title:
A Fixed-Parameter Algorithm for Random Instances of Weighted d-CNF
  Satisfiability

abstract:
  We study random instances of the weighted $d$-CNF satisfiability problem
(WEIGHTED $d$-SAT), a generic W[1]-complete problem. A random instance of the
problem consists of a fixed parameter $k$ and a random $d$-CNF formula
$\weicnf{n}{p}{k, d}$ generated as follows: for each subset of $d$ variables
and with probability $p$, a clause over the $d$ variables is selected uniformly
at random from among the $2^d - 1$ clauses that contain at least one negated
literals.
  We show that random instances of WEIGHTED $d$-SAT can be solved in $O(k^2n +
n^{O(1)})$-time with high probability, indicating that typical instances of
WEIGHTED $d$-SAT under this instance distribution are fixed-parameter
tractable. The result also hold for random instances from the model
$\weicnf{n}{p}{k,d}(d')$ where clauses containing less than $d' (1 < d' < d)$
negated literals are forbidden, and for random instances of the renormalized
(miniaturized) version of WEIGHTED $d$-SAT in certain range of the random
model's parameter $p(n)$. This, together with our previous results on the
threshold behavior and the resolution complexity of unsatisfiable instances of
$\weicnf{n}{p}{k, d}$, provides an almost complete characterization of the
typical-case behavior of random instances of WEIGHTED $d$-SAT.


title: Elasticity of soft particles and colloids near Random Close Packing

abstract:
  Assemblies of purely repulsive and frictionless particles, such as emulsions
or hard spheres, display very curious properties near their jamming transition,
which occurs at the random close packing for mono-disperse spheres. Although
such systems do not contain the long and cross-linked polymeric chains
characterizing a rubber, they behave macroscopically in a similar way: the
shear modulus $G$ can become infinitely smaller than the bulk modulus $B$.
After reviewing recent theoretical results on the structure of such packing (in
particular their coordination) I will propose an explanation for the observed
scaling of the elastic moduli, and explain why the arguments both apply to soft
and hard particles.


title:
Mean-Field Analysis of Electric Field Effect on Charge Orders in Organic
  Conductors

abstract:
  In order to investigate charge ordering phenomena under electric field,
static nonequilibrium Hartree approximation (SNHA) method is formulated on the
basis of the nonequilibrium Green's functions introduced by Keldysh. By
applying the SNHA to the 3/4-filling extended Hubbard model on anisotropic
triangular lattice, we study the stabilities and amplitudes of 3-fold and
horizontal charge orders in ${\theta}$ and ${\theta}_d$-(BEDT-TTF)$_2X$ salts
under the electric field. The obtained results show that the electric field
stabilizes the 3-fold state in comparison to the horizontal state. The
amplitude of the 3-fold state tends to decrease by the field, whereas that of
the horizontal state does not change.


title: Discrete spectrum and Weyl's asymptotic formula for incomplete manifolds

abstract:
  Motivated by recent interest in the spectrum of the Laplacian of incomplete
surfaces with isolated conical singularities, we consider more general
incomplete m-dimensional manifolds with singularities on sets of codimension at
least 2. With certain restrictions on the metric, we establish that the
spectrum is discrete and satisfies Weyl's asymptotic formula.


title: Theory of spin magnetohydrodynamics

abstract:
  We develop a phenomenological hydrodynamic theory of coherent magnetic
precession coupled to electric currents. Exchange interaction between electron
spin and collective magnetic texture produces two reciprocal effects:
spin-transfer torque on the magnetic order parameter and the Berry-phase gauge
field experienced by the itinerant electrons. The dissipative processes are
governed by three coefficients: the ohmic resistance, Gilbert damping of the
magnetization, and the "beta coefficient" describing viscous coupling between
magnetic dynamics and electric current, which stems from spin mistracking of
the magnetic order. We develop general magnetohydrodynamic equations and
discuss the net dissipation produced by the coupled dynamics. The latter in
particular allows us to determine a lower bound on the magnetic-texture
resistivity.


title:
Origin of structural and kinematical properties of the Small Magellanic
  Cloud

abstract:
  We investigate structural, kinematical, and chemical properties of stars and
gas in the Small Magellanic Cloud (SMC) interacting with the Large Magellanic
Cloud (LMC) and the Galaxy based on a series of self-consistent chemodynamical
simulations. We adopt a new "dwarf spheroidal model" in which the SMC initially
has both old stars with a spherical spatial distribution and an extended HI gas
disk. We mainly investigate SMC's evolution for the last 3 Gyr within which the
Magellanic stream (MS) and the Magellanic bridge (MB) can be formed as a result
of the LMC-SMC-Galaxy interaction. Our principal results, which can be tested
against observations, are as follows. The final spatial distribution of the old
stars projected onto the sky is spherical even after the strong LMC-SMC-Galaxy
interaction, whereas that of the new ones is significantly flattened and
appears to form a bar structure. Old stars have the line-of-sight velocity
dispersion (sigma) of ~ 30 km/s and slow rotation with the maximum rotational
velocity (V) of less than slow rotation with the maximum rotational velocity
(V) of less than 20 km/s and show asymmetry in the radial profiles. New stars
have a smaller sigma than old ones and a significant amount of rotation
(V/sigma >1). HI gas shows velocity dispersions of sigma = 10-40 km/s a high
maximum rotational velocity (V ~ 50 km/s), and the spatial distribution similar
to that of new stars. The new stars with ages younger than 3 Gyr show a
negative metallicity gradient in the sense that more metal-rich stars are
located in the inner regions of the SMC.


title: Uniform Local Existence for Inhomogeneous Rotating Fluid Equations

abstract:
  We investigate the equations of anisotropic incompressible viscous fluids in
$\R^3$, rotating around an inhomogeneous vector $B(t, x_1, x_2)$. We prove the
global existence of strong solutions in suitable anisotropic Sobolev spaces for
small initial data, as well as uniformlocal existence result with respect to
the Rossby number in the same functional spaces under the additional assumption
that $B=B(t,x_1)$ or $B=B(t,x_2)$. We also obtain the propagation of the
isotropic Sobolev regularity using a new refined product law.


title: Lower bounds for index of Wente tori

abstract:
  We show numerically that any of the constant mean curvature tori first found
by Wente must have index at least eight.


title:
The Huygens principle for a uniaxial dielectric-magnetic medium with
  gyrotropic-like magnetoelectric properties

abstract:
  The dyadic Green functions for a uniaxial dielectric-magnetic medium,
together with a reversible field transformation, were implemented to derive a
formulation of the Huygens principle appropriate to a uniaxial
dielectric-magnetic medium with gyrotropic-like magnetoelectric properties.


title: Rescattering Effect and Near Threshold Enhancement of $p\bar p$ System

abstract:
  We study the observed enhancement of a $p\bar p$ system near the threshold in
the process $J/\psi \to \gamma p\bar p$ and $e^+ e^- \to p\bar p$. From early
studies the enhancement can be explained by final state interactions, which are
in general taken into account with some potential models. In this work we offer
a simple approach within quantum field theory to explain the observed
enhancement. We point out that among different final state interactions the
rescattering in a $N\bar N$ system though exchange of $\pi$ is the most
important. The effects of the rescattering is completely fixed by the
well-known coupling $g_{\pi NN}$. Our results show that the enhancement in
$J/\psi \to \gamma p\bar p$ and $e^+ e^- \to p\bar p$ can be well described
with the rescattering effects.


title:
On the statistical significance of temporal firing patterns in
  multi-neuronal spike trains

abstract:
  Repeated occurrences of serial firing sequences of a group of neurons with
fixed time delays between neurons are observed in many experiments involving
simultaneous recordings from multiple neurons. Such temporal patterns are
potentially indicative of underlying microcircuits and it is important to know
when a repeatedly occurring pattern is statistically significant. These
sequences are typically identified through correlation counts, such as in the
two-tape algorithm of Abeles and Gerstein. In this paper we present a method
for deciding on the significance of such correlations by characterizing the
influence of one neuron on another in terms of conditional probabilities and
specifying our null hypothesis in terms of a bound on the conditional
probabilities. This method of testing significance of correlation counts is
more general than the currently available methods since under our null
hypothesis we do not assume that the spiking processes of different neurons are
independent. The structure of our null hypothesis also allows us to rank order
the detected patterns in terms of the strength of interaction among the neurons
constituting the pattern. We demonstrate our method of assessing significance
on simulated spike trains involving inhomogeneous Poisson processes with strong
interactions, where the correlation counts are obtained using the two-tape
algorithm.


title: Generalized covariant gyrokinetic dynamics of magnetoplasmas

abstract:
  A basic prerequisite for the investigation of relativistic astrophysical
magnetoplasmas, occurring typically in the vicinity of massive stellar objects
(black holes, neutron stars, active galactic nuclei, etc.), is the accurate
description of single-particle covariant dynamics, based on gyrokinetic theory
(Beklemishev et al.,1999-2005). Provided radiation-reaction effects are
negligible, this is usually based on the assumption that both the space-time
metric and the EM fields (in particular the magnetic field) are suitably
prescribed and are considered independent of single-particle dynamics, while
allowing for the possible presence of gravitational/EM perturbations driven by
plasma collective interactions which may naturally arise in such systems. The
purpose of this work is the formulation of a generalized gyrokinetic theory
based on the synchronous variational principle recently pointed out (Tessarotto
et al., 2007) which permits to satisfy exactly the physical realizability
condition for the four-velocity. The theory here developed includes the
treatment of nonlinear perturbations (gravitational and/or EM) characterized
locally, i.e., in the rest frame of a test particle, by short wavelength and
high frequency. Basic feature of the approach is to ensure the validity of the
theory both for large and vanishing parallel electric field. It is shown that
the correct treatment of EM perturbations occurring in the presence of an
intense background magnetic field generally implies the appearance of
appropriate four-velocity corrections, which are essential for the description
of single-particle gyrokinetic dynamics.


title: IKT approach for quantum hydrodynamic equations

abstract:
  A striking feature of standard quantum mechanics is its analogy with
classical fluid dynamics. In particular it is well known the Schr\"{o}dinger
equation can be viewed as describing a classical compressible and non-viscous
fluid, described by two (quantum) fluid fields ${\rho ,% \mathbf{V}} $, to be
identified with the quantum probability density and velocity field. This
feature has suggested the construction of a phase-space hidden-variable
description based on a suitable inverse kinetic theory (IKT; Tessarotto et al.,
2007). The discovery of this approach has potentially important consequences
since it permits to identify the classical dynamical system which advances in
time the quantum fluid fields. This type of approach, however requires the
identification of additional fluid fields. These can be generally identified
with suitable directional fluid temperatures $T_{QM,i}$ (for $i=1,2,3$), to be
related to the expectation values of momentum fluctuations appearing in the
Heisenberg inequalities. Nevertheless the definition given previously for them
(Tessarotto et al., 2007) is non-unique. In this paper we intend to propose a
criterion, based on the validity of a constant H-theorem, which provides an
unique definition for the quantum temperatures.


title: Near Zone Hydrodynamics of AdS/CFT Jet Wakes

abstract:
  The energy-momentum tensor of a supersonic heavy quark jet moving through a
strongly-coupled $\mathcal{N}=4$ SYM plasma is analyzed in terms of first-order
Navier-Stokes hydrodynamics. We focus on the near zone ``head'' region close to
the heavy quark where deviations from hydrodynamic behavior are expected to be
large. For realistic quark velocities, $v=0.99$, we find that the
non-hydrodynamical head region is confined at a narrow pancake surrounding the
jet with a width $\sim 1/T$ and transverse radius $\sim 3/T$. Outside this jet
head region, the jet induced stress is well approximated by Navier-Stokes
hydrodynamics.


title: On the index of constant mean curvature 1 surfaces in hyperbolic space

abstract:
  We show that the index of a constant mean curvature 1 surface in hyperbolic
3-space is completely determined by the compact Riemann surface and secondary
Gauss map that represent it in Bryant's Weierstrass representation. We give
three applications of this observation. Firstly, it allows us to explicitly
compute the index of the catenoid cousins and some other examples. Secondly, it
allows us to be able to apply a method similar to that of Choe (using Killing
vector fields on minimal surfaces in Euclidean 3-space) to our case as well,
resulting in lower bounds of index for other examples. And thirdly, it allows
us to give a more direct proof of the result by do Carmo and Silveira that if a
constant mean curvature 1 surface in hyperbolic 3-space has finite total
curvature, then it has finite index. Finally, we show that for any constant
mean curvature 1 surface in hyperbolic 3-space that has been constructed via a
correspondence to a minimal surface in Euclidean 3-space, we can take advantage
of this correspondence to find a lower bound for its index.


title: Overlaid Cellular and Mobile Ad Hoc Networks

abstract:
  In cellular systems using frequency division duplex, growing Internet
services cause unbalance of uplink and downlink traffic, resulting in poor
uplink spectrum utilization. Addressing this issue, this paper considers
overlaying an ad hoc network onto a cellular uplink network for improving
spectrum utilization and spatial reuse efficiency. Transmission capacities of
the overlaid networks are analyzed, which are defined as the maximum densities
of the ad hoc nodes and mobile users under an outage constraint. Using tools
from stochastic geometry, the capacity tradeoff curves for the overlaid
networks are shown to be linear. Deploying overlaid networks based on frequency
separation is proved to achieve higher network capacities than that based on
spatial separation. Furthermore, spatial diversity is shown to enhance network
capacities.


title: Power sums of Hecke's eigenvalues and application

abstract:
  We sharpen some estimates of Rankin on power sums of Hecke eigenvalues, by
using Kim & Shahidi's recent results on higher order symmetric powers. As an
application, we improve Kohnen, Lau & Shparlinski's lower bound for the number
of Hecke eigenvalues of same signs.


title:
Ehrhart Theory for Lawrence Polytopes and Orbifold Cohomology of
  Hypertoric Varieties

abstract:
  We establish a connection between the orbifold cohomology of hypertoric
varieties and the Ehrhart theory of Lawrence polytopes. More specifically, we
show that the dimensions of the orbifold cohomology groups of a hypertoric
variety are equal to the coefficients of the Ehrhart $\delta$-polynomial of the
associated Lawrence polytope. As a consequence, we deduce a formula for the
Ehrhart $\delta$-polynomial of a Lawrence polytope and use the injective part
of the Hard Lefschetz Theorem for hypertoric varieties to deduce some
inequalities between the coefficients of the $\delta$-polynomial.


title:
Kac-Moody algebras and the structure of cosmological singularities: a
  new light on the Belinskii-Khalatnikov-Lifshitz analysis

abstract:
  The unexpected and fascinating emergence of hyperbolic Coxeter groups and
Lorentzian Kac-Moody algebras in the investigation of gravitational theories in
the vicinity of a cosmological singularity is briefly reviewed. Some open
questions raised by this intriguing result, and some attempts to answer them,
are outlined.


title: Limit Surfaces of Riemann Examples

abstract:
  The family of embedded, singly periodic minimal surfaces of Riemann have as
limit-surfaces the helicoid, the catenoid, a single plane, or an infinite set
of equally-spaced parallel planes.


title: Nonsingular Ricci flow on a noncompact manifold in dimension three

abstract:
  We consider the Ricci flow $\frac{\partial}{\partial t}g=-2Ric$ on the
3-dimensional complete noncompact manifold $(M,g(0))$ with non-negative
curvature operator, i.e., $Rm\geq 0, |Rm(p)|\to 0, ~as ~d(o,p)\to 0.$ We prove
that the Ricci flow on such a manifold is nonsingular in any finite time.


title: String Compactification and Unification of Forces

abstract:
  I review our recent attempts toward obtaining the MSSM from string orbifold
compactification. The required constraints are the existence of three families
and R parity, vectorlike exotics, one pair of Higgs doublets, and the SU(5)$'$
hidden sector for dynamical breaking of SUSY toward a GMSB scenario. We also
comment on the threshold correction which are influenced by a power law
evolution of gauge couplings through the KK radius in non-prime orbifolds and
can be used to fit the couplings.


title:
Effective grain surface area in the formation of molecular hydrogen in
  interstellar clouds

abstract:
  In the interstellar clouds, molecular hydrogens are formed from atomic
hydrogen on grain surfaces. An atomic hydrogen hops around till it finds
another one with which it combines. This necessarily implies that the average
recombination time, or equivalently, the effective grain surface area depends
on the relative numbers of atomic hydrogen influx rate and the number of sites
on the grain. Our aim is to discover this dependency. We perform a numerical
simulation to study the recombination of hydrogen on grain surfaces in a
variety of cloud conditions. We use a square lattice (with a periodic boundary
condition) of various sizes on two types of grains, namely, amorphous carbon
and olivine. We find that the steady state results of our simulation match very
well with those obtained from a simpler analytical consideration provided the
`effective' grain surface area is written as $\sim S^{\alpha}$, where, $S$ is
the actual physical grain area and $\alpha$ is a function of the flux of atomic
hydrogen which is determined from our simulation. We carry out the simulation
for various astrophysically relevant accretion rates. For high accretion rates,
small grains tend to become partly saturated with $H$ and $H_2$ and the
subsequent accretion will be partly inhibited. For very low accretion rates,
the number of sites to be swept before a molecular hydrogen can form is too
large compared to the actual number of sites on the grain, implying that
$\alpha$ is greater than unity.


title: Some Control Variates for exotic options

abstract:
  There are no known exact formulas for the valuation of a number of exotic
options, and this is particularly true for options under discrete monitoring
and for American style options. Therefore, one usually recourses to a Monte
Carlo Simulation approach, amongst other numerical methods, to estimate the
value of these options. The problem which then arises with this method is one
of variance reduction. Control variates are often used, and we present some
results concerning these control variables, for the valuation of Asian and
lookback options. An inequality on functions of correlations useful for
comparing estimators in variance reduction procedures is also provided.


title: Classification of barrier options

abstract:
  For a given level of accuracy in option prices, the paper considers the
problem of deciding when exactly, as one or more of the pricing parameters
change, a barrier option degenerates into a simpler type of option. This
problem is meaningful in the real world where option prices are always
determined within a certain level of accuracy. The problem is reduced to
finding certain critical values of the initial stock price, and this is
achieved through a probability-based approach.


title:
Role of pulling direction in understanding the energy landscape of
  proteins

abstract:
  Single molecule force spectroscopy provide details of the underlying energy
surfaces of proteins which are essential to the understanding of their
unfolding process. Recently, it has been observed experimentally that by
pulling proteins in different directions relative to their secondary structure,
one can gain a better understanding of the shape of the energy landscape. We
consider simple lattice models which are anisotropic in nature to study the
response of a force in unfolding of a polymer. Our analytical solution of the
model, supported by extensive numerical calculations, reveal that the force
temperature diagrams are very different depending on the direction of the
applied force. We find that either unzipping or shearing kind transitions
dominate the dynamics of the unfolding process depending solely on the
direction of the applied force.


title: Time evolution of simple molecules during proto-star collapse

abstract:
  We study the formation and evolution of several molecules in a collapsing
interstellar cloud using a reasonably large reaction network containing more
then four hundred atomic and molecular species. We employ a time dependent,
spherically symmetric, hydrodynamics code to follow the hydrodynamic and
chemical evolution of the collapsing cloud. The flow is assumed to be
self-gravitating. We use two models to study the hydrodynamic evolution: in the
first model, we inject matter into an initially low density region and in the
second model, we start with a constant density cloud and let it collapse due to
self-gravity. We study the evolution of the central core for both the cases. We
include the grain chemistry to compute the formation of molecular hydrogen and
carried out the effect of gas and grain chemistry at each time step. We follow
the collapse for more than $10^{14}$s (about 3 million years) and present the
time evolution of the globally averaged abundances of various simple but
biologically important molecules, such as glycine, alanine etc. We compare our
results with those obtained from observations found that for lighter molecules
the agreement is generally very good. For complex molecules we tend to under
predict the abundances. This indicates that other pathways could be present to
form these molecules or more accurate reaction rates were needed.
  Keywords: hydrodynamics; star formation; ISM; chemical evolution


title:
Recombination Efficiency of Molecular Hydrogen on Interstellar Grains-II
  A Numerical Study

abstract:
  A knowledge of the recombination time on the grain surfaces has been a major
obstacle in deciding the production rate of molecular hydrogen and other
molecules in the interstellar medium. We present a numerical study to compute
this time for molecular hydrogen for various cloud and grain parameters. We
also find the time dependence, particularly when a grain is freshly injected
into the system. Apart from the fact that the recombination times seem to be
functions of the grain parameters such as the activation barrier energy,
temperature etc, our result also shows the dependence on the number of sites in
the grain $S$ and the effective accretion rate per site $a_s$ of atomic
hydrogen. Simply put, the average time that a pair of atomic hydrogens will
take to produce one molecular hydrogen depends on how heavily the grain is
already populated by atomic and molecular hydrogens and how fast the hopping
and desorption times are. We show that if we write the average recombination
time as $T_r \sim S^\alpha/A_H$, where, $A_H$ is the hopping rate, then
$\alpha$ could be much greater than 1 for all astrophysically relevant
accretion rates. Thus the average formation rate of $H_2$ is also dependent on
the grain parameters, temperature and the accretion rate. We believe that our
result will affect the overall rate of the formation of complex molecules such
as methanol which require successive hydrogenation on the grain surfaces in the
interstellar medium.


title:
Correlated curvature perturbations and magnetogenesis from the GUT gauge
  bosons

abstract:
  In the context of hybrid inflation at the scale of grand unification, it is
shown that, if (some of) the gauge bosons of the unbroken grand unified group
obtain a flat superhorizon spectrum of perturbations from inflation they can
affect or even generate both the observed curvature perturbation and
simultaneously produce a sizable primordial magnetic field capable of
explaining galactic magnetism. The mechanism employs the vector curvaton idea
for a supermassive grand unified gauge boson after the breaking of grand
unification.


title:
Meromorphic Approximants to Complex Cauchy Transforms with Polar
  Singularities

abstract:
  We study AAK-type meromorphic approximants to functions $F$, where $F$ is a
sum of a rational function $R$ and a Cauchy transform of a complex measure
$\lambda$ with compact regular support included in $(-1,1)$, whose argument has
bounded variation on the support. The approximation is understood in $L^p$-norm
of the unit circle, $p\geq2$. We obtain that the counting measures of poles of
the approximants converge to the Green equilibrium distribution on the support
of $\lambda$ relative to the unit disk, that the approximants themselves
converge in capacity to $F$, and that the poles of $R$ attract at least as many
poles of the approximants as their multiplicity and not much more.


title:
The classical point-electron in Colombeau's theory of nonlinear
  generalized functions

abstract:
  The electric and magnetic fields of a pole-dipole singularity attributed to a
point-electron-singularity in the Maxwell field are expressed in a Colombeau
algebra of generalized functions. This enables one to calculate dynamical
quantities quadratic in the fields which are otherwise mathematically
ill-defined: The self-energy (i.e., `mass'), the self-angular momentum (i.e.,
`spin'), the self-momentum (i.e., `hidden momentum'), and the self-force. While
the total self-force and self-momentum are zero, therefore insuring that the
electron-singularity is stable, the mass and the spin are diverging integrals
of delta-squared-functions. Yet, after renormalization according to standard
prescriptions, the expressions for mass and spin are consistent with quantum
theory, including the requirement of a gyromagnetic ratio greater than one. The
most striking result, however, is that the electric and magnetic fields differ
from the classical monopolar and dipolar fields by delta-function terms which
are usually considered as insignificant, while in a Colombeau algebra these
terms are precisely the sources of the mechanical mass and spin of the
electron-singularity.


title: Recent Developments in Supersymmetric and Hidden Sector Dark Matter

abstract:
  New results which correlate SUSY dark matter with LHC signals are presented,
and a brief review of recent developments in supersymmetric and hidden sector
dark matter is given. It is shown that the direct detection of dark matter is
very sensitive to the hierarchical SUSY sparticle spectrum and the spectrum is
very useful in distinguishing models. It is shown that the prospects of the
discovery of neutralino dark matter are very bright on the "Chargino Wall" due
to a copious number of model points on the Wall, where the NLSP is the
Chargino, and the spin independent neutralino-proton cross section is
maintained at high values in the $10^{-44}$cm$^{2}$ range for neutralino masses
up to $\sim 850$ GeV . It is also shown that the direct detection of dark
matter along with lepton plus jet signatures and missing energy provide dual,
and often complementary, probes of supersymmetry. Finally, we discuss an out of
the box possibility for dark matter, which includes dark matter from the hidden
sector, which could either consist of extra weakly interacting dark matter (a
Stino XWIMP), or milli-charged dark matter arising from the Stueckelberg
extensions of the MSSM or the SM.


title:
On the Degree Sequence and its Critical Phenomenon of an Evolving Random
  Graph Process

abstract:
  In this paper we focus on the problem of the degree sequence for the
following random graph process. At any time-step $t$, one of the following
three substeps is executed: with probability $\alpha_1$, a new vertex $x_t$ and
$m$ edges incident with $x_t$ are added; or, with probability
$\alpha-\alpha_1$, $m$ edges are added; or finally, with probability $1-\a$,
$m$ random edges are deleted. Note that in any case edges are added in the
manner of preferential attachment. we prove that there exists a critical point
$\alpha_c$ satisfying: 1) if $\alpha_1<\alpha_c$, then the model has power law
degree sequence; 2) if $\alpha_1>\alpha_c$, then the model has exponential
degree sequence; and 3) if $\alpha_1=\alpha_c$, then the model has a degree
sequence lying between the above two cases.


title: Magnetoelectric birefringence revisited

abstract:
  Electromagnetic wave propagation inside isotropic material media
characterized by dielectric coefficients $\varepsilon_{\mu\nu}(E,B)$ and
$\mu_{\mu\nu}(E,B)$ is examined. The regime of the eikonal approximation is
considered. The Hadamard method of field disturbances is used and the
dispersion relations are obtained by solving the Fresnel equation. Some
applications of the formalism are presented. Particularly, birefringence
phenomena induced by applied external fields are derived and discussed. It is
shown that magnetoelectric birefringence effect can occur even without the
presence of Kerr and Cotton-Mouton effects, provided the physical system
satisfies certain conditions.


title: Sparse Online Learning via Truncated Gradient

abstract:
  We propose a general method called truncated gradient to induce sparsity in
the weights of online learning algorithms with convex loss functions. This
method has several essential properties: The degree of sparsity is continuous
-- a parameter controls the rate of sparsification from no sparsification to
total sparsification. The approach is theoretically motivated, and an instance
of it can be regarded as an online counterpart of the popular
$L_1$-regularization method in the batch setting. We prove that small rates of
sparsification result in only small additional regret with respect to typical
online learning guarantees. The approach works well empirically. We apply the
approach to several datasets and find that for datasets with large numbers of
features, substantial sparsity is discoverable.


title: Remnant inequalities and doubly-twisted conjugacy in free groups

abstract:
  We give two results for computing doubly-twisted conjugacy relations in free
groups with respect to homomorphisms $\phi$ and $\psi$ such that certain
remnant words from $\phi$ are longer than the images of generators under
$\psi$.
  Our first result is a remnant inequality condition which implies that two
words $u$ and $v$ are not doubly-twisted conjugate. Further we show that if
$\psi$ is given and $\phi$, $u$, and $v$ are chosen at random, then the
probability that $u$ and $v$ are not doubly-twisted conjugate is 1. In the
particular case of singly-twisted conjugacy, this means that if $\phi$, $u$,
and $v$ are chosen at random, then $u$ and $v$ are not in the same
singly-twisted conjugacy class with probability 1.
  Our second result generalizes Kim's "bounded solution length". We give an
algorithm for deciding doubly-twisted conjugacy relations in the case where
$\phi$ and $\psi$ satisfy a similar remnant inequality. In the particular case
of singly-twisted conjugacy, our algorithm suffices to decide any twisted
conjugacy relation if $\phi$ has remnant words of length at least 2.
  As a consequence of our generic properties we give an elementary proof of a
recent result of Martino, Turner, and Ventura, that computes the densities of
injective and surjective homomorphisms from one free group to another. We
further compute the expected value of the density of the image of a
homomorphism.


title: The superconductivity at 18 K in LiFeAs system

abstract:
  A new iron arsenide superconducting system LiFeAs was found that crystallizes
into a tetragonal structure with space group P4/nmm. The superconductivity with
Tc up to 18 K was observed in the compounds. This simple 111 type layered iron
arsenide superconductor can be viewed as an analogue of the infinite layer
structure of copper oxides.


title:
Stabilizations of Heegaard splittings of sufficiently complicated
  3-manifolds (Preliminary Report)

abstract:
  We construct families of manifolds that have pairs of genus $g$ Heegaard
splittings that must be stabilized roughly $g$ times to become equivalent. We
also show that when two unstabilized, boundary-unstabilized Heegaard splittings
are amalgamated by a "sufficiently complicated" map, the resulting splitting is
unstabilized. As a corollary, we produce a manifold that has distance one
Heegaard splittings of arbitrarily high genus. Finally, we show that in a
3-manifold formed by a sufficiently complicated gluing, a low genus,
unstabilized Heegaard splitting can be expressed in a unique way as an
amalgamation over the gluing surface.


title: Chemical and physical small-scale structure in a pre-stellar core

abstract:
  We present a comparative study of several molecular lines and of the dust
contiunuum at 1.2mm in a pre-stellar core that is embedded in the Galactic
cirrus cloud MCLD123.5+24.9. Previous studies found that the core is
gravitationally stable and shows signs of inward motion. Using the Owens Valley
(OVRO) and Plateau de Bure (PdB) interferometers we obtained high-angular
resolution maps of the core in the carbon monosulfide CS 2-1 and the
cyanoacetylene HC3N 10-9 transitions. Together with CS 5-4, C34S 3-2, and
bolometer data obtained with the IRAM 30m telescope, we analyse the excitation
conditions and the structural properties of the cloud. On the one hand, the new
CS 2-1 observations reveal significant substructure on a scale of about 7",
i.e., the beam size, corresponding to about 1050 AU at an adopted distance of
150pc. On the other hand, the interferometric observations in the HC3N 10-9
transition shows just one single well resolved clump in the inner part of the
core. This core is well described by an intensity profile following from a
centrally peaked volume density distribution. We find no evidence for depletion
of CS onto dust grains. The inward motion seen in the CS 2-1 occurs one-sided
from the middle of the filamentary cloud towards the HC3N core.


title: Observation of an ultracold plasma instability

abstract:
  We present the first observation of an instability in an expanding ultracold
plasma. We observe periodic emission of electrons from an ultracold plasma in
weak, crossed magnetic and electric fields, and a strongly perturbed electron
density distribution in electron time-of-flight projection images. We identify
this instability as a high-frequency electron drift instability due to the
coupling between the electron drift wave and electron cyclotron harmonic, which
has large wavenumbers corresponding to wavelengths close to the electron
gyroradius.


title: Suppression of quantum tunneling for all spins for easy-axis systems

abstract:
  The semi-classical limit of quantum spin systems corresponds to a dynamical
Lagrangian which contains the usual kinetic energy, the couplings and
interactions of the spins and an additional, first order kinematical term which
corresponds to the Wess-Zumino-Novikov-Witten (WZNW) term for the spin degree
of freedom \cite{og}. It was shown that in the case of the kinetic dynamics
determined only by the WZNW term, half odd integer spin systems show a lack of
tunneling phenomena whereas integer spin systems are subject to it \cite{l} in
the case of potentials with easy-plane easy-axis symmetry. Here we prove, for
the theory with a normal quadratic kinetic term of arbitrary strength or the
first order theory with azimuthal symmetry (which is equivalently the so-called
easy-axis situation), that the tunneling is in fact suppressed for all non-zero
values of spin. This model exemplifies the concept that in the presence of
complex Euclidean action, it is necessary to use the ensuing complex critical
points in order to define the quantum (perturbation) theory \cite{ampr}. In the
present example, if we do not do so, exactly the opposite, erroneous
conclusion, that the tunneling is unsuppressed for all spins, is reached.


title:
Role of pinning potentials in heat transport through disordered harmonic
  chain

abstract:
  The role of quadratic onsite pinning potentials on determining the size (N)
dependence of the disorder averaged steady state heat current <J>, in a
isotopically disordered harmonic chain connected to stochastic heat baths, is
investigated. For two models of heat baths, namely white noise baths and
Rubin's model of baths, we find that the N dependence of <J> is the same and
depends on the number of pinning centers present in the chain. In the absence
of pinning, <J> ~ 1/N^{1/2} while in presence of one or two pins <J> ~
1/N^{3/2}. For a finite (n) number of pinning centers with 2 <= n << N, we
provide heuristic arguments and numerical evidence to show that <J> ~
1/N^{n-1/2}. We discuss the relevance of our results in the context of recent
experiments.


title:
On the application of Maxwell's theory to many-body systems, or why the
  resistive magnetohydrodynamic equations are not closed

abstract:
  The resistive magnetohydrodynamic (MHD) equations as usually defined in the
quasineutral approximation refer to a system of 14 scalar equations in 14
scalar variables, hence are determined to be complete and soluble. These
equations are a combination of Navier-Stokes and a subset of Maxwell's.
However, one of the vector equations is actually an identity when viewed from
the potential formulation of electrodynamics, hence does not determine any
degrees of freedom. Only by reinstating Gauss's law does the system of
equations become closed, allowing for the determination of both the current and
mass flow velocity from the equations of motion. Results of a typical analysis
of the proposed electromagnetic hydrodynamic model including the magnetization
force are presented.


title:
On the Throughput Allocation for Proportional Fairness in Multirate IEEE
  802.11 DCF

abstract:
  This paper presents a modified proportional fairness (PF) criterion suitable
for mitigating the \textit{rate anomaly} problem of multirate IEEE 802.11
Wireless LANs employing the mandatory Distributed Coordination Function (DCF)
option. Compared to the widely adopted assumption of saturated network, the
proposed criterion can be applied to general networks whereby the contending
stations are characterized by specific packet arrival rates, $\lambda_s$, and
transmission rates $R_d^{s}$.
  The throughput allocation resulting from the proposed algorithm is able to
greatly increase the aggregate throughput of the DCF while ensuring fairness
levels among the stations of the same order of the ones available with the
classical PF criterion. Put simply, each station is allocated a throughput that
depends on a suitable normalization of its packet rate, which, to some extent,
measures the frequency by which the station tries to gain access to the
channel. Simulation results are presented for some sample scenarios, confirming
the effectiveness of the proposed criterion.


title:
Effect of magnetization and magnetic field variation on stationary
  axisymmetric equilibrium

abstract:
  The inclusion of plasma magnetization in the equations of stationary
equilibrium is derived, and its effect on the determination of axisymmetric
equilibrium calculated. A factor of 2 on the pressure gradient arises in the
equilibrium equation from the force felt by the dipole moment density. The
algebraic and differential equation formulations are compared both with and
without consideration of magnetization, revealing the effects of both
magnetization and magnetic field variation on the equilibrium, which become
more pronounced for high pressures in a weak external field. The equivalence of
the magnetized equilibrium equation with the standard equilibrium equation in
the limit of vanishing magnetization is demonstrated.


title:
Band-Dominated Fredholm Operators and a Question of Rabinovich, Roch and
  Silbermann

abstract:
  Withdrawn due to a likely error with the homeomorphism at line (4).
  Old abstract: In the monograph 'Limit Operators and their Applications in
Operator Theory', the authors define the operator spectrum of a band-dominated
operator T and prove that T is Fredholm if and only if all of the operators in
its operator spectrum are invertible with uniformly bounded inverses. They also
ask whether the uniform boundedness condition can in fact be dispensed with. In
this note we answer this question affirmatively.


title:
Stationary axial plasma equilibrium in light of the magnetic
  polarization force

abstract:
  The standard equilibrium equation for magnetized plasma is extended to
account for the magnetic polarization force. A factor of the pressure gradient
arising from the magnetic decomposition of the Hall term survives the limit of
vanishing magnetization and is canceled by a contribution from the magnetic
polarization force, such that the proposed equation reduces to the standard
form in the free current limit. Comparison of the solutions for an axially
symmetric plasma column indicates agreement with the free current limit for
vanishing magnetization and variation in the field and current profiles as the
degree of magnetization increases.


title:
Graph polynomials and their applications II: Interrelations and
  interpretations

abstract:
  This paper surveys a comprehensive, although not exhaustive, sampling of
graph polynomials with the goal of providing a brief overview of a variety of
techniques defining a graph polynomial and then for decoding the combinatorial
information it contains. The polynomials we discuss here are not generally
specializations of the Tutte polynomial, but they are each in some way related
to the Tutte polynomial, and often to one another. We emphasize these
interrelations and explore how an understanding of one polynomial can guide
research into others. We also discuss multivariable generalizations of some of
these polynomials and the theory facilitated by this. We conclude with two
examples, one from biology and one from physics, that illustrate the
applicability of graph polynomials in other fields.
  This is the second chapter of a two chapter series, and concludes Graph
Polynomials and Their Applications I: The Tutte Polynomial, arXiv:0803.3079


title: Vortex states in patterned exchange biased NiO/Ni samples

abstract:
  We investigated the magnetization reversal of arrays of exchange biased
NiO/Ni squares with superconducting quantum interference device magnetometry
and micromagnetic simulations. The edges of the squares were 0.5, 1.5, and 3.0
$\mu$m long. The NiO/Ni structures exhibit vortexlike hysteresis loops and
micromagnetic calculations show that this feature is due to several vortices
nucleating in the islands. Furthermore, for the arrays with squares of 1.5
$\mu$m edge length, the sign of the exchange bias field changes, as compared to
the same continuous NiO/Ni layer. We attribute the vortex nucleation and the
change of the exchange bias field to the interplay between shape and
unidirectional anisotropy.


title:
Basics of Quantum Mechanics, Geometrization and some Applications to
  Quantum Information

abstract:
  In this paper we present a survey of the use of differential geometric
formalisms to describe Quantum Mechanics. We analyze Schr\"odinger framework
from this perspective and provide a description of the Weyl-Wigner
construction. Finally, after reviewing the basics of the geometric formulation
of quantum mechanics, we apply the methods presented to the most interesting
cases of finite dimensional Hilbert spaces: those of two, three and four level
systems (one qubit, one qutrit and two qubit systems). As a more practical
application, we discuss the advantages that the geometric formulation of
quantum mechanics can provide us with in the study of situations as the
functional independence of entanglement witnesses.


title: On the stability analysis in the transition to turbulence problem

abstract:
  In this note, which is of general stability theory interest, we discuss some
of the key assertions usually stated in the context of the transition to
turbulence problem. In particular, the two main points made here in the setting
of the transition problem are (i) the crucial dependence of the stability
results on whether the problem is considered on infinite or semi-infinite
domain, and (ii) the energy conservation by the nonlinear terms of the
Navier-Stokes equations. As an application, we demonstrate that the Couette
flow, when analyzed in the mathematical setting most correctly reflecting the
way the experiments are usually done, is spectrally unstable for finite
Reynolds numbers in apparent contradiction to the commonly accepted classical
century-old results. Also, the interrelation of various stability notions, the
effects of infinite dimensionality, the covariant nature of the transition
phenomena and how non-normality of the linear operators and finite-amplitude
instability fit into this picture are discussed as well.


title:
Challenging More Updates: Towards Anonymous Re-publication of Fully
  Dynamic Datasets

abstract:
  Most existing anonymization work has been done on static datasets, which have
no update and need only one-time publication. Recent studies consider
anonymizing dynamic datasets with external updates: the datasets are updated
with record insertions and/or deletions. This paper addresses a new problem:
anonymous re-publication of datasets with internal updates, where the attribute
values of each record are dynamically updated. This is an important and
challenging problem for attribute values of records are updating frequently in
practice and existing methods are unable to deal with such a situation.
  We initiate a formal study of anonymous re-publication of dynamic datasets
with internal updates, and show the invalidation of existing methods. We
introduce theoretical definition and analysis of dynamic datasets, and present
a general privacy disclosure framework that is applicable to all anonymous
re-publication problems. We propose a new counterfeited generalization
principle alled m-Distinct to effectively anonymize datasets with both external
updates and internal updates. We also develop an algorithm to generalize
datasets to meet m-Distinct. The experiments conducted on real-world data
demonstrate the effectiveness of the proposed solution.


title: Functions with isolated singularities on surfaces

abstract:
  Let M be a smooth connected compact surface, P be either the real line R^1 or
the circle S^1, and f:M-->P be a smooth mapping. In a previous series of papers
for the case when f is a Morse map the author calculated the homotopy types of
stabilizers and orbits of f with respect to the right action of the
diffeomorphisms group of M. The present paper extends those calculations to a
large class of maps M-->P with degenerate singularities satisfying certain set
of axioms.


title:
On the Perturbative Stability of the QCD Predictions for the Ratio
  $R=F_L/F_T$ in Heavy-Quark Leptoproduction

abstract:
  We analyze the perturbative and parametric stability of the QCD predictions
for the Callan-Gross ratio $R(x,Q^2)=F_L/F_T$ in heavy-quark leptoproduction.
We consider the radiative corrections to the dominant photon-gluon fusion
mechanism. In various kinematic regions, the following contributions are
investigated: exact NLO results at low and moderate $Q^2\lesssim m^2$,
asymptotic NLO predictions at high $Q^2\gg m^2$, and both NLO and NNLO
soft-gluon (or threshold) corrections at large Bjorken $x$. Our analysis shows
that large radiative corrections to the structure functions $F_T(x,Q^2)$ and
$F_L(x,Q^2)$ cancel each other in their ratio $R(x,Q^2)$ with good accuracy. As
a result, the NLO contributions to the Callan-Gross ratio are less than 10% in
a wide region of the variables $x$ and $Q^2$. We provide compact LO predictions
for $R(x,Q^2)$ in the case of low $x\ll 1$. A simple formula connecting the
high-energy behavior of the Callan-Gross ratio and low-$x$ asymptotics of the
gluon density is derived. It is shown that the obtained hadron-level
predictions for $R(x\to 0,Q^2)$ are stable under the DGLAP evolution of the
gluon distribution function. Our analytic results simplify the extraction of
the structure functions $F_2^c(x,Q^2)$ and $F_2^b(x,Q^2)$ from measurements of
the corresponding reduced cross sections, in particular at DESY HERA.


title:
Measuring the intrinsic charge transfer gap using K-edge X-ray
  absorption spectroscopy

abstract:
  Pre-edge features in X-ray absorption spectroscopy contain key information
about the lowest excited states and thus on the most interesting physical
properties of the system. In transition metal oxides they are particularly
structured but extracting physical parameters by comparison with a calculation
is not easy due to several computational challenges. By combining core-hole
attraction and correlation effects in first principles approach, we calculate
Ni K-edge X-ray absorption spectra in NiO. We obtain a striking, parameter-free
agreement with experimental data and show that dipolar pre-edge features above
the correlation gap are due to non-local excitations largely unaffected by the
core-hole. We show that in charge transfer insulators, this property can be
used to measure the correlation gap and probe the intrinsic position of the
upper-Hubbard band.


title:
Optimal prediction for radiative transfer: A new perspective on moment
  closure

abstract:
  Moment methods are classical approaches that approximate the mesoscopic
radiative transfer equation by a system of macroscopic moment equations. An
expansion in the angular variables transforms the original equation into a
system of infinitely many moments. The truncation of this infinite system is
the moment closure problem. Many types of closures have been presented in the
literature. In this note, we demonstrate that optimal prediction, an approach
originally developed to approximate the mean solution of systems of nonlinear
ordinary differential equations, can be used to derive moment closures. To that
end, the formalism is generalized to systems of partial differential equations.
Using Gaussian measures, existing linear closures can be re-derived, such as
$P_N$, diffusion, and diffusion correction closures. This provides a new
perspective on several approximations done in the process and gives rise to
ideas for modifications to existing closures.


title: Kahler manifolds with quasi-constant holomorphic curvature

abstract:
  The aim of this paper is to classify compact Kahler manifolds with
quasi-constant holomorphic sectional curvature.


title: Retarded integral inequalities of Gronwall-Bihari type

abstract:
  We establish two nonlinear retarded integral inequalities. Bounds on the
solution of some retarded equations are then obtained.


title: The length operator in Loop Quantum Gravity

abstract:
  The dual picture of quantum geometry provided by a spin network state is
discussed. From this perspective, we introduce a new operator in Loop Quantum
Gravity - the length operator. We describe its quantum geometrical meaning and
derive some of its properties. In particular we show that the operator has a
discrete spectrum and is diagonalized by appropriate superpositions of spin
network states. A series of eigenstates and eigenvalues is presented and an
explicit check of its semiclassical properties is discussed.


title: Multilevel effects in the Rabi oscillations of a Josephson phase qubit

abstract:
  We present Rabi oscillation measurements of a Nb/AlOx/Nb dc superconducting
quantum interference device (SQUID) phase qubit with a 100 um^2 area junction
acquired over a range of microwave drive power and frequency detuning. Given
the slightly anharmonic level structure of the device, several excited states
play an important role in the qubit dynamics, particularly at high power. To
investigate the effects of these levels, multiphoton Rabi oscillations were
monitored by measuring the tunneling escape rate of the device to the voltage
state, which is particularly sensitive to excited state population. We compare
the observed oscillation frequencies with a simplified model constructed from
the full phase qubit Hamiltonian and also compare time-dependent escape rate
measurements with a more complete density-matrix simulation. Good quantitative
agreement is found between the data and simulations, allowing us to identify a
shift in resonance (analogous to the ac Stark effect), a suppression of the
Rabi frequency, and leakage to the higher excited states.


title: Some Examples of Blackadar and Kirchberg's MF Algebras

abstract:
  In the paper, we provide some examples of MF algebras by considering minimal
or maximal tensor products of MF algebras and crossed products of MF algebras
by finite groups or an integer group. We also present some examples of
C$^*$-algebras, whose BDF extension semigroup is not group. These examples
include, for example, $
  C_r^*(F_n)\otimes_{max} C^*(F_n) $, $ C_r^*(F_n)\otimes_{min} C^*(F_n) $,
$C_r^*(H_1\ast H_2)$ with $2\le |H_1|<\infty$ and $3\le |H_2|<\infty$ where
$|H_1|$, $|H_2|$ are the orders of thr groups $H1$, or $H_2$ respectively, and
many others.


title:
Equation of state and effective mass of the unitary Fermi gas in a 1D
  periodic potential

abstract:
  By solving the Bogoliubov -- de Gennes equations at zero temperature, we
study the effects of a one-dimensional optical lattice on the behavior of a
superfluid Fermi gas at unitarity. We show that, due to the lattice, at low
densities the gas becomes highly compressible and the effective mass is large,
with a consequent significant reduction of the sound velocity. We discuss the
role played by the lattice in the formation of molecules and the emergence of
two-dimensional effects in the equation of state. Predictions for the density
profiles and for the frequency of the collective oscillations in the presence
of harmonic trapping are also given.


title:
Maximal spanning trees, asset graphs and random matrix denoising in the
  analysis of dynamics of financial networks

abstract:
  We study the time dependence of maximal spanning trees and asset graphs based
on correlation matrices of stock returns. In these networks the nodes represent
companies and links are related to the correlation coefficients between them.
Special emphasis is given to the comparison between ordinary and denoised
correlation matrices. The analysis of single- and multi-step survival ratios of
the corresponding networks reveals that the ordinary correlation matrices are
more stable in time than the denoised ones. Our study also shows that some
information about the cluster structure of the companies is lost in the
denoising procedure. Cluster structure that makes sense from an economic point
of view exists, and can easily be observed in networks based on denoised
correlation matrices. However, this structure is somewhat clearer in the
networks based on ordinary correlation matrices. Some technical aspects, such
as the random matrix denoising procedure, are also presented.


title:
The particle spectrum of the Tricritical Ising Model with spin reversal
  symmetric perturbations

abstract:
  We analyze the evolution of the particle spectrum of the Tricritical Ising
Model by varying the couplings of the energy and vacancy density fields. The
particle content changes from the spectrum of a supersymmetric theory (either
of an exact or a spontaneously broken supersymmetric theory) to the spectrum of
seven particles related to the underlying E_7 structure. In the low temperature
phase some of these excitations are topologically charged particles that are
stable under an arbitrary variation of the parameters. The high and low
temperature phases of the model are related by duality. In some regions of the
two couplings there are also present false vacua and sequences of bound states.
In order to study the non-integrable features of this model we employ the Form
Factor Perturbation Theory and the Truncated Conformal Space Approach.


title: Unitary Spherical Super-Landau Models

abstract:
  A Hilbert space metric is found for the SU(2|1)-invariant `superflag' Landau
models, parametrized by integer 2N' and real number M, such that the Hilbert
space norm is positive definite. The spectrum of these unitary super-Landau
models is determined. The M=0 case yields a unitary Landau model on the
supersphere SU(2|1)/U(1|1) with U(1) charge 2N=2N'+1. For the generic unitary
superflag model, the manifest SU(2|1) symmetry is dynamically enhanced to
SU(2|2); this is the `spherical' analog of the hidden worldline supersymmetry
found previously in the planar limit.

categories: hep-th cond-mat.mes-hall math-ph math.MP


title: Promotion and Evacuation

abstract:
  Promotion and evacuation are bijections on the set of linear extensions of a
finite poset first defined by Schutzenberger. This paper surveys the basic
properties of these two operations and discusses some generalizations.


title:
Long Range Correlations and the Soft Ridge in Relativistic Nuclear
  Collisions

abstract:
  Relativistic Heavy Ion Collider experiments exhibit correlations peaked in
relative azimuthal angle and extended in rapidity. Called the ridge, this peak
occurs both with and without a jet trigger. We argue that the untriggered ridge
arises when particles formed by flux tubes in an early glasma stage later
manifest transverse flow. Combining a blast wave model of flow fixed by
single-particle spectra with a simple description of the glasma, we find
excellent agreement with current data.


title: Spin effects in single electron tunneling

abstract:
  An important consequence of the discovery of giant magnetoresistance in
metallic magnetic multilayers is a broad interest in spin dependent effects in
electronic transport through magnetic nanostructures. An example of such
systems are tunnel junctions -- single-barrier planar junctions or more complex
ones. In this review we present and discuss recent theoretical results on
electron and spin transport through ferromagnetic mesoscopic junctions
including two or more barriers. Such systems are also called ferromagnetic
single-electron transistors. We start from the situation when the central part
of a device has the form of a magnetic (or nonmagnetic) metallic nanoparticle.
Transport characteristics reveal then single-electron charging effects,
including the Coulomb staircase, Coulomb blockade, and Coulomb oscillations.
Single-electron ferromagnetic transistors based on semiconductor quantum dots
and large molecules (especially carbon nanotubes) are also considered. The main
emphasis is placed on the spin effects due to spin-dependent tunnelling through
the barriers, which gives rise to spin accumulation and tunnel
magnetoresistance. Spin effects also occur in the current-voltage
characteristics, (differential) conductance, shot noise, and others. Transport
characteristics in the two limiting situations of weak and strong coupling are
of particular interest. In the former case we distinguish between the
sequential tunnelling and cotunneling regimes. In the strong coupling regime we
concentrate on the Kondo phenomenon, which in the case of transport through
quantum dots or molecules leads to an enhanced conductance and to a pronounced
zero-bias Kondo peak in the differential conductance.


title: Entropy Limit and the Cold Feedback Mechanism in Cooling Flow Clusters

abstract:
  I propose an explanation to the finding that star formation and visible
filaments strong in Halpha emission in cooling flow clusters occur only if the
minimum specific entropy and the radiative cooling time of the intracluster
medium (ICM), are below a specific threshold. The explanation is based on the
cold feedback mechanism. In this mechanism the mass accreted by the central
black hole originates in non-linear over-dense blobs of gas residing in an
extended region of the cooling flow region. I use the criterion that the
feedback cycle period must be longer than the radiative cooling time of dense
blobs for large quantities of gas to cool to low temperature. The falling time
of the dense blobs is parameterized by the ratio of the infall velocity to the
sound speed. Another parameter is the ratio of the blobs' density to that of
the surrounding ICM. By taking the values of the parameters as in previous
papers on the cold feedback model, I derive an expression that gives the right
value of the entropy threshold. Future studies will have to examine in more
detail the role of these parameters, and to show that the observed sharp change
in the behavior of clusters across the entropy, or radiative cooling time,
threshold can be reproduced by the model.


title:
First Order Conditions for Semidefinite Representations of Convex Sets
  Defined by Rational or Singular Polynomials

abstract:
  A set is called semidefinite representable or semidefinite programming (SDP)
representable if it can be represented as the projection of a higher
dimensional set which is represented by some Linear Matrix Inequality (LMI).
This paper discuss the semidefinite representability conditions for convex sets
of the form S_D(f) = {x \in D: f(x) >= 0}. Here D={x\in R^n: g_1(x) >= 0, ...,
g_m(x) >= 0} is a convex domain defined by some "nice" concave polynomials
g_i(x) (they satisfy certain concavity certificates), and f(x) is a polynomial
or rational function. When f(x) is concave over \mc{D}, we prove that S_D(f)
has some explicit semidefinite representations under certain conditions called
preordering concavity or q-module concavity, which are based on the
Positivstellensatz certificates for the first order concavity criteria. When
f(x) is a polynomial or rational function having singularities on the boundary
of S_D(f), a perspective transformation is introduced to find some explicit
semidefinite representations for S_D(f) under certain conditions. In the
particular case n=2, if the Laurent expansion of f(x) around one singular point
has only two consecutive homogeneous parts, we show that S_D(f) always admits
an explicitly constructible semidefinite representation.


title: Malleable Coding: Compressed Palimpsests

abstract:
  A malleable coding scheme considers not only compression efficiency but also
the ease of alteration, thus encouraging some form of recycling of an old
compressed version in the formation of a new one. Malleability cost is the
difficulty of synchronizing compressed versions, and malleable codes are of
particular interest when representing information and modifying the
representation are both expensive. We examine the trade-off between compression
efficiency and malleability cost under a malleability metric defined with
respect to a string edit distance. This problem introduces a metric topology to
the compressed domain. We characterize the achievable rates and malleability as
the solution of a subgraph isomorphism problem. This can be used to argue that
allowing conditional entropy of the edited message given the original message
to grow linearly with block length creates an exponential increase in code
length.


title: Simple d=4 supergravity with a boundary

abstract:
  To construct rigidly or locally supersymmetric bulk-plus-boundary actions,
one needs an extension of the usual tensor calculus. Its key ingredients are
the extended (F-, D-, etc.) density formulas and the rule for the decomposition
of bulk multiplets into (co-dimension one) boundary multiplets. Working out
these ingredients for d=4 N=1 Poincar\'e supergravity, we discover the special
role played by R-symmetry (absent in the d=3 N=1 case we studied previously).
The $U(1)_A$ R-symmetry has to be gauged which leads us to extend the
old-minimal set of auxiliary fields S, P, A_\mu by a $U(1)_A$ compensator $a$.
Our results include the ``F+A'' density formula, the ``Q+L+A'' formula for the
induced supersymmetry transformations (closing into the standard d=3 N=1
algebra) and demonstration that the compensator $a$ is the first component of
the extrinsic curvature multiplet. We rely on the superconformal approach which
allows us to perform, in parallel, the same analysis for new-minimal
supergravity.


title:
Observation of inter-Landau-level quantum coherence in semiconductor
  quantum wells

abstract:
  Using three-pulse four-wave-mixing femtosecond spectroscopy, we excite a
non-radiative coherence between the discrete Landau levels of an undoped
quantum well and study its dynamics. We observe quantum beats that reflect the
time evolution of the coherence between the two lowest Landau level
magnetoexcitons. We interpret our observations using a many-body theory and
find that the inter Landau level coherence decays with a new time constant,
substantially longer than the corresponding interband magnetoexciton dephasing
times. Our results indicate a new intraband excitation dynamics that cannot be
described in terms of uncorrelated interband excitations.


title: Role of quantum coherence in chromophoric energy transport

abstract:
  The role of quantum coherence and the environment in the dynamics of
excitation energy transfer is not fully understood. In this work, we introduce
the concept of dynamical contributions of various physical processes to the
energy transfer efficiency. We develop two complementary approaches, based on a
Green's function method and energy transfer susceptibilities, and quantify the
importance of the Hamiltonian evolution, phonon-induced decoherence, and
spatial relaxation pathways. We investigate the Fenna-Matthews-Olson protein
complex, where we find a contribution of coherent dynamics of about 10% and of
relaxation of 80%.


title:
Quantum oscillations in the parent magnetic phase of an iron arsenide
  high temperature superconductor

abstract:
  We report quantum oscillation measurements in SrFe2As2 - which is an
antiferromagnetic parent of the iron-arsenide family of superconductors - known
to become superconducting under doping and the application of pressure. The
magnetic field and temperature dependences of the oscillations between 20 and
55 T in the liquid helium temperature range suggest that the electronic
excitations are those of a Fermi liquid. We show that the observed Fermi
surface comprising small pockets is consistent with the formation of a
spin-density wave. Our measurements thus demonstrate that high Tc
superconductivity can occur on doping or pressurizing a conventional metallic
spin-density wave state.


title: Non-axisymmetric instability of axisymmetric magnetic fields

abstract:
  The MHD instabilities can generate complex field topologies even if the
initial field configuration is a very simple one. We consider the stability
properties of magnetic configurations containing a toroidal and an axial field.
In this paper, we concentrate mainly on the behavior of non-axisymmetric
perturbations in axisymmetric magnetic configurations. The stability is treated
by a linear analysis of ideal MHD equations.In the presence of an axial field,
it is shown that the instability can occur for a wide range of the azimuthal
wavenumber $m$, and its growth rate increases with increasing $m$. At given
$m$, the growth rate is at its maximum for perturbations with the axial
wave-vector that makes the Alfv\'en frequency approximately vanishing. We argue
that the instability of magnetic configurations in the ideal MHD can typically
be dominated by perturbations with very short azimuthal and axial wavelengths.


title: A version of smooth K-theory adapted to the total Chern class

abstract:
  A version of smooth K-theory is constructed, which is adapted to the total
Chern class instead of the Chern character (contrarily to previous theories).
Some total Chern class morphism from this K-theory to Cheeger-Simons
differential characters is constructed. This answers a question raised by U.
Bunke.


title: Dosimetry, scattering theory, and Monte Carlo simulation

abstract:
  The purpose of this paper is to provide an introduction to the physics of
scattering theory, to define the dosimetric concept of linear energy transfer
in terms of scattering theory, and to provide an introduction to the concepts
underlying Monte Carlo simulations.


title:
Improving Point and Interval Estimates of Monotone Functions by
  Rearrangement

abstract:
  Suppose that a target function is monotonic, namely, weakly increasing, and
an available original estimate of this target function is not weakly
increasing. Rearrangements, univariate and multivariate, transform the original
estimate to a monotonic estimate that always lies closer in common metrics to
the target function. Furthermore, suppose an original simultaneous confidence
interval, which covers the target function with probability at least
$1-\alpha$, is defined by an upper and lower end-point functions that are not
weakly increasing. Then the rearranged confidence interval, defined by the
rearranged upper and lower end-point functions, is shorter in length in common
norms than the original interval and also covers the target function with
probability at least $1-\alpha$. We demonstrate the utility of the improved
point and interval estimates with an age-height growth chart example.


title: Dynamical Regimes Induced by Spin Transfer in Magnetic Nanopillars

abstract:
  We demonstrate the predicted out-of-plane precession induced by spin transfer
in magnetic nanostructures with in-plane magnetic field. We show that other
magnetic excitations have a significant effect on the stability of the out-of
plane precession, making it extremely sensitive to the orientation of the
applied magnetic field. The data are supported with micromagnetic simulations.
Our results elucidate the relation between the excitation spectrum and the
specific dynamical behaviors of nanoscale magnets.


title: On the strength of Hausdorff's gap condition

abstract:
  Hausdorff's gap condition was satisfied by his original 1936 construction of
an (omega-1,omega-1) gap in P(N)/Fin. We solve an open problem in determining
whether Hausdorff's condition is actually stronger than the more modern
indestructibility condition, by constructing an indestructible
(omega-1,omega-1) gap not equivalent to any gap satisfying Hausdorff's
condition, from uncountably many random reals.


title: Current Correlators for General Gauge Mediation

abstract:
  In the gauge mediation mechanism, the effects of the hidden sector are
characterized by a set of correlation functions of the global symmetry current
of the hidden sector. We present methods to compute these correlators in cases
with strongly coupled hidden sectors. Several examples are presented to
demonstrate the technique explicitly.


title: Defects and D-Brane Monodromies

abstract:
  In this paper D-brane monodromies are studied from a world-sheet point of
view. More precisely, defect lines are used to describe the parallel transport
of D-branes along deformations of the underlying bulk conformal field theories.
This method is used to derive B-brane monodromies in Kahler moduli spaces of
non-linear sigma models on projective hypersurfaces. The corresponding defects
are constructed at Landau-Ginzburg points in these moduli spaces where matrix
factorisation techniques can be used. Transporting them to the large volume
phase by means of the gauged linear sigma model we find that their action on
B-branes at large volume can be described by certain Fourier-Mukai
transformations which are known from target space geometric considerations to
represent the corresponding monodromies.


title:
Linear Time Algorithms for Finding a Dominating Set of Fixed Size in
  Degenerated Graphs

abstract:
  There is substantial literature dealing with fixed parameter algorithms for
the dominating set problem on various families of graphs. In this paper, we
give a $k^{O(dk)} n$ time algorithm for finding a dominating set of size at
most $k$ in a $d$-degenerated graph with $n$ vertices. This proves that the
dominating set problem is fixed-parameter tractable for degenerated graphs. For
graphs that do not contain $K_h$ as a topological minor, we give an improved
algorithm for the problem with running time $(O(h))^{hk} n$. For graphs which
are $K_h$-minor-free, the running time is further reduced to $(O(\log
h))^{hk/2} n$. Fixed-parameter tractable algorithms that are linear in the
number of vertices of the graph were previously known only for planar graphs.
  For the families of graphs discussed above, the problem of finding an induced
cycle of a given length is also addressed. For every fixed $H$ and $k$, we show
that if an $H$-minor-free graph $G$ with $n$ vertices contains an induced cycle
of size $k$, then such a cycle can be found in O(n) expected time as well as in
$O(n \log n)$ worst-case time. Some results are stated concerning the
(im)possibility of establishing linear time algorithms for the more general
family of degenerated graphs.


title:
Universal doping dependence of the ground state staggered magnetization
  in cuprates

abstract:
  Using muon spin rotation we determine the zero temperature staggered
antiferromagnetic order parameter M0 versus hole doping measured from optimum
Dp_m, in the (Ca_{x}La_{1-x})(Ba_{1.75-x}La_{0.25+x})Cu_{3}O_{y} system. In
this system the maximum Tc and the superexchange J vary by 30% between families
(x). M0(x,Dp_m) is found to be x-independent. Using neutron diffraction we also
determine the lattice parameters variations for all x and doping. The oxygen
buckling angle is found to change with x, implying a change in the holes
kinetic energy. We discuss the surprising insensitivity of M0(x,Dp_m) to the
kinetic energy variations in the framework of the t-J model.


title:
On the Multiplexing Gain of K-user Partially Connected Interference
  Channel

abstract:
  The multiplexing gain (MUXG) of $K$-user interference channel (IC) with
partially connected interfering links is analyzed. The motivation for the
partially connected IC comes from the fact that not all interferences are
equally strong in practice. The MUXG is characterized as a function of the
number ($K$) of users and the number ($N \geq 1$) of interfering links. Our
analysis is mainly based on the interference alignment (IA) technique to
mitigate interference. Our main results are as follows: One may expect that
higher MUXG can be attained when some of interfering links do not exist.
However, when $N$ is odd and $K=N+2$, the MUXG is not increased beyond the
optimal MUXG of fully connected IC, which is $\frac{KM}{2}$. The number of
interfering links has no influence on the achievable MUXG using IA, but affects
the efficiency in terms of the number of required channel realizations: When
N=1 or 2, the optimal MUXG of the fully connected IC is achievable with a
finite number of channel realizations. In case of $N \geq 3$, however, the MUXG
of $\frac{KM}{2}$ can be achieved asymptotically as the number of channel
realizations tends to infinity.


title: A Cellular Automaton Model of Pulsar Glitches

abstract:
  A cellular automaton model of pulsar glitches is described, based on the
superfluid vortex unpinning paradigm. Recent analyses of pulsar glitch data
suggest that glitches result from scale-invariant avalanches
\citep{Melatos07a}, which are consistent with a self-organized critical system
(SOCS). A cellular automaton provides a computationally efficient means of
modelling the collective behaviour of up to $10^{16}$ vortices in the pulsar
interior, whilst ensuring that the dominant aspects of the microphysics are not
lost. The automaton generates avalanche distributions that are qualitatively
consistent with a SOCS and with glitch data. The probability density functions
of glitch sizes and durations are power laws, and the probability density
function of waiting times between successive glitches is Poissonian, consistent
with statistically independent events. The output of the model depends on the
physical and computational paramters used. The fitted power law exponents for
the glitch sizes ($a$) and durations ($b$) decreases as the strength of the
vortex pinning increases. Similarly the exponents increase as the fraction of
vortices that are pinned decreases. For the physical and computational
parameters considered, one finds $-4.3\leq a \leq -2.0$ and $-5.5\leq b\leq
-2.2$, and mean glitching rates in the range $0.0023\leq\lambda\leq0.13\$ in
units of inverse time.


title: The muon charge ratio in cosmic ray air showers

abstract:
  The muon charge ratio of the lateral muon density distributions in single EAS
is studied by simulations, in context of recent proposals to measure this
observable in coincidence with EAS observations. While effects of the hadronic
interaction do not lead to significant differences of the total muon plus and
muon minus content, the differences of the azimuthal variation of the muon
densities of opposite charges and the azimuthal variation of the muon charge
ratio appear to be very much pronounced, dependent on the direction of EAS
incidence. This is due to the influence of the geomagnetic field which induces
related effects in radio emission from extended air showers.


title: Formation of water and methanol in star forming molecular clouds

abstract:
  We study the formation of water and methanol in the dense cloud conditions to
find the dependence of its production rate on the binding energies, reaction
mechanisms, temperatures, and grain site number. We wish to find the effective
grain surface area available for chemical reaction and the effective
recombination timescales as functions of grain and gas parameters. We used a
Monte Carlo simulation to follow the chemical processes occurring on the grain
surface. We find that the formation rate of various molecules is strongly
dependent on the binding energies. When the binding energies are high, it is
very difficult to produce significant amounts of the molecular species.
Instead, the grain is found to be full of atomic species. The production rates
are found to depend on the number density in the gas phase. We show that the
concept of the effective grain surface area, which we introduced in our earlier
work, plays a significant role in grain chemistry. We compute the abundance of
water and methanol and show that the results strongly depend on the density and
composition in the gas phase, as well as various grain parameters. In the rate
equation, it is generally assumed that the recombination efficiencies are
independent of the grain parameters, and the surface coverage. Presently, our
computed parameter $\alpha$ for each product is found to depend on the
accretion rate, the grain parameters and the surface coverage of the grain. We
compare our results obtained from the rate equation and the one from the
effective rate equation, which includes $\alpha$. At the end we compare our
results with the observed abundances.


title: The deformation quantizations of the hyperbolic plane

abstract:
  We describe the space of (all) invariant deformation quantizations on the
hyperbolic plane as solutions of the evolution of a second order hyperbolic
differential operator. The construction is entirely explicit and relies on
non-commutative harmonic analytical techniques on symplectic symmetric spaces.
The present work presents a unified method producing every quantization of the
hyperbolic plane, and provides, in the 2-dimensional context, an exact solution
to Weinstein's WKB quantization program within geometric terms. The
construction reveals the existence of a metric of Lorentz signature canonically
attached (or `dual') to the geometry of the hyperbolic plane through the
quantization process.


title:
On the empirical evidence for the existence of ultra-massive white
  dwarfs

abstract:
  We re-examine the evidence for the existence of ultra-massive (M > 1.1 M_sun)
white dwarfs based on gravitational redshift of white dwarfs in common proper
motion binaries or in clusters, on parallax measurements, on orbital solutions,
and, finally, on the analysis of hydrogen line profiles. We conclude that the
best evidence is largely based on the analysis of Balmer line profiles although
the companion to the A8V star HR 8210 is a compelling case made initially using
the large binary mass function and confirmed by an analysis of the Lyman line
spectrum. The confirmation and identification of high-mass white dwarfs, more
particularly non-DA white dwarfs, using parallax measurements may prove
critical in establishing the population fraction of these objects and in
constraining the high-end of empirical initial-mass to final-mass relations.
The existence of a substantial population of ultra-massive white dwarfs
supports the concept of a steeper initial-mass to final-mass relations linking
6 M_sun progenitors with approximately greater than 1.1 M_sun white dwarfs.


title:
On the classification of complex Leibniz superalgebras with
  characteristic sequence $(n-1, 1 | m_1, ..., m_k)$ and nilindex $n+m$

abstract:
  In this work we investigate the complex Leibniz superalgebras with
characteristic sequence $(n-1, 1 | m_1, ..., m_k)$ and with nilindex equal to
$n+m.$ We prove that such superalgebras with the condition $m_2\neq0$ have
nilindex less than $n+m$. Therefore the complete classification of Leibniz
algebras with characteristic sequence $(n-1, 1 | m_1, ..., m_k)$ and with
nilindex equal to $n+m$ is reduced to the classification of filiform Leibniz
superalgebras of nilindex equal to $n+m,$ which was provided in \cite{AOKh} and
\cite{GKh}.


title:
Nucleon sigma term and strange quark content from lattice QCD with exact
  chiral symmetry

abstract:
  We calculate the nucleon sigma term in two-flavor lattice QCD utilizing the
Feynman-Hellman theorem. Both sea and valence quarks are described by the
overlap fermion formulation, which preserves exact chiral and flavor symmetries
on the lattice. We analyse the lattice data for the nucleon mass using the
analytical formulae derived from the baryon chiral perturbation theory. From
the data at valence quark mass set different from sea quark mass, we may
extract the sea quark contribution to the sigma term, which corresponds to the
strange quark content. We find that the strange quark content is much smaller
than the previous lattice calculations and phenomenological estimates.


title: Bulk viscosity in quasi particle models

abstract:
  We discuss transport properties of dynamical fluid composed of
quasi-particles whose masses depend on temperature and charge chemical
potentials. Based on the relativistic kinetic theory formulated under the
relaxation time approximation, we derive a general expression for the bulk
viscosity in the quasi-particle medium. We show that dynamically generated
particle masses imply an essential modification of the fluid compressibility.
As an application of our results we consider a class of quasi-particle models
with the chiral phase transition belonging to O(4) and Z(2) universality class.
Based on the Ginzburg-Landau and the scaling theory we study the critical
properties of the bulk viscosity zeta near the phase transition. We show that
under the relaxation time approximation the zeta is not expected to show
singular behavior near the O(4) and Z(2) critical point through static critical
exponents.


title: Concept-Oriented Programming

abstract:
  Object-oriented programming (OOP) is aimed at describing the structure and
behaviour of objects by hiding the mechanism of their representation and access
in primitive references. In this article we describe an approach, called
concept-oriented programming (COP), which focuses on modelling references
assuming that they also possess application-specific structure and behaviour
accounting for a great deal or even most of the overall program complexity.
References in COP are completely legalized and get the same status as objects
while the functions are distributed among both objects and references. In order
to support this design we introduce a new programming construct, called
concept, which generalizes conventional classes and concept inclusion relation
generalizing class inheritance. The main advantage of COP is that it allows
programmers to describe two sides of any program: explicitly used functions of
objects and intermediate functionality of references having cross-cutting
nature and executed implicitly behind the scenes during object access.


title:
Estimates for parameters and characteristics of the confining
  SU(3)-gluonic field in the ground state of toponium: Relativistic and
  nonrelativistic approaches

abstract:
  The confinement mechanism earlier proposed by author is applied to describe
the (possible) ground state of toponium $\eta_t$. For this aim the
nonperturbative consistent approach is elaborated in both relativistic and
nonrelativistic cases. The study entails estimates for parameters of the
confining SU(3)-gluonic field in the above quarkonium, those estimates being
also consistent with possible width of decay $\eta_t\to2\gamma$. The
corresponding estimates of the gluon concentrations, electric and magnetic
colour field strengths are also adduced for the mentioned field at the scales
of toponium.


title: Magnetized orbifold models

abstract:
  We study (4+2n)-dimensional N=1 super Yang-Mills theory on the orbifold
background with non-vanishing magnetic flux. In particular, we study zero-modes
of spinor fields. The flavor structure of our models is different from one in
magnetized torus models, and would be interesting in realistic model building.


title: Nested Ordered Sets and their Use for Data Modelling

abstract:
  In this paper we present a new approach to data modelling, called the
concept-oriented model (CoM), and describe its main features and
characteristics including data semantics and operations. The distinguishing
feature of this model is that it is based on the formalism of nested ordered
sets where any element participates in two structures simultaneously:
hierarchical (nested) and multi-dimensional (ordered). An element of the model
is postulated to consist of two parts, called identity and entity, and the
whole approach can be naturally broken into two branches: identity modelling
and entity modelling. We also propose a new query language with the main
construct, called concept, defined as a pair of two classes: identity class and
entity class. We describe how its operations of projection, de-projection and
product can be used to solve typical data modelling tasks.


title:
Ab initio Derivation of Low-energy Model for Iron-Based Superconductors
  LaFeAsO and LaFePO

abstract:
  Effective Hamiltonians for LaFeAsO and LaFePO are derived from the
downfolding scheme based on first-principles calculations and provide insights
for newly discovered superconductivity in the family of LnFeAsO$_{1-x}$F$_x$,
Ln = La, Ce, Pr, Nd, Sm, and Gd. Extended Hubbard Hamiltonians for five
maximally localized Wannier orbitals per Fe are constructed dominantly from
five-fold degenerate iron-3$d$ bands. They contain parameters for effective
Coulomb and exchange interactions screened by the polarization of other
electrons away from the Fermi level. The onsite Coulomb interaction estimated
as 2.2-3.3 eV is compared with the transfer integrals between the
nearest-neighbor Fe-3$d$ Wannier orbitals, 0.2-0.3 eV, indicating moderately
strong electron correlation. The Hund's rule coupling is found to be 0.3-0.6
eV. The derived model offers a firm basis for further studies on physics of
this family of materials. The effective models for As and P compounds turn out
to have very similar screened interactions with slightly narrower bandwidth for
the As compound.


title: Feynman graphs and renormalization in quantum diffusion

abstract:
  We review our proof that in a scaling limit, the time evolution of a quantum
particle in a static random environment leads to a diffusion equation. In
particular, we discuss the role of Feynman graph expansions and of
renormalization.


title:
An alternative calculation of the Casimir forces between birefringent
  plates

abstract:
  Barash has calculated the Casimir forces between parallel birefringent plates
with optical axes parallel to the plate boundaries [Izv. Vyssh. Uchebn.\
Zaved., Radiofiz., {\bf 12}, 1637 (1978)]. The interesting new feature of the
solution compared to the case of isotropic plates is the existence of a Casimir
torque which acts to line up the optical axes if they are not parallel or
perpendicular. The forces were found from a calculation of the Helmholtz free
energy of the electromagnetic field. Given the length of the calculations in
this problem and hopes of an experimental measurement of the torque, it is
important to check the results for the Casimir forces by a different method. We
provide this check by calculating the electromagnetic stress tensor between the
plates and showing that the resulting forces are in agreement with those found
by Barash.


title: Spin relaxation of localized electrons in n-type semiconductors

abstract:
  The mechanisms that determine spin relaxation times of localized electrons in
impurity bands of n-type semiconductors are considered theoretically and
compared with available experimental data. The relaxation time of the
non-equilibrium angular momentum is shown to be limited either by hyperfine
interaction, or by spin-orbit interaction in course of exchange-induced spin
diffusion. The energy relaxation time in the spin system is governed by
phonon-assisted hops within pairs of donors with an optimal distance of about 4
Bohr radii. The spin correlation time of the donor-bound electron is determined
either by exchange interaction with other localized electrons, or by spin-flip
scattering of free conduction-band electrons. A possibility of optical cooling
of the spin system of localized electrons is discussed.


title:
Avoiding entanglement sudden-death via measurement feedback control in a
  quantum network

abstract:
  In this paper, we consider a linear quantum network composed of two distantly
separated cavities that are connected via a one-way optical field. When one of
the cavity is damped and the other is undamped, the overall cavity state
obtains a large amount of entanglement in its quadratures. This entanglement
however immediately decays and vanishes in a finite time. That is, entanglement
sudden-death occurs. We show that the direct measurement feedback method
proposed by Wiseman can avoid this entanglement sudden-death, and further,
enhance the entanglement. It is also shown that the entangled state under
feedback control is robust against signal loss in a realistic detector,
indicating the reliability of the proposed direct feedback method in practical
situations.


title:
Analysis of regular inflationary cosmological models with two torsion
  functions in Poincare gauge theory of gravity

abstract:
  Analysis of regular inflationary cosmological models with two torsion
functions filled with scalar field with quadratic potential and
ultrarelativistic matter is carried out numerically. Properties of different
stages of regular inflationary cosmological solutions are studied, restrictions
on admissible values of parameters and initial conditions at transition from
compression to expansion are found. The structure of extremum surface in space
of physical variables is investigated.


title:
Practical schemes for the measurement of angular-momentum covariance
  matrices in quantum optics

abstract:
  We develop practical schemes for the measurement of the covariance matrix for
intrinsic angular-momentum variables in quantum optics. We particularize this
approach to two-beam polarimetry and interferometry, as well as to ensembles of
two-level atoms interacting with classical fields. We show the practical
advantages of noisy simultaneous measurements.


title:
A Computational Study of the Dynamics of the Critical Points in a Simple
  Fluid Flow

abstract:
  We carry out a computational experiment inspired by a physical experiment by
Ouellette and Gollub (PRL 99, 194502 (2007)) where a topological transition of
the velocity field in a fluid flow is generated by a grid of magnets. At a
well-defined Reynolds number Re the motion of the stagnation points becomes so
strong that they may merge and annihilate. Replacing the magnets by a grid of
stirrers we obtain the same essential features of the transition, but the
resolution allows us to identify two different stages of the process: A range
of Re where the annihilation rate of the stagnation points is low but non-zero
is followed by a narrow interval where the rate jumps to a high level.


title: Quantum corrections to energy of short spinning string in AdS5

abstract:
  Motivated by desire to shed light on the strong coupling behaviour of
anomalous dimensions of "short" gauge theory operators we consider the famous
example of folded spinning string in AdS_5 in the limit of small semiclassical
spin parameter \S = S/sqrt[lambda]. In this limit the string becomes short and
is moving in a near-flat central region of AdS_5. Its energy scales with spin
as E = sqrt[2 S] [ a_0 + a_1 S + a_2 S^2 + ...]. We explicitly compute the
leading 1-loop quantum AdS_5 x S^5 superstring corrections to the short-string
limit coefficients a_0 and a_1 and show, in particular, that a_1 receives a
contribution containing \zeta(3).


title:
Non-Markovian shot noise spectrum of quantum transport through quantum
  dots

abstract:
  The generalized quantum master equation with transport particle number
resolution, like its conventional unconditioned counterpart, has also the
time-local and time-nonlocal prescriptions.The latter is found to be more
suitable for the effect of electrodes bandwidth on quantum transport and noise
spectrum for weak system-reservoir coupling, as calibrated with the exact
results in the absence of Coulomb interaction. We further analyze the effect of
Coulomb interaction on the noise spectrum of transport current through quantum
dot systems, and show that the realistic finite Coulomb interaction and finite
bandwidth are manifested only with non-Markovian treatment. We demonstrate a
number of non-Markovian characteristics of shot noise spectrum, including that
due to finite bandwidth and that sensitive to and enhanced by the magnitude of
Coulomb interaction.


title: Reasonable non--Radon--Nikodym ideals

abstract:
  For any abelian Polish sigma-compact group H there exist a sigma-ideal Z over
N and a Borel Z-approximate homomorphism f : H --> H^N which is not
Z-approximable by a continuous true homomorphism g : H --> H^N.


title:
About the almost everywhere convergence of the spectral expansions of
  functions from $L_1^\a(S^N)$

abstract:
  In this paper we study the almost everywhere convergence of the expansions
related to the self-adjoint extension of the Laplace-Beltrami operator on the
unit sphere. The sufficient conditions for summability is obtained. The more
general properties and representation by the eigenfunctions of the
Laplace-Beltrami operator of the Liouville space $L_1^\a$ is used.
  For the orders of Riesz means, which greater than critical index
$\frac{N-1}{2}$ we proved the positive results on summability of
Fourier-Laplace series. Note that when order $\alpha$ of Riesz means is less
than critical index then for establish of the almost everywhere convergence
requests to use other methods form proving negative results. We have
constructed different method of summability of Laplace series, which based on
spectral expansions property of self-adjoint Laplace-Beltrami operator on the
unit sphere.


title:
Velocity gradients statistics along particle trajectories in turbulent
  flows: the refined similarity hypothesis in the Lagrangian frame

abstract:
  We present an investigation of the statistics of velocity gradient related
quantities, in particluar energy dissipation rate and enstrophy, along the
trajectories of fluid tracers and of heavy/light particles advected by a
homogeneous and isotropic turbulent flow. The Refined Similarity Hypothesis
(RSH) proposed by Kolmogorov and Oboukhov in 1962 is rephrased in the
Lagrangian context and then tested along the particle trajectories. The study
is performed on state-of-the-art numerical data resulting from numerical
simulations up to Re~400 with 2048^3 collocation points. When particles have
small inertia, we show that the Lagrangian formulation of the RSH is well
verified for time lags larger than the typical response time of the particle.
In contrast, in the large inertia limit when the particle response time
approaches the integral-time-scale of the flow, particles behave nearly
ballistic, and the Eulerian formulation of RSH holds in the inertial-range.