title: Scaling behavior of online human activity

abstract:
  The rapid development of Internet technology enables human explore the web
and record the traces of online activities. From the analysis of these
large-scale data sets (i.e. traces), we can get insights about dynamic behavior
of human activity. In this letter, the scaling behavior and complexity of human
activity in the e-commerce, such as music, book, and movie rating, are
comprehensively investigated by using detrended fluctuation analysis technique
and multiscale entropy method. Firstly, the interevent time series of rating
behaviors of these three type medias show the similar scaling property with
exponents ranging from 0.53 to 0.58, which implies that the collective
behaviors of rating media follow a process embodying self-similarity and
long-range correlation. Meanwhile, by dividing the users into three groups
based their activities (i.e., rating per unit time), we find that the scaling
exponents of interevent time series in three groups are different. Hence, these
results suggest the stronger long-range correlations exist in these collective
behaviors. Furthermore, their information complexities vary from three groups.
To explain the differences of the collective behaviors restricted to three
groups, we study the dynamic behavior of human activity at individual level,
and find that the dynamic behaviors of a few users have extremely small scaling
exponents associating with long-range anticorrelations. By comparing with the
interevent time distributions of four representative users, we can find that
the bimodal distributions may bring the extraordinary scaling behaviors. These
results of analyzing the online human activity in the e-commerce may not only
provide insights to understand its dynamic behaviors but also be applied to
acquire the potential economic interest.


title: Inverses of triangular matrices and bipartite graphs

abstract:
  To a given nonsingular triangular matrix A with entries from a ring, we
associate a weighted bipartite graph G(A) and give a combinatorial description
of the inverse of A by employing paths in G(A). Under a certain condition,
nonsingular triangular matrices A such that A and A^{-1} have the same
zero-nonzero pattern are characterized. A combinatorial construction is given
to construct outer inverses of the adjacency matrix of a weighted tree.


title: Anomalous melting behavior of solid hydrogen at high pressures

abstract:
  Hydrogen is the most abundant element in the universe, and its properties
under conditions of high temperature and pressure are crucial to understand the
interior of of large gaseous planets and other astrophysical bodies. At ultra
high pressures solid hydrogen has been predicted to transform into a quantum
fluid, because of its high zero point motion. Here we report first principles
two phase coexistence and Z method determinations of the melting line of solid
hydrogen in a pressure range spanning from 30 to 600 GPa. Our results suggest
that the melting line of solid hydrogen, as derived from classical molecular
dynamics simulations, reaches a minimum of 367 K at about 430 GPa, at higher
pressures the melting line of the atomics Cs IV phase regain a positive slope.
In view of the possible importance of quantum effects in hydrogen at such low
temperatures, we also determined the melting temperature of the atomic CsIV
phase at pressures of 400, 500, 600 GPa, employing Feynman path integral
simulations. These result in a downward shift of the classical melting line by
about 100 K, and hint at a possible secondary maximum in the melting line in
the region between 500 and 600 GPa, testifying to the importance of quantum
effects in this system. Combined, our results imply that the stability field of
the zero temperature quantum liquid phase, if it exists at all, would only
occur at higher pressures than previously thought.


title:
Unified description of Dirac electrons on a curved surface of
  topological insulators

abstract:
  Existence of a protected surface state described by a massless Dirac equation
is a defining property of the topological insulator. Though this statement can
be explicitly verified on an idealized flat surface, it remains to be addressed
to what extent it could be general. On a curved surface, the surface Dirac
equation is modified by the spin connection terms. Here, in the light of the
differential geometry, we give a general framework for constructing the surface
Dirac equation starting from the Hamiltonian for bulk topological insulators.
The obtained unified description clarifies the physical meaning of the spin
connection.


title: Effect of Ridge-Ridge Interactions in Crumpled Thin Sheets

abstract:
  We study whether and how the energy scalings based on the single-ridge
approximation are revised in an actual crumpled sheet; namely, in the presence
of ridge-ridge interactions. Molecular Dynamics Simulation is employed for this
purpose. In order to improve the data quality, modifications are introduced to
the common protocol. As crumpling proceeds, we find that the average storing
energy changes from being proportional to one-third of the ridge length to a
linear relation, while the ratio of bending and stretching energies decreases
from 5 to 2. The discrepancy between previous simulations and experiments on
the material-dependence for the power-law exponent is resolved. We further
determine the averaged ridge length to scale linearly with the crumpled ball
size $R$, the ridge number as $1/R^2$, and the average storing energy per unit
ridge length as $1/R^{2.364\sim 2.487}$. These results are consistent with the
mean-field predictions. Finally, we extend the existent simulations to the
high-pressure region for completeness, and verify the existence of a new
scaling relation that is more general than the familiar power law at covering
the whole density range.


title:
Radiation of a point charge uniformly moving along the axis of the
  circular disc-loaded waveguide

abstract:
  The space-charge distribution of the electromagnetic field excited by point
charge moving with a constant velocity on the axis of the circular disc-loaded
waveguide was analyzed. The energy losses per structure period numerically were
calculated. With increasing charge energy main features of the waveguide modes
reach some finite values and, so way, define the limit radiation spectrum. The
saturation of the amplitudes of modes (which belongs to the lower part of the
limit spectrum) was observed. The analytical techniques and results of
calculations were discussed with the use of translation symmetry and the
problems that should be noticed were pointed out.


title:
Atomic decomposition of real-variable type for Bergman spaces in the
  unit ball of $\mathbb{C}^n$

abstract:
  In this paper, we show that every (weighted) Bergman space
$\mathcal{A}^p_{\alpha} (\mathbb{B}_n)$ in the complex ball admits an atomic
decomposition of real-variable type for any $0 < p \le 1$ and $\alpha > -1.$
More precisely, for each $f \in \mathcal{A}^p_{\alpha} (\mathbb{B}_n)$ there
exist a sequence of real-variable $(p, \8)_{\alpha}$-atoms $a_k$ and a scalar
sequence $\{\lambda_k \}$ with $\sum_k | \lambda_k |^p < \8$ such that $f =
\sum_k \lambda_k P_{\alpha} (a_k),$ where $P_{\alpha}$ is the Bergman
projection from $L^2_{\alpha} (\mathbb{B}_n)$ onto $\mathcal{A}^2_{\alpha}
(\mathbb{B}_n).$ The proof is constructive, and our construction is based on
some sharp estimates about Bergman metric and Bergman kernel functions in
$\mathbb{B}_n.$


title:
Scaling properties of multiplicity fluctuations in heavy ion collisions
  simulated by AMPT model

abstract:
  Three-dimensional, as well as one- and two-dimensional, studies of
multiplicity fluctuation are performed using AMPT model to generate central
Au-Au collision events at ${\sqrt s_{NN}}= 200$ GeV. Two- and three-dimensional
normalized factorial moments in rapidity, transverse momentum and azimuthal
angle are found to exhibit power-low scaling when partitioning with the same
number of bins in each direction, indicating that the fluctuation are
isotropic, i.e. the fractality is self-similar in multiparticle production of
central Au-Au collisions. Further, we measured the parameter ${\nu}$ which it
characterizes the intermittency indices derived in particular analysis. It is
found that our model result ${\nu_{y{\phi}p_t}}= 1.86{\pm}0.07$ is larger than
${\nu} = 1.304$,which is the value of Ginzburg-Landau type of phase transition.
We also explored the intermittent or fluctuational dependence on the transverse
momentum. The result shows that the intermittency or fluctuation increase
rapidly with the increasing of transverse momentum.


title:
Complex Support Vector Machines for Regression and Quaternary
  Classification

abstract:
  The paper presents a new framework for complex Support Vector Regression as
well as Support Vector Machines for quaternary classification. The method
exploits the notion of widely linear estimation to model the input-out relation
for complex-valued data and considers two cases: a) the complex data are split
into their real and imaginary parts and a typical real kernel is employed to
map the complex data to a complexified feature space and b) a pure complex
kernel is used to directly map the data to the induced complex feature space.
The recently developed Wirtinger's calculus on complex reproducing kernel
Hilbert spaces (RKHS) is employed in order to compute the Lagrangian and derive
the dual optimization problem. As one of our major results, we prove that any
complex SVM/SVR task is equivalent with solving two real SVM/SVR tasks
exploiting a specific real kernel which is generated by the chosen complex
kernel. In particular, the case of pure complex kernels leads to the generation
of new kernels, which have not been considered before. In the classification
case, the proposed framework inherently splits the complex space into four
parts. This leads naturally in solving the four class-task (quaternary
classification), instead of the typical two classes of the real SVM. In turn,
this rationale can be used in a multiclass problem as a split-class scenario
based on four classes, as opposed to the one-versus-all method; this can lead
to significant computational savings. Experiments demonstrate the effectiveness
of the proposed framework for regression and classification tasks that involve
complex data.


title: Eigenvalues of a one-dimensional Dirac operator pencil

abstract:
  We study the spectrum of a one-dimensional Dirac operator pencil, with a
coupling constant in front of the potential considered as the spectral
parameter. Motivated by recent investigations of graphene waveguides, we focus
on the values of the coupling constant for which the kernel of the Dirac
operator contains a square integrable function. In physics literature such a
function is called a confined zero mode. Several results on the asymptotic
distribution of coupling constants giving rise to zero modes are obtained. In
particular, we show that this distribution depends in a subtle way on the sign
variation and the presence of gaps in the potential. Surprisingly, it also
depends on the arithmetic properties of certain quantities determined by the
potential. We further observe that variable sign potentials may produce complex
eigenvalues of the operator pencil. Some examples and numerical calculations
illustrating these phenomena are presented.

categories: math.SP cond-mat.mes-hall math-ph math.MP


title: H$^+$-Eigenvalues of Laplacian and Signless Laplacian Tensors

abstract:
  We propose a simple and natural definition for the Laplacian and the signless
Laplacian tensors of a uniform hypergraph. We study their H$^+$-eigenvalues,
i.e., H-eigenvalues with nonnegative H-eigenvectors, and H$^{++}$-eigenvalues,
i.e., H-eigenvalues with positive H-eigenvectors. We show that each of the
Laplacian tensor, the signless Laplacian tensor and the adjacency tensor has at
most one H$^{++}$-eigenvalue, but has several other H$^+$-eigenvalues. We
identify their largest and smallest H$^+$-eigenvalues, and establish some
maximum and minimum properties of these H$^+$-eigenvalues. We then define
analytic connectivity of a uniform hypergraph and discuss its application in
edge connectivity.


title: Optical control of an atomic inner-shell x-ray laser

abstract:
  X-ray free-electron lasers have had an enormous impact on x-ray science by
achieving femtosecond pulses with unprecedented intensities. However,
present-day facilities operating by the self-amplified spontaneous emission
(SASE) principle have a number of shortcomings, namely, their radiation has a
chaotic pulse profile and short coherence times. We put forward a scheme for a
neon-based atomic inner-shell x-ray laser (XRL) which produces temporally and
spatially coherent subfemtosecond pulses that are controlled by and
synchronized to an optical laser with femtosecond precision. We envision that
such an XRL will allow for numerous applications such as nuclear quantum optics
and the study of ultrafast quantum dynamics of atoms, molecules, and condensed
matter.


title:
Laplacian spectra of recursive treelike small-world polymer networks:
  Analytical solutions and applications

abstract:
  A central issue in the study of polymer physics is to understand the relation
between the geometrical properties of macromolecules and various dynamics, most
of which are encoded in the Laplacian spectra of a related graph describing the
macrostructural structure. In this paper, we introduce a family of treelike
polymer networks with a parameter, which has the same size as the Vicsek
fractals modeling regular hyperbranched polymers. We study some relevant
properties of the networks and show that they have an exponentially decaying
degree distribution and exhibit the small-world behavior. We then study the
Laplacian eigenvalues and their corresponding eigenvectors of the networks
under consideration, with both quantities being determined through the
recursive relations deduced from the network structure. Using the obtained
recursive relations we can find all the eigenvalues and eigenvectors for the
networks with any size. Finally, as some applications, we use the eigenvalues
to study analytically or semi-analytically three dynamical processes occurring
in the networks, including random walks, relaxation dynamics in the framework
of generalized Gaussian structure, as well as the fluorescence depolarization
under quasiresonant energy transfer. Moreover, we compare the results with
those corresponding to Vicsek fractals, and show that the dynamics differ
greatly for the two network families, which thus enables us to distinguish
between them.


title:
Quantitative uniqueness estimates for the general second order elliptic
  equations

abstract:
  In this paper we study quantitative uniqueness estimates of solutions to
general second order elliptic equations with magnetic and electric potentials.
We derive lower bounds of decay rate at infinity for any nontrivial solution
under some general assumptions. The lower bounds depend on asymptotic behaviors
of magnetic and electric potentials. The proof is carried out by the Carleman
method and the bootstrapping arguments.


title:
$d\geq 5$ magnetized static, balanced black holes with $S^2\times
  S^{d-4}$ event horizon topology

abstract:
  We construct static, nonextremal black hole solutions of the Einstein-Maxwell
equations in $d=6,7$ spacetime dimensions, with an event horizon of $S^2\times
S^{d-4}$ topology. These configurations are asymptotically flat, the U(1) field
being purely magnetic, with a spherical distribution of monopole charges but no
net charge measured at infinity. They can be viewed as generalizations of the
$d=5$ static dipole black ring, sharing its basic properties, in particular the
presence of a conical singularity. The magnetized version of these solutions is
constructed by applying a Harrison transformation, which puts them into an
external magnetic field. For $d=5,6,7$, balanced configurations approaching
asymptotically a Melvin universe background are found for a critical value of
the background magnetic field.


title:
Geometric properties of acoustic waves generated by a point source in
  solar-like interior: effects of acoustic cut-off frequency

abstract:
  Acoustic waves generated by a point source in stratified plasma are
considered in this paper. Analytical parametric solution for monochromatic
source is derived for plane-parallel polytrope model of the solar interior. The
solution is used to gain insight into the properties of the generated wavefront
as a function of excitation frequency and depth. A slowly varying pressure
perturbation moving in upper layers of solar photosphere with supersonic speed
is also considered. It is shown to excite acoustic waves putting certain
restrictions upon their geometry of the generated wavefront. The results are
discussed in relation to flare generated sunquakes.


title: $n$-plectic Maxwell Theory

abstract:
  This note provides a detailed treatment of the Multisymplectic Maxwell theory
through the general setting developed in [24] [26] [27]. In particular we
explore the DeDonder-Weyl theory, the question of algebraic and dynamical
observable forms, the copolarization process related to the good search of
canonical forms. Finally, we give - for the two dimensional case - some
indications for the construction of the higher Lepage-Dedecker correspondence,
in the context of the underlying Grassmannian viewpoint.


title:
Stacked topological insulator built from bismuth-based graphene sheet
  analogues

abstract:
  Commonly materials are classified as either electrical conductors or
insulators. The theoretical discovery of topological insulators (TIs) in 2005
has fundamentally challenged this dichotomy. In a TI, spin-orbit interaction
generates a non-trivial topology of the electronic band-structure dictating
that its bulk is perfectly insulating, while its surface is fully conducting.
The first TI candidate material put forward -graphene- is of limited practical
use since its weak spin-orbit interactions produce a band-gap of ~0.01K. Recent
reinvestigation of Bi2Se3 and Bi2Te3, however, have firmly categorized these
materials as strong three-dimensional TI's. We have synthesized the first bulk
material belonging to an entirely different, weak, topological class, built
from stacks of two-dimensional TI's: Bi14Rh3I9. Its Bi-Rh sheets are graphene
analogs, but with a honeycomb net composed of RhBi8-cubes rather than carbon
atoms. The strong bismuth-related spin-orbit interaction renders each
graphene-like layer a TI with a 2400K band-gap.


title: Topological phases in gapped edges of fractionalized systems

abstract:
  Recently, it has been proposed that exotic one-dimensional phases can be
realized by gapping out the edge states of a fractional topological insulator.
The low-energy edge degrees of freedom are described by a chain of coupled
parafermions. We introduce a classification scheme for the phases that can
occur in parafermionic chains. We find that the parafermions support both
topological symmetry fractionalized phases as well as phases in which the
parafermions condense. In the presence of additional symmetries, the phases
form a non-Abelian group. As a concrete example of the classification, we
consider the effective edge model for a $\nu= 1/3$ fractional topological
insulator for which we calculate the entanglement spectra numerically and show
that all possible predicted phases can be realized.


title: Conformal symmetries of the super Dirac operator

abstract:
  In this paper, the Dirac operator, acting on super functions with values in
super spinor space, is defined along the lines of the construction of
generalized Cauchy-Riemann operators by Stein and Weiss. The introduction of
the superalgebra of symmetries osp(m|2n) is a new and essential feature in this
approach. This algebra of symmetries is extended to the algebra of conformal
symmetries osp(m + 1, 1|2n). The kernel of the Dirac operator is studied as a
representation of both algebras. The construction also gives an explicit
realization of the Howe dual pair osp(1|2) x osp(m|2n) < osp(m + 4n|2m + 2n).
Finally, the super Dirac operator gives insight into the open problem of
classifying invariant first order differential operators in super parabolic
geometries.


title:
Equation of state in hybrid stars and the stability window of quark
  matter

abstract:
  Properties of hybrid stars with a mixed phase composed of asymmetric nuclear
matter and strange quark matter are studied. The quark phase is investigated by
the quark quasiparticle model with a self-consistent thermodynamic and
statistical treatment. We present the stability windows of the strange quark
matter with respect to the interaction coupling constant versus the bag
constant. We find that the appearance of the quark-hadron mixed phases is
associated with the meta-stable or unstable regions of the pure quark matter
parameters. The mass-radius relation of the hybrid star is dominated by the
equation of state of quark matter rather than nuclear matter. Due to the
appearance of mixed phase, the mass of hybrid star is reduced to 1.64
M$_{\odot}$ with radius 10.6 km by comparison with neutron star.


title:
The pressure dependence of the phonon spectra and elastic modulus of
  orthorhombic : the method of local density functional

abstract:
  The IR- and Raman-active phonon frequencies, as well as the elastic constants
of orthorhombic GeSe, were calculatedas a function of hydrostatic pressure
using the method of density functional in the ABINIT software package.
Comparison with the published results of theoretical calculations and
experimental data of the pressure dependence of Raman-active phonons has been
carried out. Our calculations show that at a pressure of about 29 GPa the
crystal structure of GeSe undergoes a continuous transition from simple
orthorhombic to base-centered orthorhombic lattice.


title: Algebraic K-Theory of infinity-Operads

abstract:
  The theory of dendroidal sets has been developed to serve as a combinatorial
model for homotopy coherent operads by Moerdijk and Weiss. An infinity-operad
is a dendroidal set D satisfying certain lifting conditions.
  In this paper we give a definition of K-groups K_n(D) for a dendroidal set D.
These groups generalize the K-theory of symmetric monoidal (resp. permutative)
categories and algebraic K-theory of rings. We establish some useful properties
like invariance under the appropriate equivalences and long exact sequences
which allow us to compute these groups in some examples. We show that the
K-theory groups of D can be realized as homotopy groups of a K-theory spectrum
K(D).


title:
\L ojasiewicz-type inequalities and global error bounds for nonsmooth
  definable functions in o-minimal structures

abstract:
  In this paper, we give some {\L}ojasiewicz-type inequalities and a nonsmooth
slope inequality on non-compact domains for continuous definable functions in
an o-minimal structure. We also give a necessary and sufficicent condition for
which global error bound exists. Moreover, we point out the relationship
between the Palais-Smale condition and this global error bound.


title:
Experimental and Theoretical Studies: Analysis of Low-mass Dilepton
  Enhancement in 200 GeV Au+Au Collisions at RHIC (thesis)

abstract:
  In case of an UA(1) symmetry restoration in a hot and dense hadronic matter,
the mass of the produced hadrons and mesons can significantly change, and their
production cross-section can also be modified.
  In this M.Sc. Thesis I search for the signature of an eta' enhancement in the
PHENIX dilepton spectrum in 200 GeV Au+Au collisions, which has a significant
enhancement in the low-mass region, e.g. in the (0.1-1.0) GeV invariant
electron-positron mass range. This is also the region of the eta' meson's
Dalitz-decay (eta'->ee gamma), so the eta' enhancement might be responsible for
at least a part of the excess. Other mesons' (other) properties can also be
changed in the hot, dense medium, but in this thesis I focus on the mass
modification of the eta' meson. To explore the role of eta', I used EXODUS
simulations to generate different dilepton spectra, corresponding to different
eta' properties. The conclusion here was that the excess can not be described
with just the eta' mass modification, but the agreement with data has been
improved significantly.
  Another idea which might brings us closer to understand the excess is to
examine the radial flow of the mesons, which was not included in the original
PHENIX analysis. Radial flow is important in the low-pT range, where it
describes the particles' spectra well: just in the region where the dilepton
spectrum has the most contributions from. Thus examining the effect of the
radial flow seems to be inevitable, as it might be responsible for certain
parts of the excess.
  The results summarized here are work in progress, obtained with the framework
of the PHENIX Collaboration at RHIC.


title: Automatic Verification of Erlang-Style Concurrency

abstract:
  This paper presents an approach to verify safety properties of Erlang-style,
higher-order concurrent programs automatically. Inspired by Core Erlang, we
introduce Lambda-Actor, a prototypical functional language with
pattern-matching algebraic data types, augmented with process creation and
asynchronous message-passing primitives. We formalise an abstract model of
Lambda-Actor programs called Actor Communicating System (ACS) which has a
natural interpretation as a vector addition system, for which some verification
problems are decidable. We give a parametric abstract interpretation framework
for Lambda-Actor and use it to build a polytime computable, flow-based,
abstract semantics of Lambda-Actor programs, which we then use to bootstrap the
ACS construction, thus deriving a more accurate abstract model of the input
program. We have constructed Soter, a tool implementation of the verification
method, thereby obtaining the first fully-automatic, infinite-state model
checker for a core fragment of Erlang. We find that in practice our abstraction
technique is accurate enough to verify an interesting range of safety
properties. Though the ACS coverability problem is Expspace-complete, Soter can
analyse these verification problems surprisingly efficiently.


title: Information Transfer in the Agricultural Sector in Spain

abstract:
  This article examines the structures of information transfer to the
agricultural (production) and agro-alimentary (transformation and
commercialization of the products) sector within Spain. An historical
perspective is provided to better illustrate the reality and complexity of
Spain with regard to the systems of agrarian extension, agricultural research,
the resources provided by Spain's central administration, and the use of
information by related enterprises.
  The Service of Agrarian Extension appeared in Spain in the 1950s, and new
political-administrative structures (agribusiness associations, cooperatives)
were founded when Spain became a democratic nation in the late 1970s and with
the arrival of electronic information, largely in the 1990s. We describe the
research and technological centers supporting innovation in the agro-alimentary
sector and the communication media dedicated to the agricultural sector. The
article illustrates that the systems of agricultural information in Spain have
been largely derived from initiatives of the Public Administration, with few
private initiatives.


title: On some extension theorems for multifunctions

abstract:
  In this short note we give counterexamples to several results related to
extension theorems published recently.


title: Aggregate geometry in amyloid fibril nucleation

abstract:
  We present and study a minimal structure-based model for the self-assembly of
peptides into ordered beta-sheet-rich fibrils. The peptides are represented by
unit-length sticks on a cubic lattice and interact by hydrogen bonding and
hydrophobicity forces. By Monte Carlo simulations with >100,000 peptides, we
show that fibril formation occurs with sigmoidal kinetics in the model. To
determine the mechanism of fibril nucleation, we compute the joint distribution
in length and width of the aggregates at equilibrium, using an efficient
cluster move and flat-histogram techniques. This analysis, based on simulations
with 256 peptides in which aggregates form and dissolve reversibly, shows that
the main free-energy barriers that a nascent fibril has to overcome are
associated with changes in width.


title: Evolution PDEs and augmented eigenfunctions. Finite interval

abstract:
  The so-called unified method expresses the solution of an initial-boundary
value problem (IBVP) for an evolution PDE in the finite interval in terms of an
integral in the complex Fourier (spectral) plane. Simple IBVP, which will be
referred to as problems of type~I, can be solved via a classical transform
pair. For example, the Dirichlet problem of the heat equation can be solved in
terms of the transform pair associated with the Fourier sine series. Such
transform pairs can be constructed via the spectral analysis of the associated
spatial operator. For more complicated IBVP, which will be referred to as
problems of type~II, there does \emph{not} exist a classical transform pair and
the solution \emph{cannot} be expressed in terms of an infinite series. Here we
pose and answer two related questions: first, does there exist a
(non-classical) transform pair capable of solving a type~II problem, and
second, can this transform pair be constructed via spectral analysis? The
answer to both of these questions is positive and this motivates the
introduction of a novel class of spectral entities. We call these spectral
entities augmented eigenfunctions, to distinguish them from the generalised
eigenfunctions described in the sixties by Gel'fand and his co-authors.


title:
The extrasolar planet Gliese 581 d: a potentially habitable planet?
  (Corrigendum to arXiv:1009.5814)

abstract:
  We report here that the equation for H2O Rayleigh scattering was incorrectly
stated in the original paper [arXiv:1009.5814]. Instead of a quadratic
dependence on refractivity r, we accidentally quoted an r^4 dependence. Since
the correct form of the equation was implemented into the model, scientific
results are not affected.


title: The influence of chemical composition on models of Type Ia supernovae

abstract:
  Type Ia supernovae are bright stellar explosions distinguished by
standardizable light curves that allow for their use as distance indicators for
cosmological studies. Despite the highly successful use of these events in this
capacity, many fundamental questions remain. Contemporary research investigates
how properties of the progenitor system that follow from the host galaxy such
as composition and age influence the brightness of an event with the goal of
better understanding and assessing the intrinsic scatter in the brightness. We
provide an overview of these supernovae and proposed progenitor systems, all of
which involve one or more compact stars known as white dwarfs. We describe
contemporary research investigating how the composition and structure of the
progenitor white dwarf systematically influences the explosion outcome assuming
the progenitor is a single white dwarf that has gained mass from a companion.
We present results illustrating some of these systematic effects from our
research.


title: On the relative Cohen-Macaulay modules

abstract:
  Let $R$ be a commutative Noetherian local ring and let $\fa$ be a proper
ideal of $R$. A non-zero finitely generated $R$-module $M$ is called relative
Cohen-Macaulay with respect to $\fa$ if there is precisely one non vanishing
local cohomology modules $\H_{\fa}^{i}(M)$ of $M$. In this paper, as a main
result, it is shown that if $M$ is a Gorenstein $R$--module, then
$\H_{\fa}^{i}(M)=0$ for all $i\neq c$ where $c=\h_{M}\fa$ is completely encoded
in homological properties of $\H_{\fa}^{c}(M)$, in particular in its Bass
numbers. Notice that, this result provides a generalization of a result of M.
Hellus and P. Schenzel which has been proved before, as a main result, in the
case where $M=R$.


title:
Aggregation of autoregressive random fields and anisotropic long-range
  dependence

abstract:
  We introduce the notions of scaling transition and distributional long-range
dependence for stationary random fields $Y$ on $\mathbb {Z}^2$ whose normalized
partial sums on rectangles with sides growing at rates $O(n)$ and
$O(n^{\gamma})$ tend to an operator scaling random field $V_{\gamma}$ on
$\mathbb {R}^2$, for any $\gamma>0$. The scaling transition is characterized by
the fact that there exists a unique $\gamma_0>0$ such that the scaling limits
$V_{\gamma}$ are different and do not depend on $\gamma$ for $\gamma>\gamma_0$
and $\gamma<\gamma_0$. The existence of scaling transition together with
anisotropic and isotropic distributional long-range dependence properties is
demonstrated for a class of $\alpha$-stable $(1<\alpha\le2)$ aggregated
nearest-neighbor autoregressive random fields on $\mathbb{Z}^2$ with a scalar
random coefficient $A$ having a regularly varying probability density near the
"unit root" $A=1$.


title:
Asymptotic behavior of Nambu-Bethe-Salpeter wave functions for
  multi-particles in quantum field theories

abstract:
  We derive asymptotic behaviors of the Nambu-Bethe-Salpeter (NBS) wave
function at large space separations for systems with more than 2 particles in
quantum field theories. To deal with $n$-particles in the center of mass flame
coherently, we introduce the Jacob coordinates of $n$ particles and then
combine their $3(n-1)$ coordinates into the one spherical coordinate in
$D=3(n-1)$ dimensions. We parametrize on-shell $T$-matrix for $n$-particle
system of scalar fields at low energy, using the unitarity constraint of the
$S$-matrix. We then express asymptotic behaviors of the NBS wave function for
$n$ particles at low energy, in terms of parameters of $T$-matrix, and show
that the NBS wave function carry the information of $T$-matrix such as phase
shifts and mixing angles of the $n$-particle system in its own asymptotic
behavior, so that the NBS wave function can be considered as the scattering
wave of $n$-particles in quantum mechanics. This property is one of the
essential ingredients of the HAL QCD scheme to define "potential" from the NBS
wave function in quantum field theories such as QCD. Our results, together with
an extension to systems with spin 1/2 particles, justify the HAL QCD's
definition of potentials for 3 or more nucleons(baryons) in terms the NBS wave
functions.


title:
Medical Information Embedding in Compressed Watermarked Intravascular
  Ultrasound Video

abstract:
  In medical field, intravascular ultrasound (IVUS) is a tomographic imaging
modality, which can identify the boundaries of different layers of blood
vessels. IVUS can detect myocardial infarction (heart attack) that remains
ignored and unattended when only angioplasty is done. During the past decade,
it became easier for some individuals or groups to copy and transmits digital
information without the permission of the owner. For increasing authentication
and security of copyrights, digital watermarking, an information hiding
technique, was introduced. Achieving watermarking technique with lesser amount
of distortion in biomedical data is a challenging task. Watermark can be
embedded into an image or in a video. As video data is a huge amount of
information, therefore a large storage area is needed which is not feasible. In
this case motion vector based video compression is done to reduce size. In this
present paper, an Electronic Patient Record (EPR) is embedded as watermark
within an IVUS video and then motion vector is calculated. This proposed method
proves robustness as the extracted watermark has good PSNR value and less MSE.


title:
Radio-frequency spectroscopy of a strongly interacting spin-orbit
  coupled Fermi gas

abstract:
  We investigate experimentally and theoretically radio-frequency spectroscopy
and pairing of a spin-orbit-coupled Fermi gas of $^{40}$K atoms near a Feshbach
resonance at $B_{0}=202.2$ G. Experimentally, the integrated spectroscopy is
measured, showing characteristic blue and red shifts in the atomic and
molecular responses, respectively, with increasing spin-orbit coupling.
Theoretically, a smooth transition from atomic to molecular responses in the
momentum-resolved spectroscopy is predicted, with a clear signature of
anisotropic pairing at and below resonance. Our many-body prediction agrees
qualitatively well with the observed spectroscopy near the Feshbach resonance.


title:
Ab initio derivation of Hubbard models for cold atoms in optical
  lattices

abstract:
  We derive ab initio local Hubbard models for several optical lattice
potentials of current interest, including the honeycomb and Kagom\'{e}
lattices, verifying their accuracy on each occasion by comparing the
interpolated band structures against the originals. To achieve this, we
calculate the maximally-localized generalized Wannier basis by implementing the
steepest-descent algorithm of Marzari and Vanderbilt [N. Marzari and D.
Vanderbilt, Phys. Rev. B 56, 12847 (1997)] directly in one and two dimensions.
To avoid local minima we develop an initialization procedure that is both
robust and requires no prior knowledge of the optimal Wannier basis. The MATLAB
code that implements our full procedure is freely available online at
http://ccpforge.cse.rl.ac.uk/gf/project/mlgws/.


title:
Coulomb correlations in the honeycomb lattice: role of translation
  symmetry

abstract:
  The effect of Coulomb correlations in the half-filled Hubbard model of the
honeycomb lattice is studied within the dynamical cluster approximation (DCA)
combined with exact diagonalization (ED) and continuous-time quantum Monte
Carlo (QMC). The important difference between this approach and the previously
employed cluster dynamical mean field theory (CDMFT) is that DCA preserves the
translation symmetry of the system, while CDMFT violates this symmetry. As the
Dirac cones of the honeycomb lattice are the consequence of perfect long-range
order, DCA yields semi-metallic behavior at small onsite Coulomb interactions
$U$, whereas CDMFT gives rise to a spurious excitation gap even for very small
$U$. This basic difference between the two cluster approaches is found
regardless of whether ED or QMC is used as the impurity solver. At larger
values of $U$, the lack of translation symmetry becomes less important, so that
the CDMFT reveals a Mott gap, in qualitative agreement with large-scale QMC
calculations. In contrast, the semi-metallic phase obtained in DCA persists
even at $U$ values where CDMFT and large-scale QMC consistently show Mott
insulating behavior.


title: Expensive Optimisation: A Metaheuristics Perspective

abstract:
  Stochastic, iterative search methods such as Evolutionary Algorithms (EAs)
are proven to be efficient optimizers. However, they require evaluation of the
candidate solutions which may be prohibitively expensive in many real world
optimization problems. Use of approximate models or surrogates is being
explored as a way to reduce the number of such evaluations. In this paper we
investigated three such methods. The first method (DAFHEA) partially replaces
an expensive function evaluation by its approximate model. The approximation is
realized with support vector machine (SVM) regression models. The second method
(DAFHEA II) is an enhancement on DAFHEA to accommodate for uncertain
environments. The third one uses surrogate ranking with preference learning or
ordinal regression. The fitness of the candidates is estimated by modeling
their rank. The techniques' performances on some of the benchmark numerical
optimization problems have been reported. The comparative benefits and
shortcomings of both techniques have been identified.


title: Low-temperature thermal expansion of rock-salt ZnO

abstract:
  Lattice parameter of metastable high-pressure phase of zinc oxide, rock-salt
ZnO was measured in the 10-300 K temperature range using synchrotron X-ray
powder diffraction. No phase transition was observed down to 10 K. The lattice
parameter of rock-salt ZnO was found to increase from 4.266 {\AA} in the 10-80
K range up to 4.2752(3) {\AA} at 298 K, while the volume thermal expansion
coefficient increases from slight negative values below 40 K up to
4.77\times10^-5 K^-1 at 298 K.


title:
Ion temperature profile stiffness: non-linear gyrokinetic simulations
  and comparison with experiment

abstract:
  Recent experimental observations at JET show evidence of reduced ion
temperature profile stiffness, hypothesised to be due to concomitant low
magnetic shear (s) and significant toroidal rotational flow shear. Non-linear
gyrokinetic simulations are performed, aiming to investigate the physical
mechanism behind the observations. A comprehensive set of simulations are
carried out, comparing the impact on the ion heat flux of various parameters
that differ within the data-set. These parameters include q, s, rotation,
effect of rotation on the magnetohydrodynamic (MHD) equilibrium, R/L_n, beta_e,
Z_eff, and the fast particle content. The effect of toroidal flow shear itself
is not predicted by the simulations to lead to a significant reduction in ion
heat flux, due both to an insufficient magnitude of flow shear and significant
parallel velocity gradient destabilisation. It is however found that non-linear
electromagnetic effects due to both thermal and fast-particle pressure
gradients, even at low beta_e, can significantly reduce the profile stiffness.
A total of five discharges are examined, at both inner and outer radii. For all
cases studied, the simulated and experimental ion heat flux values agree within
reasonable variations of input parameters around the experimental
uncertainties.


title:
The Outburst of the Blazar S5 0716+71 in 2011 October: Shock in a
  Helical Jet

abstract:
  We present the results of optical (R band) photometric and polarimetric
monitoring and Very Long Baseline Array (VLBA) imaging of the blazar S5
0716+714 along with Fermi gamma-ray data during a multi-waveband outburst in
2011 October. We analyze total and polarized intensity images of the blazar
obtained with the VLBA at 43 GHz during and after the outburst. Monotonic
rotation of the linear polarization vector at a rate of >50 degrees per night
coincided with a sharp maximum in gamma-ray and optical flux. At the same time,
within the uncertainties, a new superluminal knot appeared, with an apparent
speed of ~21c. The general multi-frequency behavior of the outburst can be
explained within the framework of a shock wave propagating along a helical path
in the blazar's jet.


title: The Vernam cipher is robust to small deviations from randomness

abstract:
  The Vernam cipher (or one-time pad) has played an important rule in
cryptography because it is a perfect secrecy system. For example, if an English
text (presented in binary system) $X_1 X_2 ... $ is enciphered according to the
formula $Z_i = (X_i + Y_i) \mod 2 $, where $Y_1 Y_2 ...$ is a key sequence
generated by the Bernoulli source with equal probabilities of 0 and 1, anyone
who knows $Z_1 Z_2 ... $ has no information about $X_1 X_2 ... $ without the
knowledge of the key $Y_1 Y_2 ...$. (The best strategy is to guess $X_1 X_2 ...
$ not paying attention to $Z_1 Z_2 ... $.)
  But what should one say about secrecy of an analogous method where the key
sequence $Y_1 Y_2 ...$ is generated by the Bernoulli source with a small bias,
say, $P(0) = 0.49, $ $ P(1) = 0.51$? To the best of our knowledge, there are no
theoretical estimates for the secrecy of such a system, as well as for the
general case where $X_1 X_2 ... $ (the plaintext) and key sequence are
described by stationary ergodic processes. We consider the running-key ciphers
where the plaintext and the key are generated by stationary ergodic sources and
show how to estimate the secrecy of such systems. In particular, it is shown
that, in a certain sense, the Vernam cipher is robust to small deviations from
randomness.


title:
Observable phi-eta-star at LHC and second-order QED matrix element in
  Z/gamma to l+ l- decays

abstract:
  In a recent publication by ATLAS collaboration a new observable, the
so-called phi-star angle, was used for precise measurement of transverse Z
momentum. One of the dominant systematic errors for this measurement originates
from the theoretical control of QED final-state bremsstrahlung. At present, it
is estimated at the 0.3% level for the shape of the phi-star distribution. In
this paper we discuss the possible effects of the second-order QED matrix
element for that quantity. For that purpose, results from simulations based on
the Yennie--Frautchi--Suura (YFS) exponentiation and featuring the second-order
matrix elements are used and compared with the case when the matrix element is
restricted to the first order. From this study we conclude that in order to
reach the precision below 0.3% for the phi-star distribution at the LHC,
inclusion of the second-order QED matrix element in a respective Monte Carlo
event generator is necessary.


title:
Clustering on Multi-Layer Graphs via Subspace Analysis on Grassmann
  Manifolds

abstract:
  Relationships between entities in datasets are often of multiple nature, like
geographical distance, social relationships, or common interests among people
in a social network, for example. This information can naturally be modeled by
a set of weighted and undirected graphs that form a global multilayer graph,
where the common vertex set represents the entities and the edges on different
layers capture the similarities of the entities in term of the different
modalities. In this paper, we address the problem of analyzing multi-layer
graphs and propose methods for clustering the vertices by efficiently merging
the information provided by the multiple modalities. To this end, we propose to
combine the characteristics of individual graph layers using tools from
subspace analysis on a Grassmann manifold. The resulting combination can then
be viewed as a low dimensional representation of the original data which
preserves the most important information from diverse relationships between
entities. We use this information in new clustering methods and test our
algorithm on several synthetic and real world datasets where we demonstrate
superior or competitive performances compared to baseline and state-of-the-art
techniques. Our generic framework further extends to numerous analysis and
learning problems that involve different types of information on graphs.


title: The first cohomology of separably rationally connected varieties

abstract:
  In this short note we prove that if X is a separably rationally connected
variety over an algebraically closed field of positive characteristic, then
H^1(X, O_X)=0.


title: khmer: Working with Big Data in Bioinformatics

abstract: We introduce design and optimization considerations for the 'khmer' package.


title:
Magnetization study of the energy scales in YbRh$_{2}$Si$_{2}$ under
  chemical pressure

abstract:
  We present a systematic study of the magnetization in YbRh$_{2}$Si$_{2}$
under slightly negative (6?% Ir substitution) and positive (7% Co substitution)
chemical pressure. We show how the critical field $H_{0}$, associated with the
high-field Lifshitz transitions, is shifted to lower (higher) values with Co
(Ir) substitution. The critical field $H_{\mathrm{N}}$, which identifies the
boundary line of the antiferromagnetic (AFM) phase $T_{\mathrm{N}}(H)$
increases with positive pressure and it approaches zero with 6% Ir
substitution. On the other side, the crossover field $H^{*}$, associated with
the energy scale $T^{*}(H)$ where a reconstruction of the Fermi surface has
been observed, is not much influenced by the chemical substitution.}{Following
the analysis proposed in
Refs.\,\cite{Paschen2004,Gegenwart2007,Friedemann2009,Tokiwa2009a} we have
fitted the quantity $\tilde{M}(H)=M+(dM/dH)H$ with a crossover function to
indentify $H^{*}$. The $T^{*}(H)$ line follows an almost linear $H$-dependence
at sufficiently high fields outside the AFM phase, but it deviates from
linearity at $T \le T_{\mathrm{N}}(0)$ and in
Yb(Rh$_{0.93}$Co$_{0.07}$)$_{2}$Si$_{2}$ it changes slope clearly inside the
AFM phase. Moreover, the FWHM of the fit function depends linearly on
temperature outside the phase, but remains constant inside, suggesting either
that such an analysis is valid only for $T \ge T_{\mathrm{N}}(0)$ or that the
Fermi surface changes continuously at $T = 0$ inside the AFM phase.}}


title:
Mutual adaptation of a Faraday instability pattern with its flexible
  boundaries in floating fluid drops

abstract:
  Hydrodynamic instabilities are usually investigated in confined geometries
where the resulting spatiotemporal pattern is constrained by the boundary
conditions. Here we study the Faraday instability in domains with flexible
boundaries. This is implemented by triggering this instability in floating
fluid drops. An interaction of Faraday waves with the shape of the drop is
observed, the radiation pressure of the waves exerting a force on the surface
tension held boundaries. Two regimes are observed. In the first one there is a
coadaptation of the wave pattern with the shape of the domain so that a steady
configuration is reached. In the second one the radiation pressure dominates
and no steady regime is reached. The drop stretches and ultimately breaks into
smaller domains that have a complex dynamics including spontaneous propagation.


title:
Gated Silicene as a tunable source of nearly 100% spin-polarized
  electrons

abstract:
  Silicene is a one-atom-thick 2D crystal of silicon with a hexagonal lattice
structure that is related to that of graphene but with atomic bonds that are
buckled rather than flat. This buckling confers advantages on silicene over
graphene, because it should, in principle, generate both a band gap and
polarized spin-states that can be controlled with a perpendicular electric
field. Here we use first-principles calculations to show that field-gated
silicene possesses two gapped Dirac cones exhibiting nearly 100%
spin-polarization, situated at the corners of the Brillouin zone. Using this
fact, we propose a design for a silicene-based spin-filter that should enable
the spin-polarization of an output current to be switched electrically, without
switching external magnetic fields. Our quantum transport calculations indicate
that the proposed designs will be highly efficient (nearly 100% spin
polarization) and robust against weak disorder and edge imperfections. We also
propose a Y-shaped spin/valley separator that produces spin-polarized current
at two output terminals with opposite spins.


title:
Identity Families of Multiple Harmonic Sums and Multiple Zeta (Star)
  Values

abstract:
  In this paper we present many new families of identities for multiple
harmonic sums using binomial coefficients. Some of these generalize a few
recent results of Hessami Pilehrood et al. As applications we prove several
conjectures involving multiple zeta star values (MZSV): the Two-one formula
conjectured by Ohno and Zudilin, and a few conjectures of Imatomi et al.
involving 2-3-2-1 type MZSV, where 2 means some finite string of 2's


title:
Adiabatic transformation as a search tool for new topological
  insulators: distorted ternary Li$_2$AgSb-class semiconductors and related
  compounds

abstract:
  We demonstrate that first-principles based adiabatic continuation approach is
a very powerful and efficient tool for constructing topological phase diagrams
and locating non-trivial topological insulator materials. Using this technique,
we predict that the ternary intermetallic series Li$_2M'X$ where $M'$=Cu, Ag,
Au, or Cd, and $X$=Sb, Bi, or Sn, hosts a number of topological insulators with
remarkable functional variants and tunability. We also predict that several
III-V semimetallic compounds are topologically non-trivial. We construct a
topological phase diagram in the parameter space of the atomic numbers of atoms
in Li$_2M'X$ compounds, which places a large number of topological materials
presented in this work as well as in earlier studies within a single unified
topological framework. Our results demonstrate the efficacy of adiabatic
continuation as a useful tool for exploring topologically nontrivial alloying
systems and for identifying new topological insulators even when the underlying
lattice does not possess inversion symmetry, and the approaches based on parity
analysis are not viable.


title: Constructing permutation polynomials over finite fields

abstract:
  In this paper, we construct several new permutation polynomials over finite
fields. First, using the linearized polynomials, we construct the permutation
polynomial of the form $\sum_{i=1}^k(L_{i}(x)+\gamma_i)h_i(B(x))$ over ${\bf
F}_{q^{m}}$, where $L_i(x)$ and $B(x)$ are linearized polynomials. This extends
a theorem of Coulter, Henderson and Matthews. Consequently, we generalize a
result of Marcos by constructing permutation polynomials of the forms $x
h(\lambda_{j}(x))$ and $xh(\mu_{j}(x))$, where $\lambda_{j}(x)$ is the $j$-th
elementary symmetric polynomial of $x, x^{q}, ..., x^{q^{m-1}}$ and
$\mu_{j}(x)=\textup{Tr}_{{\bf F}_{q^{m}}/{\bf F}_{q}}(x^{j})$. This answers an
open problem raised by Zieve in 2010. Finally, by using the linear translator,
we construct the permutation polynomial of the form
$L_1(x)+L_{2}(\gamma)h(f(x))$ over ${\bf F}_{q^{m}}$, which extends a result of
Kyureghyan.


title: Higgs decays to gamma l+ l- in the standard model

abstract:
  The radiative Higgs decays h -> gamma l+l- with l=e,mu and tau are analyzed
in the standard model using m_h=125 GeV. Both tree and one-loop diagrams for
the processes are evaluated. In addition to their decay rates and dilepton
invariant mass distributions, we focus on the forward-back asymmetries in these
modes. Our calculation shows that the forward-backward asymmetries in h ->
gamma e+e- and h -> gamma mu+mu- could be up to 10^{-2} while in the tau+tau-
final state, these asymmetries are below 1%. Thus the forward-backward
asymmetries in h -> gamma l+l- might be interesting observables in the future
precise experiments both to test our understanding of Higgs physics in the
standard model and to probe the novel Higgs dynamics in new physics scenarios.


title:
Small-q phonon mediated singlet and chiral spin triplet
  superconductivity in LiFeAs

abstract:
  We report fully momentum dependent, self-consistent calculations of the gap
symmetry, Fermi surface (FS) anisotropy and Tc of superconducting (SC) LiFeAs
using the experimental band structure and a realistic small-q electron phonon
interaction within the framework of Migdal-Eliashberg theory. In the
stoichiometric regime, we find the exact s++ gap as reported by ARPES. For
slight deviations from stoichiometry towards electron doping, we find that a
chiral triplet p_x+ip_y state stabilizes near Tc and that at lower temperatures
a transition from the triplet to singlet s+- SC takes place. Further doping
stabilizes the chiral p-wave SC down to T=0. Precisely the same behavior was
observed recently by NMR. Our results provide a natural and universal
understanding of the conflicting experimental observations in LiFeAs.


title: Targets for Precision Measurements

abstract:
  The general properties needed in targets (sources) for high precision, high
accuracy measurements are reviewed. The application of these principles to the
problem of developing targets for the Fission TPC is described. Longer term
issues, such as the availability of actinide materials, improved knowledge of
energy losses and straggling and the stability of targets during irradiation
are also discussed.


title:
Analysis of the radiative $\Lambda_b\rightarrow \Lambda \gamma$
  transition in SM and scenarios with one or two universal extra dimensions

abstract:
  We investigate the radiative process of the $\Lambda_b\rightarrow \Lambda
\gamma$ in the standard model as well as models with one or two compact
universal extra dimensions. Using the form factors entered to the low energy
matrix elements, calculated via light cone QCD in full theory, we calculate the
total decay width and branching ratio of this decay channel. We compare the
results of the extra dimensional models with those of the standard model on the
considered physical quantities and look for the deviations of the results from
the standard model predictions at different values of the compactification
scale (1/R).


title: Asymptotic vacua with higher derivatives

abstract:
  We study limits of vacuum, isotropic universes in the full, effective,
four-dimensional theory with higher derivatives. We show that all flat vacua as
well as general curved ones are globally attracted by the standard, square root
scaling solution at early times. Open vacua asymptote to horizon-free, Milne
states in both directions while closed universes exhibit more complex
logarithmic singularities, starting from initial data sets of a possibly
smaller dimension. We also discuss the relation of our results to the
asymptotic stability of the passage through the singularity in ekpyrotic and
cyclic cosmologies.


title:
Off-resonant Raman echo quantum memory on atoms with natural
  inhomogeneous broadening in optical QED cavity

abstract:
  A new scheme of photon echo based quantum memory in the optimal optical QED
cavity with off-resonant Raman atomic transition is proposed. The scheme
employs the atomic ensembles characterized by an optically thin resonant
transition and natural inhomogeneous broadening of the resonant line composed
of the arbitrary narrow homogeneous spectral components. The scheme provides
robust and quite simple coherent control of the light-atoms dynamics that can
be implemented by using an existing optical technique and opens a practical way
for realization of the efficient long-lived multi-mode optical quantum memory.


title: COBRA: A Combined Regression Strategy

abstract:
  A new method for combining several initial estimators of the regression
function is introduced. Instead of building a linear or convex optimized
combination over a collection of basic estimators $r_1,\dots,r_M$, we use them
as a collective indicator of the proximity between the training data and a test
observation. This local distance approach is model-free and very fast. More
specifically, the resulting nonparametric/nonlinear combined estimator is shown
to perform asymptotically at least as well in the $L^2$ sense as the best
combination of the basic estimators in the collective. A companion R package
called \cobra (standing for COmBined Regression Alternative) is presented
(downloadable on
\url{http://cran.r-project.org/web/packages/COBRA/index.html}). Substantial
numerical evidence is provided on both synthetic and real data sets to assess
the excellent performance and velocity of our method in a large variety of
prediction problems.


title:
Sign-Preserving Property for Some Fourth-Order Elliptic Operators in One
  Dimension and Radial Symmetry

abstract:
  For a class of one-dimensional linear elliptic fourth-order equations with
homogeneous Dirichlet boundary conditions it is shown that a non-positive and
non-vanishing right-hand side gives rise to a negative solution. A similar
result is obtained for the same class of equations for radially symmetric
solutions in a ball or in an annulus. Several applications are given, including
applications to nonlinear equations and eigenvalue problems.


title:
Some numerical aspects of the conservative PSM scheme in a 4D
  drift-kinetic code

abstract:
  The purpose of this work is simulation of magnetised plasmas in the ITER
project framework. In this context, kinetic Vlasov-Poisson like models are used
to simulate core turbulence in the tokamak in a toroidal geometry. This leads
to heavy simulations because a 6D dimensional problem has to be solved, even if
reduced to a 5D in so called gyrokinetic models. Accurate schemes, parallel
algorithms need to be designed to bear these simulations. This paper describes
the numerical studies to improve robustness of the conservative PSM scheme in
the context of its development in the GYSELA code. In this paper, we only
consider the 4D drift-kinetic model which is the backbone of the 5D gyrokinetic
models and relevant to build a robust and accurate numerical method.


title: Oka properties of ball complements

abstract:
  Let $n>1$ be an integer. We prove that holomorphic maps from Stein manifolds
$X$ of dimension $<n$ to the complement $\mathbb{C}^n\setminus L$ of a compact
convex set $L\subset\mathbb{C}^n$ satisfy the basic Oka property with
approximation and interpolation. If $L$ is polynomially convex then the same
holds when $2\dim X < n$. We also construct proper holomorphic maps, immersions
and embeddings $X\to\mathbb{C}^n$ with additional control of the range, thereby
extending classical results of Remmert, Bishop and Narasimhan.


title: Nonlinear transverse waves in deformed dispersive solids

abstract:
  We present a phenomenological approach to dispersion in nonlinear elasticity.
A simple, thermomechanically sound, constitutive model is proposed to describe
the (non-dissipative) properties of a hyperelastic dispersive solid, without
recourse to a microstructure or a special geometry. As a result, nonlinear and
dispersive waves can travel in the bulk of such solids, and special waves
emerge, some classic (periodic waves or pulse solitary waves of infinite
extend), some exotic (kink or pulse waves of compact support). We show that for
incompressible dispersive power-law solids and forth-order elasticity solids,
solitary waves can however only exist in the case of linear transverse
polarization. We also study the influence of pre-stretch and hardening. We
provide links with other (quasi-continuum, asymptotic) theories; in particular,
an appropriate asymptotic multiscale expansion specializes our exact equations
of motion to the vectorial MKdV equation, for any hyperelastic material.


title:
Classification of polarized symplectic automorphisms of Fano varieties
  of cubic fourfolds

abstract:
  We classify the polarized symplectic automorphisms of Fano varieties of
smooth cubic fourfolds (equipped with the Pl\"ucker polarization) and study the
fixed loci.


title:
Adaptive Network Dynamics and Evolution of Leadership in Collective
  Migration

abstract:
  The evolution of leadership in migratory populations depends not only on
costs and benefits of leadership investments but also on the opportunities for
individuals to rely on cues from others through social interactions. We derive
an analytically tractable adaptive dynamic network model of collective
migration with fast timescale migration dynamics and slow timescale adaptive
dynamics of individual leadership investment and social interaction. For large
populations, our analysis of bifurcations with respect to investment cost
explains the observed hysteretic effect associated with recovery of migration
in fragmented environments. Further, we show a minimum connectivity threshold
above which there is evolutionary branching into leader and follower
populations. For small populations, we show how the topology of the underlying
social interaction network influences the emergence and location of leaders in
the adaptive system. Our model and analysis can describe other adaptive network
dynamics involving collective tracking or collective learning of a noisy,
unknown signal, and likewise can inform the design of robotic networks where
agents use decentralized strategies that balance direct environmental
measurements with agent interactions.


title: Black holes in realistic branes: black string-like objects?

abstract:
  A realistic model describing a black string-like object in an expanding
Universe is analyzed in the context of the McVittie's solution of the Einstein
field equations. The bulk metric near the brane is provided analogously to
previous solutions for black strings. In particular, we show that at least when
the Hubble parameter on the brane is positive, a black string-like object seems
to play a fundamental role in the braneworld scenario, generalizing the
standard black strings in the context of a dynamical brane.


title: Topological conjugations are not constructable

abstract:
  We construct two computable topologically conjugate functions for which no
conjugacy is computable, or even hyperarithmetic, resolving an open question of
Kennedy and Stockman.


title: The place of the Sun among the Sun-like stars

abstract:
  Context. Monitoring of the photometric and chromospheric HK emission data
series of stars similar to the Sun in age and average activity level showed
that there is an empirical correlation between the average stellar
chromospheric activity level and the photometric variability. In general, more
active stars show larger photometric variability. Interestingly, the
measurements and reconstructions of the solar irradiance show that the Sun is
significantly less variable than indicated by the empirical relationship. Aims.
We aim to identify possible reasons for the Sun to be currently outside of this
relationship. Methods. We employed different scenarios of solar HK emission and
irradiance variability and compared them with available time series of Sun-like
stars. Results. We show that the position of the Sun on the diagram of
photometric variability versus chromospheric activity changes with time. The
present solar position is different from its temporal mean position as the
satellite era of continuous solar irradiance measurements has accidentally
coincided with a period of unusually high and stable solar activity. Our
analysis suggests that although present solar variability is significantly
smaller than indicated by the stellar data, the temporal mean solar variability
might be in agreement with the stellar data. We propose that the continuation
of the photometric program and its expansion to a larger stellar sample will
ultimately allow us to constrain the historical solar variability.


title: A Unifying Model of Genome Evolution Under Parsimony

abstract:
  We present a data structure called a history graph that offers a practical
basis for the analysis of genome evolution. It conceptually simplifies the
study of parsimonious evolutionary histories by representing both substitutions
and double cut and join (DCJ) rearrangements in the presence of duplications.
The problem of constructing parsimonious history graphs thus subsumes related
maximum parsimony problems in the fields of phylogenetic reconstruction and
genome rearrangement. We show that tractable functions can be used to define
upper and lower bounds on the minimum number of substitutions and DCJ
rearrangements needed to explain any history graph. These bounds become tight
for a special type of unambiguous history graph called an ancestral variation
graph (AVG), which constrains in its combinatorial structure the number of
operations required. We finally demonstrate that for a given history graph $G$,
a finite set of AVGs describe all parsimonious interpretations of $G$, and this
set can be explored with a few sampling moves.


title: Robust Adaptive Dynamic Programming for Optimal Nonlinear Control Design

abstract:
  This paper studies the robust optimal control design for uncertain nonlinear
systems from a perspective of robust adaptive dynamic programming (robust-ADP).
The objective is to fill up a gap in the past literature of ADP where dynamic
uncertainties or unmodeled dynamics are not addressed. A key strategy is to
integrate tools from modern nonlinear control theory, such as the robust
redesign and the backstepping techniques as well as the nonlinear small-gain
theorem, with the theory of ADP. The proposed robust-ADP methodology can be
viewed as a natural extension of ADP to uncertain nonlinear systems. A
practical learning algorithm is developed in this paper, and has been applied
to a sensorimotor control problem.


title:
Faithful actions of the absolute Galois group on connected components of
  moduli spaces

abstract:
  We give a canonical procedure associating to an algebraic number a first a
hyperelliptic curve C_a, and then a triangle curve (D_a, G_a) obtained through
the normal closure of an associated Belyi function. In this way we show that
the absolute Galois group Gal(\bar{\Q} /\Q) acts faithfully on the set of
isomorphism classes of marked triangle curves, and on the set of connected
components of marked moduli spaces of surfaces isogenous to a higher product
(these are the free quotients of a product C_1 x C_2 of curves of respective
genera g_1, g_2 >= 2 by the action of a finite group G). We show then, using
again the surfaces isogenous to a product, first that it acts faithfully on the
set of connected components of moduli spaces of surfaces of general type
(amending an incorrect proof in a previous ArXiv version of the paper); and
then, as a consequence, we obtain that for every element \sigma \in
\Gal(\bar{\Q} /\Q), not in the conjugacy class of complex conjugation, there
exists a surface of general type X such that X and the Galois conjugate surface
X^{\sigma} have nonisomorphic fundamental groups. Using polynomials with only
two critical values, we can moreover exhibit infinitely many explicit examples
of such a situation.


title: Numbers with three close factorizations

abstract:
  In this paper, we study numbers $n$ that can be factored in three different
ways as $n = A_1 B_1 = A_2 B_2 = A_3 B_3$ where $A_1$, $A_2$, $A_3$ are close
to each other and $B_1$, $B_2$, $B_3$ are close to each other.


title:
Continuous Galerkin finite element methods for hyperbolic
  integro-differential equations

abstract:
  A hyperbolic integro-differential equation is considered, as a model problem,
where the convolution kernel is assumed to be either smooth or no worse than
weakly singular. Well-posedness of the problem is studied in the context of
semigroup of linear operators, and regularity of any order is proved for smooth
kernels. Energy method is used to prove optimal order a priori error estimates
for the finite element spatial semidiscrete problem. A continuous space-time
finite element method of order one is formulated for the problem. Stability of
the discrete dual problem is proved, that is used to obtain optimal order a
priori estimates via duality arguments. The theory is illustrated by an
example.


title:
Zero-point attracting projection algorithm for sequential compressive
  sensing

abstract:
  Sequential Compressive Sensing, which may be widely used in sensing devices,
is a popular topic of recent research. This paper proposes an online recovery
algorithm for sparse approximation of sequential compressive sensing. Several
techniques including warm start, fast iteration, and variable step size are
adopted in the proposed algorithm to improve its online performance. Finally,
numerical simulations demonstrate its better performance than the relative art.


title:
The fundamental differences between Quantum Spin Hall edge-states at
  zig-zag and armchair terminations of honeycomb and ruby nets

abstract:
  Combining an analytical and numerical approach we investigate the dispersion
of the topologically protected spin-filtered edge-states of the Quantum Spin
Hall state on honeycomb and ruby nets with zigzag (ZZ) and armchair (AC) edges.
We show that the Fermi velocity of the helical edge-states on ZZ edges
increases linearly with the strength of the spin-orbit coupling (SOC) whereas
for AC edges the Fermi velocity is independent of the SOC. Also the decay
length of edge states into the bulk is dramatically different for AC and ZZ
edges, displaying an inverse functional dependence on the SOC.


title: Which measures of spin-glass overlaps are informative?

abstract:
  The nature of equilibrium states in disordered materials is often studied
using an overlap function P(q), the probability of two configurations having
similarity q. Exact sampling simulations of a two-dimensional proxy for
three-dimensional spin glasses indicate that common measures of P(q) in smaller
samples do not decide between theoretical pictures. Strong corrections result
from P(q) being an average over many scales, as seen in a toy droplet model.
However, the median of the integrals of sample-dependent P(q) curves shows
promise for deciding the thermodynamic behavior.


title: Coherent photoproduction of pi^0- and eta-mesons off 7Li

abstract:
  Coherent photoproduction of $\pi^0$-mesons from threshold ($E_{th} \approx$
136 MeV) throughout the $\Delta$-resonance region and of $\eta$-mesons close to
the production threshold ($E_{th} \approx$ 570 MeV for $\eta$) has been
measured for $^7$Li nuclei. The experiment was performed using the
tagged-photon beam of the Mainz MAMI accelerator with the Crystal Ball and TAPS
detectors combined to give an almost 4$\pi$ solid-angle electromagnetic
calorimeter. The reactions were identified by a combined invariant-mass and
missing-energy analysis. A comparison of the pion data to plane-wave impulse
modelling tests the nuclear mass form factor. So far coherent $\eta$-production
had been only identified for the lightest nuclear systems ($^2$H and $^3$He).
For $^3$He a large enhancement of the cross section above plane-wave
approximations had been reported, indicating the formation of a quasi-bound
state. The present Li-data for $\eta$-production agree with a plane-wave
approximation. Contrary to $^3$He, neither a threshold enhancement of the total
cross section nor a deviation of the angular distributions from the expected
form-factor dependence were observed.


title:
A Robust Zero-point Attraction LMS Algorithm on Near Sparse System
  Identification

abstract:
  The newly proposed $l_1$ norm constraint zero-point attraction Least Mean
Square algorithm (ZA-LMS) demonstrates excellent performance on exact sparse
system identification. However, ZA-LMS has less advantage against standard LMS
when the system is near sparse. Thus, in this paper, firstly the near sparse
system modeling by Generalized Gaussian Distribution is recommended, where the
sparsity is defined accordingly. Secondly, two modifications to the ZA-LMS
algorithm have been made. The $l_1$ norm penalty is replaced by a partial $l_1$
norm in the cost function, enhancing robustness without increasing the
computational complexity. Moreover, the zero-point attraction item is weighted
by the magnitude of estimation error which adjusts the zero-point attraction
force dynamically. By combining the two improvements, Dynamic Windowing ZA-LMS
(DWZA-LMS) algorithm is further proposed, which shows better performance on
near sparse system identification. In addition, the mean square performance of
DWZA-LMS algorithm is analyzed. Finally, computer simulations demonstrate the
effectiveness of the proposed algorithm and verify the result of theoretical
analysis.


title:
Migraine generator network and spreading depression dynamics as
  neuromodulation targets in episodic migraine

abstract:
  Migraine is a common disabling headache disorder characterized by recurrent
episodes sometimes preceded or accompanied by focal neurological symptoms
called aura. The relation between two subtypes, migraine without aura (MWoA)
and migraine with aura (MWA), is explored with the aim to identify targets for
neuromodulation techniques. To this end, a dynamically regulated control system
is schematically reduced to a network of the trigeminal nerve, which innervates
the cranial circulation, an associated descending modulatory network of
brainstem nuclei, and parasympathetic vasomotor efferents. This extends the
idea of a migraine generator region in the brainstem to a larger network and is
still simple and explicit enough to open up possibilities for mathematical
modeling in the future. In this study, it is suggested that the migraine
generator network (MGN) is driven and may therefore respond differently to
different spatio-temporal noxious input in the migraine subtypes MWA and MWoA.
The noxious input is caused by a cortical perturbation of homeostasis, known as
spreading depression (SD). The MGN might even trigger SD in the first place by
a failure in vasomotor control. As a consequence, migraine is considered as an
inherently dynamical disease to which a linear course from upstream to
downstream events would not do justice. Minimally invasive and noninvasive
neuromodulation techniques are briefly reviewed and their rational is discussed
in the context of the proposed mechanism.


title:
A stochastic gradient approach on compressive sensing signal
  reconstruction based on adaptive filtering framework

abstract:
  Based on the methodological similarity between sparse signal reconstruction
and system identification, a new approach for sparse signal reconstruction in
compressive sensing (CS) is proposed in this paper. This approach employs a
stochastic gradient-based adaptive filtering framework, which is commonly used
in system identification, to solve the sparse signal reconstruction problem.
Two typical algorithms for this problem: $l_0$-least mean square ($l_0$-LMS)
algorithm and $l_0$-exponentially forgetting window LMS ($l_0$-EFWLMS)
algorithm are hence introduced here. Both the algorithms utilize a zero
attraction method, which has been implemented by minimizing a continuous
approximation of $l_0$ norm of the studied signal. To improve the performances
of these proposed algorithms, an $l_0$-zero attraction projection ($l_0$-ZAP)
algorithm is also adopted, which has effectively accelerated their convergence
rates, making them much faster than the other existing algorithms for this
problem. Advantages of the proposed approach, such as its robustness against
noise etc., are demonstrated by numerical experiments.


title: Thermal properties of fluorinated graphene

abstract:
  Large scale atomistic simulations using the reactive force field approach
(ReaxFF) are implemented to investigate the thermomechanical properties of
fluorinated graphene (FG). A new set of parameters for the reactive force field
potential (ReaxFF) optimized to reproduce key quantum mechanical properties of
relevant carbon-fluor cluster systems are presented. Molecular dynamics (MD)
simulations are used to investigate the thermal rippling behavior of FG and its
mechanical properties and compare them with graphene (GE), graphane (GA) and a
sheet of BN. The mean square value of the height fluctuations $< h^2>$ and the
height-height correlation function $H(q)$ for different system sizes and
temperatures show that FG is an un-rippled system in contrast to the thermal
rippling behavior of graphene (GE). The effective Young's modulus of a flake of
fluorinated graphene is obtained to be 273 N/m and 250 N/m for a flake of FG
under uniaxial strain along arm-chair and zig-zag direction, respectively.


title: Moments of elliptic integrals and critical $L$-values

abstract:
  We compute the critical $L$-values of some weight 3, 4, or 5 modular forms,
by transforming them into integrals of the complete elliptic integral $K$. In
doing so, we prove closed form formulas for some moments of $K'^3$. Many of our
$L$-values can be expressed in terms of Gamma functions, and this also gives
new lattice sum evaluations.


title: Spiral graphone and one sided fluorographene nano-ribbons

abstract:
  The instability of a free-standing one sided hydrogenated/fluorinated
graphene nano-ribbon, i.e. graphone/fluorographene, is studied using ab-initio,
semiempirical and large scale molecular dynamics simulations. Free standing
semi-infinite arm-chair like hydrogenated/fluorinated graphene (AC-GO/AC-GF)
and boat like hydrogenated/fluorinated graphene (B-GO/B-GF) (nano-ribbons which
are periodic along the zig-zag direction) are unstable and spontaneously
transform into spiral structures. We find that rolled, spiral B-GO and B-GF are
energetically more favorable than spiral AC-GO and AC-GF which is opposite to
the double sided flat hydrogenated/fluorinated graphene, i.e.
graphane/fluorographene. We found that the packed, spiral structures exhibit
unexpected localized HOMO-LUMO at the edges with increasing energy gap during
rolling. These rolled hydrocarbon structures are stable beyond room temperature
up to at least $T$=1000\,K.


title: l_0 Norm Constraint LMS Algorithm for Sparse System Identification

abstract:
  In order to improve the performance of Least Mean Square (LMS) based system
identification of sparse systems, a new adaptive algorithm is proposed which
utilizes the sparsity property of such systems. A general approximating
approach on $l_0$ norm -- a typical metric of system sparsity, is proposed and
integrated into the cost function of the LMS algorithm. This integration is
equivalent to add a zero attractor in the iterations, by which the convergence
rate of small coefficients, that dominate the sparse system, can be effectively
improved. Moreover, using partial updating method, the computational complexity
is reduced. The simulations demonstrate that the proposed algorithm can
effectively improve the performance of LMS-based identification algorithms on
sparse system.


title: Review of alpha_s determinations

abstract:
  The present knowledge on the strong coupling is briefly summarized. The most
precise determinations of alpha_s, at different energies, are reviewed and
compared at the Z mass scale, using the predicted QCD running. The impressive
agreement achieved between experimental measurements and theoretical
predictions constitutes a beautiful and very significant test of Asymptotic
Freedom, establishing QCD as the fundamental theory of the strong interaction.
The world average value of the strong coupling is found to be alpha_s(M_Z^2)=
0.1186 \pm 0.0007.


title:
Fan-type degree condition restricted to triples of induced subgraphs
  ensuring Hamiltonicity

abstract:
  In 1984, Fan gave a sufficient condition involving maximum degree of every
pair of vertices at distance two for a graph to be Hamiltonian. Motivated by
Fan's result, we say that an induced subgraph $H$ of a graph $G$ is $f$-heavy
if for every pair of vertices $u,v\in V(H)$, $d_{H}(u,v)=2$ implies that
$\max\{d(u),d(v)\}\geq n/2$. For a given graph $R$, $G$ is called $R$-$f$-heavy
if every induced subgraph of $G$ isomorphic to $R$ is $f$-heavy. For a family
$\mathcal{R}$ of graphs, $G$ is $\mathcal{R}$-$f$-\emph{heavy} if $G$ is
$R$-$f$-heavy for every $R\in \mathcal{R}$. In this note we show that every
2-connected graph $G$ has a Hamilton cycle if $G$ is
$\{K_{1,3},P_7,D\}$-$f$-heavy or $\{K_{1,3},P_7,H\}$-$f$-heavy, where $D$ is
the deer and $H$ is the hourglass. Our result is a common generalization of
previous theorems of Broersma et al. and Fan on Hamiltonicity of 2-connected
graphs.


title: Weakly Explosive Percolation in Directed Networks

abstract:
  Percolation, the formation of a macroscopic connected component, is a key
feature in the description of complex networks. The dynamical properties of a
variety of systems can be understood in terms of percolation, including the
robustness of power grids and information networks, the spreading of epidemics
and forest fires, and the stability of gene regulatory networks. Recent studies
have shown that if network edges are added "competitively" in undirected
networks, the onset of percolation is abrupt or "explosive." The unusual
qualitative features of this phase transition have been the subject of much
recent attention. Here we generalize this previously studied network growth
process from undirected networks to directed networks and use finite-size
scaling theory to find several scaling exponents. We find that this process is
also characterized by a very rapid growth in the giant component, but that this
growth is not as sudden as in undirected networks.


title:
On Partition Functions of Hyperbolic Three-Geometry and Associated
  Hilbert Schemes

abstract:
  Highest-weight representations of infinite dimensional Lie algebras and
Hilbert schemes of points are considered, together with the applications of
these concepts to partition functions, which are most useful in physics.
Partition functions (elliptic genera) are conveniently transformed into product
expressions, which may inherit the homology properties of appropriate
(poly)graded Lie algebras. Specifically, the role of (Selberg-type) Ruelle
spectral functions of hyperbolic geometry in the calculation of partition
functions and associated $q$-series are discussed. Examples of these connection
in quantum field theory are considered (in particular, within the AdS/CFT
correspondence), as the AdS$_{3}$ case where one has Ruelle/Selberg spectral
functions, whereas on the CFT side, partition functions and modular forms
arise. These objects are here shown to have a common background, expressible in
terms of Euler-Poincar\'e and Macdonald identities, which, in turn, describe
homological aspects of (finite or infinite) Lie algebra representations.
Finally, some other applications of modular forms and spectral functions
(mainly related with the congruence subgroup of $SL(2, {\mathbb Z})$) to
partition functions, Hilbert schemes of points, and symmetric products are
investigated by means of homological and K-theory methods.


title:
A Miniaturized Prototype of Resonant Banana-Shaped Photoacoustic Cell
  for Gas Sensing

abstract:
  A resonant photoacoustic cell intended for laser-spectroscopy gas sensing is
represented. This cell is a miniature imitation of a macro-scale banana-shaped
cell developed previously. The parameters, which specify the cavity shape, are
chosen so as not only to provide optimal cell operation at a selected acoustic
resonance but also to reduce substantially the cell sizes. A miniaturized
prototype cell (the volume of acoustic cavity of ~ 5 mm^3) adapted to the
narrow diffraction-limited beam of near-infrared laser is produced and examined
experimentally. The noise-associated measurement error and laser-initiated
signals are studied as functions of modulation frequency. The background signal
and the useful response to light absorption by the gas are analyzed in
measurements of absorption for ammonia in nitrogen flow with the help of a
pigtailed DFB laser diode oscillated near a wavelength of 1.53 um. The
performance of prototype operation at the second longitudinal acoustic
resonance (the resonance frequency of ~ 32.9 kHz, Q-factor of ~ 16.3) is
estimated. The noise-limited minimal detectable absorption normalized to
laser-beam power and detection bandwidth is ~ 8.07*10^(-8) cm^(-1) W Hz^(-1/2).
The amplitude of the background signal is equivalent to an absorption
coefficient of ~ 2.5*10^(-5) cm^(-1). Advantages and drawbacks of the cell
prototype are discussed. Despite low absorption-sensing performance, the
produced miniaturized cell prototype shows a good capability of gas-leak
detection.


title: 1D Photonic Crystals with a Sawtooth Refractive Index

abstract:
  Exact analytical results (in terms of Bessel functions) for the bandgaps,
reflectance, and transmittance of one-dimensional photonic crystals with a
sawtooth refractive index profile on the period are derived for the first time.
This extends a group of exactly solvable models of periodic refractive indices.
The asymptotic approximations of the above exact results have been also
obtained.


title: Two new ultra-cool benchmark systems from WISE+2MASS

abstract:
  We have used the 2MASS all-sky survey and the WISE to look for ultracool
dwarfs that are part of multiple systems containing main sequence stars. We
cross-matched L dwarf candidates from the surveys with Hipparcos and Gliese
stars, finding two new systems. The first system, G255-34AB is an L2 dwarf
companion to a K8 star, at a distance of 36 pc. We estimate its bolometric
luminosity as log (L/Lsolar) = -3.78 +/- 0.045 and Teff = 2080 +/- 260 K. The
second system, GJ499ABC, is a triple, with an L5 dwarf as a companion to a
binary with an M4 and K5 star. These two new systems bring the number of L
dwarf plus main sequence star multiple systems to twenty four, which we
discuss. We consider the binary fraction for L dwarfs and main sequence stars,
and further assess possible unresolved multiplicity within the full companion
sample. This analysis shows that some of the L dwarfs in this sample might
actually be unresolved binaries themselves, since their MJ appears to be
brighter than the expected for their spectral types.


title: Feedback cooling, measurement errors, and entropy production

abstract:
  The efficiency of a feedback mechanism depends on the precision of the
measurement outcomes obtained from the controlled system. Accordingly,
measurement errors affect the entropy production in the system. We explore this
issue in the context of active feedback cooling by modeling a typical cold
damping setup as a harmonic oscillator in contact with a heat reservoir and
submitted to a velocity-dependent feedback force that reduces the random
motion. We consider two models that distinguish whether the sensor continuously
measures the position of the resonator or directly its velocity (in practice,
an electric current). Adopting the standpoint of the controlled system, we
identify the `entropy pumping' contribution that describes the entropy
reduction due to the feedback control and that modifies the second law of
thermodynamics. We also assign a relaxation dynamics to the feedback mechanism
and compare the apparent entropy production in the system and the heat bath to
the total entropy production in the super-system that includes the controller.
In this context, entropy pumping reflects the existence of hidden degrees of
freedom and the apparent entropy production satisfies fluctuation theorems
associated to an effective Langevin dynamics.


title: Penalty-regulated dynamics and robust learning procedures in games

abstract:
  Starting from a heuristic learning scheme for N-person games, we derive a new
class of continuous-time learning dynamics consisting of a replicator-like
drift adjusted by a penalty term that renders the boundary of the game's
strategy space repelling. These penalty-regulated dynamics are equivalent to
players keeping an exponentially discounted aggregate of their on-going payoffs
and then using a smooth best response to pick an action based on these
performance scores. Owing to this inherent duality, the proposed dynamics
satisfy a variant of the folk theorem of evolutionary game theory and they
converge to (arbitrarily precise) approximations of Nash equilibria in
potential games. Motivated by applications to traffic engineering, we exploit
this duality further to design a discrete-time, payoff-based learning algorithm
which retains these convergence properties and only requires players to observe
their in-game payoffs: moreover, the algorithm remains robust in the presence
of stochastic perturbations and observation errors, and it does not require any
synchronization between players.


title: VERITAS Observations of the Vicinity of the Cygnus Cocoon

abstract:
  The study of $\gamma$-ray emission from galactic sources such as supernova
remnants (SNR) may provide key insights into their potential role as
accelerators of cosmic rays up to the knee ($\sim 10^{15}$ eV). The VERITAS
Observatory is sensitive to galactic and extragalactic $\gamma$-ray sources in
the 100 GeV to 30 TeV energy range. We report here on VERITAS observations of
the vicinity of the cocoon of freshly accelerated cosmic rays reported by
Fermi, which lies between potential accelerators in the Cygnus OB2 association
and the $\gamma$-Cygni SNR. A particular focus is placed on the source VER
J2019 +407 in $\gamma$-Cygni.


title: Neutrino Oscillations

abstract:
  This review summarizes recent experimental and theoretical progress in
determining neutrino mixing angles and masses through neutrino oscillations. We
describe the basic physics of oscillation phenomena in vacuum and matter, as
well as the status of solar, reactor, atmospheric, and accelerator neutrino
experiments that probe these phenomena. The results from current global
analyses of neutrino parameters are given. Future efforts that may improve the
precision with which these parameters are known or probe new aspects of the
neutrino mixing matrix are described.


title: Casson-type invariants from the Seiberg-Witten equations

abstract:
  This is a survey of our recent work with Tom Mrowka on Seiberg-Witten gauge
theory and index theory for manifolds with periodic ends. We explain how this
work leads to a new invariant, which is related to the classical Rohlin
invariant of homology 3-spheres and to the Furuta-Ohta invariant originating in
Yang-Mills gauge theory. We give some new calculations of our invariant for
4-dimensional mapping tori.


title: Cox rings of rational surfaces and redundant blow-ups

abstract:
  We prove that the redundant blow-up preserves the finite generation of the
Cox ring of a rational surface under a suitable assumption, and we study the
birational structure of Mori dream rational surfaces via redundant blow-ups. It
turns out that the redundant blow-up completely characterizes birational
morphisms of Mori dream rational surfaces with anticanonical Iitaka dimension
$0$. As an application, we construct new Mori dream rational surfaces with
anticanonical Iitaka dimension $0$ and $-\infty$ of arbitrarily large Picard
number.


title:
Continuous third harmonic generation in a terahertz driven modulated
  nanowire

abstract:
  We consider the possibility of observing continuous third-harmonic generation
using a strongly driven, single-band one-dimensional metal. In the absence of
scattering, the quantum efficiency of frequency tripling for such a system can
be as high as 93%. Combining the Floquet quasi-energy spectrum with the Keldysh
Green's function technique, we derive the semiclassical master equation for a
one-dimensional band of strongly and rapidly driven electrons in the presence
of weak scattering by phonons. The power absorbed from the driving field is
continuously dissipated by phonon modes, leading to a quasi-equilibrium in the
electron distribution. We use the Kronig-Penney model with varying effective
mass to establish growth parameters of an InAs/InP nanowire near optimal for
third harmonic generation at terahertz frequency range.


title: A New Proof of Vinogradov's Three Primes Theorem

abstract:
  We give a new proof of Vinogradov's three primes theorem, which asserts that
all sufficiently large odd positive integers can be written as the sum of three
primes. Existing proofs rely on the theory of L-functions, either explicitly or
implicitly. Our proof uses instead a transference principle, the idea of which
was first developed by Green. To make our argument work, we also develop an
additive combinatorial result concerning popular sums, which may be of
independent interest.


title:
Is Learning to Rank Worth It? A Statistical Analysis of Learning to Rank
  Methods

abstract:
  The Learning to Rank (L2R) research field has experienced a fast paced growth
over the last few years, with a wide variety of benchmark datasets and
baselines available for experimentation. We here investigate the main
assumption behind this field, which is that, the use of sophisticated L2R
algorithms and models, produce significant gains over more traditional and
simple information retrieval approaches. Our experimental results surprisingly
indicate that many L2R algorithms, when put up against the best individual
features of each dataset, may not produce statistically significant
differences, even if the absolute gains may seem large. We also find that most
of the reported baselines are statistically tied, with no clear winner.


title: Black Hole Jet Unification in the Fermi Era

abstract:
  AGNs and GRBs produce powerful relativistic jets and their central engines
share the same basic astrophysical ingredients, despite the vastly different
mass scales. Using Fermi and Swift observations, we find evidence that the jets
produced by blazars and GRBs follow the same correlation between the gamma-ray
luminosity and kinetic power. This result suggests that jet production and
energy dissipation mechanisms are remarkably similar over 10 orders of
magnitude in jet power, establishing a physical analogy between AGN and GRBs.
We discuss the implications of these results and the road ahead.


title: On the Sendov conjecture and the critical points of polynomials

abstract:
  In this paper, we obtain new results on the critical points of a polynomial.
We discuss the Sendov conjecture for polynomials of degree nine.


title:
Stabilization of Networked Control Systems with Sparse
  Observer-Controller Networks

abstract:
  In this paper we provide a set of stability conditions for linear
time-invariant networked control systems with arbitrary topology, using a
Lyapunov direct approach. We then use these stability conditions to provide a
novel low-complexity algorithm for the design of a sparse observer-based
control network. We employ distributed observers by employing the output of
other nodes to improve the stability of each observer dynamics. To avoid
unbounded growth of controller and observer gains, we impose bounds on their
norms. The effects of relaxation of these bounds is discussed when trying to
find the complete decentralization conditions.


title:
Incoherent $J/\psi$ electroproduction from the deuteron at JLab energies
  and the elastic $J/\psi$-nucleon scattering amplitude

abstract:
  Calculations are presented for incoherent $J/\psi$ electroproduction from the
deuteron at JLab energies, including the effects of $J/\psi$-nucleon
rescattering in the final state, in order to determine the feasibility of
measuring the $J/\psi$-nucleon scattering length, or the $J/\psi$-nucleon
scattering amplitude at lower relative energies than in previous measurements.
It is shown that for a scattering length of the size predicted by existing
theoretical calculations, it would not be possible to determine the scattering
length. However, it may be possible to determine the scattering amplitude at
significantly lower relative energies than the only previous measurements.


title:
On the conjecture about the nonexistence of rotation symmetric bent
  functions

abstract:
  In this paper, we describe a different approach to the proof of the
nonexistence of homogeneous rotation symmetric bent functions. As a result, we
obtain some new results which support the conjecture made in this journal,
i.e., there are no homogeneous rotation symmetric bent functions of degree >2.
Also we characterize homogeneous degree 2 rotation symmetric bent functions by
using GCD of polynomials.