title: Cosmic string formation by flux trapping

abstract:
  We study the formation of cosmic strings by confining a stochastic magnetic
field into flux tubes in a numerical simulation. We use overdamped evolution in
a potential that is minimized when the flux through each face in the simulation
lattice is a multiple of the fundamental flux quantum. When the typical number
of flux quanta through a correlation-length-sized region is initially about 1,
we find a string network similar to that generated by the Kibble-Zurek
mechanism. With larger initial flux, the loop distribution and the Brownian
shape of the infinite strings remain unchanged, but the fraction of length in
infinite strings is increased. A 2D slice of the network exhibits bundles of
strings pointing in the same direction, as in earlier 2D simulations. We find,
however, that strings belonging to the same bundle do not stay together in 3D
for much longer than the correlation length. As the initial flux per
correlation length is decreased, there is a point at which infinite strings
disappear, as in the Hagedorn transition.

categories: hep-th astro-ph cond-mat.supr-con hep-ph


title: The Origin of the Magellanic Stream and Its Leading Arm

abstract:
  We explore the Magellanic Stream (MS) using a Gaussian decomposition of the
HI velocity profiles in the Leiden-Argentine-Bonn (LAB) all-sky HI survey. This
decomposition exposes the MS to be composed of two filaments distinct both
spatially (as first pointed out by Putman et al.) and in velocity. Using the
velocity coherence of the filaments, one can be traced back to its origin in
what we identify as the SouthEast HI Overdensity (SEHO) of the Large Magellanic
Cloud (LMC), which includes 30 Doradus. Parts of the Leading Arm (LA) can also
be traced back to the SEHO in velocity and position. Therefore, at least
one-half of the trailing Stream and most of the LA originates in the LMC,
contrary to previous assertions that both the MS and the LA originate in the
Small Magellanic Cloud (SMC) and/or in the Magellanic Bridge. The two MS
filaments show strong periodic, undulating spatial and velocity patterns that
we speculate are an imprint of the LMC rotation curve. If true, then the drift
rate of the Stream gas away from the Magellanic Clouds is ~49 km/s and the age
of the MS is ~1.74 Gyr. The Staveley-Smith et al. high-resolution HI data of
the LMC show gas outflows from supergiant shells in the SEHO that seem to be
creating the LA and LMC filament of the MS. Blowout of LMC gas is an effect not
previously accounted for but one that probably plays an important role in
creating the MS and LA.


title: Integrable systems and complex geometry

abstract:
  In this paper, we discuss an interaction between complex geometry and
integrable systems. Section 1 reviews the classical results on integrable
systems. New examples of integrable systems, which have been discovered, are
based on the Lax representation of the equations of motion. These systems can
be realized as straight line motions on a Jacobi variety of a so-called
spectral curve. In section 2, we study a Lie algebra theoretical method leading
to integrable systems and we apply the method to several problems. In section
3, we discuss the concept of the algebraic complete integrability (a.c.i.) of
hamiltonian systems. Algebraic integrability means that the system is
completely integrable in the sens of the phase space being folited by tori,
which in addition are real parts of a complex algebraic tori (abelian
varieties). The method is devoted to illustrate how to decide about the a.c.i.
of hamiltonian systems and is applied to some examples. Finally, in section 4
we study an a.c.i. in the generalized sense which appears as covering of a.c.i.
system. The manifold invariant by the complex flow is covering of abelian
variety.


title:
Empirical Photometric Redshifts of Luminous Red Galaxies and Clusters in
  SDSS

abstract:
  In this work I discuss the necessary steps for deriving photometric redshifts
for luminous red galaxies (LRGs) and galaxy clusters through simple empirical
methods. The data used is from the Sloan Digital Sky Survey (SDSS). I show that
with three bands only ({\it gri}) it is possible to achieve results as accurate
as the ones obtained by other techniques, generally based on more filters. In
particular, the use of the $(g-i)$ color helps improving the final redshifts
(especially for clusters), as this color monotonically increases up to $z \sim
0.8$. For the LRGs I generate a catalog of $\sim 1.5$ million objects at $z <
0.70$. The accuracy of this catalog is $\sigma = 0.027$ for $z \le 0.55$ and
$\sigma = 0.049$ for $0.55 < z \le 0.70$. The photometric redshift technique
employed for clusters is independent of a cluster selection algorithm. Thus, it
can be applied to systems selected by any method or wavelength, as long as the
proper optical photometry is available. When comparing the redshift listed in
literature to the photometric estimate, the accuracy achieved for clusters is
$\sigma = 0.024$ for $z \le 0.30$ and $\sigma = 0.037$ for $030 < z \le 0.55$.
However, when considering the spectroscopic redshift as the mean value of SDSS
galaxies on each cluster region, the accuracy is at the same level as found by
other authors: $\sigma = 0.011$ for $z \le 0.30$ and $\sigma = 0.016$ for $030
< z \le 0.55$. The photometric redshift relation derived here is applied to
thousands of cluster candidates selected elsewhere. I have also used galaxy
photometric redshifts available in SDSS to identify groups in redshift space
and then compare the redshift peak of the nearest group to each cluster
redshift (ABRIDGED).


title: Examples of Non-Rigid CAT(0) Groups from the Category of Knot Groups

abstract:
  C Croke and B Kleiner have constructed an example of a CAT(0) group with more
than one visual boundary. J Wilson has proven that this same group has
uncountably many distinct boundaries. In this article we prove that the knot
group of any connected sum of two non-trivial torus knots also has uncountably
many distinct CAT(0) boundaries.


title:
Cavity Enhanced Optical Vernier Spectroscopy, Broad Band, High
  Resolution, High Sensitivity

abstract:
  A femtosecond frequency comb provides a vast number of equidistantly spaced
narrow band laser modes that can be simultaneously tuned and frequency
calibrated with 15 digits accuracy. Our Vernier spectrometer utilizes all of
theses modes in a massively parallel manner to rapidly record both absorption
and dispersion spectra with a sensitivity that is provided by a high finesse
broad band optical resonator and a resolution that is only limited by the
frequency comb line width while keeping the required setup simple.


title:
Evidence for Distinct Components of the Galactic Stellar Halo from 838
  RR Lyrae Stars Discovered in the LONEOS-I Survey

abstract:
  We present 838 ab-type RR Lyrae stars from the Lowell Observatory Near Earth
Objects Survey Phase I (LONEOS-I). These objects cover 1430 deg^2 and span
distances ranging from 3-30 kpc from the Galactic Center. Object selection is
based on phased, photometric data with 28-50 epochs. We use this large sample
to explore the bulk properties of the stellar halo, including the spatial
distribution. The period-amplitude distribution of this sample shows that the
majority of these RR Lyrae stars resemble Oosterhoff type I, but there is a
significant fraction (26 %) which have longer periods and appear to be
Oosterhoff type II. We find that the radial distributions of these two
populations have significantly different profiles (rho_{OoI} ~ R^(-2.26 +-
0.07) and rho_{OoII} ~ R^(-2.88 +- 0.11). This suggests that the stellar halo
was formed by at least two distinct accretion processes and supports dual-halo
models.


title: On the theory of flat spacetime

abstract:
  Special relativity turns out to be more than coordinate transformations in
which the constancy of the speed of light plays the central role between two
inertial reference frames. Special relativity, in essence, is a theory of
four-dimensional flat spacetime. Euclidian space spans three of the spacetime's
dimensions and time spans the fourth. Properties of light may not be needed to
describe spacetime, which exists independently of light. The article shows that
a theory of spacetime can be constructed from a geometric viewpoint in which
the speed of light does not play any role. Moreover postulating
four-dimensional geometry significantly simplifies the concept of special
relativity.


title:
A method for the resolution of the Jacobi equation Y''+RY = 0 on the
  manifold Sp(2)/SU(2)

abstract:
  In this paper a method for the resolution of the differential equation of the
Jacobi vector fields in the manifold V1 = Sp(2)/SU(2) is exposed. These results
are applied to determine areas and volumes of geodesic spheres and balls.


title:
21-cm synthesis observations of VIRGOHI 21 - a possible dark galaxy in
  the Virgo Cluster

abstract:
  Many observations indicate that dark matter dominates the extra-galactic
Universe, yet no totally dark structure of galactic proportions has ever been
convincingly identified. Previously we have suggested that VIRGOHI 21, a 21-cm
source we found in the Virgo Cluster using Jodrell Bank, was a possible dark
galaxy because of its broad line-width (~200 km/s) unaccompanied by any visible
gravitational source to account for it. We have now imaged VIRGOHI 21 in the
neutral-hydrogen line and find what could be a dark, edge-on, spinning disk
with the mass and diameter of a typical spiral galaxy. Moreover, VIRGOHI 21 has
unquestionably been involved in an interaction with NGC 4254, a luminous spiral
with an odd one-armed morphology, but lacking the massive interactor normally
linked with such a feature. Numerical models of NGC 4254 call for a close
interaction ~10^8 years ago with a perturber of ~10^11 solar masses. This we
take as additional evidence for the massive nature of VIRGOHI 21 as there does
not appear to be any other viable candidate. We have also used the Hubble Space
Telescope to search for stars associated with the HI and find none down to an I
band surface brightness limit of 31.1 +/- 0.2 mag/sq. arcsec.


title: Resonances of the Quantum $\delta$-Kicked Accelerator

abstract:
  We report the observation of high order resonances of the quantum
$\delta$-kicked accelerator using a BEC kicked by a standing wave of light. The
signature of these resonances is the existence of quantum accelerator modes.
For the first time quantum accelerator modes were seen near 1/4 and 1/3 of the
Talbot time. Using a BEC enabled us to study the detailed structure of the
modes and resonances which are related to the fractional Talbot effect. We
present a general theory for this system and apply it to predict the behavior
of the accelerator modes.


title: Detection of Gauss-Markov Random Fields with Nearest-Neighbor Dependency

abstract:
  The problem of hypothesis testing against independence for a Gauss-Markov
random field (GMRF) is analyzed. Assuming an acyclic dependency graph, an
expression for the log-likelihood ratio of detection is derived. Assuming
random placement of nodes over a large region according to the Poisson or
uniform distribution and nearest-neighbor dependency graph, the error exponent
of the Neyman-Pearson detector is derived using large-deviations theory. The
error exponent is expressed as a dependency-graph functional and the limit is
evaluated through a special law of large numbers for stabilizing graph
functionals. The exponent is analyzed for different values of the variance
ratio and correlation. It is found that a more correlated GMRF has a higher
exponent at low values of the variance ratio whereas the situation is reversed
at high values of the variance ratio.


title: Quasiparticle Energies and Band Gaps of Graphene Nanoribbons

abstract:
  We present calculations of the quasiparticle energies and band gaps of
graphene nanoribbons (GNRs) carried out using a first-principles many-electron
Green's function approach within the GW approximation. Because of the
quasi-one-dimension nature of a GNR, electron-electron interaction effects due
to the enhanced screened Coulomb interaction and confinement geometry greatly
influence the quasiparticle band gap. Compared with previous tight-binding and
density functional theory studies, our calculated quasiparticle band gaps show
significant self-energy corrections for both armchair and zigzag GNRs, in the
range of 0.5-3.0 eV for ribbons of width 2.4-0.4 nm. The quasiparticle band
gaps found here suggest that use of GNRs for electronic device components in
ambient conditions may be viable.


title:
Kolmogorov condition near hyperbolic singularities of integrable
  Hamiltonian systems

abstract:
  In this paper we show that, if an integrable Hamiltonian system admits a
nondegenerate hyperbolic singularity then it will satisfy the Kolmogorov
condegeneracy condition near that singularity (under a mild additional
condition, which is trivial if the singularity contains a fixed point)


title: Hard diffraction and the Color Glass Condensate

abstract:
  Following the Good-and-Walker picture, hard diffraction in the
high-energy/small-x limit of QCD can be described in terms of eigenstates of
the scattering matrix off a Color Glass Condensate. From the CGC non-linear
evolution equations, it is then possible to derive the behavior of diffractive
cross-sections at small $x.$ I discuss recent results, in particular the
consequences of the inclusion of Pomeron loops in the evolution.


title:
A novel method for the evaluation of uncertainty in dose volume
  histogram computation

abstract:
  Dose volume histograms are a useful tool in state-of-the-art radiotherapy
planning, and it is essential to be aware of their limitations. Dose
distributions computed by treatment planning systems are affected by several
sources of uncertainty such as algorithm limitations, measurement uncertainty
in the data used to model the beam and residual differences between measured
and computed dose, once the model is optimized. In order to take into account
the effect of uncertainty, a probabilistic approach is proposed and a new kind
of histogram, a dose-expected volume histogram, is introduced. The expected
value of the volume in the region of interest receiving an absorbed dose equal
or greater than a certain value is found using the probability distribution of
the dose at each point. A rectangular probability distribution is assumed for
this point dose, and a relationship is given for practical computations. This
method is applied to a set of dose volume histograms for different regions of
interest for 6 brain patients, 8 lung patients, 8 pelvis patients and 6
prostate patients planned for IMRT. These results show how dose computation
uncertainty has effects on PTV coverage and, to a lesser extent, in dose to
organs at risk. This method allows to quantify these effects.


title:
Groups of galaxies in the SDSS Data Release 5. A group-finder and a
  catalogue

abstract:
  We extract groups of galaxies from the SDSS Data Release 5 with the purpose
of studying the supercluster-void network and environmental properties of
groups therein. We use a modified friends-of-friends (FoF) method with adopted
variable linking length in transverse and radial direction to eliminate
selection effects and to find reliably as many groups as possible to track the
supercluster network. We take into account various selection effects due to the
use of a magnitude limited sample. To determine linking length scaling we study
the luminosity-density relation in observed groups. We follow the changes in
group sizes and mean galaxy number densities within groups when shifting nearby
groups to larger distances. As a result we show that the linking length should
be a slowly growing function with distance. Our final sample contains 17143
groups in the equatorial, and 33219 groups in the northern part of the DR5
survey with membership N_g >= 2. The group catalogue is available at our
web-site http://www.obs.ee/~erik/index.html.
  Due to a narrow magnitude window in the SDSS the group catalogue based on
this survey has been obtained by moderately growing linking length scaling law
up to redshift z = 0.12. Above this redshift the scaling law turns down. In the
redshift range z=0.12 - 0.2 only the cores are detected. Along with applying
weights when calculating luminosities it is possible to use groups for
determination of the large-scale luminosity-density field.


title: A uniform Sobolev inequality under Ricci flow

abstract:
  Let ${\bf M}$ be a compact Riemannian manifold and the metrics $g=g(t)$
evolve by the Ricci flow. We prove the following result. The Sobolev imbedding
by Aubin or Hebey, perturbed by a scalar curvature term and modulo sharpness of
constants, holds uniformly for $({\bf M}, g(t))$ for all time if the Ricci flow
exists for all time; and if the Ricci flow develops a singularity in finite
time, then the same Sobolev imbedding holds uniformly after a standard
normalization. As a consequence, long time non-collapsing results are derived,
which improve Perelman's local non-collapsing results. An application to 3-d
Ricci flow with surgery is also presented.


title:
Correlations between X-ray Spectral and Timing Characteristics in Cyg
  X-2

abstract:
  Correlations between the quasi-periodic oscillations (QPOs) and the spectral
power-law index have been reported for a number of black hole candidate sources
and for four neutron star (NS) sources, 4U 0614+09, 4U 1608-52, 4U 1728-34 and
Sco X-1. An examination of QPO frequencies and index relationship in Cyg X-2 is
reported herein. The RXTE spectrum of Cyg X-2 can be adequately represented by
a simple two-component model of Compton up-scattering with a soft photon
electron temperature of about 0.7 keV and an iron K-line. Inferred spectral
power-law index shows correlation with the low QPO frequencies. We find that
the Thomson optical depth of the Compton cloud (CC) tau, in framework of
spherical geometry, is in the range of ~4-6, which is consistent with the
neutron star's surface being obscured. The NS high frequency pulsations are
presumably suppressed as a result of photon scattering off CC electrons because
of such high values of tau. We also point out a number of similarities in terms
timing (presence of low and high frequency QPOs) and spectral (high CC optical
depth and low CC plasma temperature) appearances between Cyg X-2 and Sco X-1.


title: Large-Scale Structure of Short-Lived Lyman\alpha Emitters

abstract:
  Recently discovered large-scale structure of Ly\alpha Emitters (LAEs) raises
a novel challenge to the cold dark matter (CDM) cosmology. The structure is
extended over more than 50 Mpc at redshift z=3.1, and exhibits a considerably
weak angular correlation. Such properties of LAE distributions appear to be
incompatible with the standard biased galaxy formation scenario in the CDM
cosmology. In this paper, by considering the possibility that LAEs are
short-lived events, we attempt to build up the picture of LAEs concordant with
the CDM cosmology. We find that if the lifetime of LAEs is as short as (6.7 \pm
0.6) \times 10^7 yr, the distributions of simulated galaxies successfully match
the extension and morphology of large-scale structure of LAEs at z=3.1, and
also the weak angular correlation function. This result implies that LAEs at
z=3.1 do not necessarily reside in high density peaks, but tends to be located
in less dense regions, in a different way from the expectation by the standard
biased galaxy formation scenario. In addition, we make a prediction for the
angular correlation function of LAEs at redshifts higher than 3. It is found
that the prediction deviates from that by the standard biased galaxy formation
scenario even at redshifts 4 < z < 6.


title: Graphene Spin Transistor

abstract:
  Graphitic nanostructures, e.g. carbon nanotubes (CNT) and graphene, have been
proposed as ideal materials for spin conduction[1-7]; they have long electronic
mean free paths[8] and small spin-orbit coupling[9], hence are expected to have
very long spin-scattering times. In addition, spin injection and detection in
graphene opens new opportunities to study exotic electronic states such as the
quantum Hall[10,11] and quantum spin Hall[9] states, and spin-polarized edge
states[12] in graphene ribbons. Here we perform the first non-local four-probe
experiments[13] on graphene contacted by ferromagnetic Permalloy electrodes. We
observe sharp switching and often sign-reversal of the non-local resistance at
the coercive field of the electrodes, indicating definitively the presence of a
spin current between injector and detector. The non-local resistance changes
magnitude and sign quasi-periodically with back-gate voltage, and
Fabry-Perot-like oscillations[6,14,15] are observed, consistent with
quantum-coherent transport. The non-local resistance signal can be observed up
to at least T = 300 K.


title: Bounds on the multipartite entanglement of superpositions

abstract:
  We derive the lower and upper bounds on the entanglement of a given
multipartite superposition state in terms of the entanglement of the states
being superposed. The first entanglement measure we use is the geometric
measure, and the second is the q-squashed entanglement. These bounds allow us
to estimate the amount of the multipartite entanglement of superpositions. We
also show that two states of high fidelity to one another do not necessarily
have nearly the same q-squashed entanglement.


title:
Thermodynamic Interpretation of the Field Equations of BTZ Charged Black
  Hole near the Horizon

abstract:
  As is already known, a spacetime horizon acts like a boundary of a thermal
system an we can associate with it notions as temperature and entropy.
Following the work of M. Akbar, in this paper we will show how it is possible
to interpret the field equation of a charged BTZ black hole near horizon as a
thermodynamic identity dE=TdS+PdA+PhidQ, where Phi is the electric potential
and Q is the electric charge of BTZ black hole. These results indicate that the
field equations for the charged BTZ black hole possess intrinsic thermodynamic
properties near horizon.


title:
Measurement of the production of charged pions by protons on a tantalum
  target

abstract:
  A measurement of the double-differential cross-section for the production of
charged pions in proton--tantalum collisions emitted at large angles from the
incoming beam direction is presented. The data were taken in 2002 with the HARP
detector in the T9 beam line of the CERN PS. The pions were produced by proton
beams in a momentum range from 3 \GeVc to 12 \GeVc hitting a tantalum target
with a thickness of 5% of a nuclear interaction length. The angular and
momentum range covered by the experiment ($100 \MeVc \le p < 800 \MeVc$ and
$0.35 \rad \le \theta <2.15 \rad$) is of particular importance for the design
of a neutrino factory. The produced particles were detected using a
small-radius cylindrical time projection chamber (TPC) placed in a solenoidal
magnet. Track recognition, momentum determination and particle identification
were all performed based on the measurements made with the TPC. An elaborate
system of detectors in the beam line ensured the identification of the incident
particles. Results are shown for the double-differential cross-sections
${{\mathrm{d}^2 \sigma}} / {{\mathrm{d}p\mathrm{d}\theta}}$ at four incident
proton beam momenta (3 \GeVc, 5 \GeVc, 8 \GeVc and 12 \GeVc). In addition, the
pion yields within the acceptance of typical neutrino factory designs are shown
as a function of beam momentum. The measurement of these yields within a single
experiment eliminates most systematic errors in the comparison between rates at
different beam momenta and between positive and negative pion production.


title:
Discovery of 11 New T Dwarfs in the Two Micron All-Sky Survey, Including
  a Possible L/T Transition Binary

abstract:
  We present the discovery of 11 new T dwarfs, found during the course of a
photometric survey for mid-to-late T dwarfs in the 2MASS Point Source Catalog
and from a proper motion selected sample of ultracool dwarfs in the 2MASS
Working Database. Using the NASA Infrared Telescope Facility SpeX spectrograph,
we obtained low-resolution (R~150) spectroscopy, allowing us to derive
near-infrared spectral types of T2-T8. One of these new T dwarfs, 2MASS
J13243559+6358284, was also discovered independently by Metchev et al., in
prep. This object is spectroscopically peculiar and possibly a binary and/or
very young (<300 Myr). We specifically attempted to model the spectrum of this
source as a composite binary to reproduce its peculiar spectral
characteristics. The latest-type object in our sample is a T8 dwarf, 2MASS
J07290002-3954043, now one of the four latest-type T dwarfs known. All 11 T
dwarfs are nearby given their spectrophotometric distance estimates, with 1 T
dwarf within 10 pc and 8 additional T dwarfs within 25 pc, if single. These new
additions increase the 25 pc census of T dwarfs by ~14%. Their proximity offers
an excellent opportunity to probe for companions at closer separations than are
possible for more distant T dwarfs.


title: The vanishing of the contact invariant in the presence of torsion

abstract:
  We prove that the Ozsvath-Szabo contact invariant of a closed contact
3-manifold with positive Giroux torsion vanishes.


title: Solutions of Bethe-Salpter equations in QED3

abstract:
  To understand the mechanism of the fermion pair and fermion-antifermion pair
condensation,the solutions of Bethe-Salpeter equation in QED$_{3}$ is
examined.In the ladder appoximation our solution for the axial-scalar is
consistent with Ward-Takahashi-identity for the axial vector currents.Since the
massless scalar-vector sector is described by a coupled integral equation,it is
difficult to solve explicitly.We approximate the equation for large and small
momentum region separately and convert them into differential equations in
position space.These equation can be solved easily.Boundary condition at the
origin leads the eigenvalue for dimensionless coupling constant
$\lambda=e^{2}/m$.There exists solutions for massless scalar-vector
fermion-antifermion (fa) system with discrete spectrum. In our approximation
massless-scalar-vector ff systemes does not seem to exist.


title: Renormalized Newtonian Cosmic Evolution with Primordial Non-Gaussianity

abstract:
  We study Newtonian cosmological perturbation theory from a field theoretical
point of view. We derive a path integral representation for the cosmological
evolution of stochastic fluctuations. Our main result is the closed form of the
generating functional valid for any initial statistics. Moreover, we extend the
renormalization group method proposed by Mataresse and Pietroni to the case of
primordial non-Gaussian density and velocity fluctuations. As an application,
we calculate the nonlinear propagator and examine how the non-Gaussianity
affects the memory of cosmic fields to their initial conditions. It turns out
that the non-Gaussianity affect the nonlinear propagator. In the case of
positive skewness, the onset of the nonlinearity is advanced with a given
comoving wavenumber. On the other hand, the negative skewness gives the
opposite result.


title: Local Well-Posedness of Dynamics of Viscous Gaseous Stars

abstract:
  We establish the local in time well-posedness of strong solutions to the
vacuum free boundary problem of the compressible Navier-Stokes-Poisson system
in the spherically symmetric and isentropic motion. Our result captures the
physical vacuum boundary behavior of the Lane-Emden star configurations for all
adiabatic exponents $\gamma>{6/5}$.


title:
Quantum Dynamical Algebra SU(1,1) in One-Dimensional Exactly Solvable
  Potentials

abstract:
  We mainly explore the linear algebraic structure like SU(2) or SU(1,1) of the
shift operators for some one-dimensional exactly solvable potentials in this
paper. During such process, a set of method based on original diagonalizing
technique is presented to construct those suitable operator elements, J0, J_\pm
that satisfy SU(2) or SU(1,1) algebra. At last, the similarity between radial
problem and one-dimensional potentials encourages us to deal with the radial
problem in the same way.


title: Partitions with independent iterates in random dynamical systems

abstract:
  Consider an invertible measure-preserving transformation of a probability
space. A finite partition of the space is called weakly independent if there
are infinitely many images of this partition under powers of the transformation
that are jointly independent. Krengel proved that a transformation is weakly
mixing if and only if weakly independent partitions of the underlying space are
dense among all finite partitions. Using the tools developed in the later
papers of del Junco-Reinhold-Weiss and del Junco-Begun we obtain Krengel- type
results for weakly mixing random dynamical systems (or equivalently, skew
products that are relatively weakly mixing).


title: Magneto-optical Trapping of Cadmium

abstract:
  We report the laser-cooling and confinement of Cd atoms in a magneto-optical
trap, and characterize the loading process from the background Cd vapor. The
trapping laser drives the 1S0-1P1 transition at 229 nm in this two-electron
atom and also photoionizes atoms directly from the 1P1 state. This
photoionization overwhelms the other loss mechanisms and allows a direct
measurement of the photoionization cross section, which we measure to be
2(1)x10^(-16)cm^(2) from the 1P1 state. When combined with nearby laser-cooled
and trapped Cd^(+) ions, this apparatus could facilitate studies in ultracold
interactions between atoms and ions.


title:
Phase transitions in coupled two dimensional XY systems with spatial
  anisotropy

abstract:
  We study phase transitions of coupled two dimensional XY systems with spatial
anisotropy and $U(1) \times \mathbb{Z}_2$ symmetry, motivated by spinless
bosonic atoms trapped in square optical lattice on the metastable first excited
$p-$level orbitals with anisotropic hopping amplitudes. The phase transitions
of the system are generally split into an Ising transition and an XY
transition, but the sequence and the nature of the transitions depend on the
ratio between the anisotropic couplings. In the isotropic limit the XY
variables are expected to be disordered before the Ising variables when thermal
or quantum fluctuations are turned on gradually. In the anisotropic limit with
zero perpendicular hoppings, the finite temperature transition is a
Kosterlitz-Thouless transition driven by proliferation of hybrid half vortices,
and the zero temperature quantum phase transition is split into a bond order
transition and a 3D XY transition, which can be driven by the condensation of
either single vortices or half vortices. After the condensation of half
vortices the resultant state is a Mott Insulator of paired bosons. A small
perpendicular hopping $J_b$ leads to a 2D Ising transition at low temperature
and a 2+1d quantum Ising transition with a small charging energy at zero
temperature. Global phase diagrams for both classical and quantum phase
transitions are drawn. The analytical results obtained in this work are
expected to be checked both numerically and experimentally.


title:
Complex ferromagnetic state and magnetocaloric effect in single
  crystalline Nd_{0.7}Sr_{0.3}MnO_{3}

abstract:
  The magnetocaloric effect in single crystalline Nd_{0.7}Sr_{0.3}MnO_{3} is
investigated by measuring the field-induced adiabatic change in temperature
which reveals a single negative peak around 130 K well below the Curie
temperature (T_C=203 K). In order to understand this unusual magnetocaloric
effect, we invoke the reported {55}^Mn spin-echo nuclear magnetic resonance,
electron magnetic resonance and polarized Raman scattering measurements on
Nd_{0.7}Sr_{0.3}MnO_{3}. We show that this effect is a manifestation of a
competition between the double exchange mechanism and correlations arising from
coupled spin and lattice degrees of freedom which results in a complex
ferromagnetic state. The critical behavior of Nd_{0.7}Sr_{0.3}MnO_{3} near
Curie temperature is investigated to study the influence of the coupled degrees
of freedom. We find a complicated behavior at low fields in which the order of
the transition could not be fixed and a second-order-like behavior at high
fields.


title:
Calcium and synaptic dynamics underlying reverberatory activity in
  neuronal networks

abstract:
  Persistent activity is postulated to drive neural network plasticity and
learning. To investigate its underlying cellular mechanisms, we developed a
biophysically tractable model that explains the emergence, sustenance, and
eventual termination of short-term persistent activity. Using the model, we
reproduced the features of reverberating activity that were observed in small
(50-100 cells) networks of cultured hippocampal neurons, such as the appearance
of polysynaptic current clusters, the typical inter-cluster intervals, the
typical duration of reverberation, and the response to changes in
extra-cellular ionic composition. The model relies on action
potential-triggered residual presynaptic calcium, which we suggest plays an
important role in sustaining reverberations. We show that reverberatory
activity is maintained by enhanced asynchronous transmitter release from
pre-synaptic terminals, which in itself depends on the dynamics of residual
presynaptic calcium. Hence, asynchronous release, rather than being a "synaptic
noise", can play an important role in network dynamics. Additionally, we found
that a fast timescale synaptic depression is responsible for oscillatory
network activation during reverberations, whereas the onset of a slow timescale
depression leads to the termination of reverberation. The simplicity of our
model enabled a number of predictions that were confirmed by additional
analyses of experimental manipulations.


title:
Nonlocal effect on the magnetic penetration depth in multigapped
  superconductors

abstract:
  A brief discussion is given on the nonlocal effect in multigapped
superconductivity. It is pointed out that the effective magnetic penetration
depth at lower external fields may be reduced by the nonlocal effect associated
with the presence of small energy gap. A crude estimation of the effect in
double gap system is provided and compared with the data obtained by muSR in
MgB2.


title: Supersymmetric Construction of three-dimensional isospectral systems

abstract:
  Three-dimensional isospectral systems are constructed using the framework of
supersymmetric quantum mechanics. In case the supercharge of first order in
momentum is used, it is proved that the constructed systems reduce to a trivial
generalization of one-dimensional systems. In case the second order supercharge
is used, nontrivial three-dimensional isospectral systems are constructed.


title: Non-Cooperative Scheduling of Multiple Bag-of-Task Applications

abstract:
  Multiple applications that execute concurrently on heterogeneous platforms
compete for CPU and network resources. In this paper we analyze the behavior of
$K$ non-cooperative schedulers using the optimal strategy that maximize their
efficiency while fairness is ensured at a system level ignoring applications
characteristics. We limit our study to simple single-level master-worker
platforms and to the case where each scheduler is in charge of a single
application consisting of a large number of independent tasks. The tasks of a
given application all have the same computation and communication requirements,
but these requirements can vary from one application to another. In this
context, we assume that each scheduler aims at maximizing its throughput. We
give closed-form formula of the equilibrium reached by such a system and study
its performance. We characterize the situations where this Nash equilibrium is
optimal (in the Pareto sense) and show that even though no catastrophic
situation (Braess-like paradox) can occur, such an equilibrium can be
arbitrarily bad for any classical performance measure.


title:
A mode elimination technique to improve convergence of iteration methods
  for finding solitary waves

abstract:
  We extend the key idea behind the generalized Petviashvili method of Ref.
\cite{gP} by proposing a novel technique based on a similar idea. This
technique systematically eliminates from the iteratively obtained solution a
mode that is "responsible" either for the divergence or the slow convergence of
the iterations. We demonstrate, theoretically and with examples, that this mode
elimination technique can be used both to obtain some nonfundamental solitary
waves and to considerably accelerate convergence of various iteration methods.
As a collateral result, we compare the linearized iteration operators for the
generalized Petviashvili method and the well-known imaginary-time evolution
method and explain how their different structures account for the differences
in the convergence rates of these two methods.


title:
Generalized DMPK equation for strongly localized regime - numerical
  solution

abstract:
  Generalized Dorokhov-Mello-Pereyra-Kumar (GDMPK) equation [K. A. Muttalib and
J. R. Klauder, Phys. Rev. Lett. {\bf 82}, 4272 (1999)] has been proposed for
the description of the electron transport in strongly localized systems. We
develop an algorithm for the numerical solution of this equation and confirm
that GDMPK equation correctly describes the critical and localized regimes.
Contrary to the original DMPK equation, the generalized one contains also an
information about the dimension of the system. In particular, it distinguishes
between the two and the three dimensional models with the same number of
transmission channels.


title: Relative Strength of Strategy Elimination Procedures

abstract:
  We compare here the relative strength of four widely used procedures on
finite strategic games: iterated elimination of weakly/strictly dominated
strategies by a pure/mixed strategy. A complication is that none of these
procedures is based on a monotonic operator. To deal with this problem we use
'global' versions of these operators.


title:
The fluctuation spectra around a Gaussian classical solution of a tensor
  model and the general relativity

abstract:
  Tensor models can be interpreted as theory of dynamical fuzzy spaces. In this
paper, I study numerically the fluctuation spectra around a Gaussian classical
solution of a tensor model, which represents a fuzzy flat space in arbitrary
dimensions. It is found that the momentum distribution of the low-lying
low-momentum spectra is in agreement with that of the metric tensor modulo the
general coordinate transformation in the general relativity at least in the
dimensions studied numerically, i.e. one to four dimensions. This result
suggests that the effective field theory around the solution is described in a
similar manner as the general relativity.


title: Alternative linear structures for classical and quantum systems

abstract:
  The possibility of deforming the (associative or Lie) product to obtain
alternative descriptions for a given classical or quantum system has been
considered in many papers. Here we discuss the possibility of obtaining some
novel alternative descriptions by changing the linear structure instead. In
particular we show how it is possible to construct alternative linear
structures on the tangent bundle TQ of some classical configuration space Q
that can be considered as "adapted" to the given dynamical system. This fact
opens the possibility to use the Weyl scheme to quantize the system in
different non equivalent ways, "evading", so to speak, the von Neumann
uniqueness theorem.


title:
High-quality all-oxide Schottky junctions fabricated on heavily Nb-doped
  SrTiO3 substrates

abstract:
  We present a detailed investigation of the electrical properties of epitaxial
La0.7Sr0.3MnO3/SrTi0.98Nb0.02O3 Schottky junctions. A fabrication process that
allows reduction of the junction dimensions to current electronic device size
has been employed. A heavily doped semiconductor has been used as a substrate
in order to suppress its series resistance. We show that, unlike standard
semiconductors, high-quality oxide-based Schottky junctions maintain a highly
rectifying behavior for doping concentration of the semiconductor larger than
10^20 cm^(-3). Moreover, the junctions show hysteretic current-voltage
characteristics.


title: Effective equidistribution of S-integral points on symmetric varieties

abstract:
  Let K be a global field of characteristic not 2. Let Z be a symmetric variety
defined over K and S a finite set of places of K. We obtain counting and
equidistribution results for the S-integral points of Z. Our results are
effective when K is a number field.


title:
Out-of-equilibrium tricritical point in a system with long-range
  interactions

abstract:
  Systems with long-range interactions display a short-time relaxation towards
Quasi Stationary States (QSSs) whose lifetime increases with system size. With
reference to the Hamiltonian Mean Field (HMF) model, we here show that a
maximum entropy principle, based on Lynden-Bell's pioneering idea of "violent
relaxation", predicts the presence of out-of-equilibrium phase transitions
separating the relaxation towards homogeneous (zero magnetization) or
inhomogeneous (non zero magnetization) QSSs. When varying the initial condition
within a family of "water-bags" with different initial magnetization and
energy, first and second order phase transition lines are found that merge at
an out--of--equilibrium tricritical point. Metastability is theoretically
predicted and numerically checked around the first-order phase transition line.


title:
Angular momentum conservation and torsional oscillations in the Sun and
  solar-like stars

abstract:
  The solar torsional oscillations, i.e., the perturbations of the angular
velocity of rotation associated with the eleven-year activity cycle, are a
manifestation of the interaction among the interior magnetic fields, amplified
and modulated by the solar dynamo, and rotation, meridional flow and turbulent
thermal transport. Therefore, they can be used, at least in principle, to put
constraints on that interaction. Similar phenomena are expected to be observed
in solar-like stars and can be modelled to shed light on analogous interactions
in different environments. The source of the torsional oscillations is
investigated by means of a model for the angular momentum transport within the
convection zone. A description of the torsional oscillations is introduced,
based on an analytical solution of the angular momentum equation in the
mean-field approach. It provides information on the intensity and location of
the torques producing the redistribution of the angular momentum within the
convection zone of the Sun along the activity cycle. The method can be extended
to solar-like stars for which some information on the time-dependence of the
differential rotation is becoming available. Illustrative applications to the
Sun and solar-like stars are presented. Under the hypothesis that the solar
torsional oscillations are due to the mean-field Lorentz force, the mean
amplitude of the Maxwell stresses and the phase relationship between poloidal
and toroidal field components are obtained. Our preliminary results show the
capability of the proposed approach to constrain the amplitude, phase and
location of the perturbations leading to the observed torsional oscillations.


title:
Some notes concerning the prediction of the amplitude of the two solar
  activity cycles

abstract:
  The parameter G, which is determined from the general number of sunspots
groups Ng according to the daily observations G=Sum(1/Ng)^2, is offered. This
parameter is calculated for the days when there is at least one sunspots group.
It characterizes the minimum epoch solar activity. Parameter G mounts to the
maximum during the epoch close to the minimal activity of sunspots. According
too the data of the sequence of sunspots group in Greenwich-USAF/NOAA
observatory format, observation data of Kislovodsk solar station and also daily
Wolf number the changes of parameter G during 100 years were reconstructed. It
is demonstrated in the paper that parameter G's amplitude in minimal solar
activity n is linked with the sunspot cycle's amplitude Wn+1. The 24th activity
cycle prediction is calculated, which makes W24=135(+/-12).


title:
Small values of Lusternik-Schnirelmann and systolic categories for
  manifolds

abstract:
  We prove that manifolds of Lusternik-Schnirelmann category 2 necessarily have
free fundamental group. We thus settle a 1992 conjecture of Gomez-Larranaga and
Gonzalez-Acuna, by generalizing their result in dimension 3, to all higher
dimensions. We examine its ramifications in systolic topology, and provide a
sufficient condition for ensuring a lower bound of 3 for systolic category.


title: Near-Infrared Polarimetry of the Eagle Nebula (M16)

abstract:
  We carried out deep and wide (about 8' x 8') JHKs imaging polarimetry in the
southern region of the Eagle Nebula (M16). The polarization intensity map
reveals that two YSOs with near-IR reflection nebulae are located at the tips
of two famous molecular pillars (Pillars 1 and 2) facing toward the exciting
stars of M16. The centrosymmetric polarization pattern are consistent with
those around class I objects having circumstellar envelopes, confirming that
star formation is now taking place at the two tips of the pillars under the
influence of UV radiation from the exciting stars. Polarization measurements of
point sources show that magnetic fields are aligned along some of the pillars
but in a direction that is quite different to the global structure in M16.


title: Rectified momentum transport for a kicked Bose-Einstein Condensate

abstract:
  We report the experimental observation of rectified momentum transport for a
Bose-Einstein Condensate kicked at the Talbot time (quantum resonance) by an
optical standing wave. Atoms are initially prepared in a superposition of the 0
and -2*hbar*kl momentum states using an optical pi/2 pulse. By changing the
relative phase of the superposed states, a momentum current in either direction
along the standing wave may be produced. We offer an interpretation based on
matter wave interference, showing that the observed effect is uniquely quantum.


title: Thermodynamics of pairing in mesoscopic systems

abstract:
  Using numerical and analytical methods implemented for different models we
conduct a systematic study of thermodynamic properties of pairing correlation
in mesoscopic nuclear systems. Various quantities are calculated and analyzed
using the exact solution of pairing. An in-depth comparison of canonical, grand
canonical, and microcanonical ensemble is conducted. The nature of the pairing
phase transition in a small system is of a particular interest. We discuss the
onset of discontinuity in the thermodynamic variables, fluctuations, and
evolution of zeros of the canonical and grand canonical partition functions in
the complex plane. The behavior of the Invariant Correlational Entropy is also
studied in the transitional region of interest. The change in the character of
the phase transition due to the presence of magnetic field is discussed along
with studies of superconducting thermodynamics.


title: Emergently Thermalized Islands in the Landscape

abstract:
  In this note, we point out that in the eternal inflation driven by the
metastable vacua of the landscape, it might be possible that some large and
local quantum fluctuations with the null energy condition violation can stride
over the barriers between different vacua and straightly create some islands
with radiation and matter in new vacua. Then these thermalized islands will
evolve with the standard cosmology. We show that such islands may be consistent
with our observable universe, while has some distinctly observable signals,
which may be tested in coming observations.


title:
An analytic study of the ionization from an ultrathin quantum well in a
  weak electrostatic field

abstract:
  We consider the time evolution of a particle bound by an attractive
one-dimensional delta-function potential (at x = 0) when a uniform
electrostatic field (F) is applied. We explore explicit expressions for the
time-dependent wavefunction \psi_F(x,t) and the ionization probability
{\mathcal{P}}(t), respectively, in the weak-field limit. In doing so,
\psi_F(0,t) is a key element to their evaluation. We obtain a closed expression
for \psi_F(0,t) which is an excellent approximation of the exact result being a
numerical solution of the Lippmann-Schwinger integral equation. The resulting
probability density |\psi_F(0,t)|^2, as a simple alternative to
{\mathcal{P}}(t), is also in good agreement to its counterpart from the exact
one. In doing this, we also find a new and useful integral identity of the Airy
function.


title:
Action Principle and Algebraic Approach to Gauge Transformations in
  Gauge Theories

abstract:
  The action principle is used to derive, by an entirely algebraic approach,
gauge transformations of the full vacuum-to-vacuum transition amplitude
(generating functional) from the Coulomb gauge to arbitrary covariant gauges
and in turn to the celebrated Fock-Schwinger (FS) gauge for the abelian (QED)
gauge theory without recourse to path integrals or to commutation rules and
without making use of delta functionals. The interest in the FS gauge, in
particular, is that it leads to Faddeev-Popov ghosts-free non-abelian gauge
theories. This method is expected to be applicable to non-abelian gauge
theories including supersymmetric ones.


title: Wetting of gradient fields: pathwise estimates

abstract:
  We consider the wetting transition in the framework of an effective interface
model of gradient type, in dimension 2 and higher. We prove pathwise estimates
showing that the interface is localized in the whole thermodynamically-defined
partial wetting regime considered in earlier works. Moreover, we study how the
interface delocalizes as the wetting transition is approached. Our main tool is
reflection positivity in the form of the chessboard estimate.


title:
Large Attractive Depletion Interactions in Soft Repulsive-Sphere Binary
  Mixtures

abstract:
  We consider binary mixtures of soft repulsive spherical particles and
calculate the depletion interaction between two big spheres mediated by the
fluid of small spheres, using different theoretical and simulation methods. The
validity of the theoretical approach, a virial expansion in terms of the
density of the small spheres, is checked against simulation results. Attention
is given to the approach toward the hard-sphere limit, and to the effect of
density and temperature on the strength of the depletion potential. Our results
indicate, surprisingly, that even a modest degree of softness in the pair
potential governing the direct interactions between the particles may lead to a
significantly more attractive total effective potential for the big spheres
than in the hard-sphere case. This might lead to significant differences in
phase behavior, structure and dynamics of a binary mixture of soft repulsive
spheres. In particular, a perturbative scheme is applied to predict the phase
diagram of an effective system of big spheres interacting via depletion forces
for a size ratio of small and big spheres of 0.2; this diagram includes the
usual fluid-solid transition but, in the soft-sphere case, the metastable
fluid-fluid transition, which is probably absent in hard-sphere mixtures, is
close to being stable with respect to direct fluid-solid coexistence. From
these results the interesting possibility arises that, for sufficiently soft
repulsive particles, this phase transition could become stable. Possible
implications for the phase behavior of real colloidal dispersions are
discussed.


title: Critical Delays and Polynomial Eigenvalue Problems

abstract:
  In this work we present a new method to compute the delays of delay
differential equations (DDEs), such that the DDE has a purely imaginary
eigenvalue. For delay differential equations with multiple delays, the critical
curves or critical surfaces in delay space (that is, the set of delays where
the DDE has a purely imaginary eigenvalue) are parameterized. We show how the
method is related to other works in the field by treating the case where the
delays are integer multiples of some delay value, i.e., commensurate delays.
  The parametrization is done by solving a {\em quadratic eigenvalue problem}
which is constructed from the vectorization of a matrix equation and hence
typically of large size. For commensurate delay differential equations, the
corresponding equation is a polynomial eigenvalue problem. As a special case of
the proposed method, we find a closed form for a parameterization of the
critical surface for the scalar case.
  We provide several examples with visualizations where the computation is done
with some exploitation of the structure of eigenvalue problems.


title:
D-brane States and Disk Amplitudes in OSp Invariant Closed String Field
  Theory

abstract:
  We construct solitonic states in the OSp invariant string field theory, which
are BRST invariant in the leading order of regularization parameter $\epsilon$.
We calculate the disk amplitudes using these solitonic states and show that
they describe D-branes and ghost D-branes.


title:
Background studies and shielding effects for the TPC detector of the
  CAST experiment

abstract:
  Sunset solar axions traversing the intense magnetic field of the CERN Axion
Solar Telescope (CAST) experiment may be detected in a Time Projection Chamber
(TPC) detector, as X-rays signals. These signals could be masked, however, by
the inhomogeneous background of materials in the experimental site. A detailed
analysis, based on the detector characteristics, the background radiation at
the CAST site, simulations and experimental results, has allowed us to design a
shielding which reduces the background level by a factor of ~4 compared to the
detector without shielding, depending on its position, in the energy range
between 1 and 10 keV. Moreover, this shielding has improved the homogeneity of
background measured by the TPC.


title: t-Wise Independence with Local Dependencies

abstract:
  In this note we prove a large deviation bound on the sum of random variables
with the following dependency structure: there is a dependency graph $G$ with a
bounded chromatic number, in which each vertex represents a random variable.
Variables that are represented by neighboring vertices may be arbitrarily
dependent, but collections of variables that form an independent set in $G$ are
$t$-wise independent.


title:
Josephson current in a superconductor -- ferromagnet -- superconductor
  junction with in-plane ferromagnetic domains

abstract:
  We study a diffusive superconductor--ferromagnet--superconductor (SFS)
junction with in-plane ferromagnetic domains. Close to the superconducting
transition temperature, we describe the proximity effect in the junction with
the linearized Usadel equations. We find that properties of such a junction
depend on the size of the domains relative to the magnetic coherence length. In
the case of large domains, the junction exhibits transitions to the $\pi$
state, similarly to a single-domain SFS junction. In the case of small domains,
the magnetization effectively averages out, and the junction is always in the
zero state, similarly to a superconductor--normal metal--superconductor (SNS)
junction. In both those regimes, the influence of domain walls may be
approximately described as an effective spin-flip scattering. We also study the
inhomogeneous distribution of the local current density in the junction. Close
to the 0--$\pi$ transitions, the directions of the critical current may be
opposite in the vicinity of the domain wall and in the middle of the domains.


title:
The chemical composition of the circumstellar envelopes around yellow
  hypergiant stars

abstract:
  The yellow hypergiant stars (YHGs) are extremely luminous and massive objects
whose general properties are poorly known. Only two of this kind of star show
massive circumstellar envelopes, IRC+10420 and AFGL2343. We aim to study the
chemistry of the circumstellar envelopes around these two sources, by
comparison with well known AGB stars and protoplanetary nebulae. We also
estimate the abundances of the observed molecular species. We have performed
single-dish observations of different transitions for twelve molecular species.
We have compared the ratio of the intensities of the molecular transitions and
of the estimated abundances in AFGL2343 and IRC+10420 with those in O-rich and
C-rich AGB stars and protoplanetary nebulae. Both YHGs, AFGL2343, and
IRC+10420, have been found to have an O-rich chemistry similar to that in
O-rich AGB stars, though for AFGL2343 the emission of most molecules compared
with 13CO lines is relatively weak. Clear differences with the other evolved
sources appear when we compare the line intensity corrected for distance and
the profile widths which are, respectively, very intense and very wide in YHGs.
The abundances obtained for IRC+10420 agree with those found in AGB stars, but
in general those found in AFGL2343, except for 13CO, are too low. This
apparently low molecular abundance in AFGL2343 could be due to the fact that
these molecules are present only in an inner region of the shell where the mass
is relatively low.


title:
Independent measurement of the top quark mass and the light- and
  bottom-jet energy scales at hadron colliders

abstract:
  A method for the simultaneous determination of the energy scales for b-quark
jets and light jets, the jet energy resolution, and the top quark mass at
hadron colliders is presented. The method exploits the unique kinematics of
events with top-antitop pair production, where one of the top quarks involves a
leptonic and one a hadronic W boson decay. The paper shows a feasibility study
of how this simultaneous measurement can be performed at the upcoming LHC
experiments ATLAS and CMS.


title: Non-unity gain minimal disturbance measurement

abstract:
  We propose and experimentally demonstrate an optimal non-unity gain Gaussian
scheme for partial measurement of an unknown coherent state that causes minimal
disturbance of the state. The information gain and the state disturbance are
quantified by the noise added to the measurement outcomes and to the output
state, respectively. We derive the optimal trade-off relation between the two
noises and we show that the trade-off is saturated by non-unity gain
teleportation. Optimal partial measurement is demonstrated experimentally using
a linear optics scheme with feed-forward.


title: On the growth of components with non fixed excesses

abstract:
  Denote by an $l$-component a connected graph with $l$ edges more than
vertices. We prove that the expected number of creations of $(l+1)$-component,
by means of adding a new edge to an $l$-component in a randomly growing graph
with $n$ vertices, tends to 1 as $l,n$ tends to $\infty$ but with $l =
o(n^{1/4})$. We also show, under the same conditions on $l$ and $n$, that the
expected number of vertices that ever belong to an $l$-component is $\sim
(12l)^{1/3} n^{2/3}$.


title: APEX survey of southern high mass star forming regions

abstract:
  A systematic study of a large sample of sources, covering a wide range in
galactocentric distances, masses and luminosities, is a fast and efficient way
of obtaining a good overview of the different stages of high-mass star
formation. With these goals in mind, we have started a survey of 40 color
selected IRAS sources south of -20 degrees declination with the APEX telescope
on Chajnantor, Chile. Our first APEX results already demonstrate that the
selection criteria were successful, since some of the sources are very rich in
molecular lines.


title: Pseudo-Gaussian quantum models

abstract:
  A new family of one-dimensional quantum models is proposed in terms of new
potentials with a Gaussian asymptotic behavior but approaching to the potential
of the harmonic o scillator when $x\to 0$. It is shown that, in the energy
basis of the harmonic oscillator, the matrix elements of the Hamiltonian
operators of these new models can be derived from generating functionals.


title: Dynamics of Three Agent Games

abstract:
  We study the dynamics and resulting score distribution of three-agent games
where after each competition a single agent wins and scores a point. A single
competition is described by a triplet of numbers $p$, $t$ and $q$ denoting the
probabilities that the team with the highest, middle or lowest accumulated
score wins. We study the full family of solutions in the regime, where the
number of agents and competitions is large, which can be regarded as a
hydrodynamic limit. Depending on the parameter values $(p,q,t)$, we find six
qualitatively different asymptotic score distributions and we also provide a
qualitative understanding of these results. We checked our analytical results
against numerical simulations of the microscopic model and find these to be in
excellent agreement. The three agent game can be regarded as a social model
where a player can be favored or disfavored for advancement, based on his/her
accumulated score. It is also possible to decide the outcome of a three agent
game through a mini tournament of two-a gent competitions among the
participating players and it turns out that the resulting possible score
distributions are a subset of those obtained for the general three agent-games.
We discuss how one can add a steady and democratic decline rate to the model
and present a simple geometric construction that allows one to write down the
corresponding score evolution equations for $n$-agent games.


title:
Limits of ultra-high-precision optical astrometry: Stellar surface
  structures

abstract:
  We investigate the astrometric effects of stellar surface structures as a
practical limitation to ultra-high-precision astrometry, e.g. in the context of
exoplanet searches, and to quantify the expected effects in different regions
of the HR-diagram. Stellar surface structures are likely to produce
fluctuations in the integrated flux and radial velocity of the star, as well as
a variation of the observed photocentre, i.e. astrometric jitter, and closure
phase. We use theoretical considerations supported by Monte Carlo simulations
to derive statistical relations between the corresponding astrometric,
photometric, and radial-velocity effects. For most stellar types the
astrometric jitter due to stellar surface structures is expected to be of order
10 micro-AU or greater. This is more than the astrometric displacement
typically caused by an Earth-size exoplanet in the habitable zone, which is
about 1-4 micro-AU for long-lived main-sequence stars. Only for stars with
extremely low photometric variability (<0.5 mmag) and low magnetic activity,
comparable to that of the Sun, will the astrometric jitter be of order 1
micro-AU, suffcient to allow the astrometric detection of an Earth-sized planet
in the habitable zone. While stellar surface structure may thus seriously
impair the astrometric detection of small exoplanets, it has in general
negligible impact on the detection of large (Jupiter-size) planets and on the
determination of stellar parallax and proper motion. From the starspot model we
also conclude that the commonly used spot filling factor is not the most
relevant parameter for quantifying the spottiness in terms of the resulting
astrometric, photometric and radial-velocity variations.


title:
Non-lattice simulation for supersymmetric gauge theories in one
  dimension

abstract:
  Lattice simulation of supersymmetric gauge theories is not straightforward.
In some cases the lack of manifest supersymmetry just necessitates cumbersome
fine-tuning, but in the worse cases the chiral and/or Majorana nature of
fermions makes it difficult to even formulate an appropriate lattice theory. We
propose to circumvent all these problems inherent in the lattice approach by
adopting a non-lattice approach in the case of one-dimensional supersymmetric
gauge theories, which are important in the string/M theory context.


title:
Persistence of characteristics of an ordered flux line lattice above the
  second peak in $Bi_2Sr_2CaCu_2O_{8+ \delta}$

abstract:
  We report Small Angle Neutron Scattering measurements of the flux lines
lattice (FLL) in $Bi_2Sr_2CaCu_2O_{8+ \delta}$. As previously reported, the
scattered intensity decreases strongly when the magnetic field is increased,
but it remains measurable far above the second peak. The direct observation of
Bragg peaks proves that the characteristics of a lattice are still present. No
structural features related to a symmetry breaking, such as a liquid like or an
amorphous state, can be observed. However, the associated scattered intensity
is very low and is difficult to explain. We discuss the coexistence between two
FLL states as a possible interpretation.


title:
On the Low Energy Spectra of the Nonsupersymmetric Heterotic String
  Theories

abstract:
  The ten dimensional string theories as well as eleven dimensional
supergravity are conjectured to arise as limits of a more basic theory,
traditionaly dubbed M--theory. This notion is confined to the ten dimensional
supersymmetric theories. String theory, however, also contains ten dimensional
nonsupersymmetric theories that have not been incorporated into this picture.
In this note we explore the possibility of generating the low energy spectra of
various nonsupersymmetric heterotic string vacua form the Horava--Witten model.
We argue that this can be achieved by imposing on the Horava--Witten model an
invariance with respect to some extra operators which identify the orbifold
fixed planes in a nontrivial way, and demonstrate it for the E_8 and
SO(16)XSO(16) heterotic string vacua in ten dimensions.


title: A common limit of super Liouville theory and minimal models

abstract:
  We show that N=1 supersymmetric Liouville theory can be continued to central
charge c=3/2, and that the limiting non-rational superconformal field theory
can also be obtained as a limit of supersymmetric minimal models. This
generalises a result known for the non-supersymmetric case. We present explicit
expressions for the three-point functions of bulk fields, as well as a set of
superconformal boundary states. The main technical ingredient to take the limit
of minimal models consists in determining analytic expressions for the
structure constants. In the appendix we show in detail how the structure
constants of supersymmetric and Virasoro minimal models can be rewritten in
terms of Barnes' double gamma functions.


title:
On Some Lie Bialgebra Structures on Polynomial Algebras and their
  Quantization

abstract:
  We study classical twists of Lie bialgebra structures on the polynomial
current algebra $\mathfrak{g}[u]$, where $\mathfrak{g}$ is a simple complex
finite-dimensional Lie algebra. We focus on the structures induced by the
so-called quasi-trigonometric solutions of the classical Yang-Baxter equation.
It turns out that quasi-trigonometric $r$-matrices fall into classes labelled
by the vertices of the extended Dynkin diagram of $\mathfrak{g}$. We give
complete classification of quasi-trigonometric $r$-matrices belonging to
multiplicity free simple roots (which have coefficient 1 in the decomposition
of the maximal root). We quantize solutions corresponding to the first root of
$\mathfrak{sl}(n)$.


title:
Right and Left Joint System Representation of a Rational Matrix Function
  in General Position (System Representation Theory for Dummies)

abstract:
  For a rational matrix function R of one variable in general position, the
matrix functions R(x)/R(y) and R(y)\R(x) of two variables are considered. For
these matrix functions of two variables, representations which are analogous to
the system representations (or realizations) of a rational matrix function of
one variable are constructed. This representation is called the joint right
[the joint left] system representation.


title:
Thermodynamic forces, flows, and Onsager coefficients in complex
  networks

abstract:
  We present Onsager formalism applied to random networks with arbitrary degree
distribution. Using the well-known methods of non-equilibrium thermodynamics we
identify thermodynamic forces and their conjugated flows induced in networks as
a result of single node degree perturbation. The forces and the flows can be
understood as a response of the system to events, such as random removal of
nodes or intentional attacks on them. Finally, we show that cross effects (such
as thermodiffusion, or thermoelectric phenomena), in which one force may not
only give rise to its own corresponding flow, but to many other flows, can be
observed also in complex networks.


title: Gravity as an emergent phenomenon: A conceptual description

abstract:
  I describe several broad features of a programme to understand gravity as an
emergent, long wavelength, phenomenon (like elasticity) and discuss one
concrete framework for realizing this paradigm in the backdrop of several
recent results.


title: Pascal's triangle and word bases for blob algebra ideals

abstract:
  We give an elementary proof of isomorphism of the blob (diagram) algebra and
the corresponding extended Temperley-Lieb algebra (defined by presentation).


title:
Millisecond pulsars around intermediate-mass black holes in globular
  clusters

abstract:
  We study the process of dynamical capture of a millisecond pulsar (MSP) by a
single or binary IMBH, simulating various types of single-binary and
binary-binary encounters. It is found that [IMBH,MSP] binaries form over cosmic
time in a cluster, via encounters of wide--orbit binary MSPs off the single
IMBH, and at a lower pace, via interactions of (binary or single) MSPs with the
IMBH orbited by a typical cluster star. The formation of an [IMBH,MSP] system
is strongly inhibited if the IMBH is orbited by a stellar mass black hole. The
[IMBH,MSP] binaries that form are relatively short-lived, $\lsim 10^{8-9}$ yr,
since their orbits decay via emission of gravitational waves. The detection of
an [IMBH,MSP] system has a low probability of occurrence, when inferred from
the current sample of MSPs in GCs. If next generation radio telescopes, like
SKA, will detect an order of magnitude larger population of MSP in GCs, at
least one [IMBH,MSP] is expected. Therefore, a complete search for
low-luminosity MSPs in the GCs of the Milky Way with SKA will have the
potential of testing the hypothesis that IMBHs of order $100 \msun$ are
commonly hosted in GCs.


title:
Dynamical Heterogeneity and Nonlinear Susceptibility in Short-Ranged
  Attractive Supercooled Liquids

abstract:
  Recent work has demonstrated the strong qualitative differences between the
dynamics near a glass transition driven by short-ranged repulsion and one
governed by short-ranged attraction. Here, we study in detail the behavior of
non-linear, higher-order correlation functions that measure the growth of
length scales associated with dynamical heterogeneity in both types of systems.
We find that this measure is qualitatively different in the repulsive and
attractive cases with regards to the wave vector dependence as well as the time
dependence of the standard non-linear four-point dynamical susceptibility. We
discuss the implications of these results for the general understanding of
dynamical heterogeneity in glass-forming liquids.


title:
Limits to the diffuse flux of UHE tau neutrinos at EeV energies from the
  Pierre Auger Observatory

abstract:
  With the Pierre Auger Observatory we have the capability of detecting
ultra-high energy neutrinos by searching for very inclined showers with a
significant electromagnetic component. In this work we discuss the
discrimination power of the instrument for earth skimming tau neutrinos with
ultra-high energies. Based on the data collected since January 2004 an upper
limit to the diffuse flux of neutrinos atEeV energies is presented and
systematic uncertainties are discussed.


title:
Hybrid Quasicrystals, Transport and Localization in Products of Minimal
  Sets

abstract:
  We consider convex combinations of finite-valued almost periodic sequences
(mainly substitution sequences) and put them as potentials of one-dimensional
tight-binding models. We prove that these sequences are almost periodic. We
call such combinations {\em hybrid quasicrystals} and these studies are related
to the minimality, under the shift on both coordinates, of the product space of
the respective (minimal) hulls. We observe a rich variety of behaviors on the
quantum dynamical transport ranging from localization to transport.


title: Brane Tilings

abstract:
  We review and extend the progress made over the past few years in
understanding the structure of toric quiver gauge theories; those which are
induced on the world-volume of a stack of D3-branes placed at the tip of a
toric Calabi-Yau cone, at an ``orbifold point'' in Kaehler moduli space. These
provide an infinite class of four-dimensional N=1 superconformal field theories
which may be studied in the context of the AdS/CFT correspondence. It is now
understood that these gauge theories are completely specified by certain
two-dimensional torus graphs, called brane tilings, and the combinatorics of
the dimer models on these graphs. In particular, knowledge of the dual
Sasaki-Einstein metric is not required to determine the gauge theory, only
topological and symplectic properties of the toric Calabi-Yau cone. By
analyzing the symmetries of the toric quiver theories we derive the dimer
models and use them to construct the moduli space of the theory both
classically and semiclassically. Using mirror symmetry the brane tilings are
shown to arise in string theory on the world-volumes of the fractional
D6-branes that are mirror to the stack of D3-branes at the tip of the cone.


title:
Quantum electrodynamics and experiment demonstrate the non-retarded
  nature of electrodynamical force fields

abstract:
  In quantum electrodynamics, the quantitatively most successful theory in the
history of science, intercharge forces obeying the inverse square law are due
to the exchange of space-like virtual photons. The fundamental quantum process
underlying applications as diverse as the gyromagnetic ratio of the electron
and electrical machinery is then M{\o}ller scattering $ee \to ee$. Analysis of
the quantum amplitude for this process shows that the corresponding intercharge
force acts instantaneously. This prediction has been verified in a recent
experiment.


title:
Temperature dependence of magnetic anisotropy in bulk and nanoparticles
  of Pr_0.5Sr_0.5MnO_3

abstract:
  Nanoparticles (size 20, 40 and 60 nm) of Pr_0.5Sr_0.5MnO_3 are prepared by
sol-gel technique and their magnetic properties are studied using ferromagnetic
resonance and magnetization measurements. A comparison with the properties of
the bulk material shows that the ferromagnetic transition at 265 K remains
unaffected but the anti-ferromagnetic transition at T_N = 150 K disappears in
the nanoparticles. Further, the temperature dependence of magnetic anisotropy
shows a complex behavior, being higher in the nanoparticles at high
temperatures and lower at lower temperatures in comparison with the bulk.


title: Stability of the Einstein static universe in f(R) gravity

abstract:
  We analyze the stability of the Einstein static universe by considering
homogeneous scalar perturbations in the context of f(R) modified theories of
gravity. By considering specific forms of f(R), the stability regions of the
solutions are parameterized by a linear equation of state parameter w=p/rho.
Contrary to classical general relativity, it is found that in f(R) gravity a
stable Einstein cosmos with a positive cosmological constant does indeed exist.
Thus, we are lead to conclude that, in principle, modifications in f(R) gravity
stabilize solutions which are unstable in general relativity.


title:
A new young stellar cluster embedded in a molecular cloud in the far
  outer Galaxy

abstract:
  We report the discovery of a new young stellar cluster and molecular cloud
located in the far outer Galaxy, seen towards IRAS 06361-0142, and we
characterise their properties. Near-infrared images were obtained with
VLT/ISAAC through JHKs filters, millimetre line observations of CO(1-0) were
obtained with SEST, and VLA 6 cm continuum maps obtained from archive data. The
cloud and cluster are located at a distance of 7 kpc and a Galactocentric
distance of 15 kpc, well in the far outer Galaxy. Morphologically, IRAS
06361-0142 appears as a cluster of several tens of stars surrounded by a nearly
spherical nebular cavity centred at the position of the IRAS source. The
cluster appears composed of low and intermediate-mass, young reddened stars
with a large fraction having cleared the inner regions of their circumstellar
discs responsible for (H - Ks) colour excess. The observations are compatible
with a 4 Myr cluster with variable spatial extinction between Av = 6 and Av =
13.


title: Another Proof of Wright's Inequalities

abstract:
  We present a short way of proving the inequalities obtained by Wright in
[Journal of Graph Theory, 4: 393 - 407 (1980)] concerning the number of
connected graphs with $\ell$ edges more than vertices.


title: x-Evolution of Phenomenological Dipole Cross Sections

abstract:
  Deep inelastic scattering at small x can be described very effectively using
saturation inspired dipole models. We investigate whether such models are
compatible with the numerical solutions of the Balitsky-Kovchegov (BK) equation
which is expected to describe the nonlinear evolution in x of the dipole cross
section. We find that the BK equation yields results that are qualitatively
different from those of phenomenological studies. Geometric scaling is
recovered only towards asymptotic rapidities. In this limit the value of the
anomalous dimension gamma(r,x) at the saturation scale approaches approximately
0.44, in contrast to the value 0.63 commonly used in the models.


title: On the Moduli Space of non-BPS Attractors for N=2 Symmetric Manifolds

abstract:
  We study the ``flat'' directions of non-BPS extremal black hole attractors
for N=2, d=4 supergravities whose vector multiplets' scalar manifold is endowed
with homogeneous symmetric special Kahler geometry. The non-BPS attractors with
non-vanishing central charge have a moduli space described by real special
geometry (and thus related to the d=5 parent theory), whereas the moduli spaces
of non-BPS attractors with vanishing central charge are certain Kahler
homogeneous symmetric manifolds. The moduli spaces of the non-BPS attractors of
the corresponding N=2, d=5 theories are also indicated, and shown to be rank-1
homogeneous symmetric manifolds.


title:
Controlling Secondary Structures of Bio-Polymers with Hydrogen-Like
  Bonding

abstract:
  We present results for a lattice model of bio-polymers where the type of
$\beta$-sheet formation can be controlled by different types of hydrogen bonds
depending on the relative orientation of close segments of the polymer. Tuning
these different interaction strengths leads to low-temperature structures with
different types of orientational order. We perform simulations of this model
and so present the phase diagram, ascertaining the nature of the phases and the
order of the transitions between these phases.


title: The Elongated Structure of the Hercules dSph from Deep LBT Imaging

abstract:
  We present a deep, wide-field photometric survey of the newly-discovered
Hercules dwarf spheroidal galaxy, based on data from the Large Binocular
Telescope. Images in B, V and r were obtained with the Large Binocular Camera
covering a 23' times 23' field of view to a magnitude of ~25.5 (5 sigma). This
permitted the construction of colour-magnitude diagrams that reach
approximately 1.5 magnitudes below the Hercules main sequence turnoff.
Three-filter photometry allowed us to preferentially select probable Hercules
member stars, and examine the structure of this system at a previously
unattained level. We find that the Hercules dwarf is highly elongated (3:1),
considerably more so than any other dSph satellite of the Milky Way except the
disrupting Sagittarius dwarf. While we cannot rule out that the unusual
structure is intrinsic to Hercules as an equilibrium system, our results
suggest tidal disruption as a likely cause of this highly elliptical structure.
Given the relatively large Galactocentric distance of this system (132 +/- 12
kpc), signs of tidal disruption would require the Hercules dwarf to be on a
highly eccentric orbit around the Milky Way.


title: Strong dipolar effects in a quantum ferrofluid

abstract:
  We report on the realization of a Chromium Bose-Einstein condensate (BEC)
with strong dipolar interaction. By using a Feshbach resonance, we reduce the
usual isotropic contact interaction, such that the anisotropic magnetic
dipole-dipole interaction between 52Cr atoms becomes comparable in strength.
This induces a change of the aspect ratio of the cloud, and, for strong dipolar
interaction, the inversion of ellipticity during expansion - the usual "smoking
gun" evidence for BEC - can even be suppressed. These effects are accounted for
by taking into account the dipolar interaction in the superfluid hydrodynamic
equations governing the dynamics of the gas, in the same way as classical
ferrofluids can be described by including dipolar terms in the classical
hydrodynamic equations. Our results are a first step in the exploration of the
unique properties of quantum ferrofluids.


title: Symplectic Structure of the Real Ginibre Ensemble

abstract:
  We give a simple derivation of all $n$-point densities for the eigenvalues of
the real Ginibre ensemble with even dimension $N$ as quaternion determinants. A
very simple symplectic kernel governs both, the real and complex correlations.
1-and-2-point correlations are discussed in more detail. Scaling forms for
large dimension $N$ are derived.


title:
Resonant phenomena in extended chaotic systems subject to external
  noise: the Lorenz'96 model case

abstract:
  We investigate the effects of a time-correlated noise on an extended chaotic
system. The chosen model is the Lorenz'96, a kind of "toy" model used for
climate studies. Through the analysis of the system's time evolution and its
time and space correlations, we have obtained numerical evidence for two
stochastic resonance-like behavior. Such behavior is seen when both, the usual
and a generalized signal-to-noise ratio function are depicted as a function of
the external noise intensity or the system size. The underlying mechanism seems
to be associated to a "noise-induced chaos reduction". The possible relevance
of these and other findings for an "optimal" climate prediction are discussed.


title:
Representations and classification of traveling wave solutions to
  Sinh-G{\"o}rdon equation

abstract:
  Two concepts named atom solution and combinatory solution are defined. The
classification of all single traveling wave atom solutions to Sinh-G{\"o}rdon
equation is obtained, and qualitative properties of solutions are discussed. In
particular, we point out that some qualitative properties derived intuitively
from dynamic system method aren't true. In final, we prove that our solutions
to Sinh-G{\"o}rdon equation include all solutions obtained in the paper[Fu Z T
et al, Commu. in Theor. Phys.(Beijing) 2006 45 55]. Through an example, we show
how to give some new identities on Jacobian elliptic functions.


title:
Fluctuations of the Casimir-Polder force between an atom and a
  conducting wall

abstract:
  We consider the quantum fluctuations of the Casimir-Polder force between a
neutral atom and a perfectly conducting wall in the ground state of the system.
In order to obtain the atom-wall force fluctuation we first define an operator
directly associated to the force experienced by the atom considered as a
polarizable body in an electromagnetic field, and we use a time-averaged force
operator in order to avoid ultraviolet divergences appearing in the fluctuation
of the force. This time-averaged force operator takes into account that any
measurement involves a finite time. We also calculate the Casimir-Polder force
fluctuation for an atom between two conducting walls. Experimental
observability of these Casimir-Polder force fluctuations is also discussed, as
well as the dependence of the relative force fluctuation on the duration of the
measurement.


title: On Phases of Generic Toric Singularities

abstract:
  We systematically study the phases of generic toric singularities, using
methods initiated in hep-th/0612046. These correspond to Gauged Linear Sigma
Models with arbitrary charges. We show that complete information about generic
$U(1)^r$ GLSMs can be obtained by studying the GLSM Lagrangian, appropriately
modified in the different phases of the theory. This can be used to study the
different phases of $L^{a,b,c}$ spaces and their non-supersymmetric
counterparts.


title:
Discovery of the strongly eccentric, short-period binary nature of the
  B-type system HD 313926 by the MOST satellite

abstract:
  The MOST photometric space mission discovered an eclipsing binary among its
guide stars in June 2006 which combines a relatively large eccentricity e =
0.20 with an orbital period of only 2.27 days. HD 313926 appears to consist of
two early-type stars of spectral type B3 - B7. It has a largest eccentricity
among known early-type binaries with periods less than 3.5 d. Despite the large
components indicated by its spectral type and light curve model, and its short
period, the orbit of HD 313926 has not yet circularised so it is probably very
young, even compared to other young B stars.


title:
Pure point diffraction implies zero entropy for Delone sets with uniform
  cluster frequencies

abstract:
  Delone sets of finite local complexity in Euclidean space are investigated.
We show that such a set has patch counting and topological entropy 0 if it has
uniform cluster frequencies and is pure point diffractive. We also note that
the patch counting entropy is 0 whenever the repetitivity function satisfies a
certain growth restriction.


title: Nonequilibrium Steady States of Matrix Product Form: A Solver's Guide

abstract:
  We consider the general problem of determining the steady state of stochastic
nonequilibrium systems such as those that have been used to model (among other
things) biological transport and traffic flow. We begin with a broad overview
of this class of driven diffusive systems - which includes exclusion processes
- focusing on interesting physical properties, such as shocks and phase
transitions. We then turn our attention specifically to those models for which
the exact distribution of microstates in the steady state can be expressed in a
matrix product form. In addition to a gentle introduction to this matrix
product approach, how it works and how it relates to similar constructions that
arise in other physical contexts, we present a unified, pedagogical account of
the various means by which the statistical mechanical calculations of
macroscopic physical quantities are actually performed. We also review a number
of more advanced topics, including nonequilibrium free energy functionals, the
classification of exclusion processes involving multiple particle species,
existence proofs of a matrix product state for a given model and more
complicated variants of the matrix product state that allow various types of
parallel dynamics to be handled. We conclude with a brief discussion of open
problems for future research.


title:
Ground state solutions for the nonlinear Schrodinger-Maxwell equations
  with a singular potential

abstract:
  We prove the existence of ground state solutions for the nonlinear
Schrodinger-Maxwell equations with a singular potential.


title: On fundamental groups related to the Hirzebruch surface F_1

abstract:
  Given a projective surface and a generic projection to the plane, the braid
monodromy factorization (and thus, the braid monodromy type) of the complement
of its branch curve is one of the most important topological invariants, stable
on deformations. From this factorization, one can compute the fundamental group
of the complement of the branch curve, either in C^2 or in CP^2. In this
article, we show that these groups, for the Hirzebruch surface F_{1,(a,b)}, are
almost-solvable. That is - they are an extension of a solvable group, which
strengthen the conjecture on degeneratable surfaces.


title:
Very large spontaneous electric polarization in BiFeO3 single crystals
  at room temperature and its evolution under cycling fields

abstract:
  Electric polarization loops are measured at room temperature on highly pure
BiFeO3 single crystals synthesized by a flux growth method. Because the
crystals have a high electrical resistivity, the resulting low leakage currents
allow us to measure a large spontaneous polarization reaching 100
microC.cm^{-2}, a value never reported in the bulk. During electric cycling,
the slow degradation of the material leads to an evolution of the hysteresis
curves eventually preventing full saturation of the crystals.


title: Asteroseismology of alpha Cen A. Evidence of rotational splitting

abstract:
  Asteroseismology provides a unique tool for studying stellar interiors.
Recently p modes have been detected on the bright solar-like star alpha Cen A
thanks to high-precision radial-velocity measurements. However a better
characterisation of these p modes is clearly needed to constrain theoretical
models. We observed alpha Cen A during five nights using the HARPS spectrograph
in order to improve our knowledge of the seismic properties of this star. We
performed high-precision radial-velocity sequences and computed the acoustic
spectrum of alpha Cen A. We identify 34 p modes with angular degree l=0-3 in
the frequency range 1.8-2.9 mHz and amplitude range 13-48 cm/s, in agreement
with previous seismic studies. We find an enhancement of the frequency scatter
with the angular degree l that indicates, considering the high inclination axis
of alpha Cen A, rotational splitting and explains the low values of previously
suggested mode lifetimes. We also derive new values for the small separations
that take the effect of rotational splitting into account . Our seismic study
of alpha Cen A leads to a list of now well identified p-mode frequencies and
shows the importance of taking the rotation into account in order to properly
characterise the p modes even in quite short campaigns.


title: Simple Combined Model for Nonlinear Excitations in DNA

abstract:
  We propose a new simple model for DNA denaturation bases on the pendulum
model of Englander\cite{A1} and the microscopic model of Peyrard {\it et
al.},\cite{A3} so called "combined model". The main parameters of our model
are: the coupling constant $k$ along each strand, the mean stretching $y^\ast$
of the hydrogen bonds, the ratio of the damping constant and driven force
$\gamma/F$. We show that both the length $L$ of unpaired bases and the velocity
$v$ of kinks depend on not only the coupling constant $k$ but also the
temperature $T$. Our results are in good agreement with previous works.


title: The Total Number of Giant Planets in Debris Disks with Central Clearings

abstract:
  Infrared spectra from the Spitzer Space Telescope (SSC) of many debris disks
are well fit with a single black body temperature which suggest clearings
within the disk. We assume that inside the clearing orbital instability due to
planets removes dust generating planetesimal belts and dust generated by the
outer disk that is scattered or drifts into the clearing. From numerical
integrations we estimate a minimum planet spacing required for orbital
instability (and so planetesimal and dust removal) as a function of system age
and planet mass. We estimate that a 10^8 year old debris disk with a dust disk
edge at a radius of 50 AU hosted by an A star must contain approximately 5
Neptune mass planets between the clearing radius and the iceline in order to
remove all primordial objects within it. We infer that known debris disk
systems contain at least a fifth of a Jupiter mass in massive planets. The
number of planets and spacing required is insensitive to the assumed planet
mass. However an order of magnitude higher total mass in planets could reside
in these systems if the planets are more massive.


title: Theory on Plasmon Modes of the Cell Membranes

abstract:
  Considering the plasmon oscillation of each layer of the cell membranes as a
quasi-particle, we introduce a simple model for the membrane collective charge
excitations, take into account the surface effective potential of the
plasmon-plasmon interaction between two layers. By using the useful Bogoliubov
transformation method, we easily obtained the expressions of the frequencies of
plasmon oscillations as a function of wave-number $k$ and membrane thickness
$d$, magnitude of these frequencies is in the order of $\sqrt{kd}$. Our results
are in good agreement with ones obtained by E. Manousakis.


title:
A classification of CO spaces which are continuous images of compact
  ordered spaces

abstract:
  A compact Hausdorff space X is called a CO space, if every closed subset of X
is homeomorphic to an open subset of X. Every successor ordinal with its order
topology is a CO space. We find an explicit characterization of the class K of
CO spaces which are a continuous image of a Dedkind complete totally ordered
set. (The topology of a totally ordered set is taken to be its order topology).
We show that every member of K can be described as a finite disjoint sum of
very simple spaces. Every summand has either form: (1) mu + 1 + nu^*, where mu
and nu are cardinals, and nu^* is the reverse order of nu; or (2) the summand
is the 1-point-compactification of a discrete space with cardinality aleph_1.


title:
Effects of Inelastic Neutrino-Nucleus Scattering on Supernova Dynamics
  and Radiated Neutrino Spectra

abstract:
  Based on the shell model for Gamow-Teller and the Random Phase Approximation
for forbidden transitions, we have calculated reaction rates for inelastic
neutrino-nucleus scattering (INNS) under supernova (SN) conditions, assuming a
matter composition given by Nuclear Statistical Equilibrium. The rates have
been incorporated into state-of-the-art stellar core-collapse simulations with
detailed energy-dependent neutrino transport. While no significant effect on
the SN dynamics is observed, INNS increases the neutrino opacities noticeably
and strongly reduces the high-energy tail of the neutrino spectrum emitted in
the neutrino burst at shock breakout. Relatedly the expected event rates for
the observation of such neutrinos by earthbound detectors are reduced by up to
about 60%.


title:
Continuation of connecting orbits in 3D-ODEs: (I) Point-to-cycle
  connections

abstract:
  We propose new methods for the numerical continuation of point-to-cycle
connecting orbits in 3-dimensional autonomous ODE's using projection boundary
conditions. In our approach, the projection boundary conditions near the cycle
are formulated using an eigenfunction of the associated adjoint variational
equation, avoiding costly and numerically unstable computations of the
monodromy matrix. The equations for the eigenfunction are included in the
defining boundary-value problem, allowing a straightforward implementation in
AUTO, in which only the standard features of the software are employed.
Homotopy methods to find connecting orbits are discussed in general and
illustrated with several examples, including the Lorenz equations. Complete
AUTO demos, which can be easily adapted to any autonomous 3-dimensional ODE
system, are freely available.


title: Wigner crystallization in a single and bilayer graphene

abstract:
  We study the possibility of Wigner crystallization in both single- and and
bi-layer graphene using a real space tight binding model. In addition to
verifying our earlier prediction for single layer graphene, we predict that the
bilayer graphene can undergo a Wigner crystal transition at low enough carrier
density thus offering a possibility of tunable and bipolar Wigner crystal. We
find that aside from the Coulomb interaction of the carriers of two layers that
stabilizes the charge ordered state, so does the inter layer coupling.


title: Direct observation of the strange b baryon Xi_b^{-}

abstract:
  We report the first direct observation of the strange b baryon Xi_b^{-}. We
reconstruct the decay Xi_b^{-} to J/psi Xi^{-}, with J/psi to dimuons and
Xi^{-} to Lambda pion, in ppbar collisions at sqrt(s) = 1.96 TeV. Using 1.3
fb^{-1} of data collected by the D0 detector, we observe 15.2 +/- 4.4(stat.)+
1.9/-0.4(syst.) Xi_b^{-} candidates at a mass of 5.774 +/- 0.011(stat.) +/-
0.015 (syst.) GeV. The significance of the observed signal is 5.5 sigmas,
equivalent to a probability of 3.3 X 10^{-8} of it arising from a background
fluctuation. Normalizing to the decay Lambda_b to J/psi Lambda, we measure the
relative rate to be 0.28 +/- 0.09(stat.)+ 0.09/-0.08 (syst.).


title: A Stochastic Measure for Eternal Inflation

abstract:
  We use the stochastic approach to investigate the measure for slow roll
eternal inflation. The probability for the universe of a given Hubble radius
can be calculated in this framework. In a solvable model, it is shown that the
probability for the universe to evolve from a state with a smaller Hubble
radius to that of a larger Hubble radius is dominated by the classical
probability without the stochastic source. While the probability for the
universe to evolve from a larger Hubble radius to a smaller one is suppressed
by $\exp(-\Delta S)$, where the de Sitter entropy $S$ arises naturally in this
stochastic approach.


title:
A Methodology for Efficient Space-Time Adapter Design Space Exploration:
  A Case Study of an Ultra Wide Band Interleaver

abstract:
  This paper presents a solution to efficiently explore the design space of
communication adapters. In most digital signal processing (DSP) applications,
the overall architecture of the system is significantly affected by
communication architecture, so the designers need specifically optimized
adapters. By explicitly modeling these communications within an effective
graph-theoretic model and analysis framework, we automatically generate an
optimized architecture, named Space-Time AdapteR (STAR). Our design flow inputs
a C description of Input/Output data scheduling, and user requirements
(throughput, latency, parallelism...), and formalizes communication constraints
through a Resource Constraints Graph (RCG). The RCG properties enable an
efficient architecture space exploration in order to synthesize a STAR
component. The proposed approach has been tested to design an industrial data
mixing block example: an Ultra-Wideband interleaver.