title: Gaussian process regression for survival data with competing risks

abstract:
  We apply Gaussian process (GP) regression, which provides a powerful
non-parametric probabilistic method of relating inputs to outputs, to survival
data consisting of time-to-event and covariate measurements. In this context,
the covariates are regarded as the `inputs' and the event times are the
`outputs'. This allows for highly flexible inference of non-linear
relationships between covariates and event times. Many existing methods, such
as the ubiquitous Cox proportional hazards model, focus primarily on the hazard
rate which is typically assumed to take some parametric or semi-parametric
form. Our proposed model belongs to the class of accelerated failure time
models where we focus on directly characterising the relationship between
covariates and event times without any explicit assumptions on what form the
hazard rates take. It is straightforward to include various types and
combinations of censored and truncated observations. We apply our approach to
both simulated and experimental data. We then apply multiple output GP
regression, which can handle multiple potentially correlated outputs for each
input, to competing risks survival data where multiple event types can occur.
By tuning one of the model parameters we can control the extent to which the
multiple outputs (the time-to-event for each risk) are dependent thus allowing
the specification of correlated risks. Simulation studies suggest that in some
cases assuming dependence can lead to more accurate predictions.


title: Diffusive motion of particles and dimers over anisotropic lattices

abstract:
  Behavior of the mixture of particles and dimers moving with different jump
rates at reconstructed surfaces is described. Collective diffusion coefficient
is calculated by the variational approach. Anisotropy of the collective
particle motion is analyzed as a function of jump rates and local particle
density. Analytic expressions are compared with the results of Monte Carlo
simulations of diffusing particle and dimer mixture. Direction of driven
diffusive motion of the same system depends on the jump anisotropy and on the
value of driving force. Driven motion results in the particle and dimer
separation when the directions of their easy diffusion axes differ. It is shown
that in such case trapping sites concentrated at some surface areas act as
filters or barriers for particle and dimer mixtures.


title:
Performance Analysis of Network Coded Systems Under Quasi-static
  Rayleigh Fading Channels

abstract:
  In the area of basic and network coded cooperative communication, the
expected end-to-end bit error rate (BER) values are frequently required to
compare the proposed coding, relaying, and decoding techniques. Instead of
obtaining these values via time consuming Monte Carlo simulations, deriving
closed form expressions using approximations is crucial. In this work, the
ultimate goal is to derive an approximate average BER expression for a network
coded system. While reaching this goal, we firstly consider the cooperative
systems' instantaneous BER values that are commonly composed of Q-functions of
more than one variables. For these Q-functions, we investigate the convergence
characteristics of the sampling property and generalize this property to
arbitrary functions of multiple variables. Second, we adapt the equivalent
channel approach to the network coded scenario for the ease of analysis and
propose a network decoder with reduced complexity. Finally, by combining these
techniques, we show that the obtained closed form expressions well agree with
simulation results in a wide SNR range.


title: TMD-Factorization in Hadron-Hadron Collision

abstract:
  Proof of transverse-momentum-dependent(TMD) factorization for hadron-hadron
collision is given in this paper. We focus on processes without detected soft
final hadrons or detected final hadrons that are collinear to initial hadrons.
This contradicts the widely accepted viewpoint that TMD- factorization does not
hold in such processes even in the generalized sense. The key point is that
singular points of the type l+ = 0 can be absorbed into Wilson lines of soft
gluons, where l is collinear to the plus direction. Thus one should subtract
such singular points from the collinear region of l. After such subtraction,
one can make use of Ward identity to absorb effects of scalar-polarized
collinear gluons into Wilson lines.


title:
The Green Bank Telescope Maps the Dense, Star-Forming Gas in the Nearby
  Starburst Galaxy M82

abstract:
  Observations of the Milky Way and nearby galaxies show that dense molecular
gas correlates with recent star formation, suggesting that the formation of
this gas phase may help regulate star formation. A key test of this idea
requires wide-area, high-resolution maps of dense molecular gas in galaxies to
explore how local physical conditions drive dense gas formation, but these
observations have been limited because of the faintness of dense gas tracers
like HCN and HCO+. Here we demonstrate the power of the Robert C. Byrd Green
Bank Telescope -- the largest single-dish millimeter radio telescope -- for
mapping dense gas in galaxies by presenting the most sensitive maps yet of HCN
and HCO+ in the starburst galaxy M82. The HCN and HCO+ in the disk of this
galaxy correlates with both recent star formation and more diffuse molecular
gas and shows kinematics consistent with a rotating torus. The HCO+ emission
extending to the north and south of the disk is coincident with the outflow
previously identified in CO and traces the eastern edge of the hot outflowing
gas. The central starburst region has a higher ratio of star formation to dense
gas than the outer regions, pointing to the starburst as a key driver of this
relationship. These results establish that the GBT can efficiently map the
dense molecular gas at 90 GHz in nearby galaxies, a capability that will
increase further with the 16 element feed array under construction.


title: Tomography of exotic hadrons in high-energy exclusive processes

abstract:
  We investigated the possibility of determining internal structure of exotic
hadrons by using high-energy reaction processes, where quarks and gluons are
appropriate degrees of freedom. In particular, it should be valuable to
investigate the high-energy exclusive processes which include generalized
parton distributions (GPDs) and generalized distribution amplitudes (GDAs). The
GPDs and GDAs contain momentum distributions of partons and form factors. We
found that the exotic nature appears in momentum distributions of quarks as
suggested by the constituent-counting rule and in the form factors associated
with exotic hadron sizes and the number of constituents. Transition GPDs to
exotic hadrons could probe such exotic signatures. We also propose that these
exotic signatures should be found in exclusive production processes of exotic
hadrons from gamma^* gamma in electron-positron annihilation. For example, the
GDAs contain information on a time-like form factor of the energy-momentum
tensor of a hadron h. We show that the cross section of e gamma -> e+hbar h is
sensitive to the exotic signature by looking at the hbar h invariant-mass
dependence by taking light hadrons, h=f_0 (980) and a_0 (980). From such GDA
measurements, the tomography of exotic hadrons becomes possible, for example,
by Belle and BaBar experiments and by future linear collider.


title: Traveling surface waves of moderate amplitude in shallow water

abstract:
  We study traveling wave solutions of an equation for surface waves of
moderate amplitude arising as a shallow water approximation of the Euler
equations for inviscid, incompressible and homogenous fluids. We obtain
solitary waves of elevation and depression, including a family of solitary
waves with compact support, where the amplitude may increase or decrease with
respect to the wave speed. Our approach is based on techniques from dynamical
systems and relies on a reformulation of the evolution equation as an
autonomous Hamiltonian system which facilitates an explicit expression for
bounded orbits in the phase plane to establish existence of the corresponding
periodic and solitary traveling wave solutions.


title: Characterization of casein and Poly-L-arginine Multilayer Films

abstract:
  Thin films containing casein appear to be a promising material for coatings
used in the medical area to promote biomineralization. alfa- and beta-casein
and poly-L-arginine multilayer films were formed by the layer-by layer
technique and their thickness and mass were analyzed by ellipsometry and quartz
crystal microbalance with dissipation monitoring (QCM-D). We investigated the
effect of the type of casein used for the film formation and of the
polyethyleneimine anchoring layer on the thickness and mass of adsorbed films.
The analysis of the mass of films during their post-treatment with the
solutions of various ionic strength and pH provided the information concerning
films stability, while the XPS elemental analysis confirmed binding of calcium
ions by the casein embedded in the multilayers.


title:
Nonlinear current-voltage characteristics due to quantum tunneling of
  phase slips in superconducting Nb nanowire networks

abstract:
  We report on the transport properties of an array of N about 30
interconnected Nb nanowires, grown by sputtering on robust porous Si
substrates. The analyzed system exhibits a broad resistive transition in zero
magnetic field, H, and highly nonlinear V(I) characteristics as a function of H
which can be both consistently described by quantum tunneling of phase slips.


title: The Open Quantum Brownian Motion

abstract:
  Using quantum parallelism on random walks as original seed, we introduce new
quantum stochastic processes, the open quantum Brownian motions. They describe
the behaviors of quantum walkers -- with internal degrees of freedom which
serve as random gyroscopes -- interacting with series of probes. These
processes may also be viewed as the scaling limit of open quantum random walks
and we develop this approach along three different lines: quantum trajectory,
quantum dynamical map, and quantum stochastic differential equation. We also
present a study of the simplest case, with a two level system as internal
gyroscope, illustrating the interplay between ballistic and diffusive behaviors
at work in these processes.

categories: math-ph cond-mat.stat-mech math.MP math.PR quant-ph


title: Studies of charmed baryons at LHCb

abstract:
  We report a search for the doubly charmed baryon $\Xi_{cc}^{+}$ through the
decay $\Xi_{cc}^{+} \to \Lambda_{c}^{+} K^{-} \pi^{+}$, using a data sample
corresponding to an integrated luminosity of $0.65~\mathrm{pb^{-1}}$ of $pp$
collisions at $\mathrm{\sqrt{s}} = 7~\mathrm{TeV}$. In the mass range
3300-3800$~\mathrm{MeV}/c^{2}$ no significant signal is observed. Upper limits
at $95\%$ confidence level are set on $R$, the ratio of the production cross
section of the $\Xi_{cc}^{+}$ times the relevant branching fraction over the
$\Lambda_{c}^{+}$ cross section, as a function of the $\Xi_{cc}^{+}$ mass and
lifetime. The largest upper limits on $R$ over the investigated mass range are
$R<1.5\times10^{-2}$ for a lifetime of $100~\mathrm{fs}$ and
$R<3.9\times10^{-4}$ for a lifetime of $400~\mathrm{fs}$.


title: La Silla QUEST RR Lyrae Star Survey: Region I

abstract:
  A search for RR Lyrae stars (RRLS) in 840 sq.deg. of the sky in right
ascension 150 - 210 deg and declination -10 - +10 deg yielded 1013 type ab and
359 type c RRLS. This sample is used to study the density profile of the
Galactic halo, halo substructures, and the Oosterhoff type of the halo over
distances from 5 to 80 kpc. The halo is flattened towards the Galactic plane,
and its density profile steepens in slope at galactocentric distances greater
than 25 kpc. The RRLS in the stellar stream from the Sagittarius dwarf
spheroidal (dSph) galaxy match well the model of Law and Majewski for the stars
that were stripped 1.3 to 3.2 Gyr ago, but not for the ones stripped 3.2 to 5.0
Gyr ago. Over densities are found at the locations of the Virgo Overdensity and
the Virgo Stellar Stream. Within 1 deg of 1220-1, which Jerjen et al. identify
as a halo substructure at a distance of 24 kpc, there are 4 RRLS that are
possibly members. Away from substructures, the RRLS are a mixture of Oosterhoff
types I and II, but mostly OoI (73%). The accretion of galaxies resembling in
RRLS content the most massive Milky Way satellites (LMC, SMC, For,Sgr) may
explain this preponderance of OoI. Six new RRLS and 3 new anomalous Cepheids
were found in the Sextans dSph galaxy.


title:
US and European Technology Roadmap for a Mid-infrared Space
  Interferometer

abstract:
  Studies of mid-infrared space interferometer concepts in the USA and in
Europe have converged on a single architecture. We address the question of how
the US and European communities could collaborate to advance technology efforts
leading to a future space mission. We present the current state of the art in
nulling interferometry, as demonstrated at ambient temperature and pressure in
the lab, and outline required steps to demonstrate its performance under space
conditions. Design studies of a cryogenic optical test bench under vacuum have
already been carried out. We highlight pre-conditions and constraints of a
collaborative effort, foreseeable practical and administrative challenges, and
possible strategies to meet those challenges.


title:
Asymptotic expansions of exponentials of digamma function and identity
  for Bernoulli polynomials

abstract:
  The asymptotic expansion of digamma function is a starting point for the
derivation of approximants for harmonic sums or Euler-Mascheroni constant. It
is usual to derive such approximations as values of logarithmic function, which
leads to the expansion of the exponentials of digamma function. In this paper
the asymptotic expansion of the function $\exp(p\psi(x+t))$ is derived and
analyzed in details, especially for integer values of parameter $p$. The
behavior for integer values of $p$ is proved and as a consequence a new
identity for Bernoulli polynomials. The obtained formulas are used to improve
know inequalities for Euler's constant and harmonic numbers.


title:
Resonances f0(1370), f0(1500) and f0(1710) within the extended Linear
  Sigma Model

abstract:
  In the framework of the extended Linear Sigma Model (eLSM) we investigate the
masses and decays of the three scalar-isoscalar resonances $f_{0}(1370)$,
$f_{0}(1500)$ and $f_{0}(1710)$. The degrees of freedom of the eLSM are
(pseudo)scalars and (axial)vectors as well as the scalar glueball. Although
still preliminary, present results, based on the physical masses of the above
mentioned resonances, show that $f_{0}(1710)$ is the predominantly glueball
state. However, acceptable decays for this resonance can be obtained only for a
(very) large gluon condensate.


title: Weak KAM theorem for Hamilton-Jacobi equations

abstract:
  In this paper, we generalize weak KAM theorem from positive Lagrangian
systems to "proper" Hamilton-Jacobi equations.
  We introduce an implicitly defined solution semigroup of evolutionary
Hamilton-Jacobi equations. By exploring the properties of the solution
semigroup, we prove the convergence of solution semigroup and existence of weak
KAM solutions for stationary equations: \begin{equation*} H(x, u, d_x u)=0.
\end{equation*}


title: The Darwin-Breit magnetic interaction and superconductivity

abstract:
  A number of facts indicating the relevance of the Darwin magnetic interaction
energy in the superconducting phase are pointed out. The magnetic interaction
term derived by Darwin is the same as the, so called, Breit term in
relativistic quantum mechanics. While this term always is a small perturbation
in few body systems it can be shown to be potentially dominating in systems of
large numbers of electrons. It is therefore a natural candidate in the
explanation of emergent phenomena---phenomena that only occur in sufficiently
large systems. The dimensionless parameter that indicates the importance of the
magnetic energy is the number of electrons times the classical electron radius
divided by the size of the system. The number of electrons involved are only
the electrons at the Fermi surface; electrons with lower energy cannot
contribute to current density and thus not to the magnetic field.
  The conventional understanding of superconductivity has always been
problematic and no really reductionistic derivation exists. The idea that the
inductive inertia, due to magnetism, is important in the explanation of
superconductivity was first advanced by Frenkel and later brought up by Welker
before it was prematurely discarded. So were theories involving Wigner
crystallization. We speculate that the answer requires the combination of a
Wigner lattice and the Darwin interaction. We point out that the Darwin
interaction can be shown to have the right order of magnitude to explain the
energy scales involved in normal superconductors. The London magnetic moment of
rotating superconductors and the Meissner effect and their connection are
discussed next. The London moment is shown to indicate that the number of
electrons involved in the superconducting condensate is such that the Darwin
interaction cannot be neglected.


title: Fibrations as Eilenberg-Moore algebras

abstract:
  We give an elementary exposition of some fundamental facts about fibered (or
rather opfibered) categories, in terms of monads and 2-categories. The account
avoids any mention of category-valued functors and pseudofunctors.


title: Parametric Center-Focus Problem for Abel Equation

abstract:
  The Abel differential equation $y'=p(x)y^3 + q(x) y^2$ with meromorphic
coefficients $p,q$ is said to have a center on $[a,b]$ if all its solutions,
with the initial value $y(a)$ small enough, satisfy the condition $y(a)=y(b)$.
The problem of giving conditions on $(p,q,a,b)$ implying a center for the Abel
equation is analogous to the classical Poincar\'e Center-Focus problem for
plane vector fields.
  Following [3,4,8,9] we say that Abel equation has a "parametric center" if
for each $\varepsilon \in \mathbb C$ the equation $y'=p(x)y^3 + \varepsilon
q(x) y^2$ has a center. In the present paper we use recent results of [15,6} to
show show that for a polynomial Abel equation parametric center implies strong
"composition" restriction on $p$ and $q$. In particular, we show that for $\deg
p,q \leq 10$ parametric center is equivalent to the so-called "Composition
Condition" (CC) on $p,q$.
  Second, we study trigonometric Abel equation, and provide a series of
examples, generalizing a recent remarkable example given in [8], where certain
moments of $p,q$ vanish while (CC) is violated.


title: Large Deflection of Cantilever Rod Pulled by Cable

abstract:
  The article discusses six problems which can arise in the determination of
the equilibrium configuration of an elastic cantilever rod pulled by an
inextensible cable. The discussions are illustrated with graphs of equilibrium
shapes and tables providing some reference numerical values.


title: Intent Models for Contextualising and Diversifying Query Suggestions

abstract:
  The query suggestion or auto-completion mechanisms help users to type less
while interacting with a search engine. A basic approach that ranks suggestions
according to their frequency in the query logs is suboptimal. Firstly, many
candidate queries with the same prefix can be removed as redundant. Secondly,
the suggestions can also be personalised based on the user's context. These two
directions to improve the aforementioned mechanisms' quality can be in
opposition: while the latter aims to promote suggestions that address search
intents that a user is likely to have, the former aims to diversify the
suggestions to cover as many intents as possible. We introduce a
contextualisation framework that utilises a short-term context using the user's
behaviour within the current search session, such as the previous query, the
documents examined, and the candidate query suggestions that the user has
discarded. This short-term context is used to contextualise and diversify the
ranking of query suggestions, by modelling the user's information need as a
mixture of intent-specific user models. The evaluation is performed offline on
a set of approximately 1.0M test user sessions. Our results suggest that the
proposed approach significantly improves query suggestions compared to the
baseline approach.


title: Quantum Monte Carlo study of strongly interacting Fermi gases

abstract:
  In recent years Quantum Monte Carlo techniques provided to be a valuable tool
to study strongly interacting Fermi gases at zero temperature. We have used QMC
methods to investigate several properties of the two-components Fermi gas at
unitarity and in the BCS-BEC crossover, both with equal and unequal masses
corresponding to the $Li-K$ Fermi mixture. In this paper we present several
recent QMC results, including the energy at zero and finite effective range,
the contact parameter and the static structure factor, which, at low momentum,
depends strongly on the phonons in the unitary Fermi gas.


title: Max-Min Distance Nonnegative Matrix Factorization

abstract:
  Nonnegative Matrix Factorization (NMF) has been a popular representation
method for pattern classification problem. It tries to decompose a nonnegative
matrix of data samples as the product of a nonnegative basic matrix and a
nonnegative coefficient matrix, and the coefficient matrix is used as the new
representation. However, traditional NMF methods ignore the class labels of the
data samples. In this paper, we proposed a supervised novel NMF algorithm to
improve the discriminative ability of the new representation. Using the class
labels, we separate all the data sample pairs into within-class pairs and
between-class pairs. To improve the discriminate ability of the new NMF
representations, we hope that the maximum distance of the within-class pairs in
the new NMF space could be minimized, while the minimum distance of the
between-class pairs pairs could be maximized. With this criterion, we construct
an objective function and optimize it with regard to basic and coefficient
matrices and slack variables alternatively, resulting in a iterative algorithm.


title:
Velocity filtration and temperature inversion in a system with
  long-range interactions

abstract:
  Temperature inversion due to velocity filtration, a mechanism originally
proposed to explain the heating of the solar corona, is demonstrated to occur
also in a simple paradigmatic model with long-range interactions, the
Hamiltonian mean-field model. Using molecular dynamics simulations, we show
that when the system settles into an inhomogeneous quasi-stationary state in
which the velocity distribution has suprathermal tails, the temperature and
density profiles are anticorrelated: denser parts of the system are colder than
dilute ones. We argue that this may be a generic property of long-range
interacting systems.


title:
Action principle for cellular automata and the linearity of quantum
  mechanics

abstract:
  We introduce an action principle for a class of integer valued cellular
automata and obtain Hamiltonian equations of motion. Employing sampling theory,
these discrete deterministic equations are invertibly mapped on continuum
equations for a set of bandwidth limited harmonic oscillators, which encode the
Schr\"odinger equation. Thus, the linearity of quantum mechanics is related to
the action principle of such cellular automata and its conservation laws to
discrete ones.

categories: quant-ph math-ph math.MP physics.comp-ph


title:
Unraveling orbital hybridization of triplet emitters at the
  metal-organic interface

abstract:
  We have investigated the structural and electronic properties of
phosphorescent planar platinum(II) complexes at the interface of Au(111) with
submolecular resolution using combined scanning tunneling microscopy and
spectroscopy as well as density functional theory. Our analysis shows that
molecule-substrate coupling and lateral intermolecular interactions are weak.
While the ligand orbitals remain essentially unchanged upon contact to the
substrate, we found modified electronic behavior at the Pt atom due to local
hybridization and charge transfer to the substrate. Thus, this novel class of
phosphorescent molecules exhibits well-defined and tunable interaction with its
local environment.


title: On the dynamics of a family of renormalization transformations

abstract:
  We study the family of renormalization transformations of the generalized
$d$--dimensional diamond hierarchical Potts model in statistical mechanic and
prove that their Julia sets and non-escaping loci are always connected, where
$d\geq 2$. In particular, we prove that their Julia sets can never be a
Sierpi\'{n}ski carpet if the parameter is real. We show that the Julia set is a
quasicircle if and only if the parameter lies in the unbounded capture domain
of these models. Moreover, the asymptotic formula of the Hausdorff dimension of
the Julia set is calculated as the parameter tends to infinity.


title: On cubic hypersurfaces with vanishing hessian

abstract:
  If $X = V(f) \subset \mathbb P^N$ is a reduced complex hypersurface, the
hessian of $f$ (or by abusing the terminology the hessian of $X$) is the
determinant of the matrix of the second derivatives of the form $f$, that is
the determinant of the hessian matrix of $f$. Hypersurfaces with vanishing
hessian were studied systematically for the first time in the fundamental paper
[GN], where Gordan and M. Noether analyze Hesse's claims in [Hesse1, Hesse2]
according to which these hypersurfaces are necessarily cones. Of course cones
have vanishing hessian.
  Clearly the claim is true if deg(X)=2 so that the first relevant case for the
problem is that of cubic hypersurfaces. One immediately sees that $V(x_0x_3^2 +
x_1x_3x_4 + x_2x_4^2)\subset \mathbb P^4$ is a cubic hypersurface with
vanishing hessian but not a cone (for example one could check that the first
partial derivatives of the equation are linearly independent). As firstly
pointed out in [GN], the claim is true for $N\leq 3$ and in general false for
every $N\geq 4$.
  Here we prove that for $N\leq 6$ an irreducible cubic hypersurface with
vanishing hessian in $\mathbb P^N$ is either a cone or a scroll in linear
spaces tangent to the dual of the image of the polar map of the hypersurface.
We also provide canonical forms and a projective characterization of {\it
Special Perazzo Cubic Hypersurfaces}, which, a posteriori, exhaust the class of
cubic hypersurfaces with vanishing hessian, not cones, for $N\leq 6$. Finally
we show by pertinent examples the technical difficulties arising for $N\geq 7$.


title:
A Refinement of the Schr\"odinger Equation Involving Dissipation of
  Waves in the Phase Space

abstract:
  We give an example of a mathematical model describing quantum mechanical
processes interacting with medium. As a model, we consider the process of heat
scattering of a wave function defined on the phase space. We consider the case
when the heat diffusion takes place only with respect to momenta. We state and
study the corresponding modified Kramers equation for this process. We consider
the consequent approximations to this equation in powers of the quantity
inverse to the medium resistance per unit of mass of the particle in the
process. The approximations are constructed similarly to statistical physics,
where from the usual Kramers equation for the evolution of probability density
of the Brownian motion of a particle in the phase space, one deduces an
approximate description of this process by the Fokker--Planck equation for the
density of probability distribution in the configuration space. We prove that
the zero (invertible) approximation to our model with respect to the large
parameter of the medium resistance, yields the usual quantum mechanical
description by the Schr\"odinger equation with the standard Hamilton operator.
We deduce the next approximation to the model with respect to the negative
power of the medium resistance coefficient. As a result we obtain the modified
Schr\"odinger equation taking into account dissipation of the process in the
initial model.


title: Effects of Li doping on H-diffusion in MgH$_2$: a first-principles study

abstract:
  The effects of Li doping in MgH$_2$ on H-diffusion process are investigated,
using first-principles calculations. We have identified two key effects: (1)
The concentration of H vacancy in the $+1$ charge state (V$_H^{+1}$) can
increase by several orders of magnitude upon Li doping, which significantly
increases the vacancy mediated H diffusion rate. It is caused by the preferred
charge states of substitutional Li in the $-1$ state (Li$_{Mg}^{-1}$) and of
interstitial Li in the $+1$ state (Li$_i^{+1}$), which indirectly reduce the
formation energy of V$_H^{+1}$ by up to 0.39 eV depending on the position of
Fermi energy. (2) The interaction between V$_H^{+1}$ and Li$_{Mg}^{-1}$ is
found to be attractive with a binding energy of 0.55 eV, which immobilizes the
V$_H^{+1}$ next to Li$_{Mg}^{-1}$ at high Li doping concentration. As a result,
the competition between these two effects leads to large enhancement of H
diffusion at low Li doping concentration due to the increased H-vacancy
concentration, but only limited enhancement at high Li concentration due to the
immobilization of H vacancies by too many Li.


title:
Non-Geometric Fluxes, Quasi-Hopf Twist Deformations and Nonassociative
  Quantum Mechanics

abstract:
  We analyse the symmetries underlying nonassociative deformations of geometry
in non-geometric R-flux compactifications which arise via T-duality from closed
strings with constant geometric fluxes. Starting from the non-abelian Lie
algebra of translations and Bopp shifts in phase space, together with a
suitable cochain twist, we construct the quasi-Hopf algebra of symmetries that
deforms the algebra of functions and the exterior differential calculus in the
phase space description of nonassociative R-space. In this setting
nonassociativity is characterised by the associator 3-cocycle which controls
non-coassociativity of the quasi-Hopf algebra. We use abelian 2-cocycle twists
to construct maps between the dynamical nonassociative star product and a
family of associative star products parametrized by constant momentum surfaces
in phase space. We define a suitable integration on these nonassociative spaces
and find that the usual cyclicity of associative noncommutative deformations is
replaced by weaker notions of 2-cyclicity and 3-cyclicity. Using this star
product quantization on phase space together with 3-cyclicity, we formulate a
consistent version of nonassociative quantum mechanics, in which we calculate
the expectation values of area and volume operators, and find coarse-graining
of the string background due to the R-flux.


title:
Network inference in matrix-variate Gaussian models with non-independent
  noise

abstract:
  Inferring a graphical model or network from observational data from a large
number of variables is a well studied problem in machine learning and
computational statistics. In this paper we consider a version of this problem
that is relevant to the analysis of multiple phenotypes collected in genetic
studies. In such datasets we expect correlations between phenotypes and between
individuals. We model observations as a sum of two matrix normal variates such
that the joint covariance function is a sum of Kronecker products. This model,
which generalizes the Graphical Lasso, assumes observations are correlated due
to known genetic relationships and corrupted with non-independent noise. We
have developed a computationally efficient EM algorithm to fit this model. On
simulated datasets we illustrate substantially improved performance in network
reconstruction by allowing for a general noise distribution.


title:
Modeling and analysis of a phase field system for damage and phase
  separation processes in solids

abstract:
  In this work, we analytically investigate a multi-component system for
describing phase separation and damage processes in solids. The model consists
of a parabolic diffusion equation of fourth order for the concentration coupled
with an elliptic system with material dependent coefficients for the strain
tensor and a doubly nonlinear differential inclusion for the damage function.
The main aim of this paper is to show existence of weak solutions for the
introduced model, where, in contrast to existing damage models in the
literature, different elastic properties of damaged and undamaged material are
regarded. To prove existence of weak solutions for the introduced model, we
start with an approximation system. Then, by passing to the limit, existence
results of weak solutions for the proposed model are obtained via suitable
variational techniques.


title:
Measurability of Semimartingale Characteristics with Respect to the
  Probability Law

abstract:
  Given a c\`adl\`ag process $X$ on a filtered measurable space, we construct a
version of its semimartingale characteristics which is measurable with respect
to the underlying probability law. More precisely, let $\mathfrak{P}_{sem}$ be
the set of all probability measures $P$ under which $X$ is a semimartingale. We
construct processes $(B^P,C,\nu^P)$ which are jointly measurable in time,
space, and the probability law $P$, and are versions of the semimartingale
characteristics of $X$ under $P$ for each $P\in\mathfrak{P}_{sem}$. This result
gives a general and unifying answer to measurability questions that arise in
the context of quasi-sure analysis and stochastic control under the weak
formulation.


title: dS/CFT at uniform energy density and a de Sitter "bluewall"

abstract:
  We describe a class of spacetimes that are asymptotically de Sitter in the
Poincare slicing. Assuming that a dS/CFT correspondence exists, we argue that
these are gravity duals to a CFT on a circle leading to uniform energy-momentum
density, and are equivalent to an analytic continuation of the Euclidean AdS
black brane. These are solutions with a complex parameter which then gives a
real energy-momentum density. We also discuss a related solution with the
parameter continued to a real number, which we refer to as a de Sitter
"bluewall". This spacetime has two asymptotic de Sitter universes and Cauchy
horizons cloaking timelike singularities. We argue that the Cauchy horizons
give rise to a blue-shift instability.


title:
Progress Towards Completion of the MICE Demonstration of Muon Ionization
  Cooling

abstract:
  The Muon Ionization Cooling Experiment (MICE) at the Rutherford Appleton
Laboratory aims to demonstrate $\approx$ 10% ionization cooling of a muon beam
by its interaction with low-Z absorber materials followed by restoration of
longitudinal momentum in RF linacs. MICE Step IV, including the first LH2 or
LiH absorber cell sandwiched between two particle tracking spectrometers, is
the collaboration's near-term goal. Two large superconducting spectrometer
solenoids and one focus coil solenoid will provide a magnetic field of
$\approx$4 T in the tracker and absorber-cell volumes. The status of these
components is described, as well as progress towards Steps V and VI, including
the eight RF cavities to provide the required 8 MV/m gradient in a strong
magnetic field; this entails an RF drive system to deliver 2 MW, 1 ms pulses of
201 MHz frequency at 1 Hz repetition rate, the distribution network to deliver
1 MW to each cavity with correct RF phasing, diagnostics to determine the
gradient and the muon transit phase, and development of the large-diameter
magnets required for the linacs.


title: Multi-loop Integrand Reduction via Multivariate Polynomial Division

abstract:
  We present recent developments on the topic of the integrand reduction of
scattering amplitudes. Integrand-level methods allow to express an amplitude as
a linear combination of Master Integrals, by performing operations on the
corresponding integrands. This approach has already been successfully applied
and automated at one loop, and recently extended to higher loops. We describe a
coherent framework based on simple concepts of algebraic geometry, such as
multivariate polynomial division, which can be used in order to obtain the
integrand decomposition of any amplitude at any loop order. In the one-loop
case, we discuss an improved reduction algorithm, based on the application of
the Laurent series expansion to the integrands, which has been implemented in
the semi-numerical library Ninja. At two loops, we present the reduction of
five-point amplitudes in N=4 SYM, with a unitarity-based construction of the
integrand. We also describe the multi-loop divide-and-conquer approach, which
can always be used to find the integrand decomposition of any Feynman graph,
regardless of the form and the complexity of the integrand, with purely
algebraic operations.


title:
Bounding the Higgs width at the LHC: complementary results from $H \to
  WW$

abstract:
  We investigate the potential of the process $gg \to H \to WW$ to provide
bounds on the Higgs width. Recent studies using off-shell $H\rightarrow ZZ$
events have shown that Run 1 LHC data can constrain the Higgs width, $\Gamma_H
< (25-45) \Gamma_{H}^{\rm SM}$. Using 20 fb-1 of 8 TeV ATLAS data, we estimate
a bound on the Higgs boson width from the WW channel between $\Gamma_H <
(100-500) \Gamma_H^{SM}$. The large spread in limits is due to the range of
cuts applied in the existing experimental analysis. The stricter cuts designed
to search for the on-shell Higgs boson limit the potential number of off-shell
events, weakening the constraints. As some of the cuts are lifted the bounds
improve. We show that there is potential in the high transverse mass region to
produce upper bounds of the order of $(25-50) \Gamma_H^{SM}$, depending
strongly on the level of systematic uncertainty that can be obtained. Thus, if
these systematics can be controlled, a constraint on the Higgs boson width from
the $H \to WW$ decay mode can complement a corresponding limit from $H \to ZZ$.


title: Detection and prevention of botnets and malware in an enterprise network

abstract:
  One of the most significant threats faced by enterprise networks today is
from Bots. A Bot is a program that operates as an agent for a user and runs
automated tasks over the internet, at a much higher rate than would be possible
for a human alone. A collection of Bots in a network, used for malicious
purposes is referred to as a Botnet. Bot attacks can range from localized
attacks like key-logging to network intensive attacks like Distributed Denial
of Service (DDoS). In this paper, we suggest a novel approach that can detect
and combat Bots. The proposed solution adopts a two pronged strategy which we
have classified into the standalone algorithm and the network algorithm. The
standalone algorithm runs independently on each node of the network. It
monitors the active processes on the node and tries to identify Bot processes
using parameters such as response time and output to input traffic ratio. If a
suspicious process has been identified the network algorithm is triggered. The
network algorithm will then analyze conversations to and from the hosts of the
network using the transport layer flow records. It then tries to deduce the Bot
pattern as well as Bot signatures which can subsequently be used by the
standalone algorithm to thwart Bot processes at their very onset.


title:
Selective control of edge-channel trajectories by scanning gate
  microscopy

abstract:
  Electronic Mach-Zehnder interferometers in the Quantum Hall (QH) regime are
currently discussed for the realization of quantum information schemes. A
recently proposed device architecture employs interference between two
co-propagating edge channels. Here we demonstrate the precise control of
individual edge-channel trajectories in quantum point contact devices in the QH
regime. The biased tip of an atomic force microscope is used as a moveable
local gate to pilot individual edge channels. Our results are discussed in
light of the implementation of multi-edge interferometers.


title: Reply to Comment on "Acoustics of tachyon Fermi gas"

abstract:
  In a paper appearing in this issue of Physical Review D, Burmistrov raises
some critical comments on the thermodynamics of a cold tachyon Fermi gas [E.
Trojan and G. V. Vlasov, Phys. Rev. D 83, 124013 (2011)]. However, apart from
any possible theoretical speculation, there are the basic physical principles
to test the theory.


title:
Synchronization and Noise: A Mechanism for Regularization in Neural
  Systems

abstract:
  To learn and reason in the presence of uncertainty, the brain must be capable
of imposing some form of regularization. Here we suggest, through theoretical
and computational arguments, that the combination of noise with synchronization
provides a plausible mechanism for regularization in the nervous system. The
functional role of regularization is considered in a general context in which
coupled computational systems receive inputs corrupted by correlated noise.
Noise on the inputs is shown to impose regularization, and when synchronization
upstream induces time-varying correlations across noise variables, the degree
of regularization can be calibrated over time. The proposed mechanism is
explored first in the context of a simple associative learning problem, and
then in the context of a hierarchical sensory coding task. The resulting
qualitative behavior coincides with experimental data from visual cortex.


title: Interfacing GoSam with Monte Carlo Event Generators

abstract:
  In this talk the most recent results obtained by interfacing GoSam with
external Monte Carlo event generators are presented and summarized. In the last
year the automatic one-loop amplitude generator GoSam has been used for the
computation of several processes relevant for the LHC physics program. In the
first part of the talk the latest results are summarized and the status of the
interfaces to several external Monte Carlo programs, based on the
Binoth-Les-Houches-Accord, is reported. The second part is dedicated to two
selected computations. One concerning the associated production of a Higgs and
a vector boson in association with 0 and 1 jet computed with GoSam+Powheg, and
one focusing on the analysis of the forward-backward asymmetry in the
production of top quark pairs using 0 and 1 jet merged samples with
GoSam+Sherpa. Finally some recent results on Beyond-Standard-Model physics are
also presented.


title:
Signature of Electron-magnon Umklapp Scattering in L10 FePt probed by
  Thermoelectric Measurements

abstract:
  We report unconventional thermoelectric power (Seebeck coefficient, S) in L10
structured FePt films. The temperature dependence of S can be well fitted by a
phenomenological expression consisting of electron diffusion and magnon-drag
contributions. Interestingly, the magnon drag coefficient carries an opposite
sign to that of electron diffusion, revealing a dominant contribution from the
elusive electron-magnon Umklapp scattering. DFT calculations identify several
bands crossing the Brillouin zone boundaries, facilitating the Umklapp process.
The large spin-orbit coupling in FePt results in strong mixing of majority and
minority spins among some of those bands, greatly enhancing the electron-magnon
scattering.


title: Hydrogen storage with titanium-functionalized graphene

abstract:
  We report on hydrogen adsorption and desorption on titanium-covered graphene
in order to test theoretical proposals to use of graphene functionalized with
metal atoms for hydrogen storage. At room temperature titanium islands grow
with an average diameter of about 10 nm. Samples were then loaded with
hydrogen, and its desorption kinetics was studied by thermal desorption
spectroscopy. We observe the desorption of hydrogen in the temperature range
between 400K and 700 K. Our results demonstrate the stability of hydrogen
binding at room temperature and show that hydrogen desorbs at moderate
temperatures in line with what required for practical hydrogen-storage
applications.


title:
Non-existence and Non-uniqueness for Multidimensional Sticky Particle
  Systems

abstract:
  The paper is concerned with sticky weak solutions to the equations of
pressureless gases in two or more space dimensions. Various initial data are
constructed, showing that the Cauchy problem can have (i) two distinct sticky
solutions, or (ii) no sticky solution, not even locally in time. In both cases
the initial density is smooth with compact support, while the initial velocity
field is continuous.


title: The Chemical Instability of Na2IrO3 in Air

abstract:
  We report that Na2IrO3, which has a layered honeycomb iridium oxide
sublattice interleaved by Na planes, decomposes in laboratory air while
maintaining the same basic crystal structure. The decomposition reaction was
monitored by time-dependent powder x-ray diffraction under different ambient
atmospheres, through which it was determined that it occurs only in the
simultaneous presence of both CO2 and H2O. A hydrated sodium carbonate is the
primary decomposition product along with altered Na2IrO3. The diffraction
signature of the altered Na2IrO3 is quite similar to that of the pristine
material, which makes the detection of decomposition difficult in a sample
handled under ordinary laboratory conditions. The decomposed samples show a
significantly decreased magnetic susceptibility and the disappearance of the
low temperature antiferromagnetic transition considered to be characteristic of
the phase. Samples that have never been exposed to air after synthesis display
a previously unreported magnetic transition at 5K.


title:
PyFR: An Open Source Framework for Solving Advection-Diffusion Type
  Problems on Streaming Architectures using the Flux Reconstruction Approach

abstract:
  High-order numerical methods for unstructured grids combine the superior
accuracy of high-order spectral or finite difference methods with the geometric
flexibility of low-order finite volume or finite element schemes. The Flux
Reconstruction (FR) approach unifies various high-order schemes for
unstructured grids within a single framework. Additionally, the FR approach
exhibits a significant degree of element locality, and is thus able to run
efficiently on modern streaming architectures, such as Graphical Processing
Units (GPUs). The aforementioned properties of FR mean it offers a promising
route to performing affordable, and hence industrially relevant,
scale-resolving simulations of hitherto intractable unsteady flows within the
vicinity of real-world engineering geometries. In this paper we present PyFR,
an open-source Python based framework for solving advection-diffusion type
problems on streaming architectures using the FR approach. The framework is
designed to solve a range of governing systems on mixed unstructured grids
containing various element types. It is also designed to target a range of
hardware platforms via use of an in-built domain specific language based on the
Mako templating engine. The current release of PyFR is able to solve the
compressible Euler and Navier-Stokes equations on grids of quadrilateral and
triangular elements in two dimensions, and hexahedral elements in three
dimensions, targeting clusters of CPUs, and NVIDIA GPUs. Results are presented
for various benchmark flow problems, single-node performance is discussed, and
scalability of the code is demonstrated on up to 104 NVIDIA M2090 GPUs. The
software is freely available under a 3-Clause New Style BSD license (see
www.pyfr.org).


title: Excision, descent, and singularity in algebraic $K$-theory

abstract:
  Algebraic $K$-theory is a homology theory that behaves very well on
sufficiently nice objects such as stable $C^*$-algebras or smooth algebraic
varieties, and very badly in singular situations. This survey explains how to
exploit this to detect singularity phenomena using $K$-theory and cyclic
homology.


title:
The Geometry of Trifocal Curves with Applications in Architecture, Urban
  and Spatial Planning

abstract:
  In this paper we consider historical genesis of trifocal curve as an optimal
curve for solving the Fermat's problem (minimizing the sum of distance of one
point to three given points in the plane). Trifocal curves are basic plane
geometric forms which appear in location problems. We also analyze algebraic
equation of these curves and some of their applications in architecture,
urbanism and spatial planning. The area and perimeter of trifocal curves are
calculated using a Java application. The Java applet is developed for
determining numerical value for the Fermat-Torricelli-Weber point and optimal
curve with three foci, when starting points are given on an urban map. We also
present an application of trifocal curves through the analysis of one specific
solution in South Stream gas pipeline project.


title:
The ACS survey of globular clusters. XIII. Photometric calibration in
  comparison with Stetson standards

abstract:
  In this study we compare the photometric data of 34 Milky Way globular
clusters, observed within the ACS Treasury Program (PI: Ata Sarajedini) with
the corresponding ground-based data, provided by the Photometric Standard Field
Catalogs of Stetson (2000, 2005). We focus on the transformation between the
HST/ACS F606W to V-band and F814W to I-band only. The goal is to assess the
validity of the filter transformation equations by Sirianni et al.(2005) with
respect to their dependence on metallicity, Horizontal Branch morphology, mass
and integrated (V-I) colour of the various globular clusters. Such a dependence
is expected due to the fact that the transformation equations are based on the
observations of only one globular cluster, i.e., NGC 2419. Surprisingly, the
correlation between offset and metallicity is found to be weak, with a low
level significance. The correlation between offset and Horizontal Branch
structure, as well as total cluster mass is still weaker. Based on the
available data we do not find the photometric offset to be linked to multiple
stellar populations, e.g., as found in NGC 0288, NGC 1851, and NGC 5139. The
results of this study show that there are small systematic offsets between the
transformed ACS- and observed ground based photometry, and that these are only
weakly correlated, if at all, with various cluster parameters and their
underlying stellar populations. As a result, investigators wishing to transform
globular cluster photometry from the Sirianni et al.(2005) ground-based V, I
system onto the Stetson (2000) system simply need to add 0.040 (+/-0.012) to
the V-band magnitudes and 0.047 (+/-0.011) to the I-band magnitudes. This in
turn means that the transformed ACS (V-I) colours match the ground-based values
from Stetson (2000) to within ~0.01 mag.


title: Gerstenhaber and Batalin-Vilkovisky structures on modules over operads

abstract:
  In this article, we show under what additional ingredients a comp (or
opposite) module over an operad with multiplication can be given the structure
of a cyclic k-module and how the underlying simplicial homology gives rise to a
Batalin-Vilkovisky module over the cohomology of the operad. In particular, one
obtains a generalised Lie derivative and a generalised (cyclic) cap product
that obey a Cartan-Rinehart homotopy formula, and hence yield the structure of
a noncommutative differential calculus in the sense of Nest, Tamarkin, Tsygan,
and others. Examples include the calculi known for the Hochschild theory of
associative algebras, for Poisson structures, but above all the calculus for
general left Hopf algebroids with respect to general coefficients (in which the
classical calculus of vector fields and differential forms is contained).


title:
Shell galaxies: kinematical signature of shells, satellite galaxy
  disruption and dynamical friction

abstract:
  Stellar shells observed in many giant elliptical and lenticular as well as a
few spiral and dwarf galaxies presumably result from radial minor mergers of
galaxies. We show that the line-of-sight velocity distribution of the shells
has a quadruple-peaked shape. We found simple analytical expressions that
connect the positions of the four peaks of the line profile with the mass
distribution of the galaxy, namely, the circular velocity at the given shell
radius and the propagation velocity of the shell. The analytical expressions
were applied to a test-particle simulation of a radial minor merger, and the
potential of the simulated host galaxy was successfully recovered. Shell
kinematics can thus become an independent tool to determine the content and
distribution of dark matter in shell galaxies up to ~100 kpc from the center of
the host galaxy. Moreover we investigate the dynamical friction and gradual
disruption of the cannibalized galaxy during the shell formation in the
framework of a simulation with test particles. The coupling of both effects can
considerably redistribute positions and luminosities of shells. Neglecting them
can lead to significant errors in attempts to date the merger in observed shell
galaxies.


title:
Collision Avoidance in Next-generation Fiber Positioner Robotic System
  for Large Survey Spectrograph

abstract:
  Some of the next generation massive spectroscopic survey projects, such as
DESI and PFS, plan to use thousands of fiber positioner robots packed at a
focal plane to quickly move in parallel the fiber-ends from the previous to the
next target points. The most direct trajectories are prone to collision that
could damage the robots and impact the survey operation. We thus present here a
motion planning method based on a novel decentralized navigation function for
collision-free coordination of fiber positioners. The navigation function takes
into account the configuration of positioners as well as the actuator
constraints. We provide details for the proof of convergence and collision
avoidance. Decentralization results in linear complexity for the motion
planning as well as dependency of motion duration with respect to the number of
positioners. Therefore the coordination method is scalable for large-scale
spectrograph robots. The short in-motion duration of positioner robots (~2.5
seconds using typical actuator constraints), will thus allow the time dedicated
for observation to be maximized.


title:
What is the best risk measure in practice? A comparison of standard
  measures

abstract:
  Expected Shortfall (ES) has been widely accepted as a risk measure that is
conceptually superior to Value-at-Risk (VaR). At the same time, however, it has
been criticised for issues relating to backtesting. In particular, ES has been
found not to be elicitable which means that backtesting for ES is less
straightforward than, e.g., backtesting for VaR. Expectiles have been suggested
as potentially better alternatives to both ES and VaR. In this paper, we
revisit commonly accepted desirable properties of risk measures like coherence,
comonotonic additivity, robustness and elicitability. We check VaR, ES and
Expectiles with regard to whether or not they enjoy these properties, with
particular emphasis on Expectiles. We also consider their impact on capital
allocation, an important issue in risk management. We find that, despite the
caveats that apply to the estimation and backtesting of ES, it can be
considered a good risk measure. As a consequence, there is no sufficient
evidence to justify an all-inclusive replacement of ES by Expectiles in
applications. For backtesting ES, we propose an empirical approach that
consists in replacing ES by a set of four quantiles, which should allow to make
use of backtesting methods for VaR.
  Keywords: Backtesting; capital allocation; coherence; diversification;
elicitability; expected shortfall; expectile; forecasts; probability integral
transform (PIT); risk measure; risk management; robustness; value-at-risk


title: Vortex-crystal pattern in an anti-artificial spin ice system

abstract:
  We have proposed in this work an original system composed by anti-dots
nanopatterned in a ferromagnetic thin film, mimicking negatively the structure
of an articial spin ice. In the hysteresis loop we notice the emergency of an
anisotropy in the magnetization saturation and in the micromagnetic
simulations, in the beginning of the hysteresis loop (relaxation), the
formation of a vortex crystal array with vortices in diferent positions
possessing random polarization and chirality. The crystal of vortices in this
electrically connected sample could be most eficient than those observed in
non-connected nanodiscs for current-driven or magnetic vortices switching by
electric currents.


title:
Hysteresis behavior of the anisotropic quantum Heisenberg model driven
  by periodic magnetic field

abstract:
  Dynamic behavior of a quantum Heisenberg ferromagnet in the presence of a
periodically oscillating magnetic field has been analyzed by means of the
effective field theory with two spin cluster. The dynamic equation of motion
has been constructed with the help of a Glauber type stochastic process and
solved for a simple cubic lattice. After the phase diagrams given, the behavior
of the hysteresis loop area, coercive field and remanent magnetization with the
anisotropy in the exchange interaction has been investigated in detail.
Especially, by comparing of the magnitudes of the hysteresis loop area in the
high anisotropy limit (i.e. Ising model) and low anisotropy limit (i.e.
isotropic Heisenberg model), detailed description of the hysteresis loop area
with the anisotropy in the exchange interaction given. Some interesting
features have been obtained about this behavior as well as in phase diagrams
such as tricritical points.


title:
The optical rebrightening of GRB100814A: an interplay of forward and
  reverse shocks?

abstract:
  We present a wide dataset of gamma-ray, X-ray, UVOIR, and radio observations
of the Swift GRB100814A. At the end of the slow decline phase of the X-ray and
optical afterglow, this burst shows a sudden and prominent rebrightening in the
optical band only, followed by a fast decay in both bands. The optical
rebrightening also shows chromatic evolution. Such a puzzling behaviour cannot
be explained by a single component model. We discuss other possible
interpretations, and we find that a model that incorporates a long-lived
reverse shock and forward shock fits the temporal and spectral properties of
GRB100814A the best.


title:
A new CVD Diamond Mosaic-Detector for (n,$\alpha$) Cross-Section
  Measurements at the n\_TOF Experiment at CERN

abstract:
  At the n\_TOF experiment at CERN a dedicated single-crystal chemical vapor
deposition (sCVD) Diamond Mosaic-Detector has been developed for (n,$\alpha$)
cross-section measurements. The detector, characterized by an excellent time
and energy resolution, consists of an array of 9 sCVD diamond diodes. The
detector has been characterized and a cross-section measurement has been
performed for the $^{59}$Ni(n,$\alpha$)$^{56}$Fe reaction in 2012. The
characteristics of the detector, its performance and the promising preliminary
results of the experiment are presented.


title:
Direct Measurement of Interstellar Extinction Toward Young Stars Using
  Atomic Hydrogen Lyman-$\alpha$ Absorption

abstract:
  Interstellar reddening corrections are necessary to reconstruct the intrinsic
spectral energy distributions (SEDs) of accreting protostellar systems. The
stellar SED determines the heating and chemical processes that can occur in
circumstellar disks. Measurement of neutral hydrogen absorption against broad
Lyman-$\alpha$ emission profiles in young stars can be used to obtain the total
H I column density (N(H I)) along the line of sight. We measure N(H I) with new
and archival ultraviolet observations from the Hubble Space Telescope ($HST$)
of 31 classical T Tauri and Herbig Ae/Be stars. The H I column densities range
from log$_{10}$(N(H I)) $\approx 19.6 - 21.1$, with corresponding visual
extinctions of A$_{V}$ $= 0.02 - 0.72$ mag, assuming an R$_{V}$ of 3.1. We find
that the majority of the H I absorption along the line of sight likely comes
from interstellar rather than circumstellar material. Extinctions derived from
new $HST$ blue-optical spectral analyses, previous IR and optical measurements,
and new X-ray column densities on average overestimate the interstellar
extinction toward young stars compared to the N(H I) values by $\sim 0.6$ mag.
We discuss possible explanations for this discrepancy in the context of a
protoplanetary disk geometry.


title: Numerical simulation of a solitonic gas in KdV and KdV-BBM equations

abstract:
  The collective behaviour of soliton ensembles (i.e. the solitonic gas) is
studied using the methods of the direct numerical simulation. Traditionally
this problem was addressed in the context of integrable models such as the
celebrated KdV equation. We extend this analysis to non-integrable KdV-BBM type
models. Some high resolution numerical results are presented in both integrable
and nonintegrable cases. Moreover, the free surface elevation probability
distribution is shown to be quasi-stationary. Finally, we employ the asymptotic
methods along with the Monte-Carlo simulations in order to study quantitatively
the dependence of some important statistical characteristics (such as the
kurtosis and skewness) on the Stokes-Ursell number (which measures the relative
importance of nonlinear effects compared to the dispersion) and also on the
magnitude of the BBM term.


title: Fractional Fokker-Planck equation

abstract:
  This paper deals with the long time behavior of solutions to a "fractional
Fokker-Planck" equation of the form $\partial_t f = I[f] + \text{div}(xf)$
where the operator $I$ stands for a fractional Laplacian. We prove an
exponential in time convergence towards equilibrium in new spaces. Indeed, such
a result was already obtained in a $L^2$ space with a weight prescribed by the
equilibrium in \cite{GI}. We improve this result obtaining the convergence in a
$L^1$ space with a polynomial weight. To do that, we take advantage of the
recent paper \cite{GMM} in which an abstract theory of enlargement of the
functional space of the semigroup decay is developed.


title: A Random Field Model and its Application in Industrial Production

abstract:
  In competitive industries, a reliable yield forecasting is a prime factor to
accurately determine the production costs and therefore ensure profitability.
Indeed, quantifying the risks long before the effective manufacturing process
enables fact-based decision-making. From the development stage, improvement
efforts can be early identified and prioritized. In order to measure the impact
of industrial process fluctuations on the product performances, the
construction of a failure risk probability estimator is presented in this
article. The complex relationship between the process technology and the
product design (non linearities, multi-modal features...) is handled via random
process regression. A random field encodes, for each product configuration, the
available information regarding the risk of non-compliance. After a brief
presentation of the Gaussian model approach, we describe a Bayesian reasoning
avoiding a priori choices of location and scale parameters. The Gaussian
mixture prior, conditioned by measured (or calculated) data, yields a posterior
characterized by a multivariate Student distribution. The probabilistic nature
of the model is then operated to derive a failure risk probability, defined as
a random variable. To do this, our approach is to consider as random all
unknown, inaccessible or fluctuating data. In order to propagate uncertainties,
a fuzzy set approach provides an appropriate framework for the implementation
of a Bayesian model mimicking expert elicitation. The underlying leitmotiv is
to insert minimal a priori information in the failure risk model. The relevancy
of this concept is illustrated with theoretical examples.


title: On Dense Subgroups of Homeo(I)

abstract:
  We prove that a dense subgroup of $\mathrm{Homeo}_{+}(I)$ is not elementary
amenable and (if it is finitely generated) has infinite girth. We also show
that the topological group $\mathrm{Homeo}_{+}(I)$ does not satisfy the
Stability of the Generators Property.


title: On the Complexity of the F5 Gr\"obner basis Algorithm

abstract:
  We study the complexity of Gr\"obner bases computation, in particular in the
generic situation where the variables are in simultaneous Noether position with
respect to the system.
  We give a bound on the number of polynomials of degree $d$ in a Gr\"obner
basis computed by Faug\`ere's $F_5$ algorithm~(Fau02) in this generic case for
the grevlex ordering (which is also a bound on the number of polynomials for a
reduced Gr\"obner basis, independently of the algorithm used). Next, we analyse
more precisely the structure of the polynomials in the Gr\"obner bases with
signatures that $F_5$ computes and use it to bound the complexity of the
algorithm.
  Our estimates show that the version of~$F_5$ we analyse, which uses only
standard Gaussian elimination techniques, outperforms row reduction of the
Macaulay matrix with the best known algorithms for moderate degrees, and even
for degrees up to the thousands if Strassen's multiplication is used. The
degree being fixed, the factor of improvement grows exponentially with the
number of variables.


title:
Spectral analysis of Markov kernels and application to the convergence
  rate of discrete random walks

abstract:
  Let $\{X_n\}_{n\in\N}$ be a Markov chain on a measurable space $\X$ with
transition kernel $P$ and let $V:\X\r[1,+\infty)$. The Markov kernel $P$ is
here considered as a linear bounded operator on the weighted-supremum space
$\cB_V$ associated with $V$. Then the combination of quasi-compactness
arguments with precise analysis of eigen-elements of $P$ allows us to estimate
the geometric rate of convergence $\rho_V(P)$ of $\{X_n\}_{n\in\N}$ to its
invariant probability measure in operator norm on $\cB_V$. A general procedure
to compute $\rho_V(P)$ for discrete Markov random walks with identically
distributed bounded increments is specified.


title: Expected Dimensions of Higher-rank Brill-Noether Loci

abstract:
  In this paper, we prove a new expected dimension formula for certain rank two
Brill-Noether loci with fixed special determinant. This answers a question
asked by Osserman and also leads to a new and much simpler proof of a theorem
of Osserman. Our result generalizes the well-known result by Bertram, Feinberg
and independently Mukai on expected dimension of rank two Brill-Noether loci
with canonical determinant and partially verifies a conjecture (in rank two) of
Grzegorczyk and Newstead on coherent systems.


title: Random Abstract Simplicial Complexes Reduction

abstract:
  Random abstract simplicial complex representation provides a mathematical
description of wireless networks and their topology. In order to reduce the
energy consumption in this type of network, we intend to reduce the number of
network nodes without modifying neither the connectivity nor the coverage of
the network. In this paper, we present a reduction algorithm that lower the
number of points of an abstract simplicial complex in an optimal order while
maintaining its topology. Then, we study the complexity of such an algorithm
for a network simulated by a binomial point process and represented by a
Vietoris-Rips complex.


title: Remarks about the correspondence between $f(R)$ and Brans-Dicke gravity

abstract:
  We discuss the correspondence between metric $f(R)$ gravity and $\omega=0$
Brans-Dicke theory with a potential, by working out an example that reconfirms
this equivalence.


title: Electron Lens as Beam-Beam Wire Compensator in HL-LHC

abstract:
  Current wires are considered for compensation of long-range beam-beam
interactions for the High Luminosity upgrade (HL-LHC) of the Large Hadron
Collider at CERN. In this note, we demonstrate the advantage of using Electron
Lens for this purpose instead of a conventional current-bearing wire.


title: Quantum Communications Based on Quantum Hashing

abstract:
  In this paper we consider an application of the recently proposed quantum
hashing technique for computing Boolean functions in the quantum communication
model. The combination of binary functions on non-binary quantum hash function
is done via polynomial presentation, which we have called a characteristic of a
Boolean function. Based on the characteristic polynomial presentation of
Boolean functions and quantum hashing technique we present a method for
computing Boolean functions in the quantum one-way communication model, where
one of the parties performs his computations and sends a message to the other
party, who must output the result after his part of computations. Some of the
results are also true in a more restricted Simultaneous Message Passing model
with no shared resources, in which communicating parties can interact only via
the referee. We give several examples of Boolean functions whose polynomial
presentations have specific properties allowing for construction of quantum
communication protocols that are provably exponentially better than classical
ones in the simultaneous message passing setting.


title:
A model for the onset of oscillations near the stopping angle in an
  inclined granular flow

abstract:
  We propose an explanation for the onset of oscillations seen in numerical
simulations of dense, inclined flows of inelastic, frictional spheres. It is
based on a phase transition between disordered and ordered collisional states
that may be interrupted by the formation of force chains. Low frequency
oscillations between ordered and disordered states take place over weakly bumpy
bases; higher-frequency oscillations over strongly bumpy bases involve the
formation of particle chains that extend to the base and interrupt the phase
change. The predicted frequency and amplitude of the oscillations induced by
the unstable part of the equation of state are similar to those seen in the
simulations and they depend upon the contact stiffness in the same way. Such
oscillations could be the source of sound produced by flowing sand.


title: From regular modules to von Neumann regular rings via coordinatization

abstract:
  In this paper we establish a very close link (in terms of von Neumann's
coordinatization) between regular modules introduced by Zelmanowitz, on one
hand, and von Neumann regular rings, on the other hand: we prove that the
lattice $\mathcal{L}^{fg}(M)$ of all finitely generated submodules of a
finitely generated regular module $M$, over an arbitrary ring, can be
coordinatized as the lattice of all principal right ideals of some von Neumann
regular ring $S$.


title: Simplicial Homology for Future Cellular Networks

abstract:
  Simplicial homology is a tool that provides a mathematical way to compute the
connectivity and the coverage of a cellular network without any node location
information. In this article, we use simplicial homology in order to not only
compute the topology of a cellular network, but also to discover the clusters
of nodes still with no location information. We propose three algorithms for
the management of future cellular networks. The first one is a frequency
auto-planning algorithm for the self-configuration of future cellular networks.
It aims at minimizing the number of planned frequencies while maximizing the
usage of each one. Then, our energy conservation algorithm falls into the
self-optimization feature of future cellular networks. It optimizes the energy
consumption of the cellular network during off-peak hours while taking into
account both coverage and user traffic. Finally, we present and discuss the
performance of a disaster recovery algorithm using determinantal point
processes to patch coverage holes.


title:
SDSS J074511.56+194926.5: Discovery of a Metal-Rich and Tidally
  Distorted Extremely Low Mass White Dwarf

abstract:
  We present the discovery of an unusual, tidally-distorted extremely low mass
white dwarf (WD) with nearly solar metallicity. Radial velocity measurements
confirm that this is a compact binary with an orbital period of 2.6975 hrs and
a velocity semi-amplitude of K = 108.7 km/s. Analysis of the hydrogen Balmer
lines yields an effective temperature of Teff = 8380 K and a surface gravity of
log g = 6.21 that in turn indicate a mass of M = 0.16 Msol and a cooling age of
4.2 Gyr. In addition, a detailed analysis of the observed metal lines yields
abundances of log Mg/H = -3.90, log Ca/H = -5.80, log Ti/H = -6.10, log Cr/H =
-5.60, and log Fe/H = -4.50, similar to the sun. We see no evidence of a debris
disk from which these metals would be accreted though the possibility cannot
entirely be ruled out. Other potential mechanisms to explain the presence of
heavy elements are discussed. Finally, we expect this system to ultimately
undergo unstable mass transfer and merge to form a ~0.3-0.6 Msol WD in a few
Gyr.


title: Semi-Stochastic Gradient Descent Methods

abstract:
  In this paper we study the problem of minimizing the average of a large
number ($n$) of smooth convex loss functions. We propose a new method, S2GD
(Semi-Stochastic Gradient Descent), which runs for one or several epochs in
each of which a single full gradient and a random number of stochastic
gradients is computed, following a geometric law. The total work needed for the
method to output an $\varepsilon$-accurate solution in expectation, measured in
the number of passes over data, or equivalently, in units equivalent to the
computation of a single gradient of the loss, is
$O((\kappa/n)\log(1/\varepsilon))$, where $\kappa$ is the condition number.
This is achieved by running the method for $O(\log(1/\varepsilon))$ epochs,
with a single gradient evaluation and $O(\kappa)$ stochastic gradient
evaluations in each. The SVRG method of Johnson and Zhang arises as a special
case. If our method is limited to a single epoch only, it needs to evaluate at
most $O((\kappa/\varepsilon)\log(1/\varepsilon))$ stochastic gradients. In
contrast, SVRG requires $O(\kappa/\varepsilon^2)$ stochastic gradients. To
illustrate our theoretical results, S2GD only needs the workload equivalent to
about 2.1 full gradient evaluations to find an $10^{-6}$-accurate solution for
a problem with $n=10^9$ and $\kappa=10^3$.


title:
The time-dependent exchange-correlation functional for a Hubbard dimer:
  quantifying non-adiabatic effect

abstract:
  We address and quantify the role of non-adiabaticity ("memory effects") in
the exchange-correlation (xc) functional of time-dependent density functional
theory (TDDFT) for describing non-linear dynamics of many-body systems.
Time-dependent resonant processes are particularly challenging for available
TDDFT approximations, due to their strong non-linear and non-adiabatic
character. None of the known approximate density functionals are able to cope
with this class of problems in a satisfactory manner. In this work we look at
the prototypical example of the resonant processes by considering Rabi
oscillations within the exactly soluble 2-site Hubbard model. We construct the
exact adiabatic xc functional and show that (i) it does not reproduce correctly
resonant Rabi dynamics, (ii) there is a sizable non-adiabatic contribution to
the exact xc potential, which turns out to be small only at the beginning and
at the end of the Rabi cycle when the ground state population is dominant. We
then propose a "two-level" approximation for the time-dependent xc potential
which can capture Rabi dynamics in the 2-site problem. It works well both for
resonant and for detuned Rabi oscillations and becomes essentially exact in the
linear response regime. This new, fully non-adiabatic and explicit density
functional constitutes one of the main results of the present work.


title: Sharp capacity estimates for annuli in weighted R^n and in metric spaces

abstract:
  We obtain estimates for the nonlinear variational capacity of annuli in
weighted R^n and in metric spaces. We introduce four different (pointwise)
exponent sets, show that they all play fundamental roles for capacity
estimates, and also demonstrate that whether an end point of an exponent set is
attained or not is important. As a consequence of our estimates we obtain, for
instance, criteria for points to have zero (resp. positive) capacity. Our
discussion holds in rather general metric spaces, including Carnot groups and
many manifolds, but it is just as relevant on weighted R^n. Indeed, to
illustrate the sharpness of our estimates, we give several examples of radially
weighted R^n, which are based on quasiconformality of radial stretchings in
R^n.


title:
Higher-order QCD effects for associated WH production and decay at the
  LHC

abstract:
  We consider Standard Model Higgs boson production in association with a W
boson in hadron collisions. We supplement the fully exclusive perturbative
computation of QCD radiative effects up to next-to-next-to-leading order (NNLO)
with the computation of the decay of the Higgs boson into a bb pair at
next-to-leading order (NLO). We consider the selection cuts that are typically
applied in the LHC experimental analysis, and we compare our fixed-order
predictions with the results obtained with the MC@NLO event generator. We find
that NLO corrections to the H -> bb decay can be important to obtain a reliable
pT spectrum of the Higgs boson, but that, in the cases of interest, their
effect is well accounted for by the parton shower Monte Carlo. NNLO corrections
to the production process typically decrease the cross section by an amount
which depends on the detail of the applied cuts, but they have a mild effect on
the shape of the Higgs pT spectrum. We also discuss the effect of QCD radiative
corrections on the invariant mass distribution of the Higgs candidate.


title: An agent-based epidemiological model of incarceration

abstract:
  We build an agent-based model of incarceration based on the SIS model of
infectious disease propagation. Our central hypothesis is that the observed
racial disparities in incarceration rates between Black and White Americans can
be explained as the result of differential sentencing between the two
demographic groups. We demonstrate that if incarceration can be spread through
a social influence network, then even relatively small differences in
sentencing can result in the large disparities in incarceration rates.
Controlling for effects of transmissibility, susceptibility, and influence
network structure, our model reproduces the observed large disparities in
incarceration rates given the differences in sentence lengths for White and
Black drug offenders in the United States without extensive parameter tuning.
We further establish the suitability of the SIS model as applied to
incarceration, as the observed structural patterns of recidivism are an
emergent property of the model. In fact, our model shows a remarkably close
correspondence with California incarceration data, without requiring any
parameter tuning. This work advances efforts to combine the theories and
methods of epidemiology and criminology.


title: Ground State Phase Diagram of Parahydrogen in One Dimension

abstract:
  The low-temperature phase diagram of parahydrogen in one dimension is studied
by quantum Monte Carlo simulations, whose results are interpreted within the
framework of Luttinger liquid theory. We show that, contrary to what was
claimed in a previous study [Phys. Rev. Lett. 85, 2348 (2000)], the equilibrium
phase is a crystal. The phase diagram mimics that of parahydrogen in two
dimensions, with a single quasicrystaline phase and no quantum phase
transition; i.e., it is qualitatively different from that of Helium-four in one
dimension.


title: The Parameterized Complexity of Reasoning Problems Beyond NP

abstract:
  Today's propositional satisfiability (SAT) solvers are extremely powerful and
can be used as an efficient back-end for solving NP-complete problems. However,
many fundamental problems in knowledge representation and reasoning are located
at the second level of the Polynomial Hierarchy or even higher, and hence
polynomial-time transformations to SAT are not possible, unless the hierarchy
collapses. Recent research shows that in certain cases one can break through
these complexity barriers by fixed-parameter tractable (fpt) reductions which
exploit structural aspects of problem instances in terms of problem parameters.
In this paper we develop a general theoretical framework that supports the
classification of parameterized problems on whether they admit such an
fpt-reduction to SAT or not. This framework is based on several new
parameterized complexity classes. As a running example, we use the framework to
classify the complexity of the consistency problem for disjunctive answer set
programming, with respect to various natural parameters. We underpin the
robustness of our theory by providing a characterization of the new complexity
classes in terms of weighted QBF satisfiability, alternating Turing machines,
and first-order model checking. In addition, we provide a compendium of
parameterized problems that are complete for the new complexity classes,
including problems related to Knowledge Representation and Reasoning, Logic,
and Combinatorics.


title:
Formal properties of the probability of fixation: identities,
  inequalities and approximations

abstract:
  The formula for the probability of fixation of a new mutation is widely used
in theoretical population genetics and molecular evolution. Here we derive a
series of identities, inequalities and approximations for the exact probability
of fixation of a new mutation under the Moran process (equivalent results hold
for the approximate probability of fixation for the Wright-Fisher process after
an appropriate change of variables). We show that the behavior of the logarithm
of the probability of fixation is particularly simple when the selection
coefficient is measured as a difference of Malthusian fitnesses, and we exploit
this simplicity to derive several inequalities and approximations. We also
present a comprehensive comparison of both existing and new approximations for
the probability of fixation, highlighting in particular approximations that
result in a reversible Markov chain when used to model the dynamics of
evolution under weak mutation.


title:
On the relation generation method of Joux for computing discrete
  logarithms

abstract:
  In \cite{joux}, Joux devised an algorithm to compute discrete logarithms
between elements in a certain subset of the multiplicative group of an
extension of the finite field $\mathbb{F}_{p^n}$ in time polynomial in $p$ and
$n$. Shortly after, Barbulescu, Gaudry, Joux and Thome \cite{bgjt} proposed a
descent algorithm that in $(p n)^{\mathcal{O}(\log n)}$ time projects an
arbitrary element in $\mathbb{F}_{p^n}^\times$ as a product of powers of
elements in the aforementioned subset. Together, these two algorithms yield a
quasi-polynomial time algorithm for computing discrete logarithms in finite
fields of small characteristic. The success of both the algorithms are reliant
on heuristic assumptions. We identify obstructions that prevent certain
heuristic assumptions they make from being true in general. Further, we
describe methods to overcome these obstructions.


title:
Components of spaces of curves with constrained curvature on flat
  surfaces

abstract:
  Let $S$ be a complete flat surface, such as the Euclidean plane. We obtain
direct characterizations of the connected components of the space of all curves
on $S$ which start and end at given points in given directions, and whose
curvatures are constrained to lie in a given interval, in terms of all
parameters involved. Many topological properties of these spaces are
investigated. Some conjectures of L. E. Dubins are proved.


title:
Chain Equivalences for Symplectic Bases, Quadratic Forms and Tensor
  Products of Quaternion Algebras

abstract:
  We present a set of generators for the symplectic group which is different
from the well-known set of transvections, from which the chain equivalence for
quadratic forms in characteristic 2 is an immediate result. Based on the chain
equivalences for quadratic forms, both in characteristic 2 and not 2, we
provide chain equivalences for tensor products of quaternion algebras over
fields with no nontrivial 3-fold Pfister forms. The chain equivalence for
biquaternion algebras in characteristic 2 is also obtained in this process,
without any assumption on the base-field.


title:
From the Berkovits formulation to the Witten formulation in open
  superstring field theory

abstract:
  The Berkovits formulation of open superstring field theory is based on the
large Hilbert space of the superconformal ghost sector. We discuss its relation
to the Witten formulation based on the small Hilbert space. We introduce a
one-parameter family of conditions for partial gauge fixing of the Berkovits
formulation such that the cubic interaction of the theory under the partial
gauge fixing reduces to that of the Witten formulation in a singular limit. The
local picture-changing operator at the open-string midpoint in the Witten
formulation is regularized in our approach, and the divergence in on-shell
four-point amplitudes coming from collision of picture-changing operators is
resolved. The quartic interaction inherited from the Berkovits formulation
plays a role of adjusting different behaviors of the picture-changing operators
in the $s$ channel and in the $t$ channel of Feynman diagrams with two cubic
vertices, and correct amplitudes in the world-sheet theory are reproduced.
While gauge invariance at the second order in the coupling constant is obscured
in the Witten formulation by collision of picture-changing operators, it is
well defined in our approach and is recovered by including the quartic
interaction inherited from the Berkovits formulation.


title: Note on the number of edges in families with linear union-complexity

abstract:
  We give a simple argument showing that the number of edges in the
intersection graph $G$ of a family of $n$ sets in the plane with a linear
union-complexity is $O(\omega(G)n)$. In particular, we prove $\chi(G)\leq
\text{col}(G)< 19\omega(G)$ for intersection graph $G$ of a family of
pseudo-discs, which improves a previous bound.


title:
Broadband Isolated Attosecond Pulses: Generation, Characterization, and
  Applications

abstract:
  The generation of the shortest isolated attosecond pulses requires both broad
spectral bandwidth and control of the spectral phase. Rapid progress has been
made in both aspects, leading to the generation of the world-record-shortest 67
as light pulses in 2012, and broadband attosecond continua covering a wide
range of extreme ultraviolet and soft x-ray wavelengths. Such pulses have been
successfully applied in photoelectron/photoion spectroscopy and the recently
developed attosecond transient absorption spectroscopy to study electron
dynamics in matter. In this Review, we discuss the significant recent
advancement in the generation, characterization, and application of
ultrabroadband isolated attosecond pulses with spectral bandwidth comparable to
the central frequency, which can in principle be compressed to a single optical
cycle.


title: Disjoint induced subgraphs of the same order and size

abstract:
  For a graph $G$, let $f(G)$ be the largest integer $k$ for which there exist
two vertex-disjoint induced subgraphs of $G$ each on $k$ vertices, both
inducing the same number of edges. We prove that $f(G) \ge n/2 - o(n)$ for
every graph $G$ on $n$ vertices. This answers a question of Caro and Yuster.


title: An Approach: Modality Reduction and Face-Sketch Recognition

abstract:
  To recognize face sketch through face photo database is a challenging task
for todays researchers. Because face photo images in training set and face
sketch images in testing set have different modality. Difference between two
face photos of difference person is smaller than the difference between same
person in a face photo and face sketched. In this paper, for reduction of the
modality between face photo and face sketch we first bring face photo and face
sketch images in a new dimension using 2D Discrete Haar wavelet transform with
scale 3 followed by a negative approach. After that, extract features from
transformed images using Principal Component Analysis (PCA). Thereafter, we use
SVM classifier and K-NN classifier for better classification. Our proposed
method is experimentally verified by its robustness against faces that are
captured in a good lighting condition and in a frontal pose. The experiment has
been conducted with 100 male and female face images as training set and 100
male and female face sketch images as testing set collected from CUHK training
and testing cropped photos and CUHK training and testing cropped sketches.


title: Locally Rotationally Symmetric Vacuum Solutions in f(R) Gravity

abstract:
  This paper is devoted to find the Locally Rotationally Symmetric (LRS) vacuum
solutions in the context of f(R) theory of gravity. Actually, we have
considered the three metrics representing the whole family of LRS spacetimes
and solved the field equations by using metric approach as well as the
assumption of constant scalar curvature. It is mention here that R may be zero
or non-zero. In all we found 10 different solutions.


title:
Face Recognition using Hough Peaks extracted from the significant blocks
  of the Gradient Image

abstract:
  This paper proposes a new technique for automatic face recognition using
integrated peaks of the Hough transformed significant blocks of the binary
gradient image. In this approach firstly the gradient of an image is calculated
and a threshold is set to obtain a binary gradient image, which is less
sensitive to noise and illumination changes. Secondly, significant blocks are
extracted from the absolute gradient image, to extract pertinent information
with the idea of dimension reduction. Finally the best fitted Hough peaks are
extracted from the Hough transformed significant blocks for efficient face
recognition. Then these Hough peaks are concatenated together, which are used
as feature in classification process. The efficiency of the proposed method is
demonstrated by the experiment on 1100 images from the FRAV2D face database,
2200 images from the FERET database, where the images vary in pose, expression,
illumination and scale and 400 images from the ORL face database, where the
images slightly vary in pose. Our method has shown 93.3%, 88.5% and 99%
recognition accuracy for the FRAV2D, FERET and the ORL database respectively.


title:
High Performance Human Face Recognition using Gabor based Pseudo Hidden
  Markov Model

abstract:
  This paper introduces a novel methodology that combines the multi-resolution
feature of the Gabor wavelet transformation (GWT) with the local interactions
of the facial structures expressed through the Pseudo Hidden Markov model
(PHMM). Unlike the traditional zigzag scanning method for feature extraction a
continuous scanning method from top-left corner to right then top-down and
right to left and so on until right-bottom of the image i.e. a spiral scanning
technique has been proposed for better feature selection. Unlike traditional
HMMs, the proposed PHMM does not perform the state conditional independence of
the visible observation sequence assumption. This is achieved via the concept
of local structures introduced by the PHMM used to extract facial bands and
automatically select the most informative features of a face image. Thus, the
long-range dependency problem inherent to traditional HMMs has been drastically
reduced. Again with the use of most informative pixels rather than the whole
image makes the proposed method reasonably faster for face recognition. This
method has been successfully tested on frontal face images from the ORL, FRAV2D
and FERET face databases where the images vary in pose, illumination,
expression, and scale. The FERET data set contains 2200 frontal face images of
200 subjects, while the FRAV2D data set consists of 1100 images of 100 subjects
and the full ORL database is considered. The results reported in this
application are far better than the recent and most referred systems.


title:
Human Face Recognition using Gabor based Kernel Entropy Component
  Analysis

abstract:
  In this paper, we present a novel Gabor wavelet based Kernel Entropy
Component Analysis (KECA) method by integrating the Gabor wavelet
transformation (GWT) of facial images with the KECA method for enhanced face
recognition performance. Firstly, from the Gabor wavelet transformed images the
most important discriminative desirable facial features characterized by
spatial frequency, spatial locality and orientation selectivity to cope with
the variations due to illumination and facial expression changes were derived.
After that KECA, relating to the Renyi entropy is extended to include cosine
kernel function. The KECA with the cosine kernels is then applied on the
extracted most important discriminating feature vectors of facial images to
obtain only those real kernel ECA eigenvectors that are associated with
eigenvalues having positive entropy contribution. Finally, these real KECA
features are used for image classification using the L1, L2 distance measures;
the Mahalanobis distance measure and the cosine similarity measure. The
feasibility of the Gabor based KECA method with the cosine kernel has been
successfully tested on both frontal and pose-angled face recognition, using
datasets from the ORL, FRAV2D and the FERET database.


title:
Finite temperature fermionic condensate and currents in topologically
  nontrivial spaces

abstract:
  We investigate the finite temperature fermionic condensate and the
expectation values of the charge and current densities for a massive fermion
field in a spacetime background with an arbitrary number of toroidally
compactified spatial dimensions in the presence of a non-vanishing chemical
potential. Periodicity conditions along compact dimensions are taken with
arbitrary phases and the presence of a constant gauge field is assumed. The
latter gives rise to Aharonov-Bohm-like effects on the expectation values. They
are periodic functions of magnetic fluxes enclosed by compact dimensions with
the period equal to the flux quantum. The current density has nonzero
components along compact dimensions only. Both low- and high-temperature
asymptotics of the expectation values are studied. In particular, it has been
shown that at high temperatures the current density is exponentially
suppressed. This behavior is in sharp contrast with the corresponding
asymptotic in the case of a scalar field, where the current density linearly
grows with the temperature. The features for the models in odd dimensional
spacetimes are discussed. Applications are given to cylindrical and toroidal
nanotubes described within the framework of effective Dirac theory for the
electronic subsystem.


title:
On the stability of bow shocks generated by red supergiants: the case of
  IRC-10414

abstract:
  In this Letter, we explore the hypothesis that the smooth appearance of bow
shocks around some red supergiants (RSGs) might be caused by the ionization of
their winds by external sources of radiation. Our numerical simulations of the
bow shock generated by IRC-10414 (the first-ever RSG with an optically detected
bow shock) show that the ionization of the wind results in its acceleration by
a factor of two, which reduces the difference between the wind and space
velocities of the star and makes the contact discontinuity of the bow shock
stable for a range of stellar space velocities and mass-loss rates. Our best
fit model reproduces the overall shape and surface brightness of the observed
bow shock and suggests that the space velocity and mass-loss rate of IRC-10414
are $\approx$50 ${\rm km} \, {\rm s}^{-1}$ and $\approx$$10^{-6}$ $M_\odot \,
{\rm yr}^{-1}$, respectively, and that the number density of the local ISM is
$\approx$3 ${\rm cm}^{-3}$. It also shows that the bow shock emission comes
mainly from the shocked stellar wind. This naturally explains the enhanced
nitrogen abundance in the line-emitting material, derived from the spectroscopy
of the bow shock. We found that photoionized bow shocks are $\approx$15$-$50
times brighter in optical line emission than their neutral counterparts, from
which we conclude that the bow shock of IRC-10414 must be photoionized.


title:
Chasing the phantom: A closer look at Type Ia supernovae and the dark
  energy equation of state

abstract:
  Some recent observations provide $> 2\sigma$ evidence for phantom dark energy
-- a value of the dark energy equation of state less than the
cosmological-constant value of $-1$. We focus on constraining the equation of
state by combining current data from the most mature geometrical probes of dark
energy: Type Ia supernovae (SNe Ia) from the Supernova Legacy Survey (SNLS3),
the Supernova Cosmology Project (Union2.1), and the Pan-STARRS1 survey (PS1);
cosmic microwave background measurements from Planck and WMAP9; and a
combination of measurements of baryon acoustic oscillations. The combined data
are consistent with $w = -1$ for the Union2.1 sample, though they present
moderate ($\sim 1.9\sigma$) evidence for a phantom value when either the SNLS3
or PS1 sample is used instead. We study the dependence of the constraints on
the redshift, stretch, color, and host galaxy stellar mass of SNe, but we find
no unusual trends. In contrast, the constraints strongly depend on any external
$H_0$ prior: a higher adopted value for the direct measurement of the Hubble
constant ($H_0 \gtrsim 71~\text{km/s/Mpc}$) leads to $\gtrsim 2\sigma$ evidence
for phantom dark energy. Given Planck data, we can therefore make the following
statement at $2\sigma$ confidence: either the SNLS3 and PS1 data have
systematics that remain unaccounted for or the Hubble constant is below 71
km/s/Mpc; else the dark energy equation of state is indeed phantom.