title: Symmetries in the system of type $A_5^{(2)}$

abstract:
  In this paper, we propose a 3-parameter family of coupled Painlev\'e III
systems in dimension four with affine Weyl group symmetry of type $A_5^{(2)}$.
We also propose its symmetric form in which the $A_5^{(2)}$-symmetries become
clearly visible.


title:
Cutting surfaces and applications to periodic points and chaotic-like
  dynamics

abstract:
  In this paper we propose an elementary topological approach which unifies and
extends various different results concerning fixed points and periodic points
for maps defined on sets homeomorphic to rectangles embedded in euclidean
spaces. We also investigate the associated discrete semidynamical systems in
view of detecting the presence of chaotic-like dynamics.


title: Quantum pump effect in one-dimensional systems of Dirac fermions

abstract:
  We investigate the behavior of the directed current in one-dimensional
systems of Dirac fermions driven by local periodic potentials in the forward as
well in backscattering channels. We treat the problem with Keldysh
non-equilibrium Green's function formalism. We present the exact solution for
the case of an infinite wire and show that in this case the dc current vanishes
identically. We also investigate a confined system consistent in an annular
arrangement coupled to a particle reservoir. We present a perturbative
treatment that allows for the analytical expressions of the dc current in the
lowest order of the amplitudes of the potential. We also present results
obtained from the exact numerical solution of the problem.


title: CdZnTe:Cl crystals for X-ray computer tomography detectors

abstract:
  Processes of growth of semi-insulating Cd(1-x)Zn(x)Te:Cl crystals (x = 0.0002
and 0.1) of n-type conductivity are investigated. From the grown crystals
detectors for X-ray computer tomography with small value of photocurrent memory
(afterglow) (0.1-0.3%) are obtained.


title: Symmetries in the system of type $D_4^{(1)}$

abstract:
  In this paper, we propose a 4-parameter family of coupled Painlev\'e III
systems in dimension four with affine Weyl group symmetry of type $D_4^{(1)}$.
We also propose its symmetric form in which the $D_4^{(1)}$-symmetries become
clearly visible.


title:
Survival of the mm-cm size grain population observed in protoplanetary
  disks

abstract:
  Millimeter interferometry provides evidence for the presence of mm to cm size
"pebbles" in the outer parts of disks around pre-main-sequence stars. The
observations suggest that large grains are produced relatively early in disk
evolution (< 1 Myr) and remain at large radii for longer periods of time (5 to
10 Myr). Simple theoretical estimates of the radial drift time of solid
particles, however, imply that they would drift inward over a time scale of
less than 0.1 Myr. In this paper, we address this conflict between theory and
observation, using more detailed theoretical models, including the effects of
sedimentation, collective drag forces and turbulent viscosity. We find that,
although these effects slow down the radial drift of the dust particles, this
reduction is not sufficient to explain the observationally determined long
survival time of mm/cm-sized grains in protoplanetary disks. However, if for
some reason the gas to dust ratio in the disk is reduced by at least a factor
of 20 from the canonical value of 100 (for instance through photoevaporation of
the gas), then the radial drift time scales become sufficiently large to be in
agreement with observations.


title: Discrete Choices under Social Influence: Generic Properties

abstract:
  We consider a model of socially interacting individuals that make a binary
choice in a context of positive additive endogenous externalities. It
encompasses as particular cases several models from the sociology and economics
literature. We extend previous results to the case of a general distribution of
idiosyncratic preferences, called here Idiosyncratic Willingnesses to Pay
(IWP). Positive additive externalities yield a family of inverse demand curves
that include the classical downward sloping ones but also new ones with non
constant convexity. When j, the ratio of the social influence strength to the
standard deviation of the IWP distribution, is small enough, the inverse demand
is a classical monotonic (decreasing) function of the adoption rate. Even if
the IWP distribution is mono-modal, there is a critical value of j above which
the inverse demand is non monotonic, decreasing for small and high adoption
rates, but increasing within some intermediate range. Depending on the price
there are thus either one or two equilibria. Beyond this first result, we
exhibit the generic properties of the boundaries limiting the regions where the
system presents different types of equilibria (unique or multiple). These
properties are shown to depend only on qualitative features of the IWP
distribution: modality (number of maxima), smoothness and type of support
(compact or infinite). The main results are summarized as phase diagrams in the
space of the model parameters, on which the regions of multiple equilibria are
precisely delimited.


title:
No interactions for a collection of spin-two fields intermediated by a
  massive Rarita-Schwinger field

abstract:
  The cross-couplings among several massless spin-two fields (described in the
free limit by a sum of Pauli-Fierz actions) in the presence of a massive
Rarita-Schwinger field are investigated in the framework of the deformation
theory based on local BRST cohomology. Under the hypotheses of locality,
smoothness of the interactions in the coupling constant, Poincare invariance,
Lorentz covariance, and the preservation of the number of derivatives on each
field, we prove that there are no consistent cross-interactions among different
gravitons with a positively defined metric in internal space in the presence of
a massive Rarita-Schwinger field. The basic features of the couplings between a
single Pauli-Fierz field and a massive Rarita-Schwinger field are also
emphasized.


title: Sulphur abundances from the SI near-infrared triplet at 1045 nm

abstract:
  context : Unlike silicon and calcium, sulphur is an alpha-element which does
not form dust. Some of the available observations of the evolution of sulphur
with metallicity indicate an increased scatter of sulphur to iron ratios at low
metallicities or even a bimodal distribution, with some stars showing constant
S/Fe at all metallicities and others showing an increasing S/Fe ratio with
decreasing metallicity. In metal-poor stars SI lines of Multiplet 1 at 920 nm
are not yet too weak to permit to measure the sulphur abundance A(S), however
in ground-based observations they are severely affected by telluric lines. aims
: We investigate the possibility to measure sulphur abundances from SI Mult. 3
at 1045 nm lines, which lie in the near infra-red. These are slightly weaker
than those of Mult. 1, but lie in a range not affected by telluric lines.
method We investigate the lines of Mult.3 in the Sun (G2V), Procyon (F5V), HD
33256 (F5V), HD 25069 (G9V) and epsilon Eri (HD 22049, K2V). For the Sun and
Procyon the analysis has been performed with CO5BOLD 3D hydrodynamical model
atmospheres, for the other three stars, for which hydrodynamical simulations
are not available, the analysis has been performed using 1D model atmospheres.
results For our sample of stars we find a global agreement of A(S) from lines
of different multiplets. conclusions : Our results suggest that the infrared
lines of Mult. 3 are a viable indicator of the sulphur abundance which, because
of the intrinsic strength of this multiplet, should be suitable to study the
trend of [S/Fe] at low metallicities.


title:
Competition between unconventional superconductivity and incommensurate
  antiferromagnetic order in CeRh1-xCoxIn5

abstract:
  Elastic neutron diffraction measurements were performed on the quasi-two
dimensional heavy fermion system CeRh1-xCoxIn5, ranging from an incommensurate
antiferromagnet for low x to an unconventional superconductor on the Co-rich
end of the phase diagram. We found that the superconductivity competes with the
incommensurate antiferromagnetic (AFM) order characterized by qI=(1/2, 1/2,
delta) with delta=0.298, while it coexists with the commensurate AFM order with
qc=(1/2, 1/2, 1/2). This is in sharp contrast to the CeRh1-xIrxIn5 system,
where both the commensurate and incommensurate magnetic orders coexist with the
superconductivity. These results reveal that particular areas on the Fermi
surface nested by qI play an active role in forming the superconducting state
in CeCoIn5.


title:
Existence of graphs with sub exponential transitions probability decay
  and applications

abstract:
  In this paper, we present a complete proof of the construction of graphs with
bounded valency such that the simple random walk has a return probability at
time $n$ at the origin of order $exp(-n^{\alpha}),$ for fixed $\alpha \in
[0,1[$ and with Folner function $exp(n^{\frac{2\alpha}{1-\alpha}})$. We begin
by giving a more detailled proof of this result contained in (see
\cite{ershdur}). In the second part, we give an application of the existence of
such graphs. We obtain bounds of the correct order for some functional of the
local time of a simple random walk on an infinite cluster on the percolation
model.


title:
INTEGRAL and Multiwavelength Observations of the Blazar Mrk 421 during
  an Active Phase

abstract:
  A ToO observation of the TeV-emitting blazar Mrk 421 with INTEGRAL was
triggered in June 2006 by an increase of the RXTE count rate to more than 30
mCrab. The source was then observed with all INTEGRAL instruments with the
exception of the spectrometer SPI for a total exposure of 829 ks. During this
time several outbursts were observed by IBIS and JEM-X. Multiwavelength
observations were immediately triggered and the source was observed at radio,
optical and X-ray wavelengths up to TeV energies. The data obtained during
these observations are analysed with respect to spectral evolution and
correlated variability. Preliminary results of the analysis are presented in
this poster.


title:
Scale invariant quantum potential leading to globally self-trapped wave
  function in Madelung fluid

abstract:
  We show in spatially one dimensional Madelung fluid that a simple requirement
on local stability of the maximum of quantum probability density will, if
combined with the global scale invariance of quantum potential, lead to a class
of quantum probability densities globally being self-trapped by their own
self-generated quantum potentials, possessing only a finite-size spatial
support. It turns out to belong to a class of the most probable wave function
given its energy through the maximum entropy principle. We proceed to show that
there is a limiting case in which the quantum probability density becomes the
stationary-moving soliton-like solution of the Schr\"odinger equation.


title:
Probing the Nuclear Symmetry Energy with Heavy-Ion Reactions Induced by
  Neutron-Rich Nuclei

abstract:
  Heavy-ion reactions induced by neutron-rich nuclei provide a unique means to
investigate the equation of state of isospin-asymmetric nuclear matter,
especially the density dependence of the nuclear symmetry energy. In
particular, recent analyses of the isospin diffusion data in heavy-ion
reactions have already put a stringent constraint on the nuclear symmetry
energy around the nuclear matter saturation density. We review this exciting
result and discuss its implications on nuclear effective interactions and the
neutron skin thickness of heavy nuclei. In addition, we also review the
theoretical progress on probing the high density behaviors of the nuclear
symmetry energy in heavy-ion reactions induced by high energy radioactive
beams.


title: On Gauged Renormalisation Group Transformations of Lattice Fermions

abstract:
  We construct a hierarchy of lattice fermions, where the coarser lattice Dirac
operator is the Schur complement of the block UL decomposition of the finer
lattice operator. We show that the construction is an exact gauged
renormalisation group transformation of the lattice action. In particular,
using such a transformation and the QCDLAB tool, it is shown how to implement
the Ginsparg-Wilson strategy for chiral fermions in the presence of a dynamical
gauge field. The scheme allows, for the first time, a full multigrid algorithm
for lattice quarks.


title:
Variations in the lithium abundances of turn off stars in the globular
  cluster 47 Tuc

abstract:
  aims: Our aim is to determine Li abundances in TO stars of the Globular
Cluster 47 Tuc and test theories about Li variations among TO stars. method: We
make use of high resolution (R~ 43000), high signal-to-noise ratio (S/N=50--70)
spectra of 4 turn off (TO) stars obtained with the UVES spectrograph at the
8.2m VLT Kueyen telescope. results: The four stars observed, span the range
1.6<~A(Li)} <~ 2.14, providing a mean A(Li) = 1.84 with a standard deviation of
0.25 dex. When coupled with data of other two TO stars of the cluster,
available in the literature, the full range in Li abundances observed in this
cluster is 1.6<~A(Li)<~ 2.3. The variation in A(Li) is at least 0.6 dex (0.7
dex considering also the data available in the literature) and the scatter is
six times larger than what expected from the observational error. We claim that
these variations are real. A(Li) seems to be anti-correlated with A(Na) exactly
as observed in NGC 6752. No systematic error in our analysis could produce such
an anti-correlation. conclusions: Na production through p captures on 22Ne at
temperatures in excess of 3x10^7 K and the contemporary Li destruction could
result in this anti-correlation. However such nuclear processing cannot have
taken place in the stars themselves, which do not reach such high temperatures,
even at their centre. This points towards the processing in a previous
generation of stars. The low N/O ratios in the observed stars and the apparent
lack of correlation between N an Li abundances, place a strong constraint on
the properties of this previous generation. Our results indicate a different
behaviour among the Globular Clusters so far studied as far as the abundance
patterns are concerned.


title:
A Luttinger Liquid Coupled to a Quantum Spin Bath: Flow Equation
  Approach to the Kondo Necklace Model

abstract:
  We study a lattice realization of a Luttinger liquid interacting with a bath
of quantum spins in terms of an antiferromagnetic S=1/2 Heisenberg chain, where
each spin is also coupled to a \sigma=1/2 Kondo spin degree of freedom. This
model describes the low-energy spin dynamics in quasi one dimensional
materials, where the electronic spins of the magnetic ions interact with those
of impurities, nuclei and possibly other spin species present in their
environment. For large ferromagnetic and antiferromagnetic Kondo interaction J'
there are two phases corresponding to an effective spin-1 Heisenberg chain and
a dimerised spin-1/2 ladder, respectively. For weak Kondo interaction we
establish that the Kondo interaction drives the system to a strong coupling
regime. This suggests that J'=0 is the only critical point in the system.


title: Parallel computing for the finite element method

abstract:
  A finite element method is presented to compute time harmonic microwave
fields in three dimensional configurations. Nodal-based finite elements have
been coupled with an absorbing boundary condition to solve open boundary
problems. This paper describes how the modeling of large devices has been made
possible using parallel computation, New algorithms are then proposed to
implement this formulation on a cluster of workstations (10 DEC ALPHA 300X) and
on a CRAY C98. Analysis of the computation efficiency is performed using simple
problems. The electromagnetic scattering of a plane wave by a perfect electric
conducting airplane is finally given as example.


title: On Predicting the Solar Cycle using Mean-Field Models

abstract:
  We discuss the difficulties of predicting the solar cycle using mean-field
models. Here we argue that these difficulties arise owing to the significant
modulation of the solar activity cycle, and that this modulation arises owing
to either stochastic or deterministic processes. We analyse the implications
for predictability in both of these situations by considering two separate
solar dynamo models. The first model represents a stochastically-perturbed flux
transport dynamo. Here even very weak stochastic perturbations can give rise to
significant modulation in the activity cycle. This modulation leads to a loss
of predictability. In the second model, we neglect stochastic effects and
assume that generation of magnetic field in the Sun can be described by a fully
deterministic nonlinear mean-field model -- this is a best case scenario for
prediction. We designate the output from this deterministic model (with
parameters chosen to produce chaotically modulated cycles) as a target
timeseries that subsequent deterministic mean-field models are required to
predict. Long-term prediction is impossible even if a model that is correct in
all details is utilised in the prediction. Furthermore, we show that even
short-term prediction is impossible if there is a small discrepancy in the
input parameters from the fiducial model. This is the case even if the
predicting model has been tuned to reproduce the output of previous cycles.
Given the inherent uncertainties in determining the transport coefficients and
nonlinear responses for mean-field models, we argue that this makes predicting
the solar cycle using the output from such models impossible.


title:
Transition on the entropic elasticity of DNA induced by intercalating
  molecules

abstract:
  We use optical tweezers to perform stretching experiments on DNA molecules
when interacting with the drugs daunomycin and ethidium bromide, which
intercalate the DNA molecule. These experiments are performed in the low-force
regime from zero up to 2 pN. Our results show that the persistence length of
the DNA-drug complexes increases strongly as the drug concentration increases
up to some critical value. Above this critical value, the persistence length
decreases abruptly and remains practically constant for larger drug
concentrations. The contour length of the molecules increases monotonically and
saturates as drugs concentration increases. Measured in- tercalants critical
concentrations for the persistence length transition coincide with reported
values for the helix-coil transition of DNA-drug complexes, obtained from
sedimentation experiments.


title:
Revival-collapse phenomenon in the quadrature squeezing of the
  multiphoton Jaynes-Cummings model with the binomial states

abstract:
  In this paper we study the interaction between two-level atom and quantized
single-mode field, namely, Jaynes-Cummings model (JCM). The field and the atom
are initially prepared in the binomial state and the excited atomic state,
respectively. For this system we prove that the revival-collapse phenomenon
exhibited in the atomic inversion of the standard JCM can be numerically
(naturally) manifested in the evolution of the squeezing factor of the
three-photon (standard) JCM provided that the initial photon-number
distribution of the radiation has a smooth envelope.


title: Bound Polaron in CuCl and GaAs Quantum Dots

abstract:
  We calculated the binding energy of a polaron bound to a hydrogenic donor
impurity located in a spherical quantum dot by means of a variational and
numerical technique for finite potential models. The polaronic effect has been
considered taking into account the ion-phonon coupling under the Lee Low Pines
approach. The results show that the binding energies are drastically affected
by the dot radius, the potential barrier height and the polaronic effects.


title: Quantum Master Equation for QED in Exact Renormalization Group

abstract:
  Recently, one of us (H.S.) gave an explicit form of the Ward-Takahashi
identity for the Wilson action of QED. We first rederive the identity using a
functional method. The identity makes it possible to realize the gauge symmetry
even in the presence of a momentum cutoff. In the cutoff dependent realization,
the abelian nature of the gauge symmetry is lost, breaking the nilpotency of
the BRS transformation. Using the Batalin-Vilkovisky formalism, we extend the
Wilson action by including the antifield contributions. Then, the
Ward-Takahashi identity for the Wilson action is lifted to a quantum master
equation, and the modified BRS transformation regains nilpotency. We also
obtain a flow equation for the extended Wilson action.


title: The time evolution of cosmological redshift as a test of dark energy

abstract:
  The variation of the expansion rate of the Universe with time produces an
evolution in the cosmological redshift of distant sources (for example quasar
Lyman-$\alpha$ absorption lines), that might be directly observed by future
ultra stable, high-resolution spectrographs (such as CODEX) coupled to
extremely large telescopes (such as European Southern Observatory's Extremely
Large Telescope, ELT). This would open a new window to explore the physical
mechanism responsible for the current acceleration of the Universe. We
investigate the evolution of cosmological redshift from a variety of dark
energy models, and compare it with simulated data. We perform a Fisher matrix
analysis and discuss the prospects for constraining the parameters of these
models and for discriminating among competing candidates. We find that, because
of parameter degeneracies, and of the inherent technical difficulties involved
in this kind of observations, the uncertainties on parameter reconstruction can
be rather large unless strong external priors are assumed. However, the method
could be a valuable complementary cosmological tool, and give important
insights on the dynamics of dark energy, not obtainable using other probes.


title:
Parallel computation of the rank of large sparse matrices from algebraic
  K-theory

abstract:
  This paper deals with the computation of the rank and of some integer Smith
forms of a series of sparse matrices arising in algebraic K-theory. The number
of non zero entries in the considered matrices ranges from 8 to 37 millions.
The largest rank computation took more than 35 days on 50 processors. We report
on the actual algorithms we used to build the matrices, their link to the
motivic cohomology and the linear algebra and parallelizations required to
perform such huge computations. In particular, these results are part of the
first computation of the cohomology of the linear group GL_7(Z).


title:
A 2D quantum antiferromagnet with a four-fold degenerate
  valence-bond-solid ground state

abstract:
  We study the competition between antiferromagnetic order and valence bond
solid formation in a two-dimensional frustrated spin-1/2 model. The J1-J2 model
on the square lattice is further frustrated by introducing products of
three-spin projectors which stabilize four dimer-product states as degenerate
ground states. These four states are reminiscent of the dimerized singlet
ground state of the Shastry-Sutherland model. Using exact diagonalizations, we
study the evolution of the ground state by varying theratio of interactions.
For a large range of parameters (J2 > 0.25J1), our model shows a direct
transition between the valence-bond-solid phase and the collinear
antiferromagnetic phase. For small values of J2, several intermediate phases
appear which are also analyzed.


title: Scaling Laws of Cognitive Networks

abstract:
  We consider a cognitive network consisting of n random pairs of cognitive
transmitters and receivers communicating simultaneously in the presence of
multiple primary users. Of interest is how the maximum throughput achieved by
the cognitive users scales with n. Furthermore, how far these users must be
from a primary user to guarantee a given primary outage. Two scenarios are
considered for the network scaling law: (i) when each cognitive transmitter
uses constant power to communicate with a cognitive receiver at a bounded
distance away, and (ii) when each cognitive transmitter scales its power
according to the distance to a considered primary user, allowing the cognitive
transmitter-receiver distances to grow. Using single-hop transmission, suitable
for cognitive devices of opportunistic nature, we show that, in both scenarios,
with path loss larger than 2, the cognitive network throughput scales linearly
with the number of cognitive users. We then explore the radius of a primary
exclusive region void of cognitive transmitters. We obtain bounds on this
radius for a given primary outage constraint. These bounds can help in the
design of a primary network with exclusive regions, outside of which cognitive
users may transmit freely. Our results show that opportunistic secondary
spectrum access using single-hop transmission is promising.


title: A study of the size of snow particles in powder snow avalanches

abstract:
  In this work, we study the size of the particles involved in a powder snow
avalanche phenomenon. To determine these sizes, we study all the phenomena the
particles have to face before arriving in the "body" of the avalanche. We study
the boundary layer which is at the bottom of the avalanche. We determine, with
the help of experimental data, the range of size of the particles that can be
entrained by the avalanche. We then examine the possibility for these particles
to reach the top of the boundary layer, and so to take part in the avalanche.
Our final result is that the more frequent particles suspended in a powder snow
avalanche have a size lower than 200 micrometers.


title: A Nice Labelling for Tree-Like Event Structures of Degree 3

abstract:
  We address the problem of ﬁnding nice labellings for event structures
of degree 3. We develop a minimum theory by which we prove that the labelling
number of an event structure of degree 3 is bounded by a linear function of the
height. The main theorem we present in this paper states that event structures
of degree 3 whose causality order is a tree have a nice labelling with 3
colors. Finally, we exemplify how to use this theorem to construct upper bounds
for the labelling number of other event structures of degree 3.


title: Experimental Results and Analytical Predictions of EHL Film Thickness

abstract:
  In this work, we consider several types of lubricants - including
non-Newtonian fluids - that were studied under various operating conditions
leading us to explore a wide range of dimensionless parameters. The
experimental results are compared with predictions given by the usual
analytical EHL relationships and by more recently developed models. This broad
comparison conducted with particular emphasis on minimum film thickness (hm)
showed a fair agreement between experimental data and a few predictions
including some obtained from extended models. Commonly used elasto-hydrodynamic
lubrication (EHL) models did not systematically gave accurate hm estimation,
whereas minimum film thickness not only is a yield value but also serves as a
key parameter in estimating lubrication regimes.


title: A new class of rank one transformations with singular spectrum

abstract:
  We introduce a new tool to study the spectral type of rank one
transformations using the method of central limit theorem for trigonometric
sums. We get some new applications.


title:
Density of states and supercurrent in diffusive SNS junctions: role of
  nonideal interfaces and spin-flip scattering

abstract:
  We present a theoretical study of the density of states and supercurrent in
diffusive superconductor-normal metal-superconductor (SNS) junctions. In
particular, we study the influence on these two equilibrium properties of both
an arbitrary transparency of the SN interfaces and the presence of spin-flip
scattering in the normal wire. We show that the minigap that is present in the
spectrum of the diffusive wire is very sensitive to the interface transmission.
More mportantly, we show that at arbitrary transparency the minigap replaces
the Thouless energy as the relevant energy scale for the proximity effect,
determining for instance the temperature dependence of the critical current. We
also study in detail how the critical current is suppressed by the effect of
spin-flip scattering, which can be due to either magnetic impurities or, under
certain circumstances, to an external magnetic field. Our analysis based on the
quasiclassical theory of diffusive superconductors can be very valuable to
establish quantitative comparisons between experiment and theory.


title:
Navier-Stokes equations with periodic boundary conditions and pressure
  loss

abstract:
  We present in this note the existence and uniqueness results for the Stokes
and Navier-Stokes equations which model the laminar flow of an incompressible
fluid inside a two-dimensional channel of periodic sections. The data of the
pressure loss coefficient enables us to establish a relation on the pressure
and to thus formulate an equivalent problem.


title:
Reproductive strong solutions of Navier-Stokes equations with non
  homogeneous boundary conditions

abstract:
  The object of the present paper is to show the existence and the uniqueness
of a reproductive strong solution of the Navier-Stokes equations, i.e. the
solution $\boldsymbol{u} $ belongs to $\text{}\mathbf{L}% ^{\infty}(0,T;V) \cap
\mathbf{L}^{2}(0,T;\mathbf{H}% ^{2}(\Omega))$ and satisfies the property
$\boldsymbol{u}% (\boldsymbol{x,}T) =\boldsymbol{u}% (\boldsymbol{x,}0)
=\boldsymbol{u}_{0}(\boldsymbol{x})$. One considers the case of an
incompressible fluid in two dimensions with nonhomogeneous boundary conditions,
and external forces are neglected.


title: Solutions fortes de l'\'equation de l'\'energie

abstract:
  In this paper, we give some existence results of stong solutions for the
energy equation associated to the Navier-Stokes equations with nonhomogeneous
boundary conditions in two dimension.


title: On Brownian flights

abstract:
  Let K be a compact subset of ${\mathbb R}^n$. We choose at random with
uniform law a point at distance $\epsilon$ of K and start a Brownian motion
(BM) from this point. We study the probability that this BM hits K for the
first time at a distance $\geq r$ from the starting point.


title: Energy solutions for polymer aqueous solutions in two dimension

abstract:
  The aim of this article is to study a nonlinear system modeling a
Non-Newtonian fluid of polymer aqueous solutions. We are interested here in the
existence of weak solutions for the stationary problem in a bounded plane
domain or in two-dimensional exterior domain. Due to the third order of
derivatives in the non-linear term, it's difficult to obtain solution
satisfying energy inequality. But with a good choice of boundary conditions, an
adapt special basis and the use of the good properties of the trilinear form
associated to the non-linear term, we obtain energy solutions. The problem in
bounded domain is treated and the more difficult problem on non bounded domain
too.


title:
Yield design formulation for porous media subjected to flow, using
  approximate pressure field. Calcul \`a la rupture en pr\'esence d'un
  \'ecoulement : formulation cin\'ematique avec un champ de pression approch\'e

abstract:
  Yield design formulation for porous media subjected to flow, using
approximate pressure field. We attempt here to use the kinematic method of
yield design in the case of a porous medium subjected to flow (with or without
free surface), without looking for the exact solution of the pressure field.
The method proposed here is based on the use of approximate pressure fields. In
this paper, we show how, under different conditions concerning the yield
criterion and the velocity field, the use of such approximate fields allows to
obtain a necessary condition for stability without having to find the real
pressure field. Nous cherchons ici \`a utiliser la m\'ethode cin\'ematique du
calcul \`a la rupture dans le cas d'un milieu poreux soumis \`a un \'ecoulement
avec ou sans surface libre sans conna\^itre la solution exacte du champ de
pression. La m\'ethode propos\'ee ici repose sur l'utilisation de champs de
pression approch\'es par d\'efaut. Nous montrerons comment sous certaines
conditions portant sur le crit\`ere de r\'esistance et sur le champ de vitesse
utilis\'e, l'utilisation de tels champs de pression approch\'es permet
d'obtenir une condition n\'ecessaire de stabilit\'e sans avoir \`a d\'eterminer
exactement l'\'ecoulement.


title: Neutron Beta Decay: Status and Future of the Asymmetry Measurement

abstract:
  With more intense sources of cold and ultracold neutrons becoming available
and with improved experimental techniques being developed, determination of
|Vud| from neutron beta decay with a similar precision to that from from
superallowed beta decays is within reach. Determination of |Vud| from neutron
beta decay, free from nuclear corrections, hold the most promise for a further
improvement of the determination of |Vud|. The current and future neutron beta
decay correlation experiments including the UCNA experiment at Los Alamos
National Laboratory are reviewed


title:
Analogy electromagnetism-acoustics: Validation and application to local
  impedance active control for sound absorption

abstract:
  An analogy between electromagnetism and acoustics is presented in 2D. The
propagation of sound in presence of absorbing material is modeled using an open
boundary microwave package. Validation is performed through analytical and
experimental results. Application to local impedance active control for free
field sound absorption is finally described.


title:
Coupled Painlev\'e VI systems in dimension four with affine Weyl group
  symmetry of type $D_6^{(1)}$, II

abstract:
  We give a reformulation of a six-parameter family of coupled Painlev\'e VI
systems with affine Weyl group symmetry of type $D_6^{(1)}$ from the viewpoint
of its symmetry and holomorphy properties.


title: Lightest scalar in the SU_L(2)*SU_R(2) linear \sigma model

abstract:
  We consider the lightest scalar meson in the frame of the $SU_L(2)\times
SU_R(2)$ linear $\sigma$ model, keeping in mind that this model could be the
low energy realization of the two-flavour QCD. We show that the $\sigma$ field
is described by its four-quark component at least in the $\sigma$ resonance
energy (virtuality) region and the $\sigma\to\gamma\gamma$ decay is the four
quark transition.
  We emphasize that residues of the $\sigma$ pole in the $\pi\pi\to\pi\pi$ and
$\gamma\gamma\to\pi\pi$ amplitudes do not give an idea about the $\sigma$ meson
nature, and the progress in studying the $\sigma$ meson production mechanisms
in different processes could essentially further us in understanding its
nature.


title: Geometric gradient-flow dynamics with singular solutions

abstract:
  The gradient-flow dynamics of an arbitrary geometric quantity is derived
using a generalization of Darcy's Law. We consider flows in both Lagrangian and
Eulerian formulations. The Lagrangian formulation includes a dissipative
modification of fluid mechanics. Eulerian equations for self-organization of
scalars, 1-forms and 2-forms are shown to reduce to nonlocal characteristic
equations. We identify singular solutions of these equations corresponding to
collapsed (clumped) states and discuss their evolution.


title:
Effect of flux-dependent Friedel oscillations upon the effective
  transmission of an interacting nano-system

abstract:
  We consider a nano-system connected to measurement probes via non interacting
leads. When the electrons interact inside the nano-system, the coefficient
|ts(E_F)|^2 describing its effective transmission at the Fermi energy E_F
ceases to be local. This effect of electron-electron interactions upon
|ts(E_F)|^2 is studied using a one dimensional model of spinless fermions and
the Hartree-Fock approximation. The non locality of |ts(E_F)|^2 is due to the
coupling between the Hartree and Fock corrections inside the nano-system and
the scatterers outside the nano-system via long range Friedel oscillations.
Using this phenomenon, one can vary |ts(E_F)|^2 by an Aharonov-Bohm flux
threading a ring which is attached to one lead at a distance Lc from the
nano-system. For small distances Lc, the variation of the quantum conductance
induced by this non local effect can exceed 0.1 (e^2/h).


title:
Molecular Dynamics Study of a Thermal Expansion Coefficient: Ti Bulk
  with an Elastic Minimum Image Method

abstract:
  Linear thermal expansion coefficient (TEC) and specific heat of Ti bulk is
investigated by means of molecular dynamics simulation. Elastic Minimum Image
Convention of periodic boundary conditions is introduced to allow the bulk to
adjust its size according to the new temporarily fixed temperature. The TEC and
the specific heat of Ti are compared to the available theoretical and
experimental data.


title: Asymptotics of the fast diffusion equation via entropy estimates

abstract:
  We consider non-negative solutions of the fast diffusion equation $u_t=\Delta
u^m$ with $m \in (0,1)$, in the Euclidean space R^d, d?3, and study the
asymptotic behavior of a natural class of solutions, in the limit corresponding
to $t\to\infty$ for $m\ge m_c=(d-2)/d$, or as t approaches the extinction time
when m < mc. For a class of initial data we prove that the solution converges
with a polynomial rate to a self-similar solution, for t large enough if $m\ge
m_c$, or close enough to the extinction time if m < mc. Such results are new in
the range $m\le m_c$ where previous approaches fail. In the range mc < m < 1 we
improve on known results.


title:
Mixing-demixing transition and collapse of a vortex state in a
  quasi-two-dimensional boson-fermion mixture

abstract:
  We investigate the mixing-demixing transition and the collapse in a
quasi-two-dimensional degenerate boson-fermion mixture (DBFM) with a bosonic
vortex. We solve numerically a quantum-hydrodynamic model based on a new
density functional which accurately takes into account the dimensional
crossover. It is demonstrated that with the increase of interspecies repulsion,
a mixed state of DBFM could turn into a demixed state. The system collapses for
interspecies attraction above a critical value which depends on the vortex
quantum number. For interspecies attraction just below this critical limit
there is almost complete mixing of boson and fermion components. Such mixed and
demixed states of a DBFM could be experimentally realized by varying an
external magnetic field near a boson-fermion Feshbach resonance, which will
result in a continuous variation of interspecies interaction.


title: Growing Directed Networks: Estimation and Hypothesis Testing

abstract:
  Based only on the information gathered in a snapshot of a directed network,
we present a formal way of checking if the proposed model is correct for the
empirical growing network under study. In particular, we show how to estimate
the attractiveness, and present an application of the model presented in
[arxiv:0704.1847] to the scientific publications network from the ISI dataset.


title:
Power control algorithms for CDMA networks based on large system
  analysis

abstract:
  Power control is a fundamental task accomplished in any wireless cellular
network; its aim is to set the transmit power of any mobile terminal, so that
each user is able to achieve its own target SINR. While conventional power
control algorithms require knowledge of a number of parameters of the signal of
interest and of the multiaccess interference, in this paper it is shown that in
a large CDMA system much of this information can be dispensed with, and
effective distributed power control algorithms may be implemented with very
little information on the user of interest. An uplink CDMA system subject to
flat fading is considered with a focus on the cases in which a linear MMSE
receiver and a non-linear MMSE serial interference cancellation receiver are
adopted; for the latter case new formulas are also given for the system SINR in
the large system asymptote. Experimental results show an excellent agreement
between the performance and the power profile of the proposed distributed
algorithms and that of conventional ones that require much greater prior
knowledge.


title: Catalan Traffic and Integrals on the Grassmannians of Lines

abstract:
  We prove that certain numbers occurring in a problem of paths enumeration,
studied by Niederhausen (Catlan Traffic at the Beach, The Electronic Journal of
Combinatorics, 9, (2002), 1--17), are top intersection numbers in the
cohomology ring of the grassmannians of the lines in the complex projective
(n+1)-space.


title: A note on Seshadri constants on general $K3$ surfaces

abstract:
  We prove a lower bound on the Seshadri constant $\epsilon (L)$ on a $K3$
surface $S$ with $\Pic S \simeq \ZZ[L]$. In particular, we obtain that
$\epsilon (L)=\alpha$ if $L^2=\alpha^2$ for an integer $\alpha$.


title: Extended centres of finitely generated prime algebras

abstract:
  Let $K$ be a field and let $A$ be a finitely generated prime $K$-algebra. We
generalize a result of Smith and Zhang, showing that if $A$ is not PI and does
not have a locally nilpotent ideal, then the extended centre of $A$ has
transcendence degree at most ${\rm GKdim}(A)-2$ over $K$. As a consequence, we
are able to show that if $A$ is a prime $K$-algebra of quadratic growth, then
either the extended centre is a finite extension of K or $A$ is PI. Finally, we
give an example of a finitely generated non-PI prime $K$-algebra of GK
dimension 2 with a locally nilpotent ideal such that the extended centre has
infinite transcendence degree over $K$.


title:
Fundamental-measure density functional for the fluid of aligned hard
  hexagons: New insights in fundamental measure theory

abstract:
  In this article we obtain a fundamental measure functional for the model of
aligned hard hexagons in the plane. Our aim is not just to provide a functional
for a new, admittedly academic, model, but to investigate the structure of
fundamental measure theory. A model of aligned hard hexagons has similarities
with the hard disk model. Both share "lost cases", i.e. admit configurations of
three particles in which there is pairwise overlap but not triple overlap.
These configurations are known to be problematic for fundamental measure
functionals, which are not able to capture their contribution correctly. This
failure lies in the inability of these functionals to yield a correct low
density limit of the third order direct correlation function. Here we derive
the functional by projecting aligned hard cubes on the plane x+y+z=0. The
correct dimensional crossover behavior of these functionals permits us to
follow this strategy. The functional of aligned hard cubes, however, does not
have lost cases, so neither had the resulting functional for aligned hard
hexagons. The latter exhibits, in fact, a peculiar structure as compared to the
one for hard disks. It depends on a uniparametric family of weighted densities
through a new term not appearing in the functional for hard disks. Apart from
studying the freezing of this system, we discuss the implications of the
functional structure for new developments of fundamental measure theory.


title: Local well-posedness of Musiela's SPDE with L\'evy noise

abstract:
  We determine sufficient conditions on the volatility coefficient of Musiela's
stochastic partial differential equation driven by an infinite dimensional
L{\'e}vy process so that it admits a unique local mild solution in spaces of
functions whose first derivative is square integrable with respect to a weight.


title: The prime spectrum of algebras of quadratic growth

abstract:
  We study prime algebras of quadratic growth. Our first result is that if $A$
is a prime monomial algebra of quadratic growth then $A$ has finitely many
prime ideals $P$ such that $A/P$ has GK dimension one. This shows that prime
monomial algebras of quadratic growth have bounded matrix images. We next show
that a prime graded algebra of quadratic growth has the property that the
intersection of the nonzero prime ideals $P$ such that $A/P$ has GK dimension 2
is non-empty, provided there is at least one such ideal. From this we conclude
that a prime monomial algebra of quadratic growth is either primitive or has
nonzero locally nilpotent Jacobson radical. Finally, we show that there exists
a prime monomial algebra $A$ of GK dimension two with unbounded matrix images
and thus the quadratic growth hypothesis is necessary to conclude that there
are only finitely many prime ideals such that $A/P$ has GK dimension 1.


title: Hadron spectroscopy from canonical partition functions

abstract:
  A spectroscopic method for staggered fermions based on thermodynamical
considerations is proposed. The canonical partition functions corresponding to
the different quark number sectors are expressed in the low temperature limit
as polynomials of the eigenvalues of the reduced fermion matrix. Taking the
zero temperature limit yields the masses of the lowest states. The method is
successfully applied to the Goldstone pion and both dynamical and quenched
results are presented showing good agreement with that of standard
spectroscopy. Though in principle the method can be used to obtain the baryon
and dibaryon masses, due to their high computational costs such calculations
are practically unreachable.


title:
Power control and receiver design for energy efficiency in multipath
  CDMA channels with bandlimited waveforms

abstract:
  This paper is focused on the cross-layer design problem of joint multiuser
detection and power control for energy-efficiency optimization in a wireless
data network through a game-theoretic approach. Building on work of Meshkati,
et al., wherein the tools of game-theory are used in order to achieve
energy-efficiency in a simple synchronous code division multiple access system,
system asynchronism, the use of bandlimited chip-pulses, and the multipath
distortion induced by the wireless channel are explicitly incorporated into the
analysis. Several non-cooperative games are proposed wherein users may vary
their transmit power and their uplink receiver in order to maximize their
utility, which is defined here as the ratio of data throughput to transmit
power. In particular, the case in which a linear multiuser detector is adopted
at the receiver is considered first, and then, the more challenging case in
which non-linear decision feedback multiuser detectors are employed is
considered. The proposed games are shown to admit a unique Nash equilibrium
point, while simulation results show the effectiveness of the proposed
solutions, as well as that the use of a decision-feedback multiuser receiver
brings remarkable performance improvements.


title: Fusion algebras with negative structure constants

abstract:
  We introduce fusion algebras with not necessarily positive structure
constants and without identity element. We prove that they are semisimple when
tensored with $\mathbb{C}$ and that their characters satisfy orthogonality
relations. Then we define the proper notion of subrings and factor rings for
such algebras. For certain algebras $R$ we prove the existence of a ring $R'$
with nonnegative structure constants such that $R$ is a factor ring of $R'$. We
give some examples of interesting factor rings of the representation ring of
the quantum double of a finite group. Then, we investigate the algebras
associated to Hadamard matrices. For an $n\times n$-matrix the corresponding
algebra is a factor ring of a subalgebra of
$\mathbb{Z}[{(\mathbb{Z}/2\mathbb{Z})}^{n-2}]$.


title: Lattice QCD study of a five-quark hadronic molecule

abstract:
  We compute the ground-state energies of a heavy-light K-Lambda like system as
a function of the relative distance r of the hadrons. The heavy quarks, one in
each hadron, are treated as static. Then, the energies give rise to an
adiabatic potential Va(r) which we use to study the structure of the five-quark
system. The simulation is based on an anisotropic and asymmetric lattice with
Wilson fermions. Energies are extracted from spectral density functions
obtained with the maximum entropy method. Our results are meant to give
qualitative insight: Using the resulting adiabatic potential in a Schroedinger
equation produces bound state wave functions which indicate that the ground
state of the five-quark system resembles a hadronic molecule, whereas the first
excited state, having a very small rms radius, is probably better described as
a five-quark cluster, or a pentaquark. We hypothesize that an all light-quark
pentaquark may not exist, but in the heavy-quark sector it might, albeit only
as an excited state.


title: Bounded Pushdown dimension vs Lempel Ziv information density

abstract:
  In this paper we introduce a variant of pushdown dimension called bounded
pushdown (BPD) dimension, that measures the density of information contained in
a sequence, relative to a BPD automata, i.e. a finite state machine equipped
with an extra infinite memory stack, with the additional requirement that every
input symbol only allows a bounded number of stack movements. BPD automata are
a natural real-time restriction of pushdown automata. We show that BPD
dimension is a robust notion by giving an equivalent characterization of BPD
dimension in terms of BPD compressors. We then study the relationships between
BPD compression, and the standard Lempel-Ziv (LZ) compression algorithm, and
show that in contrast to the finite-state compressor case, LZ is not universal
for bounded pushdown compressors in a strong sense: we construct a sequence
that LZ fails to compress signicantly, but that is compressed by at least a
factor 2 by a BPD compressor. As a corollary we obtain a strong separation
between finite-state and BPD dimension.


title:
Constraints on supernova progenitors from spatial correlations with
  H-alpha emission

abstract:
  We have attempted to constrain the progenitors of all supernova types,
through correlations of the positions of historical supernovae with recent star
formation, as traced by H-alpha emission. Through pixel statistics we have
found that a large fraction of the SNII population do not show any association
with current star formation, which we put down to a 'runaway' fraction of these
progenitors. The SNIb/c population accurately traces the H-alpha emission, with
some suggestion that the SNIc progenitors show a higher degree of correlation
than the SNIb, suggesting higher mass progenitors for the former. Overall the
SNIa population only show a weak correlation to the positions of HII regions,
but as many as a half may be associated with a young stellar population.


title: L'indice de Maslov dans les $JB^*$-triples

abstract:
  We construct a homotopy invariant index for pathes in the set of invertible
tripotents in a JB*-triple that satisfy a Fredholm type condition with respect
to a fixed invertible tripotent. That index generalizes the Maslov index in the
Fredholm-Lagrangian of a symplectic Hilbert space.


title: Semiclassical Quantization of the Giant Magnon

abstract:
  Solitons in field theory provide a window into regimes not directly
accessible by the fundamental perturbative degrees of freedom. Motivated by
interest in the worldsheet S-matrix of string theory in AdS_5 x S^5 in the
limit of infinite worldsheet volume we consider the semiclassical quantization
of a particular soliton of this theory: the Hofman-Maldacena `giant magnon'
spinning string. We obtain explicit formulas for the complete spectrum of
bosonic and fermionic fluctuations around the giant magnon. As an application
of these results we confirm that the one-loop correction to the classical
energy vanishes as expected.


title:
Neglecting the porosity of hot-star winds can lead to underestimating
  mass-loss rates

abstract:
  Context: The mass-loss rate is a key parameter of massive stars. Adequate
stellar atmosphere models are required for spectral analyses and mass-loss
determinations. Present models can only account for the inhomogeneity of
stellar winds in the approximation of small-scale structures that are optically
thin. This treatment of ``microclumping'' has led to reducing empirical
mass-loss rates by factors of two and more. Aims: Stellar wind clumps can be
optically thick in spectral lines. We investigate how this ``macroclumping''
impacts on empirical mass-loss rates. Methods: The Potsdam Wolf-Rayet (PoWR)
model atmosphere code is generalized in the ``formal integral'' to account for
clumps that are not necessarily optically thin. Results: Optically thick clumps
reduce the effective opacity. This has a pronounced effect on the emergent
spectrum. Our modeling for the O-type supergiant zeta Puppis reveals that the
optically thin H-alpha line is not affected by wind porosity, but that the PV
resonance doublet becomes significantly weaker when macroclumping is taken into
account. The reported discrepancies between resonance-line and
recombination-line diagnostics can be resolved entirely with the macroclumping
modeling without downward revision of the mass-loss rate. Conclusions:
Mass-loss rates inferred from optically thin emission, such as the H-alpha line
in O stars, are not influenced by macroclumping. The strength of optically
thick lines, however, is reduced because of the porosity effects. Therefore,
neglecting the porosity in stellar wind modeling can lead to underestimating
empirical mass-loss rates.


title:
Ordinary differential systems in dimension three with affine Weyl group
  symmetry of types $D_4^{(1)},B_3^{(1)},G_2^{(1)},D_3^{(2)}$ and $A_2^{(2)}$

abstract:
  We present a four-parameter family of ordinary differential systems in
dimension three with affine Weyl group symmetry of type $D_4^{(1)}$. By
obtaining its first integral, we can reduce this system to the second-order
non-linear ordinary differential equations of Painlev\'e type. We also study
this system restricted its parameters. Each system can be obtained by
connecting some invariant divisors in the system of type $D_4^{(1)}$. Each
system admits affine Weyl group symmetry of types
$B_3^{(1)},G_2^{(1)},D_3^{(2)}$ and $A_2^{(2)}$, respectively. These
symmetries, holomorphy conditions and invariant divisors are new.


title: Shear zones in granular media: 3D Contact Dynamics simulation

abstract:
  Shear zone formation is investigated in slow 3D shear flows. We simulate the
linear version of the split-bottom shear cell. It is shown that the same type
of wide shear zones is achieved in the presence as well as in the absence of
gravity. We investigate the relaxation of the material towards a stationary
flow and analyze the stress and the velocity fields. We provide the functional
form of the widening of the shear zone inside the bulk. We discuss the growth
of the region where the material is in critical state. It is found that the
growth of the critical zone is responsible for the initial transient of the
shear zone.


title:
Symmetry in the Painlev\'e systems and their extensions to
  four-dimensional systems

abstract:
  We give a new approach to the symmetries of the Painlev\'e equations
$P_{V},P_{IV},P_{III}$ and $P_{II}$, respectively. Moreover, we make natural
extensions to fourth-order analogues for each of the Painlev\'e equations
$P_{V}$ and $P_{III}$, respectively, which are natural in the sense that they
preserve the symmetries.


title: Muon Physics: A Pillar of the Standard Model

abstract:
  Since its discovery in the 1930s, the muon has played an important role in
our quest to understand the sub-atomic theory of matter. The muon was the first
second-generation standard-model particle to be discovered, and its decay has
provided information on the (Vector -Axial Vector) structure of the weak
interaction, the strength of the weak interaction, G_F, and the conservation of
lepton number (flavor) in muon decay. The muon's anomalous magnetic moment has
played an important role in restricting theories of physics beyond the standard
standard model, where at present there is a 3.4 standard-deviation difference
between the experiment and standard-model theory. Its capture on the atomic
nucleus has provided valuable information on the modification of the weak
current by the strong interaction which is complementary to that obtained from
nuclear beta decay.


title: Multivariate Wavelet Frames

abstract:
  We proved that for any matrix dilation and for any positive integer $n$,
there exists a compactly supported tight wavelet frame with approximation order
$n$. Explicit methods for construction of dual and tight wavelet frames with a
given number of vanishing moments are suggested.


title: An English translation o Bertrand's theorem

abstract:
  A beautiful theorem due to J. L. F. Bertrand concerning the laws of
attraction that admit bounded closed orbits for arbitrarily chosen initial
conditions is translated from French into English.


title: The Quantum Configuration Space of Loop Quantum Cosmology

abstract:
  The article gives an account of several aspects of the space known as the
Bohr compactification of the line, featuring as the quantum configuration space
in loop quantum cosmology, as well as of the corresponding configuration space
realization of the so-called polymer representation. Analogies with loop
quantum gravity are explored, providing an introduction to (part of) the
mathematical structure of loop quantum gravity, in a technically simpler
context.


title: The Search for Primordial Black Holes Using Very Short Gamma Ray Bursts

abstract:
  We show the locations of the SWIFT short hard bursts (SHB) with afterglows on
the galactic map and compare with the VSB BATSE events. As we have pointed out
before, there is an excess of events in the galactic map of BATSE VSB events.
We not that none of VSB SWIFT era events fall into this cluster. More SWIFT
events are needed to check this claim. We also report a new study with KONUS
data of the VSB sample with an average energy above 90 keV showing a clear
excess of events below 100 ms duration (T90) that have large mean energy
protons. We suggest that VSB themselves consist of two subclasses: a fraction
of events have peculiar distribution properties and have no detectable
counterparts, as might be expected for exotic sources such as primordial black
holes. We show how GLAST could add key new information to the study of VSB
bursts and could help test the black hole concept.


title: Large radius exciton in single-walled carbon nanotubes

abstract:
  The spectrum of large radius exciton in an individual semiconducting
single-walled carbon nanotube (SWCNT) is described within the framework of
elementary potential model, in which exciton is modeled as bound state of two
oppositely charged quasi-particles confined on the tube surface. Due to the
parity of the interaction potential the exciton states split into the odd and
even series. It is shown that for the bare and screened Coulomb electron-hole
(e-h) potentials the binding energy of even excitons in the ground state well
exceeds the energy gap. The factors preventing the collapse of single-electron
states in isolated semiconducting SWCNTs are discussed.


title: Two-Loop Fermionic Corrections to Massive Bhabha Scattering

abstract:
  We evaluate the two-loop corrections to Bhabha scattering from fermion loops
in the context of pure Quantum Electrodynamics. The differential cross section
is expressed by a small number of Master Integrals with exact dependence on the
fermion masses me, mf and the Mandelstam invariants s,t,u. We determine the
limit of fixed scattering angle and high energy, assuming the hierarchy of
scales me^2 << mf^2 << s,t,u. The numerical result is combined with the
available non-fermionic contributions. As a by-product, we provide an
independent check of the known electron-loop contributions.


title:
Suppressed dependence of polarization on epitaxial strain in highly
  polar ferroelectrics

abstract:
  A combined experimental and computational investigation of coupling between
polarization and epitaxial strain in highly polar ferroelectric
PbZr_0.2Ti_0.8O_3 (PZT) thin films is reported. A comparison of the properties
of relaxed (tetragonality c/a = 1.05) and highly-strained (c/a = 1.09)
epitaxial films shows that polarization, while being amongst the highest
reported for PZT or PbTiO_3 in either film or bulk forms (P_r = 82
microC/cm^2), is almost independent of the epitaxial strain. We attribute this
behavior to a suppressed sensitivity of the A-site cations to epitaxial strain
in these Pb-based perovskites, where the ferroelectric displacements are
already large, contrary to the case of less polar perovskites, such as BaTiO_3.
In the latter case, the A-site cation (Ba) and equatorial oxygen displacements
can lead to substantial polarization increases.


title:
Indices of the iterates of $R^3$-homeomorphisms at Lyapunov stable fixed
  points

abstract:
  Given any positive sequence (\{c_n\}_{n \in {\Bbb N}}), we construct
orientation preserving homeomorphisms (f:{\Bbb R}^3 \to {\Bbb R}^3) such that
(Fix(f)=Per(f)=\{0\}), (0) is Lyapunov stable and (\limsup \frac{|i(f^m,
0)|}{c_m}= \infty). We will use our results to discuss and to point out some
strong differences with respect to the computation and behavior of the
sequences of the indices of planar homeomorphisms.


title:
Existence of outermost apparent horizons with product of spheres
  topology

abstract:
  In this paper we find new examples of Riemannian manifolds with outermost
apparent horizons with nonspherical topology, in dimensions four and above.
More precisely, for any $n,m\ge1$, we construct asymptotically flat, scalar
flat Riemannian manifolds containing smooth outermost minimal hypersurfaces
with topology $S^n\times S^{m+1}$. In the context of general relativity these
hypersurfaces correspond to outermost apparent horizons of black holes.


title: BFKL at Next-to-Next-to-Leading Order

abstract:
  We determine an approximate expression for the O(alpha_s^3) contribution
chi_2 to the kernel of the BFKL equation, which includes all collinear and
anticollinear singular contributions. This is derived using recent results on
the relation between the GLAP and BFKL kernels (including running-coupling
effects to all orders) and on small-x factorization schemes. We present the
result in various schemes, relevant both for applications to the BFKL equation
and to small-x evolution of parton distributions.


title: Unimodular Relativity and the Dark Matter Problem

abstract:
  We introduce a modified divergence law for the energy-momentum tensor in the
theory of unimodular relativity. Consequently, an additional equation for the
measure field follows from the divergence of the field equations. The equations
of motion are derived and the weak-field, low-velocity limit is investigated.
It is found that the gravitational acceleration acquires a term that is
proportional to the gradient of the mass density. We show that this term can
provide the additional acceleration observed on astrophysical scales without
the need for dark matter.


title: Dynamics of the universe in the modified unimodular theory of gravity

abstract:
  The equations that govern the dynamics of the universe in the modified
unimodular theory of gravity are derived. We find a mechanism for inflation in
the early universe without postulating a false vacuum state during the first
$10^{-35}$ seconds after the Big Bang. In addition, we find a natural
explanation for the acceleration of the universe without resorting to dark
energy.


title: The Physical Nature of Polar Broad Absorption Line Quasars

abstract:
  It has been shown based on radio variability arguments that some BALQSOs
(broad absorption line quasars) are viewed along the polar axis (orthogonal to
accretion disk) in the recent article of Zhou et al. These arguments are based
on the brightness temperature, $T_{b}$ exceeding $10^{12} ^{\circ}$ K which
leads to the well-known inverse Compton catastrophe unless the radio jet is
relativistic and is viewed along its axis. In this letter, we expand the Zhou
et al sample of polar BALQSOs to the entire SDSS DR5. In the process, we
clarify a mistake in their calculation of brightness temperature. The expanded
sample of high $T_{b}$ BALQSOS, has an inordinately large fraction of LoBALQSOs
(low ionization BALQSOs). We consider this an important clue to understanding
the nature of the polar BALQSOs. This is expected in the polar BALQSO
analytical/numerical models of Punsly in which LoBALQSOs occur when the line of
sight is very close to the polar axis, where the outflow density is the
highest.


title:
Resolving the pulsations of subdwarf B stars: HS 0039+4302, HS
  0444+0458, and an examination of the group properties of resolved pulsators

abstract:
  We continue our program of single-site observations of pulsating subdwarf B
(sdB) stars and present the results of extensive time series photometry of HS
0039+4302 and HS 0444+0458. Both were observed at MDM Observatory during the
fall of 2005. We extend the number of known frequencies for HS 0039+4302 from 4
to 14 and discover one additional frequency for HS 0444+0458, bringing the
total to three. We perform standard tests to search for multiplet structure,
measure amplitude variations, and examine the frequency density to constrain
the mode degree $\ell$.
  Including the two stars in this paper, 23 pulsating sdB stars have received
follow-up observations designed to decipher their pulsation spectra. It is
worth an examination of what has been detected. We compare and contrast the
frequency content in terms of richness and range and the amplitudes with
regards to variability and diversity. We use this information to examine
observational correlations with the proposed $\kappa$ pulsation mechanism as
well as alternative theories.


title:
Multilevel Deconstruction of the In Vivo Behavior of Looped DNA-Protein
  Complexes

abstract:
  Protein-DNA complexes with loops play a fundamental role in a wide variety of
cellular processes, ranging from the regulation of DNA transcription to
telomere maintenance. As ubiquitous as they are, their precise in vivo
properties and their integration into the cellular function still remain
largely unexplored. Here, we present a multilevel approach that efficiently
connects in both directions molecular properties with cell physiology and use
it to characterize the molecular properties of the looped DNA-lac repressor
complex while functioning in vivo. The properties we uncover include the
presence of two representative conformations of the complex, the stabilization
of one conformation by DNA architectural proteins, and precise values of the
underlying twisting elastic constants and bending free energies. Incorporation
of all this molecular information into gene-regulation models reveals an
unprecedented versatility of looped DNA-protein complexes at shaping the
properties of gene expression.


title:
The Invariant Ring of Triples of 3x3 Matrices over a Field of Arbitrary
  Characteristic

abstract:
  Let R_{n,d} be the ring of invariants of d-tuples of n x n matrices under the
simultaneous conjugation action of the general linear group. A minimal
generating system and a homogeneous system of parameters for R_{3,3} are
determined. Homogeneous systems of parameters for R_{3,2}, R_{4,2} are also
pointed out.


title:
Indecomposable invariants of quivers for dimension (2,...,2) and maximal
  paths

abstract:
  An upper bound on degrees of elements of a minimal generating system for
invariants of quivers of dimension (2,...,2) is established over a field of
arbitrary characteristic and its precision is estimated. The proof is based on
the reduction to the problem of description of maximal paths satisfying certain
condition.


title: Giant viscosity enhancement in a spin-polarized Fermi liquid

abstract:
  The viscosity is measured for a Fermi liquid, a dilute $^3$He-$^4$He mixture,
under extremely high magnetic field/temperature conditions ($B \leq 14.8$ T, $T
\geq 1.5$ mK). The spin splitting energy $\mu B$ is substantially greater than
the Fermi energy $k_B T_F$; as a consequence the polarization tends to unity
and s-wave quasiparticle scattering is suppressed for $T \ll T_F$. Using a
novel composite vibrating-wire viscometer an enhancement of the viscosity is
observed by a factor of more than 500 over its low-field value. Good agreement
is found between the measured viscosity and theoretical predictions based upon
a $t$-matrix formalism.


title:
Radio Spectral Evolution of an X-ray Poor Impulsive Solar Flare:
  Implications for Plasma Heating and Electron Acceleration

abstract:
  We present radio and X-ray observations of an impulsive solar flare that was
moderately intense in microwaves, yet showed very meager EUV and X-ray
emission. The flare occurred on 2001 Oct 24 and was well-observed at radio
wavelengths by the Nobeyama Radioheliograph (NoRH), the Nobeyama Radio
Polarimeters (NoRP), and by the Owens Valley Solar Array (OVSA). It was also
observed in EUV and X-ray wavelength bands by the TRACE, GOES, and Yohkoh
satellites. We find that the impulsive onset of the radio emission is
progressively delayed with increasing frequency relative to the onset of hard
X-ray emission. In contrast, the time of flux density maximum is progressively
delayed with decreasing frequency. The decay phase is independent of radio
frequency. The simple source morphology and the excellent spectral coverage at
radio wavelengths allowed us to employ a nonlinear chi-squared minimization
scheme to fit the time series of radio spectra to a source model that accounts
for the observed radio emission in terms of gyrosynchrotron radiation from
MeV-energy electrons in a relatively dense thermal plasma. We discuss plasma
heating and electron acceleration in view of the parametric trends implied by
the model fitting. We suggest that stochastic acceleration likely plays a role
in accelerating the radio-emitting electrons.


title: Multi-qubit stabilizer and cluster entanglement witnesses

abstract:
  One of the problems concerning entanglement witnesses (EWs) is the
construction of them by a given set of operators. Here several multi-qubit EWs
called stabilizer EWs are constructed by using the stabilizer operators of some
given multi-qubit states such as GHZ, cluster and exceptional states. The
general approach to manipulate the multi-qubit stabilizer EWs by
exact(approximate) linear programming (LP) method is described and it is shown
that the Clifford group play a crucial role in finding the hyper-planes
encircling the feasible region. The optimality, decomposability and
non-decomposability of constructed stabilizer EWs are discussed.


title: Near-Infrared and X-ray Observations of the Enigmatic G70.7+1.2

abstract:
  We present high resolution imaging of the puzzling radio and optical nebula
G70.7+1.2 with the Keck Observatory's laser guide star adaptive optics (LGS-AO)
system and the Chandra X-ray Observatory. The archival X-ray observations show
a hard (Gamma ~ 1.8), low luminosity (L_X ~ 4 x 10^31 ergs/s) point source at
the center of the nebula. Follow-up LGS-AO near-infrared imaging of the Chandra
error circle reveals a relatively bright (K' ~ 14 magnitude) counterpart. Both
its color and brightness are consistent with a heavily obscured B-star or
possibly a late-G/early-K giant. The most plausible explanation is that this
newly discovered X-ray source is a non-accreting B-star/pulsar binary powering
the radio and optical nebula. If so, the luminous Be-star discussed in the
literature seemingly embedded in the nebula is not the dominant force
responsible for shaping G70.7+1.2. Thus, we suggest that G70.7+1.2 is the
result of two unrelated objects (a B-star X-ray binary and a Be star)
interacting with a dense molecular cloud. With this explanation we believe we
have solved the mystery of the origin of G70.7+1.2.


title: Fundamental Plane of Sunyaev-Zeldovich clusters

abstract:
  Sunyaev-Zel'dovich (SZ) cluster surveys are considered among the most
promising methods for probing dark energy up to large redshifts. However, their
premise is hinged upon an accurate mass-observable relationship, which could be
affected by the (rather poorly understood) physics of the intracluster gas. In
this letter, using a semi-analytic model of the intracluster gas that
accommodates various theoretical uncertainties, I develop a Fundamental Plane
relationship between the observed size, thermal energy, and mass of galaxy
clusters. In particular, I find that M ~ (Y_{SZ}/R_{SZ,2})^{3/4}, where M is
the mass, Y_{SZ} is the total SZ flux or thermal energy, and R_{SZ,2} is the SZ
half-light radius of the cluster. I first show that, within this model, using
the Fundamental Plane relationship reduces the (systematic+random) errors in
mass estimates to 14%, from 22% for a simple mass-flux relationship. Since
measurement of the cluster sizes is an inevitable part of observing the SZ
clusters, the Fundamental Plane relationship can be used to reduce the error of
the cluster mass estimates by ~ 34%, improving the accuracy of the resulting
cosmological constraints without any extra cost. I then argue why our
Fundamental Plane is distinctly different from the virial relationship that one
may naively expect between the cluster parameters. Finally, I argue that while
including more details of the observed SZ profile cannot significantly improve
the accuracy of mass estimates, a better understanding of the impact of
non-gravitational heating/cooling processes on the outskirts of the
intracluster medium (apart from external calibrations) might be the best way to
reduce these errors.


title: The Spectral Index Distribution of EGRET Blazars: Prospects for GLAST

abstract:
  The intrinsic distribution of spectral indices in GeV energies of
gamma-ray--loud blazars is a critical input in determining the spectral shape
of the unresolved blazar contribution to the diffuse extragalactic gamma-ray
background, as well as an important test of blazar emission theories. We
present a maximum-likelihood method of determining the intrinsic spectral index
distribution (ISID) of a population of gamma-ray emitters which accounts for
error in measurement of individual spectral indices, and we apply it to EGRET
blazars. We find that the most likely Gaussian ISID for EGRET blazars has a
mean of 2.27 and a standard deviation of 0.20. We additionally find some
indication that FSRQs and BL Lacs may have different ISIDs (with BL Lacs being
harder). We also test for spectral index hardening associated with blazar
variability for which we find no evidence. Finally, we produce simulated GLAST
spectral index datasets and perform the same analyses. With improved statistics
due to the much larger number of resolvable blazars, GLAST data will help us
determine the ISIDs with much improved accuracy. Should any difference exist
between the ISIDs of BL Lacs and FSRQs or between the ISIDs of blazars in the
quiescent and flaring states, GLAST data will be adequate to separate these
ISIDs at a significance better than 3 sigma.


title:
Adding Environmental Gas Physics to the Semi-Analytic Method for Galaxy
  Formation: Gravitational Heating

abstract:
  We present results of an attempt to include more detailed gas physics
motivated from hydrodynamical simulations within semi-analytic models (SAM) of
galaxy formation, focusing on the role that environmental effects play. The
main difference to previous SAMs is that we include 'gravitational' heating of
the intra-cluster medium (ICM) by the net surplus of gravitational potential
energy released from gas that has been stripped from infalling satellites.
Gravitational heating appears to be an efficient heating source able to prevent
cooling in environments corresponding to dark matter halos more massive than
$\sim 10^{13} $M$_{\odot}$. The energy release by gravitational heating can
match that by AGN-feedback in massive galaxies and can exceed it in the most
massive ones. However, there is a fundamental difference in the way the two
processes operate. Gravitational heating becomes important at late times, when
the peak activity of AGNs is already over, and it is very mass dependent. This
mass dependency and time behaviour gives the right trend to recover down-sizing
in the star-formation rate of massive galaxies. Abridged...


title:
Spatial distribution of local currents of massless Dirac fermions in
  quantum transport through graphene nanoribbons

abstract:
  We employ the formalism of bond currents, expressed in terms of the
nonequilibrium Green functions, to image the charge flow between two sites of
the honeycomb lattice of graphene ribbons of few nanometers width. In sharp
contrast to nonrelativistic electrons, current density profiles of quantum
transport at energies close to the Dirac point in clean zigzag graphene
nanoribbons (ZGNR) differs markedly from the profiles of charge density peaked
at the edges due to zero-energy localized edge states. For transport through
the lowest propagating mode induced by these edge states, edge vacancies do not
affect current density peaked in the center of ZGNR. The long-range potential
of a single impurity acts to reduce local current around it while concurrently
increasing the current density along the zigzag edge, so that ZGNR conductance
remains perfect $G=2e^2/h$.


title:
Searching for Earth analogues around the nearest stars: the disk
  age-metallicity relation and the age distribution in the Solar Neighbourhood

abstract:
  The chemical composition of Earth's atmosphere has undergone substantial
evolution over the course of its history. It is possible, even likely, that
terrestrial planets in other planetary systems have undergone similar changes;
consequently, the age distribution of nearby stars is an important
consideration in designing surveys for Earth-analogues. Valenti & Fischer
(2005) provide age and metallicity estimates for 1039 FGK dwarfs in the Solar
Neighbourhood. Using the Hipparcos catalogue as a reference to calibrate
potential biases, we have extracted volume-limited samples of nearby stars from
the Valenti-Fischer dataset. Unlike other recent investigations, our analysis
shows clear evidence for an age-metallicity relation in the local disk, albeit
with substantial dispersion at any epoch. The mean metallicity increases from
-0.3 dex at a lookback time of ~10 Gyrs to +0.15 dex at the present day.
Supplementing the Valenti-Fischer measurements with literature data to give a
complete volume-limited sample, the age distribution of nearby FGK dwarfs is
broadly consistent with a uniform star-formation rate over the history of the
Galactic disk. In striking contrast, most stars known to have planetary
companions are younger than 5 Gyrs; however, stars with planetary companions
within 0.4 AU have a significantly flatter age distribution, indicating that
those systems are stable on timescales of many Gyrs. Several of the older,
lower metallicity host stars have enhanced [alpha/Fe] ratios, implying
membership of the thick disk. If the frequency of terrestrial planets is also
correlated with stellar metallicity, then the median age of such planetary
system is likely to be ~3 Gyrs. We discuss the implications of this hypothesis
in designing searches for Earth analogues among the nearby stars.


title: Measuring the dark side (with weak lensing)

abstract:
  We introduce a convenient parametrization of dark energy models that is
general enough to include several modified gravity models and generalized forms
of dark energy. In particular we take into account the linear perturbation
growth factor, the anisotropic stress and the modified Poisson equation. We
discuss the sensitivity of large scale weak lensing surveys like the proposed
DUNE satellite to these parameters. We find that a large-scale weak-lensing
tomographic survey is able to easily distinguish the Dvali-Gabadadze-Porrati
model from LCDM and to determine the perturbation growth index to an absolute
error of 0.02-0.03.


title:
An Inner Hole in the Disk around TW Hydrae Resolved in 7 Millimeter Dust
  Emission

abstract:
  We present Very Large Array observations at 7 millimeters wavelength that
resolve the dust emission structure in the disk around the young star TW Hydrae
at the scale of the ~4 AU (~0.16") radius inner hole inferred from spectral
energy distribution modeling. These high resolution data confirm directly the
presence of an inner hole in the dust disk and reveal a high brightness ring
that we associate with the directly illuminated inner edge of the disk. The
clearing of the inner disk plausibly results from the dynamical effects of a
giant planet in formation. In an appendix, we develop an analytical framework
for the interpretation of visibility curves from power-law disk models with
inner holes.


title:
AMBRE - a Mathematica package for the construction of Mellin-Barnes
  representations for Feynman integrals

abstract:
  The Mathematica toolkit AMBRE derives Mellin-Barnes (MB) representations for
Feynman integrals in d=4-2eps dimensions. It may be applied for tadpoles as
well as for multi-leg multi-loop scalar and tensor integrals. AMBRE uses a
loop-by-loop approach and aims at lowest dimensions of the final MB
representations. The present version of AMBRE works fine for planar Feynman
diagrams. The output may be further processed by the package MB for the
determination of its singularity structure in eps. The AMBRE package contains
various sample applications for Feynman integrals with up to six external
particles and up to four loops.


title: Orbit-based deformation procedure for two-field models

abstract:
  We present a method for generating new deformed solutions starting from
systems of two real scalar fields for which defect solutions and orbits are
known. The procedure generalizes the approach introduced in a previous work
[Phys. Rev. D 66, 101701(R) (2002)], in which it is shown how to construct new
models altogether with its defect solutions, in terms of the original model and
solutions. As an illustration, we work out an explicit example in detail.


title: Trapping and Cooling a mirror to its quantum mechanical ground state

abstract:
  We propose a technique aimed at cooling a harmonically oscillating mirror to
its quantum mechanical ground state starting from room temperature. Our method,
which involves the two-sided irradiation of the vibrating mirror inside an
optical cavity, combines several advantages over the two-mirror arrangements
being used currently. For comparable parameters the three-mirror configuration
provides a stiffer trap for the oscillating mirror. Furthermore it prevents
bistability from limiting the use of higher laser powers for mirror trapping,
and also partially does so for mirror cooling. Lastly, it improves the
isolation of the mirror from classical noise so that its dynamics are perturbed
mostly by the vacuum fluctuations of the optical fields. These improvements are
expected to bring the task of achieving ground state occupation for the mirror
closer to completion.


title: Testing General Metric Theories of Gravity with Bursting Neutron Stars

abstract:
  I show that several observable properties of bursting neutron stars in metric
theories of gravity can be calculated using only conservation laws, Killing
symmetries, and the Einstein equivalence principle, without requiring the
validity of the general relativistic field equations. I calculate, in
particular, the gravitational redshift of a surface atomic line, the touchdown
luminosity of a radius-expansion burst, which is believed to be equal to the
Eddington critical luminosity, and the apparent surface area of a neutron star
as measured during the cooling tails of bursts. I show that, for a general
metric theory of gravity, the apparent surface area of a neutron star depends
on the coordinate radius of the stellar surface and on its gravitational
redshift in the exact same way as in general relativity. On the other hand, the
Eddington critical luminosity depends also on an additional parameter that
measures the degree to which the general relativistic field equations are
satisfied. These results can be used in conjunction with current and future
high-energy observations of bursting neutron stars to test general relativity
in the strong-field regime.


title:
Stationary and non-stationary fluid flow of a Bose-Einstein condensate
  through a penetrable barrier

abstract:
  We experimentally study the fluid flow induced by a broad, penetrable barrier
moving through an elongated dilute gaseous Bose-Einstein condensate. The
barrier is created by a laser beam swept through the condensate, and the
resulting dipole potential can be either attractive or repulsive. We examine
both cases and find regimes of stable and unstable fluid flow: At slow speeds
of the barrier, the fluid flow is stationary due to the superfluidity of the
condensate. At intermediate speeds, we observe a non-stationary regime in which
the condensate gets filled with dark solitons. At faster speeds, soliton
formation completely ceases and a remarkable absence of excitation in the
condensate is seen again.


title: Hopf algebras of dimension pq, II

abstract:
  Let H be a Hopf algebra of dimension pq over an algebraically closed field of
characteristic zero, where p, q are odd primes with p < q < 4p+12. We prove
that H is semisimple and thus isomorphic to a group algebra, or the dual of a
group algebra.


title: The Topological Theory of the Milnor Invariant $\bar{\mu}(1,2,3)$

abstract:
  We study a topological Abelian gauge theory that generalizes the Abelian
Chern-Simons one, and that leads in a natural way to the Milnor's link
invariant $\bar{\mu}(1,2,3)$ when the classical action on-shell is calculated.


title: The First Release COSMOS Optical and Near-IR Data and Catalog

abstract:
  We present imaging data and photometry for the COSMOS survey in 15
photometric bands between 0.3um and 2.4um. These include data taken on the
Subaru 8.3m telescope, the KPNO and CTIO 4m telescopes, and the CFHT 3.6m
telescope. Special techniques are used to ensure that the relative photometric
calibration is better than 1% across the field of view. The absolute
photometric accuracy from standard star measurements is found to be 6%. The
absolute calibration is corrected using galaxy spectra, providing colors
accurate to 2% or better. Stellar and galaxy colors and counts agree well with
the expected values. Finally, as the first step in the scientific analysis of
these data we construct panchromatic number counts which confirm that both the
geometry of the universe and the galaxy population are evolving.


title: Vortex trapping in suddenly connected Bose-Josephson junctions

abstract:
  We investigate the problem of vortex trapping in cyclically coupled
Bose-Josephson junctions. Starting with $N$ independent BECs we couple the
condensates through Josephson links and allow the system to reach a stable
circulation by adding a dissipative term in our semiclassical equations of
motion. The central question we address is what is the probability to trap a
vortex with winding number $m$. Our numerical simulations reveal that the final
distribution of winding numbers is narrower than the initial distribution of
total phases, indicating an increased probability for no-vortex configurations.
Further, the nonlinearity of the problem manifests itself in the somewhat
counter-intuitive result that it is possible to obtain a non-zero circulation
starting with zero total phase around the loop. The final width of the
distribution of winding numbers for $N$ sites scales as $\lambda N^{\alpha}$,
where $\alpha=0.47\pm 0.01$ and $\lambda <0.67$ (value predicted for the
initial distribution) indicating a shrinking of the final distribution. The
actual value of $\lambda$ is found to depend on the strength of dissipation.


title:
Thermodynamic properties of Bi2Sr2CaCu2O8 calculated from the electronic
  dispersion

abstract:
  The electronic dispersion for Bi2Sr2CaCu2O(8+d) has been determined from
angle-resolved photoelectron spectroscopy (ARPES). From this dispersion we
calculate the entropy and superfluid density. Even with no adjustable
parameters we obtain an exceptional match with experimental data across the
entire phase diagram, thus indirectly confirming both the ARPES and
thermodynamic data. The van Hove singularity is crossed in the overdoped region
giving a distinctive linear-in-T temperature dependence in the superfluid
density there.


title: A simple derivation of the Overlap Dirac Operator

abstract:
  We derive the vector-like four dimensional overlap Dirac operator starting
from a five dimensional Dirac action in the presence of a delta-function
space-time defect. The effective operator is obtained by first integrating out
all the fermionic modes in the fixed gauge background, and then identifying the
contribution from the localized modes as the determinant of an operator in one
dimension less. We define physically relevant degrees of freedom on the defect
by introducing an auxiliary defect-bound fermion field and integrating out the
original five dimensional bulk field.


title:
Induced inflation from a 5D purely kinetic scalar field formalism on
  warped product spaces

abstract:
  Considering a separable and purely kinetic 5D scalar field on a warped
product metric background we propose a new and more general approach for
inducing 4D scalar potentials on a 4D constant foliation of the 5D space-time.
We obtain an induced potential for a true 4D scalar field instead of a
potential for an effective 4D scalar field. In this formalism we can recover
the usual 4D inflationary formalism with a geometrically induced inflationary
potential. In addition the quantum confinement of the inflaton modes is
obtained naturally from the model for at least a class of warping factors.
Besides the 4D inflationary physics that results of this formalism is
independent of the 4D-hypersurface chosen.


title: Integrable Nonautonomous Nonlinear Schrodinger Equations

abstract:
  We show that a recently given nonautonomous nonlinear Schrodinger equation
(NLSE) can be transformed into the autonomous NLSE.


title: Observations and Modeling of Line Asymmetries in Chromospheric Flares

abstract:
  For many years various asymmetrical profiles of different spectral lines
emitted from solar flares have been frequently observed. These asymmetries or
line shifts are caused predominantly by vertical mass motions in flaring layers
and they provide a good diagnostics for plasma flows during solar flares. There
are many controversial results of observations and theoretical analysis of
plasma flows in solar chromospheric flares. The main difficulty is the
interpretation of line shifts or asymmetries. For many years, methods based on
bisector techniques were used but they give a reliable results only for some
specific conditions and in most cases cannot be applied. The most promising
approach is to use the non-LTE techniques applied for flaring atmosphere. The
calculation of synthetic line profiles is performed with the radiative transfer
techniques and the assumed physical conditions correspond to flaring
atmosphere. I will present an overview of different observations and
interpretations of line asymmetries in chromospheric flares. I will explain
what we have learnt about the chromospheric evaporation in the frame of
hydrodynamical models as well as reconnection models. A critical review will be
done on the classical methods used to derive Doppler-shifts for optically thick
chomospheric lines. In particular, details on the new approach for interpreting
chromospheric line asymmetries based on the non-LTE techniques will be
presented.


title: Multiple quantum wells for passive ultra short laser pulse generation

abstract:
  Solid state lasers are demanding independent control in the gain media and
cavity loss to achieve ultra short laser pulses using passive mode-locking.
Recently, laser mode-locking is achieved with a MBE structure with multiple
quantum wells, designed to achieve two functions; Bragg mirror and changes in
absorption to control the cavity dynamics. The use of an AlGaAs/AlAs Bragg
mirror with a 15 nm GaAs saturable absorber used in a Cr:LiSAF tuneable laser
proved to be effective to produce femtosecond pulses. The use of saturable
absorbers thus far is a trial and error procedure that is changing due to the
correlation with more predictive procedures.


title:
New $_5F_4$ hypergeometric transformations, three-variable Mahler
  measures, and formulas for $1/\pi$

abstract:
  New relations are established between families of three-variable Mahler
measures. Those identities are then expressed as transformations for the
$_5F_4$ hypergeometric function. We use these results to obtain two explicit
$_5F_4$ evaluations, and several new formulas for $1/\pi$.


title: Quantum phase transitions beyond the dilute Bose gas limit

abstract:
  We study a Heisenberg S=1/2 ring-exchange antiferromagnet which exhibits a
quantum phase transition from a spontaneously dimerized (valence bond solid)
phase to a magnetically ordered (Neel) phase. We argue that the quantum
transition is of unconventional nature; both singlet and triplet modes of high
density condense as the transition is approached from the dimer side, signaling
restoration of lattice symmetry. These features are consistent with "deconfined
quantum criticality", of which the present model is believed to be the only
example so far.


title: Black Holes and Large Order Quantum Geometry

abstract:
  We study five-dimensional black holes obtained by compactifying M theory on
Calabi-Yau threefolds. Recent progress in solving topological string theory on
compact, one-parameter models allows us to test numerically various conjectures
about these black holes. We give convincing evidence that a microscopic
description based on Gopakumar-Vafa invariants accounts correctly for their
macroscopic entropy, and we check that highly nontrivial cancellations -which
seem necessary to resolve the so-called entropy enigma in the OSV conjecture-
do in fact occur. We also study analytically small 5d black holes obtained by
wrapping M2 branes in the fiber of K3 fibrations. By using heterotic/type II
duality we obtain exact formulae for the microscopic degeneracies in various
geometries, and we compute their asymptotic expansion for large charges.


title:
Direct Observation of Polarization vs. Thickness Relation in Ultra-Thin
  Ferroelectric Films

abstract:
  A reduction of polarization in ultra-thin ferroelectric films appears to be
fundamental to ferroelectricity at the nanoscale. For the model system PbTiO3
on SrTiO3, we report observation of the polarization vs. thickness relation.
Distinct periodicity changes of ferroelectric domains obtained from x-ray
diffraction and total energy calculations reveal a linear lowering of the
polarization below a critical thickness of ~12 nm. Independent polarization and
tetragonality measurements provide insight into the fundamental relation
between polarization and tetragonality in nanoscale ferroelectrics.


title: Ferromagnetic resonance force microscopy on a thin permalloy film

abstract:
  Ferromagnetic Resonance Force Microscopy (FMRFM) offers a means of performing
local ferromagnetic resonance. We have studied the evolution of the FMRFM force
spectra in a continuous 50 nm thick permalloy film as a function of probe-film
distance and performed numerical simulations of the intensity of the FMRFM
probe-film interaction force, accounting for the presence of the localized
strongly nonuniform magnetic field of the FMRFM probe magnet. Excellent
agreement between the experimental data and the simulation results provides
insight into the mechanism of FMR mode excitation in an FMRFM experiment.


title:
Molecular dynamics studies on spatial scale of low energy excitation in
  a simple polymer system

abstract:
  A molecular dynamics simulation is performed to investigate spatial scale of
low energy excitation (LEE) in a single linear chain of united atoms. The self
part of the dynamic structure function, $S_\mathrm{S}(q,\omega)$, is obtained
in a wide range in frequency space ($\omega$) and reciprocal space ($q$). A
broad peak corresponding to the LEE is detected at $\omega/2\pi=2.5 \times
10^{11} \mathrm{s^{-1}}$ ($\equiv \omega_{\mathrm{LEE}}/2\pi$) on the contour
maps of $S_\mathrm{S}(q,\omega)$, near and below the glass transition
temperature ($T_{\mathrm{g}}$=230 K). The
$S_\mathrm{S}(q,\omega_{\mathrm{LEE}})$ is symmetric around a maximum along the
logarithm of $q$. The inverse of $q_{\mathrm{max}}$, giving the maximum
position of $S_\mathrm{S}(q,\omega_{\mathrm{LEE}})$, depends on temperature as
$2\pi/q_{\mathrm{max}}\sim T^{0.52}$ for $60 \mathrm{K}<T<T_{\mathrm{g}}$ and
$2\pi/q_{\mathrm{max}}\sim T^{0.97}$ for $T_{\mathrm{g}}<T<600 \mathrm{K}$,
which is the spatial scale of the motion corresponding to the LEE at low
temperatures. Based on a Gaussian approximation for the displacements of
monomer groups which give rise to the motion relevant to the LEE, it is found
that the number of monomers contained in a group is about 6.


title:
Contraints on radiative dark-matter decay from the cosmic microwave
  background

abstract:
  If dark matter decays to electromagnetically-interacting particles, it can
inject energy into the baryonic gas and thus affect the processes of
recombination and reionization. This leaves an imprint on the cosmic microwave
background (CMB): the large-scale polarization is enhanced, and the small-scale
temperature fluctuation is damped. We use the WMAP three-year data combined
with galaxy surveys to constrain radiatively decaying dark matter. Our new
limits to the dark-matter decay width are about ten times stronger than
previous limits. For dark-matter lifetimes that exceed the age of the Universe,
a limit of $\zeta \Gamma_{\chi} < 1.7 \times 10^{-25} s^{-1}$ (95% CL) is
derived, where $\zeta$ is the efficiency of converting decay energy into
ionization energy. Limits for lifetimes short compared with the age of the
Universe are also derived. We forecast improvements expected from the Planck
satellite.