title: Bertrand spacetimes as Kepler/oscillator potentials

abstract:
  Perlick's classification of (3+1)-dimensional spherically symmetric and
static spacetimes (\cal M,\eta=-1/V dt^2+g) for which the classical Bertrand
theorem holds [Perlick V Class. Quantum Grav. 9 (1992) 1009] is revisited. For
any Bertrand spacetime (\cal M,\eta) the term V(r) is proven to be either the
intrinsic Kepler-Coulomb or the harmonic oscillator potential on its associated
Riemannian 3-manifold (M,g). Among the latter 3-spaces (M,g) we explicitly
identify the three classical Riemannian spaces of constant curvature, a
generalization of a Darboux space and the Iwai-Katayama spaces generalizing the
MIC-Kepler and Taub-NUT problems. The key dynamical role played by the Kepler
and oscillator potentials in Euclidean space is thus extended to a wide class
of 3-dimensional curved spaces.


title: Persistence of normally expanded submanifolds with boundary or corners

abstract:
  We show that invariant submanifolds with boundary, and more generally with
corners which are normally expanded by an endomorphism are persistent as
$a$-regular stratifications. This result will be shown in class $C^s$, for
$s\ge 1$. We present also a simple example of a submanifold with boundary which
is normally expanded but non-persistent as a differentiable submanifold.


title: The thermodynamic approach to market

abstract:
  The first (Russian) edition of the book was among the first monographs on
econophysics. The book gives an explanation of several intriguing phenomena,
providing new insights and answers to some deeply vexing questions.
  Why the economic "shock therapy" implemented in Eastern Europe was doomed to
a failure whereas the approach adopted by China and Vietnam should inevitably
lead to economic growth (damped, perhaps, by corruption and inconsistencies)?
  Why some restrictions imposed on markets are dangerous? Politicians (and
laymen) usually believe that the more restrictions you impose on the society,
the easier it is to govern. The reality seems to be more subtle. Some
restrictions are necessary for the markets to function. However, restrictions
on salary, for example, seem to always result in unemployment, as a simple
"spin" model shows. Evidently, optimizing freedom is an equilibrium problem,
and none of the extrema is devoid of danger.
  Why should crooked dealings be prevented?
  What is a reasonable rate of taxation, if any such exists?
  Other questions abound, raising many points of interest.
  Appendices contain an essay which informally can be entitled "Why mathematics
and physics major should study economics" and a deep mathematical paper
summarizing a century long study of nonholonomic systems (such as ideal gas or
market economy) in the quest for an analog of the curvature tensor in
nonholonomic setting.


title: Perturbed Kerr Black Holes can probe deviations from General Relativity

abstract:
  Although the Kerr solution is common to many gravity theories, its
perturbations are different in different theories. Hence, perturbed Kerr black
holes can probe deviations from General Relativity.


title: Super-Zeeman Embedding Models on N-Supersymmetric World-Lines

abstract:
  We construct a model of an electrically charged magnetic dipole with
arbitrary N-extended world-line supersymmetry, which exhibits a supersymmetric
Zeeman effect. By including supersymmetric constraint terms, the ambient space
of the dipole may be tailored into an algebraic variety, and the supersymmetry
broken for almost all parameter values. The so exhibited obstruction to
supersymmetry breaking refines the standard one, based on the Witten index
alone.


title: Twenty-Five Moves Suffice for Rubik's Cube

abstract:
  How many moves does it take to solve Rubik's Cube? Positions are known that
require 20 moves, and it has already been shown that there are no positions
that require 27 or more moves; this is a surprisingly large gap. This paper
describes a program that is able to find solutions of length 20 or less at a
rate of more than 16 million positions a second. We use this program, along
with some new ideas and incremental improvements in other techniques, to show
that there is no position that requires 26 moves.


title: Influence of Speed Limit on Roadway Safety in Indiana

abstract:
  The influence of speed limits on roadway safety is an extremely important
social issue and is subject to an extensive debate in the State of Indiana and
nationwide. With around 800-900 fatalities and thousands of injuries annually
in Indiana, traffic accidents place an incredible social and economic burden on
the state. Still, speed limits posted on highways and other roads are routinely
exceeded as individual drivers try to balance safety and mobility (speed). This
research explores the relationship between speed limits and roadway safety.
Namely, the research focuses on the influence of the posted speed limit on the
causation and severity of accidents. Data on individual accidents from the
Indiana Electronic Vehicle Crash Record System is used in the research, and
appropriate statistical models are estimated for causation and severity of
different types of accidents on all road classes. The results of the modeling
show that speed limits do not have a statistically significant adverse effect
on unsafe-speed-related causation of accidents on all roads, but generally
increase the severity of accidents on the majority of roads other than highways
(the accident severity on highways is unaffected by speed limits). Our findings
can perhaps save both lives and travel time by helping the Indiana Department
of Transportation determine optimal speed limit policies in the state.


title:
Role of attractive methane-water interactions in the potential of mean
  force between methane molecules in water

abstract:
  On the basis of a gaussian quasi-chemical model of hydration, a model of non
van der Waals character, we explore the role of attractive methane-water
interactions in the hydration of methane and in the potential of mean force
between two methane molecules in water. We find that the hydration of methane
is dominated by packing and a mean-field energetic contribution. Contributions
beyond the mean-field term are unimportant in the hydration phenomena for a
hydrophobic solute such as methane. Attractive solute-water interactions make a
net repulsive contribution to these pair potentials of mean force. With no
conditioning, the observed distributions of binding energies are super-gaussian
and can be effectively modeled by a Gumbel (extreme value) distribution. This
further supports the view that the characteristic form of the unconditioned
distribution in the high-e tail is due to energetic interactions with a small
number of molecules. Generalized extreme value distributions also effectively
model the results with minimal conditioning, but in those cases the
distributions are sufficiently narrow that details of their shape aren't
significant.


title:
Bulk viscosity of the Lennard-Jones system at the triple point by
  dynamical Non Equilibrium Molecular Dynamics

abstract:
  Non-equilibrium Molecular Dynamics (NEMD) calculations of the bulk viscosity
of the triple point Lennard-Jones fluid are performed with the aim of
investigating the origin of the observed disagreement between Green-Kubo
estimates and previous NEMD data. We show that a careful application of the
Doll's perturbation field, the dynamical NEMD method, the instantaneous form of
the perturbation and the "subtraction technique" provides a NEMD estimate of
the bulk viscosity at zero field in full agreement with the value obtained by
the Green-Kubo formula. As previously reported for the shear viscosity, we find
that the bulk viscosity exhibits a large linear regime with the field intensity
which confirms the Lennard-Jones fluid as a genuine Newtonian fluid even at
triple point.


title:
Theoretical study of the intrinsic magnetic properties of disordered
  $Fe_{1-x}Ru_x$ alloys: a mean-field approach

abstract:
  The magnetic properties of the $Fe_{1-x}Ru_x$ alloy system for 0 $\leq$ x
$\leq$ 0.10 are studied by using a mean-field approximation based on the
Bogoliubov inequality. Ferromagnetic Fe-Fe spin correlations and
antiferromagnetic Fe-Ru and Ru-Ru exchanges have been considered to describe
the temperature dependence of the Curie temperature and low temperature
magnetization. A composition dependence has been imposed in the exchange
couplings, as indicated by experiments. From a least-square fitting procedure
to the experimental results an estimation of the interaction parameters was
obtained, which yielded the low temperature dependence of the magnetization and
of the ferromagnetic Curie temperature. A good agreement was obtained with
available experimental results.


title: Manipulating a single adsorbed DNA for a critical endpoint

abstract:
  We show the existence of a critical endpoint in the phase diagram of
unzipping of an adsorbed double-stranded (ds) polymer like DNA. The competition
of base pairing, adsorption and stretching by an external force leads to the
critical end point. From exact results, the location of the critical end point
is determined and its classical nature established.


title: SiFTO: An Empirical Method for Fitting SNe Ia Light Curves

abstract:
  We present SiFTO, a new empirical method for modeling type Ia supernovae (SNe
Ia) light curves by manipulating a spectral template. We make use of
high-redshift SN observations when training the model, allowing us to extend it
bluer than rest frame U. This increases the utility of our high-redshift SN
observations by allowing us to use more of the available data. We find that
when the shape of the light curve is described using a stretch prescription,
applying the same stretch at all wavelengths is not an adequate description.
SiFTO therefore uses a generalization of stretch which applies different
stretch factors as a function of both the wavelength of the observed filter and
the stretch in the rest-frame B band. We compare SiFTO to other published
light-curve models by applying them to the same set of SN photometry, and
demonstrate that SiFTO and SALT2 perform better than the alternatives when
judged by the scatter around the best fit luminosity distance relationship. We
further demonstrate that when SiFTO and SALT2 are trained on the same data set
the cosmological results agree.


title:
Non-minimal pp-wave Einstein-Yang-Mills-Higgs model: color cross-effects
  induced by curvature

abstract:
  Non-minimal interactions in the pp-wave Einstein - Yang - Mills - Higgs
(EYMH) model are shown to give rise to color cross-effects analogous to the
magneto-electricity in the Maxwell theory. In order to illustrate the
significance of these color cross-effects, we reconstruct the effective
(associated, color and color-acoustic) metrics for the pp-wave non-minimal
seven-parameter EYMH model with parallel gauge and scalar background fields.
Then these metrics are used as hints for obtaining explicit exact solutions of
the non-minimally extended Yang-Mills and Higgs equations for the test fields
propagating in the vacuum interacting with curvature. The influence of the
non-minimal coupling on the test particle motion is interpreted in terms of the
so-called trapped surfaces, introduced in the Analog Gravity theory.


title:
Can a double stranded DNA be unzipped by pulling a single strand?:
  Phases of adsorbed DNA

abstract:
  We study the unzipping of a double stranded DNA (dsDNA) by applying an
external force on a single strand while leaving the other strand free. We find
that the dsDNA can be unzipped to two single strands if the external force
exceeds a critical value. We obtain the phase diagram which is found to be
different from the phase diagram of unzipping by pulling both the strands in
opposite directions. In the presence of an attractive surface near DNA, the
phase diagram gets modified drastically and shows richer surprises including a
critical end point and a triple point.


title:
The Equations of Singular Loci of Ample Divisors on (Subvarieties of)
  Abelian Varieties

abstract:
  In this paper we consider ideal sheaves associated to the singular loci of a
divisor in a linear system $|L|$ of an ample line bundle on a complex abelian
variety. We prove an effective result on their (continuous) global generation,
after suitable twists by powers of $L$. Moreover we show that similar results
hold for subvarieties of a complex abelian variety.


title:
Thermodynamics with an Action Principle, heat and gravitation (2nd
  version)

abstract:
  Some features of hydro- and thermodynamics, as applied to atmospheres and to
stellar structures, are puzzling: 1. The suggestion, first made by Laplace,
that our atmosphere has an adiabatic temperature distribution, is confirmed for
the lower layers, but the reason why it should be so is understood only
qualitatively. 2. Arguments in which a concept of energy plays a role, in the
context of hydro-thermodynamical systems and gravitation, are often flawed, and
some familiar results concerning the stability of model stellar structures,
first advanced at the end of the 19th century and repeated in the most modern
textbooks, are less than completely convincing. 3. The standard treatment of
relativistic thermodynamics does not allow for a systematic treatment of
mixtures, such as the mixture of a perfect gas with radiation. 4. The concept
of mass in applications of general relativity to stellar structure is
unsatisfactory. It is proposed that a formulation of thermodynamics as an
action principle may be a suitable approach to adopt for a new investigation of
these matters.
  We formulate thermodynamics of ideal gases in terms of an action principle
and study the interaction between an ideal gas and the photon gas, or heat. The
action principle provides a hamiltonian functional, not available in
traditional approaches where familiar expressions for the energy have no
operative meaning. The usual polytropic atmosphere in an external gravitational
field is examined, in order to determine to what extent it is shaped by
radiation.
  A new formulation of the concept of radiative equilibrium is proposed.


title: Hitting time for the continuous quantum walk

abstract:
  We define the hitting (or absorbing) time for the case of continuous quantum
walks by measuring the walk at random times, according to a Poisson process
with measurement rate $\lambda$. From this definition we derive an explicit
formula for the hitting time, and explore its dependence on the measurement
rate. As the measurement rate goes to either 0 or infinity the hitting time
diverges; the first divergence reflects the weakness of the measurement, while
the second limit results from the Quantum Zeno effect. Continuous-time quantum
walks, like discrete-time quantum walks but unlike classical random walks, can
have infinite hitting times. We present several conditions for existence of
infinite hitting times, and discuss the connection between infinite hitting
times and graph symmetry.


title: Intrinsic and Fundamental Decoherence: Issues and Problems

abstract:
  We investigate the meaning of gravity-induced decoherence in quantum theory,
known as `intrinsic' or `fundamental' decoherence in the literature. We explore
a range of issues relevant to this problem, including the meaning of modified
uncertainty relations, the interpretations of the Planck scale, the distinction
between quantum and stochastic fluctuations and the role of the time variable
in quantum mechanics. We examine the specific physical assumptions that enter
into different approaches to the subject. In particular, we critique two
representative approaches that identify time fluctuations as the origin of
intrinsic or fundamental decoherence: one that models the fluctuations by
stochastic process and one that purports to derive decoherence from the quantum
fluctuations of real clocks.


title:
Secure Hop-by-Hop Aggregation of End-to-End Concealed Data in Wireless
  Sensor Networks

abstract:
  In-network data aggregation is an essential technique in mission critical
wireless sensor networks (WSNs) for achieving effective transmission and hence
better power conservation. Common security protocols for aggregated WSNs are
either hop-by-hop or end-to-end, each of which has its own encryption schemes
considering different security primitives. End-to-end encrypted data
aggregation protocols introduce maximum data secrecy with in-efficient data
aggregation and more vulnerability to active attacks, while hop-by-hop data
aggregation protocols introduce maximum data integrity with efficient data
aggregation and more vulnerability to passive attacks.
  In this paper, we propose a secure aggregation protocol for aggregated WSNs
deployed in hostile environments in which dual attack modes are present. Our
proposed protocol is a blend of flexible data aggregation as in hop-by-hop
protocols and optimal data confidentiality as in end-to-end protocols. Our
protocol introduces an efficient O(1) heuristic for checking data integrity
along with cost-effective heuristic-based divide and conquer attestation
process which is $O(\ln{n})$ in average -O(n) in the worst scenario- for
further verification of aggregated results.


title: Local theta correspondence and the lifting of Duke, Imamoglu and Ikeda

abstract:
  We use results on the local theta correspondence to prove that for large
degrees the Duke-Imamoglu-Ikeda lifting of an elliptic modular form is not a
linear combination of theta series.


title:
Testing a Neutrino Mass Generation Mechanism at the Large Hadron
  Collider

abstract:
  The Large Hadron Collider could be a discovery machine for the neutrino mass
pattern and its Majorana nature in the context of a well-motivated TeV scale
Type II seesaw model. This is achieved by identifying the flavor structure of
the lepton number violating decays of the charged Higgs bosons. The observation
of either H^+ --> tau^+ nubar or H^+ --> e^+ nubar will be particularly robust
to determine the neutrino spectra since they are independent of the unknown
Majorana phases, which could be probed via the H^{++} --> e^+_i e^+_j decays.
In a less favorable scenario when the leptonic channels are suppressed, one
needs to observe the decays H^+ --> W^+ H_1, and H^+ --> t bbar to confirm the
triplet-doublet mixing that implies the Type II relation. The associated
production H^{++} H^{-} is crucial in order to test the triplet nature of the
Higgs field.


title: Excitonic condensation of massless fermions in graphene bilayers

abstract:
  Graphene, a single sheet of graphite with honeycomb lattice structure, has
massless carriers with tunable density and polarity. We investigate the ground
state phase diagram of two graphene sheets (embedded in a dielectric) separated
by distance $d$ where the top layer has electrons and the bottom layer has
holes, using mean-field theory. We find that a uniform excitonic condensate
occurs over a large range of carrier densities and is weakly dependent on the
relative orientation of the two sheets. We obtain the excitonic gap,
quasiparticle energy and the density of states. We show that both, the
condensate phase stiffness and the mass of the excitons, with massless
particles as constituents, vary as the square-root of the carrier density, and
predict that the condensate will not undergo Wigner crystallization.


title: Quantum decoherence of a charge qubit in a spin-fermion model

abstract:
  We consider quantum decoherence in solid-state systems by studying the
transverse dynamics of a single qubit interacting with a fermionic bath and
driven by external pulses. Our interest is in investigating the extent to which
the lost coherence can be restored by the application of external pulses to the
qubit. We show that the qubit evolution under various pulse sequences can be
mapped onto Keldysh path integrals. This approach allows a simple diagrammatic
treatment of different bath excitation processes contributing to qubit
decoherence. We apply this theory to the evolution of the qubit coupled to the
Andreev fluctuator bath in the context of widely studied superconducting
qubits. We show that charge fluctuations within the Andreev-fluctuator model
lead to a 1/f noise spectrum with a characteristic temperature depedence. We
discuss the strategy for suppression of decoherence by the application of
higher-order (beyond spin echo) pulse sequences.


title: Halo Assembly Bias in Hierarchical Structure Formation

abstract:
  We investigate the origin of halo assembly bias, the dependence of halo
clustering on assembly history. We relate halo assembly to peak properties
measured in the Lagrangian space of the initial linear Gaussian random density
field, and show how these same Lagrangian properties determine large-scale
bias. We focus on the two regimes where assembly bias has been observed to be
significant: at masses very large and very small compared to the nonlinear mass
scale. At high masses, we show that assembly bias is expected from the
statistics of the peaks of Gaussian random fluctuations, and we show that the
extent of assembly bias found in N-body simulations of rare halos is in
excellent agreement with our theoretical prediction. At low masses, we argue
that assembly bias largely arises from a sub-population of low mass halos whose
mass accretion has ceased. Due to their arrested development, these halos
naturally become unbiased, in contrast to their anti-biased peers. We show that
a simple toy model incorporating these effects can roughly reproduce the bias
trends found in N-body simulations.


title: Fossil Ionized Bubbles Around Dead Quasars During Reionization

abstract:
  One of the most dramatic signatures of the reionization era may be the
enormous ionized bubbles around luminous quasars (with radii reaching ~40
comoving Mpc), which may survive as "fossil'' ionized regions long after their
source shuts off. Here we study how the inhomogeneous intergalactic medium
(IGM) evolves inside such fossils. The average recombination rate declines
rapidly with time, and the brief quasar episode significantly increases the
mean free path inside the fossil bubbles. As a result, even a weak ionizing
background generated by galaxies inside the fossil can maintain it in a
relatively highly and uniformly ionized state. For example, galaxies that would
ionize 20-30% of hydrogen in a random patch of the IGM can maintain 80-90%
ionization inside the fossil, for a duration much longer than the average
recombination time in the IGM. Quasar fossils at z<10 thus retain their
identity for nearly a Hubble time, and will appear "gray,'' distinct from both
the average IGM (which has a "swiss-cheese" ionization topology and a lower
mean ionized fraction), and from fully-ionized bubbles around active quasars.
More distant fossils, at z>10 have a weaker galaxy-generated ionizing
background and a higher gas density, so they can attain a swiss-cheese topology
similar to the rest of the IGM, but with a smaller contrast between the ionized
bubbles and the partially neutral regions separating them. Analogous
HeIII-fossils should exist around the epoch of HeII/HeIII reionization at z~3,
although rapid recombinations inside the HeIII-fossils will be more common. Our
model of inhomogeneous recombination also applies to "double reionization''
models and shows that a non-monotonic reionization history is even more
unlikely than previously thought.


title: A Local Mean Field Analysis of Security Investments in Networks

abstract:
  Getting agents in the Internet, and in networks in general, to invest in and
deploy security features and protocols is a challenge, in particular because of
economic reasons arising from the presence of network externalities. Our goal
in this paper is to carefully model and quantify the impact of such
externalities on the investment in, and deployment of, security features and
protocols in a network.
  Specifically, we study a network of interconnected agents, which are subject
to epidemic risks such as those caused by propagating viruses and worms, and
which can decide whether or not to invest some amount to self-protect and
deploy security solutions. We make three contributions in the paper. First, we
introduce a general model which combines an epidemic propagation model with an
economic model for agents which captures network effects and externalities.
Second, borrowing ideas and techniques used in statistical physics, we
introduce a Local Mean Field (LMF) model, which extends the standard mean-field
approximation to take into account the correlation structure on local
neighborhoods. Third, we solve the LMF model in a network with externalities,
and we derive analytic solutions for sparse random graphs, for which we obtain
asymptotic results. We explicitly identify the impact of network externalities
on the decision to invest in and deploy security features. In other words, we
identify both the economic and network properties that determine the adoption
of security technologies.


title: Is Quantum Gravity Necessary?

abstract:
  In view of the enormous difficulties we seem to face in quantizing general
relativity, we should perhaps consider the possibility that gravity is a
fundamentally classical interaction. Theoretical arguments against such mixed
classical-quantum models are strong, but not conclusive, and the question is
ultimately one for experiment. I review some work in progress on the
possibility of experimental tests, exploiting the nonlinearity of the
classical-quantum coupling, that could help settle this question.


title: Atomic Processes in Planetary Nebulae and H II Regions

abstract:
  Spectroscopic studies of Planetary Nebulae (PNe) and H {\sc ii} regions have
driven much development in atomic physics. In the last few years the
combination of a generation of powerful observatories, the development of ever
more sophisticated spectral modeling codes, and large efforts on mass
production of high quality atomic data have led to important progress in our
understanding of the atomic spectra of such astronomical objects. In this paper
I review such progress, including evaluations of atomic data by comparisons
with nebular spectra, detection of spectral lines from most iron-peak elements
and n-capture elements, observations of hyperfine emission lines and analysis
of isotopic abundances, fluorescent processes, and new techniques for
diagnosing physical conditions based on recombination spectra. The review is
directed toward atomic physicists and spectroscopists trying to establish the
current status of the atomic data and models and to know the main standing
issues.


title:
A Parameterization Invariant Approach to the Statistical Estimation of
  the CKM Phase $\alpha$

abstract:
  In contrast to previous analyses, we demonstrate a Bayesian approach to the
estimation of the CKM phase $\alpha$ that is invariant to parameterization. We
also show that in addition to {\em computing} the marginal posterior in a
Bayesian manner, the distribution must also be {\em interpreted} from a
subjective Bayesian viewpoint. Doing so gives a very natural interpretation to
the distribution. We also comment on the effect of removing information about
$\mathcal{B}^{00}$.


title: The QWalk Simulator of Quantum Walks

abstract:
  Several research groups are giving special attention to quantum walks
recently, because this research area have been used with success in the
development of new efficient quantum algorithms. A general simulator of quantum
walks is very important for the development of this area, since it allows the
researchers to focus on the mathematical and physical aspects of the research
instead of deviating the efforts to the implementation of specific numerical
simulations. In this paper we present QWalk, a quantum walk simulator for one-
and two-dimensional lattices. Finite two-dimensional lattices with generic
topologies can be used. Decoherence can be simulated by performing measurements
or by breaking links of the lattice. We use examples to explain the usage of
the software and to show some recent results of the literature that are easily
reproduced by the simulator.


title:
Density-density functionals and effective potentials in many-body
  electronic structure calculations

abstract:
  We demonstrate the existence of different density-density functionals
designed to retain selected properties of the many-body ground state in a
non-interacting solution starting from the standard density functional theory
ground state. We focus on diffusion quantum Monte Carlo applications that
require trial wave functions with optimal Fermion nodes. The theory is
extensible and can be used to understand current practices in several
electronic structure methods within a generalized density functional framework.
The theory justifies and stimulates the search of optimal empirical density
functionals and effective potentials for accurate calculations of the
properties of real materials, but also cautions on the limits of their
applicability. The concepts are tested and validated with a near-analytic
model.


title:
To Explain Results of Position Measurement by Self-Induced Photon
  Emission and Absorption

abstract:
  It is proposed in this paper that without a measurement, the wave function of
a system periodically transits to a bound energy eigenfunction or the
complementary wave function that is orthogonal to all the bound energy
eigenfunctions. Applying this assumption to analyze results of position
measurement shows that when the wave function of the entangled incident object
and a position detector is a linear combination of the bound energy
eigenfunctions of the entangled system prior to collapses, the detection rate
essentially equals the probability flux of the incident object entering the
detector. When the wave function of the entangled incident object and a
position detector is not a linear combination of the bound energy
eigenfunctions of the entangled system, results of position measurement can
also be explained by the proposed self-induced photon emission and absorption.


title:
A bright, dust-obscured, millimeter-selected galaxy beyond the Bullet
  Cluster (1E0657-56)

abstract:
  Deep 1.1 mm continuum observations of 1E0657-56 (the "Bullet Cluster") taken
with the millimeter-wavelength camera AzTEC on the 10-m Atacama Submillimeter
Telescope Experiment (ASTE), have revealed an extremely bright
(S$_{\rm{1.1mm}}=15.9$ mJy) unresolved source. This source, MMJ065837-5557.0,
lies close to a maximum in the density of underlying mass-distribution, towards
the larger of the two interacting clusters as traced by the weak-lensing
analysis of Clowe et al. 2006. Using optical--IR colours we argue that
MMJ065837-5557.0 lies at a redshift of $z = 2.7 \pm 0.2$. A lensing-derived
mass-model for the Bullet Cluster shows a critical-line (caustic) of
magnification within a few arcsecs of the AzTEC source, sufficient to amplify
the intrinsic millimeter-wavelength flux of the AzTEC galaxy by a factor of
$\gg 20$. After subtraction of the foreground cluster emission at 1.1mm due to
the Sunyaev-Zel'dovich effect, and correcting for the magnification, the
rest-frame FIR luminosity of MMJ065837-5557.0 is $\le 10^{12} \rm L_{\odot}$,
characteristic of a luminous infrared galaxy (LIRG). We explore various
scenarios to explain the colors, morphologies and positional offsets between
the potential optical and IR counterparts, and their relationship with
MMJ065837-5557.0. Until higher-resolution and more sensitive (sub)millimeter
observations are available, the detection of background galaxies close to the
caustics of massive lensing clusters offers the only opportunity to study this
intrinsically faint millimeter-galaxy population.


title: Periods for flat algebraic connections

abstract:
  In previous work, we established a duality between the algebraic de Rham
cohomology of a flat algebraic connection on a smooth quasi-projective surface
over the complex numbers and the rapid decay homology of the dual connection
relying on a conjecture by C. Sabbah, which has been proved recently by T.
Mochizuki for algebraic connections in any dimension. In the present article,
we verify that Mochizuki's results allow to generalize these duality results to
arbitrary dimensions also.


title:
Room Temperature All Semiconducting sub-10nm Graphene Nanoribbon
  Field-Effect Transistors

abstract:
  Sub-10nm wide graphene nanoribbon field-effect transistors (GNRFETs) are
studied systematically. All sub-10nm GNRs afforded semiconducting FETs without
exception, with Ion/Ioff ratio up to 10^6 and on-state current density as high
as ~2000uA/um. We estimated carrier mobility ~200cm2/Vs and scattering mean
free path ~10nm in sub-10nm GNRs. Scattering mechanisms by edges, acoustic
phonon and defects are discussed. The sub-10nm GNRFETs are comparable to small
diameter (d<=~1.2nm) carbon nanotube FETs with Pd contacts in on-state current
density and Ion/Ioff ratio, but have the advantage of producing
all-semiconducting devices.


title: Constraining The Early-Universe Baryon Density And Expansion Rate

abstract:
  We explore constraints on extensions to the standard models of cosmology and
particle physics which modify the early-Universe expansion rate S = H'/H
(parametrized by the effective number of neutrinos N_nu). The constraints on
N_nu and the baryon density parameter (eta_B = n_B/n_gamma = 10^(-10)*eta_10)
from BBN at 20 minutes are compared with those from the CMB at 400 kyr and LSS
at 14 Gyr. BBN provides the strongest constraint on N_nu (1.6 < N_nu < 3.3 at
95% confidence), but a weaker constraint on eta_B. The CMB/LSS best constrain
the baryon density (5.9 < eta_10 < 6.4 at 95% confidence), independent of N_nu,
but provide a relatively weak N_nu constraint, consistent with N_nu = 3. Using
the best fit values and the allowed ranges of the CMB/LSS-derived parameters to
calculate the BBN-predicted primordial abundances yields excellent agreement
with the observationally inferred abundance of deuterium and good agreement
with 4He, confirming the consistency between the BBN and CMB/LSS results.
However, the BBN-predicted abundance of 7Li is high, by a factor of 3 or more.
We comment on the value of N_nu and a possible anomaly in the matter power
spectrum inferred from observations of the Ly-alpha forest. The good agreement
between our BBN and CMB/LSS results permit us to constrain any post-BBN entropy
production as well as to limit the production of any non-thermalized
relativistic particles and, allow us to combine them finding 95% ranges, 1.8 <
N_nu < 3.2 and 5.9 < eta_10 < 6.4.


title: Turbulent magnetic pumping in a Babcock-Leighton solar dynamo model

abstract:
  The turbulent pumping effect corresponds to the transport of magnetic flux
due to the presence of density and turbulence gradients in convectively
unstable layers. In the induction equation it appears as an advective term and
for this reason it is expected to be important in the solar and stellar dynamo
processes. In this work, we have explored the effects of the turbulent pumping
in a flux-dominated Babcock-Leighton solar dynamo model with a solar-like
rotation law. The results reveal the importance of the pumping mechanism for
solving current limitations in mean field dynamo modeling such as the storage
of the magnetic flux and the latitudinal distribution of the sunspots. In the
case that a meridional flow is assumed to be present only in the upper part of
the convective zone, it is the full turbulent pumping that regulates both the
period of the solar cycle and the latitudinal distribution of the sunspots
activity.


title:
Deterministic excitable media under Poisson drive: power law responses,
  spiral waves and dynamic range

abstract:
  When each site of a spatially extended excitable medium is independently
driven by a Poisson stimulus with rate h, the interplay between creation and
annihilation of excitable waves leads to an average activity F. It has recently
been suggested that in the low-stimulus regime (h ~ 0) the response function
F(h) of hypercubic deterministic systems behaves as a power law, F ~ h^m.
Moreover the response exponent m has been predicted to depend only on the
dimensionality d of the lattice, m = 1/(1+d) [T. Ohta and T. Yoshimura, Physica
D 205, 189 (2005)]. In order to test this prediction, we study the response
function of excitable lattices modeled by either coupled Morris-Lecar equations
or Greenberg-Hastings cellular automata. We show that the prediction is
verified in our model systems for d = 1, 2, and 3, provided that a minimum set
of conditions is satisfied. Under these conditions, the dynamic range - which
measures the range of stimulus intensities that can be coded by the network
activity - increases with the dimensionality d of the network. The power law
scenario breaks down, however, if the system can exhibit self-sustained
activity (spiral waves). In this case, we recover a scenario that is common to
probabilistic excitable media: as a function of the conductance coupling G
among the excitable elements, the dynamic range is maximized precisely at the
critical value G_c above which self-sustained activity becomes stable. We
discuss the implications of these results in the context of neural coding.


title: Canonical metrics of commuting maps

abstract:
  In the present work we establish the equality of the canonical metric of two
commuting maps on an algebraic variety X. As a consequence the canonical height
and measure associated to both maps are identical.


title: Superstring scattering amplitudes in higher genus

abstract:
  In this paper we continue the program pioneered by D'Hoker and Phong, and
recently advanced by Cacciatori, Dalla Piazza, and van Geemen, of finding the
chiral superstring measure by constructing modular forms satisfying certain
factorization constraints. We give new expressions for their proposed ans\"atze
in genera 2 and 3, respectively, which admit a straightforward generalization.
We then propose an ansatz in genus 4 and verify that it satisfies the
factorization constraints and gives a vanishing cosmological constant. We
further conjecture a possible formula for the superstring amplitudes in any
genus, subject to the condition that certain modular forms admit holomorphic
roots.


title:
Three-Dimensional Grain Boundary Spectroscopy in Transparent High Power
  Ceramic Laser Materials

abstract:
  Using confocal Raman and fluorescence spectroscopic imaging in 3-dimensions,
we show direct evidence for Nd3+-Nd3+ interactions across grain boundaries
(GBs) in Nd3+:YAG laser ceramics. It is clearly shown that Nd3+ segregation
takes place at GBs leading to self-fluorescence quenching which affects a
volume fraction as high as 20%. In addition, we show a clear trend of
increasing spatial inhomogeneities in Nd3+ concentration when the doping levels
exceeds 3 at%, which is not detected by standard spectrometry techniques. These
results could point the way to further improvements in what is already an
impressive class of ceramic laser materials.


title:
Skepsis on the scenario of Biological Evolution provided by stochastic
  models

abstract:
  Stochastic models, based on random processes, may lead to power law
distributions, which provide long range correlations. The observation of power
law behavior and the presence of long range correlations in biological systems
has been demonstrated in various studies. The combination of the two just
mentioned results, theoretical and experimental, supports strongly the scenario
of biological evolution across different organisms. In the current Letter we
explore in a general way, using the algebra of Nonextensive Statistics
introduced by Tsallis and coworkers, if the processes which are described by a
class of stochastic models are really random and discuss the results with
regard to a possible biological evolution.


title: Tracking Vector Magnetograms with the Magnetic Induction Equation

abstract:
  The differential affine velocity estimator (DAVE) developed in Schuck (2006)
for estimating velocities from line-of-sight magnetograms is modified to
directly incorporate horizontal magnetic fields to produce a differential
affine velocity estimator for vector magnetograms (DAVE4VM). The DAVE4VM's
performance is demonstrated on the synthetic data from the anelastic
pseudospectral ANMHD simulations that were used in the recent comparison of
velocity inversion techniques by Welsch (2007). The DAVE4VM predicts roughly
95% of the helicity rate and 75% of the power transmitted through the
simulation slice. Inter-comparison between DAVE4VM and DAVE and further
analysis of the DAVE method demonstrates that line-of-sight tracking methods
capture the shearing motion of magnetic footpoints but are insensitive to flux
emergence -- the velocities determined from line-of-sight methods are more
consistent with horizontal plasma velocities than with flux transport
velocities. These results suggest that previous studies that rely on velocities
determined from line-of-sight methods such as the DAVE or local correlation
tracking may substantially misrepresent the total helicity rates and power
through the photosphere.


title:
Spin-Charge-Lattice Coupling through Resonant Multi-Magnon Excitations
  in Multiferroic BiFeO3

abstract:
  Spin-charge-lattice coupling mediated by multi-magnon processes is
demonstrated in multiferroic BiFeO3. Experimental evidence of two and three
magnons excitations as well as multimagnon coupling at electronic energy scales
and high temperatures are reported. Temperature dependent Raman experiments
show up to five resonant enhancements of the 2-magnon excitation below the Neel
temperature. These are shown to be collective interactions between on-site Fe
d-d electronic resonance, phonons and multimagnons


title: Hypergeometric solutions for third order linear ODEs

abstract:
  In this paper we present a decision procedure for computing pFq
hypergeometric solutions for third order linear ODEs, that is, solutions for
the classes of hypergeometric equations constructed from the 3F2, 2F2, 1F2 and
0F2 standard equations using transformations of the form {x -> F(x), y -> P(x)
y}, where F(x) is rational in x and P(x) is arbitrary. A computer algebra
implementation of this work is present in Maple 12.


title: Electromagnetic form factors from the fifth dimension

abstract:
  We analyse various $U(1)_{EM}$ form factors of mesons at strong coupling in
an $\mathcal{N}=2$ flavored version of $\mathcal{N}=4$ $SYM$ which becomes
conformal in the UV. The quark mass breaks the conformal symmetry in the IR and
generates a mass gap. In the appropriate limit, the gravity dual is described
in terms of probe $D7$-branes in $AdS_5\times S^5$. By studying the $D7$
fluctuations we find the suitable terms in a "meson effective theory" which
allow us to compute the desired form factors, namely the $\gamma\pi\rho$ and
$\gamma f_0\rho$ transition form factors. At large $q^2$ we find perfect
agreement with the naive parton model counting, which is a consequence of the
conformal nature of both QCD and our model in the UV. By using the same tools,
we can compute the $\gamma^*\gamma^*\pi$ form factor. However this channel is
more subtle and comparisons to the QCD result are more involved.


title: Was the Andromeda Stream Produced by a Disk Galaxy?

abstract:
  The halo region of M31 exhibits a startling level of stellar inhomogeneities,
the most prominent of which is the "giant southern stream". Our previous
analysis indicates that this stream, as well as several other observed
features, are products of the tidal disruption of a single satellite galaxy
with stellar mass ~10^9 solar masses less than 1 Gyr ago. Here we show that the
specific observed morphology of the stream and halo debris favors a cold,
rotating, disk-like progenitor over a dynamically hot, non-rotating one. These
observed characteristics include the asymmetric distribution of stars along the
stream cross-section and its metal-rich core/metal-poor sheath structure. We
find that a disk-like progenitor can also give rise to arc-like features on the
minor axis at certain orbital phases that resemble the recently discovered
minor-axis "streams", even reproducing the lower observed metallicity of these
streams. Though interpreted by the discoverers as new, independent tidal
streams, our analysis suggests that these minor-axis streams may alternatively
arise from the progenitor of the giant southern stream. Overall, our study
points the way to a more complete reconstruction of the stream progenitor and
its merger with M31, based on the emerging picture that most of the major
inhomogeneities observed in the M31 halo share a common origin with the giant
stream.


title: Line strengths of early-type galaxies

abstract:
  In this paper we present measurements of velocity dispersions and Lick
indices for 509 galaxies in the local Universe, based on high signal-to-noise,
long slit spectra obtained with the 1.52 m ESO telescope at La Silla. The
conversion of our measurements into the Lick/IDS system was carried out
following the general prescription of Worthey and Ottaviani 1997. Comparisons
of our measurements with those of other authors show, in general, good
agreement. We also examine the dependence between these indices (e.g., Hbeta,
Mg_2, Fe5270 and NaD) and the central velocity dispersion (sigma), and we find
that they are consistent with those previously reported in the literature.
Benefiting from the relatively large size of the sample, we are able to
investigate the dependence of these relations on morphology and environment,
here represented by the local galaxy density. We find that for metallic lines
these relations show no significant dependence on environment or morphology,
except in the case of NaD, which shows distinct behavior for E and S0. On the
other hand, the Hbeta-logsigma shows a significant difference as a function of
the local density of galaxies, which we interpret as being caused by the
truncation of star formation in high density environments. Comparing our
results with those obtained by other authors we find a few discrepancies,
adding to the ongoing debate about the nature of these relations. Finally, we
report that the scatter of the Mg indices versus sigma relations correlate with
Hbeta, suggesting that age may contribute to the scatter. Furthermore, this
scatter shows no significant dependence on morphology or environment. Our
results are consistent with the current downsizing model, where low mass
galaxies have an extended star formation history (abridged).


title:
Casimir force calculations near the insulator-conductor transition in
  gold thin films

abstract:
  We present theoretical calculations of the Casimir force for Au thin films
near the insulator-conductor transition that has been observed experimentally.
The dielectric function of the Au thin films is described by the Drude-Smith
model. The parameters needed to model the dielectric function such as the
relaxation time, plasma frequency and the backscattering constant depend on the
thickness of the film. The Casimir force decreases as the film thickness
decreases until it reaches a minimum after which the force increases again. The
minimum of the force coincides with the critical film thickness where a
percolation conductor-insulator occurs.


title: Direct Detection of Kaluza-Klein Particles in Neutrino Telescopes

abstract:
  In theories with universal extra dimensions (UEDs), all standard model fields
propagate in the bulk and the lightest state of the first Kaluza-Klein (KK)
level can be made stable by imposing a Z2 parity. We consider a framework where
the lightest KK particle (LKP) is a neutral, extremely weakly interacting
particle such as the first KK excitation of the graviton, while the
next-to-lightest KK particle (NLKP) is the first KK mode of a charged
right-handed lepton. In such a scenario, due to its very small couplings to the
LKP, the NLKP is long-lived. We investigate the production of these particles
from the interaction of high energy neutrinos with nucleons in the Earth, and
determine the rate of NLKP events in neutrino telescopes. Using the
Waxman-Bahcall limit for the neutrino flux, we find that the rate can be as
large as a few hundreds events a year for realistic values of the NLKP mass.


title: A generalization of a Cullen's Integral Theorem for the quaternions

abstract:
  We discuss the proof of a certain integral theorem obtained by C. G. Cullen,
originally stated on the class of the analytic intrinsic functions on the
quaternions. It is shown that this integral theorem is true for a larger class
of quaternionic functions.


title: A Resolved Molecular Gas Disk around the Nearby A Star 49 Ceti

abstract:
  The A star 49 Ceti, at a distance of 61 pc, is unusual in retaining a
substantial quantity of molecular gas while exhibiting dust properties similar
to those of a debris disk. We present resolved observations of the disk around
49 Ceti from the Submillimeter Array in the J=2-1 rotational transition of CO
with a resolution of 1.0x1.2 arcsec. The observed emission reveals an extended
rotating structure viewed approximately edge-on and clear of detectable CO
emission out to a distance of ~90 AU from the star. No 1.3 millimeter continuum
emission is detected at a 3-sigma sensitivity of 2.1 mJy/beam. Models of disk
structure and chemistry indicate that the inner disk is devoid of molecular
gas, while the outer gas disk between 40 and 200 AU from the star is dominated
by photochemistry from stellar and interstellar radiation. We determine
parameters for a model that reproduces the basic features of the spatially
resolved CO J=2-1 emission, the spectral energy distribution, and the
unresolved CO J=3-2 spectrum. We investigate variations in disk chemistry and
observable properties for a range of structural parameters. 49 Ceti appears to
be a rare example of a system in a late stage of transition between a gas-rich
protoplanetary disk and a tenuous, virtually gas-free debris disk.


title: Diversity of Online Community Activities

abstract:
  Web sites where users create and rate content as well as form networks with
other users display long-tailed distributions in many aspects of behavior.
Using behavior on one such community site, Essembly, we propose and evaluate
plausible mechanisms to explain these behaviors. Unlike purely descriptive
models, these mechanisms rely on user behaviors based on information available
locally to each user. For Essembly, we find the long-tails arise from large
differences among user activity rates and qualities of the rated content, as
well as the extensive variability in the time users devote to the site. We show
that the models not only explain overall behavior but also allow estimating the
quality of content from their early behaviors.


title: Colorful horizons with charge in anti-de Sitter space

abstract:
  An abelian gauge symmetry can be spontaneously broken near a black hole
horizon in anti-de Sitter space using a condensate of non-abelian gauge fields.
There is a second order phase transition between Reissner-Nordstrom-anti-de
Sitter solutions, which are preferred at high temperatures, and symmetry
breaking solutions, which are preferred at low temperatures.


title: Rolling Solution for Tachyon Condensation in Open String Field Theory

abstract:
  Open string field theory in the level truncation approximation is considered.
It is shown that the energy conservation law determines the existence of
rolling tachyon solution. The coupling of the open string field theory action
to a Friedmann-Robertson-Walker metric is considered and as a result the new
time dependent rolling tachyon solution is presented and possible cosmological
consequences are discussed.


title: Changes of variables in modulation and Wiener amalgam spaces

abstract:
  In this paper various properties of global and local changes of variables as
well as properties of canonical transforms are investigated on modulation and
Wiener amalgam spaces. We establish several relations among localisations of
modulation and Wiener amalgam spaces and, as a consequence, we obtain several
versions of local and global Beurling-Helson type theorems. We also establish a
number of positive results such as local boundedness of canonical transforms on
modulation spaces, properties of homogeneous changes of variables, and local
continuity of Fourier integral operators on Fourier Lebesgue spaces. Finally,
counterparts of these results are discussed for spaces on the torus as well as
for weighted spaces.


title: New techniques for pointed Hopf algebras

abstract:
  We present techniques that allow to decide that the dimension of some pointed
Hopf algebras associated with non-abelian groups is infinite. These results are
consequences of arXiv:0803.2430v1. We illustrate each technique with
applications.


title: On a Generalised Lehmer Problem for Arbitrary Powers

abstract:
  We consider a generalisation of the classical Lehmer problem about the parity
distribution of an integer and its modular inverse. We use some known estimates
of exponential sums to study a more general question of simultaneous
distribution of the residues of any fixed number of negative and positive
powers of integers in prescribed arithmetic progressions. In particular, we
improve and generalise a recent result of Y. Yi and W. Zhang.


title: Kramers-Kronig relation of graphene conductivity

abstract:
  Utilizing a complete Lorentz-covariant and local-gauge-invariant formulation,
we discuss graphene response to arbitrary external electric field. The
relation, which is called as Kramers-Kr(\ddot{o})nig relation in the paper,
between imaginary part and real part of ac conductivity is given. We point out
there exists an ambiguity in the conductivity computing, attributed to the wick
behavior at ultraviolet vicinity. We argue that to study electrical response of
graphene completely, non-perturbational contribution should be considered.


title:
Obtaining the One-Holed Torus from Pants: Duality in an
  SL(3,C)-Character Variety

abstract:
  The SL(3,C)-representation variety R of a free group F arises naturally by
considering surface group representations for a surface with boundary. There is
a SL(3,C)-action on the coordinate ring of R. The geometric points of the
subring of invariants of this action is an affine variety X. The points of X
parametrize isomorphism classes of completely reducible representations. The
coordinate ring C[X] is a complex Poisson algebra with respect to a
presentation of F imposed by the surface. In previous work, we have worked out
the bracket on all generators when the surface is a three-holed sphere and when
the surface is a one-holed torus. In this paper, we show how the symplectic
leaves corresponding to these two different Poisson structures on X relate to
each other. In particular, they are symplectically dual at a generic point.
Moreover, the topological gluing map which turns the three-holed sphere into
the one-holed torus induces a rank preserving Poisson map on C[X].


title: Robustness and Regularization of Support Vector Machines

abstract:
  We consider regularized support vector machines (SVMs) and show that they are
precisely equivalent to a new robust optimization formulation. We show that
this equivalence of robust optimization and regularization has implications for
both algorithms, and analysis. In terms of algorithms, the equivalence suggests
more general SVM-like algorithms for classification that explicitly build in
protection to noise, and at the same time control overfitting. On the analysis
front, the equivalence of robustness and regularization, provides a robust
optimization interpretation for the success of regularized SVMs. We use the
this new robustness interpretation of SVMs to give a new proof of consistency
of (kernelized) SVMs, thus establishing robustness as the reason regularized
SVMs generalize well.


title: Clustered chimera states in delay coupled oscillator systems

abstract:
  We investigate "chimera" states in a ring of identical phase oscillators
coupled in a time-delayed and spatially non-local fashion. We find novel
"clustered chimera" states that have spatially distributed phase coherence
separated by incoherence with adjacent coherent regions in anti-phase. The
existence of such time-delay induced phase clustering is further supported
through solutions of a generalized functional self-consistency equation of the
mean field. Our results highlight an additional mechanism for cluster formation
that may find wider practical applications.


title:
Hawking radiation in Reissner-Nordstr\"{o}m blackhole with a global
  monopole via Covariant anomalies and Effective action

abstract:
  We adopt the covariant anomaly cancellation method as well as the effective
action approach to obtain the Hawking radiation from the Reissner-Nordstr\"{o}m
blackhole with a global monopole falling in the class of the most general
spherically symmetric charged blackhole $(\sqrt{-g}\neq1)$, using only
covariant boundary condition at the event horizon.


title:
Search for Standard Model Higgs Boson Production in Association with a W
  Boson at CDF

abstract:
  We present a search for standard model Higgs boson production in association
with a W boson in proton-antiproton collisions ($p\bar{p}\to W^\pm H \to
\ell\nu b\bar{b}$) at a center of mass energy of 1.96 TeV. The search employs
data collected with the CDF II detector which correspond to an integrated
luminosity of approximately 1 fb-1. We select events consistent with a
signature of a single lepton ($e^\pm/\mu^\pm$), missing transverse energy, and
two jets. Jets corresponding to bottom quarks are identified with a secondary
vertex tagging method and a neural network filter technique. The observed
number of events and the dijet mass distributions are consistent with the
standard model background expectations, and we set 95% confidence level upper
limits on the production cross section times branching ratio ranging from 3.9
to 1.3 pb for Higgs boson masses from 110 to 150 GeV/c2, respectively.


title: Critique of some thermodynamic proofs based on the pump-engine couple

abstract:
  We argue that all the common thermodynamic proofs based on the pump-engine
couple possess an inherent circularity and hence are of doubtful value. In
certain cases, ways of avoiding them are suggested. In others, the difficulties
are discussed. Particularly, we emphasize that a neat proof of Carnot theorems
requires the entropic formulation of the second law.


title:
Flux dependent MeV self-ion- induced effects on Au nanostructures:
  Dramatic mass transport and nano-silicide formation

abstract:
  We report a direct observation of dramatic mass transport due to 1.5 MeV Au2+
ion impact on isolated Au nanostructures of an average size 7.6 nm and a height
6.9 nm that are deposited on Si (111) substrate under high flux (3.2x10^10 to
6.3x10^12 ions cm-2 s-1) conditions. The mass transport from nanostructures
found to extend up to a distance of about 60 nm into the substrate, much beyond
their size. This forward mass transport is compared with the recoil
implantation profiles using SRIM simulation. The observed anomalies with theory
and simulations are discussed. At a given energy, the incident flux plays a
major role in mass transport and its re-distribution. The mass transport is
explained on the basis of thermal effects and creation of rapid diffusion paths
at nano-scale regime during the course of ion irradiation. The unusual mass
transport is found to be associated with the formation of gold silicide
nanoalloys at sub-surfaces. The complexity of the ion-nanostructure interaction
process has been discussed with a direct observation of melting (in the form of
spherical fragments on the surface) phenomena. The transmission electron
microscopy, scanning transmission electron microscopy and Rutherford
backscattering spectroscopy methods have been used.


title:
Freely-suspended matrix-free metamaterials showing THz left-handed pass
  bands

abstract:
  Featuring dense spatial distributions of engineered metallic particles,
electromagnetic metamaterials exhibit simultaneously negative values of both,
dielectric permittivity and magnetic permeability, within a resonance frequency
band called left-handed passband. Unusual electromagnetic properties are found
resulting in promising applications such as sub-wavelength resolution imaging.
State-of-the-art micro/nanomanufacturing has led to resonance frequencies
reaching the visible red. The common embedding of the metal particles in
plastic matrices or deposition on dielectric substrates within a small area
severely limits the usefulness of the materials. Here, we use UV or X-ray
lithography to build comparably large areas and quantities of the first
freely-suspended matrix-free metamaterials in which the metallic structures are
S-string-like with their ends held by a window-frame. In vacuo spectral
characterization combined with simulation reveals left-handed passbands from
1.6 to 2.2 THz. Owing to their size, the devices can be easily handled. They
offer a straightforward way of making them tunable and two-dimensionally
isotropic.


title: S-wave bottom baryons

abstract:
  The masses of S-wave bottom baryons are calculated in the framework of
coupled-channel formalism. The relativistic three-quark equations for the
bottom baryons using the dispersion relation technique are found. The
approximate solutions of these equations based on the extraction of leading
singularities of the amplitude are obtained. The calculated mass values of
S-wave bottom baryons are in good agreement with the experimental ones.


title:
Combinatorial and model-theoretical principles related to regularity of
  ultrafilters and compactness of topological spaces. I

abstract:
  We begin the study of the consequences of the existence of certain infinite
matrices. Our present application is to compactness of products of topological
spaces.


title:
Homogenization of semi-linear PDEs with discontinuous effective
  coefficients

abstract:
  We study the asymptotic behavior of solution of semi-linear PDEs. Neither
periodicity nor ergodicity will be assumed. In return, we assume that the
coefficients admit a limit in \`{C}esaro sense. In such a case, the averaged
coefficients could be discontinuous. We use probabilistic approach based on
weak convergence for the associated backward stochastic differential equation
in the S-topology to derive the averaged PDE. However, since the averaged
coefficients are discontinuous, the classical viscosity solution is not defined
for the averaged PDE. We then use the notion of "$L^p-$viscosity solution"
introduced in \cite{CCKS}. We use BSDEs techniques to establish the existence
of $L^p-$viscosity solution for the averaged PDE. We establish weak continuity
for the flow of the limit diffusion process and related the PDE limit to the
backward stochastic differential equation via the representation of
$L^p$-viscosity solution.


title: Off-Site Continuums as Cosmological Models of Galaxies and the Universe

abstract:
  The off-site continuums are proposed for the cosmological models of the
galaxies and the Universe. It is shown that many visual properties of galaxies
and the Universe may be described on frames of the off-site continuums
methodology. In cosmological scale, the appearance of off-site objects is quite
similar to the influence of the 'dark matter' and the 'dark energy'. Analogies
to known relic radiation also look through. It is discussed few possible models
of galaxies and the Universe. Such point of view may appear useful for the
investigation of conceptual problems of modern cosmology.


title:
Multiagent Approach for the Representation of Information in a Decision
  Support System

abstract:
  In an emergency situation, the actors need an assistance allowing them to
react swiftly and efficiently. In this prospect, we present in this paper a
decision support system that aims to prepare actors in a crisis situation
thanks to a decision-making support. The global architecture of this system is
presented in the first part. Then we focus on a part of this system which is
designed to represent the information of the current situation. This part is
composed of a multiagent system that is made of factual agents. Each agent
carries a semantic feature and aims to represent a partial part of a situation.
The agents develop thanks to their interactions by comparing their semantic
features using proximity measures and according to specific ontologies.


title:
Convergence of a finite volume scheme for nonlocal reaction-diffusion
  systems modelling an epidemic disease

abstract:
  We analyze a finite volume scheme for nonlocal SIR model, which is a nonlocal
reaction-diffusion system modeling an epidemic disease. We establish existence
solutions to the finite volume scheme, and show that it converges to a weak
solution. The convergence proof is based on deriving series of a priori
estimates and using a general $L^p$ compactness criterion.


title:
Boundary-mediated electron-electron interactions in quantum point
  contacts

abstract:
  An unusual increase of the conductance with temperature is observed in clean
quantum point contacts for conductances larger than 2e^2/h. At the same time a
positive magnetoresistance arises at high temperatures. A model accounting for
electron-electron interactions mediated by bound- aries (scattering on Friedel
oscillations) qualitatively describes the observation. It is supported by
numerical simulation at zero magnetic field.


title:
Local Polynomial Estimation for Sensitivity Analysis on Models With
  Correlated Inputs

abstract:
  Sensitivity indices when the inputs of a model are not independent are
estimated by local polynomial techniques. Two original estimators based on
local polynomial smoothers are proposed. Both have good theoretical properties
which are exhibited and also illustrated through analytical examples. They are
used to carry out a sensitivity analysis on a real case of a kinetic model with
correlated parameters.


title: The Baxter's Q-operator for the W-algebra $W_N$

abstract:
  The q-oscillator representation for the Borel subalgebra of the affine
symmetry $U_q(sl_N^)$ is presented. By means of this q-oscillator
representation, we give the free field realizations of the Baxter's Q-operator
$Q_j(t)$, $\bar{Q}_j(t)$ for the W-algebra $W_N$. We give the functional
relations of the $T$-$Q$ operators, including the higher-rank generalization of
the Baxter's $T$-$Q$ relation.


title: Deficiency of Broad Line AGNs in Compact Groups of Galaxies

abstract:
  Based on a new survey of AGN activity in Compact Groups of Galaxies, we
report a remarkable deficiency of Broad Line AGNs as compared to Narrow Line
AGNs. The cause of such deficiency could be related to the average low
luminosity of AGNs in CGs: $10^{39}$ erg s$^{-1}$. This result may imply lower
accretion rates in CG AGNs, making Broad Line Regions (BLR) undetectable, or
may indicate a genuine absence of BLRs. Both phenomena are consistent with gas
stripping through tidal interaction and dry mergers.


title:
Spherically averaged versus angle-dependent interactions in quadrupolar
  fluids

abstract:
  Employing simplified models in computer simulation is on the one hand often
enforced by computer time limitations but on the other hand it offers insights
into the molecular properties determining a given physical phenomenon. We
employ this strategy to the determination of the phase behaviour of quadrupolar
fluids, where we study the influence of omitting angular degrees of freedom of
molecules via an effective spherically symmetric potential obtained from a
perturbative expansion. Comparing the liquid-vapor coexistence curve, vapor
pressure at coexistence, interfacial tension between the coexisting phases,
etc., as obtained from both the models with the full quadrupolar interactions
and the (approximate) isotropic interactions, we find discrepancies in the
critical region to be typically (such as in the case of carbon dioxide) of the
order of 4%. However, when the Lennard-Jones parameters are rescaled such that
critical temperatures and critical densities of both models coincide with the
experimental results, almost perfect agreement between the above-mentioned
properties of both models is obtained. This result justifies the use of
isotropic quadrupolar potentials. We present also a detailed comparison of our
simulations with a combined integral equation/density functional approach and
show that the latter provides an accurate description except for the vicinity
of the critical point.


title: Limiting Carleman weights and anisotropic inverse problems

abstract:
  In this article we consider the anisotropic Calderon problem and related
inverse problems. The approach is based on limiting Carleman weights,
introduced in Kenig-Sjoestrand-Uhlmann (Ann. of Math. 2007) in the Euclidean
case. We characterize those Riemannian manifolds which admit limiting Carleman
weights, and give a complex geometrical optics construction for a class of such
manifolds. This is used to prove uniqueness results for anisotropic inverse
problems, via the attenuated geodesic X-ray transform. Earlier results in
dimension $n \geq 3$ were restricted to real-analytic metrics.


title: Localized - delocalized electron quantum phase transitions

abstract:
  Metal--insulator transitions and transitions between different quantum Hall
liquids are used to describe the physical ideas forming the basis of quantum
phase transitions and the methods of application of theoretical results in
processing experimental data. The following two theoretical schemes are
discussed and compared: the general theory of quantum phase transitions, which
has been developed according to the theory of thermodynamic phase transitions
and relies on the concept of a partition function, and a theory which is based
on a scaling hypothesis and the renormalization-group concept borrowed from
quantum electrodynamics, with the results formulated in terms of flow diagrams.


title: Almost Einstein and Poincare-Einstein manifolds in Riemannian signature

abstract:
  An almost Einstein manifold satisfies equations which are a slight weakening
of the Einstein equations; Einstein metrics, Poincare-Einstein metrics, and
compactifications of certain Ricci-flat asymptotically locally Euclidean
structures are special cases. The governing equation is a conformally invariant
overdetermined PDE on a function. Away from the zeros of this the almost
Einstein structure is Einstein, while the zero set gives a scale singularity
set which may be viewed as a conformal infinity for the Einstein metric. In
this article we give a classification of the possible scale singularity spaces
and derive geometric results which explicitly relate the intrinsic conformal
geometry of these to the conformal structure of the ambient almost Einstein
manifold. Classes of examples are constructed. A compatible generalisation of
the constant scalar curvature condition is also developed. This includes almost
Einstein as a special case, and when its curvature is suitably negative, is
closely linked to the notion of an asymptotically hyperbolic structure.


title:
Tension between scalar/pseudoscalar new physics contribution to B_s -->
  mu+ mu- and B --> K mu+ mu-

abstract:
  New physics in the form of scalar/pseudoscalar operators cannot lower the
semileptonic branching ratio B(B --> K mu+ mu-) below its standard model value.
In addition, we show that the upper bound on the leptonic branching ratio B(B_s
--> mu+ mu-) sets a strong constraint on the maximum value of B(B --> K mu+
mu-) in models with multiple Higgs doublets: with the current bound, B(B --> K
mu+ mu-) cannot exceed the standard model prediction by more than 2.5%. The
conclusions hold true even if the new physics couplings are complex. However
these constraints can be used to restrict new physics couplings only if the
theoretical and experimental errors in B(B --> K mu+ mu-) are reduced to a few
per cent. The constraints become relaxed in a general class of models with
scalar/pesudoscalar operators.


title:
Muon pair creation by two x-ray laser photons in the field of an atomic
  nucleus

abstract:
  The generation of muon-antimuon pairs is calculated in the collision of an
ultrarelativistic bare ion with an intense x-ray laser beam. The reaction
proceeds nonlinearly via absorption of two laser photons. By systematic study
throughout the nuclear chart we show that the interplay between the nuclear
charge and size, along with the possibility of nuclear excitation leads to
saturation of the total production rates for high-Z ions, in contrast to the
usual Z^2 scaling for pointlike projectiles. The process is experimentally
accessible by combining present-day ion accelerators with near-future laser
sources and in principle allows for the measurement of nuclear form factors.


title: A caricature of a singular curvature flow in the plane

abstract:
  We study a singular parabolic equation of the total variation type in one
dimension. The problem is a simplification of the singular curvature flow. We
show existence and uniqueness of weak solutions. We also prove existence of
weak solutions to the semi-discretization of the problem as well as convergence
of the approximating sequences. The semi-discretization shows that facets must
form. For a class of initial data we are able to study in details the facet
formation and interactions and their asymptotic behavior. We notice that our
qualitative results may be interpreted with the help of a special composition
of multivalued operators.


title: Public transport networks: empirical analysis and modeling

abstract:
  We use complex network concepts to analyze statistical properties of urban
public transport networks (PTN). To this end, we present a comprehensive survey
of the statistical properties of PTNs based on the data of fourteen cities of
so far unexplored network size. Especially helpful in our analysis are
different network representations. Within a comprehensive approach we calculate
PTN characteristics in all of these representations and perform a comparative
analysis. The standard network characteristics obtained in this way often
correspond to features that are of practical importance to a passenger using
public traffic in a given city. Specific features are addressed that are unique
to PTNs and networks with similar transport functions (such as networks of
neurons, cables, pipes, vessels embedded in 2D or 3D space). Based on the
empirical survey, we propose a model that albeit being simple enough is capable
of reproducing many of the identified PTN properties. A central ingredient of
this model is a growth dynamics in terms of routes represented by self-avoiding
walks.


title:
Geographic Information Systems in Evaluation and Visualization of
  Construction Schedule

abstract:
  Commercially available scheduling tools such as Primavera and Microsoft
Project fail to provide information pertaining to the spatial aspects of
construction project. A methodology using geographical information systems
(GIS) is developed to represent spatial aspects of the construction progress
graphically by synchronizing it with construction schedule. The spatial aspects
are depicted by 3D model developed in AutoCAD and construction schedule is
generated using Microsoft Excel. Spatial and scheduling information are linked
together into the GIS environment (ArcGIS). The GIS-based system developed in
this study may help in better understanding the schedule along with its spatial
aspects.


title: IC10~X-1/NGC300~X-1: the very immediate progenitors of BH-BH binaries

abstract:
  We investigate the future evolution of two extragalactic X-ray binaries: IC10
X-1 and NGC300 X-1. Each of them consists of a high mass BH ($\sim 20-30
\msun$) accreting from a massive WR star companion ($\gtrsim 20 \msun$), and
both are located in low metallicity galaxies. We analyze the current state of
the systems and demonstrate that both systems will very quickly ($\lesssim 0.3$
Myr) form close BH-BH binaries with the short coalescence time ($\sim 3$ Gyr)
and large chirp mass ($\sim 15 \msun$). The formation of BH-BH system seems
unavoidable, as {\em (i)} WR companions are well within their Roche lobes and
they do not expand so no Roche lobe overflow is expected, {\em (ii)} even
intense WR wind mass loss does not remove sufficient mass to prohibit the
formation of the second BH, {\em (ii)} even if BH receives the large natal
kick, the systems are very closely bound and are almost impossible to disrupt.
As there are two such immediate BH-BH progenitor systems within 2 Mpc and as
the current gravitational wave instruments LIGO/VIRGO (initial stage) can
detect such massive BH-BH mergers out to $\sim 200$ Mpc, the empirically
estimated detection rate of such inspirals is $R=3.36^{+8.29}_{-2.92}$ at the
99% confidence level. If there is no detection in the current LIGO/VIRGO data
(unreleased year of $s6$ run), the existence of these two massive BH systems
poses an interesting challenge. Either the gravitational radiation search is
not sensitive to massive inspirals or there is some fundamental
misunderstanding of stellar evolution physics leading directly to the formation
of BH-BH binaries.


title: Measuring B -> tau nu and B_c -> tau nu at the Z peak

abstract:
  The measurement of B->tau nu at the B factories provides important
constraints on the parameter tan beta/m_H^+- in the context of models with two
Higgs doublets. Limits on this decay from e+e- collisions at the Z peak were
sensitive to the sum of B->tau nu and B_c->tau nu. Due to the possibly sizeable
contribution from B_c->tau nu we suggest that a signal for this combination
might be observed if the LEP L3 Collaboration used their total data of ~3.6
10^6 hadronic decays of the Z boson. Moreover, we point out that a future
Linear Collider operating at the Z peak (Giga Z option) could constrain tan
beta/m_H^+- from the sum of these processes with a precision comparable to that
anticipated at proposed high luminosity B factories from B-> tau nu alone.


title: Maxima of Dirichlet and triangular arrays of gamma variables

abstract:
  Consider a rowwise independent triangular array of gamma random variables
with varying parameters. Under several different conditions on the shape
parameter, we show that the sequence of row-maximums converges weakly after
linear or power transformation. Depending on the parameter combinations, we
obtain both Gumbel and non-Gumbel limits.
  The weak limits for maximum of the coordinates of certain Dirichlet vectors
of increasing dimension are also obtained using the gamma representation.


title: Photon production at the interaction point of the ILC

abstract:
  The intense beam-beam effect at the interaction point of the International
Linear Collider (ILC) causes large disruption of the beams and the production
of photons. These photons, arising dominantly through beamstrahlung emission,
are problematic for the machine design as they need to be transported and
dumped in a controlled way. In this work, we perform simulations of the
beam-beam interaction to predict photon production rates and distributions for
the different beam parameters considered at ILC. The results are expressed in
terms of a set of cones of excluded power, allowing to define the
beam-stay-clear requirements relevant for different cases and contexts. A
comparison is also made with theoretical expectations. The suggested photon
cone half-opening angles are 0.75 and 0.85 mrad in the horizontal and vertical
planes, respectively. These cones cover all machine energies and parameter
sets, and include the low power Compton photons.


title: On the gap between representability and collapsibility

abstract:
  A simplicial complex K is called d-representable if it is the nerve of a
collection of convex sets in R^d; K is d-collapsible if it can be reduced to an
empty complex by repeatedly removing a face of dimension at most d-1 that is
contained in a unique maximal face; and K is d-Leray if every induced
subcomplex of K has vanishing homology of dimension d and larger.
  It is known that d-representable implies d-collapsible implies d-Leray, and
no two of these notions coincide for d greater or equal to 2. The famous Helly
theorem and other important results in discrete geometry can be regarded as
results about d-representable complexes, and in many of these results
"d-representable" in the assumption can be replaced by "d-collapsible" or even
"d-Leray".
  We investigate "dimension gaps" among these notions, and we construct, for
all positive integers d, a 2d-Leray complex that is not (3d-1)-collapsible and
a d-collapsible complex that is not (2d-2)-representable. In the proofs we
obtain two results of independent interest: (i) The nerve of every finite
family of sets, each of size at most d, is d-collapsible. (ii) If the nerve of
a simplicial complex K is d-representable, then K embeds in R^d.


title: Self-similar solutions for the LSW model with encounters

abstract:
  The LSW model with encounters has been suggested by Lifshitz and Slyozov as a
regularization of their classical mean-field model for domain coarsening to
obtain universal self-similar long-time behavior. We rigorously establish that
an exponentially decaying self-similar solution to this model exist, and show
that this solutions is isolated in a certain function space. Our proof relies
on setting up a suitable fixed-point problem in an appropriate function space
and careful asymptotic estimates of the solution to a corresponding homogeneous
problem.


title:
Integration with respect to local time and Ito's formula for smooth
  nondegenerate martingales

abstract:
  We show an It\^ o's formula for nondegenerate Brownian martingales
$X_t=\int_0^t u_s dW_s$ and functions $F(x,t)$ with locally integrable
derivatives in $t$ and $x$. We prove that one can express the additional term
in It\^o's s formula as an integral over space and time with respect to local
time.


title: A probable close brown dwarf companion to GJ 1046 (M2.5V)

abstract:
  Context. Brown dwarf companions to stars at separations of a few AU or less
are rare objects, and none have been found so far around early-type M dwarfs
M0V-M5V). With GJ 1046 (M2.5V), a strong candidate for such a system with a
separation of 0.42 AU is presented.
  Aims. We aim at constraining the mass of the companion in order to decide
whether it is a brown dwarf or a low-mass star.
  Methods. We employed precision RV measurements to determine the orbital
parameters and the minimum companion mass. We then derived an upper limit to
the companion mass from the lack of disturbances of the RV measurements by a
secondary spectrum. An even tighter upper limit is subsequently established by
combining the RV-derived orbital parameters with the recent new version of the
Hipparcos Intermediate Astrometric Data.
  Results. For the mass of the companion, we derive m>26.9 MJup from the RV
data. Based on the RV data alone, the probability that the companion exceeds
the stellar mass threshold is just 6.2%. The absence of effects from the
secondary spectrum lets us constrain the companion mass to m <229 MJup. The
combination of RV and Hipparcos data yields a 3sigma upper mass limit to the
companion mass of 112 MJup with a formal optimum value at m=47.2 MJup. From the
combination of RV and astrometric data, the chance probability that the
companion is a star is 2.9%.
  Conclusions. We have found a low-mass, close companion to an early-type M
dwarf. While the most likely interpretation of this object is that it is a
brown dwarf, a low-mass stellar companion is not fully excluded.


title: Pion-Photon TDAs in the NJL Model

abstract:
  The pion-photon Transition Distribution Amplitudes (TDAs) are studied,
treating the pion as a bound state in the sense of Bethe-Salpeter, in the
formalism of the NJL model. The results obtained explicitly verify support, sum
rules and polynomiality conditions. The role of PCAC is highlighted.


title: On the size of Nikodym sets in finite fields

abstract:
  Let $\mathbb{F}_q$ denote a finite field of $q$ elements. Define a set
$B\subset\mathbb{F}_q^n$ to be Nikodym if for each $x\in B^{c}$, there exists a
line $L$ such that $L\cap B^c=\{x\}.$ The main purpose of this note is to show
that the size of every Nikodym set is at least $C_n\cdot q^n$, where $C_n$
depends only on $n$.


title: Quantum dissipative Rashba spin ratchets

abstract:
  We predict the possibility to generate a finite stationary spin current by
applying an unbiased ac driving to a quasi-one-dimensional asymmetric periodic
structure with Rashba spin-orbit interaction and strong dissipation. We show
that under a finite coupling strength between the orbital degrees of freedom
the electron dynamics at low temperatures exhibits a pure spin ratchet
behavior, {\it i.e.} a finite spin current and the absence of charge transport
in spatially asymmetric structures. It is also found that the equilibrium spin
currents are not destroyed by the presence of strong dissipation.


title: The Current Status of Asteroseismology

abstract:
  Stellar evolution, a fundamental bedrock of modern astrophysics, is driven by
the physical processes in stellar interiors. While we understand these
processes in general terms, we lack some important ingredients. Seemingly small
uncertainties in the input physics of the models, e.g., the opacities or the
amount of mixing and of interior rotation, have large consequences for the
evolution of stars. The goal of asteroseismology is to improve the description
of the interior physics of stars by means of their oscillations, just as global
helioseismology led to a huge step forward in our knowledge about the internal
structure of the Sun. In this paper we present the current status of
asteroseismology by considering case studies of stars with a variety of masses
and evolutionary stages. In particular, we outline how the confrontation
between the observed oscillation frequencies and those predicted by the models
allows us to pinpoint limitations of the input physics of current models and
improve them to a level that cannot be reached with any other current method.


title:
Parametrization of Bose-Einstein Correlations and Reconstruction of the
  Space-Time Evolution of Pion Production in e+e- Annihilation

abstract:
  A parametrization of the Bose-Einstein correlation function of pairs of
identical pions produced in hadronic e+e- annihilation is proposed within the
framework of a model (the tau-model) in which space-time and momentum space are
very strongly correlated. Using information from the Bose-Einstein correlations
as well as from single-pion spectra,it is then possible to reconstruct the
space-time evolution of pion production.


title: Landau's necessary density conditions for LCA groups

abstract:
  H. Landau's necessary density conditions for sampling and interpolation may
be viewed as a general principle resting on a basic fact of Fourier analysis:
The complex exponentials $e^{i kx}$ ($k$ in $\mathbb{Z}$) constitute an
orthogonal basis for $L^2([-\pi,\pi])$. The present paper extends Landau's
conditions to the setting of locally compact abelian (LCA) groups, relying in
an analogous way on the basics of Fourier analysis. The technicalities--in
either case of an operator theoretic nature--are however quite different. We
will base our proofs on the comparison principle of J. Ramanathan and T.
Steger.


title:
Quasiparticle Tunneling in the Fractional Quantum Hall State at \nu =
  5/2

abstract:
  Theory predicts that quasiparticle tunneling between the counter-propagating
edges in a fractional quantum Hall state can be used to measure the effective
quasiparticle charge e* and dimensionless interaction parameter g, and thereby
characterize the many-body wavefunction describing the state. We report
measurements of quasiparticle tunneling in a high mobility GaAs two dimensional
electron system in the fractional quantum Hall state at nu=5/2 using a
gate-defined constriction to bring the edges close together. We find the
dc-bias peaks in the tunneling conductance at different temperatures collapse
onto a single curve when scaled, in agreement with weak tunneling theory.
Various models for the \nu=5/2 state predict different values for g. Among
these models, the non-abelian states with e*=1/4 and g=1/2 are most consistent
with the data.


title: A New Upper Bound for Max-2-Sat: A Graph-Theoretic Approach

abstract:
  In {\sc MaxSat}, we ask for an assignment which satisfies the maximum number
of clauses for a boolean formula in CNF. We present an algorithm yielding a run
time upper bound of $O^*(2^{\frac{1}{6.2158}})$ for {\sc Max-2-Sat} (each
clause contains at most 2 literals), where $K$ is the number of clauses. The
run time has been achieved by using heuristic priorities on the choice of the
variable on which we branch. The implementation of these heuristic priorities
is rather simple, though they have a significant effect on the run time. The
analysis is done using a tailored non-standard measure.


title: Symplectic maps of complex domains into complex space forms

abstract:
  Let $M\subset{\complex}^n$ be a complex domain of ${\complex}^n$ endowed with
a rotation invariant \K form $\omega_{\Phi}= \frac{i}{2}
\partial\bar\partial\Phi$. In this paper we describe sufficient conditions on
the \K potential $\Phi$ for $(M, \omega_{\Phi})$ to admit a symplectic
embedding (explicitely described in terms of $\Phi$) into a complex space form
of the same dimension of $M$. In particular we also provide conditions on
$\Phi$ for $(M, \omega_{\Phi})$ to admit global symplectic coordinates. As an
application of our results we prove that each of the Ricci flat (but not flat)
\K forms on ${\complex}^2$ constructed by LeBrun (Taub-NUT metric) admits
explicitely computable global symplectic coordinates.


title: Riemannian geometry of Hartogs domains

abstract:
  Let $D_F = \{(z_0, z) \in {\C}^{n} | |z_0|^2 < b, \|z\|^2 < F(|z_0|^2) \}$ be
a strongly pseudoconvex Hartogs domain endowed with the \K metric $g_F$
associated to the \K form $\omega_F = -\frac{i}{2} \partial \bar{\partial} \log
(F(|z_0|^2) - \|z\|^2)$.
  This paper contains several results on the Riemannian geometry of these
domains. In the first one we prove that if $D_F$ admits a non special geodesic
(see definition below) through the origin whose trace is a straight line then
$D_F$ is holomorphically isometric to an open subset of the complex hyperbolic
space. In the second theorem we prove that all the geodesics through the origin
of $D_F$ do not self-intersect, we find necessary and sufficient conditions on
$F$ for $D_F$ to be geodesically complete and we prove that $D_F$ is locally
irreducible as a Riemannian manifold. Finally, we compare the Bergman metric
$g_B$ and the metric $g_F$ in a bounded Hartogs domain and we prove that if
$g_B$ is a multiple of $g_F$, namely $g_B=\lambda g_F$, for some $\lambda\in
\R^+$, then $D_F$ is holomorphically isometric to an open subset of the complex
hyperbolic space.


title:
Statistics of the zeros of zeta functions in families of hyperelliptic
  curves over a finite field

abstract:
  We study the fluctuations in the distribution of zeros of zeta functions of a
family of hyperelliptic curves defined over a fixed finite field, in the limit
of large genus. According to the Riemann Hypothesis for curves, the zeros all
lie on a circle. Their angles are uniformly distributed, so for a curve of
genus g a fixed interval I will contain 2g|I| angles as the genus grows. We
show that for the variance of number of angles in I is asymptotically a
constant multiple of log(2g|I|) and prove a central limit theorem: The
normalized fluctuations are Gaussian. These results continue to hold for
shrinking intervals as long as the expected number of angles 2g|I| tends to
infinity.


title:
Magnetic properties of BaCdVO(PO_4)_2: a strongly frustrated spin-1/2
  square lattice close to the quantum critical regime

abstract:
  We report magnetization and specific heat measurements on polycrystalline
samples of BaCdVO(PO_4)_2 and show that this compound is a S=1/2 frustrated
square lattice with ferromagnetic nearest-neighbor (J_1) and antiferromagnetic
next-nearest-neighbor (J_2) interactions. The coupling constants J_1\simeq -3.6
K and J_2\simeq 3.2 K are determined from a fitting of the susceptibility data
and confirmed by an analysis of the saturation field (H_s=4.2 T), the specific
heat, and the magnetic entropy. BaCdVO(PO_4)_2 undergoes magnetic ordering at
about 1 K, likely towards a columnar antiferromagnetic state. We find that
BaCdVO(PO_4)_2 with the frustration ratio \alpha=J_2/J_1\simeq -0.9 is closer
to a critical (quantum spin liquid) region of the frustrated square lattice
than any of the previously reported compounds. Positive curvature of the
magnetization curve is observed in agreement with recent theoretical
predictions for high-field properties of the frustrated square lattice close to
the critical regime.


title: Symplectic duality between complex domains

abstract:
  In this paper after extending the definition of symplectic duality (given by
the first two authors in arXiv:math/0603141 for bounded symmetric domains) to
arbitrary complex domains of ${\C}^n$ centered at the origin we generalize some
of the results proved in arXiv:math/0603141 and arXiv:0707.2125 to those
domains.


title:
Electroproduction of $\phi(1020)$ mesons at $1.4\leq Q^2\leq$ GeV$^2$
  measured with the CLAS spectrometer

abstract:
  Electroproduction of exclusive $\phi$ vector mesons has been studied with the
CLAS detector in the kinematical range $1.4\leq Q^2\leq 3.8$ GeV$^{2}$,
$0.0\leq t^{\prime}\leq 3.6$ GeV$^{2}$, and $2.0\leq W\leq 3.0$ GeV. The
scaling exponent for the total cross section as $1/(Q^2+M_{\phi}^2)^n$ was
determined to be $n=2.49\pm 0.33$. The slope of the four-momentum transfer $t'$
distribution is $b_{\phi}=0.98 \pm 0.17$ GeV$^{-2}$. Under the assumption of
s-channel helicity conservation (SCHC), we determine the ratio of longitudinal
to transverse cross sections to be $R=0.86 \pm 0.24$. A 2-gluon exchange model
is able to reproduce the main features of the data.


title: Nested Cluster Algorithm for Frustrated Quantum Antiferromagnets

abstract:
  Simulations of frustrated quantum antiferromagnets suffer from a severe sign
problem. We solve the ergodicity problem of the loop-cluster algorithm in a
natural way and apply a powerful strategy to address the sign problem. For the
spin 1/2 Heisenberg antiferromagnet on a kagome and on a frustrated square
lattice, a nested cluster algorithm eliminates the sign problem for large
systems. The method is applicable to general lattice geometries but limited to
moderate temperatures.


title: Reinforcement Learning by Value Gradients

abstract:
  The concept of the value-gradient is introduced and developed in the context
of reinforcement learning. It is shown that by learning the value-gradients
exploration or stochastic behaviour is no longer needed to find locally optimal
trajectories. This is the main motivation for using value-gradients, and it is
argued that learning value-gradients is the actual objective of any
value-function learning algorithm for control problems. It is also argued that
learning value-gradients is significantly more efficient than learning just the
values, and this argument is supported in experiments by efficiency gains of
several orders of magnitude, in several problem domains. Once value-gradients
are introduced into learning, several analyses become possible. For example, a
surprising equivalence between a value-gradient learning algorithm and a
policy-gradient learning algorithm is proven, and this provides a robust
convergence proof for control problems using a value function with a general
function approximator.


title:
The effect of rotation on the abundances of the chemical elements of the
  A-type stars in the Praesepe cluster

abstract:
  We study how chemical abundances of late B-, A- and early F-type stars evolve
with time, and we search for correlations between the abundance of chemical
elements and other stellar parameters, such as effective temperature and Vsini.
We have observed a large number of B-, A- and F-type stars belonging to open
clusters of different ages. In this paper we concentrate on the Praesepe
cluster (log t = 8.85), for which we have obtained high resolution, high
signal-to-noise ratio spectra of sixteen normal A- and F-type stars and one Am
star, using the SOPHIE spectrograph of the Observatoire de Haute-Provence. For
all the observed stars, we have derived fundamental parameters and chemical
abundances. In addition, we discuss another eight Am stars belonging to the
same cluster, for which the abundance analysis had been presented in a previous
paper. We find a strong correlation between peculiarity of Am stars and Vsini.
The abundance of the elements underabundant in Am stars increases with Vsini,
while it decreases for the overabundant elements. Chemical abundances of
various elements appear correlated with the iron abundance.


title: Lindelof type of generalization of separability in Banach spaces

abstract:
  We will introduce the countable separation property (CSP) of Banach spaces X,
which is defined as follows: For each subset \mathcal{F} of X^{\ast}, which
separates X, there exists a countable separating subset \mathcal{F}_{0} of
\mathcal{F}. All separable Banach spaces have CSP and plenty of examples of
non-separable CSP spaces are provided. Connections of CSP with
Markucevic-bases, Corson property and related geometric issues are discussed.


title:
The Knight field and the local nuclear dipole-dipole field in an
  (In,Ga)As quantum dot ensemble

abstract:
  We present a comprehensive investigation of the electron-nuclear system of
negatively charged InGaAs/GaAs self-assembled quantum dots under the influence
of weak external magnetic fields (up to 2 mT). We demonstrate that, in contrast
to conventional semiconductor systems, these small fields have a profound
influence on the electron spin dynamics, via the hyperfine interaction. Quantum
dots, with their comparatively limited number of nuclei, present
electron-nuclear behavior that is unique to low-dimensional systems. We show
that the conventional Hanle effect used to measure electron spin relaxation
times, for example, cannot be used in these systems when the spin lifetimes are
long. An individual nucleus in the QD is subject to milli-Tesla effective
fields, arising from the interaction with its nearest-neighbors and with the
electronic Knight field. The alignment of each nucleus is influenced by
application of external fields of the same magnitude. A polarized nuclear
system, which may have an effective field strength of several Tesla, may easily
be influenced by these milli-Tesla fields. This in turn has a dramatic effect
on the electron spin dynamics, and we use this technique to gain a measure of
both the dipole-dipole field and the maximum Knight field in our system, thus
allowing us to estimate the maximum Overhauser field that may be generated at
zero external magnetic field. We also show that one may fine-tune the angle
which the Overhauser field makes with the optical axis.