title: A New Stream Cipher: Dicing

abstract:
  In this paper, we will propose a new synchronous stream cipher named DICING,
which can be viewed as a clock-controlled one but with a new mechanism of
altering steps. It has satisfactory performance and there have not been found
weakness for the known attacks, the key sizes can be 128bits and 256bits
respectively.


title: A simple bijection between binary trees and colored ternary trees

abstract:
  In this short note, we first present a simple bijection between binary trees
and colored ternary trees and then derive a new identity related to generalized
Catalan numbers.


title: Pattern Avoidance in Generalized Non-crossing Trees

abstract:
  In this paper, the problem of pattern avoidance in generalized non-crossing
trees is studied. The generating functions for generalized non-crossing trees
avoiding patterns of length one and two are obtained. Lagrange inversion
formula is used to obtain the explicit formulas for some special cases.
Bijection is also established between generalized non-crossing trees with
special pattern avoidance and the little Schr\"{o}der paths.


title: Origin of spatial variation of pairing gap in Bi-based high-Tc cuprates

abstract:
  Recently, scanning tunneling microscopy on Bi-2212 cuprate superconductor has
revealed a spatial variation of the energy gap that is directly correlated with
a modulation of the apical oxygen position. We identify two mechanisms by which
out-of-plane oxygens can modulate the pairing interaction within the CuO_2
layer: a covalency between the x^2-y^2 band and apical p-orbital, and a
screening of correlation U by apical oxygen polarization. Both effects strongly
depend on the apical oxygen position and their cooperative action explains the
experiment.

categories: cond-mat.supr-con cond-mat.mes-hall cond-mat.mtrl-sci cond-mat.str-el


title:
Evidence for electromagnetic granularity in the polycrystalline
  iron-based superconductor LaO0.89F0.11FeAs

abstract:
  The new rare-earth arsenate superconductors are layered, low carrier density
compounds with many similarities to the high-Tc cuprates. An important question
is whether they also exhibit weak-coupling across randomly oriented
grain-boundaries. In this work we show considerable evidence for such
weak-coupling by study of the dependence of magnetization in bulk and powdered
samples. Bulk sample magnetization curves show very little hysteresis while
remanent magnetization shows almost no sample size dependence, even after
powdering. We conclude that these samples exhibit substantial electromagnetic
granularity on a scale approximating the grain size, though we cannot yet
determine whether this is intrinsic or extrinsic.


title: Long-term radio variability of AGN: flare characteristics

abstract:
  We have studied the flare characteristics of 55 AGN at 8 different frequency
bands between 4.8 and 230 GHz. Our extensive database enables us to study the
various observational properties of flares in these sources and compare our
results with theoretical models. We visually extracted 159 individual flares
from the flux density curves and calculated different parameters, such as the
peak flux density and duration, in all the frequency bands. The selection of
flares is based on the 22 and 37 GHz data from Mets\"ahovi Radio Observatory
and 90 and 230 GHz data from the SEST telescope. Additional lower frequency
4.8, 8, and 14.5 GHz data are from the University of Michigan Radio
Observatory. We also calculated variability indices and compared them with
earlier studies. The observations seem to adhere well to the shock model, but
there is still large scatter in the data. Especially the time delays between
different frequency bands are difficult to study due to the incomplete sampling
of the higher frequencies. The average duration of the flares is 2.5 years at
22 and 37 GHz, which shows that long-term monitoring is essential for
understanding the typical behaviour in these sources. It also seems that the
energy release in a flare is independent of the duration of the flare.


title: On the Spectrum of a Model Operator in Fock Space

abstract:
  A model operator $H$ associated to a system describing four particles in
interaction, without conservation of the number of particles, is considered. We
describe the essential spectrum of $H$ by the spectrum of the channel operators
and prove the Hunziker-van Winter-Zhislin (HWZ) theorem for the operator $H.$
We also give some variational principles for boundaries of the essential
spectrum and interior eigenvalues.


title:
An AC susceptometer for the characterization of large, bulk
  superconducting samples

abstract:
  The main purpose of this work was to design, develop and construct a simple,
low-cost AC susceptometer to measure large, bulk superconducting samples (up to
32 mm in diameter) in the temperature range 78-120 K. The design incorporates a
double heating system that enables a high heating rate (25 K/hour) while
maintaining a small temperature gradient (< 0.2 K) across the sample. The
apparatus can be calibrated precisely using a copper coil connected in series
with the primary coil. The system has been used successfully to measure the
temperature dependence of the AC magnetic properties of entire RE-Ba-Cu-O
[(RE)BCO] bulk superconducting domains. A typical AC susceptibility measurement
run from 78 K to 95 K takes about 2 hours, with excellent temperature
resolution (temperature step ~ 4 mK) around the critical temperature, in
particular.


title:
New conditional symmetries and exact solutions of reaction-diffusion
  systems with power diffusivities

abstract:
  A wide range of new Q-conditional symmetries for reaction-diffusion systems
with power diffusivities are constructed. The relevant non-Lie ansatze to
reduce the reaction-diffusion systems to ODE systems and examples of exact
solutions are obtained. The relation of the solutions obtained with the
development of spatially inhomogeneous structures is discussed.


title: Nonlinear magnetic diffusivity and alpha tensors in helical turbulence

abstract:
  The effect of a dynamo-generated mean magnetic field of Beltrami type on the
mean electromotive force is studied. In the absence of the mean magnetic field
the turbulence is assumed to be homogeneous and isotropic, but it becomes
inhomogeneous and anisotropic with this field. Using the testfield method the
dependence of the alpha and turbulent diffusivity tensors on the magnetic
Reynolds number Rm is determined for magnetic fields that have reached
approximate equipartition with the velocity field. The tensor components are
characterized by a pseudoscalar alpha and a scalar turbulent magnetic
diffusivity etat. Increasing Rm from 2 to 600 reduces etat by a factor ~5,
suggesting that the quenching of etat is, in contrast to the 2-dimensional
case, only weakly dependent on Rm. Over the same range of Rm, however, alpha is
reduced by a factor ~14, which can qualitatively be explained by a
corresponding increase of a magnetic contribution to the alpha effect with
opposite sign. The level of fluctuations of alpha and etat is only 10% and 20%
of the respective kinematic reference values.


title:
Assessment of effective parameters on dilution using approximate
  reasoning methods in longwall mining method, Iran coal mines

abstract:
  Approximately more than 90% of all coal production in Iranian underground
mines is derived directly longwall mining method. Out of seam dilution is one
of the essential problems in these mines. Therefore the dilution can impose the
additional cost of mining and milling. As a result, recognition of the
effective parameters on the dilution has a remarkable role in industry. In this
way, this paper has analyzed the influence of 13 parameters (attributed
variables) versus the decision attribute (dilution value), so that using two
approximate reasoning methods, namely Rough Set Theory (RST) and Self
Organizing Neuro- Fuzzy Inference System (SONFIS) the best rules on our
collected data sets has been extracted. The other benefit of later methods is
to predict new unknown cases. So, the reduced sets (reducts) by RST have been
obtained. Therefore the emerged results by utilizing mentioned methods shows
that the high sensitive variables are thickness of layer, length of stope, rate
of advance, number of miners, type of advancing.


title:
A limiting rule for the variability of coding sequence length in
  microbial genomes

abstract:
  The mean length and the variability of coding sequences for 48 genomes of
bacteria and archaea were analyzed. It was found that the plotted data can be
described by an angular area. This suggests the followings: a) The variability
of a genome increases as the mean length increases; b) There is an upper and a
lower limit for variability for a given mean length; c) Extrapolation of the
upper and lower limits to lower mean values converges to a single point which
might be assimilated to a primordial cell. The whole picture is reminding of a
process which starts from a single cell and evolves into more and more species
which, in turn, show more and more variability.


title:
A multi-coloured survey of NGC 253 with XMM-Newton: testing the methods
  used for creating luminosity functions from low-count data

abstract:
  NGC 253 is a local, star-bursting spiral galaxy with strong X-ray emission
from hot gas, as well as many point sources. We have conducted a spectral
survey of the X-ray population of NGC 253 using a deep XMM-Newton
observation.NGC 253 only accounts for ~20% of the XMM-Newton EPIC field of
view, allowing us to identify ~100 X-ray sources that are unlikely to be
associated with NGC\thinspace 253. Hence we were able to make a direct estimate
of contamination from e.g. foreground stars and background galaxies.
  X-ray luminosity functions (XLFs) of galaxy populations are often used to
characterise their properties. There are several methods for estimating the
luminosities of X-ray sources with few photons. We have obtained spectral fits
for the brightest 140 sources in the 2003 XMM-Newton observation of NGC 253,
and compare the best fit luminosities of those 69 non-nuclear sources
associated with NGC 253 with luminosities derived using other methods.
  We find the luminosities obtained from these various methods to vary
systematically by a factor of up to three for the same data; this is largely
due to differences in absorption.
  We therefore conclude that assuming Galactic absorption is probably unwise;
rather, one should measure the absorption for the population.
  A remarkable correlation has been reported between the XLFs of galaxies and
their star formation rates. However, the XLFs used in that study were obtained
using several different methods. If the sample galaxies were revisited and a
single method were applied, then this correlation may become stronger still.


title: The $\square_b$ Heat Equation and Multipliers via the Wave Equation

abstract:
  Recently, Nagel and Stein studied the $\square_b$-heat equation, where
$\square_b$ is the Kohn Laplacian on the boundary of a weakly-pseudoconvex
domain of finite type in $\C^2$. They showed that the Schwartz kernel of
$e^{-t\square_b}$ satisfies good "off-diagonal" estimates, while that of
$e^{-t\square_b}-\pi$ satisfies good "on-diagonal" estimates, where $\pi$ is
the Szeg\"o projection. We offer a simple proof of these results, which easily
generalizes to other, similar situations. Our methods involve adapting the
well-known relationship between the heat equation and the finite propagation
speed of the wave equation to this situation. In addition, we apply these
methods to study multipliers of the form $m\l(\square_b\r)$. In particular, we
show that $m\l(\square_b\r)$ is an NIS operator, where $m$ satisfies an
appropriate Mihlin-H\"ormander condition.


title: Physically-Relativized Church-Turing Hypotheses

abstract:
  We turn `the' Church-Turing Hypothesis from an ambiguous source of
sensational speculations into a (collection of) sound and well-defined
scientific problem(s):
  Examining recent controversies, and causes for misunderstanding, concerning
the state of the Church-Turing Hypothesis (CTH), suggests to study the CTH
relative to an arbitrary but specific physical theory--rather than vaguely
referring to ``nature'' in general. To this end we combine (and compare)
physical structuralism with (models of computation in) complexity theory. The
benefit of this formal framework is illustrated by reporting on some previous,
and giving one new, example result(s) of computability and complexity in
computational physics.


title: Testability of Reversible Iterative Logic Arrays

abstract:
  Iterative Logic Arrays (ILAs) are ideal as VLSI sub-systems because of their
regular structure and its close resemblance with FPGAs (Field Programmable Gate
Arrays). Reversible circuits are of interest in the design of very low power
circuits where energy loss implied by high frequency switching is not of much
consideration. Reversibility is essential for Quantum Computing. This paper
examines the testability of Reversible Iterative Logic Arrays (ILAs) composed
of reversible k-CNOT gates. For certain ILAs it is possible to find a test set
whose size remains constant irrespective of the size of the ILA, while for
others it varies with array size. Former type of ILAs is known as
Constant-Testable, i.e. C-Testable. It has been shown that Reversible Logic
Arrays are C-Testable and size of test set is equal to number of entries in
cells truth table implying that the reversible ILAs are also Optimal-Testable,
i.e. O-Testable. Uniform-Testability, i.e. U-Testability has been defined and
Reversible Heterogeneous ILAs have been characterized as U-Testable. The test
generation problem has been shown to be related to certain properties of cycles
in a set of graphs derived from cell truth table. By careful analysis of these
cycles an efficient test generation technique that can be easily converted to
an ATPG program has been presented for both 1-D and 2D ILAs. The same
algorithms can be easily extended for n-Dimensional Reversible ILAs.


title:
Parity-violating macroscopic force between chiral molecules and source
  mass

abstract:
  A theory concerning non-zero macroscopic chirality-dependent force between a
source mass and homochiral molecules due to the exchange of light particles is
presented in this paper. This force is proposed to have opposite sign for
molecules with opposite chirality. Using the central field approximation, we
calculate this force between a copper block and a vessel of chiral molecules
(methyl phenyl carbinol nitrite). The magnitude of force is estimated with the
published limits of the scalar and pseudo-scalar coupling constants. Based on
our theoretical model, this force may violate the equivalence principle when
the homochiral molecules are used to be the test masses.


title: Finite wavelength cloaking by plasmonic resonance

abstract:
  We consider cloaking by a coated cylindrical system using plasmonic
resonance, and extend previous quasistatic treatments to include the effect of
finite wavelength. We show that a probe cylinder can still be cloaked at finite
wavelengths, but the cloaking cylinder develops a non-zero scattering
cross-section. We show that this latter effect is dominated by a monopole term
in the case of an ideal (lossless) cloaking material, and by a dipole term in
the case of a realistic (lossy) material. It can be reduced but not eliminated
by variations of geometric or dielectric parameters of the cloaking cylinder.


title:
A Simple Dynamic Mind-map Framework To Discover Associative
  Relationships in Transactional Data Streams

abstract:
  In this paper, we informally introduce dynamic mind-maps that represent a new
approach on the basis of a dynamic construction of connectionist structures
during the processing of a data stream. This allows the representation and
processing of recursively defined structures and avoids the problem of a more
traditional, fixed-size architecture with the processing of input structures of
unknown size. For a data stream analysis with association discovery, the
incremental analysis of data leads to results on demand. Here, we describe a
framework that uses symbolic cells to calculate associations based on
transactional data streams as it exists in e.g. bibliographic databases. We
follow a natural paradigm of applying simple operations on cells yielding on a
mind-map structure that adapts over time.


title:
A note on extension of sliced average variance estimation to
  multivariate regression

abstract:
  This paper has been withdrawn because the Editor of Electronical Journal of
Statistics declined the paper.


title:
A new molecular dynamics calculation and its application to the spectra
  of light and strange baryons

abstract:
  A new approach based on antisymmetrized molecular dynamics is proposed to
correctly take account of the many-body correlation. We applied it to the
spectra of low-lying, light and strange baryons. The inclusion of the
quark-quark correlation is vital to predict the precise spectra, and the
semi-relativistic kinematics is also important to correct the level ordering.
The baryon spectra calculated by the present method is as precise as the
Faddeev calculation.


title:
Non-Gaussianity, Isocurvature Perturbation, Gravitational Waves and a
  No-Go Theorem for Isocurvaton

abstract:
  We investigate the isocurvaton model, in which the isocurvature perturbation
plays a role in suppressing the curvature perturbation, and large
non-Gaussianity and gravitational waves can be produced with no isocurvature
perturbation for dark matter. We show that in the slow roll non-interacting
multi-field theory, the isocurvaton mechanism can not be realized. This result
can also be generalized to most of the studied models with generalized kinetic
terms. We also study the implications for the curvaton model. We show that
there is a combined constraint for curvaton on non-Gaussianity, gravitational
waves and isocurvature perturbation. The technique used in this paper can also
help to simplify some calculations in the mixed inflaton and curvaton models.
We also investigate possibilities to produce large negative non-Gaussianity and
nonlocal non-Gaussianity in the curvaton model.


title: Throughput and Delay Analysis of Wireless Random Access Networks

abstract:
  This paper studies the network throughput and transport delay of a multihop
wireless random access network based on a Markov renewal model of packet
transportation. We show that the distribution of the source-to-destination (SD)
distance plays a critical role in characterizing network performance. We
establish necessary and sufficient condition on the SD distance for scalable
network throughput, and address the optimal rate allocation issue with fairness
and the QoS requirements taken into consideration. In respect to the end-to-end
performance, the transport delay is explored in this paper along with network
throughput. We characterize the transport delay by relating it to nodal
queueing behavior and the SD-distance distribution; the former is a local
property while the latter is a global property. In addition, we apply the large
deviation theory to derive the tail distribution of transport delay. To put our
theory into practical network operation, several traffic scaling laws are
provided to demonstrate how network scalability can be achieved by localizing
the traffic pattern, and a leaky bucket scheme at the network access is
proposed for traffic shaping and flow control.


title: Hierarchical Models, Marginal Polytopes, and Linear Codes

abstract:
  In this paper, we explore a connection between binary hierarchical models,
their marginal polytopes and codeword polytopes, the convex hulls of linear
codes. The class of linear codes that are realizable by hierarchical models is
determined. We classify all full dimensional polytopes with the property that
their vertices form a linear code and give an algorithm that determines them.


title: Genus two curves with quaternionic multiplication and modular jacobian

abstract:
  We describe a method to determine all the isomorphism classes of principal
polarizations of the modular abelian surfaces $A_f$ with quaternionic
multiplication attached to a normalized newform $f$ without complex
multiplication. We include an example of $A_f$ with quaternionic multiplication
for which we find numerically a curve $C$ whose Jacobian is $A_f$ up to
numerical approximation, and we prove that it has quaternionic multiplication
and is isogenous to $A_f$.


title:
Chiral Condensate at Nonzero Chemical Potential in the Microscopic Limit
  of QCD

abstract:
  The chiral condensate in QCD at zero temperature does not depend on the quark
chemical potential (up to one third the nucleon mass), whereas the spectral
density of the Dirac operator shows a strong dependence on the chemical
potential. The cancellations which make this possible also occur on the
microscopic scale, where they can be investigated by means of a random matrix
model. We show that they can be understood in terms of orthogonality properties
of orthogonal polynomials. In the strong non-Hermiticity limit they are related
to integrability properties of the spectral density. As a by-product we find
exact analytical expressions for the partially quenched chiral condensate in
the microscopic domain at nonzero chemical potential.


title: Models of some simple modular Lie superalgebras

abstract:
  Models of the exceptional simple modular Lie superalgebras in characteristic
$p\geq 3$, that have appeared in the classification due to Bouarroudj, Grozman
and Leites of the Lie superalgebras with indecomposable symmetrizable Cartan
matrices, are provided. The models relate these exceptional Lie superalgebras
to some low dimensional nonassociative algebraic systems.


title: Tropical Resultants for Curves and Stable Intersection

abstract:
  We introduce the notion of resultant of two planar curves in the tropical
geometry framework. We prove that the tropicalization of the algebraic
resultant can be used to compute the stable intersection of two tropical plane
curves. It is shown that, for two generic preimages of the curves to an
algebraic framework, their intersection projects exactly onto the stable
intersection of the curves. It is also given sufficient conditions for such a
generality in terms of the residual coefficients of the algebraic coefficients
of defining equations of the curves.


title:
The Finite Horizon Optimal Multi-Modes Switching Problem: the Viscosity
  Solution Approach

abstract:
  In this paper we show existence and uniqueness of a solution for a system of
m variational partial differential inequalities with inter-connected obstacles.
This system is the deterministic version of the Verification Theorem of the
Markovian optimal m-states switching problem. The switching cost functions are
arbitrary. This problem is in relation with the valuation of firms in a
financial market.


title: Canonical metrics on Hartogs domains

abstract:
  An $n$-dimensional Hartogs domain $D_F$ with strongly pseudoconvex boundary
can be equipped with a natural Kaehler metric $g_F$. This paper contains two
results. In the first one we prove that if $g_F$ is an extremal Kaehler metric
then $(D_F, g_F)$ is holomorphically isometric to an open subset of the
$n$-dimensional complex hyperbolic space. In the second one we prove the same
assertion under the assumption that there exists a real holomorphic vector
field $X$ on $D_F$ such that $(g_F, X)$ is a Kaehler-Ricci soliton.


title: Algebraic Topology of Spin Glasses

abstract:
  We study topology of frustration in $d$-dimensional Ising spin glasses with
$d\ge 2$ with nearest-neighbor interactions. We prove the following: For any
given spin configuration, the domain walls on the unfrustration network are all
transverse to a frustrated loop on the unfrustration network, where a domain
wall is defined to be a connected element of the collection of all the
$(d-1)$-cells which are dual to the bonds having an unfavorable energy, and the
unfrustration network is the collection of all the unfrustrated plaquettes.
These domain walls are topologically nontrivial because they are all related to
the global frustration of a loop on the unfrustration network. Taking account
of the thermal stability for the domain walls, we can explain the numerical
results that three or higher dimensional systems exhibit a spin glass phase,
whereas two-dimensional ones do not. Namely, in two dimensions, the thermal
fluctuations of the topologically nontrivial domain walls destroy the order of
the frozen spins on the unfrustration network, whereas they do not in three or
higher dimensions. This may be interpreted as a global, topological effect of
the frustrations.


title: Functional Optimization in Complex Excitable Networks

abstract:
  We study the effect of varying wiring in excitable random networks in which
connection weights change with activity to mold local resistance or
facilitation due to fatigue. Dynamic attractors, corresponding to patterns of
activity, are then easily destabilized according to three main modes, including
one in which the activity shows chaotic hopping among the patterns. We describe
phase transitions to this regime, and show a monotonous dependence of critical
parameters on the heterogeneity of the wiring distribution. Such correlation
between topology and functionality implies, in particular, that tasks which
require unstable behavior --such as pattern recognition, family discrimination
and categorization-- can be most efficiently performed on highly heterogeneous
networks. It also follows a possible explanation for the abundance in nature of
scale--free network topologies.


title: Attractors in Black

abstract:
  We review recent results in the study of attractor horizon geometries (with
non-vanishing Bekenstein-Hawking entropy) of dyonic extremal d=4 black holes in
supergravity. We focus on N=2, d=4 ungauged supergravity coupled to a number
n_{V} of Abelian vector multiplets, outlining the fundamentals of the special
Kaehler geometry of the vector multiplets' scalar manifold (of complex
dimension n_{V}), and studying the 1/2-BPS attractors, as well as the non-BPS
(non-supersymmetric) ones with non-vanishing central charge.
  For symmetric special Kaehler geometries, we present the complete
classification of the orbits in the symplectic representation of the classical
U-duality group (spanned by the black hole charge configuration supporting the
attractors), as well as of the moduli spaces of non-BPS attractors (spanned by
the scalars which are not stabilized at the black hole event horizon).
  Finally, we report on an analogous classification for N>2-extended, d=4
ungauged supergravities, in which also the 1/N-BPS attractors yield a related
moduli space.


title:
Upper bounds for Total Cross Section in scattering by an obstacle with
  impedance boundary conditions

abstract:
  The scalar scattering of a plane wave by a smooth obstacle with impedance
boundary conditions is considered. Upper bounds for the Total Cross Section and
for the absorbed power are presented.


title: A Method for Constructing a Lax Pair for the Ernst Equation

abstract:
  A systematic construction of a Lax pair and an infinite set of conservation
laws for the Ernst equation is described. The matrix form of this equation is
rewritten as a differential ideal of gl(2,R)-valued differential forms, and its
symmetry condition is expressed as an exterior equation which is linear in the
symmetry characteristic and has the form of a conservation law. By means of a
recursive process, an infinite collection of such laws is then obtained, and
the conserved "charges" are used to derive a linear exterior equation whose
components constitute a Lax pair.


title:
The Fujita Exponent for Semilinear Heat Equations with Quadratically
  Decaying Potential or in an Exterior Domain

abstract:
  Consider the equation
  u_t=\Delta u-Vu +au^p \text{in} R^n\times (0,T);
  u(x,0)=\phi(x)\gneq0, \text{in} R^n,
  where $p>1$, $n\ge2$, $T\in(0,\infty]$, $V(x)\sim\frac\omega{|x|^2}$ as
$|x|\to\infty$, for some $\omega\neq0$, and $a(x)$ is on the order $|x|^m$ as
$|x|\to\infty$, for some $m\in (-\infty,\infty)$. A solution to the above
equation is called global if $T=\infty$. Under some additional technical
conditions, we calculate a critical exponent $p^*$ such that global solutions
exist for $p>p^*$, while for $1<p\le p^*$, all solutions blow up in finite
time. We also show that when $V\equiv0$, the blow-up/global solution dichotomy
for \eqref{abstract} coincides with that for the corresponding problem in an
exterior domain with the Dirichlet boundary condition, including the case in
which $p$ is equal to the critical exponent.


title:
Non-Markovian dynamics of a single electron spin coupled to a nuclear
  spin bath

abstract:
  We apply the time-convolutionless (TCL) projection operator technique to the
model of a central spin which is coupled to a spin bath via nonuniform
Heisenberg interaction. The second-order results of the TCL method for the
coherences and populations of the central spin are determined analytically and
compared with numerical simulations of the full von Neumann equation of the
total system. The TCL approach is found to yield an excellent approximation in
the strong field regime for the description of both the short-time dynamics and
the long time behavior.


title:
Apparent superluminal advancement of a single photon far beyond its
  coherence length

abstract:
  We present experimental results relative to superluminal propagation based on
a single photon traversing an optical system, called 4f-system, which acts
singularly on the photon's spectral component phases. A single photon is
created by a CW laser light down{conversion process. The introduction of a
linear spectral phase function will lead to the shift of the photon peak far
beyond the coherence length of the photon itself (an apparent superluminal
propagation of the photon). Superluminal group velocity detection is done by
interferometric measurement of the temporal shifted photon with its correlated
untouched reference. The observed superluminal photon propagation complies with
causality. The operation of the optical system allows to enlighten the origin
of the apparent superluminal photon velocity. The experiment foresees a
superluminal effect with single photon wavepackets.


title:
New Anomalies in Cosmic Microwave Background Anisotropy: Violation of
  the Isotropic Gaussian Hypothesis in Low-$l$ Modes

abstract:
  In the standard framework of cosmology, primordial density fluctuations are
assumed to have an isotropic Gaussian distribution. We search for deviations
from this assumption in the WMAP data for the low $l$ modes of Cosmic Microwave
Background Anisotropies (CMBA), by studying the directions of the z-axis that
maximize the $l=m$ modes and the resulting amplitudes of these modes. We find a
general alignment of the directions for $l=2$ to 10 modes to within 1/4 of the
northern hemisphere. This alignment can be regarded as a generalization of the
recently discovered alignment of the $l=2$ and 3 modes - the so-called `Axis of
Evil'. Furthermore, we find abnormally high (low) powers in the $l=m=6$, 12 -
17 ($l=m=5$) modes; the probabilities for having the anomalous amplitudes of
the $l=m=5$, 6, 17 modes are about 0.1%, 1% and 1% respectively according to
the Gaussian conjecture. The alignment and anomalous amplitudes for these low
$l$ modes are very robust against foreground contamination or different
cleaning strategies, suggesting a cosmological origin and possibly supporting a
non-standard inflation.


title:
Branching Fractions and CP-Violating Asymmetries in Radiative B Decays
  to eta K gamma

abstract:
  We present measurements of the CP-violation parameters S and C for the
radiative decay B0 -> eta K0s gamma; for B -> eta K gamma we also measure the
branching fractions and for B+ -> eta K+ gamma the time-integrated charge
asymmetry Ach. The data, collected with the BaBar detector at the Stanford
Linear Accelerator Center, represent $465 \times 10^6$ BBbar pairs produced in
$e^{+} e^{-}$ annihilation. The results are $S = -0.18^{+0.49}_{-0.46} \pm
0.12$, $C = -0.32^{+0.40}_{-0.39} \pm 0.07$, BF(B0 -> eta K0 gamma) =
$(7.1^{+2.1}_{-2.0} \pm 0.4) \times 10^{-6}$, BF(B+ -> eta K+ gamma) =
$(7.7+-1.0 \pm 0.4) \times 10^{-6}$, and Ach = $(-9.0^{+10.4}_{-9.8} \pm 1.4)
\times 10^{-2}$. The first error quoted is statistical and the second
systematic.


abstract:
  Necessary and sufficient conditions for bipartite entanglement are derived,
which apply to arbitrary Hilbert spaces. Motivated by the concept of witnesses,
optimized entanglement inequalities are formulated solely in terms of arbitrary
Hermitian operators, which makes them useful for applications in experiments.
The needed optimization procedure is based on a separability eigenvalue
problem, whose analytical solutions are derived for a special class of
projection operators. For general Hermitian operators, a numerical
implementation of entanglement tests is proposed. It is also shown how to
identify bound entangled states with positive partial transposition.


title:
Emergence, Competition and Dynamical Stabilization of Dissipative
  Rotating Spiral Waves in an Excitable Medium: A Computational Model Based on
  Cellular Automata

abstract:
  We report some qualitatively new features of emergence, competition and
dynamical stabilization of dissipative rotating spiral waves (RSWs) in the
cellular-automaton model of laser-like excitable media proposed in
arXiv:cond-mat/0410460v2 ; arXiv:cond-mat/0602345 . Part of the observed
features are caused by unusual mechanism of excitation vorticity when the RSW's
core get into the surface layer of an active medium. Instead of the well known
scenario of RSW collapse, which takes place after collision of RSW's core with
absorbing boundary, we observed complicated transformations of the core leading
to regeneration (nonlinear "reflection" from the boundary) of the RSW or even
to birth of several new RSWs in the surface layer. Computer experiments on
bottlenecked evolution of such the RSW-ensembles (vortex matter) are reported
and a possible explanation of real experiments on spin-lattice relaxation in
dilute paramagnets is proposed on the basis of an analysis of the RSWs
dynamics. Chimera states in RSW-ensembles are revealed and compared with
analogous states in ensembles of nonlocally coupled oscillators. Generally, our
computer experiments have shown that vortex matter states in laser-like
excitable media have some important features of aggregate states of the usual
matter.


title:
Spin dynamics in (III,Mn)V ferromagnetic semiconductors: the role of
  correlations

abstract:
  We address the role of correlations between spin and charge degrees of
freedom on the dynamical properties of ferromagnetic systems governed by the
magnetic exchange interaction between itinerant and localized spins. For this
we introduce a general theory that treats quantum fluctuations beyond the
Random Phase Approximation based on a correlation expansion of the Green's
function equations of motion. We calculate the spin susceptibility, spin--wave
excitation spectrum, and magnetization precession damping. We find that
correlations strongly affect the magnitude and carrier concentration dependence
of the spin stiffness and magnetization Gilbert damping.


title:
Optical Study of LaO_0.9F_0.1FeAs: Evidence for a Weakly Coupled
  Superconducting State

abstract:
  We have studied the reflectance of the recently discovered superconductor
LaO_0.9F0.FeAs in a wide energy range from the far infrared to the visible
regime. We report on the observation of infrared active phonons, the plasma
edge (PE) and possible interband transitions. On the basis of this data and the
reported in-plane penetration depth lambda_L(0) about 254 nm [H. Luetkens et
al., Phys. Rev. Lett. v. 101, 0970009 (2008)] a disorder sensitive relatively
small value of the total electron electron-boson coupling constant
lambda_tot=lambda_e-ph+lambda_e-sp ~ 0.6 +- 0.35 can be estimated adopting an
effective single-band picture.


title:
Recurrence properties of unbiased coined quantum walks on infinite
  $d$-dimensional lattices

abstract:
  The P\'olya number characterizes the recurrence of a random walk. We apply
the generalization of this concept to quantum walks [M. \v{S}tefa\v{n}\'ak, I.
Jex and T. Kiss, Phys. Rev. Lett. \textbf{100}, 020501 (2008)] which is based
on a specific measurement scheme. The P\'olya number of a quantum walk depends
in general on the choice of the coin and the initial coin state, in contrast to
classical random walks where the lattice dimension uniquely determines it. We
analyze several examples to depict the variety of possible recurrence
properties. First, we show that for the class of quantum walks driven by
independent coins for all spatial dimensions, the P\'olya number is independent
of the initial conditions and the actual coin operators, thus resembling the
property of the classical walks. We provide an analytical estimation of the
P\'olya number for this class of quantum walks. Second, we examine the 2-D
Grover walk, which exhibits localisation and thus is recurrent, except for a
particular initial state for which the walk is transient. We generalize the
Grover walk to show that one can construct in arbitrary dimensions a quantum
walk which is recurrent. This is in great contrast with the classical walks
which are recurrent only for the dimensions $d=1,2$. Finally, we analyze the
recurrence of the 2-D Fourier walk. This quantum walk is recurrent except for a
two-dimensional subspace of the initial states. We provide an analytical
formula of the P\'olya number in its dependence on the initial state.


title: A trace formula for varieties over a discretely valued field

abstract:
  We study the motivic Serre invariant of a smoothly bounded algebraic or rigid
variety $X$ over a complete discretely valued field $K$ with perfect residue
field $k$. If $K$ has characteristic zero, we extend the definition to
arbitrary $K$-varieties using Bittner's presentation of the Grothendieck ring
and a process of N\'eron smoothening of pairs of varieties.
  The motivic Serre invariant can be considered as a measure for the set of
unramified points on $X$. Under certain tameness conditions, it admits a
cohomological interpretation by means of a trace formula. In the curve case, we
use T. Saito's geometric criterion for cohomological tameness to obtain more
detailed results. We discuss some applications to Weil-Ch\^atelet groups, Chow
motives, and the structure of the Grothendieck ring.


title:
Comparative Studies on Giant Magnetoresistance in Carbon Nanotubes and
  Graphene Nanoribbons with Ferromagnetic Contacts

abstract:
  This contribution reports on comparative studies on giant magnetoresistance
(GMR) in carbon nanotubes (CNTs) and graphene nanoribbons of similar aspect
ratios (i.e perimeter/length and width/length ratios, for the former and the
latter, respectively). The problem is solved at zero temperature in the
ballistic transport regime, by means of the Green's functions technique within
the tight-binding model and with the so-called wide band approximation for
electrodes. The GMR effect in graphene is comparable to that of CNTs, it
depends strongly on the chirality and only slightly on the aspect ratio. It
turns out that graphene, analogously to CNTs may be quite an interesting
material for spintronic applications.


title: Classification of bijections between 321- and 132-avoiding permutations

abstract:
  It is well-known, and was first established by Knuth in 1969, that the number
of 321-avoiding permutations is equal to that of 132-avoiding permutations. In
the literature one can find many subsequent bijective proofs of this fact. It
turns out that some of the published bijections can easily be obtained from
others. In this paper we describe all bijections we were able to find in the
literature and show how they are related to each other via ``trivial''
bijections. We classify the bijections according to statistics preserved (from
a fixed, but large, set of statistics), obtaining substantial extensions of
known results. Thus, we give a comprehensive survey and a systematic analysis
of these bijections. We also give a recursive description of the algorithmic
bijection given by Richards in 1988 (combined with a bijection by Knuth from
1969). This bijection is equivalent to the celebrated bijection of Simion and
Schmidt (1985), as well as to the bijection given by Krattenthaler in 2001, and
it respects 11 statistics--the largest number of statistics any of the
bijections respects.


title: Hydrodynamic limit of particle systems with long jumps

abstract:
  We consider some interacting particle processes with long-range dynamics: the
zero-range and exclusion processes with long jumps. We prove that the
hydrodynamic limit of these processes corresponds to a (possibly non-linear)
fractional heat equation. The scaling in this case is superdiffusive. In
addition, we discuss a central limit theorem for a tagged particle on the
zero-range process and existence and uniqueness of solutions of the Cauchy
problem for the fractional heat equation.


title:
Bit-Interleaved Coded Modulation Revisited: A Mismatched Decoding
  Perspective

abstract:
  We revisit the information-theoretic analysis of bit-interleaved coded
modulation (BICM) by modeling the BICM decoder as a mismatched decoder. The
mismatched decoding model is well-defined for finite, yet arbitrary, block
lengths, and naturally captures the channel memory among the bits belonging to
the same symbol. We give two independent proofs of the achievability of the
BICM capacity calculated by Caire et al. where BICM was modeled as a set of
independent parallel binary-input channels whose output is the bitwise
log-likelihood ratio. Our first achievability proof uses typical sequences, and
shows that due to the random coding construction, the interleaver is not
required. The second proof is based on the random coding error exponents with
mismatched decoding, where the largest achievable rate is the generalized
mutual information. We show that the generalized mutual information of the
mismatched decoder coincides with the infinite-interleaver BICM capacity. We
also show that the error exponent -and hence the cutoff rate- of the BICM
mismatched decoder is upper bounded by that of coded modulation and may thus be
lower than in the infinite-interleaved model. We also consider the mutual
information appearing in the analysis of iterative decoding of BICM with EXIT
charts. We show that the corresponding symbol metric has knowledge of the
transmitted symbol and the EXIT mutual information admits a representation as a
pseudo-generalized mutual information, which is in general not achievable. A
different symbol decoding metric, for which the extrinsic side information
refers to the hypothesized symbol, induces a generalized mutual information
lower than the coded modulation capacity.


title: Electromagnetic wave manipulation using layered systems

abstract:
  We show that the optical properties of an oblique layered system with two
kinds of isotropic materials can be described using the concept of
transformation media as long as the thickness of the layers is much smaller
than the wavelength. Once the connection with transformation media is
established, we then show that oblique layered system can serve as a universal
element to build a variety of interesting functional optical components such as
wave splitters, wave combiners, one-dimensional cloaking devices and
reflectionless field rotators.


title:
White noise analysis on manifolds and the energy representation of a
  gauge group

abstract:
  The energy representation of a gauge group on a Riemannian manifold has been
discussed by several authors. Y. Shimada has shown the irreducibility for
compact Riemannian manifold, using white noise analysis. In this paper we
extend its technique to noncompact Riemannian manifolds which have differential
operators satisfying some conditions.


title: Small deviations of general L\'{e}vy processes

abstract:
  We study the small deviation problem
$\log\mathbb{P}(\sup_{t\in[0,1]}|X_t|\leq\varepsilon)$, as $\varepsilon\to0$,
for general L\'{e}vy processes $X$. The techniques enable us to determine the
asymptotic rate for general real-valued L\'{e}vy processes, which we
demonstrate with many examples. As a particular consequence, we show that a
L\'{e}vy process with nonvanishing Gaussian component has the same (strong)
asymptotic small deviation rate as the corresponding Brownian motion.


title:
Quantum States Allowing Minimum Uncertainty Product of angular position
  and momentum

abstract:
  We provide necessary and sufficient conditions for states to have an
arbitrarily small uncertainty product of the azimuthal angle $\phi $ and its
canonical moment $L_{z}$. We illustrate our results with analytical examples.


title:
Momentum distributions of $\alpha$-particles from decaying low-lying
  $^{12}$C-resonances

abstract:
  The complex scaled hyperspherical adiabatic expansion method is used to
compute momentum and energy distributions of the three $\alpha$-particles
emerging from the decay of low-lying $^{12}$C-resonances. The large distance
continuum properties of the wave functions are crucial and must be accurately
calculated. We discuss separately decays of natural parity states: two $0^+$,
one $1^{-}$, three $2^+$, one $3^-$, two $4^+$, one $6^+$, and one of each of
unnatural parity, $1^{+}$, $2^-$, $3^+$, $4^-$. The lowest natural parity state
of each $J^{\pi}$ decays predominantly sequentially via the $^{8}$Be ground
state whereas other states including unnatural parity states predominantly
decay directly to the continuum. We present Dalitz plots and systematic
detailed momentum correlations of the emerging $\alpha$-particles.


title: Top quark physics at the LHC

abstract:
  The physics perspectives of the production and decay of single top quarks and
top quark pairs at the CERN Large Hadron Collider (LHC) are reviewed from a
phenomenological point of view.


title: Evolution of the correlation functions in 2D dislocation systems

abstract:
  In this paper spatial correlations of parallel edge dislocations are studied.
After closing a hierarchy of equations for the many-particle density functions
by the Kirkwood superposition approximation, we derive evolution equations for
the correlation functions. It is found that these resulting equations and those
governing the evolution of density fields of total as well as geometrically
necessary dislocations around a single edge dislocation are formally the same.
The second case corresponds to the already described phenomenon of Debye
screening of an individual dislocation. This equivalence of the correlation
functions and screened densities is demonstrated also by discrete dislocation
dynamics simulation results, which confirm the physical correctness of the
applied Kirkwood superposition approximation. Relation of this finding and the
linear response theory in thermal systems is also discussed.


title:
The luminosity function, halo masses and stellar masses of luminous
  Lyman-break galaxies at redshifts 5<z<6

abstract:
  We present the results of a study of a large sample of luminous (z'{AB}<26)
Lyman break galaxies (LBGs) in the redshift interval 4.7<z<6.3, selected from a
contiguous 0.63 square degree area covered by the UKIDSS Ultra Deep Survey
(UDS) and the Subaru XMM-Newton Survey (SXDS). Utilising the large area
coverage and the excellent available optical+nearIR data, we use a photometric
redshift analysis to derive a new, robust, measurement of the bright end (L>L*)
of the UV-selected luminosity function at high redshift. When combined with
literature studies of the fainter LBG population, our new sample provides
improved constraints on the luminosity function of redshift 5<z<6 LBGs over the
luminosity range 0.1L*<L<10L*. A maximum likelihood analysis returns
best-fitting Schechter function parameters of M*_1500=-20.73, phi*=0.0009
Mpc^-3 and alpha=-1.66 for the luminosity function at z=5, and M*_1500 =
-20.04, phi*=0.0018 Mpc^-3 and alpha=-1.71 at z=6. In addition, an analysis of
the angular clustering properties of our LBG sample demonstrates that luminous
5<z<6 LBGs are strongly clustered (r_0 = 8.1 Mpc), and are consistent with the
occupation of dark matter halos with masses of ~10^{11.5-12.0} Msun. Moreover,
by stacking the available multi-wavelength imaging data for the high-redshift
LBGs it is possible to place useful constraints on their typical stellar mass.
The results of this analysis suggest that luminous LBGs at 5<z<6 have an
average stellar mass of ~10^10 Msun, consistent with the results of the
clustering analysis assuming plausible values for the ratio of stellar to dark
matter. Finally, by combining our luminosity function results with those of the
stacking analysis we derive estimates of ~1x10^7 Msun Mpc^-3 and 4x10^6 Msun
Mpc^-3 for the stellar mass density at z~5 and z~6 respectively.


title: Extended Absolute Parallelism Geometry

abstract:
  In this paper, we study Absolute Parallelism (AP-) geometry on the tangent
bundle $TM$ of a manifold $M$. Accordingly, all geometric objects defined in
this geometry are not only functions of the positional argument $x$, but also
depend on the directional argument $y$. Moreover, many new geometric objects,
which have no counterpart in the classical AP-geometry, emerge in this
different framework. We refer to such a geometry as an Extended Absolute
Parallelism (EAP-) geometry. The building blocks of the EAP-geometry are a
nonlinear connection assumed given a priori and $2n$ linearly independent
vector fields (of special form) defined globally on $TM$ defining the
parallelization. Four different $d$-connections are used to explore the
properties of this geometry. Simple and compact formulae for the curvature
tensors and the W-tensors of the four defined $d$-connections are obtained,
expressed in terms of the torsion and the contortion tensors of the EAP-space.
Further conditions are imposed on the canonical $d$-connection assuming that it
is of Cartan type (resp. Berwald type). Important consequences of these
assumptions are investigated. Finally, a special form of the canonical
$d$-connection is studied under which the classical AP-geometry is recovered
naturally from the EAP-geometry. Physical aspects of some of the geometric
objects investigated are pointed out and possible physical implications of the
EAP-space are discussed, including an outline of a generalized field theory on
the tangent bundle $TM$ of $M$


title: Soft end-point and mass corrections to the eta' g*g* vertex function

abstract:
  Power-suppressed corrections arising from end-point integration regions to
the space-like vertex function of the massive eta'-meson virtual gluon
transition eta' - g*g* are computed. Calculations are performed within the
standard hard-scattering approach (HSA) and the running coupling method
supplemented by the infrared renormalon calculus. Contributions to the vertex
function from the quark and gluon contents of the eta' -meson are taken into
account and the Borel resummed expressions for F_{eta' g*g*}(Q2,\omega ,\eta),
as well as for F_{eta' g g*}}(Q^{2},\omega =\pm 1,\eta) and F_{eta'
g*g*}(Q^{2},\omega =0,\eta) are obtained. It is demonstrated that the
power-suppressed corrections \sim (\Lambda ^{2}/Q^{2})^{n}, in the explored
range of the total gluon virtuality 1 <Q2 < 25 GeV2, considerably enhance the
vertex function relative to the results found in the framework of the standard
HSA with a fixed coupling. Modifications generated by the eta ' -meson mass
effects are discussed.


title: Froggatt-Nielsen hierarchy and the neutrino mass matrix

abstract:
  We study the neutrino mass matrix derived from the seesaw mechanism in which
the neutrino Yukawa couplings and the heavy Majorana neutrino mass matrix are
controlled by the Froggatt-Nielsen mechanism. In order to obtain the large
neutrino mixings, two Froggatt-Nielsen fields are introduced with a complex
vacuum expectation values. As a by-product, CP violation is systematically
induced even if the order one couplings of FN fields are real. We show several
predictions of this model, such as theta_{13}, the Dirac CP phase, two Majorana
CP phases, the effective mass of the neutrinoless double beta decay and the
leptogenesis. The prediction of the branching ratio of mu to e+gamma is also
given in SUSY model.


title:
Beyond The Quenched (or Probe Brane) Approximation in Lattice (or
  Holographic) QCD

abstract:
  We propose a method to improve the quenched approximation. The method, based
on the worldline formalism, takes into account effects of quark loops. The idea
is useful mostly for AdS/CFT (holographic) calculations. To demonstrate the
method we estimate screening (string breaking) effects by a simple holographic
calculation.


title:
On the Secure Degrees of Freedom in the K-User Gaussian Interference
  Channel

abstract:
  This paper studies the K-user Gaussian interference channel with secrecy
constraints. Two distinct network models, namely the interference channel with
confidential messages and the one with an external eavesdropper, are analyzed.
Using interference alignment along with secrecy pre-coding at each transmitter,
it is shown that each user in the network can achieve non-zero secure Degrees
of Freedoms (DoFs) in both scenarios. In particular, the proposed coding scheme
achieves (K-2)/(2K-2) secure DoFs for each user in the interference channel
with confidential messages model, and (K-2)/2K secure DoFs in the case of an
external eavesdropper. The fundamental difference between the two scenarios
stems from the lack of channel state information (CSI) about the external
eavesdropper. Remarkably, the results establish the positive impact of
interference on the secrecy capacity of wireless networks.


title:
Detecting THz current fluctuations in a quantum point contact using a
  nanowire quantum dot

abstract:
  We use a nanowire quantum dot to probe high-frequency current fluctuations in
a nearby quantum point contact. The fluctuations drive charge transitions in
the quantum dot, which are measured in real-time with single-electron detection
techniques. The quantum point contact (GaAs) and the quantum dot (InAs) are
fabricated in different material systems, which indicates that the interactions
are mediated by photons rather than phonons. The large energy scales of the
nanowire quantum dot allow radiation detection in the long-wavelength infrared
regime.


title: A degree inequality for Lie algebras with a regular Poisson semi-center

abstract:
  For Lie algebras whose Poisson semi-center is a polynomial ring we give a
bound for the sum of the degrees of the generating semi-invariants. This bound
was previously known in many special cases.


title:
On the divine clockwork: the spectral gap for the correspondence limit
  of the Nelson diffusion generator for the atomic elliptic state

abstract:
  The correspondence limit of the atomic elliptic state in three dimensions is
discussed in terms of Nelson's stochastic mechanics. In previous work we have
shown that this approach leads to a limiting Nelson diffusion and here we
discuss in detail the invariant measure for this process and show that it is
concentrated on the Kepler ellipse in the plane z=0. We then show that the
limiting Nelson diffusion generator has a spectral gap; thereby proving that in
the infinite time limit the density for the limiting Nelson diffusion will
converge to its invariant measure. We also include a summary of the Cheeger and
Poincare inequalities both of which are used in our proof of the existence of
the spectral gap.


title: Hawking evaporation of cosmogenic black holes in TeV-gravity models

abstract:
  We study the properties of black holes of mass 10^4--10^{11} GeV in models
with the fundamental scale of gravity at the TeV. These black holes could be
produced in the collision of a ultrahigh energy cosmic ray with a dark matter
particle in our galactic halo or with another cosmic ray. We show that QCD
bremsstrahlung and pair production processes are unable to thermalize the
particles exiting the black hole, so a chromosphere is never formed during
Hawking evaporation. We evaluate with HERWIG the spectrum of stable 4-dim
particles emitted during the Schwarzschild phase and find that in all cases it
is peaked at energies around 0.2 GeV, with an approximate 43% of neutrinos, 28%
of photons, 16% of electrons and 13% of protons. Bulk gravitons are peaked at
higher energies, they account for a 0.4% of the particles (16% of the total
energy) emitted by the most massive black holes in n=6 extra dimensions or just
the 0.02% of the particles (1.4% of the energy) emitted by a 10 TeV black hole
for n=2.


title:
Variations on a theme of Runge: effective determination of integral
  points on certain varieties

abstract:
  We consider some variations on the classical method of Runge for effectively
determining integral points on certain curves. We first prove a version of
Runge's theorem valid for higher-dimensional varieties, generalizing a uniform
version of Runge's theorem due to Bombieri. We then take up the study of how
Runge's method may be expanded by taking advantage of certain coverings. We
prove both a result for arbitrary curves and a more explicit result for
superelliptic curves. As an application of our method, we solve certain
equations involving squares in products of terms in an arithmetic progression.


title:
Gauge Invariant Lagrangians for Free and Interacting Higher Spin Fields.
  A Review of the BRST formulation

abstract:
  We give a detailed review of the construction of gauge invariant Lagrangians
for free and interacting higher spin fields using the BRST approach developed
over the past few years.


title: Enhanced quantum tunnelling induced by disorder

abstract:
  We reconsider the problem of the enhancement of tunnelling of a quantum
particle induced by disorder of a one-dimensional tunnel barrier of length $L$,
using two different approximate analytic solutions of the invariant imbedding
equations of wave propagation for weak disorder. The two solutions are
complementary for the detailed understanding of important aspects of numerical
results on disorder-enhanced tunnelling obtained recently by Kim et al. (Phys.
rev. B{\bf 77}, 024203 (2008)). In particular, we derive analytically the
scaled wavenumber $(kL)$-threshold where disorder-enhanced tunnelling of an
incident electron first occurs, as well as the rate of variation of the
transmittance in the limit of vanishing disorder. Both quantities are in good
agreement with the numerical results of Kim et al. Our non-perturbative
solution of the invariant imbedding equations allows us to show that the
disorder enhances both the mean conductance and the mean resistance of the
barrier.


title: Searching for Frequent Colors in Rectangles

abstract:
  We study a new variant of colored orthogonal range searching problem: given a
query rectangle $Q$ all colors $c$, such that at least a fraction $\tau$ of all
points in $Q$ are of color $c$, must be reported. We describe several data
structures for that problem that use pseudo-linear space and answer queries in
poly-logarithmic time.


title: A note on the enumeration of directed animals via gas considerations

abstract:
  In the literature, most of the results about the enumeration of directed
animals on lattices via gas considerations are obtained by a formal passage to
the limit of enumeration of directed animals on cyclical versions of the
lattice. Here we provide a new point of view on this phenomenon. Using the gas
construction given in [Electron. J. Combin. (2007) 14 R71], we describe the gas
process on the cyclical versions of the lattices as a cyclical Markov chain
(roughly speaking, Markov chains conditioned to come back to their starting
point). Then we introduce a notion of convergence of graphs, such that if
$(G_n)\to G$ then the gas process built on $G_n$ converges in distribution to
the gas process on $G$. That gives a general tool to show that gas processes
related to animals enumeration are often Markovian on lines extracted from
lattices. We provide examples and computations of new generating functions for
directed animals with various sources on the triangular lattice, on the
$\mathcal {T}_n$ lattices introduced in [Ann. Comb. 4 (2000) 269--284] and on a
generalization of the $\mathcaligr {L}_n$ lattices introduced in [J. Phys. A 29
(1996) 3357--3365].


title:
Comment on "'t Hooft vertices, partial quenching, and rooted staggered
  QCD"

abstract:
  A recent criticism of the proof of the failure of the rooting procedure with
staggered fermions is shown to be incorrect.


title: Anisotropic flow: Achievements, Difficulties, Expectations

abstract:
  Anisotropic flow measurements play a crucial role in understanding the
physics and bulk properties of the system created in heavy ion collisions. In
this talk I briefly review the most important results obtained so far, recent
developments in the analysis techniques and the interpretation of the results,
and what should we expect next, both at RHIC and LHC. I also discuss event
anisotropies sensitive to the strong parity violation effects.


title:
PHENIX measurements of 3D emission source functions in Au+Au collisions
  at $\sqrt{s_{NN}} = 200$ GeV

abstract:
  A state-of-the-art 3D source imaging technique is used to extract the 3D
two-pion source function in central and mid-central Au+Au collisions at
$\sqrt{s_{NN}} = 200$ GeV. The source function indicates a previously
unresolved non-Gaussian tail in the directions of the pion pair transverse
momentum (out) and along the beam (long). Model comparisons give robust
estimates for several characteristics of the emission source, including its
transverse size, its mean proper breakup time $\tau$ and its emission duration
$\Delta\tau$. These estimates are incompatible with the predictions for a first
order phase transition. However, they point to significant relative emission
times which could result from a crossover phase transition.


title:
A model for interevent times with long tails and multifractality in
  human communications: An application to financial trading

abstract:
  Social, technological and economic time series are divided by events which
are usually assumed to be random albeit with some hierarchical structure. It is
well known that the interevent statistics observed in these contexts differs
from the Poissonian profile by being long-tailed distributed with resting and
active periods interwoven. Understanding mechanisms generating consistent
statistics have therefore become a central issue. The approach we present is
taken from the Continuous Time Random Walk formalism and represents an
analytical alternative to models of non-trivial priority that have been
recently proposed. Our analysis also goes one step further by looking at the
multifractal structure of the interevent times of human decisions. We here
analyze the inter-transaction time intervals of several financial markets. We
observe that empirical data describes a subtle multifractal behavior. Our model
explains this structure by taking the pausing-time density in the form of a
superstatistics where the integral kernel quantifies the heterogeneous nature
of the executed tasks. An stretched exponential kernel provides a multifractal
profile valid for a certain limited range. A suggested heuristic analytical
profile is capable of covering a broader region.


title: Planet Formation in Binary Stars: The case of Gamma Cephei

abstract:
  Over 30 planetary systems have been discovered to reside in binary stars. For
small separations gravitational perturbation of the secondary star has a strong
influence on the planet formation process. It truncates the protoplanetary
disk, may shortens its lifetime, and stirs up the embedded planetesimals. Due
to its small semi-major axis (18.5 AU) and large eccentricity (e=0.35) the
binary $\gamma$ Cephei represents a particularly challenging example. In the
present study we model the orbital evolution and growth of embedded
protoplanetary cores of about 30 earth masses in the putative protoplanetary
disk surrounding the primary star in the $\gamma$ Cep system. We assume
coplanarity of the disk, binary and planet and perform two-dimensional
hydrodynamic simulations of embedded cores in a protoplanetary disk. The
presence of the eccentric secondary star perturbs the disk periodically and
generates strong spiral arms at periapse which propagate toward the disk
centre. The disk also becomes slightly eccentric (with e_d = 0.1-0.15), and
displays a slow retrograde precession in the inertial frame. For all initial
separations (2.5 to 3.5 AU) we find inward migration of the cores. For initial
semi-major axes (a_p \gsim 2.7), we find a strong increase in the planetary
eccentricity despite the presence of inward migration. Only cores which are
initially far from the disk outer edge have a bounded orbital eccentricity
which converges, roughly to the value of the planet observed in the $\gamma$
Cep system. We have shown that under the condition protoplanetary cores can
form at around 2.5 AU, it is possible to evolve and grow such a core to form a
planet with final outcome similar to that observed.


title:
The core helium flash revisited: I. One and two-dimensional hydrodynamic
  simulations

abstract:
  We investigate the hydrodynamics of the core helium flash near its peak. Past
research concerned with the dynamics of this event is inconclusive. However,
the most recent multidimensional hydrodynamic studies suggest a quiescent
behavior and seem to rule out an explosive scenario. Previous work indicated,
that depending on initial conditions, employed turbulence models, grid
resolution, and dimensionality of the simulation, the core helium flash leads
either to the disruption of a low-mass star or to a quiescent quasi-hydrostatic
evolution. We try to clarify this issue by simulating the evolution with
advanced numerical methods and detailed microphysics. Assuming spherical or
axial symmetry, we simulate the evolution of the helium core of a $1.25
M_{\odot}$ star with a metallicity Z=0.02 during the core helium flash at its
peak with a grid-based hydrodynamics code. We find that the core helium flash
neither rips the star apart, nor that it significantly alters its structure, as
convection plays a crucial role in keeping the star in hydrostatic equilibrium.
In addition, our simulations show the presence of overshooting, which implies
new predictions concerning mixing of chemical species in red giants.


title:
Disorder-Induced Inhomogeneities of the Superconducting State Close to
  the Superconductor-Insulator Transition

abstract:
  Scanning tunneling spectroscopy at very low temperature on homogeneously
disordered superconducting Titanium Nitride thin films reveals strong spatial
inhomogeneities of the superconducting gap $\Delta$ in the density of states.
Upon increasing disorder, we observe suppression of the superconducting
critical temperature $T_c$ towards zero, enhancement of spatial fluctuations in
$\Delta$, and growth of the $\Delta/T_c$ ratio. These findings suggest that
local superconductivity survives across the disorder-driven
superconductor-insulator transition.


title:
Towards quantitative control on discreteness error in the non-linear
  regime of cosmological N body simulations

abstract:
  The effects of discreteness arising from the use of the N-body method on the
accuracy of simulations of cosmological structure formation are not currently
well understood. After a discussion of how the relevant discretisation
parameters introduced should be extrapolated to recover the Vlasov-Poisson
limit, we study numerically, and with analytical methods we have developed
recently, the central issue of how finite particle density affects the
precision of results. In particular we focus on the power spectrum at
wavenumbers around and above the Nyquist wavenumber, in simulations in which
the force resolution is taken smaller than the initial interparticle spacing.
Using simulations of identical theoretical initial conditions sampled on four
different "pre-initial" configurations (three different Bravais lattices, and a
glass) we obtain a {\it lower bound} on the real discreteness error. With the
guidance of our analytical results, we establish with confidence that the
measured dispersion is not contaminated either by finite box size effects or by
subtle numerical effects. Our results show notably that, at wavenumbers {\it
below} the Nyquist wavenumber, the dispersion increases monotonically in time
throughout the simulation, while the same is true above the Nyquist wavenumber
once non-linearity sets in. For normalizations typical of cosmological
simulations, we find lower bounds on errors at the Nyquist wavenumber of order
of a percent, and larger above this scale. The only way this error may be
reduced below these levels at these scales, and indeed convergence to the
physical limit firmly established, is by extrapolation, at fixed values of the
other relevant parameters, to the regime in which the mean comoving
interparticle distance becomes less than the force smoothing scale.


title:
Phonon background versus analogue Hawking radiation in Bose-Einstein
  condensates

abstract:
  We determine the feasibility of detecting analogue Hawking radiation in a
Bose-Einstein condensate in the presence of atom loss induced heating. We find
that phonons created by three-body losses overshadow those due to analogue
Hawking radiation. To overcome this problem, three-body losses may have to be
suppressed, for example as proposed by Search et al. [Phys. Rev. Lett. 92
140401 (2004)]. The reduction of losses to a few percent of their normal rate
is typically sufficient to suppress the creation of loss phonons on the time
scale of a fast analogue Hawking phonon detection.


title: Canonical triangulations of Dehn fillings

abstract:
  Every cusped, finite-volume hyperbolic three-manifold has a canonical
decomposition into ideal polyhedra. We study the canonical decomposition of the
hyperbolic manifold obtained by filling some (but not all) of the cusps with
solid tori: in a broad range of cases, generic in an appropriate sense, this
decomposition can be predicted from that of the unfilled manifold. As an
example, we treat all hyperbolic fillings on one cusp of the Whitehead link
complement.


title: Infinite self-gravitating systems and cosmological structure formation

abstract:
  The usual thermodynamic limit for systems of classical self-gravitating point
particles becomes well defined, as a {\it dynamical} problem, using a simple
physical prescription for the calculation of the force, equivalent to the
so-called ``Jeans' swindle''. The relation of the resulting intrinsically out
of equilibrium problem, of particles evolving from prescribed uniform initial
conditions in an infinite space, to the one studied in current cosmological
models (in an expanding universe) is explained. We then describe results of a
numerical study of the dynamical evolution of such a system, starting from a
simple class of infinite ``shuffled lattice'' initial conditions. The
clustering, which develops in time starting from scales around the grid scale,
is qualitatively very similar to that seen in cosmological simulations, which
begin from lattices with applied correlated displacements and incorporate an
expanding spatial background. From very soon after the formation of the first
non-linear structures, a spatio-temporal scaling relation describes well the
evolution of the two-point correlations. At larger times the dynamics of these
correlations converges to what is termed ``self-similar'' evolution in
cosmology, in which the time dependence in the scaling relation is specified
entirely by that of the linearized fluid theory. We show how this statistical
mechanical ``toy model'' can be useful in addressing various questions about
these systems which are relevant in cosmology. Some of these questions are
closely analagous to those currently studied in the literature on long range
interactions, notably the relation of the evolution of the particle system to
that in the Vlasov limit and the nature of approximately quasi-stationary
states.


title: Ideal class groups and torsion in Picard groups of varieties

abstract:
  We give a new general technique for constructing and counting number fields
with an ideal class group of nontrivial m-rank. Our results can be viewed as
providing a way of specializing the Picard group of a variety V over
$\mathbb{Q}$ to obtain class groups for number fields $\mathbb{Q}(P)$, $P\in
V(\Qbar)$, for certain families of points P. In particular, we show how the
problem of constructing quadratic number fields with a large-rank ideal class
group can be reduced to the problem of finding a hyperelliptic curve with a
rational Weierstrass point and a large rational torsion subgroup in its
Jacobian. Furthermore, we show how many previous results on constructing
large-rank ideal class groups can be fit into our framework and rederived. As
an application of our technique, we derive a quantitative version of a theorem
of Nakano. This gives the best known general quantitative result on number
fields with a large-rank ideal class group.


title:
The ionizing radiation from massive stars and its impact on HII regions:
  results from modern model atmospheres

abstract:
  We present a detailed comparison of the ionizing spectral energy
distributions (SEDs) predicted by four modern stellar atmosphere codes, TLUSTY,
CMFGEN, WMbasic, and FASTWIND. We consider three sets of stellar parameters
representing a late O-type dwarf (O9.5 V), a mid O-type (O7 V) dwarf, and an
early O-type dwarf (O5.5 V). We explore two different possibilities for such a
comparison, following what we called evolutionary and observational approaches:
in the evolutionary approach one compares the SEDs of stars defined by the same
values of Teff and logg; in the observational approach the models to be
compared do not necessarily have the same Teff and logg, but produce similar H
and HeI-II optical lines. We find that there is a better agreement, in terms of
Q(H0), the ratio Q(He0)/Q(H0), and the shape of the SEDs predicted by the four
codes in the spectral range between 13 and 30 eV, when models are compared
following the observational approach. However, even in this case, large
differences are found at higher energies.
  We then discuss how the differences in the SEDs may affect the overall
properties of surrounding nebulae in terms of temperature and ionization
structure. We find that the effect over the nebular temperature is not larger
than 300-350 K. Contrarily, the different SEDs produce significantly different
nebular ionization structures. This will lead to important consequences on the
establishment of the ionization correction factors that are used in the
abundance determination of HII regions, as well as in the characterization of
the ionizing stellar population from nebular line ratios.


title: Quantum Phase Transition in the Itinerant Antiferromagnet (V0.9Ti0.1)2O3

abstract:
  Quantum-critical behavior of the itinerant electron antiferromagnet
(V0.9Ti0.1)2O3 has been studied by single-crystal neutron scattering. By
directly observing antiferromagnetic spin fluctuations in the paramagnetic
phase, we have shown that the characteristic energy depends on temperature as
c_1 + c_2 T^{3/2}, where c_1 and c_2 are constants. This T^{3/2} dependence
demonstrates that the present strongly correlated d-electron antiferromagnet
clearly shows the criticality of the spin-density-wave quantum phase transition
in three space dimensions.


title:
Positive streamers in air and nitrogen of varying density: experiments
  on similarity laws

abstract:
  Positive streamers in ambient air at pressures from 0.013 to 1 bar are
investigated experimentally. The voltage applied to the anode needle ranges
from 5 to 45 kV, the discharge gap from 1 to 16 cm. Using a "slow" voltage rise
time of 100 to 180 ns, the streamers are intentionally kept thin. For each
pressure p, we find a minimal diameter d_{min}. To test whether streamers at
different pressures are similar, the minimal streamer diameter d_{min} is
multiplied by its pressure p; we find this product to be well approximated by
p*d_{min}=0.20 \pm 0.02 mm*bar over two decades of air pressure at room
temperature. The value also fits diameters of sprite discharges above
thunderclouds at an altitude of 80 km when extrapolated to room temperature (as
air density rather than pressure determines the physical behavior). The minimal
velocity of streamers in our measurements is approximately 0.1 mm/ns = 10^5
m/s. The same minimal velocity has been reported for tendrils in sprites. We
also investigate the size of the initial ionization cloud at the electrode tip
from which the streamers emerge, and the streamer length between branching
events. The same quantities are also measured in nitrogen with a purity of
approximately 99.9 %. We characterize the essential differences with streamers
in air and find a minimal diameter of p*d_{min}=0.12 \pm 0.02 mm*bar in our
nitrogen.


title: A Deep Survey of the Fornax dSph I: Star Formation History

abstract:
  Based on a deep imaging survey, we present the first homogeneous star
formation history (SFH) of the Fornax dwarf spheroidal (dSph) galaxy. We have
obtained two-filter photometry to a depth of B ~ 23 over the entire surface of
Fornax, the brightest dSph associated with the Milky Way, and derived its SFH
using a CMD-fitting technique. We show that Fornax has produced the most
complex star formation and chemical enrichment histories of all the Milky Way
dSphs. This system has supported multiple epochs of star formation. A
significant number of stars were formed in the early Universe, however the most
dominant population are the intermediate age stars. This includes a strong
burst of star formation approximately 3 to 4 Gyr ago. Significant population
gradients are also evident. Similar to other dSphs, we have found that recent
star formation was concentrated towards the centre of the system. Furthermore,
we show that the central region harboured a faster rate of chemical enrichment
than the outer parts of Fornax. At the centre, the ancient stars (age > 10 Gyr)
display a mean metallicity of [Fe/H] ~ -1.4, with evidence for three peaks in
the metallicity distribution. Overall, enrichment in Fornax has been highly
efficient: the most recent star formation burst has produced stars with close
to solar metallicity. Our results support a scenario in which Fornax
experienced an early phase of rapid chemical enrichment producing a wide range
of abundances. Star formation gradually decreased until ~4 Gyr ago, when Fornax
experienced a sudden burst of strong star formation activity accompanied by
substantial chemical enrichment. Weaker star forming events followed, and we
have found tentative evidence for stars with ages less than 100 Myr.


title: From the warm magnetized atomic medium to molecular clouds

abstract:
  {It has recently been proposed that giant molecular complexes form at the
sites where streams of diffuse warm atomic gas collide at transonic
velocities.} {We study the global statistics of molecular clouds formed by
large scale colliding flows of warm neutral atomic interstellar gas under ideal
MHD conditions. The flows deliver material as well as kinetic energy and
trigger thermal instability leading eventually to gravitational collapse.} {We
perform adaptive mesh refinement MHD simulations which, for the first time in
this context, treat self-consistently cooling and self-gravity.} {The clouds
formed in the simulations develop a highly inhomogeneous density and
temperature structure, with cold dense filaments and clumps condensing from
converging flows of warm atomic gas. In the clouds, the column density
probability density distribution (PDF) peaks at $\sim 2 \times 10^{21} \psc$
and decays rapidly at higher values; the magnetic intensity correlates weakly
with density from $n \sim 0.1$ to $10^4 \pcc$, and then varies roughly as
$n^{1/2}$ for higher densities.} {The global statistical properties of such
molecular clouds are reasonably consistent with observational determinations.
Our numerical simulations suggest that molecular clouds formed by the
moderately supersonic collision of warm atomic gas streams.}


title: High-sensitivity diamond magnetometer with nanoscale resolution

abstract:
  We present a novel approach to the detection of weak magnetic fields that
takes advantage of recently developed techniques for the coherent control of
solid-state electron spin quantum bits. Specifically, we investigate a magnetic
sensor based on Nitrogen-Vacancy centers in room-temperature diamond. We
discuss two important applications of this technique: a nanoscale magnetometer
that could potentially detect precession of single nuclear spins and an optical
magnetic field imager combining spatial resolution ranging from micrometers to
millimeters with a sensitivity approaching few femtotesla/Hz$^{1/2}$.


title: Topological expansion of the chain of matrices

abstract:
  We solve the loop equations to all orders in $1/N^2$, for the Chain of
Matrices matrix model (with possibly an external field coupled to the last
matrix of the chain). We show that the topological expansion of the free
energy, is, like for the 1 and 2-matrix model, given by the symplectic
invariants of the associated spectral curve. As a consequence, we find the
double scaling limit explicitly, and we discuss modular properties, large $N$
asymptotics. We also briefly discuss the limit of an infinite chain of matrices
(matrix quantum mechanics).


title:
Discovery of Fast-Moving X-Ray--Emitting Ejecta Knots in the Oxygen-Rich
  Supernova Remnant Puppis A

abstract:
  We report on the discovery of fast-moving X-ray--emitting ejecta knots in the
Galactic Oxygen-rich supernova remnant Puppis A from XMM-Newton observations.
We find an X-ray knotty feature positionally coincident with an O-rich
fast-moving optical filament with blue-shifted line emission located in the
northeast of Puppis A. We extract spectra from northern and southern regions of
the feature. Applying a one-component non-equilibrium ionization model for the
two spectra, we find high metal abundances relative to the solar values in both
spectra. This fact clearly shows that the feature originates from metal-rich
ejecta. In addition, we find that line emission in the two regions is
blue-shifted. The Doppler velocities derived in the two regions are different
with each other, suggesting that the knotty feature consists of two knots that
are close to each other along the line of sight. Since fast-moving O-rich
optical knots/filaments are believed to be recoiled metal-rich ejecta, expelled
to the opposite direction against the high-velocity central compact object, we
propose that the ejecta knots disclosed here are also part of the recoiled
material.


title: Isometric embeddings into the Minkowski space and new quasi-local mass

abstract:
  The definition of quasi-local mass for a bounded space-like region in
space-time is essential in several major unsettled problems in general
relativity. The quasi-local mass is expected to be a type of flux integral on
the boundary two-surface and should be independent of whichever space-like
region it bounds. An important idea which is related to the Hamiltonian
formulation of general relativity is to consider a reference surface in a flat
ambient space with the same first fundamental form and derive the quasi-local
mass from the difference of the extrinsic geometries. This approach has been
taken by Brown-York and Liu-Yau (see also related works) to define such notions
using the isometric embedding theorem into the Euclidean three-space. However,
there exist surfaces in the Minkowski space whose quasilocal mass is strictly
positive. It appears that the momentum information needs to be accounted for to
reconcile the difference. In order to fully capture this information, we use
isometric embeddings into the Minkowski space as references. In this article,
we first prove an existence and uniqueness theorem for such isometric
embeddings. We then solve the boundary value problem for Jang's equation as a
procedure to recognize such a surface in the Minkowski space. In doing so, we
discover new expression of quasi-local mass. The new mass is positive when the
ambient space-time satisfies the dominant energy condition and vanishes on
surfaces in the Minkowski space. It also has the nice asymptotic behavior at
spatial and null infinity. Some of these results were announced in [29].


title: The geometry of twisted conjugacy classes in wreath products

abstract:
  We give a geometric proof based on recent work of Eskin, Fisher and Whyte
that the lamplighter group $L_n$ has infinitely many twisted conjugacy classes
for any automorphism $\vp$ only when $n$ is divisible by 2 or 3, originally
proved by Gon\c{c}alves and Wong. We determine when the wreath product $G \wr
\Z$ has this same property for several classes of finite groups $G$, including
symmetric groups and some nilpotent groups.


title:
Transient Heavy Element Absorption Systems in Novae: Episodic Mass
  Ejection from the Secondary Star

abstract:
  A high-resolution spectroscopic survey of postoutburst novae reveals
short-lived heavy element absorption systems in a majority of novae near
maximum light, having expansion velocities of 400-1000 km/s and velocity
dispersions between 35-350 km/s. A majority of systems are accelerated
outwardly, and they all progressively weaken and disappear over timescales of
weeks. A few of the systems having narrow, deeper absorption reveal a rich
spectrum of singly ionized Sc, Ti, V, Cr, Fe, Sr, Y, Zr, and Ba lines. Analysis
of the richest such system, in Nova LMC 2005, shows the excitation temperature
to be 104 K and elements lighter than Fe to have abundance enhancements over
solar values by up to an order of magnitude. The gas causing the absorption
systems must be circumbinary and its origin is most likely mass ejection from
the secondary star. The absorbing gas pre-exists the outburst and may represent
episodic mass transfer events from the secondary star that initiate the nova
outburst(s). If SNe Ia originate in single degenerate binaries, such absorption
systems could be detectable before maximum light


title: Binary Morphisms to Ultimately Periodic Words

abstract:
  This paper classifies binary morphisms that map to ultimately periodic words.
In particular, if a morphism h maps an infinite non-ultimately periodic word to
an ultimately periodic word then it must be true that h(0) commutes with h(1).


title: Mining a medieval social network by kernel SOM and related methods

abstract:
  This paper briefly presents several ways to understand the organization of a
large social network (several hundreds of persons). We compare approaches
coming from data mining for clustering the vertices of a graph (spectral
clustering, self-organizing algorithms. . .) and provide methods for
representing the graph from these analysis. All these methods are illustrated
on a medieval social network and the way they can help to understand its
organization is underlined.


title: Seidel's Representation on the Hamiltonian Group of a Cartesian Product

abstract:
  Let $(M,\omega)$ be a closed symplectic manifold and $\textup{Ham}(M,\omega)$
the group of Hamiltonian diffeomorphisms of $(M,\omega)$. Then the Seidel
homomorphism is a map from the fundamental group of $\textup{Ham}(M,\omega)$ to
the quantum homology ring $QH_*(M;\Lambda)$. Using this homomorphism we give a
sufficient condition for when a nontrivial loop $\psi$ in
$\textup{Ham}(M,\omega)$ determines a nontrivial loop $\psi\times\textup{id}_N$
in $\textup{Ham}(M\times N,\omega\oplus\eta)$, where $(N,\eta)$ is a closed
symplectic manifold such that $\pi_2(N)=0$.


title:
Positive and negative streamers in ambient air: measuring diameter,
  velocity and dissipated energy

abstract:
  Positive and negative streamers are studied in ambient air at 1 bar; they
emerge from a needle electrode placed 40 mm above a planar electrode. The
amplitudes of the applied voltage pulses range from 5 to 96 kV; most pulses
have rise times of 30 ns or shorter. Diameters, velocities and energies of the
streamers are measured. Two regimes are identified; a low voltage regime where
only positive streamers appear and a high voltage regime where both positive
and negative streamers exist. Below 5 kV, no streamers emerge. In the range
from 5 to 40 kV, positive streamers form, while the negative discharges only
form a glowing cloud at the electrode tip, but no streamers. For 5 to 20 kV,
diameters and velocities of the positive streamers have the minimal values of
d=0.2 mm and v \approx 10^5 m/s. For 20 to 40 kV, their diameters increase by a
factor 6 while the voltage increases only by a factor 2. Above the transition
value of 40 kV, streamers of both polarities form; they strongly resemble each
other, though the positive ones propagate further; their diameters continue to
increase with applied voltage. For 96 kV, positive streamers attain diameters
of 3 mm and velocities of 4*10^6 m/s, negative streamers are about 20 % slower
and thinner. An empirical fit formula for the relation between velocity v and
diameter d is v=0.5 d^2/(mm ns) for both polarities. Streamers of both
polarities dissipate energies of the order of several mJ per streamer while
crossing the gap.


title: Subcritical dynamos in shear flows

abstract:
  Identifying generic physical mechanisms responsible for the generation of
magnetic fields and turbulence in differentially rotating flows is fundamental
to understand the dynamics of astrophysical objects such as accretion disks and
stars. In this paper, we discuss the concept of subcritical dynamo action and
its hydrodynamic analogue exemplified by the process of nonlinear transition to
turbulence in non-rotating wall-bounded shear flows. To illustrate this idea,
we describe some recent results on nonlinear hydrodynamic transition to
turbulence and nonlinear dynamo action in rotating shear flows pertaining to
the problem of turbulent angular momentum transport in accretion disks. We
argue that this concept is very generic and should be applicable to many
astrophysical problems involving a shear flow and non-axisymmetric
instabilities of shear-induced axisymmetric toroidal velocity or magnetic
fields, such as Kelvin-Helmholtz, magnetorotational, Tayler or global
magnetoshear instabilities. In the light of several recent numerical results,
we finally suggest that, similarly to a standard linear instability,
subcritical MHD dynamo processes in high-Reynolds number shear flows could act
as a large-scale driving mechanism of turbulent flows that would in turn
generate an independent small-scale dynamo.


title: Massive stars in the nuclei and arms of spirals

abstract:
  Many of the properties of massive stars in external galaxies, such as
chemical compositions, mass functions, and ionizing fluxes, can be derived from
the study of the associated clouds of ionized gas. Moreover, the signatures of
Wolf-Rayet stars are often detected in the spectra of extragalactic H II
regions. This paper reviews some aspects of the recent work on the massive star
content of nearby spiral galaxies, as inferred from the analysis of giant H II
regions. Particular attention is given to regions of high metallicity,
including nuclear hot spots, and to the chemical abundance comparison between
supergiant stars and ionized gas.


title:
Supersymmetric Extensions and Dark Matter in Models of Warped Higgsless
  EWSB

abstract:
  We introduce a minimal supersymmetric extension of a higgsless model for
electroweak symmetry breaking in a warped extra dimension. In contrast to the
non supersymmetric version, our model naturally contains a candidate for cold
dark matter. No KK-parity is required, because its stability is guaranteed by
an R-parity. We discuss the regions in parameter that are compatible with the
observed dark matter content of our universe and are allowed by electroweak
precision measurements as well as direct searches.


title:
Two-Dimensional Hydrodynamic Models of Super Star Clusters with a
  Positive Star Formation Feedback

abstract:
  Using the hydrodynamic code ZEUS, we perform 2D simulations to determine the
fate of the gas ejected by massive stars within super star clusters. It turns
out that the outcome depends mainly on the mass and radius of the cluster. In
the case of less massive clusters, a hot high velocity ($\sim 1000$ km
s$^{-1}$) stationary wind develops and the metals injected by supernovae are
dispersed to large distances from the cluster. On the other hand, the density
of the thermalized ejecta within massive and compact clusters is sufficiently
large as to immediately provoke the onset of thermal instabilities. These
deplete, particularly in the central densest regions, the pressure and the
pressure gradient required to establish a stationary wind, and instead the
thermally unstable parcels of gas are rapidly compressed, by a plethora of
re-pressurizing shocks, into compact high density condensations. Most of these
are unable to leave the cluster volume and thus accumulate to eventually feed
further generations of star formation.
  The simulations cover an important fraction of the parameter-space, which
allows us to estimate the fraction of the reinserted gas which accumulates
within the cluster and the fraction that leaves the cluster as a function of
the cluster mechanical luminosity, the cluster size and heating efficiency.


title:
A spanning tree model for the Heegaard Floer homology of a branched
  double-cover

abstract:
  Given a diagram of a link K in S^3, we write down a Heegaard diagram for the
branched-double cover Sigma(K). The generators of the associated Heegaard Floer
chain complex correspond to Kauffman states of the link diagram. Using this
model we make some computations of the homology \hat{HF}(Sigma(K)) as a graded
group. We also conjecture the existence of a delta-grading on
\hat{HF}(Sigma(K)) analogous to the delta-grading on knot Floer and Khovanov
homology.


title: A Gribov equation for the photon Green's function

abstract:
  We present a derivation of the Gribov equation for the gluon/photon Green's
function D(q). Our derivation is based on the second derivative of the
gauge-invariant quantity Tr ln D(q), which we interpret as the gauge-boson
`self-loop'. By considering the higher-order corrections to this quantity, we
are able to obtain a Gribov equation which sums the logarithmically enhanced
corrections. By solving this equation, we obtain the non-perturbative running
coupling in both QCD and QED. In the case of QCD, alpha_S has a singularity in
the space-like region corresponding to super-criticality, which is argued to be
resolved in Gribov's light-quark confinement scenario. For the QED coupling in
the UV limit, we obtain a \propto Q^2 behaviour for space-like Q^2=-q^2. This
implies the decoupling of the photon and an NJLVL-type effective theory in the
UV limit.


title: Combining the Hybrid Functional Method with Dynamical Mean-Field Theory

abstract:
  We present a new method to compute the electronic structure of correlated
materials combining the hybrid functional method with the dynamical mean-field
theory. As a test example of the method we study cerium sesquioxide, a strongly
correlated Mott-band insulator. The hybrid functional part improves the
magnitude of the pd-band gap which is underestimated in the standard
approximations to density functional theory while the dynamical mean-field
theory part splits the 4f-electron spectra into a lower and an upper Hubbard
band.


title:
Implications of CP-violating transitions in hot quark matter on heavy
  ion collisions

abstract:
  Quantum Chromodynamics (QCD) predicts that topological charge changing
transitions will take place in hot quark matter. Such transitions induce P- and
CP-violating effects. We will show that in the presence of a magnetic field
these transitions can separate quarks according to their electric charge along
the direction of the magnetic field. This is the so-called Chiral Magnetic
Effect. We will argue that it might be possible to observe the Chiral Magnetic
Effect in heavy ion collisions.


title: Almost-natural proofs

abstract:
  Razborov and Rudich have shown that so-called "natural proofs" are not useful
for separating P from NP unless hard pseudorandom number generators do not
exist. This famous result is widely regarded as a serious barrier to proving
strong lower bounds in circuit complexity theory.
  By definition, a natural combinatorial property satisfies two conditions,
constructivity and largeness. Our main result is that if the largeness
condition is weakened slightly, then not only does the Razborov-Rudich proof
break down, but such "almost-natural" (and useful) properties provably exist.
Specifically, under the same pseudorandomness assumption that Razborov and
Rudich make, a simple, explicit property that we call "discrimination" suffices
to separate P/poly from NP; discrimination is nearly linear-time computable and
almost large, having density 2^{-q(n)} where q is a quasi-polynomial function.
For those who hope to separate P from NP using random function properties in
some sense, discrimination is interesting, because it is constructive, yet may
be thought of as a minor alteration of a property of a random function.
  The proof relies heavily on the self-defeating character of natural proofs.
Our proof technique also yields an unconditional result, namely that there
exist almost-large and useful properties that are constructive, if we are
allowed to call non-uniform low-complexity classes "constructive." We note,
though, that this unconditional result can also be proved by a more
conventional counting argument.
  Finally, we give an alternative proof, communicated to us by Salil Vadhan at
FOCS 2008, of one of our theorems, and we make some speculative remarks on the
future prospects for proving strong circuit lower bounds.


title: A language for mathematical knowledge management

abstract:
  We argue that the language of Zermelo Fraenkel set theory with definitions
and partial functions provides the most promising bedrock semantics for
communicating and sharing mathematical knowledge. We then describe a syntactic
sugaring of that language that provides a way of writing remarkably readable
assertions without straying far from the set-theoretic semantics. We illustrate
with some examples of formalized textbook definitions from elementary set
theory and point-set topology. We also present statistics concerning the
complexity of these definitions, under various complexity measures.