title: On the torsion of rational elliptic curves over quartic fields

abstract:
  Let E be an elliptic curve defined over Q and let G = E(Q)_tors be the
associated torsion subgroup. We study, for a given G, which possible groups G
<= H could appear such that H=E(K)_tors, for [K:Q]=4 and H is one of the
possible torsion structures that occur infinitely often as torsion structures
of elliptic curves defined over quartic number fields.


title:
String states, loops and effective actions in noncommutative field
  theory and matrix models

abstract:
  Refining previous work by Iso, Kawai and Kitazawa, we discuss bi-local string
states as a tool for loop computations in noncommutative field theory and
matrix models. Defined in terms of coherent states, they exhibit the stringy
features of noncommutative field theory. This leads to a closed form for the
1-loop effective action in position space, capturing the long-range non-local
UV/IR mixing for scalar fields. The formalism applies to generic fuzzy spaces.
The non-locality is tamed in the maximally supersymmetric IKKT or IIB model,
where it gives rise to supergravity. The linearized supergravity interactions
are obtained directly in position space at one loop using string states on
generic noncommutative branes.


title:
Metastable energy strata in numerical discretizations of weakly
  nonlinear wave equations

abstract:
  The quadratic nonlinear wave equation on a one-dimensional torus with small
initial values located in a single Fourier mode is considered. In this
situation, the formation of metastable energy strata has recently been
described and their long-time stability has been shown. The topic of the
present paper is the correct reproduction of these metastable energy strata by
a numerical method. For symplectic trigonometric integrators applied to the
equation, it is shown that these energy strata are reproduced even on long time
intervals in a qualitatively correct way.


title:
Tent-transformed lattice rules for integration and approximation of
  multivariate non-periodic functions

abstract:
  We develop algorithms for multivariate integration and approximation in the
weighted half-period cosine space of smooth non-periodic functions. We use
specially constructed tent-transformed rank-1 lattice points as cubature nodes
for integration and as sampling points for approximation. For both integration
and approximation, we study the connection between the worst-case errors of our
algorithms in the cosine space and the worst-case errors of some related
algorithms in the well-known weighted Korobov space of smooth periodic
functions. By exploiting this connection, we are able to obtain constructive
worst-case error bounds with good convergence rates for the cosine space.


title: A Cockcroft-Walton PMT base with signal processing circuit

abstract:
  Design a surface mount 14-PIN Cockcroft-Walton photomultiplier tube base for
a muon detector, which provides both high voltage power supply and signal
processing. The whole system, including the detector, adopts a +5V DC power
input, and features as tiny size, low power-consumption and good portability,
extremely well meeting the requirements of the power supply with a battery on a
mobile workstation. Detailed descriptions and test results of a prototype are
presented.


title: Coherent cyclotron motion beyond Kohn's theorem

abstract:
  In solids, the high density of charged particles makes many-body interactions
a pervasive principle governing optics and electronics[1-12]. However, Walter
Kohn found in 1961 that the cyclotron resonance of Landau-quantized electrons
is independent of the seemingly inescapable Coulomb interaction between
electrons[2]. While this surprising theorem has been exploited in sophisticated
quantum phenomena[13-15] such as ultrastrong light-matter coupling[16],
superradiance[17], and coherent control[18], the complete absence of
nonlinearities excludes many intriguing possibilities, such as quantum-logic
protocols[19]. Here, we use intense terahertz pulses to drive the cyclotron
response of a two-dimensional electron gas beyond the protective limits of
Kohn's theorem. Anharmonic Landau ladder climbing and distinct terahertz four-
and six-wave mixing signatures occur, which our theory links to dynamic Coulomb
effects between electrons and the positively charged ion background. This new
context for Kohn's theorem unveils previously inaccessible internal degrees of
freedom of Landau electrons, opening up new realms of ultrafast quantum control
for electrons.


title:
Heat kernel estimates and the relative compactness of perturbations by
  potentials

abstract:
  We consider a self-adjoint non-negative operator $H$ in a Hilbert space
$\mathsf{L}^2(X,{\rm d}\mu)$. We assume that the semigroup $(\mathrm{e}^{-t
H})_{t>0}$ is defined by an integral kernel, $p$, which allows an estimate of
the form $p(t,x,x)\le F_1(x)F_2(t)$ for all $(x,t)\in X\times\mathbb{R_+}$; we
refer to $F_1$ as the \emph{control function}. We show that such an estimate
leads to rather satisfying abstract results on relative compactness of
perturbations of $H$ by potentials. It came as a surprise to us, however, that
such an estimate holds for the Laplace-Beltrami operator on \emph{any}
Riemannian manifold. In particular, using a domination principle, one can
deduce from the latter fact a very general result on the relative compactness
of perturbations by potentials of the Bochner Laplacian associated with a
Hermitian bundle $(E, h^E,\nabla^E)$ over an arbitrary Riemannian manifold
$(M,g)$; in fact, only quantities of order zero in $g$ enter in the estimates.
We extend this result to weighted Riemannian manifolds, where under lower
curvature bounds on the $\alpha$-Bakry-\'{E}mery tensor one can construct quite
explicit control functions, and to any weighted graph, where the control
function is expressed in terms of the vertex weight function.


title: Death and Suicide in Universal Artificial Intelligence

abstract:
  Reinforcement learning (RL) is a general paradigm for studying intelligent
behaviour, with applications ranging from artificial intelligence to psychology
and economics. AIXI is a universal solution to the RL problem; it can learn any
computable environment. A technical subtlety of AIXI is that it is defined
using a mixture over semimeasures that need not sum to 1, rather than over
proper probability measures. In this work we argue that the shortfall of a
semimeasure can naturally be interpreted as the agent's estimate of the
probability of its death. We formally define death for generally intelligent
agents like AIXI, and prove a number of related theorems about their behaviour.
Notable discoveries include that agent behaviour can change radically under
positive linear transformations of the reward signal (from suicidal to
dogmatically self-preserving), and that the agent's posterior belief that it
will survive increases over time.


title:
Strongly confined fluids: Diverging time scales and slowing down of
  equilibration

abstract:
  The Newtonian dynamics of strongly confined fluids exhibits a rich behavior.
Its confined and unconfined degrees of freedom decouple for confinement length
$L \to 0$. In that case and for a slit geometry the intermediate scattering
functions $S_{\mu\nu}(q,t)$ simplify, resulting for $(\mu,\nu) \neq (0,0)$ in a
Knudsen-gas like behavior of the confined degrees of freedom, and otherwise in
$S_{\parallel}(q,t)$, describing the structural relaxation of the unconfined
ones. Taking the coupling into account we prove that the energy fluctuations
relax exponentially. For smooth potentials the relaxation times diverge as
$L^{-3}$ and $L^{-4}$, respectively, for the confined and unconfined degrees of
freedom. The strength of the $L^{-3}$ divergence can be calculated
analytically. It depends on the pair potential and the two-dimensional pair
distribution function. Experimental setups are suggested to test these
predictions.


title: Maximally supersymmetric solutions of $R^2$ supergravity

abstract:
  There are five maximally supersymmetric backgrounds in four-dimensional
off-shell N=1 supergravity, two of which are well known: Minkowski superspace
M^{4|4} and anti-de Sitter superspace AdS^{4|4}. The three remaining
supermanifolds support spacetimes of different topology, which are: R x S^3,
AdS_3 x R, and a supersymmetric plane wave isometric to the Nappi-Witten group.
As is well known, the Minkowski and anti-de Sitter superspaces are solutions of
the Poincar\'e and anti-de Sitter supergravity theories, respectively. Here we
demonstrate that the other three superspaces are solutions of no-scale $R^2$
supergravity. We also present a new (probably the simplest) derivation of the
maximally supersymmetric backgrounds of off-shell N=1 supergravity.


title:
Thermally-Targeted Adsorption And Enrichment In Micro-scale Hydrothermal
  Pore Environments

abstract:
  The unique ability of chaotic advection under micro-scale confinement to
direct chemical processes along accelerated kinetic pathways has long been
recognized. But practical applications have been slow to emerge because optimal
results are often counter-intuitively achieved in flows that appear to possess
undesirably high disorder. Here we demonstrate how thermally actuated chaotic
phenomena within these microenvironments are capable of establishing a
continuous conveyor transporting chemical compounds from the bulk to targeted
locations on solid boundaries where they become greatly enriched. These
findings intriguingly suggest that microscale chaotic advection may offer a
new- mechanism to explain emergence of biomolecular complexity from dilute
organic precursors in the prebiotic milieu-a key unanswered question in the
origin of life. We further show how these flows can be rationally designed and
harnessed to execute bulk biochemical processes with a level of robustness
previously thought unattainable.


title: Forecasting Framework for Open Access Time Series in Energy

abstract:
  In this paper we propose a framework for automated forecasting of
energy-related time series using open access data from European Network of
Transmission System Operators for Electricity (ENTSO-E). The framework provides
forecasts for various European countries using publicly available historical
data only. Our solution was benchmarked using the actual load data and the
country provided estimates (where available). We conclude that the proposed
system can produce timely forecasts with comparable prediction accuracy in a
number of cases. We also investigate the probabilistic case of forecasting -
that is, providing a probability distribution rather than a simple point
forecast - and incorporate it into a web based API that provides quick and easy
access to reliable forecasts.


title: Fighting the flow: the stability of model flocks in a vortical flow

abstract:
  We investigate the stability of self-propelled particle flocks in the
Taylor-Green vortex, a steady vortical flow. We consider a model where
particles align themselves to a combination of the orientation and the
acceleration of particles within a critical radius. We identify two distinct
regimes, if alignment with orientation is dominant the particles tend to be
expelled from regions of high vorticity. In contrast if anticipation is
dominant the particles accumulate in areas of large vorticity. In both regimes
the relative order of the flock is reduced. However we show that there can be a
critical balance of the two effects which stabilises the flock in the presence
of external fluid forcing. This strategy could provide a mechanism for animal
flocks to remain globally ordered in the presence of fluid forcing, and may
also have applications in the design of flocking autonomous drones and
artificial microswimmers.


title: Programmable Mechanical Metamaterials: the Role of Geometry

abstract:
  We experimentally and numerically study the precise role of geometry for the
mechanics of biholar metamaterials, quasi-2D slabs of rubber patterned by
circular holes of two alternating sizes. We recently showed how the response to
uniaxial compression of these metamaterials can be programmed by their lateral
confinement $^1$. In particular, there is a range of confining strains
$\varepsilon_x$ for which the resistance to compression becomes non-trivial -
non-monotonic or hysteretic - in a range of compressive strains
$\varepsilon_y$. Here we show how the dimensionless geometrical parameters $t$
and $\chi$, which characterize the porosity and size ratio of the holes that
pattern these metamaterials, can significantly tune these ranges over a wide
range. We study the behavior for the limiting cases where $t$ and $\chi$ become
large, and discuss the new physics that arises there. Away from these extreme
limits, the variation of the strain ranges of interest is smooth with porosity,
but the variation with size ratio evidences a cross-over at low $\chi$ from
biholar to monoholar (equal sized holes) behavior, related to the elastic
instabilities in purely monoholar metamaterials$^2$. Our study provides precise
guidelines for the rational design of programmable biholar metamaterials,
tailored to specific applications, and indicates that the widest range of
programmability arises for moderate values of both $t$ and $\chi$.


title: Cosmological Solutions of $f(T)$ Gravity

abstract:
  In the cosmological scenario in $f\left( T\right) $ gravity, we find
analytical solutions for an isotropic and homogeneous universe containing a
dust fluid and radiation and for an empty anisotropic Bianchi I universe. The
method that we apply is that of movable singularities of differential
equations. For the isotropic universe, the solutions are expressed in terms of
a Laurent expansion, while for the anisotropic universe we find a family of
exact Kasner-like solutions in vacuum. Finally, we discuss when a nonlinear
$f\left( T\right) $-gravity theory provides solutions for the teleparallel
equivalence of general relativity and derive conditions for exact solutions of
general relativity to solve the field equations of an $f(T)$ theory.


title:
A comparison of methods for the detection of gravitational waves from
  unknown neutron stars

abstract:
  Rapidly rotating neutron stars are promising sources of continuous
gravitational wave radiation for the LIGO and Virgo interferometers. The
majority of neutron stars in our galaxy have not been identified with
electromagnetic observations. All-sky searches for isolated neutron stars offer
the potential to detect gravitational waves from these unidentified sources.
The parameter space of these blind all-sky searches, which also cover a large
range of frequencies and frequency derivatives, presents a significant
computational challenge. Different methods have been designed to perform these
searches within acceptable computational limits. Here we describe the first
benchmark in a project to compare the search methods currently available for
the detection of unknown isolated neutron stars. We employ a mock data
challenge to compare the ability of each search method to recover signals
simulated assuming a standard signal model. We find similar performance among
the short duration search methods, while the long duration search method
achieves up to a factor of two higher sensitivity. We find the absence of
second derivative frequency in the search parameter space does not degrade
search sensivity for signals with physically plausible second derivative
frequencies. We also report on the parameter estimation accuracy of each search
method, and the stability of the sensitivity in frequency, frequency derivative
and in the presence of detector noise.


title: Quantum metrics on noncommutative spaces

abstract:
  We introduce two new formulations for the notion of "quantum metric on
noncommutative space". For a compact noncommutative space associated to a
unital C*-algebra, our quantum metrics are elements of the spatial tensor
product of the C*-algebra with itself. We consider some basic properties of
these new objects, and state some connections with the Rieffel theory of
compact quantum metric spaces. The main gap in our work is the lack of a
nonclassical example even in the case of C*-algebras of matrices.


title:
Modeling Opinion Dynamics: Theoretical analysis and continuous
  approximation

abstract:
  Frequently we revise our first opinions after talking over with other
individuals because we get convinced. Argumentation is a verbal and social
process aimed at convincing. It includes conversation and persuasion. In this
case, the agreement is reached because the new arguments are incorporated. In
this paper we deal with a simple model of opinion formation with such
persuasion dynamics, and we find the exact analytical solutions for both, long
and short range interactions. A novel theoretical approach has been used in
order to solve the master equations of the model with non-local kernels.
Simulation results demonstrate an excellent agreement with results obtained by
the theoretical estimation.


title:
Electrically-induced phase transition in $\alpha$-(BEDT-TTF)$_2$I$_3$:
  Indications for high-mobility hot charge carriers

abstract:
  The two-dimensional organic conductor $\alpha$-(BEDT-TTF)$_2$I$_3$ undergoes
a metal-insulator transition at $T_{\rm CO}=135$ K due to electronic charge
ordering. We have conducted time-resolved investigations of its electronic
properties in order to explore the field- and temperature-dependent dynamics.
At a certain threshold field, the system switches from low-conducting to a
high-conducting state, accompanied by a negative differential resistance. Our
time-dependent infrared investigations indicate that close to $T_{\rm CO}$ the
strong electric field pushes the crystal into a metallic state with optical
properties similar to the one for $T>T_{\rm CO}$. Well into the insulating
state, however, at $T=80$ K, the spectral response evidences a completely
different electronically-induced high-conducting state. Applying a two-state
model of hot electrons explains the observations by excitation of charge
carriers with a high mobility. They resemble the Dirac-like charge-carriers
with a linear dispersion of the electronic bands found in
$\alpha$-(BEDT-TTF)$_2$I$_3$ at high-pressure. Extensive numerical simulations
quantitatively reproduce our experimental findings in all details.


title:
Coulomb blockade based field-effect transistors exploiting stripe-shaped
  channel geometries of self-assembled metal nanoparticles

abstract:
  Metallic nanoparticles offer possibilities to build basic electric devices
with new functionality and improved performance. Due to the small volume and
the resulting low self-capacitance, each single nanoparticle exhibits a high
charging energy. Thus, a Coulomb-energy gap emerges during transport
experiments that can be shifted by electric fields, allowing for charge
transport whenever energy levels of neighboring particles match. Hence, the
state of the device changes sequentially between conducting and non-conducting
instead of just one transition from conducting to pinch-off as in
semiconductors. To exploit this behavior for field-effect transistors, it is
necessary to use uniform nanoparticles in ordered arrays separated by
well-defined tunnel barriers. In this work, CoPt nanoparticles with a narrow
size distribution are synthesized by colloidal chemistry. These particles are
deposited via the scalable Langmuir-Blodgett technique as ordered, homogeneous
monolayers onto Si/SiO2 substrates with pre-patterned gold electrodes. The
resulting nanoparticle arrays are limited to stripes of adjustable lengths and
widths. In such a defined channel with a limited number of conduction paths the
current can be controlled precisely by a gate voltage. Clearly pronounced
Coulomb oscillations are observed up to temperatures of 150 K. Using such
systems as field-effect transistors yields unprecedented oscillating current
modulations with on/off-ratios of around 70 %.


title:
History of "Anomalous" Atmospheric Neutrino Events: A First Person
  Account

abstract:
  The modern picture of the neutrino as a multiple mass highly mixed neutral
particle has emerged over 40 years of study. Best known of the issues leading
to this picture was the apparent loss of neutrinos coming from the sun. This
article describes another piece of evidence that supports the picture; the
substantial reduction of high energy muon type neutrinos observed in nature.
For much of the 40 year period, before the modern picture emerged this
observation was known as the "atmospheric neutrino anomaly", since as will be
seen, these neutrinos originate in the Earth's atmosphere.
  This paper describes the discovery of the atmospheric neutrino anomaly. We
explore the scientific context and motivations in the late 1970's from which
this work emerged. The gradual awareness that the observations of atmospheric
neutrinos were not as expected took place in the 1983-1986 period.

categories: physics.hist-ph astro-ph.HE hep-ex hep-ph hep-th


title: Total dominator chromatic number of some operations on a graph

abstract:
  Let $G$ be a simple graph. A total dominator coloring of $G$ is a proper
coloring of the vertices of $G$ in which each vertex of the graph is adjacent
to every vertex of some color class. The total dominator chromatic number
$\chi_d^t(G)$ of $G$ is the minimum number of colors among all total dominator
coloring of $G$. In this paper, we examine the effects on $\chi_d^t(G)$ when
$G$ is modified by operations on vertex and edge of $G$.


title: Converting virtual link diagrams to normal ones

abstract:
  A virtual link diagram is called normal if the associated abstract link
diagram is checkerboard colorable, and a virtual link is normal if it has a
normal diagram as a representative.In this paper, we introduce a method of
converting a virtual link diagram to a normal virtual link diagram by use of
the double covering technique. We show that the normal virtual link diagrams
obtained from two equivalent virtual link diagrams are related by generalized
Reidemeister moves and Kauffman flypes.


title: Unified Scalable Equivalent Formulations for Schatten Quasi-Norms

abstract:
  The Schatten quasi-norm can be used to bridge the gap between the nuclear
norm and rank function, and is the tighter approximation to matrix rank.
However, most existing Schatten quasi-norm minimization (SQNM) algorithms, as
well as for nuclear norm minimization, are too slow or even impractical for
large-scale problems, due to the SVD or EVD of the whole matrix in each
iteration. In this paper, we rigorously prove that for any p, p1, p2>0
satisfying 1/p=1/p1+1/p2, the Schatten-p quasi-norm of any matrix is equivalent
to minimizing the product of the Schatten-p1 norm (or quasi-norm) and
Schatten-p2 norm (or quasi-norm) of its two factor matrices. Then we present
and prove the equivalence relationship between the product formula of the
Schatten quasi-norm and its weighted sum formula for the two cases of p1 and
p2: p1=p2 and p1\neq p2. In particular, when p>1/2, there is an equivalence
between the Schatten-p quasi-norm of any matrix and the Schatten-2p norms of
its two factor matrices, where the widely used equivalent formulation of the
nuclear norm can be viewed as a special case. That is, various SQNM problems
with p>1/2 can be transformed into the one only involving smooth, convex norms
of two factor matrices, which can lead to simpler and more efficient algorithms
than conventional methods.
  We further extend the theoretical results of two factor matrices to the cases
of three and more factor matrices, from which we can see that for any 0<p<1,
the Schatten-p quasi-norm of any matrix is the minimization of the mean of the
Schatten-(p3+1)p norms of all factor matrices, where p3 denotes the largest
integer not exceeding 1/p. In other words, for any 0<p<1, the SQNM problem can
be transformed into an optimization problem only involving the smooth, convex
norms of multiple factor matrices.


title:
On-line Tools for Solar Data Compiled at the Debrecen Observatory and
  their Extensions with the Greenwich Sunspot Data

abstract:
  The primary task of the Debrecen Heliophysical Observatory (DHO) has been the
most detailed, reliable, and precise documentation of the solar photospheric
activity since 1958. This long-term effort resulted in various solar catalogs
based on ground-based and space-borne observations. A series of sunspot
databases and on-line tools were compiled at DHO: the Debrecen
Photoheliographic Data (DPD, 1974--), the dataset based on the Michelson
Doppler Imager (MDI) of the Solar and Heliospheric Observatory (SOHO) called
SOHO/MDI--Debrecen Data (SDD, 1996--2010), and the dataset based on the
Helioseismic and Magnetic Imager (HMI) of the Solar Dynamics Observatory (SDO)
called SDO/HMI--Debrecen Data (HMIDD, 2010--). User-friendly web-presentations
and on-line tools were developed to visualize and search data. As a last step
of compilation, the revised version of Greenwich Photoheliographic Results
(GPR, 1874--1976) catalog was converted to DPD format, and a homogeneous
sunspot database covering more than 140 years was created. The database of
images for the GPR era was completed with the full-disc drawings of the
Hungarian historical observatories \'Ogyalla and Kalocsa (1872--1919) and with
the polarity drawings of Mount Wilson Observatory. We describe the main
characteristics of the available data and on-line tools.


title: Cross-ratio Identities and Higher-order Poles of CHY-integrand

abstract:
  The evaluation of generic Cachazo-He-Yuan(CHY)-integrands is a big challenge
and efficient computational methods are in demand for practical evaluation. In
this paper, we propose a systematic decomposition algorithm by using
cross-ratio identities, which provides an analytic and easy to implement method
for the evaluation of any CHY-integrand. This algorithm aims to decompose a
given CHY-integrand containing higher-order poles as a linear combination of
CHY-integrands with only simple poles in a finite number of steps, which
ultimately can be trivially evaluated by integration rules of simple poles. To
make the method even more efficient for CHY-integrands with large number of
particles and complicated higher-order pole structures, we combine the
$\Lambda$-algorithm and the cross-ratio identities, and as a by-product it
provides us a way to deal with CHY-integrands where the $\Lambda$-algorithm was
not applicable in its original formulation.


title: On the modified multi-component Camassa-Holm system in higher dimensions

abstract:
  This paper is devoted to the Cauchy problem for the modified multi-component
Camassa-Holm system in higher dimensions. On the one hand, we establish an
almost complete local well-posedness results for the system in the framework of
Besov spaces. On the other hand, several blow-up criteria of strong solutions
to the system are derived by using the Littlewood-Paley decomposition and the
energy method.


title:
Limits on Entanglement Effects in the String Landscape from Planck and
  BICEP/Keck Data

abstract:
  We consider observational limits on a proposed model of the string landscape
in inflation. In this scenario, effects from the decoherence of entangled
quantum states in long-wavelength modes in the universe result in modifications
to the Friedmann Equation and a corresponding modification to inflationary
dynamics. Previous work by Holman, Mersini-Houghton, and Takahashi suggested
that such effects could provide an explanation for well-known anomalies in the
Cosmic Microwave Background (CMB), such as the lack of power on large scales
and the "cold spot" seen by both the WMAP and Planck satellites. In this paper,
we compute limits on these entanglement effects from the Planck CMB data
combined with the BICEP/Keck polarization measurement, and find no evidence for
observable modulations to the power spectrum from landscape entanglement, and
no sourcing of observable CMB anomalies. The originally proposed model with an
exponential potential is ruled out to high significance. Assuming a
Starobinsky-type $R^2$ inflation model, which is consistent with CMB
constraints, data place a $2\sigma$ lower bound of $b > 6.46 \times 10^7\ {\rm
GeV}$ on the Supersymmetry breaking scale associated with entanglement
corrections.


title: Effective model based on QCD with gluon condensate

abstract:
  We construct the effective model based on QCD with gluon condensate. Under
the assumption that the gluons are condensed with the sharp momentum peak in
the momentum space, we formulate the effective field theory incorporating both
the gluon condensate and the chiral condensate, then study the phase transition
on temperature and chemical potential plane with respect to two condensates. We
find that the condensates decrease with increasing temperature, which is
reliable tendency on the condensate being consistent with the argument of the
asymptotic behavior.


title: Time-Dependent AdS Backgrounds from S-Branes

abstract:
  We construct time and radial dependent solutions that describe p-branes in
chargeless S-brane backgrounds. In particular, there are some new M5- and
D3-branes among our solutions which have AdS limits and contain a cosmological
singularity as well. We also find a time-dependent version of the dyonic
membrane configuration in 11-dimensions by applying a Lunin-Maldacena
deformation to our new M5-brane solution.


title: Layers of deformed instantons in holographic baryonic matter

abstract:
  We discuss homogeneous baryonic matter in the decompactified limit of the
Sakai-Sugimoto model, improving existing approximations based on flat-space
instantons. We allow for an anisotropic deformation of the instantons in the
holographic and spatial directions and for a density-dependent distribution of
arbitrarily many instanton layers in the bulk. Within our approximation, the
baryon onset turns out to be a second-order phase transition, at odds with
nature, and there is no transition to quark matter at high densities, at odds
with expectations from QCD. This changes when we impose certain constraints on
the shape of single instantons, motivated by known features of holographic
baryons in the vacuum. Then, a first-order baryon onset and chiral restoration
at high density are possible, and at sufficiently large densities two instanton
layers are formed dynamically. Our results are a further step towards
describing realistic, strongly interacting matter over a large density regime
within a single model, desirable for studies of compact stars.


title:
Nonlinear response of metallic acGNR to an elliptically-polarized
  terahertz excitation field

abstract:
  We present a theoretical description of the nonlinear response induced by an
elliptically-polarized terahertz beam normally-incident on intrinsic and
extrinsic metallic armchair graphene nanorib- bons. Our results show that using
a straightforward experimental setup, it should be possible to observe novel
polarization-dependent nonlinearities at low excitation field strengths of the
or- der of 10 4 V/m. At low temperatures the Kerr nonlinearities in extrinsic
nanoribbons persist to significantly higher excitation frequencies than they do
for linear polarizations, and at room tem- peratures, the third-harmonic
nonlinearities are enhanced by 2-3 orders of magnitude. Finally, the
Fermi-level and temperature dependence of the nonlinear response is
characterized.


title: Disappearance of the Mach Cone in heavy ion collisions

abstract:
  We present an analysis of di-hadron correlations using recently developed
methods for background subtraction which allow for higher precision
measurements with fewer assumptions about the background. These studies
indicate that low momentum jets interacting with the medium do not equilibrate
with the medium, but rather that interactions with the medium lead to more
subtle increases in their widths and fragmentation functions, consistent with
observations from studies of higher momentum fully reconstructed jets. The
away-side shape is not consistent with a Mach cone.


title: RPP: Automatic Proof of Relational Properties by Self-Composition

abstract:
  Self-composition provides a powerful theoretical approach to prove relational
properties, i.e. properties relating several program executions, that has been
applied to compare two runs of one or similar programs (in secure dataflow
properties, code transformations, etc.). This tool demo paper presents RPP, an
original implementation of self-composition for specification and verification
of relational properties in C programs in the FRAMA-C platform. We consider a
very general notion of relational properties invoking any finite number of
function calls of possibly dissimilar functions with possible nested calls. The
new tool allows the user to specify a relational property, to prove it in a
completely automatic way using classic deductive verification, and to use it as
a hypothesis in the proof of other properties that may rely on it.


title: Automorphisms and endomorphisms of lacunary hyperbolic groups

abstract:
  In this article we study automorphisms and endomorphisms of lacunary
hyperbolic groups. We prove that every lacunary hyperbolic group is Hopfian,
answering a question by Henry Wilton. In addition, we show that if a lacunary
hyperbolic group has the fix point property for actions on $\mathbf R$-trees,
then it is co-Hopfian and its outer automorphism group is locally finite. We
also construct lacunary hyperbolic groups whose automorphism group is infinite,
locally finite, and contains any locally finite group given in advance.


title: A note on Hardy's theorem

abstract:
  Hardy's theorem for the Riemann zeta-function $\zeta(s)$ says that it admits
infinitely many complex zeros on the line $\Re({s}) = \frac{1}{2}$. In this
note, we give a simple proof of this statement which, to the best of our
knowledge, is new.


title: On the Study of Solar Flares with Neutrino Observatories

abstract:
  Since the end of the eighties, in response to a reported increase of the
total neutrino flux in the Homestake experiment in coincidence with solar
flares, neutrino detectors have searched for signals of neutrinos associated
with solar flare activity. Protons which are accelerated by the magnetic
structures of such flares may collide with the solar atmosphere, producing
mesons which subsequently decay, resulting in neutrinos at O(MeV-GeV) energies.
The study of such neutrinos would provide a new window on the underlying
physics of the acceleration process. The sensitivity to solar flares of the
IceCube Neutrino Observatory, located at the geographical South Pole, is
currently under study. We introduce a new approach for a time profile analysis.
This is based on a stacking method of selected solar flares which are likely to
be connected with pion production. An initial approach towards a neutrino
search using the current IceCube experiment as well as first efforts to improve
the detection efficiency in the future are presented.


title:
Constrained Phase Noise Estimation in OFDM Using Scattered Pilots
  Without Decision Feedback

abstract:
  In this paper, we consider an OFDM radio link corrupted by oscillator phase
noise in the receiver, namely the problem of estimating and compensating for
the impairment. To lessen the computational burden and delay incurred onto the
receiver, we estimate phase noise using only scattered pilot subcarriers, i.e.,
no tentative symbol decisions are used in obtaining and improving the phase
noise estimate. In particular, the phase noise estimation problem is posed as
an unconstrained optimization problem whose minimizer suffers from the
so-called amplitude and phase estimation error. These errors arise due to
receiver noise, estimation from limited scattered pilot subcarriers and
estimation using a dimensionality reduction model. It is empirically shown
that, at high signal-to-noise-ratios, the phase estimation error is small. To
reduce the amplitude estimation error, we restrict the minimizer to be drawn
from the so-called phase noise geometry set when minimizing the cost function.
The resulting optimization problem is a non-convex program. However, using the
S-procedure for quadratic equalities, we show that the optimal solution can be
obtained by solving the convex dual problem. We also consider a less complex
heuristic scheme that achieves the same objective of restricting the minimizer
to the phase noise geometry set. Through simulations, we demonstrate improved
coded bit-error-rate and phase noise estimation error performance when
enforcing the phase noise geometry. For example, at high
signal-to-noise-ratios, the probability density function of the phase noise
estimation error exhibits thinner tails which results in lower bit-error-rate.


title:
Long-range interactions and phase defects in chains of fluid-coupled
  oscillators

abstract:
  Eukaryotic cilia and flagella are chemo-mechanical oscillators capable of
generating long-range coordinated motions known as metachronal waves. Pair
synchronization is a fundamental requirement for these collective dynamics, but
it is generally not sufficient for collective phase-locking, chiefly due to the
effect of long-range interactions. Here we explore experimentally and
numerically a minimal model for a ciliated surface; hydrodynamically coupled
oscillators rotating above a no-slip plane. Increasing their distance from the
wall profoundly effects the global dynamics, due to variations in hydrodynamic
interaction range. The array undergoes a transition from a traveling wave to
either a steady chevron pattern or one punctuated by periodic phase defects.
Within the transition between these regimes the system displays behavior
reminiscent of chimera states.

categories: physics.bio-ph cond-mat.soft math.DS physics.flu-dyn


title: Black holes with vector hair

abstract:
  In this paper, we consider Einstein gravity coupled to a vector field, either
minimally or non-minimally, together with a vector potential of the type
$V=2\Lambda_0+\ft 12 m^2 A^2+\gamma_4 A^4$. For a simpler non-minimally coupled
theory with $\Lambda_0=m=\gamma_4=0$, we obtain both extremal and non-extremal
black hole solutions that are asymptotic to Minkowski space-times. We study the
global properties of the solutions and derive the first law of thermodynamics
using Wald formalism. We find that the thermodynamical first laws of the
extremal black holes are modified by a one form associated with the vector
field. In particular, due to the existence of the non-minimal coupling, the
vector forms thermodynamic conjugates with the graviton mode and partly
contributes to the one form modifying the first laws. For a minimally coupled
theory with $\Lambda_0\neq 0$, we also obtain one class of asymptotically flat
extremal black hole solutions in general dimensions. This is possible because
the parameters $(m^2,\gamma_4)$ take certain values such that $V=0$. In
particular, we find that the vector also forms thermodynamic conjugates with
the graviton mode and contributes to the corresponding first laws, although the
non-minimal coupling has been turned off. Thus all the extremal black hole
solutions that we obtain provide highly non-trivial examples how the first law
of thermodynamics can be modified by a either minimally or non-minimally
coupled vector field.
  We also study Gauss-Bonnet gravity non-minimally coupled to a vector and
obtain asymptotically flat black holes and Lifshitz black holes.


title:
Experimental demonstration of a resonator-induced phase gate in a
  multi-qubit circuit QED system

abstract:
  The resonator-induced phase (RIP) gate is a multi-qubit entangling gate that
allows a high degree of flexibility in qubit frequencies, making it attractive
for quantum operations in large-scale architectures. We experimentally realize
the RIP gate with four superconducting qubits in a three-dimensional (3D)
circuit-quantum electrodynamics architecture, demonstrating high-fidelity
controlled-Z (CZ) gates between all possible pairs of qubits from two different
4-qubit devices in pair subspaces. These qubits are arranged within a wide
range of frequency detunings, up to as large as 1.8 GHz. We further show a
dynamical multi-qubit refocusing scheme in order to isolate out 2-qubit
interactions, and combine them to generate a four-qubit
Greenberger-Horne-Zeilinger state.


title: Measurement of linear response functions in Nuclear Magnetic Resonance

abstract:
  We measure multi-time correlation functions of a set of Pauli operators on a
two-level system, which can be used to retrieve its associated linear response
functions. The two-level system is an effective spin constructed from the
nuclear spins of $^{1}$H atoms in a solution of $^{13}$C-labeled chloroform.
Response functions characterize the linear response of the system to a family
of perturbations, allowing us to compute physical quantities such as the
magnetic susceptibility of the effective spin. We use techniques exported from
quantum information to measure time correlations on the two-level system. This
approach requires the use of an ancillary qubit encoded in the nuclear spins of
the $^{13}$C atoms and a sequence of controlled operations. Moreover, we
demonstrate the ability of such a quantum platform to compute time-correlation
functions of arbitrary order, which relate to higher-order corrections of
perturbative methods. Particularly, we show three-time correlation functions
for arbitrary times, and we also measure time correlation functions at fixed
times up to tenth order.


title:
Shape and symmetry determine two-dimensional melting transitions of hard
  regular polygons

abstract:
  The melting transition of two-dimensional (2D) systems is a fundamental
problem in condensed matter and statistical physics that has advanced
significantly through the application of computational resources and
algorithms. 2D systems present the opportunity for novel phases and phase
transition scenarios not observed in 3D systems, but these phases depend
sensitively on the system and thus predicting how any given 2D system will
behave remains a challenge. Here we report a comprehensive simulation study of
the phase behavior near the melting transition of all hard regular polygons
with $3\leq n\leq 14$ vertices using massively parallel Monte Carlo simulations
of up to one million particles. By investigating this family of shapes, we show
that the melting transition depends upon both particle shape and symmetry
considerations, which together can predict which of three different melting
scenarios will occur for a given $n$. We show that systems of polygons with as
few as seven edges behave like hard disks; they melt continuously from a solid
to a hexatic fluid and then undergo a first-order transition from the hexatic
phase to the fluid phase. We show that this behavior, which holds for all
$7\leq n\leq 14$, arises from weak entropic forces among the particles. Strong
directional entropic forces align polygons with fewer than seven edges and
impose local order in the fluid. These forces can enhance or suppress the
discontinuous character of the transition depending on whether the local order
in the fluid is compatible with the local order in the solid. As a result,
systems of triangles, squares, and hexagons exhibit a KTHNY-type continuous
transition between fluid and hexatic, tetratic, and hexatic phases,
respectively, and a continuous transition from the appropriate "x"-atic to the
solid. [abstract truncated due to arxiv length limitations].


title: U-duality transformation of membrane on $T^{n}$ revisited

abstract:
  The problem with the U-duality transformation of membrane on $T^{n}$ is
recently addressed in [arXiv:1509.02915 [hep-th]]. We will consider the
U-duality transformation rule of membrane on $T^{n}\times R$. It turns out that
winding modes on $T^{n}$ should be taken into account, since the duality
transformation may bring the membrane configuration without winding modes into
the one with winding modes. With the winding modes added, the membrane
worldvolume theory in lightcone gauge is equivalent to the $n+1$ dimensional
super-Yang-Mills (SYM) theory in $\tilde{T}^{n}$, which has $SL(2,Z)\times
SL(3,Z)$ and $SL(5,Z)$ symmetries for $n=3$ and $n=4$, respectively. The
$SL(2,Z)\times SL(3,Z)$ transformation can be realized classically, making the
on-shell field configurations transformed into each other. However, the
$SL(5,Z)$ symmetry may only be realized at the quantum level, since the
classical $5d$ SYM field configurations cannot form the representation of
$SL(5,Z)$.


title:
Measurement of the angular coefficients in $Z$-boson events using
  electron and muon pairs from data taken at $\sqrt{s}=8$ TeV with the ATLAS
  detector

abstract:
  The angular distributions of Drell-Yan charged lepton pairs around the
$Z$-boson mass peak probe the underlying QCD dynamics of $Z$-boson production.
This paper presents a measurement of the complete set of angular coefficients
$A_{0-7}$ describing these distributions in the $Z$-boson Collins-Soper frame.
The data analysed correspond to 20.3 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}
= 8$ TeV, collected by the ATLAS detector at the CERN LHC. The measurements are
compared to the most precise fixed-order calculations currently available
($\mathcal{O}(\alpha^{2}_{s})$) and with theoretical predictions embedded in
Monte Carlo generators. The measurements are precise enough to probe QCD
corrections beyond the formal accuracy of these calculations and to provide
discrimination between different parton-shower models. A significant deviation
from the $\mathcal{O}(\alpha^{2}_{s})$ predictions is observed for
$A_{0}-A_{2}$. Evidence is found for non-zero $A_{5,6,7}$, consistent with
expectations.


title: COATLI: an all-sky robotic optical imager with 0.3 arcsec image quality

abstract:
  COATLI will provide 0.3 arcsec FWHM images from 550 to 900 nm over a large
fraction of the sky. It consists of a robotic 50-cm telescope with a
diffraction-limited fast-guiding imager. Since the telescope is small, fast
guiding will provide diffraction-limited image quality over a field of at least
1 arcmin and with coverage of a large fraction of the sky, even in relatively
poor seeing. The COATLI telescope will be installed at the at the Observatorio
Astron\'omico Nacional in Sierra San Pedro M\'artir, M\'exico, during 2016 and
the diffraction-limited imager will follow in 2017.


title: Effect of TTC on Satellite Orbital Mechanics

abstract:
  The modified dynamical equation of motions introduced in previous publication
topological torsion current (TTC) [Mario J. Pinheiro (2013) 'A Variational
Method in Out-of-Equilibrium Physical Systems', Scientific Reports {\bf 3},
Article number: 3454] predicts a so-far unforeseen anomalous acceleration
detected in spacecrafts during close planetary flybys in retrograde direction,
and a null-effect when the spacecraft approach the planet in posigrade
direction.


title:
Shape and spin distributions of large object populations from random
  projection areas

abstract:
  We model the shape and spin characteristics of an object population when
there are not enough data to model its single members. The data are random
projection areas of the members. We construct a mapping $f(x)\rightarrow C(y)$,
$x\in\mathbb{R}^2$, $y\in\mathbb{R}$, where $f(x)$ is the distribution function
of the shape elongation and spin vector obliquity, and $C(y)$ is the cumulative
distribution function of an observable $y$ describing the variation of the
observed projection areas of one member, and show that the mapping is
invertible. Using the projected area of an ellipsoid as our model, we obtain
analytical basis functions for a function series of $C(y)$ and prove uniqueness
and stability properties of the inverse problem. Even though the model error is
considerably larger than the measurement noise for realistic cases of arbitrary
shapes (such as asteroids), the main characteristics of $f(x)$ (such as the
locations of peaks) are robustly recovered from the data.


title: Thermodynamics of acoustic black holes in two dimensions

abstract:
  It is well-known that the thermal Hawking-like radiation can be emitted from
the acoustic horizon, but the thermodynamic-like understanding for acoustic
black holes was rarely made. In this paper, we will show that the kinematic
connection can lead to the dynamic connection at the horizon between the fluid
and gravitational models in two dimension, which implies that there exists the
thermodynamic-like description for acoustic black holes. Then, we discuss the
first law of thermodynamics for the acoustic black hole via an intriguing
connection between the gravitational-like dynamics of the acoustic horizon and
thermodynamics. We obtain a universal form for the entropy of acoustic black
holes, which has an interpretation similar to the entropic gravity. We also
discuss the specific heat, and find that the derivative of the velocity of
background fluid can be regarded as a novel acoustic analogue of the
two-dimensional dilaton potential, which interprets why the two-dimensional
fluid dynamics can be connected to the gravitational dynamics but difficult for
four-dimensional case. In particular, when a constraint is added for the fluid,
the analogue of a Schwarzschild black hole can be realized.


title:
On the graphical extraction of multipole mixing ratios of nuclear
  transitions

abstract:
  We propose a novel graphical method for determining the mixing ratios
{\delta} and their associated uncertainties for mixed nuclear transitions. It
incorporates the uncertainties both on both the measured and the theoretical
conversion coefficients. The accuracy of the method has been studied by
deriving the corresponding probability density function. The domains of
applicability of the method are carefully defined.


title: DDOTI: the deca-degree optical transient imager

abstract:
  DDOTI will be a wide-field robotic imager consisting of six 28-cm telescopes
with prime focus CCDs mounted on a common equatorial mount. Each telescope will
have a field of view of 12 square degrees, will have 2 arcsec pixels, and will
reach a 10-sigma limiting magnitude in 60 seconds of r = 18.7 in dark time and
r = 18.0 in bright time. The set of six will provide an instantaneous field of
view of about 72 square degrees. DDOTI uses commercial components almost
entirely. The first DDOTI will be installed at the Observatorio Astron\'omico
Nacional in Sierra San Pedro Mart\'ir, Baja California, M\'exico in early 2017.
The main science goals of DDOTI are the localization of the optical transients
associated with GRBs detected by the GBM instrument on the Fermi satellite and
with gravitational-wave transients. DDOTI will also be used for studies of AGN
and YSO variability and to determine the occurrence of hot Jupiters. The
principal advantage of DDOTI compared to other similar projects is cost: a
single DDOTI installation costs only about US$500,000. This makes it possible
to contemplate a global network of DDOTI installations. Such geographic
diversity would give earlier access and a higher localization rate. We are
actively exploring this option.


title: Magnetic shielding and exotic spin-dependent interactions

abstract:
  Experiments searching for exotic spin-dependent interactions typically employ
magnetic shielding between the source of the exotic field and the interrogated
spins. We explore the question of what effect magnetic shielding has on
detectable signals induced by exotic fields. Our general conclusion is that for
common experimental geometries and conditions, magnetic shields should not
significantly reduce sensitivity to exotic spin-dependent interactions,
especially when the technique of comagnetometry is used. However, exotic fields
that couple to electron spin can induce magnetic fields in the interior of
shields made of a soft ferro- or ferrimagnetic material. This induced magnetic
field must be taken into account in the interpretation of experiments searching
for new spin-dependent interactions and raises the possibility of using a flux
concentrator inside magnetic shields to amplify exotic spin-dependent signals.


title: On resolvable Steiner 2-designs and maximal arcs in projective planes

abstract:
  A combinatorial characterization of resolvable Steiner 2-$(v,k,1)$ designs
embeddable as maximal arcs in a projective plane of order $(v-k)/(k-1)$ is
proved, and a generalization of a conjecture by Andries Brouwer \cite{Br} is
formulated.


title:
Constraining scalar-Gauss-Bonnet Inflation by Reheating, Unitarity and
  PLANCK

abstract:
  We revisit the inflationary dynamics in detail for theories with Gauss-Bonnet
gravity coupled to scalar functions, in light of the Planck data. Considering
the chaotic inflationary scenario, we constrain the parameters of two models
involving inflaton-Gauss-Bonnet coupling by current Planck data. For non zero
inflaton-Gauss-Bonnet coupling $\beta$, an inflationary analysis provides us a
big cosmologically viable region in the space of $(m,\beta)$, where $m$ is the
mass of inflaton. However, we study further on constraining $\beta$ arising
from reheating considerations and unitarity of tree-level amplitude involving
we have studied the constraints on $\beta$ arising from reheating
considerations and unitarity of tree level amplitude involving $2$ graviton
$\rightarrow 2$ graviton ($h h\rightarrow hh$) scattering. Our analysis,
particularly on reheating significantly reduces the parameter space of
$(m,\beta)$ for all models. he quadratic Gauss-Bonnet coupling parameter turns
out to be more strongly constrained than that of the linear coupling. For the
linear Gauss-Bonnet coupling function, we obtain $\beta \lesssim 10^3$, with
the condition $\beta (m/M_P)^2 \simeq 10^{-4}$. However, study of the Higgs
inflation scenario in the presence of Gauss-Bonnet term turned out to be
strongly disfavored.


title:
Fusion and quasifission dynamics in the reactions $^{48}$Ca+$^{249}$Bk
  and $^{50}$Ti+$^{249}$Bk using TDHF

abstract:
  Background: Synthesis of superheavy elements (SHE) with fusion-evaporation
reactions is strongly hindered by the quasifission (QF) mechanism which
prevents the formation of an equilibrated compound nucleus and which depends on
the structure of the reactants. New SHE have been recently produced with
doubly-magic $^{48}$Ca beams. However, SHE synthesis experiments with
single-magic $^{50}$Ti beams have so far been unsuccessful. Purpose: In
connection with experimental searches for $Z=117,119$ superheavy elements, we
perform a theoretical study of fusion and quasifission mechanisms in
$^{48}$Ca,$^{50}$Ti+$^{249}$Bk reactions in order to investigate possible
differences in reaction mechanisms induced by these two projectiles. Methods:
The collision dynamics and the outcome of the reactions are studied using
unrestricted time-dependent Hartree-Fock (TDHF) calculations as well as the
density-constrained TDHF method to extract the nucleus-nucleus potentials and
the excitation energy in each fragment. Results: Nucleus-nucleus potentials,
nuclear contact times, masses and charges of the fragments, as well as their
kinetic and excitation energies strongly depend on the orientation of the
prolate $^{249}$Bk nucleus. Long contact times associated with fusion are
observed in collisions of both projectiles with the side of the $^{249}$Bk
nucleus, but not on collisions with its tip. The energy and impact parameter
dependences of the fragment properties, as well as their mass-angle and
mass-total kinetic energy correlations are investigated. Conclusions: Entrance
channel reaction dynamics are similar with both $^{48}$Ca and $^{50}$Ti
projectiles. Both are expected to lead to the formation of a compound nucleus
by fusion if they have enough energy to get in contact with the side of the
$^{249}$Bk target.


title:
On orders of approximation functions of generalized smoothness in
  Lorentz spaces

abstract:
  This paper considers the Lorentz space with mixed norm of periodic functions
of many variables and of the generalized Nikol'skii -- Besov classes. Estimates
for the order of approximation of the generalized Nikol'skii -- Besov classes
by partial sums of Fourier's series for multiple trigonometric system in
Lorentz spaces with mixed norm are obtained.


title: An Integration of General Relativity and Relativistic Quantum Theory

abstract:
  In previous work, the author extended the Poincare Lie algebra to include a
four position operator as a natural extension to a large fifteen parameter Lie
algebra of operators. We here propose to generalize the metric contained in
those structure constants to be the Riemann metric as determined by Einstein's
equations from the energy momentum tensor. This gives a new type of "Lie"
algebra whose structure constants are space-time dependent. One obtains a new
type of uncertainty principle in strong gravitational fields and an altered
spectra for the hydrogen atom.


title:
Time Evolution of the Matter Content of the Expanding Universe in the
  Framework of Brans-Dicke Gravity

abstract:
  A cosmological model has been constructed in the framework of Brans-Dicke
(BD) gravity, based on an inter-conversion between matter and dark energy, for
a spatially flat universe in the era of pressureless dust. To account for the
non-conservartion of the matter content, a function of time f(t) has been
arbitrarily put into the expression of the density of matter. By definition,
f(t) is proportional to the matter content of the universe. Using suitable
ansazes for scale factor and scalar field, the functional form of f(t) has been
determined from the BD field equations. The scale factor has been so chosen
that it would cause a signature flip of the deceleration parameter with time.
The function f(t) decreases monotonically with time, indicating a
transformation of matter into dark energy. Time dependence of the proportions
of matter and dark energy of the universe has been determined. The effect of
non-conservation of the matter content upon various cosmological parameters has
been explored in the present study. Two models of matter-energy interaction
have been proposed and f(t) has been expressed as a function of their
interaction term. The dark energy equation-of-state (EoS) parameter has been
expressed and analyzed in terms of f(t).


title:
Scalar field quasinormal frequencies of Reissner-Nordstr\"om black hole
  surrounded by quintessence by using he continued fraction method

abstract:
  We evaluate the quasinormal modes of massless scalar field around
Reissner-Nordstr$\ddot{\text{o}}$m black hole surrounded by a static and
spherically symmetric quintessence by using the continued fraction method. The
appropriate Frobenius series for three special cases of the quintessence
parameter $ \epsilon = -1/3, -2/3$ and $-1$ are derived successfully. We show
that the variation of quasinormal frequencies with charge of the black hole and
the quintessential parameters. The numerical results show that quintessence
field decreases oscillation frequencies of all angular momentum $l$ modes and
increases the damping time of $l>0$ modes.


title: Adversarially Learned Inference

abstract:
  We introduce the adversarially learned inference (ALI) model, which jointly
learns a generation network and an inference network using an adversarial
process. The generation network maps samples from stochastic latent variables
to the data space while the inference network maps training examples in data
space to the space of latent variables. An adversarial game is cast between
these two networks and a discriminative network is trained to distinguish
between joint latent/data-space samples from the generative network and joint
samples from the inference network. We illustrate the ability of the model to
learn mutually coherent inference and generation networks through the
inspections of model samples and reconstructions and confirm the usefulness of
the learned representations by obtaining a performance competitive with
state-of-the-art on the semi-supervised SVHN and CIFAR10 tasks.


title:
Summability estimates on transport densities with dirichlet regions on
  the boundary via symmetrization techniques

abstract:
  In this paper we consider the mass transportation problem in a bounded domain
$\Omega$ where a positive mass f + in the interior is sent to the boundary
$\partial\Omega$, appearing for instance in some shape optimization problems,
and we prove summability estimates on the associated transport density
$\sigma$, which is the transport density from a diffuse measure to a measure on
the boundary f -- = P \# f + (P being the projection on the boundary), hence
singular. Via a symmetrization trick, as soon as $\Omega$ is convex or
satisfies a uniform exterior ball condition, we prove L p estimates (if f +
$\in$ L p, then $\sigma$ $\in$ L p). Finally, by a counterexample we prove that
if f + $\in$ L $\infty$ $(\Omega)$ and f -- has bounded density w.r.t. the
surface measure on $\partial\Omega$, the transport density $\sigma$ between f +
and f -- is not necessarily in L $\infty$ $(\Omega)$, which means that the fact
that f -- = P \# f + is crucial.


title: On the denominators of the Taylor coefficients of G-functions

abstract:
  Let $\sum\_{n=0}^\infty a\_n z^n\in \overline{\mathbb Q}[[z]]$ be a
$G$-function, and, for any $n\ge0$, let $\delta\_n\ge 1$ denote the least
integer such that $\delta\_n a\_0, \delta\_n a\_1, ..., \delta\_n a\_n$ are all
algebraic integers. By definition of a $G$-function, there exists some constant
$c\ge 1$ such that $\delta\_n\le c^{n+1}$ for all $n\ge 0$. In practice, it is
observed that $\delta\_n$ always divides $D\_{bn}^{s} C^{n+1}$ where
$D\_n=lcm\{1,2, ..., n\}$, $b, C$ are positive integers and $s\ge 0$ is an
integer. We prove that this observation holds for any $G$-function provided the
following conjecture is assumed: {\em Let $\mathbb{K}$ be a number field, and
$L\in \mathbb{K}[z,\frac{d }{d z}]$ be a $G$-operator; then the generic radius
of solvability $R\_v(L)$ is equal to 1, for all finite places $v$ of
$\mathbb{K}$ except a finite number.} The proof makes use of very precise
estimates in the theory of $p$-adic differential equations, in particular the
Christol-Dwork Theorem. Our result becomes unconditional when $L$ is a
geometric differential operator, a special type of $G$-operators for which the
conjecture is known to be true. The famous Bombieri-Dwork Conjecture asserts
that any $G$-operator is of geometric type, hence it implies the above
conjecture.


title:
Geometry of Uhlenbeck partial compactification of orthogonal instanton
  spaces and the K-theoretic Nekrasov partition functions

abstract:
  Let $M^K_n$ be the moduli space of framed $K$-instantons over $S^4$ with
instanton number $n$ when $K$ is a compact simple Lie group of classical type.
Let $U^{K}_{n}$ be the Uhlenbeck partial compactification of $M^{K}_{n}$. A
scheme structure on $U^{K}_{n}$ is endowed by Donaldson as an algebro-geometric
Hamiltonian reduction of ADHM data. In this paper, for $K=SO(N,R)$, $N\ge5$, we
prove that $U^{K}_{n}$ is an irreducible normal variety with smooth locus
$M^{K}_{n}$. Hence, together with the author's previous result, the K-theoretic
Nekrasov partition function for any simple classical group other than
$SO(3,R)$, is interpreted as a generating function of Hilbert series of the
instanton moduli spaces.
  Using this approach we also study the case $K=SO(4,R)$ which is the unique
semisimple but non-simple classical group.


title: A Mean-Field Description for AdS Black Hole

abstract:
  In this paper we find an equivalent mean-field description for asymptotically
$AdS$ black hole in high temperature limit and in arbitrary dimensions. We
obtain a class of mean-field potential for which the description is valid. We
explicitly show that there is an one to one correspondence between the
thermodynamics of a gas of interacting particles moving under a mean-field
potential and an $AdS$ black hole, namely the equation of state, temperature,
pressure, entropy and enthalpy of both the systems match. In $3+1$ dimensions,
in particular, the mean-field description can be thought of as an ensemble of
tiny interacting {\it asymptotically flat} black holes moving in volume $V$ and
at temperature $T$. This motivates us to identify these asymptotically flat
black holes as microstructure of asymptotically $AdS$ black holes in $3+1$
dimensions.


title:
f-GAN: Training Generative Neural Samplers using Variational Divergence
  Minimization

abstract:
  Generative neural samplers are probabilistic models that implement sampling
using feedforward neural networks: they take a random input vector and produce
a sample from a probability distribution defined by the network weights. These
models are expressive and allow efficient computation of samples and
derivatives, but cannot be used for computing likelihoods or for
marginalization. The generative-adversarial training method allows to train
such models through the use of an auxiliary discriminative neural network. We
show that the generative-adversarial approach is a special case of an existing
more general variational divergence estimation approach. We show that any
f-divergence can be used for training generative neural samplers. We discuss
the benefits of various choices of divergence functions on training complexity
and the quality of the obtained generative models.


title:
A different interpretation of "Measuring propagation speed of Coulomb
  fields" by R. de Sangro, G. Finocchiaro, P. Patteri, M. Piccolo, G. Pizzella

abstract:
  We claim that the anti-relativistic statement in de Sangro et al., Eur. Phys.
J. C 75, 137 (2015) that the Coulomb field of a moving charge propagates
rigidly with it, cannot as a matter of fact be inferred from the measurements
reported in that reference. Registered is not the passing of the Coulomb disk,
but the acceleration-dependent part of the Lienard-Wiechert field.


title:
$k$-essence non-minimally coupled with Gauss-Bonnet invariant for
  inflation

abstract:
  In this paper, we investigated inflationary solutions for a subclass of
Horndeski models where a scalar field is non-minimally coupled with the
Gauss-Bonnet invariant. Examples of canonical scalar field and $k$-essence to
support the early-time acceleration are considered. The formalism to calculate
the perturbations in FRW universe and to derive the spectral index and the
tensor-to-scalar ratio is furnished.


title: Understanding the relativistic overdensity of galaxy surveys

abstract:
  The main goal of galaxy surveys is to map the distribution of the galaxies,
for the purpose of understanding the properties of this distribution and its
implications for the content and the evolution of the universe. However, in
order to realise the full potential of these surveys, we need to ensure that we
are using the correct analysis: a relativistic analysis, which has been widely
studied recently. In this work, the known relativistic overdensity of galaxy
surveys is re-examined. Unlike in previous works, a consistent approach for
incorporating both the relativistic number-count overdensity and the
relativistic cosmic magnification over-density in the total observed
overdensity of a generic survey, is presented. Since in practice, analyses are
often done for specific sample types (flux-limited or volume-limited) the
approach in this work allows for the total observed overdensity to be easily
reduced to either of the individual overdensities by applying the same limiting
conditions as for extracting the corresponding data samples. This is not
obvious, or in some cases not possible, with the results of previous works.
Thus, the calculations in this work serve to generalise the expression for the
total observed overdensity. However, care must be taken to apply it
appropriately: the type of the data sample in consideration needs to be taken
into account.


title: Relativistic model for anisotropic strange stars

abstract:
  In this article, we attempt to find a singularity free solution of Einstein's
field equations for compact stellar objects, precisely strange (quark) stars,
considering Schwarzschild metric as the exterior spacetime. To this end, we
consider that the stellar object is spherically symmetric, static and
anisotropic in nature and follows the density profile given by Mak and Harko
(2002), which satisfies all the physical conditions. To investigate different
properties of the ultra-dense strange stars we have employed the MIT bag model
for the quark matter. Our investigation displays an interesting feature that
the anisotropy of compact stars increases with the radial coordinate and
attains its maximum value at the surface which seems an inherent property for
the singularity free anisotropic compact stellar objects. In this connection we
also perform several tests for physical features of the proposed model and show
that these are reasonably acceptable within certain range. Further, we find
that the model is consistent with the energy conditions and the compact stellar
structure is stable with the validity of the TOV equation and Herrera cracking
concept. For the masses bellow the maximum mass point in mass vs radius curve
the typical behavior achieved within the framework of general relativity. We
have calculated the maximum mass and radius of the strange stars for the three
finite values of bag constant $B_g$.


title: Functions with uniform level sets

abstract:
  Functions with uniform level sets can represent orders, preference relations
or other binary relations and thus turn out to be a tool for scalarization that
can be used, e.g., in multicriteria optimization, decision theory, mathematical
finance, production theory and operator theory. Sets which are not necessarily
convex can be separated by functions with uniform level sets. This has a deep
impact on functional analysis, where many proofs require separation theorems.
This report focuses on properties of real-valued and extended-real-valued
functions with uniform level sets which are defined on a topological vector
space. This includes the extension of aspects and results given in an earlier
paper by Gerth (now Tammer) and Weidner. The functions may be, e.g.,
continuous, convex, strictly quasiconcave or sublinear. They can coincide with
a Minkowski functional or with an order unit norm on a subset of the space. As
a side result, we show that the core of a closed pointed convex cone is its
interior in an appropriate norm topology.


title: Measure of Node Similarity in Multilayer Networks

abstract:
  The weight of links in a network is often related to the similarity of the
nodes. Here, we introduce a simple tunable measure for analysing the similarity
of nodes across different link weights. In particular, we use the measure to
analyze homophily in a group of 659 freshman students at a large university.
Our analysis is based on data obtained using smartphones equipped with custom
data collection software, complemented by questionnaire-based data. The network
of social contacts is represented as a weighted multilayer network constructed
from different channels of telecommunication as well as data on face-to-face
contacts. We find that even strongly connected individuals are not more similar
with respect to basic personality traits than randomly chosen pairs of
individuals. In contrast, several socio-demographics variables have a
significant degree of similarity. We further observe that similarity might be
present in one layer of the multilayer network and simultaneously be absent in
the other layers. For a variable such as gender, our measure reveals a
transition from similarity between nodes connected with links of relatively low
weight to dis-similarity for the nodes connected by the strongest links. We
finally analyze the overlap between layers in the network for different levels
of acquaintanceships.


title: Random walk in a stratified medium

abstract: We study the recurrence properties of a random walk in a stratified medium.


title:
Biased Contribution Index: A Simpler Mechanism to Maintain Fairness in
  Peer to Peer Network

abstract:
  To maintain fairness, in the terms of resources shared by an individual peer,
a proper incentive policy is required in a peer to peer network. This letter
proposes, a simpler mechanism to rank the peers based on their resource
contributions to the network. This mechanism will suppress the free riders from
downloading the resources from the network. Contributions of the peers are
biased in such a way that it can balance the download and upload amount of
resources at each peer. This mechanism can be implemented in a distributed
system and it converges much faster than the other existing approaches.


title: Bergman projection induced by kernel with integral representation

abstract:
  Bounded Bergman projections $P_\omega:L^p_\omega(v)\to L^p_\omega(v)$,
induced by reproducing kernels admitting the representation
  $$
  \frac{1}{(1-\overline{z}\zeta)^\gamma}\int_0^1\frac{d\nu(r)}{1-r\overline{z}\zeta},
  $$ and the corresponding (1,1)-inequality are characterized in terms of
Bekoll\'e-Bonami-type conditions. The two-weight inequality for the maximal
Bergman projection $P^+_\omega:L^p_\omega(u)\to L^p_\omega(v)$ in terms of
Sawyer-testing conditions is also discussed.


title: Lumped Element Kinetic Inductance Detectors for space applications

abstract:
  Kinetic Inductance Detectors (KID) are now routinely used in ground-based
telescopes. Large arrays, deployed in formats up to kilopixels, exhibit
state-of-the-art performance at millimeter (e.g. 120-300 GHz, NIKA and NIKA2 on
the IRAM 30-meters) and sub-millimeter (e.g. 350-850 GHz AMKID on APEX)
wavelengths. In view of future utilizations above the atmosphere, we have
studied in detail the interaction of ionizing particles with LEKID (Lumped
Element KID) arrays. We have constructed a dedicated cryogenic setup that
allows to reproduce the typical observing conditions of a space-borne
observatory. We will report the details and conclusions from a number of
measurements. We give a brief description of our short term project, consisting
in flying LEKID on a stratospheric balloon named B-SIDE.


title: Differentially Private Gaussian Processes

abstract:
  A major challenge for machine learning is increasing the availability of data
while respecting the privacy of individuals. Here we combine the provable
privacy guarantees of the differential privacy framework with the flexibility
of Gaussian processes (GPs). We propose a method using GPs to provide
differentially private (DP) regression. We then improve this method by crafting
the DP noise covariance structure to efficiently protect the training data,
while minimising the scale of the added noise. We find that this cloaking
method achieves the greatest accuracy, while still providing privacy
guarantees, and offers practical DP for regression over multi-dimensional
inputs. Together these methods provide a starter toolkit for combining
differential privacy and GPs.


title: Decomposition of stencil update formula into atomic stages

abstract:
  In parallel solution of partial differential equations, a complex stencil
update formula that accesses multiple layers of neighboring grid points
sometimes must be decomposed into atomic stages, ones that access only
immediately neighboring grid points. This paper shows that this requirement can
be formulated as constraints of an optimization problem, which is equivalent to
the dual of a minimum-cost network flow problem. An optimized decomposition of
a single stencil on one set of grid points can thereby be computed efficiently.


title:
Inelastic collisions of ultracold triplet Rb$_\textbf{2}$ molecules in
  the rovibrational ground state

abstract:
  Exploring inelastic and reactive collisions on the quantum level is a main
goal of the developing field of ultracold chemistry. We present first
experimental studies of inelastic collisions of metastable ultracold triplet
molecules in the vibrational ground state. The measurements are performed with
nonpolar $\textrm{Rb}_2$ dimers which are prepared in precisely-defined quantum
states and trapped in an array of quasi-1D potential tubes. In particular, we
investigate collisions of molecules in the absolute lowest triplet energy level
where any inelastic process requires a change of the electronic state.
Nevertheless, we find similar decay rates as for collisions between
rotationally or vibrationally excited triplet molecules and they are close to
the rates for universal reactions. As anticipated theoretically, the measured
decay rate constants vary considerably when confinement and collision energy
are changed. This might be exploited to control the collisional properties of
molecules.


title: On deformation spaces of quadratic rational maps

abstract:
  We study the group of self-equivalences of a partially postcritically finite
branched cover and answer a question of Adam Epstein about contractibility of
certain deformation spaces of rational maps.


title: Intrinsic expansions for averaged diffusion processes

abstract:
  We show that the rate of convergence of asymptotic expansions for solutions
of SDEs is generally higher in the case of degenerate (or partial) diffusion
compared to the elliptic case, i.e. it is higher when the Brownian motion
directly acts only on some components of the diffusion. In the scalar case,
this phenomenon was already observed in (Gobet and Miri 2014) using Malliavin
calculus techniques. In this paper, we provide a general and detailed analysis
by employing the recent study of intrinsic functional spaces related to
hypoelliptic Kolmogorov operators in (Pagliarani et al. 2016). Relevant
applications to finance are discussed, in particular in the study of
path-dependent derivatives (e.g. Asian options) and in models incorporating
dependence on past information.


title:
Molecular dynamics of halogenated graphene - hexagonal boron nitride
  nanoribbons

abstract:
  The hybrid graphene - hexagonal boron nitride (G-hBN) systems offer new
routes in the design of nanoscale electronic devices. Using {\it ab initio}
density functional theory calculations we investigate the dynamics of zig-zag
nanoribbons a few interatomic distances wide. Several structures are analyzed,
namely pristine graphene, hBN and G-hBN systems. By passivating the nanoribbon
edges with hydrogen and different halogen atoms, one may tune the electronic
and mechanical properties, like the band gap energies and the natural
frequencies of vibration.


title: On Solving Floating Point SSSP Using an Integer Priority Queue

abstract:
  We address the single source shortest path planning problem (SSSP) in the
case of floating point edge weights. We show how any integer based Dijkstra
solution that relies on a monotone integer priority queue to create a full
ordering over path lengths in order to solve integer SSSP can be used as an
oracle to solve floating point SSSP with positive edge weights (floating point
P-SSSP). Floating point P-SSSP is of particular interest to the robotics
community. This immediately yields a handful of faster runtimes for floating
point P-SSSP; for example, ${O({m + n\log \log \frac{C}{\delta}})}$, where $C$
is the largest weight and $\delta$ is the minimum edge weight in the graph. It
also ensures that many future advances for integer SSSP will be transferable to
floating point P-SSSP.


title:
Orbital selective spin excitations and their impact on superconductivity
  of LiFe1-xCoxAs

abstract:
  We use neutron scattering to study spin excitations in single crystals of
LiFe$_{0.88}$Co$_{0.12}$As, which is located near the boundary of the
superconducting phase of LiFe$_{1-x}$Co$_{x}$As and exhibits non-Fermi-liquid
behavior indicative of a quantum critical point. By comparing spin excitations
of LiFe$_{0.88}$Co$_{0.12}$As with a combined density functional theory (DFT)
and dynamical mean field theory (DMFT) calculation, we conclude that
wave-vector correlated low energy spin excitations are mostly from the $d_{xy}$
orbitals, while high-energy spin excitations arise from the $d_{yz}$ and
$d_{xz}$ orbitals. Unlike most iron pnictides, the strong orbital selective
spin excitations in LiFeAs family cannot be described by anisotropic Heisenberg
Hamiltonian. While the evolution of low-energy spin excitations of
LiFe$_{1-x}$Co$_x$As are consistent with electron-hole Fermi surface nesting
condition for the $d_{xy}$ orbital, the reduced superconductivity in
LiFe$_{0.88}$Co$_{0.12}$As suggests that Fermi surface nesting conditions for
the $d_{yz}$ and $d_{xz}$ orbitals are also important for superconductivity in
iron pnictides.


title: $L^{2}$-Sobolev theory for the complex Green operator

abstract:
  These notes are concerned with the $L^{2}$-Sobolev theory of the complex
Green operator on pseudoconvex, oriented, bounded and closed CR--submanifolds
of $\mathbb{C}^{n}$ of hypersurface type. This class of submanifolds
generalizes that of boundaries of pseudoconvex domains. We first discuss
briefly the CR--geometry of general CR--submanifolds and then specialize to
this class. Next, we review the basic $L^{2}$-theory of the tangential
Cauchy-Riemann operator and the associated complex Green operator(s) on these
submanifolds. After these preparations, we discuss recent results on
compactness and regularity in Sobolev spaces of the complex Green operator(s).


title:
A Lagrangian fluctuation-dissipation relation for scalar turbulence, I.
  Flows with no bounding walls

abstract:
  An exact relation is derived between scalar dissipation due to molecular
diffusivity and the randomness of stochastic Lagrangian trajectories for flows
without bounding walls. This "Lagrangian fluctuation-dissipation relation"
equates the scalar dissipation for either passive or active scalars to the
variance of scalar inputs associated to initial scalar values and internal
scalar sources, as those are sampled backward in time by the stochastic
Lagrangian trajectories. As an important application, we reconsider the
phenomenon of "Lagrangian spontaneous stochasticity" or persistent
non-determinism of Lagrangian particle trajectories in the limit of vanishing
viscosity and diffusivity. Previous work on the Kraichnan (1968) model of
turbulent scalar advection has shown that anomalous scalar dissipation is
associated in that model to Lagrangian spontaneous stochasticity. There has
been controversy, however, regarding the validity of this mechanism for scalars
advected by an actual turbulent flow. We here completely resolve this
controversy by exploiting the fluctuation-dissipation relation. For either a
passive or active scalar advected by any divergence-free velocity field,
including solutions of the incompressible Navier-Stokes equation, and away from
walls, we prove that anomalous scalar dissipation requires Lagrangian
spontaneous stochasticity. For passive scalars we prove furthermore that
spontaneous stochasticity yields anomalous dissipation for suitable initial
scalar distributions, so that the two phenomena are there completely
equivalent. These points are illustrated by numerical results from a database
of homogeneous, isotropic turbulence, which provide both additional support to
the results and physical insight into the representation of diffusive effects
by stochastic Lagrangian particle trajectories.


title: Not all simple looking degree sequence problems are easy

abstract:
  Degree sequence (DS) problems are around for at least hundred twenty years,
and with the advent of network science, more and more complicated, structured
DS problems were invented. Interestingly enough all those problems so far are
computationally easy. It is clear, however, that we will find soon
computationally hard DS problems. In this paper we want to find such hard DS
problems with relatively simple definition.
  For a vertex $v$ in the simple graph $G$ denote $d_i(v)$ the number of
vertices at distance exactly $i$ from $v$. Then $d_1(v)$ is the usual degree of
vertex $v.$ The vector $\mathbf{d}^2(G)=( (d_1(v_1), d_2(v_1)), \ldots,$
$(d_1(v_n), d_2(v_n))$ is the {\bf second order degree sequence} of the graph
$G$. In this note we show that the problem to decide whether a sequence of
natural numbers $((i_1,j_1),\ldots (i_n,j_n))$ is a second order degree
sequence of a simple undirected graph $G$ is strongly NP-complete. Then we will
discuss some further NP-complete DS problems.


title: Epsilon_K in the Standard Model and the kaon phase conventions

abstract:
  The parameter epsilon_K, that quantifies CP violation in kaon mixing, is the
observable setting the strongest constraints on new physics with a generic
flavour and CP structure. While its experimental uncertainty is at the half
percent level, the theoretical one is at the level of 15%. One of the largest
sources of the latter uncertainty is the poor perturbative behaviour of the
short-distance contribution of the box diagram with two charm quarks. In this
proceeding, based on arXiv:1602.08494, I summarise how that contribution can be
removed, from the imaginary part of the mixing amplitude, by a rephasing of the
kaon fields. A first outcome is a mild reduction of the total theoretical
uncertainty of epsilon_K: while this might look counterintuitive at first
sight, if different "pieces" (i.e. short- and long-distance) of an observable
are computed with different techniques, then it is possible to choose a phase
convention where the total uncertainty of that observable is optimised.
Moreover, it is worthy to discuss if and how this freedom of rephasing, which
has been somehow overlooked in the past, can help in making progress in lattice
QCD computations of immediate relevance for epsilon_K.


title: Nearly Parallel Vortex Filaments in the 3D Ginzburg-Landau Equations

abstract:
  We introduce a framework to study the occurrence of vortex filament
concentration in $3D$ Ginzburg-Landau theory. We derive a functional that
describes the free-energy of a collection of nearly-parallel quantized vortex
filaments in a cylindrical $3$-dimensional domain, in certain scaling limits;
it is shown to arise as the $\Gamma$-limit of a sequence of scaled
Ginzburg-Landau functionals. Our main result establishes for the first time a
long believed connection between the Ginzburg-Landau functional and the energy
of nearly parallel filaments that applies to many mathematically and physically
relevant situations where clustering of filaments is expected. In this setting
it also constitutes a higher-order asymptotic expansion of the Ginzburg-Landau
energy, a refinement over the arclength functional approximation. Our
description of the vorticity region significantly improves on previous studies
and enables us to rigorously distinguish a collection of multiplicity one
vortex filaments from an ensemble of fewer higher multiplicity ones. As an
application, we prove the existence of solutions of the Ginzburg-Landau
equation that exhibit clusters of vortex filaments whose small-scale structure
is governed by the limiting free-energy functional.


title: Coherent light in intense spatio-spectral twin beams

abstract:
  Intense spatio-spectral twin beams generated in the regime with pump
depletion are analyzed applying a suggested quantum model that treats the
signal, idler and pump fields in the same way. The model assumes the signal and
idler fields in the form of the generalized superposition of signal and noise
and reveals nonzero signal coherent components in both fields, contrary to the
models developed earlier. The influence of coherent components on the
properties of intense twin beams is elucidated. The interference pattern formed
in the process of sum-frequency generation and that of the Hong-Ou-Mandel
interferometer are shown to be able to experimentally confirm the presence of
coherent components.


title:
Beyond Born-Mayer: Improved models for short-range repulsion in ab
  initio force fields

abstract:
  Short-range repulsion within inter-molecular force fields is conventionally
described by either Lennard-Jones (${A}/{r^{12}}$) or Born-Mayer ($A\exp(-Br)$)
forms. Despite their widespread use, these simple functional forms are often
unable to describe the interaction energy accurately over a broad range of
inter-molecular distances, thus creating challenges in the development of ab
initio force fields and potentially leading to decreased accuracy and
transferability. Herein, we derive a novel short-range functional form based on
a simple Slater-like model of overlapping atomic densities and an iterated
stockholder atom (ISA) partitioning of the molecular electron density. We
demonstrate that this Slater-ISA methodology yields a more accurate,
transferable, and robust description of the short-range interactions at minimal
additional computational cost compared to standard Lennard-Jones or Born-Mayer
approaches. Finally, we show how this methodology can be adapted to yield the
standard Born-Mayer functional form while still retaining many of the
advantages of the Slater-ISA approach.


title:
Universality properties of steady driven coagulation with collisional
  evaporation

abstract:
  Irreversible aggregation is an archetypal example of a system driven far from
equilibrium by sources and sinks of a conserved quantity (mass). The source is
a steady input of monomers and the evaporation of colliding particles with a
small probability is the sink. Using exact and heuristic analyses, we find a
universal regime and two distinct non-universal regimes distinguished by the
relative importance of mergers between small and large particles. At the
boundary between the regimes we find an analogue of the logarithmic correction
conjectured by Kraichnan for two-dimensional turbulence.


title: Simultaneous slow and fast light involving the Faraday effect

abstract:
  We theoretically study the linear transmission of linearly polarizedlight
pulses in an ensemble of cold atoms submitted to a static magneticfield
parallel to the direction of propagation. The carrier frequencyof the incident
pulses coincides with a resonance frequency of theatoms. The transmitted light,
the electric field of which is transversal,is examined in the polarizations
parallel and perpendicular to thatof the incident pulses. We give explicit
analytic expressions for thetransfer functions of the system for both
polarizations and for thecorresponding group delays. We demonstrate that slow
light can beobserved in a polarization, whereas fast light is simultaneously
observedin the perpendicular polarization. Moreover, we point out that, dueto
the polarization post selection, the system is not necessarilyminimum phase
shift. Slow light can then be obtained in situationswhere an irrelevant
application of the Kramers-Kronig relations could lead oneto expect fast light.
When the incident light is step modulated, wefinally show that, in suitable
conditions, the system enables oneto separate optical precursor and main field.


title: Hardware Decoders for Polar Codes: An Overview

abstract:
  Polar codes are an exciting new class of error correcting codes that achieve
the symmetric capacity of memoryless channels. Many decoding algorithms were
developed and implemented, addressing various application requirements: from
error-correction performance rivaling that of LDPC codes to very high
throughput or low-complexity decoders. In this work, we review the state of the
art in polar decoders implementing the successive-cancellation, belief
propagation, and list decoding algorithms, illustrating their advantages.


title: Product of octahedra is badly approximated in the $\ell_{2,1}$-metric

abstract:
  We prove that the cartesian product of octahedra
$B_{1,\infty}^{n,m}=B_1^n\times\ldots\times B_1^n$ ($m$ octahedra) is badly
approximated by half--dimensional subspaces in mixed--norm:
$d_{N/2}(B_{1,\infty}^{n,m},\ell_{2,1}^{n,m})\ge cm$, $N=mn$. As a corollary
the orders for linear widths of H\"older--Nikolskii classes $H^r_p(\mathbb
T^d)$ in the $L_q$ metric are obtained for $(p,q)$ in a certain set (a domain
in the parameter space).


title: Stochastic Structured Prediction under Bandit Feedback

abstract:
  Stochastic structured prediction under bandit feedback follows a learning
protocol where on each of a sequence of iterations, the learner receives an
input, predicts an output structure, and receives partial feedback in form of a
task loss evaluation of the predicted structure. We present applications of
this learning scenario to convex and non-convex objectives for structured
prediction and analyze them as stochastic first-order methods. We present an
experimental evaluation on problems of natural language processing over
exponential output spaces, and compare convergence speed across different
objectives under the practical criterion of optimal task performance on
development data and the optimization-theoretic criterion of minimal squared
gradient norm. Best results under both criteria are obtained for a non-convex
objective for pairwise preference learning under bandit feedback.


title: The Meaning of Null in Databases and Programming Languages

abstract:
  The meaning of null in relational databases is a major source of confusion
not only among database users but also among database textbook writers. The
purpose of this article is to examine what database nulls could mean and to
make some modest suggestions about how to reduce the confusion.


title:
Stochastic perturbations of iterations of a simple, non-expanding,
  nonperiodic, piecewise linear, interval-map

abstract:
  Let g(x)=x/2 + 17/30 (mod 1), let \xi_i, i= 1,2,... be a sequence of
independent, identically distributed random variables with uniform distribution
on the interval [0,1/15], define g_i(x)=g(x)+ \xi_i (mod 1) and, for n=1,2,...,
define g^n(x)=g_n(g_{n-1}(...(g_1(x))...)). For x \in [0,1) let \mu_{n,x}
denote the distribution of g^n(x). The purpose of this note is to show that
there exists a unique probability measure \mu, such that, for all x \in [0,1),
\mu_{n,x} tends to \mu, as n tends to infinity. This contradicts a claim by
Lasota and Mackey from 1987 stating that the process has an asymptotic
three-periodicity.


title:
Symmetry-protected coherent transport for diluted vacancies and adatoms
  in graphene

abstract:
  We study the effects of a low concentration of adatoms or single vacancies in
the linear-response transport properties of otherwise clean graphene. These
impurities were treated as localized orbitals, and for each type two cases with
distinct coupling symmetries were studied. For adatoms, we considered top- and
hollow-site adsorbates (TOP and HS). For vacancies, we studied impurity
formation by soft bond reconstruction (REC), as well as the more symmetric case
of charge accumulation in unreconstructed vacancies (VAC). Our results indicate
that the transport is determined by usual impurity scattering when the
graphene-impurity coupling does not possess $C_{3v}$ symmetry (TOP and REC). In
contrast, VAC impurities decouple from the electronic states at the Dirac
points, and yield no contribution to the resistivity for a sample in charge
neutrality. Furthermore, the inversion-symmetry-conserving HS impurities also
decouple from entire sets of momenta throughout the Brillouin zone, and do not
contribute to the resistivity within a broad range of parameters. These
behaviors are protected by $C_{3v}$ and inversion symmetry, respectively, and
persist for more general impurity models.


title: Chern-Simons modified gravity and closed time-like curves

abstract:
  We verify the consistency of the G\"odel-type solutions within the
four-dimensional Chern-Simons modified gravity with the non-dynamical
Chern-Simons coefficient, for different forms of matter including dust, fluid,
scalar field and electromagnetic field, and the related causality issues.
Unlike the general relativity, the vacuum solution turns out to be possible in
our theory. Another essentially new result of our theory having no analogue in
the general relativity consists in the existence of the hyperbolic causal
solutions for the physically well-motivated matter.


title:
Implications of Environmental Uncertainty for Business-IT Alignment: A
  Comparative Study of SMEs and Large Organizations

abstract:
  This paper presents a comprehensive study of the influence of environmental
uncertainty on business-IT alignment. The existing literature postulates
environmental uncertainty as a key challenge to achieving business-IT
alignment. Hence, the first objective of this study is to identify the extent
of the impact of environmental uncertainty on business-IT alignment, and to
determine its relative impact in the light of the other antecedents.
Furthermore, small and medium sized enterprises (SMEs) differ fundamentally
from large firms in many ways. Thus this paper also aims to investigate the
variation between SMEs and large firms with regard to the antecedents for
strategic alignment. Based on data collected from 212 firms, a conceptual model
is tested against the research objectives. The findings provide important
contributions to both research and practice by demonstrating the relative
impact of environmental uncertainty, and showing how the antecedents of
alignment vary between SMEs and large firms.


title:
A Multi Perspective Approach for Understanding the Determinants of Cloud
  Computing Adoption among Australian SMEs

abstract:
  Cloud computing is proved to be an effective computing technology for
organisations through the advantages that it offers such as cost-effectiveness,
IT technical agility and scalability, enhancing businesses processes, and
increasing enterprises competitiveness. In Australia, there is an emerging
trend that small and medium-sized enterprises (SMEs) begin to adopt this
technology in the conventional working practices. However, there is a dearth of
prior studies on examining the factors that influence the cloud computing
adoption among Australian SMEs. To fill the empirical vacuum, this
research-in-progress proposes an integrated framework for examining the
determinants of cloud computing service adoption with the consideration of the
unique characteristics of Australian SMEs, such as relatively low adoption of
cloud computing services, less innovative, and limited knowledge about cloud
computing and its benefits and hindrances. To this end, we are conducting
consecutive studies to investigate this research issue. An exploratory
interview study will be undertaken to identify and verify the unique
characteristics of Australian SMEs toward the cloud computing adoption. This is
followed by an organisational level survey that examines the effects of those
determinants on cloud computing adoption. Finally, a decision model for cloud
computing adoption among Australian SMEs will be developed by using a Multi
Criteria Decision Approach (MCDA) through rating, prioritising, and ranking of
various criteria and alternatives available to the decision makers. Adopting
the mixed-method research fashion, this research-in-progress intends to make
significant implications to scholars and practitioners alike in the cloud
computing research and applications areas.