title: The chemical composition of the Small Magellanic Cloud

abstract:
  The Small Magellanic Cloud is a close, irregular galaxy that has experienced
a complex star formation history due to the strong interactions occurred both
with the Large Magellanic Cloud and the Galaxy. Despite its importance, the
chemical composition of its stellar populations older than 1-2 Gyr is still
poorly investigated. I present the first results of a spectroscopic survey of
200 Small Magellanic Cloud giant stars performed with FLAMES@VLT. The derived
metallicity distribution peaks at [Fe/H] -0.9/-1.0 dex, with a secondary peak
at [Fe/H] -0.6 dex. All these stars show [alpha/Fe] abundance ratios that are
solar or mildly enhanced (+0.1 dex). Also, three metal-poor stars (with [Fe/H]
-2.5 dex and enhanced [alpha/Fe] ratios compatible with those of the Galactic
Halo) have been detected in the outskirts of the SMC: these giants are the most
metal-poor stars discovered so far in the Magellanic Clouds.


title:
Tension moderation and fluctuation spectrum in simulated lipid membranes
  under an applied electric potential

abstract:
  We investigate the effect of an applied electric potential on the mechanics
of a coarse grained POPC bilayer under tension. The size and duration of our
simulations allow for a detailed and accurate study of the fluctuations.
Effects on the fluctuation spectrum, tension, bending rigidity, and bilayer
thickness are investigated in detail. In particular, the least square fitting
technique is used to calculate the fluctuation spectra. The simulations confirm
a recently proposed theory that the effect of an applied electric potential on
the membrane will be moderated by the elastic properties of the membrane. In
agreement with the theory, we find that the larger the initial tension the
larger the effect of the electric potential. Application of the electric
potential increases the amplitude of the long wavelength part of the spectrum
and the bending rigidity is deduced from the short wavelength fluctuations. The
effect of the applied electric potential on the bending rigidity is
non-existent within error bars. However, when the membrane is stretched there
is a point where the bending rigidity is lowered due to a decrease of the
thickness of the membrane. All these effects should prove important for
mechanosensitive channels and biomembrane mechanics in general.


title: Non-commutative q-Painleve VI equation

abstract:
  By applying suitable centrality condition to non-commutative non-isospectral
lattice modified Gel'fand-Dikii type systems we obtain the corresponding
non-autonomous equations. Then we derive non-commutative q-discrete Painleve VI
equation with full range of parameters as the (2,2) similarity reduction of the
non-commutative, non-isospectral and non-autonomous lattice modified
Korteweg-de Vries equation. We also comment on the fact that in making the
analogous reduction starting from Schwarzian Korteweg-de Vries equation no such
"non-isospectral generalization" is needed.


title:
Comparing C and Zilber exponential fields, zero sets of exponential
  polynomials

abstract:
  We continue the research programme of comparing the complex exponential field
with Zilber exponential. For the latter we prove, using diophantine geometry,
various properties about zero sets of exponential functions, proved for C using
analytic function theory, e g the Identity Theorem.


title:
Impact of nuclear irradiation on helium bubble nucleation at interfaces
  in liquid metals coupled to permeation through stainless steels

abstract:
  The impact of nucleating gas bubbles in the form of a dispersed gas phase on
hydrogen isotope permeation at interfaces between liquid metals, like LLE, and
structural materials, like stainless steel, has been studied. Liquid metal to
structural material interfaces involving surfaces, may lower the nucleation
barrier promoting bubble nucleation at active sites. Hence, hydrogen isotope
absorption into gas bubbles modelling and control at interfaces may have a
capital importance regarding design, operation and safety.
  He bubbles as a permeation barrier principle is analysed showing a
significant impact on hydrogen isotope permeation, which may have a significant
effect on liquid metal systems, e.g., tritium extraction systems. Liquid metals
like LLE under nuclear irradiation in, e.g., breeding blankets of a nuclear
fusion reactor would generate tritium which is to be extracted and recirculated
as fuel. At the same time that tritium is bred, helium is also generated and
may precipitate in the form of nano bubbles.
  Phenomena modelling is exposed and implemented in OpenFoam(r) CFD tool for 0D
to 3D simulations. Results for a 1D case show the impact of a He dispersed
phase of nano bubbles on hydrogen isotopes permeation at an interface. In
addition, a simple permeator simulation, consisting in a straight 3D pipe is
exposed showing the effect of a He dispersed gas phase on hydrogen isotope
permeation through different stainless steels. Results show the permeation
reduction as a function of the interface area covered by He bubbles.
  Our work highlights the effect of gas bubble nucleation at interfaces and the
importance of controlling these phenomena in nuclear technology applications.


title: Microscopic origin of the relativistic splitting of surface states

abstract:
  Spin-orbit splitting of surface states is analyzed within and beyond the
Rashba model using as examples the (111) surfaces of noble metals, Ag2Bi
surface alloy, and topological insulator Bi2Se3. The ab initio analysis of
relativistic velocity proves the Rashba model to be fundamentally inapplicable
to real crystals. The splitting is found to be primarily due to a spin-orbit
induced in-plane modification of the wave function, namely to its effect on the
nonrelativistic Hamiltonian. The usual Rashba splitting -- given by charge
distribution asymmetry -- is an order of magnitude smaller.


title: Domain Mapping for Volumetric Parameterization using Harmonic Functions

abstract:
  Volumetric parameterization problem refers to parameterization of both the
interior and boundary of a 3D model. It is a much harder problem compared to
surface parameterization where a parametric representation is worked out only
for the boundary of a 3D model (which is a surface). Volumetric
parameterization is typically helpful in solving complicated geometric problems
pertaining to shape matching, morphing, path planning of robots, and
isogeometric analysis etc. A novel method is proposed in which a volume
parameterization is developed by mapping a general non-convex (genus-0) domain
to its topologically equivalent convex domain. In order to achieve a continuous
and bijective mapping of a domain, first we use the harmonic function to
establish a potential field over the domain. The gradients of the potential
values are used to track the streamlines which originate from the boundary and
converge to a single point, referred to as the shape center. Each streamline
approaches the shape center at a unique polar angle and an azimuthal angle .
Once all the three parameters (potential value, polar angle, azimuthal angle)
necessary to represent any point in the given domain are available, the domain
is said to be parameterized. Using our method, given a 3D non-convex domain, we
can parameterize the surface as well as the interior of the domain. The
proposed method is implemented and the algorithm is tested on many standard
cases to demonstrate the effectiveness.


title: Magnetic structure of solar active region NOAA 11158

abstract:
  Magnetic fields in the solar corona are responsible for a wide range of
phenomena. However, any direct measurements of the coronal magnetic fields are
very difficult due to lack of suitable spectral lines, weak magnetic fields,
and high temperatures. Therefore, one extrapolates photospheric field
measurements into the corona. Owing to low coronal plasma $\beta$, we can apply
a force-free model in lowest order to study the slow evolution of active region
(AR) magnetic fields. On applying these models to AR 11158 and compared with
coronal plasma tracers, we found that (1) the approximation of potential field
to coronal structures over large length scales is a reasonable one, 2) linear
force-free (LFF) assumption to AR coronal fields may not be applicable model as
it assumes uniform twist over the entire AR, and 3) for modeling fields at
sheared, stressed locations where energy release in the form of flares are
usually observed, non-linear force free fields (NLFFF) seem to provide a good
approximation. The maximum available free-energy profile shows step-wise
decrease that is sufficient to power an M-class flare as observed.


title: Binary Satellite Galaxies

abstract:
  Suggestions have appeared in the literature that the following five pairs of
Milky Way and Andromeda satellite galaxies are gravitationally bound: Draco and
Ursa Minor, Leo IV and V, Andromeda I and III, NGC 147 and 185, and the
Magellanic clouds. Under the assumption that a given pair is gravitationally
bound, the Virial theorem provides an estimate of its total mass and so its
instantaneous tidal radius. For all of these pairs except for the Magellanic
clouds the resulting total mass is 2 to 4 orders of magnitude higher than that
within the half light radius. Furthermore in the case of each pair except for
Leo IV and Leo V, the estimated tidal radius is inferior to the separation
between the two satellites. Therefore all or almost all of these systems are
not gravitationally bound. We note several possible explanations for the
proximities and similar radial velocities of the satellites in each pair, for
example they may have condensed from the same infalling structure or they may
be bound by a nongravitational interaction between dark matter and an extremely
light particle.


title: Supercurrent multiplet correlators at weak and strong coupling

abstract:
  Correlators of gauge invariant operators provide useful information on the
dynamics, phases and spectra of a quantum field theory. In this paper, we
consider N=1 supersymmetric theories and focus our attention on the
supercurrent multiplet. We give a complete characterization of two-point
functions of operators belonging to such multiplet, like the energy-momentum
tensor and the supercurrent, and study the relations between them. We discuss
instances of weakly coupled and strongly coupled theories, in which different
symmetries, like conformal invariance and supersymmetry, may be conserved
and/or spontaneously or explicitly broken. For theories at strong coupling, we
exploit AdS/CFT techniques. We provide a holographic description of different
properties of a strongly coupled theory, including a realization of the
Goldstino mode in a simple illustrative model.


title: Space-Filling vs. Luzin's Condition (N)

abstract:
  Let us assume that we are given two metric spaces, where the Hausdorff
dimension of the first space is strictly smaller than the one of the second
space. Suppose further that the first space has sigma-finite measure with
respect to the Hausdorff measure of the corresponding dimension. We show for
quite general metric spaces that for any measurable surjection from the first
onto the second space, there is a set of measure zero that is mapped to a set
of positive measure (both measures are the Hausdorff measures corresponding to
the Hausdorff dimension of the first space). We also study more general
situations where the measures on the two metric spaces are not necessarily the
same and not necessarily Hausdorff measures.


title: A minimization approach to hyperbolic Cauchy problems

abstract:
  Developing an original idea of De Giorgi, we introduce a new and purely
variational approach to the Cauchy Problem for a wide class of defocusing
hyperbolic equations. The main novel feature is that the solutions are obtained
as limits of functions that minimize suitable functionals in space-time (where
the initial data of the Cauchy Problem serve as prescribed boundary
conditions). This opens up the way to new connections between the hyperbolic
world and that of the Calculus of Variations. Also dissipative equations can be
treated. Finally, we discuss several examples of equations that fit in this
framework, including nonlocal equations, in particular equations with the
fractional Laplacian.


title: Unsplittable coverings in the plane

abstract:
  A system of sets forms an {\em $m$-fold covering} of a set $X$ if every point
of $X$ belongs to at least $m$ of its members. A $1$-fold covering is called a
{\em covering}. The problem of splitting multiple coverings into several
coverings was motivated by classical density estimates for {\em sphere
packings} as well as by the {\em planar sensor cover problem}. It has been the
prevailing conjecture for 35 years (settled in many special cases) that for
every plane convex body $C$, there exists a constant $m=m(C)$ such that every
$m$-fold covering of the plane with translates of $C$ splits into $2$
coverings. In the present paper, it is proved that this conjecture is false for
the unit disk. The proof can be generalized to construct, for every $m$, an
unsplittable $m$-fold covering of the plane with translates of any open convex
body $C$ which has a smooth boundary with everywhere {\em positive curvature}.
Somewhat surprisingly, {\em unbounded} open convex sets $C$ do not misbehave,
they satisfy the conjecture: every $3$-fold covering of any region of the plane
by translates of such a set $C$ splits into two coverings. To establish this
result, we prove a general coloring theorem for hypergraphs of a special type:
{\em shift-chains}. We also show that there is a constant $c>0$ such that, for
any positive integer $m$, every $m$-fold covering of a region with unit disks
splits into two coverings, provided that every point is covered by {\em at
most} $c2^{m/2}$ sets.


title: Managing Heterogeneous WSNs in Smart Cities: Challenges and Requirements

abstract:
  The dramatic advances in wireless communications and electronics have enabled
the development of Wireless Sensor Networks (WSNs). WSNs consist of many
affordable and portable sensor nodes for collecting data from the environment.
In this article, we address management requirements of WSNs through presenting
some key management scenarios in the Smart Cities context, such as intelligent
transportation systems, smart grids and smart buildings. The limited resources
and heterogeneous characteristics of WSNs pose new challenges in network
management, which include the presence of various faults, the difficulty in
replacing and repairing a large number of sensor nodes, the existence of an
uncertain topology, and the resource allocation. To cope with these challenges,
we first discuss advantages and disadvantages of centralized and distributed
management approaches and then discuss the benefit of the multilevel management
schema. Next, we present in detail the specific features for a WSN management
system such as lightweight, self-detection, self-configuration, sharing
infrastructure, service monitoring, plug and play, context awareness and
interoperability. Finally, we present the required mechanisms for some basic
management functions.


title: Thermal String Excitations in Artificial Spin-Ice Dipolar Arrays

abstract:
  We report on a theoretical investigation of artificial spin-ice dipolar
arrays, using a nanoisland geometry adopted from recent experiments [A. Farhan
\textit{et al.}, Nature Phys.\ \textbf{9} (2013) 375]. The number of thermal
magnetic string excitations in the square lattice is drastically increased by a
vertical displacement of rows and columns. We find large increments especially
for low temperatures and for string excitations with quasi-monopoles of charges
$\pm 4$. By kinetic Monte Carlo simulations we address the thermal stability of
such excitations, thereby providing time scales for their experimental
observation.


title: Positivstellens\"atze for Quantum Multigraphs

abstract:
  Studying inequalities between subgraph- or homomorphism-densities is an
important topic in graph theory. Sums of squares techniques have proven useful
in dealing with such questions. Using an approach from real algebraic geometry,
we strengthen a Positivstellensatz for simple quantum graphs by Lov\'asz and
Szegedy, and we prove several new Positivstellens\"atze for nonnegativity of
quantum multigraphs. We provide new examples and counterexamples.


title:
Probabilistic Forecasts of Solar Irradiance by Stochastic Differential
  Equations

abstract:
  Probabilistic forecasts of renewable energy production provide users with
valuable information about the uncertainty associated with the expected
generation. Current state-of-the-art forecasts for solar irradiance have
focused on producing reliable \emph{point} forecasts. The additional
information included in probabilistic forecasts may be paramount for decision
makers to efficiently make use of this uncertain and variable generation. In
this paper, a stochastic differential equation (SDE) framework for modeling the
uncertainty associated with the solar irradiance point forecast is proposed.
This modeling approach allows for characterizing both the interdependence
structure of prediction errors of short-term solar irradiance and their
predictive distribution. A series of different SDE models are fitted to a
training set and subsequently evaluated on a one-year test set. The final model
proposed is defined on a bounded and time-varying state space with zero
probability almost surely of events outside this space.


title: Investigation of light and heavy tetraquark candidates using lattice QCD

abstract:
  We review the status of an ongoing long-term lattice investigation of the
spectrum and structure of tetraquark candidates. We focus on the light scalar
meson $a_0(980)$. First steps regarding the study of a possibly existing $c c
\bar{c} \bar{c}$ tetraquark are also outlined.


title: Cluster algebras in scattering amplitudes with special 2D kinematics

abstract:
  We study the cluster algebra of the kinematic configuration space
$Conf_n(\mathbb{P}^3)$ of a n-particle scattering amplitude restricted to the
special 2D kinematics. We found that the n-points two loop MHV remainder
function found in special 2D kinematics depend on a selection of
\XX-coordinates that are part of a special structure of the cluster algebra
related to snake triangulations of polygons. This structure forms a necklace of
hypercubes beads in the corresponding Stasheff polytope. Furthermore in $n =
12$, the cluster algebra and the selection of \XX-coordinates in special 2D
kinematics replicates the cluster algebra and the selection of \XX-coordinates
of $n=6$ two loop MHV amplitude in 4D kinematics.


title: Pollux: a stable weak dipolar magnetic field but no planet ?

abstract:
  Pollux is considered as an archetype of a giant star hosting a planet: its
radial velocity (RV) presents sinusoidal variations with a period of about 590
d, which have been stable for more than 25 years. Using ESPaDOnS and Narval we
have detected a weak (sub-gauss) magnetic field at the surface of Pollux and
followed up its variations with Narval during 4.25 years, i.e. more than for
two periods of the RV variations. The longitudinal magnetic field is found to
vary with a sinusoidal behaviour with a period close to that of the RV
variations and with a small shift in phase. We then performed a Zeeman Doppler
imaging (ZDI) investigation from the Stokes V and Stokes I least-squares
deconvolution (LSD) profiles. A rotational period is determined, which is
consistent with the period of variations of the RV. The magnetic topology is
found to be mainly poloidal and this component almost purely dipolar. The mean
strength of the surface magnetic field is about 0.7 G. As an alternative to the
scenario in which Pollux hosts a close-in exoplanet, we suggest that the
magnetic dipole of Pollux can be associated with two temperature and
macroturbulent velocity spots which could be sufficient to produce the RV
variations. We finally investigate the scenarii of the origin of the magnetic
field which could explain the observed properties of Pollux.


title:
Accuracy of energy measurement and reversible operation of a
  microcanonical Szilard engine

abstract:
  In a recent paper [Vaikuntanathan and Jarzynski, Phys. Rev. E {\bf 83},
061120 (2011), arXiv:1105.1744] a model was introduced whereby work could be
extracted from a thermal bath by measuring the energy of a particle that was
thermalized by the bath and manipulating the potential of the particle in the
appropriate way, depending on the measurement outcome. If the extracted work is
$W_1$ and the work $W_{\text{er}}$ needed to be dissipated in order to erase
the measured information in accordance with Landauer's principle, it was shown
that $W_1\leq W_{\text{er}}$ in accordance with the second law of
thermodynamics. Here we extend this work in two directions: First, we discuss
how accurately the energy should be measured. By increasing the accuracy one
can extract more work, but at the same time one obtains more information that
has to be deleted. We discuss what are the appropriate ways of optimizing the
balance between the two and find optimal solutions. Second, whenever $W_1$ is
strictly less than $W_{\text{er}}$ it means that an irreversible step has been
performed. We identify the irreversible step and propose a protocol that will
achieve the same transition in a reversible way, increasing $W_1$ so that $W_1
= W_{\text{er}}$.


title: Counting Photons in Static Electric and Magnetic Fields

abstract:
  We describe the electromagnetic field by the massless limit of a massive
vector field in the presence of a Coulomb gauge fixing term. The gauge fixing
term ensures that, in the massless limit, the longitudinal mode is removed from
the spectrum and only the two transverse modes survive. The system, coupled to
a classical conserved current, is quantized in the canonical formalism. The
classical field configurations due to time-independent electric charges and
currents are represented by coherent states of longitudinal and transverse
photons, respectively. The occupation number in these states is finite. In
particular, the number of longitudinal photons bound by an electric charge q is
given by N=q^2/(16\pi\hbar).


title:
Electronic properties of Co$_{2}$FeSi investigated by x-ray magnetic
  linear dichroism

abstract:
  We present experimental XMLD spectra measured on epitaxial (001)-oriented
thin Co$_{2}$FeSi films, which are rich in features and depend sensitively on
the degree of atomic order and interdiffusion from capping layers. Al- and
Cr-capped films with different degrees of atomic order were prepared by DC
magnetron sputtering by varying the deposition temperatures. The local
structural properties of the film samples were additionally investigated by
nuclear magnetic resonance (NMR) measurements. The XMLD spectra of the
different samples show clear and uniform trends at the $L_{3,2}$ edges. The
Al-capped samples show similar behavior as previous measured XMLD spectra of
Co$_2$FeSi$_{0.6}$Al$_{0.4}$. Thus, we assume that during deposition Al atoms
are being implanted into the subsurface of Co$_{2}$FeSi. Such an interdiffusion
is not observed for the corresponding Cr-capped films, which makes Cr the
material of choice for capping Co$_{2}$FeSi films. We report stronger XMLD
intensities at the $L_{3,2}$ Co and Fe egdes for films with a higher saturation
magnetization. Additionally, we compare the spectra with \textit{ab initio}
predictions and obtain a reasonably good agreement. Furthermore, we were able
to detect an XMCD signal at the Si $L$-edge, indicating the presence of a
magnetic moment at the Si atoms.


title:
Comments on arXiv:1310.5067: "A response to `A self-consistent public
  catalogue of voids and superclusters in the SDSS Data Release 7 galaxy
  surveys' "

abstract:
  Sutter et al. have responded to the criticisms we made of their cosmic void
catalogue in our recent paper presenting an alternative catalogue (Nadathur &
Hotchkiss 2013). Unfortunately, their response contains several statements
which are incorrect, as we point out in this note.


title: Scalable interconnections for remote exciton systems

abstract:
  Excitons, quasi-particles consisting of electron-hole pairs bound by the
Coulomb interaction, are a potential medium for processing of photonic
information in the solid-state. Information processing via excitons requires
efficient techniques for the transport and manipulation of these uncharged
particles. We introduce here a novel concept for the interconnection of
multiple remote exciton systems based on the long-range transport of dipolar
excitons by a network of configurable interconnects driven by acoustic wave
beams. By combining this network with electrostatic gates, we demonstrate an
integrated exciton multiplexer capable of interconnecting, gating and routing
exciton systems separated by millimeter distances. The multiplexer provides a
scalable platform for the manipulation of exciton fluids with potential
applications in information processing.


title:
Study of two-proton radioactivity within the relativstic mean-field plus
  bcs approach

abstract:
  Encouraged by the success of RMF+BCS approach for the description of the
ground state properties of the chains of isotopes of proton magic nuclei with
proton number \textit{Z}=8, 20, 28, 50 and 82 as well as those of proton
sub-magic nuclei with \textit{Z}=40, we have further employed it, in an
analogous manner, for a detailed calculations of the ground state properties of
the neutron magic isotones with neutron number \textit{N} = 8, 20, 28, 50, 82
and 126 as well as those of neutron sub-magic isotones with \textit{N} = 40
using the TMA force parameterizations in order to explore low lying resonance
and other exotic phenomenon near drip-lines. The results of these calculations
for wave-function, single particle pairing gaps etc. are presented here to
demonstrate the general validity of our RMF+BCS approach. It is found that, in
some of the proton-rich nuclei in the vicinity of the proton drip-line, the
main contribution to the pairing correlations is provided by the low-lying
resonant states, in addition to the contributions coming from the states close
to the Fermi surface, which results extended proton drip-line for isotonic
chain.


title:
Motivic Milnor fibre for nondegenerate function germs on toric
  singularities

abstract:
  We study function germs on toric varieties which are nondegenerate for their
Newton diagram. We express their motivic Milnor fibre in terms of their Newton
diagram. We extend a formula for the motivic nearby fibre to the case of a
toroidal degeneration. We illustrate this by some examples.


title: Modified arctan-gravity model mimicking a cosmological constant

abstract:
  A novel theory of $F(R)$ gravity with the Lagrangian density ${\cal
L}=[R-(b/\beta)\arctan\left(\beta R\right)]/(2\kappa^2)$ is analyzed. Constant
curvature solutions of the model are found, and the potential of the scalar
field and the mass of a scalar degree of freedom in Einstein's frame are
derived. The cosmological parameters of the model are calculated, which are in
agreement with the PLANCK data. Critical points for the de Sitter phase and the
matter dominated epoch of autonomous equations are obtained and studied.


title: Stability analysis of inflation with an SU(2) gauge field

abstract:
  We study anisotropic cosmologies of a scalar field interacting with an SU(2)
gauge field via a gauge-kinetic coupling. We analyze Bianchi class A models,
which include Bianchi type I, II, VI0, VII0, VIII and IX. The linear stability
of isotropic inflationary solution with background magnetic field is shown,
which generalizes the known results for U(1) gauge fields. We also study
anisotropic inflationary solutions, all of which turn out to be unstable. Then
nonlinear stability for the isotropic inflationary solution is examined by
numerically investigating the dependence of the late-time behaviour on the
initial conditions. We present a number of novel features that may well affect
physical predictions and viability of the models. First, in the absence of
spatial curvature, strong initial anisotropy leads to a rapid oscillation of
gauge field, thwarting convergence to the inflationary attractor. Secondly, the
inclusion of spatial curvature destabilizes the oscillatory attractor and the
global stability of the isotropic inflation with gauge field is restored.
Finally, based on the numerical evidence combined with the knowledge of the
eigenvalues for various inflationary solutions, we give a generic lower-bound
for the duration of transient anisotropic inflation, which is inversely
proportional to the slow-roll parameter.


title:
Spallation caused by the diffusion and agglomeration of vacancies in
  ductile metals

abstract:
  In this work, the spallation processes in the ductile metals are
systematically discussed in theory. By employing the phase transition theory
and non-equilibrium transport theory, the spallation processes of ductile
metals under dynamic loading may be mainly determined by the diffusion and
agglomeration of generated vacancies. And through the theoretical analysis on
the dynamic spallation processes, it is found that (1)the spallation critical
behaviors exist; (2)both the damage evolution rate and the void growth velocity
in the spallation planes are monitored by the grain sizes, the tensile strain
rate and the temperature of the metal after shocking, i.e., a larger grain size
and tensile strain rate and higher temperature will cause a larger damage
evolution rate and void growth velocity; (3)there exists the characteristic
size for the voids and the characteristic stress on the void boundary, which
are dependent of vacancy excitation energy and the average volume occupied by
the metal atom; (4)both the stress and temperature close to the void are high
and may cause the melting, and they decrease quickly as the distance away from
the void increases; (5)the plastic zone surrounding the formed voids is
obtained and found to be governed by the characteristic stress; (6)the void
growth in the spallation processes may arise from the agglomeration of
vacancies rather than the emitting of dislocations. Most of the theoretical
results are novel and obtained first. And they are found to be in agreement
with the experimental results and the simulated results.


title: Discontinuities of energy derivatives in spin-density functional theory

abstract:
  Standard approximations for the exchange-correlation functional are known to
deviate from linear dependence of the energy on the electron and spin numbers
(in -space). Violation of this flat-plane condition underlies the failure of
all known approximate functionals to describe band gaps in strongly correlated
systems. Then crucial for further development of functionals is recognition of
the behavior of the energy as a function of, and its derivatives (derivatives
discontinuity pattern at 0K limit). In this Letter, the energy derivatives are
analyzed thoroughly. It is shown that apart from the well-known type of
discontinuity pattern, three other patterns are possible in the vicinity of the
singlet state point. The zero temperature limits of energy derivatives at this
point are derived, found different for various directions. Existence of all
discontinuity patterns is illustrated on the example of diatomic molecules set.


title:
Fast implementation for semidefinite programs with positive matrix
  completion

abstract:
  Solving semidefinite programs (SDP) in a short time is the key to managing
various mathematical optimization problems. The matrix-completion primal-dual
interior-point method (MC-PDIPM) extracts a sparse structure of input SDP by
factorizing the variable matrices. In this paper, we propose a new
factorization based on the inverse of the variable matrix to enhance the
performance of MC-PDIPM. We also use multithreaded parallel computing to deal
with the major bottlenecks in MC-PDIPM. Numerical results show that the new
factorization and multithreaded computing reduce the computation time for SDPs
that have structural sparsity.


title: Bifurcation analysis in a frustrated nematic cell

abstract:
  Using Landau-de Gennes theory to describe nematic order, we study a
frustrated cell consisting of nematic liquid crystal confined between two
parallel plates. We prove the uniqueness of equilibrium states for a small cell
width. Letting the cell width grow, we study the behaviour of this unique
solution. Restricting ourselves to a certain interval of temperature, we prove
that this solution becomes unstable at a critical value of the cell width.
Moreover, we show that this loss of stability comes with the appearance of two
new solutions: there is a symmetric pitchfork bifurcation. This picture agrees
with numerical simulations performed by P. Palffy-Muhorray, E.C. Gartland and
J.R. Kelly. Some of the methods that we use in the present paper apply to other
situations, and we present the proofs in a general setting. More precisely, the
paper contains the proof of a general uniqueness result for a class of
perturbed quasilinear elliptic systems, and general considerations about
symmetric solutions and their stability, in the spirit of Palais' Principle of
Symmetric Criticality.


title:
Comparing rankings by means of competitivity graphs: structural
  properties and computation

abstract:
  In this paper we introduce a new technique to analyze families of rankings
focused on the study of structural properties of a new type of graphs. Given a
finite number of elements and a family of rankings of those elements, we say
that two elements compete when they exchange their relative positions in at
least two rankings. This allows us to define an undirected graph by connecting
elements that compete. We call this graph a competitivity graph. We study the
relationship of competitivity graphs with other well-known families of graphs,
such as permutation graphs, comparability graphs and chordal graphs. In
addition to this, we also introduce certain important sets of nodes in a
competitivity graph. For example, nodes that compete among them form a
competitivity set and nodes connected by chains of competitors form a set of
eventual competitors. We analyze hese sets and we show a method to obtain sets
of eventual competitors directly from a family of rankings.


title:
Laboratory Transferability of Optimally Shaped Laser Pulses for Quantum
  Control

abstract:
  Optimal control experiments can readily identify effective shaped laser
pulses, or "photonic reagents", that achieve a wide variety of objectives. For
many practical applications, an important criterion is that a particular
photonic reagent prescription still produce a good, if not optimal, target
objective yield when transferred to a different system or laboratory, {even if
the same shaped pulse profile cannot be reproduced exactly. As a specific
example, we assess the potential for transferring optimal photonic reagents for
the objective of optimizing a ratio of photoproduct ions from a family of
halomethanes through three related experiments.} First, applying the same set
of photonic reagents with systematically varying second- and third-order chirp
on both laser systems generated similar shapes of the associated control
landscape (i.e., relation between the objective yield and the variables
describing the photonic reagents). Second, optimal photonic reagents obtained
from the first laser system were found to still produce near optimal yields on
the second laser system. Third, transferring a collection of photonic reagents
optimized on the first laser system to the second laser system reproduced
systematic trends in photoproduct yields upon interaction with the homologous
chemical family. Despite inherent differences between the two systems,
successful and robust transfer of photonic reagents is demonstrated in the
above three circumstances. The ability to transfer photonic reagents from one
laser system to another is analogous to well-established utilitarian operating
procedures with traditional chemical reagents. The practical implications of
the present results for experimental quantum control are discussed.


title: New Precision Measurement of Hyperfine Splitting of Positronium

abstract:
  The ground state hyperfine splitting of positronium $\Delta_{\mathrm{HFS}}$
is sensitive to high order corrections of quantum electrodynamics (QED) in
bound state. The theoretical prediction and the averaged experimental value for
$\Delta_{\mathrm{HFS}}$ has a discrepancy of 15 ppm, which is equivalent to 3.9
standard deviations (s.d.). A new precision measurement which reduces the
systematic uncertainty from the positronium thermalization effect was
performed, in which the non-thermalization effect was measured to be as large
as $10 \pm 2\,{\mathrm{ppm}}$ in a timing window we used. When this effect is
taken into account, our new result becomes $\Delta_{\mathrm{HFS}} = 203.394\,2
\pm 0.001\,6 ({\mathrm{stat., 8.0\,ppm}}) \pm 0.001\,3 ({\mathrm{sys.,
6.4\,ppm}})$\,GHz, which favors the QED prediction within 1.2 s.d. and
disfavors the previous experimental average by 2.6 s.d.


title: New Results on the Number Theoretic Hilbert Transform

abstract:
  This paper presents new results in the theory of number theoretic Hilbert
(NHT) transforms. New polymorphic solutions have been found for the 14-point
and 16-point transforms. Several transform pairs are computed and solutions
found for which the sequence and the transform have the same shape. The
multiplicity of solutions for the same moduli increases their applicability to
cryptography.


title:
Electric Vehicle Charging Station Placement: Formulation, Complexity,
  and Solutions

abstract:
  To enhance environmental sustainability, many countries will electrify their
transportation systems in their future smart city plans. So the number of
electric vehicles (EVs) running in a city will grow significantly. There are
many ways to re-charge EVs' batteries and charging stations will be considered
as the main source of energy. The locations of charging stations are critical;
they should not only be pervasive enough such that an EV anywhere can easily
access a charging station within its driving range, but also widely spread so
that EVs can cruise around the whole city upon being re-charged. Based on these
new perspectives, we formulate the Electric Vehicle Charging Station Placement
Problem (EVCSPP) in this paper. We prove that the problem is non-deterministic
polynomial-time hard. We also propose four solution methods to tackle EVCSPP
and evaluate their performance on various artificial and practical cases. As
verified by the simulation results, the methods have their own characteristics
and they are suitable for different situations depending on the requirements
for solution quality, algorithmic efficiency, problem size, nature of the
algorithm, and existence of system prerequisite.


title: Optimal Charging of an Electric Vehicle using a Markov Decision Process

abstract:
  The combination of electric vehicles (EVs) and renewable energy is taking
shape as a potential driver for a future free of fossil fuels. However, the
efficient management of the EV fleet is not exempt from challenges. It calls
for the involvement of all actors directly or indirectly related to the energy
and transportation sectors, ranging from governments, automakers and
transmission system operators, to the ultimate beneficiary of the change: the
end-user. An EV is primarily to be used to satisfy driving needs, and
accordingly charging policies must be designed primarily for this purpose. The
charging models presented in the technical literature, however, overlook the
stochastic nature of driving patterns. Here we introduce an efficient
stochastic dynamic programming model to optimally charge an EV while accounting
for the uncertainty inherent to its use. With this aim in mind, driving
patterns are described by an inhomogeneous Markov model that is fitted using
data collected from the utilization of an EV. We show that the randomness
intrinsic to driving needs has a substantial impact on the charging strategy to
be implemented.


title: The renaissance of radio detection of cosmic rays

abstract:
  Nearly 50 years ago, the first radio signals from cosmic ray air showers were
detected. After many successful studies, however, research ceased not even 10
years later. Only a decade ago, the field was revived with the application of
powerful digital signal processing techniques. Since then, the detection
technique has matured, and we are now in a phase of transition from small-scale
experiments accessing energies below 1018 eV to experiments with a reach for
energies beyond 1019 eV. We have demonstrated that air shower radio signals
carry information on both the energy and the mass of the primary particle, and
current experiments are in the process of quantifying the precision with which
this information can be accessed. All of this rests on a solid understanding of
the radio emission processes which can be interpreted as a coherent
superposition of geomagnetic emission, Askaryan charge-excess radiation, and
Cherenkov-like coherence effects arising in the density gradient of the
atmosphere. In this article, I highlight the "state of the art" of radio
detection of cosmic rays and briefly discuss its perspectives for the next few
years.


title:
Non-asymptotic performance analysis of importance sampling schemes for
  small noise diffusions

abstract:
  In this note we develop a prelimit analysis of performance measures for
importance sampling schemes related to small noise diffusion processes. In
importance sampling the performance of any change of measure is characterized
by its second moment. For a given change of measure, we characterize the second
moment of the corresponding estimator as the solution to a PDE, which we
analyze via a full asymptotic expansion with respect to the size of the noise
and obtain a precise statement on its accuracy. The main correction term to the
decay rate of the second moment solves a transport equation that can be solved
explicitly. The asymptotic expansion that we obtain identifies the source of
possible poor performance of nevertheless asymptotically optimal importance
sampling schemes and allows for more accurate comparison among competing
importance sampling schemes.


title: Scaling limit for a family of random paths with radial behavior

abstract:
  We introduce a system of coalescing random paths with radialbehavior in a
subsetof the plane. We call it theDiscrete Radial Poissonian Web. We show that
underdiffusive scaling this family converges in distribution toa mapping of a
restrictionof the Brownian Web.


title:
Are There Really Cooper Pairs And Persistent Currents in Aromatic
  Molecules

abstract:
  Over twenty years ago one of us suggested the title was affirmative. In 2012
Cooper pairs were identified in several, but not all aromatic compounds tested,
benzene being one. This manuscript discusses the formation of three
time-reversed pairs of states forming pseudobosons (high energy Cooper pairs)
in benzene at room temperature. The large stabilization in energy that results
is the additive effect of energy gaps of an s wave state and a charge density
wave permitting the pseudobosons to exist at room temperature. The overall
result of these interactions is three pseudobosons occupying the lowest boson
state and the positions of the carbon nuclei are optimum by forming a perfect
hexagon. The possibility of a persistent current exists; detection might not be
easy.


title:
Eikonal Slant Helices and Eikonal Darboux Helices In 3-Dimensional
  Riemannian Manifolds

abstract:
  In this study, we give definitions and characterizations of eikonal slant
helix curves, eikonal Darboux helices and non-normed eikonal Darboux helices in
three dimensional Riemannian manifold 3 M . We show that every eikonal slant
helix is also an eikonal Darboux helix. Furthermore, we obtain that if the
curve a is a non-normed eikonal Darboux helix, then a is an eikonal slant helix
if and only if k 2 +t 2 = constant, where k and t are curvature and torsion of
a, respectively.


title: Causality Constraints on Hadron Production In High Energy Collisions

abstract:
  For hadron production in high energy collisions, causality requirements lead
to the counterpart of the cosmological horizon problem: the production occurs
in a number of causally disconnected regions of finite space-time size. As a
result, globally conserved quantum numbers (charge, strangeness, baryon number)
must be conserved locally in spatially restricted correlation clusters. This
provides a theoretical basis for the observed suppression of strangeness
production in elementary interactions (pp, e^+e^-). In contrast, the space-time
superposition of many collisions in heavy ion interactions largely removes
these causality constraints, resulting in an ideal hadronic resonance gas in
full equilibrium.


title:
Weak convergence of marked point processes generated by crossings of
  multivariate jump processes. Applications to neural network modeling

abstract:
  We consider the multivariate point process determined by the crossing times
of the components of a multivariate jump process through a multivariate
boundary, assuming to reset each component to an initial value after its
boundary crossing. We prove that this point process converges weakly to the
point process determined by the crossing times of the limit process. This holds
for both diffusion and deterministic limit processes. The almost sure
convergence of the first passage times under the almost sure convergence of the
processes is also proved. The particular case of a multivariate Stein process
converging to a multivariate Ornstein-Uhlenbeck process is discussed as a
guideline for applying diffusion limits for jump processes. We apply our
theoretical findings to neural network modeling. The proposed model gives a
mathematical foundation to the generalization of the class of Leaky
Integrate-and-Fire models for single neural dynamics to the case of a firing
network of neurons. This will help future study of dependent spike trains.


title: Generalized activity equations for spiking neural network dynamics

abstract:
  Much progress has been made in uncovering the computational capabilities of
spiking neural networks. However, spiking neurons will always be more expensive
to simulate compared to rate neurons because of the inherent disparity in time
scales - the spike duration time is much shorter than the inter-spike time,
which is much shorter than any learning time scale. In numerical analysis, this
is a classic stiff problem. Spiking neurons are also much more difficult to
study analytically. One possible approach to making spiking networks more
tractable is to augment mean field activity models with some information about
spiking correlations. For example, such a generalized activity model could
carry information about spiking rates and correlations between spikes
self-consistently. Here, we will show how this can be accomplished by
constructing a complete formal probabilistic description of the network and
then expanding around a small parameter such as the inverse of the number of
neurons in the network. The mean field theory of the system gives a rate-like
description. The first order terms in the perturbation expansion keep track of
covariances.


title:
High Energy Collisions of Dense Hadrons in Quantum Chromodynamics : LHC
  Phenomenology and Universality of Parton Distributions

abstract:
  As the value of the longitudinal momentum carried by partons in a
ultra-relativistic hadron becomes small, one observes a growth of their
density. When the parton density becomes close to a value of order
$1/\alpha_s$, it does not grow any longer, it saturates. These high density
effects seem to be well described by the Color Glass Condensate effective field
theory. On the experimental side, the LHC provides the best tool ever for
reaching the saturated phase of hadronic matter. For this reason saturation
physics is a very active branch of QCD during these past and coming years since
saturation theories and experimental data can be compared. I first deal with
the phenomenology of the proton-lead collisions performed in winter 2013 at the
LHC and whose data are about to be available. I compute the di-gluon production
cross-section which provides the simplest observable for finding quantitative
evidences of saturation in the kinematic range of the LHC. I also discuss the
limit of the strongly correlated final state at large transverse momenta and by
the way, generalize parton distribution to dense regime. The second main topic
is the quantum evolution of the quark and gluon spectra in nucleus-nucleus
collisions having in mind the proof of its universal character. This result is
already known for gluons and here I detail the calculation carefully. For
quarks universality has not been proved yet but I derive an intermediate
leading order to next-to leading order recursion relation which is a crucial
step for extracting the quantum evolution. Finally I briefly present an
independent work in group theory. I detail a method I used for computing traces
involving an arbitrary number of group generators, a situation often
encountered in QCD calculations.


title: Alignment in star-debris disc systems seen by Herschel

abstract:
  Many nearby main-sequence stars have been searched for debris using the
far-infrared Herschel satellite, within the DEBRIS, DUNES and Guaranteed-Time
Key Projects. We discuss here 11 stars of spectral types A to M where the
stellar inclination is known and can be compared to that of the
spatially-resolved dust belts. The discs are found to be well aligned with the
stellar equators, as in the case of the Sun's Kuiper belt, and unlike many
close-in planets seen in transit surveys. The ensemble of stars here can be
fitted with a star-disc tilt of ~<10 degrees. These results suggest that
proposed mechanisms for tilting the star or disc in fact operate rarely. A few
systems also host imaged planets, whose orbits at tens of AU are aligned with
the debris discs, contrary to what might be expected in models where external
perturbers induce tilts.


title: Light quark mass dependence of the X(3872) in XEFT

abstract:
  The quark mass dependence of hadrons is an important input for lattice
calculations. We investigate the light quark mass dependence of the binding
energy of the X(3872) and the Dbar0-D*0 scattering length in the C=+1 channel
to next-to-leading order in XEFT where pion interactions are perturbative. At
this order, the quark mass dependence is determined by a quark mass-dependent
contact interaction in addition to the one-pion exchange. Using naturalness
arguments to constrain unknown parameters, we find a moderate sensitivity of
the binding energy for quark masses up to twice the physical value while the
scattering length is more sensitive. The occurrence of infrared divergences due
to on-shell pions in XEFT and their treatment is discussed in detail.


title:
Optimal Asymmetric Binary Quantization for Estimation Under
  Symmetrically Distributed Noise

abstract:
  Estimation of a location parameter based on noisy and binary quantized
measurements is considered in this letter. We study the behavior of the
Cramer-Rao bound as a function of the quantizer threshold for different
symmetric unimodal noise distributions. We show that, in some cases, the
intuitive choice of threshold position given by the symmetry of the problem,
placing the threshold on the true parameter value, can lead to locally worst
estimation performance.


title:
Double-peaked thermonuclear bursts at the soft-hard state transition in
  the Rapid Burster

abstract:
  Long suspected to be due to unstable accretion events, the type II bursts
exhibited by the Rapid Burster (RB, or MXB 1730-335) still lack an exhaustive
explanation. Apart from type II bursts, the transient RB also shows the
better-understood thermonuclear shell flashes known as type I bursts. In search
of links between these two phenomena, we carried out a comprehensive analysis
of all $\textit{Rossi X-ray Timing Explorer}$ observations of the RB and found
six atypical type I bursts, featuring a double-peaked profile that is not due
to photospheric radius expansion. The bursts appear in a phase of the outburst
decay close to the onset of the type II bursts, when the source also switches
from the high/soft to the low/hard state. We also report the discovery of a
simultaneous low-frequency quasi-periodic oscillation present in the persistent
emission as well as in the burst decaying emission. We discuss several
scenarios to understand the nature of the peculiar bursts and of the
accompanying oscillation, as well as their possible relation with each other
and with the type II burst phenomenon. We favour a model consisting of two
accretion channels, one polar and one equatorial, in a source viewed at low
inclination. We also, for the first time, clearly identify the atoll nature of
the RB.


title:
Geometric local theta correspondence for dual reductive pairs of type II
  at the Iwahori level

abstract:
  In this paper we are interested in the geometric local theta correspondence
at the Iwahori level for dual reductive pairs $(G,H)$ of type II over a
non-Archimedean field of characteristic $p\neq 2$ in the framework of the
geometric Langlands program. We consider the geometric version of the
$I_{H}\times I_{G}$-invariants of the Weil representation
$\mathcal{S}^{I_{H}\times I_{G}}$ as a bimodule under the of action
Iwahori-Hecke algebras $\mathcal{H}_{I_{G}}$ and $\mathcal{H}_{I_{H}}$ and we
give some partial geometric description of the corresponding category under the
action of Hecke functors. We also define geometric Jacquet functors for any
connected reductive group $G$ at the Iwahori level and we show that they
commute with the Hecke action of the $\mathcal{H}_{I_{L}}$-subelgebra of
$\mathcal{H}_{I_{G}}$ for a Levi subgroup $L$.


title: A new look at the Julg-Valette homotopy for groups acting on trees

abstract:
  We propose a new look at the Julg-Valette theorem on K-theoretic amenability
for groups operating on trees. The main tool is a generalization of a
construction of uniformly bounded representations of the free groups due to
Pytlik and Szwarc.


title: Descendants of Magnetic and non-Magnetic A-type Stars

abstract:
  We have studied the magnetic field of about 50 active and non-active single
G-K-type red giants by means of spectropolarimetry with Narval and ESPaDOnS. 30
giants have been significantly Zeeman-detected. A close study of the 17 giants
with known rotational periods shows that the measured magnetic field strength
is correlated to the rotation, in particular to the Rossby number. 4 giants for
which the magnetic field is measured to be outstandingly strong with respect to
the rotational period or the evolutionary state are identified as probable
Ap-star descendants. We detail their magnetic properties and propose criteria
to identify Ap-star descendants.


title:
Dual and backward SDE representation for optimal control of
  non-Markovian SDEs

abstract:
  We study optimal stochastic control problem for non-Markovian stochastic
differential equations (SDEs) where the drift, diffusion coefficients, and gain
functionals are path-dependent, and importantly we do not make any ellipticity
assumption on the SDE. We develop a controls randomization approach, and prove
that the value function can be reformulated under a family of dominated
measures on an enlarged filtered probability space. This value function is then
characterized by a backward SDE with nonpositive jumps under a single
probability measure, which can be viewed as a path-dependent version of the
Hamilton-Jacobi-Bellman equation, and an extension to $G$ expectation.


title: Tau/Charm Factory Accelerator Report

abstract:
  The present Report concerns the current status of the Italian Tau/Charm
accelerator project and in particular discusses the issues related to the
lattice design, to the accelerators systems and to the associated conventional
facilities. The project aims at realizing a variable energy Flavor Factory
between 1 and 4.6 GeV in the center of mass, and succeeds to the SuperB project
from which it inherits most of the solutions proposed in this document. The
work comes from a cooperation involving the INFN Frascati National Laboratories
accelerator experts, the young newcomers, mostly engineers, of the Cabibbo Lab
consortium and key collaborators from external laboratories.


title: Optimal Scalar Quantization for Parameter Estimation

abstract:
  In this paper, we study an asymptotic approximation of the Fisher information
for the estimation of a scalar parameter using quantized measurements. We show
that, as the number of quantization intervals tends to infinity, the loss of
Fisher information induced by quantization decreases exponentially as a
function of the number of quantization bits. A characterization of the optimal
quantizer through its interval density and an analytical expression for the
Fisher information are obtained. A comparison between optimal uniform and
non-uniform quantization for the location and scale estimation problems shows
that non-uniform quantization is only slightly better. As the optimal
quantization intervals are shown to depend on the unknown parameters, by
applying adaptive algorithms that jointly estimate the parameter and set the
thresholds in the location and scale estimation problems, we show that the
asymptotic results can be approximately obtained in practice using only 4 or 5
quantization bits.


title:
Some exact solutions to the Lighthill Whitham Richards Payne traffic
  flow equations II: moderate congestion

abstract:
  We find a further class of exact solutions to the Lighthill Whitham Richards
Payne (LWRP) traffic flow equations. As before, using two consecutive
Lagrangian transformations, a linearization is achieved. Next, depending on the
initial density, we either obtain exact formulae for the dependence of the car
density and velocity on x, t, or else, failing that, the same result in a
parametric representation. The calculation always involves two possible
factorizations of a consistency condition. Both must be considered. In physical
terms, the lineup usually separates into two offshoots at different velocities.
Each velocity soon becomes uniform. This outcome in many ways resembles not
only Rowlands, Infeld and Skorupski J. Phys. A: Math. Theor. 46 (2013) 365202
(part I) but also the two soliton solution to the Korteweg-de Vries equation.
This paper can be read independently of part I. This explains unavoidable
repetitions. Possible uses of both papers in checking numerical codes are
indicated at the end. Since LWRP, numerous more elaborate models, including
multiple lanes, traffic jams, tollgates etc. abound in the literature. However,
we present an exact solution. These are few and far between, other then found
by inverse scattering. The literature for various models, including ours, is
given. The methods used here and in part I may be useful in solving other
problems, such as shallow water flow.


title: Avoiding Loopholes with Hybrid Bell-Leggett-Garg Inequalities

abstract:
  By combining the postulates of macrorealism with Bell locality, we derive a
qualitatively different hybrid inequality that avoids two loopholes that
commonly appear in Leggett-Garg and Bell inequalities. First, locally invasive
measurements can be used, which avoids the "clumsiness" Leggett-Garg inequality
loophole. Second, a single experimental ensemble with fixed analyzer settings
is sampled, which avoids the "disjoint sampling" Bell inequality loophole. The
derived hybrid inequality has the same form as the Clauser-Horne-Shimony-Holt
Bell inequality; however, its quantum violation intriguingly requires weak
measurements. A realistic explanation of an observed violation requires either
the failure of Bell locality, or a preparation-conspiracy of finely tuned and
nonlocally correlated noise. Modern superconducting and optical systems are
poised to implement this test.


title: A classification of 2-dim Lattice Theory

abstract:
  A unified classification and analysis is presented of two dimensional Dirac
operators of QCD-like theories in the continuum as well as in a naive lattice
discretization. Thereby we consider the quenched theory in the strong coupling
limit. We do not only consider the case of a lattice which has an even number
of lattice sites in both directions and is thus equivalent to the case of
staggered fermions. We also study lattices with one or both directions with an
odd parity to understand the general mechanism of changing the universality
class via a discretization. Furthermore we identify the corresponding random
matrix ensembles sharing the global symmetries of these QCD-like theories.
Despite the Mermin-Wagner-Coleman theorem we find good agreement of lattice
data with our random matrix predictions.


title: Plasmonic materials for energy: from physics to applications

abstract:
  Physical mechanisms unique to plasmonic materials, which can be exploited for
the existing and emerging applications of plasmonics for renewable energy
technologies, are reviewed. The hybrid nature of surface plasmon (SP) modes -
propagating surface plasmon polaritons (SPPs) and localized surface plasmons
(LSPs) - as collective photon-electron oscillations makes them attractive
candidates for energy applications. High density of optical states in the
vicinity of plasmonic structures enhances light absorption and emission,
enables localized heating, and drives near-field heat exchange between hot and
cold surfaces. SP modes channel the energy of absorbed photons directly to the
free electrons, and the generated hot electrons can be utilized in
thermoelectric, photovoltaic and photo-catalytic platforms. Advantages and
disadvantages of using plasmonics over conventional technologies for solar
energy and waste heat harvesting are discussed, and areas where plasmonics is
expected to lead to performance improvements not achievable by other methods
are identified.

categories: physics.optics cond-mat.mes-hall cond-mat.mtrl-sci physics.class-ph quant-ph


title: Matrices with totally positive powers and their generalizations

abstract:
  In this paper, eventually totally positive matrices (i.e. matrices all whose
powers starting with some point are totally positive) are studied. We present a
new approach to eventual total positivity which is based on the theory of
eventually positive matrices. We mainly focus on the spectral properties of
such matrices. We also study eventually J-sign-symmetric matrices and matrices,
whose powers are P-matrices.


title: Planar graphene tunnel field-effect transistor

abstract:
  We propose a concept for a graphene tunnel field-effect transistor. The main
idea is based on the use of two graphene electrodes with zigzag termination
divided by a narrow gap under the influence of the common gate. Our analysis
shows that such device will have a pronounced switching effect at low gate
voltage and high on/off current ratio at room temperature.


title:
Large deviations for correlated random variables described by a matrix
  product ansatz

abstract:
  We study the large deviations of sums of correlated random variables
described by a matrix product ansatz, which generalizes the product structure
of independent random variables to matrices whose non-commutativity is the
source of correlations. We show with specific examples that different large
deviation behaviors can be found with this ansatz. In particular, it is
possible to construct sums of correlated random variables that violate the Law
of Large Numbers, the Central Limit Theorem, as well as sums that have
nonconvex rate functions or rate functions with linear parts or plateaux.


title:
The multivariate Meixner polynomials as matrix elements of $SO(d,1)$
  representations on oscillator states

abstract:
  The multivariate Meixner polynomials are shown to arise as matrix elements of
unitary representations of the $SO(d,1)$ group on oscillator states. These
polynomials depend on $d$ discrete variables and are orthogonal with respect to
the negative multinomial distribution. The emphasis is put on the bivariate
case for which the SO(2,1) connection is used to derive the main properties of
the polynomials: orthogonality relation, raising/lowering relations, generating
function, recurrence relations and difference equations as well as explicit
expressions in terms of standard (univariate) Krawtchouk and Meixner
polynomials. It is explained how these results generalize directly to $d$
variables.


title: Quantum magnons of the intermediate phase of half-doped manganite oxides

abstract:
  At half doping, the ground state of three-dimensional manganite perovskite
oxides like R$_{1-x}$Ca$_x$MnO$_3$, where R is a trivalent ion such as La, Pr,
etc, is still unclear. Many experimental findings agree better with the
combined magnetic, charge, and orbital order characteristic of the
"intermediate phase", introduced by Efremov et al. in 2004 [Nature Mats. 3,
853]. This phase consists of spin dimers (thus incorporating aspects of the
Zener polaron phase (ZP) proposed in 2002 by Daoud-Aladine et al. [Phys. Rev.
Lett. 89, 097205]), though formed by a pair of parallel Mn spins of different
magnitude, in principle (thereby allowing for a degree of Mn charge
disproportionation: not necessarily as large as that of Mn$^{3+}$-Mn$^{4+}$ in
Goodenough's original CE phase [Phys. Rev. 100, 564 (1955)]). In the
intermediate phase, consecutive spin dimers localed along the planar zig-zag
chains are oriented at a constant relative angle $\Phi$ between them. Varying
Mn-charge disproportionation and $\Phi$, the intermediate phase should allow to
continuously interpolate between the two limiting cases of the CE phase and the
dimer phase denoted as "orthogonal intermediate $\pi/2-$phase". It is not easy
to find a microscopic model able to describe the phenomenological intermediate
phase adequately for the spin, charge, and orbital degrees of freedom
simultaneously. Here, we study the quantum spin excitations of a planar model
of interacting localized spins, which we found can stabilize the intermediate
phase classically. We compare the quantum magnons of the intermediate phase
with those of the CE and orthogonal $\pi/2$ phases, in the context of recent
experimental results.


title: Monotone Simultaneous Embedding of Directed Paths

abstract:
  We study monotone simultaneous embeddings of upward planar digraphs, which
are simultaneous embeddings where the drawing of each digraph is upward planar,
and the directions of the upwardness of different graphs can differ. We first
consider the special case where each digraph is a directed path. In contrast to
the known result that any two directed paths admit a monotone simultaneous
embedding, there exist examples of three paths that do not admit such an
embedding for any possible choice of directions of monotonicity. We prove that
if a monotone simultaneous embedding of three paths exists then it also exists
for any possible choice of directions of monotonicity. We provide a
polynomial-time algorithm that, given three paths, decides whether a monotone
simultaneous embedding exists and, in the case of existence, also constructs
such an embedding. On the other hand, we show that already for three paths, any
monotone simultaneous embedding might need a grid of exponential (w.r.t. the
number of vertices) size. For more than three paths, we present a
polynomial-time algorithm that, given any number of paths and predefined
directions of monotonicity, decides whether the paths admit a monotone
simultaneous embedding with respect to the given directions, including the
construction of a solution if it exists. Further, we show several implications
of our results on monotone simultaneous embeddings of general upward planar
digraphs. Finally, we discuss complexity issues related to our problems.


title:
HESS J1818-154, a new composite supernova remnant discovered in TeV
  gamma rays and X-rays

abstract:
  Composite supernova remnants (SNRs) constitute a small subclass of the
remnants of massive stellar explosions where non-thermal radiation is observed
from both the expanding shell-like shock front and from a pulsar wind nebula
(PWN) located inside of the SNR. These systems represent a unique evolutionary
phase of SNRs where observations in the radio, X-ray, and $\gamma$-ray regimes
allow the study of the co-evolution of both these energetic phenomena. In this
article, we report results from observations of the shell-type SNR G15.4+0.1
performed with the High Energy Stereoscopic System (H.E.S.S.) and XMM-Newton. A
compact TeV $\gamma$-ray source, HESSJ1818-154, located in the center and
contained within the shell of G15.4+0.1 is detected by H.E.S.S. and featurs a
spectrum best represented by a power-law model with a spectral index of $-2.3
\pm 0.3_{stat} \pm 0.2_{sys}$ and an integral flux of
F$(>$0.42$\,\mathrm{TeV}$)=($0.9 \pm 0.3_{\mathrm{stat}} \pm
0.2_{\mathrm{sys}}) \times 10^{-12}$cm$^{-2}$s$^{-1}$. Furthermore, a recent
observation with XMM-Newton reveals extended X-ray emission strongly peaked in
the center of G15.4+0.1. The X-ray source shows indications of an
energy-dependent morphology featuring a compact core at energies above 4 keV
and more extended emission that fills the entire region within the SNR at lower
energies. Together, the X-ray and VHE $\gamma$-ray emission provide strong
evidence of a PWN located inside the shell of G15.4+0.1, and this SNR can
therefore be classified as a \emph{composite} based on these observations. The
radio, X-ray, and $\gamma$-ray emission from the PWN is compatible with a
one-zone leptonic model that requires a low average magnetic field inside the
emission region. An unambiguous counterpart to the putative pulsar, which is
thought to power the PWN, has been detected neither in radio nor in X-ray
observations of G15.4+0.1.


title: Iteration Complexity Analysis of Block Coordinate Descent Methods

abstract:
  In this paper, we provide a unified iteration complexity analysis for a
family of general block coordinate descent (BCD) methods, covering popular
methods such as the block coordinate gradient descent (BCGD) and the block
coordinate proximal gradient (BCPG), under various different coordinate update
rules. We unify these algorithms under the so-called Block Successive
Upper-bound Minimization (BSUM) framework, and show that for a broad class of
multi-block nonsmooth convex problems, all algorithms covered by the BSUM
framework achieve a global sublinear iteration complexity of $O(1/r)$, where r
is the iteration index. Moreover, for the case of block coordinate minimization
(BCM) where each block is minimized exactly, we establish the sublinear
convergence rate of $O(1/r)$ without per block strong convexity assumption.
Further, we show that when there are only two blocks of variables, a special
BSUM algorithm with Gauss-Seidel rule can be accelerated to achieve an improved
rate of $O(1/r^2)$.


title: Spectrum of Quantum Transfer Matrices via Classical Many-Body Systems

abstract:
  In this paper we clarify the relationship between inhomogeneous quantum spin
chains and classical integrable many-body systems. It provides an alternative
(to the nested Bethe ansatz) method for computation of spectra of the spin
chains. Namely, the spectrum of the quantum transfer matrix for the
inhomogeneous ${\mathfrak g}{\mathfrak l}_n$-invariant XXX spin chain on $N$
sites with twisted boundary conditions can be found in terms of velocities of
particles in the rational $N$-body Ruijsenaars-Schneider model. The possible
values of the velocities are to be found from intersection points of two
Lagrangian submanifolds in the phase space of the classical model. One of them
is the Lagrangian hyperplane corresponding to fixed coordinates of all $N$
particles and the other one is an $N$-dimensional Lagrangian submanifold
obtained by fixing levels of $N$ classical Hamiltonians in involution. The
latter are determined by eigenvalues of the twist matrix. To support this
picture, we give a direct proof that the eigenvalues of the Lax matrix for the
classical Ruijsenaars-Schneider model, where velocities of particles are
substituted by eigenvalues of the spin chain Hamiltonians, calculated through
the Bethe equations, coincide with eigenvalues of the twist matrix, with
certain multiplicities. We also prove a similar statement for the ${\mathfrak
g}{\mathfrak l}_n$ Gaudin model with $N$ marked points (on the quantum side)
and the Calogero-Moser system with $N$ particles (on the classical side). The
realization of the results obtained in terms of branes and supersymmetric gauge
theories is also discussed.


title:
Optimal Wegner estimate and the density of states for N-body,
  interacting Schrodinger operators with random potentials

abstract:
  We prove an optimal one-volume Wegner estimate for interacting systems of $N$
quantum particles moving in the presence of random potentials. The proof is
based on the scale-free unique continuation principle recently developed for
the 1-body problem by Rojas-Molina and Veseli\`c \cite{RM-V1} and extended to
spectral projectors by Klein \cite{klein1}. These results extend of our
previous results in \cite{CHK:2003,CHK:2007}. We also prove a two-volume Wegner
estimate as introduced in \cite{chulaevsky-suhov1}. The random potentials are
generalized Anderson-type potentials in each variable with minimal conditions
on the single-site potential aside from positivity. Under additional
conditions, we prove the Lipschitz continuity of the integrated density of
states (IDS) This implies the existence and local finiteness of the density of
states. We also apply these techniques to interacting $N$-particle
Schr\"odinger operators with Delone-Anderson type random external potentials.


title: Effect of gravitational stratification on the propagation of a CME

abstract:
  Our aim is to study the role of gravitational stratification on the
propagation of CMEs. In particular, we assess how it influences the speed and
shape of CMEs and under what conditions the flux rope ejection becomes a CME or
when it is quenched. We ran a set of MHD simulations that adopt an eruptive
initial magnetic configuration that has already been shown to be suitable for a
flux rope ejection. We varied the temperature of the backgroud corona and the
intensity of the initial magnetic field to tune the gravitational
stratification and the amount of ejected magnetic flux. We used an automatic
technique to track the expansion and the propagation of the magnetic flux rope
in the MHD simulations. From the analysis of the parameter space, we evaluate
the role of gravitational stratification on the CME speed and expansion. Our
study shows that gravitational stratification plays a significant role in
determining whether the flux rope ejection will turn into a full CME or whether
the magnetic flux rope will stop in the corona. The CME speed is affected by
the background corona where it travels faster when the corona is colder and
when the initial magnetic field is more intense. The fastest CME we reproduce
in our parameter space travels at 850 km/s. Moreover, the background
gravitational stratification plays a role in the side expansion of the CME, and
we find that when the background temperature is higher, the resulting shape of
the CME is flattened more. Our study shows that although the initiation
mechanisms of the CME are purely magnetic, the background coronal plasma plays
a key role in the CME propagation, and full MHD models should be applied when
one focusses especially on the production of a CME from a flux rope ejection.


title: Forward integration, convergence and nonadapted pointwise multipliers

abstract:
  In this paper we study the forward integral of operator-valued processes with
respect to a cylindrical Brownian motion. In particular, we provide conditions
under which the approximating sequence of processes of the forward integral,
converges to the stochastic integral process with respect to Sobolev norms of
smoothness alpha < 1/2. This result will be used to derive a new integration by
parts formula for the forward integral.


title: A quantitative theory of coherent delocalization

abstract:
  We define a quantitative measure of coherent delocalization; similarly to the
concept of entanglement measures, we require that a measure of coherent
delocalization may never increase under processes that do not create coherent
superpositions. After a complete characterization of such processes, we prove
that a set of recently introduced functions that characterize coherent
delocalization never grow under such processes and thus are indeed valid
measures.


title: TOPoS: I. Survey design and analysis of the first sample

abstract:
  The metal-weak tail of the metallicity distribution function (MDF) of the
Galactic Halo stars contains crucial information on the formation mode of the
first generation of stars. To determine this observationally, it is necessary
to observe large numbers of extremely metal-poor stars. We present here the
Turn-Off Primordial Stars survey (TOPoS) that is conducted as an ESO Large
Programme at the VLT. This project has {four} main goals: (i) to understand the
formation of low-mass stars in a low-metallicity gas: determine the metal-weak
tail of the halo MDF below [M/H]=-3.5. In particular, we aim at determining the
critical metallicity, that is the lowest metallicity sufficient for the
formation of low-mass stars; (ii) to determine the relative abundance of the
elements in extremely metal-poor stars, which are the signature of the massive
first stars; (iii) to determine the trend of the lithium abundance at the time
when the Galaxy formed; and (iv) to derive the fraction of C-enhanced extremely
metal-poor stars with respect to normal extremely metal-poor stars. The large
number of stars observed in the SDSS provides a good sample of candidates of
stars at extremely low metallicity. Candidates with turn-off colours down to
magnitude g=20 were selected from the low-resolution spectra of SDSS by means
of an automated procedure. X-Shooter has the potential of performing the
necessary follow-up spectroscopy, providing accurate metallicities and
abundance ratios for several key elements for these stars. We here present the
stellar parameters of the first set of stars. The nineteen stars range in iron
abundance between -4.1 and -2.9 dex relative to the Sun. Two stars have a high
radial velocity and, according to our estimate of their kinematics, appear to
be marginally bound to the Galaxy and are possibly accreted from another
galaxy.


title: Snowmass 2013 Computing Frontier: Intensity Frontier

abstract:
  The Intensity Frontier (IF) is a primary focus of the U.S.-based particle
physics program. It encompasses a large spectrum of physics, including quark
flavor physics, charged lepton processes, neutrinos, baryon number violation,
new light weakly-coupled particles, and nucleons, nuclei and atoms. There are
many experiments, a range of scales in data output and throughput, and a wide
range in the number of experimenters. The experiments, projects and theory in
this area all require demanding computing capabilities and technologies. The IF
experiments have significant computing requirements for simulation, theory and
modeling, beam line and experiment design, triggers and DAQ, online monitoring,
event reconstruction and processing, and physics analysis. We have conducted a
qualitative survey of the current and near-term future experiments in the IF to
understand the computing demands of this area and their expected evolution.
This report details the expected computing requirements for the IF in the
context of the Snowmass Community Summer Study 2013.


title:
A new insight into the innermost jet regions: probing extreme jet
  variability with LOFT

abstract:
  Blazars are highly variable sources over timescales that can be as low as
minutes. This is the case of the High Energy Peaked BL Lac (HBL) objects
showing strong variability in X-rays, which highly correlate with that of the
TeV emission. The degree of this correlation is still debated, particularly
when the flaring activity is followed down to very short time scales. This
correlation could challenge the synchrotron-self-Compton scenario in which one
relativistic electron population dominates the entire radiative output. We
argue that the LOFT Large Area Detector (10 m$^2$, LAD), thanks to its
unprecedented timing capability, will allow us to detect the X-ray counterpart
(2-50 keV) of the very fast variability observed at TeV energies, sheding light
on the nature of X-TeV connection. We will discuss the test case of PKS
2155-304, showing as it would be possible to look for any X-ray variability
occurring at very short timescales, never explored so far. This will put strong
constraints on the size and the location of any additional electron population
in the multi-zone scenario. Under this perspective, LOFT and the CTA
observatories, planned to operate in the same time frame, will allow us to
investigate in depth the connection between X-ray and TeV emissions. We also
discuss the potentialities of LOFT in measuring the change in spectral
curvature of the synchrotron spectra in HBLs which will make possible to
directly study the mechanism of acceleration of highly energetic electrons.
LOFT timing capability will be also promising in the study of Flat Spectrum
Radio Quasars (FSRQs) with flux $\ge 1$ mCrab. Constraints to the location of
the high energy emission will be given by temporal investigation on second
timescale and spectral trend analysis on minute timescales. This represents a
further link with CTA because of the rapid (unexpected) TeV emission recently
detected in some FSRQs.


title: Influence of a Minimal Length on the Creation of Scalar Particles

abstract:
  In this paper we have studied the problem of scalar particles pair creation
by an electric field in the presence of a minimal length. Two sets of exact
solutions for the Klein Gordon equation are given in momentum space. Then the
canonical method based on Bogoliubov transformation connecting the "in" with
the "out" states is applied to calculate the probability to create a pair of
particles and the mean number of created particles. The number of created
particles per unit of time per unit of length, which is related directly to the
experimental measurements, is calculated. It is shown that, with an electric
field less than the critical value, the minimal length minimizes the particle
creation. It is shown, also, that the limit of zero minimal length reproduces
the known results corresponding to the ordinary quantum fields.


title:
The glass transition in a nutshell: a source of inspiration to describe
  the subcritical transition to turbulence

abstract:
  The starting point of the present work is the observation of possible
analogies, both at the phenomenological and at the methodological level,
between the subcritical transition to turbulence and the glass transition.
Having recalled the phenomenology of the subcritical transition to turbulence,
we review the theories of the glass transition at a very basic level, focusing
on the history of their development as well as on the concepts they have
elaborated. Doing so, we aim at attracting the attention on the above mentioned
analogies, which we believe could inspire new developments in the theory of the
subcritical transition to turbulence. We then briefly describe a model inspired
by one of the simplest and most inspiring model of the glass transition, the
so-called Random Energy Model, as a first step in that direction.


title: Dynamics of indirect exciton transport by moving acoustic fields

abstract:
  We report on the modulation of indirect excitons (IXs) as well as their
transport by moving periodic potentials produced by surface acoustic waves
(SAWs). The potential modulation induced by the SAW strain modifies both the
band gap and the electrostatic field in the quantum wells confining the IX,
leading to changes in their energy. In addition, this potential capture and
transports IXs over several hundreds of {\mu}m. While the IX packets keep to a
great extent their spatial shape during transport by the moving potential, the
effective transport velocity is lower than the SAW group velocity and increases
with the SAW amplitude. This behavior is attributed to the capture of IXs by
traps along the transport path, thereby increasing the IX transit time. The
experimental results are well-reproduced by an analytical model for the
interaction between trapping centers and IXs during transport.


title:
NMR investigation of the pressure induced Mott transition to
  superconductivity in Cs3C60 isomeric compounds

abstract:
  The discovery in 1991 of high temperature superconductivity (SC) in A3C60
compounds, where A is an alkali ion, has been initially ascribed to a BCS
mechanism, with a weak incidence of electron correlations. However various
experimental evidences taken for compounds with distinct alkali content
established the interplay of strong correlations and Jahn Teller distortions of
the C60 ball. The importance of electronic correlations even in A3C60 has been
highlighted by the recent discovery of two expanded fulleride Cs3C60 isomeric
phases that are Mott insulators at ambient pressure. Both phases undergo a
pressure induced first order Mott transition to SC with a (p, T) phase diagram
displaying a dome shaped SC, a common situation encountered nowadays in
correlated electron systems. NMR experiments allowed us to establish that the
bipartite A15 phase displays N\'eel order at 47K, while magnetic freezing only
occurs at lower temperature in the fcc phase. NMR data do permit us to conclude
that well above the critical pressure, the singlet superconductivity found for
light alkalis is recovered. However deviations from BCS expectations linked
with electronic correlations are found near the Mott transition. So, although
SC involves an electron-phonon mechanism, correlations have a significant
incidence on the electronic properties, as had been anticipated from DMFT
calculations.


title: London Penetration Depth and Pair Breaking

abstract:
  The London penetration depth is evaluated for isotropic materials for any
transport and pair-breaking Born scattering rates. Besides known results, a
number of new features are found. The slope $|d\rho/d\theta |$ of the
normalized superfluid density $\rho=\lambda^2(0)/\lambda^2(\theta)$ at the
transition $\theta=T/T_c=1$ has a minimum near the value of the pair-breaking
parameter separating gapped and gapless states. The low-$T$ exponentially flat
part of $\rho$ for the s-wave materials is suppressed by increasing pair
breaking. For strong $T_c $ suppression by magnetic impurities the "Homes
scaling" $\lambda^{-2}(0) \propto \sigma T_c$ with $\sigma$ being the normal
conductivity gives way to $\lambda^{-2}(0) \propto \sigma T_c^2$. For the
d-wave order parameter, the transport and spin-flip Born scattering rates enter
the theory only as a sum, in particular, they affect the $T_c$ depression in
the same manner. We confirm that the linear low temperature behavior of $\rho$
in a broad range of the combined scattering parameter turns to the $T^2$
behavior only when the critical temperature is suppressed at least by a factor
of 3 relative to the clean limit $T_{c0}$. Moreover, in this range, $\rho
(\theta)$ is only weakly dependent on the scattering parameter, i.e. it is
nearly universal.


title:
Finite time extinction for stochastic sign fast diffusion and
  self-organized criticality

abstract:
  We prove finite time extinction for stochastic sign fast diffusion equations
driven by linear multiplicative space-time noise, corresponding to the
Bak-Tang-Wiesenfeld model for self-organized criticality. This solves a problem
posed and left open in several works: [Barbu, Da Prato, R\"ockner, CMP, 2009],
[Barbu, Da Prato, R\"ockner, CRMAS, 2009], [Barbu, R\"ockner, CMP, 2012],
[Barbu, Da Prato, R\"ockner, JMAA, 2012], [R\"ockner, Wang, JMLS, 2013],
[Barbu, MMAS, 2013]. The highly singular-degenerate nature of the drift in
interplay with the stochastic perturbation causes the need for new methods in
the analysis of mass diffusion and several new estimates and techniques are
introduced.


title: Coarse grained NN potential with Chiral Two Pion Exchange

abstract:
  We determine the chiral constants of the Nucleon-Nucleon Two Pion Exchange
potential deduced from Chiral Perturbation Theory. By using a coarse grained
representation of the short distance interactions with 30 parameters, the
Partial Wave Analysis fit gives chi^2/dof = 1.1 to a mutually consistent set of
6713 data previously built from all published proton-proton and neutron proton
scattering data from 1950 till 2013 with LAB energy below 350 MeV. We obtain
(c1, c3, c4)=(-0.41+- 1.08,-4.66+- 0.60, 4.31+- 0.17)/GeV with an almost 100%
anti-correlation between c1 and c3. We also provide the errors in the short
distance parameters and propagate them to the deuteron properties and low
partial waves phase shifts.


title: Typical automorphism groups of finite nonrigid structures

abstract:
  We work with a finite relational vocabulary with at least one relation symbol
with arity at least 2. Fix any integer $m > 1$. For almost all finite
structures (labelled or unlabelled) such that at least $m$ elements are moved
by some automorphisms, the automorphism group is $(Z_2)^i$ for some $i \leq
(m+1)/2$; and if some relation symbol has arity at least 3, then the
automorphism group is almost always $Z_2$.


title: Effective multiple mixing in semidirect product actions

abstract:
  We prove effective decay of certain multiple correlation coefficients for
measure preserving, mixing Weyl chamber actions of semidirect products of
semisimple groups with $G$-vector spaces. These estimates provide decay for
some semisimple groups of higher rank.


title: Switching Exciton Pulses Through Conical Intersections

abstract:
  Exciton pulses transport excitation and entanglement adiabatically through
Rydberg aggregates, assemblies of highly excited light atoms, which are set
into directed motion by resonant dipole-dipole interaction. Here, we
demonstrate the coherent splitting of such pulses as well as the spatial
segregation of electronic excitation and atomic motion. Both mechanisms exploit
local nonadiabatic effects at a conical intersection, turning them from a
decoherence source into an asset. The intersection provides a sensitive knob
controlling the propagation direction and coherence properties of exciton
pulses. The fundamental ideas discussed here have general implications for
excitons on a dynamic network.


title: On Logical Depth and the Running Time of Shortest Programs

abstract:
  The logical depth with significance $b$ of a finite binary string $x$ is the
shortest running time of a binary program for $x$ that can be compressed by at
most $b$ bits. There is another definition of logical depth. We give two
theorems about the quantitative relation between these versions: the first
theorem concerns a variation of a known fact with a new proof, the second
theorem and its proof are new. We select the above version of logical depth and
show the following. There is an infinite sequence of strings of increasing
length such that for each $j$ there is a $b$ such that the logical depth of the
$j$th string as a function of $j$ is incomputable (it rises faster than any
computable function) but with $b$ replaced by $b+1$ the resuling function is
computable. Hence the maximal gap between the logical depths resulting from
incrementing appropriate $b$'s by 1 rises faster than any computable function.
All functions mentioned are upper bounded by the Busy Beaver function. Since
for every string its logical depth is nonincreasing in $b$, the minimal
computation time of the shortest programs for the sequence of strings as a
function of $j$ rises faster than any computable function but not so fast as
the Busy Beaver function.


title: New canonical triple covers of surfaces

abstract:
  We construct a surface of general type with canonical map of degree 12 which
factors as a triple cover and a bidouble cover of $\mathbb P^2$. We also show
the existence of a smooth surface with $q=0,$ $\chi=13$ and $K^2=9\chi$ such
that its canonical map is either of degree 3 onto a surface of general type or
of degree 9 onto a rational surface.


title: Computing finite models using free Boolean generators

abstract:
  A parallel method for computing Boolean expressions based on the properties
of finite free Boolean algebras is presented. We also show how various finite
combinatorial objects can be codded in the formalism of Boolean algebras and
counted by this procedure. Particularly, using a translation of first order
predicate formulas to propositional formulas, we give a method for constructing
and counting finite models of the first order theories. An implementation of
the method that can be run on multi-core CPUs as well as on highly parallel
GPUs is outlined.


title: Conformal invariance of the 3D self-avoiding walk

abstract:
  We show that if the three dimensional self-avoiding walk (SAW) is conformally
invariant, then one can compute the hitting densities for the SAW in a half
space and in a sphere. We test these predictions by Monte Carlo simulations and
find excellent agreement, thus providing evidence that the SAW is conformally
invariant in three dimensions.


title:
Protein signatures using electrostatic molecular surfaces in harmonic
  space

abstract:
  We developed a novel method based on the Fourier analysis of protein
molecular surfaces to speed up the analysis of the vast structural data
generated in the post-genomic era. This method computes the power spectrum of
surfaces of the molecular electrostatic potential, whose three-dimensional
coordinates have been either experimentally or theoretically determined. Thus
we achieve a reduction of the initial three-dimensional information on the
molecular surface to the one-dimensional information on pairs of points at a
fixed scale apart. Consequently, the similarity search in our method is
computationally less demanding and significantly faster than shape comparison
methods. As proof of principle, we applied our method to a training set of
viral proteins that are involved in major diseases such as Hepatitis C, Dengue
fever, Yellow fever, Bovine viral diarrhea and West Nile fever. The training
set contains proteins of four different protein families, as well as a
mammalian representative enzyme. We found that the power spectrum successfully
assigns a unique signature to each protein included in our training set, thus
providing a direct probe of functional similarity among proteins. The results
agree with established biological data from conventional structural
biochemistry analyses.


title: Quasirelativistic Langevin equation

abstract:
  We address the problem of a microscopic derivation of the Langevin equation
for a weakly relativistic Brownian particle. A non-covariant Hamiltonian model
is adopted, in which the free motion of particles is described
relativistically, while their interaction is treated classically, i.e. by means
of action-to-a-distance interaction potentials. Relativistic corrections to the
classical Langevin equation emerge as nonlinear dissipation terms and originate
from the nonlinear dependence of the relativistic velocity on momentum. On the
other hand, similar nonlinear dissipation forces also appear as classical
(non-relativistic) corrections to the weak-coupling approximation. It is shown
that these classical corrections, which are usually ignored in phenomenological
models, may be of the same order of magnitude, if not larger than relativistic
ones. The interplay of relativistic corrections and classical
beyond-the-weak-coupling contributions determines the sign of the leading
nonlinear dissipation term in the Langevin equation, and thus is qualitatively
important.


title: Thermal axion production

abstract:
  We reconsider thermal production of axions in the early universe, including
axion couplings to all Standard Model (SM) particles. Concerning the axion
coupling to gluons, we find that thermal effects enhance the axion production
rate by a factor of few with respect to previous computations performed in the
limit of small strong gauge coupling. Furthermore, we find that the top Yukawa
coupling induces a much larger axion production rate, unless the axion couples
to SM particles only via anomalies.


title: Illustration of Babinet's principle with ultracold atoms

abstract:
  We demonstrate Babinet's principle by the absorption of high intensity light
from dense clouds of ultracold atoms. Images of the diffracted light are
directly related to the spatial distribution of atoms. The advantages of
employing Babinet's principle as an imaging technique are that it is easy to
implement and the detected signal is large. We discuss the regimes of
applicability of this technique as well as its limitations.


title:
Positive solutions for a nonlinear elliptic problem with strong lack of
  compactness

abstract:
  This paper deals with the lack of compactness in nonlinear elliptic problems
$(P)$. In particular, a domain $\Omega$ is provided where not converging
Palais-Smale sequences exist at every energy level. Nevertheless, it is proved
that problem $(P)$ has infinitely many solutions on $\Omega$.


title: Quantum Gaudin model and classical KP hierarchy

abstract:
  This short note is a review of the intriguing connection between the quantum
Gaudin model and the classical KP hierarchy recently established in [1]. We
construct the generating function of integrals of motion for the quantum Gaudin
model with twisted boundary conditions (the master T-operator) and show that it
satisfies the bilinear identity and Hirota equations for the classical KP
hierarchy. This implies that zeros of eigenvalues of the master $T$-operator in
the spectral parameter have the same dynamics as the Calogero-Moser system of
particles.