title: Data Hiding and Retrieval Using Permutation Index Method

abstract:
  In this paper a novel approach for matrix manipulation and indexing is
proposed .Here the elements in a row of matrix are designated by numeric value
called permutation index followed by the elements of the row being randomised.
This is done for all the rows of the matrix and in the end the set of
permutation indices are put in the parent matrix and random locations depending
on a pre decided scheme called passkey. This passkey is used to put back the
elements of all the rows back in the correct sequence. This approach finds
application in data encapsulation and hiding.


title: Environment-dependent payoffs in finite populations

abstract:
  In constant-payoff finite population games, when selection is weak and
population size is large, the one-third law serves as the condition for a
strategy to be advantageous. We generalize the result to the case where payoff
matrices are environment-dependent and provide a more general law. In this way
we model feedback from the environment and show its impact on the dynamics.


title:
Laser photons acquire circular polarization by interacting with a Dirac
  or Majorana neutrino beam

abstract:
  It is shown that for the reason of neutrinos being left-handed and their
gauge-couplings being parity-violated, linearly polarized photons acquire their
circular polarization by interacting with neutrinos. Calculating the ratio of
linear and circular polarizations of laser photons interacting with either
Dirac or Majorana neutrino beam, we obtain this ratio for the Dirac neutrino
case, which is about twice less than the ratio for the Majorana neutrino case.
Based on this ratio, we discuss the possibility of using advanced laser
facilities and the T2K neutrino experiment to measure the circular polarization
of laser beams interacting with neutrino beams in ground laboratories. This
could be an additional and useful way to gain some insight into the physics of
neutrinos, for instance their Dirac or Majorana nature.


title:
Appearance of flat surface bands in three-dimensional topological
  insulators in a ferromagnetic exchange field

abstract:
  We study the properties of the surface states in three-dimensional
topological insulators in the presence of a ferromagnetic exchange field. We
demonstrate that for layered materials like Bi$_2$Se$_3$ the surface states on
the top surface behave qualitatively different than the surface states at the
side surfaces. We show that the group velocity of the surface states can be
tuned by the direction and strength of the exchange field. If the exchange
field becomes larger than the bulk gap of the material, a phase transition into
a topologically nontrivial semimetallic state occurs. In particular, the
material becomes a Weyl semimetal, if the exchange field possesses a non-zero
component perpendicular to the layers. Associated with the Weyl semimetallic
state we show that Fermi arcs appear at the surface. Under certain
circumstances either one-dimensional or even two-dimensional surface flat bands
can appear. We show that the appearence of these flat bands is related to
chiral symmetries of the system and can be understood in terms of topological
winding numbers. In contrast to previous systems that have been suggested to
possess surface flat bands, the present system has a much larger energy scale,
allowing the observation of surface flat bands at room temperature. The flat
bands are tunable in the sense that they can be turned on or off by rotation of
the ferromagnetic exchange field. Our findings are supported by both numerical
results on a finite system as well as approximate analytical results.


title: A Note on Asymmetric Thick Branes

abstract:
  In this work we study asymmetric thick braneworld scenarios, generated after
adding a constant to the superpotential associated to the scalar field. We
study in particular models with odd and even polynomial superpotentials, and we
show that asymmetric brane can be generated irrespective of the potential being
symmetric or asymmetric. We study in addition the nonpolynomial
sine-Gordon-like model, also constructed with the inclusion of a constant in
the standard superpotential, and we investigate gravitational stability of the
asymmetric brane. The results suggest robustness of the new braneworld
scenarios and add further possibilities for the construction of asymmetric
branes.


title: Sequences of weak solutions for fractional equations

abstract:
  This work is devoted to study the existence of infinitely many weak solutions
to nonlocal equations involving a general integrodifferential operator of
fractional type. These equations have a variational structure and we find a
sequence of nontrivial weak solutions for them exploiting the
${\mathbb{Z}}_2$-symmetric version of the Mountain Pass Theorem. To make the
nonlinear methods work, some careful analysis of the fractional spaces involved
is necessary. As a particular case, we derive an existence theorem for the
fractional Laplacian, finding nontrivial solutions of the equation $$
\left\{\begin{array}{ll} (-\Delta)^s u=f(x,u) & {\mbox{in}} \Omega\\ u=0 &
{\mbox{in}} \erre^n\setminus \Omega. \end{array} \right. $$ As far as we know,
all these results are new and represent a fractional version of classical
theorems obtained working with Laplacian equations.


title: Two-elliptic coordinates. Eigenfunctions and eigenvalues

abstract:
  The elliptic coordinates are used to build a new families of 2D coordinate
systems which are orthogonal and admits the separation of variables. The charts
of characteristic curves are constructed for these systems and compared with
Mathieu's. The possible applications are in quantum mechanics, diffraction
theory, vibrations and classical dynamics.


title:
A Herschel view of IC 1396 A: Unveiling the different sequences of star
  formation

abstract:
  The IC1396A globule in the young cluster Tr37, hosting many young stars and
protostars, is assumed to be a site of triggered star formation. We mapped
IC1396A with Herschel/PACS at 70 and 160 micron. The Herschel maps trace in
great detail the very embedded protostellar objects and the structure of the
cloud. PACS data reveal a previously unknown Class 0 object (IC1396A-PACS-1)
located behind the ionization front. IC1396A-PACS-1 is not detectable with
Spitzer, but shows marginal X-ray emission. The data also allowed to study
three of the Class I intermediate-mass objects within the cloud. We derived
approximate cloud temperatures to study the effect and potential interactions
between the protostars and the cloud. The Class 0 object is associated with the
densest and colder part of IC1396A. Heating in the cloud is dominated by the
winds and radiation of the O6.5 star HD 206267 and, to a lesser extent, by the
effects of the Herbig Ae star V 390 Cep. The surroundings of the Class I and
Class II objects embedded in the cloud also appear warmer than the sourceless
areas, although most of the low-mass objects cannot be individually extracted
due to distance and beam dilution. The observations suggest that at least two
episodes of star formation have occurred in IC1396A. One would have originated
the known, ~1 Myr-old Class I and II objects in the cloud, and a new wave of
star formation would have produced the Class 0 source at the tip of the
brigth-rimmed cloud. From its location and properties, IC1396A-PACS-1 is
consistent with triggering via radiative driven implosion (RDI) induced by HD
206267. The mechanisms behind the formation of the more evolved population of
Class I/II/III objects in the cloud are uncertain. Heating of most of the
remaining cloud by Class I/Class II objects and by HD 206267 itself may
preclude further star formation in the region.


title: Recent DHCAL Developments

abstract:
  This talk reports on recent progress concerning the development of a Digital
Hadron Calorimeter with Resistive Plate Chambers as active elements. After the
successful testing of a Digital Hadron Calorimeter prototype, the DHCAL, in the
Fermilab and CERN test beams, the DHCAL group is now tackling some of the
remaining technical issues which were not addressed specifically with the
prototype. The talk reports on developments related to the RPC chamber design,
to improvements in the RPC rate capabilities, the high voltage distribution
system, and a gas recirculation system.


title: FPCB : a simple and swift strategy for mirror repeat identification

abstract:
  After the recent advancement of sequencing strategies, mirror repeats have
been found to be present in the gene sequence of many organisms and species.
This presence of mirror repeats in most of the sequences indicates towards some
important functional role of these repeats. However, a simple and quick
strategy to search these repeats in a given sequence is not available. We in
this manuscript have proposed a simple and swift strategy named as FPCB
strategy to identify mirror repeats in a give sequence. The strategy includes
three simple steps of downloading sequencing in FASTA format (F), making its
parallel complement (PC) and finally performing a homology search with the
original sequence (B). At least twenty genes were analyzed using the proposed
study. A number and types of mirror repeats were observed. We have also tried
to give nomenclature to these repeats. We hope that the proposed FPCB strategy
will be quite helpful for the identification of mirror repeats in DNA or mRNA
sequence. Also the strategy may help in unraveling the functional role of
mirror repeats in various processes including evolution.


title:
Bootstrap for dependent Hilbert space-valued random variables with
  application to von Mises statistics

abstract:
  Statistical methods for functional data are of interest for many
applications. In this paper, we prove a central limit theorem for random
variables taking their values in a Hilbert space. The random variables are
assumed to be weakly dependent in the sense of near epoch dependence, where the
underlying process fulfills some mixing conditions. As parametric inference in
an infinite dimensional space is difficult, we show that the nonoverlapping
block bootstrap is consistent. Furthermore, we show how these results can be
used for degenerate von Mises-statistics.


title: Manifest causality in quantum field theory with sources and detectors

abstract:
  We introduce a way to compute scattering amplitudes in quantum field theory
including the effects of particle production and detection. Our amplitudes are
manifestly causal, by which we mean that the source and detector are always
linked by a connected chain of retarded propagators. We show how these
amplitudes can be derived from a path integral, using the Schwinger-Keldysh
"in-in" formalism. Focussing on phi-cubed theory, we confirm that our approach
agrees with the standard S-matrix approach in the case of positive energy
plane-wave scattering.


title:
Eugene Garfield, Francis Narin, and PageRank: The Theoretical Bases of
  the Google Search Engine

abstract:
  This paper presents a test of the validity of using Google Scholar to
evaluate the publications of researchers by comparing the premises on which its
search engine, PageRank, is based, to those of Garfield's theory of citation
indexing. It finds that the premises are identical and that PageRank and
Garfield's theory of citation indexing validate each other.


title: Schauder bases in Dirac modules over quaternions

abstract:
  Dirac modules over the quaternion skew field are investigated on a compact
domain relative to the supremum norm and Hardy's norm with the parameter
$1<p<\infty $ as well. An existence of Schauder bases in them is proved.
Procedures for construction of such bases are outlined.


title: The Racah algebra and superintegrable models

abstract:
  The universal character of the Racah algebra will be illustrated by showing
that it is at the center of the relations between the Racah polynomials, the
recoupling of three su(1,1) representations and the symmetries of the generic
second-order superintegrable model on the 2-sphere.


title: Extreme Harmonic Generation in Electrically Driven Spin Resonance

abstract:
  We report the observation of multiple harmonic generation in electric dipole
spin resonance in an InAs nanowire double quantum dot. The harmonics display a
remarkable detuning dependence: near the interdot charge transition as many as
eight harmonics are observed, while at large detunings we only observe the
fundamental spin resonance condition. The detuning dependence indicates that
the observed harmonics may be due to Landau-Zener transition dynamics at
anticrossings in the energy level spectrum.


title:
The Symmetric Convex Ordering: A Novel Partial Order for B-DMCs Ordering
  the Information Sets of Polar Codes

abstract:
  In this paper, we propose a novel partial order for binary discrete
memoryless channels that we call the symmetric convex ordering. We show that
Ar{\i}kan's polar transform preserves 'symmetric convex orders'. Furthermore,
we show that while for symmetric channels this ordering turns out to be
equivalent to the stochastic degradation ordering already known to order the
information sets of polar codes, a strictly weaker partial order is obtained
when at least one of the channels is asymmetric. In between, we also discuss
two tools which can be useful for verifying this ordering: a criterion known as
the cut criterion and channel symmetrization. Finally, we discuss potential
applications of the results to polar coding over non-stationary channels.


title: The Dunkl oscillator in three dimensions

abstract:
  The isotropic Dunkl oscillator model in three-dimensional Euclidean space is
considered. The system is shown to be maximally superintegrable and its
symmetries are obtained by the Schwinger construction using the
raising/lowering operators of the dynamical sl_{-1}(2) algebra of the
one-dimensional Dunkl oscillator. The invariance algebra generated by the
constants of motion, an extension of u(3) with reflections, is called the
Schwinger-Dunkl algebra sd(3). The system is shown to admit separation of
variables in Cartesian, polar (cylindrical) and spherical coordinates and the
corresponding separated solutions are expressed in terms of generalized
Hermite, Laguerre and Jacobi polynomials.


title: Application of p-adic analysis to time series

abstract:
  Time series defined by a p-adic pseudo-differential equation is investigated
using the expansion of the time series over p-adic wavelets. Quadratic
correlation function is computed. This correlation function shows a
degree--like behavior and is locally constant for some time periods. It is
natural to apply this kind of models for the investigation of avalanche
processes and punctuated equilibrium as well as fractal-like analysis of time
series generated by measurement of pressure in oil wells.


title: Measure of Diracness in two-dimensional semiconductors

abstract:
  We analyze the low-energy properties of two-dimensional direct-gap
semiconductors, such as for example the transition-metal dichalcogenides
MoS$_2$, WS$_2$, and their diselenide analogues MoSe$_2$, WSe$_2$, etc., which
are currently intensively investigated. In general, their electrons have a
mixed character -- they can be massive Dirac fermions as well as simple
Schr\"odinger particles. We propose a measure (Diracness) for the degree of
mixing between the two characters and discuss how this quantity can in
principle be extracted experimentally, within magneto-transport measurements,
and numerically via ab initio calculations.


title: Critical behaviour for scalar nonlinear waves

abstract:
  In the long-wave regime, nonlinear waves may undergo a phase transition from
a smooth to a fast oscillatory behaviour. We study this phenomenon, commonly
known as dispersive shock, in the light of Dubrovin's universality conjecture ,
and we argue that the transition can be described by a special solution of a
model universal partial differential equation. This universal solution is
constructed by means of a string equation. We provide a classification of
universality classes and the explicit description of the transition by means of
special functions, extending Dubrovin's universality conjecture to a wider
class of equations. In particular, we show that Benjamin-Ono equation belongs
to a novel universality class with respect to the ones known in the literature,
and we compute its string equation exactly. We describe our results using the
language of statistical mechanics, showing that dispersive shocks share many
features of the tri-critical point in statistical systems, and building a
dictionary between nonlinear waves and statistical mechanics.


title: Rectification of enriched infinity-categories

abstract:
  We prove a rectification theorem for enriched infinity-categories: If V is a
nice monoidal model category, we show that the homotopy theory of
infinity-categories enriched in V is equivalent to the familiar homotopy theory
of categories strictly enriched in V. It follows, for example, that
infinity-categories enriched in spectra or chain complexes are equivalent to
spectral categories and dg-categories. A similar method gives a comparison
result for enriched Segal categories, which implies that the homotopy theories
of n-categories and (infinity,n)-categories defined by iterated
infinity-categorical enrichment are equivalent to those of more familiar
versions of these objects. In the latter case we also include a direct
comparison with complete n-fold Segal spaces. Along the way we prove a
comparison result for fibrewise simplicial localizations potentially of
independent use.


title: White Dwarf based evaluation of the GALEX absolute calibration

abstract:
  This paper describes a revised photometric calibration of the \emph{Galaxy
Evolution Explorer} magnitudes, based on measurements of DA white dwarfs. The
photometric magnitudes of white dwarfs measured by \emph{GALEX} are compared to
predicted magnitudes based on independent spectroscopic data (108 stars) and
alternately to \emph{IUE} UV fluxes of the white dwarfs (218 stars). The
results demonstrate a significant non-linear correlation and small offset
between archived \emph{GALEX} fluxes and observed and predicted UV fluxes for
our sample. The primary source of non-linearity may be due to detector dead
time corrections for brighter stars, but it should be noted that there was a
predicted non-linearity in the fainter stars as well. Sample expressions are
derived which 'correct' observed \emph{GALEX} magnitudes to an absolute
magnitude scale that is linear with respect, and directly related, to the
\emph{Hubble Space Telescope} photometric scale. These corrections should be
valid for stars dimmer than magnitudes 9.3 and 10.5 in the NUV and FUV
respectively, and brighter than magnitude 17.5 in both


title:
Precise measurement of alpha-K for the 65.7-keV M4 transition in 119Sn:
  Extended test of internal-conversion theory

abstract:
  We have measured the K-shell internal conversion coefficient, alpha-K, for
the 65.7-keV M4 transition in 119Sn to be 1621(25). This result agrees well
with Dirac-Fock calculations in which the effect of the K-shell atomic vacancy
is accounted for, and disagrees with calculations in which the vacancy is
ignored. This extends our precision tests of theory to Z = 50, the lowest Z yet
measured.


title: Quadratic Twists of Elliptic Curves

abstract:
  In this paper, we show that Tian's induction method can be generalised to
study the Birch-Swinnerton-Dyer conjecture for the quadratic twists, both with
global root number $+1$ and with global root number $-1$, of certain elliptic
curves $E$ defined over $\mathbb Q$. In particular, for the curve $E = X_0(49)$
we prove the following results. Let $q_1, \ldots, q_r$ be distinct primes which
are congruent to $1$ modulo $4$ and inert in the field $F = \mathbb
Q(\sqrt{-7})$, and let $E^{(R)}$ be the twist of $E$ by the quadratic extension
$\mathbb Q(\sqrt{R})/\mathbb Q$, where $R=q_1\ldots q_r$. Then we show that the
complex L-series of $E^{(R)}$ does not vanish at $s=1$, and the full
Birch-Swinnerton-Dyer conjecture is true for $E^{(R)}$. Let $l_0$ be a prime
number which is congruent to $3$ modulo $4$, and is such that $7$ splits in the
field $K = \mathbb Q(\sqrt{-l_0})$. If we assume in addition that all of the
primes $q_1, \ldots, q_r$ are inert in $K$ as well as in $F$, then we prove
that the complex $L$-series of the twist of $E$ by $\mathbb
Q(\sqrt{-l_0R})/\mathbb Q$ always has a simple zero at $s=1$. Similar results
are obtained for certain other elliptic curves defined over $\mathbb Q$.


title:
The chemical composition of the Sun from helioseismic and solar neutrino
  data

abstract:
  We perform a quantitative analysis of the solar composition problem by using
a statistical approach that allows us to combine the information provided by
helioseimic and solar neutrino data in an effective way. We include in our
analysis the helioseismic determinations of the surface helium abundance and of
the depth of the convective envelope, the measurements of the $^7{\rm Be}$ and
$^8{\rm B}$ neutrino fluxes, the sound speed profile inferred from helioseismic
frequencies. We provide all the ingredients to describe how these quantities
depend on the solar surface composition and to evaluate the (correlated)
uncertainties in solar model predictions. We include errors sources that are
not traditionally considered such as those from inversion of helioseismic data.
We, then, apply the proposed approach to infer the chemical composition of the
Sun. We show that the opacity profile of the Sun is well constrained by the
solar observational properties. In the context of a two parameter analysis in
which elements are grouped as volatiles (i.e. C, N, O and Ne) and refractories
(i.e Mg, Si, S, Fe), the optimal composition is found by increasing the the
abundance of volatiles by $\left( 45\pm 4\right)\%$ and that of refractories by
$\left( 19\pm 3\right)\%$ with respect to the values provided by AGSS09. This
corresponds to the abundances $\varepsilon_{\rm O}=8.85\pm 0.01$ and
$\varepsilon_{\rm Fe}=7.52\pm0.01$. As an additional result of our analysis, we
show that the observational data prefer values for the input parameters of the
standard solar models (radiative opacities, gravitational settling rate, the
astrophysical factors $S_{34}$ and $S_{17}$) that differ at the $\sim 1\sigma$
level from those presently adopted.


title:
Dielectric and Magnetic Properties of (Bi1-xLaxFeO3)0.5(PbTiO3)0.5
  Ceramics Prepared from Mechanically Synthesized Powders

abstract:
  Multiferroic (Bi1-xLaxFeO3)0.5(PbTiO3)0.5 ceramics was prepared from
mechanical synthesized nanopowders. The XRD studies revealed the tetragonal
structure and the tetragonality decreased with La content. Dielectric response
of the compounds was found to contain three anomalies: 1) relaxor-like behavior
due to lattice disorder (below 300 K); 2) dielectric permittivity maxima at~400
K attributed to the presence of oxygen vacancies; 3) grain boundary effect
above 475 K. The Curie point at ~500 K was observed for the compound with
x=0.5. The composition near the morphotropic boundary:
(Bi0.8La0.2FeO3)0.5(PbTiO3)0.5 shoved the highest remnant magnetization. The
irreversible magnetic properties of the (Bi1-xLaxFeO3)0.5(PbTiO3)0.5 compounds
can be explained in terms of disorder induced spin-glass behavior due to random
substitution of La or Pb ions for Bi sites. A sharp step in magnetization about
250 K is caused by the A-site distortion associated with tilts of FeO6
octahedra leading to modification of Fe-O-Fe angles and of antiferromagnetic
coupling between magnetic Fe3+ moments.


title: Tools for NLO automation: extension of the golem95C integral library

abstract:
  We present an extension of the program golem95C for the numerical evaluation
of scalar integrals and tensor form factors entering the calculation of
one-loop amplitudes, which supports tensor ranks exceeding the number of
propagators. This extension allows various applications in Beyond the Standard
Model physics and effective theories, for example higher ranks due to
propagators of spin two particles, or due to effective vertices. Complex masses
are also supported. The program is not restricted to the Feynman diagrammatic
approach, as it also contains routines to interface to unitarity-inspired
numerical reconstruction of the integrand at the tensorial level. Therefore it
can serve as a general integral library in automated programs to calculate
one-loop amplitudes.


title: Coulomb interaction effects on the Majorana states in quantum wires

abstract:
  The stability of the Majorana modes in the presence of a repulsive
interaction is studied in the standard semiconductor wire - metallic
superconductor configuration. The effects of short-range Coulomb interaction,
which is incorporated using a purely repulsive $\delta$-function to model the
strong screening effect due to the presence of the superconductor, are
determined within a Hartree-Fock approximation of the effective Bogoliubov-De
Gennes Hamiltonian that describes the low-energy physics of the wire. Through a
numerical diagonalization procedure we obtain interaction corrections to the
single particle eigenstates and calculate the extended topological phase
diagram in terms of the chemical potential and the Zeeman energy. We find that,
for a fixed Zeeman energy, the interaction shifts the phase boundaries to a
higher chemical potential, whereas for a fixed chemical potential this shift
can occur either to lower or to higher Zeeman energies. This effects can be
interpreted as a renormalization of the g-factor due to the interaction. The
minimum Zeeman energy needed to realize Majorana fermions decreases with
increasing the strength of the Coulomb repulsion. Furthermore, we find that in
wires with multi-band occupancy this effect can be enhanced by increasing the
chemical potential, i. e. by occupying higher energy bands.


title: Cyclotomy of Weil Sums of Binomials

abstract:
  The Weil sum $W_{K,d}(a)=\sum_{x \in K} \psi(x^d + a x)$ where $K$ is a
finite field, $\psi$ is an additive character of $K$, $d$ is coprime to
$|K^\times|$, and $a \in K^\times$ arises often in number-theoretic
calculations, and in applications to finite geometry, cryptography, digital
sequence design, and coding theory. Researchers are especially interested in
the case where $W_{K,d}(a)$ assumes three distinct values as $a$ runs through
$K^\times$. A Galois-theoretic approach, combined with $p$-divisibility results
on Gauss sums, is used here to prove a variety of new results that constrain
which fields $K$ and exponents $d$ support three-valued Weil sums, and restrict
the values that such Weil sums may assume.


title: Surface and bulk entanglement in free-fermion chains

abstract:
  We consider free-fermion chains where full and empty parts are connected by a
transition region with narrow surfaces. This can be caused by a linear
potential or by time evolution from a step-like initial state. Entanglement
spectra, entanglement entropies and fluctuations are determined for subsystems
either in the surface region or extending into the bulk. In all cases there is
logarithmic behaviour in the subsystem size, but the prefactors in the surface
differ from those in the bulk by 3/2. A previous fluctuation result is
corrected and a general scaling formula is inferred from the data.


title: Algorithmic Diversity for Software Security

abstract:
  Software diversity protects against a modern-day exploits such as code-reuse
attacks. When an attacker designs a code-reuse attack on an example executable,
it relies on replicating the target environment. With software diversity, the
attacker cannot reliably replicate their target. This is a security benefit
which can be applied to massive-scale software distribution. When applied to
large-scale communities, an invested attacker may perform analysis of samples
to improve the chances of a successful attack (M. Franz).
  We present a general NOP-insertion algorithm which can be expanded and
customized for security, performance, or other costs. We demonstrate an
improvement in security so that a code-reuse attack based on any one variant
has minimal chances of success on another and analyse the costs of this method.
Alternately, the variants may be customized to meet performance or memory
overhead constraints. Deterministic diversification allows for the flexibility
to balance these needs in a way that doesn't exist in a random online method.


title: Approximating the Revenue Maximization Problem with Sharp Demands

abstract:
  We consider the revenue maximization problem with sharp multi-demand, in
which $m$ indivisible items have to be sold to $n$ potential buyers. Each buyer
$i$ is interested in getting exactly $d_i$ items, and each item $j$ gives a
benefit $v_{ij}$ to buyer $i$. We distinguish between unrelated and related
valuations. In the former case, the benefit $v_{ij}$ is completely arbitrary,
while, in the latter, each item $j$ has a quality $q_j$, each buyer $i$ has a
value $v_i$ and the benefit $v_{ij}$ is defined as the product $v_i q_j$. The
problem asks to determine a price for each item and an allocation of bundles of
items to buyers with the aim of maximizing the total revenue, that is, the sum
of the prices of all the sold items. The allocation must be envy-free, that is,
each buyer must be happy with her assigned bundle and cannot improve her
utility. We first prove that, for related valuations, the problem cannot be
approximated to a factor $O(m^{1-\epsilon})$, for any $\epsilon>0$, unless {\sf
P} = {\sf NP} and that such result is asymptotically tight. In fact we provide
a simple $m$-approximation algorithm even for unrelated valuations. We then
focus on an interesting subclass of "proper" instances, that do not contain
buyers a priori known not being able to receive any item. For such instances,
we design an interesting $2$-approximation algorithm and show that no
$(2-\epsilon)$-approximation is possible for any $0<\epsilon\leq 1$, unless
{\sf P} $=$ {\sf NP}. We observe that it is possible to efficiently check if an
instance is proper, and if discarding useless buyers is allowed, an instance
can be made proper in polynomial time, without worsening the value of its
optimal solution.


title: Circular orbits on a warped spandex fabric

abstract:
  We present a theoretical and experimental analysis of circular-like orbits
made by a marble rolling on a warped spandex fabric. We show that the mass of
the fabric interior to the orbital path influences the motion of the marble in
a nontrivial way, and can even dominate the orbital characteristics. We also
compare a Kepler-like expression for such orbits to similar expressions for
orbits about a spherically-symmetric massive object in the presence of a
constant vacuum energy, as described by general relativity.


title: Semi-Markov Models in High Frequency Finance: A Review

abstract:
  In this paper we describe three stochastic models based on a semi-Markov
chains approach and its generalizations to study the high frequency price
dynamics of traded stocks. The three models are: a simple semi-Markov chain
model, an indexed semi-Markov chain model and a weighted indexed semi-Markov
chain model. We show, through Monte Carlo simulations, that the models are able
to reproduce important stylized facts of financial time series as the
persistence of volatility. In particular, we analyzed high frequency data from
the Italian stock market from the first of January 2007 until end of December
2010 and we apply to it the semi-Markov chain model and the indexed semi-Markov
chain model. The last model, instead, is applied to data from Italian and
German stock markets from January 1, 2007 until the end of December 2010.


title: Forecasting wind speed financial return

abstract:
  The prediction of wind speed is very important when dealing with the
production of energy through wind turbines. In this paper, we show a new
nonparametric model, based on semi-Markov chains, to predict wind speed.
Particularly we use an indexed semi-Markov model that has been shown to be able
to reproduce accurately the statistical behavior of wind speed. The model is
used to forecast, one step ahead, wind speed. In order to check the validity of
the model we show, as indicator of goodness, the root mean square error and
mean absolute error between real data and predicted ones. We also compare our
forecasting results with those of a persistence model. At last, we show an
application of the model to predict financial indicators like the Internal Rate
of Return, Duration and Convexity.


title: Revision of the Coulomb logarithm in the ideal plasma

abstract:
  The standard picture of the Coulomb logarithm in the ideal plasma is
controversial, the arguments for the lower cut off need revision. The two cases
of far subthermal and of far superthermal electron drift motions are accessible
to a rigorous analytical treatment. We show that the lower cut off $b_{\min}$
is a function of symmetry and shape of the shielding cloud, it is not
universal. In the subthermal case shielding is spherical and $b_{\min}$ is to
be identified with the de Broglie wavelength; at superthermal drift the
shielding cloud exhibits cylindrical (axial) symmetry and $b_{\min}$ is the
classical parameter of perpendicular deflection. In both situations the cut
offs are determined by the electron-ion encounters at large collision
parameters. This is in net contrast to the governing standard meaning that
attributes $b_{\min}$ to the Coulomb singularity at vanishing collision
parameters $b$ and, consequently, assigns it universal validity. The origin of
the contradictions in the traditional picture is analyzed.


title: Constrained information transmission on Erd\"os-R\'enyi graphs

abstract:
  We model the transmission of information of a message on the Erd\"os-R\'eny
random graph with parameters $(n,p)$ and limited resources. The vertices of the
graph represent servers that may broadcast a message at random. Each server has
a random emission capital that decreases by one at each emission. We examine
two natural dynamics: in the first dynamics, an informed server performs its
attempts, then checks at each of them if the corresponding edge is open or not;
in the second dynamics the informed server knows a priori who are its
neighbors, and it performs all its attempts on its actual neighbors in the
graph. In each case, we obtain first and second order asymptotics (law of large
numbers and central limit theorem), when $n\to \infty$ and $p$ is fixed, for
the final proportion of informed servers.


title:
Temperature-dependent structural property and power factor of n type
  thermoelectric Bi0.90Sb0.10 and Bi0.86Sb0.14 alloys

abstract:
  Thermal variation of structural property, linear thermal expansion
coefficient, resistivity, thermopower and power factor of polycrystalline
Bi1-xSbx (x=0.10, 0.14) samples are reported. Temperature-dependent powder
diffraction experiments indicate that samples do not undergo any structural
phase transition. Rietveld refinement technique has been used to perform
detailed structural analysis. Temperature dependence of thermal expansion
coefficient is found to be stronger for Bi0.90Sb0.10. Also, power factor for
direct band gap Bi0.90Sb0.10 is higher as compared to that for indirect band
gap Bi0.86Sb0.14. Role of electron-electron and electron-phonon scattering on
resistivity, thermopower and power factor have been discussed.


title:
Double-Electromagnetically Induced Transparency in a Y-type atomic
  system

abstract:
  We study the absorption and dispersion properties of a weak tunable probe
field in a four-level Y-type atomic system driven by two strong laser
(coupling) fields within the framework of density matrix formalism. It is found
that the probe absorption profile displays double-electromagnetically induced
transparency (double-EIT) and it is shown how to control it by changing the
Rabi frequencies as well as the atom field detuning of the coupling fields.


title: The spectrum of tachyons in AdS/CFT

abstract:
  We analyze the spectrum of open strings stretched between a D-brane and an
anti-D-brane in planar AdS/CFT using various tools. We focus on open strings
ending on two giant gravitons with different orientation in $AdS_5 \times S^5$
and study the spectrum of string excitations using the following approaches:
open spin-chain, boundary asymptotic Bethe ansatz and boundary thermodynamic
Bethe ansatz (BTBA). We find agreement between a perturbative high order
diagrammatic calculation in ${\cal N}=4$ SYM and the leading finite-size
boundary Luscher correction. We study the ground state energy of the system at
finite coupling by deriving and numerically solving a set of BTBA equations.
While the numerics give reasonable results at small coupling, they break down
at finite coupling when the total energy of the string gets close to zero,
possibly indicating that the state turns tachyonic. The location of the
breakdown is also predicted analytically.


title: Radio Emission from the Bow Shock of G2

abstract:
  The radio flux from the synchrotron emission of electrons accelerated in the
forward bow shock of G2 is expected to have peaked when the forward shock
passes close to the pericenter from the Galactic Center, around autumn of 2013.
This radio flux is model dependent. We find that if G2 were to be a
momentum-supported bow shock of a faint star with a strong wind, the radio
synchrotron flux from the forward-shock heated ISM is well below the quiescent
radio flux of Sgr A*. By contrast, if G2 is a diffuse cloud, the radio flux is
predicted to be much larger than the quiescent radio flux and therefore should
have already been detected or will be detected shortly. No such radiation has
been observed to date. Radio measurements can reveal the nature of G2 well
before G2 completes its periapsis passage.


title:
Exact scaling exponents in Korn and Korn-type inequalities for
  cylindrical shells

abstract:
  Understanding asymptotics of gradient components in relation to the
symmetrized gradient is im- portant for the analysis of buckling of slender
structures. For circular cylindrical shells we obtain the exact scaling
exponent of the Korn constant as a function of shell's thickness. Equally sharp
results are obtained for individual components of the gradient in cylindrical
coordinates. We also derive an ana- logue of the Kirchho? ansatz, whose most
prominent feature is its singular dependence on the slenderness parameter, in
marked contrast with the classical case of plates and rods.


title: A Methodology for Player Modeling based on Machine Learning

abstract:
  AI is gradually receiving more attention as a fundamental feature to increase
the immersion in digital games. Among the several AI approaches, player
modeling is becoming an important one. The main idea is to understand and model
the player characteristics and behaviors in order to develop a better AI. In
this work, we discuss several aspects of this new field. We proposed a taxonomy
to organize the area, discussing several facets of this topic, ranging from
implementation decisions up to what a model attempts to describe. We then
classify, in our taxonomy, some of the most important works in this field. We
also presented a generic approach to deal with player modeling using ML, and we
instantiated this approach to model players' preferences in the game
Civilization IV. The instantiation of this approach has several steps. We first
discuss a generic representation, regardless of what is being modeled, and
evaluate it performing experiments with the strategy game Civilization IV.
Continuing the instantiation of the proposed approach we evaluated the
applicability of using game score information to distinguish different
preferences. We presented a characterization of virtual agents in the game,
comparing their behavior with their stated preferences. Once we have
characterized these agents, we were able to observe that different preferences
generate different behaviors, measured by several game indicators. We then
tackled the preference modeling problem as a binary classification task, with a
supervised learning approach. We compared four different methods, based on
different paradigms (SVM, AdaBoost, NaiveBayes and JRip), evaluating them on a
set of matches played by different virtual agents. We conclude our work using
the learned models to infer human players' preferences. Using some of the
evaluated classifiers we obtained accuracies over 60% for most of the inferred
preferences.


title:
A Randomized Incremental Algorithm for the Hausdorff Voronoi Diagram of
  Non-crossing Clusters

abstract:
  In the Hausdorff Voronoi diagram of a family of \emph{clusters of points} in
the plane, the distance between a point $t$ and a cluster $P$ is measured as
the maximum distance between $t$ and any point in $P$, and the diagram is
defined in a nearest-neighbor sense for the input clusters. In this paper we
consider %El."non-crossing" \emph{non-crossing} clusters in the plane, for
which the combinatorial complexity of the Hausdorff Voronoi diagram is linear
in the total number of points, $n$, on the convex hulls of all clusters. We
present a randomized incremental construction, based on point location, that
computes this diagram in expected $O(n\log^2{n})$ time and expected $O(n)$
space. Our techniques efficiently handle non-standard characteristics of
generalized Voronoi diagrams, such as sites of non-constant complexity, sites
that are not enclosed in their Voronoi regions, and empty Voronoi regions. The
diagram finds direct applications in VLSI computer-aided design.


title:
A Combinatorial $\tilde{O}(m^{3/2})$-time Algorithm for the Min-Cost
  Flow Problem

abstract:
  We present a combinatorial method for the min-cost flow problem and prove
that its expected running time is bounded by $\tilde O(m^{3/2})$. This matches
the best known bounds, which previously have only been achieved by numerical
algorithms or for special cases. Our contribution contains three parts that
might be interesting in their own right: (1) We provide a construction of an
equivalent auxiliary network and interior primal and dual points with potential
$P_0=\tilde{O}(\sqrt{m})$ in linear time. (2) We present a combinatorial
potential reduction algorithm that transforms initial solutions of potential
$P_0$ to ones with duality gap below $1$ in $\tilde O(P_0\cdot
\mbox{CEF}(n,m,\epsilon))$ time, where $\epsilon^{-1}=O(m^2)$ and
$\mbox{CEF}(n,m,\epsilon)$ denotes the running time of any combinatorial
algorithm that computes an $\epsilon$-approximate electrical flow. (3) We show
that solutions with duality gap less than $1$ suffice to compute optimal
integral potentials in $O(m+n\log n)$ time with our novel crossover procedure.
All in all, using a variant of a state-of-the-art $\epsilon$-electrical flow
solver, we obtain an algorithm for the min-cost flow problem running in $\tilde
O(m^{3/2})$.


title: Fisher zeros and RG flows for $SU(3)$ with $N_f$ flavors

abstract:
  We calculate the Fisher zeros for $SU(3)$ gauge theory with different $N_f$
flavors of staggered fermions for various values of the fermion mass. We
discuss the finite-size scaling near the end point of the line of discontinuity
of $\bar{\psi} \psi$ in the beta-mass plane and in the larger beta-lower mass
region. We discuss possible interpretations of these results in terms of
Wilsonian RG flows and their possible relevance to construct composite Higgs
models.


title: Diophantine equations with Euler polynomials

abstract:
  In this paper we determine possible decompositions of Euler polynomials
$E_k(x)$, i.e. possible ways of writing Euler polynomials as a functional
composition of polynomials of lower degree. Using this result together with the
well-known criterion of Bilu and Tichy, we prove that the Diophantine equation
$$-1^k +2 ^k - \cdots + (-1)^{x} x^k=g(y),$$ with $g\in \mathbb{Q}[X]$ of
degree at least $2$ and $k\geq 7$, has only finitely many integers solutions
$x, y$ unless polynomial $g$ can be decomposed in ways that we list explicitly.


title: A criterion for I-adic completeness

abstract:
  Let $I$ denote an ideal in a commutative Noetherian ring $R$. Let $M$ be an
$R$-module. The $I$-adic completion is defined by $\hat{M}^I =
\varprojlim{}_{\alpha} M/I^{\alpha}M$. Then $M$ is called $I$-adic complete
whenever the natural homomorphism $M \to \hat{M}^I$ is an isomorphism. Let $M$
be $I$-separated, i.e. $\cap_{\alpha} I^{\alpha}M = 0$. In the main result of
the paper it is shown that $M$ is $I$-adic complete if and only if
$\Ext_R^1(F,M) = 0$ for the flat test module $F = \oplus_{i = 1}^r R_{x_i}$
where $\{x_1,\ldots,x_r\}$ is a system of elements such that $\Rad I = \Rad \xx
R$. This result extends several known statements starting with C. U. Jensen's
result (see \cite[Proposition 3]{J}) that a finitely generated $R$-module $M$
over a local ring $R$ is complete if and only if $\Ext^1_R(F,M) = 0$ for any
flat $R$-module $F$.


title: Shape Optimization Problems for Metric Graphs

abstract:
  We consider the shape optimization problem $$\min\big\{{\mathcal E}(\Gamma)\
:\ \Gamma\in{\mathcal A},\ {\mathcal H}^1(\Gamma)=l\ \big\},$$ where ${\mathcal
H}^1$ is the one-dimensional Hausdorff measure and ${\mathcal A}$ is an
admissible class of one-dimensional sets connecting some prescribed set of
points ${\mathcal D}=\{D_1,\dots,D_k\}\subset{\mathbb R}^d$. The cost
functional ${\mathcal E}(\Gamma)$ is the Dirichlet energy of $\Gamma$ defined
through the Sobolev functions on $\Gamma$ vanishing on the points $D_i$. We
analyze the existence of a solution in both the families of connected sets and
of metric graphs. At the end, several explicit examples are discussed.


title: Bisimulation equivalence of first-order grammars is Ackermann-hard

abstract:
  Bisimulation equivalence (or bisimilarity) of first-order grammars is
decidable, as follows from the decidability result by Senizergues (1998, 2005)
that has been given in an equivalent framework of equational graphs with finite
out-degree, or of pushdown automata (PDA) with only deterministic and popping
epsilon-transitions. Benedikt, Goeller, Kiefer, and Murawski (2013) have shown
that the bisimilarity problem for PDA (even) without epsilon-transitions is
nonelementary. Here we show Ackermann-hardness for bisimilarity of first-order
grammars. The grammars do not use explicit epsilon-transitions, but they
correspond to the above mentioned PDA with (deterministic and popping)
epsilon-transitions, and this feature is substantial in the presented
lower-bound proof. The proof is based on a (polynomial) reduction from the
reachability problem of reset (or lossy) counter machines, for which the
Ackermann-hardness has been shown by Schnoebelen (2010); in fact, this
reachability problem is known to be Ackermann-complete in the hierarchy of
fast-growing complexity classes defined by Schmitz (2013).


title: Bi-Lipschitz Pieces between Manifolds

abstract:
  A well-known class of questions asks the following: If $X$ and $Y$ are metric
measure spaces and $f:X\rightarrow Y$ is a Lipschitz mapping whose image has
positive measure, then must $f$ have large pieces on which it is bi-Lipschitz?
Building on methods of David (who is not the present author) and Semmes, we
answer this question in the affirmative for Lipschitz mappings between certain
types of Ahlfors $s$-regular, topological $d$-manifolds. In general, these
manifolds need not be bi-Lipschitz embeddable in any Euclidean space. To prove
the result, we use some facts on the Gromov-Hausdorff convergence of manifolds
and a topological theorem of Bonk and Kleiner. This also yields a new proof of
the uniform rectifiability of some metric manifolds.


title: Lax monads, equipments and generalized multicategory theory

abstract:
  Generalized multicategories, also called $T$-monoids, are well known class of
mathematical structures, which include diverse set of examples. In this paper
we construct a generalization of the adjunction between strict monoidal
categories and multicategories, where the latter are replaced by $T$-monoids.
To do this we introduce lax monads in a 3-category, and establish their
relationship with equipments, which are bicategory like structures appropriate
for the generalized multicategory theory.


title: Blowfish Privacy: Tuning Privacy-Utility Trade-offs using Policies

abstract:
  Privacy definitions provide ways for trading-off the privacy of individuals
in a statistical database for the utility of downstream analysis of the data.
In this paper, we present Blowfish, a class of privacy definitions inspired by
the Pufferfish framework, that provides a rich interface for this trade-off. In
particular, we allow data publishers to extend differential privacy using a
policy, which specifies (a) secrets, or information that must be kept secret,
and (b) constraints that may be known about the data. While the secret
specification allows increased utility by lessening protection for certain
individual properties, the constraint specification provides added protection
against an adversary who knows correlations in the data (arising from
constraints). We formalize policies and present novel algorithms that can
handle general specifications of sensitive information and certain count
constraints. We show that there are reasonable policies under which our privacy
mechanisms for k-means clustering, histograms and range queries introduce
significantly lesser noise than their differentially private counterparts. We
quantify the privacy-utility trade-offs for various policies analytically and
empirically on real datasets.


title: Fragmentation model for expanding cylinder

abstract:
  A two-dimensional energy-based model of fragmentation of rapidly expanding
cylinder under plane strain conditions is proposed. The model allows us to
estimate the average fragment length and the number of fragments produced by
ductile fracture of the cylinder. Comparison of obtained results with published
experimental data on the fragmentation of the aluminum rings and cylinders
shows that they are in good agreement.


title: Shape optimization problems on metric measure spaces

abstract:
  We consider shape optimization problems of the form $$\min\big\{J(\Omega)\ :\
\Omega\subset X,\ m(\Omega)\le c\big\},$$ where $X$ is a metric measure space
and $J$ is a suitable shape functional. We adapt the notions of
$\gamma$-convergence and weak $\gamma$-convergence to this new general abstract
setting to prove the existence of an optimal domain. Several examples are
pointed out and discussed.


title: Simplifying instanton corrections to N=4 SYM correlators

abstract:
  We compute instanton corrections to non-minimal correlation functions of
chiral primary operators in the N=4 super Yang-Mills super-current multiplet.
Using a representation in terms of Mellin integrals, we find that these
corrections can be written as conformal integrals in AdS_5 times certain
"kinematic" prefactors that are independent of the instanton moduli. We then
consider the consecutive, pairwise light-like limit x_{i, i+1}^2 -> 0 of such
correlators, and prove that the ratio between the instanton contribution and
the corresponding tree-level expression vanishes in this limit. We also
speculate on the extension to the non-perturbative level of the proposed
duality with polygonal Wilson loops and briefly discuss its potential
implications for scattering amplitudes.


title: On the Market Viability under Proportional Transaction Costs

abstract:
  This paper studies the market viability with proportional transaction costs.
Instead of requiring the existence of strictly consistent price systems (SCPS)
as in the literature, we show that strictly consistent local martingale systems
(SCLMS) can successfully serve as the dual elements such that the market
viability can be verified. We introduce two weaker notions of no arbitrage
conditions on market models named no unbounded profit with bounded risk (NUPBR)
and no local arbitrage with bounded portfolios (NLABP). In particular, we show
that the NUPBR and NLABP conditions in the robust sense for the smaller bid-ask
spreads is the equivalent characterization of the existence of SCLMS for
general market models. We also discuss the implications for the utility
maximization problem.


title: The McKay correspondence, tilting equivalences, and rationality

abstract:
  We consider the problem of comparing t-structures under the derived McKay
correspondence and for tilting equivalences. We relate the t-structures using
certain natural torsion theories. As an application, we give a criterion for
rationality for surfaces with a tilting bundle. In particular we show that
every smooth projective surface which admits a full, strong, exceptional
collection of line bundles is rational.


title:
Self-regulating genes. Exact steady state solution by using Poisson
  Representation

abstract:
  Systems biology studies the structure and behavior of complex gene regulatory
networks. One of its aims is to develop a quantitative understanding of the
modular components that constitute such networks. The self-regulating gene is a
type of auto regulatory genetic modules which appears in over 40% of known
transcription factors in E. coli. In this work, using the technique of Poisson
Representation, we are able to provide exact steady state solutions for this
feedback model. By using the methods of synthetic biology (P.E.M. Purnick and
Weiss, R., Nature Reviews, Molecular Cell Biology, 2009, 10: 410-422) one can
build the system itself from modules like this.


title: Non-Markovianity of a quantum emitter in front of a mirror

abstract:
  We consider a quantum emitter ("atom") radiating in a one-dimensional (1D)
photonic waveguide in the presence of a single mirror, resulting in a delay
differential equation for the atomic amplitude. We carry out a systematic
analysis of the non-Markovian (NM) character of the atomic dynamics in terms of
refined, recently developed notions of quantum non-Markovianity such as
indivisibility and information back-flow. NM effects are quantified as a
function of the round-trip time and phase shift associated with the atom-mirror
optical path. We find, in particular, that unless an atom-photon bound state is
formed a finite time delay is always required in order for NM effects to be
exhibited. This identifies a finite threshold in the parameter space, which
separates the Markovian and non-Markovian regimes.


title:
A Relaxed-Projection Splitting Algorithm for Variational Inequalities in
  Hilbert Spaces

abstract:
  We introduce a relaxed-projection splitting algorithm for solving variational
inequalities in Hilbert spaces for the sum of nonsmooth maximal monotone
operators, where the feasible set is defined by a nonlinear and nonsmooth
continuous convex function inequality. In our scheme, the orthogonal
projections onto the feasible set are replaced by projections onto separating
hyperplanes. Furthermore, each iteration of the proposed method consists of
simple subgradient-like steps, which does not demand the solution of a
nontrivial subproblem, using only individual operators, which exploits the
structure of the problem. Assuming monotonicity of the individual operators and
the existence of solutions, we prove that the generated sequence converges
weakly to a solution.


title:
Topology and Criticality in Resonating Affleck-Kennedy-Lieb-Tasaki loop
  Spin Liquid States

abstract:
  We exploit a natural Projected Entangled-Pair State (PEPS) representation for
the resonating Affleck-Kennedy-Lieb-Tasaki loop (RAL) state. By taking
advantage of PEPS-based analytical and numerical methods, we characterize the
RAL states on various two-dimensional lattices. On square and honeycomb
lattices, these states are critical since the dimer-dimer correlations decay as
a power law. On kagome lattice, the RAL state has exponentially decaying
correlation functions, supporting the scenario of a gapped spin liquid. We
provide further evidence that the RAL state on the kagome lattice is a
$\mathbb{Z}_2$ spin liquid, by identifying the four topological sectors and
computing the topological entropy. Furthermore, we construct a one-parameter
family of PEPS states interpolating between the RAL state and a short-range
Resonating Valence Bond state and find a critical point, consistent with the
fact that the two states belong to two different phases. We also perform a
variational study of the spin-1 kagome Heisenberg model using this
one-parameter PEPS.


title: Esnault-Levine-Wittenberg indices

abstract:
  These are extended notes of a lecture about the papers 1207.1883 by
Esnault-Levine-Wittenberg and 1308.3024 by Wittenberg. The aim is to define the
Esnault-Levine-Wittenberg indices, establish their basic properties amd to pose
several questions. v.2: references updated.


title: The symplectic displacement energy

abstract:
  We define the symplectic displacement energy of a non-empty subset of a
compact symplectic manifold as the infimum of the Hofer-like norm [5] of
symplectic diffeomorphisms that displace the set. We show that this energy
(like the usual displacement energy defined using Hamiltonian diffeomorphisms)
is a strictly positive number on sets with non-empty interior. As a consequence
we prove a result justifying the introduction of the notion of strong
symplectic homeomorphisms [4].


title:
The Gaia-ESO Survey: Reevaluation of the parameters of the open cluster
  Trumpler 20 using photometry and spectroscopy

abstract:
  Trumpler 20 is an old open cluster (OC) located toward the Galactic centre,
at about 3 kpc from the Sun and $\sim$7 kpc from the Galactic centre. Its
position makes this cluster particularly interesting in the framework of the
chemical properties of the Galactic disc because very few old OCs reside in the
inner part of the disc. For this reason it has been selected as a cluster
target of the Gaia-ESO Survey, and spectra of many stars in the main sequence
and red clump phases are now available. Moreover, although it has been studied
by several authors in the past, no consensus on the evolutionary status of Tr
20 has been reached. The heavy contamination of field stars (the line of sight
of Tr 20 crosses the Carina spiral arm) complicates a correct interpretation.
Another interesting aspect of the cluster is that it shows a broadened
main-sequence turn-off and a prominent and extended red-clump, characteristics
that are not easily explained by classical evolutionary models. Exploiting both
spectroscopic information from the Gaia-ESO Survey (and the ESO archive) and
literature photometry, we obtain a detailed and accurate analysis of the
properties of the cluster. We make use of the first accurate metallicity
measurement ever obtained from several spectra of red clump stars, and of
cluster membership determination using radial velocities. According to the
evolutionary models adopted, we find that Tr 20 has an age in the range
1.35-1.66 Gyr, an average reddening $E(B-V)$ in the range 0.31-0.35 mag, and a
distance modulus $(m-M)_0$ between 12.64 and 12.72 mag. The spectroscopic
metallicity is [Fe/H]=+0.17 dex. We discuss the structural properties of the
object and constrain possible hypotheses for its broadened upper main sequence
by estimating the effect of differential reddening and its extended red clump.


title: Extinction risk and conservation of the world's sharks and rays

abstract:
  The rapid expansion of human activities threatens ocean-wide biodiversity
loss. Numerous marine animal populations have declined, yet it remains unclear
whether these trends are symptomatic of a chronic accumulation of global marine
extinction risk. We present the first systematic analysis of threat for a
globally-distributed lineage of 1,041 chondrichthyan fishes - sharks, rays, and
chimaeras. We estimate that one-quarter are threatened according to IUCN Red
List criteria due to overfishing (targeted and incidental). Large-bodied,
shallow-water species are at greatest risk and five out of the seven most
threatened families are rays. Overall chondrichthyan extinction risk is
substantially higher than for most other vertebrates, and only one-third of
species are considered safe. Population depletion has occurred throughout the
world's ice-free waters, but is particularly prevalent in the Indo-Pacific
Biodiversity Triangle and Mediterranean Sea. Improved management of fisheries
and trade is urgently needed to avoid extinctions and promote population
recovery.


title: Strong Turing Degrees for Additive BSS RAM's

abstract:
  For the additive real BSS machines using only constants 0 and 1 and order
tests we consider the corresponding Turing reducibility and characterize some
semi-decidable decision problems over the reals. In order to refine,
step-by-step, a linear hierarchy of Turing degrees with respect to this model,
we define several halting problems for classes of additive machines with
different abilities and construct further suitable decision problems. In the
construction we use methods of the classical recursion theory as well as
techniques for proving bounds resulting from algebraic properties. In this way
we extend a known hierarchy of problems below the halting problem for the
additive machines using only equality tests and we present a further
subhierarchy of semi-decidable problems between the halting problems for the
additive machines using only equality tests and using order tests,
respectively.


title:
Study of X-ray radiation damage in the AGIPD sensor for the European
  XFEL

abstract:
  The European X-ray Free Electron Laser (XFEL), currently being constructed in
Hamburg and planning to be operational in 2017 for users, will deliver 27,000
fully coherent, high brilliance X-ray pulses per second with duration less than
100 fs. The unique features of the X-ray beam pose major challenges for
detectors used at the European XFEL for imaging experiments, in particular a
radiation tolerance of silicon sensors for doses up to 1 GGy for 3 years of
operation at an operating voltage above 500 V. One of the detectors under
development at the European XFEL is the Adaptive Gain Integrating Pixel
Detector (AGIPD), which is a hybrid detector system with ASICs bump-bonded to
p+n silicon pixel sensors. We have designed the silicon sensors for the AGIPD,
which have been fabricated by SINTEF and delivered in the beginning of February
of 2013. To demonstrate the performance of the AGIPD sensor with regard to
radiation hardness, mini-sensors with the same pixel and guard-ring designs as
the AGIPD together with test structures have been irradiated at the beamline
P11 of PETRA III with 8 keV and 12 keV monoenergetic X-rays to dose values up
to 10 MGy. The radiation hardness of the AGIPD sensor has been proven and all
electrical properties are within specification before and after irradiation. In
addition, the oxide-charge density and surface-current density from test
structures have been characterized as function of the X-ray dose and compared
to previous measurements for test structures produced by four vendors.


title:
The X-ray Properties of Five Galactic Supernova Remnants Detected by the
  Spitzer GLIMPSE Survey

abstract:
  (Abbreviated) We present a study of the X-ray properties of five Galactic
supernova remnants (SNRs) -- Kes 17 (G304.6$+$0.1), G311.5$-$0.3, G346.6$-$0.2,
CTB 37A (G348.5$+$0.1) and G348.5$-$0.0 -- that were detected in the infrared
by Reach et al. (2006) in an analysis of data from the Galactic Legacy Infrared
Mid-Plane Survey Extraordinaire (GLIMPSE) that was conducted by the Spitzer
Space Telescope. We present and analyze archival ASCA observations of Kes 17,
G311.5$-$0.3 and G346.6$-$0.2, archival XMM-Newton observations of Kes 17, CTB
37A and G348.5$-$0.0 and an archival Chandra observation of CTB 37A. All of the
SNRs are clearly detected in the X-ray possibly except for G348.5$-$0.0. Our
study reveals that the four detected SNRs all feature center-filled X-ray
morphologies and that the observed emission from these sources is thermal in
all cases. We argue that these SNRs should be classified as mixed-morphology
SNRs (MM SNRs): our study strengthens the correlation between MM SNRs and SNRs
interacting with molecular clouds and suggests that the origin of
mixed-morphology SNRs may be due to the interactions between these SNRs and
adjacent clouds. Our ASCA analysis of G311.5$-$0.3 reveals for the first time
X-ray emission from this SNR: the X-ray emission is center-filled within the
radio and infrared shells and thermal in nature ($kT$ $\sim$ 0.98 keV), thus
motivating its classification as an MM SNR. We find considerable spectral
variations in the properties associated with the plasmas of the other
X-ray-detected SNRs, such as a possible overabundance of magnesium in the
plasma of Kes 17. Finally, we also estimate such properties as electron density
$n$$_e$, radiative age $t$$_{rad}$ and swept-up mass $M$$_X$ for each of the
four X-ray-detected SNRs.


title:
Analysis of the $E_{1}$ and $E_{1}$ +${\Delta}_{1}$ optical transitions
  in (Ga,Mn)As epitaxial layers

abstract:
  The diluted (Ga,Mn)As became a model ferromagnetic semiconductor, however
there is still a disagreement on the source of its magnetism. The divergences
arise from the results indicating that the holes mediated ferromagnetism reside
in the valence band or the impurity band. Full understanding of character of
the Mn states in GaAs can bring the increase of (Ga,Mn)As Curie temperature. In
this paper we verify the ellipsometric results and compare with more precise
photoreflectance method which gives a new insight into the interactions of Mn
impurity states with GaAs valence band. Indeed, $E_{1}$ and
$E_{1}$+${\Delta}_{1}$ inter-band transition energies for highly doped and
annealed (Ga,Mn)As epitaxial layers have not confirmed the interaction between
detached Mn impurity band and the valence band. Thus, the description with
merged Mn states and GaAs valence band is in agreement with our results. Our
findings are supported by the high resolution transmission microscopy and
magnetization measurements.


title: Reversible Dynamics in Strongly Non-Local Boxworld Systems

abstract:
  In order to better understand the structure of quantum theory, or speculate
about theories that may supercede it, it can be helpful to consider alternative
physical theories. ``Boxworld'' describes one such theory, in which all
non-signaling correlations are achievable. In a limited class of multipartite
Boxworld systems - wherein all subsystems are identical and all measurements
have the same number of outcomes - it has been demonstrated that the set of
reversible dynamics is `trivial', generated solely by local relabellings and
permutations of subsystems. We develop the convex formalism of Boxworld to give
an alternative proof of this result, then extend this proof to all multipartite
Boxworld systems, and discuss the potential relevance to other theories. These
results lend further support to the idea that the rich reversible dynamics in
quantum theory may be the key to understanding its structure and its
informational capabilities.


title: Weighing the Neutrino

abstract:
  We investigate the potential of short-baseline experiments in order to
measure the dispersion relation of the (muon) neutrino, with a prospect of
eventually measuring the neutrino mass. As a byproduct, the experiment would
help to constrain parameters of Lorentz-violating effects in the neutrino
sector. The potential of a high-flux laser-accelerated proton beam (e.g., at
the upcoming ELI facility), incident on a thick target composed of a light
element to produce pions, with a subsequent decay to muons and muon-neutrinos,
is discussed. We find a possibility for a muon neutrino mass measurement of
unprecedented accuracy.


title: Proposal for demonstrating the Hong-Ou-Mandel effect with matter waves

abstract:
  The Hong-Ou-Mandel (HOM) effect is a striking demonstration of destructive
quantum interference between pairs of indistinguishable bosons, realised so far
only with massless photons. Here we propose an experiment which can realise
this effect in the matter-wave regime using pair-correlated atoms produced via
a collision of two Bose-Einstein condensates and subjected to two laser induced
Bragg pulses. We formulate a novel measurement protocol appropriate for the
multimode matter-wave field, which---unlike the typical two-mode optical
case---bypasses the need for repeated measurements under different displacement
settings of the beam-splitter, thus dramatically reducing the number of
experimental runs required to map out the interference visibility. The protocol
can be utilised in related matter-wave schemes; here we focus on condensate
collisions and by simulating the entire experiment we predict a HOM-dip
visibility of ~69%. By being larger than 50%, such a visibility highlights
strong quantum correlations between the atoms and paves the way for a possible
demonstration of a Bell inequality violation with massive particles in a
related Rarity-Tapster setup.


title:
Probing Intergalactic Neutral Hydrogen by the Lyman Alpha Red Damping
  Wing of Gamma-Ray Burst 130606A Afterglow Spectrum at z = 5.913

abstract:
  The unprecedentedly bright optical afterglow of GRB 130606A located by Swift
at a redshift close to the reionization era (z = 5.913) provides a new
opportunity to probe the ionization status of intergalactic medium (IGM). Here
we present an analysis of the red Ly alpha damping wing of the afterglow
spectrum taken by Subaru/FOCAS during 10.4-13.2 hr after the burst. We find
that the minimal model including only the baseline power-law and HI absorption
in the host galaxy does not give a good fit, leaving residuals showing concave
curvature in 8400-8900 A with an amplitude of about 0.6% of the flux. Such a
curvature in the short wavelength range cannot be explained either by
extinction at the host with standard extinction curves, intrinsic curvature of
afterglow spectra, or by the known systematic uncertainties in the observed
spectrum. The red damping wing by intervening HI gas outside the host can
reduce the residual by about 3 sigma statistical significance. We find that a
damped Ly alpha system is not favored as the origin of this intervening HI
absorption, from the observed Ly beta and metal absorption features. Therefore
absorption by diffuse IGM remains as a plausible explanation. A fit by a simple
uniform IGM model requires HI neutral fraction of f_HI ~ 0.1-0.5 depending on
the distance to the GRB host, implying high f_HI IGM associated with the
observed dark Gunn-Peterson (GP) troughs. This gives a new evidence that the
reionization is not yet complete at z ~ 6.


title: Classification of the algebras $\mathbb{O}_{p,q}$

abstract:
  We study a series of real nonassociative algebras $\mathbb{O}_{p,q}$
introduced in $[5]$. These algebras have a natural $\mathbb{Z}_2^n$-grading,
where $n=p+q$, and they are characterized by a cubic form over the field
$\mathbb{Z}_2$. We establish all the possible isomorphisms between the algebras
$\mathbb{O}_{p,q}$ preserving the structure of $\mathbb{Z}_2^n$-graded algebra.
The classification table of $\mathbb{O}_{p,q}$ is quite similar to that of the
real Clifford algebras $\mathrm{Cl}_{p,q}$, the main difference is that the
algebras $\mathbb{O}_{n,0}$ and $\mathbb{O}_{0,n}$ are exceptional.


title:
Delocalization for the 3-D discrete random Schroedinger operator at weak
  disorder

abstract:
  We apply a recently developed approach (Liaw 2013) to study the existence of
extended states for the three dimensional discrete random Schroedinger operator
at small disorder. The conclusion of delocalization at small disorder agrees
with other numerical and experimental observations. Further the work furnishes
a verification of the numerical approach and its implementation.
  Not being based on scaling theory, this method eliminates problems due to
boundary conditions, common to previous numerical methods in the field. At the
same time, as with any numerical experiment, one cannot exclude finite-size
effects with complete certainty. Our work can be thought of as a new and quite
different use of Lanczos' algorithm; a posteriori tests to show that the
orthogonality loss is very small.
  We numerically track the "bulk distribution" (here: the distribution of where
we most likely find an electron) of a wave packet initially located at the
origin, after iterative application of the discrete random Schroedinger
operator.


title: Rate exact Bayesian adaptation with modified block priors

abstract:
  A novel block prior is proposed for adaptive Bayesian estimation. The prior
does not depend on the smoothness of the function or the sample size. It puts
sufficient prior mass near the true signal and automatically concentrates on
its effective dimension. A rate-optimal posterior contraction is obtained in a
general framework, which includes density estimation, white noise model,
Gaussian sequence model, Gaussian regression and spectral density estimation.


title: Transparent Checkpoint-Restart over InfiniBand

abstract:
  InfiniBand is widely used for low-latency, high-throughput cluster computing.
Saving the state of the InfiniBand network as part of distributed checkpointing
has been a long-standing challenge for researchers. Because of a lack of a
solution, typical MPI implementations have included custom checkpoint-restart
services that "tear down" the network, checkpoint each node as if the node were
a standalone computer, and then re-connect the network again. We present the
first example of transparent, system-initiated checkpoint-restart that directly
supports InfiniBand. The new approach is independent of any particular Linux
kernel, thus simplifying the current practice of using a kernel-based module,
such as BLCR. This direct approach results in checkpoints that are found to be
faster than with the use of a checkpoint-restart service. The generality of
this approach is shown not only by checkpointing an MPI computation, but also a
native UPC computation (Berkeley Unified Parallel C), which does not use MPI.
Scalability is shown by checkpointing 2,048 MPI processes across 128 nodes
(with 16 cores per node). In addition, a cost-effective debugging approach is
also enabled, in which a checkpoint image from an InfiniBand-based production
cluster is copied to a local Ethernet-based cluster, where it can be restarted
and an interactive debugger can be attached to it. This work is based on a
plugin that extends the DMTCP (Distributed MultiThreaded CheckPointing)
checkpoint-restart package.


title: From Coulomb Blockade to Resonant Transmission in a MoS2 Nanoribbon

abstract:
  We have measured a nanoribbon of MoS2 at low temperature, and observed the
evolution of the system from a regime of multiple small quantum dots in series
to one where the entire nanoribbon acts as a single quantum dot. At higher
Fermi energies, resonant transmission through disorder-induced potential wells
is evident. Our findings shed light on the length scale of quasi-ballistic
transport in the material.


title:
A geometric classification of the path components of the space of
  locally stable maps $S^3\to \mathbb{R}^4$

abstract:
  Locally stable maps $S^3\to\mathbb{R}^4$ are classified up to homotopy
through locally stable maps. The equivalence class of a map $f$ is determined
by three invariants: the isotopy class $\sigma(f)$ of its framed singularity
link, the generalized normal degree $\nu(f)$, and the algebraic number of cusps
$\kappa(f)$ of any extension of $f$ to a locally stable map of the $4$-disk
into $\mathbb{R}^5$. Relations between the invariants are described, and it is
proved that for any $\sigma$, $\nu$, and $\kappa$ which satisfy these
relations, there exists a map $f:S^3\to\mathbb{R}^4$ with $\sigma(f)=\sigma$,
$\nu(f)=\nu$, and $\kappa(f)=\kappa$. It follows in particular that every
framed link in $S^3$ is the singularity set of some locally stable map into
$\mathbb{R}^4$.


title:
Magnetic fields in Accretion Discs around Neutron Stars - Consequences
  for the change of spin

abstract:
  Accretion disks are ubiquitous in the universe and it is generally accepted
that magnetic fields play a pivotal role in accretion-disk physics. The spin
history of millisecond pulsars, which are usually classified as magnetized
neutron stars spun up by an accretion disk, depends sensitively on the magnetic
field structure, and yet highly idealized models from the 80s are still being
used for calculating the magnetic field components. We present a possible way
of improving the currently used models with a semi-analytic approach. The
resulting magnetic field profile of both the poloidal and the toroidal
component can be very different from the one suggested previously. This might
dramatically change our picture of which parts of the disk tend to spin the
star up or down.


title:
The geometric origin of Lie point symmetries of the Schr\"{o}dinger and
  the Klein Gordon equations

abstract:
  We determine the Lie point symmetries of the Schr\"{o}dinger and the Klein
Gordon equations in a general Riemannian space. It is shown that these
symmetries are related with the homothetic and the conformal algebra of the
metric of the space respectively. We consider the kinematic metric defined by
the classical Lagrangian and show how the Lie point symmetries of the
Schr\"{o}dinger equation and the Klein Gordon equation are related with the
Noether point symmetries of this Lagrangian. The general results are applied to
two practical problems a. The classification of all two and three dimensional
potentials in a Euclidian space for which the Schr\"{o}dinger equation and the
Klein Gordon equation admit Lie point symmetries and b. The application of Lie
point symmetries of the Klein Gordon equation in the exterior Schwarzschild
spacetime and the determination of the metric by means of conformally related
Lagrangians.


title:
Kepler-91b: a planet at the end of its life. Planet and giant host star
  properties via light-curve variations

abstract:
  The evolution of planetary systems is intimately linked to the evolution of
their host star. Our understanding of the whole planetary evolution process is
based on the large planet diversity observed so far. To date, only few tens of
planets have been discovered orbiting stars ascending the Red Giant Branch.
Although several theories have been proposed, the question of how planets die
remains open due to the small number statistics. In this work we study the
giant star Kepler-91 (KOI-2133) in order to determine the nature of a
transiting companion. This system was detected by the Kepler Space Telescope.
However, its planetary confirmation is needed. We confirm the planetary nature
of the object transiting the star Kepler-91 by deriving a mass of $
M_p=0.88^{+0.17}_{-0.33} ~M_{\rm Jup}$ and a planetary radius of
$R_p=1.384^{+0.011}_{-0.054} ~R_{\rm Jup}$. Asteroseismic analysis produces a
stellar radius of $R_{\star}=6.30\pm 0.16 ~R_{\odot}$ and a mass of
$M_{\star}=1.31\pm 0.10 ~ M_{\odot} $. We find that its eccentric orbit
($e=0.066^{+0.013}_{-0.017}$) is just $1.32^{+0.07}_{-0.22} ~ R_{\star}$ away
from the stellar atmosphere at the pericenter. Kepler-91b could be the previous
stage of the planet engulfment, recently detected for BD+48 740. Our
estimations show that Kepler-91b will be swallowed by its host star in less
than 55 Myr. Among the confirmed planets around giant stars, this is the
planetary-mass body closest to its host star. At pericenter passage, the star
subtends an angle of $48^{\circ}$, covering around 10% of the sky as seen from
the planet. The planetary atmosphere seems to be inflated probably due to the
high stellar irradiation.


title:
Discovery of a transparent sightline at {\rho} < 20 kpc from an
  interacting pair of galaxies

abstract:
  We report the discovery of a transparent sightline at projected distances of
{\rho} < 20 kpc to an interacting pair of mature galaxies at z = 0.12. The
sightline of the UV-bright quasar PG1522+101 at z = 1.328 passes at {\rho} =
11.5 kpc from the higher-mass galaxy (M_* = 10^10.6 M_Sun) and {\rho} = 20.4
kpc from the lower-mass one (M_* = 10^10.0 M_Sun). The two galaxies are
separated by 9 kpc in projected distance and 30 km/s in line-of-sight velocity.
Deep optical images reveal tidal features indicative of close interactions.
Despite the small projected distances, the quasar sightline shows little
absorption associated with the galaxy pair with a total HI column density it no
greater than log N(HI) = 13.65. This limiting HI column density is already two
orders-of-magnitude less than what is expected from previous halo gas studies.
In addition, we detect no heavy-element absorption features associated with the
galaxy pair with 3-{\sigma} limits of log N(MgII) < 12.2 and log N(OVI) < 13.7.
The probability of seeing such little absorption in a sightline passing at a
small projected distance from two non-interacting galaxies is 0.2%. The absence
of strong absorbers near the close galaxy pair suggests that the cool gas
reservoirs of the galaxies have been significantly depleted by the galaxy
interaction. These observations therefore underscore the potential impact of
galaxy interactions on the gaseous halos around galaxies.


title:
Combined Flux and Anisotropy Searches Improve Sensitivity to Gamma Rays
  from Dark Matter

abstract:
  Searches for dark matter annihilation signals in the diffuse gamma-ray
background are promising. We present the first comprehensive study utilizing
both flux and anisotropy, using the example of a spectral line signal. Besides
improving sensitivity, a combined analysis will help separately determine the
particle properties of dark matter and the cosmological aspects of its clumping
into halo substructure. The significance of a signal in a shot-noise-dominated
anisotropy analysis increases linearly with time $t$, as opposed to $\sqrt{t}$
for a flux analysis, so a flux hint might be confirmed with an anisotropy
signal. A first combined line search with Fermi-LAT would provide powerful new
sensitivity; one with the proposed GAMMA-400 would be dramatically better.

categories: astro-ph.HE astro-ph.CO astro-ph.GA hep-ex hep-ph


title:
Evaluating Gyrochronology on the Zero-Age-Main-Sequence: Rotation
  Periods in the Southern Open Cluster Blanco 1 from the KELT-South Survey

abstract:
  We report periods for 33 members of Blanco 1 as measured from KELT-South
light curves, the first reported rotation periods for this benchmark
zero-age-main-sequence open cluster. The distribution of these stars spans from
late-A or early-F dwarfs to mid-K with periods ranging from less than a day to
~8 days. The rotation period distribution has a morphology similar to the
coeval Pleiades cluster, suggesting the universal nature of stellar rotation
distributions. Employing two different gyrochronology methods, we find an age
of 146+13-14 Myr for the cluster. Using the same techniques, we infer an age of
134+9-10 Myr for the Pleiades measured from existing literature rotation
periods. These rotation-derived ages agree with independently determined
cluster ages based on the lithium depletion boundary technique. Additionally,
we evaluate different gyrochronology models, and quantify levels of agreement
between the models and the Blanco 1/Pleiades rotation period distributions,
including incorporating the rotation distributions of clusters at ages up to
1.1 Gyr. We find the Skumanich-like spin-down rate sufficiently describes the
rotation evolution of stars hotter than the Sun; however, we find cooler stars
rotating faster than predicted by a Skumanich-law, suggesting a mass dependence
in the efficiency of stellar angular momentum loss rate. Finally, we compare
the Blanco 1 and Pleiades rotation period distributions to available non-linear
angular momentum evolution models. We find they require a significant mass
dependence on the initial rotation rate of solar-type stars to reproduce the
observed range of rotation periods at a given stellar mass, and are furthermore
unable to predict the observed over-density of stars along the upper-envelope
of the clusters' rotation distributions.


title: Soft X-ray Excess in the Coma Cluster from a Cosmic Axion Background

abstract:
  We show that the soft X-ray excess in the Coma cluster can be explained by a
cosmic background of relativistic axions converting into photons in the cluster
magnetic field. We provide a detailed self-contained review of the cluster soft
X-ray excess, the proposed astrophysical explanations and the problems they
face, and explain how a 0.1-1 keV axion background naturally arises at
reheating in many string theory models of the early universe. We study the
morphology of the soft excess by numerically propagating axions through
stochastic, multi-scale magnetic field models that are consistent with
observations of Faraday rotation measures from Coma. By comparing to ROSAT
observations of the 0.2-0.4 keV soft excess, we find that the overall excess
luminosity is easily reproduced for $g_{a\gamma\gamma} \sim 2 \times 10^{-13}$
GeV$^{-1}$. The resulting morphology is highly sensitive to the magnetic field
power spectrum. For Gaussian magnetic field models, the observed soft excess
morphology prefers magnetic field spectra with most power in coherence lengths
on ${\cal O}(3 {\rm ~kpc})$ scales over those with most power on ${\cal O}(12
{\rm ~kpc})$ scales. Within this scenario, we bound the mean energy of the
axion background to $50\, {\rm eV}\lesssim \langle E_a \rangle \lesssim 250\,
{\rm eV}$, the axion mass to $m_a \lesssim 10^{-12}\,\hbox{eV}$, and derive a
lower bound on the axion-photon coupling $g_{a\gamma\gamma} \gtrsim
\sqrt{0.5/\Delta N_{\rm eff}}\, 1.4 \times 10^{-13}$ GeV$^{-1}$.


title: Compressed convolution

abstract:
  We introduce the concept of compressed convolution, a technique to convolve a
given data set with a large number of non-orthogonal kernels. In typical
applications our technique drastically reduces the effective number of
computations. The new method is applicable to convolutions with symmetric and
asymmetric kernels and can be easily controlled for an optimal trade-off
between speed and accuracy. It is based on linear compression of the collection
of kernels into a small number of coefficients in an optimal eigenbasis. The
final result can then be decompressed in constant time for each desired
convolved output. The method is fully general and suitable for a wide variety
of problems. We give explicit examples in the context of simulation challenges
for upcoming multi-kilo-detector cosmic microwave background (CMB) missions.
For a CMB experiment with O(10,000) detectors with similar beam properties, we
demonstrate that the algorithm can decrease the costs of beam convolution by
two to three orders of magnitude with negligible loss of accuracy. Likewise, it
has the potential to allow the reduction of disk space required to store signal
simulations by a similar amount. Applications in other areas of astrophysics
and beyond are optimal searches for a large number of templates in noisy data,
e.g. from a parametrized family of gravitational wave templates; or calculating
convolutions with highly overcomplete wavelet dictionaries, e.g. in methods
designed to uncover sparse signal representations.


title: The Next-to-Minimal Two Higgs Doublet Model

abstract:
  The simplest extension of the Two Higgs Doublet Model is the addition of a
real scalar singlet, S. The effects of mixing between the singlet and the
doublets can be manifested in two ways. It can modify the couplings of the 126
GeV Higgs boson, h, and it can lead to direct detection of the heavy Higgs at
the LHC. In this paper, we show that in the type-I model, for heavy Higgs
masses in the 200-600 GeV range, the latter effect will be detected earlier
than the former for most of parameter space. Should no such Higgs be discovered
in this mass range, then the upper limit on the mixing will be sufficiently
strong such that there will be no significant effects on the couplings of the h
for most of parameter space. The reverse is true in the type-II model, the
limits from measurements of the couplings of the h will dominate over the
limits from non-observation of the heavy Higgs.


title:
X-ray properties of K-selected galaxies at 0.5<z<2.0: Investigating
  trends with stellar mass, redshift and spectral type

abstract:
  We examine how the total X-ray luminosity correlates with stellar mass,
stellar population, and redshift for a K-band limited sample of ~3500 galaxies
at 0.5<z<2.0 from the NEWFIRM Medium Band Survey in the COSMOS field. The
galaxy sample is divided into 32 different galaxy types, based on similarities
between the spectral energy distributions. For each galaxy type, we further
divide the sample into bins of redshift and stellar mass, and perform an X-ray
stacking analysis using the Chandra COSMOS (C-COSMOS) data. We find that full
band X-ray luminosity is primarily increasing with stellar mass, and at similar
mass and spectral type is higher at larger redshifts. When comparing at the
same stellar mass, we find that the X-ray luminosity is slightly higher for
younger galaxies (i.e., weaker 4000\AA breaks), but the scatter in this
relation is large. We compare the observed X-ray luminosities to those expected
from low and high mass X-ray binaries (XRBs). For blue galaxies, XRBs can
almost fully account for the observed emission, while for older galaxies with
larger 4000\AA breaks, active galactic nuclei (AGN) or hot gas dominate the
measured X-ray flux. After correcting for XRBs, the X-ray luminosity is still
slightly higher in younger galaxies, although this correlation is not
significant. AGN appear to be a larger component of galaxy X-ray luminosity at
earlier times, as the hardness ratio increases with redshift. Together with the
slight increase in X-ray luminosity this may indicate more obscured AGNs or
higher accretion rates at earlier times.


title:
A Sub-Earth-Mass Moon Orbiting a Gas Giant Primary or a High Velocity
  Planetary System in the Galactic Bulge

abstract:
  We present the first microlensing candidate for a free-floating
exoplanet-exomoon system, MOA-2011-BLG-262, with a primary lens mass of M_host
~ 4 Jupiter masses hosting a sub-Earth mass moon. The data are well fit by this
exomoon model, but an alternate star+planet model fits the data almost as well.
Nevertheless, these results indicate the potential of microlensing to detect
exomoons, albeit ones that are different from the giant planet moons in our
solar system. The argument for an exomoon hinges on the system being relatively
close to the Sun. The data constrain the product M pi_rel, where M is the lens
system mass and pi_rel is the lens-source relative parallax. If the lens system
is nearby (large pi_rel), then M is small (a few Jupiter masses) and the
companion is a sub-Earth-mass exomoon. The best-fit solution has a large
lens-source relative proper motion, mu_rel = 19.6 +- 1.6 mas/yr, which would
rule out a distant lens system unless the source star has an unusually high
proper motion. However, data from the OGLE collaboration nearly rule out a high
source proper motion, so the exoplanet+exomoon model is the favored
interpretation for the best fit model. However, the alternate solution has a
lower proper motion, which is compatible with a distant (so stellar) host. A
Bayesian analysis does not favor the exoplanet+exomoon interpretation, so
Occam's razor favors a lens system in the bulge with host and companion masses
of M_host = 0.12 (+0.19 -0.06) M_solar and m_comp = 18 (+28 -100 M_earth, at a
projected separation of a_perp ~ 0.84 AU. The existence of this degeneracy is
an unlucky accident, so current microlensing experiments are in principle
sensitive to exomoons. In some circumstances, it will be possible to
definitively establish the low mass of such lens systems through the
microlensing parallax effect. Future experiments will be sensitive to less
extreme exomoons.


title: On a shadow system of the S-K-T competition system

abstract:
  We study a boundary value problem with an integral constraint that arises
from the modelings of species competition proposed by Lou and Ni in \cite{LN2}.
Through bifurcation theories, we obtain the existence of non-constant positive
solutions over one-dimensional domain, which are small perturbations from the
positive constant solution of the system. Moreover, we determine the stability
of the bifurcating solutions. Finally, for the diffusion rate being
sufficiently small, we construct infinitely many positive solutions with single
transition layer, which is represented as an approximation of a step function
that. The transition-layer solution can be used to model the phenomenon of
species segregation through competitions.


title:
Green Bank Telescope observations of low column density HI around NGC
  2997 and NGC 6946

abstract:
  Observations of ongoing HI accretion in nearby galaxies have only identified
about 10% of the needed fuel to sustain star formation in these galaxies. Most
of these observations have been conducted using interferometers and may have
missed lower column density, diffuse, HI gas that may trace the missing 90% of
gas. Such gas may represent the so-called "cold flows" predicted by current
theories of galaxy formation to have never been heated above the virial
temperature of the dark matter halo. As a first attempt to identify such cold
flows around nearby galaxies and complete the census of HI down to N(HI)~10^18
cm^-2, I used the Robert C. Byrd Green Bank Telescope (GBT) to map the
circumgalactic (r < 100-200 kpc) HI environment around NGC 2997 and NGC 6946.
The resulting GBT observations cover a four square degree area around each
galaxy with a 5-sigma detection limit of N(HI)~10^18 cm^-2 over a 20 km/s
linewidth. This project complements absorption line studies, which are
well-suited to the regime of lower N(HI). Around NGC 2997, the GBT HI data
reveal an extended HI disk and all of its surrounding gas-rich satellite
galaxies, but no filamentary features. Furthermore, the HI mass as measured
with the GBT is only 7% higher than past interferometric measurements. After
correcting for resolution differences, the HI extent of the galaxy is 23%
larger at the N(HI)~1.2x10^18 cm^-2 level as measured by the GBT. On the other
hand, the HI observations of NGC 6946 reveal a filamentary feature apparently
connecting NGC 6946 with its nearest companions. This HI filament has
N(HI)~10^18 cm^-2 and a FWHM of 55+-5 km/s and was invisible in past
interferometer observations. The properties of this filament are broadly
consistent with being a cold flow or debris from a past tidal interaction
between NGC 6946 and its satellites.


title: Geometric mutual information at classical critical points

abstract:
  A practical use of the entanglement entropy in a 1d quantum system is to
identify the conformal field theory describing its critical behavior. It is
exactly $(c/3)\ln \ell$ for an interval of length $\ell$ in an infinite system,
where $c$ is the central charge of the conformal field theory. Here we define
the geometric mutual information, an analogous quantity for classical critical
points. We compute this for 2d conformal field theories in an arbitrary
geometry, and show in particular that for a rectangle cut into two rectangles,
it is proportional to $c$. This makes it possible to extract $c$ in classical
simulations, which we demonstrate for the critical Ising and 3-state Potts
models.


title:
On the Asymptotic Statistics of the Number of Occurrences of Multiple
  Permutation Patterns

abstract:
  We study statistical properties of the random variables $X_{\sigma}(\pi)$,
the number of occurrences of the pattern $\sigma$ in the permutation $\pi$. We
present two contrasting approaches to this problem: traditional probability
theory and the ``less traditional'' computational approach. Through the
perspective of the first one, we prove that for any pair of patterns $\sigma$
and $\tau$, the random variables $X_{\sigma}$ and $X_{\tau}$ are jointly
asymptotically normal (when the permutation is chosen from $S_{n}$). From the
other perspective, we develop algorithms that can show asymptotic normality and
joint asymptotic normality (up to a point) and derive explicit formulas for
quite a few moments and mixed moments empirically, yet rigorously. The
computational approach can also be extended to the case where permutations are
drawn from a set of pattern avoiders to produce many empirical moments and
mixed moments. This data suggests that some random variables are not
asymptotically normal in this setting.


title: Cosmological singularity theorems and black holes

abstract:
  An extension of Penrose's singularity theorem is proved for spacetimes where
black holes are allowed to form from non-singular initial data. With standard
assumptions about the spacetime, and assuming the existence of a trapped
surface which lies outside of black hole horizons and is not completely
surrounded by horizons, we show that the spacetime region outside (or on) the
horizons must contain singularities. If the trapped surface is surrounded by
horizons, we show that the horizons divide spacetime into causally disconnected
pieces. Unlike the original Penrose's theorem, our theorems provide some
information about the location of singularities. We illustrate how they can be
used to rule out some cosmological scenarios.


title:
Unit cell orientation of tetragonal-like BiFeO$_3$ thin films grown on
  highly miscut LaAlO$_3$ substrates

abstract:
  Synchrotron and lab-scale x-ray diffraction shows that tetragonal-like
T'-BiFeO3 films on miscut LaAlO3 substrates (miscut < 5 deg) exhibit
(00l)-planes tilted away from those of the substrate as predicted by the "Nagai
model" (except for miscut <0.2 deg). Tilts as large as 1 deg are achieved even
in 100 nm thick films, strikingly larger than those observed in other
perovskites. We attribute this to the large c/a ratio and the high crystalline
coherency of the T'-BiFeO3/LaAlO3 interface. This coherency is possible through
an observed "diagonal-on-diagonal" alignment. Interestingly, the substrate
miscut does not influence the relative population of monoclinic domains.