograph on
noncommutative geometry and quantum groups. We present examples of non compact
quantum groups which are deformations of low dimensional Lie groups. The paper
is of expository nature and provides both particular examples and some general
procedures for constructing them.


title:
Surprising relations between parametric level correlations and fidelity
  decay

abstract:
  Unexpected relations between fidelity decay and cross form--factor, i.e.,
parametric level correlations in the time domain are found both by a heuristic
argument and by comparing exact results, using supersymmetry techniques, in the
framework of random matrix theory. A power law decay near Heisenberg time, as a
function of the relevant parameter, is shown to be at the root of revivals
recently discovered for fidelity decay. For cross form--factors the revivals
are illustrated by a numerical study of a multiply kicked Ising spin chain.


title: Twisting versus bending in quantum waveguides

abstract:
  We make an overview of spectral-geometric effects of twisting and bending in
quantum waveguides modelled by the Dirichlet Laplacian in an unbounded
three-dimensional tube of uniform cross-section. We focus on the existence of
Hardy-type inequalities in twisted tubes of non-circular cross-section.

categories: math-ph cond-mat.mes-hall math.MP math.SP