title:
Hadron Correlation in Jets on the Near and Away Sides of High-p_T
  Triggers in Heavy-ion Collisions

abstract:
  Correlation between trigger and associated particles in jets produced on near
and away sides of high-p_T triggers in heavy-ion collisions is studied.
Hadronization of jets on both sides is treated by thermal-shower and
shower-shower recombination. Energy loss of semihard and hard partons
traversing the nuclear medium is parametrized in a way that renders good fit of
the single-particle inclusive distributions at all centralities. The associated
hadron distribution in the near-side jet can be determined showing weak
dependence on system size because of trigger bias. The inverse slope increases
with trigger momentum in agreement with data. The distribution of associated
particle in the away-side jet is also studied with careful attention given to
antitrigger bias that is due to the longer path length that the away-side jet
recoiling against the trigger jet must propagate in the medium to reach the
opposite side. Centrality dependence is taken into account after determining a
realistic probability distribution of the dynamical path length of the parton
trajectory within each class of centrality. For symmetric dijets with
p_T^{trig}=p_T^{assoc}(away) it is shown that the per-trigger yield is
dominated by tangential jets. The average parton momentum for the recoil jet is
shown to be always larger than that of the trigger jet for fixed p_T^{trig} and
centrality and for any measurable p_T^{assoc}(away). With the comprehensive
treatment of dijet production described here it is possible to answer many
questions regarding the behavior of partons in the medium under conditions that
can be specified on measurable hadron momenta.


title: On the dark energy rest frame and the CMB

abstract:
  Dark energy is usually parametrized as a perfect fluid with negative pressure
and a certain equation of state. Besides, it is supposed to interact very
weakly with the rest of the components of the universe and, as a consequence,
there is no reason to expect it to have the same large-scale rest frame as
matter and radiation. Thus, apart from its equation of state $w$ and its energy
density $\Omega_{DE}$ one should also consider its velocity as a free parameter
to be determined by observations. This velocity defines a cosmological
preferred frame, so the universe becomes anisotropic and, therefore, the CMB
temperature fluctuations will be affected, modifying mainly the dipole and the
quadrupole.


title: Cosmic polarimetry in magnetoactive plasmas

abstract:
  Polarimetry of the Cosmic Microwave Background (CMB) represents one of the
possible diagnostics aimed at testing large-scale magnetism at the epoch of the
photon decoupling. The propagation of electromagnetic disturbances in a
magnetized plasma leads naturally to a B-mode polarization whose angular power
spectrum is hereby computed both analytically and numerically. Combined
analyses of all the publicly available data on the B-mode polarization are
presented, for the first time, in the light of the magnetized $\Lambda$CDM
scenario. Novel constraints on pre-equality magnetism are also derived in view
of the current and expected sensitivities to the B-mode polarization.


title: Spin-polarized high-energy scattering of charged leptons on nucleons

abstract:
  The proton is a composite object with spin one-half, understood to contain
highly relativistic spin one-half quarks exchanging spin-one gluons, each
possibly with significant orbital angular momenta. While their fundamental
interactions are well described by Quantum ChromoDynamics (QCD), our standard
theory of the strong interaction, nonperturbative calculations of the internal
structure of the proton based directly on QCD are beginning to provide reliable
results. Most of our present knowledge of the structure of the proton is based
on experimental measurements interpreted within the rich framework of QCD. An
area presently attracting intense interest, both experimental and theoretical,
is the relationship between the spin of the proton and the spins and orbital
angular momenta of its constituents. While remarkable progress has been made,
especially in the last decade, the discovery and investigation of new concepts
have revealed that much more remains to be learned. This progress is reviewed
and an outlook for the future is offered.


title: Frequency-dependent Drude damping in Casimir force calculations

abstract:
  The Casimir force is calculated between Au thin films that are described by a
Drude model with a frequency dependent damping function. The model parameters
are obtained from available experimental data for Au thin films. Two cases are
considered; annealed and nonannealed films that have a different damping
function. Compared with the calculations using a Drude model with a constant
damping parameter, we observe changes in the Casimir force of a few percent.
This behavior is only observed in films of no more than 300 $\AA$ thick.


title: Interacting models may be key to solve the cosmic coincidence problem

abstract:
  It is argued that cosmological models that feature a flow of energy from dark
energy to dark matter may solve the coincidence problem of late acceleration
(i.e., "why the energy densities of both components are of the same order
precisely today?"). However, much refined and abundant observational data of
the redshift evolution of the Hubble factor are needed to ascertain whether
they can do the job.


title:
Unifying the study of background dynamics and perturbations in
  $f(R)$-gravity

abstract:
  In this paper we show how the covariant gauge invariant equations for the
evolution of scalar, vector and tensor perturbations for a generic
$f(R)$-gravity theory can be recast in order to exploit the power of dynamical
system methodology. In this way, recent results describing the dynamics of the
background FRW model can be easily combined with these equations to reveal
important details pertaining to the evolution of cosmological models in fourth
order gravity.


title: Intense Atomic and Molecular Beams via Neon Buffer Gas Cooling

abstract:
  We realize a continuous guided beam of cold deuterated ammonia with a flux of
3e11 ND3 molecules/s and a continuous free-space beam of cold potassium with a
flux of 1e16 K atoms/s. A novel feature of the buffer gas source used to
produce these beams is cold neon, which, due to intermediate Knudsen number
beam dynamics, produces a forward velocity and low-energy tail that is
comparable to much colder helium-based sources. We expect this source to be
trivially generalizable to a very wide range of atomic and molecular species
with significant vapor pressure below 1000 K. This source has properties that
make it a good starting point for laser cooling of molecules or atoms, cold
collision studies, trapping, or nonlinear optics in buffer-gas-cooled atomic or
molecular gases.


title: Pull-in control in microswitches using acoustic Casimir forces

abstract:
  In this paper we present a theoretical calculation of the acoustic Casimir
pressure in a model micro system. Unlike the quantum case, the acoustic Casimir
pressure can be made attractive or repulsive depending on the frequency
bandwidth of the acoustic noise. As a case study, a one degree of freedom
simple-lumped system in an acoustic resonant cavity is considered. We show that
the frequency bandwidth of the acoustic field can be tuned to increase the
stability in existing microswitch systems by selecting the sign of the force.
The acoustic intensity and frequency bandwidth are introduced as two additional
control parameters of the microswitch.


title: Fractal Structure of Loop Quantum Gravity

abstract:
  In this paper we have calculated the spectral dimension of loop quantum
gravity (LQG) using simple arguments coming from the area spectrum at different
length scales. We have obtained that the spectral dimension of the spatial
section runs from 2 to 3, across a 1.5 phase, when the energy of a probe scalar
field decrees from high to low energy. We have calculated the spectral
dimension of the space-time also using results from spin-foam models, obtaining
a 2-dimensional effective manifold at hight energy. Our result is consistent
with other two approach to non perturbative quantum gravity: causal dynamical
triangulation and asymptotic safety quantum gravity.


title: Lifts of partial characters with respect to a chain of normal subgroups

abstract:
  In this paper, we consider lifts of $\pi$-partial characters with the
property that the irreducible constituents of their restrictions to certain
normal subgroups are also lifts. We will show that such a lift must be induced
from what we call an inductive pair, and every character induced from an
inductive pair is a such a lift. With this condition, we will get a lower bound
on the number of such lifts.


title: On the Banach-Mazur Type for Normed Spaces

abstract:
  In order to measure qualitative properties we introduce a notion of a type
for arbitrary normed spaces which measures the worst possible growth of partial
sums of sequences weakly converging to zero. The ideas can be traced back to
Banach and Mazur who used this type to compare the so-called linear dimension
of classical Banach spaces. As an application we compare the linear dimension
and investigate isomorphy of some classical Banach spaces.


title:
RooStatsCms: a tool for analyses modelling, combination and statistical
  studies

abstract:
  The RooStatsCms (RSC) software framework allows analysis modelling and
combination, statistical studies together with the access to sophisticated
graphics routines for results visualisation. The goal of the project is to
complement the existing analyses by means of their combination and accurate
statistical studies.


title: Kac-Moody and Virasoro Symmetries of Principal Chiral Sigma Models

abstract:
  It is commonly asserted that there is a \hat G\times G centreless Kac-Moody
extension of the manifest G\times G global symmetry of the two-dimensional
principal chiral model (PCM) for the group manifold G. Here, we show that the
symmetry is in fact larger, namely \hat G\times \hat G, the full centreless
Kac-Moody extension of the entire manifest G\times G global symmetry. Extending
previous results in the literature, we also obtain an explicit realisation of
the Virasoro-like symmetry of the PCM, generated by K_n=L_{n+1} - L_{n-1} for
both positive and negative n. We show that these generators obey
Sugarawara-type commutation relations with the two commuting copies of the
Kac-Moody algebra \hat G.


title:
Evidence for the Missing Baryons in the Angular Correlation of the
  Diffuse X-ray Background

abstract:
  The amount of detected baryons in the local Universe is at least a factor of
two smaller than measured at high redshift. It is believed that a significant
fraction of the baryons in the current Universe is "hiding" in a hot
filamentary structure filling the intergalactic space, the Warm-Hot
Intergalactic Medium ($WHIM$). We found evidence of the missing baryons in the
$WHIM$ by detecting their signature on the angular correlation of diffuse X-ray
emission with the XMM-Newton satellite. Our result indicates that $(12\pm 5)$%
of the total diffuse X-ray emission in the energy range 0.4-0.6 keV is due to
intergalactic filaments. The statistical significance of our detection is
several sigmas ($\chi ^2>136$ N=19). The error bar in the X-ray flux is
dominated, instead, by cosmic variation and model uncertainties.


title: Groups where all the irreducible characters are super-monomial

abstract:
  Isaacs has defined a character to be super monomial if every primitive
character inducing it is linear. Isaacs has conjectured that if $G$ is an
$M$-group with odd order, then every irreducible character is super monomial.
We prove that the conjecture is true if $G$ is an $M$-group of odd order where
every irreducible character is a $\{p \}$-lift for some prime $p$. We say that
a group where irreducible character is super monomial is a super $M$-group. We
use our results to find an example of a super $M$-group that has a subgroup
that is not a super $M$-group.


title: Improved Neutron-Capture Element Abundances in Planetary Nebulae

abstract:
  Spectroscopy of planetary nebulae (PNe) provides the means to investigate
s-process enrichments of neutron(n)-capture elements that cannot be detected in
asymptotic giant branch (AGB) stars. However, accurate abundance determinations
of these elements present a challenge. Corrections for unobserved ions can be
large and uncertain, since in many PNe only one ion of a given n-capture
element has been detected. Furthermore, the atomic data governing the
ionization balance of these species are not well-determined, inhibiting the
derivation of accurate ionization corrections. We present initial results of a
program that addresses these challenges. Deep high resolution optical
spectroscopy of ~20 PNe has been performed to detect emission lines from
trans-iron species including Se, Br, Kr, Rb, and Xe. The optical spectral
region provides access to multiple ions of these elements, which reduces the
magnitude and importance of uncertainties in the ionization corrections. In
addition, experimental and theoretical efforts are providing determinations of
the photoionization cross-sections and recombination rate coefficients of Se,
Kr, and Xe ions. These new atomic data will make it possible to derive robust
ionization corrections for these elements. Together, our observational and
atomic data results will enable n-capture element abundances to be determined
with unprecedented accuracy in ionized nebulae.


title: The Large Sieve and Galois Representations

abstract:
  We describe a generalization of the large sieve to situations where the
underlying groups are nonabelian, and give several applications to the
arithmetic of abelian varieties. In our applications, we sieve the set of
primes via the system of representations arising from the Galois action on the
torsion points of an abelian variety. The resulting upper bounds require
explicit character sum calculations, with stronger results holding if one
assumes the Generalized Riemann Hypothesis.


title:
Some index formulae on the moduli space of stable parabolic vector
  bundles

abstract:
  We study natural families of d-bar operators on the moduli space of stable
parabolic vector bundles. Applying a families index theorem for hyperbolic cusp
operators from our previous work, we find formulae for the Chern characters of
the associated index bundles. The contributions from the cusps are explicitly
expressed in terms of the Chern characters of natural vector bundles related to
the parabolic structure. We show that our result implies formulae for the Chern
classes of the associated determinant bundles consistent with a result of
Takhtajan and Zograf.


title:
Importance of Initial Electronic State in Two-Dimensional Electron
  System for Electron Transport from Two-Dimensional Electron Gas to Quantum
  Dot

abstract:
  We have theoretically investigated the time-evolution of electron transport
from a two-dimensional electron system (2DES) to a quantum dot (QD). We clearly
showed that the coherent electron transport is remarkably modified depending on
the initial electronic state in the 2DES. The electron transport from the 2DES
to the QD is strongly enhanced when the initial state of electron in the 2DES
is localized below the QD. We indicate that these features should be obtained
in other nano-structure-electrode coupled systems, and the electron transport
between the systems having completely different geometrical conditions is
significantly affected by the initial spatial distribution of the electron
density.


title: Spectral extension of the quantum group cotangent bundle

abstract:
  The structure of a cotangent bundle is investigated for quantum linear groups
GLq(n) and SLq(n). Using a q-version of the Cayley-Hamilton theorem we
construct an extension of the algebra of differential operators on SLq(n)
(otherwise called the Heisenberg double) by spectral values of the matrix of
right invariant vector fields. We consider two applications for the spectral
extension. First, we describe the extended Heisenberg double in terms of a new
set of generators -- the Weyl partners of the spectral variables. Calculating
defining relations in terms of these generators allows us to derive SLq(n) type
dynamical R-matrices in a surprisingly simple way. Second, we calculate an
evolution operator for the model of q-deformed isotropic top introduced by
A.Alekseev and L.Faddeev. The evolution operator is not uniquely defined and we
present two possible expressions for it. The first one is a Riemann theta
function in the spectral variables. The second one is an almost free motion
evolution operator in terms of logarithms of the spectral variables. Relation
between the two operators is given by a modular functional equation for Riemann
theta function.


title:
Asymptotic expansion of planar canard solutions near a non-generic
  turning point

abstract:
  This paper deals with the asymptotic study of the so-called canard solutions,
which arise in the study of real singularly perturbed ODEs. Starting near an
attracting branch of the "slow curve", those solutions are crossing a turning
point before following for a while a repelling branch of the "slow curve".
Assuming that the turning point is degenerate (or non-generic), we apply a
correspondence presented in a recent paper. This application needs the
definition of a family of functions $\phi$ that is studied in a first part.
Then, we use the correspondence is used to compute the asymptotic expansion in
the powers of the small parameter for the canard solution.


title: Effective action of a five-dimensional domain wall

abstract:
  We calculate the four-dimensional low-energy effective action for the
perturbations of a two-scalar domain wall model in five dimensions. Comparison
of the effective action to the Nambu-Goto action reveals the presence of an
additional coupling between the light scalar field and the massless translation
mode (branon excitation), which can be written in terms of the curvature scalar
of the induced metric. We comment on the impact of this interaction to branon
physics.


title:
First, second, and third change of rings theorems for the Gorenstein
  homological dimensions

abstract:
  Motivated by their impact on homological algebra, the change of rings results
have been the subject of several interesting works in Gorenstein homological
algebra over Noetherian rings.
  In this paper, we investigate the change of rings theorems for the Gorenstein
dimensions over arbitrary rings. Namely, by the use of the notion of strongly
Gorenstein modules, we extend the well-known first, second, and third change of
rings theorems for the classical projective and injective dimensions to the
Gorenstein projective and injective dimensions, respectively. Each of the
results established, in this paper, for the Gorenstein projective dimension is
a generalization of a result established over Noetherian rings and for finitely
generated modules. In this paper, we investigate the change of rings theorems
for the Gorenstein dimensions over arbitrary rings. Namely, by the use of the
notion of strongly Gorenstein modules, we extend the well-known first, second,
and third change of rings theorems for the classical projective and injective
dimensions to the Gorenstein projective and injective dimensions, respectively.
Each of the results established in this paper for the Gorenstein projective
dimension is a generalization of a $G$-dimension of a finitely generated module
$M$ over a noetherian ring $R$.


title: The Ricci Flow for Nilmanifolds

abstract:
  We consider the Ricci flow for simply connected nilmanifolds, which
translates to a Ricci flow on the space of nilpotent metric Lie algebras. We
consider the evolution of the inner product and the evolution of structure
constants, as well as the evolution of these quantities modulo rescaling. We
set up systems of O.D.E.'s for some of these flows and describe their
qualitative properties. We also present some explicit solutions for the
evolution of soliton metrics under the Ricci flow.


title: Phase transitions in diluted negative-weight percolation models

abstract:
  We investigate the geometric properties of loops on two-dimensional lattice
graphs, where edge weights are drawn from a distribution that allows for
positive and negative weights. We are interested in the appearance of spanning
loops of total negative weight. The resulting percolation problem is
fundamentally different from conventional percolation, as we have seen in a
previous study of this model for the undiluted case.
  Here, we investigate how the percolation transition is affected by additional
dilution. We consider two types of dilution: either a certain fraction of edges
exhibit zero weight, or a fraction of edges is even absent. We study these
systems numerically using exact combinatorial optimization techniques based on
suitable transformations of the graphs and applying matching algorithms. We
perform a finite-size scaling analysis to obtain the phase diagram and
determine the critical properties of the phase boundary.
  We find that the first type of dilution does not change the universality
class compared to the undiluted case whereas the second type of dilution leads
to a change of the universality class.


title: Supersolid state in fermionic optical lattice systems

abstract:
  We study ultracold fermionic atoms trapped in an optical lattice with
harmonic confinement by combining the real-space dynamical mean-field theory
with a two-site impurity solver. By calculating the local particle density and
the pair potential in the systems with different clusters, we discuss the
stability of a supersolid state, where an s-wave superfluid coexists with a
density-wave state of checkerboard pattern. It is clarified that a confining
potential plays an essential role in stabilizing the supersolid state. The
phase diagrams are obtained for several effective particle densities.


title: Steinberg lattice of the general linear group and its modular reduction

abstract:
  We study the Steinberg lattice of the general linear group when reduced
modulo a prime different from the defining characteristic.


title: The butterfly diagram in the 18th century

abstract:
  Digitized images of the drawings by J.C. Staudacher were used to determine
sunspot positions for the period of 1749-1796. From the entire set of drawings,
6285 sunspot positions were obtained for a total of 999 days. Various methods
have been applied to find the orientation of the solar disk which is not given
for the vast majority of the drawings by Staudacher. Heliographic latitudes and
longitudes in the Carrington rotation frame were determined. The resulting
butterfly diagram shows a highly populated equator during the first two cycles
(Cycles 0 and 1 in the usual counting since 1749). An intermediate period is
Cycle 2, whereas Cycles 3 and 4 show a typical butterfly shape. A tentative
explanation may be the transient dominance of a quadrupolar magnetic field
during the first two cycles.


title: Emerging AdS from Extremally Rotating NS5-branes

abstract:
  We investigate the near-horizon limit of extremally rotating NS5-branes. The
resulting geometry has SL(2,R) \times U(1)^2 isometry. The asymptotic symmetry
group contains a chiral Virasoro algebra, and we obtain two different
realizations depending on the boundary conditions we impose. When one of the
two angular momenta vanishes, the symmetry is enhanced to AdS_3. The entropy of
the boundary theory can be estimated from the Cardy formula and it agrees with
the Bekenstein-Hawking entropy of the bulk theory. We can embed the extremally
rotating NS5-brane geometry in an exactly solvable string background, which may
yield microscopic understanding of this duality, especially about the
mysterious enhancement of the symmetry from AdS_2 to AdS_3. The construction
suggests emerging Virasoro symmetries in the extreme corner of the (1+5)
dimensional little string theory.


title:
Solution to Faddeev equations with two-body experimental amplitudes as
  input and application to J^P=1/2^+, S=0 baryon resonances

abstract:
  We solve the Faddeev equations for the two meson-one baryon system $\pi\pi N$
and coupled channels using the experimental two-body $t$-matrices for the $\pi
N$ interaction as input and unitary chiral dynamics to describe the interaction
between the rest of coupled channels. In addition to the $N^*(1710)$ obtained
before with the $\pi\pi N$ channel, we obtain, for $J^\pi=1/2^+$ and total
isospin of the three-body system $I=1/2$, a resonance peak whose mass is around
2080 MeV and width of 54 MeV, while for $I=3/2$ we find a peak around 2126 MeV
and 42 MeV of width. These two resonances can be identified with the $N^*
(2100)$ and the $\Delta (1910)$, respectively. We obtain another peak in the
isospin 1/2 configuration, around 1920 MeV which can be interpreted as a
resonance in the $N a_0(980)$ and $N f_0(980)$ systems.


title: Lorentz Violation and Alpha-Decay

abstract:
  Relating the effective Lorentz violation coefficients for composite particles
to the coefficients for their constituent fields is a challenging problem. We
calculate the Lorentz violation coefficients relevant to the dynamics of an
alpha-particle in terms of proton and neutron coefficients. The alpha-particle
coefficients would lead to anisotropies in the alpha-decays of nuclei, and
because the decay process involves quantum tunneling, the effects of any
Lorentz violations could be exponentially enhanced.


title:
Tailoring the excitation of localized surface plasmon-polariton
  resonances by focusing radially-polarized beams

abstract:
  We study the interaction of focused radially-polarized light with metal
nanospheres. By expanding the electromagnetic field in terms of multipoles, we
gain insight on the excitation of localized surface plasmon-polariton
resonances in the nanoparticle. We show that focused radially-polarized beams
offer more opportunities than a focused plane wave or a Gaussian beam for
tuning the near- and far-field system response. These results find applications
in nano-optics, optical tweezers, and optical data storage.


title: Restricted limits of minimal affinizations

abstract:
  We obtain character formulas of minimal affinizations of representations of
quantum groups when the underlying simple Lie algebra is orthogonal and the
support of the highest weight is contained in the first three nodes of the
Dynkin diagram. We also give a framework for extending our techniques to a more
general situation. In particular, for the orthogonal algebras and a highest
weight supported in at most one spin node, we realize the restricted classical
limit of the corresponding minimal affinizations as a quotient of a module
given by generators and relations and, furthermore, show that it projects onto
the submodule generated by the top weight space of the tensor product of
appropriate restricted Kirillov-Reshetikhin modules. We also prove a conjecture
of Chari and Pressley regarding the equivalence of certain minimal
affinizations in type D4.


title:
Rayleigh-Taylor-Unstable Accretion and Variability of Magnetized Stars:
  Global Three-Dimensional Simulations

abstract:
  We present results of 3D simulations of MHD instabilities at the accretion
disk-magnetosphere boundary. The instability is Rayleigh-Taylor, and develops
for a fairly broad range of accretion rates and stellar rotation rates and
magnetic fields. It produces tall, thin tongues of plasma that penetrate the
magnetosphere in the equatorial plane. The shape and number of the tongues
changes with time on the inner-disk dynamical timescale. In contrast with
funnel flows, which deposit matter mainly in the polar region, the tongues
deposit matter much closer to the stellar equator. The instability appears for
relatively small misalignment angles, $\Theta\lesssim30^\circ$, between the
star's rotation and magnetic axes, and is associated with higher accretion
rates. The hot spots and light curves during accretion through instability are
generally much more chaotic than during stable accretion. The unstable state of
accretion has possible implications for quasi-periodic oscillations and
intermittent pulsations from accreting systems.


title: The number of elements in the mutation class of a quiver of type $D_n$

abstract:
  We show that the number of quivers in the mutation class of a quiver of
Dynkin type $D_n$ is given by $\sum_{d|n} \phi(n/d)\binom{2d}{d}/(2n)$ for $n
\geq 5$. To obtain this formula, we give a correspondence between the quivers
in the mutation class and certain rooted trees.


title: 'Fair' Partitions of Polygons - an Introduction

abstract:
  We address the question: Given a positive integer $N$, can any 2D convex
polygonal region be partitioned into $N$ convex pieces such that all pieces
have the same area and same perimeter? The answer to this question is easily
`yes' for $N$=2. We prove the answer to be `yes' for $N$=4 and also discuss
higher powers of 2.


title: The Quantum Locker Puzzle

abstract:
  The locker puzzle is a game played by multiple players against a referee. It
has been previously shown that the best strategy that exists cannot succeed
with probability greater than 1-ln2 \approx 0.31, no matter how many players
are involved. Our contribution is to show that quantum players can do much
better--they can succeed with probability 1. By making the rules of the game
significantly stricter, we show a scenario where the quantum players still
succeed perfectly, while the classical players win with vanishing probability.
Other variants of the locker puzzle are considered, as well as a cheating
referee.


title: Unexplained Excess of Electron-Like Events From a 1-GeV Neutrino Beam

abstract:
  The MiniBooNE Collaboration observes unexplained electron-like events in the
reconstructed neutrino energy range from 200 to 475 MeV. With $6.46 \times
10^{20}$ protons on target, 544 electron-like events are observed in this
energy range, compared to an expectation of $415.2 \pm 43.4$ events,
corresponding to an excess of $128.8 \pm 20.4 \pm 38.3$ events. The shape of
the excess in several kinematic variables is consistent with being due to
either $\nu_e$ and $\bar \nu_e$ charged-current scattering or to $\nu_\mu$
neutral-current scattering with a photon in the final state. No significant
excess of events is observed in the reconstructed neutrino energy range from
475 to 1250 MeV, where 408 events are observed compared to an expectation of
$385.9 \pm 35.7$ events.


title: Observational Evidence for Cosmological-Scale Extra Dimensions

abstract:
  We present a case that current observations may already indicate new
gravitational physics on cosmological scales. The excess of power seen in the
Lyman-alpha forest and small-scale CMB experiments, the anomalously large bulk
flows seen both in peculiar velocity surveys and in kinetic SZ, and the higher
ISW cross-correlation all indicate that structure may be more evolved than
expected from LCDM. We argue that these observations find a natural explanation
in models with infinite-volume (or, at least, cosmological-size) extra
dimensions, where the graviton is a resonance with a tiny width. The
longitudinal mode of the graviton mediates an extra scalar force which speeds
up structure formation at late times, thereby accounting for the above
anomalies. The required graviton Compton wavelength is relatively small
compared to the present Hubble radius, of order 300-600 Mpc. Moreover, with
certain assumptions about the behavior of the longitudinal mode on super-Hubble
scales, our modified gravity framework can also alleviate the tension with the
low quadrupole and the peculiar vanishing of the CMB correlation function on
large angular scales, seen both in COBE and WMAP. This relies on a novel
mechanism that cancels a late-time ISW contribution against the primordial
Sachs-Wolfe amplitude.


title:
Relativistic Simulations of Black Hole-Neutron Star Mergers: Effects of
  black-hole spin

abstract:
  Black hole-neutron star (BHNS) binary mergers are candidate engines for
generating both short-hard gamma-ray bursts (SGRBs) and detectable
gravitational waves. Using our most recent conformal thin-sandwich BHNS initial
data and our fully general relativistic hydrodynamics code, which is now
AMR-capable, we are able to efficiently and accurately simulate these binaries
from large separations through inspiral, merger, and ringdown. We evolve the
metric using the BSSN formulation with the standard moving puncture gauge
conditions and handle the hydrodynamics with a high-resolution shock-capturing
scheme. We explore the effects of BH spin (aligned and anti-aligned with the
orbital angular momentum) by evolving three sets of initial data with BH:NS
mass ratio q=3: the data sets are nearly identical, except the BH spin is
varied between a/M = -0.5 (anti-aligned), 0.0, and 0.75. The number of orbits
before merger increases with a/M, as expected. We also study the nonspinning BH
case in more detail, varying q between 1, 3, and 5. We calculate gravitational
waveforms for the cases we simulate and compare them to binary black-hole
waveforms. Only a small disk (< 0.01 M_sun) forms for the anti-aligned spin
case (a/M = -0.5) and for the most extreme mass ratio case (q=5). By contrast,
a massive (M_disk is about 0.2 M_sun), hot disk forms in the rapidly spinning
(a/M = 0.75) aligned BH case. Such a disk could drive a SGRB,possibly by, e.g.,
producing a copious flux of neutrino-antineutino pairs.


title: The Volume of the Universe after Inflation and de Sitter Entropy

abstract:
  We calculate the probability distribution for the volume of the Universe
after slow-roll inflation both in the eternal and in the non-eternal regime.
Far from the eternal regime the probability distribution for the number of
e-foldings, defined as one third of the logarithm of the volume, is sharply
peaked around the number of e-foldings of the classical inflaton trajectory. At
the transition to the eternal regime this probability is still peaked (with the
width of order one e-folding) around the average, which gets twice larger at
the transition point. As one enters the eternal regime the probability for the
volume to be finite rapidly becomes exponentially small. In addition to
developing techniques to study eternal inflation, our results allow us to
establish the quantum generalization of a recently proposed bound on the number
of e-foldings in the non-eternal regime: the probability for slow-roll
inflation to produce a finite volume larger than e^(S_dS/2), where S_dS is the
de Sitter entropy at the end of the inflationary stage, is smaller than the
uncertainty due to non-perturbative quantum gravity effects. The existence of
such a bound provides a consistency check for the idea of de Sitter
complementarity.


title: Open String Wavefunctions in Warped Compactifications

abstract:
  We analyze the wavefunctions for open strings in warped compactifications,
and compute the warped Kahler potential for the light modes of a probe D-brane.
This analysis not only applies to the dynamics of D-branes in warped
backgrounds, but also allows to deduce warping corrections to the closed string
Kahler metrics via their couplings to open strings. We consider in particular
the spectrum of D7-branes in warped Calabi-Yau orientifolds, which provide a
string theory realizations of the Randall-Sundrum scenario. We find that
certain background fluxes, necessary in the presence of warping, couple to the
fermionic wavefunctions and qualitatively change their behavior. This modified
dependence of the wavefunctions are needed for consistency with supersymmetry,
though it is present in non-supersymmetric vacua as well. We discuss the
deviations of our setup from the RS scenario and, as an application of our
results, compute the warping corrections to Yukawa couplings in a simple model.
Our analysis is performed both with and without the presence of D-brane
world-volume flux, as well as for the case of backgrounds with varying dilaton.


title: Chaos in a spatial epidemic model

abstract:
  We investigate an interacting particle system inspired by the gypsy moth,
whose populations grow until they become sufficiently dense so that an epidemic
reduces them to a low level. We consider this process on a random 3-regular
graph and on the $d$-dimensional lattice and torus, with $d\geq2$. On the
finite graphs with global dispersal or with a dispersal radius that grows with
the number of sites, we prove convergence to a dynamical system that is chaotic
for some parameter values. We conjecture that on the infinite lattice with a
fixed finite dispersal distance, distant parts of the lattice oscillate out of
phase so there is a unique nontrivial stationary distribution.


title: Cosmological constraints on a light non-thermal sterile neutrino

abstract:
  Although the MiniBooNE experiment has severely restricted the possible
existence of light sterile neutrinos, a few anomalies persist in oscillation
data, and the possibility of extra light species contributing as a subdominant
hot (or warm) component is still interesting. In many models, this species
would be in thermal equilibrium in the early universe and share the same
temperature as active neutrinos, but this is not necessarily the case. In this
work, we fit up-to-date cosmological data with an extended LambdaCDM model,
including light relics with a mass typically in the range 0.1 -10 eV. We
provide, first, some nearly model-independent constraints on their current
density and velocity dispersion, and second, some constraints on their mass,
assuming that they consist either in early decoupled thermal relics, or in
non-resonantly produced sterile neutrinos. Our results can be used for
constraining most particle-physics-motivated models with three active neutrinos
and one extra light species. For instance, we find that at the 3 sigma
confidence level, a sterile neutrino with mass m_s = 2 eV can be accommodated
with the data provided that it is thermally distributed with (T_s/T_nu) < 0.8,
or non-resonantly produced with (Delta N_eff) < 0.5. The bounds become
dramatically tighter when the mass increases. For m_s < 0.9 eV and at the same
confidence level, the data is still compatible with a standard thermalized
neutrino.


title: Quantifiers for randomness of chaotic pseudo random number generators

abstract:
  We deal with randomness-quantifiers and concentrate on their ability do
discern the hallmark of chaos in time-series used in connection with pseudo
random number generators (PRNG). Workers in the field are motivated to use
chaotic maps for generating PRNGs because of the simplicity of their
implementation. Although there exist very efficient general-purpose benchmarks
for testing PRNGs, we feel that the analysis provided here sheds additional
didactic light on the importance of the main statistical characteristics of a
chaotic map, namely, i) its invariant measure and ii) the mixing constant. This
is of help in answering two questions that arise in applications, that is, (1)
which is the best PRNG among the available ones? and (2) If a given PRNG turns
out not to be good enough and a randomization procedure must still be applied
to it, which is the best applicable randomization procedure?. Our answer
provides a comparative analysis of several quantifiers advanced in the extant
literature.


title: Observations on the Wilson fermions in the epsilon regime

abstract:
  We make several observations concerning the low quark mass region with Wilson
fermions and how this is connected with the epsilon regime in the continuum. A
transition from tiny cutoff effects to rather large discretization errors would
take place in general with Wilson fermions if we lower the quark mass at finite
lattice spacing. We argue that these two regions exhibit rather different
behaviours concerning the coupling between cutoff effects and zero-modes. We
interpolate between these two regimes adding to the continuum epsilon regime
formulae, in the spirit of the Symanzik expansion, the relevant operators
parametrising the leading cutoff effects. We compute the partition function,
the chiral condensate, scalar and pseudo-scalar correlation functions. The
final formulae can be used to fit lattice data to extract physical low energy
constants, and to estimate systematic uncertainties coming from discretization
errors. Moreover they suggest ways on how to remove these cutoff effects, the
core of which are captured by the continuum zero modes.


title: Modeling the X-ray emission of SN 1993J

abstract:
  We investigate the effects of radiative shocks on the observed X-ray emission
from the Type II supernova SN 1993J. To this end, the X-ray emission is modeled
as a result of the interaction between the supernova ejecta and a dense
circumstellar medium at an age of 8 years. The circumstances under which the
reverse shock is radiative are discussed and the observed X-ray emission is
analyzed using the numerical code described in Nymark et al. (2006). We argue
that the original analysis of the X-ray observations suffered from the lack of
self-consistent models for cooling shocks with high density and velocity,
leading to questionable conclusions about the temperatures and elemental
abundances. We reanalyze the spectra with our numerical model, and discuss the
expected spectra for different explosion models for the progenitors. We find
that the spectra of SN 1993J are compatible with a CNO-enriched composition and
that the X-ray flux is dominated by the reverse shock.


title:
The nonlinear probability distribution function in models with local
  primordial non-Gaussianity

abstract:
  We use the spherical evolution approximation to investigate nonlinear
evolution from the non-Gaussian initial conditions characteristic of the local
f_nl model. We provide an analytic formula for the nonlinearly evolved
probability distribution function of the dark matter which shows that the
under-dense tail of the nonlinear PDF in the f_nl model should differ
significantly from that for Gaussian initial conditions. Measurements of the
under-dense tail in numerical simulations may be affected by discreteness
effects, and we use a Poisson counting model to describe this effect. Once this
has been accounted for, our model is in good quantitative agreement with the
simulations.


title: Quantization in Spacetime from Null Paths in Higher Dimensions

abstract:
  Massive particles on timelike paths in spacetime can be viewed as moving on
null paths in a higher-dimensional manifold. This and other consequences follow
from the use of Campbell's theorem to embed 4D general relativity in
non-compactified 5D Kaluza-Klein theory. We now show that it is possible in
principle to obtain the standard rule for quantization in 4D from the canonical
metric with null paths in 5D. Particle mass can be wavelike, as suggested
originally by Dirac, and other 4D/5D consequences are outlined.


title:
How Euler would compute the Euler-Poincar\'e characteristic of a Lie
  superalgebra

abstract:
  The Euler-Poincar\'e characteristic of a finite-dimensional Lie algebra
vanishes. If we want to extend this result to Lie superalgebras, we should deal
with infinite sums. We observe that a suitable method of summation, which goes
back to Euler, allows to do that, to a certain degree. The mathematics behind
it is simple, we just glue the pieces of elementary homological algebra,
first-year calculus and pedestrian combinatorics together, and present them in
a (hopefully) coherent manner.


title: Anyonic order parameters for discrete gauge theories on the lattice

abstract:
  We present a new family of gauge invariant non-local order parameters for
(non-abelian) discrete gauge theories on a Euclidean lattice, which are in
one-to-one correspondence with the excitation spectrum that follows from the
representation theory of the quantum double D(H) of the finite group H.
  These combine magnetic flux-sector labeled by a conjugacy class with an
electric representation of the centralizer subgroup that commutes with the
flux. In particular cases like the trivial class for magnetic flux, or the
trivial irrep for electric charge, these order parameters reduce to the
familiar Wilson and the 't Hooft operators respectively. It is pointed out that
these novel operators are crucial for probing the phase structure of a class of
discrete lattice models we define, using Monte Carlo simulations.


title: Unfolding Convex Polyhedra via Quasigeodesic Star Unfoldings

abstract:
  We extend the notion of a star unfolding to be based on a simple
quasigeodesic loop Q rather than on a point. This gives a new general method to
unfold the surface of any convex polyhedron P to a simple, planar polygon:
shortest paths from all vertices of P to Q are cut, and all but one segment of
Q is cut.


title:
Raman Spectroscopy of Graphene under Uniaxial Stress: Phonon Softening
  and Determination of the Crystallographic Orientation

abstract:
  We present a systematic study of the Raman spectra of optical phonons in
graphene monolayers under tunable uniaxial tensile stress. Both the G and 2D
bands exhibit significant red shifts. The G band splits into two distinct
sub-bands (G+, G-) because of the strain-induced symmetry breaking. Raman
scattering from the G+ and G- bands shows a distinctive polarization dependence
that reflects the angle between the axis of the stress and the underlying
graphene crystal axes. Polarized Raman spectroscopy therefore constitutes a
purely optical method for the determination of the crystallographic orientation
of graphene.


title:
Constraints on modified gravity from the observed X-ray luminosity
  function of galaxy clusters

abstract:
  We use measurements of the growth of cosmic structure, as inferred from the
observed evolution of the X-ray luminosity function (XLF) of galaxy clusters,
to constrain departures from General Relativity (GR) on cosmological scales. We
employ the popular growth rate parameterization, Omega_m(z)^gamma, for which GR
predicts a growth index gamma~0.55. We use observations of the cosmic microwave
background (CMB), type Ia supernovae (SNIa), and X-ray cluster gas-mass
fractions (fgas), to simultaneously constrain the expansion history and energy
content of the Universe, as described by the background model parameters:
Omega_m, w, and Omega_k, i.e., the mean matter density, the dark energy
equation of state parameter, and the mean curvature, respectively. Using
conservative allowances for systematic uncertainties, in particular for the
evolution of the mass-luminosity scaling relation in the XLF analysis, we find
gamma=0.51+0.16-0.15 and Omega_m=0.27+-0.02 (68.3 per cent confidence limits),
for a flat cosmological constant (LCDM) background model. Allowing w to be a
free parameter, we find gamma=0.44+0.17-0.15. Relaxing the flatness prior in
the LCDM model, we obtain gamma=0.51+0.19-0.16. When in addition to the XLF
data we use the CMB data to constrain gamma through the ISW effect, we obtain a
combined constraint of gamma=0.45+0.14-0.12 for the flat LCDM model. Our
analysis provides the tightest constraints to date on the growth index. We find
no evidence for departures from General Relativity on cosmological scales.


title: Average-Case Perturbations and Smooth Condition Numbers

abstract:
  We define a new condition number adapted to directionally uniform
perturbations. The definitions and theorems can be applied to a large class of
problems. We show the relation with the classical condition number, and study
some interesting examples.


title: Similar is Better: Speed Variability Reduces Traffic Flow

abstract:
  Every driver knows that severe weather conditions cause traffic congestions.
In many cases there is no direct reason for the congestion, and people tend to
attribute it to the slow driving mode. Our computational study shows that the
slow driving cannot account for this phenomenon. It comes out that the reason
is not the decrease in mean velocity, but rather the change in the speed
distribution on the road. Width of the distribution, namely - the number of
"very fast" or "very slow" vehicles, affects both the need and the availability
of lane change and bypassing. Besides providing insight and analyzing the
underlying mechanism of a collective phenomenon, this example sheds light on a
fundamental aspect of computational modeling. Although simple-as-possible
models are desirable and provide better understanding of the real important
component of the modeled system, they can very easily turn into
over-simplifications and miss relevant qualitative phenomena.


title:
Conformal mappings versus other power series methods for solving
  ordinary differential equations: illustration on anharmonic oscillators

abstract:
  The simplicity and the efficiency of a quasi-analytical method for solving
nonlinear ordinary differential equations (ODE), is illustrated on the study of
anharmonic oscillators (AO) with a potential $V(x) =\beta x^{2}+x^{2m}$
($m>0$). The method [Nucl. Phys. B801, 296 (2008)], applies a priori to any ODE
with two-point boundaries (one being located at infinity), the solution of
which has singularities in the complex plane of the independent variable $x$. A
conformal mapping of a suitably chosen angular sector of the complex plane of
$x$ upon the unit disc centered at the origin makes convergent the transformed
Taylor series of the generic solution so that the boundary condition at
infinity can be easily imposed. In principle, this constraint, when applied on
the logarithmic-derivative of the wave function, determines the eigenvalues to
an arbitrary level of accuracy. In practice, for $\beta \geq 0$ or slightly
negative, the accuracy of the results obtained is astonishingly large with
regards to the modest computing power used. It is explained why the efficiency
of the method decreases as $\beta $ is more and more negative. Various aspects
of the method and comparisons with some seemingly similar methods, based also
on expressing the solution as a Taylor series, are shortly reviewed, presented
and discussed.


title:
Feature selection by Higher Criticism thresholding: optimal phase
  diagram

abstract:
  We consider two-class linear classification in a high-dimensional, low-sample
size setting. Only a small fraction of the features are useful, the useful
features are unknown to us, and each useful feature contributes weakly to the
classification decision -- this setting was called the rare/weak model (RW
Model). We select features by thresholding feature $z$-scores. The threshold is
set by {\it higher criticism} (HC). Let $\pee_i$ denote the $P$-value
associated to the $i$-th $z$-score and $\pee_{(i)}$ denote the $i$-th order
statistic of the collection of $P$-values. The HC threshold (HCT) is the order
statistic of the $z$-score corresponding to index $i$ maximizing $(i/n -
\pee_{(i)})/\sqrt{\pee_{(i)}(1-\pee_{(i)})}$. The ideal threshold optimizes the
classification error. In \cite{PNAS} we showed that HCT was numerically close
to the ideal threshold. We formalize an asymptotic framework for studying the
RW model, considering a sequence of problems with increasingly many features
and relatively fewer observations. We show that along this sequence, the
limiting performance of ideal HCT is essentially just as good as the limiting
performance of ideal thresholding. Our results describe two-dimensional {\it
phase space}, a two-dimensional diagram with coordinates quantifying "rare" and
"weak" in the RW model. Phase space can be partitioned into two regions -- one
where ideal threshold classification is successful, and one where the features
are so weak and so rare that it must fail. Surprisingly, the regions where
ideal HCT succeeds and fails make the exact same partition of the phase
diagram. Other threshold methods, such as FDR threshold selection, are
successful in a substantially smaller region of the phase space than either HCT
or Ideal thresholding.


title:
Heating in an Extended Accretion Disk Corona along the Z-Pattern in Cyg
  X-2

abstract:
  We observed at very high spectral resolution the prototype Z-source Cyg x-2
twice along its entire X-ray spectral variation pattern. In this preliminary
analysis we find an extended accretion disk corona exhibiting Lyman alpha
emissions from various H-like ions, as well as emissions from He-like ions of
Fe and Al, and Li-like ions of Fe. The brightest lines show a range of line
broadening: H-like lines are very broad with Doppler velocities between 1100
and 2700 km/s, while some others are narrower with widths of a few hundred
km/s. Line diagnostics allow us for the first time to determine coronal
parameters. The line properties are consistent with a stationary, extended up
to 10^10 cm, dense (1x10^15 cm^-3), and hot (log xi > 3; T > 10^6 K) accretion
disk corona. We find ongoing heating of the corona along the Z-track and
determine that heating luminosities change from about 0.4 L_Edd on the
horizontal to about 1.4 L_Edd on the flaring branch.


title: Mixing time of exponential random graphs

abstract:
  Exponential random graphs are used extensively in the sociology literature.
This model seeks to incorporate in random graphs the notion of reciprocity,
that is, the larger than expected number of triangles and other small
subgraphs. Sampling from these distributions is crucial for parameter
estimation hypothesis testing, and more generally for understanding basic
features of the network model itself. In practice sampling is typically carried
out using Markov chain Monte Carlo, in particular either the Glauber dynamics
or the Metropolis-Hasting procedure.
  In this paper we characterize the high and low temperature regimes of the
exponential random graph model. We establish that in the high temperature
regime the mixing time of the Glauber dynamics is $\Theta(n^2 \log n)$, where
$n$ is the number of vertices in the graph; in contrast, we show that in the
low temperature regime the mixing is exponentially slow for any local Markov
chain. Our results, moreover, give a rigorous basis for criticisms made of such
models. In the high temperature regime, where sampling with MCMC is possible,
we show that any finite collection of edges are asymptotically independent;
thus, the model does not possess the desired reciprocity property, and is not
appreciably different from the Erd\H{o}s-R\'enyi random graph.


title: Quantum and classical structures in nondeterminstic computation

abstract:
  In categorical quantum mechanics, classical structures characterize the
classical interfaces of quantum resources on one hand, while on the other hand
giving rise to some quantum phenomena. In the standard Hilbert space model of
quantum theories, classical structures over a space correspond to its
orthonormal bases. In the present paper, we show that classical structures in
the category of relations correspond to biproducts of abelian groups. Although
relations are, of course, not an interesting model of quantum computation, this
result has some interesting computational interpretations. If relations are
viewed as denotations of nondeterministic programs, it uncovers a wide variety
of non-standard quantum structures in this familiar area of classical
computation. Ironically, it also opens up a version of what in philosophy of
quantum mechanics would be called an ontic-epistemic gap, as it provides no
direct interface to these nonstandard quantum structures.


title: A 2MASS Analysis of the Stability of Southern Bok Globules

abstract:
  We used near-infrared 2MASS data to construct visual extinction maps of a
sample of Southern Bok globules utilizing the NICE method. We derived radial
extinction profiles of dense cores identified in the globules and analyzed
their stability against gravitational collapse with isothermal Bonnor-Ebert
spheres. The frequency distribution of the stability parameter xi_max of these
cores shows that a large number of them are located in stable states, followed
by an abrupt decrease of cores in unstable states. This decrease is steeper for
globules with associated IRAS point sources than for starless globules.
Moreover, globules in stable states have a Bonnor-Ebert temperature of T = 15
+- 6 K, while the group of critical plus unstable globules has a different
temperature of T = 10 +- 3 K. Distances were estimated to all the globules
studied in this work and the spectral class of the IRAS sources was calculated.
No variations were found in the stability parameters of the cores and the
spectral class of their associated IRAS sources. On the basis of 13CO J = 1-0
molecular line observations, we identified and modeled a blue-assymetric line
profile toward a globule of the sample, obtaining an upper limit infall speed
of 0.25 km/s.


title:
Branching rules in the ring of superclass functions of unipotent
  upper-triangular matrices

abstract:
  It is becoming increasingly clear that the supercharacter theory of the
finite group of unipotent upper-triangular matrices has a rich combinatorial
structure built on set-partitions that is analogous to the partition
combinatorics of the classical representation theory of the symmetric group.
This paper begins by exploring a connection to the ring of symmetric functions
in non-commuting variables that mirrors the symmetric group's relationship with
the ring of symmetric functions. It then also investigates some of the
representation theoretic structure constants arising from the restriction,
tensor products and superinduction of supercharacters in this context.


title:
Symmetry operators for Dirac's equation on two-dimensional spin
  manifolds

abstract:
  It is shown that the second order symmetry operators for the Dirac equation
on a general two-dimensional spin manifold may be expressed in terms of Killing
vectors and valence two Killing tensors. The role of these operators in the
theory of separation of variables for the Dirac equation is studied.


title:
Discrete solitons and vortices in hexagonal and honeycomb lattices:
  Existence, stability, and dynamics

abstract:
  We consider a prototypical dynamical lattice model, namely, the discrete
nonlinear Schroedinger equation on nonsquare lattice geometries. We present a
systematic classification of the solutions that arise in principal
six-lattice-site and three-lattice-site contours in the form of both discrete
multipole solitons and discrete vortices. Additionally to identifying the
possible states, we analytically track their linear stability both
qualitatively and quantitatively. We find that among the six-site
configurations, the hexapole of alternating phases, as well as the vortex of
topological charge S=2 have intervals of stability; among three-site states,
only the vortex of topological charge S=1 may be stable in the case of focusing
nonlinearity. These conclusions are confirmed both for hexagonal and for
honeycomb lattices by means of detailed numerical bifurcation analysis of the
stationary states from the anticontinuum limit, and by direct simulations to
monitor the dynamical instabilities, when the latter arise. The dynamics reveal
a wealth of nonlinear behavior resulting not only in single-site solitary wave
forms, but also in robust multisite breathing structures.


title: Universality of algebraic laws in Hamiltonian systems

abstract:
  Hamiltonian mixed systems with unbounded phase space are typically
characterized by two asymptotic algebraic laws: decay of recurrence time
statistics ($\gamma$) and superdiffusion ($\beta$). We conjecture the universal
exponents $\gamma=\beta=3/2$ for trapping of trajectories to regular islands
based on our analytical results for a wide class of area-preserving maps. For
Hamiltonian mixed systems with bounded phase space the interval
$3/2\leq\gamma_{b}\leq3$ was obtained, given that trapping takes place. A
number of simulations and experiments by other authors give additional support
to our claims.


title:
Massive gravitational waves from f(R) theories of gravity: Potential
  detection with LISA

abstract:
  This letter is a generalization of previous results on gravitational waves
(GWs) from f(R) theories of gravity. In some previous papers, particular f(R)
theories have been linearized for the first time in the literature. Now, the
process is further generalized, showing that every f(R) theory can be
linearized producting a third massive mode of gravitational radiation. In this
framework, previous results are particular cases of the more general problem
that is discussed in this letter. The potential detectability of such massive
GWs with LISA is also discussed with the auxilium of longitudinal response
functions.


title: Solitary Wave Solutions for the Nonlinear Dirac Equations

abstract:
  In this paper we prove the existence and local uniqueness of stationary
states for the nonlinear Dirac equation \[ i \sum_{j=0}^{3} \ga^j \pd_j \psi -
m\psi + F(\bar{\psi}\psi)\psi =0 \] where $ m >0$ and $ F(s) = |s|^{\theta}$
for $ 1\leq \theta < 2.$ More precisely we show that there exists $\e_0 > 0$
such that for $\omega \in(m - \e_0, m), $ there exists a solution $ \psi(t,x) =
e^{-i\omega t}\phi_{\omega}(x), x_0 = t, x = (x_1, x_2, x_3),$ and the mapping
from $ \omega $ to $ \phi_{\omega} $ is continuous. We prove this result by
relating the stationary solutions to the ground states of nonlinear
Schr\"{o}dinger equations.


title:
Force-detected nuclear double resonance between statistical spin
  polarizations

abstract:
  We demonstrate nuclear double resonance for nanometer-scale volumes of spins
where random fluctuations rather than Boltzmann polarization dominate. When the
Hartmann-Hahn condition is met in a cross-polarization experiment, flip-flops
occur between two species of spins and their fluctuations become coupled. We
use magnetic resonance force microscopy to measure this effect between 1H and
13C spins in 13C-enriched stearic acid. The development of a cross-polarization
technique for statistical ensembles adds an important tool for generating
chemical contrast in nanometer-scale magnetic resonance.


title: Secrecy capacity of a class of orthogonal relay eavesdropper channels

abstract:
  The secrecy capacity of relay channels with orthogonal components is studied
in the presence of an additional passive eavesdropper node. The relay and
destination receive signals from the source on two orthogonal channels such
that the destination also receives transmissions from the relay on its channel.
The eavesdropper can overhear either one or both of the orthogonal channels.
Inner and outer bounds on the secrecy capacity are developed for both the
discrete memoryless and the Gaussian channel models. For the discrete
memoryless case, the secrecy capacity is shown to be achieved by a partial
decode-and-forward (PDF) scheme when the eavesdropper can overhear only one of
the two orthogonal channels. Two new outer bounds are presented for the
Gaussian model using recent capacity results for a Gaussian multi-antenna
point-to-point channel with a multi-antenna eavesdropper. The outer bounds are
shown to be tight for two sub-classes of channels. The first sub-class is one
in which the source and relay are clustered and the and the eavesdropper
receives signals only on the channel from the source and the relay to the
destination, for which the PDF strategy is optimal. The second is a sub-class
in which the source does not transmit to the relay, for which a
noise-forwarding strategy is optimal.


title:
Theoretical investigation of polarization-compensated II-IV/I-V
  perovskite superlattices

abstract:
  Recent work suggested that head-to-head and tail-to-tail domain walls could
be induced to form in ferroelectric superlattices by introducing compensating
"delta doping" layers via chemical substitution in specified atomic planes
[Phys. Rev. B 73, 020103(R), 2006]. Here we investigate a variation of this
approach in which superlattices are formed of alternately stacked groups of
II-IV and I-V perovskite layers, and the "polar discontinuity" at the II-IV/I-V
interface effectively provides the delta-doping layer. Using first-principles
calculations on SrTiO3/KNbO3 as a model system, we show that this strategy
allows for the growth of a superlattice with stable polarized regions and large
polarization discontinuities at the internal interfaces. We also generalize a
Wannier-based definition of layer polarizations in perovskite superlattices
[Phys. Rev. Lett. 97, 107602 (2006)] to the case in which some (e.g., KO or
NbO2) layers are non-neutral, and apply this method to quantify the local
variations in polarization in the proposed SrTiO3/KNbO3 superlattice system.


title: An Efficient PTAS for Two-Strategy Anonymous Games

abstract:
  We present a novel polynomial time approximation scheme for two-strategy
anonymous games, in which the players' utility functions, although potentially
different, do not differentiate among the identities of the other players. Our
algorithm computes an $eps$-approximate Nash equilibrium of an $n$-player
2-strategy anonymous game in time $poly(n) (1/eps)^{O(1/eps^2)}$, which
significantly improves upon the running time $n^{O(1/eps^2)}$ required by the
algorithm of Daskalakis & Papadimitriou, 2007. The improved running time is
based on a new structural understanding of approximate Nash equilibria: We show
that, for any $eps$, there exists an $eps$-approximate Nash equilibrium in
which either only $O(1/eps^3)$ players randomize, or all players who randomize
use the same mixed strategy. To show this result we employ tools from the
literature on Stein's Method.


title: A Topological Phase in a Quantum Gravity Model

abstract:
  I would claim that we do not have a suitably general definition of what a
topological phase is, or more importantly, any robust understanding of how to
enter one even in the world of mathematical models. The latter is, of course,
the more important issue and the main subject of this note. But a good
definition can sharpen our thinking and a poor definition can misdirect us. I
will not attempt a final answer here but merely comment on the strengths and
weaknesses of possible definitions and argue for some flexibility. In
particular, I describe a rather simple class of ``quantum gravity'' models
which are neither lattice nor field theoretic but appear to contain strong
candidates for topological phases.

categories: cond-mat.str-el cond-mat.stat-mech gr-qc hep-th quant-ph


title:
Diffusivity of adatoms on plasma-exposed surfaces determined from the
  ionization energy approximation and ionic polarizability

abstract:
  Microscopic surface diffusivity theory based on atomic ionization energy
concept is developed to explain the variations of the atomic and displacement
polarizations with respect to the surface diffusion activation energy of
adatoms in the process of self-assembly of quantum dots on plasma-exposed
surfaces. These polarizations are derived classically, while the atomic
polarization is quantized to obtain the microscopic atomic polarizability. The
surface diffusivity equation is derived as a function of the ionization energy.
The results of this work can be used to fine-tune the delivery rates of
different adatoms onto nanostructure growth surfaces and optimize the
low-temperature plasma based nanoscale synthesis processes.


title: Density of commensurators for uniform lattices of right-angled buildings

abstract:
  Let G be the automorphism group of a regular right-angled building X. The
"standard uniform lattice" \Gamma_0 in G is a canonical graph product of finite
groups, which acts discretely on X with quotient a chamber. We prove that the
commensurator of \Gamma_0 is dense in G. This result was also obtained by
Haglund. For our proof, we develop carefully a technique of "unfoldings" of
complexes of groups. We use unfoldings to construct a sequence of uniform
lattices \Gamma_n in G, each commensurable to \Gamma_0, and then apply the
theory of group actions on complexes of groups to the sequence \Gamma_n. As
further applications of unfoldings, we determine exactly when the group G is
nondiscrete, and we prove that G acts strongly transitively on X.


title: Badly approximable affine forms and Schmidt games

abstract:
  For any real number \t, the set of all real numbers x for which there exists
a constant c(x) > 0 such that \inf_{p \in \ZZ} |\t q - x - p| \geq c(x)/|q| for
all q in \ZZ {0} is an 1/8-winning set.


title:
The Isospectral Fruits of Representation Theory: Quantum Graphs and
  Drums

abstract:
  We present a method which enables one to construct isospectral objects, such
as quantum graphs and drums. One aspect of the method is based on
representation theory arguments which are shown and proved. The complementary
part concerns techniques of assembly which are both stated generally and
demonstrated. For that purpose, quantum graphs are grist to the mill. We
develop the intuition that stands behind the construction as well as the
practical skills of producing isospectral objects. We discuss the theoretical
implications which include Sunada's theorem of isospectrality arising as a
particular case of this method. A gallery of new isospectral examples is
presented and some known examples are shown to result from our theory.


title:
The Radius-Luminosity Relationship for Active Galactic Nuclei: The
  Effect of Host-Galaxy Starlight on Luminosity Measurements II. The Full
  Sample of Reverberation-Mapped AGNs

abstract:
  We present high-resolution HST images of all 35 AGNs with optical
reverberation-mapping results, which we have modeled to create a nucleus-free
image of each AGN host galaxy. From the nucleus-free images, we determine the
host-galaxy contribution to ground-based spectroscopic luminosity measurements
at 5100A. After correcting the luminosities of the AGNs for the contribution
from starlight, we re-examine the Hbeta R-L relationship. Our best fit for the
relationship gives a powerlaw slope of 0.52 with a range of 0.45 - 0.59 allowed
by the uncertainties. This is consistent with our previous findings, and thus
still consistent with the naive assumption that all AGNs are simply
luminosity-scaled versions of each other. We discuss various consistency checks
relating to the galaxy modeling and starlight contributions, as well as
possible systematic errors in the current set of reverberation measurements
from which we determine the form of the R-L relationship.


title:
The Black Hole Mass-Bulge Luminosity Relationship for Active Galactic
  Nuclei from Reverberation Mapping and Hubble Space Telescope Imaging

abstract:
  We investigate the relationship between black hole mass and bulge luminosity
for AGNs with reverberation-based black hole mass measurements and bulge
luminosities from two-dimensional decompositions of Hubble Space Telescope host
galaxy images. We find that the slope of the relationship for AGNs is 0.76-0.85
with an uncertainty of ~0.1, somewhat shallower than the M_BH \propto
L^{1.0+/-0.1} relationship that has been fit to nearby quiescent galaxies with
dynamical black hole mass measurements. This is somewhat perplexing, as the AGN
black hole masses include an overall scaling factor that brings the AGN
M_BH-sigma relationship into agreement with that of quiescent galaxies. We
discuss biases that may be inherent to the AGN and quiescent galaxy samples and
could cause the apparent inconsistency in the forms of their M_BH-L_bulge
relationships.


title:
Possible duality violations in tau decay and their impact on the
  determination of alpha_s

abstract:
  We discuss the issue of duality violations in hadronic tau decay. After
introducing a physically motivated ansatz for duality violations, we estimate
their possible size by fitting this ansatz to the tau experimental data
provided by the ALEPH collaboration. Our conclusion is that these data do not
exclude significant duality violations in tau decay. This may imply an
additional systematic error in the value of alpha_s(m_tau), extracted from tau
decay, as large as \delta alpha_s(m_tau) \sim 0.003-0.010 .


title: On sums and products in C[x]

abstract:
  We show that under the assumption of a 24-term version of Fermat's Last
Theorem, there exists an absolute constant c > 0 such that if S is a set of n >
n_0 positive integers satisfying |S.S| < n^(1+c), then the sumset S.S satisfies
|S+S| >> n^2. In other words, we prove a weak form of the Erdos-Szemeredi
sum-product conjecture, conditional on an extension of Fermat's Last Theorem.
Unconditionally, we prove this theorem for when S is a set of n monic
polynomials. We also prove an analogue of a theorem of Bourgain and Chang for
the ring C[x].


title:
Time-resolved lasing action from single and coupled photonic crystal
  nanocavity array lasers emitting in the telecom-band

abstract:
  We measure the lasing dynamics of single and coupled photonic crystal
nanocavity array lasers fabricated in the indium gallium arsenide phosphide
material system. Under short optical excitation, single cavity lasers produce
pulses as fast as 11 ps (FWHM), while coupled cavity lasers show significantly
longer lasing duration which is not explained by a simple rate equations model.
A Finite Difference Time Domain simulation including carrier gain and diffusion
suggests that asynchronous lasing across the nanocavity array extends the
laser's pulse duration.


title:
Congestion Control Protocol for Wireless Sensor Networks Handling
  Prioritized Heterogeneous Traffic

abstract:
  Heterogeneous applications could be assimilated within the same wireless
sensor network with the aid of modern motes that have multiple sensor boards on
a single radio board. Different types of data generated from such types of
motes might have different transmission characteristics in terms of priority,
transmission rate, required bandwidth, tolerable packet loss, delay demands
etc. Considering a sensor network consisting of such multi-purpose nodes, in
this paper we propose Prioritized Heterogeneous Traffic-oriented Congestion
Control Protocol (PHTCCP) which ensures efficient rate control for prioritized
heterogeneous traffic. Our protocol uses intra-queue and inter-queue priorities
for ensuring feasible transmission rates of heterogeneous data. It also
guarantees efficient link utilization by using dynamic transmission rate
adjustment. Detailed analysis and simulation results are presented along with
the description of our protocol to demonstrate its effectiveness in handling
prioritized heterogeneous traffic in wireless sensor networks.


title:
Experimental determination of the microscopic origin of magnetism in
  parent iron pnictides

abstract:
  Like high Tc cuprates, the newly discovered iron based superconductors lie in
close proximity to a magnetically ordered parent phase. However, while the
magnetic order in parent cuprates is known to derive from a spin-spin local
superexchange interaction, a plethora of experiments including neutron
scattering have so far been unable to conclusively resolve whether a local
moment Heisenberg description applies in parent iron based compounds, or
whether magnetism arises from a collective SDW order instability. These two
alternatives can in principle be distinguished by measuring the low energy
momentum-resolved bulk-representative electronic structure of the magnetically
ordered phase. Using a combination of polarization dependent ARPES and STM, we
have isolated the complete low-lying bulk representative electronic structure
of magnetic SrFe2As2 with d-orbital symmetry specificity for the first time.
Our results show that while multiple bands with different iron d-orbital
character indeed contribute to charge transport, only one pair of bands with
opposite mirror symmetries microscopically exhibit an itinerant SDW instability
with energy scales on the order of 50 meV. The orbital resolved band topology
below T_SDW point uniquely to a nesting driven band hybridization mechanism of
the observed antiferromagnetism in the iron pnictides, and is consistent with
an unusual anisotropic nodal-density-wave state. In addition, these results
place strong constraints on many theories of pnictide superconductivity that
require a strict local moment magnetism starting point.


title:
An Ensemble Kalman-Particle Predictor-Corrector Filter for Non-Gaussian
  Data Assimilation

abstract:
  An Ensemble Kalman Filter (EnKF, the predictor) is used make a large change
in the state, followed by a Particle Filer (PF, the corrector) which assigns
importance weights to describe non-Gaussian distribution. The weights are
obtained by nonparametric density estimation. It is demonstrated on several
numerical examples that the new predictor-corrector filter combines the
advantages of the EnKF and the PF and that it is suitable for high dimensional
states which are discretizations of solutions of partial differential
equations.


title: Characterizing Truthful Multi-Armed Bandit Mechanisms

abstract:
  We consider a multi-round auction setting motivated by pay-per-click auctions
for Internet advertising. In each round the auctioneer selects an advertiser
and shows her ad, which is then either clicked or not. An advertiser derives
value from clicks; the value of a click is her private information. Initially,
neither the auctioneer nor the advertisers have any information about the
likelihood of clicks on the advertisements. The auctioneer's goal is to design
a (dominant strategies) truthful mechanism that (approximately) maximizes the
social welfare.
  If the advertisers bid their true private values, our problem is equivalent
to the "multi-armed bandit problem", and thus can be viewed as a strategic
version of the latter. In particular, for both problems the quality of an
algorithm can be characterized by "regret", the difference in social welfare
between the algorithm and the benchmark which always selects the same "best"
advertisement. We investigate how the design of multi-armed bandit algorithms
is affected by the restriction that the resulting mechanism must be truthful.
We find that truthful mechanisms have certain strong structural properties --
essentially, they must separate exploration from exploitation -- and they incur
much higher regret than the optimal multi-armed bandit algorithms. Moreover, we
provide a truthful mechanism which (essentially) matches our lower bound on
regret.


title: Accelerated expansion through interaction

abstract:
  Interactions between dark matter and dark energy with a given equation of
state are known to modify the cosmic dynamics. On the other hand, the strength
of these interactions is subject to strong observational constraints. Here we
discuss a model in which the transition from decelerated to accelerated
expansion of the Universe arises as a pure interaction phenomenon. Various
cosmological scenarios that describe a present stage of accelerated expansion,
like the LCDM model or a (generalized) Chaplygin gas, follow as special cases
for different interaction rates. This unifying view on the homogeneous and
isotropic background level is accompanied by a non-adiabatic perturbation
dynamics which can be seen as a consequence of a fluctuating interaction rate.


title:
Observation of Exciton-Phonon Sideband in Individual Metallic
  Single-Walled Carbon Nanotubes

abstract:
  Single-walled carbon nanotubes (SWCNTs) are quasi-one-dimensional systems
with poor Coulomb screening and enhanced electron-phonon interaction, and are
good candidates for excitons and exciton-phonon couplings in metallic state.
Here we report back scattering reflection experiments on individual metallic
SWCNTs. An exciton-phonon sideband separated by 0.19 eV from the first optical
transition peak is observed in a metallic SWCNT of chiral index (13,10), which
provides clear evidences of excitons in metallic SWCNTs. A static dielectric
constant of 10 is estimated from the reflectance spectrum.


title: Interpretation of Solar Magnetic Field Strength Observations

abstract:
  This study based on longitudinal Zeeman effect magnetograms and spectral line
scans investigates the dependence of solar surface magnetic fields on the
spectral line used and the way the line is sampled in order to estimate the
magnetic flux emerging above the solar atmosphere and penetrating to the corona
from magnetograms of the Mt. Wilson 150-foot tower synoptic program (MWO). We
have compared the synoptic program \lambda5250\AA line of Fe I to the line of
Fe I at \lambda5233\AA since this latter line has a broad shape with a profile
that is nearly linear over a large portion of its wings. The present study uses
five pairs of sampling points on the $\lambda5233$\AA line. We recommend
adoption of the field determined with a line bisector method with a sampling
point as close as possible to the line core as the best estimate of the
emergent photospheric flux. The combination of the line profile measurements
and the cross-correlation of fields measured simultaneously with \lambda5250\AA
and \lambda5233\AA yields a formula for the scale factor 1/\delta that
multiplies the MWO synoptic magnetic fields. The new calibration shows that
magnetic fields measured by the MDI system on the SOHO spacecraft are equal to
0.619+/-0.018 times the true value at a center-to-limb position 30 deg. Berger
and Lites (2003) found this factor to be 0.64+/-0.013 based on a comparison the
the Advanced Stokes Polarimeter.


title: A two-state Raman coupler for coherent atom optics

abstract:
  We present results on a Raman laser-system that resonantly drives a closed
two-photon transition between two levels in different hyperfine ground states
of 87Rb. The coupler is based on a novel optical design for producing two
phase-coherent optical beams to drive a Raman transition. Operated as an
outcoupler, it produces an atom laser in a single internal atomic state, with
the lower divergence and increased brightness typical of a Raman outcoupler.
Due to the optical nature of the outcoupling, the two-state outcoupler is an
ideal candidate for transferring photon correlations onto atom-laser beams. As
our laser system couples just two hyperfine ground states, it has also been
used as an internal state beamsplitter, taking the next major step towards free
space Ramsey interferometry with an atom laser.


title:
Exact dynamical exchange-correlation kernel of a weakly inhomogeneous
  electron gas

abstract:
  The dynamical exchange-correlation kernel $f_{xc}$ of a non-uniform electron
gas is an essential input for the time-dependent density functional theory of
electronic systems. The long-wavelength behavior of this kernel is known to be
of the form $f_{xc}= \alpha/q^2$ where $q$ is the wave vector and $\alpha$ is a
frequency-dependent coefficient. We show that in the limit of weak
non-uniformity the coefficient $\alpha$ has a simple and exact expression in
terms of the ground-state density and the frequency-dependent kernel of a {\it
uniform} electron gas at the average density. We present an approximate
evaluation of this expression for Si and discuss its implications for the
theory of excitonic effects.


title:
The Role of Angular Momentum and Cosmic Censorship in the
  (2+1)-Dimensional Rotating Shell Collapse

abstract:
  We study the gravitational collapse problem of rotating shells in
three-dimensional Einstein gravity with and without a cosmological constant.
Taking the exterior and interior metrics to be those of stationary metrics with
asymptotically constant curvature, we solve the equations of motion for the
shells from the Darmois-Israel junction conditions in the "co-rotating" frame.
We study various collapse scenarios with "arbitrary" angular momentum for a
variety of geometric configurations, including anti-de Sitter, de Sitter, and
flat spaces. We find that the collapsing shells can form a BTZ black hole, a
three-dimensional Kerr-dS spacetime, and an horizonless geometry of point
masses under certain initial conditions. For pressureless dust shells, the
curvature singularity is "not" formed due to the angular momentum barrier near
the origin. However when the shell pressure is nonvanishing, we find that for
all types of shells with polytropic-type equations of state (including the
perfect fluid and the generalized Chaplygin gas), collapse to a naked
singularity is "possible" under generic initial conditions. We conclude that in
three dimensions angular momentum does not in general guard against violation
of cosmic censorship.


title: Efficient Isomorphism Testing for a Class of Group Extensions

abstract:
  The group isomorphism problem asks whether two given groups are isomorphic or
not. Whereas the case where both groups are abelian is well understood and can
be solved efficiently, very little is known about the complexity of isomorphism
testing for nonabelian groups. In this paper we study this problem for a class
of groups corresponding to one of the simplest ways of constructing nonabelian
groups from abelian groups: the groups that are extensions of an abelian group
A by a cyclic group of order m. We present an efficient algorithm solving the
group isomorphism problem for all the groups of this class such that the order
of A is coprime with m. More precisely, our algorithm runs in time almost
linear in the orders of the input groups and works in the general setting where
the groups are given as black-boxes.


title:
Human group formation in online guilds and offline gangs driven by
  common team dynamic

abstract:
  Quantifying human group dynamics represents a unique challenge. Unlike
animals and other biological systems, humans form groups in both real (offline)
and virtual (online) spaces -- from potentially dangerous street gangs
populated mostly by disaffected male youths, through to the massive global
guilds in online role-playing games for which membership currently exceeds tens
of millions of people from all possible backgrounds, age-groups and genders. We
have compiled and analyzed data for these two seemingly unrelated offline and
online human activities, and have uncovered an unexpected quantitative link
between them. Although their overall dynamics differ visibly, we find that a
common team-based model can accurately reproduce the quantitative features of
each simply by adjusting the average tolerance level and attribute range for
each population. By contrast, we find no evidence to support a version of the
model based on like-seeking-like (i.e. kinship or `homophily').


title: A characterization of well-founded algebraic lattices

abstract:
  We characterize well-founded algebraic lattices by means of forbidden
subsemilattices of the join-semilattice made of their compact elements. More
specifically, we show that an algebraic lattice $L$ is well-founded if and only
if $K(L)$, the join-semilattice of compact elements of $L$, is well-founded and
contains neither $[\omega]^{<\omega}$, nor $\underline\Omega(\omega^*)$ as a
join-subsemilattice. As an immediate corollary, we get that an algebraic
modular lattice $L$ is well-founded if and only if $K(L)$ is well-founded and
contains no infinite independent set. If $K(L)$ is a join-subsemilattice of
$I_{<\omega}(Q)$, the set of finitely generated initial segments of a
well-founded poset $Q$, then $L$ is well-founded if and only if $K(L)$ is
well-quasi-ordered.


title:
Cooperative Hybrid ARQ Protocols: Unified Frameworks for Protocol
  Analysis

abstract:
  Cooperative hybrid-ARQ (HARQ) protocols, which can exploit the spatial and
temporal diversities, have been widely studied. The efficiency of cooperative
HARQ protocols is higher than that of cooperative protocols, because
retransmissions are only performed when necessary. We classify cooperative HARQ
protocols as three decode-and-forward based HARQ (DF-HARQ) protocols and two
amplified-and-forward based (AF-HARQ) protocols. To compare these protocols and
obtain the optimum parameters, two unified frameworks are developed for
protocol analysis. Using the frameworks, we can evaluate and compare the
maximum throughput and outage probabilities according to the SNR, the relay
location, and the delay constraint for the protocols.


title:
Strong field effects on pulsar arrival times: circular orbits and
  equatorial beams

abstract:
  If a pulsar orbits a supermassive black hole, the timing of pulses that pass
close to the hole will show a variety of strong field effects. To compute the
intensity and timing of pulses that have passed close to a nonrotating black
hole we introduce here a simple formalism based on two "universal functions,"
one for the bending of photon trajectories and the other for the photon travel
time on these trajectories. We apply this simple formalism to the case of a
pulsar in circular orbit that beams its pulses into the orbital plane. In
addition to the "primary" pulses that reach the receiver by a more-or-less
direct path, we find that there are secondary and higher order pulses. These
are usually much dimmer than the primary pulses, but they can be of comparable
or even greater intensity if they are emitted when pulsar is on the side of the
hole furthest from the receiver. We show that there is a phase relationship of
the primary and secondary pulses that is a probe of the strongly curved
spacetime geometry. Analogs of these phenomena are expected in more general
configurations, in which a pulsar in orbit around a hole emits pulses that are
not confined to the orbital plane.


abstract:
  In this article we derive Fokker - Planck equation for incompressible fluid
and investigate its properties. In version 2 symmetries of linearized equations
and some examples of invariant solutions are added.


title:
Fermi Liquid Model of Radiation Induced Magnetoresistance Oscillations
  in GaAs/Al$_x$Ga$_{1-x}$As Heterostructure Two-Dimensional Electron System:
  Theoretical Evidence of an Electron Reservoir

abstract:
  The magnetoresistance oscillations in GaAs/Al$_x$Ga$_{1-x}$As
heterostructures induced by millimeterwave radiation recently observed by Zudov
et al. [Phys. Rev. B {\bf 64}, 201311 (2001)] is theoretically reproduced by
introducing a model based on the finite temperature Fermi liquid theory of dc
conductivity and the electron reservoir hypothesis. The obtained oscillation
patterns show excellent agreement with the experimental result by Zudov et al.
and are independent of the polarization of the radiation field in accordance
with the experimental observation by Smet et al. [Phys. Rev. Lett. {\bf 95},
116804 (2005)].


title:
The structure of surfaces and threefolds mapping to the moduli stack of
  canonically polarized varieties

abstract:
  Generalizing the well-known Shafarevich hyperbolicity conjecture, it has been
conjectured by Viehweg that a quasi-projective manifold that admits a
generically finite morphism to the moduli stack of canonically polarized
varieties is necessarily of log general type. Given a quasi-projective
threefold Y that admits a non-constant map to the moduli stack, we employ
extension properties of logarithmic pluri-forms to establish a strong
relationship between the moduli map and the minimal model program of Y: in all
relevant cases the minimal model program leads to a fiber space whose fibration
factors the moduli map. A much refined affirmative answer to Viehweg's
conjecture for families over threefolds follows as a corollary. For families
over surfaces, the moduli map can be often be described quite explicitly.
  Slightly weaker results are obtained for families of varieties with trivial,
or more generally semi-ample canonical bundle.


title: Fermionic formulas for eigenfunctions of the difference Toda Hamiltonian

abstract:
  We use the Whittaker vectors and the Drinfeld Casimir element to show that
eigenfunctions of the difference Toda Hamiltonian can be expressed via
fermionic formulas. Motivated by the combinatorics of the fermionic formulas we
use the representation theory of the quantum groups to prove a number of
identities for the coefficients of the eigenfunctions.


title: A Note on Normal Forms of Quantum States and Separability

abstract:
  We study the normal form of multipartite density matrices. It is shown that
the correlation matrix (CM) separability criterion can be improved from the
normal form we obtained under filtering transformations. Based on CM criterion
the entanglement witness is further constructed in terms of local orthogonal
observables for both bipartite and multipartite systems.


title: Ballistic aggregation for one-sided Brownian initial velocity

abstract:
  We study the one-dimensional ballistic aggregation process in the continuum
limit for one-sided Brownian initial velocity (i.e. particles merge when they
collide and move freely between collisions, and in the continuum limit the
initial velocity on the right side is a Brownian motion that starts from the
origin $x=0$). We consider the cases where the left side is either at rest or
empty at $t=0$. We derive explicit expressions for the velocity distribution
and the mean density and current profiles built by this out-of-equilibrium
system. We find that on the right side the mean density remains constant
whereas the mean current is uniform and grows linearly with time. All
quantities show an exponential decay on the far left. We also obtain the
properties of the leftmost cluster that travels towards the left. We find that
in both cases relevant lengths and masses scale as $t^2$ and the evolution is
self-similar.


title:
Classification of Cell Images Using MPEG-7-influenced Descriptors and
  Support Vector Machines in Cell Morphology

abstract:
  Counting and classifying blood cells is an important diagnostic tool in
medicine. Support Vector Machines are increasingly popular and efficient and
could replace artificial neural network systems. Here a method to classify
blood cells is proposed using SVM. A set of statistics on images are
implemented in C++. The MPEG-7 descriptors Scalable Color Descriptor, Color
Structure Descriptor, Color Layout Descriptor and Homogeneous Texture
Descriptor are extended in size and combined with textural features
corresponding to textural properties perceived visually by humans. From a set
of images of human blood cells these statistics are collected. A SVM is
implemented and trained to classify the cell images. The cell images come from
a CellaVision DM-96 machine which classify cells from images from microscopy.
The output images and classification of the CellaVision machine is taken as
ground truth, a truth that is 90-95% correct. The problem is divided in two --
the primary and the simplified. The primary problem is to classify the same
classes as the CellaVision machine. The simplified problem is to differ between
the five most common types of white blood cells. An encouraging result is
achieved in both cases -- error rates of 10.8% and 3.1% -- considering that the
SVM is misled by the errors in ground truth. Conclusion is that further
investigation of performance is worthwhile.


title: Ramsey interferometry with an atom laser

abstract:
  We present results on a free-space atom interferometer operating on the first
order magnetically insensitive |F=1,mF=0> -> |F=2,mF=0> transition of
Bose-condensed 87Rb atoms. A pulsed atom laser is output-coupled from a
Bose-Einstein condensate and propagates through a sequence of two internal
state beam splitters, realized via coherent Raman transitions between the two
interfering states. We observe Ramsey fringes with a visibility close to 100%
and determine the current and the potentially achievable interferometric phase
sensitivity. This system is well suited to testing recent proposals for
generating and detecting squeezed atomic states.


title: On extremal positive maps acting between type I factors

abstract:
  The paper is devoted to the problem of classification of extremal positive
maps acting between $B(K)$ and $B(H)$ where $K$ and $H$ are Hilbert spaces. It
is shown that every positive map with the property that $\rank \phi(P)\leq 1$
for any one-dimensional projection $P$ is a rank 1 preserver. It allows to
characterize all decomposable extremal maps as those which satisfy the above
condition. Further, we prove that every extremal positive map which is
2-positive turns out to automatically completely positive. Finally we get the
same conclusion for such extremal positive maps that $\rank \phi(P)\leq 1$ for
some one-dimensional projection $P$ and satisfy the condition of local complete
positivity. It allows us to give a negative answer for Robertson's problem in
some special cases.


title: $B_{s} \to PP $ decays and the NLO contributions in the pQCD Approach

abstract:
  By employing the perturbative QCD(pQCD) factorization approach, we calculated
the partial next-to-leading order (NLO) contributions to $B_s \to P P$ decays
($P= \pi, K, \etap $), coming from the QCD vertex corrections, the quark-loops
and the chromo-magnetic penguins. we found numerically that (a) for three
measured decays $\bar{B}_s \to K^+ \pi^-, K^+K^-$ and $\pi^+\pi^-$, the
consistency between the pQCD predictions and the measured values are improved
effectively by the inclusion of the NLO contributions; (b) for $\bar{B}_s \to
K^0\etap$ and $K^0\pi^0$ decays, the NLO enhancements to the branching ratios
can be significant, from $\sim 50%$ to 170%, to be tested by the LHC
experiments; (c) for the CP-violating asymmetries, the leading order pQCD
predictions can also be changed significantly by the inclusion of the NLO
contributions; (d) for $\bar{B}_s \to K^+\pi^-$ decay, the pQCD prediction for
the direct CP asymmetry is $\acp^{dir}(\bar{B}_s \to K^+\pi^-)=0.26\pm 0.06$,
which agrees very well with the only measured value available currently.


title: Urologic robots and future directions

abstract:
  PURPOSE OF REVIEW: Robot-assisted laparoscopic surgery in urology has gained
immense popularity with the daVinci system, but a lot of research teams are
working on new robots. The purpose of this study is to review current urologic
robots and present future development directions. RECENT FINDINGS: Future
systems are expected to advance in two directions: improvements of remote
manipulation robots and developments of image-guided robots. SUMMARY: The final
goal of robots is to allow safer and more homogeneous outcomes with less
variability of surgeon performance, as well as new tools to perform tasks on
the basis of medical transcutaneous imaging, in a less invasive way, at lower
costs. It is expected that improvements for a remote system could be augmented
in reality, with haptic feedback, size reduction, and development of new tools
for natural orifice translumenal endoscopic surgery. The paradigm of
image-guided robots is close to clinical availability and the most advanced
robots are presented with end-user technical assessments. It is also notable
that the potential of robots lies much further ahead than the accomplishments
of the daVinci system. The integration of imaging with robotics holds a
substantial promise, because this can accomplish tasks otherwise impossible.
Image-guided robots have the potential to offer a paradigm shift.