title: On the origin of spectral states in accreting black holes

abstract:
  The origin of dramatically different electron distributions responsible for
Comptonization in black hole X-ray binaries (BHBs) in their various states is
discussed. We solve the coupled kinetic equations for photons and electrons
without approximations on the relevant cross-sections accounting for Compton
scattering, synchrotron radiation, and Coulomb collisions. In the absence of
external soft photons, the electrons are efficiently thermalized by synchrotron
self-absorption and Coulomb scattering even for pure nonthermal electron
injection. The resulting quasi-thermal synchrotron self-Compton spectra have
very stable slopes and electron temperatures similar to the hard states of
BHBs. The hard spectral slopes observed in the X-rays, the cutoff at 100 keV,
and the MeV tail together require low magnetic fields ruling out the magnetic
dissipation mechanism. The motion of the accretion disk toward the black hole
results in larger Compton cooling and lower equilibrium electron temperature.
Our self-consistent simulations show that in this case both electron and photon
distributions attain a power-law-dominated shape similar to what is observed in
the soft state. The electron distribution in the Cyg X-1 soft state might
require a strong magnetic field, being consistent with the magnetically
dominated corona.


title:
A spectral synthesis method to suppress aliasing and calibrate for delay
  errors in Fourier transform correlators

abstract:
  Context: Fourier transform (or lag) correlators in radio interferometers can
serve as an efficient means of synthesising spectral channels. However aliasing
corrupts the edge channels so they usually have to be excluded from the data
set. In systems with around 10 channels, the loss in sensitivity can be
significant. In addition, the low level of residual aliasing in the remaining
channels may cause systematic errors. Moreover, delay errors have been widely
reported in implementations of broadband analogue correlators and simulations
have shown that delay errors exasperate the effects of aliasing. Aims: We
describe a software-based approach that suppresses aliasing by oversampling the
cross-correlation function. This method can be applied to interferometers with
individually-tracking antennas equipped with a discrete path compensator
system. It is based on the well-known property of interferometers where the
drift scan response is the Fourier transform of the source's band-limited
spectrum. Methods: In this paper, we simulate a single baseline interferometer,
both for a real and a complex correlator. Fringe-rotation usually compensates
for the phase of the fringes to bring the phase centre in line with the
tracking centre. Instead, a modified fringe-rotation is applied. This enables
an oversampled cross-correlation function to be reconstructed by gathering
successive time samples. Results: Simulations show that the oversampling method
can synthesise the cross-power spectrum while avoiding aliasing and works
robustly in the presence of noise. An important side benefit is that it
naturally accounts for delay errors in the correlator and the resulting
spectral channels are regularly gridded.


title:
Resistivity peak values at transition between fractional quantum Hall
  states

abstract:
  Experimental data available in the literature for peak values of the diagonal
resistivity in the transitions between fractional quantum Hall states are
compared with the theoretical predictions. It is found that the majority of the
peak values are close to the theoretical values for two-dimensional systems
with moderate mobilities.


title: The isoperimetric problem for Holderian curves

abstract:
  We prove a necessary stationary condition for non-differentiable
isoperimetric variational problems with scale derivatives, defined on the class
of H\"{o}lder continuous functions.


title: Inertial frame rotation induced by rotating gravitational waves

abstract:
  We calculate the rotation of the inertial frames within an almost flat
cylindrical region surrounded by a pulse of non-axially-symmetric gravitational
waves that rotate about the axis of our cylindrical polar coordinates. Our
spacetime has only one Killing vector. It is along the z-axis and hypersurface
orthogonal. We solve the Einstein equations to first order in the wave
amplitude and superpose such linearized solutions to form a wave pulse. We then
solve the relevant Einstein equation to second order in the amplitude to find
the rotation of inertial frames produced by the pulse. The rotation is without
time delay. The influence of gravitational wave angular momentum on the
inertial frame demonstrates that Mach's principle can not be expressed in terms
of the influence of the stress-energy-momentum tensor alone but must involve
also influences of gravitational wave energy and angular momentum.


title:
Supernemo: A Next Generation Project to Search for Neutrinoless Double
  Beta Decay

abstract:
  The SuperNEMO project aims to search for neutrinoless double beta decay
($0\nu\beta\beta$) up to a sensitivity of 10$^{26}$ years for the
$0\nu\beta\beta$ half-life (down to 50 meV in the effective Majorana neutrino
mass), using $\sim$100 kg of source and a `tracko-calo' detector. The current
status of the 2007--2009 R&D programme is presented here, focusing on the most
challenging aspects: calorimetry, production of sources, low radioactivity
measurements, and tracker.


title:
Superpotentials from variational derivatives rather than Lagrangians in
  relativistic theories of gravity

abstract:
  The prescription of Silva to derive superpotential equations from variational
derivatives rather than from Lagrangian densities is applied to theories of
gravity derived from Lovelock Lagrangians in the Palatini representation.
Spacetimes are without torsion and isolated sources of gravity are minimally
coupled. On a closed boundary of spacetime, the metric is given and the
connection coefficients are those of Christoffel. We derive equations for the
superpotentials in these conditions. The equations are easily integrated and we
give the general expression for all superpotentials associated with Lovelock
Lagrangians. We find, in particular, that in Einstein's theory, in any number
of dimensions, the superpotential, valid at spatial and at null infinity, is
that of Katz, Bicak and Lynden-Bell, the KBL superpotential. We also give
explicitly the superpotential for Gauss-Bonnet theories of gravity. Finally, we
find a simple expression for the superpotential of Einstein-Gauss-Bonnet
theories with an anti-de Sitter background: it is minus the KBL superpotential,
confirming, as it should, the calculation of the total mass-energy of spacetime
at spatial infinity by Deser and Tekin.


title: Implications for CP asymmetries of improved data on $B \to K^0 \pi^0$

abstract:
  The decay $B^0 \to K^0 \pi^0$, dominated by a $b \to s$ penguin amplitude,
holds the potential for exhibiting new physics in this amplitude. In the pure
QCD penguin limit one expects $\ckp = 0$ and $\skp = \sin 2 \beta$ for the
coefficients of $\cos \Delta m t$ and $\sin \Delta m t$ in the time-dependent
CP asymmetry. Small non-penguin contributions lead to corrections to these
expressions which are calculated in terms of isospin-related $B\to K\pi$ rates
and asymmetries, using information about strong phases from experiment. We
study the prospects for incisive tests of the Standard Model through
examination of these corrections. We update a prediction $\ckp=0.15\pm 0.04$,
pointing out the sensitivity of a prediction $\skp\approx 1$ to the measured
branching ratio for $B^0\to K^0\pi^0$ and to other observables.


title: A New Car-Following Model Inspired by Galton Board

abstract:
  Different from previous models based on scatter theory and random matrix
theory, a new interpretation of the observed log-normal type time-headway
distribution of vehicles is presented in this paper. Inspired by the well known
Galton Board, this model views driver's velocity adjusting process similar to
the dynamics of a particle falling down a board and being deviated at decision
points. A new car-following model based on this idea is proposed to reproduce
the observed traffic flow phenomena. The agreement between the empirical
observations and the simulation results suggests the soundness of this new
approach.


title: Angular dependence of the radiation power of a Josephson STAR-emitter

abstract:
  We calculate the angular dependence of the power of stimulated terahertz
amplified radiation (STAR) emitted from a $dc$ voltage applied across a stack
of intrinsic Josephson junctions. During coherent emission, we assume a
spatially uniform $ac$ Josephson current density in the stack acts as a surface
electric current density antenna source, and the cavity features of the stack
are contained in a magnetic surface current density source. A superconducting
substrate acts as a perfect magnetic conductor with $H_{||,ac}=0$ on its
surface. The combined results agree very well with recent experimental
observations. Existing Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ crystals atop perfect
electric conductors could have Josephson STAR-emitter power in excess of 5 mW,
acceptable for many device applications.


title:
Reply to the Comment on "Spin and orbital angular momentum in gauge
  theories: Nucleon spin structure and multipole radiation revisited" [PRL
  100:232002 (2008)]

abstract:
  This is a Reply to the Comment [arXiv:0807.0699] on our paper [PRL 100:232002
(2008)].


title:
Brownian motion of a charged test particle driven by vacuum fluctuations
  near a dielectric half-space

abstract:
  We study the Brownian motion of a charged test particle driven by quantum
electromagnetic fluctuations in the vacuum region near a non-dispersive and
non-absorbing dielectric half-space and calculate the mean squared fluctuations
in the velocity of the test particle. Our results show that a nonzero
susceptibility of the dielectrics has its imprints on the velocity dispersions
of the test particles. The most noteworthy feature in sharp contrast to the
case of an idealized perfectly conducting interface is that the velocity
dispersions in the parallel directions are no longer negative and does not die
off in time, suggesting that the potentially problematic negativeness of the
dispersions in those directions in the case of perfect conductors is just a
result of our idealization and does not occur for real material boundaries.


title:
Effects of environmental and exciton screening in single-walled carbon
  nanotubes

abstract:
  The ground-state exciton binding energy for single-walled carbon nanotubes
(SWCNTs) in vacuum calculated ignoring the screening of Coulomb interaction
appears to be much greater than the corresponding band gap. The most essential
contributions to the screening of electron-hole (e-h) interaction potential in
semiconducting SWCNTs, which return the ground-state exciton binding energy
into the energy gap, are considered. Our estimates on the screening effects and
exciton binding energies are in satisfactory agreement with the corresponding
experimental data for concrete nanotubes.


title: Training-induced criticality in martensites

abstract:
  We propose an explanation for the self-organization towards criticality
observed in martensites during the cyclic process known as `training'. The
scale-free behavior originates from the interplay between the reversible phase
transformation and the concurrent activity of lattice defects. The basis of the
model is a continuous dynamical system on a rugged energy landscape, which in
the quasi-static limit reduces to a sandpile automaton. We reproduce all the
principal observations in thermally driven martensites, including power-law
statistics, hysteresis shakedown, asymmetric signal shapes, and correlated
disorder.


title:
Study of spin fluctuations in Ni3Al using point contact Andreev
  reflection spectroscopy

abstract:
  We report point contact Andreev reflection (PCAR) spectroscopy studies on
Ni3Al with composition range (24, 26 and 27 at. % of Al in the solid solution)
spanning the ferromagnetic to paramagnetic phase boundary. PCAR studies
performed using Nb tip as counter electrode reveal that the superconducting
quasiparticle lifetime (\tao) and superconducting energy gap (\delta) decreases
with increasing spin fluctuation in the normal metal electrode. Our study
reveals that PCAR could be a useful probe to study spin fluctuations in systems
which are on the verge of a magnetic instability.


title:
L'Algebre Tropicale Comme Algebre De la Caracteristique 1 : Algebre
  Lineaire Sur Les Semi-Corps Idempotents

abstract:
  We define a formal framework for the study of algebras of type Max-plus,
Min-Plus, tropical algebras, and more generally algebras over a commutative
idempotent semi-field. This work is motivated by the increasingly diversified
use of these algebras which occur also in control theory, automata theory as
well as in algebraic geometry, and in more specific ways in other parts of
mathematics such as the theory of monoids.
  In this first article, we expecially re-examine linear algebra over
idempotent semi-fields: the most delicate, but undoubtedly the most interesting
point is the notion of a singular point seen as a generalization of the notion
of zero. We thus rediscover many notions of regularity already introduced for
matrices, and this permits us to define further notions, new in this context,
such as that of the kernel of a linear form, and to apply duality to obtain a
good notion of tropical dimension of a submodule.


title: Model of Genetic Variation in Human Social Networks

abstract:
  Social networks exhibit strikingly systematic patterns across a wide range of
human contexts. While genetic variation accounts for a significant portion of
the variation in many complex social behaviors, the heritability of egocentric
social network attributes is unknown. Here we show that three of these
attributes (in-degree, transitivity, and centrality) are heritable. We then
develop a "mirror network" method to test extant network models and show that
none accounts for observed genetic variation in human social networks. We
propose an alternative "Attract and Introduce" model with two simple forms of
heterogeneity that generates significant heritability as well as other
important network features. We show that the model is well suited to real
social networks in humans. These results suggest that natural selection may
have played a role in the evolution of social networks. They also suggest that
modeling intrinsic variation in network attributes may be important for
understanding the way genes affect human behaviors and the way these behaviors
spread from person to person.


title: A comment on the LLA method, the kT jet algorithm and the BFKL theory

abstract:
  The leading logarithmic approximation method fails to yield the correct
asymptotic behavior in some realistic situations: inclusion of the beta-terms
to which the LLA method is insensitive may change a power growth to merely
logarithmic. The results of [hep-ph/0101058] indicate that the problem of
large-s behavior of total cross sections belongs to this class. Similarly, a
reference to the LLA method cannot be sufficient to justify constructions such
as the kT jet algorithm.


title: Carbon nanotube as a nanoscale Cherenkov--type light emitter - nanoFEL

abstract:
  A mechanism of stimulated emission of electromagnetic radiation by an
electron beam in carbon nanotubes is theoretically considered. Three basic
properties of carbon nanotubes, a strong slowing down of surface
electromagnetic waves, ballisticity of the electron motion over typical
nanotube length, and extremely high electron current density reachable in
nanotubes, allow proposing them as candidates for the development of nano-scale
Chernekov-type emitters, analogous to traveling wave tube and free electron
laser. Dispersion equations of the electron beam instability and the threshold
conditions of the stimulated emission have been derived and analyzed,
demonstrating realizability of the nanotube-based nanoFEL at realistic
parameters of nanotubes and electronic beams.


title: Ultrafast pump-probe dynamics in ZnSe-based semiconductor quantum-wells

abstract:
  Pump-probe experiments are used as a controllable way to investigate the
properties of photoexcited semiconductors, in particular, the absorption
saturation. We present an experiment-theory comparison for ZnSe quantum wells,
investigating the energy renormalization and bleaching of the excitonic
resonances. Experiments were performed with spin-selective excitation and
above-bandgap pumping. The model, based on the semiconductor Bloch equations in
the screened Hartree-Fock approximation, takes various scattering processes
into account phenomenologically. Comparing numerical results with available
experimental data, we explain the experimental results and find that the
electron spin-flip occurs on a time scale of 30 ps.


title: Algorithms for Representation Theory of Real Reductive Groups

abstract:
  We give an algorithm for computing the irreducible admissible representations
of a real reductive group with regular integral infinitesimal character. This
algorithm has been implemented on a computer, as part of the Atlas of Lie
Groups and Representations project.


title:
Energy-Efficient Resource Allocation in Multiuser MIMO Systems: A
  Game-Theoretic Framework

abstract:
  This paper focuses on the cross-layer issue of resource allocation for energy
efficiency in the uplink of a multiuser MIMO wireless communication system.
Assuming that all of the transmitters and the uplink receiver are equipped with
multiple antennas, the situation considered is that in which each terminal is
allowed to vary its transmit power, beamforming vector, and uplink receiver in
order to maximize its own utility, which is defined as the ratio of data
throughput to transmit power; the case in which non-linear interference
cancellation is used at the receiver is also investigated. Applying a
game-theoretic formulation, several non-cooperative games for utility
maximization are thus formulated, and their performance is compared in terms of
achieved average utility, achieved average SINR and average transmit power at
the Nash equilibrium. Numerical results show that the use of the proposed
cross-layer resource allocation policies brings remarkable advantages to the
network performance.


title:
Guide to the Atlas Software: Computational Representation Theory of Real
  Reductive Groups

abstract:
  This is an introduction to the Atlas of Lie Groups and Representations
software, for computing representation and structure theory of real reductive
groups. The user is led through the basic commands of the software, via
numerous examples. See Algorithms for Representation Theory of Real Reductive
Groups, arXiv number 0807.3093, for a more complete mathematical description of
the algorithm


title:
Stochastic Maximum Principle for a PDEs with noise and control on the
  boundary

abstract:
  In this paper we prove necessary conditions for optimality of a stochastic
control problem for a class of stochastic partial differential equations that
is controlled through the boundary. This kind of problems can be interpreted as
a stochastic control problem for an evolution system in an Hilbert space. The
regularity of the solution of the adjoint equation, that is a backward
stochastic equation in infinite dimension, plays a crucial role in the
formulation of the maximum principle.


title:
Energy-Efficient Power Control in Multipath CDMA Channels via Large
  System Analysis

abstract:
  This paper is focused on the design and analysis of power control procedures
for the uplink of multipath code-division-multiple-access (CDMA) channels based
on the large system analysis (LSA). Using the tools of LSA, a new decentralized
power control algorithm aimed at energy efficiency maximization and requiring
very little prior information on the interference background is proposed;
moreover, it is also shown that LSA can be used to predict with good accuracy
the performance and operational conditions of a large network operating at the
equilibrium over a multipath channel, i.e. the power,
signal-to-interference-plus-noise ratio (SINR) and utility profiles across
users, wherein the utility is defined as the number of bits reliably delivered
to the receiver for each energy-unit used for transmission. Additionally, an
LSA-based performance comparison among linear receivers is carried out in terms
of achieved energy efficiency at the equilibrium. Finally, the problem of the
choice of the utility-maximizing training length is also considered. Numerical
results show a very satisfactory agreement of the theoretical analysis with
simulation results obtained with reference to systems with finite (and not so
large) numbers of users.


title:
Effect of doping on irreversible Campbell length in MgB$_2$ single
  crystals

abstract:
  We have measured small-amplitude rf penetration depth $\lambda(H,T)$ in pure
and C, Li and (Li+C) doped single crystals of MgB$_2$. The effect of doping on
the critical temperature T$_c$ and on the upper critical field H$_{c2}$ was
found to be in good agreement with previous results. We report the presence of
clear signatures of irreversibility in $\lambda(H,T)$, associated with the peak
effect. Carbon doping enhances the signature and shifts its position on the H-T
phase diagram to higher temperatures. Contrary to this, Li substitution has the
effect of suppressing the peak effect to lower temperatures. Analysis of both
zero field (ZFC) and field cooled (FC) measurements suggests that the
hysteresis associated with the peak effect is due to macroscopic screening
supercurrents, $j$, generated during the magnetic field ramp.


title: The Spectra of Supersymmetric States in String Theory

abstract:
  In this thesis we study the spectra of supersymmetric states in string theory
compactifications with eight and sixteen supercharges, with special focus
placed on the quantum states of black holes and the phenomenon of wall-crossing
in these theories. A self-contained introduction to the relevant background
material is included.


title: Influence of geography on language competition

abstract:
  Competition between languages or cultural traits diffusing in the same
geographical area is studied combining the language competition model of Abrams
and Strogatz and a human dispersal model on an inhomogeneous substrate. Also,
the effect of population growth is discussed. It is shown through numerical
experiments that the final configuration of the surviving language can be
strongly affected by geographical and historical factors. These factors are not
related to the dynamics of culture transmission, but rather to initial
population distributions as well as geographical boundaries and
inhomogeneities, which modulate the diffusion process.


title:
Universal analytic properties of noise. Introducing the J-Matrix
  formalism

abstract:
  We propose a new method in the spectral analysis of noisy time-series data
for damped oscillators. From the Jacobi three terms recursive relation for the
denominators of the Pad\'e Approximations built on the well-known Z-transform
of an infinite time-series, we build an Hilbert space operator, a J-Operator,
where each bound state (inside the unit circle in the complex plane) is simply
associated to one damped oscillator while the continuous spectrum of the
J-Operator, which lies on the unit circle itself, is shown to represent the
noise. Signal and noise are thus clearly separated in the complex plane. For a
finite time series of length 2N, the J-operator is replaced by a finite order
J-Matrix J_N, having N eigenvalues which are time reversal covariant. Different
classes of input noise, such as blank (white and uniform), Gaussian and pink,
are discussed in detail, the J-Matrix formalism allowing us to efficiently
calculate hundreds of poles of the Z-transform. Evidence of a universal
behaviour in the final statistical distribution of the associated poles and
zeros of the Z-transform is shown. In particular the poles and zeros tend, when
the length of the time series goes to infinity, to a uniform angular
distribution on the unit circle. Therefore at finite order, the roots of unity
in the complex plane appear to be noise attractors. We show that the
Z-transform presents the exceptional feature of allowing lossless undersampling
and how to make use of this property. A few basic examples are given to suggest
the power of the proposed method.


title:
The continuity of the inversion and the structure of maximal subgroups
  in countably compact topological semigroups

abstract:
  In this paper we search for conditions on a countably compact
(pseudo-compact) topological semigroup under which: (i) each maximal subgroup
$H(e)$ in $S$ is a (closed) topological subgroup in $S$; (ii) the Clifford part
$H(S)$(i.e. the union of all maximal subgroups) of the semigroup $S$ is a
closed subset in $S$; (iii) the inversion $\operatorname{inv}\colon H(S)\to
H(S)$ is continuous; and (iv) the projection $\pi\colon H(S)\to E(S)$,
$\pi\colon x\longmapsto xx^{-1}$, onto the subset of idempotents $E(S)$ of $S$,
is continuous.


title: Measurement of Time-Dependent CP Asymmetry in B0 --> KS pi0 gamma Decays

abstract:
  We measure the time-dependent CP asymmetry in B0 --> K_S0 pi0 gamma decays
for two regions of K_S0-pi0 invariant mass, m(K_S0 pi0), using the final BABAR
data set of 467 x 10^6 BBbar pairs collected at the PEP-II e+e- collider at
SLAC. We find 339 +/- 24 B0 --> K*0 gamma candidates and measure S_{K* gamma} =
-0.03 +/- 0.29 +/- 0.03 and C_{K* gamma} = -0.14 +/- 0.16 +/- 0.03. In the
range 1.1 < m(K_S0 pi0) < 1.8 GeV/c^2 we find 133 +/- 20 B0 --> K_S0 pi0 gamma
candidates and measure S_{K_S0 pi0 gamma} = -0.78 +/- 0.59 +/- 0.09 and C_{K_S0
pi0 gamma} = -0.36 +/- 0.33 +/- 0.04. The uncertainties are statistical and
systematic, respectively.


title: On the splitting problem for selections

abstract:
  We investigate when does the Repov\v{s}-Semenov Splitting problem for
selections have an affirmative solution for continuous set-valued mappings in
finite-dimensional Banach spaces. We prove that this happens when images of
set-valued mappings or even their graphs are P-sets (in the sense of Balashov)
or strictly convex sets. We also consider an example which shows that there is
no affirmative solution of this problem even in the simplest case in $\R^{3}$.
We also obtain affirmative solution of the Approximate splitting problem for
Lipschitz continuous selections in the Hilbert space.


title: Broue's Abelian Defect Group Conjecture for the Tits Group

abstract:
  In this paper we prove that Broue's abelian defect group conjecture holds for
the Tits group $^2F_4(2)'$. Also we prove that under certain conditions we are
able to lift derived equivalences and use this to prove Broue's conjecture for
the group $^2F_4(2)$.


title: On the Inviscid Burgers Equation and the Axiom of Choice

abstract: The article considers the Choice Axiom.


title:
Quasiparticle spin from adiabatic transport in quantum Hall trial
  wavefunctions

abstract:
  Quasiparticle spin (in the spacetime sense) couples to curvature of space.
Here this fact is used to calculate the spin of quasiholes in trial quantum
Hall states by adiabatically dragging them around on a sphere, for trial states
given by conformal blocks in some conformal field theory. The spin is found to
agree with the conformal weight of the corresponding field. The result
completes a recent argument that constructions using blocks from non-unitary
theories that contain negative quantum dimensions produce contradictions that
prevent them from describing topological (gapped) phases of matter.


title: Mean field limit for bosons and propagation of Wigner measures

abstract:
  We consider the N-body Schr\"{o}dinger dynamics of bosons in the mean field
limit with a bounded pair-interaction potential. According to the previous work
\cite{AmNi}, the mean field limit is translated into a semiclassical problem
with a small parameter $\epsilon\to 0$, after introducing an
$\epsilon$-dependent bosonic quantization. The limit is expressed as a
push-forward by a nonlinear flow (e.g. Hartree) of the associated Wigner
measures. These object and their basic properties were introduced in
\cite{AmNi} in the infinite dimensional setting. The additional result
presented here states that the transport by the nonlinear flow holds for rather
general class of quantum states in their mean field limit.


title:
Relative critical exponents, non-vanishing and metrics with minimal
  singularities

abstract:
  In this article we prove a non-vanishing statement, as well as several
properties of metrics with minimal singularities of adjoint bundles. Our
arguments involve many ideas from Y.-T. Siu's analytic proof of the finite
generation of the canonical ring. An important technical tool is the notion of
relative critical exponent of two closed positive currents with respect to a
measure.


title:
Ramsey-like measurement of the decoherence rate between Zeeman
  sub-levels

abstract:
  Two-photon processes that involve different sub-levels of the ground state of
an atom, are highly sensitive to depopulation and decoherence within the ground
state. For example, the spectral width of electromagnetically induced
transparency resonances in $\Lambda-$type system, are strongly affected by the
ground state depopulation and decoherence rates. We present a direct
measurement of decay rates between hyperfine and Zeeman sub-levels in the
ground state of $^{87}$Rb vapor. Similar to the relaxation-in-the-dark
technique, pumping lasers are used to pre-align the atomic vapor in a well
defined quantum state. The free propagation of the atomic state is monitored
using a Ramsey-like method. Coherence times in the range 1-10 ms were measured
for room temperature atomic vapor. In the range of the experimental parameters
used in this study, the dominant process inducing Zeeman decoherence is the
spin-exchange collisions between rubidium atoms.


title:
Simplified contact pseudopotential for anisotropic interactions of
  polarized particles under harmonic confinement

abstract:
  Motivated by the recent progress in cooling and trapping polar molecules, we
present a simplified version of the rigorous contact pseudopotential for
anisotropically-interacting polarized particles [A. Derevianko, Phys. Rev. A
67, 033607 (2003); Phys. Rev. A 72, 039901(E) (2005)]. The simplifications are
carried out for a practically important case of harmonically confined particles
described by sufficiently smooth wavefunctions. The resulting contact
pseudo-potential depends on the K-matrix of the underlying scattering process
and is represented as a sum over pairs of partial waves coupled by the
collision. The contribution of each pair of the coupled waves (l and l')
involves a tensor product of derivatives of orders l and l'. The asymmetry in
the derivatives reflects the anisotropy of the original interaction potential:
there is a preferential appearance of the derivatives along the polarizing
field.


title:
Functional inequalities for heavy tails distributions and application to
  isoperimetry

abstract:
  This paper is devoted to the study of probability measures with heavy tails.
Using the Lyapunov function approach we prove that such measures satisfy
different kind of functional inequalities such as weak Poincar\'e and weak
Cheeger, weighted Poincar\'e and weighted Cheeger inequalities and their dual
forms. Proofs are short and we cover very large situations. For product
measures on $\R^n$ we obtain the optimal dimension dependence using the mass
transportation method. Then we derive (optimal) isoperimetric inequalities.
Finally we deal with spherically symmetric measures. We recover and improve
many previous results.


title:
A note on state space representations of locally stationary wavelet time
  series

abstract:
  In this note we show that the locally stationary wavelet process can be
decomposed into a sum of signals, each of which following a moving average
process with time-varying parameters. We then show that such moving average
processes are equivalent to state space models with stochastic design
components. Using a simple simulation step, we propose a heuristic method of
estimating the above state space models and then we apply the methodology to
foreign exchange rates data.


title:
Steep-Spectrum Radio Emission from the Low-Mass Active Galactic Nucleus
  GH 10

abstract:
  GH 10 is a broad-lined active galactic nucleus (AGN) energized by a black
hole of mass 800,000 Solar masses. It was the only object detected by Greene et
al. in their Very Large Array (VLA) survey of 19 low-mass AGNs discovered by
Greene & Ho. New VLA imaging at 1.4, 4.9, and 8.5 GHz reveals that GH 10's
emission has an extent of less than 320 pc, has an optically-thin synchrotron
spectrum with a spectral index -0.76+/-0.05, is less than 11 percent linearly
polarized, and is steady - although poorly sampled - on timescales of weeks and
years. Circumnuclear star formation cannot dominate the radio emission, because
the high inferred star formation rate, 18 Solar masses per year, is
inconsistent with the rate of less than 2 Solar masses per year derived from
narrow Halpha and [OII] 3727 emission. Instead, the radio emission must be
mainly energized by the low-mass black hole. GH 10's radio properties match
those of the steep-spectrum cores of Palomar Seyfert galaxies, suggesting that,
like those Seyferts, the emission is outflow-driven. Because GH 10 is radiating
close to its Eddington limit, it may be a local analog of the starting
conditions, or seeds, for supermassive black holes. Future imaging of GH 10 at
higher resolution thus offers an opportunity to study the relative roles of
radiative versus kinetic feedback during black-hole growth.


title: Stability for t-intersecting families of permutations

abstract:
  A family of permutations (\mathcal{A} \subset S_{n}) is said to be
(t)-\textit{intersecting} if any two permutations in (\mathcal{A}) agree on at
least (t) points, i.e. for any (\sigma, \pi \in \mathcal{A}), (|\{i \in [n]:
\sigma(i)=\pi(i)\}| \geq t). It was recently proved by Friedgut, Pilpel and the
author that for (n) sufficiently large depending on (t), a (t)-intersecting
family (\mathcal{A} \subset S_{n}) has size at most ((n-t)!), with equality
only if (\mathcal{A}) is a coset of the stabilizer of (t) points (or
`(t)-coset' for short), proving a conjecture of Deza and Frankl. Here, we first
obtain a rough stability result for (t)-intersecting families of permutations,
namely that for any (t \in \mathbb{N}) and any positive constant (c), if
(\mathcal{A} \subset S_{n}) is a (t)-intersecting family of permutations of
size at least (c(n-t)!), then there exists a (t)-coset containing all but at
most a (O(1/n))-fraction of (\mathcal{A}). We use this to prove an exact
stability result: for (n) sufficiently large depending on (t), if (\mathcal{A}
\subset S_{n}) is a (t)-intersecting family which is not contained within a
(t)-coset, then (\mathcal{A}) is at most as large as the family \mathcal{D} & =
& \{\sigma \in S_{n}: \sigma(i)=i \forall i \leq t, \sigma(j)=j \textrm{for
some} j > t+1\} && \cup \{(1 t+1),(2 t+1),...,(t t+1)\} which has size
((1-1/e+o(1))(n-t)!). Moreover, if (\mathcal{A}) is the same size as
(\mathcal{D}) then it must be a `double translate' of (\mathcal{D}), meaning
that there exist (\pi,\tau \in S_{n}) such that (\mathcal{A}=\pi \mathcal{D}
\tau). We also obtain an analogous result for (t)-intersecting families in the
alternating group (A_{n}).


title:
Spin correlations and cobalt charge states: A new phase diagram of
  sodium cobaltates

abstract:
  Using 23Na NMR measurements on sodium cobaltates at intermediate dopings
(0.44<=x<=0.62), we establish the qualitative change of behavior of the local
magnetic susceptibility at x*=0.63-0.65, from a low x Pauli-like regime to the
high x Curie-Weiss regime. For 0.5<=x<=0.62, the presence of a maximum T* in
the temperature dependence of the susceptibility shows the existence of an
x-dependent energy scale. T_1 relaxation measurements establish the
predominantly antiferromagnetic character of spin correlations for x<x*. This
contradicts the commonly assumed uncorrelated Pauli behavior in this x range
and is at odds with the observed ferromagnetic correlations for x>x*. It is
suggested that at a given x the ferromagnetic correlations might dominate the
antiferromagnetic ones above T*. From 59Co NMR data, it is shown that moving
towards higher x away from x=0.5 results in the progressive appearance of
nonmagnetic Co3+ sites, breaking the homogeneity of Co states encountered for
x<=0.5. The main features of the NMR-detected 59Co quadrupolar effects,
together with indications from the powder x-ray diffraction data, lead us to
sketch a possible structural origin for the Co3+ sites. In light of this
ensemble of new experimental observations, a new phase diagram is proposed,
taking into account the systematic presence of correlations and their
x-dependence.


title: Cutting Cakes Correctly

abstract:
  Without additional hypotheses, Proposition 7.1 in Brams and Taylor's book
"Fair Division" (Cambridge University Press, 1996) is false, as are several
related Pareto-optimality theorems of Brams, Jones and Klamler in their 2006
cake-cutting paper.


title: A Proof of the Cameron-Ku conjecture

abstract:
  A family of permutations A \subset S_n is said to be intersecting if any two
permutations in A agree at some point, i.e. for any \sigma, \pi \in A, there is
some i such that \sigma(i)=\pi(i). Deza and Frankl showed that for such a
family, |A| <= (n-1)!. Cameron and Ku showed that if equality holds then A =
{\sigma \in S_{n}: \sigma(i)=j} for some i and j. They conjectured a
`stability' version of this result, namely that there exists a constant c < 1
such that if A \subset S_{n} is an intersecting family of size at least
c(n-1)!, then there exist i and j such that every permutation in A maps i to j
(we call such a family `centred'). They also made the stronger `Hilton-Milner'
type conjecture that for n \geq 6, if A \subset S_{n} is a non-centred
intersecting family, then A cannot be larger than the family C = {\sigma \in
S_{n}: \sigma(1)=1, \sigma(i)=i \textrm{for some} i > 2} \cup {(12)}, which has
size (1-1/e+o(1))(n-1)!.
  We prove the stability conjecture, and also the Hilton-Milner type conjecture
for n sufficiently large. Our proof makes use of the classical representation
theory of S_{n}. One of our key tools will be an extremal result on
cross-intersecting families of permutations, namely that for n \geq 4, if A,B
\subset S_{n} are cross-intersecting, then |A||B| \leq ((n-1)!)^{2}. This was a
conjecture of Leader; it was recently proved for n sufficiently large by
Friedgut, Pilpel and the author.


title:
$^{77}$Se NMR investigation of the field-induced spin-density-wave
  transitions in (TMTSF)$_2$ClO$_4$

abstract:
  Complementary $^{77}$Se nuclear magnetic resonance (NMR) and electrical
transport have been used to correlate the spin density dynamics with the
subphases of the field-induced spin density wave (FISDW) ground state in \tmt.
We find that the peaks in the spin-lattice relaxation rate 1/T$_1$ appear
within the metal-FISDW phase boundary and/or at first-order subphase
transitions. In the quantum limit above 25 T, the NMR data gives an insight
into the FISDW electronic structure.


title: Stability and Causality in relativistic dissipative hydrodynamics

abstract:
  The stability and causality of the Landau-Lifshitz theory and the
Israel-Stewart type causal dissipative hydrodynamics are discussed. We show
that the problem of acausality and instability are correlated in relativistic
dissipative hydrodynamics and instability is induced by acausality. We further
discuss the stability of the scaling solution. The scaling solution of the
causal dissipative hydrodynamics can be unstable against inhomogeneous
perturbations.


title:
Geometric phase for non-Hermitian Hamiltonian evolution as anholonomy of
  a parallel transport along a curve

abstract:
  We develop a new interpretation of the geometric phase in evolution with a
non-Hermitian real value Hamiltonian by relating it to the angle developed
during the parallel transport along a closed curve by a unit vector triad in
the 3D-Minkovsky space. We also show that this geometric phase is responsible
for the anholonomy effects in stochastic processes considered in [N. A.
Sinitsyn and I. Nemenman, EPL {\bf 77}, 58001 (2007)], and use it to derive the
stochastic system response to periodic parameter variations.


title:
de Haas-van Alphen oscillations in quasi-two-dimensional underdoped
  cuprate superconductors in the canonical ensemble

abstract:
  We calculate the de Haas-van Alphen (dHvA) effect waveform using the
canonical ensemble for different Fermi surface scenarios applicable to the
underdoped cuprate superconductor YBa2Cu3O6.5, in which quantum oscillations
have recently been observed. The harmonic content of the dHvA waveform of the
principal F ~ 500 T frequency is consistent with the existence of a second
thermodynamically dominant section of Fermi surface that acts primarily as a
charge reservoir. Oscillations in the charge density to and from this reservoir
are shown to potentially contribute to the observed large quantum oscillations
in the Hall resistance.


title: Experimental Aspects of Heavy Quarkonium Production at the LHC

abstract:
  More than 30 years after the discovery of the J/psi, its production mechanism
is still poorly understood. With the LHC data it will be possible to study
quarkonia up to very high transverse momenta and with high statistics. In this
note we discuss experimental aspects of J/psi and Upsilon(1S) production at the
LHC. In particular, we investigate the sensitivity of a general purpose LHC
detector to observables, which are complementary to the cross section and
polarisation measurement. These observables would be sensitive to the radiation
produced in association with the quarkonium.


title: The Dark Side of Strongly Coupled Theories

abstract:
  We investigate the constraints of dark matter search experiments on the
different candidates emerging from the minimal quasi-conformal strong coupling
theory with fermions in the adjoint representation. For one candidate, the
current limits of CDMS exclude a tiny window of masses around 120 GeV. We also
investigate under what circumstances the newly proposed candidate composed of a
-2 negatively charged particle and a $^4He^{+2}$ can explain the discrepancy
between the results of the CDMS and DAMA experiments. We found that this type
of dark matter should give negative results in CDMS, while it can trigger the
detectors of DAMA, if a condition between the mass and the binding energy of
the -2 particle with the nucleus of the detector is satisfied.


title: Axions and the Strong CP Problem

abstract:
  Current upper bounds of the neutron electric dipole moment constrain the
physically observable quantum chromodynamic (QCD) vacuum angle $|\bar\theta|
\lesssim 10^{-11}$. Since QCD explains vast experimental data from the 100 MeV
scale to the TeV scale, it is better to explain this smallness of
$|\bar\theta|$ in the QCD framework, which is the strong \Ca\Pa problem. Now,
there exist two plausible solutions to this problem, one of which leads to the
existence of the very light axion. The axion decay constant window, $10^9\
{\gev}\lesssim F_a\lesssim 10^{12} \gev$ for a ${\cal O}(1)$ initial
misalignment angle $\theta_1$, has been obtained by astrophysical and
cosmological data. For $F_a\gtrsim 10^{12}$ GeV with $\theta_1<{\cal O}(1)$,
axions may constitute a significant fraction of dark matter of the universe.
The supersymmetrized axion solution of the strong \Ca\Pa problem introduces its
superpartner the axino which might have affected the universe evolution
significantly. Here, we review the very light axion (theory,
supersymmetrization, and models) with the most recent particle, astrophysical
and cosmological data, and present prospects for its discovery.


title: Pattern Formation of Glioma Cells: Effects of Adhesion

abstract:
  We investigate clustering of malignant glioma cells. \emph{In vitro}
experiments in collagen gels identified a cell line that formed clusters in a
region of low cell density, whereas a very similar cell line (which lacks an
important mutation) did not cluster significantly. We hypothesize that the
mutation affects the strength of cell-cell adhesion. We investigate this effect
in a new experiment, which follows the clustering dynamics of glioma cells on a
surface. We interpret our results in terms of a stochastic model and identify
two mechanisms of clustering. First, there is a critical value of the strength
of adhesion; above the threshold, large clusters grow from a homogeneous
suspension of cells; below it, the system remains homogeneous, similarly to the
ordinary phase separation. Second, when cells form a cluster, we have evidence
that they increase their proliferation rate. We have successfully reproduced
the experimental findings and found that both mechanisms are crucial for
cluster formation and growth.


title:
On a generalization of the Dirac bracket in the De Donder-Weyl
  Hamiltonian formalism

abstract:
  The elements of the contrained dynamics algorithm in the De Donder-Weyl (DW)
Hamiltonian theory for degenerate Lagrangian theories are discussed. A
generalization of the Dirac bracket to the DW Hamiltonian theory with second
class constraints (defined in the text) is presented.


title:
A preliminary analysis of the energy transfer between the dark sectors
  of the Universe

abstract:
  We study the mutual interaction between the dark sectors (dark matter and
dark energy) of the Universe by resorting to the extended thermodynamics of
irreversible processes and constrain the former with supernova type Ia data. As
a byproduct, the present dark matter temperature results in good agreement with
independent estimates of the temperature of the gas of sterile neutrinos.


title:
Bose-Einstein condensates of polar molecules: anisotropic interactions =
  anisotropic mass

abstract:
  So far the theory of Bose-Einstein condensates (BEC) of polar molecules was
based on an ad hoc generalization of equations for spherical atoms. Here I
adopt a rigorous pseudo-potential approach to low-energy dipolar interactions
and derive a non-linear mean-field Schrodinger equation for a
harmonically-trapped condensate. I show that, effectively, the dipolar
interactions alter molecular mass. The resulting effective mass is anisotropic:
to the leading order the mass is altered only for the motion along the
polarizing field. For a typical BEC of spin-polarized magnetically-interacting
alkali-metal atoms the effective atomic mass is reduced by 10% from its bare
value. For a BEC of polar molecules the mass may be reduced by a factor of a
1,000.


title:
On-shell Delta I = 3/2 kaon weak matrix elements with non-zero total
  momentum

abstract:
  We present our results for the on-shell Delta I = 3/2 kaon decay matrix
elements using domain wall fermions and the DBW2 gauge action at one coarse
lattice spacing corresponding to 1/a = 1.31 GeV in the quenched approximation.
The on-shell matrix elements are evaluated in two different frames: the
center-of-mass frame and non-zero total-momentum frame. We employ the formula
proposed by Lellouch and L\"uscher in the center-of-mass frame, and its
extension for non-zero total momentum frame to extract the infinite volume,
on-shell, center-of-mass frame decay amplitudes. We determine the decay
amplitude at the physical pion mass and momentum from the chiral extrapolation
and an interpolation of the relative momentum using the results calculated in
the two frames. We have obtained Re(A_2) = 1.66(23)(^{+48}_{-03})(^{+53}_{-0})
x 10^{-8} GeV and Im(A_2) = -1.181(26)(^{+141}_{-014})(^{+44}_{-0}) x 10^{-12}
GeV at the physical point, using the data at the relatively large pion mass,
m_pi > 0.35 GeV. The first error is statistic, and the second and third are
systematic. The second error is estimated with several fits of the chiral
extrapolation including (quenched) chiral perturbation formula at next to
leading order using only lighter pion masses. The third one is estimated with
an analysis using the lattice dispersion relation. The result of Re(A_2) is
reasonably consistent with experiment.


title: Energy Cascades in Astrophysical Plasma

abstract:
  A local turbulence model is developed to study energy cascades in the
interstellar medium (ISM) based on self-consistent two-dimensional fluid
simulations. The model describes a partially ionized magnetofluid interstellar
medium (ISM) that couples a neutral hydrogen fluid with a plasma primarily
through charge exchange interactions. Charge exchange interactions are
ubiquitous in warm ISM plasma and the strength of the interaction depends
largely on the relative speed between the plasma and the neutral fluid. Unlike
small length-scale linear collisional dissipation in a single fluid, charge
exchange processes introduce channels that can be effective on a variety of
length-scales that depend on the neutral and plasma densities, temperature,
relative velocities, charge exchange cross section and the characteristic
length scales. We find, from scaling arguments and nonlinear coupled fluid
simulations, that charge exchange interactions modify spectral transfer
associated with large scale energy containing eddies. Consequently, the warm
ISM turbulent cascade rate prolongs spectral transfer amongst inertial range
turbulent modes. Turbulent spectra associated with the neutral and plasma ISM
fluids are therefore steeper than those predicted by Kolmogorov's
phenomenology.


title:
Search for large extra dimensions in final states containing one photon
  or jet and large missing transverse energy produced in p-pbar collisions at
  sqrt(s) = 1.96 TeV

abstract:
  We present the results of searches for large extra dimensions in samples of
events with large missing transverse energy and either a photon or a jet
produced in p-pbar collisions at sqrt(s) = 1.96 TeV collected with the CDF II
detector. For gamma + missing Et and jet + missing Et candidate samples
corresponding to 2.0 fb^-1 and 1.1 fb^-1 of integrated luminosity respectively,
we observe good agreement with standard model expectations and obtain a
combined lower limit on the fundamental parameter of the large extra dimensions
model, Md, as a function of the number of extra dimensions in the model.


title:
Absorption of 10 Gev--1 Tev Gamma Rays by Radiation from Broad-Line
  Region in 3C 279

abstract:
  In this paper, we study the photon-photon pair production optical depth for
10 GeV--1 TeV gamma rays from 3C 279 due to the diffuse radiation of broad-line
region (BLR). Assuming a power-law spectrum of $E_{\gamma}^{-a_2}$ for the
photon intensity of very high energy (VHE) gamma rays, $a_1 \gtrsim 405$ and
$a_2\gtrsim 6.4$ are inferred by the integrated photon fluxes measured by MAGIC
and HESS. Based on this power-law spectrum, the pre-absorbed spectra are
inferred by correcting the photon-photon absorption on the diffuse photons of
the BLR (internal absorption) and the extragalactic background light (external
absorption). Position of gamma-ray emitting region $R_{\rm{\gamma}}$ determines
the relative contributions of this two diffuse radiation to the total
absorption for 10 GeV--1 TeV gamma rays. The internal absorption could make
spectral shape of gamma rays more complex than only corrected for the external
absorption, and could lead to the formation of arbitrary softening and
hardening gamma-ray spectra. It should be necessary for the internal absorption
to be considered in studying 10 GeV--1 TeV gamma rays from powerful blazars.
The energies of annihilated gamma-ray photons due to the internal absorption
are likely to be mainly reradiated around GeV. Our results indicate that
$R_{\rm{\gamma}}$ may be between the inner and outer radii of the BLR for 3C
279. This implies for powerful blazars that $R_{\rm{\gamma}}$ might be neither
inside the BLR cavity nor outside the BLR, but be within the BLR shell.
Observations of $\it GLAST$, MAGIC, HESS, and VERITAS in the near future could
give more constraints on the position of the gamma-ray emitting region relative
to the BLR.


title: Neumann-Rosochatius integrable system for strings on AdS_4 x CP^3

abstract:
  We use the reduction of the string dynamics on AdS_4 x CP^3 to the
Neumann-Rosochatius integrable system. All constraints can be expressed simply
in terms of a few parameters. We analyze the giant magnon and single spike
solutions on R_t x CP^3 with two angular momenta in detail and find the
energy-charge relations. The finite-size effects of the giant magnon and single
spike solutions are analyzed.


title: Absorption of 10--200 Gev Gamma Rays by Radiation from BLR in Blazars

abstract:
  In this paper, we study the photon-photon pair production optical depth for
gamma-rays with energies from 10 to 200 GeV emitted by powerful blazars due to
the diffuse radiation field of broad line region (BLR). There are four key
parameters in the BLR model employed to determine the $\gamma-\gamma$
attenuation optical depth of these gamma-rays. They are the gamma-ray emitting
radius $R_{\gamma}$, the BLR luminosity $L_{\rm{BLR}}$, the BLR half thickness
$h$ and the ratio $\tau_{\rm{BLR}}/f_{\rm{cov}}$ of the Thomson optical depth
to the covering factor of BLR. For FSRQs, on average, it is impossible for
gamma-rays with energies from 10 to 200 GeV to escape from the diffuse
radiation field of the BLR. If $\it GLAST$ could detect these gamma-rays for
most of FSRQs, the gamma-ray emitting region is likely to be outside the cavity
formed by the BLR. Otherwise, the emitting region is likely to be inside the
BLR cavity. As examples, we estimate the photon-photon absorption optical depth
of gamma-rays with energies from 10 to 200 GeV for two powerful blazars, HFSRQ
PKS 0405$-$123 and FSRQ 3C 279. Comparing our results with $\it GLAST$
observations in the future could test whether the model employed and the
relevant assumptions in this paper are reliable and reasonable, and then limit
constraints on the position of the gamma-ray emitting region relative to the
BLR and the properties of the BLR.


title: Intersections of several disks of the Riemann sphere as K-spectral sets

abstract:
  We prove that if $n$ closed disks $D_1, D_2, ..., D_n$, of the Riemann sphere
are spectral sets for a bounded linear operator $A$ on a Hilbert space, then
their intersection $D_1\cap D_2...\cap D_n$ is a complete $K$-spectral set for
$A$, with $K\leq n+n(n-1)/\sqrt3$. When $n=2$ and the intersection $X_1\cap
X_2$ is an annulus, this result gives a positive answer to a question of A.L.
Shields (1974).


title: Nearly Isotropic superconductivity in (Ba,K)Fe2As2

abstract:
  Superconductivity was recently observed in the iron-arsenic-based compounds
with a superconducting transition temperature (Tc) as high as 56K [1-7],
naturally raising comparisons with the high Tc copper oxides. The copper oxides
have layered crystal structures with quasi-two-dimensional electronic
properties, which led to speculations that reduced dimensionality (that is,
extreme anisotropy) is a necessary prerequisite for superconductivity at
temperatures above 40 K [8,9]. Early work on the iron-arsenic compounds seemed
to support this view [7,10]. Here we report measurements of the electrical
resistivity in single crystals of (Ba,K)Fe2As2 in a magnetic field up to 60 T.
We find that the superconducting properties are in fact quite isotropic, being
rather independent of the direction of the applied magnetic fields at low
temperature. Such behaviour is strikingly different from all previously-known
layered superconductors [9,11], and indicates that reduced dimensionality in
these compounds is not a prerequisite for high-temperature superconductivity.
We suggest that this situation arises because of the underlying electronic
structure of the iron-arsenide compounds, which appears to be much more three
dimensional than that of the copper oxides. Extrapolations of low-field
single-crystal data incorrectly suggest a high anisotropy and a greatly
exaggerated zero-temperature upper critical field.


title:
Ground-state properties of gapped graphene using the random phase
  approximation

abstract:
  We study the effect of band gap on the ground-state properties of Dirac
electrons in a doped graphene within the random phase approximation at zero
temperature. Band gap dependence of the exchange, correlation and ground-state
energies and the compressibility are calculated. We additionally show that the
conductance in the gapped graphene is smaller than gapless one. We also
calculate the band gap dependence of charge compressibility and it decreases
with increasing the band gap values.


title: Weight Reduction for Mod l Bianchi Modular Forms

abstract:
  Let K be an imaginary quadratic field with class number one and ring of
integers O. We prove that mod l, a system of Hecke eigenvalues occurring in the
first cohomology group of some congruence subgroup Gamma of SL(2,O) can be
realized in the first cohomology with trivial coefficients after increasing the
level of Gamma by l.


title: Complementarity of Future Dark Energy Probes

abstract:
  In recent years a plethora of future surveys have been suggested to constrain
the nature of dark energy. In this paper we adapt a binning approach to the
equation of state factor ``w'' and discuss how future weak lensing, galaxy
cluster counts, Supernovae and baryon acoustic oscillation surveys constrain
the equation of state at different redshifts. We analyse a few representative
future surveys, namely DES, PS1, WFMOS, PS4, EUCLID, SNAP and SKA, and perform
a principal component analysis for the ``w'' bins. We also employ a prior from
Planck cosmic microwave background measurements on the remaining cosmological
parameters. We study at which redshifts a particular survey constrains the
equation of state best and how many principal components are significantly
determined. We then point out which surveys would be sufficiently
complementary. We find that weak lensing surveys, like EUCLID, would constrain
the equation of state best and would be able to constrain of the order of three
significant modes. Baryon acoustic oscillation surveys on the other hand
provide a unique opportunity to probe the equation of state at relatively high
redshifts.


title:
Study of the decoherence of a double quantum dot charge qubit via the
  Redfield equation

abstract:
  By using the Redfield form of the master equation, we investigate the
decoherence times of a double quantum dot charge qubit (DQDCQ) in three
different cases, namely when it is coupled to (I) the piezoelectric coupling
phonon bath (PCPB), (II) the deformation coupling phonon bath (DCPB), and (III)
the Ohmic bath. It is found that our results for case (I) and (II) are in the
same magnitude with those obtained via the exact path integral methods, while
for case (III), the decoherence time is in well agreement with the experimental
value.


title: Investigation of quantum roulette

abstract:
  In this paper, by using permutation matrices as a representation of symmetric
group $S_N$ and Fourier matrix, we investigate quantum roulette with an
arbitrary $N$-state. This strategy, which we introduce, is general method that
allows us to solve quantum game for an arbitrary $N$-state. We consider the
interaction between the system and its environment and study the effect of the
depolarizing channel on this strategy. Finally, as an example we employ this
strategy for quantum roulette with N=3.


title:
Maximized string order parameters in the valence bond solid states of
  quantum integer spin chains

abstract:
  We propose a set of maximized string order parameters to describe the hidden
topological order in the valence bond solid states of quantum integer spin-S
chains. These optimized string order parameters involve spin-twist angles
corresponding to $Z_{S+1}$ rotations around $z$ or $x$-axes, suggesting a
hidden $Z_{S+1}\times Z_{S+1}$ symmetry. Our results also suggest that a local
triplet excitation in the valence bond solid states carries a $Z_{S+1}$
topological charge measured by these maximized string order parameters.


title: Relational Approach to Spin Networks

abstract:
  Individual spinors in a SU(2) spin network are described by their relations
to the background spin network. A 'covariant' formulation of these relations
yields the de Sitter group SO(3,2) as the fundamental symmetry group. Locally
this symmetry group is approximated by the Poincare group, which leaves
invariant (certain) clusters of spinors. The calculated masses of these
clusters reproduce the lepton spectrum. Corrections to the approximate Poincare
group, based on the exact SO(3,2) symmetry, deliver interaction terms,
identical to those of the standard model. In addition, gravitation is obtained.
The calculation of the fine-structure constant reproduces Wyler's formula.


title: Application of Hamamatsu MPPC to T2K Neutrino Detectors

abstract:
  A special type of Hamamatsu MPPC, with a sensitive area of 1.3x1.3mm^2
containing 667 pixels with 50x50um^2 each, has been developed for the near
neutrino detector in the T2K long baseline neutrino experiment. About 60 000
MPPCs will be used in total to read out the plastic scintillator detectors with
wavelength shifting fibers. We report on the basic performance of MPPCs
produced for T2K.


title:
Neutrino Masses with a Suitable Parametrization in the PPF 3-3-1 Gauge
  Model

abstract:
  Plausible phenomenological consequences of the well-known Pisano-Pleitez-
Frampton 3-3-1 model - such as the neutrino masses - are analyzed within the
solution provided by the exact algebraical approach - proposed several years
ago by Cotaescu - for gauge models with high symmetries. We prove that a
suitable parametrisation in the Higgs sector and a redefinition of the three
scalar triplets involved therein can lead to realistic predictions for the
lepton mass spectrum, while a minimal number of coupling parameters are
employed in the Yukawa sector.


title:
Mass production test of Hamamatsu MPPC for T2K neutrino oscillation
  experiment

abstract:
  In the T2K near neutrino detectors, about 60 000 Hamamatsu Multi-Pixel Photon
Counters (MPPCs) will be used. The mass production of MPPC has started in
February 2008.In order to perform quality assurance and to characterize each
device, we have developed an MPPC test system. For each MPPC, gain, breakdown
voltage, noise rate, photo detection efficiency, and cross-talk and after-pulse
rate are measured as functions of the bias voltage and temperature. The design
of the test system and the measurement procedure are described.


title:
Instant Evaluation and Demystification of zeta(n),L(n,chi) that
  Euler,Ramanujan Missed III

abstract:
  We show that for a non-positive value of the first variable,Hurwitz zeta
function becomes a polynomial in the second variable. We show this, using
'integration approach', instead of 'power series approach', which we had
resorted to, in our earlier paper with the same title. This, in particular,
explains why Riemann zeta function at positive even integer arguments, can be
evaluated and why it cannot be evaluated explicitly at positive odd integer
arguments.


title:
Coexistence of two order parameters and a pseudogaplike feature in the
  iron-based superconductor LaFeAsO_(1-x)F_x

abstract:
  The nature and value of the order parameters (OPs) in the superconducting
Fe-based oxypnictides REFeAsO_(1-x)F_x (RE = rare earth) are a matter of
intense debate, also connected to the pairing mechanism which is probably
unconventional. Point-contact Andreev-reflection experiments on
LaFeAsO_(1-x)F_x gave us direct evidence of three energy scales in the
superconducting state: a nodeless superconducting OP, Delta1 = 2.8-4.6 meV,
which scales with the local Tc of the contact; a larger unconventional OP that
gives conductance peaks at 9.8-12 meV, apparently closes below Tc and decreases
on increasing the Tc of the contact; a pseudogaplike feature (i.e. a depression
in the conductance around zero bias), that survives in the normal state up to
T* ~ 140 K (close to the Neel temperature of the undoped compound), which we
associate to antiferromagnetic spin fluctuations (AF SF) coexisting with
superconductivity. These findings point toward a complex, unconventional nature
of superconductivity in LaFeAsO_(1-x)F_x.


title: Stochastic model for nucleosome sliding in the presence of DNA ligands

abstract:
  Heat-induced mobility of nucleosomes along DNA is an experimentally
well-studied phenomenon. A recent experiment shows that the repositioning is
modified in the presence of minor-groove binding DNA ligands. We present here a
stochastic three-state model for the diffusion of a nucleosome along DNA in the
presence of such ligands. It allows us to describe the dynamics and the steady
state of such a motion analytically. The analytical results are in excellent
agreement with numerical simulations of this stochastic process.With this
model, we study the response of a nucleosome to an external force and how it is
affected by the presence of ligands.


title:
Principle of detailed balance and convergence assessment of Markov Chain
  Monte Carlo methods and simulated annealing

abstract:
  Markov Chain Monte Carlo (MCMC) methods are employed to sample from a given
distribution of interest, whenever either the distribution does not exist in
closed form, or, if it does, no efficient method to simulate an independent
sample from it is available. Although a wealth of diagnostic tools for
convergence assessment of MCMC methods have been proposed in the last two
decades, the search for a dependable and easy to implement tool is ongoing. We
present in this article a criterion based on the principle of detailed balance
which provides a qualitative assessment of the convergence of a given chain.
The criterion is based on the behaviour of a one-dimensional statistic, whose
asymptotic distribution under the assumption of stationarity is derived; our
results apply under weak conditions and have the advantage of being completely
intuitive. We implement this criterion as a stopping rule for simulated
annealing in the problem of finding maximum likelihood estimators for
parameters of a 20-component mixture model. We also apply it to the problem of
sampling from a 10-dimensional funnel distribution via slice sampling and the
Metropolis-Hastings algorithm. Furthermore, based on this convergence criterion
we define a measure of efficiency of one algorithm versus another.


title:
Super-rigidity and finiteness of embedded $J$-holomorphic curves on
  Calabi-Yau threefolds

abstract:
  The paper contains a fundamental defect in its framework of using the gauge
action to study the rigidity problem. As a result, the calculations leading to
the main formula is also incorrect.


title: Electronic structure of LaFe1-xCoxAsO from first principle calculations

abstract:
  Based on the first-principles calculations, we have investigated the
geometry, binding properties, density of states and band structures of the
novel superconductor LaFe1-xCoxAsO and its parent compounds with the ZrCuSiAs
structure. We demonstrate that La-O bond and TM-As (TM=Fe or Co) bond are both
strongly covalent, while the LaO and TMAs layers have an almost ionic
interaction through the Bader charge analysis. Partial substitution of iron
with cobalt modify the Fermi level from a steep edge to a flat slope, which
explains why in this system Co doping suppresses the spin density wave (SDW)
transition.


title:
A topological pinching for the injectivity radius of a compact surface
  in S^3 and in H^3

abstract:
  It is given a topological pinching for the injectivity radius of a compact
embedded surface either in the sphere or in the hyperbolic space


title: Random-Matrix Approach to RPA equations. I

abstract:
  We study the RPA equations in their most general form by taking the matrix
elements appearing in the RPA equations as random. This yields either a
unitarily or an orthogonally invariant random-matrix model which is not of the
Cartan type. The average spectrum of the model is studied with the help of a
generalized Pastur equation. Two independent parameters govern the behaviour of
the system: The strength $\alpha^2$ of the coupling between positive- and
negative-energy states and the distance between the origin and the centers of
the two semicircles that describe the average spectrum for $\alpha^2 = 0$, the
latter measured in units of the equal radii of the two semicircles. With
increasing $\alpha^2$, positive- and negative-energy states become mixed and
ever more of the spectral strength of the positive-energy states is transferred
to those at negative energy, and vice versa. The two semicircles are deformed
and pulled toward each other. As they begin to overlap, the RPA equations yield
non--real eigenvalues: The system becomes unstable. We determine analytically
the critical value of the strength for the instability to occur. Several
features of the model are illustrated numerically.


title: Algorithmic randomness and splitting of supermartingales

abstract:
  Randomness in the sense of Martin-L\"of can be defined in terms of lower
semicomputable supermartingales. We show that such a supermartingale cannot be
replaced by a pair of supermartingales that bet only on the even bits (the
first one) and on the odd bits (the second one) knowing all preceding bits.


title:
Algebraic relations among periods and logarithms of rank 2 Drinfeld
  modules

abstract:
  For any rank 2 Drinfeld module rho defined over an algebraic function field,
we consider its period matrix P, which is analogous to the period matrix of an
elliptic curve defined over a number field. Suppose that the characteristic of
F_q is odd and rho is without complex multiplication. We show that the
transcendence degree of the field generated by the entries of P over F_q(theta)
is 4. As a consequence, we show also the algebraic independence of Drinfeld
logarithms of algebraic functions which are linearly independent over
F_q(theta).


title: Earth Flyby and Pioneer Anomalies

abstract:
  Applying Newtonian dynamics in five dimensions rather than four, to a
universe that is closed, isotropic and expanding,suggests that under certain
circumstances an additional and previously unidentified acceleration, a_A, can
arise affecting the four dimensional motion of spacecraft. The two cases of
this acceleration being either real or virtual are considered. In the real
case, simple estimates of a_A are shown to be in partial agreement with
reported acceleration anomalies from several Earth flybys and from the Pioneer
spacecraft. However, these estimates do not fully reconcile with radio Doppler
tracking data. The virtual case, by contrast, appears to overcome these and
other difficulties with the real case, and is discussed in an addendum.
Furthermore, the virtual case has an altitude dependence which makes detection
of any anomaly unlikely above ~2000 km. Equations governing this additional
acceleration have been derived from first principles, without the introduction
of free parameters or new constants and without amendment to the law of
gravity.


title:
On the exactness of the cavity method for Weighted b-Matchings on
  Arbitrary Graphs and its Relation to Linear Programs

abstract:
  We consider the general problem of finding the minimum weight b-matching on
arbitrary graphs. We prove that, whenever the linear programming relaxation of
the problem has no fractional solutions, then the cavity or belief propagation
equations converge to the correct solution both for synchronous and
asynchronous updating.


title: Lepton Flavour Violation in Models with A4 Flavour Symmetry

abstract:
  We analyze lepton flavour violating transitions, leptonic magnetic dipole
moments (MDMs) and electric dipole moments (EDMs) in a class of models
characterized by the flavour symmetry A4 x Z3 x U(1)_{FN}, whose choice is
motivated by the approximate tri-bimaximal mixing observed in neutrino
oscillations. We construct the relevant low-energy effective Lagrangian where
these effects are dominated by dimension six operators, suppressed by the scale
M of new physics. All the flavour breaking effects are universally described by
the vacuum expectation values <Phi> of a set of spurions. We separately analyze
both a supersymmetric and a general case. While the observed discrepancy delta
a_mu in the anomalous MDM of the muon suggests M of order of a few TeV, several
data require M above 10 TeV, in particular the limit on EDM of the electron. In
the general case also the present limit on BR(mu -> e gamma) requires M >10
TeV, at least. The branching ratios for mu -> e gamma, tau -> mu gamma and tau
-> e gamma are all expected to be of the same order. In the supersymmetric case
the constraint from mu -> e gamma is softened and it can be satisfied by a
smaller scale M. In this case both the observed delta a_mu and the current
bound on BR(mu -> e gamma) can be satisfied, at the price of a rather small
value for |<Phi>|, of the order of a few percents, that reflects on a similar
value for theta_{13}.


title: A comparative review of recent researches in geometry

abstract:
  Felix Klein's so-called Erlangen Program was published in 1872 as professoral
dissertation. It proposed a new solution to the problem how to classify and
characterize geometries on the basis of projective geometry and group theory.
The given translation was made in 1892 by Dr. M. W. Haskell and transcribed by
N. C. Rughoonauth. We replaced bibliographical data in text and footnotes with
pointers to a complete bibliography section.


title:
Orbital mixing and nesting in the bilayer manganites
  La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$

abstract:
  A first principles study of La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ compounds for
doping levels $0.3\leq x\leq 0.5$ shows that the low energy electronic
structure of the majority spin carriers is determined by strong momentum
dependent interactions between the Mn $e_g$ $d_{x^2-y^2}$ and $d_{3z^2-r^2}$
orbitals, which in addition to an $x$ dependent Jahn-Teller distortion, differ
in the ferromagnetic and antiferromagnetic phases. The Fermi surface exhibits
nesting behavior that is reflected by peaks in the static susceptibility, whose
positions as a function of momentum have a non-trivial dependence on $x$.


title:
A geometric degree formula for $A$-discriminants and Euler obstructions
  of toric varieties

abstract:
  We give explicit formulas for the dimensions and the degrees of
$A$-discriminant varieties introduced by Gelfand-Kapranov-Zelevinsky. Our
formulas can be applied also to the case where the $A$-discriminant varieties
are higher-codimensional and their degrees are described by the geometry of the
configurations $A$. Moreover combinatorial formulas for the Euler obstructions
of general (not necessarily normal) toric varieties will be also given.


title:
Classical to quantum transition of a driven nonlinear nanomechanical
  resonator

abstract:
  Much experimental effort is invested these days in fabricating
nanoelectromechanical systems (NEMS) that are sufficiently small, cold, and
clean, so as to approach quantum mechanical behavior as their typical quantum
energy scale $\hbar\Omega$ becomes comparable to that of the ambient thermal
energy $k_{B}T$. Such systems will hopefully enable one to observe the quantum
behavior of human-made objects, and test some of the basic principles of
quantum mechanics. Here we expand and elaborate on our recent suggestion [PRL
99 (2007) 040404] to exploit the nonlinear nature of a nanoresonator in order
to observe its transition into the quantum regime. We study this transition for
an isolated resonator, as well as one that is coupled to a heat bath at either
zero or finite temperature. We argue that by exploiting nonlinearities, quantum
dynamics can be probed using technology that is almost within reach. Numerical
solutions of the equations of motion display the first quantum corrections to
classical dynamics that appear as the classical-to-quantum transition occurs.
This provides practical signatures to look for in future experiments with NEMS
resonators.


title:
Pseudomagnetic fields and ballistic transport in a suspended graphene
  sheet

abstract:
  We study a suspended graphene sheet subject to the electric field of a gate
underneath. We compute the elastic deformation of the sheet and the
corresponding effective gauge field, which modifies the electronic transport.
In a clean system the two-terminal conductance of the sample is reduced below
the ballistic limit and is almost totally suppressed at low carrier
concentrations in samples under tension. Residual disorder restores a small
finite conductivity.


title:
Doping evolution of itinerant magnetic excitations in Fe-based
  oxypnictides

abstract:
  Employing the four-band tight-binding model we study theoretically the doping
dependence of the spin response in the normal state of novel Fe-based pnictide
superconductors. We show that the commensurate spin density wave (SDW)
transition that arises due to interband scattering between the hole
$\alpha$-pockets and the electron $\beta$-pockets disappears already at the
doping concentration $x \approx 0.04$ reflecting the evolution of the Fermi
surfaces. Correspondingly, with further increase of the doping the
antiferromagnetic fluctuations are suppressed for $x > 0.1$ and the
Im$\chi({\bf Q_{AFM}},\omega)$ becomes nearly temperature independent. At the
same time, we observe that the uniform susceptibility deviates from the
Pauli-like behavior and is increasing with increasing temperature reflecting
the activation processes for the $\alpha$-Fermi surfaces up to temperatures of
about T=800K. With increase of the doping the absolute value of the uniform
susceptibility lowers and its temperature dependence changes. In particular, it
is a constant at low temperatures and then decreases with increasing
temperature. We discuss our results in a context of recent experimental data.


title: The pattern of genetic hitchhiking under recurrent mutation

abstract:
  Genetic hitchhiking describes evolution at a neutral locus that is linked to
a selected locus. If a beneficial allele rises to fixation at the selected
locus, a characteristic polymorphism pattern (so-called selective sweep)
emerges at the neutral locus. The classical model assumes that fixation of the
beneficial allele occurs from a single copy of this allele that arises by
mutation. However, recent theory (Pennings and Hermisson, 2006a; Pennings and
Hermisson, 2006b) has shown that recurrent beneficial mutation at biologically
realistic rates can lead to markedly different polymorphism patterns, so called
soft selective sweeps. We extend an approach that has recently been developed
for the classical hitchhiking model (Schweinsbergand Durrett, 2005; Etheridge,
Pfaffelhuber, Wakolbinger, 2006) to study the recurrent mutation scenario. We
show that the genealogy at the neutral locus can be approximated (to leading
orders in the selection strength) by a marked Yule process with immigration.
Using this formalism, we derive an improved analytical approximation for the
expected heterozygosity at the neutral locus at the time of fixation of the
beneficial allele.


title: Audit and Change Analysis of Spreadsheets

abstract:
  Because spreadsheets have a large and growing importance in real-world work,
their contents need to be controlled and validated. Generally spreadsheets have
been difficult to verify, since data and executable information are stored
together. Spreadsheet applications with multiple authors are especially
difficult to verify, since controls over access are difficult to enforce.
Facing similar problems, traditional software engineering has developed
numerous tools and methodologies to control, verify and audit large
applications with multiple developers. We present some tools we have developed
to enable 1) the audit of selected, filtered, or all changes in a spreadsheet,
that is, when a cell was changed, its original and new contents and who made
the change, and 2) control of access to the spreadsheet file(s) so that
auditing is trustworthy. Our tools apply to OpenOffice.org calc spreadsheets,
which can generally be exchanged with Microsoft Excel.


title: Quantum mechanics on space with SU(2) fuzziness

abstract:
  Quantum mechanics of models is considered which are constructed in spaces
with Lie algebra type commutation relations between spatial coordinates. The
case is specialized to that of the group SU(2), for which the formulation of
the problem via the Euler parameterization is also presented. SU(2)-invariant
systems are discussed, and the corresponding eigenvalue problem for the
Hamiltonian is reduced to an ordinary differential equation, as it is the case
with such models on commutative spaces.


title:
Projective modules over noncommutative tori are multi-window Gabor
  frames for modulation spaces

abstract:
  In the present investigation we are linking noncommutative geometry over
noncommutative tori with Gabor analysis, where the first has its roots in
operator algebras and the second in time-frequency analysis. Therefore we are
in the position to invoke modern methods of operator algebras, e.g. topological
stable rank of Banach algebras, to exploit the deeper properties of Gabor
frames. Furthermore we are able to extend results due to Connes and Rieffel on
projective modules over noncommutative tori to Banach algebras, which arise in
a natural manner in Gabor analysis. The main goal of this investigation is
twofold: (i) an interpretation of projective modules over noncommutative tori
in terms of Gabor analysis and (ii) that the Morita-Rieffel equivalence between
noncommutative tori is the natural framework for the duality theory of Gabor
frames. More concretely, we interpret generators of projective modules over
noncommutative tori as the Gabor atoms of multi-window Gabor frames for
modulation spaces. Moreover, we show that this implies the {\it existence} of
good multi-window Gabor frames for modulation spaces with Gabor atoms in
Feichtinger's algebra and in Schwartz space.


title:
Bulges of disk galaxies at intermediate redshifts. I. Samples with and
  without bulges in the Groth Strip Survey

abstract:
  We aim to define a sample of intermediate-z disk galaxies harbouring central
bulges, and a complementary sample of disk galaxies without measurable bulges.
We intend to provide colour profiles for both samples, as well as measurements
of nuclear, disk, and global colours, which may be used to constrain the
relative ages of bulges and disks. We select a diameter-limited sample of
galaxies in images from the HST/WFPC2 Groth Strip survey, which is divided into
two subsamples of higher and lower inclination to assess the role of dust in
the measures quantities. Mergers are visually identified and excluded. We take
special care to control the pollution by ellipticals. The bulge sample is
defined with a criterion based on nuclear surface brightness excess over the
inward extrapolation of the exponential law fitted to the outer regions of the
galaxies. We extract colour profiles on the semi-minor axis least affected by
dust in the disk, and measure nuclear colours at 0.85 kpc from the centre over
those profiles. Disk colours are measured on major axis profiles; global
colours are obtained from 2.6"-diameter apertures. We obtain a parent sample
containing 248 galaxies with known redshifts, spectroscopic or photometric,
spanning 0.1 < z < 1.2. The bulge subsample comprises 54 galaxies (21.8% of the
total), while the subsample with no measureable bulges is 55.2% of the total
(137 galaxies). The remainder (23%) is composed of mergers. We list nuclear,
disk, and global colours (observed and restframe) and magnitudes (apparent and
absolute), as well as galaxy colour gradients for the samples with and without
bulges. We also provide images, colour maps, plots of spectral energy
distributions, major-axis surface brightness profiles, and minor-axis colour
profiles for both samples.


title:
Inelastic neutron scattering and lattice dynamical calculations in
  BaFe2As2

abstract:
  We report here first extensive measurements of the temperature dependence of
phonon density of states of BaFe2As2, the parent compound of the newly
discovered FeAs-based superconductors, using inelastic neutron scattering. The
experiments were carried out on the thermal time-of-flight neutron spectrometer
IN4 at the ILL on a polycrystalline sample. There is no appreciable change in
the spectra between T = 10 K and 200 K, although the sample undergoes a
magnetic as well as a tetragonal-to-orthorhombic structural phase transition at
140 K. This indicates a rather harmonic phonon system. Shell model lattice
dynamical calculations based on interatomic potentials are carried out to
characterize the phonon data. The calculations predict a shift of the
Ba-phonons to higher energies at 4 GPa. The average energy of the phonons of
the Ba-sublattice is also predicted to increase on partial substitution of Ba
by K to Ba0.6K0.4. The calculations show good agreement with the experimental
phonon spectra, and also with the specific heat data from the literature.


title: Mesoscopic Aspects of Strongly Interacting Cold Atoms

abstract:
  Harmonically trapped lattice bosons with strong repulsive interactions
exhibit a superfluid-Mott-insulator heterostructure in the form of a "wedding
cake". We discuss the mesoscopic aspects of such a system within a
one-dimensional scattering matrix approach and calculate the scattering
properties of quasi-particles at a superfluid-Mott-insulator interface as an
elementary building block to describe transport phenomena across such a
boundary. We apply the formalism to determine the heat conductivity through a
Mott layer, a quantity relevant to describe thermalization processes in the
optical lattice setup. We identify a critical hopping below which the heat
conductivity is strongly suppressed.


title:
First Principles Calculations of Spin-Dependent Conductance of Graphene
  Flakes

abstract:
  Using ab initio density functional theory and quantum transport calculations
based on nonequilibrium Green's function formalism we study structural,
electronic, and transport properties of hydrogen-terminated short graphene
nanoribbons (graphene flakes) and their functionalization with vanadium atoms.
Rectangular graphene flakes are stable, having geometric and electronic
structures quite similar to that of extended graphene nanoribbons. We show that
a spin-polarized current can be produced by pure, hydrogenated rectangular
graphene flakes by exploiting the spatially-separated edge states of the flake
using asymmetric, non-magnetic contacts. Functionalization of the graphene
flake with magnetic adatoms such as vanadium also leads to spin-polarized
currents even with symmetric contacts. We observe and discuss sharp
discontinuities in the transmission spectra which arise from Fano resonances of
localized states in the flake.


title: Permutations Which Make Transitive Groups Primitive

abstract:
  In this article we look into characterizing primitive groups in the following
way. Given a primitive group we single out a subset of its generators such that
these generators alone (the so-called primitive generators) imply the group is
primitive. The remaining generators ensure transitivity or comply with specific
features of the group.
  We show that, other than the symmetric and alternating groups, there are
infinitely many primitive groups with one primitive generator each. These
primitive groups are certain Mathieu groups, certain projective general and
projective special linear groups, and certain subgroups of some affine special
linear groups.


title: De Sitter Invariance and a Possible Mechanism of Gravity

abstract:
  It is believed that gravity will be explained in the framework of the
existing quantum theory when one succeeds in eliminating divergencies at large
momenta or small distances (although the phenomenon of gravity has been
observed only at nonrelativistic momenta and large distances). We consider a
quantum-mechanical description of systems of two free particles in de Sitter
invariant quantum theory (i.e. the paper contains nothing but the two-body de
Sitter kinematics). In our pure algebraic approach the cosmological constant
problem does not arise. It is shown that a system can be simultaneously
quasiclassical in relative momentum and energy only if the cosmological
constant is not anomalously small. We explicitly construct the relative
distance operator. The corresponding eigenvectors differ from standard ones at
both, large and small momenta. At large momenta they ensure fast convergence of
quasiclassical wave functions. There also exists an anomalously large (but
finite) contribution from small momenta, which is a consequence of the fact
that the cosmological constant is finite. We argue that gravity might be a
manifestation of this contribution.


title:
On uniqueness of large solutions of nonlinear parabolic equations in
  nonsmooth domains

abstract:
  We study the existence and uniqueness of the positive solutions of the
problem (P): $\partial_tu-\Delta u+u^q=0$ ($q>1$) in $\Omega\times (0,\infty)$,
$u=\infty$ on $\partial\Omega\times (0,\infty)$ and $u(.,0)\in L^1(\Omega)$,
when $\Omega$ is a bounded domain in $\mathbb R^N$. We construct a maximal
solution, prove that this maximal solution is a large solution whenever
$q<N/(N-2)$ and it is unique if $\partial\Omega=\partial\bar\Omega^c$. If
$\partial\Omega$ has the local graph property, we prove that there exists at
most one solution to problem (P)


title: The moduli space of 3-dimensional associative algebras

abstract:
  In this paper, we give a classification of the 3-dimensional associative
algebras over the complex numbers, including a construction of the moduli
space, using versal deformations to determine how the space is glued together.


title:
Un th\'eor\`eme de la masse positive pour le probl\`eme de Yamabe en
  dimension paire

abstract:
  Let $(M,g)$ be a compact conformally flat manifold of dimension $n\geq4$ with
positive scalar curvature. According to a positive mass theorem by Schoen and
Yau, the constant term in the development of the Green function of the
conformal Laplacian is positive if $(M,g)$ is not conformally equivalent to the
sphere. On spin manifolds, there is an elementary proof of this fact by Ammann
and Humbert, based on a proof of Witten. Using differential forms instead of
spinors, we give an elementary proof on even dimensional manifolds, without any
other topological assumption.


title: Miniversal deformations of dialgebras

abstract:
  We develop the theory of versal deformations of dialgebras and describe a
method for constructing a miniversal deformation of a dialgebra.


title: Normal and anomalous solitons in the theory of dynamical Cooper pairing

abstract:
  We obtain multi-soliton solutions of the time-dependent Bogoliubov-de Gennes
equations or, equivalently, Gorkov equations that describe the dynamics of a
fermionic condensate in the dissipationless regime. There are two kinds of
solitons - normal and anomalous. At large times, normal multi-solitons
asymptote to unstable stationary states of the BCS Hamiltonian with zero order
parameter (normal states), while the anomalous ones tend to eigenstates
characterized by a nonzero anomalous average. Under certain circumstances,
multi-soliton solutions break up into sums of single solitons. In the linear
analysis near the stationary states, solitons correspond to unstable modes.
Generally, they are nonlinear extensions of these modes, so that a stationary
state with $k$ unstable modes gives rise to a $k$-soliton solution. We relate
parameters of the multi-solitons to those of the asymptotic stationary state,
which determines the conditions necessary for exciting solitons. We further
argue that the dynamics in many physical situations is multi-soliton.


title: Pion-Muon Asymmetry Revisited

abstract:
  Long ago an unexpected and unexplainable phenomena was observed. The
distribution of muons from positive pion decay at rest was anisotropic with an
excess in the backward direction relative to the direction of the proton beam
from which the pions were created. Although this effect was observed by several
different groups with pions produced by different means, the result was not
accepted by the physics community, because it is in direct conflict with a
large set of other experiments indicating that the pion is a pseudoscalar
particle. It is possible to satisfy both sets of experiments if helicity-zero
vector particles exist and the pion is such a particle. Helicity-zero vector
particles have direction but no net spin. For the neutral pion to be a vector
particle requires an additional modification to conventional theory as
discussed herein. An experiment is proposed which can prove that the asymmetry
in the distribution of muons from pion decay is a genuine physical effect
because the asymmetry can be modified in a controllable manner. A positive
result will also prove that the pion is NOT a pseudoscalar particle.


title: Accuracy in Spreadsheet Modelling Systems

abstract:
  Accuracy in spreadsheet modelling systems can be reduced due to difficulties
with the inputs, the model itself, or the spreadsheet implementation of the
model. When the "true" outputs from the system are unknowable, accuracy is
evaluated subjectively. Less than perfect accuracy can be acceptable depending
on the purpose of the model, problems with inputs, or resource constraints.
Users build modelling systems iteratively, and choose to allocate limited
resources to the inputs, the model, the spreadsheet implementation, and to
employing the system for business analysis. When making these choices, users
can suffer from expectation bias and diagnosis bias. Existing research results
tend to focus on errors in the spreadsheet implementation. Because industry has
tolerance for system inaccuracy, errors in spreadsheet implementations may not
be a serious concern. Spreadsheet productivity may be of more interest.


title: Research Strategy and Scoping Survey on Spreadsheet Practices

abstract:
  We propose a research strategy for creating and deploying prescriptive
recommendations for spreadsheet practice. Empirical data on usage can be used
to create a taxonomy of spreadsheet classes. Within each class, existing
practices and ideal practices can he combined into proposed best practices for
deployment. As a first step we propose a scoping survey to gather non-anecdotal
data on spreadsheet usage. The scoping survey will interview people who develop
spreadsheets. We will investigate the determinants of spreadsheet importance,
identify current industry practices, and document existing standards for
creation and use of spreadsheets. The survey will provide insight into user
attributes, spreadsheet importance, and current practices. Results will be
valuable in themselves, and will guide future empirical research.


title: Structural distance and evolutionary relationship of networks

abstract:
  Evolutionary mechanism in a self-organized system cause some functional
changes that force to adapt new conformation of the interaction pattern between
the components of that system. Measuring the structural differences one can
retrace the evolutionary relation between two systems. We present a method to
quantify the topological distance between two networks of different sizes,
finding that the architectures of the networks are more similar within the same
class than the outside of their class. With 43 cellular networks of different
species, we show that the evolutionary relationship can be elucidated from the
structural distances.

categories: q-bio.QM cond-mat.stat-mech physics.data-an q-bio.PE


title: New Guidelines For Spreadsheets

abstract:
  Current prescriptions for spreadsheet style specify modular separation of
data, calcu1ation and output, based on the notion that writing a spreadsheet is
like writing a computer program. Instead of a computer programming style, this
article examines rules of style for text, graphics, and mathematics. Much
'common wisdom' in spreadsheets contradicts rules for these well-developed
arts. A case is made here for a new style for spreadsheets that emphasises
readability. The new style is described in detail with an example, and
contrasted with the programming style.


title: When, why and how to test spreadsheets

abstract:
  Testing is a vital part of software development, and spreadsheets are like
any other software in this respect. This paper discusses the testing of
spreadsheets in the light of one practitioner's experience. It considers the
concept of software testing and how it differs from reviewing, and describes
when it might take place. Different types of testing are described, and some
techniques for performing them presented. Some of the commonly encountered
problems are discussed.


title: On gravitational defects, particles and strings

abstract:
  We study the inclusion of point and string matter in the deSitter gauge
theory, or MacDowell-Mansouri formulation of four dimensional gravity. We
proceed by locally breaking the gauge symmetries of general relativity along
worldlines and worldsheets embedded in the spacetime manifold. Restoring full
gauge invariance introduces new dynamical fields which describe the dynamics of
spinning matter coupled to gravity. We discuss the physical interpretation of
the obtained formalism by studying the flat limit and the spinless case on
arbitrary backgrounds. It turns out that the worldline action describes a
massive spinning particle, while the worldsheet action contains the Nambu-Goto
string augmented with spinning contributions. Finally, we study the
gravity/matter variational problem and conclude by discussing potential
applications of the formalism to the inclusion of the Nambu-Goto string in
spinfoam models of four dimensional quantum gravity.