title: Integrability and Generalized Monodromy Matrix

abstract:
  We construct the Generalized Monodromy matrix $\mathcal{\hat{M}}(\omega)$ of
two dimensional string effective action by introducing the T-duality group
properties.The integrability conditions with general solutions depending on
spectral parameter are given. This construction is investigated for the exactly
solvable Wess, Zumino, Novikov and Witten (WZNW) model in pp-wave Limit when
B=0.


title:
Magnetic Excitations of the Diagonal Incommensurate Phase in
  Lightly-Doped La2-xSrxCuO4

abstract:
  We present inelastic neutron scattering experiments on a single-domain
crystal of lightly-doped La1.96Sr0.04CuO4. We find that the magnetic excitation
spectrum in this insulating phase with a diagonal incommensurate spin
modulation is remarkably similar to that in the superconducting regime, where
the spin modulation is bond parallel. In particular, we find that the
dispersion slope at low energy is essentially independent of doping and
temperature over a significant range. The energy at which the excitations cross
the commensurate antiferromagnetic wave vector increases roughly linearly with
doping through the underdoped regime.


title: Extended UV (XUV) Emission in Nearby Galaxy Disks

abstract:
  We summarize the main properties of the extended UV (XUV) emission found in
roughly 30% of the nearby spiral galaxies observed by the GALEX satellite. Two
different classes of XUV disks are identified, the Type 1 XUV disks where
significant, structured UV-bright features are found beyond the "classical"
azimuthally-averaged star-formation threshold, and the Type 2 XUV disks, which
are characterized by very extended (seven times the area where most of the
stellar mass is found), blue [(FUV-K)<5mag] outer disks. These latter disks are
extreme examples of galaxies growing inside-out. The few XUV disks studied in
detail to date are rich in HI but relatively poor in molecular gas, have
stellar populations with luminosity-weighted ages of ~1 Gyr, and ionized-gas
metal abundances of ~Zsun/10. As part of the CAHA-XUV project we are in the
process of obtaining deep multi-wavelength imaging and spectroscopy of 65
XUV-disk galaxies so to determine whether or not these properties are common
among XUV disks.


title: On the Number of Matchings in Regular Graphs

abstract:
  For the set of graphs with a given degree sequence, consisting of any number
of $2's$ and $1's$, and its subset of bipartite graphs, we characterize the
optimal graphs who maximize and minimize the number of $m$-matchings. We find
the expected value of the number of $m$-matchings of $r$-regular bipartite
graphs on $2n$ vertices with respect to the two standard measures. We state and
discuss the conjectured upper and lower bounds for $m$-matchings in $r$-regular
bipartite graphs on $2n$ vertices, and their asymptotic versions for infinite
$r$-regular bipartite graphs. We prove these conjectures for 2-regular
bipartite graphs and for $m$-matchings with $m\le 4$.


title: Core Mass Function: The Role of Gravity

abstract:
  We analyze the mass distribution of cores formed in an isothermal,
magnetized, turbulent, and self-gravitating nearly critical molecular cloud
model. Cores are identified at two density threshold levels. Our main results
are that the presence of self-gravity modifies the slopes of the core mass
function (CMF) at the high mass end. At low thresholds, the slope is shallower
than the one predicted by pure turbulent fragmentation. The shallowness of the
slope is due to the effects of core coalescence and gas accretion. Most
importantly, the slope of the CMF at the high mass end steepens when cores are
selected at higher density thresholds, or alternatively, if the CMF is fitted
with a log-normal function, the width of the lognormal distribution decreases
with increasing threshold. This is due to the fact that gravity plays a more
important role in denser structures selected at higher density threshold and
leads to the conclusion that the role of gravity is essential in generating a
CMF that bears more resemblance with the IMF when cores are selected with an
increasing density threshold in the observations.


title: The Effect of Satellite Galaxies on Gravitational Lensing Flux Ratios

abstract:
  Gravitational lenses with anomalous flux ratios are often cited as possible
evidence for dark matter satellites predicted by simulations of hierarchical
merging in cold dark matter cosmogonies. We show that the fraction of quads
with anomalous flux ratios depends primarily on the total mass and spatial
extent of the satellites, and the characteristic lengthscale R of their
distribution. If R is 100 kpc, then for a moderately elliptical galaxy with a
line-of-sight velocity dispersion of 250 km/s, a mass of 3 x 10^9 solar masses
in highly-concentrated (Plummer model) satellites is needed for 20% of
quadruplets to show anomalous flux ratios, rising to 1.25 x 10^10 solar masses
for 50%. Several times these masses are required if the satellites have more
extended Hernquist profiles. Compared to a typical elliptical, the flux ratios
of quads formed by typical edge-on disc galaxies with maximum discs are
significantly less susceptible to changes through substructure -- three times
the mass in satellite galaxies is needed to affect 50% of the systems. In many
of the lens systems with anomalous flux ratios, there is evidence for visible
satellites (e.g., B2045+265 or MG0414+0534). We show that optically identified
substructure should not be preponderant among lens systems with anomalies.
There are two possible resolutions of this difficulty. First, in some cases,
visible substructure may be projected within or close to the Einstein radius
and wrongly ascribed as the culprit, whereas dark matter substructure is
causing the flux anomaly. Second, bright satellites, in which baryon cooling
and condensation has taken place, may have higher central densities than dark
satellites, rendering them more efficient at causing flux anomalies.


title: The Jiang-Su algebra revisited

abstract:
  We give a number of new characterizations of the Jiang-Su algebra Z, both
intrinsic and extrinsic, in terms of C*-algebraic, dynamical, topological and
K-theoretic conditions. Along the way we study divisibility properties of
C*-algebras, we give a precise characterization of those unital C*-algebras of
stable rank one that admit a unital embedding of the dimension-drop C*-algebra
Z_{n,n+1}, and we prove a cancellation theorem for the Cuntz semigroup of
C*-algebras of stable rank one.


title:
High-field transport in semiconductor superlattices for interacting
  Wannier-Stark levels

abstract:
  We develop a microscopic theory of electron transport in superlattices within
the Wannier-Stark approach by including the interaction associated with Zener
tuneling among the energy levels pertaining to adjacent quantum wells. By using
a Monte Carlo technique we have simulated the hopping motion associated with
absorption and emission of polar optical phonons and determined the main
transport parameters for the case of a GaAs/GaAlAs structure at room
temperature. The interaction among the levels is found to be responsible for a
systematic increase of the level energy with respect to the bottom of the
quantum well at electric fields above about 20 kV/cm. When compared with the
non-interacting case, at the highest fields the average carrier energy
evidences a consistent increase which leads to a significant softening of the
negative differential value of both the drift velocity and diffusivity.


title:
Predictability and epidemic pathways in global outbreaks of infectious
  diseases: the SARS case study

abstract:
  Background: The global spread of the severe acute respiratory syndrome (SARS)
epidemic has clearly shown the importance of considering the long-range
transportation networks in the understanding of emerging diseases outbreaks.
The introduction of extensive transportation data sets is therefore an
important step in order to develop epidemic models endowed with realism.
Methods: We develop a general stochastic meta-population model that
incorporates actual travel and census data among 3 100 urban areas in 220
countries. The model allows probabilistic predictions on the likelihood of
country outbreaks and their magnitude. The level of predictability offered by
the model can be quantitatively analyzed and related to the appearance of
robust epidemic pathways that represent the most probable routes for the spread
of the disease. Results: In order to assess the predictive power of the model,
the case study of the global spread of SARS is considered. The disease
parameter values and initial conditions used in the model are evaluated from
empirical data for Hong Kong. The outbreak likelihood for specific countries is
evaluated along with the emerging epidemic pathways. Simulation results are in
agreement with the empirical data of the SARS worldwide epidemic. Conclusions:
The presented computational approach shows that the integration of long-range
mobility and demographic data provides epidemic models with a predictive power
that can be consistently tested and theoretically motivated. This computational
strategy can be therefore considered as a general tool in the analysis and
forecast of the global spreading of emerging diseases and in the definition of
containment policies aimed at reducing the effects of potentially catastrophic
outbreaks.


title: Self-gravitating branes of codimension 4 in Lovelock gravity

abstract:
  We construct a familly of exact solutions of Lovelock equations describing
codimension four branes with discrete symmetry in the transverse space. Unlike
what is known from pure Einstein gravity, where such brane solutions of higher
codimension are singular, the solutions we find, for the complete Lovelock
theory, only present removable singularities. The latter account for a
localised tension-like energy-momentum tensor on the brane, in analogy with the
case of a codimension two self-gravitating cosmic string in pure Einstein
gravity. However, the solutions we discuss present two main distinctive
features : the tension of the brane receives corrections from the induced
curvature of the brane's worldsheet and, in a given Lovelock theory, the
spectrum of possible values of the tension is discrete. These solutions provide
a new framework for the study of higher codimension braneworlds.


title: A functional central limit theorem for regenerative chains

abstract:
  Using the regenerative scheme of Comets, Fern\'andez and Ferrari (2002), we
establish a functional central limit theorem (FCLT) for discrete time
stochastic processes (chains) with summable memory decay. Furthermore, under
stronger assumptions on the memory decay, we identify the limiting variance in
terms of the process only. As applications, we define classes of binary
autoregressive processes and power-law Ising chains for which the FCLT is
fulfilled.


title:
Direct Nuclear Reactions in Lithium-Lithium Systems: 7Li+7Li at Elab = 2
  - 16 MeV

abstract:
  Angular distributions of 7Li(7Li,t), (7Li,alpha) and (7Li,6He) reactions were
measured for laboratory energies from 2 - 16 MeV. Exact finite range DWBA
analyses were performed with the aim to identify contributions of direct
processes and to investigate the applicability of DWBA to such few nucleon
systems. It turned out that DWBA can be successfully applied to estimate
differential and total cross sections of direct transfer processes in 7Li+7Li
interaction. The direct mechanism was found to play a dominant role in most of
these reactions but significant contributions of other, strongly energy
dependent processes were also established. It is suggested that these processes
might be due to isolated resonances superimposed on the backround of
statistical fluctuations arising from interference of compound nucleus and
direct transfer contributions.


title:
Parton Distributions at Hadronization from Bulk Dense Matter Produced at
  RHIC

abstract:
  We present an analysis of $\Omega$, $\Xi$, $\Lambda$ and $\phi$ spectra from
Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV in terms of distributions of
effective constituent quarks at hadronization. Consistency in quark ratios
derived from various hadron spectra provides clear evidence for hadron
formation dynamics as suggested by quark coalescence or recombination models.
We argue that the constituent quark distribution reflects properties of the
effective partonic degrees of freedom at hadronization. Experimental data
indicate that strange quarks have a transverse momentum distribution flatter
than that of up/down quarks consistent with hydrodynamic expansion in partonic
phase prior to hadronization. After the AMPT model is tuned to reproduce the
strange and up/down quark distributions, the model can describe the measured
spectra of hyperons and $\phi$ mesons very well where hadrons are formed
through dynamical coalescence.


title: Emergence of atom-light-mirror entanglement inside an optical cavity

abstract:
  We propose a scheme for the realization of a hybrid, strongly
quantum-correlated system formed of an atomic ensemble surrounded by a
high-finesse optical cavity with a vibrating mirror. We show that the steady
state of the system shows tripartite and bipartite continuous variable
entanglement in experimentally accessible parameter regimes, which is robust
against temperature.


title:
Identifying wave packet fractional revivals by means of information
  entropy

abstract:
  Wave packet fractional revivals is a relevant feature in the long time scale
evolution of a wide range of physical systems, including atoms, molecules and
nonlinear systems. We show that the sum of information entropies in both
position and momentum conjugate spaces is an indicator of fractional revivals
by analyzing three different model systems: $(i)$ the infinite square well,
$(ii)$ a particle bouncing vertically against a wall in a gravitational field,
and $(iii)$ the vibrational dynamics of hydrogen iodide molecules. This
description in terms of information entropies complements the usual one in
terms of the autocorrelation function.


title: Mixed-Symmetry Massless Fields in Minkowski space Unfolded

abstract:
  The unfolded formulation for arbitrary massless mixed-symmetry bosonic and
fermionic fields in Minkowski space is constructed. The unfolded form is proved
to be uniquely determined by the requirement that all gauge symmetries are
manifest. The unfolded equations have the form of a covariant constancy
condition. The gauge fields and gauge parameters are differential forms with
values in certain irreducible Lorentz tensors. The unfolded equations for
bosons determine completely those for fermions. The proposed unfolded
formulation also contains dual formulations for massless mixed-symmetry fields.


title:
The evolution of the morphological scale of early-type galaxies since
  z=2

abstract:
  We present the morphological analysis based on HST-NICMOS observations in the
F160W filter of a sample of 30 early-type galaxies spectroscopically confirmed
at 1.2<z<2. We derive the effective radius R_e and the mean surface brightness
mu_e of galaxies in the rest-frame R-band. We find that early-types at z~1.5
are characterized by a surface brightness (SB) much higher then their local
counterparts with comparable R_e. In particular, we find that the mean SB of
these early-types should get fainter by ~2.5 mag from z~1.5 to z=0 to match the
SB of the local early-types with comparable R_e. This evolution exceeds by a
factor two the luminosity evolution expected for early-types in this redshift
range and more than a factor three the one derived from the observed luminosity
function of galaxies. Consequently, an evolution of the effective radius R_e
from the epoch of their formation towards z=0 has to be invoked and the
hypothesis of fixed size rejected.


title: The Dancing Sky: 6 years of night sky observations at Cerro Paranal

abstract:
  The present work provides the results of the first six years of operation of
the systematic night-sky monitoring at ESO-Paranal (Chile). The UBVRI night-sky
brightness was estimated on about 10,000 VLT-FORS1 archival images, obtained on
more than 650 separate nights, distributed over 6 years and covering the
descent from maximum to minimum of sunspot cycle n.23. Additionally, a set of
about 1,000 low resolution, optical night-sky spectra have been extracted and
analyzed. The unprecedented database discussed in this paper has led to the
detection of a clear seasonal variation of the broad band night sky brightness
in the VRI passbands, similar to the well known semi-annual oscillation of the
NaI D doublet. The spectroscopic data demonstrate that this seasonality is
common to all spectral features, with the remarkable exception of the OH
rotational-vibrational bands. A clear dependency on the solar activity is
detected in all passbands and it is particularly pronounced in the U band,
where the sky brightness decreased by about 0.6 mag arcsec-2 from maximum to
minimum of solar cycle n.23. No correlation is found between solar activity and
the intensity of the NaI D doublet and the OH bands. A strong correlation
between the intensity of NI 5200A and [OI]6300,6364A is reported here for the
first time. The paper addresses also the determination of the correlation
timescales with solar activity and the possible connection with the flux of
charged particles emitted by the Sun.


title: New Results on the Ages of Star Clusters in Region B of M82

abstract:
  The post-starburst region B in M82 and its massive star cluster component
have been the focus of multiple studies, with reports that there is a large
population of coeval clusters of age ~1 Gyr, which were created with a Gaussian
initial mass distribution. This is in disagreement with other studies of young
star clusters, which invariably find a featureless power-law mass distribution.
Here, we present Gemini-North optical spectra of seven star clusters in M82-B
and show that their ages are all between 10 and 300 Myr (a factor of 3-100
younger than previous photometric results) and that their extinctions range
between near-zero and 4 mag (Av). Using new HST ACS-HRC U-band observations we
age date an additional ~30 clusters whose ages/extinctions agree well with
those determined from spectroscopy. Completeness tests show that the reported
`turn-over' in the luminosity/mass distributions is most likely an artefact,
due to the resolved nature of the clusters. We also show that the radial
velocities of the clusters are inconsistent with them belonging to a bound
region.


title: Non-existence and splitting theorems for normal integral bases

abstract:
  We establish new conditions that prevent the existence of (weak) normal
integral bases in tame Galois extensions of number fields. This leads to the
following result: under appropriate technical hypotheses, the existence of a
normal integral basis in the upper layer of an abelian tower Q \subset K
\subset L forces the tower to be split in a very strong sense.


title: Where are the hot ion lines in classical T Tauri stars formed?

abstract:
  Classical T Tauri stars show a plethora of in- and outflow signatures in a
variety of wavelengths bands. In order to constrain gas velocities and
temperatures we analyse the emission in the hot ion lines. We use all available
archival FUSE spectra of CTTS to measure the line widths, fluxes and shifts and
complement this sample with HST/GHRS and HST/STIS data. We present theoretical
estimates for temperatures reached in possible emission models like jets,
winds, disks and accretion funnels and look for correlations with X-ray lines
and absorption properties. We find line shifts in the range from -170 km/s and
+100 km/s. Most linewidths exceed the stellar rotational broadening. Those CTTS
with blue-shifted lines also show excess absorption in X-rays. CTTS single out
from MS stars by their large ratio of the O VII to O VI luminosities. No single
emission mechanism can be found for all objects. The properties of those stars
with blue-shifted lines are compatible with an origin in a shock-heated
dust-depleted outflow.


title:
Holomorphic maps from rational homogeneous spaces onto projective
  manifolds

abstract:
  Answering a problem raised by Lazarsfeld, Hwang and Mok proved that a
surjective holomorphic map from a rational homogeneous space of Picard number 1
onto projective manifold different from projective space must be a
biholomorphism. THe aim of this paper is to generalized this result to
irreducible rational homogeneous space of higher Picard number.


title:
The Cepheid Period-Luminosity Relation at Mid-Infrared Wavelengths: I.
  First-Epoch LMC Data

abstract:
  We present the first mid-infrared Period-Luminosity (PL) relations for Large
Magellanic Cloud (LMC) Cepheids. Single-epoch observations of 70 Cepheids were
extracted from Spitzer IRAC observations at 3.6, 4.5, 5.8 and 8.0 microns,
serendipitously obtained during the SAGE (Surveying the Agents of a Galaxy's
Evolution) imaging survey of the LMC. All four mid-infrared PL relations have
nearly identical slopes over the period range 6 - 88 days, with a small scatter
of only +/-0.16 mag independent of period for all four of these wavelengths. We
emphasize that differential reddening is not contributing significantly to the
observed scatter, given the nearly two orders of magnitude reduced sensitivity
of the mid-IR to extinction compared to the optical. Future observations,
filling in the light curves for these Cepheids, should noticeably reduce the
residual scatter. These attributes alone suggest that mid-infrared PL relations
will provide a practical means of significantly improving the accuracy of
Cepheid distances to nearby galaxies.


title: Vortex Tubes in Turbulence Velocity Fields at High Reynolds Numbers

abstract:
  The elementary structures of turbulence, i.e., vortex tubes, are studied
using velocity data obtained in laboratory experiments for boundary layers and
duct flows at microscale Reynolds numbers 332-1934. While past experimental
studies focused on intense vortex tubes, the present study focuses on all
vortex tubes with various intensities. We obtain the mean velocity profile. The
radius scales with the Kolmogorov length. The circulation velocity scales with
the Kolmogorov velocity, in contrast to the case of intense vortex tubes alone
where the circulation velocity scales with the rms velocity fluctuation. Since
these scaling laws are independent of the configuration for turbulence
production, they appear to be universal at high Reynolds numbers.


title:
Massive stars exploding in a He-rich circumstellar medium. I. Type Ibn
  (SN 2006jc-like) events

abstract:
  We present new spectroscopic and photometric data of the type Ibn supernovae
2006jc, 2000er and 2002ao. We discuss the general properties of this recently
proposed supernova family, which also includes SN 1999cq. The early-time
monitoring of SN 2000er traces the evolution of this class of objects during
the first few days after the shock breakout. An overall similarity in the
photometric and spectroscopic evolution is found among the members of this
group, which would be unexpected if the energy in these core-collapse events
was dominated by the interaction between supernova ejecta and circumstellar
medium. Type Ibn supernovae appear to be rather normal type Ib/c supernova
explosions which occur within a He-rich circumstellar environment. SNe Ibn are
therefore likely produced by the explosion of Wolf-Rayet progenitors still
embedded in the He-rich material lost by the star in recent mass-loss episodes,
which resemble known luminous blue variable eruptions. The evolved Wolf-Rayet
star could either result from the evolution of a very massive star or be the
more evolved member of a massive binary system. We also suggest that there are
a number of arguments in favour of a type Ibn classification for the historical
SN 1885A (S-Andromedae), previously considered as an anomalous type Ia event
with some resemblance to SN 1991bg.


title:
Massive stars exploding in a He-rich circumstellar medium. II. The
  transitional case of SN 2005la

abstract:
  We present photometric and spectroscopic data of the peculiar SN 2005la, an
object which shows an optical light curve with some luminosity fluctuations and
spectra with comparably strong narrow hydrogen and helium lines, probably of
circumstellar nature. The increasing full-width-half-maximum velocity of these
lines is indicative of an acceleration of the circumstellar material. SN 2005la
exhibits hybrid properties, sharing some similarities with both type IIn
supernovae and 2006jc-like (type Ibn) events. We propose that the progenitor of
SN 2005la was a very young Wolf-Rayet (WN-type) star which experimented mass
ejection episodes shortly before core collapse.


title: Unified geometric description of black hole thermodynamics

abstract:
  In the space of thermodynamic equilibrium states we introduce a Legendre
invariant metric which contains all the information about the thermodynamics of
black holes. The curvature of this thermodynamic metric becomes singular at
those points where, according to the analysis of the heat capacities, phase
transitions occur. This result is valid for the Kerr-Newman black hole and all
its special cases and, therefore, provides a unified description of black hole
phase transitions in terms of curvature singularities.


title:
Grand canonical Gutzwiller approximation for magnetic inhomogeneous
  systems

abstract:
  The Gutzwiller approximation (GA) for Gutzwiller-projected grand canonical
wave functions with fugacity factors is investigated in detail. Our systems in
general contain inhomogeneity and local magnetic moments. In deriving
renormalization formulae, we also derive or estimate terms of higher powers of
intersite contractions neglected in the conventional GA. We examine several
different constraints, i.e., local/global spin-dependent/independent
particle-number conservation. Out of the four, the local spin-dependent
constraint seems the most promising at present. An improved GA derived from it
agrees with the variational Monte Carlo method better than the conventional GA
does. The corrections to the conventional GA can be interpreted as two-site
correlation including the phase difference of configurations. Furthermore,
projected quasi-particle excited states are orthogonal to each other within the
GA. Using these states, spectral weights are calculated. We show that asymmetry
between electron addition and removal spectra can appear by taking into account
the higher powers of the intersite contractions in the case of the d-wave
superconductors and the Fermi sea; the addition is smaller than the removal.
However, the asymmetry is quite weak especially near the Fermi level. In
contrast, projected s-wave superconductors can have the opposite asymmetry
(addition larger than removal) especially near the Fermi level. In addition,
formulae from the other three constraints are also derived, which may be useful
depending on purposes.


title: Testing different stellar mass estimators at 1<z<2

abstract:
  Physical parameters of galaxies (as luminosity, stellar mass, age) are often
derived by means of the model templates which best fit their
spectro-photometric data. We have performed a quantitative test aimed at
exploring the ability of this procedure in recovering the physical parameters
of early-type galaxies at 1<z<2. A wide range of simulated SEDs, reproducing
those of early-type galaxies at 1<z<2 with assigned age and mass, are used to
build mock photometric catalogs with wavelength coverage and photometric
uncertainties similar to those of two topical surveys (i.e. VVDS and GOODS).
The best fitting analysis of the simulated photometric data allows to study the
differences among the recovered parameters and the input ones. Results indicate
that the stellar masses measured by means of optical bands are affected by
larger uncertainties with respect to those obtained from near-IR bands, and
they frequently underestimate the real values. The M/L ratio in the V band
results strongly underestimated, even when derived from the recently proposed
recipe based on rest-frame optical colours (e.g. (B-V)).


title: Formal Desingularization of Surfaces - The Jung Method Revisited -

abstract:
  In this paper we propose the concept of formal desingularizations as a
substitute for the resolution of algebraic varieties. Though a usual resolution
of algebraic varieties provides more information on the structure of
singularities there is evidence that the weaker concept is enough for many
computational purposes. We give a detailed study of the Jung method and show
how it facilitates an efficient computation of formal desingularizations for
projective surfaces over a field of characteristic zero, not necessarily
algebraically closed. The paper includes a generalization of Duval's Theorem on
rational Puiseux parametrizations to the multivariate case and a detailed
description of a system for multivariate algebraic power series computations.


title: Vortex trapping and expulsion in thin-film YBCO strips

abstract:
  A scanning SQUID microscope was used to image vortex trapping as a function
of the magnetic induction during cooling in thin-film YBCO strips for strip
widths W from 2 to 50 um. We found that vortices were excluded from the strips
when the induction Ba was below a critical induction Bc. We present a simple
model for the vortex exclusion process which takes into account the vortex -
antivortex pair production energy as well as the vortex Meissner and
self-energies. This model predicts that the real density n of trapped vortices
is given by n=(Ba-BK)/Phi0 with BK = 1.65Phi0/W^2 and Phi0 = h/2e the
superconducting flux quantum. This prediction is in good agreement with our
experiments on YBCO, as well as with previous experiments on thin-film strips
of niobium. We also report on the positions of the trapped vortices. We found
that at low densities the vortices were trapped in a single row near the
centers of the strips, with the relative intervortex spacing distribution width
decreasing as the vortex density increased, a sign of longitudinal ordering.
The critical induction for two rows forming in the 35 um wide strip was (2.89 +
1.91-0.93)Bc, consistent with a numerical prediction.


title: Le probleme de l'isomorphisme de graphes est dans P

abstract:
  This paper has been withdrawn by the author, due to possible
counter-examples.


title: Grid Integration of Robotic Telescopes

abstract:
  Robotic telescopes and grid technology have made significant progress in
recent years. Both innovations offer important advantages over conventional
technologies, particularly in combination with one another. Here, we introduce
robotic telescopes used by the Astrophysical Institute Potsdam as ideal
instruments for building a robotic telescope network. We also discuss the grid
architecture and protocols facilitating the network integration that is being
developed by the German AstroGrid-D project. Finally, we present three user
interfaces employed for this purpose.


title: Adjoint Computation for Hypersurfaces Using Formal Desingularizations

abstract:
  We show how to use formal desingularizations (defined earlier by the first
author) in order to compute the global sections (also called adjoints) of
twisted pluricanonical sheaves. These sections define maps that play an
important role in the birational classification of schemes.


title:
Astrometric and photometric monitoring of GQ Lup and its sub-stellar
  companion

abstract:
  Neuhaeuser et al. (2005) presented direct imaging evidence for a sub-stellar
companion to the young T Tauri star GQ Lup. Common proper motion was highly
significant, but no orbital motion was detected. Faint luminosity, low gravity,
and a late-M/early-L spectral type indicated that the companion is either a
planet or a brown dwarf. We have monitored GQ Lup and its companion in order to
detect orbital and parallactic motion and variability in its brightness. We
also search for closer and fainter companions. We have taken six more images
with the VLT Adaptive Optics instrument NACO from May 2005 to Feb 2007, always
with the same calibration binary from Hipparcos for both astrometric and
photometric calibration. By adding up all the images taken so far, we search
for additional companions. The position of GQ Lup A and its companion compared
to a nearby non-moving background object varies as expected for parallactic
motion by about one pixel (2 \pi with parallax \pi). We could not find evidence
for variability of the GQ Lup companion in the K-band (standard deviation being
\pm 0.08 mag), which may be due to large error bars. No additional companions
are found with deep imaging. There is now exceedingly high significance for
common proper motion of GQ Lup A and its companion. In addition, we see for the
first time an indication for orbital motion (about 2 to 3 mas/yr decrease in
separation, but no significant change in the position angle), consistent with a
near edge-on or highly eccentric orbit. We measured the parallax for GQ Lup A
to be \pi = 6.4 \pm 1.9 mas (i.e. 156 \pm 50 pc) and for the GQ Lup companion
to be 7.2 \pm 2.1 mas (i.e. 139 \pm 45 pc), both consistent with being in the
Lupus I cloud and bound to each other.


title: A Theory of Scalar Mesons

abstract:
  We discuss the effect of the instanton induced, six-fermion effective
Lagrangian on the decays of the lightest scalar mesons in the
diquark--antidiquark picture. This addition allows for a remarkably good
description of light scalar meson decays. The same effective Lagrangian
produces a mixing of the lightest scalars with the positive parity q-qbar
states. Comparing with previous work where the q-qbar mesons are identified
with the nonet at 1200-1700 MeV, we find that the mixing required to fit the
mass spectrum is in good agreement with the instanton coupling obtained from
light scalar decays. A coherent picture of scalar mesons as a mixture of
tetraquark states (dominating in the lightest mesons) and heavy q-qbar states
(dominating in the heavier mesons) emerges.


title:
Universal Short-Range Repulsion in the Baryon System Originating from
  the Confinement --Approach in String-Junction Model--

abstract:
  We show a way to unifiedly understand the origins of the repulsive core of
baryon-baryon interaction and the universal repulsion of three-baryon
interaction needed to avoid dramatic softening of the equation of state of
neutron stars due to hyperon mixing. For this aim we adopt the string-junction
model which embodies the essential aspects of the confinement in the baryon
system confirmed by recent lattice QCD calculations. Key concept of this study
lies in the recognition that baryonic short-range repulsion appears as the
latent effect implying the energy necessary for full overlap of baryons, for
the confinement to persist at such situation. Numerical results are shown and
related problems are discussed.


title: Relativeca Dopplera efiko inter du akcelataj korpoj - I

abstract:
  We describe the Doppler effect between equally accelerated light source and
observer under the special relativity. The proper accelerations are constant
and parallel. An English version is available by request.
  - - - - - - - - - - -
  Ni priskribas luman Doppleran efikon inter same akcelataj fonto kaj
observanto ^ce special-relativeco. La propraj akceloj estas konstantaj kaj
paralelaj.


title: Liouville type results for periodic and almost periodic linear operators

abstract:
  We are concerned with some extensions of the classical Liouville theorem for
bounded harmonic functions to solutions of more general equations. We deal with
entire solutions of periodic and almost periodic parabolic equations including
the elliptic framework as a particular case. We derive a Liouville type result
for periodic operators as a consequence of a result for operators periodic in
just one variable, which is new even in the elliptic case. More precisely, we
show that if $c\leq0$ and $a_{ij}, b_i, c, f$ are periodic in the same
space/time direction, with the same period, then any bounded solution $u$ of
$$\partial_t
u-a_{ij}(x,t)\partial_{ij}u-b_i(x,t)\partial_iu-c(x,t)u=f(x,t),\quad x\in\R^N,\
t\in\R,$$ is periodic in that direction. We then derive the following Liouville
type result: if $c\leq0, f\equiv0$ and $a_{ij}, b_i, c$ are periodic in all the
space/time variables, with the same periods, then the space of bounded
solutions of the above equation has at most dimension one. In the case of the
equation $\partial_t u-Lu=f(x,t)$, with $L$ periodic elliptic operator
independent of $t$, the hypothesis $c\leq0$ can be weaken by requiring that the
periodic principal eigenvalue of $-L$ is nonnegative. Instead, the periodicity
assumption cannot be relaxed, because we explicitly exhibit an almost periodic
function $b$ such that the space of bounded solutions of $u''+b(x)u'=0$ in $\R$
has dimension 2, and it is generated by the constant solution and a non-almost
periodic solution. Next, a sufficient condition for any bounded solution to be
almost periodicis derived. We also treat the case of periodic domains under
either Dirichlet or Robin boundary conditions.


title: Crossed Andreev reflection in a graphene bipolar transistor

abstract:
  We investigate the crossed Andreev reflections between two graphene leads
connected by a narrow superconductor. When the leads are respectively of the
n-and p- type, we find that electron elastic cotunneling and local Andreev
reflection are both eliminated even in the absence of any valley-isospin or
spin polarizations. We further predict oscillations of both diagonal and cross
conductances as a function of the distance between the graphene-superconductor
interfaces.


title: The Keldysh action of a multi-terminal time-dependent scatterer

abstract:
  We present a derivation of the Keldysh action of a general multi-channel
time-dependent scatterer in the context of the Landauer-B\"uttiker approach.
The action is a convenient building block in the theory of quantum transport.
This action is shown to take a compact form that only involves the scattering
matrix and reservoir Green functions. We derive two special cases of the
general result, one valid when reservoirs are characterized by well-defined
filling factors, the other when the scatterer connects two reservoirs. We
illustrate its use by considering Full Counting Statistics and the Fermi Edge
Singularity.


title: Un-particle Effective Action

abstract:
  We study un-particle dynamics in the framework of standard quantum field
theory. We obtain the Feynman propagator by supplementing standard quantum
field theory definitions with integration over the mass spectrum. Then we use
this information to construct effective actions for scalar, gauge vector and
gravitational un-particles.


title: Ship-induced solitons as a manifestation of critical phenomena

abstract:
  A ship, moving with small acceleration in a reservoir of uniform depth, can
be subjected to a sudden hydrodynamical impact similar to collision with an
underwater rock, and on water surface unusual solitary wave will start running.
The factors responsible for formation of solitons induced by a moving ship are
analyzed. Emphasis is given to a phenomenon observed by John Scott Russell more
170 years ago when a sudden stop of a boat preceded the occurrence of exotic
water dome. In dramatic changes of polemic about the stability and mathematical
description of a solitary wave, the question why "Russell's wave" occurred has
not been raised, though attempts its recreation invariably suffered failure. In
our report the conditions disclosing the principle of the famous event as a
critical phenomenon are described. In a reservoir of uniform depth a ship can
confront by a dynamic barrier within narrow limits of ship's speed and
acceleration. In a wider interval of parameters a ship generates a satellite
wave, which can be transformed in a different-locking soliton. These phenomena
can be classified into an extensive category of dynamic barrier effects
including the transition of aircrafts through the sound barrier.


title:
A general derivation of differential cross section in quark-quark
  scatterings at fixed impact parameter

abstract:
  We propose a general derivation of differential cross section in quark-quark
scatterings at fixed impact parameters. The derivation is well defined and free
of ambiguity in the conventional one. The approach can be applied to a variety
of partonic and hadronic scatterings in low or high energy particle collisions.


title:
Determining the CP parity of Higgs bosons at the LHC in their tau decay
  channels

abstract:
  If neutral Higgs bosons will be discovered at the CERN Large Hadron Collider
(LHC) then an important subsequent issue will be the investigation of their CP
nature. Higgs boson decays into tau lepton pairs are particularly suited in
this respect. Analyzing the three charged pion decay modes of the tau leptons
and taking expected measurement uncertainties at the LHC into account, we show
that the CP properties of a Higgs boson can be pinned down with appropriately
chosen observables, provided that sufficiently large event numbers will
eventually be available.


title:
Star Cluster Formation and Star Formation: The Role of Environment and
  Star Formation Efficiencies

abstract:
  Analyzing global starburst properties in various kinds of starburst and
post-starburst galaxies and relating them to the properties of the star cluster
populations they form, I explore the conditions for the formation of massive,
compact, long-lived star clusters. The aim is to find out whether the relative
amount of star formation that goes into star cluster formation as opposed to
field star formation, and into the formation of massive long-lived clusters in
particular, is universal or scales with star formation rate, burst strength,
star formation efficiency, galaxy or gas mass, and whether or not there are
special conditions or some threshold for the formation of star clusters that
merit to be called globular clusters a few gigayears later.


title:
Dynamics of Annihilation I : Linearized Boltzmann Equation and
  Hydrodynamics

abstract:
  We study the non-equilibrium statistical mechanics of a system of freely
moving particles, in which binary encounters lead either to an elastic
collision or to the disappearance of the pair. Such a system of {\em ballistic
annihilation} therefore constantly looses particles. The dynamics of
perturbations around the free decay regime is investigated from the spectral
properties of the linearized Boltzmann operator, that characterize linear
excitations on all time scales. The linearized Boltzmann equation is solved in
the hydrodynamic limit by a projection technique, which yields the evolution
equations for the relevant coarse-grained fields and expressions for the
transport coefficients. We finally present the results of Molecular Dynamics
simulations that validate the theoretical predictions.


title: X-ray variability of NGC 2516 stars in the XMM-Newton observations

abstract:
  We present the characteristics of the X-ray variability of stars in the
cluster NGC2516 as derived from XMM-Newton/EPIC/pn data. The X-ray variations
on short (hours), medium (months), and long (years) time scales have been
explored. We detected 303 distinct X-ray sources by analysing six EPIC/pn
observations; 194 of them are members of the cluster. Stars of all spectral
types, from the early-types to the late-M dwarfs, were detected. The
Kolmogorov-Smirnov test applied to the X-ray photon time series shows that, on
short time scales, only a relatively small fraction (ranging from 6% to 31% for
dG and dF, respectively) of the members of NGC2516 are variable with a
confidence level $\geq$99%; however, it is possible that the fraction is small
only because of the poor statistics. The time X-ray amplitude distribution
functions (XAD) of a set of dF7-dK2 stars, derived on short (hours) and medium
(months) time scales, seem to suggest that medium-term variations, if present,
have a much smaller amplitude than those on short time scales; a similar result
is also obtained for dK3-dM stars. The amplitude variations of late-type stars
in NGC2516 are consistent with those of the coeval Pleiades stars. Comparing
these data with those of ROSAT/PSPC, collected 7-8 years earlier, and of
ROSAT/HRI, just 4-5 years earlier, we find no evidence of significant
variability on the related time scales, suggesting that long-term variations
due to activity cycles similar to the solar cycle are not common among young
stars. Indications of spectral variability was found in one star whose spectra
at three epochs were available.


title: Consistency of shared reference frames should be reexamined

abstract:
  In a recent Letter [G. Chiribella et al., Phys. Rev. Lett. 98, 120501
(2007)], four protocols were proposed to secretly transmit a reference frame.
Here We point out that in these protocols an eavesdropper can change the
transmitted reference frame without being detected, which means the consistency
of the shared reference frames should be reexamined. The way to check the above
consistency is discussed. It is shown that this problem is quite different from
that in previous protocols of quantum cryptography.


title:
Towards an unifying perspective of the fundamental properties and
  structural principles governing the immune system

abstract:
  In the study of the basic properties observed in the immune system and, in a
broader view, in biological systems, several concepts have already been
mathematically formulated or treated in an analytical perspective, such as
degeneracy, robustness, noise, and bow tie architecture. These properties,
among others, seem to rule many aspects of the system functioning, and share
among themselvesseveral characteristics, intersecting each other, and often
becoming one the indivisible part of the other. According to Kitano, systems
biology needs solid theoretical and methodological foundation of principles and
properties, able to lead towards a unified perspective. An effort in unifying
the formalization and analysis of these principles can be now timely attempted.


title: The optical spectra of the brightest mid-IR-selected galaxies

abstract:
  We present here some of the first results we have obtained on the study of
the optical spectra of Spitzer/MIPS 24 micron-selected galaxies in the
  COSMOS field. This is part of a series of studies we are conducting to
analyse the optical spectral properties of mid-infrared (mid-IR) galaxies with
different
  IR luminosities up to high redshifts. The results shown here correspond to
the brightest S(24 micron)>2 mJy IR galaxy population at z<1.


title:
Recent Advances in the Description of Electromagnetic Two-Nucleon
  Knockout Reactions

abstract:
  Recent advances in the description of electromagnetic two-nucleon knockout
reactions are reviewed. The sensitivity to different types of correlations and
to their treatment in the nuclear wave functions, the effects of final-state
interactions and the role of center-of-mass effects in connection with the
problem of the lack of orthogonality between initial bound states and final
scattering states obtained by the use of an energy-dependent optical-model
potential are discussed. Results are presented for proton-proton and
proton-neutron knockout off 16O also in comparison with the available data.


title: Aspects of Predicative Algebraic Set Theory II: Realizability

abstract:
  This is the second in a series of papers on the relation between algebraic
set theory and predicative formal systems. In part I, we introduced the notion
of a predicative category of small maps and obtained the result that such
categories always contain a model of set theory. In the present paper, we show
that the familiar realizability models of the constructive set theories CZF and
IZF can be obtained as an application of this result. For this purpose, we show
that predicative categories with small maps are closed under an internal notion
of realizability.


title:
Polarization tensor of charged gluons in color magnetic background field
  at finite temperature

abstract:
  We calculate the polarization tensor of charged gluons in a Abelian
homogeneous magnetic background field at finite temperature in one loop order
Lorentz background field gauge in full generality. Thereby we first determine
the ten independent tensor structures. For the calculation of the corresponding
form factors we use the Schwinger representation and represent form factors as
double parametric integrals and a sum resulting from the Matsubara formalism
used. The integrands are given explicitly in terms of hyperbolic trigonometric
functions. Like in the case of neutral gluons, the polarization tensor is not
transversal. Out of the tensor structures, seven are transversal and three are
not. The nontransversal part follows explicitly from our calculations.


title:
A modification of Einstein-Schrodinger theory that contains both general
  relativity and electrodynamics

abstract:
  We modify the Einstein-Schrodinger theory to include a cosmological constant
$\Lambda_z$ which multiplies the symmetric metric, and we show how the theory
can be easily coupled to additional fields. The cosmological constant
$\Lambda_z$ is assumed to be nearly cancelled by Schrodinger's cosmological
constant $\Lambda_b$ which multiplies the nonsymmetric fundamental tensor, such
that the total $\Lambda=\Lambda_z+\Lambda_b$ matches measurement. The resulting
theory becomes exactly Einstein-Maxwell theory in the limit as
$|\Lambda_z|\to\infty$. For $|\Lambda_z|\sim 1/(Planck length)^2$ the field
equations match the ordinary Einstein and Maxwell equations except for extra
terms which are $<10^{-16}$ of the usual terms for worst-case field strengths
and rates-of-change accessible to measurement. Additional fields can be
included in the Lagrangian, and these fields may couple to the symmetric metric
and the electromagnetic vector potential, just as in Einstein-Maxwell theory.
The ordinary Lorentz force equation is obtained by taking the divergence of the
Einstein equations when sources are included. The Einstein-Infeld-Hoffmann
(EIH) equations of motion match the equations of motion for Einstein-Maxwell
theory to Newtonian/Coulombian order, which proves the existence of a Lorentz
force without requiring sources. This fixes a problem of the original
Einstein-Schrodinger theory, which failed to predict a Lorentz force. An exact
charged solution matches the Reissner-Nordstrom solution except for additional
terms which are $\sim 10^{-66}$ of the usual terms for worst-case radii
accessible to measurement. An exact electromagnetic plane-wave solution is
identical to its counterpart in Einstein-Maxwell theory.


title: Monitoring field soil suction using a miniature tensiometer

abstract:
  An experimental device was developed to monitor the field soil suction using
miniature tensiometer. This device consists of a double tube system that
ensures a good contact between the tensiometer and the soil surface at the
bottom of the testing borehole. This system also ensures the tensiometer
periodical retrieving without disturbing the surrounding soil. This device was
used to monitor the soil suction at the site of Boissy-le-Ch\^atel, France. The
measurement was performed at two depths (25 and 45 cm) during two months (May
and June 2004). The recorded suction data are analyzed by comparing with the
volumetric water content data recorded using TDR (Time Domain Reflectometer)
probes as well as the meteorological data. A good agreement between these
results was observed, showing a satisfactory performance of the developed
device.


title: Paraxial Light Beams with Angular Momentum

abstract:
  Fundamental and applied concepts concerning the ability of light beams to
carry a certain mechanical angular momentum with respect to the propagation
axis are reviewed and discussed. Following issues are included:
  Historical reference;
  Angular momentum of a paraxial beam and its constituents;
  Spin angular momentum and paradoxes associated with it;
  Orbital angular momentum;
  Circularly-spiral beams: examples and methods of generation;
  Orbital angular momentum and the intensity moments;
  Symmetry breakdown and decomposition of the orbital angular momentum;
  Mechanical models of the vortex light beams;
  Mechanical action of the beam angular momentum;
  Rotational Doppler effect, its manifestation in the image rotation;
  Spectrum of helical harmonics and associated problems;
  Non-collinear rotational Doppler effect;
  Properties of a beam forcedly rotating around its own axis.
  Research prospects and ways of practical utilization of optical beams with
angular momentum.


title:
Critical mass for a Patlak-Keller-Segel model with degenerate diffusion
  in higher dimensions

abstract:
  This paper is devoted to the analysis of non-negative solutions for a
generalisation of the classical parabolic-elliptic Patlak-Keller-Segel system
with $d\ge3$ and porous medium-like non-linear diffusion. Here, the non-linear
diffusion is chosen in such a way that its scaling and the one of the Poisson
term coincide. We exhibit that the qualitative behaviour of solutions is
decided by the initial mass of the system. Actually, there is a sharp critical
mass $M_c$ such that if $M \in (0,M_c]$ solutions exist globally in time,
whereas there are blowing-up solutions otherwise. We also show the existence of
self-similar solutions for $M \in (0,M_c)$. While characterising the eventual
infinite time blowing-up profile for $M=M_c$, we observe that the long time
asymptotics are much more complicated than in the classical Patlak-Keller-Segel
system in dimension two.


title: Adiabatic waves along interfacial layers near the critical point

abstract:
  Near the critical point, isothermal interfacial zones are investigated
starting from a non-local density of energy. From the equations of motion of
thermocapillary fluids, we point out a new kind of adiabatic waves propagating
along the interfacial layers. The waves are associated with the second
derivatives of densities and propagate with a celerity depending on the
proximity of the critical point.

categories: physics.flu-dyn cond-mat.other math-ph math.MP


title:
Screening in semiconductor nanocrystals: \textit{Ab initio} results and
  Thomas-Fermi theory

abstract:
  A first-principles calculation of the impurity screening in Si and Ge
nanocrystals is presented. We show that isocoric screening gives results in
agreement with both the linear response and the point-charge approximations.
Based on the present ab initio results, and by comparison with previous
calculations, we propose a physical real-space interpretation of the several
contributions to the screening. Combining the Thomas-Fermi theory and simple
electrostatics, we show that it is possible to construct a model screening
function that has the merit of being of simple physical interpretation. The
main point upon which the model is based is that, up to distances of the order
of a bond length from the perturbation, the charge response does not depend on
the nanocrystal size. We show in a very clear way that the link between the
screening at the nanoscale and in the bulk is given by the surface
polarization. A detailed discussion is devoted to the importance of local field
effects in the screening. Our first-principles calculations and the
Thomas-Fermi theory clearly show that in Si and Ge nanocrystals, local field
effects are dominated by surface polarization, which causes a reduction of the
screening in going from the bulk down to the nanoscale. Finally, the model
screening function is compared with recent state-of-the-art ab initio
calculations and tested with impurity activation energies.


title: Surface effects in color superconducting strange-quark matter

abstract:
  Surface effects in strange-quark matter play an important role for certain
observables which have been proposed in order to identify strange stars, and
color superconductivity can strongly modify these effects. We study the surface
of color superconducting strange-quark matter by solving the
Hartree-Fock-Bogoliubov equations for finite systems ("strangelets") within the
MIT bag model, supplemented with a pairing interaction. Due to the bag-model
boundary condition, the strange-quark density is suppressed at the surface.
This leads to a positive surface charge, concentrated in a layer of ~1 fm below
the surface, even in the color-flavor locked (CFL) phase. However, since in the
CFL phase all quarks are paired, this positive charge is compensated by a
negative charge, which turns out to be situated in a layer of a few tens of fm
below the surface, and the total charge of CFL strangelets is zero. We also
study the surface and curvature contributions to the total energy. Due to the
strong pairing, the energy as a function of the mass number is very well
reproduced by a liquid-drop type formula with curvature term.


title: Operators on C_{0}(L,X) whose range does not contain c_{0}

abstract:
  This paper contains the following results: a) Suppose that X is a non-trivial
Banach space and L is a non-empty locally compact Hausdorff space without any
isolated points. Then each linear operator T: C_{0}(L,X)\to C_{0}(L,X), whose
range does not contain C_{00} isomorphically, satisfies the Daugavet equality
||I+T||=1+||T||. b) Let \Gamma be a non-empty set and X, Y be Banach spaces
such that X is reflexive and Y does not contain c_{0} isomorphically. Then any
continuous linear operator T: c_{0}(\Gamma,X)\to Y is weakly compact.


title: Post-Red Supergiants

abstract:
  The yellow hypergiants are found in a stage between the massive Red
Supergiants and the Wolf-Rayet stars. This review addresses current issues
concerning the evolution of massive stars, concentrating on the transitional
post-Red Supergiant phase. Few yellow hypergiants are known and even fewer show
direct evidence for having evolved off the Red Supergiant branch. Indeed, only
two such rare objects with clear evidence for having gone through of a previous
mass losing phase are known, IRC +10420 and HD 179821. We will review their
properties and present recent results employing near-infrared interferometry,
integral field spectroscopy and polarimetry. Finally, their real-time evolution
is discussed.


title: On the global well-posedness for the axisymmetric Euler equations

abstract:
  This paper deals with the global well-posedness of the 3D axisymmetric Euler
equations for initial data lying in critical Besov spaces $B_{p,1}^{1+3/p}$. In
this case the BKM criterion is not known to be valid and to circumvent this
difficulty we use a new decomposition of the vorticity.


title: Functional renormalisation group for two-body scattering

abstract:
  The functional renormalisation group is applied to the effective action for
scattering of two nonrelativistic fermions. The resulting physical effective
action is shown to contain the correct threshold singularity. The corresponding
"bare" action respects Galilean invariance up to second order in momenta.
Beyond that order it contains terms that violate this symmetry and, for the
particular regulator considered, nonanalytic third-order terms. The
corresponding potential can be expanded around a nontrivial fixed point using
the power counting appropriate to a system with large scattering length.


title:
Detecting metal-rich intermediate-age Globular Clusters in NGC 4570
  using K-band photometry

abstract:
  Globular Cluster Systems (GCSs) of most early-type galaxies feature two peaks
in their optical colour distributions. Blue-peak GCs are believed to be old and
metal-poor, whereas the ages, metallicities, and the origin of the red-peak GCs
are still being debated. We obtained deep K-band photometry and combined it
with HST observations in g and z to yield a full SED from optical to
near-infrared. This now allows us to break the age-metallicity degeneracy. We
used our evolutionary synthesis models GALEV for star clusters to compute a
large grid of models with different metallicities and a wide range of ages.
Comparing these models to our observations revealed a large population of
intermediate-age (1-3 Gyr) and metalrich (~ solar metallicity) globular
clusters, that will give us further insights into the formation history of this
galaxy.


title:
Malliavin calculus for difference approximations of multidimensional
  diffusions: truncated local limit theorem

abstract:
  For a difference approximations of multidimensional diffusion, the truncated
local limit theorem is proved. Under very mild conditions on the distribution
of the difference terms, this theorem provides that the transition
probabilities of these approximations, after truncation of some asymptotically
negligible terms, possess a densities that converge uniformly to the transition
probability density for the limiting diffusion and satisfy a uniform
diffusion-type estimates. The proof is based on the new version of the
Malliavin calculus for the product of finite family of measures, that may
contain non-trivial singular components. An applications for uniform estimates
for mixing and convergence rates for difference approximations to SDE's and for
convergence of difference approximations for local times of multidimensional
diffusions are given.


title: A Note on the class of superreflexive almost transitive Banach spaces

abstract:
  The class J of simultaneously almost transitive, uniformly convex and
uniformly smooth Banach spaces is characterized in terms of convex-transitivity
and weak geometry of the norm.


title:
Highlights from the Pierre Auger Obseervatory - the birth of the hybrid
  era

abstract:
  Highlights from the Pierre Auger Observatory are presented. In particular
there is a detailed discussion of of the cosmic ray energy spectrum from 0.3
EeV to 100 EeV and of the mass composition above 1 EeV.


title:
Spectra of symmetric powers of graphs and the Weisfeiler-Lehman
  refinements

abstract:
  The k-th power of a n-vertex graph X is the iterated cartesian product of X
with itself. The k-th symmetric power of X is the quotient graph of certain
subgraph of its k-th power by the natural action of the symmetric group. It is
natural to ask if the spectrum of the k-th power --or the spectrum of the k-th
symmetric power-- is a complete graph invariant for small values of k, for
example, for k=O(1) or k=O(log n). In this paper, we answer this question in
the negative: we prove that if the well known 2k-dimensional Weisfeiler-Lehman
method fails to distinguish two given graphs, then their k-th powers --and
their k-th symmetric powers-- are cospectral. As it is well known, there are
pairs of non-isomorphic n-vertex graphs which are not distinguished by the
k-dim WL method, even for k=Omega(n). In particular, this shows that for each
k, there are pairs of non-isomorphic n-vertex graphs with cospectral k-th
(symmetric) powers.


title:
Decentralized Two-Hop Opportunistic Relaying With Limited Channel State
  Information

abstract:
  A network consisting of $n$ source-destination pairs and $m$ relays is
considered. Focusing on the large system limit (large $n$), the throughput
scaling laws of two-hop relaying protocols are studied for Rayleigh fading
channels. It is shown that, under the practical constraints of single-user
encoding-decoding scheme, and partial channel state information (CSI) at the
transmitters (via integer-value feedback from the receivers), the maximal
throughput scales as $\log n$ even if full relay cooperation is allowed.
Furthermore, a novel decentralized opportunistic relaying scheme with receiver
CSI, partial transmitter CSI, and no relay cooperation, is shown to achieve the
optimal throughput scaling law of $\log n$.


title: Spin-drag relaxation time in one-dimensional spin-polarized Fermi gases

abstract:
  Spin propagation in systems of one-dimensional interacting fermions at finite
temperature is intrinsically diffusive. The spreading rate of a spin packet is
controlled by a transport coefficient termed "spin drag" relaxation time
$\tau_{\rm sd}$. In this paper we present both numerical and analytical
calculations of $\tau_{\rm sd}$ for a two-component spin-polarized cold Fermi
gas trapped inside a tight atomic waveguide. At low temperatures we find an
activation law for $\tau_{\rm sd}$, in agreement with earlier calculations of
Coulomb drag between slightly asymmetric quantum wires, but with a different
and much stronger temperature dependence of the prefactor. Our results provide
a fundamental input for microscopic time-dependent spin-density functional
theory calculations of spin transport in 1D inhomogeneous systems of
interacting fermions.


title: Analysis of the stochastic FitzHugh-Nagumo system

abstract:
  In this paper we study a system of stochastic differential equations with
dissipative nonlinearity which arise in certain neurobiology models. Besides
proving existence, uniqueness and continuous dependence on the initial datum,
we shall be mainly concerned with the asymptotic behaviour of the solution. We
prove the existence of an invariant ergodic measure $\nu$ associated with the
transition semigroup $P_t$; further, we identify its infinitesimal generator in
the space $L^2(H;\nu)$.


title:
Universality of the break-up profile for the KdV equation in the small
  dispersion limit using the Riemann-Hilbert approach

abstract:
  We obtain an asymptotic expansion for the solution of the Cauchy problem for
the Korteweg-de Vries (KdV) equation in the small dispersion limit near the
point of gradient catastrophe (x_c,t_c) for the solution of the dispersionless
equation.
  The sub-leading term in this expansion is described by the smooth solution of
a fourth order ODE, which is a higher order analogue to the Painleve I
equation. This is in accordance with a conjecture of Dubrovin, suggesting that
this is a universal phenomenon for any Hamiltonian perturbation of a hyperbolic
equation. Using the Deift/Zhou steepest descent method applied on the
Riemann-Hilbert problem for the KdV equation, we are able to prove the
asymptotic expansion rigorously in a double scaling limit.


title: Far UV and X-ray observation: a hot view of shell galaxies

abstract:
  Shell galaxies are considered the debris of recent accretion/merging
episodes. Their high frequency in low density environments suggest that such
episodes could drive the secular evolution for at least some fraction of the
early-type galaxy population. We present here the preliminary results of
ultraviolet and X-ray data for a sample of three shell galaxies, namely NGC
474, NGC 7070A and ESO 2400100. The Far UV morphology and photometry are
derived using the observations obtained with the Galaxy Evolution Explorer and
the XMM- Newton Optical Monitor. We aim at investigating the rejuvenation
processes in the stellar population using the UV information as well as at
gaining information about the possible evolution with time of the X-ray
emission due interaction/merging processes.


title: The GALEX UV emission in shell galaxies

abstract:
  Shell galaxies are widely considered the debris of recent accretion/merging
episodes. Their high frequency in low density environment suggests that such
episodes could be among the driver of the early-type galaxy secular evolution.
We present far and near UV (FUV and NUV respectively hereafter) GALEX
photometric properties of a sample of shell galaxies.


title: A class of transversal polymatroids with Gorenstein base ring

abstract:
  In this paper, the principal tool to describe transversal polymatroids with
Gorenstein base ring is polyhedral geometry, especially the $Danilov-Stanley$
theorem for the characterization of canonical module. Also, we compute the
$a-invariant$ and the Hilbert series of base ring associated to this class of
transversal polymatroids.


title: Auger transitions in one-dimensional metals

abstract:
  We present a dynamical theory of the Auger decay in one-dimensional (1D)
metals described by the Tomonaga-Luttinger model. An analytic expression of the
Auger current is derived in the framework of the 1-step approach, where the
finite lifetime of the initial core-hole and the core-valence interaction are
taken into account. This allows to capture typical dynamical features like the
shake-down effect, in which the Auger spectrum shows a non-vanishing weight
above the 2-step high-energy threshold. The obtained results give also a hint
to understand the sizable suppression of Auger spectral weight closed to the
Fermi energy recently observed in carbon nanotubes with respect to graphite.


title: Dissipative Two-Fluid Models

abstract:
  From Hamilton's principle of stationary action, we derive governing equations
of two-fluid mixtures and extend the model to the dissipative case without
chemical reactions. For both conservative and dissipative cases, an algebraic
identity connecting equations of momentum, mass, energy and entropy is obtained
by extending the Gibbs identity in dynamics. The obtained system is hyperbolic
for small relative velocity of the phases.


title:
Dispersive magnetic excitations in the S=1 antiferromagnet
  Ba$_3$Mn$_2$O$_8$

abstract:
  We present powder inelastic neutron scattering measurements of the S=1
dimerized antiferromagnet Ba$_3$Mn$_2$O$_8$. The $T=1.4$ K magnetic spectrum
exhibits a spin-gap of $\Delta \approx 1.0$ meV and a dispersive spectrum with
a bandwidth of approximately 1.5 meV. Comparison to coupled dimer models
describe the dispersion and scattering intensity accurately and determine the
exchange constants in Ba$_3$Mn$_2$O$_8$. The wave vector dependent scattering
intensity confirms the proposed S=1 dimer bond. Temperature dependent
measurements of the magnetic excitations indicate the presence of both
singlet-triplet and thermally activated triplet-quintet excitations.


title:
A new form of governing equations of fluids arising from Hamilton's
  principle

abstract:
  A new form of governing equations is derived from Hamilton's principle of
least action for a constrained Lagrangian, depending on conserved quantities
and their derivatives with respect to the time-space. This form yields
conservation laws both for non-dispersive case (Lagrangian depends only on
conserved quantities) and dispersive case (Lagrangian depends also on their
derivatives). For non-dispersive case the set of conservation laws allows to
rewrite the governing equations in the symmetric form of
Godunov-Friedrichs-Lax. The linear stability of equilibrium states for
potential motions is also studied. In particular, the dispersion relation is
obtained in terms of Hermitian matrices both for non-dispersive and dispersive
case. Some new results are extended to the two-fluid non-dispersive case.


title: Virasoro Algebra and L\"owner-Kufarev Equations

abstract:
  Contour dynamics is a classical subject both in physics and in complex
analysis. We show that the dynamics provided by the L\"owner-Kufarev ODE and
PDE possesses a rigid algebraic structure given by the Virasoro algebra.
Namely, the `positive' Virasoro generators span the holomorphic part of the
complexified vector bundle over the space of univalent functions, smooth on the
boundary. In the covariant formulation they are conserved by the
L\"owner-Kufarev evolution. The `negative' Virasoro generators span the
antiholomorphic part. They contain a conserved term and we give an iterative
method to obtain them based on the Poisson structure of the L\"owner-Kufarev
evolution. The L\"owner-Kufarev PDE provides a distribution of the tangent
bundle of non-normalized univalent functions, which forms the tangent bundle of
normalized ones. It also gives an explicit correspondence between the latter
bundle and the holomorphic eigen space of the complexified Lie algebra of
vector fields on the unit circle. Finally, we give Hamiltonian and Lagrangian
formulations of the motion within the coefficient body in the field of an
elliptic operator constructed by means of Virasoro generators. We also discuss
relations between CFT and SLE.


title: Ferromagnet in a continuously tuneable random field

abstract:
  The Random-Field Ising Model (RFIM) has been extensively studied as a model
system for understanding the effects of disorder in magnets. Since the late
1970s, there has been a particular focus on realizations of the RFIM in
site-diluted antiferromagnets. We observe random-field effects in the dilute
dipole-coupled ferromagnet $\mathrm{LiHo}_x\mathrm{Y}_{1-x}\mathrm{F}_4$. In
the presence of a magnetic field transverse to the Ising axis ($H_t$), the
behavior of $\mathrm{LiHo}_x\mathrm{Y}_{1-x}\mathrm{F}_4$ becomes increasingly
dominated by the influence of random-field terms in the effective Hamiltonian.
This is seen experimentally in the shape of the ferromagentic-paramagnetic
phase boundary and in changes to the critical exponents near the classical
critical point. We find that above the classical critical point the magnetic
susceptibility diverges as $H_t\to0$, and that the susceptibility both above
and below the classical critical point can be collapsed onto a single universal
curve using a modified Curie law which explicitly incorporates random-field
contributions. The discovery of a ferromagnetic realization of the RFIM opens
the door to investigation of the random-field problem with the wide variety of
techniques available for probing ferromagnets, including the ability to examine
both the statics and dynamics of the random-field problem. It also allows
studying the effects of controlled amounts of randomness on the dynamics of
domain pinning and the energetics of domain reversal.


title: The Einstein relation for random walks on graphs

abstract:
  This paper investigates the Einstein relation; the connection between the
volume growth, the resistance growth and the expected time a random walk needs
to leave a ball on a weighted graph. The Einstein relation is proved under
different set of conditions. In the simplest case it is shown under the volume
doubling and time comparison principles. This and the other set of conditions
provide the basic framework for the study of (sub-) diffusive behavior of the
random walks on weighted graphs.


title: Symbiotic gap and semi-gap solitons in Bose-Einstein condensates

abstract:
  Using the variational approximation and numerical simulations, we study
one-dimensional gap solitons in a binary Bose-Einstein condensate trapped in an
optical-lattice potential. We consider the case of inter-species repulsion,
while the intra-species interaction may be either repulsive or attractive.
Several types of gap solitons are found: symmetric or asymmetric; unsplit or
split, if centers of the components coincide or separate; intra-gap (with both
chemical potentials falling into a single bandgap) or inter-gap, otherwise. In
the case of the intra-species attraction, a smooth transition takes place
between solitons in the semi-infinite gap, the ones in the first finite
bandgap, and semi-gap solitons (with one component in a bandgap and the other
in the semi-infinite gap).


title:
Dephasing in the electronic Mach-Zehnder interferometer at filling
  factor 2

abstract:
  We propose a simple physical model which describes dephasing in the
electronic Mach-Zehnder interferometer at filling factor 2. This model explains
very recent experimental results, such as the unusual lobe-type structure in
the visibility of Aharonov-Bohm oscillations, phase rigidity, and the asymmetry
of the visibility as a function of transparencies of quantum point contacts.
According to our model, dephasing in the interferometer originates from strong
Coulomb interaction at the edge of two-dimensional electron gas. The long-range
character of the interaction leads to a separation of the spectrum of edge
excitations on slow and fast mode. These modes are excited by electron
tunneling and carry away the phase information. The new energy scale associated
with the slow mode determines the temperature dependence of the visibility and
the period of its oscillations as a function of voltage bias. Moreover, the
variation of the lobe structure from one experiment to another is explained by
specific charging effects, which are different in all experiments. We propose
to use a strongly asymmetric Mach-Zehnder interferometer with one arm being
much shorter than the other for the spectroscopy of quantum Hall edge states.


title: A Lie-theoretic construction of spherical symplectic reflection algebras

abstract:
  We propose a construction of the spherical subalgebra of a symplectic
reflection algebra of an arbitrary rank corresponding to a star-shaped affine
Dynkin diagram. Namely, it is obtained from the universal enveloping algebra of
a certain semi-simple Lie algebra by the process of quantum Hamiltonian
reduction. As an application, we propose a construction of finite-dimensional
representations of the spherical subalgebra.


title: Bose-Einstein correlations of neutral gauge bosons in $pp$ collisions

abstract:
  The theory for Bose-Einstein correlations in case of neutral gauge bosons in
$pp$ collisions at high energies is presented. Based on quantum field theory at
finite temperature the two-particle Bose-Einstein correlations of neutral gauge
bosons are carried out for the first time. As a result, the important
parameters of the correlation functions can be obtained for the $Z^{0}Z^{0}$
pairs. The correlations of two bosons in 4-momentum space presented in this
paper offer useful and instructive complimentary viewpoints to theoretical and
experimental works in multiparticle femtoscopy and interferometry measurements
at hadron colliders.


title:
Upper bounds for transition probabilities on graphs and isoperimetric
  inequalities

abstract:
  In this paper necessary and sufficient conditions are presented for heat
kernel upper bounds for random walks on weighted graphs. Several equivalent
conditions are given in the form of isoperimetric inequalities.


title:
Detection of non-ordered central gas motions in a sample of four low
  surface brightness galaxies

abstract:
  We present integral-field spectroscopy of the ionized gas in the central
regions of four galaxies with a low surface brightness disk taken with the
Visible Multi Object Spectrograph at the Very Large Telescope and aimed at
testing the accuracy in the determination of the central logarithmic slope
$\alpha$ of the mass density radial profile $\rho(r) \propto r^\alpha$ in this
class of objects. For all the sample galaxies we subtracted from the observed
velocity field the best-fit model of gas in circular motions and derived the
residuals. Only ESO-LV 5340200 is characterized by a regular velocity field. We
extracted the velocity curves of this galaxy along several position angles, in
order to estimate the uncertainty in deriving the central gradient of the total
mass density from long-slit spectroscopy. We report the detection of strong
non-ordered motions of the ionized gas in three out of four sample galaxies.
The deviations have velocity amplitudes and spatial scales that make not
possible to disentangle between cuspy and core density radial profiles.


title: Ultracold bosons in lattices with binary disorder

abstract:
  Quantum phases of ultracold bosons with repulsive interactions in lattices in
the presence of quenched disorder are investigated. The disorder is assumed to
be caused by the interaction of the bosons with impurity atoms having a large
effective mass. The system is described by the Bose-Hubbard Hamiltonian with
random on-site energies which have a discrete binary probability distribution.
The phase diagram at zero temperature is calculated using several methods like
a strong-coupling expansion, an exact numerical diagonalization, and a
Bose-Fermi mapping valid in the hard-core limit. It is shown that the
Mott-insulator phase exists for any strength of disorder in contrast to the
case of continuous probability distribution. We find that the compressibility
of the Bose glass phase varies in a wide range and can be extremely low.
Furthermore, we evaluate experimentally accessible quantities like the momentum
distribution, the static and dynamic structure factors, and the density of
excited states. The influence of finite temperature is discussed as well.


title: CP asymmetries in charged Higgs boson decays in MSSM

abstract:
  In the Standard Model with Minimal Supersymmetry, the Lagrangian contains
complex parameters which lead to additional CP violation. We study CP violating
asymmetries in the decays of the MSSM charged Higgs boson, induced by loop
corrections with intermediate SUSY particles, and perform analytical and
numerical analysis. The decay rate asymmetry can go up to 25% and the
forward-backward asymmetry can reach up to 10%.


title:
On the relationship between the structural and socioacademic communities
  of a coauthorship network

abstract:
  This article presents a study that compares detected structural communities
in a coauthorship network to the socioacademic characteristics of the scholars
that compose the network. The coauthorship network was created from the
bibliographic record of a multi-institution, interdisciplinary research group
focused on the study of sensor networks and wireless communication. Four
different community detection algorithms were employed to assign a structural
community to each scholar in the network: leading eigenvector, walktrap, edge
betweenness and spinglass. Socioacademic characteristics were gathered from the
scholars and include such information as their academic department, academic
affiliation, country of origin, and academic position. A Pearson's $\chi^2$
test, with a simulated Monte Carlo, revealed that structural communities best
represent groupings of individuals working in the same academic department and
at the same institution. A generalization of this result suggests that, even in
interdisciplinary, multi-institutional research groups, coauthorship is
primarily driven by departmental and institutional affiliation.


title:
Systematics of the first 2+ excitation in spherical nuclei with
  Skryme-QRPA

abstract:
  We use the Quasiparticle Random Phase Approximation (QRPA) and the Skyrme
interactions SLy4 and SkM* to systematically calculate energies and transition
strengths for the lowest 2+ state in spherical even-even nuclei.The SkM*
functional, applied to 178 spherical nuclei between Z=10 and 90, produces
excitation energies that are on average 11% higher than experimental values,
with residuals that fluctuate about the average by -35%+55%. The predictions of
SkM* and SLy4 have significant differences, in part because of differences in
the calculated ground state deformations; SkM* performs better in both the
average and dispersion of energies. Comparing the QRPA results with those of
generator-coordinate-method (GCM) calculations, we find that the QRPA
reproduces trends near closed shells better than the GCM, and overpredicts the
energies less severely in general. We attribute part of the difference to a
deficiency in the way the GCM is implemented.


title: On the Minimum Spanning Tree for Directed Graphs with Potential Weights

abstract:
  In general the problem of finding a miminum spanning tree for a weighted
directed graph is difficult but solvable. There are a lot of differences
between problems for directed and undirected graphs, therefore the algorithms
for undirected graphs cannot usually be applied to the directed case. In this
paper we examine the kind of weights such that the problems are equivalent and
a minimum spanning tree of a directed graph may be found by a simple algorithm
for an undirected graph.


title: Scalar field cosmological models with finite scale factor singularities

abstract:
  We construct a scalar field based cosmological model, possessing a
cosmological singularity characterized by a finite value of the cosmological
radius and an infinite scalar curvature. Using the methods of the qualitative
theory of differential equations, we give a complete description of the
cosmological evolutions in the model under consideration. There are four
classes of evolutions, two of which have finite lifetimes, while the other two
undergo an infinite expansion.


title:
Statistics of particle dispersion in Direct Numerical Simulations of
  wall-bounded turbulence: results of an international collaborative benchmark
  test

abstract:
  In this paper, the results of an international collaborative test case
relative to the production of a Direct Numerical Simulation and Lagrangian
Particle Tracking database for turbulent particle dispersion in channel flow at
low Reynolds number are presented. The objective of this test case is to
establish a homogeneous source of data relevant to the general problem of
particle dispersion in wall-bounded turbulence. Different numerical approaches
and computational codes have been used to simulate the particle-laden flow and
calculations have been carried on long enough to achieve a statistically-steady
condition for particle distribution. In such stationary regime, a comprehensive
database including both post-processed statistics and raw data for the fluid
and for the particles has been obtained. The complete datasets can be
downloaded from the web at http://cfd.cineca.it/cfd/repository/. In this paper,
the most relevant velocity statistics (for both phases) and particle
distribution statistics are discussed and benchmarked by direct comparison
between the different numerical predictions.


title:
Estimation of X-ray scattering impact in imaging degradation for the
  SIMBOL-X telescope

abstract:
  The imaging performance of X-ray optics (expressed in terms of HEW,
Half-Energy-Width) can be severely affected by X-ray scattering caused by the
surface roughness of the mirrors. The impact of X-ray scattering has an
increasing relevance for increasing photon energy, and can be the dominant
problem in a hard X-ray telescope like SIMBOL-X. In this work we show how, by
means of a novel formalism, we can derive a surface roughness tolerance - in
terms of its power spectrum - from a specific HEW requirement for the SIMBOL-X
optical module.


title: Random walks on graphs with volume and time doubling

abstract:
  This paper studies the on- and off-diagonal upper estimate and the two-sided
transition probability estimate of random walks on weighted graphs.


title: Galois theory and integral models of Lambda-rings

abstract:
  We show that any Lambda-ring, in the sense of Riemann-Roch theory, which is
finite etale over the rational numbers and has an integral model as a
Lambda-ring is contained in a product of cyclotomic fields. In fact, we show
that the category of them is described in a Galois-theoretic way in terms of
the monoid of pro-finite integers under multiplication and the cyclotomic
character. We also study the maximality of these integral models and give a
more precise, integral version of the result above. These results reveal an
interesting relation between Lambda-rings and class field theory.


title: Dynamical Mean Field Theory equations on nearly real frequency axis

abstract:
  The Iterated Perturbation Theory (IPT) equations of the Dynamical Mean Field
Theory (DMFT) for the half-filled Hubbard model, are solved on nearly real
frequencies at various values of the Hubbard parameters $U$, to investigate the
nature of metal-insulator transition (MIT) at finite temperatures. This method
avoids the instabilities associated with the infamous Pad\'e analytic
continuation and reveals fine structures across the MIT at finite temperatures,
which {\em can not be captured} by conventional methods for solving DMFT
equations on Matsubara frequencies. Our method suggests that at finite
temperatures, there is an abrupt decrease in the height of the quasi-particle
(Kondo) peak at a critical value of $U_c$, to a non-zero but small bump which
gradually suppresses as one moves deeper into the {\em bad} insulator regime.
In contrast to Vollhardt and coworkers [J. Phys. Soc. Jpn. {\bf 74} (2005)
136], down to $T=0.01$ of the half-bandwidth we find no $T^*$ separating bad
insulator from a true Mott insulator.


title: Two metrics for general phylogenetic networks

abstract:
  We prove that Nakhleh's latest dissimilarity measure for phylogenetic
networks separates distinguishable phylogenetic networks, and that a slight
modification of it provides a true distance on the class of all phylogenetic
networks.


title:
Fractional Laplacian phase transitions and boundary reactions: a
  geometric inequality and a symmetry result

abstract:
  We deal with symmetry properties for solutions of nonlocal equations of the
type $(-\Delta)^s v= f(v)\qquad {in $\R^n$,}$ where $s \in (0,1)$ and the
operator $(-\Delta)^s$ is the so-called fractional Laplacian. The study of this
nonlocal equation is made via a careful analysis of the following degenerate
elliptic equation
  ${-div (x^\a \nabla u)=0 \qquad {on $\R^n\times(0,+\infty)$}
  -x^\a u_x = f(u) \qquad {on $\R^n\times\{0\}$} $
  where $\a \in (-1,1)$. This equation is related to the fractional Laplacian
since the Dirichlet-to-Neumann operator $\Gamma_\a: u|_{\partial \R^{n+1}_+}
\mapsto -x^\a u_x |_{\partial \R^{n+1}_+} $ is $(-\Delta)^{\frac{1-\a}{2}}$.
This equation is related to the fractional Laplacian since the
Dirichlet-to-Neumann operator $\Gamma_\a: u|_{\partial \R^{n+1}_+} \mapsto
-x^\a u_x |_{\partial \R^{n+1}_+} $ is $(-\Delta)^{\frac{1-\a}{2}}$. More
generally, we study the so-called boundary reaction equations given by
  ${-div (\mu(x) \nabla u)+g(x,u)=0 {on $\R^n\times(0,+\infty)$}
  - \mu(x) u_x = f(u) {on $\R^n\times{0}$}$
  under some natural assumptions on the diffusion coefficient $\mu$ and on the
nonlinearities $f$ and $g$. We prove a geometric formula of Poincar\'e-type for
stable solutions, from which we derive a symmetry result in the spirit of a
conjecture of De Giorgi.


title:
New insights into the X-ray properties of the nearby barred spiral
  galaxy NGC 1672

abstract:
  We present some preliminary results from new Chandra and XMM-Newton X-ray
observations of the nearby barred spiral galaxy NGC1672. It shows dramatic
nuclear and extra-nuclear star formation activity, including starburst regions
located near each end of its strong bar, both of which host ultraluminous X-ray
sources (ULXs). With the new high-spatial-resolution Chandra imaging, we show
for the first time that NGC1672 possesses a faint ($L(X)~10^39 erg/s), hard
central X-ray source surrounded by an X-ray bright circumnuclear starburst ring
that dominates the X-ray emission in the region. The central source may
represent low-level AGN activity, or alternatively the emission from X-ray
binaries associated with star-formation in the nucleus.


title:
Mapping of dissipative particle dynamics in fluctuating hydrodynamics
  simulations

abstract:
  Dissipative particle dynamics (DPD) is a novel particle method for mesoscale
modeling of complex fluids. DPD particles are often thought to represent
packets of real atoms, and the physical scale probed in DPD models are
determined by the mapping of DPD variables to the corresponding physical
quantities. However, the non-uniqueness of such mapping has led to difficulties
in setting up simulations to mimic real systems and in interpreting results.
For modeling transport phenomena where thermal fluctuations are important
(e.g., fluctuating hydrodynamics), an area particularly suited for DPD method,
we propose that DPD fluid particles should be viewed as only 1) to provide a
medium in which the momentum and energy are transferred according to the
hydrodynamic laws and 2) to provide objects immersed in the DPD fluids the
proper random "kicks" such that these objects exhibit correct fluctuation
behaviors at the macroscopic scale. We show that, in such a case, the choice of
system temperature and mapping of DPD scales to physical scales are uniquely
determined by the level of coarse-graining and properties of DPD fluids. We
also verified that DPD simulation can reproduce the macroscopic effects of
thermal fluctuation in particulate suspension by showing that the Brownian
diffusion of solid particles can be computed in DPD simulations with good
accuracy.


title: Spontaneous emission of an atom near a wedge

abstract:
  It is a well known fact that non-trivial boundary conditions affect the
interaction between atoms and the always present quantized electromagnetic
field. In this paper, we focus on how the spontaneous emission rate of a given
excited atom is altered when placed inside a perfectly conducting wedge. We
begin by briefly presenting the formalism on which our calculations are
founded, proceeding then to a long but straightforward calculation of the
transition rate. We present results for a general atom but, for the sake of
simplicity, we narrow them down to an effective two-level system in our
numerical investigations. From these we conclude that the results are
physically sound.


title:
High-Yield of Memory Elements from Carbon Nanotube Field-Effect
  Transistors with Atomic Layer Deposited Gate Dielectric

abstract:
  Carbon nanotube field-effect transistors (CNT FETs) have been proposed as
possible building blocks for future nano-electronics. But a challenge with CNT
FETs is that they appear to randomly display varying amounts of hysteresis in
their transfer characteristics. The hysteresis is often attributed to charge
trapping in the dielectric layer between the nanotube and the gate. This study
includes 94 CNT FET samples, providing an unprecedented basis for statistics on
the hysteresis seen in five different CNT-gate configurations. We find that the
memory effect can be controlled by carefully designing the gate dielectric in
nm-thin layers. By using atomic layer depositions (ALD) of HfO$_{2}$ and
TiO$_{2}$ in a triple-layer configuration, we achieve the first CNT FETs with
consistent and narrowly distributed memory effects in their transfer
characteristics.


title:
Subsystem stabilizer codes cannot have a universal set of transversal
  gates for even one encoded qudit

abstract:
  A long-standing open problem in fault-tolerant quantum computation has been
to find a universal set of transversal gates. As three of us proved in arXiv:
0706.1382, such a set does not exist for binary stabilizer codes. Here we
generalize our work to show that for subsystem stabilizer codes in $d$
dimensional Hilbert space, such a universal set of transversal gates cannot
exist for even one encoded qudit, for any dimension $d$, prime or nonprime.
This result strongly supports the idea that other primitives, such as quantum
teleportation, are necessary for universal fault-tolerant quantum computation,
and may be an important factor for fault tolerance noise thresholds.


title: Neutral scalar Higgs bosons in the USSM at the LHC

abstract:
  We study the possibility of discovering neutral scalar Higgs bosons in the
$U(1)'$-extended supersymmetric standard model (USSM) at the CERN Large Hadron
Collider (LHC), by examining their productions via the exotic quark loop in the
gluon fusion process at leading order. It is possible in some parameter region
that the neutral scalar Higgs bosons may have stronger couplings with the
exotic quarks than with top quark. In this case, the exotic quarks may
contribute more significantly than top quark in productions of the neutral
scalar Higgs bosons in the gluon fusion process. We find that there is indeed
some parameter region in the USSM that supports our speculations.


title: Numeric modeling of fire suppression by organophosphorous inhibitors

abstract:
  Numerical calculations of the effect of organophosphorous inhibitor
(CF3CH2O)3P and its mixtures with carbon dioxide on propane flames are carried
out using the three dimensional Reynolds-averaged Navier-Stokes (RANS)
equations in the low Mach number approximation. The k-e model of turbulence,
the EDC combustion model and the weighted-sum-of-gray-gases model of radiation
are used. The Westbrook global-kinetic scheme with fractional order of reaction
was used for the calculation of chemical reaction rate of propane combustion.
The empirical expression for the correction factor for the chemical reaction
rate was used to model the effect of organophosphorous inhibitor no the
reaction. Two series of test calculations for different values of the
correction factor are carried out. Dependences of the minimum extinguishing
concentration of the inhibitor per carbon dioxide volume concentration in the
extinguishing mixtures were obtained. The results of test calculations are
shown to agree reasonably with the experimental data. A calculation of the
compartment fire extinguishment was carried out using the result of test
calculations. Temperature and inhibitor volume concentration fields at the
moment of fire extinguishment are obtained. The results of calculation are used
to find out the optimum position of the extinguish mixture source.


title: Half-Metallic L2$_1$ Structures with (001) Planar Insertions

abstract:
  A number of L2$_1$ phase alloys (composition X$_2$YZ) are half-metallic.
Although this structure is typically described in terms of an fcc Bravais
lattice with a 4 atom basis, it can be viewed more simply as a variant of bcc
or B2 in which planes of X$_2$ alternate with planes of YZ along the 001
direction. Using ab-initio electronic structure calculations, we have
investigated planar insertions along 001 into the L2$_1$ structure. For most
scenarios, insertion of single or double atomic layers of Cr into Co$_2$MnGe or
Co$_2$MnSi did not destroy the half-metallic property. One insertion of a Cr
layer into Co$_2$MnGe was observed to increase the gap. In fact, we observed
that for a large number of insertions using various transition metals or
combinations of transition metals and non-transition metals, the band gap in
the minority channel at the Fermi energy remains. An ad hoc rule that seems to
partially capture the tendency to form half-metals can be formulated as: "001
planar insertions that can plausibly yield 8 down spin electrons on the X$_2$
layer and 4 down spin electrons on the YZ layer yield half-metals".


title:
Bright solitary waves in a Bose-Einstein condensate and their
  interactions

abstract:
  We examine the dynamics of two bright solitary waves with a negative
nonlinear term. The observed repulsion between two solitary waves -- when these
are in an antisymmetric combination -- is attributed to conservation laws.
Slight breaking of parity, in combination with weak relaxation of energy, leads
the two solitary waves to merge. The effective repulsion between solitary waves
requires certain nearly ideal conditions and is thus fragile.