title: Two-dimensional phase transition models and \lambda \phi^4 field theory

abstract:
  The overview is given of the results obtained recently in the course of
renormalization-group (RG) study of two-dimensional (2D) models. RG functions
of the two-dimensional n-vector \lambda \phi^4 Euclidean field theory are
written down up to the five-loop terms and perturbative series are resummed by
the Pade-Borel-Leroy techniques. An account for the five-loop term is shown to
shift the Wilson fixed point only briefly, leaving it outside the segment
formed by the results of the lattice calculations. This is argued to reflect
the influence of the non-analytical contribution to the \beta-function. The
evaluation of the critical exponents for n = 1, n = 0 and n = -1 in the
five-loop approximation and comparison of the results with known exact values
confirm the conclusion that non-analytical contributions are visible in two
dimensions. The estimates obtained on the base of pseudo-\epsilon expansions
originating from the 5-loop 2D RG series are also discussed.

categories: cond-mat.stat-mech hep-lat hep-ph hep-th


title: Gravitational Wave Background from Population III Stars

abstract:
  We estimate the gravitational wave (GW) background from Population III (Pop
III) stars using the results from our hydrodynamic simulations (Suwa et al.
2007). We calculate gravitational waveforms from matter motions and anisotropic
neutrino emissions for single Pop III stars. We find that the GW amplitudes
from matter motions are dominant until just after bounce, but those from
neutrinos dominate later on at frequencies below $\sim 10$ Hz in the GW
spectrum. Computing the overall signal produced by the ensemble of such Pop III
stars, we find that the resultant density parameter of the GW background peaks
at the amplitude of $\Omega_\mathrm{GW}\sim 10^{-10}$ in the frequency interval
$\sim 1-10$ Hz. We show that such signals, depending on the formation rate of
Pop III stars, can be within the detection limits of future planned
interferometers such as DECIGO and BBO in the frequency interval of $\sim
0.1-1$ Hz. Our results suggest that the detection of the GW background from Pop
III stars can be an important tool to supply the information about the star
formation history in the early universe.


title: Revised value of the eighth-order electron g-2

abstract:
  The contribution to the eighth-order anomalous magnetic moment (g-2) of the
electron from a set of diagrams without closed lepton loops is recalculated
using a new FORTRAN code generated by an automatic code generator. Comparing
the contributions of individual diagrams of old and new calculations, we found
an inconsistency in the old treatment of infrared subtraction terms in two
diagrams. Correcting this error leads to the revised value -1.9144 (35)
(alpha/pi)^4 for the eighth-order term. This theoretical change induces the
shift of the inverse of the fine structure constant by -6.41180(73)x10^{-7}.


title:
Shell Structure and $\rho$-Tensor Correlations in Density-Dependent
  Relativistic Hartree-Fock theory

abstract:
  A new effective interaction PKA1 with $\rho$-tensor couplings for the
density-dependent relativistic Hartree-Fock (DDRHF) theory is presented. It is
obtained by fitting selected empirical ground state and shell structure
properties. It provides satisfactory descriptions of nuclear matter and the
ground state properties of finite nuclei at the same quantitative level as
recent DDRHF and RMF models. Significant improvement on the single-particle
spectra is also found due to the inclusion of $\rho$-tensor couplings. As a
result, PKA1 cures a common disease of the existing DDRHF and RMF Lagrangians,
namely the artificial shells at 58 and 92, and recovers the realistic sub-shell
closure at 64. Moreover, the proper spin-orbit splittings and well-conserved
pseudo-spin symmetry are obtained with the new effective interaction PKA1. Due
to the extra binding introduced by the $\rho$-tensor correlations, the balance
between the nuclear attractions and the repulsions is changed and this
constitutes the physical reason for the improvement of the nuclear shell
structure.


title: Z_{12-I} Orbifold Compactification toward SUSY Standard Model

abstract:
  We explain the orbifold compactification in string models and present a
Z_{12-I} orbifold compactification toward supersymmetric standard models. We
also point out an effective R-parity from this string construction. The VEVs of
gauge singlets are chosen such that phenomenological constraints are satisfied.


title: Metric Embedding for Nearest Neighbor Classification

abstract:
  The distance metric plays an important role in nearest neighbor (NN)
classification. Usually the Euclidean distance metric is assumed or a
Mahalanobis distance metric is optimized to improve the NN performance. In this
paper, we study the problem of embedding arbitrary metric spaces into a
Euclidean space with the goal to improve the accuracy of the NN classifier. We
propose a solution by appealing to the framework of regularization in a
reproducing kernel Hilbert space and prove a representer-like theorem for NN
classification. The embedding function is then determined by solving a
semidefinite program which has an interesting connection to the soft-margin
linear binary support vector machine classifier. Although the main focus of
this paper is to present a general, theoretical framework for metric embedding
in a NN setting, we demonstrate the performance of the proposed method on some
benchmark datasets and show that it performs better than the Mahalanobis metric
learning algorithm in terms of leave-one-out and generalization errors.


title: Spin glasses and Stein's method

abstract:
  We introduce some applications of Stein's method in the high temperature
analysis of spin glasses. Stein's method allows the direct analysis of the
Gibbs measure without having to create a cavity. Another advantage is that it
gives limit theorems with total variation error bounds, although the bounds can
be suboptimal. A surprising byproduct of our analysis is a relatively
transparent explanation of the Thouless-Anderson-Palmer system of equations.
Along the way, we develop Stein's method for mixtures of two Gaussian
densities.


title: The Incidence of Highly-Obscured Star-Forming Regions in SINGS Galaxies

abstract:
  Using the new capabilities of the Spitzer Space Telescope and extensive
multiwavelength data from the Spitzer Infrared Nearby Galaxies Survey (SINGS),
it is now possible to study the infrared properties of star formation in nearby
galaxies down to scales equivalent to large HII regions. We are therefore able
to determine what fraction of large, infrared-selected star-forming regions in
normal galaxies are highly obscured and address how much of the star formation
we miss by relying solely on the optical portion of the spectrum. Employing a
new empirical method for deriving attenuations of infrared-selected
star-forming regions we investigate the statistics of obscured star formation
on 500pc scales in a sample of 38 nearby galaxies. We find that the median
attenuation is 1.4 magnitudes in H-alpha and that there is no evidence for a
substantial sub-population of uniformly highly-obscured star-forming regions.
The regions in the highly-obscured tail of the attenuation distribution
(A_H-alpha > 3) make up only ~4% of the sample of nearly 1800 regions, though
very embedded infrared sources on the much smaller scales and lower
luminosities of compact and ultracompact HII regions are almost certainly
present in greater numbers. The highly-obscured cases in our sample are
generally the bright, central regions of galaxies with high overall attenuation
but are not otherwise remarkable. We also find that a majority of the galaxies
show decreasing radial trends in H-alpha attenuation. The small fraction of
highly-obscured regions seen in this sample of normal, star-forming galaxies
suggests that on 500pc scales the timescale for significant dispersal or break
up of nearby, optically-thick dust clouds is short relative to the lifetime of
a typical star-forming region.


title:
Approximately-Universal Space-Time Codes for the Parallel, Multi-Block
  and Cooperative-Dynamic-Decode-and-Forward Channels

abstract:
  Explicit codes are constructed that achieve the diversity-multiplexing gain
tradeoff of the cooperative-relay channel under the dynamic decode-and-forward
protocol for any network size and for all numbers of transmit and receive
antennas at the relays.
  A particularly simple code construction that makes use of the Alamouti code
as a basic building block is provided for the single relay case.
  Along the way, we prove that space-time codes previously constructed in the
literature for the block-fading and parallel channels are approximately
universal, i.e., they achieve the DMT for any fading distribution. It is shown
how approximate universality of these codes leads to the first DMT-optimum code
construction for the general, MIMO-OFDM channel.


title: Largely deformed states of $^{13}$B

abstract:
  The excited states of $^{13}$B were studied with a method of antisymmetrized
molecular dynamics(AMD). The theoretical results suggest that the intruder
states with large deformations construct the rotational bands, $K^\pi=3/2^-$
and $K^\pi=1/2^+$, starting from 5 MeV and 8 MeV, respectively. The neutron
structure of the $K^\pi=3/2^-$ is analogous to the intruder ground state of
$^{12}$Be. In the predicted $K^\pi=1/2^+$ band, we found very exotic structure
with a proton intruder configuration. This proton intruder state has a larger
deformation than superdeformation. The band-head $1/2^+$ state is assigned to
the $1/2^+$(4.83 MeV), which was experimentally suggested to be the proton
intruder state because of the strong production via the proton-transfer to the
$^{12}$Be($0^+$) state in the $^4$He($^{12}$Be,$^{13}$B$\gamma$)$X$
experiments.


title: Axiomatic Foundations for the Principle of Entropy Increase

abstract:
  We show that the principle of entropy increase may be exactly founded on a
few axioms valid not only for quantum and classical statistics, but also for a
wide range of statistical processes.


title: A symmetric Finsler space with Chern connection

abstract:
  We define a symmetry for a Finsler space with Chern connection and
investigate its implementation and properties and find a relation between them
and flag curvature.


title: Experimental Estimates of Dephasing Time in Molecular Magnets

abstract:
  Muon spin relaxation measurements in isotropic molecular magnets (MM) with a
spin value S ranging from 7/2 to 27/2 are used to determine the magnitude and
origin of dephasing time $\tau_\phi$ of molecular magnets. It is found that
$\tau_\phi$ ~ 10 nsec with no S or ligand dependence. This indicates a nuclear
origin for the stochastic field. Since $\tau_\phi$ is a property of the
environment, we argue that it is a number common to similar types of MM.
Therefore, $\tau_\phi$ is shorter than the Zener and tunneling times of
anisotropic MM such as Fe8 or Mn4 for standard laboratory sweep rates. Our
findings call for a stochastic Landau-Zener theory in this particular case.


title: Interference in Bohmian Mechanics with Complex Action

abstract:
  In recent years, intensive effort has gone into developing numerical tools
for exact quantum mechanical calculations that are based on Bohmian mechanics.
As part of this effort we have recently developed as alternative formulation of
Bohmian mechanics in which the quantum action, S, is taken to be complex [JCP
{125}, 231103 (2006)]. In the alternative formulation there is a significant
reduction in the magnitude of the quantum force as compared with the
conventional Bohmian formulation, at the price of propagating complex
trajectories. In this paper we show that Bohmian mechanics with complex action
is able to overcome the main computational limitation of conventional Bohmian
methods -- the propagation of wavefunctions once nodes set in. In the vicinity
of nodes, the quantum force in conventional Bohmian formulations exhibits rapid
oscillations that pose severe difficulties for existing numerical schemes. We
show that within complex Bohmian mechanics, multiple complex initial conditions
can lead to the same real final position, allowing for the description of nodes
as a sum of the contribution from two or more crossing trajectories. The idea
is illustrated on the reflection amplitude from a one-dimensional Eckart
barrier. We believe that trajectory crossing, although in contradiction to the
conventional Bohmian trajectory interpretation, provides an important new tool
for dealing with the nodal problem in Bohmian methods.


title:
Unified derivation of Bohmian methods and the incorporation of
  interference effects

abstract:
  We present a unified derivation of Bohmian methods that serves as a common
starting point for the derivative propagation method (DPM), Bohmian mechanics
with complex action (BOMCA) and the zero-velocity complex action method
(ZEVCA). The unified derivation begins with the ansatz
$\psi=e^{\frac{iS}{\hbar}}$ where the action, $S$, is taken to be complex and
the quantum force is obtained by writing a hierarchy of equations of motion for
the phase partial derivatives. We demonstrate how different choices of the
trajectory velocity field yield different formulations such as DPM, BOMCA and
ZEVCA. The new derivation is used for two purposes. First, it serves as a
common basis for comparing the role of the quantum force in the DPM and BOMCA
formulations. Second, we use the new derivation to show that superposing the
contributions of real, crossing trajectories yields a nodal pattern essentially
identical to that of the exact quantum wavefunction. The latter result suggests
a promising new approach to deal with the challenging problem of nodes in
Bohmian mechanics.


title: Two-component model for the axial form factor of the nucleon

abstract:
  The axial form factor of the nucleon is studied in a two-component model
consisting of a three-quark intrinsic structure surrounded by a meson cloud.
The experimental data in the space-like region are well reproduced with a
minimal number of parameters. The results are similar to those obtained from a
dipole fit up to 1 GeV$^2$, but they surprisingly show a zero between 2 and 3
GeV$^2$. Such behavior, predicted by the present model completely disagrees
with the dipole parametrization. The theoretical expression for the form factor
is then analytically extrapolated to the time-like region, giving the first
predictions in this regime. This kinematical region is especially interesting
for present and future colliders.


title: Realistic solution to the tunneling time problem

abstract:
  There remains the old question of how long a quantum particle takes to tunnel
through a potential barrier higher than its incident kinetic energy. In this
article a solution of the question is proposed on the basis of a realistic
explanation of quantum mechanics. The explanation implies that the tunneling
particle has a certain chance to borrow enough energy from self-interference to
high-jump over the barrier. The root-mean-square velocity and the effective
tunneling time of an electron tunneling through a rectangular barrier are
numerically calculated. No superluminal effect (Hartman effect) is found for
the tunneling electron. Heisenberg's energy-time uncertainty relation for the
tunneling effect is verified by calculating an introduced coefficient
representing uncertainty. The present author argues that phase time, dwell time
and B\"{u}tticker-Landauer time are not appropriate expressions for the actual
transit time in a tunneling process. A quantum high-jumping model is presented
to resolve the paradox that kinetic energy of the tunneling particle is
negative and its momentum is imaginary.


title: On elliptic differential operators with shifts

abstract:
  We give an index formula for elliptic differential operators whose
coefficients include shifts forming an infinite group.


title: Homogeneous geodesics in homogeneous Finsler spaces

abstract:
  In this paper, we study homogeneous geodesics in homogeneous Finsler spaces.
We first give a simple criterion that characterizes geodesic vectors. We show
that the geodesics on a Lie group, relative to a bi-invariant Finsler metric,
are the cosets of the one-parameter subgroups. The existence of infinitely many
homogeneous geodesics on compact semi-simple Lie group is established. We
introduce the notion of naturally reductive homogeneous Finsler space. As a
special case, we study homogeneous geodesics in homogeneous Randers spaces.
Finally, we study some curvature properties of homogeneous geodesics. In
particular, we prove that the S-curvature vanishes along the homogeneous
geodesics.


title: Nonlinear elastic stress response in granular packings

abstract:
  We study the nonlinear elastic response of a two-dimensional material to a
localized boundary force, with the particular goal of understanding the
differences observed between isotropic granular materials and those with
hexagonal anisotropy. Corrections to the classical Boussinesq result for the
stresses in an infinite half-space of a linear, isotropic material are
developed in a power series in inverse distance from the point of application
of the force. The breakdown of continuum theory on scales of order of the grain
size is modeled with phenomenological parameters characterizing the strengths
of induced multipoles near the point of application of the external force. We
find that the data of Geng et al. on isotropic and hexagonal packings of
photoelastic grains can be fit within this framework. Fitting the hexagonal
packings requires a choice of elastic coefficients with hexagonal anisotropy
stronger than that of a simple ball and spring model. For both the isotropic
and hexagonal cases, induced dipole and quadrupole terms produce propagation of
stresses away from the vertical direction over short distances. The scale over
which such propagation occurs is significantly enhanced by the nonlinearities
that generate hexagonal anisotropy.


title: Charge Inversion of Divalent Ionic Solutions in Silica Channels

abstract:
  Recent experiments (F.H.J. Van Der Heyden et al., PRL 96, 224502 (2006)) of
streaming currents in silica nanochannels with divalent ions report charge
inversion, i.e. interfacial charges attracting counterions in excess of their
own nominal charge, in conflict with existing theoretical and simulation
results. We reveal the mechanism of charge inversion by using all-atomic
molecular dynamics simulations. Our results show excellent agreement with
experiments, both qualitatively and quantitatively. We further discuss the
implications of our study for the general problem of ionic correlations in
solutions as well as in regards of the properties of silica-water interfaces.


title: Wedderburn polynomials over division rings, II

abstract:
  A polynomial $f(t)$ in an Ore extension $K[t;S,D]$ over a division ring $K$
is a Wedderburn polynomial if $f(t)$ is monic and is the minimal polynomial of
an algebraic subset of $K$. These polynomials have been studied in "Wedderburn
polynomials over division rings,I (Journal of Pure and Applied Algebra, Vol.
186, (2004), 43-76). In this paper, we continue this study and give some
applications to triangulation, diagonalization and eigenvalues of matrices over
a division ring in the general setting of $(S,D)$-pseudo-linear
transformations. In the last section we introduce and study the notion of
$G$-algebraic sets which, in particular, permits generalization of Wedderburn's
theorem relative to factorization of central polynomials.


title: New Developments and Future Perspectives of Gaseous Detectors

abstract:
  Gaseous detectors are fundamental components of all present and planned high
energy physics experiments.
  Over the past decade two representatives (GEM, Micromegas) of the
Micro-Pattern Gas Detector (MPGD) concept have become increasingly important;
the high radiation resistance and excellent spatial and time resolution make
them an invaluable tool to confront future detector challenges at the next
generation of colliders.
  Novel structures where GEM and Micromegas are directly coupled to the CMOS
multi-pixel readout represent an exciting field and allow to reconstruct
fine-granularity, two-dimensional images of physics events. Originally
developed for the high energy physics, MPGD applications have expanded to
astrophysics, neutrino physics, neutron detection and medical imaging.


title: Phase structure of matrix quantum mechanics at finite temperature

abstract:
  We study matrix quantum mechanics at finite temperature by Monte Carlo
simulation. The model is obtained by dimensionally reducing 10d U(N) pure
Yang-Mills theory to 1d. Following Aharony et al., one can view the same model
as describing the high temperature regime of (1+1)d U(N) super Yang-Mills
theory on a circle. In this interpretation an analog of the deconfinement
transition was conjectured to be a continuation of the black-hole/black-string
transition in the dual gravity theory. Our detailed analysis in the critical
regime up to N=32 suggests the existence of the non-uniform phase, in which the
eigenvalue distribution of the holonomy matrix is non-uniform but gapless. The
transition to the gapped phase is of second order. The internal energy is
constant (giving the ground state energy) in the uniform phase, and rises
quadratically in the non-uniform phase, which implies that the transition
between these two phases is of third order.


title:
Towards lattice simulation of the gauge theory duals to black holes and
  hot strings

abstract:
  A generalization of the AdS/CFT conjecture postulates a duality between IIA
string theory and 16 supercharge Yang-Mills quantum mechanics in the large N 't
Hooft limit. At low temperatures string theory describes black holes, whose
thermodynamics may hence be studied using the dual quantum mechanics. This
quantum mechanics is strongly coupled which motivates the use of lattice
techniques. We argue that, contrary to expectation, the theory when discretized
naively will nevertheless recover continuum supersymmetry as the lattice
spacing is sent to zero. We test these ideas by studying the 4 supercharge
version of this Yang-Mills quantum mechanics in the 't Hooft limit. We use both
a naive lattice action and a manifestly supersymmetric action. Using Monte
Carlo methods we simulate the Euclidean theories, and study the lattice
continuum limit, for both thermal and non-thermal periodic boundary conditions,
confirming continuum supersymmetry is recovered for the naive action when
appropriate. We obtain results for the thermal system with N up to 12. These
favor the existence of a single deconfined phase for all non-zero temperatures.
These results are an encouraging indication that the 16 supercharge theory is
within reach using similar methods and resources.


title:
Triggering Mechanism for the Filament Eruption on 2005 September 13 in
  Active Region NOAA 10808

abstract:
  On 2005 September 13 a filament eruption accompanied by a halo CME occurred
in the most flare-productive active region NOAA 10808 in Solar Cycle 23. Using
multi-wavelength observations before the filament eruption on Sep. 13th, we
investigate the processes leading to the catastrophic eruption. We find that
the filament slowly ascended at a speed of 0.1km/s over two days before the
eruption. During slow ascending, many small flares were observed close to the
footpoints of the filament, where new magnetic elements were emerging. On the
basis of the observational facts we discuss the triggering mechanism leading to
the filament eruption. We suggest the process toward the eruption as follows:
First, a series of small flares played a role in changing the topology of the
loops overlying the filament. Second, the small flares gradually changed the
equilibrium state of the filament and caused the filament to ascend slowly over
two days. Finally, a C2.9 flare that occurred when the filament was close to
the critical point for loss of equilibrium directly led to the catastrophic
filament eruption right after itself.


title: On probabilities for separating sets of order statistics

abstract:
  Consider a set of order statistics that arise from sorting samples from two
different populations, each with their own, possibly different distribution
function. The probability that these order statistics fall in disjoint, ordered
intervals, and that of the smallest statistics, a certain number come from the
first populations, are given in terms of the two distribution functions. The
result is applied to computing the joint probability of the number of
rejections and the number of false rejections for the Benjamini-Hochberg false
discovery rate procedure.


title: Towards the Typology of Elections at Russia

abstract:
  A distinction in reasons and motives for choosing a particular political
leader establishes the key difference between older and young democracy. The
former is based on electoral history, while the latter is based on feelings and
personal attitude. Besides, a comparatively abundant number of political
figures (persons or parties and associations) is specific for young
democracies. The problem of a reference votes' distribution is analyzed.
Lefevbre's theory of a reflexive control is supposed to make the basis for
indifferent choice of political figures. This theory yields a golden section
split of votes (or the series of Fibonacci numbers, for the case of multiple
choice). A typology of political campaigns based on this theory is proposed. A
proximity of ratings of competing persons means the highest electoral tension,
a leadership of a person means a high level of mobilization; a neutral
situation corresponds to Fibonacci numbers distribution of votes.


title: A dynamical law for slow crack growth in polycarbonate films

abstract:
  We study experimentally the slow growth of a single crack in polycarbonate
films submitted to uniaxial and constant imposed stress. For this visco-plastic
material, we uncover a dynamical law that describes the dependence of the
instantaneous crack velocity with experimental parameters. The law involves a
Dugdale-Barenblatt static description of crack tip plastic zones associated to
an Eyring's law and an empirical dependence with the crack length that may come
from a residual elastic field.


title: There Exist some Omega-Powers of Any Borel Rank

abstract:
  Omega-powers of finitary languages are languages of infinite words
(omega-languages) in the form V^omega, where V is a finitary language over a
finite alphabet X. They appear very naturally in the characterizaton of regular
or context-free omega-languages. Since the set of infinite words over a finite
alphabet X can be equipped with the usual Cantor topology, the question of the
topological complexity of omega-powers of finitary languages naturally arises
and has been posed by Niwinski (1990), Simonnet (1992) and Staiger (1997). It
has been recently proved that for each integer n > 0, there exist some
omega-powers of context free languages which are Pi^0_n-complete Borel sets,
that there exists a context free language L such that L^omega is analytic but
not Borel, and that there exists a finitary language V such that V^omega is a
Borel set of infinite rank. But it was still unknown which could be the
possible infinite Borel ranks of omega-powers. We fill this gap here, proving
the following very surprising result which shows that omega-powers exhibit a
great topological complexity: for each non-null countable ordinal alpha, there
exist some Sigma^0_alpha-complete omega-powers, and some Pi^0_alpha-complete
omega-powers.


title:
Relative velocities among accreting planetesimals in binary systems: the
  circumbinary case

abstract:
  We numerically investigate the possibility of planetesimal accretion in
circumbinary disks, under the coupled influence of both stars' secular
perturbations and friction due to the gaseous component of the protoplanetary
disk. We focus on one crucial parameter: the distribution of encounter
velocities between planetesimals in the 0.5 to 100km size range. An extended
range of binary systems with differing orbital parameters is explored. The
resulting encounter velocities are compared to the threshold velocities below
which the net outcome of a collision is accumulation into a larger body instead
of mass erosion. For each binary configuration, we derive the critical radial
distance from the binary barycenter beyond which planetesimal accretion is
possible. This critical radial distance is smallest for equal-mass binaries on
almost circular orbits. It shifts to larger values for increasing
eccentricities and decreasing mass ratio. The importance of the planetesimals'
orbital alignments of planetesimals due to gas drag effects is discussed.


title:
Insights into the Evolution of Horizons from Non-Orthogonal Temporal
  Coordinates

abstract:
  The introduction of coordinates representing the points of view of various
observers results in the possibility of horizons when acceleration and
gravitation are included. A horizon is a surface of possible light beams in a
region of space of finite distance from the observer, which means that since
nothing travels faster than light, events on the far side of a horizon cannot
influence those on the causal side. A black hole has such a horizon, where some
radially outgoing light beams can never reach a distant (or even nearby)
observer. However, since one suspects that black holes can swallow energy, and
even evaporate by Hawking radiation, such horizons must take on a time
dependency. A naive introduction of temporal dependency results in infinities
(singularities) in energy densities, suggesting in such descriptions that an
in-falling observer would encounter a hard surface at the horizon. However, if
coordinates representing space-time as analogous to a "flowing river" are used
to describe the dynamics of a black hole, no such singularities are
encountered. Such a parameterization of time dependent horizons will be offered
in this presentation. A Penrose space-time diagram (which represents the entire
space-time on a finite diagram with light beams always moving at a 45 degree
angle to vertical) describing the growth and evaporation of an example black
hole, along with the resulting coordinate anomaly, will be constructed.


title: "No Information Without Disturbance": Quantum Limitations of Measurement

abstract:
  In this contribution I review rigorous formulations of a variety of
limitations of measurability in quantum mechanics. To this end I begin with a
brief presentation of the conceptual tools of modern measurement theory. I will
make precise the notion that quantum measurements necessarily alter the system
under investigation and elucidate its connection with the complementarity and
uncertainty principles.


title:
Model for monitoring of a charge qubit using a radio-frequency quantum
  point contact including experimental imperfections

abstract:
  The extension of quantum trajectory theory to incorporate realistic
imperfections in the measurement of solid-state qubits is important for quantum
computation, particularly for the purposes of state preparation and
error-correction as well as for readout of computations. Previously this has
been achieved for low-frequency (dc) weak measurements. In this paper we extend
realistic quantum trajectory theory to include radio frequency (rf) weak
measurements where a low-transparency quantum point contact (QPC), coupled to a
charge qubit, is used to damp a classical oscillator circuit. The resulting
realistic quantum trajectory equation must be solved numerically. We present an
analytical result for the limit of large dissipation within the oscillator
(relative to the QPC), where the oscillator slaves to the qubit. The rf+dc mode
of operation is considered. Here the QPC is biased (dc) as well as subjected to
a small-amplitude sinusoidal carrier signal (rf). The rf+dc QPC is shown to be
a low-efficiency charge-qubit detector, that may nevertheless be higher than
the dc-QPC (which is subject to 1/f noise).


title:
RF Shimming Pulses For Ex-Situ NMR Spectroscopy and Imaging Using B1
  Inhomogeneities

abstract:
  I describe a method for generating "shim pulses" for NMR spectroscopy and
imaging (MRI) by taking advantage of the inherent inhomogeneity in the static
and radiofrequency (RF) fields of a one-sided NMR system. The RF inhomogeneity
here is assumed, without loss of generality, to be a linear gradient. General
polynomials in the spatial variables can be generated using x, y and z RF
gradients using trains of hard pulses which result in linear combinations of
monomials xy, y^2, xz etc., and any desired scalings of these monomials. The
basic shim pulse is constructed using small tip angle approximations.


title: Mesoscopic fluctuations of spin currents

abstract:
  Spin currents may be generated by applying bias voltages V to the
nanostructures even in the absence of spin-active ferromagnetic interfaces.
Most theoretical proposals concentrate on a concrete spin-orbit interaction and
on the disorder-averaged effect. It remains underappreciated that any
spin-orbit interaction produces random spin currents with a typical amplitude
e^2 V/\hbar not affected by disorder. This work addresses such mesoscopic
fluctuations of spin currents for generic model of a nanostructure where
several quantum connectors meet in a single node. The analysis is performed in
the framework of recently developed quantum circuit theory of G_Q corrections
and reveals four distinct mechanisms of spin current fluctuations. The results
are elaborated for simple models of tunnel and ballistic connectors.


title:
Rescattering effects and the determination of the gluon density for x <<
  1

abstract:
  We consider the possible role of rescattering effects in the determination of
the gluon density for the LHC from DIS data. We discuss a method that uses
results of s-channel calculations to estimate these effects, and comment on
potential applications to diffractive and multi-parton interactions.


title:
On the Origin of the "Ridge" phenomenon induced by Jets in Heavy Ion
  Collisions

abstract:
  We argue that "ridge" in 2-particle correlation function associated with hard
trigger at RHIC heavy ion collisions is naturally explained by an interrelation
of jet quenching and hydrodynamical transverse flow. The excess particles
forming the ridge are produced by QCD bremsstrahlung along the beam (and thus
have wide rapidity distribution) and then boosted by transverse flow.
Nontrivial correlation between directions of the jet and the radial flow is
provided by jet quenching: our straightforward and basically
parameter-independent calculation reproduces the angular shape, width and other
properties of the "ridge".


title: On the Sharpness and Bias of Quantum Effects

abstract:
  The question of quantifying the sharpness (or unsharpness) of a quantum
mechanical effect is investigated. Apart from sharpness, another property,
bias, is found to be relevant for the joint measurability or coexistence of two
effects. Measures of bias will be defined and examples given.


title: Rotational dynamics of a superhelix towed in a Stokes fluid

abstract:
  Motivated by the intriguing motility of spirochetes (helically-shaped
bacteria that screw through viscous fluids due to the action of internal
periplasmic flagella), we examine the fundamental fluid dynamics of
superhelices translating and rotating in a Stokes fluid. A superhelical
structure may be thought of as a helix whose axial centerline is not straight,
but also a helix. We examine the particular case where these two superimposed
helices have different handedness, and employ a combination of experimental,
analytic, and computational methods to determine the rotational velocity of
superhelical bodies being towed through a very viscous fluid. We find that the
direction and rate of the rotation of the body is a result of competition
between the two superimposed helices; for small axial helix amplitude, the body
dynamics is controlled by the short-pitched helix, while there is a cross-over
at larger amplitude to control by the axial helix. We find far better, and
excellent, agreement of our experimental results with numerical computations
based upon the method of Regularized Stokeslets than upon the predictions of
classical resistive force theory.


title: Dynamic metastability in the two-dimensional Potts ferromagnet

abstract:
  We investigate the non-equilibrium dynamics of the 2D Potts model on the
square lattice after a quench below the discontinuous transition point. By
means of numerical simulations of systems with q =12,24 and 48 we observe the
onset of a stationary regime below the temperature-driven transition, in a
temperature interval decreasing with the system size and increasing with q.
These results obtained dynamically agree with those obtained from the
analytical continuation of the free energy (Meunier and Morel, 2000), from
which metastability in the 2D Potts model results to be a finite size effect.


title: Avoidable Sets in The Bicyclic Inverse Semigroup

abstract:
  A subset $U$ of a set $S$ with a binary operation is called {\it avoidable}
if $S$ can be partitioned into two subsets $A$ and $B$ such that no element of
$U$ can be written as a product of two distinct elements of $A$ or as the
product of two distinct elements of $B$. The avoidable sets of the bicyclic
inverse semigroup are classified.


title: Stokes trapping and planet formation

abstract:
  It is believed that planets are formed by aggregation of dust particles
suspended in the turbulent gas forming accretion disks around developing stars.
We describe a mechanism, termed 'Stokes trapping', by which turbulence limits
the growth of aggregates of dust particles, so that their Stokes number
(defined as the ratio of the damping time of the particles to the Kolmogorov
dissipation timescale) remains close to unity. We discuss possible mechanisms
for avoiding this barrier to further growth. None of these is found to be
satisfactory and we introduce a new theory which does not involve the growth of
small clusters of dust grains.


title: The Yang Mills system and cyclic covering of abelian varieties

abstract:
  In this paper, we consider a dynamical system related to the Yang-Mills
system for a field with gauge group SU(2). We solve this system in terms of
genus two hyperelliptic functions and we show that it is algebraic completely
integrable in the generalized sense.


title:
Some solutions with torsion in Chern-Simons gravity and observable
  effects

abstract:
  It is shown that in all odd dimensional Chern-Simons theories states in which
the torsion is non zero (but it can approach smoothly to zero outside suitable
regions) do exist. Some possible observational effects related to neutrino
oscillations are pointed out. In the theory of continuum media (in which
suitable defects can be described by localized non vanishing torsion) "the
gravitational intuition" is a rather useful tool to describe the physical
effects of such defects. A possible astrophysical application is shortly
described.


title: The diameter of random Cayley digraphs of given degree

abstract:
  We consider random Cayley digraphs of order $n$ with uniformly distributed
generating set of size $k$. Specifically, we are interested in the asymptotics
of the probability such a Cayley digraph has diameter two as $n\to\infty$ and
$k=f(n)$. We find a sharp phase transition from 0 to 1 at around $k = \sqrt{n
\log n}$. In particular, if $f(n)$ is asymptotically linear in $n$, the
probability converges exponentially fast to 1.


title:
Finite Element Formulation of the Bloch Equations with Dipolar Field
  Effects

abstract:
  A Galerkin finite element (FEM) formulation for the Bloch equations with
dipolar field is presented which makes possible the derivation of weak
solutions to the Bloch equations. The FEM formulation has the advantage that
the equations of motion are local in real space, eliminating the global
truncation errors associated with calculations of the dipolar field in Fourier
space. The dipolar field and other geometric parameters are calculated only
once, before the simulation, and used as an initial condition rather than
re-calculated at every time step of some numerical integration.


title: Beyond Gross-Pitaevskii Mean Field Theory

abstract:
  A large number of effects related to the phenomenon of Bose-Einstein
Condensation (BEC) can be understood in terms of lowest order mean field
theory, whereby the entire system is assumed to be condensed, with thermal and
quantum fluctuations completely ignored. Such a treatment leads to the
Gross-Pitaevskii Equation (GPE) used extensively throughout this book. Although
this theory works remarkably well for a broad range of experimental parameters,
a more complete treatment is required for understanding various experiments,
including experiments with solitons and vortices. Such treatments should
include the dynamical coupling of the condensate to the thermal cloud, the
effect of dimensionality, the role of quantum fluctuations, and should also
describe the critical regime, including the process of condensate formation.
The aim of this Chapter is to give a brief but insightful overview of various
recent theories, which extend beyond the GPE. To keep the discussion brief,
only the main notions and conclusions will be presented. This Chapter
generalizes the presentation of Chapter 1, by explicitly maintaining
fluctuations around the condensate order parameter. While the theoretical
arguments outlined here are generic, the emphasis is on approaches suitable for
describing single weakly-interacting atomic Bose gases in harmonic traps.
Interesting effects arising when condensates are trapped in double-well
potentials and optical lattices, as well as the cases of spinor condensates,
and atomic-molecular coupling, along with the modified or alternative theories
needed to describe them, will not be covered here.


title: Odd-frequency Pairs and Josephson Current through a Strong Ferromagnet

abstract:
  We study Josephson current in superconductor / diffusive ferromagnet
/superconductor junctions by using the recursive Green function method. When
the exchange potential in a ferromagnet is sufficiently large as compared to
the pair potential in a superconductor, an ensemble average of Josephson
current is much smaller than its mesoscopic fluctuations. The Josephson current
vanishes when the exchange potential is extremely large so that a ferromagnet
is half-metallic. Spin-flip scattering at junction interfaces drastically
changes the characteristic behavior of Josephson current. In addition to
spin-singlet Cooper pairs, equal-spin triplet pairs penetrate into a half
metal. Such equal-spin pairs have an unusual symmetry property called
odd-frequency symmetry and carry the Josephson current through a half metal.
The penetration of odd-frequency pairs into a half metal enhances the low
energy quasiparticle density of states, which could be detected experimentally
by scanning tunneling spectroscopy. We will also show that odd-frequency pairs
in a half metal cause a nonmonotonic temperature dependence of the critical
Josephson current.


title:
Study of \pi^{-}p \to \eta n at low energies in a chiral constituent
  quark model

abstract:
  A chiral quark model approach is extended to the study of the $\pi N$
scattering at low energies. The process of $\pi^{-}p \to \eta n$ near threshold
is investigated. The model is successful in describing the differential cross
sections and total cross section near the $\eta$ production threshold. The
roles of the resonances in $n\leq 2$ shells are clarified. Near threshold, the
$S_{11}(1535)$ dominates the reactions, while the interferences from the
$S_{11}(1650)$ turn out to be destructive around $W\lesssim 1.6$ GeV. The
$D_{13}(1520)$ is crucial to give correct shapes of the differential cross
sections. The nucleon pole term contributions are significant. The
$P_{11}(1710)$ plays an important role around the c.m. energy $W=1.7$ GeV, it
is crucial to produce an enhancement in the region of $W>1.6$ GeV as suggested
by the data for total cross section. The $t$-channel is negligible in the
reactions.


title: The Origin of Large-scale HI structures in the Magellanic Bridge

abstract:
  We investigate the formation of a number of key large-scale HI features in
the ISM of the Magellanic Bridge using dissipationless numerical simulation
techniques. This study comprises the first direct comparison between detailed
HI maps of the Bridge and numerical simulations. We confirm that the SMC forms
two tidal filaments: a near arm, which forms the connection between the SMC and
LMC, and a counterarm. We show that the HI of the most dense part of the Bridge
can become arranged into a bimodal configuration, and that the formation of a
"loop" of HI, located off the North-Eastern edge of the SMC can be reproduced
simply as a projection of the counter-arm, and without invoking localised
energy-deposition processes such as SNe or stellar winds.


title: Cohen-Macaulayness and computation of Newton graded toric rings

abstract:
  Let $H$ be a positive semigroup in $\mathbb{Z}^d$ generated by $A$, and let
$K[H]$ be the associated semigroup ring over a field $K$. We investigate
heredity of the Cohen-Macaulay property from $K[H]$ to both its $A$-Newton
graded ring and to its face rings. We show by example that neither one inherits
in general the Cohen-Macaulay property. On the positive side we show that for
every $H$ there exist generating sets $A$ for which the Newton graduation
preserves Cohen-Macaulayness. This gives an elementary proof for an important
vanishing result on $A$-hypergeometric Euler-Koszul homology. As a tool for our
investigations we develop an algorithm to compute algorithmically the Newton
filtration on a toric ring.


title: stdchk: A Checkpoint Storage System for Desktop Grid Computing

abstract:
  Checkpointing is an indispensable technique to provide fault tolerance for
long-running high-throughput applications like those running on desktop grids.
This paper argues that a dedicated checkpoint storage system, optimized to
operate in these environments, can offer multiple benefits: reduce the load on
a traditional file system, offer high-performance through specialization, and,
finally, optimize data management by taking into account checkpoint application
semantics. Such a storage system can present a unifying abstraction to
checkpoint operations, while hiding the fact that there are no dedicated
resources to store the checkpoint data. We prototype stdchk, a checkpoint
storage system that uses scavenged disk space from participating desktops to
build a low-cost storage system, offering a traditional file system interface
for easy integration with applications. This paper presents the stdchk
architecture, key performance optimizations, support for incremental
checkpointing, and increased data availability. Our evaluation confirms that
the stdchk approach is viable in a desktop grid setting and offers a low cost
storage system with desirable performance characteristics: high write
throughput and reduced storage space and network effort to save checkpoint
images.


title: Crossed products of k-graph C*-algebras by Z^l

abstract:
  An action of Z^l by automorphisms of a k-graph induces an action of Z^l by
automorphisms of the corresponding k-graph C*-algebra. We show how to construct
a (k+l)-graph whose C*-algebra coincides with the crossed product of the
original k-graph algebra by Z^l. We then investigate the structure of the
crossed-product C*-algebra.


title: The Impact of Stellar Oscillations on Doppler Velocity Planet Searches

abstract:
  We present a quantitative investigation of the effect of stellar oscillations
on Doppler velocity planet searches. Using data from four asteroseismological
observation campaigns, we find a power law relationship between the noise
impact of these oscillations on Doppler velocities and both the
luminosity-to-mass of the target stars, and observed integration times.
Including the impact of oscillation jitter should improve the quality of
Keplerian fits to Doppler velocity data. The scale of the effect these
oscillations have on Doppler velocity measurements is smaller than that
produced by stellar activity, but is most significant for giant and subgiant
stars, and at short integration times (i.e. less than a few minutes). Such
short observation times tend to be used only for very bright stars. However,
since it is these very same stars that tend to be targeted for the highest
precision observations, as planet searches probe to lower and lower planet
masses, oscillation noise for these stars can be significant and needs to be
accounted for in observing strategies.


title: On the existence of the critical point in finite density lattice QCD

abstract:
  We propose a method to probe the nature of phase transitions in lattice QCD
at finite temperature and density, which is based on the investigation of an
effective potential as a function of the average plaquette. We analyze data
obtained in a simulation of two-flavor QCD using p4-improved staggered quarks
with bare quark mass $m/T = 0.4$, and find that a first order phase transition
line appears in the high density regime for $\mu_q/T \simge 2.5$. We also
discuss the difference between the phase structures of QCD with non-zero quark
chemical potential and non-zero isospin chemical potential.


title: The mean curvature flow for isoparametric submanifolds

abstract:
  A submanifold in space forms is isoparametric if the normal bundle is flat
and principal curvatures along any parallel normal fields are constant. We
study the mean curvature flow with initial data an isoparametric submanifold in
Euclidean space and sphere. We show that the mean curvature flow preserves the
isoparametric condition, develops singularities in finite time, and converges
in finite time to a smooth submanifold of lower dimension. We also give a
precise description of the collapsing.


title: Supernovae as Probes of Extra Dimensions

abstract:
  Since the dawn of the new millennium, there has been a revived interest in
the concept of extra dimensions.In this scenario all the standard model matter
and gauge fields are confined to the 4 dimensions and only gravity can escape
to higher dimensions of the universe.This idea can be tested using table-top
experiments, collider experiments, astrophysical or cosmological observations.
The main astrophysical constraints come from the cooling rate of supernovae,
neutron stars, red giants and the sun. In this article, we consider the energy
loss mechanism of SN1987A and study the constraints it places on the number and
size of extra dimensions and the higher dimensional Planck scale.


title:
Strongly enhanced effective mass in dilute two-dimensional electron
  systems: System-independent origin

abstract:
  We measure the effective mass in a dilute two-dimensional electron system in
(111)-silicon by analyzing temperature dependence of the Shubnikov-de Haas
oscillations in the low-temperature limit. A strong enhancement of the
effective mass with decreasing electron density is observed. The mass
renormalization as a function of the interaction parameter r_s is in good
agreement with that reported for (100)-silicon, which shows that the relative
mass enhancement is system- and disorder-independent being determined by
electron-electron interactions only.


title:
L\'evy Statistics and Anomalous Transport: L\'evy flights and
  Subdiffusion

abstract:
  Levy flights and subdiffusive processes and their properties are discussed.
We derive the space- and time-fractional transport equations, and consider
their solutions in external potentials. An extensive list of references is
included.


title:
Testing gravity with motion of satellites around galaxies: Newtonian
  gravity against Modified Newtonian Dynamics

abstract:
  The motion of satellite galaxies around normal galaxies at distances 50-500
kpc provides a sensitive test for the theories. We study the surface density
and the velocities of satellites around isolated galaxies in the Sloan Digital
Sky Survey. We find that the surface number-density of satellites declines with
the projected distance as a power law with the slope -1.5-2. The rms velocities
gradually decline: observations exclude constant velocities at a 10 sigma
level. We show that observational data strongly favor the standard model: all
three major statistics of satellites - the number-density profile, the
line-of-sight velocity dispersion, and the distribution function of the
velocities -- agree remarkably well with the predictions of the standard
cosmological model. Thus, that the success of the standard model extends to
scales (50-500) kpc, much lower than what was previously considered. MOND fails
on these scales for models which assume any single power-law number-density
profile of satellites and any constant velocity anisotropy by predicting nearly
constant rms velocities of satellites. Satellite data can be fit by fine-tuned
models, which require (1) specific non-power-law density profile, (2) very
radial orbits at large distances (velocity anisotropy beta =0.6-0.7 at 200-300
kpc), and (3) 2-2.5 times more stellar mass than what is found in the galaxies.
The external gravity force - a necessary component for MOND -- makes the
situation even worse. We argue that a combination of satellite data and
observational constraints on stellar masses make these models very problematic.


title: A formula for the hypergeometric function of type $BC_n$

abstract:
  Formulae of Berezin and Karpelevic for the radial parts of invariant
differential operators and the spherical function on a complex Grassmann
manifold are generalized to the hypergeometric functions associated with root
system of type $BC_n$ under condition that the multiplicity of the middle roots
is zero or one.


title:
Quantum Oscillations in Magnetic Field Induced Antiferromagnetic Phase
  of Underdoped Cuprates : Application to Ortho-II YBa2Cu3O6.5

abstract:
  Magnetic field induced antiferromagnetic phase of the underdoped cuprates is
studied within the t-t'-J model. A magnetic field suppresses the pairing
amplitude, which in turn may induce antiferromagnetism. We apply our theory to
interpret the recently reported quantum oscillations in high magnetic field in
ortho-II YBa2Cu3O6.5 and propose that the total hole density abstracted from
the oscillation period is reduced by 50% due to the antiferromagnetism.


title: Datta-Das type spin-field effect transistor in non-ballistic regime

abstract:
  It is revealed that in spin helix state of (001) quantum well system, strong
suppression of D'yakonov-Perel' spin relaxation process occurs by an interplay
between Rashba and Dresselhaus couplings over a wide range of Rashba coupling
strength. Contrary to common belief in early works, this leads to the finding
that Datta-Das type spin-field effect transistor is actually applicable to more
realistic non-ballistic transport regime in two dimensional electron gas
system.


title:
A phase transition behavior for Brownian motions interacting through
  their ranks

abstract:
  Consider a time-varying collection of n points on the positive real axis,
modeled as exponentials of n Brownian motions whose drift vector at every time
point is determined by the relative ranks of the coordinate processes at that
time. If at each time point we divide the points by their sum, under suitable
assumptions the rescaled point process converges to a stationary distribution
(depending on n and the vector of drifts) as time goes to infinity. This
stationary distribution can be exactly computed using a recent result of Pal
and Pitman. The model and the rescaled point process are both central objects
of study in models of equity markets introduced by Banner, Fernholz, and
Karatzas. In this paper, we look at the behavior of this point process under
the stationary measure as $n$ tends to infinity. Under a certain `continuity at
the edge' condition on the drifts, we show that one of the following must
happen: either (i) all points converge to zero, or (ii) the maximum goes to one
and the rest go to zero, or (iii) the processes converge in law to a
non-trivial Poisson-Dirichlet distribution. The proof employs, among other
things, techniques from Talagrand's analysis of the low temperature phase of
Derrida's Random Energy Model of spin glasses. The main result establishes a
universality property for the BFK models and aids in explicit asymptotic
computations using known results about the Poisson-Dirichlet law.


title:
Magnetic and Structural Studies of the Quasi-Two-Dimensional Spin-Gap
  System (CuCl)LaNb2O7

abstract:
  We report magnetization, nuclear magnetic resonance (NMR), nuclear quadrupole
resonance (NQR), and transmission electron microscopy (TEM) studies on the
quasi-two-dimensional spin-gap system (CuCl)LaNb2O7, a possible candidate for
the J1-J2 model on a square lattice. A sharp single NQR line is observed at the
Cu and Cl sites, indicating that both Cu and Cl atoms occupy a unique site.
However, the electric field gradient tensors at the Cu, Cl, and La sites do not
have axial symmetry. This is incompatible with the reported crystal structure.
Thus the J1-J2 model has to be modified. We propose alternative two-dimensional
dimer models based on the NMR, NQR, and TEM results. The value of the hyperfine
coupling constant at the Cu sites indicates that the spin density is mainly on
the d(3z2-r2) orbital (z parallel c). At 1.5 K, Cu- and Nb-NMR signals
disappear above the critical field Bc1 = 10.3 T determined from the onset of
the magnetization, indicating a field-induced magnetic phase transition at Bc1.


title: Reparametrizations of Continuous Paths

abstract:
  A reparametrization (of a continuous path) is given by a surjective weakly
increasing self-map of the unit interval. We show that the monoid of
reparametrizations (with respect to compositions) can be understood via
``stop-maps'' that allow to investigate compositions and factorizations, and we
compare it to the distributive lattice of countable subsets of the unit
interval. The results obtained are used to analyse the space of traces in a
topological space, i.e., the space of continuous paths up to reparametrization
equivalence. This space is shown to be homeomorphic to the space of regular
paths (without stops) up to increasing reparametrizations. Directed versions of
the results are important in directed homotopy theory.


title: Transport properties of a meson gas

abstract:
  We present recent results on a systematic method to calculate transport
coefficients for a meson gas (in particular, we analyze a pion gas) at low
temperatures in the context of Chiral Perturbation Theory. Our method is based
on the study of Feynman diagrams with a power counting which takes into account
collisions in the plasma by means of a non-zero particle width. In this way, we
obtain results compatible with analysis of Kinetic Theory with just the leading
order diagram. We show the behavior with temperature of electrical and thermal
conductivities and shear and bulk viscosities, and we discuss the fundamental
role played by unitarity. We obtain that bulk viscosity is negligible against
shear viscosity near the chiral phase transition. Relations between the
different transport coefficients and bounds on them based on different
theoretical approximations are also discussed. We also comment on some
applications to heavy-ion collisions.


title: Subcritical crack growth in fibrous materials

abstract:
  We present experiments on the slow growth of a single crack in a fax paper
sheet submitted to a constant force $F$. We find that statistically averaged
crack growth curves can be described by only two parameters : the mean rupture
time $\tau$ and a characteristic growth length $\zeta$. We propose a model
based on a thermally activated rupture process that takes into account the
microstructure of cellulose fibers. The model is able to reproduce the shape of
the growth curve, the dependence of $\zeta$ on $F$ as well as the effect of
temperature on the rupture time $\tau$. We find that the length scale at which
rupture occurs in this model is consistently close to the diameter of cellulose
microfibrils.


title: Anomaly Analysis of Hawking Radiation from Acoustic Black Hole

abstract:
  The Hawking radiation from the three dimensional rotating acoustic black hole
is considered from the viewpoint of anomaly cancellation method initiated by
Robinson and Wilczek. Quantum field near the horizon is effectively described
by two dimensional charged field with a charge identified as the angular
momentum m. The fluxes of charge and energy are obtained from the anomaly
cancellation condition and regularity at the horizon, and are shown to match
with those of the two dimensional black body radiation at the Hawking
temperature.


title: Imaging the stick-slip peeling of an adhesive tape under a constant load

abstract:
  Using a high speed camera, we study the peeling dynamics of an adhesive tape
under a constant load with a special focus on the so-called stick-slip regime
of the peeling. It is the first time that the very fast motion of the peeling
point is imaged. The speed of the camera, up to 16000 fps, allows us to observe
and quantify the details of the peeling point motion during the stick and slip
phases: stick and slip velocities, durations and amplitudes. First, in contrast
with previous observations, the stick-slip regime appears to be only transient
in the force controlled peeling. Additionally, we discover that the stick and
slip phases have similar durations and that at high mean peeling velocity, the
slip phase actually lasts longer than the stick phase. Depending on the mean
peeling velocity, we also observe that the velocity change between stick and
slip phase ranges from a rather sudden to a smooth transition. These new
observations can help to discriminate between the various assumptions used in
theoretical models for describing the complex peeling of an adhesive tape. The
present imaging technique opens the door for an extensive study of the velocity
controlled stick-slip peeling of an adhesive tape that will allow to understand
the statistical complexity of the stick-slip in a stationary case.


title: Experimental Algorithm for the Maximum Independent Set Problem

abstract:
  We develop an experimental algorithm for the exact solving of the maximum
independent set problem. The algorithm consecutively finds the maximal
independent sets of vertices in an arbitrary undirected graph such that the
next such set contains more elements than the preceding one. For this purpose,
we use a technique, developed by Ford and Fulkerson for the finite partially
ordered sets, in particular, their method for partition of a poset into the
minimum number of chains with finding the maximum antichain. In the process of
solving, a special digraph is constructed, and a conjecture is formulated
concerning properties of such digraph. This allows to offer of the solution
algorithm. Its theoretical estimation of running time equals to is $O(n^{8})$,
where $n$ is the number of graph vertices. The offered algorithm was tested by
a program on random graphs. The testing the confirms correctness of the
algorithm.


title: Algebraic definition of Holonomy on Poisson Manifold

abstract:
  We give an algebraic construction of connection on the symplectic leaves of
Poisson manifold, introduced in \cite{Ginzburg}. This construction is suitable
for the definition of the linearized holonomy on a regular symplectic
foliation.


title: CMB anisotropy power spectrum using linear combinations of WMAP maps

abstract:
  In recent years the goal of estimating different cosmological parameters
precisely has set new challenges in the effort to accurately measure the
angular power spectrum of CMB. This has required removal of foreground
contamination as well as detector noise bias with reliability and precision.
Recently, a novel {\em model-independent} method for the estimation of CMB
angular power spectrum solely from multi-frequency observations has been
proposed and implemented on the first year WMAP data by Saha et al. 2006. All
previous estimates of power spectrum of CMB are based upon foreground templates
using data sets from different experiments. However our methodology
demonstrates that {\em CMB angular spectrum can be reliably estimated with
precision from a self contained analysis of the WMAP data}. In this work we
provide a detailed description of this method. We also study and identify the
biases present in our power spectrum estimate. We apply our methodoly to
extract the power spectrum from the WMAP 1 year and 3 year data.


title:
Analyzing powers Ayy, Axx, Axz and Ay in the dd->3Hen reaction at 270
  MeV

abstract:
  The data on the tensor Ayy, Axx, Axz and vector Ay analyzing powers in the
dd->3Hen obtained at Td= 270 MeV in the angular range 0 - 110 degrees in the
c.m. are presented. The observed negative sign of the tensor analyzing powers
Ayy, Axx and Axz at small angles clearly demonstrate the sensitivity to the
ratio of the D and S wave component of the 3He wave function. However, the
one-nucleon exchange calculations by using the standard 3He wave functions have
failed to reproduce the strong variation of the tensor analyzing powers as a
function of the angle in the c.m.


title: Compact jets as probes for sub-parsec scale regions in AGN

abstract:
  Compact relativistic jets in active galactic nuclei offer an effective tool
for investigating the physics of nuclear regions in galaxies. The emission
properties, dynamics, and evolution of jets in AGN are closely connected to the
characteristics of the central supermassive black hole, accretion disk and
broad-line region in active galaxies. Recent results from studies of the
nuclear regions in several active galaxies with prominent outflows are reviewed
in this contribution.


title:
An explicit stationary phase formula for the local formal
  Fourier-Laplace transform

abstract:
  We give an explicit formula (i.e., a formal stationary phase formula) for the
local Fourier-Laplace transform of a formal germ of meromorphic connection of
one complex variable with a possibly irregular singularity. This is a complex
analogue of the formulas in the preprint math/0702436v1.


title: Chern-Simons pre-quantization over four-manifolds

abstract:
  We introduce a pre-symplectic structure on the space of connections in a
G-principal bundle over a four-manifold and a Hamiltonian action on it of the
group of gauge transformations that are trivial on the boundary. The moment map
is given by the square of curvature so that the 0-level set is the space of
flat connections. Thus the moduli space of flat connections is endowed with a
pre-symplectic structure. In case when the four-manifold is null-cobordant we
shall construct, on the moduli space of connections, as well as on that of flat
connections, a hermitian line bundle with connection whose curvature is given
by the pre-symplectic form. This is the Chern-Simons pre-quantum line bundle.
The group of gauge transformations on the boundary of the base manifold acts on
the moduli space of flat connections by an infinitesimally symplectic way. When
the base manifold is a 4-dimensional disc we show that this action is lifted to
the pre-quantum line bundle by its abelian extension. The geometric description
of the latter is related to the 4-dimensional Wess-Zumino-Witten model. The
previous version of this arxiv text had several incoincidence with the
published article in the Differential Geometry and its Applications vol.29, so
the author corrected them.


title:
Quantum-statistical equation-of-state models of dense plasmas:
  high-pressure Hugoniot shock adiabats

abstract:
  We present a detailed comparison of two self-consistent equation-of-state
models which differ from their electronic contribution: the atom in a spherical
cell and the atom in a jellium of charges. It is shown that both models are
well suited for the calculation of Hugoniot shock adiabats in the high pressure
range (1 Mbar-10 Gbar), and that the atom-in-a-jellium model provides a better
treatment of pressure ionization. Comparisons with experimental data are also
presented. Shell effects on shock adiabats are reviewed in the light of these
models. They lead to additional features not only in the variations of pressure
versus density, but also in the variations of shock velocity versus particle
velocity. Moreover, such effects are found to be responsible for enhancement of
the electronic specific heat.


title: Optical asymptotics via Weniger transformation

abstract:
  Starting from the resurgence equation discovered by Berry and Howls [M. V.
Berry and C. Howls "Hyperasymptotics for integrals with saddles," Proc. R. Soc.
Lond. A 434, 657-675 (1991)], the Weniger transformation is here proposed as a
natural, efficient, and straightforwardly implementable scheme for the
efficient asymptotics evaluation of a class of integrals occurring in several
areas of physics and, in particular, of optics. Preliminary numerical tests,
carried out on the Pearcey function, provide a direct comparison between the
performances of Weniger transformation and those of Hyperasymptotics, which
seems to corroborate the theoretical predictions. We believe that Weniger
transformation would be a very useful computational tool for the asymptotic
treatment of several optical problems.


title:
The Characteristic Noise Induced by the Continious Measurements in
  Classical Open Systems

abstract:
  We proposed the modified version of quantum-mechanical theory of continuous
measurements for the case of classical open systems. In our approach the
influence of measurement on evolution of distribution function of an open
system is described by the Fokker-Planck equation of a special form. The
diffusion tensor of this equation is uniquely defined by a type of the measured
quantity. On the basis of the approach proposed the stationary states of the
linear dissipative systems, induced by measurements in them, are considered.
Also we demonstrate on the simple example, how in the conservative system,
consisting of noninteracting parts, measurement of the integral of motion
results in relaxation to the quasi-thermodynamic equilibrium between parts of
the system. The "temperature" of such state is determined by energy of the
system and by the mean value of measured integral of motion. PACS numbers:
03.65.Ta, 05.40.-a


title: Crossed Andreev reflection at spin-active interfaces

abstract:
  With the aid of the quasiclassical Eilenberger formalism we develop a theory
of non-local electron transport across three-terminal ballistic
normal-superconducting-normal (NSN) devices with spin-active NS interfaces. The
phenomenon of crossed Andreev reflection (CAR) is known to play the key role in
such transport. We demonstrate that CAR is highly sensitive to electron spins
and yields a rich variety of properties of non-local conductance which we
describe non-perturbatively at arbitrary voltages, temperature, spin-dependent
interface transmissions and their polarizations. Our results can be applied to
multi-terminal hybrid structures with normal, ferromagnetic and half-metallic
electrodes and can be directly tested in future experiments.


title:
Coulomb effects in polarization transfer in elastic antiproton and
  proton electron scattering at low energies

abstract:
  The influence of Coulomb distortion on the polarization transfer in elastic
proton and antiproton electron scattering at low energies is calculated in a
distorted wave Born approximation. For antiproton electron scattering Coulomb
effects reduce substantially the spin transfer cross section compared to the
plane wave Born approximation whereas for proton electron scattering they lead
to a dramatic increase for kinetic proton lab energies below about 20 keV.


title:
Parametric Frequency Conversion of Short Optical Pulses Controlled by a
  CW Background

abstract:
  We predict that parametric sum-frequency generation of an ultra-short pulse
may result from the mixing of an ultra-short optical pulse with a
quasi-continuous wave control. We analytically show that the intensity, time
duration and group velocity of the generated idler pulse may be controlled in a
stable manner by adjusting the intensity level of the background pump.


title: On the corona of magnetars

abstract:
  Slow dissipation of non-potential magnetic fields in the magnetosphere of the
magnetar is assumed to accelerate particles to hundreds MeV along the magnetic
field lines. We consider interaction of fast particles with the surface of the
magnetar. We argue that the collisionless dissipation does not work in the
atmosphere of the neutron star because the two-stream instability is stabilized
by the inhomogeneity of the atmosphere. Rather, the dominant dissipation
mechanism is collisional Landau levelexcitations followed by pair production
via the deexcitation gamma-rays ultimately leading to electrons with the energy
below the Landau energy. We show that, because of the effects of the
superstrong magnetic field, these electrons could emerge from the surface
carrying most of the original energy so that a hot corona arises with the
temperature of 1 - 2 MeV. This extended corona is better suited than a thin
atmosphere to convert most of the primary beam energy to non-thermal radiation
and, as we show, most of the coronal energy release is radiated away in the
hard X-ray and the soft gamma-ray bands by Comptonization and bremsstrahlung.
The radiation spectrum is a power-law with the photon index $1<\alpha<2$. The
model may account for the persistent hard X-ray emission discovered recently
from the soft gamma-ray repeaters and anomalous X-ray pulsars and predicts that
the radiation spectrum is extended into the MeV band.


title: Time-dependent quantum Monte Carlo and the stochastic quantization

abstract:
  We examine the relation between the recently proposed time-dependent quantum
Monte Carlo (TDQMC) method and the principles of stochastic quantization. In
both TDQMC and stochastic quantization particle motion obeys stochastic
guidance equations to preserve quantum equilibrium. In this way the probability
density of the Monte Carlo particles corresponds to the modulus square of the
many-body wave function at all times. However, in TDQMC the motion of particles
and guide waves occurs in physical space unlike in stochastic quantization
where it occurs in configuration space. Hence the practical calculation of time
evolution of many-body fully correlated quantum systems becomes feasible within
the TDQMC methodology. We illustrate the TDQMC technique by calculating the
symmetric and antisymmetric ground state of a model one-dimensional Helium
atom, and the time evolution of the dipole moment when the atom is irradiated
by a strong ultrashort laser pulse.


title: Cusps of Hilbert modular varieties

abstract:
  Motivated by a question of Hirzebruch on the possible topological types of
cusp cross-sections of Hilbert modular varieties, we give a necessary and
sufficient condition for a manifold M to be diffeomorphic to a cusp
cross-section of a Hilbert modular variety. Specialized to Hilbert modular
surfaces, this proves that every Sol 3-manifold is diffeomorphic to a cusp
cross-section of a (generalized) Hilbert modular surface. We also deduce an
obstruction to geometric bounding in this setting. Consequently, there exist
Sol 3-manifolds that cannot arise as a cusp cross-section of a 1-cusped
nonsingular Hilbert modular surface.


title:
The Impact of Type Ia Supernova Explosions on their Companions in Binary
  System

abstract:
  Using a simple analytic method, we calculate the impact effect between the
ejecta of a SN Ia and its companion to survey the influence of initial
parameters of the progenitor's system, which is useful for searching the
companion in a explosion remnant. The companion models are obtained from
Eggleton's evolution code.The results are divided into two groups based on mass
transfer stage. For a given condition, more hydrogen-rich material is stripped
from the envelope of a Hertzsprung-gap companion than that of a main-sequence
companion, while a larger kick velocity and a larger luminosity are gained for
a main-sequence companion. The kick velocity is too low to significantly affect
the final spatial velocity of the companion, which is mainly affected by the
initial parameters of the progenitor systems. The spatial velocity of the
stripped material has an upper limit within the range of 8000 - 9500 km/s,
which only depends on the total kinetic energy of the explosion.The stripped
mass, the ratio of the stripped mass to the companion mass and the kick
velocity of the companion all significantly depend on the initial companion
mass and orbital period. Our model may naturally explain the spatial velocity
of the star G in the remnant of Tycho's supernova, while an energy-loss
mechanism is needed to interpret its luminosity.


title: Bohr and Rogosinski abscissas for ordinary Dirichlet series

abstract:
  We prove that the abscissas of Bohr and Rogosinski for ordinary Dirichlet
series, mapping the right half-plane into the bounded convex domain $G\subset
\mathbb{C} $ are independent of the domain $G$. Furthermore, we obtain new
estimates about these abscissas.


title: Outflow and dense gas emission from massive Infrared Dark Clouds

abstract:
  Infrared Dark Clouds are expected to harbor sources in different, very young
evolutionary stages. To better characterize these differences, we observed a
sample of 43 massive Infrared Dark Clouds, originally selected as candidate
high-mass starless cores, with the IRAM 30m telescope covering spectral line
tracers of low-density gas, high-density gas, molecular outflows/jets and
temperature effects. The SiO(2-1) observations reveal detections toward 18
sources. Assuming that SiO is exclusively produced by sputtering from dust
grains, this implies that at least in 40% of this sample star formation is
on-going. A broad range of SiO line-widths is observed (between 2.2 and
65km/s), and we discuss potential origins for this velocity spread. While the
low-density tracers 12CO(2-1) and 13CO(1-0) are detected in several velocity
components, the high-density tracer H13CO+(1--0) generally shows only a single
velocity component and is hence well suited for kinematic distance estimates of
IRDCs. Furthermore, the H13CO+ line-width is on average 1.5 times larger than
that of previously observed NH3(1,1). This is indicative of more motion at the
denser core centers, either due to turbulence or beginning star formation
activity. In addition, we detect CH3CN toward only six sources whereas CH3OH is
observed toward approximately 40% of the sample. Estimates of the CH3CN and
CH3OH abundances are low with average values of 1.2x10^{-10} and 4.3x10^{-10},
respectively. These results are consistent with chemical models at the earliest
evolutionary stages of high-mass star formation. Furthermore, the CH3OH
abundances compare well to recently reported values for low-mass starless
cores.


title:
Calorimetric Evidence for a Fulde-Ferrell-Larkin-Ovchinnikov
  Superconducting State in the Layered Organic Superconductor
  \kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$

abstract:
  The specific heat of the layered organic superconductor $\kappa$-%
(BEDT-TTF)$_2$Cu(NCS)$_2$, where BEDT-TTF is bisethylenedithio-%
tetrathiafulvalene, has been studied in magnetic fields up to 28 T applied
perpendicular and parallel to the superconducting layers. In parallel fields
above 21 T, the superconducting transition becomes first order, which signals
that the Pauli-limiting field is reached. Instead of saturating at this field
value, the upper critical field increases sharply and a second first-order
transition line appears within the superconducting phase. Our results give
strong evidence that the phase, which separates the homogeneous superconducting
state from the normal state is a realization of a
Fulde-Ferrell-Larkin-Ovchinnikov state.


title:
Circular Polarization of Primordial Gravitational Waves in
  String-inspired Inflationary Cosmology

abstract:
  We study a mechanism to produce the circular polarization of primordial
gravitational waves.
  The circular polarization is generated during the super-inflation driven by
the Gauss-Bonnet term in the string-inspired cosmology. The instability in the
tensor mode caused by the Gauss-Bonnet term and the parity violation due to the
gravitational Chern-Simons term are the essential ingredients of the mechanism.
We also discuss detectability of the produced circular polarization of
gravitational waves. It turns out that the simple model of single-field
inflation contradicts CMB observations. To circumvent this difficulty, we
propose a two-field inflation model. In this two-field model, the circular
polarization of gravitational waves is created in the frequency range designed
by the Big-Bang Observer (BBO) or the deci-hertz gravitational-wave observatory
(DECIGO).


title: Graceful exit via polymerization of pre-big bang cosmology

abstract:
  We consider a phenomenological modification of the Pre Big Bang scenario
using ideas from the resolution of curvature singularities in Loop Quantum
Cosmology. We show that non-perturbative Loop modifications to the dynamics,
arising from the underlying polymer representation, can resolve the graceful
exit problem. The curvature and the dilaton energy stay finite at all times, in
both the string and Einstein frames. In the string frame, the dilaton tends to
a constant value at late times after the bounce.


title: Dark energy models toward observational tests and data

abstract:
  A huge amount of good quality astrophysical data converges towards the
picture of a spatially flat universe undergoing the today observed phase of
accelerated expansion. This new observational trend is commonly addressed as
Precision Cosmology. Despite of the quality of astrophysical surveys, the
nature of dark energy dominating the matter-energy content of the universe is
still unknown and a lot of different scenarios are viable candidates to explain
cosmic acceleration. Methods to test these cosmological models are based on
distance measurements and lookback time toward astronomical objects used as
standard candles. I discuss the characterizing parameters and constraints of
three different classes of dark energy models pointing out the related
degeneracy problem which is the signal that more data at low (z= 0- 1), medium
(1<z<10) and high (10 <z< 1000) redshift are needed to definitively select
realistic models.


title: A new type fit for the CKM matrix elements

abstract:
  The aim of the paper is to propose a new type of fits in terms of invariant
quantities for finding the entries of the CKM matrix from the quark sector, by
using the mathematical solution to the reconstruction problem of 3 x 3 unitary
matrices from experimental data, recently found. The necessity of this type of
fit comes from the compatibility conditions between the data and the
theoretical model formalised by the CKM matrix, which imply many strong
nonlinear conditions on moduli which all have to be satisfied in order to
obtain a unitary matrix.


title:
Persistence of direction increases the drift velocity of run and tumble
  chemotaxis

abstract:
  Escherichia coli is a motile bacterium that moves up a chemoattractant
gradient by performing a biased random walk composed of alternating runs and
tumbles. Previous models of run and tumble chemotaxis neglect one or more
features of the motion, namely (i) a cell cannot directly detect a
chemoattractant gradient but rather makes temporal comparisons of
chemoattractant concentration, (ii) rather than being entirely random, tumbles
exhibit persistence of direction, meaning that the new direction after a tumble
is more likely to be in the forward hemisphere, and (iii) rotational Brownian
motion makes it impossible for an E. coli cell to swim in a straight line
during a run. This paper presents an analytic calculation of the chemotactic
drift velocity taking account of (i), (ii) and (iii), for weak chemotaxis. The
analytic results are verified by Monte Carlo simulation. The results reveal a
synergy between temporal comparisons and persistence that enhances the drift
velocity, while rotational Brownian motion reduces the drift velocity.


title:
Breathers and Raman scattering in a two-leg ladder with staggered
  Dzialoshinskii-Moriya interaction

abstract:
  Recent experiments have revealed the role of staggered Dzialoshinskii-Moriya
interaction in the magnetized phase of an antiferromagnetic spin 1/2 two-leg
ladder compound under a uniform magnetic field. We derive a low energy
effective field theory describing a magnetized two-leg ladder with a weak
staggered Dzialoshinskii-Moriya interaction. This theory predicts the
persistence of the spin gap in the magnetized phase, in contrast to standard
two-leg ladders, and the presence of bound states in the excitation spectrum.
Such bound states are observable in Raman scattering measurements. These
results are then extended to intermediate Dzialoshinskii-Moriya interaction
using Exact Diagonalizations.


title:
Probing the electron-phonon coupling in MgB2 through magnetoresistance
  measurements in neutron irradiated thin films

abstract:
  We report magnetoresistance (MR) measurements on MgB2 and the corresponding
full account from ab-initio calculations; we suggest that this combination can
be a useful tool to probe electron- phonon coupling. We obtain good
quantitative agreement between high field measurements on neutron irradiated
epitaxial thin films and calculations within Bloch-Boltzmann transport theory
over a wide range of magnetic fields (0-28 T) and temperatures (40-300 K), and
as a function of the field orientation. The crossovers between in-plane and
out-of-plane MR, experimentally observed as a function of either disorder or
temperature are well reproduced indicating that disorder and interaction with
phonons strongly affect the scattering rate of s-carriers.


title:
A model of dense-plasma atomic structure for equation-of-state
  calculations

abstract:
  A model of dense plasmas relying on the superconfiguration approximation is
presented. In each superconfiguration the nucleus is totally screened by the
electrons in a Wigner-Seitz sphere (ion-sphere model). Superconfigurations of
the same charge are grouped into ions. It is shown that boundary values of the
wavefunctions play a crucial role in the form of the Virial theorem from which
the pressure formula is derived. Finally, a condition is presented and
discussed, which makes the ion-sphere model variational when bound electrons
are treated quantum-mechanically and free electrons quasi-classically.


title: Evolution of dust and ice features around FU Orionis objects

abstract:
  (abridged) We present spectroscopy data for a sample of 14 FUors and 2 TTauri
stars observed with the Spitzer Space Telescope or with the Infrared Space
Observatory (ISO). Based on the appearance of the 10 micron silicate feature we
define 2 categories of FUors. Objects showing the silicate feature in
absorption (Category 1) are still embedded in a dusty and icy envelope. The
shape of the 10 micron silicate absorption bands is compared to typical dust
compositions of the interstellar medium and found to be in general agreement.
Only one object (RNO 1B) appears to be too rich in amorphous pyroxene dust, but
a superposed emission feature can explain the observed shape. We derive optical
depths and extinction values from the silicate band and additional ice bands at
6.0, 6.8 and 15.2 micron. In particular the analysis of the CO_2 ice band at
15.2 micron allows us to search for evidence for ice processing and constrains
whether the absorbing material is physically linked to the central object or in
the foreground. For objects showing the silicate feature in emission (Category
2), we argue that the emission comes from the surface layer of accretion disks.
Analyzing the dust composition reveals that significant grain growth has
already taken place within the accretion disks, but no clear indications for
crystallization are present. We discuss how these observational results can be
explained in the picture of a young, and highly active accretion disk. Finally,
a framework is proposed as to how the two categories of FUors can be understood
in a general paradigm of the evolution of young, low-mass stars. Only one
object (Parsamian 21) shows PAH emission features. Their shapes, however, are
often seen toward evolved stars and we question the object's status as a FUor
and discuss other possible classifications.


title:
0-pi Transitions in a Superconductor/Chiral Ferromagnet/Superconductor
  Junction induced by a Homogeneous Cycloidal Spiral

abstract:
  We study the pi phase in a superconductor-ferromagnet-superconductor
Josephson junction, with a ferromagnet showing a cycloidal spiral spin
modulation with in-plane propagation vector. Our results reveal a high
sensitivity of the junction to the spiral order and indicate the presence of
0-pi quantum phase transitions as function of the spiral wave vector. We find
that the chiral magnetic order introduces chiral superconducting triplet pairs
that strongly influence the physics in such Josephson junctions, with potential
applications in nanoelectronics and spintronics.


title:
Two-dimensional Schroedinger operators with fast decaying potential and
  multidimensional $L_2$-kernel

abstract:
  Using Moutard transformations we show how explicit examples of
two-dimensional Schroedinger operators with fast decaying potential and
multidimensional $L_2$-kernel may be constructed


title:
Time dependent couplings and crossover length scales in non-equilibrium
  surface roughening

abstract:
  We show that time dependent couplings may lead to nontrivial scaling
properties of the surface fluctuations of the asymptotic regime in
non-equilibrium kinetic roughening models . Three typical situations are
studied. In the case of a crossover between two different rough regimes, the
time-dependent coupling may result in anomalous scaling for scales above the
crossover length. In a different setting, for a crossover from a rough to
either a flat or damping regime, the time dependent crossover length may
conspire to produce a rough surface, despite the most relevant term tends to
flatten the surface. In addition, our analysis sheds light into an existing
debate in the problem of spontaneous imbibition, where time dependent couplings
naturally arise in theoretical models and experiments.


title: Formation of Massive Primordial Stars in a Reionized Gas

abstract:
  We use cosmological hydrodynamic simulations with unprecedented resolution to
study the formation of primordial stars in an ionized gas at high redshifts.
Our approach includes all the relevant atomic and molecular physics to follow
the thermal evolution of a prestellar gas cloud to very high densities of
~10^{18} cm^{-3}. We locate a star-forming gas cloud within a reionized region
in our cosmological simulation. The first run-away collapse is triggered when
the gas cloud's mass is ~40 Msun. We show that the cloud core remains stable
against chemo-thermal instability and also against gravitational deformation
throughout its evolution. Consequently, a single proto-stellar seed is formed,
which accretes the surrounding hot gas at the rate ~10^{-3} Msun/year. We carry
out proto-stellar evolution calculations using the inferred accretion rate. The
resulting mass of the star when it reaches the zero-age main sequence is M_ZAMS
~40 Msun. We argue that, since the obtained M_ZAMS is as large as the mass of
the collapsing parent cloud, the final stellar mass should be close to this
value. Such massive, rather than exceptionally massive, primordial stars are
expected to cause early chemical enrichment of the Universe by exploding as
black hole-forming super/hypernovae, and may also be progenitors of high
redshift gamma-ray bursts. The elemental abundance patterns of recently
discovered hyper metal-poor stars suggest that they might have been born from
the interstellar medium that was metal-enriched by supernovae of these massive
primordial stars.


title: Jet disc coupling in black hole binaries

abstract:
  In the last decade multi-wavelength observations have demonstrated the
importance of jets in the energy output of accreting black hole binaries. The
observed correlations between the presence of a jet and the state of the
accretion flow provide important information on the coupling between accretion
and ejection processes. After a brief review of the properties of black hole
binaries, I illustrate the connection between accretion and ejection through
two particularly interesting examples. First, an INTEGRAL observation of Cygnus
X-1 during a 'mini-' state transition reveals disc jet coupling on time scales
of orders of hours. Second, the black hole XTEJ1118+480 shows complex
correlations between the X-ray and optical emission. Those correlations are
interpreted in terms of coupling between disc and jet on time scales of seconds
or less. Those observations are discussed in the framework of current models.


title: Generation of perturbation after multi-field inflation

abstract:
  We explore a new possibility that some inflaton fields in multi-field
inflation models satisfy the observed value of the spectral index so that the
curvature perturbation generated by them through post-inflationary dynamics may
be relevant for the current observations. We illustrate this point using a
simple and reasonable multi-field chaotic inflation model motivated from string
theory. Possible non-Gaussianity and the tensor-to-scalar ratio are briefly
addressed.


title:
Experimental search for neutron - mirror neutron oscillations using
  storage of ultracold neutrons

abstract:
  The idea of a hidden sector of mirror partners of elementary particles has
attracted considerable interest as a possible candidate for dark matter.
Recently it was pointed out by Berezhiani and Bento that the present
experimental data cannot exclude the possibility of a rapid oscillation of the
neutron n to a mirror neutron n' with oscillation time much smaller than the
neutron lifetime. A dedicated search for vacuum transitions n->n' has to be
performed at weak magnetic field, where both states are degenerate. We report
the result of our experiment, which compares rates of ultracold neutrons after
storage at a weak magnetic field well below 20 nT and at a magnetic field
strong enough to suppress the seeked transitions. We obtain a new limit for the
oscillation time of n-n' transitions, tau_osc (90% C.L.) > 414 s. The
corresponding limit for the mixing energy of the normal and mirror neutron
states is delta_m (90% C.L.) < 1.5x10-18 eV.


title: Modelling exchange bias in core/shell nanoparticles

abstract:
  We present an atomistic model of a single nanoparticle with core/shell
structure that takes into account its lattice strucutre and spherical geometry,
and in which the values of microscopic parameters such as anisotropy and
exchange constants can be tuned in the core, shell and interfacial regions. By
means of Monte Carlo simulations of the hysteresis loops based on this model,
we have determined the range of microscopic parameters for which loop shifts
after field cooling can be observed. The study of the magnetic order of the
interfacial spins for different particles sizes and values of the interfacial
exchange coupling have allowed us to correlate the appearance of loop
asymmetries and vertical displacements to the existence of a fraction of
uncompensated spins at the shell interface that remain pinned during field
cycling, offering new insight on the microscopic origin of the experimental
phenomenology.


title: Twisted noncommutative equivariant cohomology: Weil and Cartan models

abstract:
  We propose Weil and Cartan models for the equivariant cohomology of
noncommutative spaces which carry a covariant action of Drinfel'd twisted
symmetries. The construction is suggested by the noncommutative Weil algebra of
Alekseev and Meinrenken; we show that one can implement a Drinfel'd twist of
their models in order to take into account the noncommutativity of the spaces
we are acting on.


title:
Critical mass of bacterial populations and critical temperature of
  self-gravitating Brownian particles in two dimensions

abstract:
  We show that the critical mass M_c=8\pi of bacterial populations in two
dimensions in the chemotactic problem is the counterpart of the critical
temperature T_c=GMm/4k_B of self-gravitating Brownian particles in
two-dimensional gravity. We obtain these critical values by using the Virial
theorem or by considering stationary solutions of the Keller-Segel model and
Smoluchowski-Poisson system. We also consider the case of one dimensional
systems and develop the connection with the Burgers equation. Finally, we
discuss the evolution of the system as a function of M or T in bounded and
unbounded domains in dimensions d=1, 2 and 3 and show the specificities of each
dimension. This paper aims to point out the numerous analogies between
bacterial populations, self-gravitating Brownian particles and, occasionally,
two-dimensional vortices.


title: An introduction to Seiberg-Witten theory on closed 3-manifolds

abstract:
  This is a version of the author's diploma thesis written at the University of
Cologne in 2002/03. The topic is the construction of Seiberg-Witten invariants
of closed 3-manifolds. In analogy to the four dimensional case, the structure
of the moduli space is investigated. The Seiberg-Witten invariants are defined
and their behaviour under deformation of the Riemannian metric is analyzed.
  Since it is essentially an exposition of results which were already known
during the time of writing, the thesis has not been published. In particular,
the author does not claim any originality concerning the results. Moreover, new
developments of the theory are not included. However, the detailed
account--together with the appendices on the required functional analytic and
geometric background--might be of interest for people starting to work in the
area of gauge field theory.


title:
Form factors in finite volume II:disconnected terms and finite
  temperature correlators

abstract:
  Continuing the investigation started in a previous work, we consider form
factors of integrable quantum field theories in finite volume, extending our
investigation to matrix elements with disconnected pieces. Numerical
verification of our results is provided by truncated conformal space approach.
Such matrix elements are important in computing finite temperature correlation
functions, and we give a new method for generating a low temperature expansion,
which we test for the one-point function up to third order.