title: Effects of Jet Opening Angle and Velocity Structure on Blazar Parameters

abstract:
  We had earlier shown that for a constant velocity jet the discrepancy between
the low speeds indicated by VLBI knot motions and the high Doppler factors
inferred from emission of TeV photons could be reconciled if ultrarelativistic
jets possessed modest opening angles. Here we evaluate the (flux-weighted)
viewing angles of the jet and the apparent speeds and Doppler factors of the
radio knots on parsec scales. The influence of the jet opening angle on these
radio knot parameters are found for the usually considered types of
relativistic nuclear jets: those with uniform bulk speeds and those where the
bulk Lorentz factor of the flow decreases with distance from the jet axis,
known as `spine--sheath' flows. For both types of jet velocity structures the
expectation value of the jet orientation angle at first falls dramatically with
increases in the (central) jet Lorentz factor, but for extremely relativistic
jets it levels off at a fraction of the opening angle. The effective values of
the apparent speeds and Doppler factors of the knots always decline
substantially with increasing jet opening angle. The rarity of highly
superluminal parsec-scale radio components in TeV blazars can be understood if
their jets are both highly relativistic and intrinsically weaker, so probably
less well collimated, than the jets in ordinary blazars.


title:
A Generalized Information Formula as the Bridge between Shannon and
  Popper

abstract:
  A generalized information formula related to logical probability and fuzzy
set is deduced from the classical information formula. The new information
measure accords with to Popper's criterion for knowledge evolution very much.
In comparison with square error criterion, the information criterion does not
only reflect error of a proposition, but also reflects the particularity of the
event described by the proposition. It gives a proposition with less logical
probability higher evaluation. The paper introduces how to select a prediction
or sentence from many for forecasts and language translations according to the
generalized information criterion. It also introduces the rate fidelity theory,
which comes from the improvement of the rate distortion theory in the classical
information theory by replacing distortion (i.e. average error) criterion with
the generalized mutual information criterion, for data compression and
communication efficiency. Some interesting conclusions are obtained from the
rate-fidelity function in relation to image communication. It also discusses
how to improve Popper's theory.


title:
Causal vs. Noncausal Description of Nonlinear Wave Mixing; Resolving the
  Damping-Sign Controversy

abstract:
  Frequency-domain nonlinear wave mixing processes may be described either
using response functions whereby the signal is generated after all interactions
with the incoming fields, or in terms of scattering amplitudes where all fields
are treated symetrically with no specific time ordering. Closed Green's
function expressions derived for the two types of signals have different
analytical properties. The recent controversy regarding the sign of radiative
damping in the linear (Kramers Heisenberg) formula is put in a broader context.


title: Gutzwiller density functional theory for correlated electron systems

abstract:
  We develop a new density functional theory (DFT) and formalism for correlated
electron systems by taking as reference an interacting electron system that has
a ground state wavefunction which obeys exactly the Gutzwiller approximation
for all one particle operators. The solution of the many electron problem is
mapped onto the self-consistent solution of a set of single particle
Schroedinger equations analogous to standard DFT-LDA calculations.


title: Monopole annihilation in cosmic necklaces

abstract:
  A sequence of two symmetry breaking transitions in the early universe may
produce monopoles whose flux is confined into two strings each, which thus
assemble into "necklaces" with monopoles as beads. Such "cosmic necklaces" have
been proposed as a source of ultra-high-energy cosmic rays. We analyze the
evolution of these systems and show that essentially all monopoles annihilate
or leave the string at early times, after which cosmic necklaces evolve in a
similar way to a network of ordinary cosmic strings. We investigate several
modifications to the basic picture, but in nearly all cases we find that too
few monopoles remain on the necklaces to produce any observable cosmic rays.
There may be a small window for superconducting condensates to prevent
annihilations, but only if both the string and the condensate scale are very
high.


title:
Lattices for Distributed Source Coding: Jointly Gaussian Sources and
  Reconstruction of a Linear Function

abstract:
  Consider a pair of correlated Gaussian sources (X1,X2). Two separate encoders
observe the two components and communicate compressed versions of their
observations to a common decoder. The decoder is interested in reconstructing a
linear combination of X1 and X2 to within a mean-square distortion of D. We
obtain an inner bound to the optimal rate-distortion region for this problem. A
portion of this inner bound is achieved by a scheme that reconstructs the
linear function directly rather than reconstructing the individual components
X1 and X2 first. This results in a better rate region for certain parameter
values. Our coding scheme relies on lattice coding techniques in contrast to
more prevalent random coding arguments used to demonstrate achievable rate
regions in information theory. We then consider the case of linear
reconstruction of K sources and provide an inner bound to the optimal
rate-distortion region. Some parts of the inner bound are achieved using the
following coding structure: lattice vector quantization followed by
"correlated" lattice-structured binning.


title: Separable and Low-Rank Continuous Games

abstract:
  In this paper, we study nonzero-sum separable games, which are continuous
games whose payoffs take a sum-of-products form. Included in this subclass are
all finite games and polynomial games. We investigate the structure of
equilibria in separable games. We show that these games admit finitely
supported Nash equilibria. Motivated by the bounds on the supports of mixed
equilibria in two-player finite games in terms of the ranks of the payoff
matrices, we define the notion of the rank of an n-player continuous game and
use this to provide bounds on the cardinality of the support of equilibrium
strategies. We present a general characterization theorem that states that a
continuous game has finite rank if and only if it is separable. Using our rank
results, we present an efficient algorithm for computing approximate equilibria
of two-player separable games with fixed strategy spaces in time polynomial in
the rank of the game.


title:
Charge accumulation at the boundaries of a graphene strip induced by a
  gate voltage: Electrostatic approach

abstract:
  Distribution of charge induced by a gate voltage in a graphene strip is
investigated. We calculate analytically the charge profile and demonstrate a
strong(macroscopic) charge accumulation along the boundaries of a
micrometers-wide strip. This charge inhomogeneity is especially important in
the quantum Hall regime where we predict the doubling of the number of edge
states and coexistence of two different types of such states. Applications to
graphene-based nanoelectronics are discussed.


title:
A comparison of three replication strategies in complex multicellular
  organisms: Asexual replication, sexual replication with identical gametes,
  and sexual replication with distinct sperm and egg gametes

abstract:
  This paper studies the mutation-selection balance in three simplified
replication models. The first model considers a population of organisms
replicating via the production of asexual spores. The second model considers a
sexually replicating population that produces identical gametes. The third
model considers a sexually replicating population that produces distinct sperm
and egg gametes. All models assume diploid organisms whose genomes consist of
two chromosomes, each of which is taken to be functional if equal to some
master sequence, and defective otherwise. In the asexual population, the
asexual diploid spores develop directly into adult organisms. In the sexual
populations, the haploid gametes enter a haploid pool, where they may fuse with
other haploids. The resulting immature diploid organisms then proceed to
develop into mature organisms. Based on an analysis of all three models, we
find that, as organism size increases, a sexually replicating population can
only outcompete an asexually replicating population if the adult organisms
produce distinct sperm and egg gametes. A sexual replication strategy that is
based on the production of large numbers of sperm cells to fertilize a small
number of eggs is found to be necessary in order to maintain a sufficiently low
cost for sex for the strategy to be selected for over a purely asexual
strategy. We discuss the usefulness of this model in understanding the
evolution and maintenance of sexual replication as the preferred replication
strategy in complex, multicellular organisms.


title: The stochastic edge in adaptive evolution

abstract:
  In a recent article, Desai and Fisher (2007) proposed that the speed of
adaptation in an asexual population is determined by the dynamics of the
stochastic edge of the population, that is, by the emergence and subsequent
establishment of rare mutants that exceed the fitness of all sequences
currently present in the population. Desai and Fisher perform an elaborate
stochastic calculation of the mean time $\tau$ until a new class of mutants has
been established, and interpret $1/\tau$ as the speed of adaptation. As they
note, however, their calculations are valid only for moderate speeds. This
limitation arises from their method to determine $\tau$: Desai and Fisher
back-extrapolate the value of $\tau$ from the best-fit class' exponential
growth at infinite time. This approach is not valid when the population adapts
rapidly, because in this case the best-fit class grows non-exponentially during
the relevant time interval. Here, we substantially extend Desai and Fisher's
analysis of the stochastic edge. We show that we can apply Desai and Fisher's
method to high speeds by either exponentially back-extrapolating from finite
time or using a non-exponential back-extrapolation. Our results are compatible
with predictions made using a different analytical approach (Rouzine et al.
2003, 2007), and agree well with numerical simulations.


title: Einsteinian gravity from a topological action

abstract:
  The curvature-squared model of gravity, in the affine form proposed by Weyl
and Yang, is deduced from a topological action in 4D. More specifically, we
start from the Pontrjagin (or Euler) invariant. Using the BRST antifield
formalism with a double duality gauge fixing, we obtain a consistent
quantization in spaces of double dual curvature as classical instanton type
background.
  However, exact vacuum solutions with double duality properties exhibit a
`vacuum degeneracy'. By modifying the duality via a scale breaking term, we
demonstrate that only Einstein's equations with an induced cosmological
constant emerge for the topology of the macroscopic background. This may have
repercussions on the problem of `dark energy' as well as `dark matter' modeled
by a torsion induced quintaxion.


title:
Generalized momenta of mass and their applications to the flow of
  compressible fluid

abstract:
  We present a technique that allows to obtain certain results in the
compressible fluid theory: in particular, it is a nonexistence result for the
highly decreasing at infinity solutions to the Navier-Stokes equations, the
construction of the solutions with uniform deformation and the study of
behavior of the boundary of a material volume of liquid.


title:
The effect of negative feedback loops on the dynamics of Boolean
  networks

abstract:
  Feedback loops in a dynamic network play an important role in determining the
dynamics of that network. Through a computational study, in this paper we show
that networks with fewer independent negative feedback loops tend to exhibit
more regular behavior than those with more negative loops. To be precise, we
study the relationship between the number of independent feedback loops and the
number and length of the limit cycles in the phase space of dynamic Boolean
networks. We show that, as the number of independent negative feedback loops
increases, the number (length) of limit cycles tends to decrease (increase).
These conclusions are consistent with the fact, for certain natural biological
networks, that they on the one hand exhibit generally regular behavior and on
the other hand show less negative feedback loops than randomized networks with
the same numbers of nodes and connectivity.


title:
The traveling wave approach to asexual evolution: Muller's ratchet and
  speed of adaptation

abstract:
  We use traveling-wave theory to derive expressions for the rate of
accumulation of deleterious mutations under Muller's ratchet and the speed of
adaptation under positive selection in asexual populations. Traveling-wave
theory is a semi-deterministic description of an evolving population, where the
bulk of the population is modeled using deterministic equations, but the class
of the highest-fitness genotypes, whose evolution over time determines loss or
gain of fitness in the population, is given proper stochastic treatment. We
derive improved methods to model the highest-fitness class (the stochastic
edge) for both Muller's ratchet and adaptive evolution, and calculate analytic
correction terms that compensate for inaccuracies which arise when treating
discrete fitness classes as a continuum. We show that traveling wave theory
makes excellent predictions for the rate of mutation accumulation in the case
of Muller's ratchet, and makes good predictions for the speed of adaptation in
a very broad parameter range. We predict the adaptation rate to grow
logarithmically in the population size until the population size is extremely
large.


title: Convergence of Kaehler-Ricci flow with integral curvature bound

abstract:
  Let $g(t)$, $t\in [0, +\infty)$, be a solution of the normalized
K\"ahler-Ricci flow on a compact K\"ahler $n$-manifold $M$ with $c_{1}(M)>0$
and initial metric $g (0)\in 2\pi c_{1}(M)$.
  If there is a constant $C$ independent of $t$ such that $$
\int_{M}|Rm(g(t))|^{n}dv_{t}\leq C,$$ then, for any $t_{k}\to \infty$, a
subsequence of $(M, g(t_{k}))$ converges to a compact orbifold $(X, h)$ with
only finite many singular points $\{q_{j}\}$ in the Gromov-Hausdorff sense,
where $h$ is a K\"ahler metric on $X\backslash \{q_{j}\}$ satisfying the
K\"ahler-Ricci soliton equation, i.e. there is a smooth function $f$ such that
$$Ric(h)-h=\nabla\bar{\nabla}f, {\rm and}\it \nabla \nabla f=\bar{\nabla}
\bar{\nabla} f=0. $$


title: Eternal Chaotic Inflation is Prohibited by Weak Gravity Conjecture

abstract:
  We investigate whether the eternal chaotic inflation can be achieved when the
weak gravity conjecture is taken into account. We show that even the assisted
chaotic inflation with potential $\lambda\phi^4$ or $m^2\phi^2$ can not be
eternal. The effective field theory description for the inflaton field breaks
down before inflation reaches the eternal regime. We also find that the total
number of e-folds is still bounded by the inflationary entropy for the assisted
inflation.


title: Phase transition of meshwork models for spherical membranes

abstract:
  We have studied two types of meshwork models by using the canonical Monte
Carlo simulation technique. The first meshwork model has elastic junctions,
which are composed of vertices, bonds, and triangles, while the second model
has rigid junctions, which are hexagonal (or pentagonal) rigid plates.
Two-dimensional elasticity is assumed only at the elastic junctions in the
first model, and no two-dimensional bending elasticity is assumed in the second
model. Both of the meshworks are of spherical topology. We find that both
models undergo a first-order collapsing transition between the smooth spherical
phase and the collapsed phase. The Hausdorff dimension of the smooth phase is
H\simeq 2 in both models as expected. It is also found that H\simeq 2 in the
collapsed phase of the second model, and that H is relatively larger than 2 in
the collapsed phase of the first model, but it remains in the physical bound,
i.e., H<3. Moreover, the first model undergoes a discontinuous surface
fluctuation transition at the same transition point as that of the collapsing
transition, while the second model undergoes a continuous transition of surface
fluctuation. This indicates that the phase structure of the meshwork model is
weakly dependent on the elasticity at the junctions.


title:
Averages over hyperplanes, sum-product theory in vector spaces over
  finite fields and the Erdos-Falconer distance conjecture

abstract:
  We prove a point-wise and average bound for the number of incidences between
points and hyper-planes in vector spaces over finite fields. While our
estimates are, in general, sharp, we observe an improvement for product sets
and sets contained in a sphere. We use these incidence bounds to obtain
significant improvements on the arithmetic problem of covering ${\mathbb F}_q$,
the finite field with q elements, by $A \cdot A+... +A \cdot A$, where A is a
subset ${\mathbb F}_q$ of sufficiently large size. We also use the incidence
machinery we develope and arithmetic constructions to study the Erdos-Falconer
distance conjecture in vector spaces over finite fields. We prove that the
natural analog of the Euclidean Erdos-Falconer distance conjecture does not
hold in this setting due to the influence of the arithmetic. On the positive
side, we obtain good exponents for the Erdos -Falconer distance problem for
subsets of the unit sphere in $\mathbb F_q^d$ and discuss their sharpness. This
results in a reasonably complete description of the Erdos-Falconer distance
problem in higher dimensional vector spaces over general finite fields.


title:
Groundstate with Zero Eigenvalue for Generalized Sombrero-shaped
  Potential in $N$-dimensional Space

abstract:
  Based on an iterative method for solving the goundstate of Schroedinger
equation, it is found that a kind of generalized Sombrero-shaped potentials in
N-dimensional space has groundstates with zero eigenvalue. The restrictions on
the parameters in the potential are discussed.


title:
Electric field of a pointlike charge in a strong magnetic field and
  ground state of a hydrogenlike atom

abstract:
  In an external constant magnetic field, so strong that the electron Larmour
length is much shorter than its Compton length, we consider the modification of
the Coulomb potential of a point charge owing to the vacuum polarization. We
establish a short-range component of the static interaction in the Larmour
scale, expressed as a Yukawa-like law, and reveal the corresponding "photon
mass" parameter. The electrostatic force regains its long-range character in
the Compton scale: the tail of the potential follows an anisotropic Coulomb
law, decreasing away from the charge slower along the magnetic field and faster
across. In the infinite-magnetic-field limit the potential is confined to an
infinitely thin string passing though the charge parallel to the external
field. This is the first evidence for dimensional reduction in the photon
sector of quantum electrodynamics. The one-dimensional form of the potential on
the string is derived that includes a delta-function centered in the charge.
The nonrelativistic ground-state energy of a hydrogenlike atom is found with
its use and shown not to be infinite in the infinite-field limit, contrary to
what was commonly accepted before, when the vacuum polarization had been
ignored. These results may be useful for studying properties of matter at the
surface of extremely magnetized neutron stars.

categories: astro-ph gr-qc hep-lat hep-ph hep-th physics.atom-ph


title: Sums of products of congruence classes and of arithmetic progressions

abstract:
  Consider the congruence class R_m(a)={a+im:i\in Z} and the infinite
arithmetic progression P_m(a)={a+im:i\in N_0}. For positive integers a,b,c,d,m
the sum of products set R_m(a)R_m(b)+R_m(c)R_m(d) consists of all integers of
the form (a+im)(b+jm)+(c+km)(d+\ell m) for some i,j,k,\ell\in Z. It is proved
that if gcd(a,b,c,d,m)=1, then R_m(a)R_m(b)+R_m(c)R_m(d) is equal to the
congruence class R_m(ab+cd), and that the sum of products set
P_m(a)P_m(b)+P_m(c)P_m(d) eventually coincides with the infinite arithmetic
progression P_m(ab+cd).


title:
Dy2Ti2O7 Spin Ice: a Test Case for Emergent Clusters in a Frustrated
  Magnet

abstract:
  Dy2Ti2O7 is a geometrically frustrated magnetic material with a strongly
correlated spin ice regime that extends from 1 K down to as low as 60 mK. The
diffuse elastic neutron scattering intensities in the spin ice regime can be
remarkably well described by a phenomenological model of weakly interacting
hexagonal spin clusters, as invoked in other geometrically frustrated magnets.
We present a highly refined microscopic theory of Dy2Ti2O7 that includes
long-range dipolar and exchange interactions to third nearest neighbors and
which demonstrates that the clusters are purely fictitious in this material.
The seeming emergence of composite spin clusters and their associated
scattering pattern is instead an indicator of fine-tuning of ancillary
correlations within a strongly correlated state.


title: Credit risk - A structural model with jumps and correlations

abstract:
  We set up a structural model to study credit risk for a portfolio containing
several or many credit contracts. The model is based on a jump--diffusion
process for the risk factors, i.e. for the company assets. We also include
correlations between the companies. We discuss that models of this type have
much in common with other problems in statistical physics and in the theory of
complex systems. We study a simplified version of our model analytically.
Furthermore, we perform extensive numerical simulations for the full model. The
observables are the loss distribution of the credit portfolio, its moments and
other quantities derived thereof. We compile detailed information about the
parameter dependence of these observables. In the course of setting up and
analyzing our model, we also give a review of credit risk modeling for a
physics audience.

categories: q-fin.RM cond-mat.stat-mech physics.soc-ph q-fin.ST


title: Quantum Algorithms for Learning and Testing Juntas

abstract:
  In this article we develop quantum algorithms for learning and testing
juntas, i.e. Boolean functions which depend only on an unknown set of k out of
n input variables. Our aim is to develop efficient algorithms:
  - whose sample complexity has no dependence on n, the dimension of the domain
the Boolean functions are defined over;
  - with no access to any classical or quantum membership ("black-box")
queries. Instead, our algorithms use only classical examples generated
uniformly at random and fixed quantum superpositions of such classical
examples;
  - which require only a few quantum examples but possibly many classical
random examples (which are considered quite "cheap" relative to quantum
examples).
  Our quantum algorithms are based on a subroutine FS which enables sampling
according to the Fourier spectrum of f; the FS subroutine was used in earlier
work of Bshouty and Jackson on quantum learning. Our results are as follows:
  - We give an algorithm for testing k-juntas to accuracy $\epsilon$ that uses
$O(k/\epsilon)$ quantum examples. This improves on the number of examples used
by the best known classical algorithm.
  - We establish the following lower bound: any FS-based k-junta testing
algorithm requires $\Omega(\sqrt{k})$ queries.
  - We give an algorithm for learning $k$-juntas to accuracy $\epsilon$ that
uses $O(\epsilon^{-1} k\log k)$ quantum examples and $O(2^k \log(1/\epsilon))$
random examples. We show that this learning algorithms is close to optimal by
giving a related lower bound.


title:
The Relationship between the Optical Depth of the 9.7 micron Silicate
  Absorption Feature and Infrared Differential Extinction in Dense Clouds

abstract:
  We have examined the relationship between the optical depth of the 9.7 micron
silicate absorption feature (tau_9.7) and the near-infrared color excess,
E(J-Ks) in the Serpens, Taurus, IC 5146, Chameleon I, Barnard 59, and Barnard
68 dense clouds/cores. Our data set, based largely on Spitzer IRS spectra,
spans E(J-Ks)=0.3 to 10 mag (corresponding to visual extinction between about 2
and 60 mag.). All lines of sight show the 9.7 micron silicate feature. Unlike
in the diffuse ISM where a tight linear correlation between the 9.7 micron
silicate feature optical depth and the extinction (Av) is observed, we find
that the silicate feature in dense clouds does not show a monotonic increase
with extinction. Thus, in dense clouds, tau_9.7 is not a good measure of total
dust column density. With few exceptions, the measured tau_9.7 values fall well
below the diffuse ISM correlation line for E(J-Ks) > 2 mag (Av >12 mag). Grain
growth via coagulation is a likely cause of this effect.


abstract:
  Canonical orders, introduced in the minimal model program for orders, are
simultaneous generalisations of Kleinian singularities and their associated
skew group rings. In this paper, we construct minimal resolutions of canonical
orders via non-commutative cyclic covers and skew group rings. This allows us
to exhibit a derived equivalence between minimal resolutions of canonical
orders and the skew group ring form of the canonical order in all but one case.
The Fourier-Mukai transform used to construct this equivalence allows us to
make explicit, the numerical version of the McKay correspondence for canonical
orders which, relates the exceptional curves of the minimal resolution to the
indecomposable reflexive modules of the canonical order.


title: A Bayesian Framework for Combining Valuation Estimates

abstract:
  Obtaining more accurate equity value estimates is the starting point for
stock selection, value-based indexing in a noisy market, and beating benchmark
indices through tactical style rotation. Unfortunately, discounted cash flow,
method of comparables, and fundamental analysis typically yield discrepant
valuation estimates. Moreover, the valuation estimates typically disagree with
market price. Can one form a superior valuation estimate by averaging over the
individual estimates, including market price? This article suggests a Bayesian
framework for combining two or more estimates into a superior valuation
estimate. The framework justifies the common practice of averaging over several
estimates to arrive at a final point estimate.

categories: q-fin.ST cs.CE nlin.AO nlin.CD nlin.SI physics.pop-ph physics.soc-ph stat.AP


title:
Observational biases in Lagrangian reconstructions of cosmic velocity
  fields

abstract:
  Lagrangian reconstruction of large-scale peculiar velocity fields can be
strongly affected by observational biases. We develop a thorough analysis of
these systematic effects by relying on specially selected mock catalogues. For
the purpose of this paper, we use the MAK reconstruction method, although any
other Lagrangian reconstruction method should be sensitive to the same
problems. We extensively study the uncertainty in the mass-to-light assignment
due to luminosity incompleteness, and the poorly-determined relation between
mass and luminosity. The impact of redshift distortion corrections is analyzed
in the context of MAK and we check the importance of edge and finite-volume
effects on the reconstructed velocities. Using three mock catalogues with
different average densities, we also study the effect of cosmic variance. In
particular, one of them presents the same global features as found in
observational catalogues that extend to 80 Mpc/h scales. We give recipes,
checked using the aforementioned mock catalogues, to handle these particular
observational effects, after having introduced them into the mock catalogues so
as to quantitatively mimic the most densely sampled currently available galaxy
catalogue of the nearby universe. Once biases have been taken care of, the
typical resulting error in reconstructed velocities is typically about a
quarter of the overall velocity dispersion, and without significant bias. We
finally model our reconstruction errors to propose an improved Bayesian
approach to measure Omega_m in an unbiased way by comparing the reconstructed
velocities to the measured ones in distance space, even though they may be
plagued by large errors. We show that, in the context of observational data, a
nearly unbiased estimator of Omega_m may be built using MAK reconstruction.


title: Small Cosmological Constants from a Modified Randall-Sundrum Model

abstract:
  We study a mechanism, inspired from the mechanism for generating the gauge
hierarchy in Randall-Sundrum model, to investigate the cosmological constant
problem. First we analyze the bulk cosmological constant and brane vacuum
energies in RS model. We show that the five-dimensional bulk cosmological
constant and the vacuum energies of the two branes all obtain their natural
values. Finally we argue how we can generate a small four-dimensional effective
cosmological constant on the branes through modifying the original RS model.


title:
Type IIP Supernova SN 2004et: A Multi-Wavelength Study in X-Ray, Optical
  and Radio

abstract:
  We present X-ray, broad band optical and low frequency radio observations of
the bright type IIP supernova SN 2004et. The \cxo observed the supernova at
three epochs, and the optical coverage spans a period of $\sim$ 470 days since
explosion. The X-ray emission softens with time, and we characterise the X-ray
luminosity evolution as $\Lx \propto t^{-0.4}$. We use the observed X-ray
luminosity to estimate a mass-loss rate for the progenitor star of $\sim
\ee{2}{-6} M_\odot \mathrm{yr}^{-1}$. The optical light curve shows a
pronounced plateau lasting for about 110 days. Temporal evolution of
photospheric radius and color temperature during the plateau phase is
determined by making black body fits. We estimate the ejected mass of $^{56}$Ni
to be 0.06 $\pm$ 0.03 M$_\odot$. Using the expressions of Litvinova &
Nad\"{e}zhin (1985) we estimate an explosion energy of (0.98 $\pm$ 0.25)
$\times 10^{51}$ erg. We also present a single epoch radio observation of SN
2004et. We compare this with the predictions of the model proposed by Chevalier
et al. (2006). These multi-wavelength studies suggest a main sequence
progenitor mass of $\sim$ 20 M$_\odot$ for SN 2004et.


title: Loop Products and Closed Geodesics

abstract:
  We show the Chas-Sullivan product (on the homology of the free loop space of
a Riemannian manifold) is related to the Morse index of its closed geodesics.
We construct related products in the cohomology of the free loop space and of
the based loop space, and show they are nontrivial.


title: A minimalist pilot-wave model for quantum electrodynamics

abstract:
  We present a way to construct a pilot-wave model for quantum electrodynamics.
The idea is to introduce beables corresponding only to the bosonic degrees of
freedom and not to the fermionic degrees of freedom of the quantum state. We
show that this is sufficient to reproduce the quantum predictions. The beables
will be field beables corresponding to the electromagnetic field and they will
be introduced in a similar way to that of Bohm's model for the free
electromagnetic field. Our approach is analogous to the situation in
non-relativistic quantum theory, where Bell treated spin not as a beable but
only as a property of the wavefunction. After presenting this model we also
discuss a simple way for introducing additional beables that represent the
fermionic degrees of freedom.


title: Probing the Green-Schwarz Mechanism at the Large Hadron Collider

abstract:
  We investigate the phenomenology of new abelian gauge bosons, which we denote
as $X$ bosons, that suffer a mixed anomaly with the Standard Model, but are
made self-consistent by the Green-Schwarz mechanism. A distinguishing aspect of
the resulting effective theory is the decay of $X$ bosons into Standard Model
gauge bosons, $X\to ZZ, WW, \gamma Z$. We compute the production cross-section
of the $X$ boson from vector boson fusion at the Large Hadron Collider. We
study the $pp\to X\to ZZ\to 4l$ signal, and analyze the prospects of discovery.
We argue that such a discovery could indirectly probe high energies, even up to
the string scale.


title: Derivatives of embedding functors I: the stable case

abstract:
  For smooth manifolds $M$ and $N$, let $\Ebar(M, N)$ be the homotopy fiber of
the map $\Emb(M, N)\longrightarrow \Imm(M, N)$. Consider the functor from the
category of Euclidean spaces to the category of spectra, defined by the formula
$V\mapsto \Sigma^\infty\Ebar(M, N\times V)$. In this paper, we describe the
Taylor polynomials of this functor, in the sense of M. Weiss' orthogonal
calculus, in the case when $N$ is a nice open submanifold of a Euclidean space.
This leads to a description of the derivatives of this functor when $N$ is a
tame stably parallelizable manifold (we believe that the parallelizability
assumption is not essential). Our construction involves a certain space of
rooted forests (or, equivalently, a space of partitions) with leaves marked by
points in $M$, and a certain ``homotopy bundle of spectra'' over this space of
trees. The $n$-th derivative is then described as the ``spectrum of restricted
sections'' of this bundle. This is the first in a series of two papers. In the
second part, we will give an analogous description of the derivatives of the
functor $\Ebar(M, N\times V)$, involving a similar construction with certain
spaces of connected graphs (instead of forests) with points marked in $M$.


title: Econophysics and Financial-Economic Monitoring

abstract:
  The author solves two problems: formation of object of econophysics, creation
of the general theory of financial-economic monitoring. In the first problem he
studied two fundamental tasks: a choice of conceptual model and creation of
axiomatic base. It is accepted, that the conceptual model of econophysics is a
concrete definition of entropy conceptual model. Financial and economic
monitoring is considered as monitoring of flows on entropy manifold of phase
space - on a Diffusion field.


title: Observation of a new D_sJ meson in B+->D0BD0K+ decays

abstract:
  We report the observation of a new $D_{sJ}$ meson produced in $B^{+} \to
\bar{D}^{0} D_{sJ} \to \bar{D}^{0} D^{0} K^{+}$. This state has a mass of
$M=2708 \pm 9 ^{+11}_{-10} \rm{MeV}/{\it c}^{2}$, a width $\Gamma = 108 \pm 23
^{+36}_{-31} ~\rm{MeV}/ {\it c}^{2}$ and a $1^{-}$ spin-parity. The results are
based on an analysis of 449 million $B\bar{B}$ events collected at the
$\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy
$e^{+} e^{-}$ collider.


title: Limit on the electric charge-nonconserving $\mu^+ \to invisible$ decay

abstract:
  The first limit on the branching ratio of the electric charge-nonconserving
invisible muon decay $Br(\mu^+ \to invisible) < 5.2 \times 10^{-3}$ is obtained
from the recently reported results on new determination of the Fermi constant
from muon decays. The results of a feasibility study of a new proposed
experiment for a sensitive search for this decay mode at the level of a few
parts in 10^{11} are presented. Constrains on the $\tau \to invisible$ decay
rate are discussed. These leptonic charge-nonconserving processes may hold in
four-dimensional world in models with infinite extra dimensions, thus making
their searches complementary to collider experiments probing new physics.


title:
Generation of large scale magnetic fields by coupling to curvature and
  dilaton field

abstract:
  We investigate the generation of large scale magnetic fields in the universe
from quantum fluctuations produced in the inflationary stage. By coupling these
quantum fluctuations to the dilaton field and Ricci scalar, we show that the
magnetic fields with the strength observed today can be produced. We consider
two situations: First, the evolution of dilaton ends at the onset of the
reheating stage. Second, the dilaton continues its evolution after reheating
and then decays. In both cases, we come back to the usual Maxwell equations
after inflation and then calculate present magnetic fields.


title: Jet hadrochemistry as a characteristics of jet quenching

abstract:
  Jets produced in nucleus-nucleus collisions at the LHC are expected to be
strongly modified due to the interaction of the parton shower with the dense
QCD matter. Here, we point out that jet quenching can leave signatures not only
in the longitudinal and transverse jet energy and multiplicity distributions,
but also in the hadrochemical composition of the jet fragments. In particular,
we show that even in the absence of medium effects at or after hadronization,
the medium-modification of the parton shower can result in significant changes
in jet hadrochemistry. We discuss how jet hadrochemistry can be studied within
the high-multiplicity environment of nucleus-nucleus collisions at the LHC.


title:
Decomposition of Cartan Matrix and conjectures on Brauer character
  degrees

abstract:
  Let $G$ be a finite group and $N$ be a normal subgroup of $G$. Let
$J=J(F[N])$ denote the Jacboson radical of $F[N]$ and $I={\rm Ann}(J)=\{\alpha
\in F[G]|J\alpha =0\}$. We have another algebra $F[G]/I$. We study the
decomposition of Cartan matrix of $F[G]$ according to $F[G/N]$ and $F[G]/I$.
This decomposition establishs some connections between Cartan invariants and
chief composition factors of $G$. We find that existing zero-defect $p$-block
in $N$ depends on the properties of $I$ in $F[G]$ or Cartan invariants. When we
consider the Cartan invariants for a block algebra $B$ of $G$, the
decomposition is related to what kind of blocks in $N$ covered by $B$. We
mainly consider a block $B$ of $G$ which covers a block $b$ of $N$ with
$l(b)=1$. In two cases, we prove Willems' conjecture holds for these blocks,
which covers some true cases by Holm and Willems. Furthermore We give an
affirmative answer to a question by Holm and Willems in our cases. Some other
results about Cartan invariants are presented in our paper.


title: Dynamics of symmetric holomorphic maps on projective spaces

abstract:
  We consider complex dynamics of a critically finite holomorphic map from P^k
to P^k, which has symmetries associated with the symmetric group S_{k+2} acting
on P^k, for each k \ge 1. The Fatou set of each map of this family consists of
attractive basins of superattracting points. Each map of this family satisfies
Axiom A.


title: Generating mapping class groups of nonorientable surfaces with boundary

abstract:
  We obtain simple generating sets for various mapping class groups of a
nonorientable surface with punctures and/or boundary. We also compute the
abelianizations of these mapping class groups.


title:
Two-stage Kondo effect in side-coupled quantum dots: Renormalized
  perturbative scaling theory and Numerical Renormalization Group analysis

abstract:
  We study numerically and analytically the dynamical (AC) conductance through
a two-dot system, where only one of the dots is coupled to the leads but it is
also side-coupled to the other dot through an antiferromagnetic exchange (RKKY)
interaction. In this case the RKKY interaction gives rise to a ``two-stage
Kondo effect'' where the two spins are screened by two consecutive Kondo
effects. We formulate a renormalized scaling theory that captures remarkably
well the cross-over from the strongly conductive correlated regime to the low
temperature low conductance state. Our analytical formulas agree well with our
numerical renormalization group results. The frequency dependent current noise
spectrum is also discussed.


title: A comparison theorem for simplicial resolutions

abstract:
  It is well known that Barr and Beck's definition of comonadic homology makes
sense also with a functor of coefficients taking values in a semi-abelian
category instead of an abelian one. The question arises whether such a homology
theory has the same convenient properties as in the abelian case. Here we focus
on independence of the chosen comonad: conditions for homology to depend on the
induced class of projectives only.


title:
Coulomb tunneling for fusion reactions in dense matter: Path integral
  Monte Carlo versus mean field

abstract:
  We compare Path Integral Monte Carlo calculations by Militzer and Pollock
(Phys. Rev. B 71, 134303, 2005) of Coulomb tunneling in nuclear reactions in
dense matter to semiclassical calculations assuming WKB Coulomb barrier
penetration through the radial mean-field potential. We find a very good
agreement of two approaches at temperatures higher than ~1/5 of the ion plasma
temperature. We obtain a simple parameterization of the mean field potential
and of the respective reaction rates. We analyze Gamow-peak energies of
reacting ions in various reaction regimes and discuss theoretical uncertainties
of nuclear reaction rates taking carbon burning in dense stellar matter as an
example.


title:
Doping and energy evolution of spin dynamics in the electron-doped
  cuprate superconductor Pr$_{0.88}$LaCe$_{0.12}$CuO$_{4-\delta}$

abstract:
  The doping and energy evolution of the magnetic excitations of the
electron-doped cuprate superconductor Pr$_{0.88}$LaCe$_{0.12}$CuO$_{4-\delta}$
in the superconducting state is studied based on the kinetic energy driven
superconducting mechanism. It is shown that there is a broad commensurate
scattering peak at low energy, then the resonance energy is located among this
low energy commensurate scattering range. This low energy commensurate
scattering disperses outward into a continuous ring-like incommensurate
scattering at high energy. The theory also predicts a dome shaped doping
dependent resonance energy.


title: INTEGRAL and Swift Observations of Blazars in Outburst

abstract:
  The blazars 3C 454.3, PKS 0537-441 and PKS 2155-304 are traditionally known
to be among the most active sources of this class. They emit at all
frequencies, up to the gamma-rays, and are good probes of multiwavelength
nuclear variability. The first two have also luminous broad emission line
regions. We have recently monitored them with various facilities, including
Swift and INTEGRAL, and have interpreted their variations with models of
non-thermal radiation from a relativistic jet. In particular, we have tested
for the first two sources the hypothesis that the variability is produced
within the jet through internal shocks, i.e. collisions of relativistic plasma
blobs. This allows a parameterization of all physical quantities as functions
of the bulk Lorentz factor. We have made the critical assumption that every
flaring episode is characterized by a fixed amount of energy. The model
reproduces brilliantly the multiwavelength data and especially the gamma-ray
spectra, when available. The model is not applicable to PKS 2155-304, the
variability of which is caused by independent variations of few individual
parameters.


title:
Simple Coherent Polarization Manipulation Scheme for Generating High
  Power Radially Polarized Beam

abstract:
  We present a simple novel scheme that converts a Gaussian beam into an
approximated radially polarized beam using coherent polarization manipulation
together with Poynting walk-off in birefringent crystals. Our scheme alleviates
the interferometric stability required by previous schemes that implemented
this coherent mode summation using Mach-Zehnder-like interferometers. A
symmetrical arrangement of two walk-off crystals with a half-wave plate, allows
coherence control even when the laser has short temporal coherence length. We
generated 14 watts of radially polarized beam from an Ytterbium fiber laser,
only limited by the available fiber laser power.


title:
Limit theorems for conditioned multitype Dawson-Watanabe processes and
  Feller diffusions

abstract:
  A multitype Dawson-Watanabe process is conditioned, in subcritical and
critical cases, on non-extinction in the remote future. On every finite time
interval, its distribution is absolutely continuous with respect to the law of
the unconditioned process. A martingale problem characterization is also given.
Several results on the long time behavior of the conditioned mass process|the
conditioned multitype Feller branching diffusion are then proved. The general
case is first considered, where the mutation matrix which models the
interaction between the types, is irreducible. Several two-type models with
decomposable mutation matrices are analyzed too.


title: Molecular content of a type-Ia SN host galaxy at z=0.6

abstract:
  We study the properties and the molecular content of the host of a type-Ia
supernova (SN1997ey). This z=0.575 host is the brightest submillimetre source
of the sample of type-Ia supernova hosts observed at 450um and 850um by Farrah
et al.. Observations were performed at IRAM-30m to search for CO(2-1) and
CO(3-2) lines in good weather conditions but no signal was detected. The star
formation rate cannot exceed 50 M_sol/yr. These negative results are confronted
with an optical analysis of a Keck spectrum and other data archives. We reach
the conclusion that this galaxy is a late-type system (0.7 L^B_*), with a small
residual star-formation activity (0.2 M_sol/yr) detected in the optical. No
source of heating (AGN or starburst) is found to explain the
submillimetre-continuum flux and the non-CO detection excludes the presence of
a large amount of cold gas. We thus suggest that either the star formation
activity is hidden in the nucleus (with A_V ~ 4) or this galaxy is passive or
anemic and this flux might be associated with a background galaxy.


title: SUSY structures on deformed supermanifolds

abstract:
  We construct a geometric structure on deformed supermanifolds as a certain
subalgebra of the vector fields. In the classical limit we obtain a decoupling
of the infinitesimal odd and even transformations, whereas in the semiclassical
limit the result is a representation of the supersymmetry algebra. In the case
of mass preserving structure we describe all high energy corrections to this
algebra.


title: Workspace and Kinematic Analysis of the VERNE machine

abstract:
  This paper describes the workspace and the inverse and direct kinematic
analysis of the VERNE machine, a serial/parallel 5-axis machine tool designed
by Fatronik for IRCCyN. This machine is composed of a three-degree-of-freedom
(DOF) parallel module and a two-DOF serial tilting table. The parallel module
consists of a moving platform that is connected to a fixed base by three
non-identical legs. This feature involves (i) a simultaneous combination of
rotation and translation for the moving platform, which is balanced by the
tilting table and (ii) workspace whose shape and volume vary as a function of
the tool length. This paper summarizes results obtained in the context of the
European projects NEXT ("Next Generation of Productions Systems").


title: Expected Performance of a Self-Coherent Camera

abstract:
  Residual wavefront errors in optical elements limit the performance of
coronagraphs. To improve their efficiency, different types of devices have been
proposed to correct or calibrate these errors. In this paper, we study one of
these techniques proposed by Baudoz et al. 2006 and called Self-Coherent Camera
(SCC). The principle of this instrument is based on the lack of coherence
between the stellar light and the planet that is searched for. After recalling
the principle of the SCC, we simulate its performance under realistic
conditions and compare it with the performance of differential imaging.


title:
Upper bound of loss probability in an OFDMA system with randomly located
  users

abstract:
  For OFDMA systems, we find a rough but easily computed upper bound for the
probability of loosing communications by insufficient number of sub-channels on
downlink. We consider as random the positions of receiving users in the system
as well as the number of sub-channels dedicated to each one. We use recent
results of the theory of point processes which reduce our calculations to the
first and second moments of the total required number of sub-carriers.


title:
Analytic solution of the Schrodinger equation for an electron in the
  field of a molecule with an electric dipole moment

abstract:
  We relax the usual diagonal constraint on the matrix representation of the
eigenvalue wave equation by allowing it to be tridiagonal. This results in a
larger solution space that incorporates an exact analytic solution for the
non-central electric dipole potential cos(theta)/r^2, which was known not to
belong to the class of exactly solvable potentials. As a result, we were able
to obtain an exact analytic solution of the three-dimensional time-independent
Schrodinger equation for a charged particle in the field of a point electric
dipole that could carry a nonzero net charge. This problem models the
interaction of an electron with a molecule (neutral or ionized) that has a
permanent electric dipole moment. The solution is written as a series of square
integrable functions that support a tridiagonal matrix representation for the
angular and radial components of the wave operator. Moreover, this solution is
for all energies, the discrete (for bound states) as well as the continuous
(for scattering states). The expansion coefficients of the radial and angular
components of the wavefunction are written in terms of orthogonal polynomials
satisfying three-term recursion relations. For the Coulomb-free case, where the
molecule is neutral, we calculate critical values for its dipole moment below
which no electron capture is allowed. These critical values are obtained not
only for the ground state, where it agrees with already known results, but also
for excited states as well.

categories: physics.chem-ph math-ph math.MP physics.atom-ph


title:
Continuous or discrete attractors in neural circuits? A self-organized
  switch at maximal entropy

abstract:
  A recent experiment suggests that neural circuits may alternatively implement
continuous or discrete attractors, depending on the training set up. In
recurrent neural network models, continuous and discrete attractors are
separately modeled by distinct forms of synaptic prescriptions (learning
rules). Here, we report a solvable network model, endowed with Hebbian synaptic
plasticity, which is able to learn either discrete or continuous attractors,
depending on the frequency of presentation of stimuli and on the structure of
sensory coding. A continuous attractor is learned when experience matches
sensory coding, i.e. when the distribution of experienced stimuli matches the
distribution of preferred stimuli of neurons. In that case, there is no
processing of sensory information and neural activity displays maximal entropy.
If experience goes beyond sensory coding, processing is initiated and the
continuous attractor is destabilized into a set of discrete attractors.


title: A Curious Geometrical Fact About Entanglement

abstract:
  I sketch how the set of pure quantum states forms a phase space, and then
point out a curiousity concerning maximally entangled pure states: they form a
minimal Lagrangian submanifold of the set of all pure states. I suggest that
this curiousity should have an interesting physical interpretation.


title: Pauli-Spin-Blockade Transport through a Silicon Double Quantum Dot

abstract:
  We present measurements of resonant tunneling through discrete energy levels
of a silicon double quantum dot formed in a thin silicon-on-insulator layer. In
the absence of piezoelectric phonon coupling, spontaneous phonon emission with
deformation-potential coupling accounts for inelastic tunneling through the
ground states of the two dots. Such transport measurements enable us to observe
a Pauli spin blockade due to effective two-electron spin-triplet correlations,
evident in a distinct bias-polarity dependence of resonant tunneling through
the ground states. The blockade is lifted by the excited-state resonance by
virtue of efficient phonon emission between the ground states. Our experiment
demonstrates considerable potential for investigating silicon-based spin
dynamics and spin-based quantum information processing.


title: Theory of Star Formation

abstract:
  We review current understanding of star formation, outlining an overall
theoretical framework and the observations that motivate it. A conception of
star formation has emerged in which turbulence plays a dual role, both creating
overdensities to initiate gravitational contraction or collapse, and countering
the effects of gravity in these overdense regions. The key dynamical processes
involved in star formation -- turbulence, magnetic fields, and self-gravity --
are highly nonlinear and multidimensional. Physical arguments are used to
identify and explain the features and scalings involved in star formation, and
results from numerical simulations are used to quantify these effects. We
divide star formation into large-scale and small-scale regimes and review each
in turn. Large scales range from galaxies to giant molecular clouds (GMCs) and
their substructures. Important problems include how GMCs form and evolve, what
determines the star formation rate (SFR), and what determines the initial mass
function (IMF). Small scales range from dense cores to the protostellar systems
they beget. We discuss formation of both low- and high-mass stars, including
ongoing accretion. The development of winds and outflows is increasingly well
understood, as are the mechanisms governing angular momentum transport in
disks. Although outstanding questions remain, the framework is now in place to
build a comprehensive theory of star formation that will be tested by the next
generation of telescopes.


title: Charged Rotating Black Branes in Various Dimensions

abstract:
  In this thesis, two different aspects of asymptotically charged rotating
black branes in various dimensions are studied. In the first part, the
thermodynamics of these spacetimes is investigated, while in the second part
the no hair theorem for these spacetimes in four dimensions is considered. In
part I, first, the Euclidean actions of a d-dimensional charged rotating black
brane are computed through the use of the counterterms renormalization method
both in the canonical and the grand-canonical ensemble, and it is shown that
the logarithmic divergencies associated to the Weyl anomalies and matter field
vanish. Second, a Smarr-type formula for the mass as a function of the entropy,
the angular momenta and the electric charge is obtained, which shows that these
quantities satisfy the first law of thermodynamics. Third, by using the
conserved quantities and the Euclidean actions, the thermodynamics potentials
of the system in terms of the temperature, the angular velocities and the
electric potential are obtained both in the canonical and the grand-canonical
ensemble. Fourth, a stability analysis in these two ensembles is performed,
which shows that the system is thermally stable. This is in commensurable with
the fact that there is no Hawking-Page phase transition for black object with
zero curvature horizon. Finally, the logarithmic correction of the entropy due
to the thermal fluctuation around the equilibrium is calculated. In part II,
the cosmological defects are studied, and it is shown that the Abelian Higgs
field equations in the background of a four-dimensional rotating charged black
string have vortex solutions.


title: Jet Properties and Evolution in Small and Intermediate Scale Objects

abstract:
  Kinematic and spectral studies are improving our knowledge of the age
distribution in compact radio sources, providing evidence that small sources
are generally very young. The properties of jets in objects spanning the size
range from a few tens of parsecs to some kiloparsecs become then of particular
interest. Because of our selection criteria and of the small scales involved,
the properties of jets in the population of Compact Symmetric Objects (CSO) are
not well known yet. Polarization properties seem to indicate a strong influence
by the interaction with the dense surrounding medium, and some objects show
evidence of relativistic bulk motion. More evolved jets are present in the
class of Low Power Compact (LPC) sources and a number of cases are discussed
here. Since it is becoming increasingly clear that not all these sources will
survive to evolve into large scale radio galaxies, the question of the final
evolution of the CSO and LPC population is also discussed, with examples of
candidate dying sources.


title: On dilatation operator for a renormalizable theory

abstract:
  Given a renormalizable theory we construct the dilatation operator, in the
sense of generator of RG flow of composite operators. The generator is found as
a differential operator acting on the space of normal symbols of composite
operators in the theory. In the spirit of AdS/CFT correspondence, this operator
is interpreted as the Hamiltonian of the dual theory. In the case of a field
theory with non-abelian gauge symmetry the resulting system is a matrix model.
  The one-loop case is analyzed in details and it is shown that we reproduce
known results from N=4 supersymmetric Yang-Mills theory.


title: On the abundance discrepancy problem in HII regions

abstract:
  The origin of the abundance discrepancy is one of the key problems in the
physics of photoionized nebula. In this work, we analize and discuss data for a
sample of Galactic and extragalactic HII regions where this abundance
discrepancy has been determined. We find that the abundance discrepancy factor
(ADF) is fairly constant and of the order of 2 in all the available sample of
HII regions. This is a rather different behaviour than that observed in
planetary nebulae, where the ADF shows a much wider range of values. We do not
find correlations between the ADF and the O/H, O++/H+ ratios, the ionization
degree, Te(High), Te(Low)/ Te(High), FWHM, and the effective temperature of the
main ionizing stars within the observational uncertainties. These results
indicate that whatever mechanism is producing the abundance discrepancy in HII
regions it does not substantially depend on those nebular parameters. On the
contrary, the ADF seems to be slightly dependent on the excitation energy, a
fact that is consistent with the predictions of the classical temperature
fluctuations paradigm. Finally, we obtain that Te values obtained from OII
recombination lines in HII regions are in agreement with those obtained from
collisionally excited line ratios, a behaviour that is again different from
that observed in planetary nebulae. These similar temperature determinations
are in contradiction with the predictions of the model based on the presence of
chemically inhomogeneous clumps but are consistent with the temperature
fluctuations paradigm. We conclude that all the indications suggest that the
physical mechanism responsible of the abundance discrepancy in HII regions and
planetary nebulae are different.


title: Generalized Einstein-Aether theories and the Solar System

abstract:
  It has been shown that generalized Einstein-Aether theories may lead to
significant modifications to the non-relativistic limit of the Einstein
equations. In this paper we study the effect of a general class of such
theories on the Solar System. We consider corrections to the gravitational
potential in negative and positive powers of distance from the source. Using
measurements of the perihelion shift of Mercury and time delay of radar signals
to Cassini, we place constraints on these corrections. We find that a subclass
of generalized Einstein-Aether theories are compatible with these constraints.


title: Lyalpha heating and its impact on early structure formation

abstract:
  In this paper we have calculated the effect of Lyalpha photons emitted by the
first stars on the evolution of the IGM temperature. We have considered both a
standard Salpeter IMF and a delta-function IMF for very massive stars with mass
300 M_sun. We find that the Lyalpha photons produced by the stellar populations
considered here are able to heat the IGM at z<25, although never above ~100 K.
Stars with a Salpeter IMF are more effective as, due to the contribution from
small-mass long-living stars, they produce a higher Lyalpha background. Lyalpha
heating can affect the subsequent formation of small mass objects by producing
an entropy floor that may limit the amount of gas able to collapse and reduce
the gas clumping.We find that the gas fraction in halos of mass below ~ 5 x
10^6 M_sun is less than 50% (for the smallest masses this fraction drops to 1%
or less) compared to a case without Lyalpha heating. Finally, Lyalpha photons
heat the IGM temperature above the CMB temperature and render the 21cm line
from neutral hydrogen visible in emission at z<15.


title: Proper holomorphic disks in the complement of varieties in \C^2

abstract:
  For any closed analytic set X in C^2 there exists a proper holomorphic
embedding of the unit disk into C^2 such that the image avoids X.


title: Supersymmetric noncommutative solitons

abstract:
  I consider a supersymmetric Bogomolny-type model in 2+1 dimensions
originating from topological string theory. By a gauge fixing this model is
reduced to a supersymmetric U(n) chiral model with a Wess-Zumino-Witten-type
term in 2+1 dimensions. After a noncommutative extension of the model, I employ
the dressing method to construct explicit multi-soliton configurations on
noncommutative R^{2,1|2N}.


title:
From cluster to solid - the variational cluster approximation applied to
  NiO

abstract:
  The variational cluster approximation is applied to the calculation of the
single particle spectral function of NiO. Trial self energies and the numerical
value of the Luttinger-Ward functional are obtained by exact diagonalization of
NiO6-clusters and the single particle parameters of the clusters serve as
variational parameters to obtain a stationary point of the grand potential of
the lattice system. Good agreement with experiment is obtained.


title:
Voids in the Local Volume: a limit on appearance of a galaxy in a DM
  halo

abstract:
  Current explanation of the overabundance of dark matter subhalos in the Local
Group (LG) indicates that there maybe a limit on mass of a halo, which can host
a galaxy. This idea can be tested using voids in the distribution of galaxies:
at some level small voids should not contain any (even dwarf) galaxies. We use
observational samples complete to M_B = -12 with distances less than 8 Mpc to
construct the void function (VF): the distribution of sizes of voids empty of
any galaxies. There are ~30 voids with sizes ranging from 1 to 5 Mpc. We then
study the distribution of dark matter halos in very high resolution simulations
of the LCDM model. The theoretical VF matches the observations remarkably well
only if we use halos with circular velocities larger than 45 +/- 10 km/s. This
agrees with the Local Group predictions. There are smaller halos in the voids,
but they should not produce any luminous matter. Small voids look quite similar
to their giant cousins: the density has a minimum at the center of a void and
it increases as we get closer to the border. Small nonluminous halos inside the
void form a web of tiny filaments. Thus, both the Local Group data and the
nearby voids indicate that isolated halos below 45 +/- 10 km/s must not host
galaxies and that small (few Mpc) voids are truly dark.


title:
On the orbital and physical parameters of the HDE 226868/Cygnus X-1
  binary system

abstract:
  In this paper we explore the consequences of the recent determination of the
mass m=(8.7 +/- 0.8)M_Sun of Cygnus X-1, obtained from the Quasi-Periodic
Oscillation (QPO)-photon index correlation scaling, on the orbital and physical
properties of the binary system HDE 226868/Cygnus X-1. By using such a result
and the latest spectroscopic optical data of the HDE 226868 supergiant star we
get M=(24 +/- 5)M_Sun for its mass. It turns out that deviations from the third
Kepler law significant at more than 1-sigma level would occur if the
inclination i of the system's orbital plane to the plane of the sky falls
outside the range 41-56 deg: such deviations cannot be due to the first
post-Newtonian (1PN) correction to the orbital period because of its smallness;
interpreted in the framework of the Newtonian theory of gravitation as due to
the stellar quadrupole mass moment Q, they are unphysical because Q would take
unreasonably large values. By conservatively assuming that the third Kepler law
is an adequate model for the orbital period we obtain i=(48 +/- 7) deg which
yields for the relative semimajor axis a=(42 +/- 9)R_Sun. Our estimate for the
Roche's lobe of HDE 226868 is r_M = (21 +/- 6)R_Sun.


title: Cohomology of Split Group Extensions and Characteristic Classes

abstract:
  There are characteristic classes that are the obstructions to the vanishing
of the differentials in the Lyndon-Hochischild-Serre spectral sequence of an
extension of an integral lattice L by a group G. These characteristic classes
exist in a given page of the spectral sequence provided the differentials in
the previous pages are all zero. When L decomposes into a sum of G-sublattices,
we show that there are defining relations between the characteristic classes of
L and the characteristic classes of its summands.


title: Radio Observations of AGN in Low Surface Brightness Galaxies

abstract:
  We present preliminary results of a study of the low frequency radio
continuum emission from the nuclei of Giant Low Surface Brightness (LSB)
galaxies. We have mapped the emission and searched for extended features such
as radio lobes/jets associated with AGN activity. LSB galaxies are poor in star
formation and generally less evolved compared to nearby bright spirals. This
paper presents low frequency observations of 3 galaxies; PGC 045080 at 1.4 GHz,
610 MHz, 325MHz, UGC 1922 at 610 MHz and UGC 6614 at 610 MHz. The observations
were done with the GMRT. Radio cores as well as extended structures were
detected and mapped in all three galaxies; the extended emission may be
assocated with jets/lobes associated with AGN activity. Our results indicate
that although these galaxies are optically dim, their nuclei can host AGN that
are bright in the radio domain.


title: Singular measures of circle homeomorphisms with two break points

abstract:
  Let $T_{f}$ be a circle homeomorphism with two break points $a_{b},c_{b}$ and
irrational rotation number $\varrho_{f}$. Suppose that the derivative $Df$ of
its lift $f$ is absolutely continuous on every connected interval of the set
$S^{1}\backslash\{a_{b},c_{b}\}$, that $DlogDf \in L^{1}$ and the product of
the jump ratios of $ Df $ at the break points is nontrivial, i.e.
$\frac{Df_{-}(a_{b})}{Df_{+}(a_{b})}\frac{Df_{-}(c_{b})}{Df_{+}(c_{b})}\neq1$.
We prove that the unique $T_{f}$- invariant probability measure $\mu_{f}$ is
then singular with respect to Lebesgue measure $l$ on $S^{1}$.


title: Chandra Observation of PSR B1823-13 and its Pulsar Wind Nebula

abstract:
  We report on an observation of the Vela-like pulsar B1823-13 and its
synchrotron nebula with Chandra.The pulsar's spectrum fits a power-law model
with a photon index Gamma_PSR=2.4 for the plausible hydrogen column density
n_H=10^{22} cm^{-2}, corresponding to the luminosity L_PSR=8*10^{31} ergs
s^{-1} in the 0.5-8 keV band, at a distance of 4 kpc. The pulsar radiation
likely includes magnetospheric and thermal components, but they cannot be
reliably separated because of the small number of counts detected and strong
interstellar absorption. The pulsar is surrounded by a compact, 25''x 10'',
pulsar wind nebula (PWN) elongated in the east-west direction, which includes a
brighter inner component, 7''x 3'', elongated in the northeast-southwest
direction. The slope of the compact PWN spectrum is Gamma_comp=1.3, and the
0.5-8 keV luminosity is L_comp~3*10^{32} ergs s^{-1}. The compact PWN is
surrounded by asymmetric diffuse emission (extended PWN) seen up to at least
2.4' south of the pulsar, with a softer spectrum (Gamma_ext=1.9), and the 0.5-8
keV luminosity L_ext~10^{33}-10^{34} ergs s^{-1}. We also measured the pulsar's
proper motion using archival VLA data: \mu_\alpha=23.0+/-2.5 mas yr^{-1},
  \mu_\delta=-3.9+/-3.3 mas yr^{-1}, which corresponds to the transverse
velocity v_perp=440 km s^{-1}. The direction of the proper motion is
approximately parallel to the elongation of the compact PWN, but it is nearly
perpendicular to that of the extended PWN and to the direction towards the
center of the bright VHE gamma-ray source HESS J1825-137, which is likely
powered by PSR B1823-13.


title:
$A$-dependence of coherent electroproduction of $\rho^{0}$ mesons on
  nuclei in forward direction

abstract:
  This article presents the $A$-dependence of the differential cross section
for the coherent electroproduction of vector mesons on nuclei in forward
direction, at fixed values of longitudinal momentum transfer $q_{L}$. It is
shown that such cross section has complicated behavior over the atomic mass
number $A$ with local minimums and maximums. It is also shown that a ratio of
the real to the imaginary parts of the forward coherent amplitude on nuclei
$\alpha_{A} = \Re e{f_{A}} / \Im m{f_{A}}$ has breaking points at some values
of $A$. Comparison of the behaviors of the normalized cross section
$\Big(\frac{d\sigma}{d\Omega}\Big)_{A}\Big/\Big(\frac{d\sigma}{d\Omega}\Big)_{N}$
and $\alpha_{A}$ over $A$ shows that the location of minimums of the cross
section are very close to the breaking points of $\alpha_{A}$.


title: e-Science initiatives in Venezuela

abstract:
  Within the context of the nascent e-Science infrastructure in Venezuela, we
describe several web-based scientific applications developed at the Centro
Nacional de Calculo Cientifico Universidad de Los Andes (CeCalCULA), Merida,
and at the Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas.
The different strategies that have been followed for implementing quantum
chemistry and atomic physics applications are presented. We also briefly
discuss a damage portal based on dynamic, nonlinear, finite elements of lumped
damage mechanics and a biomedical portal developed within the framework of the
\textit{E-Infrastructure shared between Europe and Latin America} (EELA)
initiative for searching common sequences and inferring their functions in
parasitic diseases such as leishmaniasis, chagas and malaria.


title:
On the Hausdorff dimension of invariant measures of weakly contracting
  on average measurable IFS

abstract:
  We consider measures which are invariant under a measurable iterated function
system with positive, place-dependent probabilities in a separable metric
space. We provide an upper bound of the Hausdorff dimension of such a measure
if it is ergodic. We also prove that it is ergodic iff the related skew product
is.


title:
Exact Extended Supersymmetry on a Lattice: Twisted N=4 Super Yang-Mills
  in Three Dimensions

abstract:
  We propose a lattice formulation of three dimensional super Yang-Mills model
with a twisted N=4 supersymmetry. The extended supersymmetry algebra of all the
eight supercharges is fully and exactly realized on the lattice with a modified
"Leibniz rule". The formulation we employ here is a three dimensional extension
of manifestly gauge covariant method which was developed in our previous
proposal of Dirac-Kaehler twisted N=2 super Yang-Mills on two dimensional
lattice. The twisted N=4 supersymmetry algebra is geometrically realized on a
three dimensional lattice with link supercharges and the use of "shifted"
(anti-)commutators. A possible solution to the recent critiques on the link
formulation will be discussed.


title: The Kinetostatic Optimization of a Novel Prismatic Drive

abstract:
  The design of a mechanical transmission taking into account the transmitted
forces is reported in this paper. This transmission is based on Slide-o-Cam, a
cam mechanism with multiple rollers mounted on a common translating follower.
The design of Slide-o-Cam, a transmission intended to produce a sliding motion
from a turning drive, or vice versa, was reported elsewhere. This transmission
provides pure-rolling motion, thereby reducing the friction of rack-and-pinions
and linear drives. The pressure angle is a suitable performance index for this
transmission because it determines the amount of force transmitted to the load
vs. that transmitted to the machine frame. To assess the transmission
capability of the mechanism, the Hertz formula is introduced to calculate the
stresses on the rollers and on the cams. The final transmission is intended to
replace the current ball-screws in the Orthoglide, a three-DOF parallel robot
for the production of translational motions, currently under development for
machining applications at Ecole Centrale de Nantes.


title: Chiral Plaquette Polaron Theory of Cuprate Superconductivity

abstract:
  Ab-initio density functional calculations on explicitly doped
La(2-x)Sr(x)CuO4 find doping creates localized holes in out-of-plane orbitals.
A model for superconductivity is developed based on the assumption that doping
leads to the formation of holes on a four-site Cu plaquette composed of the
out-of-plane A1 orbitals apical O pz, planar Cu dz2, and planar O psigma. This
is in contrast to the assumption of hole doping into planar Cu dx2-y2 and O
psigma orbitals as in the t-J model. Interaction of holes with the d9 spin
background leads to chiral polarons with either a clockwise or anti-clockwise
charge current. When the polaron plaquettes percolate through the crystal at
x~0.05 for LaSrCuO, a Cu dx2-y2 and planar O psigma band is formed. Spin
exchange Coulomb repulsion with chiral polarons leads to D-wave
superconductivity. The equivalent of the Debye energy in phonon
superconductivity is the maximum energy separation between a chiral polaron and
its time-reversed partner. An additive skew-scattering contribution to the Hall
effect is induced by chiral polarons and leads to a temperature dependent Hall
effect that fits the measured values for LaSrCuO. The integrated imaginary
susceptibility satisfies omega/T scaling due to chirality and spin-flip
scattering of polarons along with a uniform distribution of polaron energy
splittings. The derived functional form is compatible with experiments. The
static spin structure factor is computed and is incommensurate with a
separation distance from (pi,pi) given by ~(2pi)x. Coulomb scattering of the
x2-y2 band with polarons leads to linear resistivity. Coupling of the x2-y2
band to the undoped Cu d9 spins leads to the ARPES pseudogap and its doping and
temperature dependence.


title: Degenerating families of dendrograms

abstract:
  Dendrograms used in data analysis are ultrametric spaces, hence objects of
nonarchimedean geometry. It is known that there exist $p$-adic representation
of dendrograms. Completed by a point at infinity, they can be viewed as
subtrees of the Bruhat-Tits tree associated to the $p$-adic projective line.
The implications are that certain moduli spaces known in algebraic geometry are
$p$-adic parameter spaces of (families of) dendrograms, and stochastic
classification can also be handled within this framework. At the end, we
calculate the topology of the hidden part of a dendrogram.


title:
Diquark Representations for Singly Heavy Baryons with Light Staggered
  Quarks

abstract:
  In the staggered fermion formulation of lattice QCD, we construct diquark
operators which are to be embedded in singly heavy baryons. The group
theoretical connections between continuum and lattice staggered diquark
representations are established.


title: Bounds on new physics from B_s mixing

abstract:
  I summarize the observables constraining the B_s-B_s-bar mixing complex and
present a new calculation of the element Gamma_{12}^s of the decay matrix.
Gamma_{12}^s enters the prediction of the width difference Delta Gamma_s, for
which we obtain Delta Gamma_s^SM = 0.088 +/- 0.017 ps^(-1), if no new physics
enters B_s-B_s-bar mixing. Applying our formulae to Tevatron data we find a
deviation of the B_s-B_s-bar mixing phase phi_s from its Standard Model value
by 2 standard deviations. I stress that present data do not give any
information on the sign of Delta Gamma_s.


title: Introduction to Quantum Mechanics and the Quantum-Classical transition

abstract:
  In this paper we present a survey of the use of differential geometric
formalisms to describe Quantum Mechanics. We analyze Schroedinger and
Heisenberg frameworks from this perspective and discuss how the momentum map
associated to the action of the unitary group on the Hilbert space allows to
relate both approaches. We also study Weyl-Wigner approach to Quantum Mechanics
and discuss the implications of bi-Hamiltonian structures at the quantum level.


title: Mumford dendrograms

abstract:
  An effective $p$-adic encoding of dendrograms is presented through an
explicit embedding into the Bruhat-Tits tree for a $p$-adic number field. This
field depends on the number of children of a vertex and is a finite extension
of the field of $p$-adic numbers. It is shown that fixing $p$-adic
representatives of the residue field allows a natural way of encoding strings
by identifying a given alphabet with such representatives. A simple $p$-adic
hierarchic classification algorithm is derived for $p$-adic numbers, and is
applied to strings over finite alphabets. Examples of DNA coding are presented
and discussed. Finally, new geometric and combinatorial invariants of time
series of $p$-adic dendrograms are developped.


title:
Security analysis of decoy state quantum key distribution incorporating
  finite statistics

abstract:
  Decoy state method quantum key distribution (QKD) is one of the promising
practical solutions to BB84 QKD with coherent light pulses. In the real world,
however, statistical fluctuations with the finite code length cannot be
negligible, and the securities of theoretical and experimental researches of
the decoy method state QKD so far are based on the asymptotic GLLP's formula
which guarantees only that the limit of eavesdropper's information becomes zero
as the code length approaches infinity. In this paper, we propose a
substantially improved decoy state QKD in the framework of the finite code
length and derive the upper bound of eavesdropper's information in the finite
code length decoy state QKD with arbitrary number of decoy states of different
intensities incorporating the finite statistics. We also show the performance
of our decoy QKD and optimal values of parameters by numerical simulation.


title:
Electron-hole contribution to the apparent s-d exchange interaction in
  III-V diluted magnetic semiconductors

abstract:
  Spin splitting of photoelectrons in p-type and electrons in n-type III-V
Mn-based diluted magnetic semiconductors is studied theoretically. It is
demonstrated that the unusual sign and magnitude of the apparent s-d exchange
integral reported for GaAs:Mn arises from exchange interactions between
electrons and holes bound to Mn acceptors. This interaction dominates over the
coupling between electrons and Mn spins, so far regarded as the main source of
spin-dependent phenomena. A reduced magnitude of the apparent s-d exchange
integral found in n-type materials is explained by the presence of repulsive
Coulomb potentials at ionized Mn acceptors and a bottleneck effect.


title:
Quantisation of Hopping Magnetoresistance Prefactor in Strongly
  Correlated Two-Dimensional Electron Systems

abstract:
  We report an universal behaviour of hopping transport in strongly interacting
mesoscopic two-dimensional electron systems (2DES). In a certain window of
background disorder, the resistivity at low perpendicular magnetic fields
follows the expected relation $\rho(B_\perp) = \rho_{\rm{B}}\exp(\alpha
B_\perp^2)$. The prefactor $\rho_{\rm{B}}$ decreases exponentially with
increasing electron density but saturates to a finite value at higher
densities. Strikingly, this value is found to be universal when expressed in
terms of absolute resistance and and shows quantisation at $R_{\rm{B}}\approx
h/e^2$ and $R_{\rm{B}}\approx 1/2$ $ h/e^2$. We suggest a strongly correlated
electronic phase as a possible explanation.


title:
Strong orientational effect of stretched aerogel on the 3He order
  parameter

abstract:
  Deformation of aerogel strongly modifies the orientation of the order
parameter of superfluid 3He confined in aerogel. We used a radial squeezing of
aerogel to keep the orbital angular momentum of the 3He Cooper pairs in the
plane perpendicular to the magnetic field. We did not find strong evidence for
a "polar" phase, with a nodal line along the equator of the Fermi surface,
predicted to occur at large radial squeezing. Instead we observed 3He-A with a
clear experimental evidence of the destruction of the long-range order by
random anisotropy -- the Larkin-Imry-Ma effect. In 3He-B we observed and
identified new modes of NMR, which are impossible to obtain in bulk 3He-B. One
of these modes is characterized by a repulsive interaction between magnons,
which is suitable for the magnon Bose-Einstein condensation (BEC).


title: Exchangeable Random Networks

abstract:
  We introduce and study a class of exchangeable random graph ensembles. They
can be used as statistical null models for empirical networks, and as a tool
for theoretical investigations. We provide general theorems that carachterize
the degree distribution of the ensemble graphs, together with some features
that are important for applications, such as subgraph distributions and kernel
of the adjacency matrix. These results are used to compare to other models of
simple and complex networks. A particular case of directed networks with
power-law out--degree is studied in more detail, as an example of the
flexibility of the model in applications.


title: Singular point characterization in microscopic flows

abstract:
  We suggest an approach to microrheology based on optical traps in order to
measure fluid fluxes around singular points of fluid flows. We experimentally
demonstrate this technique, applying it to the characterization of controlled
flows produced by a set of birefringent spheres spinning due to the transfer of
light angular momentum. Unlike the previous techniques, this method is able to
distinguish between a singular point in a complex flow and the absence of flow
at all; furthermore it permits us to characterize the stability of the singular
point.


title:
Detecting spatial patterns with the cumulant function. Part II: An
  application to El Nino

abstract:
  The spatial coherence of a measured variable (e.g. temperature or pressure)
is often studied to determine the regions where this variable varies the most
or to find teleconnections, i.e. correlations between specific regions. While
usual methods to find spatial patterns, such as Principal Components Analysis
(PCA), are constrained by linear symmetries, the dependence of variables such
as temperature or pressure at different locations is generally nonlinear. In
particular, large deviations from the sample mean are expected to be strongly
affected by such nonlinearities. Here we apply a newly developed nonlinear
technique (Maxima of Cumulant Function, MCF) for the detection of typical
spatial patterns that largely deviate from the mean. In order to test the
technique and to introduce the methodology, we focus on the El Nino/Southern
Oscillation and its spatial patterns. We find nonsymmetric temperature patterns
corresponding to El Nino and La Nina, and we compare the results of MCF with
other techniques, such as the symmetric solutions of PCA, and the nonsymmetric
solutions of Nonlinear PCA (NLPCA). We found that MCF solutions are more
reliable than the NLPCA fits, and can capture mixtures of principal components.
Finally, we apply Extreme Value Theory on the temporal variations extracted
from our methodology. We find that the tails of the distribution of extreme
temperatures during La Nina episodes is bounded, while the tail during El Ninos
is less likely to be bounded. This implies that the mean spatial patterns of
the two phases are asymmetric, as well as the behaviour of their extremes.


title: Parallel Tiled QR Factorization for Multicore Architectures

abstract:
  As multicore systems continue to gain ground in the High Performance
Computing world, linear algebra algorithms have to be reformulated or new
algorithms have to be developed in order to take advantage of the architectural
features on these new processors. Fine grain parallelism becomes a major
requirement and introduces the necessity of loose synchronization in the
parallel execution of an operation. This paper presents an algorithm for the QR
factorization where the operations can be represented as a sequence of small
tasks that operate on square blocks of data. These tasks can be dynamically
scheduled for execution based on the dependencies among them and on the
availability of computational resources. This may result in an out of order
execution of the tasks which will completely hide the presence of intrinsically
sequential tasks in the factorization. Performance comparisons are presented
with the LAPACK algorithm for QR factorization where parallelism can only be
exploited at the level of the BLAS operations.


title: Superstring partition functions in the doubled formalism

abstract:
  Computation of superstring partition function for the non-linear sigma model
on the product of a two-torus and its dual within the scope of the doubled
formalism is presented. We verify that it reproduces the partition functions of
the toroidally compactified type--IIA and type--IIB theories for appropriate
choices of the GSO projection.


title:
A Six Degree-Of-Freedom Haptic Device Based On The Orthoglide And A
  Hybrid Agile Eye

abstract:
  This paper is devoted to the kinematic design of a new six degree-of-freedom
haptic device using two parallel mechanisms. The first one, called orthoglide,
provides the translation motions and the second one, called agile eye, produces
the rotational motions. These two motions are decoupled to simplify the direct
and inverse kinematics, as it is needed for real-time control. To reduce the
inertial load, the motors are fixed on the base and a transmission with two
universal joints is used to transmit the rotational motions from the base to
the end-effector. Two alternative wrists are proposed (i), the agile eye with
three degrees of freedom or (ii) a hybrid wrist made by the assembly of a
two-dof agile eye with a rotary motor. The last one is optimized to increase
its stiffness and to decrease the number of moving parts.


title: Hodge metrics and the curvature of higher direct images

abstract:
  Using the harmonic theory developed by Takegoshi for representation of
relative cohomology and the framework of computation of curvature of direct
images bundles by Berndtsson, we prove that the higher direct images by a
smooth morphism of the relative canonical bundle twisted by a semi-positive
vector bundle are locally free and semi-positively curved, when endowed with a
suitable Hodge type metric.


title: Analyse Comparative des Manipulateurs 3R \`a Axes Orthogonaux

abstract:
  A family of 3R orthogonal manipulators without offset on the third body can
be divided into exactly nine workspace topologies. The workspace is
characterized in a half-cross section by the singular curves. The workspace
topology is defined by the number of cusps and nodes that appear on these
singular curves. Based on this classification, we evaluate theses manipulators
by the condition number related to the joint space and the proportion of the
region with four inverse kinematic solutions compared to a sphere containing
all the workspace. This second performance number is in relation with the
workspace. We determine finally le topology of workspace to which belong
manipulators having the best performance number values.


title:
An Exhaustive Study of the Workspace Topologies of all 3R Orthogonal
  Manipulators with Geometric Simplifications

abstract:
  This paper analyses the workspace of the three-revolute orthogonal
manipulators that have at least one of their DH parameters equal to zero. These
manipulators are classified into different groups with similar kinematic
properties. The classification criteria are based on the topology of the
workspace. Each group is evaluated according to interesting kinematic
properties such as the size of the workspace subregion reachable with four
inverse kinematic solutions, the existence and the size of voids, and the size
of the regions of feasible paths in the workspace.


title:
Dynamics of wave packets in two-dimensional crystals under external
  magnetic and electric fields: Vortices formation

abstract:
  In the present work we deal with the dynamics of wave packets in a
two-dimensional crystal under the action of magnetic and electric fields. The
magnetic field is perpendicular to the plane and the electric field is on the
plane. In the simulations we considered a symmetric gauge for the vector
potential while the initial wave packet was assumed to have a gaussian
structure with given velocities. The parameters that control the kind of time
evolution of the packets are: the width of the gaussian, its velocity, and, the
intensity and direction of the electric field as well as the magnitude of the
magnetic field. In order to characterize the kind of propagation we evaluated
the mean-square displacement (MSD), the participation function and which is
more important we were able to follow the wave at different times, which
allowed us to see the time evolution of the centroid of the wave packets. A
novel effect was observed, namely, the dynamics is such that the wave function
\emph{splits} into two or more components and \emph{reconstructs} successively
as time goes, vortices are forming. To our understanding this is the first time
such an effect is reported. As for the inclusion of the electric field, we
observe a complex behavior of the wave packet as well as note that the vortices
propagate in direction perpendicular to the applied electric field. A similar
behavior presented by the classical treatment, In our case we give a quantum
mechanics explanation for that


title:
Power Dependence of the Photocurrent Lineshape in a Semiconductor
  Quantum Dot

abstract:
  We propose a kinetic theory to describe the power dependence, $I_{PC}(P)$, of
the photocurrent (PC) lineshape in optically pumped quantum dots at low
temperatures, in both zero and finite magnetic fields. We show that there is a
crossover power $P_c$, determined by the electron and hole tunneling rates, at
which the photocurrent spectra become strongly influenced by the dot kinetics,
and no longer reflect the exciton lifetime in the dot. For $P>P_c$, we show
that the photocurrent saturates due to the slow hole escape rate (in e.g.,
InGaAs/GaAs dots), whereas the line-width increases with power: $\Gamma \propto
\sqrt{P}$. We also analyze to what measure the spin-doublet lineshape of the
photocurrent studied in a high magnetic field reflects the degree of circular
polarization of the incident light.


title: Coherence of an Entangled Exciton-Photon State

abstract:
  We study the effect of the exciton fine-structure splitting on the
polarisation-entanglement of photon pairs produced by the biexciton cascade in
a single quantum dot. The entanglement is found to persist despite separations
between the intermediate energy levels of up to 4 micro-eV. Measurements
demonstrate that entanglement of the photon pair is robust to the dephasing of
the intermediate exciton state responsible for the first order coherence time
of either single photon. We present a theoretical framework taking into account
the effects of spin-scattering, background light and dephasing. We distinguish
between the first-order coherence time, and a parameter which we measure for
the first time and define as the cross-coherence time.


title:
Phase separation and competition of superconductivity and magnetism in
  the two-dimensional Hubbard model: From strong to weak coupling

abstract:
  Cooperation and competition between the antiferromagnetic, d-wave
superconducting and Mott-insulating states are explored for the two-dimensional
Hubbard model including nearest and next-nearest-neighbor hoppings at zero
temperature. Using the variational cluster approach with clusters of different
shapes and sizes up to 10 sites, it is found that the doping-driven transition
from a phase with microscopic coexistence of antiferromagnetism and
superconductivity to a purely superconducting phase is discontinuous for strong
interaction and accompanied by phase separation. At half-filling the system is
in an antiferromagnetic Mott-insulating state with vanishing charge
compressibility. Upon decreasing the interaction strength U below a certain
critical value of roughly U=4 (in units of the nearest-neighbor hopping),
however, the filling-dependent magnetic transition changes its character and
becomes continuous. Phase separation or, more carefully, the tendency towards
the formation of inhomogeneous states disappears. This critical value is in
contrast to previous studies, where a much larger value was obtained. Moreover,
we find that the system at half-filling undergoes the Mott transition from an
insulator to a state with a finite charge compressibility at essentially the
same value. The weakly correlated state at half-filling exhibits
superconductivity microscopically admixed to the antiferromagnetic order. This
scenario suggests a close relation between phase separation and the
Mott-insulator physics.


title: Brane-World Black Hole Solutions via a Confining Potential

abstract:
  Using a confining potential, we consider spherically symmetric vacuum (static
black hole) solutions in a brane-world scenario. Working with a constant
curvature bulk, two interesting cases/solutions are studied. A Schwarzschild-de
Sitter black hole solution similar to the standard solution in the presence of
a cosmological constant is obtained which confirms the idea that an extra term
in the field equations on the brane can play the role of a positive
cosmological constant and may be used to account for the accelerated expansion
of the universe. The other solution is one in which we can have a proper
potential to explain the galaxy rotation curves without assuming the existence
of dark matter and without working with new modified theories (modified
Newtonian dynamics).


title:
Practical Approach to Knowledge-based Question Answering with Natural
  Language Understanding and Advanced Reasoning

abstract:
  This research hypothesized that a practical approach in the form of a
solution framework known as Natural Language Understanding and Reasoning for
Intelligence (NaLURI), which combines full-discourse natural language
understanding, powerful representation formalism capable of exploiting
ontological information and reasoning approach with advanced features, will
solve the following problems without compromising practicality factors: 1)
restriction on the nature of question and response, and 2) limitation to scale
across domains and to real-life natural language text.


title:
Integration of a Balanced Virtual Manikin in a Virtual Reality Platform
  aimed at Virtual Prototyping

abstract:
  The work presented here is aimed at introducing a virtual human controller in
a virtual prototyping framework. After a brief introduction describing the
problem solved in the paper, we describe the interest as for digital humans in
the context of concurrent engineering. This leads us to draw a control
architecture enabling to drive virtual humans in a real-time immersed way, and
to interact with the product, through motion capture. Unfortunately, we show
this control scheme can lead to unfeasible movements because of the lack of
balance control. Introducing such a controller is a problem that was never
addressed in the context of real-time. We propose an implementation of a
balance controller, that we insert into the previously described control
scheme. Next section is dedicated to show the results we obtained. Finally, we
propose a virtual reality platform into which the digital character controller
is integrated.


title: Form Factors in the Quark Resonance Model

abstract:
  Vector and axial form factors in the quark resonance model are analyzed with
a combination of theoretical and phenomenological arguments. The new form of
form factors is deduced from $\Delta$(1232) excitation models and available
data. The vector part is shown to agree with the resonant contribution to
electron-proton inclusive $F_2$ data. The axial part is obtained by finding a
simultaneous fit to ANL and BNL $\frac{d \sigma}{d Q^2}$ neutrino scattering
data. The best fit corresponds to $C_5^A(0)=0.88$ in the Rarita Schwinger
formalism.


title: Balanced Virtual Humans Interacting with their Environment

abstract:
  The animation of human avatars seems very successful; the computer graphics
industry shows outstanding results in films everyday, the game industry
achieves exploits... Nevertheless, the animation and control processes of such
manikins are very painful. It takes days to a specialist to build such animated
sequences, and it is not adaptive to any type of modifications. Our main
purpose is the virtual human for engineering, especially virtual prototyping.
As for this domain of activity, such amounts of time are prohibitive.


title: Virtual reality: A human centered tool for improving Manufacturing

abstract:
  Manufacturing is using Virtual Reality tools to enhance the product life
cycle. Their definitions are still in flux and it is necessary to define their
connections. Thus, firstly, we will introduce more closely some definitions
where we will find that, if the Virtual manufacturing concepts originate from
machining operations and evolve in this manufacturing area, there exist a lot
of applications in different fields such as casting, forging, sheet
metalworking and robotics (mechanisms). From the recent projects in Europe or
in USA, we notice that the human perception or the simulation of mannequin is
more and more needed in both fields. In this context, we have isolated some
applications as ergonomic studies, assembly and maintenance simulation, design
or training where the virtual reality tools can be applied. Thus, we find out a
family of applications where the virtual reality tools give the engineers the
main role in the optimization process. We will illustrate our paper by several
examples where virtual reality interfaces are used and combined with
optimization tools as multi-agent systems.