title: Mechanism of Wall Turbulence in Boundary Layer Flow

abstract:
  The energy gradient method is used to analyze the turbulent generation in the
transition boundary layer flow. It is found that the maximum of the energy
gradient function occurs at the wall for the Blasius boundary layer flow. At
this location under a sufficiently high Reynolds number, even a low level of
free-stream disturbance can cause the turbulent transition and sustain the flow
to be in a state of turbulence. This is an excellent explanation of the physics
of self-sustenance of wall turbulence. The mechanism of receptivity for
boundary layer flow can also be understood from the energy gradient criterion.
That is, the free-stream disturbance can propagate towards the wall by the
"energy gradient" process to cause turbulent transition, and the transition
point in boundary layer can be moved forward towards the leading edge when the
level of external disturbance increases.


title:
Tuning the magnetic properties of half-metallic semi-Heusler alloys by
  sp-electron substitution: The case of AuMnSn$_{1-x}$Sb$_x$ quaternary alloys

abstract:
  We study the electronic and magnetic properties of the quaternary
AuMnSn$_{1-x}$Sb$_{x}$ Heusler alloys using first principles calculations. We
determine their magnetic phase diagram and we show that they present a phase
transition from a ferromagnetic to an antiferromagnetic state with increasing
Sb concentration. For large Sb concentrations the antiferromagnetic
superexchange coupling dominates over the ferromagnetic RKKY-like exchange
mechanism. This behavior is similar to the one demonstrated by the isovalent
Ni$_{1-x}$Cu$_x$MnSb alloy studied recently by the authors [I. Galanakis et al,
Phys. Rev. B. \textbf{77}, 214417 (2008)]. Thus the variation of the
concentration of the \textit{sp}-electrons (Sn and Sb atoms) and the variation
of the concentration of the non-magnetic \textit{3d} atoms (Cu) lead to a
similar tuning of the the magnetic properties of the Heusler alloys. We show
that the inclusion of correlation effects does not alter the phase diagram.
Calculated results are in good agreement with the available experimental data.


title:
Resonance Production in Heavy Ion Collisions: Suppression of
  $\Lambda(1520)$ and Enhancement of $\Sigma(1385)$

abstract:
  We investigate the yield of $\Lambda(1520)$ resonance in heavy ion collisions
within the framework of a kinetic master equation without the assumption of
chemical equilibrium. We show that reactions such as $\Lambda(1520)+\pi
\leftrightarrow \Sigma^*$ can favor $\Sigma^*$ production, thereby decreasing
the $\Lambda(1520)$ yield. Within the same approach we thus find a yield
enhancement for $\Sigma(1385)$ and a yield suppression for $\Lambda(1520)$.


title:
Conjectures about distinction and Asai $L$-functions of generic
  representations of general linear groups over local fields

abstract:
  Let $K/F$ be a quadratic extension of p-adic fields. The
Bernstein-Zelevinsky's classification asserts that generic representations are
parabolically induced from quasi-square-integrable representations. We show,
following a method developed by Cogdell and Piatetski-Shapiro, that the
equality of the Rankin-Selberg type Asai $L$-function of generic
representations of $GL(n,K)$ and of the Asai $L$-function of the Langlands
parameter, is equivalent to the truth of a conjecture about classification of
distinguished generic representations in terms of the inducing
quasi-square-integrable representations. As the conjecture is true for
principal series representations, this gives the expression of the Asai
L-function of such representations.


title:
Simulations of Fibre Orientation in Dilute Suspensions with Front Moving
  in the Filling Process of a Rectangular Channel Using Level Set Method

abstract:
  The simulation of fibre orientation in dilute suspension with a front moving
is carried out using the projection and level set methods. The motion of fibres
is described using the Jeffery equation and the contribution of fibres to the
flow is accounted for by the configuration field method. The governing
Navier-Stokes equation for the fluid flow is solved using the projection method
with finite difference scheme, while the fibre-related equations are directly
solved with the Runge-Kutta method. Our findings indicate that the fibre motion
has strong influence on the distributions of the streamwise and transverse
velocities in the fountain flow. Fibre motion produces strong normal stress
near the wall which leads to the reduction of transversal velocity as compared
to the Newtonian flow without fibres and in turn the streamwise velocity near
the wall is increased. Thus, the fibre addition to the flow weakens the
strength of the fountain flow. It is also found that the fibre orientation is
not always along the direction of velocity vector in the process of mold
filling. In the region of the fountain flow, the fibre near the centerline is
more oriented cross the streamwise direction comparing to that in the region
far behind the flow front. This leads to that the fibre near the centreline in
the region of fountain flow is more extended along the transverse direction.
Since fibre orientation in the suspension flow and the shape of the flow front
have great bearing on the quality of the product made from injection molding,
this study has much implications for engineering applications. These results
can also be useful in other field dealing with fibre suspensions.


title:
Higher order QCD corrections to charged-lepton deep-inelastic scattering
  and global fits of parton distributions

abstract:
  We study the perturbative QCD corrections to heavy-quark structure functions
of charged-lepton deep-inelastic scattering and their impact on global fits of
parton distributions. We include the logarithmically enhanced terms near
threshold due to soft gluon resummation in the QCD corrections at
next-to-next-to-leading order. We demonstrate that this approximation is
sufficient to describe the available HERA data in most parts of the kinematic
region. The threshold-enhanced next-to-next-to-leading order corrections
improve the agreement between predictions based on global fits of the parton
distribution functions and the HERA collider data even in the small-x region.


title:
Numerical Simulation of Fibre Suspension Flow through an Axisymmetric
  Contraction and Expansion Passages by Brownian Configuration Field Method

abstract:
  In this paper, the finite element method is combined with the Brownian
Configuration Field (BFC) method to simulate the fibre suspension flow in
axisymmetric contraction and expansion passages. In order to solve for the high
stress at high concentration, the Discrete Adaptive Viscoelastic Stress
Splitting (DAVSS) method is employed. For the axisymmetric contraction and
expansion passages with different geometry ratios, the results obtained are
compared to available constitutive models and experiments. The predicted vortex
length for dilute suspensions agrees well with experimental data in literature.
Our numerical results show clearly the effect on vortex enhancement with
increase of the volume fractions and the aspect ratios. Effect of aspect ratio
of fibres on the vortex length is also studied. It is found that for the lower
expansion ratio flows the vortex dimension in the corner region is fairly
independent of fibre concentration and aspect ratio of fibres while the said
vortex dimension increases with the increase of fibre concentration for
contraction flows. The finding suggests that the aligned fibre approximation
traditionally employed in previous work does not exactly describe the effect of
fibre motion, and the present BFC method is deemed more suitable for the flow
of dilute fibre suspensions. In terms of numerics, the employment of DAVSS
enhances numerical stability in the presence of high concentration of fibre in
the flow.


title:
Cluster-resolved dynamic scaling theory and universal corrections for
  transport on percolating systems

abstract:
  For percolating systems, we propose a universal exponent relation connecting
the leading corrections to scaling of the cluster size distribution with the
dynamic corrections to the asymptotic transport behaviour at criticality. Our
derivation is based on a cluster-resolved scaling theory unifying the scaling
of both the cluster size distribution and the dynamics of a random walker. We
corroborate our theoretical approach by extensive simulations for a site
percolating square lattice and numerically determine both the static and
dynamic correction exponents.


title: Alternative descriptions and bipartite compound quantum systems

abstract:
  We analyze some features of alternative Hermitian and quasi-Hermitian quantum
descriptions of simple and bipartite compound systems. We show that alternative
descriptions of two interacting subsystems are possible if and only if the
metric operator of the compound system can be obtained as tensor product of
positive operators on component spaces. Some examples also show that such
property could be strictly connected with symmetry properties of the
non-Hermitian Hamiltonian.


title: Spherical designs via Brouwer fixed point theorem

abstract:
  For each N>=c_d*n^{2d*(d+1)/(d+2)} we prove the existence of a spherical
n-design on S^d consisting of N points, where c_d is a constant depending only
on $d$.


title:
Abnormally large changes in anharmonicity of intramolecular vibrations
  in free clusters of nitrogen

abstract:
  Cathodoluminescence VUV spectra of free pure nitrogen clusters produced by
condensation of gas mixtures in supersonic jets expanding into vacuum were
studied. The clusters were of icosahedral structure, as evidenced by our
electron diffraction measurements, i.e., quasicrystals, and contained about
1000 atoms. The cluster temperature was about 40 K. The luminescence spectra
measured in the range of 45,000-75,000 cm^-1 clearly showed three vibronic w ->
X series of transitions from the excited 'w' to the ground 'X' state, which are
intrinsic to nitrogen molecules. All the transitions revealed a strong
dependence of the matrix shift of their peak positions on vibration quantum
number, while for bulk samples of N2 the matrix shift is known to remain
unchanged. Our analysis showed that in clusters the vibrational anharmonicity
parameter changes drastically for both the upper and lower states, while the
change in the vibrational frequencies is much less prominent. The results
obtained provide information about an abnormally strong influence of cluster
environment on the nonlinear contribution to the vibrations of nitrogen
molecules.


title: The Witten genus and vertex algebras

abstract:
  This article is the first report of an ongoing project aimed at finding a
geometric interpretation of the Witten genus and other tmf classes. Section 2
reviews the sheaves of chiral differential operators (CDOs) over a complex
manifold, including their construction, obstructions and relation with the
Witten genus. In section 3, the structure of each sheaf of CDOs is reorganized
in terms of modules over the sheaf of holomorphic functions. This invokes the
notion of a differential graded vertex algebroid. The construction of sheaves
of CDOs is due to Gorbounov, Malikov and Schechtman, and so is the notion of a
vertex algebroid; the differential graded version is first introduced here.
Section 4 contains the main result, namely the construction of a sheaf of
differential graded conformal vertex algebras that provides a fine resolution
of a sheaf of CDOs. This `infinite dimensional Dolbeault complex' plays a role
for the Witten genus similar to that of the Dolbeault complex for the Todd
genus.


title:
Global Well-posedness for the fourth order nonlinear Schr\"{o}dinger
  equations with small rough data in high demension

abstract:
  For $n\geq 2$, we establish the smooth effects for the solutions of the
linear fourth order Shr\"{o}dinger equation in anisotropic Lebesgue spaces with
$\Box_k$-decomposition. Using these estimates, we study the Cauchy problem for
the fourth order nonlinear Schr\"{o}dinger equations with three order
derivatives and obtain the global well posedness for this problem with small
data in modulation space $M^{9/2}_{2,1}({\Real^{n}})$.


title:
Multiple glass transitions in star polymer mixtures: Insights from
  theory and simulations

abstract:
  The glass transition in binary mixtures of star polymers is studied by mode
coupling theory and extensive molecular dynamics computer simulations. In
particular, we have explored vitrification in the parameter space of size
asymmetry $\delta$ and concentration $\rho_2$ of the small star polymers at
fixed concentration of the large ones. Depending on the choice of parameters,
three different glassy states are identified: a single glass of big polymers at
low $\delta$ and low $\rho_2$, a double glass at high $\delta$ and low
$\rho_2$, and a novel double glass at high $\rho_2$ and high $\delta$ which is
characterized by a strong localization of the small particles. At low $\delta$
and high $\rho_2$ there is a competition between vitrification and phase
separation. Centered in the $(\delta, \rho_2)$-plane, a liquid lake shows up
revealing reentrant glass formation. We compare the behavior of the dynamical
density correlators with the predictions of the theory and find remarkable
agreement between the two.


title:
Theoretical study of neutrino-induced coherent pion production off
  nuclei at T2K and MiniBooNE energies

abstract:
  We have developed a model for neutrino-induced coherent pion production off
nuclei in the energy regime of interest for present and forthcoming neutrino
oscillation experiments. It is based on a microscopic model for pion production
off the nucleon that, besides the dominant Delta pole contribution, takes into
account the effect of background terms required by chiral symmetry. Moreover,
the model uses a reduced nucleon-to-Delta resonance axial coupling, which leads
to coherent pion production cross sections around a factor two smaller than
most of the previous theoretical estimates. In the coherent production, the
main nuclear effects, namely medium corrections on the Delta propagator and the
final pion distortion, are included. We have improved on previous similar
models by taking into account the nucleon motion and employing a more
sophisticated optical potential. As found in previous calculations the
modification of the Delta self-energy inside the nuclear medium strongly
reduces the cross section, while the final pion distortion mainly shifts the
peak position to lower pion energies. The angular distribution profiles are not
much affected by nuclear effects. Nucleon motion increases the cross section by
15% at neutrino energies of 650 MeV, while Coulomb effects on charged pions are
estimated to be small. Finally, we discuss at length the deficiencies of the
Rein-Sehgal pion coherent production model for neutrino energies below 2 GeV,
and in particular for the MiniBooNE and T2K experiments. We also predict flux
averaged cross sections for these two latter experiments and K2K.


title:
Anderson transition on the Cayley tree as a traveling wave critical
  point for various probability distributions

abstract:
  For Anderson localization on the Cayley tree, we study the statistics of
various observables as a function of the disorder strength $W$ and the number
$N$ of generations. We first consider the Landauer transmission $T_N$. In the
localized phase, its logarithm follows the traveling wave form $\ln T_N \simeq
\bar{\ln T_N} + \ln t^*$ where (i) the disorder-averaged value moves linearly
$\bar{\ln (T_N)} \simeq - \frac{N}{\xi_{loc}}$ and the localization length
diverges as $\xi_{loc} \sim (W-W_c)^{-\nu_{loc}}$ with $\nu_{loc}=1$ (ii) the
variable $t^*$ is a fixed random variable with a power-law tail $P^*(t^*) \sim
1/(t^*)^{1+\beta(W)}$ for large $t^*$ with $0<\beta(W) \leq 1/2$, so that all
integer moments of $T_N$ are governed by rare events. In the delocalized phase,
the transmission $T_N$ remains a finite random variable as $N \to \infty$, and
we measure near criticality the essential singularity $\bar{\ln (T)} \sim - |
W_c-W |^{-\kappa_T}$ with $\kappa_T \sim 0.25$. We then consider the
statistical properties of normalized eigenstates, in particular the entropy and
the Inverse Participation Ratios (I.P.R.). In the localized phase, the typical
entropy diverges as $(W-W_c)^{- \nu_S}$ with $\nu_S \sim 1.5$, whereas it grows
linearly in $N$ in the delocalized phase. Finally for the I.P.R., we explain
how closely related variables propagate as traveling waves in the delocalized
phase. In conclusion, both the localized phase and the delocalized phase are
characterized by the traveling wave propagation of some probability
distributions, and the Anderson localization/delocalization transition then
corresponds to a traveling/non-traveling critical point. Moreover, our results
point towards the existence of several exponents $\nu$ at criticality.


title:
Relativistic quasiparticle time blocking approximation. II. Pygmy dipole
  resonance in neutron-rich nuclei

abstract:
  Theoretical studies of low-lying dipole strength in even-even spherical
nuclei within the relativistic quasiparticle time blocking approximation
(RQTBA) are presented. The RQTBA developed recently as an extension of the
self-consistent relativistic quasiparticle random phase approximation (RQRPA)
enables one to investigate effects of coupling of two-quasiparticle excitations
to collective vibrations within a fully consistent calculation scheme based on
covariant energy density functional theory. Dipole spectra of even-even
$^{130}$Sn -- $^{140}$Sn and $^{68}$Ni -- $^{78}$Ni isotopes calculated within
both RQRPA and RQTBA show two well separated collective structures: the
higher-lying giant dipole resonance (GDR) and the lower-lying pygmy dipole
resonance (PDR) which can be identified by a different behavior of the
transition densities of states in these regions.


title:
Low-dimensional NbO structures on the Nb(110) surface: scanning
  tunneling microscopy, electron spectroscopy and diffraction

abstract:
  X-ray photoelectron spectroscopy and diffraction (XPS, XPD) and scanning
tunneling microscopy (STM) have been used for study of NbOx-structures on the
Nb(110) surface. It is shown that niobium atoms are ordered to form a
two-dimensional superstructure with equidistant spacing between the chains of
niobium atoms. Chemical shifts of Nb3d- and O1s-levels demonstrate that the
oxide layer corresponds to niobium monoxide NbO and the most part of oxygen in
chemisorbed state is localized on the surface. A model of quasi-ordered
structure of NbO on the Nb(110) surface is proposed.


title:
The effect of stellar feedback on the formation and evolution of gas and
  dust tori in AGN

abstract:
  Recently, the existence of geometrically thick dust structures in Active
Galactic Nuclei (AGN) has been directly proven with the help of mid-infrared
interferometry. The observations are consistent with a two-component model made
up of a geometrically thin and warm central disk, surrounded by a colder,
fluffy torus component. In an exploratory study, we investigate one possible
physical mechanism, which could produce such a structure, namely the effect of
stellar feedback from a young nuclear star cluster on the interstellar medium
in centres of AGN. The model is realised with the help of the hydrodynamics
code TRAMP. We follow the evolution of the interstellar medium by taking
discrete mass loss and energy ejection due to stellar processes, as well as
optically thin radiative cooling into account. In a post-processing step, we
calculate observable quantities (spectral energy distributions and images) with
the help of the radiative transfer code MC3D. The interplay between injection
of mass, supernova explosions and radiative cooling leads to a two-component
structure made up of a cold geometrically thin, but optically thick and very
turbulent disk residing in the vicinity of the angular momentum barrier,
surrounded by a filamentary structure. The latter consists of cold long radial
filaments flowing towards the disk and a hot tenuous medium in between, which
shows both inwards and outwards directed motions. This modelling is able to
reproduce the range of observed neutral hydrogen column densities of a sample
of Seyfert galaxies as well as the relation between them and the strength of
the silicate 10 micron spectral feature. Despite being quite crude, our mean
Seyfert galaxy model is even able to describe the SEDs of two intermediate type
Seyfert galaxies observed with the Spitzer Space Telescope.


title: Simultaneous Determination of Signal and Background Asymmetries

abstract:
  This article discusses the determination of asymmetries. We consider a sample
of events consisting of a peak of signal events on top of some background
events. Both signal and background have an unknown asymmetry, e.g. a spin or
forward-backward asymmetry. A method is proposed which determines signal and
background asymmetries simultaneously using event weighting. For vanishing
asymmetries the statistical error of the asymmetries reaches the minimal
variance bound (MVB) given by the Cram\'er-Rao inequality and it is very close
to it for large asymmetries. The method thus provides a significant gain in
statistics compared to the classical method of side band subtraction of
background asymmetries. It has the advantage with respect to the unbinned
maximum likelihood approach, reaching the MVB as well, that it does not require
loops over the event sample in the minimization procedure.


title: Casimir Lifshitz pressure and free energy: exploring a simple model

abstract:
  The Casimir effect, the dispersion force attracting neutral objects to each
other, may be understood in terms of multiple scattering of light between the
interacting bodies. We explore the simple model in which the bodies are assumed
to possess reflection coefficients independent of the energy and angle of
incidence of an impinging field and show how a multitude of information can be
extracted within the geometry of two parallel plates. The full thermal
behaviour of the model is found and we discuss how non-analytic behaviour
emerges in the combined limits of zero temperature and perfect reflection.
Finally we discuss the possibility of a generalised force conjugate to the
reflection coefficients of the interacting materials and how, if the materials
involved were susceptible to changing their reflective properties, this would
tend to enhance the Casimir attraction. The dependence of this correction on
separation is studied for the constant reflection model, indicating that the
effect is likely to be negligible under most experimental circumstances.


title:
Modification of the Kolmogorov-Johnson-Mehl-Avrami rate equation for
  non-isothermal experiments and its analytical solution

abstract:
  Avrami's model describes the kinetics of phase transformation under the
assumption of spatially random nucleation. In this paper we provide a
quasi-exact analytical solution of Avrami's model when the transformation takes
place under continuous heating. This solution has been obtained with different
activation energies for both nucleation and growth rates. The relation obtained
is also a solution of the so-called Kolmogorov-Johnson-Mehl-Avrami
transformation rate equation. The corresponding non-isothermal
Kolmogorov-Johnson-Mehl-Avrami transformation rate equation only differs from
the one obtained under isothermal conditions by a constant parameter, which
only depends on the ratio between nucleation and growth rate activation
energies. Consequently, a minor correction allows us to extend the
Kolmogorov-Johnson-Mehl-Avrami transformation rate equation to continuous
heating conditions.


title:
Lepton Universality, |V_{us}| and search for second class current in tau
  decays

abstract:
  Several hundred million tau decays have been studied with the BaBar detector
at the PEP-II e+e- collider at the SLAC National Accelerator Laboratory. Recent
results on Charged Current Lepton Universality and two independent measurements
of |V_{us}| using tau- -> e- nubar nu, mu- nubar nu, pi- nu, K- nu and KS0 pi-
nu decays, and a search for Second Class Current in tau- -> pi- omega nu decays
are presented, where the charge conjugate decay modes are also implied.


title: Comment on "Torsion Cosmology and Accelerating Universe"

abstract:
  Cosmological solutions for homogeneous isotropic models in the framework of
the Poincar\'e gauge theory of gravity based on gravitational Lagrangian
adopted in the paper by Kun-Feng Shie, James M. Nester and Hwei-Jang Yo (Phys.
Rev. D \textbf{78}, 023522 (2008)) are discussed. Cosmological solutions for
accelerating Universe obtained in referred paper are compared with
corresponding solutions of standard $\Lambda CDM$-model and also with
cosmological solution obtained by authors of this Comment.


title:
Nobeyama Millimeter Array Observations of the Nuclear Starburst of M83:
  A GMA Scale Correlation between Dense Gas Fraction and Star Formation
  Efficiency

abstract:
  We present aperture synthesis high-resolution (~ 7" x 3") observations in
CO(J=1-0) line, HCN(J=1-0) line, and 95 GHz continuum emission toward the
central (~ 1.5 kpc) region of the nearby barred spiral galaxy M 83 with the
Nobeyama Millimeter Array. Our high-resolution CO(J=1-0) mosaic map depicts the
presence of molecular ridges along the leading sides of the stellar bar and
nuclear twin peak structure. On the other hand, we found the distribution of
the HCN(J=1-0) line emission which traces dense molecular gas (nH2 > a few x
10^4 cm^-3) shows nuclear single peak structure and coincides well with that of
the 95 GHz continuum emission which traces massive starburst. The peaks of the
HCN(J=1-0) line and the 95 GHz continuum emission are not spatially coincident
with the optical starburst regions traced by the HST V-band image. This
suggests the existence of deeply buried ongoing starburst due to strong
extinction (A_v ~ 5 mag) near the peaks of the HCN(J=1-0) line and the 95 GHz
continuum emission. We found that the HCN(J=1-0)/CO(J=1-0) intensity ratio
R_HCN/CO correlates well with extinction-corrected SFE in the central region of
M 83 at a resolution of 7.5" (~ 160 pc). This suggests that SFE is controlled
by dense gas fraction traced by R_HCN/CO even on a Giant Molecular cloud
Association (GMA) scale. Moreover, the correlation between R_HCN/CO and the SFE
in the central region of M 83 seems to be almost coincident with that of the
Gao & Solomon (2004a) sample. This suggests that the correlation between
R_HCN/CO and the SFE on a GMA (~ 160 pc) scale found in M 83 is the origin of
the global correlation on a few kpc scale shown by Gao & Solomon (2004a).


title:
Simple approximate analytical solution for non-isothermal single-step
  transformations: kinetic analysis

abstract:
  In this paper, we develop a method for obtaining the approximate solution for
the evolution of single-step transformations under non-isothermal conditions.
We have applied it to many reaction models and obtained very simple analytical
expressions for the shape of the corresponding transformation rate peaks. These
analytical solutions represent a significant simplification of the system's
description allowing easy curve fitting to experiment. A remarkable property is
that the evolutions of the transformed fraction obtained at different heating
rates are identical when time is scaled by a time constant. The accuracy
achieved with our method is checked against several reaction models and
different temperature dependencies of the transformation rate constant. It is
shown that its accuracy is closely related with that of the Kissinger method.


title: Model of a two--transverse mode laser with injected signal

abstract:
  We derive a simple model for a two transverse mode laser (that considers the
TEM00 and TEM10 modes) in which an injected signal with the shape of the TEM10
mode but a frequency close to that of the TEM00 mode is injected.


title: Radiative corrections to pion-nucleus bremsstrahlung

abstract:
  We calculate the one-photon loop radiative corrections to virtual pion
Compton scattering $\pi^- \gamma^* \to \pi^- \gamma$, that subprocess which
determines in the one-photon exchange approximation the pion-nucleus
bremsstrahlung reaction $\pi^- Z\to \pi^- Z \gamma$. Ultraviolet and infrared
divergencies of the loop integrals are both treated by dimensional
regularization. Analytical expressions for the ${\cal O}(\alpha)$ corrections
to the virtual Compton scattering amplitudes, $A(s,u,Q)$ and $B(s,u,Q)$, are
derived with their full dependence on the (small) photon virtuality $Q$ from 9
classes of contributing one-loop diagrams. Infrared finiteness of these virtual
radiative corrections is achieved (in the standard way) by including soft
photon radiation below an energy cut-off $\lambda$. In the region of low $\pi^-
\gamma$ center-of-mass energies, where the pion-nucleus bremsstrahlung process
is used to extract the pion electric and magnetic polarizabilities, we find
radiative corrections up to about -3% for $\lambda=5 $MeV. Furthermore, we
extend our calculation of the radiative corrections to virtual pion Compton
scattering $\pi^-\gamma^* \to \pi^- \gamma$ by including the leading pion
structure effect in form of the polarizability difference $\alpha_\pi -
\beta_\pi$. Our analytical results are particularly relevant for analyzing the
data of the COMPASS experiment at CERN which aims at measuring the pion
electric and magnetic polarizabilities with high statistics using the Primakoff
effect.


title:
Sharp Decay Estimates and Vanishing Viscosity for Diffusive
  Hamilton-Jacobi Equations

abstract:
  Sharp temporal decay estimates are established for the gradient and time
derivative of solutions to a viscous Hamilton-Jacobi equation as well the
associated Hamilton-Jacobi equation. Special care is given to the dependence of
the estimates on the viscosity. The initial condition being only continuous and
either bounded or non-negative. The main requirement on the Hamiltonians is
that it grows superlinearly or sublinearly at infinity, including in particular
H(r) = r^p for r non-negatif and p positif and different from 1.


title:
Seismology of beta Cephei stars: differentially-rotating models for
  interpreting the oscillation spectrum of nu-Eridani

abstract:
  A method for the asteroseismic analysis of beta Cephei stars is presented and
applied to the star nu Eridani. The method is based on the analysis of
rotational splittings, and their asymmetries using differentially-rotating
asteroseismic models. Models with masses around 7.13 M_sun, and ages around
14.9 Myr, were found to fit better 10 of the 14 observed frequencies, which
were identified as the fundamental radial mode and the three L=1 triplets g, p,
and p. The splittings and aymmetries found for these modes recover those
provided in the literature, except for p. For this last mode, all its
non-axysimmetric components are predicted by the models. Moreover, opposite
signs of the observed and predicted splitting asymmetries are found. If
identification is confirmed, this can be a very interesting source of
information about the internal rotation profile, in particular in the outer
regions of the star.
  In general, the seismic models which include a description for shellular
rotation yield slightly better results as compared with those given by
uniformly-rotating models. Furthermore, we show that asymmetries are quite
dependent on the overshooting of the convective core, which make the present
technique suitable for testing the theories describing the angular momentum
redistribution and chemical mixing due to rotationally-induced turbulence.


title:
The Globular Cluster Systems in the Coma Ellipticals. IV: WFPC2
  Photometry for Five Giant Ellipticals

abstract:
  We analyze photometric data in V and I for the globular cluster (GC) systems
in five of the giant ellipticals in the Coma Cluster: NGC 4874, 4881, 4889,
4926, and IC 4051. We find that the GC luminosity functions are quite similar
to one another, with a turnover derived from a composite sample of more than
9,000 GCs at V = 27.71 +- 0.07 (M_V = -7.3). Both a simple Gaussian curve and
an evolved Schechter function fit the bright half of the GCLF equally well,
though the Coma GCLF is broader and has a higher ``cutoff mass'' (M_c ~ 3 x
10^6 M_Sun) than in any of the Virgo giants. These five Coma members exhibit a
huge range in GC specific frequency, from a low of S_N = 0.7 for NGC 4881 up to
12 for IC 4051 and NGC 4874. No single formation scenario appears able to
account for these differences in otherwise-similar galaxies. The supergiant NGC
4874 has the richest globular cluster system known, probably holding more than
30,000 clusters; its true extent is not yet determined and may extend well out
into the Coma potential well. For the three biggest GC systems (NGC 4874, 4889,
IC 4051), all three populations are dominated by red, metal-rich clusters.
Their metallicity distributions also may all have the normal bimodal form, with
the two sequences at the expected mean colors <V-I>(blue) = 0.98 and <V-I>(red)
= 1.15. However, the color distributions and relative numbers of metal-rich
clusters show intriguing counterexamples to a trend established by Peng et al.
2008 (ApJ 681, 197) for the Virgo galaxies. At the very highest-density and
most massive regimes represented by the Coma supergiants, formation of
metal-rich clusters seems to have been especially favored.


title: Negative group velocity in layer-by-layer chiral photonic crystals

abstract:
  We study the group velocity of light in layer-by-layer chiral photonic
crystals composed of dielectrics and metals. Through studying the band
structures with an extended-zone scheme that is given by a Fourier analysis, we
show the existence of negative group velocity in the proposed chiral
structures. The physical mechanism is interpreted with the help of a simplified
model that has an analytical solution. The iso-frequency contours of the
photonic band structure suggest that the negative group velocity can lead to
either positive or negative refraction, depending on the orientation of the
medium interface. We propose a feasible realization of such kind of photonic
crystals. Computational results on the proposed realization are consistent with
that of the simplified models.


title:
Thermal Symmetry Crossover and Universal Behaviors in Carbon Nanotube
  Dots

abstract:
  Motivated by recent experiments on electronic transport through a carbon
nanotube, we investigate the role of the intra- and inter-orbital Coulomb
interactions on the temperature evolution of the conductance. It is shown that
small amount (~10%) of asymmetry between these Coulomb repulsions substantially
deforms the conductance profile at finite temperature, particularly around
half-filling. The nature of such thermal symmetry crossover is elucidated.


title: Neutrino mass generation in the SO(4) model

abstract:
  Generation of neutrino mass in SO(4) model is proposed here. The algebraic
structure of SO(4) is same as to that of $SU(2)_{L}\times SU(2)_{R}$. It is
shown that the spontaneous symmetry breaking results three massive as well as
three massless gauge bosons. The standard model theory according to which there
exist three massive gauge bosons and a massless one is emerged from this model.
In the framework of $SU(2)_{L}\times SU(2)_{R}$ a small Dirac neutrino mass is
derived. It is also shown that such mass term may vanish with a special choice.
The Majorana mass term is not considered here and thus in this model the
neutrino mass does not follow seesaw structure.


title: Neutralino annihilation to quarks with SUSY-QCD corrections

abstract:
  The calculation of the cosmological relic density of the dark matter
candidate within supersymmetric models is an interesting possibility to obtain
additional constraints on the supersymmetric parameter space with respect to
collider, electroweak precision, and low-energy data. Considering future
cosmological precision measurements, radiative corrections can play an
important role in the analysis. We present full QCD and SUSY-QCD corrections to
neutralino pair annihilation into quark-antiquark pairs and analyze their
impact on the neutralino annihilation cross section and the relic density. By
comparing to the relic density obtained from a pure leading order calculation,
we show that the corrections strongly influence the extraction of SUSY mass
parameters from cosmological data.


title: A stabilized pairing functional

abstract:
  We propose a modified pairing functional for nuclear structure calculations
which avoids the abrupt phase transition between pairing and non-pairing
states. The intended application is the description of nuclear collective
motion where the smoothing of the transition is compulsory to remove
singularities. The stabilized pairing functional allows a thoroughly
variational formulation, unlike the Lipkin-Nogami (LN) scheme which is often
used for the purpose of smoothing. First applications to nuclear ground states
and collective excitations prove the reliability and efficiency of the proposed
stabilized pairing.


title:
Reduction of the N=8 BLG and N=6 BL Theories to 2D Effective Field
  Theories

abstract:
  Starting from the three dimensional N=8 BLG and N=6 BL theories with CS level
k=1, a dimensional reduction is performed on the M2-branes worldvolume. The IR
limit of these 2D EFTs should represent the action of F1 strings in type IIA.
The CS term reduces to a particular Phi*F term and the scalars and fermions get
"mass" terms. The reduced actions still rely on three-algebra, which we did not
require to define precisely.


title: A new measurement of the cosmic X-ray background

abstract:
  We present a new measurement of the cosmic X-ray background (CXRB) in the
1.5-7 keV energy band, performed by exploiting the Swift X-ray telescope (XRT)
data archive. We also present a CXRB spectral model in a wider energy band
(1.5-200 keV), obtained by combining these data with the recently published
Swift-BAT measurement. From the XRT archive we collect a complete sample of 126
high Galactic latitude gamma-ray burst (GRB) follow-up observations. This
provides a total exposure of 7.5 Ms and a sky-coverage of 7 square degrees
which represents a serendipitous survey, well suited for a direct measurement
of the CXRB in the 1.5-10 keV interval. Our work is based on a complete
characterization of the instrumental background and an accurate measurement of
the stray-light contamination and vignetting calibration. We find that the CXRB
spectrum in the 1.5-7 keV energy band can be equally well fitted by a single
power-law with photon index Gamma=1.47+/-0.07 or a single power-law with photon
index Gamma=1.41+/-0.06 and an exponential roll-off at 41 keV. The measured
flux in the 2-10 keV energy band is 2.18+/-0.13 E-11 erg/(cm2 s deg2) in the
2-10 keV band. Combining Swift-XRT with Swift-BAT (15-200 keV) we find that, in
the 1.5-200 keV band, the CXRB spectrum can be well described by two
smoothly-joined power laws with the energy break at 29.0+/-0.5 keV
corresponding to a nu F_nu peak located at 22.4+/-0.4 keV. Taking advantage of
both the Swift high energy instruments (XRT and BAT), we produce an analytical
description of the CXRB spectrum over a wide (1.5-200 keV) energy band. This
model is marginally consistent with the HEAO1 measurement (~10% higher at
energies higher than 20 keV, while it is significantly (30%) higher at low
energies (2-10 keV).


title:
Self-similar factor approximants for evolution equations and
  boundary-value problems

abstract:
  The method of self-similar factor approximants is shown to be very convenient
for solving different evolution equations and boundary-value problems typical
of physical applications. The method is general and simple, being a
straightforward two-step procedure. First, the solution to an equation is
represented as an asymptotic series in powers of a variable. Second, the series
are summed by means of the self-similar factor approximants. The obtained
expressions provide highly accurate approximate solutions to the considered
equations. In some cases, it is even possible to reconstruct exact solutions
for the whole region of variables, starting from asymptotic series for small
variables. This can become possible even when the solution is a transcendental
function. The method is shown to be more simple and accurate than different
variants of perturbation theory with respect to small parameters, being
applicable even when these parameters are large. The generality and accuracy of
the method are illustrated by a number of evolution equations as well as
boundary value problems.


title: The Interaction Rate in Holographic Models of Dark Energy

abstract:
  Observational data from supernovae type Ia, baryon acoustic oscillations, gas
mass fraction in galaxy clusters, and the growth factor are used to reconstruct
the the interaction rate of the holographic dark energy model recently proposed
by Zimdahl and Pav\'{o}n [1] in the redshift interval $0 < z < 1.8$. It shows a
reasonable behavior as it increases with expansion from a small or vanishing
value in the far past and begins decreasing at recent times. This suggests that
the equation of state parameter of dark energy does not cross the phantom
divide line.


title: Static and dynamic properties of a reversible gel

abstract:
  We study a microscopically realistic model of a physical gel and use computer
simulations to investigate its static and dynamic properties at thermal
equilibrium. The phase diagram comprises a sol phase, a coexistence region
ending at a critical point, a gelation line, and an equilibrium gel phase
unrelated to phase separation. The global structure of the gel is homogeneous,
but the stress is supported by a fractal network. Gelation results in a
dramatic slowing down of the dynamics, which can be used to locate the
transition, which otherwise shows no structural signatures. Moreover, the
equilibrium gel dynamics is highly heterogeneous as a result of the presence of
particle families with different mobilities. An analysis of gel dynamics in
terms of mobile and arrested particles allows us to elucidate several
differences between the dynamics of equilibrium gels and that of glass-formers.


title: An embedding theorem for Hilbert categories

abstract:
  We axiomatically define (pre-)Hilbert categories. The axioms resemble those
for monoidal Abelian categories with the addition of an involutive functor. We
then prove embedding theorems: any locally small pre-Hilbert category whose
monoidal unit is a simple generator embeds (weakly) monoidally into the
category of pre-Hilbert spaces and adjointable maps, preserving adjoint
morphisms and all finite (co)limits. An intermediate result that is important
in its own right is that the scalars in such a category necessarily form an
involutive field. In case of a Hilbert category, the embedding extends to the
category of Hilbert spaces and continuous linear maps. The axioms for
(pre-)Hilbert categories are weaker than the axioms found in other approaches
to axiomatizing 2-Hilbert spaces. Neither enrichment nor a complex base field
is presupposed. A comparison to other approaches will be made in the
introduction.


title: Fibonacci Index and Stability Number of Graphs: a Polyhedral Study

abstract:
  The Fibonacci index of a graph is the number of its stable sets. This
parameter is widely studied and has applications in chemical graph theory. In
this paper, we establish tight upper bounds for the Fibonacci index in terms of
the stability number and the order of general graphs and connected graphs.
Tur\'an graphs frequently appear in extremal graph theory. We show that Tur\'an
graphs and a connected variant of them are also extremal for these particular
problems. We also make a polyhedral study by establishing all the optimal
linear inequalities for the stability number and the Fibonacci index, inside
the classes of general and connected graphs of order $n$.


title: The XMM-Newton Serendipitous Survey. VI. The X-ray Luminosity Function

abstract:
  We present the X-ray luminosity function of AGN in three energy bands (Soft:
0.5-2 keV, Hard: 2-10 keV and Ultrahard: 4.5-7.5 keV). We have used the XMS
survey along with other highly complete flux-limited deeper and shallower
surveys for a total of 1009, 435 and 119 sources in the Soft, Hard and
Ultrahard bands, respectively. We have modeled the intrinsic absorption of the
Hard and Ultrahard sources (NH function) and computed the intrinsic X-ray
luminosity function in all bands using a Maximum Likelihood fit technique to an
analytical model. We find that the X-ray luminosity function (XLF) is best
described by a Luminosity-Dependent Density Evolution (LDDE) model. Our results
show a good overall agreement with previous results in the Hard band, although
with slightly weaker evolution. Our model in the Soft band present slight
discrepancies with other works in this band, the shape of our present day XLF
being significantly flatter. We find faster evolution in the AGN detected in
the Ultrahard band than those in the Hard band. The fraction of absorbed AGN in
the Hard and Ultrahard bands is dependent on the X-ray luminosity. We find
evidence of evolution of this fraction with redshift in the Hard band but not
in the Ultrahard band, possibly due to the low statistics. Our best-fit XLF
shows that the high-luminosity AGN are fully formed earlier than the less
luminous AGN. The latter sources account for the vast majority of the accretion
rate and mass density of the Universe, according to an anti-hierarchical black
hole growth scenario.


title:
Nondegenerate parametric amplification in superlattice and the limits of
  strong and weak dissipation

abstract:
  We develop a semiclassical theory of the nondegenerate parametric
amplification in a single miniband of superlattice. We present the formulas
describing absorption and gain of signal and idler fields in superlattice and
analyze the limiting cases of strong and weak dissipation. We show how the
well-known Manley-Rowe relations arise in the tight-binding lattice in the weak
dissipation limit. Our results can be applied to an amplification of THz
signals in semiconductor superlattices and a control of nonlinear transport of
cold atoms in optical lattices.


title:
Primordial black hole formation in the radiative era: investigation of
  the critical nature of the collapse

abstract:
  Following on after two previous papers discussing the formation of primordial
black holes in the early universe, we present here results from an in-depth
investigation of the extent to which primordial black hole formation in the
radiative era can be considered as an example of the critical collapse
phenomenon. We focus on initial supra-horizon-scale perturbations of a type
which could have come from inflation, with only a growing component and no
decaying component. In order to study perturbations with amplitudes extremely
close to the supposed critical limit, we have modified our previous computer
code with the introduction of an adaptive mesh refinement scheme. This has
allowed us to follow black hole formation from perturbations whose amplitudes
are up to eight orders of magnitude closer to the threshold than we could do
before. We find that scaling-law behaviour continues down to the smallest black
hole masses that we are able to follow and we see no evidence of shock
production such as has been reported in some previous studies and which led
there to a breaking of the scaling-law behaviour at small black-hole masses. We
attribute this difference to the different initial conditions used. In addition
to the scaling law, we also present other features of the results which are
characteristic of critical collapse in this context.


title:
Bridging the size gap between density-functional and many-body
  perturbation theory

abstract:
  The calculation of quasi-particle spectra based on the GW approximation is
extended to systems of hundreds of atoms, thus expanding the size range of
current approaches by more than one order of magnitude. This is achieved
through an optimal strategy, based on the use of Wannier-like orbitals, for
evaluating the polarization propagator. Our method is validated by calculating
the vertical ionization energies of the benzene molecule and the band structure
of crystalline silicon. Its potentials are then demonstrated by addressing the
quasi-particle spectrum of a model structure of vitreous silica, as well as of
the tetraphenylporphyrin molecule.


title: Symmetry Energy for Nuclei Beyond the Stability Valley

abstract:
  We apply the direct variational method to derive the equation of state for
finite nuclei within the stability valley. The extended Thomas-Fermi
approximation for the energy functional with Skyrme forces is used. Using the
leptodermous expansion for the profile nucleon densities, we have studied the
neutron coat and the isospin symmetry energy for neutron-rich nuclei. Using
equation of state for the pressure, we derive the region of spinodal
instability of finite nuclei and its dependence on the mass number, the
asymmetry parameter and the Skyrme force parameters. We suggest the procedure
of derivation of the isospin symmetry energy from analysis of the isospin shift
of chemical potential $\Delta\lambda = \lambda_n - \lambda_p$ beyond the
beta-stability line.


title:
Multiplier ideal sheaves and the K\"ahler-Ricci flow on toric Fano
  manifolds with large symmetry

abstract:
  The purpose of this paper is to calculate the support of the multiplier ideal
sheaves derived from the K\"ahler-Ricci flow on certain toric Fano manifolds
with large symmetry. The early idea of this paper has already been in Appendix
of \cite{futaki-sano0711}.


title: Exclusive quasielastic production of dijets at hadronic colliders

abstract:
  We critically re-examine the calculation of central production of dijets in
quasi-elastic hadronic collisions. We find that the process is not dominated by
the perturbative contribution, and discuss several sources of uncertainties in
the calculation.


title: Quantifiers for quantum logic

abstract:
  We consider categorical logic on the category of Hilbert spaces. More
generally, in fact, any pre-Hilbert category suffices. We characterise closed
subobjects, and prove that they form orthomodular lattices. This shows that
quantum logic is just an incarnation of categorical logic, enabling us to
establish an existential quantifier for quantum logic, and conclude that there
cannot be a universal quantifier.


title:
Bridges of Low Energy observables with Leptogenesis in mu-tau Reflection
  Symmetry

abstract:
  We consider an exact mu-tau reflection symmetry in neutrino sectorrealized at
the GUT scale in the context of the seesaw model with and without
supersymmetry. Assuming the two lighter heavy Majorana neutrinos are degenerate
at the GUT scale, it is shown that the renormalization group (RG) evolution
from the GUT scale to the seesaw scale gives rise to breaking of the mu-tau
symmetry and a tiny splitting between two degenerate heavy Majorana neutrino
masses as well as small variations of the CP phases in Y_nu, which are
essential to achieve a successful leptogenesis. Such small RG effects lead to
tiny deviations of theta_{23} from the maximal value and the CP phase
delta_{CP} from pi/2 imposed at the GUT scale due to mu-tau reflection
symmetry. In our scenario, the required amount of the baryon asymmetry eta_B
can be generated via so-called resonant e-leptogenesis, in which the wash-out
factor concerned with electron flavor plays a crucial role in reproducing a
successful leptogenesis. We show that CP violation responsible for the
generation of baryon asymmetry of our universe can be directly linked with CP
violation measurable through neutrino oscillation as well as neutrino mixing
angles theta_{12} and theta_{13}. We expect that, in addition to the reactor
and long baseline neutrino experiments, the measurements for the supersymmetric
parameter tan{beta} at future collider experiments would serve as an indirect
test of our scenario of baryogenesis based on the mu-tau reflection symmetry.


title:
Influence of metal contacts and charge inhomogeneity on transport
  properties of graphene near the neutrality point

abstract:
  There is an increasing amount of literature concerning electronic properties
of graphene close to the neutrality point. Many experiments continue using the
two-probe geometry or invasive contacts or do not control samples' macroscopic
homogeneity. We believe that it is helpful to point out some problems related
to such measurements. By using experimental examples, we illustrate that the
charge inhomogeneity induced by spurious chemical doping or metal contacts can
lead to large systematic errors in assessing graphene's transport properties
and, in particular, its minimal conductivity. The problems are most severe in
the case of two-probe measurements where the contact resistance is found to
strongly vary as a function of gate voltage.


title: Parity Violation in Hydrogen and Longitudinal Atomic Beam Spin Echo I

abstract:
  We discuss the propagation of hydrogen atoms in static electric and magnetic
fields in a longitudinal atomic beam spin echo (lABSE) apparatus. There the
atoms acquire geometric (Berry) phases that exhibit a new manifestation of
parity-(P-)violation in atomic physics. We provide analytical as well as
numerical calculations of the behaviour of the metastable 2S states of
hydrogen. The conditions for electromagnetic field configurations that allow
for adiabatic evolution of the relevant atomic states are investigated. Our
results provide the theoretical basis for the discussion of possible
measurements of P-violating geometric phases in lABSE experiments.


title:
A comparison of atomistic and continuum theoretical approaches to
  determine electronic properties of GaN/AlN quantum dots

abstract:
  In this work we present a comparison of multiband k.p-models, the effective
bond-orbital approach, and an empirical tight-binding model to calculate the
electronic structure for the example of a truncated pyramidal GaN/AlN
self-assembled quantum dot with a zincblende structure. For the system under
consideration, we find a very good agreement between the results of the
microscopic models and the 8-band k.p-formalism, in contrast to a 6+2-band
k.p-model, where conduction band and valence band are assumed to be decoupled.
This indicates a surprisingly strong coupling between conduction and valence
band states for the wide band gap materials GaN and AlN. Special attention is
paid to the possible influence of the weak spin-orbit coupling on the localized
single-particle wave functions of the investigated structure.


title: Matrix Models as Non-commutative Field Theories on R^3

abstract:
  In the context of spin foam models for quantum gravity, group field theories
are a useful tool allowing on the one hand a non-perturbative formulation of
the partition function and on the other hand admitting an interpretation as
generalized matrix models. Focusing on 2d group field theories, we review their
explicit relation to matrix models and show their link to a class of
non-commutative field theories invariant under a quantum deformed 3d Poincare
symmetry. This provides a simple relation between matrix models and
non-commutative geometry. Moreover, we review the derivation of effective 2d
group field theories with non-trivial propagators from Boulatov's group field
theory for 3d quantum gravity. Besides the fact that this gives a simple and
direct derivation of non-commutative field theories for the matter dynamics
coupled to (3d) quantum gravity, these effective field theories can be
expressed as multi-matrix models with non-trivial coupling between matrices of
different sizes. It should be interesting to analyze this new class of
theories, both from the point of view of matrix models as integrable systems
and for the study of non-commutative field theories.


title: Galois Theory, discriminants and torsion subgroups of elliptic curves

abstract:
  We find a tight relationship between the torsion subgroup and the image of
the mod 2 Galois representation associated to an elliptic curve defined over
the rationals. This is shown using some characterizations for the squareness of
the discriminant of the elliptic curve.


title: Dynamics of latent voters

abstract:
  We study the effect of latency on binary-choice opinion formation models.
Latency is introduced into the models as an additional dynamic rule: after a
voter changes its opinion, it enters a waiting period of stochastic length
where no further changes take place. We first focus on the voter model and show
that as a result of introducing latency, the average magnetization is not
conserved, and the system is driven toward zero magnetization, independently of
initial conditions. The model is studied analytically in the mean-field case
and by simulations in one dimension. We also address the behavior of the
Majority Rule model with added latency, and show that the competition between
imitation and latency leads to a rich phenomenology.


title:
Some Results on Cubic and Higher Order Extensions of the Poincar\'e
  Algebra

abstract:
  In these lectures we study some possible higher order (of degree greater than
two) extensions of the Poincar\'e algebra. We first give some general
properties of Lie superalgebras with some emphasis on the supersymmetric
extension of the Poincar\'e algebra or Supersymmetry. Some general features on
the so-called Wess-Zumino model (the simplest field theory invariant under
Supersymmetry) are then given. We further introduce an additional algebraic
structure called Lie algebras of order F, which naturally comprise the concepts
of ordinary Lie algebras and superalgebras. This structure enables us to define
various non-trivial extensions of the Poincar\'e algebra. These extensions are
studied more precisely in two different contexts. The first algebra we are
considering is shown to be an (infinite dimensional) higher order extension of
the Poincar\'e algebra in $(1+2)-$dimensions and turns out to induce a symmetry
which connects relativistic anyons. The second extension we are studying is
related to a specific finite dimensional Lie algebra of order three, which is a
cubic extension of the Poincar\'e algebra in $D-$space-time dimensions.
Invariant Lagrangians are constructed.


title: Magnetohydrodynamic turbulence in supernova remnants

abstract:
  We present estimates of the angular power spectra of the synchrotron
radiation intensity fluctuations at 6 and 20 cm for the shell type supernova
remnant Cas A and the filled-centre Crab supernova remnant. We find that the
intensity fluctuations of both sources have a power law power spectrum with
index -3.24 +/- 0.03. This power law power spectrum is consistent with the
magnetohydrodynamic turbulence in the synchrotron emitting plasma. For Cas A,
there is a break in the power spectrum and the power law index changes from
-3.2 to -2.2 at large angular scale. This transition occurs at an angular scale
that corresponds to the shell thickness of Cas A. We interpret this as a
transition from three dimensional turbulence to two dimensional turbulence on
scales that are respectively smaller and larger than the shell thickness.


title:
Magnetic acceleration of ultra-relativistic jets in gamma-ray burst
  sources

abstract:
  We present a relativistic-MHD numerical study of axisymmetric, magnetically
driven jets with parameters applicable to gamma-ray burst (GRB) flows. We also
present analytic expressions for the asymptotic jet shape and other flow
parameters that agree very well with the numerical results. All
current-carrying outflows exhibit self-collimation and consequent acceleration
near the rotation axis, but unconfined outflows lose causal connectivity across
the jet and therefore do not collimate or accelerate efficiently in their outer
regions. Magnetically accelerated jets confined by an external pressure that
varies with distance with a power-law index < 2 assume a paraboloidal shape and
have an acceleration efficiency > 50%. They attain Lorentz factors > 30 on
scales 10^9-3x10^10 cm, consistent with the possibility that short/hard GRB
jets are accelerated on scales where they can be confined by moderately
relativistic winds from accretion discs, and > 100 on scales 10^10-10^12 cm,
consistent with the possibility that long/soft GRB jets are accelerated within
the envelopes of collapsing massive stars. We also find that the Lorentz factor
of a magnetically accelerated jet is approximately inversely proportional to
the opening half-angle of the poloidal streamlines. This implies that the
gamma-ray emitting components of GRB outflows are very narrow, with a
half-angle < 1 degree in regions where the Lorentz factor exceeds 100, and that
the afterglow light curves of these components would either exhibit a very
early jet break or show no jet break at all.


title:
Quasi-one dimensional graphite ribbon structures in presence of magnetic
  field and on-site Coulomb correlation at half-filling

abstract:
  We have presented the role of the Coulomb interaction ($U$) and the magnetic
field ($\vec{B}$) on the ground state properties of the quasi-one dimensional
graphite ribbon structures at half-filling. Mean field Hartree-Fock
Approximation is used to study the systems. To understand the boundary effects
in graphite structures, we have compared the results of these systems with
those of the square lattice ribbon structures. Studying the density of states,
the Drude weight and the charge gap, we have drawn the $U-B$ phase diagrams for
the zigzag and the armchair graphite ribbons.


title: On the String Equation of the BKP Hierarchy

abstract:
  The Adler-Shiota-van Moerbeke formula is employed to derive the
$W$-constraints for the $p$-reduced BKP hierarchy constrained by the string
equation. We also provide the Grassmannian description of the string equation
in terms of the spectral parameter.


title:
HCO mapping of the Horsehead : Tracing the illuminated dense molecular
  cloud surfaces

abstract:
  Far-UV photons strongly affect the physical and chemical state of molecular
gas in the vicinity of young massive stars. We have obtained maps of the HCO
and H13CO+ ground state lines towards the Horsehead edge at 5'' angular
resolution with a combination of IRAM PdBI and 30m observations. These maps
have been complemented with IRAM-30m observations of several excited
transitions at two different positions. Bright formyl radical emission
delineates the illuminated edge of the nebula, with a faint emission remaining
towards the shielded molecular core. Viewed from the illuminated star, the HCO
emission almost coincides with the PAH and CCH emission. HCO reaches a similar
abundance than HCO+ in the PDR (~1-2 x10^{-9} with respect to H2). Pure
gas-phase chemistry models fail to reproduce the observed HCO abundance by ~2
orders of magnitude, except if reactions of OI with carbon radicals abundant in
the PDR (i.e., CH2) play a significant role in the HCO formation.
Alternatively, HCO could be produced in the PDR by non-thermal processes such
as photo-processing of ice mantles and subsequent photo-desorption of either
HCO or H2CO, and further gas phase photodissociation. The measured HCO/H13CO+
abundance ratio is large towards the PDR (~50), and much lower toward the gas
shielded from FUV radiation (<1). We propose that high HCO abundances
(>10^{-10}) together with large HCO/H13CO+ abundance ratios (>1) are sensitive
diagnostics of the presence of active photochemistry induced by FUV radiation.


title: Dynamics and Efficiency of Brownian Rotors

abstract:
  Brownian rotors play an important role in biological systems and in future
nano-technological applications. However the mechanisms determining their
dynamics, efficiency and performance remain to be characterized. Here the F0
portion of the F-ATP synthase is considered as a paradigm of a Brownian rotor.
In a generic analytical model we analyze the stochastic rotation of F0-like
motors as a function of the driving free energy difference and of the free
energy profile the rotor is subjected to. The latter is composed of the rotor
interaction with its surroundings, of the free energy of chemical transitions,
and of the workload. The dynamics and mechanical efficiency of the rotor
depends on the magnitude of its stochastic motion driven by the free energy
energy difference and its rectification on the reaction-diffusion path. We
analyze which free energy profiles provide maximum flow and how their
arrangement on the underlying reaction-diffusion path affects rectification and
-- by this -- the efficiency.

categories: physics.bio-ph cond-mat.soft physics.chem-ph q-bio.QM


title:
Strong short-range magnetic order in a frustrated FCC lattice and its
  possible role in the iron structural transformation

abstract:
  We investigate magnetic properties of a frustrated Heisenberg antiferromagnet
with a face-centered cubic (FCC) lattice and exchange interactions between the
nearest- and next-nearest neighbours, J1 and J2. In a collinear phase with the
wave vector Q = (pi,pi,pi) the equations of the self-consistent spin-wave
theory for the sublattice magnetization and the average short range order
parameter are obtained and numerically solved. The dependence of the Neel
temperature T_N on the ratio J2/J1 is obtained. It is shown, that at strong
enough frustration there is a wide temperature region above T_N with strong
short range magnetic order. Application of this result to description of
structural phase transition between alpha and gamma-phase of Fe is considered.


title: Masses, Beaming and Eddington Ratios in Ultraluminous X-ray Sources

abstract:
  I suggest that the beaming factor in bright ULXs varies as $b \propto \dot
m^{-2}$, where $\dot m$ is the Eddington ratio for accretion. This is required
by the observed universal $L_{\rm soft} \propto T^{-4}$ relation between
soft--excess luminosity and temperature, and is reasonable on general physical
grounds. The beam scaling means that all observable properties of bright ULXs
depend essentially only on the Eddington ratio $\dot m$, and that these systems
vary mainly because the beaming is sensitive to the Eddington ratio. This
suggests that bright ULXs are stellar--mass systems accreting at Eddington
ratios of order 10 -- 30, with beaming factors $b \ga 0.1$. Lower--luminosity
ULXs follow bolometric (not soft--excess) $L \sim T^4$ correlations and
probably represent {\it sub}--Eddington accretion on to black holes with masses
$\sim 10\msun$. High--mass X-ray binaries containing black holes or neutron
stars and undergoing rapid thermal-- or nuclear--timescale mass transfer are
excellent candidates for explaining both types. If the $b \propto \dot m^{-2}$
scaling for bright ULXs can be extrapolated to the Eddington ratios found in
SS433, some objects currently identified as AGN at modest redshifts might
actually be ULXs (`pseudoblazars'). This may explain cases where the active
source does not coincide with the centre of the host galaxy.


title: DR21 Main: A Collapsing Cloud

abstract:
  The molecular cloud, DR21 Main, is an example of a large-scale gravitational
collapse about an axis near the plane of the sky where the collapse is free of
major disturbances due to rotation or other effects. Using flux maps,
polarimetric maps, and measurements of the field inclination by comparing the
line widths of ion and neutral species, we estimate the temperature, mass,
magnetic field, and the turbulent kinetic, mean magnetic, and gravitational
potential energies, and present a 3D model of the cloud and magnetic field.


title:
Phase-field-crystal modeling of the (2x1)-(1x1) phase-transitions of
  Si(001) and Ge(001) surfaces

abstract:
  We propose a two-dimensional phase-field-crystal model for the
(2$\times$1)-(1$\times$1) phase transitions of Si(001) and Ge(001) surfaces.
The dimerization in the 2$\times$1 phase is described with a
phase-field-crystal variable which is determined by solving an evolution
equation derived from the free energy. Simulated periodic arrays of
dimerization variable is consistent with scanning-tunnelling-microscopy images
of the two dimerized surfaces. Calculated temperature dependence of the
dimerization parameter indicates that normal dimers and broken ones coexist
between the temperatures describing the charactristic temperature width of the
phase-transition, $T_L$ and $T_H$, and a first-order phase transition takes
place at a temperature between them. The dimerization over the whole
temperature is determined. These results are in agreement with experiment. This
phase-field-crystal approach is applicable to phase-transitions of other
reconstructed surface phases, especially semiconductor $n\times$1 reconstructed
surface phases.


title: A fully nonlinear problem with free boundary in the plane

abstract:
  We prove that bounded solutions to an overdetermined fully nonlinear free
boundary problem in the plane are one dimensional. Our proof relies on maximum
principle techniques and convexity arguments.


title: Horseshoes in multidimensional scaling and local kernel methods

abstract:
  Classical multidimensional scaling (MDS) is a method for visualizing
high-dimensional point clouds by mapping to low-dimensional Euclidean space.
This mapping is defined in terms of eigenfunctions of a matrix of interpoint
dissimilarities. In this paper we analyze in detail multidimensional scaling
applied to a specific dataset: the 2005 United States House of Representatives
roll call votes. Certain MDS and kernel projections output ``horseshoes'' that
are characteristic of dimensionality reduction techniques. We show that, in
general, a latent ordering of the data gives rise to these patterns when one
only has local information. That is, when only the interpoint distances for
nearby points are known accurately. Our results provide a rigorous set of
results and insight into manifold learning in the special case where the
manifold is a curve.


title: General Relativistic Rotation Curves in a Post-Newtonian Light

abstract:
  The missing of a Keplerian fall-off in the observed galaxy rotation curves
represents classical evidence for the existence of dark matter on galactic
scales. There has been some recent activity concerning the potential of
modelling galactic systems with the help of general relativity. This was
motivated by claims that by the use of full general relativity dark matter
could be made superfluous. Here we focus on possible axisymmetric and
stationary solutions of Einstein's equations with rotating dust. After a short
review of the current debate we pursue the idea of approaching such
relativistic models in a Newtonian language. We analyse rigidly as well as
differentially rotating Newtonian and Post-Newtonian spacetimes and find that
it is necessary to incorporate a Post-Newtonian term in order to make physical
sense.


title: Minority Games

abstract:
  We present a simple introduction to the basic Minority Game (MG) introduced
by Challet and Zhang in 1997 and discuss some of its physical properties and
subsequent developments. We also introduce some of its variants include the
Evolutionay Minority Game (EMG), the Thermal Minority Game (TMG), the simple
Minority Game without information and the Grand-canonical Minority Game (GCMG).
Some analytical approaches on Minority Games and the relations of Minority
Games with financial market are also briefly discussed.


title: Exact Categories

abstract:
  We survey the basics of homological algebra in exact categories in the sense
of Quillen. All diagram lemmas are proved directly from the axioms, notably the
five lemma, the 3 x 3-lemma and the snake lemma. We briefly discuss exact
functors, idempotent completion and weak idempotent completeness. We then show
that it is possible to construct the derived category of an exact category
without any embedding into abelian categories and we sketch Deligne's approach
to derived functors. The construction of classical derived functors with values
in an abelian category painlessly translates to exact categories, i.e., we give
proofs of the comparison theorem for projective resolutions and the horseshoe
lemma. After discussing some examples we elaborate on Thomason's proof of the
Gabriel-Quillen embedding theorem in an appendix.


title: Diffractive processes at the LHC

abstract:
  We present a model of high energy soft $pp$ interactions that has multi s-
and t-channel components, which has been tuned to describe all the available
data. The t-channel components allow matching of the soft to the hard (QCD)
Pomeron. Absorptive effects are found to be large, and, for example, suppress
the prediction of the total $pp$ cross section to about 90 mb at the LHC. We
use the model to calculate the survival probability, S^2, of the rapidity gaps
in the exclusive process pp \to p+H+p, a process with great advantages for
searching for the H \to \bb signal. We consider both eikonal and enhanced
rescattering.


title: C*-Algebras Associated with Iterated Function Systems

abstract:
  We review Kajiwara and Watatani's construction of a C*-algebra from an
iterated function system (IFS). If the IFS satisfies the finite branch
condition or the open set condition, we build an injective homomorphism from
Kajiwara-Watatani algebras to the Cuntz algebra, which can be thought as the
algebra of the lifted system, and we give the description of its image.
Finally, if the IFS admits a left inverse we show that the Kajiwara-Watatani
algebra is isomorphic to an Exel's crossed product.


title: A five-wave HLL Riemann solver for relativistic MHD

abstract:
  We present a five-wave Riemann solver for the equations of ideal relativistic
magnetohydrodynamics. Our solver can be regarded as a relativistic extension of
the five-wave HLLD Riemann solver initially developed by Miyoshi and Kusano for
the equations of ideal MHD. The solution to the Riemann problem is approximated
by a five wave pattern, comprised of two outermost fast shocks, two rotational
discontinuities and a contact surface in the middle. The proposed scheme is
considerably more elaborate than in the classical case since the normal
velocity is no longer constant across the rotational modes. Still, proper
closure to the Rankine-Hugoniot jump conditions can be attained by solving a
nonlinear scalar equation in the total pressure variable which, for the chosen
configuration, has to be constant over the whole Riemann fan. The accuracy of
the new Riemann solver is validated against one dimensional tests and
multidimensional applications. It is shown that our new solver considerably
improves over the popular HLL solver or the recently proposed HLLC schemes.


title: Compactification minimale et mauvaise reduction

abstract:
  We construct the minimal compactification of some modular Siegel varieties at
their bad reduction places. These varieties parametrize principally polarized
abelian schemes endowed with a parahoric level structure at a prime number $p$,
and with an auxiliary level structure ; such varieties have bad reduction at
$p$. We also sketch the arithmetic theory of the associated Siegel modular
forms.
  -----
  Nous construisons la compactification minimale de certaines varietes
modulaires de Siegel en leurs places de mauvaise reduction. Ces varietes
parametrent des schemas abeliens principalement polarises munis d'une structure
de niveau parahorique en un nombre premier $p$, et d'une structure de niveau
auxilliaire ; elles ont mauvaise reduction en $p$. Nous esquissons egalement
une theorie arithmetique des formes modulaires de Siegel associees a ces
varietes.


title: Categorified Noncommutative manifolds

abstract:
  We construct a noncommutative geometry with generalised `tangent bundle' from
Fell bundle $C^*$-categories ($E$) beginning by replacing pair groupoid objects
(points) with objects in $E$. This provides a categorification of a certain
class of real spectral triples where the Dirac operator is constructed from
morphisms in a category. Applications for physics include quantisation via the
tangent groupoid and new constraints on $D_{\mathrm{finite}}$ (the fermion mass
matrix).


title:
Higgs mechanism from fluxes and two mass hierarchies in the "fat" throat
  solution of Type IIA supegravity

abstract:
  Spectra of Kaluza-Klein gauge fields are calculated at the background of the
magnetic fluxbrane throat-like solution of the Type IIA supergravity equations.
Magnetic flux plays the role of Higgs scalar generating the electroweak scale
mass of non-abelian KK gauge field. The same "flux-Higgs" mechanism gives the
scale of the "second mass hierarchy", 0.001 eV, in the spectrum of KK
excitations at the background of the throat deformed in a Reissner-Nordstrom
way. Gauge coupling constants in 4 dimensions are calculated; they prove to be
of the physically sensible values for the EW scale massive modes of the gauge
fields and are extremely small for the long range gauge fields. 5D effective
Action with the flux-generated mass terms of the KK gauge fields associated
with isometries of compactified subspaces is put down, correspondence of the
"classical" KK approach and dual holography approach to the low-dimensional
gauge theories is discussed, and idea of Bootstrap Holography is set forth.


title:
Total electronic energy by tight binding approximation and experimental
  toughness of three different hybrid polymers

abstract:
  We computed by a modified tight binding approximation, the total electronic
energy of three different hybrid polymers: $H-SiO_2$, $CH_3-SiO_2$ and
$C_6H_5-SiO_2$. We made the hypothesis that the structures of these polymers
are amorphous. Computational results regarding the total electronic energy and
experimental data \cite{ferchichi} on the toughness of these three hybrid
polymers were compared. A good qualitative agreement was found between
computations and experiments.


title: Cores and Cusps in the Dwarf Spheroidals

abstract:
  We consider the problem of determining the structure of the dark halo of
nearby dwarf spheroidal galaxies (dSphs) from the spherical Jeans equations.
Whether the dark halos are cusped or cored at the centre is an important
strategic problem in modern astronomy. The observational data comprise the
line-of-sight velocity dispersion of a luminous tracer population. We show that
when such data are analysed to find the dark matter density with the spherical
Poisson and Jeans equations, then the generic solution is a dark halo density
that is cusped like an isothermal. Although milder cusps (like the
Navarro-Frenk-White 1/r cusp and even cores are possible, they are not generic.
Such solutions exist only if the anisotropy parameter beta and the logarithmic
slope of the stellar density gamma satisfy the constraint gamma = 2 x beta at
the centre or if the radial velocity dispersion falls to zero at the centre.
This surprisingly strong statement is really a consequence of the assumption of
spherical symmetry, and the consequent coordinate singularity at the origin.
So, for example, a dSph with an exponential light profile can exist in
Navarro-Frenk- White halo and have a flat velocity dispersion, but anisotropy
in general drives the dark halo solution to an isothermal cusp. The identified
cusp or core is therefore a consequence of the assumptions (particularly of
spherical symmetry and isotropy), and not the data.


title:
Electronic properties of single-crystalline Fe$_{1.05}$Te and
  Fe$_{1.03}$Se$_{0.30}$Te$_{0.70}$

abstract:
  We report on a comprehensive study of the transport, specific heat, magnetic
susceptibility and optical spectroscopy on single crystal of Fe$_{1.05}$Te. We
confirm that Fe$_{1.05}$Te undergoes a first-order phase transition near 65 K.
However, its physical properties are considerably different from other parent
compounds of FeAs-based systems, presumably attributed to the presence of
excess Fe ions. The charge transport is rather incoherent above the transition,
and no clear signature of the gap is observed below the transition temperature.
Strong impurity scattering effect exists also in Se-doped superconducting
sample Fe$_{1.03}$Se$_{0.30}$Te$_{0.70}$, leading to a relatively low T$_c$ but
a rather high upper critical field.


title: Matrix valued Brownian motion and a paper by Polya

abstract:
  We give a geometric description of the motion of eigenvalues of a Brownian
motion with values in some matrix spaces. In the second part we consider a
paper by Polya where he introduced a function close to the Riemann zeta
function, which satisfies Riemann hypothesis. We show that each of these two
functions can be related to Brownian motion on a symmetric space.


title:
Bodeker's Effective Theory: From Langevin Dynamics to Dyson-Schwinger
  Equations

abstract:
  The dynamics of weakly coupled, non-abelian gauge fields at high temperature
is non-perturbative if the characteristic momentum scale is of order |k|~ g^2
T. Such a situation is typical for the processes of electroweak baryon number
violation in the early Universe. Bodeker has derived an effective theory that
describes the dynamics of the soft field modes by means of a Langevin equation.
This effective theory has been used for lattice calculations so far. In this
work we provide a complementary, more analytic approach based on
Dyson-Schwinger equations. Using methods known from stochastic quantisation, we
recast Bodeker's Langevin equation in the form of a field theoretic path
integral. We introduce gauge ghosts in order to help control possible gauge
artefacts that might appear after truncation, and which leads to a BRST
symmetric formulation and to corresponding Ward identities. A second set of
Ward identities, reflecting the origin of the theory in a stochastic
differential equation, is also obtained. Finally Dyson-Schwinger equations are
derived.


title:
Differential transformations of parabolic second-order operators in the
  plane

abstract:
  Here, Darboux's classical results about transformations with differential
substitutions for hyperbolic equations are extended to the case of parabolic
equations of the form $L u = \big(D^2_{x} + a(x,y) D_x + b(x,y) D_y +
c(x,y)\big)u=0$.
  We prove a general Theorem that provides a way to determine transformations
for parabolic equations shown above. It turnes out that transforming operators
$M$ of some higher order can be always represented as a composition of some
first-order operators that consecutively define a series of transformations.
  Existence of inverse transformations implies some differential constrains on
the coefficients of the initial operator. We show that these relations can
imply famous integrable equations, in particular, the Boussinesq equation.


title:
Scalar field cosmology in the energy phase-space -- unified description
  of dynamics

abstract:
  In this letter we apply dynamical system methods to study all evolutional
paths admissible for all initial conditions of the FRW cosmological model with
a non-minimally coupled to gravity scalar field and a barotropic fluid. We
choose "energy variables" as phase variables. We reduce dynamics to a
3-dimensional dynamical system for an arbitrary potential of the scalar field
in the phase space variables. After postulating the potential parameter
$\Gamma$ as a function of $\lambda$ (defined as $-V'/V$) we reduce whole
dynamics to a 3-dimensional dynamical system and study evolutional paths
leading to current accelerating expansion. If we restrict the form of the
potential then we will obtain a 2-dimensional dynamical system. We use the
dynamical system approach to find a new generic quintessence scenario of
approaching to the de Sitter attractor which appears only for the case of
non-vanishing coupling constant.


title:
A variable near-infrared counterpart to the neutron-star low-mass X-ray
  binary 4U 1705-440

abstract:
  We report the discovery of a near-infrared (nIR) counterpart to the
persistent neutron-star low-mass X-ray binary 4U 1705-440, at a location
consistent with its recently determined Chandra X-ray position. The nIR source
is highly variable, with K_s-band magnitudes varying between 15.2 and 17.3 and
additional J- and H-band observations revealing color variations. A comparison
with contemporaneous X-ray monitoring observations shows that the nIR
brightness correlates well with X-ray flux and X-ray spectral state. We also
find possible indications for a change in the slope of the nIR/X-ray flux
relation between different X-ray states. We discuss and test various proposed
mechanisms for the nIR emission from neutron-star low-mass X-ray binaries and
conclude that the nIR emission in 4U 1705-440 is most likely dominated by X-ray
heating of the outer accretion disk and the secondary star.


title:
On the problem of detecting linear dependence for products of abelian
  varieties and tori

abstract:
  Let G be the product of an abelian variety and a torus defined over a number
field K. Let R be a point in G(K) and let L be a finitely generated subgroup of
G(K). Suppose that for all but finitely many primes p of K the point (R mod p)
belongs to (L mod p). Does it follow that R belongs to L? We answer this
question affirmatively in three cases: if L is cyclic; if L is a free left
End_K G-submodule of G(K); if L has a set of generators (as a group) which is a
basis of a free left End_K G-submodule of G(K). In general we prove that there
exists an integer m (depending only on G, K and the rank of L) such that mR
belongs to the left End_K G-submodule of G(K) generated by L.


title: Robust adaptive importance sampling for normal random vectors

abstract:
  Adaptive Monte Carlo methods are very efficient techniques designed to tune
simulation estimators on-line. In this work, we present an alternative to
stochastic approximation to tune the optimal change of measure in the context
of importance sampling for normal random vectors. Unlike stochastic
approximation, which requires very fine tuning in practice, we propose to use
sample average approximation and deterministic optimization techniques to
devise a robust and fully automatic variance reduction methodology. The same
samples are used in the sample optimization of the importance sampling
parameter and in the Monte Carlo computation of the expectation of interest
with the optimal measure computed in the previous step. We prove that this
highly dependent Monte Carlo estimator is convergent and satisfies a central
limit theorem with the optimal limiting variance. Numerical experiments confirm
the performance of this estimator: in comparison with the crude Monte Carlo
method, the computation time needed to achieve a given precision is divided by
a factor between 3 and 15.


title:
XMM-Newton observation of MACHO 104.20906.960: a dwarf nova candidate
  with a 2 h period

abstract:
  The binaries known as cataclysmic variables are particular binary systems in
which the primary star (a white dwarf) accretes material from a secondary via
Roche-lobe mechanism. Usually, these objects have orbital period of a few hours
so that a detailed temporal analysis can be performed. Here, we present Chandra
${\it XMM}$-Newton observations of a dwarf nova candidate identified in the
past by optical observations towards the galactic Bulge and labeled as MACHO
104.20906.960. After a spectral analysis, we used the Lomb-Scargle technique
for the period search and evaluated the confidence level using Monte-Carlo
simulations. In this case, we found that the $X$-ray source shows a period of
$2.03_{-0.07}^{+0.09} $ hours (3$\sigma$ error) so that it is most likely a
system of interacting objects. The modulation of the signal was found with a
confidence level of $>$99%. The spectrum can be described by a two thermal
plasma components with X-ray flux in the 0.3--10 keV energy band of
$1.77_{-0.19}^{+0.16}\times10^{-13}$ erg s$^{-1}$ cm$^{-2}$. We find that the
distance of the source is approximately 1 kpc thus corresponding to a
luminosity $L_{X}\simeq 2\times 10^{31}$ erg s$^{-1}$.


title:
Ultra-fast quenching of binary colloidal suspensions in an external
  magnetic field

abstract:
  An ultra-fast quench is applied to binary mixtures of superparamagnetic
colloidal particles confined at a two-dimensional water-air interface by a
sudden increase of an external magnetic field. This quench realizes a virtually
instantaneous cooling which is impossible in molecular systems. Using
real-space experiments, the relaxation behavior after the quench is explored.
Local crystallites with triangular and square symmetry are formed on different
time scales and the correlation peak amplitude of the small particles evolves
nonmonotonically in time in agreement with Brownian dynamics computer
simulations.


title: Dynamical screening of an endohedral atom

abstract:
  The present work is a generalisation of the dynamical screening factor
presented in [1] to consider an atom located at an arbitrary position within
the fullerene. A more elaborated investigation into the case where the atom is
located at the centre is performed and compared with quantum mechanical
calculations for dynamical screening factor of Ar@C$_{60}$ [2] and Mg@C$_{60}$
[3]. The $\pi$ and $\sigma$ plasmons of the fullerene are accounted for in a
modified screening factor to improve correspondence with the quantum
calculations. The spatial dependence of the screening factor was explored with
Ar@C$_{60}$ and Ar@C$_{240}$ and found to depend significantly on the radial
distance of the atom from the centre of the fullerene. A spatial averaging of
the screening factor is presented.


title: Linear Processing and Sum Throughput in the Multiuser MIMO Downlink

abstract:
  We consider linear precoding and decoding in the downlink of a multiuser
multiple-input, multiple-output (MIMO) system, wherein each user may receive
more than one data stream. We propose several mean squared error (MSE) based
criteria for joint transmit-receive optimization and establish a series of
relationships linking these criteria to the signal-to-interference-plus-noise
ratios of individual data streams and the information theoretic channel
capacity under linear minimum MSE decoding. In particular, we show that
achieving the maximum sum throughput is equivalent to minimizing the product of
MSE matrix determinants (PDetMSE). Since the PDetMSE minimization problem does
not admit a computationally efficient solution, a simplified scalar version of
the problem is considered that minimizes the product of mean squared errors
(PMSE). An iterative algorithm is proposed to solve the PMSE problem, and is
shown to provide near-optimal performance with greatly reduced computational
complexity. Our simulations compare the achievable sum rates under linear
precoding strategies to the sum capacity for the broadcast channel.


title:
The ferroelectric-paraelectric phase transition in BiFeO3: crystal
  structure of the orthorhombic beta-phase

abstract:
  A detailed investigation using variable temperature powder neutron
diffraction demonstrates that BiFeO3 undergoes a phase transition from the
ferroelectric alpha phase (rhombohedral, R3c) to a paraelectric beta phase
(orthorhombic, Pbnm) between 820 oC and 830 oC. Co-existence of both phases
over a finite temperature interval, together with abrupt changes in key
structural parameters, confirm that the transition is firstorder. The beta
phase corresponds to the GdFeO3-type perovskite. The metastability of BiFeO3
relative to Bi2Fe4O9 above 810 oC precludes observation of a reported cubic
gamma phase above 925 oC under the present experimental conditions.


title:
On group properties and reality conditions of UOSp(1|2) gauge
  transformations

abstract:
  For osp(1|2;C) graded Lie algebra, which proper Lie subalgebra is su(2), we
consider the Baker-Campbell-Hausdorff formula and formulate a reality condition
for the Grassmann-odd transformation parameters that multiply the pair of odd
generators of the graded Lie algebra. Utilization of su(2)-spinors clarifies
the nature of Grassmann-odd transformation parameters and allow us an
investigation of the corresponding infinitesimal gauge transformations. We also
explore action of the corresponding group element of UOSp(1|2) on an
appropriately graded representation space and find that the graded
generalization of hermitian conjugation is compatible with the Dirac adjoint.
Consistency of generalized (graded) unitary condition with the proposed reality
condition is shown.


title: Axionic D3-D7 Inflation

abstract:
  We study the motion of a D3 brane moving within a Type IIB string vacuum
compactified to 4D on K3 x T_2/Z_2 in the presence of D7 and O7 planes. We work
within the effective 4D supergravity describing how the mobile D3 interacts
with the lightest bulk moduli of the compactification, including the effects of
modulus-stabilizing fluxes. We seek inflationary solutions to the resulting
equations, performing our search numerically in order to avoid resorting to
approximate parameterizations of the low-energy potential. We consider
uplifting from D-terms and from the supersymmetry-breaking effects of anti-D3
branes. We find examples of slow-roll inflation (with anti-brane uplifting)
with the mobile D3 moving along the toroidal directions, falling towards a
D7-O7 stack starting from the antipodal point. The inflaton turns out to be a
linear combination of the brane position and the axionic partner of the K3
volume modulus, and the similarity of the potential along the inflaton
direction with that of racetrack inflation leads to the prediction n_s \le 0.95
for the spectral index. The slow roll is insensitive to most of the features of
the effective superpotential, and requires a one-in-10^4 tuning to ensure that
the torus is close to square in shape. We also consider D-term inflation with
the D3 close to the attractive D7, but find that for a broad (but not
exhaustive) class of parameters the conditions for slow roll tend to
destabilize the bulk moduli. In contrast to the axionic case, the best
inflationary example of this kind requires the delicate adjustment of potential
parameters (much more than the part-per-mille level), and gives inflation only
at an inflection point of the potential (and so suffers from additional
fine-tuning of initial conditions to avoid an overshoot problem).


title: Parallel execution of portfolio optimization

abstract:
  Analysis of asset liability management (ALM) strategies especially for long
term horizon is a crucial issue for banks, funds and insurance companies.
  Modern economic models, investment strategies and optimization criteria make
ALM studies computationally very intensive task. It attracts attention to
multiprocessor system and especially to the cheapest one: multi core PCs and PC
clusters.
  In this article we are analyzing problem of parallel organization of
portfolio optimization, results of using clusters for optimization and the most
efficient cluster architecture for these kinds of tasks.


title:
Quadratic Magnetoelectric Effect and Magnetic Field Induced Pyroelectric
  Effect in Multiferroic BaMnF4

abstract:
  The experimental studies of magnetoelectric effects in pulse magnetic field
up to 250 kOe and their theoretical analysis on the basis of magnetic symmetry
consideration are carried out. It is shown that the nonvanishing components of
quadratic magnetoelectric effect tensor corresponding to the electric
polarization along b- and c-axes point out the triclinic distortion of the
crystal symmetry. Anomalous temperature dependence of magnetically induced
polarization Pa(Hb) testifies to the magnetically induced pyroelectric effect.
The torque curves measurements show the deflection of the spin orientation from
the b-axis at 9 degrees of arc.


title: Fermi Acceleration at relativistic Shocks

abstract:
  After a successful development of theoretical and numerical works on Fermi
acceleration at relativistic shocks, some difficulties recently raised with the
scattering issue, a crucial aspect of the process. Most pioneering works were
developed assuming the scattering off magnetic fluctuations as given. Even in
that case, when a mean field is considered, its orientation is mostly
perpendicular to the shock normal in the front frame, and this tends to quench
the scattering process. Solving this difficulty leads to address the issue of
the generation of very intense magnetic fluctuations at short wave lengths. The
relativistic motion of the shock front let the cosmic rays to visit upstream
during a very short time only, making this generation of magnetic fluctuations
very challenging. Anyway there is some hope to solve the problem. Thanks to a
recent work by Spitkovsky (2008) \cite{AS}, we know that the process works
without any mean field and now we have to investigate up to which intensity the
mean field can be amplified for allowing Fermi process with appropriate fast
instabilities. In this presentation, the collisionless shock structure in
relativistic regime is sketched, the scattering issue is presented, and the
instabilities that can provide the expected magnetic field amplification are
presented as well. Although there exists observational evidence that particles
are accelerated in relativistic flows and are distributed according to a power
law suggesting a Fermi process, the drastic conditions for Fermi process to
work are not always clearly fulfilled.


title:
Electronic Structure of Superconducting FeSe Studied by High-Resolution
  Photoemission Spectroscopy

abstract:
  We have performed soft x-ray and ultrahigh-resolution laser-excited
photoemission measurements on tetragonal FeSe, which was recently identified as
a superconductor. Energy dependent study of valence band is compared to band
structure calculations and yields a reasonable assignment of partial densities
of states. However, the sharp peak near the Fermi level slightly deviates from
the calculated energy position, giving rise to the necessity of self-energy
correction. We have also performed ultrahigh-resolution laser photoemission
experiment on FeSe and observed the suppression of intensity around the Fermi
level upon cooling.