title:
Evolutionary dynamics of imatinib-treated leukemic cells by stochastic
  approach

abstract:
  The evolutionary dynamics of a system of cancerous cells in a model of
chronic myeloid leukemia (CML) is investigated by a statistical approach.
Cancer progression is explored by applying a Monte Carlo method to simulate the
stochastic behavior of cell reproduction and death in a population of blood
cells which can experience genetic mutations. In CML front line therapy is
represented by the tyrosine kinase inhibitor imatinib which strongly affects
the reproduction of leukemic cells only. In this work, we analyze the effects
of a targeted therapy on the evolutionary dynamics of normal, first-mutant and
cancerous cell populations. Several scenarios of the evolutionary dynamics of
imatinib-treated leukemic cells are described as a consequence of the efficacy
of the different modeled therapies. We show how the patient response to the
therapy changes when an high value of the mutation rate from healthy to
cancerous cells is present. Our results are in agreement with clinical
observations. Unfortunately, development of resistance to imatinib is observed
in a proportion of patients, whose blood cells are characterized by an
increasing number of genetic alterations. We find that the occurrence of
resistance to the therapy can be related to a progressive increase of
deleterious mutations.


title:
Polariton parametric photoluminescence in spatially inhomogeneous
  systems

abstract:
  A general theory of polariton parametric photoluminescence in spatially
inhomogeneous systems is developed. The quantum Langevin equations are solved
in a generalized Bogoliubov de Gennes approximation. We apply the formalism to
the specific case of a disordered microcavity. In this case, we numerically
solve the equations for the coherent emission and the photoluminescence. We
describe the effect of the exciton and photon disorder on the photoluminescence
pattern exhibited in momentum space, finding a good agreement with the
experimental observations.


title: The monopole mass in the random percolation gauge theory

abstract:
  We study the behaviour of the monopole at finite temperature in the
(2+1)-dimensional lattice gauge theory dual to the percolation model; by
exploiting the correspondences to statistical systems, we possess powerful
tools to evaluate the monopole mass both above and below the critical
temperature with high-precision Monte Carlo simulations.


title: Pattern formation during diffusion limited transformations in solids

abstract:
  We develop a description of diffusion limited growth in solid-solid
transformations, which are strongly influenced by elastic effects. Density
differences and structural transformations provoke stresses at interfaces,
which affect the phase equilibrium conditions. We formulate equations for the
interface kinetics similar to dendritic growth and study the growth of a stable
phase from a metastable solid in both a channel geometry and in free space. We
perform sharp interface calculations based on Green's function methods and
phase field simulations, supplemented by analytical investigations. For pure
dilatational transformations we find a single growing finger with symmetry
breaking at higher driving forces, whereas for shear transformations the
emergence of twin structures can be favorable. We predict the steady state
shapes and propagation velocities, which can be higher than in conventional
dendritic growth.


title:
A kinematic study of the irregular dwarf galaxy NGC 2366 using HI and
  Halpha observations

abstract:
  Abridged. Context. The metal content of dwarf galaxies and the metal
enrichment of the intergalactic medium both suggest that mass loss from
galaxies is a significant factor for the chemical evolution history of
galaxies, in particular of dwarf galaxies. However, no clear evidence of a
blow-away in local dwarf galaxies has been found so far.
  Aims. We therefore performed a detailed kinematic analysis of the neutral and
ionised gas in the nearby star-forming irregular dwarf galaxy NGC 2366 in order
to make predictions about the fate of the gas and to get a more complete
picture of this galaxy.
  Methods. A deep Halpha image and Fabry-Perot interferometric data of NGC 2366
were obtained. They were complemented by HI synthesis data from the THINGS
survey. We searched for line-splitting both in Halpha and HI by performing a
Gaussian decomposition. To get an idea whether the expansion velocities are
high enough for a gas blow-away, we used the pseudo-isothermal halo model,
which gives us realistic values for the escape velocities of NGC 2366. The good
data quality also allowed us to discuss some peculiarities of the morphology
and the dynamics in NGC 2366.
  Results. A large red-shifted outflow north west of the giant extragalactic
HII region with an expansion velocity of up to 50 km/s is found in Halpha, but
not in HI. Additionally, a blue-shifted component north of the giant
extragalactic HII region was detected both in Halpha and HI with an expansion
velocity of up to 30 km/s. A comparison with the escape velocities of NGC 2366
reveals that the gas does not have enough kinetic energy to leave the
gravitational potential.


title:
On the integral of $\log x\frac{dy}{y}-\log y\frac{dx}{x}$ over the
  A-polynomial curves

abstract:
  In this note, we study the integral of the 1-form $\log x\frac{dy}{y}-\log
y\frac{dx}{x}$ over certain plane curves defined by A-polynomials of knots. It
is quite surprising that a Chern-Simons type invariant of 3-manifolds, which
can be geometrically computed, may be used to get the exact values of those
integrals. The arithmetic nature of these integrals is still unknown at the
moment and deserved further investigation.


title: Spontaneous ordering against an external field in nonequilibrium systems

abstract:
  We study the collective behavior of nonequilibrium systems subject to an
external field with a dynamics characterized by the existence of
non-interacting states. Aiming at exploring the generality of the results, we
consider two types of models according to the nature of their state variables:
(i) a vector model, where interactions are proportional to the overlap between
the states, and (ii) a scalar model, where interaction depends on the distance
between states. In both cases the system displays three phases: two ordered
phases, one parallel to the field, and another orthogonal to the field; and a
disordered phase. The phase space is numerically characterized for each model
in a fully connected network. By placing the particles on a small-world
network, we show that, while a regular lattice favors the alignment with the
field, the presence of long-range interactions promotes the formation of the
ordered phase orthogonal to the field.


title:
Pion condensation in the two--flavor chiral quark model at finite
  baryochemical potential

abstract:
  Pion condensation is studied at one--loop level and nonzero baryochemical
potential in the framework of two flavor constituent quark model using the
one--loop level optimized perturbation theory for the resummation of the
perturbative series. A Landau type of analysis is presented for the
investigation of the phase boundary between the pion condensed/non-condensed
phases. The statement that the condensation starts at $\muI = m_{\pi}$ is
slightly modified by one--loop corrections. The second order critical surface
is determined and analysed in the $\muI-\muB-T$ space. The $\muI$ dependence of
the one--loop level charged pion pole masses is also studied.


title:
Analytical results for O(\alpha_s) radiative corrections to e+ e- ->
  tbar t(pol.) up to a given gluon energy cut

abstract:
  We determine the O(\alpha_s) radiative corrections to polarized top quark
pair production in e+ e- -annihilations with a specified gluon energy cut. We
write down fully analytical results for the unpolarized and polarized
O(\alpha_s) cross sections e+ e- -> tbar t (G) and e+ e- -> tbar t(pol.) (G)
including their polar orientation dependence relative to the beam direction. In
the soft gluon limit we recover the usual factorizing form known from the soft
gluon approximation. In the limit when the gluon energy cut takes its maximum
value we recover the totally inclusive unpolarized and polarized cross sections
calculated previously. We provide some numerical results on the cut-off
dependence of the various polarized and unpolarized cross sections and discuss
how the exact results numerically differ from the approximate soft-gluon
results.


title:
The breathing-mode giant monopole resonance and the surface
  compressibility in the relativistic mean-field theory

abstract:
  The breathing-mode isoscalar giant monopole resonance (GMR) is investigated
using the generator coordinate method within the relativistic mean-field (RMF)
theory. Employing the Lagrangian models of the nonlinear-$\sigma$ model
(NL$\sigma$), the scalar-vector interaction model (SVI) and the
$\sigma$-$\omega$ coupling model (SIGO), we show that each Lagrangian model
exhibits a distinctly different GMR response. Consequently, Lagrangian models
yield a different value of the GMR energy for a given value of the nuclear
matter incompressibility $K_\infty$. It is shown that this effect arises
largely from a different value of the surface incompressibility $K_{surf}$
inherent to each Lagrangian model, thus giving rise to the ratio
$K_{surf}/K_\infty$ which depends upon the Lagrangian model used. This is
attributed to a difference in the density dependence of the meson masses and
hence to the density dependence of the nuclear interaction amongst various
Lagrangian models. The sensitivity of the GMR energy to the Lagrangian model
used and thus emergence of a multitude of GMR energies for a given value of
$K_\infty$ renders the method of extracting $K_\infty$ on the basis of
interpolation amongst forces as inappropriate. As a remedy, the need to
'calibrate' the density dependence of the nuclear interaction in the RMF theory
is proposed.


title: Green's Functions and Topological Configurations

abstract:
  There are, among others, currently two important views on the
non-perturbative structure of Yang-Mills theory. One is through topological
configurations and one is through Green's functions, in particular their
(asymptotic) infrared behavior. Based on both views, various scenarios for
confinement, chiral symmetry breaking and other non-perturbative effects have
been developed. However, if both views are correct then they can only be
different aspects of the same underlying physics, and it must be possible to
relate them.
  After discussing the current status of the understanding of this connection,
smeared and cooled configurations in lattice gauge theory are used to determine
the properties of Green's functions in the low-momentum regime. It is found
that the qualitative properties are essentially unchanged compared to results
on unsmeared configurations. This is also the case when the configurations are
smeared sufficiently strongly to reach the almost (anti-)self-dual domain.


title: Topological Dynamics of Cellular Automata: Dimension Matters

abstract:
  Topological dynamics of cellular automata (CA), inherited from classical
dynamical systems theory, has been essentially studied in dimension 1. This
paper focuses on higher dimensional CA and aims at showing that the situation
is different and more complex starting from dimension 2. The main results are
the existence of non sensitive CA without equicontinuous points, the
non-recursivity of sensitivity constants, the existence of CA having only
non-recursive equicontinuous points and the existence of CA having only
countably many equicontinuous points. They all show a difference between
dimension 1 and higher dimensions. Thanks to these new constructions, we also
extend undecidability results concerning topological classification previously
obtained in the 1D case. Finally, we show that the set of sensitive CA is only
Pi_2 in dimension 1, but becomes Sigma_3-hard for dimension 3.


title: Kolmogorov cosmic microwave background sky

abstract:
  A new map of the sky representing the degree of randomness in the cosmic
microwave background (CMB) temperature has been obtained. The map based on
estimation of the Kolmogorov stochasticity parameter clearly distinguishes the
contribution of the Galactic disk from the CMB and reveals regions of various
degrees of randomness that can reflect the properties of inhomogeneities in the
Universe. For example, among the high randomness regions is the southern
non-Gaussian anomaly, the Cold Spot, with a stratification expected for the
voids. Existence of its counterpart, a Northern Cold Spot with almost identical
randomness properties among other low-temperature regions is revealed. By its
informative power, Kolmogorov's map can be complementary to the CMB temperature
and polarization sky maps.


title: Slow decay of Gibbs measures with heavy tails

abstract:
  We consider Glauber dynamics reversible with respect to Gibbs measures with
heavy tails. Spins are unbounded. The interactions are bounded and finite
range. The self potential enters into two classes of measures, $\kappa$-concave
probability measure and sub-exponential laws, for which it is known that no
exponential decay can occur. We prove, using coercive inequalities, that the
associated infinite volume semi-group decay to equilibrium polynomially and
stretched exponentially, respectively. Thus improving and extending previous
results by Bobkov and Zegarlinski.


title:
Detection of the tagged or untagged photons in acousto-optic imaging of
  thick highly scattering media by photorefractive adaptive holography

abstract:
  We propose an original adaptive wavefront holographic setup based on the
photorefractive effect (PR), to make real-time measurements of acousto-optic
signals in thick scattering media, with a high flux collection at high rates
for breast tumor detection. We describe here our present state of art and
understanding on the problem of breast imaging with PR detection of the
acousto-optic signal.


title:
Limit Theorems and Coexistence Probabilities for the Curie-Weiss Potts
  Model with an external field

abstract:
  The Curie-Weiss Potts model is a mean field version of the well-known Potts
model. In this model, the critical line $\beta = \beta_c (h)$ is explicitly
known and corresponds to a first order transition when $q > 2$. In the present
paper we describe the fluctuations of the density vector in the whole domain
$\beta \geqslant 0$ and $h \geqslant 0$, including the conditional fluctuations
on the critical line and the non-Gaussian fluctuations at the extremity of the
critical line. The probabilities of each of the two thermodynamically stable
states on the critical line are also computed. Similar results are inferred for
the Random-Cluster model on the complete graph.


title:
Episodic Magnetic Bubbles and Jets: Astrophysical Implications from
  Laboratory Experiments

abstract:
  Collimated outflows (jets) are ubiquitous in the universe appearing around
sources as diverse as protostars and extragalactic supermassive blackholes.
Jets are thought to be magnetically collimated, and launched from a magnetized
accretion disk surrounding a compact gravitating object. We have developed the
first laboratory experiments to address time-dependent, episodic phenomena
relevant to the poorly understood jet acceleration and collimation region. The
experimental results show the periodic ejections of magnetic bubbles naturally
evolving into a heterogeneous jet propagating inside a channel made of
self-collimated magnetic cavities. The results provide a unique view of the
possible transition from a relatively steady-state jet launching to the
observed highly structured outflows.


title:
Dilatation of a one-dimensional nonlinear crack impacted by a periodic
  elastic wave

abstract:
  The interactions between linear elastic waves and a nonlinear crack with
finite compressibility are studied in the one-dimensional context. Numerical
studies on a hyperbolic model of contact with sinusoidal forcing have shown
that the mean values of the scattered elastic displacements are discontinuous
across the crack. The mean dilatation of the crack also increases with the
amplitude of the forcing levels. The aim of the present theoretical study is to
analyse these nonlinear processes under a larger range of nonlinear jump
conditions. For this purpose, the problem is reduced to a nonlinear
differential equation. The dependence of the periodic solution on the forcing
amplitude is quantified under sinusoidal forcing conditions. Bounds for the
mean, maximum and minimum values of the solution are presented. Lastly,
periodic forcing with a null mean value is addressed. In that case, a result
about the mean dilatation of the crack is obtained.

categories: physics.class-ph math-ph math.DS math.MP


title: Uniformites et Continuity Spaces

abstract:
  A semigroup A is an abelian semigroup with identity 0. A set of positives in
A is an ordered down-directed set P containing with every r an element r/2 with
r/2 + r/2 = r. A continuity space is an abstract set X equipped with a map d :
XxX to A satisfying d(x, x) = 0 and d(x, z) d(x, y) + d(y, z). A quasi-uniform
space is an abstract set X equipped with a filterbase of binary relations {U}
such that each U contains the diagonal as well as for some V{U}. For each rP,
the set } is seen to be a quasi-uniform filterbase on X . Indeed, the
down-directedness of P ensures that U(r) is a filterbase of oversets of the
diagonal and U(r) contains U(r/2)U(r/2). One obtains a uniform filterbase by
symmetrization, i.e. by intersecting the U(r) with the U(s) = {(y, x)|d(y, x)
<s}.


title: Indistinguishability of independent single photons

abstract:
  The indistinguishability of independent single photons is presented by
decomposing the single photon pulse into the mixed state of different transform
limited pulses. The entanglement between single photons and outer environment
or other photons induces the distribution of the center frequencies of those
transform limited pulses and makes photons distinguishable. Only the single
photons with the same transform limited form are indistinguishable. In details,
the indistinguishability of single photons from the solid-state quantum emitter
and spontaneous parametric down conversion is examined with two-photon
Hong-Ou-Mandel interferometer. Moreover, experimental methods to enhance the
indistinguishability are discussed, where the usage of spectral filter is
highlighted.


title: On Superconformal Characters and Partition Functions in Three Dimensions

abstract:
  Possible short and semi-short positive energy, unitary representations of the
Osp(2N|4) superconformal group in three dimensions are discussed. Corresponding
character formulae are obtained, consistent with character formulae for the
SO(3,2) conformal group, revealing long multiplet decomposition at unitarity
bounds in a simple way. Limits, corresponding to reduction to various Osp(2N|4)
subalgebras, are taken in the characters that isolate contributions from fewer
states, at a given unitarity threshold, leading to considerably simpler
formulae. Via these limits, applied to partition functions, closed formulae for
the generating functions for numbers of BPS operators in the free field limit
of superconformal U(n)\times U(n) \N=6 Chern Simons theory and its supergravity
dual are obtained in the large n limit. Partial counting of semi-short
operators is performed and consistency between operator counting for the free
field and supergravity limits with long multiplet decomposition rules is
explicitly demonstrated. Partition functions counting certain protected scalar
primary semi-short operators, and their superconformal descendants, are
proposed and computed for large n. Certain chiral ring partition functions are
discussed from a combinatorial perspective.


title: On peeling procedure applied to a Poisson point process

abstract:
  In the focus of our attention is the asymptotic properties of the sequence of
convex hulls which arise as a result of a peeling procedure applied to the
convex hull generated by a Poisson point process. Processes of the considered
type are tightly connected with empirical point processes and stable random
vectors. Results are given about the limit shape of the convex hulls in the
case of a discrete spectral measure. We give some numerical experiments to
illustrate the peeling procedure for a more large class of Poisson point
processes.


title: Thermal degradation of ligno-cellulosic fuels: DSC and TGA studies

abstract:
  The scope of this work was to show the utility of thermal analysis and
calorimetric experiments to study the thermal oxidative degradation of
Mediterranean scrubs. We investigated the thermal degradation of four species;
DSC and TGA were used under air sweeping to record oxidative reactions in
dynamic conditions. Heat released and mass loss are important data to be
measured for wildland fires modelling purpose and fire hazard studies on
ligno-cellulosic fuels. Around 638 and 778 K, two dominating and overlapped
exothermic peaks were recorded in DSC and individualized using a experimental
and numerical separation. This stage allowed obtaining the enthalpy variation
of each exothermic phenomenon. As an application, we propose to classify the
fuels according to the heat released and the rate constant of each reaction.
TGA experiments showed under air two successive mass loss around 638 and 778 K.
Both techniques are useful in order to measure ignitability, combustibility and
sustainability of forest fuels.


title:
Application of feedback connection artificial neural network to seismic
  data filtering

abstract:
  The Elman artificial neural network (ANN) (feedback connection) was used for
seismic data filtering. The recurrent connection that characterizes this
network offers the advantage of storing values from the previous time step to
be used in the current time step. The proposed structure has the advantage of
training simplicity by a back-propagation algorithm (steepest descent). Several
trials were addressed on synthetic (with 10% and 50% of random and Gaussian
noise) and real seismic data using respectively 10 to 30 neurons and a minimum
of 60 neurons in the hidden layer. Both an iteration number up to 4000 and
arrest criteria were used to obtain satisfactory performances. Application of
such networks on real data shows that the filtered seismic section was
efficient. Adequate cross-validation test is done to ensure the performance of
network on new data sets.


title: Quiet Sun mini-CMEs activated by supergranular flows

abstract:
  Context: The atmosphere of the quiet Sun is controlled by photospheric flows
sweeping up concentrations of mixed polarity magnetic field. Along supergranule
boundaries and junctions, there is a strong correlation between magnetic flux
and bright chromospheric and transition region emission.
  Aim: The aim is to investigate the relationship between photospheric flows
and small flare-like brightenings seen in Extreme Ultraviolet images.
  Method: We describe observations of small eruptions seen in quiet Sun images
taken with the Extreme UltraViolet Imager (EUVI) on STEREO. The photospheric
flows during the eruption build-up phase are investigated by tracking granules
in high resolution MDI continuum images.
  Results: Eruptions with characteristics of small coronal mass ejections
(CMEs) occur at the junctions of supergranular cells. The eruptions produce
brightening at the onset site, dark cloud or small filament ejections, and
faint waves moving with plane-of-sky speeds up to 150 km/s. In the two examples
studied, they appear to be activated by converging and rotating supergranular
flows, twisting small concentrations of opposite polarity magnetic field. An
estimate of the occurrence rate is about 1400 events per day over the whole
Sun. One third of these events seem to be associated with waves. Typically, the
waves last for about 30 min and travel a distance of 100 arcsec, so at any one
time they cover 1/30th of the lower corona.


title: Classification of knotted tori in the 2-metastable dimension

abstract:
  This paper is on the classical Knotting Problem: for a given manifold N and a
number m describe the set of isotopy classes of embeddings N->S^m. We study the
specific case of knotted tori, i. e. the embeddings S^p x S^q -> S^m. The
classification of knotted tori up to isotopy in the metastable dimension range
m>p+3q/2+3/2, p<q+1, was given by A. Haefliger, E. Zeeman and A. Skopenkov. We
consider the dimensions below the metastable range, and give an explicit
criterion for the finiteness of this set of isotopy classes in the 2-metastable
dimension:
  Theorem. Assume that p+4q/3+2<m<p+3q/2+2 and m>2p+q+2. Then the set of smooth
embeddings S^p x S^q -> S^m up to isotopy is infinite if and only if either q+1
or p+q+1 is divisible by 4.
  Our approach to the classification is based on an analogue of the Koschorke
exact sequence from the theory of link maps. This sequence involves a new
beta-invariant of knotted tori. The exactness is proved using embedded surgery
and the Habegger-Kaiser techniques of studying the complement.


title: Gerbes and the Holomorphic Brauer Group of Complex Tori

abstract:
  The purpose of this paper is to develop the theory of holomorphic gerbes on
complex tori in a manner analogous to the classical theory for line bundles. In
contrast to past studies on this subject, we do not restrict to the case where
these gerbes are torsion or topologically trivial. We give an Appell-Humbert
type description of all holomorphic gerbes on complex tori. This gives an
explicit, simple, cocycle representative (and hence gerbe) for each equivalence
class of holomorphic gerbes. We also prove that a gerbe on the fiber product of
four spaces over a common base is trivial as long as it is trivial upon
restriction to any three out of the four spaces. A fine moduli stack for gerbes
on complex tori is constructed. This involves the construction of a
'Poincar\'e' gerbe which plays a role analogous to the role of the Poincar\'e
bundle in the case of line bundles.


title: Sunspots: from small-scale inhomogeneities towards a global theory

abstract:
  The penumbra of a sunspot is a fascinating phenomenon featuring complex
velocity and magnetic fields. It challenges both our understanding of radiative
magneto-convection and our means to measure and derive the actual geometry of
the magnetic and velocity fields. In this contribution we attempt to summarize
the present state-of-the-art from an observational and a theoretical
perspective.


title:
Scale-dependent bias induced by local non-Gaussianity: A comparison to
  N-body simulations

abstract:
  We investigate the effect of primordial non-Gaussianity of the local f_NL
type on the auto- and cross-power spectrum of dark matter haloes using
simulations of the LCDM cosmology. We perform a series of large N-body
simulations of both positive and negative f_NL, spanning the range between 10
and 100. Theoretical models predict a scale-dependent bias correction \Delta
b(k,f_NL) that depends on the linear halo bias b(M). We measure the power
spectra for a range of halo mass and redshifts covering the relevant range of
existing galaxy and quasar populations. We show that auto and cross-correlation
analyses of bias are consistent with each other. We find that for low
wavenumbers with k<0.03 h/Mpc the theory and the simulations agree well with
each other for biased haloes with b(M)>1.5. We show that a scale-independent
bias correction improves the comparison between theory and simulations on
smaller scales, where the scale-dependent effect rapidly becomes negligible.
The current limits on f_NL from Slosar et al. (2008) come mostly from very
large scales k<0.01 h/Mpc and, therefore, remain valid. For the halo samples
with b(M)<1.5-2 we find that the scale- dependent bias from non-Gaussianity
actually exceeds the theoretical predictions. Our results are consistent with
the bias correction scaling linearly with f_NL.


title: Effects of Uniform and Differential Rotation on Stellar Pulsations

abstract:
  We have investigated the effects of uniform rotation and a specific model for
differential rotation on the pulsation frequencies of 10 \Msun\ stellar models.
Uniform rotation decreases the frequencies for all modes. Differential rotation
does not appear to have a significant effect on the frequencies, except for the
most extreme differentially rotating models. In all cases, the large and small
separations show the effects of rotation at lower velocities than do the
individual frequencies. Unfortunately, to a certain extent, differential
rotation mimics the effects o f more rapid rotation, and only the presence of
some specific observed frequencies with well identified modes will be able to
uniquely constrain the internal rotation of pulsating stars.


title: IceCube Collaboration Contributions to ARENA 2008

abstract:
  Contributions of the IceCube Collaboration to the 3rd International Workshop
on Acoustic and Radio EeV Neutrino detection Activities (ARENA 2008). The
conference was held at Roma University "Sapienza," June 25-27, 2008, in Rome,
Italy. This is an html index of the IceCube Collaboration contributions, with
clickable links to the individual papers.


title: Dynamics of Gas-Fluidized Granular Rods

abstract:
  We study a quasi-two-dimensional monolayer of granular rods fluidized by a
spatially and temporally homogeneous upflow of air. By tracking the position
and orientation of the particles, we characterize the dynamics of the system
with sufficient resolution to observe ballistic motion at the shortest time
scales. Particle anisotropy gives rise to dynamical anisotropy and
superdiffusive dynamics parallel to the rod's long axis, causing the parallel
and perpendicular mean squared displacements to become diffusive on different
timescales. The distributions of free times and free paths between collisions
deviate from exponential behavior, underscoring the non-thermal character of
the particle motion. The dynamics show evidence of rotational-translational
coupling similar to that of an anisotropic Brownian particle. We model
rotational-translation coupling in the single-particle dynamics with a modified
Langevin model using non-thermal noise sources. This suggests a
phenomenological approach to thinking about collections of self-propelling
particles in terms of enhanced memory effects.


title:
Energy ejection in the collapse of a cold spherical self-gravitating
  cloud

abstract:
  When an open system of classical point particles interacting by Newtonian
gravity collapses and relaxes violently, an arbitrary amount of energy may in
principle be carried away by particles which escape to infinity. We investigate
here, using numerical simulations, how this released energy and other related
quantities (notably the binding energy and size of the virialized structure)
depends on the initial conditions, for the one parameter family of starting
configurations given by randomly distributing N cold particles in a spherical
volume. Previous studies have established that the minimal size reached by the
system scales approximately as N^{-1/3}, a behaviour which follows trivially
when the growth of perturbations (which regularize the singularity of the cold
collapse in the infinite N limit) are assumed to be unaffected by the
boundaries. Our study shows that the energy ejected grows approximately in
proportion to N^{1/3}, while the fraction of the initial mass ejected grows
only very slowly with N, approximately logarithmically, in the range of N
simulated. We examine in detail the mechanism of this mass and energy ejection,
showing explicitly that it arises from the interplay of the growth of
perturbations with the finite size of the system. A net lag of particles
compared to their uniform spherical collapse trajectories develops first at the
boundaries and then propagates into the volume during the collapse. Particles
in the outer shells are then ejected as they scatter through the time dependent
potential of an already re-expanding central core. Using modified initial
configurations we explore the importance of fluctuations at different scales,
and discreteness (i.e. non-Vlasov) effects in the dynamics.


title: Simultaneous NIR/sub-mm observation of flare emission from SgrA*

abstract:
  We report on a successful, simultaneous observation and modeling of the
sub-millimeter to near-infrared flare emission of the Sgr A* counterpart
associated with the super-massive black hole at the Galactic center. Our
modeling is based on simultaneous observations that have been carried out on 03
June, 2008 using the NACO adaptive optics (AO) instrument at the ESO VLT and
the LABOCA bolometer at the APEX telescope. Inspection and modeling of the
light curves show that the sub-mm follows the NIR emission with a delay of
1.5+/-0.5 hours. We explain the flare emission delay by an adiabatic expansion
of the source components.


title: A semantics for obligations

abstract: We analyze a number of properties obligations have or should have.


title:
Anomalous far infrared monochromatic transmission through a film of
  type-II superconductor in magnetic field

abstract:
  Anomalous far infrared monochromatic transmission through a lattice of
Abrikosov vortices in a type-II superconducting film is found and reported. The
transmitted frequency corresponds to the photonic mode localized by the defects
of the Abrokosov lattice. These defects are formed by extra vortices placed out
of the nodes of the ideal Abrokosov lattice. The extra vortices can be pinned
by crystal lattice defects of a superconductor. The corresponding frequency is
studied as a function of magnetic field and temperature in the framework of the
Dirac-type two-band model. While our approach is valid for all type-II
superconductors, the specific calculations have been performed for the
YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ (YBCO). The control of the transmitted
frequency by varying magnetic field and/or temperature is analyzed. It is
suggested that found anomalously transmitted localized mode can be utilized in
the far infrared monochromatic filters.


title: Quantum Thermodynamic Cycles and Quantum Heat Engines (II)

abstract:
  We study the quantum mechanical generalization of force or pressure, and then
we extend the classical thermodynamic isobaric process to quantum mechanical
systems. Based on these efforts, we are able to study the quantum version of
thermodynamic cycles that consist of quantum isobaric process, such as quantum
Brayton cycle and quantum Diesel cycle. We also consider the implementation of
quantum Brayton cycle and quantum Diesel cycle with some model systems, such as
single particle in 1D box and single-mode radiation field in a cavity. These
studies lay the microscopic (quantum mechanical) foundation for Szilard-Zurek
single molecule engine.


title: Studying the single--electron transistor by photoionization

abstract:
  We present theoretical results demonstrating that photoionization can be a
useful tool for investigating single--electron transistors. Suggestions are
given on how to conduct experiments using photoionization alone or in
combination with transport measurements.


title:
Effective Nonlinear Schr\"odinger Equations for Cigar-Shaped and
  Disk-Shaped Fermi Superfluids at Unitarity

abstract:
  In the case of tight transverse confinement (cigar-shaped trap) the
three-dimensional (3D) nonlinear Schr\"odinger equation, describing superfluid
Fermi atoms at unitarity (infinite scattering length $|a|\to \infty$), is
reduced to an effective one-dimensional form by averaging over the transverse
coordinates. The resultant effective equation is a 1D nonpolynomial Schrodinger
equation, which produces results in good agreement with the original 3D one. In
the limit of small and large fermion number $N$ the nonlinearity is of simple
power-law type. A similar reduction of the 3D theory to a two-dimensional form
is also performed for a tight axial confinement (disk-shaped trap). The
resultant effective 2D nonpolynomial equation also produces results in
agreement with the original 3D equation and has simple power-law nonlinearity
for small and large $N$. For both cigar- and disk-shaped superfluids our
nonpolynomial Schr\"odinger equations are quite attractive for phenomenological
application.


title:
A view of mathematics research productivity at U.S. regional public
  universities

abstract:
  Statistical summaries of certain kinds of mathematics research output are
given for a large sample of U.S. regional public universities. These
statistical summaries are reported using a variety of metrics that distinguish
between single-authored and collaborative work and account for publication
length.


title:
Study of the Gribov region in Euclidean Yang-Mills theories in the
  maximal Abelian gauge

abstract:
  The properties of the Gribov region in SU(2) Euclidean Yang-Mills theories in
the maximal Abelian gauge are investigated. This region turns out to be bounded
in all off-diagonal directions, while it is unbounded along the diagonal one.
The soft breaking of the BRST invariance due to the restriction of the domain
of integration in the path integral to the Gribov region is scrutinized. Owing
to the unboundedness in the diagonal direction, the invariance with respect to
Abelian transformations is preserved, a property which is at the origin of the
local U(1) Ward identity of the maximal Abelian gauge.


title: Renormalization flows in complex networks

abstract:
  Complex networks have acquired a great popularity in recent years, since the
graph representation of many natural, social and technological systems is often
very helpful to characterize and model their phenomenology. Additionally, the
mathematical tools of statistical physics have proven to be particularly
suitable for studying and understanding complex networks. Nevertheless, an
important obstacle to this theoretical approach is still represented by the
difficulties to draw parallelisms between network science and more traditional
aspects of statistical physics. In this paper, we explore the relation between
complex networks and a well known topic of statistical physics:
renormalization. A general method to analyze renormalization flows of complex
networks is introduced. The method can be applied to study any suitable
renormalization transformation. Finite-size scaling can be performed on
computer-generated networks in order to classify them in universality classes.
We also present applications of the method on real networks.


title:
Effective string theory constraints on the long distance behavior of the
  subleading potentials

abstract:
  The dynamics of heavy quarkonium systems in the strong coupling regime
reduces to a quantum mechanical problem with a number of potentials which may
be organized in powers of 1/m, m being the heavy quark mass. The potentials
must be calculated non-perturbatively, for instance in lattice QCD. It is well
known that the long distance behavior of the static (1/m^0) potential is well
reproduced by an effective string theory. We show that this effective string
theory, if correct, should also reproduce the long distance behavior of all 1/m
suppressed potentials. We demonstrate the practical usefulness of this result
by finding a suitable parameterization of the recently calculated 1/m
potential. We also calculate the 1/m^2 velocity dependent and spin dependent
potentials. Once Poincar\'e invariance is implemented, the shapes of most of
the spin independent potentials are fully predicted in terms of the string
tension, and the shapes of the spin dependent ones in terms of a single
parameter.


title:
Measurement of the eta->3pi0 Dalitz Plot Distribution with the WASA
  Detector at COSY

abstract:
  In the first production run of the WASA experiment at COSY, the eta decay
into three neutral pions was measured in proton-proton interactions at a proton
beam kinetic energy of 1.4 GeV. The Dalitz plot of the three pions was studied
using 1.2e5 fully reconstructed events, and the quadratic slope parameter alpha
was determined to be -0.027+/-0.008(stat)+/-0.005(syst). The result is
consistent with previous measurements and further corroborates the importance
of pion-pion final state interactions.


title: Directional detection of Dark Matter

abstract:
  Among the many experimental techniques available, those providing directional
information have the potential of yielding an unambiguous observation of WIMPs
even in the presence of insidious backgrounds. A measurement of the
distribution of arrival direction of WIMPs can also discriminate between
Galactic Dark Matter halo models. In this article, I will discuss the
motivation for directional detectors and review the experimental techniques
used by the various experiments. I will then describe one of them, the DMTPC
detector, in more detail.


title:
Two-particle irreducible effective action approach to nonlinear current
  conserving approximations in driven systems

abstract:
  Using closed-time path two-particle irreducible coarse-grained effective
action (CTP 2PI CGEA) techniques, we study the response of an open interacting
electronic system to time-dependent external electromagnetic fields. We show
that the CTP 2PI CGEA is invariant under a simultaneous gauge transformation of
the external field and the full Schwinger-Keldysh propagator, and that this
property holds even when the loop expansion of the CTP 2PI CGEA is truncated at
arbitrary order. The effective action approach provides a systematic way of
calculating the propagator and response functions of the system, via the
Schwinger-Dyson equation and the Bethe-Salpeter equations, respectively. We
show that, due to the invariance of the CTP 2PI CGEA under external gauge
transformations, the response functions calculated from it satisfy the
Ward-Takahashi hierarchy, thus warranting the conservation of the electronic
current beyond the expectation value level. We also clarify the connection
between nonlinear response theory and the WT hierarchy, and discuss an example
of an ad hoc approximation that violate it. These findings may be useful in the
study of current fluctuations in correlated electronic pumping devices.


title:
Representations of the general linear groups which are irreducible over
  subgroups

abstract:
  We classify all triples $(G,V,H)$ such that $SL_n(q)\leq G\leq GL_n(q)$, $V$
is a representation of $G$ of dimension greater than one over an algebraically
closed field $\FF$ of characteristic coprime to $q$, and $H$ is a proper
subgroup of $G$ such that the restriction $V\dar_{H}$ is irreducible. This
problem is a natural part of the Aschbacher-Scott program on maximal subgroups
of finite classical groups.


title:
Dark Matter Annihilation in the light of EGRET, HEAT, WMAP, INTEGRAL and
  ROSAT

abstract:
  The ROSAT Galactic wind observations confirm that our Galaxy launches
supernova driven Galactic winds with wind speeds of about 150 km/s in the
Galactic plane. Galactic winds of this strength are incompatible with current
isotropic models for Cosmic Ray transport. In order to reproduce our local CRs
in the presence of Galactic winds, charged CRs are required to be much more
localized than in the standard isotropic GALPROP models. This requires that
anisotropic diffusion is the dominant diffusion mode in the interstellar
medium, particularly that the diffusion in the disk and in the halo are
different. In addition small scale phenomena such as trapping by molecular
cloud complexes and the structure of our local environment might influence the
secondary CR production rate and our local CR density gradients. We introduce
an anisotropic convection driven transport model (aCDM) which is consistent
with the Galactic wind observations by ROSAT. This also explains the large
bulge/disk ratio as observed by INTEGRAL. Furthermore such models predict an
increase in the $e^+/(e^++e^-)$-fraction as observed by PAMELA and HEAT, if the
synchrotron constraints in the 408 MHz and WMAP range are taken into account.
No additional contribution from Dark Matter is required. The aCDM is able to
explain the absence of a positron annihilation signal from molecular clouds as
observed by INTEGRAL by virtue of a mechanism which confines and isotropizes
CRs between MCs. We find that the EGRET excess of diffuse $\gamma$-rays
currently cannot be explained by astrophysical effects in this type of model
and that the interpretation of the EGRET excess as Dark Matter annihilation is
perfectly consistent with all observational constraints from local CR fluxes
and synchrotron radiation.


title:
A partial analog of integrability theorem for distributions on p-adic
  spaces and applications

abstract:
  Let X be a smooth real algebraic variety. Let $\xi$ be a distribution on it.
One can define the singular support of $\xi$ to be the singular support of the
$D_X$-module generated by $\xi$ (some times it is also called the
characteristic variety). A powerful property of the singular support is that it
is a coisotropic subvariety of $T^*X$. This is the integrability theorem (see
[KKS, Mal, Gab]). This theorem turned out to be useful in representation theory
of real reductive groups (see e.g. [AG_AMOT, AS, Say]).
  The aim of this paper is to give an analog of this theorem to the
non-Archimedean case. The theory of D-modules is not available to us so we need
a different definition of the singular support. We use the notion wave front
set from [Hef] and define the singular support to be its Zariski closure. Then
we prove that the singular support satisfies some property that we call weakly
coisotropic, which is weaker than being coisotropic but is enough for some
applications. We also prove some other properties of the singular support that
were trivial in the Archimedean case (using the algebraic definition) but not
obvious in the non-Archimedean case.


title: Quantitative asymptotics of graphical projection pursuit

abstract:
  There is a result of Diaconis and Freedman which says that, in a limiting
sense, for large collections of high-dimensional data most one-dimensional
projections of the data are approximately Gaussian. This paper gives
quantitative versions of that result. For a set of deterministic vectors
$\{x_i\}_{i=1}^n$ in $\R^d$ with $n$ and $d$ fixed, let $\theta\in\s^{d-1}$ be
a random point of the sphere and let $\mu_n^\theta$ denote the random measure
which puts mass $\frac{1}{n}$ at each of the points
$\inprod{x_1}{\theta},...,\inprod{x_n}{\theta}$. For a fixed bounded Lipschitz
test function $f$, $Z$ a standard Gaussian random variable and $\sigma^2$ a
suitable constant, an explicit bound is derived for the quantity $\ds\P[|\int f
d\mu_n^\theta-\E f(\sigma Z)|>\epsilon]$. A bound is also given for
$\ds\P[d_{BL}(\mu_n^\theta, N(0,\sigma^2))>\epsilon]$, where $d_{BL}$ denotes
the bounded-Lipschitz distance, which yields a lower bound on the waiting time
to finding a non-Gaussian projection of the $\{x_i\}$ if directions are tried
independently and uniformly on $\s^{d-1}$.


title: An Improved Model of SiO Maser Emission in Miras

abstract:
  We describe a combined dynamic atmosphere and maser propagation model of SiO
maser emission in Mira variables. This model rectifies many of the defects of
an earlier model of this type, particularly in relation to the infra-red (IR)
radiation field generated by dust and various wavelength-dependent, optically
thick layers. Modelled masers form in rings with radii consistent with those
found in VLBI observations and with earlier models. This agreement requires the
adoption of a radio photosphere of radius approximately twice that of the
stellar photosphere, in agreement with observations. A radio photosphere of
this size renders invisible certain maser sites with high amplification at low
radii, and conceals high-velocity shocks, which are absent in radio continuum
observations. The SiO masers are brightest at an optical phase of 0.1 to 0.25,
which is consistent with observed phase-lags. Dust can have both mild and
profound effects on the maser emission. Maser rings, a shock and the optically
thick layer in the SiO pumping band at 8.13\micron appear to be closely
associated in three out of four phase samples.


title: Momentum exchange between light and a single atom: Abraham or Minkowski?

abstract:
  We consider the forces exerted by a pulse of plane-wave light on a single
atom. The leading edge of the pulse exerts a dispersive force on the atom, and
this modifies the atomic momentum while the atom is enveloped in the light. The
standard view of the optical dipole force indicates that red-detuned light
should attract the atom towards high intensity. This should increase the
average momentum per photon to $\textbf{p}_{0} n$, where $\textbf{p}_{0}$ is
the photon momentum in free space and $n$ is the average refractive index due
to the presence of the atom in the light. We show, however, that this is the
wrong conclusion and that the atom is in fact repelled from the light by the
dispersive forces, giving the photons a momentum $\textbf{p}_{0} /n$. This
leads us to identify Abraham's optical momentum with the kinetic momentum
transfer. The form due to Minkowski is similarly associated with the canonical
momentum. We consider the possibility of demonstrating this in the laboratory,
and we note an unexpected connection with the Aharonov-Casher effect.


title: General moment theorems for non-distinct unrestricted partitions

abstract:
  A well-known result from Hardy and Ramanujan gives an asymptotic expression
for the number of possible ways to express an integer as the sum of smaller
integers. In this vein, we consider the general partitioning problem of writing
an integer $n$ as a sum of summands from a given sequence $\gL$ of
non-decreasing integers. Under suitable assumptions on the sequence $\gL$, we
obtain results using associated zeta-functions and saddle-point techniques. We
also calculate higher moments of the sequence $\gL$ as well as the expected
number of summands. Applications are made to various sequences, including those
of Barnes and Epstein types. These results are of potential interest in
statistical mechanics in the context of Bose-Einstein condensation.

categories: math-ph cond-mat.stat-mech hep-th math.MP


title: On the $n\bar{n}$ transitions in the medium

abstract:
  The corrections to the model of $n\bar{n}$ transitions in the medium and
additional baryon-number-violating processes are considered. We focus on the
time-dependence since it is different for the $n\bar{n}$ transition followed by
annihilation (basic process) and processes mentioned above.


title: A minimalist two-level foundation for constructive mathematics

abstract:
  We present a two-level theory to formalize constructive mathematics as
advocated in a previous paper with G. Sambin. One level is given by an
intensional type theory, called Minimal type theory. This theory extends the
set-theoretic version introduced in the mentioned paper with collections. The
other level is given by an extensional set theory which is interpreted in the
first one by means of a quotient model. This two-level theory has two main
features: it is minimal among the most relevant foundations for constructive
mathematics; it is constructive thanks to the way the extensional level is
linked to the intensional one which fulfills the "proofs-as-programs" paradigm
and acts as a programming language.


title:
The AdS(4) x CP(3) string and its Bethe equations in the near plane wave
  limit

abstract:
  We perform a detailed study of bosonic type IIA string theory in a large
light-cone momentum / near plane wave limit of $AdS_4 \times CP_3$. In order to
attain this we derive the Hamiltonian up to cubic and quartic order in number
of fields and calculate the energies for string excitations in a $R\times S^2
\times S^2$ subspace. The computation for the string energies is performed for
arbitrary length excitations utilizing an unitary transformation which allows
us to remove the cubic terms in the Hamiltonian. We then rewrite a recent set
of proposed all loop Bethe equations in a light-cone language and compare their
predictions with the obtained string energies. We find perfect agreement.


title: On a damage-plasticity approach to model concrete failure

abstract:
  A damage-plasticity constitutive model for the description of fracture in
plain concrete is presented. Two approaches, the local model comprising the
adjustment of the softening modulus and the nonlocal model based on spatial
averaging of history variables, are applied to the analysis of a concrete bar
subjected to uniaxial tension and to a three-point bending test. The influence
of mesh size and the decomposition into damage and plasticity components are
discussed. It is shown that for the two examples studied, both approaches
result in mesh-independent results. However, the nonlocal model, which relies
on spatial averaging of history variables, exhibits sensitivity with respect to
boundary conditions, which requires further studies.


title: The Julia set of a post-critically finite endomorphism of PC^2

abstract:
  We construct a combinatorial model of the Julia set of the endomorphism $f(z,
w)=((1-2z/w)^2, (1-2/w)^2)$ of $PC^2$.


title: The mass formula for quasi-black holes

abstract:
  A quasi-black hole, either non-extremal or extremal, can be broadly defined
as the limiting configuration of a body when its boundary approaches the body's
quasihorizon. We consider the mass contributions and the mass formula for a
static quasi-black hole. The analysis involves careful scrutiny of the surface
stresses when the limiting configuration is reached. It is shown that there
exists a strict correspondence between the mass formulas for quasi-black holes
and pure black holes. This perfect parallelism exists in spite of the
difference in derivation and meaning of the formulas in both cases. For
extremal quasi-black holes the finite surface stresses give zero contribution
to the total mass. This leads to a very special version of Abraham-Lorentz
electron in general relativity in which the total mass has pure electromagnetic
origin in spite of the presence of bare stresses.


title: Concrete Constructions of Real Equiangular Line Sets

abstract:
  We give some concrete constructions of real equiangular line sets. The
emphasis here is on {\em building blocks} for certain angles which are then
used to build up larger equiangular line sets. We concentrate on angles greater
than or equal to 1/7.


title: Canonical Phase Measurements in the Presence of Photon Loss

abstract:
  We analyze the optimal state, as given by Berry and Wiseman [Phys. Rev. Lett
{\bf 85}, 5098, (2000)], under the canonical phase measurement in the presence
of photon loss. The model of photon loss is a generic fictitious beam splitter,
and we present the full density matrix calculations, which are more direct and
do not involve any approximations. We find for a given amount of loss the upper
bound for the input photon number that yields a sub-shot noise estimate.


title: A Giambelli formula for isotropic Grassmannians

abstract:
  Let X be a symplectic or odd orthogonal Grassmannian parametrizing isotropic
subspaces in a vector space equipped with a nondegenerate (skew) symmetric
form. We prove a Giambelli formula which expresses an arbitrary Schubert class
in H^*(X,Z) as a polynomial in certain special Schubert classes. We study theta
polynomials, a family of polynomials defined using raising operators whose
algebra agrees with the Schubert calculus on X. Furthermore, we prove that
theta polynomials are special cases of Billey-Haiman Schubert polynomials and
use this connection to express the former as positive linear combinations of
products of Schur Q-functions and S-polynomials.


title:
Brunet-Derrida behavior of branching-selection particle systems on the
  line

abstract:
  We consider a class of branching-selection particle systems on $\R$ similar
to the one considered by E. Brunet and B. Derrida in their 1997 paper "Shift in
the velocity of a front due to a cutoff". Based on numerical simulations and
heuristic arguments, Brunet and Derrida showed that, as the population size $N$
of the particle system goes to infinity, the asymptotic velocity of the system
converges to a limiting value at the unexpectedly slow rate $(\log N)^{-2}$. In
this paper, we give a rigorous mathematical proof of this fact, for the class
of particle systems we consider. The proof makes use of ideas and results by R.
Pemantle, and by N. Gantert, Y. Hu and Z. Shi, and relies on a comparison of
the particle system with a family of $N$ independent branching random walks
killed below a linear space-time barrier.


title:
Asymptotic stability and blow up for a semilinear damped wave equation
  with dynamic boundary conditions

abstract:
  In this paper we consider a multi-dimensional wave equation with dynamic
boundary conditions, related to the Kelvin-Voigt damping. Global existence and
asymptotic stability of solutions starting in a stable set are proved. Blow up
for solutions of the problem with linear dynamic boundary conditions with
initial data in the unstable set is also obtained.


title: Complete Characterization of Quantum-Optical Processes

abstract:
  The technologies of quantum information and quantum control are rapidly
improving, but full exploitation of their capabilities requires complete
characterization and assessment of processes that occur within quantum devices.
We present a method for characterizing, with arbitrarily high accuracy, any
quantum optical process. Our protocol recovers complete knowledge of the
process by studying, via homodyne tomography, its effect on a set of coherent
states, i.e. classical fields produced by common laser sources. We demonstrate
the capability of our protocol by evaluating and experimentally verifying the
effect of a test process on squeezed vacuum.


title: Chaos Phenotypes in Fluids

abstract:
  I shall briefly survey the current status on more rigorous studies of chaos
in fluids by focusing along the line of chaos phenotypes: sensitive dependence
on initial data, and recurrence.

categories: nlin.CD math.AP nlin.PS physics.ao-ph physics.flu-dyn


title: On billiard approach in multidimensional cosmological models

abstract:
  A short overview of the billiard approach for cosmological-type models with n
Einstein factor-spaces is presented. We start with the billiard representation
for pseudo-Euclidean Toda-like systems of cosmological origin. Then we consider
cosmological model with multicomponent "perfect-fluid" and cosmological-type
model with composite branes. The second one describes cosmological and
spherically-symmetric configurations in a theory with scalar fields and fields
of forms.
  The conditions for appearance of asymptotical Kasner-like and oscillating
behaviors in the limit \tau \to +0 and \tau \to + \infty (where \tau is a
"synchronous-type" variable) are formulated (e.g. in terms of inequalities on
Kasner parameters). Examples of billiards related to the hyperbolic Kac-Moody
algebras E_{10}, AE_3 and A_{1,II} are given.


title: Source of the observed thermodynamic arrow

abstract:
  The puzzle of the thermodynamic arrow of time reduces to the question of how
the universe could have had lower entropy in the past. I show that no special
entropy lowering mechanism (or fluctuation) is necessary. As a consequence of
expansion, at a particular epoch in the history of the universe a state that
was near maximum entropy under the dominant short range forces becomes
extremely unlikely, due to a switchover to newly dominant long range forces.
This happened at about the time of decoupling, prior to which I make no
statement about arrows. The role of cosmology in thermodynamics was first
suggested by T. Gold.


title:
Center stable manifolds for quasilinear parabolic pde and conditional
  stability of nonclassical viscous shock waves

abstract:
  Motivated by the study of conditional stability of traveling waves, we give
an elementary $H^2$ center stable manifold construction for quasilinear
parabolic PDE, sidestepping apparently delicate regularity issues by the
combination of a carefully chosen implicit fixed-point scheme and
"damping-type" $H^s$ energy estimates of a type familiar from the study of
hyperbolic--parabolic and relaxation systems. An important feature of these
methods is that they generalize to situations such as the hyperbolic--parabolic
or relaxation case for which parabolic-type smoothing estimates are
unavailable. As an application, we show conditional stability of Lax- or
undercompressive shock waves of general quasilinear parabolic systems of
conservation laws by a pointwise stability analysis on the center stable
manifold.


title: The Dust-to-Gas Ratio in the Small Magellanic Cloud Tail

abstract:
  The Tail region of the Small Magellanic Cloud (SMC) was imaged using the MIPS
instrument on the Spitzer Space Telescope as part of the SAGE-SMC Spitzer
Legacy. Diffuse infrared emission from dust was detected in all the MIPS bands.
The Tail gas-to-dust ratio was measured to be 1200 +/- 350 using the MIPS
observations combined with existing IRAS and HI observations. This gas-to-dust
ratio is higher than the expected 500-800 from the known Tail metallicity
indicating possible destruction of dust grains. Two cluster regions in the Tail
were resolved into multiple sources in the MIPS observations and local
gas-to-dust ratios were measured to be ~440 and ~250 suggests dust formation
and/or significant amounts of ionized gas in these regions. These results
support the interpretation that the SMC Tail is a tidal tail recently stripped
from the SMC that includes gas, dust, and young stars.


title: Comment on "Quantum bounce and cosmic recall" [arXiv:0710.4543]

abstract:
  A recently derived inequality on volume fluctuations of a bouncing cosmology,
valid for states which are semiclassical long after the bounce, does not
restrict pre-bounce fluctuations sufficiently strongly to conclude that the
pre-bounce state was semiclassical except in a very weak sense.


title:
Effects of multiple occupancy and inter-particle interactions on
  selective transport through narrow channels: theory versus experiment

abstract:
  Many biological and artificial transport channels function without direct
input of metabolic energy during a transport event and without structural
rearrangements involving transitions from a 'closed' to an 'open' state.
Nevertheless, such channels are able to maintain efficient and selective
transport. It has been proposed that attractive interactions between the
transported molecules and the channel can increase the transport efficiency and
that the selectivity of such channels can be based on the strength of the
interaction of the specifically transported molecules with the channel. Herein,
we study the transport through narrow channels in a framework of a general
kinetic theory, which naturally incorporates multi-particle occupancy of the
channel and non-single-file transport. We study how the transport efficiency
and the probability of translocation through the channel are affected by
inter-particle interactions in the confined space inside the channel, and
establish conditions for selective transport. We compare the predictions of the
model with the available experimental data - and find good semi-quantitative
agreement. Finally, we discuss applications of the theory to the design of
artificial nano-molecular sieves.


title:
A predictive bond order model connects covalent superconductivity,
  including cuprates, oxypnictides or HfN based materials

abstract:
  A phenomenological bond order model predicting doping curves [Tc vs doped
charge, c] of cuprates is found to have wider applicability. In this model Tc
is dependent on the density of electronic pair crystals [EC] in a covalently
bonding layer structure and on a layer Isolation factor, f [ECI model].
Characteristic doping curve events such as optima are correlated with a select
number of EC with pair repeats corresponding to multiples of lattice parameters
such as c=2/3x4=0.167, where 3x4 represent pair periodicity of 3a0 and 4b0. At
these EC all doped charge is converted into pairs according to c=2np. For Tc
prediction one writes Tc=2npfTe, where Te=600K and 300K as empirical constants
for hole and electron doping. Doping curves for YBa2Cu3Oy with their sharp
optima or kinks, separated by near linear ranges, or Tc plateaus on different
preparations, can express the stability of special EC. Examples are c=0.22=2/32
for the sharp optimum or the Tc=90K plateau, and c= 0.17 for the 60K plateau,
the latter depicting also the optimum for other systems such as La2-wSrwCuO4.
For oxypnictides R[O1-xFx]FeAs one writes Tc=300x and expects EC with optimal
dopings at x=0.11 and 0.17, as corroborated experimentally. Other examples
include HfN derivatives such as Li0.17HfNCl.


title:
Resolving the discrepancy between lensing and X-ray mass estimates of
  the complex galaxy cluster Abell 1689

abstract:
  There is a long-standing discrepancy between galaxy cluster masses determined
from X-ray and gravitational lensing observations of which Abell 1689 is a
well-studied example. In this work we take advantage of 180 ks of Chandra X-ray
observations and a new weak gravitational study based on a Hubble Space
Telescope mosaic covering the central 1.8 Mpc x 1.4 Mpc to eliminate the mass
discrepancy. In contrast to earlier X-ray analyses where the very circular
surface brightness has been inferred as Abell 1689 being spherically symmetric
and in hydrostatic equilibrium, a hardness ratio map analysis reveals a regular
and symmetric appearing main clump with a cool core plus some substructure in
the North Eastern part of the cluster. The gravitational lensing mass model
supports the interpretation of Abell 1689 being composed of a main clump, which
is possibly a virialized cluster, plus some substructure. In order to avoid
complications and mis-interpretations due to X-ray emission from the
substructure, we exclude it from the mass reconstruction. Comparing X-ray and
lensing mass profiles of the regular main part only, shows no significant
discrepancy between the two methods and the obtained mass profiles are
consistent over the full range where the mass can be reconstructed from X-rays
(out to approx. 1 Mpc). The obtained cluster mass within approx. 875 kpc
derived from X-rays alone is 6.4 plus/minus 2.1 x 10^14 solar masses compared
to a weak lensing mass of 8.6 plus/minus 3.0 x 10^14 solar masses within the
same radius.


title:
The Expected Detection of Dust Emission from High-Redshift Lyman Alpha
  Galaxies

abstract:
  Recent results have shown that a substantial fraction of high-redshift Lyman
alpha galaxies contain considerable amounts of dust. This implies that Lyman
alpha galaxies are not primordial, as has been thought in the past. However,
this dust has not been directly detected in emission; rather it has been
inferred based on extinction estimates from rest-frame ultraviolet (UV) and
optical observations. This can be tricky, as both dust and old stars redden
galactic spectra at the wavelengths used to infer dust. Measuring dust emission
directly from these galaxies is thus a more accurate way to estimate the total
dust mass, giving us real physical information on the stellar populations and
interstellar medium (ISM) enrichment. New generation instruments such as the
Atacama Large Millimeter Array (ALMA) and Sub-Millimeter Array (SMA), should be
able to detect dust emission from some of these galaxies in the sub-mm. Using
measurements of the UV spectral slopes, we derive far-infrared flux predictions
for of a sample of 23 z > 4 Lyman alpha galaxies. We find that in only a few
hours, we can detect dust emission from 39 +/- 22% of our Lyman alpha galaxies.
Comparing these results to those found from a sample of 21 Lyman break galaxies
(LBGs), we find that LBGs are on average 60% more likely to be detected than
Lyman alpha galaxies, implying that they are more dusty, and thus indicating an
evolutionary difference between these objects. These observations will provide
better constraints on dust in these galaxies than those derived from their UV
and optical fluxes alone. Undeniable proof of dust in these galaxies could
explain the larger than expected Lyman alpha equivalent widths seen in many
Lyman alpha galaxies today.


title: Stability of a Spherical Accretion Shock with Nuclear Dissociation

abstract:
  We examine the stability of a standing shock wave within a spherical
accretion flow onto a gravitating star, in the context of core-collapse
supernova explosions. Our focus is on the effect of nuclear dissociation below
the shock on the linear growth, and non-linear saturation, of non-radial
oscillations of the shocked fluid. We combine two-dimensional, time-dependent
hydrodynamic simulations using FLASH2.5 with a solution to the linear
eigenvalue problem, and demonstrate the consistency of the two approaches.
Previous studies of this `Standing Accretion Shock Instability' (SASI) have
focused either on zero-energy accretion flows without nuclear dissociation, or
made use of a detailed finite-temperature nuclear equation of state and
included strong neutrino heating. Our main goal in this and subsequent papers
is to introduce equations of state of increasing complexity, in order to
isolate the various competing effects. In this work we employ an ideal gas
equation of state with a constant rate of nuclear dissociation below the shock,
and do not include neutrino heating. We find that a negative Bernoulli
parameter below the shock significantly lowers the real frequency, growth rate,
and saturation amplitude of the SASI. A decrease in the adiabatic index has
similar effects. The non-linear development of the instability is characterized
by an expansion of the shock driven by turbulent kinetic energy at nearly
constant internal energy. Our results also provide further insight into the
instability mechanism: the rate of growth of a particular mode is fastest when
the radial advection time from the shock to the accretor overlaps with the
period of a standing lateral sound wave. The fastest-growing mode can therefore
be modified by nuclear dissociation.


title:
Chi-square and Poissonian Data: Biases Even in the High-Count Regime and
  How to Avoid them

abstract:
  We demonstrate that two approximations to the chi^2 statistic as popularly
employed by observational astronomers for fitting Poisson-distributed data can
give rise to intrinsically biased model parameter estimates, even in the high
counts regime, unless care is taken over the parameterization of the problem.
For a small number of problems, previous studies have shown that the fractional
bias introduced by these approximations is often small when the counts are
high. However, we show that for a broad class of problem, unless the number of
data bins is far smaller than \sqrt{N_c}, where N_c is the total number of
counts in the dataset, the bias will still likely be comparable to, or even
exceed, the statistical error. Conversely, we find that fits using Cash's
C-statistic give comparatively unbiased parameter estimates when the counts are
high. Taking into account their well-known problems in the low count regime, we
conclude that these approximate chi^2 methods should not routinely be used for
fitting an arbitrary, parameterized model to Poisson-distributed data,
irrespective of the number of counts per bin, and instead the C-statistic
should be adopted. We discuss several practical aspects of using the
C-statistic in modelling real data. We illustrate the bias for two specific
problems, measuring the count-rate from a lightcurve and obtaining the
temperature of a thermal plasma from its X-ray spectrum measured with the
Chandra X-ray observatory. In the context of X-ray astronomy, we argue the bias
could give rise to systematically mis-calibrated satellites and a ~5-10% shift
in galaxy cluster scaling relations.


title: Aetherizing Lambda: Barotropic Fluids as Dark Energy

abstract:
  We examine the class of barotropic fluid models of dark energy, in which the
pressure is an explicit function of the density, p = f(\rho). Through general
physical considerations we constrain the asymptotic past and future behaviors
and show that this class is equivalent to the sum of a cosmological constant
and a decelerating perfect fluid, or "aether", with w_{AE}\ge0. Barotropic
models give substantially disjoint predictions from quintessence, except in the
limit of \LambdaCDM. They are also interesting in that they simultaneously can
ameliorate the coincidence problem and yet "predict" a value of w\approx-1.


title: Probing condensate order in deep optical lattices

abstract:
  We study interacting bosons in optical lattices in the weak-tunneling regime
in systems that exhibit the coexistence of Mott-insulating and condensed
phases. We discuss the nature of the condensed ground state in this regime and
the validity of the mean-field treatment thereof. We suggest two experimental
signatures of condensate order in the system. (1) We analyze the hyperfine
configuration of the system and propose a set of experimental parameters for
observing radio-frequency spectra that would demonstrate the existence of the
condensed phase between Mott-insulating phases. We derive the structure of the
signal from the condensate in a typical trapped system, taking into account
Goldstone excitations, and discuss its evolution as a function of temperature.
(2) We study matter-wave interference patterns displayed by the system upon
release from all confining potentials. We show that as the density profiles
evolve very differently for the Mott-insulating phase and the condensed phase,
they can be distinguished from one another when the two phases coexist.


title: The Optical Frequency Comb as a One-Way Quantum Computer

abstract:
  In the one-way model of quantum computing, quantum algorithms are implemented
using only measurements on an entangled initial state. Much of the hard work is
done up-front when creating this universal resource, known as a cluster state,
on which the measurements are made. Here we detail a new proposal for a
scalable method of creating cluster states using only a single multimode
optical parametric oscillator (OPO). The method generates a continuous-variable
cluster state that is universal for quantum computation and encoded in the
quadratures of the optical frequency comb of the OPO. This work expands on the
presentation in Phys. Rev. Lett. 101, 130501 (2008).


title:
Parallel Chip-Firing on the Complete Graph: Devil's Staircase and
  Poincare Rotation Number

abstract:
  We study how parallel chip-firing on the complete graph K_n changes behavior
as we vary the total number of chips. Surprisingly, the activity of the system,
defined as the average number of firings per time step, does not increase
smoothly in the number of chips; instead it remains constant over long
intervals, punctuated by sudden jumps. In the large n limit we find a "devil's
staircase" dependence of activity on the number of chips. The proof proceeds by
reducing the chip-firing dynamics to iteration of a self-map of the circle S^1,
in such a way that the activity of the chip-firing state equals the Poincare
rotation number of the circle map. The stairs of the devil's staircase
correspond to periodic chip-firing states of small period.


title: Crystal Melting and Toric Calabi-Yau Manifolds

abstract:
  We construct a statistical model of crystal melting to count BPS bound states
of D0 and D2 branes on a single D6 brane wrapping an arbitrary toric Calabi-Yau
threefold. The three-dimensional crystalline structure is determined by the
quiver diagram and the brane tiling which characterize the low energy effective
theory of D branes. The crystal is composed of atoms of different colors, each
of which corresponds to a node of the quiver diagram, and the chemical bond is
dictated by the arrows of the quiver diagram. BPS states are constructed by
removing atoms from the crystal. This generalizes the earlier results on the
BPS state counting to an arbitrary non-compact toric Calabi-Yau manifold. We
point out that a proper understanding of the relation between the topological
string theory and the crystal melting involves the wall crossing in the
Donaldson-Thomas theory.


title: Bright High z SnIa: A Challenge for LCDM?

abstract:
  It has recently been pointed out by Kowalski et. al. (arxiv:0804.4142) that
there is `an unexpected brightness of the SnIa data at z>1'. We quantify this
statement by constructing a new statistic which is applicable directly on the
Type Ia Supernova (SnIa) distance moduli. This statistic is designed to pick up
systematic brightness trends of SnIa datapoints with respect to a best fit
cosmological model at high redshifts. It is based on binning the normalized
differences between the SnIa distance moduli and the corresponding best fit
values in the context of a specific cosmological model (eg LCDM). We then focus
on the highest redshift bin and extend its size towards lower redshifts until
the Binned Normalized Difference (BND) changes sign (crosses 0) at a redshift
z_c (bin size N_c). The bin size N_c of this crossing (the statistical
variable) is then compared with the corresponding crossing bin size N_{mc} for
Monte Carlo data realizations based on the best fit model. We find that the
crossing bin size N_c obtained from the Union08 and Gold06 data with respect to
the best fit LCDM model is anomalously large compared to N_{mc} of the
corresponding Monte Carlo datasets obtained from the best fit LCDM in each
case. In particular, only 2.2% of the Monte Carlo LCDM datasets are consistent
with the Gold06 value of N_c while the corresponding probability for the
Union08 value of N_c is 5.3%. Thus, according to this statistic, the
probability that the high redshift brightness bias of the Union08 and Gold06
datasets is realized in the context of a (w_0,w_1)=(-1,0) model (LCDM
cosmology) is less than 6%. The corresponding realization probability in the
context of a (w_0,w_1)=(-1.4,2) model is more than 30% for both the Union08 and
the Gold06 datasets.


title: Entanglement detection

abstract:
  How can one prove that a given state is entangled? In this paper we review
different methods that have been proposed for entanglement detection. We first
explain the basic elements of entanglement theory for two or more particles and
then entanglement verification procedures such as Bell inequalities,
entanglement witnesses, the determination of nonlinear properties of a quantum
state via measurements on several copies, and spin squeezing inequalities. An
emphasis is given on the theory and application of entanglement witnesses. We
also discuss several experiments, where some of the presented methods have been
implemented.


title:
The Generalized Green-Schwarz Mechanism for Type IIB Orientifolds with
  D3- and D7-Branes

abstract:
  In this paper, we work out in detail the tadpole cancellation conditions as
well as the generalized Green-Schwarz mechanism for type IIB orientifold
compactifications with D3- and D7-branes. We find that not only the well-known
D3- and D7-tadpole conditions have to be satisfied, but in general also the
vanishing of the induced D5-brane charges leads to a non-trivial constraint. In
fact, for the case $h^{1,1}_{-} \neq 0$ the latter condition is important for
the cancellation of chiral anomalies. We also extend our analysis by including
D9- as well as D5-branes and determine the rules for computing the chiral
spectrum of the combined system.


title:
MgII absorption systems and their neighbouring galaxies from a
  background subtraction technique

abstract:
  We estimate the absolute magnitude distribution of galaxies which lie within
about a Mpc of Mg II absorption systems. The absorption systems themselves lie
along 1880 lines of sight to QSOs from the Sloan Digital Sky Survey Data
Release 3, have rest equivalent widths greater than 0.88 Angstroms, and
redshifts between 0.37 < z < 0.82. Our measurement is based on all galaxies
which lie within a projected distance of about 900 kpc/h of each QSO
demonstrating absorption. The redshifts of these projected neighbors are not
available, so we use a background subtraction technique to estimate the
absolute magnitude distribution of true neighbors. (Our method exploits the
fact that, although we do not know the redshifts of the neighbors, we do know
the redshift of the absorbers.) The absolute magnitude distribution we find is
well described by a bell-shaped curve peaking at about rest-frame M_B = -20,
corresponding to L/L* = 1.4. A comparison of this observed distribution to ones
in the literature suggests that it is unlikely to be drawn from a population
dominated by late-type galaxies. However, the strong equivalent width systems
may be associated with later galaxy types. Finally we use the absolute
magnitude distribution, along with the observed covering fraction of about 8
percent, to estimate the extent of the MgII absorbing gas around a galaxy. For
an L* galaxy, this scale is about 70 kpc/h. We provide an analytic description
of our method, which is generally applicable to any dataset in which redshifts
are only available for a small sub-sample. Hence, we expect it to aid in the
analysis of galaxy scaling relations from photometric redshift datasets.


title: Logarithm laws for unipotent flows, I

abstract:
  We prove analogues of the logarithm laws of Sullivan and Kleinbock-Margulis
in the context of unipotent flows. In particular, we obtain results for
one-parameter actions on the space of lattices $SL(n, \R)/SL(n, \Z)$. The key
lemma for our results says the measure of the set of unimodular lattices in
$\R^n$ that does not intersect a `large' volume subset of $\R^n$ is `small'.
This can be considered as a `random' analogue of the classical Minkowski
theorem in the geometry of numbers.


title: F-SU(5)

abstract:
  We construct three flipped SU(5) X U(1)_X models from F-theory, and consider
two such models from free fermionic string model building. To achieve the
decoupling scenario in F-theory models and the string-scale gauge coupling
unification in free fermionic models, we introduce vector-like particles at the
TeV scale that can be observed at the Large Hadron Collider. We study gauge
coupling unification, and find that proton decay is within the reach of the
future Hyper-Kamiokande experiment. In these models, the doublet-triplet
splitting problem and monopole problem can be solved, the neutrino masses and
mixings can be explained via the double seesaw or seesaw mechanism, the
observed baryon asymmetry can be obtained through leptogenesis, the hybrid
inflation can be realized, and the correct cosmic primodial density
fluctuations can be generated.


title: A Nonseparably Connected Metric Space as a Dense Connected Graph

abstract:
  We present a connected metric space that does not contain any nontrivial
separable connected subspace. Our space is a dense connected graph of a
function from the real line satisfying Cauchy's equation.


title: Functional renormalization group approach to the Anderson impurity model

abstract:
  We develop a functional renormalization group approach which describes the
low-energy single-particle properties of the Anderson impurity model up to
intermediate on-site interactions $U \lesssim 15 \Delta$, where $\Delta$ is the
hybridization in the wide-band limit. Our method is based on a generalization
of a method proposed by Sch\"{u}tz, Bartosch and Kopietz [Phys. Rev. B 72,
035107 (2005)], using two independent Hubbard-Stratonovich fields associated
with transverse and longitudinal spin fluctuations. Although we do not
reproduce the exponentially small Kondo scale in the limit $U \to \infty$, the
spin fluctuations included in our approach remove the unphysical Stoner
instability predicted by mean-field theory for $U > \pi \Delta$. We discuss
different decoupling schemes and show that a decoupling which manifestly
respects the spin-rotational invariance of the problem gives rise to the lowest
quasiparticle weight. To obtain a closed flow equation for the fermionic
self-energy we also propose a new truncation scheme of the functional
renormalization group flow equations using Dyson-Schwinger equations to express
bosonic vertex functions in terms of fermionic ones.


title: Spin bath interactions effects on the geometric phase

abstract:
  We calculate the geometric phase of a spin-1/2 particle coupled to an
external environment comprising N spin-1/2 particle in the framework of open
quantum systems. We analyze the decoherence factor and the deviation of the
geometric phase under a nonunitary evolution from the one gained under an
unitary one. We show the dependence upon the system's and bath's parameter and
analyze the range of validity of the perturbative approximation. Finally, we
discuss the implications of our results.


title: The Shapes of Molecular Cloud Cores in Simulations and Observations

abstract:
  In this study, we investigate the shapes of starless and protostellar cores
using hydrodynamic, self-gravitating adaptive mesh refinement simulations of
turbulent molecular clouds. We simulate observations of these cores in dust
emission, including realistic noise and telescope resolution, and compare to
the observed core shapes measured in Orion by Nutter & Ward-Thompson (2007).
The simulations and the observations have generally high statistical
similarity, with particularly good agreement between simulations and Orion B.
Although protostellar cores tend to have semi-major axis to semi-minor axis
ratios closer to one, the distribution of axis ratios for starless and
protostellar cores are not significantly different for either the actual
observations of Orion or the simulated observations. Because of the high level
of agreement between the non-magnetic hydrodynamic simulations and observation,
contrary to a number of previous authors, one cannot infer the presence of
magnetic fields from core shape distributions.


title: Gauss's method for secular dynamics, softened

abstract:
  We show that the algorithm proposed by Gauss to compute the secular evolution
of gravitationally interacting Keplerian rings extends naturally to softened
gravitational interactions. The resulting tool is ideal for the study of the
secular dynamical evolution of nearly Keplerian systems such as stellar
clusters surrounding black holes in galactic nuclei, cometary clouds, or
planetesimal discs. We illustrate its accuracy, efficiency and versatility on a
variety of configurations. In particular, we examine a secularly unstable
unstable system of counter-rotating disks, and follow the unfolding and
saturation of the instability into a global, uniformly precessing, lopsided
(m=1) mode.


title: AdS_4 x CP^3 superstring and D=3 N=6 superconformal symmetry

abstract:
  Motivated by the isomorphism between osp(4|6) superalgebra and D=3 N=6
superconformal algebra we consider the superstring action on the AdS_4 x CP^3
background parametrized by D=3 N=6 super-Poincare and CP^3 coordinates
supplemented by the coordinates corresponoding to dilatation and superconformal
generators. It is also discussed the relation between the degeneracy of
fermionic equations of motion and the action kappa-invariance in the framework
of the supercoset approach.


title:
Semi-classical limit and minimum decoherence in the Conditional
  Probability Interpretation of Quantum Mechanics

abstract:
  The Conditional Probability Interpretation of Quantum Mechanics replaces the
abstract notion of time used in standard Quantum Mechanics by the time that can
be read off from a physical clock. The use of physical clocks leads to apparent
non-unitary and decoherence. Here we show that a close approximation to
standard Quantum Mechanics can be recovered from conditional Quantum Mechanics
for semi-classical clocks, and we use these clocks to compute the minimum
decoherence predicted by the Conditional Probability Interpretation.


title:
World Sheet Superstring and Superstring Field Theory: a new solution
  using Ultradistributions of Exponential Type

abstract:
  In this paper we show that Ultradistributions of Exponential Type (UET) are
appropriate for the description in a consistent way world sheet superstring and
superstring field theories. A new Lagrangian for the closed world sheet
superstring is obtained. We also show that the superstring field is a linear
superposition of UET of compact support (CUET), and give the notion of
anti-superstring. We evaluate the propagator for the string field, and
calculate the convolution of two of them.


title: Turbulence-Flame Interactions in Type Ia Supernovae

abstract:
  The large range of time and length scales involved in type Ia supernovae (SN
Ia) requires the use of flame models. As a prelude to exploring various options
for flame models, we consider, in this paper, high-resolution three-dimensional
simulations of the small-scale dynamics of nuclear flames in the supernova
environment in which the details of the flame structure are fully resolved. The
range of densities examined, 1 to $8 \times 10^7$ g cm$^{-3}$, spans the
transition from the laminar flamelet regime to the distributed burning regime
where small scale turbulence disrupts the flame. The use of a low Mach number
algorithm facilitates the accurate resolution of the thermal structure of the
flame and the inviscid turbulent kinetic energy cascade, while implicitly
incorporating kinetic energy dissipation at the grid-scale cutoff. For an
assumed background of isotropic Kolmogorov turbulence with an energy
characteristic of SN Ia, we find a transition density between 1 and $3 \times
10^7$ g cm$^{-3}$ where the nature of the burning changes qualitatively. By $1
\times 10^7$ g cm$^{-3}$, energy diffusion by conduction and radiation is
exceeded, on the flame scale, by turbulent advection. As a result, the
effective Lewis Number approaches unity. That is, the flame resembles a laminar
flame, but is turbulently broadened with an effective diffusion coefficient,
$D_T \sim u' l$, where $u'$ is the turbulent intensity and $l$ is the integral
scale. For the larger integral scales characteristic of a real supernova, the
flame structure is predicted to become complex and unsteady. Implications for a
possible transition to detonation are discussed.


title:
Anomalous diffusion in supercooled liquids: a long-range localisation in
  particle trajectories

abstract:
  A statistical analysis of the geometries of particle trajectories in the
supercooled liquid state is reported. We examine two structurally different
fragile glass-forming liquids simulated by molecular dynamics. In both liquids,
the trajectories are found to exhibit a long-range localisation distinct from
the short-range localisation within the cage of nearest neighbours. This novel
diffusion anomaly is interpreted as a result of the potential-energy landscape
topography of fragile glass-formers where the local energy minima coalesce into
metabasins - compact domains with low escape probability.


title: Epitaxial growth of graphene-like silicon nano-ribbons

abstract:
  Graphene, a flat monolayer of carbon atoms tightly packed into a
two-dimensional honeycomb lattice (a one atom thick graphite sheet), is
presently the hottest material in nanoscience and nanotechnology. Its
challenging hypothetical reflection in the silicon world is coined silicene;
Here, we have demonstrated that the silicon nano-wires self-aligned in a
massively parallel array recently observed by STM on Ag(110), are true silicene
nano-ribbons. Our calculations using density functional theory clearly show
that Si atoms tends to form hexagons on top the silver substrate in a
honeycomb, graphene-like arrangement.


title: Symplectic Spinors, Holonomy and Maslov Index

abstract:
  In this note it is shown that the Maslov Index for pairs of Lagrangian Paths
as introduced by Cappell, Lee and Miller appears by parallel transporting
elements of (a certain complex line-subbundle of) the symplectic spinorbundle
over Euclidean space, when pulled back to an (embedded) Lagrangian submanifold
$L$, along closed or non-closed paths therein. In especially, the CLM-Index mod
4 determines the holonomy group of this line bundle w.r.t. the
Levi-Civita-connection on $L$, hence its vanishing mod 4 is equivalent to the
existence of a trivializing parallel section. Moreover, it is shown that the
CLM-Index determines parallel transport in that line-bundle along arbitrary
paths when compared to the parallel transport w.r.t. to the canonical flat
connection of Euclidean space, if the Lagrangian tangent planes at the
endpoints either coincide or are orthogonal. This is derived from a result on
parallel transport of certain elements of the dual spinorbundle along closed or
endpoint-transversal paths.


title:
Measurement of the kT Distribution of Particles in Jets Produced in
  ppbar Collisions at s**(1/2)=1.96$-TeV

abstract:
  We present a measurement of the transverse momentum with respect to the jet
axis ($k_{T}$) of particles in jets produced in $p\bar p$ collisions at
$\sqrt{s}=1.96$ TeV. Results are obtained for charged particles within a cone
of opening angle 0.5 radians around the jet axis in events with dijet invariant
masses between 66 and 737 GeV/c$^{2}$. The experimental data are compared to
theoretical predictions obtained for fragmentation partons within the framework
of resummed perturbative QCD using the modified leading log and
next-to-modified leading log approximations. The comparison shows that trends
in data are successfully described by the theoretical predictions, indicating
that the perturbative QCD stage of jet fragmentation is dominant in shaping
basic jet characteristics.


title: On Analytic Perturbations of a Family of Feigenbaum-like Equations

abstract:
  We prove existence of solutions $(\phi,\lambda)$ of a family of of
Feigenbaum-like equations \label{family} \phi(x)={1+\eps \over \lambda}
\phi(\phi(\lambda x)) -\eps x +\tau(x), where $\eps$ is a small real number and
$\tau$ is analytic and small on some complex neighborhood of $(-1,1)$ and
real-valued on $\fR$. The family $(\ref{family})$ appears in the context of
period-doubling renormalization for area-preserving maps (cf. \cite{GK}).
  Our proof is a development of ideas of H. Epstein (cf \cite{Eps1},
\cite{Eps2}, \cite{Eps3}) adopted to deal with some significant complications
that arise from the presence of terms $\eps x +\tau(x)$ in the equation
$(\ref{family})$. The method relies on a construction of novel {\it a-priori}
bounds for unimodal functions which turn out to be very tight. We also obtain
good bounds on the scaling parameter $\lambda$.
  A byproduct of the method is a new proof of the existence of a
Feigenbaum-Coullet-Tresser function.


title:
Hawking radiation via anomaly cancelation for the black holes of
  five-dimensional minimal gauged supergravity

abstract:
  The anomaly cancelation method proposed by Wilczek et al. is applied to the
general charged rotating black holes in five-dimensional minimal gauged
supergravity. Thus Hawking temperature and fluxes are found. The Hawking
temperature obtained agrees with the surface gravity formula. The black holes
have charge and two unequal angular momenta and these give rise to appropriate
terms in the effective U(1) gauge field of the reduced (1+1)-dimensional
theory. In particular, it is found that the terms in this U(1) gauge field
correspond exactly to the correct electrostatic potential and the two angular
velocities on the horizon of the black holes, and so the results for the
Hawking fluxes derived here from the anomaly cancelation method are in complete
agreement with the ones obtained from integrating the Planck distribution.


title:
On "the complete basis set limit" and plane-wave methods in
  first-principles simulations of water

abstract:
  Water structure, measured by the height of the first peak in oxygen-oxygen
radial distributions, is converged with respect to plane-wave basis energy
cutoffs for ab initio molecular dynamics simulations, confirming the
reliability of plane-wave methods.


title: Plastic Deformation of 2D Crumpled Wires

abstract:
  When a single long piece of elastic wire is injected trough channels into a
confining two-dimensional cavity, a complex structure of hierarchical loops is
formed. In the limit of maximum packing density, these structures are described
by several scaling laws. In this paper it is investigated this packing process
but using plastic wires which give origin to completely irreversible structures
of different morphology. In particular, it is studied experimentally the
plastic deformation from circular to oblate configurations of crumpled wires,
obtained by the application of an axial strain. Among other things, it is shown
that in spite of plasticity, irreversibility, and very large deformations,
scaling is still observed.


title:
Partition Functions of Matrix Models as the First Special Functions of
  String Theory. II. Kontsevich Model

abstract:
  In arXiv:hep-th/0310113 we started a program of creating a reference-book on
matrix-model tau-functions, the new generation of special functions, which are
going to play an important role in string theory calculations. The main focus
of that paper was on the one-matrix Hermitian model tau-functions. The present
paper is devoted to a direct counterpart for the Kontsevich and Generalized
Kontsevich Model (GKM) tau-functions. We mostly focus on calculating resolvents
(=loop operator averages) in the Kontsevich model, with a special emphasis on
its simplest (Gaussian) phase, where exists a surprising integral formula, and
the expressions for the resolvents in the genus zero and one are especially
simple (in particular, we generalize the known genus zero result to genus one).
We also discuss various features of generic phases of the Kontsevich model, in
particular, a counterpart of the unambiguous Gaussian solution in the generic
case, the solution called Dijkgraaf-Vafa (DV) solution. Further, we extend the
results to the GKM and, in particular, discuss the p-q duality in terms of
resolvents and corresponding Riemann surfaces in the example of dualities
between (2,3) and (3,2) models.