title: SIR epidemics in dynamic contact networks

abstract:
  Contact patterns in populations fundamentally influence the spread of
infectious diseases. Current mathematical methods for epidemiological
forecasting on networks largely assume that contacts between individuals are
fixed, at least for the duration of an outbreak. In reality, contact patterns
may be quite fluid, with individuals frequently making and breaking social or
sexual relationships. Here we develop a mathematical approach to predicting
disease transmission on dynamic networks in which each individual has a
characteristic behavior (typical contact number), but the identities of their
contacts change in time. We show that dynamic contact patterns shape
epidemiological dynamics in ways that cannot be adequately captured in static
network models or mass-action models. Our new model interpolates smoothly
between static network models and mass-action models using a mixing parameter,
thereby providing a bridge between disparate classes of epidemiological models.
Using epidemiological and sexual contact data from an Atlanta high school, we
then demonstrate the utility of this method for forecasting and controlling
sexually transmitted disease outbreaks.


title: Scientific citations in Wikipedia

abstract:
  The Internet-based encyclopaedia Wikipedia has grown to become one of the
most visited web-sites on the Internet. However, critics have questioned the
quality of entries, and an empirical study has shown Wikipedia to contain
errors in a 2005 sample of science entries. Biased coverage and lack of sources
are among the "Wikipedia risks". The present work describes a simple assessment
of these aspects by examining the outbound links from Wikipedia articles to
articles in scientific journals with a comparison against journal statistics
from Journal Citation Reports such as impact factors. The results show an
increasing use of structured citation markup and good agreement with the
citation pattern seen in the scientific literature though with a slight
tendency to cite articles in high-impact journals such as Nature and Science.
These results increase confidence in Wikipedia as an good information organizer
for science in general.


title:
Determination of the body force of a two-dimensional isotropic elastic
  body

abstract:
  Let $\Omega$ represent a two$-$dimensional isotropic elastic body. We
consider the problem of determining the body force $F$ whose form
$\phi(t)(f_1(x),f_2(x))$ with $\phi$ be given inexactly. The problem is
nonlinear and ill-posed. Using the Fourier transform, the methods of Tikhonov's
regularization and truncated integration, we construct a regularized solution
from the data given inexactly and derive the explicitly error estimate.
Numerical part is given


title: Method to measure neutron beam polarization with 2x1 Neutron Spin Filter

abstract:
  A method to measure a beam polarization with the use of polarized 3He gas is
discussed. It is shown that special design of the Neutron Spin Filter cell
allows for a fast and accurate measurement. The accuracy of this method is
analyzed.


title: Discontinuity and Involutions on Countable Sets

abstract:
  For any infinite subset $X$ of the rationals and a subset $F \subseteq X$
which has no isolated points in $X$ we construct a function $f: X \to X$ such
that $f(f(x))=x$ for each $x\in X$ and $F $ is the set of discontinuity points
of $f$.


title: Optimal quantization for the pricing of swing options

abstract:
  In this paper, we investigate a numerical algorithm for the pricing of swing
options, relying on the so-called optimal quantization method. The numerical
procedure is described in details and numerous simulations are provided to
assert its efficiency. In particular, we carry out a comparison with the
Longstaff-Schwartz algorithm.


title:
Electrical excitation of shock and soliton-like waves in two-dimensional
  electron channels

abstract:
  We study electrical excitation of nonlinear plasma waves in heterostructures
with two-dimensional electron channels and with split gates, and the
propagation of these waves using hydrodynamic equations for electron transport
coupled with two-dimensional Poisson equation for self-consistent electric
potential. The term related to electron collisions with impurities and phonons
as well as the term associated with viscosity are included into the
hydrodynamic equations. We demonstrate the formation of shock and soliton-like
waves as a result of the evolution of strongly nonuniform initial electron
density distribution. It is shown that the shock wave front and the shape of
soliton-like pulses pronouncedly depend on the coefficient of viscosity, the
thickness of the gate layer and the nonuniformity of the donor distribution
along the channel. The electron collisions result in damping of the shock and
soliton-like waves, while they do not markedly affect the thickness of the
shock wave front.


title:
Algebraically closed real geodesics on n-dimensional ellipsoids are
  dense in the parameter space and related to hyperelliptic tangential
  coverings

abstract:
  The closedness condition for real geodesics on n-dimensional ellipsoids is in
general transcendental in the parameters (semiaxes of the ellipsoid and
constants of motion). We show that it is algebraic in the parameters if and
only if both the real and the imaginary geodesics are closed and we
characterize such double--periodicity condition via real hyperelliptic
tangential coverings. We prove the density of algebraically closed geodesics on
n-dimensional ellipsoids with respect to the natural topology in the
(2n)-dimensional real parameter space. In particular, the approximating
sequence of algebraic closed geodesics on the approximated ellipsoids may be
chosen so to share the same values of the length and of the real period vector
as the limiting closed geodesic on the limiting ellipsoid.
  Finally, for real doubly-periodic geodesics on triaxial ellipsoids, we show
how to evaluate algebraically the period mapping and we present some explicit
examples of families of algebraically closed geodesics.


title:
Scattering amplitudes in strongly coupled N=4 SYM from semiclassical
  strings in AdS

abstract:
  Very recently in arXiv:0705.0303 Alday and Maldacena gave a string theory
prescription for computing (all) planar amplitudes in N=4 supersymmetric gauge
theory at strong coupling using the AdS/CFT correspondence. These amplitudes
are determined by a classical string solution and contain a universal
exponential factor involving the action of the classical string. On the gauge
theory side, expressions for perturbative amplitudes at strong coupling were
previously proposed only for specific helicities of external particles -- the
maximally helicity violating or MHV amplitudes. These follow from the
exponential ansatz of Bern, Dixon and Smirnov for MHV amplitudes in N=4 SYM. In
this paper we examine the amplitudes dependence on helicities and
particle-types of external states. We consider the prefactor of string
amplitudes and give arguments suggesting that the prefactor at strong coupling
should be the same as the Yang-Mills tree-level amplitude for the same process.
This implies that scattering amplitudes in N=4 SYM simplify dramatically in the
strong coupling limit. It follows from our proposal that in this limit all (MHV
and non-MHV) n-point amplitudes are given by the (known) tree-level Yang-Mills
result times the helicity-independent (and particle-type-independent) universal
exponential.


title: Elliptic flow from pQCD + saturation + hydro model

abstract:
  We have previously predicted multiplicities and transverse momentum spectra
of hadrons for the most central LHC Pb+Pb collisions at $\sqrt{s_{NN}}=5.5$ TeV
using initial state for hydrodynamic evolution from pQCD + final state
saturation model. By considering binary collision and wounded nucleon profiles
we extend these studies to non-central collisions, and predict the $p_{T}$
dependence of minimum bias $v_{2}$ for pions at the LHC. For protons we also
show how the $p_{T}$ dependence of $v_2$ changes from RHIC to the LHC.


title: Abell 43: Longest period Planetary Nebula Nucleus variable

abstract:
  Based on 24h high speed photometry of the hybrid PG 1159 star Abell 43, we
have detected 6 sighificant pulsations with periods between 2380 s and 6075 s.
A short (4h) run on the almost spectroscopic twin NGC 7094 central star
resulted in detection of 3 low amplitude pulsations with periods between 2000 s
and 5000 s. The results are close to predictions for g-mode pulsations driven
by the kappa-mechanism induced by the partial ionization of carbon and oxygen.


title: First order phase transitions in classical lattice gas spin models

abstract:
  The present paper considers some classical ferromagnetic lattice--gas models,
consisting of particles that carry $n$--component spins ($n=2,3$) and
associated with a $D$--dimensional lattice ($D=2,3$); each site can host one
particle at most, thus implicitly allowing for hard--core repulsion; the pair
interaction, restricted to nearest neighbors, is ferromagnetic, and site
occupation is also controlled by the chemical potential $\mu$. The models had
previously been investigated by Mean Field and Two--Site Cluster treatments
(when D=3), as well as Grand--Canonical Monte Carlo simulation in the case
$\mu=0$, for both D=2 and D=3; the obtained results showed the same kind of
critical behaviour as the one known for their saturated lattice counterparts,
corresponding to one particle per site. Here we addressed by Grand--Canonical
Monte Carlo simulation the case where the chemical potential is negative and
sufficiently large in magnitude; the value $\mu=-D/2$ was chosen for each of
the four previously investigated counterparts, together with $\mu=-3D/4$ in an
additional instance. We mostly found evidence of first order transitions, both
for D=2 and D=3, and quantitatively characterized their behaviour. Comparisons
are also made with recent experimental results.


title: R & D for Future Zeplin

abstract:
  We propose a new concept for a very low background multi-ton liquid xenon
Dark Matter experiment. The detector consists of two concentric spheres and a
charge readout device in the centre. Xenon between the two spheres forms a
self-shield and veto device. The inner surface of the central sphere is coated
with CsI to form an internal photocathode with minimum of 2\pi coverage for any
event in the active volume. Photoelectrons from the CsI photocathode drift
toward the charge readout micro-structure in the centre of the detector. Both
scintillation and ionisation are measured simultaneously for background
rejection and 3-D event mapping. In addition to external shielding, the low
background is achieved by eliminating PMTs and by using low radioactivity pure
materials throughout the detector. We present detailed calculations of the
charge readout system and design details. The detector is expected to probe the
full SUSY parameter space.


title: TYZ expansion for the Kepler manifold

abstract:
  The main goal of the paper is to address the issue of the existence of
Kempf's distortion function and the Tian-Yau-Zelditch (TYZ) asymptotic
expansion for the Kepler manifold - an important example of non compact
manfold. Motivated by the recent results for compact manifolds we construct
Kempf's distortion function and derive a precise TYZ asymptotic expansion for
the Kepler manifold. We get an exact formula: finite asymptotic expansion of
$n-1$ terms and exponentially small error terms uniformly with respect to the
discrete quantization parameter $m\to \infty $ and $\rho \to \infty$, $\rho$
being the polar radius in $\C^n$.
  Moreover, the coefficents are calculated explicitly and they turned out to be
homogeneous functions with respect to the polar radius in the Kepler manifold.
We also prove and derive an asymptotic expansion of the obtstruction term with
the coefficients being defined by geometrical quantities. We show that our
estimates are sharp by analyzing the nonharmonic behaviour of $T_m$ and the
error term of the approximation of the Fubini--Study metric by $m\omega$ for
$m\to +\infty$. The arguments of the proofs combine geometrical methods,
quantization tools and functional analytic techniques for investigating
asymptotic expansions in the framework of analytic-Gevrey spaces.


title:
Controlled formation of metallic nanowires via Au nanoparticle ac
  trapping

abstract:
  Applying ac voltages, we trapped gold nanoparticles between microfabricated
electrodes under well-defined conditions. We demonstrate that the nanoparticles
can be controllably fused together to form homogeneous gold nanowires with
pre-defined diameters and conductance values. Whereas electromigration is known
to form a gap when a dc voltage is applied, this ac technique achieves the
opposite, thereby completing the toolkit for the fabrication of nanoscale
junctions.


title:
Imaging the cool stars in the interacting binaries AE Aqr, BV Cen and
  V426 Oph

abstract:
  It is well known that magnetic activity in late-type stars increases with
increasing rotation rate. Using inversion techniques akin to medical imaging,
the rotationally broadened profiles from such stars can be used to reconstruct
`Doppler images' of the distribution of cool, dark starspots on their stellar
surfaces. Interacting binaries, however, contain some of the most rapidly
rotating late-type stars known and thus provide important tests of stellar
dynamo models. Furthermore, magnetic activity is thought to play a key role in
their evolution, behaviour and accretion dynamics. Despite this, we know
comparatively little about the magnetic activity and its influence on such
binaries. In this review we summarise the concepts behind indirect imaging of
these systems, and present movies of the starspot distributions on the cool
stars in some interacting binaries. We conclude with a look at the future
opportunities that such studies may provide.


title: Quantum Electrodynamics of qubits

abstract:
  Systematic description of a spin one-half system endowed with magnetic moment
or any other two-level system (qubit) interacting with the quantized
electromagnetic field is developed. This description exploits a close analogy
between a two-level system and the Dirac electron that comes to light when the
two-level system is described within the formalism of second quantization in
terms of fermionic creation and annihilation operators. The analogy enables one
to introduce all the powerful tools of relativistic QED (albeit in a greatly
simplified form). The Feynman diagrams and the propagators turn out to be very
useful. In particular, the QED concept of the vacuum polarization finds its
close counterpart in the photon scattering off a two level-system leading via
the linear response theory to the general formulas for the atomic
polarizability and the dynamic single spin susceptibility. To illustrate the
usefulness of these methods, we calculate the polarizability and susceptibility
up to the fourth order of perturbation theory. These {\em ab initio}
calculations resolve some ambiguities concerning the sign prescription and the
optical damping that arise in the phenomenological treatment. We also show that
the methods used to study two-level systems (qubits) can be extended to
many-level systems (qudits). As an example, we describe the interaction with
the quantized electromagnetic field of an atom with four relevant states: one S
state and three degenerate P states.


title:
Isolated unstable Weibel modes in unmagnetized plasmas with tunable
  asymmetry

abstract:
  In this letter, an initially unmagnetized pair plasma with asymmetric
velocity distributions is investigated where any unstable Weibel mode must be
isolated, with discrete values for the growth rates and the unstable
wavenumbers. For both a non-relativistic distribution with thermal spread and a
high-relativistic two-stream distribution it is shown that isolated modes are
excited and that, as the asymmetry tends to zero, the growth rate remains
finite, as long as the distribution function is not precisely symmetric.


title:
Massive perturbers and the efficient merger of binary massive black
  holes

abstract:
  We show that dynamical relaxation in the aftermath of a galactic merger and
the ensuing formation and decay of a binary massive black hole (MBH), are
dominated by massive perturbers (MPs) such as giant molecular clouds or
clusters. MPs accelerate relaxation by orders of magnitude relative to 2-body
stellar relaxation alone, and efficiently scatter stars into the binary MBH's
orbit. The 3-body star-binary MBH interactions shrink the binary MBH to the
point where energy losses from the emission of gravitational waves (GW) lead to
rapid coalescence. We model this process based on observed and simulated MP
distributions and take into account the decreased efficiency of the star-binary
MBH interaction due to acceleration in the galactic potential. We show that
mergers of gas-rich galactic nuclei lead to binary MBH coalescence well within
the Hubble time. Moreover, lower-mass binary MBHs (<10^8 Msun) require only a
few percent of the typical gas mass in a post-merger nucleus to coalesce in a
Hubble time. The fate of a binary MBH in a gas poor galactic merger is less
certain, although massive stellar structures (e.g. clusters, stellar rings)
could likewise lead to efficient coalescence. These coalescence events are
observable by their strong GW emission. MPs thus increase the cosmic rate of
such GW events, lead to a higher mass deficit in the merged galactic core and
suppress the formation of triple MBH systems and the resulting ejection of MBHs
into intergalactic space.


title: Extremal metrics on Hartogs domains

abstract:
  An $n$-dimensional Hartogs domain $D_F$ with strongly pseudoconvex boundary
can be equipped with a natural \K metric $g_F$. In this paper we prove that if
$g_F$ is an extremal \K metric then $(D_F, g_F)$ is biholomorphically isometric
to the $n$-dimensional complex hyperbolic space.


title:
Parallelized approximation algorithms for minimum routing cost spanning
  trees

abstract:
  We parallelize several previously proposed algorithms for the minimum routing
cost spanning tree problem and some related problems.


title: Improvements to the Psi-SSA representation

abstract:
  Modern compiler implementations use the Static Single Assignment
representation as a way to efficiently implement optimizing algorithms. However
this representation is not well adapted to architectures with a predicated
instruction set. The Psi-SSA representation extends the SSA representation such
that standard SSA algorithms can be easily adapted to an architecture with a
fully predicated instruction set. A new pseudo operation, the Psi operation, is
introduced to merge several conditional definitions into a unique definition.


title:
On the complexity of solving ordinary differential equations in terms of
  Puiseux series

abstract:
  We prove that the binary complexity of solving ordinary polynomial
differential equations in terms of Puiseux series is single exponential in the
number of terms in the series. Such a bound was given by Grigoriev [10] for
Riccatti differential polynomials associated to ordinary linear differential
operators. In this paper, we get the same bound for arbitrary differential
polynomials. The algorithm is based on a differential version of the
Newton-Puiseux procedure for algebraic equations.


title: A tree approach to $p$-variation and to integration

abstract:
  We consider a real-valued path; it is possible to associate a tree to this
path, and we explore the relations between the tree, the properties of
$p$-variation of the path, and integration with respect to the path. In
particular, the fractal dimension of the tree is estimated from the variations
of the path, and Young integrals with respect to the path, as well as integrals
from the rough paths theory, are written as integrals on the tree. Examples
include some stochastic paths such as martingales, L\'evy processes and
fractional Brownian motions (for which an estimator of the Hurst parameter is
given).


title:
An efficient method for calculation of cooling in Lagrange computational
  gas dynamics

abstract:
  A new method for computation of gas cooling for Lagrange approach is
suggested. The method is based on precalculation of cooling law for known
cooling function. Unlike implicit methods, this method is very efficient, it is
an one-step method which is even more accurate than implicit methods of the
same order.


title:
Validity conditions of the direct boundary integral equation for
  exterior problems of plane elasticity

abstract:
  Writing the boundary integral equation for an exterior problem of elasticity
is subordinate so far to hypotheses on the asymptotical behaviour at infinity
of solutions. The sufficient conditions met in the literature are too
restrictive and do not notably cover the case when the loading has a non zero
resultant force. This difficulty can be removed by considering the problem in
displacements relatively to one point located at a finite distance from the
loading. Finally, this auxiliary problem allows widening the conditions of
validity of the usual formulation of the direct integral method.


title: Dark Energy: A Unifying View

abstract:
  Different models of the cosmic substratum which pretend to describe the
present stage of accelerated expansion of the Universe like the $\Lambda$CDM
model or a Chaplygin gas, can be seen as special realizations of a holographic
dark energy cosmology if the option of an interaction between pressurless dark
matter and dark energy is taken seriously. The corresponding interaction
strength parameter plays the role of a cosmological constant. Differences occur
at the perturbative level. In particular, the pressure perturbations are
intrinsically non-adiabatic.


title: Semiclassical approximation with zero velocity trajectories

abstract:
  We present a new semiclassical method that yields an approximation to the
quantum mechanical wavefunction at a fixed, predetermined position. In the
approach, a hierarchy of ODEs are solved along a trajectory with zero velocity.
The new approximation is local, both literally and from a quantum mechanical
point of view, in the sense that neighboring trajectories do not communicate
with each other. The approach is readily extended to imaginary time propagation
and is particularly useful for the calculation of quantities where only local
information is required. We present two applications: the calculation of
tunneling probabilities and the calculation of low energy eigenvalues. In both
applications we obtain excellent agrement with the exact quantum mechanics,
with a single trajectory propagation.


title:
The Exact Solutions to the Gravitational Contraction in Comoving
  Coordinate System

abstract:
  The gravitational collapse of a star is a warmly discussed but still puzzling
problem, which not only involves the dynamics of the gases, but also the subtle
coordinate transformation. In this letter, we give some more detailed
investigation on this problem, and reach the results: (I). The comoving
coordinate system for the stellar system is only compatible with the
zero-pressure free falling particles. (II). For the free falling dust, there
are three kind of solutions respectively corresponding to the oscillating, the
critical and the open trajectories. The solution of Oppenheimer and Snyder is
the critical case. (III). All solutions are exactly derived. There is a new
kind singularity in the solution, but its origin is unclear.


title:
Primordial Neutrinos, Cosmological Perturbations in Interacting
  Dark-Energy Model: CMB and LSS

abstract:
  We present cosmological perturbation theory in neutrinos probe interacting
dark-energy models, and calculate cosmic microwave background anisotropies and
matter power spectrum. In these models, the evolution of the mass of neutrinos
is determined by the quintessence scalar field, which is responsible for the
cosmic acceleration today. We consider several types of scalar field potentials
and put constraints on the coupling parameter between neutrinos and dark
energy. Assuming the flatness of the universe, the constraint we can derive
from the current observation is $\sum m_{\nu} < 0.87 eV$ at the 95 % confidence
level for the sum over three species of neutrinos. We also discuss on the
stability issue of the our model and on the impact of the scattering term in
Boltzmann equation from the mass-varying neutrinos.


title: Ordering phenomena in quasi one-dimensional organic conductors

abstract:
  Low-dimensional organic conductors could establish themselves as model
systems for the investigation of the physics in reduced dimensions. In the
metallic state of a one-dimensional solid, Fermi-liquid theory breaks down and
spin and charge degrees of freedom become separated. But the metallic phase is
not stable in one dimension: as the temperature is reduced, the electronic
charge and spin tend to arrange themselves in an ordered fashion due to strong
correlations. The competition of the different interactions is responsible for
which broken-symmetry ground state is eventually realized in a specific
compound and which drives the system towards an insulating state.
  Here we review the various ordering phenomena and how they can be identified
by optic and magnetic measurements. While the final results might look very
similar in the case of a charge density wave and a charge-ordered metal, for
instance, the physical cause is completely different. When density waves form,
a gap opens in the density of states at the Fermi energy due to nesting of the
one-dimension Fermi surface sheets. When a one-dimensional metal becomes a
charge-ordered Mott insulator, on the other hand, the short-range Coulomb
repulsion localizes the charge on the lattice sites and even causes certain
charge patterns.
  We try to point out the similarities and conceptional differences of these
phenomena and give an example for each of them. Particular emphasis will be put
on collective phenomena which are inherently present as soon as ordering breaks
the symmetry of the system.


title: The Variable Star One-shot Project, and its little child: Wikimbad

abstract:
  The Variable Star One-shot Project (VSOP) aimed at providing to the
world-wide stellar community the necessary one-shot spectrum of unstudied
variable stars, too often classified as such by an analysis of photometric data
only. The VSOP has established an new kind of observational model, where all
steps from observations to spectral analysis, are automatized (or are underway
to be fully automatized). The project is centralized on a collaborative wiki
website. The VSOP operational model is very successful, data is continously
flowing and being analyszed, and VSOP is now a worldwide open collaboration of
people with very different and complementary skills and expertise. The idea of
a central wiki website has been extended by one of us to propose a new service
to the whole astronomical community, called Wikimbad. Wikimbad is an open wiki
website aimed at collecting, organizing and making publicly available all kind
of reduced and published astronomical data. Its strengths and a comparison with
the Virtual Observatory are discussed. See: http://vsop.sc.eso.org and
http://wikimbad.org


title:
Best insertion algorithm for resource-constrained project scheduling
  problem

abstract:
  This paper considers heuristics for well known resource-constrained project
scheduling problem (RCPSP). First a feasible schedule is constructed using
randomized best insertion algorithm. The construction is followed by a local
search where a new solution is generated as follows: first we randomly delete m
activities from the list, which are then reinserted in the list in consecutive
order. At the end of run, the schedule with the minimum makespan is selected.
Experimental work shows very good results on standard test instances found in
PSPLIB


title: Study of the effect of metallicity on the amplitudes of Cepheids

abstract:
  Results concerning the dependence of photometric and radial velocity
amplitudes on metallicity are presented based on about 200 Galactic classical
Cepheids pulsating in the fundamental mode. The Galactic distribution of the
[Fe/H] value of Cepheids is also studied. We show that the photometric
amplitude ratio $A_\mathrm{I}/A_\mathrm{V}$ is independent of metallicity. The
observed dependence of this ratio on the pulsation period does not correspond
to the theoretical predictions.


title: Fuzzy Fluid Mechanics in Three Dimensions

abstract:
  We introduce a rotation invariant short distance cut-off in the theory of an
ideal fluid in three space dimensions, by requiring momenta to take values in a
sphere. This leads to an algebra of functions in position space is
non-commutative. Nevertheless it is possible to find appropriate analogues of
the Euler equations of an ideal fluid. The system still has a hamiltonian
structure. It is hoped that this will be useful in the study of possible
singularities in the evolution of Euler (or Navier-Stokes) equations in three
dimensions.

categories: math-ph cond-mat.stat-mech gr-qc hep-th math.AP math.MP math.QA nlin.CD physics.flu-dyn


title:
Tree-Level Stability Without Spacetime Fermions: Novel Examples in
  String Theory

abstract:
  Is perturbative stability intimately tied with the existence of spacetime
fermions in string theory in more than two dimensions? Type 0'B string theory
in ten-dimensional flat space is a rare example of a non-tachyonic,
non-supersymmetric string theory with a purely bosonic closed string spectrum.
However, all known type 0' constructions exhibit massless NSNS tadpoles
signaling the fact that we are not expanding around a true vacuum of the
theory. In this note, we are searching for perturbatively stable examples of
type 0' string theory without massless tadpoles in backgrounds with a spatially
varying dilaton. We present two examples with this property in non-critical
string theories that exhibit four- and six-dimensional Poincare invariance. We
discuss the D-branes that can be embedded in this context and the type of gauge
theories that can be constructed in this manner. We also comment on the
embedding of these non-critical models in critical string theories and their
holographic (Little String Theory) interpretation and propose a general
conjecture for the role of asymptotic supersymmetry in perturbative string
theory.


title:
k_T factorization is violated in production of high-transverse-momentum
  particles in hadron-hadron collisions

abstract:
  We show that hard-scattering factorization is violated in the production of
high-p_T hadrons in hadron-hadron collisions, in the case that the hadrons are
back-to-back, so that k_T factorization is to be used. The explicit
counterexample that we construct is for the single-spin asymmetry with one beam
transversely polarized. The Sivers function needed here has particular
sensitivity to the Wilson lines in the parton densities. We use a greatly
simplified model theory to make the breakdown of factorization easy to check
explicitly. But the counterexample implies that standard arguments for
factorization fail not just for the single-spin asymmetry but for the
unpolarized cross section for back-to-back hadron production in QCD in
hadron-hadron collisions. This is unlike corresponding cases in e^+e^-
annihilation, Drell-Yan, and deeply inelastic scattering. Moreover, the result
endangers factorization for more general hadroproduction processes.


title:
Nonequilibrium critical relaxation at a first-order phase transition
  point

abstract:
  We study numerically the nonequilibrium dynamical behavior of an Ising model
with mixed two-spin and four-spin interactions after a sudden quench from the
high-temperature phase to the first-order phase transition point. The
autocorrelation function is shown to approach its limiting value, given by the
magnetization in the ordered phase at the transition point, m_c, through a
stretched exponential decay. On the other hand relaxation of the magnetization
starting with an uncorrelated initial state with magnetization, m_i, approaches
either m_c, for m_i>0.5, or zero, for m_i<0.5. For small m_i and for m_i
slightly larger than 0.5 the relaxation of the magnetization shows an
asymptotic power-law time dependence, thus from a nonequilibrium point of view
the transition is continuous.


title: Inverted and mirror repeats in model nucleotide sequences

abstract:
  We analytically and numerically study the probabilistic properties of
inverted and mirror repeats in model sequences of nucleic acids. We consider
both perfect and non-perfect repeats, i.e. repeats with mismatches and gaps.
The considered sequence models are independent identically distributed (i.i.d.)
sequences, Markov processes and long range sequences. We show that the number
of repeats in correlated sequences is significantly larger than in i.i.d.
sequences and that this discrepancy increases exponentially with the repeat
length for long range sequences.


title: The Copenhagen interpretation, and pragmatism

abstract:
  In the past both instrumentalism and empiricism have inspired certain
pragmatic elements into the Copenhagen interpretation of quantum mechanics. The
relation of such pragmatisms with the correspondence principle is discussed. It
is argued that neither Bohr nor Heisenberg did take `correspondence' in one of
these forms, and that it, in particular, was Bohr's classical attitude which
caused him to apply in an inconsistent way his correspondence principle to the
Einstein-Podolsky-Rosen experiment, thus causing much confusion. It is
demonstrated that an empiricist pragmatism is conducive to an explanation of
violation of the Bell inequalities as a consequence of `complementarity' in the
sense of `mutual disturbance in a joint nonideal measurement of incompatible
observables' rather than as being caused by `nonlocal influences'.


title: Elementary transformation analysis for Array-OL

abstract:
  Array-OL is a high-level specification language dedicated to the definition
of intensive signal processing applications. Several tools exist for
implementing an Array-OL specification as a data parallel program. While
Array-OL can be used directly, it is often convenient to be able to deduce part
of the specification from a sequential version of the application. This paper
proposes such an analysis and examines its feasibility and its limits.


title:
A Short Review of Time Dependent Solutions and Space-like Singularities
  in String Theory

abstract:
  These lecture notes provide a short review of the status of time dependent
backgrounds in String theory, and in particular those that contain space-like
singularities. Despite considerable efforts, we do not have yet a full and
compelling picture of such backgrounds. We review some of the various attempts
to understand these singularities via generalizations of the BKL dynamics,
using worldsheet methods and using non-perturbative tools such as the AdS/CFT
correspondence and M(atrix) theory. These lecture notes are based on talks
given at Cargese 06 and the dead-sea conference 06.


title: On the freezing of variables in random constraint satisfaction problems

abstract:
  The set of solutions of random constraint satisfaction problems (zero energy
groundstates of mean-field diluted spin glasses) undergoes several structural
phase transitions as the amount of constraints is increased. This set first
breaks down into a large number of well separated clusters. At the freezing
transition, which is in general distinct from the clustering one, some
variables (spins) take the same value in all solutions of a given cluster. In
this paper we study the critical behavior around the freezing transition, which
appears in the unfrozen phase as the divergence of the sizes of the
rearrangements induced in response to the modification of a variable. The
formalism is developed on generic constraint satisfaction problems and applied
in particular to the random satisfiability of boolean formulas and to the
coloring of random graphs. The computation is first performed in random tree
ensembles, for which we underline a connection with percolation models and with
the reconstruction problem of information theory. The validity of these results
for the original random ensembles is then discussed in the framework of the
cavity method.

categories: cond-mat.stat-mech cond-mat.dis-nn cs.CC math.PR


title: Predictability, entropy and information of infinite transformations

abstract:
  We show that a certain type of quasi finite, conservative, ergodic, measure
preserving transformation always has a maximal zero entropy factor, generated
by predictable sets. We also construct a conservative, ergodic, measure
preserving transformation which is not quasi finite; and consider distribution
asymptotics of information showing that e.g. for Boole's transformation,
information is asymptotically mod-normal with square root normalization. Lastly
we see that certain ergodic, probability preserving transformations with zero
entropy have analogous properties and consequently entropy dimension of at most
1/2.


title: Entropy Function for Non-extremal D1D5 and D2D6NS5-branes

abstract:
  We apply the entropy function formalism to non-extremal D1D5 and
D2D6NS5-branes whose throat approximation is given by the Schwarzschild black
hole in AdS_3\times S^3\times T^4 and AdS_3\times S^2\times S^1\times T^4,
respectively. We find the Bekenstein-Hawking entropy and the (alpha')^3R^4
corrections from the value of the entropy function at its saddle point. While
the higher derivative terms have no effect on the temperature, they decrease
the value of the entropy.


title: Thresholds for Intersecting D-branes Revisited

abstract:
  Gauge threshold corrections for intersecting D6-brane string models on
toroidal orbifold backgrounds are reconsidered. Both by dimensionally
regularising the appearing open string one-loop diagrams in tree-channel as
well as by zeta-function regularisation of the corresponding loop-channel
one-loop diagrams, we arrive at a result which takes into account the infrared
divergence from the contribution of the massless states in the running of the
gauge coupling constant as well as the contribution of states, which become
light in certain regions of the moduli space.


title:
Astrophysical S-factor of the 3He(alpha,gamma)7Be reaction measured at
  low energy via prompt and delayed gamma detection

abstract:
  Solar neutrino fluxes depend both on astrophysical and on nuclear physics
inputs, namely on the cross sections of the reactions responsible for neutrino
production inside the Solar core. While the flux of solar 8B neutrinos has been
recently measured at Superkamiokande with a 3.5% uncertainty and a precise
measurement of 7Be neutrino flux is foreseen in the next future, the predicted
fluxes are still affected by larger errors. The largest nuclear physics
uncertainty to determine the fluxes of 8B and 7Be neutrinos comes from the
3He(alpha,gamma)7Be reaction. The uncertainty on its S-factor is due to an
average discrepancy in results obtained using two different experimental
approaches: the detection of the delayed gamma rays from 7Be decay and the
measurement of the prompt gamma emission. Here we report on a new high
precision experiment performed with both techniques at the same time. Thanks to
the low background conditions of the Gran Sasso LUNA accelerator facility, the
cross section has been measured at Ecm = 170, 106 and 93 keV, the latter being
the lowest interaction energy ever reached.
  The S-factors from the two methods do not show any discrepancy within the
experimental errors. An extrapolated S(0)= 0.560+/-0.017 keV barn is obtained.
Moreover, branching ratios between the two prompt gamma-transitions have been
measured with 5-8% accuracy.


title:
Towards a library of synthetic galaxy spectra and preliminary results of
  classification and parametrization of unresolved galaxies for Gaia

abstract:
  Aims:The Gaia astrometric survey mission will, as a consequence of its
scanning law, obtain low resolution optical (330-1000 nm) spectrophotometry of
several million unresolved galaxies brighter than V=22. We present the first
steps in a project to design and implement a classification system for these
data. The goal is both to determine morphological classes and to estimate
intrinsic astrophysical parameters via synthetic templates. Here we describe
(1) a new library of synthetic galaxy spectra, and (2) first results of
classification and parametrization experiments using simulated Gaia
spectrophotometry of this library. Methods:We have created a large grid of
synthetic galaxy spectra using the PEGASE.2 code, which is based on galaxy
evolution models that take into account metallicity evolution, extinction
correction, emission lines (with stellar spectra based on the BaSeL library).
Our classification and regression models are Support Vector Machines (SVMs),
which are kernel-based nonlinear estimators. Results:We produce a basic library
of about 4000 zero redshift galaxy spectra covering the main Hubble types over
wavelength range 250 to 1050 nm at a sampling of 1 nm or less. It is computed
on a regular grid of four key astrophysical parameters for each type and for
intermediate random values of the same parameters. An extended library
reproduces this at a series of redshifts. Initial results from the SVM
classifiers and parametrizers are promising, indicating that Hubble types can
be reliably predicted and several parameters estimated with low bias and
variance. Comparing the colours of our synthetic library with Sloan Digital Sky
Survey (SDSS) spectra we find good agreement over the full range of Hubble
types and parameters.


title: A natural renormalizable model of metastable SUSY breaking

abstract:
  We propose a model of metastable dynamical supersymmetry breaking in which
all scales are generated dynamically. Our construction is a simple variant of
the Intriligator-Seiberg-Shih model, with quark masses induced by
renormalizable couplings to an auxiliary supersymmetric QCD sector. Since all
scales arise from dimensional transmutation, the model has no fundamental
dimensionful parameters. It also does not rely on higher-dimensional operators.


title: Heavy ion physics with the ALICE experiment at LHC

abstract:
  ALICE is the experiment at the LHC collider at CERN dedicated to heavy ion
physics. In this report, the ALICE detector will be presented, together with
its expected performance as far as some selected physics topics are concerned.


title:
Monogamy of entanglement as a necessary and sufficient condition for
  safe QKD in any physical theory

abstract:
  We show that the monogamy of entanglement is a sufficient phenomenon in every
physical theory, if the quantum key distribution is to be safe on the grounds
of such theory. To do so we present the QKD protocol that is safe in any
physical theory under the assumption of the monogamous entanglement only. The
necessity of this condition is also discussed.


title: Distributions vectorielles homog\`enes sur une alg\`ebre de Jordan

abstract:
  We study distributions on a Euclidean Jordan algebra V with values in a
finite dimensional representation space for the identity component G of the
structure group of V and homogeneous equivariance condition. We show that such
distributions exist if and only if the representation is spherical, and that
then the dimension of the space of these distributions is r+1 (where r is the
rank of V). We give also construction of these distributions and of those that
are invariant under the semi-simple part of G.


title: A Study of B0 to rho+rho- Decays and Constraints on the CKM Angle alpha

abstract:
  We present results from an analysis of B0 to rho+rho- decays using 383.6
million BB-bar pairs collected by the BaBar detector at the PEP-II
asymmetric-energy B Factory at SLAC. The measurements of the B0 to rho+rho-
branching fraction, longitudinal polarization fraction f_L, and the
CP-violating parameters S_{long} and C_{long} are:
  B(B0-> rho+rho-) = (25.5 +/- 2.1 (stat) +3.6/-3.9 (syst))*10^-6 f_L = 0.992
+/- 0.024 (stat) +0.026/-0.013 (syst) S_{long} = -0.17 +/- 0.20 (stat)
+0.05/-0.06 (syst) C_{long} = 0.01 +/- 0.15 (stat) +/- 0.06 (syst) We determine
the unitarity triangle angle alpha, using an isospin analysis of B to rhorho
decays. One of the two solutions, alpha = [73.1, 117.0] degrees at 68% CL is
compatible with standard model-based fits of existing data. Constraints on the
unitarity triangle are also evaluated using an SU(3) symmetry based approach.


title: Gerby Localization, Z_3-Hodge Integrals and the GW Theory of C^3/Z_3

abstract:
  We exhibit a set of recursive relations that completely determine all
equivariant Gromov-Witten invariants of the quotient orbifold C^3/Z_3. We
interpret such invariants as G-Hodge Integrals, and produce relations among
them via Atiyah-Bott localization on moduli spaces of twisted stable maps to
gerbes over the projective line.


title: Density functional theory study of (OCS)2^-

abstract:
  The structural and electronic properties of the carbonyl sulfide dimer anion
are calculated using density functional theory within a pseudopotential method.
Three geometries are optimized and investigated: C2v and C2 symmetric, as well
as one asymmetric structure. A distribution of an excess charge in three
isomers are studied by the Hirshfeld method. In an asymmetric (OCS)2^- isomer
the charge is not equally divided between the two moieties, but it is
distributed as OCS^{-0.6} OCS^{-0.4}. Low-lying excitation levels of three
isomers are compared using the time-dependent density functional theory in the
Casida approach.


title: Quantum cohomology of [C^N/\mu_r]

abstract:
  We give a construction of the moduli space of stable maps to the classifying
stack B\mu_r of a cyclic group by a sequence of r-th root constructions on
M_{0, n}. We prove a closed formula for the total Chern class of
\mu_r-eigenspaces of the Hodge bundle, and thus of the obstruction bundle of
the genus zero Gromov-Witten theory of stacks of the form [C^N/\mu_r].
  We deduce linear recursions for all genus-zero Gromov-Witten invariants.


title:
Self-consistency over the charge-density in dynamical mean-field theory:
  a linear muffin-tin implementation and some physical implications

abstract:
  We present a simple implementation of the dynamical mean-field theory
approach to the electronic structure of strongly correlated materials. This
implementation achieves full self-consistency over the charge density, taking
into account correlation-induced changes to the total charge density and
effective Kohn-Sham Hamiltonian. A linear muffin-tin orbital basis-set is used,
and the charge density is computed from moments of the many body
momentum-distribution matrix. The calculation of the total energy is also
considered, with a proper treatment of high-frequency tails of the Green's
function and self-energy. The method is illustrated on two materials with
well-localized 4f electrons, insulating cerium sesquioxide Ce2O3 and the
gamma-phase of metallic cerium, using the Hubbard-I approximation to the
dynamical mean-field self-energy. The momentum-integrated spectral function and
momentum-resolved dispersion of the Hubbard bands are calculated, as well as
the volume-dependence of the total energy. We show that full self-consistency
over the charge density, taking into account its modification by strong
correlations, can be important for the computation of both thermodynamical and
spectral properties, particularly in the case of the oxide material.


title: Separability of entangled qutrits in noisy channels

abstract:
  We present an analysis of noisy atomic channels involving qutrits. We choose
a three-level atom with V-configuration to be the qutrit state. Gell-Mann
matrices and a generalized Bloch vector (8-dimensional) are used to describe
the qutrit density operator. We introduce quantum quasi-distributions for
qutrits that provide a simple description of entanglement. Studying the
time-evolution for the atomic variables we find the Kraus representation of
spontaneous emission quantum channel (SE channel). Furthermore, we consider a
generalized Werner state of two qutrits and investigate the separability
condition in the presence of spontaneous emission noise. The influence of
spontaneous emission on the separability of Werner states for qutrit and qubit
states is compared.


title:
Tight binding formulation of the dielectric response in semiconductor
  nanocrystals

abstract:
  We report on a theoretical derivation of the electronic dielectric response
of semiconductor nanocrystals using a tight-binding framework. Extending to the
nanoscale the Hanke and Sham approach [Phys. Rev. B 12, 4501 (1975)] developed
for bulk semiconductors, we show how local field effects can be included in the
study of confined systems. A great advantage of this scheme is that of being
formulated in terms of localized orbitals and thus it requires very few
computational resources and times. Applications to the optical and screening
properties of semiconductor nanocrystals are presented here and discussed.
Results concerning the absorption cross section, the static polarizability and
the screening function of InAs (direct gap) and Si (indirect gap) nanocrystals
compare well to both first principles results and experimental data. We also
show that the present scheme allows us to easily go beyond the continuum
dielectric model, based on the Clausius-Mossotti equation, which is frequently
used to include the nanocrystal surface polarization. Our calculations indicate
that the continuum dielectric model, used in conjunction with a size dependent
dielectric constant, underestimates the nanocrystal polarizability, leading to
exceedingly strong surface polarization fields.


title:
Post-Oligarchic Evolution of Protoplanetary Embryos and the Stability of
  Planetary Systems

abstract:
  We investigate the orbit-crossing time (T_c) of protoplanet systems both with
and without a gas-disk background. The protoplanets are initially with equal
masses and separation (EMS systems) scaled by their mutual Hill's radii. In a
gas-free environment, we find log (T_c/yr) = A+B \log (k_0/2.3). Through a
simple analytical approach, we demonstrate that the evolution of the velocity
dispersion in an EMS system follows a random walk. The stochastic nature of
random-walk diffusion leads to (i) an increasing average eccentricity <e> ~
t^1/2, where t is the time; (ii) Rayleigh-distributed eccentricities
(P(e,t)=e/\sigma^2 \exp(-e^2/(2\sigma^2)) of the protoplanets; (iii) a
power-law dependence of T_c on planetary separation. As evidence for the
chaotic diffusion, the observed eccentricities of known extra solar planets can
be approximated by a Rayleigh distribution. We evaluate the isolation masses of
the embryos, which determine the probability of gas giant formation, as a
function of the dust and gas surface densities.


title: Local dynamics for fibered holomorphic transformations

abstract:
  Fibered holomorphic dynamics are skew-product transformations over an
irrational rotation, whose fibers are holomorphic functions. In this paper we
study such a dynamics on a neighborhood of an invariant curve. We obtain some
results analogous to the results in the non fibered case.


title: Ultimate Fate of our Universe from Quantum Mechanics

abstract:
  It is conjectured that time intervals of any kind are proportional to the age
of the Universe taken at the time we are considering the interval. If this is
the case then the speed of light, in fact any speed, must decrease inversely
proportional to this age. The immediate consequence is that energy is not
conserved: the hypothesis that time is a homogeneous property implies
conservation of energy (the theorem of Noether). Nonconservation of energy
follows from the condition that any time interval is proportional to the
cosmological time, and therefore time can not be homogeneous. From the
uncertainty principle, taking the constant of Planck as a real constant, time
independent, it follows that any energy in the Universe decreases linearly with
time. We then prove that Schroedinger equation does not change, except for the
potential energy term. The future of the Universe gives for the wave functions
a long sinusoidal spatial solution, so that everything becomes unlocalized. The
relativistic absolute interval remains the same, even with a changing speed of
light, and the Universe turns out to be nonexpanding. A Mass-Boom effect is
confirmed.


title: The Nuclear Spin Nanomagnet

abstract:
  Linearly polarized light tuned slightly below the optical transition of the
negatively charged exciton (trion) in a single quantum dot causes the
spontaneous nuclear spin polarization (self-polarization) at a level close to
100%. The effective magnetic field of spin-polarized nuclei brings the optical
transition energy into resonance with photon energy. The resonantly enhanced
Overhauser effect sustains the stability of the nuclear self-polarization even
in the absence of spin polarization of the quantum dot electron. As a result
the optically selected single quantum dot represents a tiny magnet with the
ferromagnetic ordering of nuclear spins - the nuclear spin nanomagnet.


title: Multiplicity one Conjectures

abstract:
  In the first part, in the local non archimedean case, we consider
distributions on GL(n+1) which are invariant under the adjoint action of GL(n).
We conjecture that such distributions are invariant by transposition. This
would imply multiplicity at most one for restrictions from GL(n+1) to GL(n). We
reduce ourselves to distributions with "singular" support and then finish the
proof for n< 9.
  In the second part we show that similar Theorems for orthogonal or unitary
groups follow from the case of GL(n)


title:
Collective states of the odd-mass nuclei within the framework of the
  Interacting Vector Boson Model

abstract:
  A supersymmetric extension of the dynamical symmetry group $Sp^{B}(12,R)$ of
the Interacting Vector Boson Model (IVBM), to the orthosymplectic group
$OSp(2\Omega/12,R)$ is developed in order to incorporate fermion degrees of
freedom into the nuclear dynamics and to encompass the treatment of odd mass
nuclei. The bosonic sector of the supergroup is used to describe the complex
collective spectra of the neighboring even-even nuclei and is considered as a
core structure of the odd nucleus. The fermionic sector is represented by the
fermion spin group $SO^{F}(2\Omega)\supset SU^{F}(2)$.
  The so obtained, new exactly solvable limiting case is applied for the
description of the nuclear collective spectra of odd mass nuclei. The
theoretical predictions for different collective bands in three odd mass
nuclei, namely $^{157}Gd$, $^{173}Yb$ and $^{163}Dy$ from rare earth region are
compared with the experiment. The $B(E2)$ transition probabilities for the
$^{157}Gd$ and $^{163}Dy$ between the states of the ground band are also
studied. The important role of the symplectic structure of the model for the
proper reproduction of the $B(E2)$ behavior is revealed. The obtained results
reveal the applicability of the models extension.


title: Sequential mechanism design

abstract:
  In the customary VCG (Vickrey-Clarke-Groves) mechanism truth-telling is a
dominant strategy. In this paper we study the sequential VCG mechanism and show
that other dominant strategies may then exist. We illustrate how this fact can
be used to minimize taxes using examples concerned with Clarke tax and public
projects.


title:
Discovery of a Ringlike Dark Matter Structure in the Core of the Galaxy
  Cluster Cl 0024+17

abstract:
  We present a comprehensive mass reconstruction of the rich galaxy cluster Cl
0024+17 at z~0.4 from ACS data, unifying both strong- and weak-lensing
constraints. The weak-lensing signal from a dense distribution of background
galaxies (~120 per square arcmin) across the cluster enables the derivation of
a high-resolution parameter-free mass map. The strongly-lensed objects tightly
constrain the mass structure of the cluster inner region on an absolute scale,
breaking the mass-sheet degeneracy. The mass reconstruction of Cl 0024+17
obtained in such a way is remarkable. It reveals a ringlike dark matter
substructure at r~75" surrounding a soft, dense core at r~50". We interpret
this peculiar sub-structure as the result of a high-speed line-of-sight
collision of two massive clusters 1-2 Gyr ago. Such an event is also indicated
by the cluster velocity distribution. Our numerical simulation with purely
collisionless particles demonstrates that such density ripples can arise by
radially expanding, decelerating particles that originally comprised the
pre-collision cores. Cl 0024+17 can be likened to the bullet cluster 1E0657-56,
but viewed $along$ the collision axis at a much later epoch. In addition, we
show that the long-standing mass discrepancy for Cl 0024+17 between X-ray and
lensing can be resolved by treating the cluster X-ray emission as coming from a
superposition of two X-ray systems. The cluster's unusual X-ray surface
brightness profile that requires a two isothermal sphere description supports
this hypothesis.


title:
Dominant aerosol processes during high-pollution episodes over Greater
  Tokyo

abstract:
  This paper studies two high-pollution episodes over Greater Tokyo: 9 and 10
December 1999, and 31 July and 1 August 2001. Results obtained with the
chemistry-transport model (CTM) Polair3D are compared to measurements of
inorganic PM2.5. To understand to which extent the aerosol processes modeled in
Polair3D impact simulated inorganic PM2.5, Polair3D is run with different
options in the aerosol module, e.g. with/without heterogeneous reactions. To
quantify the impact of processes outside the aerosol module, simulations are
also done with another CTM (CMAQ). In the winter episode, sulfate is mostly
impacted by condensation, coagulation, long-range transport, and deposition to
a lesser extent. In the summer episode, the effect of long-range transport
largely dominates. The impact of condensation/evaporation is dominant for
ammonium, nitrate and chloride in both episodes. However, the impact of the
thermodynamic equilibrium assumption is limited. The impact of heterogeneous
reactions is large for nitrate and ammonium, and taking heterogeneous reactions
into account appears to be crucial in predicting the peaks of nitrate and
ammonium. The impact of deposition is the same for all inorganic PM2.5. It is
small compared to the impact of other processes although it is not negligible.
The impact of nucleation is negligible in the summer episode, and small in the
winter episode. The impact of coagulation is larger in the winter episode than
in the summer episode, because the number of small particles is higher in the
winter episode as a consequence of nucleation.


title: Note on exponential families of distributions

abstract:
  We show that an arbitrary probability distribution can be represented in
exponential form. In physical contexts, this implies that the equilibrium
distribution of any classical or quantum dynamical system is expressible in
grand canonical form.


title:
Nonhomogeneous magnetization and superconductivity in
  superconductor-ferromagnet structures

abstract:
  We study two different superconductor-ferromagnet (S/F) structures. We
consider first a Josephson junction which consists of two S/F bilayers
separated by an insulating layer. We show that for an antiparallel alignment of
the magnetization in the two F layers the Josephson critical current $I_c$
increases with increasing exchange field $h$. The second system we consider is
a S/F structure with a local inhomogeneity of the magnetization in the
ferromagnet near the S/F interface. Due to the proximity effect not only a
singlet but also a triplet component of the superconducting condensate is
induced in the ferromagnet. The latter penetrates over the length
$\sqrt{D/\epsilon}$ ($D$ is the diffusion coefficient and $\epsilon$ the
energy). In the case of temperatures of the order of the Thouless energy this
length is comparable to the length of the ferromagnet. This long-range
penetration leads to a significant increase of the ferromagnet conductance
below the superconducting critical temperature $T_c$. Contrary to the case of
the singlet component, the contribution to the conductance due to the odd
triplet component is not zero at $T = 0$ and $V = 0$ ($V$ is the voltage) and
decays with increasing temperature T in a monotonic way


title: Progress in Lattice QCD at finite temperature

abstract:
  I review recent developements in lattice QCD at finite temperature, including
the determination of the transition temperature T_c, equation of state and
diffenet static screening lengths. The lattice data suggest that at
temperatures above 1.5T_c the quark gluon plasma can be considered as gas
consisting of quarks and gluons.


title: Gravitational particle production in braneworld cosmology

abstract:
  Gravitational particle production in time variable metric of an expanding
universe is efficient only when the Hubble parameter $H$ is not too small in
comparison with the particle mass. In standard cosmology, the huge value of the
Planck mass $M_{Pl}$ makes the mechanism phenomenologically irrelevant. On the
other hand, in braneworld cosmology the expansion rate of the early universe
can be much faster and many weakly interacting particles can be abundantly
created. Cosmological implications are discussed.


title: Resonant Cooling of Nuclear Spins in Quantum Dots

abstract:
  We propose to use the spin-blockade regime in double quantum dots to reduce
nuclear spin polarization fluctuations in analogy with optical Doppler cooling.
The Overhauser shift brings electron levels in and out of resonance, creating
feedback to suppress fluctuations. Coupling to the disordered nuclear spin
background is a major source of noise and dephasing in electron spin
measurements in such systems. Estimates indicate that a better than 10-fold
reduction of fluctuations is possible.


title:
Skinner-Rusk Unified Formalism for Optimal Control Systems and
  Applications

abstract:
  A geometric approach to time-dependent optimal control problems is proposed.
This formulation is based on the Skinner and Rusk formalism for Lagrangian and
Hamiltonian systems. The corresponding unified formalism developed for optimal
control systems allows us to formulate geometrically the necessary conditions
given by Pontryagin's Maximum Principle, provided that the differentiability
with respect to controls is assumed and the space of controls is open.
Furthermore, our method is also valid for implicit optimal control systems and,
in particular, for the so-called descriptor systems (optimal control problems
including both differential and algebraic equations).


title:
Limits of Hypergraphs, Removal and Regularity Lemmas. A Non-standard
  Approach

abstract:
  We study the integral and measure theory of the ultraproduct of finite sets.
As a main application we construct limit objects for hypergraph sequences. We
give a new proof for the Hypergraph Removal Lemma and the Hypergraph Regularity
Lemma.


title:
Observation of Electron-Hole Puddles in Graphene Using a Scanning Single
  Electron Transistor

abstract:
  The electronic density of states of graphene is equivalent to that of
relativistic electrons. In the absence of disorder or external doping the Fermi
energy lies at the Dirac point where the density of states vanishes. Although
transport measurements at high carrier densities indicate rather high
mobilities, many questions pertaining to disorder remain unanswered. In
particular, it has been argued theoretically, that when the average carrier
density is zero, the inescapable presence of disorder will lead to electron and
hole puddles with equal probability. In this work, we use a scanning single
electron transistor to image the carrier density landscape of graphene in the
vicinity of the neutrality point. Our results clearly show the electron-hole
puddles expected theoretically. In addition, our measurement technique enables
to determine locally the density of states in graphene. In contrast to
previously studied massive two dimensional electron systems, the kinetic
contribution to the density of states accounts quantitatively for the measured
signal. Our results suggests that exchange and correlation effects are either
weak or have canceling contributions.


title:
Growth control of GaAs nanowires using pulsed laser deposition with
  arsenic over pressure

abstract:
  Using pulsed laser ablation with arsenic over pressure, the growth conditions
for GaAs nanowires have been systematically investigated and optimized. Arsenic
over pressure with As$_2$ molecules was introduced to the system by thermal
decomposition of polycrystalline GaAs to control the stoichiometry and shape of
the nanowires during growth. GaAs nanowires exhibit a variety of geometries
under varying arsenic over pressure, which can be understood by different
growth processes via vapor-liquid-solid mechanism. Single-crystal GaAs
nanowires with uniform diameter, lengths over 20 $\mu$m, and thin surface oxide
layer were obtained and can potentially be used for further electronic
characterization.


title: Rational functions with linear relations

abstract:
  We find all polynomials f,g,h over a field K such that g and h are linear and
f(g(x))=h(f(x)). We also solve the same problem for rational functions f,g,h,
in case the field K is algebraically closed.


title: On Resonant Leptogenesis

abstract:
  It has been recently shown that the quantum Boltzmann equations may be
relevant for the leptogenesis scenario. In particular, they lead to a
time-dependent CP asymmetry which depends upon the previous dynamics of the
system. This memory effect in the CP asymmetry is particularly important in
resonant leptogenesis where the asymmetry is generated by the decays of nearly
mass-degenerate right-handed neutrinos. We study the impact of the nontrivial
time evolution of the CP asymmetry in resonant leptogenesis, both in the
one-flavour case and with flavour effects included. We show that significant
qualitative and quantitative differences arise with respect to the case in
which the time dependence of the CP asymmetry is neglected.


title:
A remarkable moduli space of rank 6 vector bundles related to cubic
  surfaces

abstract:
  We study the moduli space $\fM^s(6;3,6,4)$ of simple rank 6 vector bundles
$\E$ on $\PP^3$ with Chern polynomial $1+3t+6t^2+4t^3$ and properties of these
bundles, especially we prove some partial results concerning their stability.
We first recall how these bundles are related to the construction of sextic
nodal surfaces in $\PP^3$ having an even set of 56 nodes (cf. \cite{CaTo}). We
prove that there is an open set, corresponding to the simple bundles with
minimal cohomology, which is irreducible of dimension 19 and bimeromorphic to
an open set $\fA^0$ of the G.I.T. quotient space of the projective space
$\fB:=\{B\in \PP(U^\vee\otimes W\otimes V^\vee)\}$ of triple tensors of type
$(3,3,4)$ by the natural action of $SL(W)\times SL(U)$. We give several
constructions for these bundles, which relate them to cubic surfaces in 3-space
$\PP^3$ and to cubic surfaces in the dual space $(\PP^3)^{\vee}$. One of these
constructions, suggested by Igor Dolgachev, generalizes to other types of
tensors. Moreover, we relate the socalled {\em cross-product involution} for
$(3,3,4)$-tensors, introduced in \cite{CaTo}, with the Schur quadric associated
to a cubic surface in $\PP^3$ and study further properties of this involution.


title:
Evolution of Large Scale Curvature Fluctuations During the Perturbative
  Decay of the Inflaton

abstract:
  We study the evolution of cosmological fluctuations during and after
inflation driven by a scalar field coupled to a perfect fluid through afriction
term. During the slow-roll regime for the scalar field, the perfect fluid is
also frozen and isocurvature perturbations are generated. After the end of
inflation, during the decay of the inflaton, we find that a change in the
observationally relevant large scale curvature fluctuations is possible.


title: The Gorenstein Colength of an Artinian Local Ring

abstract:
  In this paper, we make the notion of approximating an Artinian local ring by
a Gorenstein Artin local ring precise using the concept of Gorenstein colength.
We also answer the question as to when the Gorenstein colength is at most two.


title:
Coulomb blockade as a probe for non-Abelian statistics in Read-Rezayi
  states

abstract:
  We consider a quantum dot in the regime of the quantum Hall effect,
particularly in Laughlin states and non-Abelian Read-Rezayi states. We find the
location of the Coulomb blockade peaks in the conductance as a function of the
area of the dot and the magnetic field. When the magnetic field is fixed and
the area of the dot is varied, the peaks are equally spaced for the Laughlin
states. In contrast, non-Abelian statistics is reflected in modulations of the
spacing which depend on the magnetic field.


title: Multiresolution wavelet analysis of integer scale Bessel functions

abstract:
  We identify multiresolution subspaces giving rise via Hankel transforms to
Bessel functions. They emerge as orthogonal systems derived from geometric
Hilbert-space considerations, the same way the wavelet functions from a
multiresolution scaling wavelet construction arise from a scale of Hilbert
spaces. We study the theory of representations of the $C^{\ast}$-algebra $%
O_{\nu +1}$ arising from this multiresolution analysis. A connection with
Markov chains and representations of $O_{\nu +1}$ is found. Projection valued
measures arising from the multiresolution analysis give rise to a Markov trace
for quantum groups $SO_q$.


title: Combinatorial Hopf algebras and K-homology of Grassmanians

abstract:
  Motivated by work of Buch on set-valued tableaux in relation to the K-theory
of the Grassmannian, we study six combinatorial Hopf algebras. These Hopf
algebras can be thought of as K-theoretic analogues of the by now classical
``square'' of Hopf algebras consisting of symmetric functions, quasisymmetric
functions, noncommutative symmetric functions and the Malvenuto-Reutenauer Hopf
algebra of permutations. In addition, we develop a theory of set-valued
P-partitions and study three new families of symmetric functions which are
weight generating functions of reverse plane partitions, weak set-valued
tableaux and valued-set tableaux.


title:
Experimental Constraints on Higgs Boson Decays to TeV-scale Right-Handed
  Neutrinos

abstract:
  The existence of neutrino masses strongly suggests that right-handed
neutrinos exist, but the data do not favor any particular scale for the
Majorana mass parameters. Here I explore the possibility that these particles
exist at the electroweak scale along with additional new physics at the TeV
scale . Higher dimension operators involving right-handed neutrinos and the
Higgs boson can introduce new decay modes of the Higgs boson, significantly
modifying its phenomenology if it is light. With minimal flavor violation the
Higgs boson cascade decays to 6 particles containing two highly displaced
vertices. Each displaced vertex produces an odd number of leptons, leading to a
dramatic signature of overall lepton violation at each vertex. I discuss the
limits from the Tevatron, and find that they are close to exploring interesting
regions of parameters, while limiting others. Moving beyond minimal flavor
violation, cascade decays of the Higgs boson into as many as 14 particles can
occur.


title: On Pure Spinor Superfield Formalism

abstract:
  We show that a certain superfield formalism can be used to find an off-shell
supersymmetric description for some supersymmetric field theories where
conventional superfield formalism does not work. This "new" formalism contains
even auxiliary variables in addition to conventional odd super-coordinates. The
idea of this construction is similar to the pure spinor formalism developed by
N.Berkovits. It is demonstrated that using this formalism it is possible to
prove that the certain Chern-Simons-like (Witten's OSFT-like) theory can be
considered as an off-shell version for some on-shell supersymmetric field
theories. We use the simplest non-trivial model found in [2] to illustrate the
power of this pure spinor superfield formalism. Then we redo all the
calculations for the case of 10-dimensional Super-Yang-Mills theory. The
construction of off-shell description for this theory is more subtle in
comparison with the model of [2] and requires additional Z_2 projection. We
discover experimentally (through a direct explicit calculation) a non-trivial
Z_2 duality at the level of Feynman diagrams. The nature of this duality
requires a better investigation.


title: Conference Summary: The Central Engine of Active Galactic Nuclei

abstract:
  The 2006 meeting in Xi'an on the Central Engine of Active Galactic Nuclei
covered the enormous and continuously expanding area of AGN research, from
theory to the most sophisticated observations and from gamma-ray energies to
long radio wavelengths. This short summary gives some, but definitely not all,
highlights and new results presented by the participants.


title: Forward hadron production in high energy pA collisions: from RHIC to LHC

abstract:
  We present a calculation of Pi, D and B mesons production at RHIC and LHC
energies based upon the KKT model of gluon saturation. We discuss dependence of
the nuclear modification factor on rapidity and transverse momentum.


title: Excitation of MHD waves in magnetized anisotropic cosmologies

abstract:
  The excitation of cosmological perturbations in an anisotropic cosmological
model and in the presence of a homogeneous magnetic field was studied, using
the resistive magnetohydrodynamic (MHD) equations. We have shown that
fast-magnetosonic modes, propagating normal to the magnetic field grow
exponentially and saturated at high values, due to the resistivity. We also
demonstrate that the jeans-like instabilities are enhanced inside a resistive
and the formation of condensations formed within an anisotropic fluid influence
the growing magnetosonic waves.


title: Toroidal Magnetic Fields in Type II Superconducting Neutron Stars

abstract:
  We determine constraints on the form of axisymmetric toroidal magnetic fields
dictated by hydrostatic balance in a type II superconducting neutron star with
a barotropic equation of state. Using Lagrangian perturbation theory, we find
the quadrupolar distortions due to such fields for various models of neutron
stars with type II superconducting and normal regions. We find that the star
becomes prolate and can be sufficiently distorted to display precession with a
period of the order of years. We also study the stability of such fields using
an energy principle, which allows us to extend the stability criteria
established by R. J. Tayler for normal conductors to more general media with
magnetic free energy that depends on density and magnetic induction, such as
type II superconductors. We also derive the growth rate and instability
conditions for a specific instability of type II superconductors, first
discussed by P. Muzikar, C. J. Pethick and P. H. Roberts, using a local
analysis based on perturbations around a uniform background.


title:
Iron abundances of B-type post-Asymptotic Giant Branch stars in globular
  clusters: Barnard 29 in M 13 and ROA 5701 in omega Cen

abstract:
  High resolution optical and ultraviolet spectra of two B-type post-Asymptotic
Giant Branch (post-AGB) stars in globular clusters, Barnard 29 in M 13 and ROA
5701 in omega Cen, have been analysed using model atmosphere techniques. The
optical spectra have been obtained with FEROS on the ESO 2.2-m telescope and
the 2d-Coud\'e spectrograph on the 2.7-m McDonald telescope, while the
ultraviolet observations are from the GHRS on the HST. Abundances of light
elements (C, N, O, Mg, Al and S) plus Fe have been determined from the optical
spectra, while the ultraviolet data provide additional Fe abundance estimates
from Fe III absorption lines in the 1875-1900 {\AA} wavelength region. A
general metal underabundance relative to young B-type stars is found for both
Barnard 29 and ROA 5701. These results are consistent with the metallicities of
the respective clusters, as well as with previous studies of the objects. The
derived abundance patterns suggest that the stars have not undergone a gas-dust
separation, contrary to previous suggestions, although they may have evolved
from the AGB before the onset of the third dredge-up. However, the Fe
abundances derived from the HST spectra are lower than those expected from the
metallicities of the respective clusters, by 0.5 dex for Barnard 29 and 0.8 dex
for ROA 5701. A similar systematic underabundance is also found for other
B-type stars in environments of known metallicity, such as the Magellanic
Clouds. These results indicate that the Fe III ultraviolet lines may yield
abundance values which are systematically too low by typically 0.6 dex and
hence such estimates should be treated with caution.


title: Black holes, information, and locality

abstract:
  Thirty years of a deepening information paradox suggest the need to revise
our basic physical framework. Multiple indicators point toward reassessment of
the principle of locality: lack of a precise definition in quantum gravity,
behavior of high-energy scattering, hints from strings and AdS/CFT, conundrums
of quantum cosmology, and finally lack of good alternative resolutions of the
paradox. A plausible conjecture states that the non-perturbative dynamics of
gravity is unitary but nonlocal. String theory may directly address these
issues but so far important aspects remain elusive. If this viewpoint is
correct, critical questions are to understand the "correspondence" limit where
nonlocal physics reduces to local quantum field theory, and beyond, to unveil
principles of an underlying nonlocal theory.


title: Charmonium at high temperature in two-flavor QCD

abstract:
  We compute charmonium spectral functions in 2-flavor QCD on anisotropic
lattices using the maximum entropy method. Our results suggest that the S-waves
(J/psi and eta_c) survive up to temperatures close to 2Tc, while the P-waves
(chi_c0 and chi_c1) melt away below 1.2Tc.


title:
Alfven modes driven non-linearly by metric perturbations in anisotropic
  magnetized cosmologies

abstract:
  We consider anisotropic magnetized cosmologies filled with conductive plasma
fluid and study the implications of metric perturbations that propagate
parallel to the ambient magnetic field. It is known that in the first order
(linear) approximation with respect to the amplitude of the perturbations no
electric field and density perturbations arise. However, when we consider the
non-linear coupling of the metric perturbations with their temporal
derivatives, certain classes of solutions can induce steeply increasing in time
electric field perturbations. This is verified both numerically and
analytically. The source of these perturbations can be either high-frequency
quantum vacuum fluctuations, driven by the cosmological pump field, in the
early stages of the evolution of the Universe or astrophysical processes or a
non-linear isotropization process of an initially anisotropic cosmological
spacetime.


title: Effective gravity from a quantum gauge theory in Euclidean space-time

abstract:
  We consider a $SO(d)$ gauge theory in an Euclidean $d$-dimensional
space-time, which is known to be renormalizable to all orders in perturbation
theory for $2\le{d}\le4$. Then, with the help of a space-time representation of
the gauge group, the gauge theory is mapped into a curved space-time with
linear connection. Further, in that mapping the gauge field plays the role of
the linear connection of the curved space-time and an effective metric tensor
arises naturally from the mapping. The obtained action, being quadratic in the
Riemann-Christoffel tensor, at a first sight, spoils a gravity interpretation
of the model. Thus, we provide a sketch of a mechanism that breaks the $SO(d)$
color invariance and generates the Einstein-Hilbert term, as well as a
cosmological constant term, allowing an interpretation of the model as a
modified gravity in the Palatini formalism. In that sense, gravity can be
visualized as an effective classical theory, originated from a well defined
quantum gauge theory. We also show that, in the four dimensional case, two
possibilities for particular solutions of the field equations are the de Sitter
and Anti de Sitter space-times.


title:
The quantum $J_1$-$J_1'$-$J_2$ spin-1/2 Heisenberg model: Influence of
  the interchain coupling on the ground-state magnetic ordering in 2D

abstract:
  We study the phase diagram of the 2D $J_1$-$J_1'$-$J_2$ spin-1/2 Heisenberg
model by means of the coupled cluster method. The effect of the coupling $J_1'$
on the Neel and stripe states is investigated. We find that the quantum
critical points for the Neel and stripe phases increase as the coupling
strength $J_1'$ is increased, and an intermediate phase emerges above the
region at $J_1' \approx 0.6$ when $J_1=1$. We find indications for a quantum
triple point at $J_1' \approx 0.60 \pm 0.03$, $J_2 \approx 0.33 \pm 0.02$ for
$J_1=1$.


title:
Quantum decoherence and classical correlations of the harmonic
  oscillator in the Lindblad theory

abstract:
  In the framework of the Lindblad theory for open quantum systems we determine
the degree of quantum decoherence and classical correlations of a harmonic
oscillator interacting with a thermal bath. The transition from quantum to
classical behaviour of the considered system is analyzed and it is shown that
the classicality takes place during a finite interval of time. We calculate
also the decoherence time and show that it has the same scale as the time after
which statistical fluctuations become comparable with quantum fluctuations.


title:
An absolute quantum energy inequality for the Dirac field in curved
  spacetime

abstract:
  Quantum Weak Energy Inequalities (QWEIs) are results which limit the extent
to which the smeared renormalised energy density of a quantum field can be
negative. On globally hyperbolic spacetimes the massive quantum Dirac field is
known to obey a QWEI in terms of a reference state chosen arbitrarily from the
class of Hadamard states; however, there exist spacetimes of interest on which
state-dependent bounds cannot be evaluated. In this paper we prove the first
QWEI for the massive quantum Dirac field on four dimensional globally
hyperbolic spacetime in which the bound depends only on the local geometry;
such a QWEI is known as an absolute QWEI.


title:
Probing for Dynamics of Dark-Energy in Mass Varying Neutrinos: Cosmic
  Microwave Background Radiation and Large Scale Structure

abstract:
  We present cosmological perturbation theory in neutrino probe interacting
dark-energy models, and calculate cosmic microwave background anisotropies and
matter power spectrum. In these models, the evolution of the mass of neutrinos
is determined by the quintessence scalar field, which is responsible for the
cosmic acceleration today. We consider several types of scalar field potentials
and put constraints on the coupling parameter between neutrinos and dark
energy. Assuming the flatness of the universe, the constraint we can derive
from the current observation is $\sum m_{\nu} < 0.87 eV$ at the 95 % confidence
level for the sum over three species of neutrinos.


title:
From Nondeterministic B\"uchi and Streett Automata to Deterministic
  Parity Automata

abstract:
  In this paper we revisit Safra's determinization constructions for automata
on infinite words. We show how to construct deterministic automata with fewer
states and, most importantly, parity acceptance conditions. Determinization is
used in numerous applications, such as reasoning about tree automata,
satisfiability of CTL*, and realizability and synthesis of logical
specifications. The upper bounds for all these applications are reduced by
using the smaller deterministic automata produced by our construction. In
addition, the parity acceptance conditions allows to use more efficient
algorithms (when compared to handling Rabin or Streett acceptance conditions).


title:
Rotational Surfaces in $\mathbb{L}^3$ and Solutions in the Nonlinear
  Sigma Model

abstract:
  The Gauss map of non-degenerate surfaces in the three-dimensional Minkowski
space are viewed as dynamical fields of the two-dimensional O(2,1) Nonlinear
Sigma Model. In this setting, the moduli space of solutions with rotational
symmetry is completely determined. Essentially, the solutions are warped
products of orbits of the 1-dimensional groups of isometries and elastic curves
in either a de Sitter plane, a hyperbolic plane or an anti de Sitter plane. The
main tools are the equivalence of the two-dimensional O(2,1) Nonlinear Sigma
Model and the Willmore problem, and the description of the surfaces with
rotational symmetry. A complete classification of such surfaces is obtained in
this paper. Indeed, a huge new family of Lorentzian rotational surfaces with a
space-like axis is presented. The description of this new class of surfaces is
based on a technique of surgery and a gluing process, which is illustrated by
an algorithm.


title:
Using an Assumption about the Monotony of Spiral Arms to Determine the
  Orientation Angles of Galaxies

abstract:
  A method is proposed for the determination of the position and inclination
angles of the plane of a spiral galaxy based on the assumption that every
spiral arm is a monotonic function of the radius versus azimuthal angle. This
method may yield more accurate results than the more commonly employed isophote
method, which is fraught with various drawbacks. The use of the new method is
illustrated by applying it to a sample of 43 objects, and the results agree
well with data from other sources.


title: IIB backgrounds with five-form flux

abstract:
  We investigate all N=2 supersymmetric IIB supergravity backgrounds with
non-vanishing five-form flux. The Killing spinors have stability subgroups
$Spin(7)\ltimes\bR^8$, $SU(4)\ltimes\bR^8$ and $G_2$. In the
$SU(4)\ltimes\bR^8$ case, two different types of geometry arise depending on
whether the Killing spinors are generic or pure. In both cases, the backgrounds
admit a null Killing vector field which leaves invariant the $SU(4)\ltimes
\bR^8$ structure, and an almost complex structure in the directions transverse
to the lightcone. In the generic case, the twist of the vector field is trivial
but the almost complex structure is non-integrable, while in the pure case the
twist is non-trivial but the almost complex structure is integrable and
associated with a relatively balanced Hermitian structure. The $G_2$
backgrounds admit a time-like Killing vector field and two spacelike closed
one-forms, and the seven directions transverse to these admit a co-symplectic
$G_2$ structure. The $Spin(7)\ltimes\bR^8$ backgrounds are pp-waves propagating
in an eight-dimensional manifold with holonomy $Spin(7)$. In addition we show
that all the supersymmetric solutions of simple five-dimensional supergravity
with a time-like Killing vector field, which include the $AdS_5$ black holes,
lift to $SU(4)\ltimes\bR^8$ pure Killing spinor IIB backgrounds. We also show
that the LLM solution is associated with a co-symplectic co-homogeneity one
$G_2$ manifold which has principal orbit $S^3\times S^3$.


title:
Annotated Bibliography of Some Papers on Combining Significances or
  p-values

abstract:
  A question that comes up repeatedly is how to combine the results of two
experiments if all that is known is that one experiment had a n-sigma effect
and another experiment had a m-sigma effect. This question is not well-posed:
depending on what additional assumptions are made, the preferred answer is
different. The note lists some of the more prominent papers on the topic, with
some brief comments and excerpts.


title:
Study in a beam test of the resolution of a Micromegas TPC with standard
  readout pads

abstract:
  The results of a beam test performed at the KEK PS in June 2005 are
presented. Drift properties of an argon-isobutane mixture have been accurately
measured and compared with predictions at magnetic fields between 0 and 1
Tesla. The r.m.s. point resolution of a padrow is compared with simulation and
with an analytical calculation. The fundamental limitations due to detector
geometry and gas properties are reviewed and the measured performances of the
detector are found to be close to this limit. A numerical application to the
case of a Linear Collider TPC is presented.


title: Quantum critical scaling of the geometric tensors

abstract:
  Berry phases and the quantum-information theoretic notion of fidelity have
been recently used to analyze quantum phase transitions from a geometrical
perspective. In this paper we unify these two approaches showing that the
underlying mechanism is the critical singular behavior of a complex tensor over
the Hamiltonian parameter space. This is achieved by performing a scaling
analysis of this quantum geometric tensor in the vicinity of the critical
points. In this way most of the previous results are understood on general
grounds and new ones are found. We show that criticality is not a sufficient
condition to ensure superextensive divergence of the geometric tensor, and
state the conditions under which this is possible. The validity of this
analysis is further checked by exact diagonalization of the spin-1/2 XXZ
Heisenberg chain.


title: Low-dimensional Supersymmetric Lattice Models

abstract:
  We study and simulate N=2 supersymmetric Wess-Zumino models in one and two
dimensions. For any choice of the lattice derivative, the theories can be made
manifestly supersymmetric by adding appropriate improvement terms corresponding
to discretizations of surface integrals. In one dimension, our simulations show
that a model with the Wilson derivative and the Stratonovitch prescription for
this discretization leads to far better results at finite lattice spacing than
other models with Wilson fermions considered in the literature. In particular,
we check that fermionic and bosonic masses coincide and the unbroken Ward
identities are fulfilled to high accuracy. Equally good results for the
effective masses can be obtained in a model with the SLAC derivative (even
without improvement terms).
  In two dimensions we introduce a non-standard Wilson term in such a way that
the discretization errors of the kinetic terms are only of order O(a^2). Masses
extracted from the corresponding manifestly supersymmetric model prove to
approach their continuum values much quicker than those from a model containing
the standard Wilson term. Again, a comparable enhancement can be achieved in a
theory using the SLAC derivative.


title:
Chandra Stacking Constraints on the Contribution of 24 micron Spitzer
  Sources to the Unresolved Cosmic X-ray Background

abstract:
  We employ X-ray stacking techniques to examine the contribution from X-ray
undetected, mid-infrared-selected sources to the unresolved, hard (6-8 keV)
cosmic X-ray background (CXB). We use the publicly available, 24 micron Spitzer
Space Telescope MIPS catalogs from the Great Observatories Origins Deep Survey
(GOODS) - North and South fields, which are centered on the 2 Ms Chandra Deep
Field-North and the 1 Ms Chandra Deep Field-South, to identify bright (S_24 >
80 microJy) mid-infrared sources that may be powered by heavily obscured AGNs.
We measure a significant stacked X-ray signal in all of the X-ray bands
examined, including, for the first time, a significant (3.2 sigma) 6-8 keV
stacked X-ray signal from an X-ray undetected source population. We find that
the X-ray-undetected MIPS sources make up about 2% (or less) of the total CXB
below 6 keV, but about 6% in the 6-8 keV band. The 0.5-8 keV stacked X-ray
spectrum is consistent with a hard power-law (Gamma = 1.44 +/- 0.07), with the
spectrum hardening at higher X-ray energies. Our findings show that these
bright MIPS sources do contain obscured AGNs, but are not the primary source of
the unresolved 50% of 6-8 keV CXB. Our study rules out obscured, luminous QSOs
as a significant source of the remaining unresolved CXB and suggests that it
most likely arises from a large population of obscured, high-redshift (z > 1),
Seyfert-luminosity AGNs.


title: Bagging multiple comparisons from microarray data

abstract:
  The problem of large-scale simultaneous hypothesis testing is re-visited.
Bagging and subagging procedures are put forth with the purpose of improving
the discovery power of the tests. The procedures are implemented in both
simulated and real data. It is shown that bagging and subagging significantly
improve power at the cost of a small increase in false discovery rate with the
proposed `maximum contrast' subagging having an edge over bagging, i.e.,
yielding similar power but significantly smaller false discovery rates.


title:
The influence of the cylindrical shape of the nucleosomes and H1 defects
  on properties of chromatin

abstract:
  We present a model improving the two-angle model for interphase chromatin
(E2A model). This model takes into account the cylindrical shape of the histone
octamers, the H1 histones in front of the nucleosomes and the vertical distance
$d$ between the in and outgoing DNA strands. Factoring these chromatin features
in, one gets essential changes in the chromatin phase diagram: Not only the
shape of the excluded-volume borderline changes but also the vertical distance
$d$ has a dramatic influence on the forbidden area. Furthermore, we examined
the influence of H1 defects on the properties of the chromatin fiber. Thus we
present two possible strategies for chromatin compaction: The use of very dense
states in the phase diagram in the gaps in the excluded volume borderline or
missing H1 histones which can lead to very compact fibers. The chromatin fiber
might use both of these mechanisms to compact itself at least locally. Line
densities computed within the model coincident with the experimental values.


title: Real interpolation of Sobolev spaces

abstract:
  We prove that $W^{1}_{p}$ is an interpolation space between $W^{1}_{p_{1}}$
and $W^{1}_{p_{2}}$ for $p>q_{0}$ and $1\leq p_{1}<p<p_{2}\leq \infty$ on some
classes of manifolds and general metric spaces, where $q_{0}$ depends on our
hypotheses.


title:
Inelastic effects in molecular junctions in the Coulomb and Kondo
  regimes: Nonequilibrium equation-of-motion approach

abstract:
  Inelastic effects in the Coulomb blockade and Kondo regimes of electron
transport through molecular junctions are considered within a simple
nonequilibrium equation-of-motion (EOM) approach. The scheme is
self-consistent, and can qualitatively reproduce the main experimental
observations of vibrational features in Coulomb blockade [H.Park et al., Nature
407, 57 (2000)] and Kondo [L.H.Yu et al., Phys. Rev. Lett. 93, 266802 (2004)]
regimes. Considerations similar to the equilibrium EOM approach by Meir et al.
[Phys. Rev. Lett. 66, 3048 (1991); ibid. 70, 2601 (1993)] are used on the
Keldysh contour to account for the nonequilibrium nature of the junction, and
dressing by appropriate Franck-Condon (FC) factors is used to account for
vibrational features. Results of the equilibrium EOM scheme by Meir et al. are
reproduced in the appropriate limit.


title: Structural properties of crumpled cream layers

abstract:
  The cream layer is a complex heterogeneous material of biological origin
which forms spontaneously at the air-milk interface. Here, it is studied the
crumpling of a single cream layer packing under its own weight at room
temperature in three-dimensional space. The structure obtained in these
circumstances has low volume fraction and anomalous fractal dimensions. Direct
means and noninvasive NMR imaging technique are used to investigate the
internal and external structure of these systems.


title: Detection of transits of the nearby hot Neptune GJ 436 b

abstract:
  This Letter reports on the photometric detection of transits of the
Neptune-mass planet orbiting the nearby M-dwarf star GJ 436. It is by far the
closest, smallest and least massive transiting planet detected so far. Its mass
is slightly larger than Neptune's at M = 22.6 +- 1.9 M_earth. The shape and
depth of the transit lightcurves show that it is crossing the host star disc
near its limb (impact parameter 0.84 +- 0.03) and that the planet size is
comparable to that of Uranus and Neptune, R = 25200 +- 2200 km = 3.95 +- 0.35
R_earth. Its main constituant is therefore very likely to be water ice. If the
current planet structure models are correct, an outer layer of H/He
constituting up to ten percent in mass is probably needed on top of the ice to
account for the observed radius.


title: Dye's theorem in the almost continuous category

abstract:
  We prove an almost continuous version of Dye's theorem: any two non-atomic
probability measure preserving homeomorphisms of Polish spaces are almost
continuously orbit equivalent. More precisely they are orbit equivalent by a
map which is defined and continuous on a Polish subset of full measure with an
inverse satisfying the same conditions. This result includes all of the recent
results on almost continuous orbit equivalence. We also deal with the case of
infinite invariant measures.


title: Condensation of elastic energy in two-dimensional packing of wire

abstract:
  Forced packing of a long metallic wire injected into a two-dimensional cavity
leads to crushed structures involving a hierarchical cascade of loops with
varying curvature radii. We study the distribution of elastic energy stored in
such systems from experiments, and high-resolution digital techniques. It is
found that the set where the elastic energy of curvature is concentrated has
dimension $D_\mathcal{S} = 1.0 \pm 0.1$, while the set where the mass is
distributed, has dimension $D =1.9 \pm 0.1$.


title:
Loop Quantum Gravity: Four Recent Advances and a Dozen Frequently Asked
  Questions

abstract:
  As per organizers' request, my talk at the 11th Marcel Grossmann Conference
consisted of two parts. In the first, I illustrated recent advances in loop
quantum gravity through examples. In the second, I presented an overall
assessment of the status of the program by addressing some frequently asked
questions. This account is addressed primarily to researchers outside the loop
quantum gravity community.


title:
The bang of a white hole in the early universe from a 6D vacuum state:
  Origin of astrophysical spectrum

abstract:
  Using a previously introduced model in which the expansion of the universe is
driven by a single scalar field subject to gravitational attraction induced by
a white hole during the expansion (from a 6D vacuum state), we study the origin
of squared inflaton fluctuations spectrum on astrophysical scales.