title:
Exclusive $J/\psi$ production at the LHC in the $k_T$ factorization
  approach

abstract:
  The recent LHCb data for exclusive $J/\psi$ peripheral production at 13 TeV
motivate an improved `NLO' analysis to estimate the gluon distribution at low
$x$ in which we re-calculate the rapidity gap survival factors and use a more
precise expression for the photon flux. We comment on the difference between
the $k_T$ and collinear factorization approaches.


title:
Radiative decays of $1^{++}$ heavy mesons in the covariant light-front
  approach

abstract:
  We calculate the predicted width for the radiative decay of a $1^{++}$ heavy
meson via the channel $1^{++} \to 1^{--} +\gamma$ in the covariant light-front
quark model. Specifically, we compute the decay widths for $\chi_{c1}(1P) \to
J/\psi + \gamma$ and $\chi_{b1}(nP) \to \Upsilon(n'S) + \gamma$. The results
are compared with experimental data and with predictions from calculations
based on nonrelativistic models and their extensions to include relativistic
effects.


title:
Wigner crystallization in transition metal dichalcogenides: A new
  approach to correlation energy

abstract:
  We introduce a new approach for the correlation energy of one- and two-valley
two-dimensional electron gas (2DEG) systems. Our approach is based on a random
phase approximation at high densities and a classical approach at low
densities, with interpolation between the two limits. This approach gives
excellent agreement with available Quantum Monte Carlo (QMC) calculations. We
employ the two-valley 2DEG model to describe the electron correlations in
monolayer transition metal dichalcogenides (TMDs). The zero-temperature
transition from a Fermi liquid to a quantum Wigner crystal phase in monolayer
TMDs is obtained using density-functional theory within the local-density
approximation. Consistent with QMC, we find that electrons crystallize at
$r_s=30.5$ in one-valley 2DEG. For two-valleys, we predict Wigner
crystallization at $r_s= 29.5$, indicating that valley degeneracy has little
effect on the critical $r_s$, in contrast to an earlier claim.


title: Computational Interpretations of Markov's principle

abstract:
  Markov's principle is a statement that originated in the Russian school of
Constructive Mathematics and stated originally that "if it is impossible that
an algorithm does not terminate, then it will terminate". This principle has
been adapted to many different contexts, and in particular we are interested in
its most common version for arithmetic, which can be stated as "given a total
recursive function f , if it is impossible that there is no n for which f(n) =
0, then there exists an n such that f(n) = 0". This is in general not accepted
in constructivism, where stating an existential statement requires one to be
able to show at request a witness for the statement: here there is no clear way
to choose such an n. We introduce more in detail the context of constructive
mathematics from different points of view, and we show how they are related to
Markov's principle. In particular, several realizability semantics are
presented, which provide interpretations of logical systems by means of
different computational concepts (mainly, recursive functions and lambda
calculi). This field of research gave origin to the well known paradigm often
called Curry-Howrd isomorphism, or also propositions as types, that states a
correspondence between proofs in logic and programs in computer science. Thanks
to this the field of proof theory, that is the metamathematical investigations
of proofs as mathematical objects, became of interest for computer science and
in particular for the study of programming languages. By using modern research
on the Curry-Howard isomorphism, we will obtain a more refined interpretation
of Markov's principle. We will then use this results to investigate the logical
properties of systems related to the principle, and introduce a proof
transformation technique to interpret constructively some non-constructive
proofs of arithmetic.


title:
On the optimality of ternary arithmetic for compactness and hardware
  design

abstract:
  In this paper, the optimality of ternary arithmetic is investigated under
strict mathematical formulation. The arithmetic systems are presented in
generic form, as the means to encode numeric values, and the choice of radix is
asserted as the main parameter to assess the efficiency of the representation,
in terms of information compactness and estimated implementation cost in
hardware. Using proper formulations for the optimization task, the universal
constant 'e' (base of natural logarithms) is proven as the most efficient radix
and ternary is asserted as the closest integer choice.


title: Non-ergodicity in open quantum systems through quantum feedback

abstract:
  It is well known that quantum feedback can alter the dynamics of open quantum
systems dramatically. In this paper, we show that non-ergodicity may be induced
through quantum feedback and resultantly create system dynamics that have
lasting dependence on initial conditions. To demonstrate this, we consider an
optical cavity inside an instantaneous quantum feedback loop, which can be
implemented relatively easily in the laboratory. Non-ergodic quantum systems
are of interest for applications in quantum information processing, quantum
metrology and quantum sensing and could potentially aid the design of thermal
machines whose efficiency is not limited by the laws of classical
thermodynamics.


title:
Solid-state ensemble of highly entangled photon sources at rubidium
  atomic transitions

abstract:
  Semiconductor InAs/GaAs quantum dots grown by the Stranski-Krastanov method
are among the leading candidates for the deterministic generation of
polarization entangled photon pairs. Despite remarkable progress in the last
twenty years, many challenges still remain for this material, such as the
extremely low yield (<1% quantum dots can emit entangled photons), the low
degree of entanglement, and the large wavelength distribution. Here we show
that, with an emerging family of GaAs/AlGaAs quantum dots grown by droplet
etching and nanohole infilling, it is possible to obtain a large ensemble
(close to 100%) of polarization-entangled photon emitters on a wafer without
any post-growth tuning. Under pulsed resonant two-photon excitation, all
measured quantum dots emit single pairs of entangled photons with ultra-high
purity, high degree of entanglement (fidelity up to F=0.91, with a record high
concurrence C=0.90), and ultra-narrow wavelength distribution at rubidium
transitions. Therefore, a solid-state quantum repeater - among many other key
enabling quantum photonic elements - can be practically implemented with this
new material.


title: Hierarchical Object Detection with Deep Reinforcement Learning

abstract:
  We present a method for performing hierarchical object detection in images
guided by a deep reinforcement learning agent. The key idea is to focus on
those parts of the image that contain richer information and zoom on them. We
train an intelligent agent that, given an image window, is capable of deciding
where to focus the attention among five different predefined region candidates
(smaller windows). This procedure is iterated providing a hierarchical image
analysis.We compare two different candidate proposal strategies to guide the
object search: with and without overlap. Moreover, our work compares two
different strategies to extract features from a convolutional neural network
for each region proposal: a first one that computes new feature maps for each
region proposal, and a second one that computes the feature maps for the whole
image to later generate crops for each region proposal. Experiments indicate
better results for the overlapping candidate proposal strategy and a loss of
performance for the cropped image features due to the loss of spatial
resolution. We argue that, while this loss seems unavoidable when working with
large amounts of object candidates, the much more reduced amount of region
proposals generated by our reinforcement learning agent allows considering to
extract features for each location without sharing convolutional computation
among regions.


title:
Functional Fit Approach (FFA) for Density of States method: SU(3) spin
  system and SU(3) lattice gauge theory with static color sources

abstract:
  We apply a recently developed variant of the Density of States (DoS) method,
the so-called Functional Fit Approach (FFA) to two different models: the SU(3)
spin model and SU(3) lattice gauge theory with static color sources. Both
models can be derived from QCD and inherit the complex action problem at finite
density. We discuss the implementation of DoS FFA in the two models and compute
observables related to the particle density. For the SU(3) spin model we show
that the results are in good agreement with the results from a Monte Carlo
simulation in the dual formulation, which is free of the complex action
problem. For the case of SU(3) lattice gauge theory with static color sources
we present first results for the particle number as a function of the coupling
for different values of the chemical potential.


title:
Non-Gaussianities due to Relativistic Corrections to the Observed Galaxy
  Bispectrum

abstract:
  High-precision constraints on primordial non-Gaussianity (PNG) will
significantly improve our understanding of the physics of the early universe.
Among all the subtleties in using large scale structure observables to
constrain PNG, accounting for relativistic corrections to the clustering
statistics is particularly important for the upcoming galaxy surveys covering
progressively larger fraction of the sky. We focus on relativistic projection
effects due to the fact that we observe the galaxies through the light that
reaches the telescope on perturbed geodesics. These projection effects can give
rise to an effective $f_{\rm NL}$ that can be misinterpreted as the primordial
non-Gaussianity signal and hence is a systematic to be carefully computed and
accounted for in modelling of the bispectrum. We develop the technique to
properly account for relativistic effects in terms of purely observable
quantities, namely angles and redshifts. We give some examples by applying this
approach to a subset of the contributions to the tree-level bispectrum of the
observed galaxy number counts calculated within perturbation theory and
estimate the corresponding non-Gaussianity parameter, $f_{\rm NL}$, for the
local, equilateral and orthogonal shapes. For the local shape, we also compute
the local non-Gaussianity resulting from terms obtained using the consistency
relation for observed number counts. Our goal here is not to give a precise
estimate of $f_{\rm NL}$ for each shape but rather we aim to provide a scheme
to compute the non-Gaussian contamination due to relativistic projection
effects. For the terms considered in this work, we obtain contamination of
$f_{\rm NL}^{\rm loc} \sim {\mathcal O}(1)$.


title:
Spatio-Temporal Waveform Design for Multi-user Massive MIMO Downlink
  with 1-bit Receivers

abstract:
  Internet-of-Things (IoT) refers to a high-density network of low-cost
low-bitrate terminals and sensors where also low energy consumption is one
central feature. As the power-budget of classical receiver chains is dominated
by the high-resolution analog-to-digital converters (ADCs), there is a growing
interest towards deploying receiver architectures with reduced-bit or even
1-bit ADCs. In this paper, we study waveform design, optimization and detection
aspects of multi-user massive MIMO downlink where user terminals adopt very
simple 1-bit ADCs with oversampling. In order to achieve spectral efficiency
higher than 1 bit/s/Hz per real-dimension, we propose a two-stage precoding,
namely a novel quantization precoder followed by maximum-ratio transmission
(MRT) or zero-forcing (ZF) type spatial channel precoder which jointly form the
multi-user-multiantenna transmit waveform. The quantization precoder outputs
are optimized, under appropriate transmitter and receiver filter bandwidth
constraints, to provide controlled inter-symbol-interference (ISI) enabling the
input symbols to be uniquely detected from 1-bit quantized observations with a
low-complexity symbol detector in the absence of noise. An additional
optimization constraint is also imposed in the quantization precoder design to
increase the robustness against noise and residual inter-user-interference
(IUI). The purpose of the spatial channel precoder, in turn, is to suppress the
IUI and provide high beamforming gains such that good symbol-error rates (SERs)
can be achieved in the presence of noise and interference. Extensive numerical
evaluations illustrate that the proposed spatio-temporal precoder based
multiantenna waveform design can facilitate good multi-user link performance,
despite the extremely simple 1-bit ADCs in the receivers, hence being one
possible enabling technology for the future low-complexity IoT networks.


title: A Decade of WHIM Searches: Where do we Stand and Where do we Go?

abstract:
  In this article we first review the past decade of efforts in detecting the
missing baryons in the Warm Hot Intergalactic Medium (WHIM) and summarize the
current state of the art by updating the baryon census and physical state of
the detected baryons in the local Universe. We then describe observational
strategies that should enable a significant step forward in the next decade,
while waiting for the step-up in quality offered by future missions. In
particular we design a multi-mega-second and multiple cycle XMM-Newton legacy
program (which we name the Ultimate Roaming Baryon Exploration, or URBE) aimed
to secure detections of the peaks in the density distribution of the Universe
missing baryons over their entire predicted range of temperatures.


title:
CHEERS: Future perspectives for abundance measurements in clusters with
  XMM-Newton

abstract:
  The CHEERS (CHEmical Enrichment RGS Sample) observations of clusters of
galaxies with XMM-Newton have shown to be valuable to constrain the chemical
evolution of the universe. The soft X-ray spectrum contains lines of the most
abundant metals from N to Ni, which provide relatively accurate abundances that
can be compared to supernova enrichment models. The accuracy of the abundances
is currently limited by systematic uncertainties introduced by the available
instruments and uncertainties in the modeling of the spectra, which are of the
order of 20-30%. We discuss the possible gain of extending the current samples
at low and high redshift. We conclude that expanding the samples would be
expensive in terms of exposure time, but will not yield significantly improved
results, because the current samples already reach the systematic limits. New
instrumentation, like Astro-H2 and ATHENA, and improvements to the atomic
databases are needed to make significant advances in this field.


title: Enhanced superconductivity in hole-doped Nb$_{2}$PdS$_{5}$

abstract:
  We synthesized a series of Nb$_{2}$Pd$_{1-x}$Ru$_{x}$S$_{5}$ polycrystalline
samples by a solid-state reaction method and systematically investigated the
Ru-doping effect on superconductivity by transport and magnetic measurements.
It is found that superconductivity is enhanced with Ru doping and is quite
robust upon disorder. Hall coefficient measurements indicate that the charge
transport is dominated by hole-type charge carriers similar to the case of Ir
doping, suggesting multi-band superconductivity. Upon Ru or Ir doping, \emph
H$_{c2}$/$\emph T_c$ exhibits a significant enhancement, exceeding the Pauli
paramagnetic limit value by a factor of approximately 4. A comparison of $T_c$
and the upper critical field ($H_{c2}$) amongst the different doping elements
on Pd site, reveals a significant role of spin--orbit coupling.


title:
Practical Interpolation for Spectrum Cartography through Local Path Loss
  Modeling

abstract:
  A fundamental building block for supporting better utilization of radio
spectrum involves predicting the impact that an emitter will have at different
geographic locations. To this end, fixed sensors can be deployed to spatially
sample the RF environment over an area of interest, with interpolation methods
used to infer received power at locations between sensors. This paper describes
a radio map interpolation method that exploits the known properties of most
path loss models, with the aim of minimizing the RMS errors in predicted
dB-power. We show that the results come very close to those for ideal Simple
Kriging. Moreover, the method is simpler in terms of real-time computation by
the network and it requires no knowledge of the spatial correlation of shadow
fading. Our analysis of the method is general, but we exemplify it for a
specific network geometry, comprising a grid-like pattern of sensors. We also
provide comparisons to other widely used interpolation methods.


title:
Next-to-leading order prediction for the decay $\mu \to e \, (e^+e^-) \,
  \nu \bar{\nu}$

abstract:
  We present the differential decay rates and the branching ratios of the muon
decay with internal conversion, $\mu \to e \, (e^+e^-) \, \nu \bar{\nu}$, in
the Standard Model at next-to-leading order (NLO) in the on-shell scheme. This
rare decay mode of the muon is among the main sources of background to the
search for $\mu \to eee$ decay. We found that in the phase space region where
the neutrino energies are small, and the three-electron momenta have a similar
signature as in the $\mu \to eee$ decay, the NLO corrections decrease the
leading-order prediction by about $10-20\%$


title:
Modelling of a compact anisotropic star as an anisotropic fluid sphere
  in $f(T)$ gravity

abstract:
  In this paper, we have studied the new exact model of anisotropic star in
$f(T)$ theory of gravity. The dynamical equations in $f(T)$ theory with the
anisotropic fluid have been solved by using Krori-Barua solution. We have
determined that all the obtained solutions are free from central singularity
and potentially stable. The observed values of mass and radius of the different
strange stars RX J 1856-37, Her X-1, and Vela X-12 have been used to calculate
the values of unknown constants in Krori and Barua metric. The physical
parameters like anisotropy, stability and redshift of the stars have been
investigated in detail.


title: A New Class of Cosmologically `Viable' $f(R)$ Models

abstract:
  Instead of assuming a form of gravity and demand cosmology fit with $\Lambda
CDM$, a potentially `viable' $f(R)$ gravity model is derived assuming an
alternative model of cosmology. Taking the `designer' approach to $f(R)$, a new
class of solutions are derived starting with linear coasting cosmology in which
scale factor linearly increases with time during matter domination. The derived
forms of $f(R)$ are presented as result.


title: Lower current large deviations for zero-range processes on a ring

abstract:
  We study lower large deviations for the current of totally asymmetric
zero-range processes on a ring with concave current-density relation. We use an
approach by Jensen and Varadhan which has previously been applied to exclusion
processes, to realize current fluctuations by travelling wave density profiles
corresponding to non-entropic weak solutions of the hyperbolic scaling limit of
the process. We further establish a dynamic transition, where large deviations
of the current below a certain value are no longer typically attained by
non-entropic weak solutions, but by condensed profiles, where a non-zero
fraction of all the particles accumulates on a single fixed lattice site. This
leads to a general characterization of the rate function, which is illustrated
by providing detailed results for four generic examples of jump rates,
including constant rates, decreasing rates, unbounded sublinear rates and
asymptotically linear rates. Our results on the dynamic transition are
supported by numerical simulations using a cloning algorithm.

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


title: Some Properties of the Nil-Graphs of Ideals of Commutative Rings

abstract:
  Let $R$ be a commutative ring with identity and ${\rm Nil}(R)$ be the set of
nilpotent elements of $R$. The nil-graph of ideals of $R$ is defined as the
graph $\mathbb{AG}_N(R)$ whose vertex set is $\{I:\ (0)\neq I\lhd R$ and there
exists a non-trivial ideal $J$ such that $IJ\subseteq {\rm Nil}(R)\}$ and two
distinct vertices $I$ and $J$ are adjacent if and only if $IJ\subseteq {\rm
Nil}(R)$. Here, we study conditions under which $\mathbb{AG}_N(R)$ is complete
or bipartite. Also, the independence number of $\mathbb{AG}_N(R)$ is
determined, where $R$ is a reduced ring. Finally, we classify Artinian rings
whose nil-graphs of ideals have genus at most one.


title:
Qualitative Description of the Particle Trajectories for the
  $N$-Solitons Solution of the Korteweg-de Vries Equation

abstract:
  The qualitative properties of the particle trajectories of the $N$-solitons
solution of the KdV equation are recovered from the first order velocity field
by the introduction of the stream function. Numerical simulations show an
accurate depth dependance of the particles trajectories for solitary waves.
Failure of the free surface kinematic boundary condition for the first order
type velocity field is highlighted.


title:
Classification of inflationary models and constraints on fundamental
  physics

abstract:
  This work is focused on the study of early time cosmology and in particular
on the study of inflation. After an introduction on the standard Big Bang
theory, we discuss the physics of CMB and we explain how its observations can
be used to set constraints on cosmological models. We introduce inflation and
we carry out its simplest realization by presenting the observables and the
experimental constraints that can be set on inflationary models. The
possibility of observing primordial gravitational waves (GWs) produced during
inflation is discussed. We present the reasons to define a classification of
inflationary models and introduce the \beta-function formalism for inflation by
explaining why in this framework we can naturally define a set of universality
classes for inflationary models. Theoretical motivations to support the
formulation of inflation in terms of this formalism are presented. Some
generalized models of inflation are introduced and the extension of the
\beta-function formalism for inflation to these models is discussed. Finally we
focus on the study of models where the (pseudo-scalar) inflaton is coupled to
some Abelian gauge fields that can be present during inflation. The analysis of
the problem is carried out by using a characterization of inflationary models
in terms of their asymptotic behavior. A wide set of theoretical aspects and of
observational consequences is discussed.


title:
Attenuation from the optical to the extreme ultraviolet by dust
  associated with broad absorption line quasars: the driving force for outflows

abstract:
  We use mid-IR to UV observations to derive a mean attenuation curve out to
the rest-frame extreme ultraviolet (EUV) for "BAL dust" -- the dust causing the
additional extinction of active galactic nuclei (AGNs) with broad absorption
lines (BALQSOs). In contrast to the normal, relatively flat, mean AGN
attenuation curve, BAL dust is well fit by a steeply rising, SMC-like curve. We
confirm the shape of the theoretical Weingartner & Draine SMC curve out to 700
\AA, but the drop in attenuation at still shorter wavelengths is less than
predicted. The identical attenuation curve for low-ionization BALQSOs (LoBALs)
does not support them being a "break out" phase in the life of AGNs. Although
attenuation in the optical due to BAL dust is low ($E(B-V) \sim 0.03 - 0.05$),
the attenuation rises to one magnitude in the EUV because of the steep
extinction curve. Here the dust optical depth is at the optimum value for
radiative acceleration of dusty gas. Because the spectral energy distribution
of AGNs peaks in the EUV where the optical depth is highest, the force on the
dust dominates the acceleration of BAL gas. For LoBALs we get a negative
attenuation curve in the optical. This is naturally explained if there is more
light scattered into our line of sight in LoBALs compared with non-BALQSOs. We
suggest that this and partial covering are causes when attenuation curves
appear to be steeper in the UV that an SMC curve.


title:
On the oscillation-driven cosmological expansion at the post-inflation
  stage

abstract:
  Dynamics of the inflaton scalar field oscillating around a minimum of the
singular potentials in the expanding Universe is investigated. Asymptotic
formulas are obtained describing the cosmological expansion at the late times.
The problem of stability of the oscillations considered and the related
phenomenon of the field fragmentation are briefly discussed.


title:
Emission of extremely bright gamma-ray pulsar in the Large Magellanic
  Cloud

abstract:
  In the present paper a theoretical interpretation of observational
characteristics of the pulsar PSR J0540-6919 is suggested. In particular, we
provide a theoretical model explaining the presence of two peaks in the radio
domain and the brooding of these peaks at higher frequencies. The model also
explains the pulse-phase coincidence of emission peaks at different frequencies
and shows the physical, 'genetic' connection between the radio remission at
frequencies of the order of GHz with gamma-ray emission up to GeV energies.


title: A Formal Definition for Configuration

abstract:
  There exists a wide set of techniques to perform keyword-based search over
relational databases but all of them match the keywords in the users' queries
to elements of the databases to be queried as first step. The matching process
is a time-consuming and complex task. So, improving the performance of this
task is a key issue to improve the keyword based search on relational data
sources.In this work, we show how to model the matching process on
keyword-based search on relational databases by means of the symmetric group.
Besides, how this approach reduces the search space is explained in detail.


title: Radon depletion in xenon boil-off gas

abstract:
  An important background in detectors using liquid xenon for rare event
searches arises from the decays of radon and its daughters. We report for the
first time a reduction of $^{222}$Rn in the gas phase above a liquid xenon
reservoir. We show a reduction factor of $\gtrsim 4$ for the $^{222}$Rn
concentration in boil-off xenon gas compared to the radon enriched liquid
phase. A semiconductor-based $\alpha$-detector and miniaturized proportional
counters are used to detect the radon. As the radon depletion in the boil-off
gas is understood as a single-stage distillation process, this result
establishes the suitability of cryogenic distillation to separate radon from
xenon down to the $10^{-15}\,$mol/mol level.


title:
Rapid Stabilization of a Linearized Bilinear $1-D$ Schr\"odinger
  Equation

abstract:
  We consider the one dimensional Schr\"odinger equation with a bilinear
control and prove the rapid stabilization of the linearized equation around the
ground state. The feedback law ensuring the rapid stabilization is obtained
using a transformation mapping the solution to the linearized equation on the
solution to an exponentially stable target linear equation. A suitable
condition is imposed on the transformation in order to cancel the non-local
terms arising in the kernel system. This conditions also insures the uniqueness
of the transformation. The continuity and invertibility of the transformation
follows from exact controllability of the linearized system.


title: Diminishable Parameterized Problems and Strict Polynomial Kernelization

abstract:
  Kernelization---a mathematical key concept for provably effective
polynomial-time preprocessing of NP-hard problems---plays a central role in
parameterized complexity and has triggered an extensive line of research. This
is in part due to a lower bounds framework that allows to exclude
polynomial-size kernels under the assumption of NP $\nsubseteq$ coNP$/$poly. In
this paper we consider a restricted yet natural variant of kernelization,
namely strict kernelization, where one is not allowed to increase the parameter
of the reduced instance (the kernel) by more than an additive constant.
  Building on earlier work of Chen, Flum, and M\"{u}ller [Theory Comput. Syst.
2011] and developing a general and remarkably simple framework, we show that a
variety of FPT problems does not admit strict polynomial kernels under the
weaker assumption of P $\neq$ NP. In particular, we show that various
(multicolored) graph problems and Turing machine computation problems do not
admit strict polynomial kernels unless P $=$ NP. To this end, a key concept we
use are diminishable problems; these are parameterized problems that allow to
decrease the parameter of the input instance by at least one in polynomial
time, thereby outputting an equivalent problem instance. Finally, we study a
relaxation of the notion of strict kernels and reveal its limitations.


title:
Properties of the financial break-even point in a simple investment
  project as a function of the discount rate

abstract:
  We consider a simple investment project with the following parameters: I>0:
Initial investment which is amortizable in n years; n: Number of years the
investment allows production with constant output per year; A>0: Annual
amortization (A=I/n); Q>0: Quantity of products sold per year; Cv>0: Variable
cost per unit; p>0: Price of the product with p>Cv; Cf>0: Annual fixed costs;
te: Tax of earnings; r: Annual discount rate. We also assume inflation is
negligible. We derive a closed expression of the financial break-even point Qf
(i.e. the value of Q for which the net present value (NPV) is zero) as a
function of the parameters I, n, Cv, Cf, te, r, p. We study the behavior of Qf
as a function of the discount rate r and we prove that: (i) For r negligible Qf
equals the accounting break-even point Qc (i.e. the earnings before taxes (EBT)
is null) ; (ii) When r is large the graph of the function Qf=Qf(r) has an
asymptotic straight line with positive slope. Moreover, Qf(r) is an strictly
increasing and convex function of the variable r; (iii) From a sensitivity
analysis we conclude that, while the influence of p and Cv on Qf is strong, the
influence of Cf on Qf is weak.


title: Meshfree elastoplastic solid for nonsmooth multidomain dynamics

abstract:
  A method for simulation of elastoplastic solids in multibody systems with
nonsmooth and multidomain dynamics is developed. The solid is discretised into
pseudo-particles using the meshfree moving least squares method. The particles
carry strain and stress tensor variables that are mapped to deformation
constraints and constraint forces. The discretised solid model thus fit a
unified framework for nonsmooth multidomain dynamics for realtime simulations
including strong coupling of rigid multibodies with complex kinematic
constraints such as articulation joints, unilateral contacts with dry friction,
drivelines and hydraulics. The nonsmooth formulation allow for impulses, due to
impacts for instance, to propagate instantly between the rigid multibody and
the solid. Plasticity is introduced through an associative perfectly plastic
modified Drucker-Prager model. The elastic and plastic dynamics is verified for
simple test systems and the capability of simulating tracked terrain vehicles
driving on a deformable terrain is demonstrated.


title: Generalized Zermelo navigation on Hermitian manifolds under mild wind

abstract:
  We generalize and study the Zermelo navigation problem on Hermitian manifolds
in the presence of a perturbation $W$ determined by a mild complex velocity
vector field $||W(z)||_h<||u(z)||_h$, with application of complex Finsler
metric of complex Randers type. By admitting space-dependence of ship's
relative speed $||u(z)||_h\leq1$ we discuss the projectively related complex
Finsler metrics, the geodesics corresponding to the solutions of Zermelo's
problem, in particular the conformal case and the connections between the
corresponding background Hermitian metric $h$, new Hermitian metric $a$ and
resulting complex Randers metric $F$. Moreover, we present some necessary and
sufficient conditions for the obtained locally projectively flat solutions. Our
findings are also illustrated with several examples.


title: Experimental pre-assessing entanglement in Gaussian states mixing

abstract:
  We suggest and demonstrate a method to assess entanglement generation schemes
based on mixing of Gaussian states at a beam splitter (BS). Our method is based
on the fidelity criterion and represents a tool to analyze the effect of losses
and noise before the BS in both symmetric and asymmetric channels with and
without thermal effects. More generally, our scheme allows one to pre-assess
entanglement resources and to optimize the design of BS-based schemes for the
generation of continuous variable entanglement.


title: Microscopic and continuum descriptions of Janus motor fluid flow fields

abstract:
  Active media, whose constituents are able to move autonomously, display novel
features that differ from those of equilibrium systems. In addition to
naturally-occurring active systems such as populations of swimming bacteria,
active systems of synthetic self-propelled nanomotors have been developed.
These synthetic systems are interesting because of their potential applications
in a variety of fields. Janus particles, synthetic motors of spherical geometry
with one hemisphere that catalyzes the conversion of fuel to product and one
noncatalytic hemisphere, can propel themselves in solution by
self-diffusiophoresis. In this mechanism the concentration gradient generated
by the asymmetric catalytic activity leads to a force on the motor that induces
fluid flows in the surrounding medium. These fluid flows are studied in detail
through microscopic simulations of Janus motor motion and continuum theory. It
is shown that continuum theory is able to capture many but not all features of
the dynamics of the Janus motor and the velocity fields of the fluid.


title:
Dynamic Spanning Forest with Worst-Case Update Time: Adaptive, Las
  Vegas, and $O(n^{1/2-\epsilon})$-Time

abstract:
  We present two algorithms for dynamically maintaining a spanning forest of a
graph undergoing edge insertions and deletions. Our algorithms guarantee {\em
worst-case update time} and work against an adaptive adversary, meaning that an
edge update can depend on previous outputs of the algorithms. We provide the
first polynomial improvement over the long-standing $O(\sqrt{n})$ bound of
[Frederickson STOC'83, Eppstein, Galil, Italiano and Nissenzweig FOCS'92] for
such type of algorithms. The previously best improvement was $O(\sqrt{n
(\log\log n)^2/\log n})$ [Kejlberg-Rasmussen, Kopelowitz, Pettie and Thorup
ESA'16]. We note however that these bounds were obtained by deterministic
algorithms while our algorithms are randomized.
  Our first algorithm is Monte Carlo and guarantees an $O(n^{0.4+o(1)})$
worst-case update time, where the $o(1)$ term hides the $O(\sqrt{\log\log
n/\log n})$ factor. Our second algorithm is Las Vegas and guarantees an
$O(n^{0.49306})$ worst-case update time with high probability. Algorithms with
better update time either needed to assume that the adversary is oblivious
(e.g. [Kapron, King and Mountjoy SODA'13]) or can only guarantee an amortized
update time. Our second result answers an open problem by Kapron et al. To the
best of our knowledge, our algorithms are among a few non-trivial randomized
dynamic algorithms that work against adaptive adversaries.


title:
Finite volume corrections and low momentum cuts in the thermodynamics of
  quantum gases

abstract:
  The conjecture, that the finite volume corrections to the thermodynamic
functions can be correctly reproduced by using the thermodynamic limit with low
particle momenta cutoff is examined in a very transparent example of an ideal
boson gas in one dimension.
  We show that this conjecture is always true in principle, and derive
convenient relations for the momentum cutoff dependence on thermal parameters
in the asymptotic limits of large and small volume.


title:
Low rank factorization of the Coulomb integrals for periodic coupled
  cluster theory

abstract:
  We study the decomposition of the Coulomb integrals of periodic systems into
a tensor contraction of six matrices of which only two are distinct. We find
that the Coulomb integrals can be well approximated in this form already with
small matrices compared to the number of real space grid points. The cost of
computing the matrices scales as O(N^4) using a regularized form of the
alternating least squares algorithm. The studied factorization of the Coulomb
integrals can be exploited to reduce the scaling of the computational cost of
expensive tensor contractions appearing in the amplitude equations of coupled
cluster methods with respect to system size. We apply the developed
methodologies to calculate the adsorption energy of a single water molecule on
a hexagonal boron nitride monolayer in a plane wave basis set and periodic
boundary conditions.


title:
Systematic Classification of Side-Channel Attacks: A Case Study for
  Mobile Devices

abstract:
  Side-channel attacks on mobile devices have gained increasing attention since
their introduction in 2007. While traditional side-channel attacks, such as
power analysis attacks and electromagnetic analysis attacks, required physical
presence of the attacker as well as expensive equipment, an (unprivileged)
application is all it takes to exploit the leaking information on modern mobile
devices. Given the vast amount of sensitive information that are stored on
smartphones, the ramifications of side-channel attacks affect both the security
and privacy of users and their devices.
  In this paper, we propose a new categorization system for side-channel
attacks, which is necessary as side-channel attacks have evolved significantly
since their scientific investigations during the smart card era in the 1990s.
Our proposed classification system allows to analyze side-channel attacks
systematically, and facilitates the development of novel countermeasures.
Besides this new categorization system, the extensive survey of existing
attacks and attack strategies provides valuable insights into the evolving
field of side-channel attacks, especially when focusing on mobile devices. We
conclude by discussing open issues and challenges in this context and outline
possible future research directions.


title:
MCMC Shape Sampling for Image Segmentation with Nonparametric Shape
  Priors

abstract:
  Segmenting images of low quality or with missing data is a challenging
problem. Integrating statistical prior information about the shapes to be
segmented can improve the segmentation results significantly. Most shape-based
segmentation algorithms optimize an energy functional and find a point estimate
for the object to be segmented. This does not provide a measure of the degree
of confidence in that result, neither does it provide a picture of other
probable solutions based on the data and the priors. With a statistical view,
addressing these issues would involve the problem of characterizing the
posterior densities of the shapes of the objects to be segmented. For such
characterization, we propose a Markov chain Monte Carlo (MCMC) sampling-based
image segmentation algorithm that uses statistical shape priors. In addition to
better characterization of the statistical structure of the problem, such an
approach would also have the potential to address issues with getting stuck at
local optima, suffered by existing shape-based segmentation methods. Our
approach is able to characterize the posterior probability density in the space
of shapes through its samples, and to return multiple solutions, potentially
from different modes of a multimodal probability density, which would be
encountered, e.g., in segmenting objects from multiple shape classes. We
present promising results on a variety of data sets. We also provide an
extension for segmenting shapes of objects with parts that can go through
independent shape variations. This extension involves the use of local shape
priors on object parts and provides robustness to limitations in shape training
data size.


title: Dynamics of wetting explored with inkjet printing

abstract:
  An inkjet printer head, which is capable of depositing liquid droplets with a
resolution of $22$ picoliters and high repeatability, is employed to
investigate the wetting dynamics of drops printed on a horizontal plane as well
as on a granular monolayer. For a sessile drop on a horizontal plane, we
characterize the contact angle hysteresis, drop volume and contact line
dynamics from side view images. We show that the evaporation rate scales with
the dimension of the contact line instead of the surface area of the drop. We
demonstrate that the system evolves into a closed cycle upon repeating the
depositing-evaporating process, owing to the high repeatability of the printing
facility. Finally, we extend the investigation to a granular monolayer in order
to explore the interplay between liquid deposition and granular particles.


title: Top-k String Auto-Completion with Synonyms

abstract:
  Auto-completion is one of the most prominent features of modern information
systems. The existing solutions of auto-completion provide the suggestions
based on the beginning of the currently input character sequence (i.e. prefix).
However, in many real applications, one entity often has synonyms or
abbreviations. For example, "DBMS" is an abbreviation of "Database Management
Systems". In this paper, we study a novel type of auto-completion by using
synonyms and abbreviations. We propose three trie-based algorithms to solve the
top-k auto-completion with synonyms; each one with different space and time
complexity trade-offs. Experiments on large-scale datasets show that it is
possible to support effective and efficient synonym-based retrieval of
completions of a million strings with thousands of synonyms rules at about a
microsecond per-completion, while taking small space overhead (i.e. 160-200
bytes per string). The source code of our experiments can be download at:
http://udbms.cs.helsinki.fi/?projects/autocompletion/download .


title: Quantum Dynamics in Open Quantum-Classical Systems

abstract:
  Often quantum systems are not isolated and interactions with their
environments must be taken into account. In such open quantum systems these
environmental interactions can lead to decoherence and dissipation, which have
a marked influence on the properties of the quantum system. In many instances
the environment is well-approximated by classical mechanics, so that one is led
to consider the dynamics of open quantum-classical systems. Since a full
quantum dynamical description of large many-body systems is not currently
feasible, mixed quantum-classical methods can provide accurate and
computationally tractable ways to follow the dynamics of both the system and
its environment. This review focuses on quantum-classical Liouville dynamics,
one of several quantum-classical descriptions, and discusses the problems that
arise when one attempts to combine quantum and classical mechanics, coherence
and decoherence in quantum-classical systems, nonadiabatic dynamics,
surface-hopping and mean-field theories and their relation to quantum-classical
Liouville dynamics, as well as methods for simulating the dynamics.


title:
Properties of Star Clusters -- III: Analysis of 13 FSR Clusters using
  UKIDSS-GPS and VISTA-VVV

abstract:
  Discerning the nature of open cluster candidates is essential for both
individual and statistical analyses of cluster properties. Here we establish
the nature of thirteen cluster candidates from the FSR cluster list using
photometry from the 2MASS and deeper, higher resolution UKIDSS-GPS and
VISTA-VVV surveys. These clusters were selected because they were flagged in
our previous studies as expected to contain a large proportion of pre-main
sequence members or are at unusually small/large Galactocentric distances. We
employ a decontamination procedure of JHK photometry to identify cluster
members. Cluster properties are homogeneously determined and we conduct a cross
comparative study of our results with the literature (where available). Seven
of the here studied clusters were confirmed to contain PMS stars, one of which
is a newly confirmed cluster. Our study of FSR1716 is the deepest to date and
is in notable disagreement with previous studies, finding that it has a
distance of about 7.3kpc and age of 10-12Gyr. As such, we argue that this
cluster is a potential globular cluster candidate.


title:
Sparse Multichannel Blind Deconvolution of Seismic Data via Spectral
  Projected-Gradient

abstract:
  In this work, an efficient numerical scheme is presented for seismic blind
deconvolution in a multichannel scenario. The proposed method iterate with wo
steps: first, wavelet estimation across all channels and second, refinement of
the reflectivity estimate simultaneously in all channels using sparse
deconvolution. The reflectivity update step is formulated as a basis pursuit
denoising problem and a sparse solution is obtained with the spectral
projected-gradient algorithm - faithfulness to the recorded traces is
constrained by the measured noise level. Wavelet re-estimation has a closed
form solution when performed in the frequency domain by finding the minimum
energy wavelet common to all channels. Nothing is assumed known about the
wavelet apart from its time duration. In tests with both synthetic and real
data, the method yields sparse reflectivity series and stable wavelet estimates
results compared to existing methods with significantly less computational
effort.


title: Nearest-Neighbor Interaction Systems in the Tensor-Train Format

abstract:
  Low-rank tensor approximation approaches have become an important tool in the
scientific computing community. The aim is to enable the simulation and
analysis of high-dimensional problems which cannot be solved using conventional
methods anymore due to the so-called curse of dimensionality. This requires
techniques to handle linear operators defined on extremely large state spaces
and to solve the resulting systems of linear equations or eigenvalue problems.
In this paper, we present a systematic tensor-train decomposition for
nearest-neighbor interaction systems which is applicable to a host of different
problems. With the aid of this decomposition, it is possible to reduce the
memory consumption as well as the computational costs significantly.
Furthermore, it can be shown that in some cases the rank of the tensor
decomposition does not depend on the network size. The format is thus feasible
even for high-dimensional systems. We will illustrate the results with several
guiding examples such as the Ising model, a system of coupled oscillators, and
a CO oxidation model.


title:
Long term regularity of the one-fluid Euler-Maxwell system in 3D with
  vorticity

abstract:
  We prove long-term regularity of solutions of the one-fluid Euler-Maxwell
system in 3 spatial dimensions, in the case of small initial data with
nontrivial vorticity.


title: Holographic Heavy-Light Chiral Effective Action

abstract:
  We propose a variant of the $D4$-$D8$ construction to describe the low energy
effective theory of heavy-light mesons, interacting with the lowest lying
pseudoscalar and vector mesons. The heavy degrees of freedom are identified
with the $D8_L$-$D8_H$ string low energy modes, and are approximated near the
world volume of $N_f-1$ light $D8_L$ branes, by fundamental vector field valued
in $U(N_f-1)$. The effective action follows from the reduction of the bulk
D-brane Born-Infeld (DBI) and Chern-Simons (CS) actions, and is shown to
exhibit both chiral and heavy-quark symmetry. The action interpolates
continuously between the $U(N_f)$ case with massless mesons, and the $U(N_f-1)$
case with heavy-light mesons. The heavy-light meson radial spectrum is
Regge-like. The one-pion and two-pion couplings to the heavy-light multiplets
are evaluated. The partial widths for the charged decays $G\rightarrow H+\pi$
are shown to be comparable to the recently reported full widths for both the
charm and bottom mesons.


title: Hydrodynamic pairing of soft particles in a confined flow

abstract:
  The mechanism of hydrodynamics-induced pairing of soft particles, namely
closed bilayer membranes (vesicles, a model system for red blood cells) and
drops, is studied numerically with a special attention paid to the role of the
confinement (the particles are within two rigid walls). This study unveils the
complexity of the pairing mechanism due to hydrodynamic interactions. We find
both for vesicles and for drops that two particles attract each other and form
a stable pair at weak confinement if their initial separation is below a
certain value. If the initial separation is beyond that distance, the particles
repel each other and adopt a longer stable interdistance. This means that for
the same confinement we have (at least) two stable branches. To which branch a
pair of particles relaxes with time depends only on the initial configuration.
An unstable branch is found between these two stable branches. At a critical
confinement the stable branch corresponding to the shortest interdistance
merges with the unstable branch in the form of a saddle-node bifurcation. At
this critical confinement we have a finite jump from a solution corresponding
to the continuation of the unbounded case to a solution which is induced by the
presence of walls. The results are summarized in a phase diagram, which proves
to be of a complex nature. The fact that both vesicles and drops have the same
qualitative phase diagram points to the existence of a universal behavior,
highlighting the fact that with regard to pairing the details of mechanical
properties of the deformable particles are unimportant. This offers an
interesting perspective for simple analytical modeling.


title: Homological finiteness properties of fibre products

abstract: We study the homological finiteness property FPn of fibre products


title: Quantum heat traces

abstract:
  We study new invariants of elliptic partial differential operators acting on
sections of a vector bundle over a closed Riemannian manifold that we call the
relativistic heat trace and the quantum heat traces. We obtain some reduction
formulas expressing these new invariants in terms of some integral transforms
of the usual classical heat trace and compute the asymptotics of these
invariants. The coefficients of these asymptotic expansion are determined by
the usual heat trace coefficients (which are locally computable) as well as by
some new global invariants.

categories: math-ph hep-th math.AP math.DG math.MP math.SP


title:
Dendrimer Assisted Dispersion of Carbon Nanotubes: A Molecular Dynamics
  Study

abstract:
  Various unique physical, chemical, mechanical and electronic properties of
carbon nanotube (CNT) make it very useful materials for diverse potential
application in many fields. Experimentally synthesized CNTs are generally found
in bundle geometry with a mixture of different chirality and present a unique
challenge to separate them. In this paper we have proposed the PAMAM dendrimer
to be an ideal candidate for this separation. To estimate efficiency of the
dendrimer in dispersion of CNTs from the bundle geometry, we have calculated
potential of mean forces (PMF). Our PMF study of two dendrimer wrapped CNTs
shows lesser binding affinity compared to the two bare CNTs. PMF study shows
that the binding affinity decreases for non-protonated dendrimer and for the
protonated case, the interaction is fully repulsive in nature. For both the
non-protonated as well as protonated cases, the PMF increases with increasing
dendrimer generations from 2 to 4 gradually compare to the bare PMF. We have
performed PMF calculations with (6,5) and (6,6) chirality to study the
chirality dependence of PMF. Calculated PMF for protonated dendrimer wrapped
chiral CNTs is more compared to the protonated dendrimer wrapped armchair CNTs
for all the generations studied. However, for non-protonated dendrimer wrapped
CNTs such chirality dependence is not very prominent. Our study suggests that
the dispersion efficiency of protonated dendrimer is more compared to the
non-protonated dendrimer and can be used as an effective dispersing agent in
dispersion of CNT from the bundle geometry.


title:
Bright Metal-Poor Stars from the Hamburg/ESO Survey. II. A
  Chemodynamical Analysis

abstract:
  We obtain estimates of stellar atmospheric parameters for a previously
published sample of 1777 relatively bright (9 < B < 14) metal-poor candidates
from the Hamburg/ESO Survey. The original Frebel et al. analysis of these stars
was only able to derive estimates of [Fe/H] and [C/Fe] for a subset of the
sample, due to limitations in the methodology then available. A new
spectroscopic analysis pipeline has been used to obtain estimates of Teff, log
g, [Fe/H], and [C/Fe] for almost the entire dataset. This sample is very local
- about 90% of the stars are located within 0.5 kpc of the Sun. We consider the
chemodynamical properties of these stars in concert with a similarly local
sample of stars from a recent analysis of the Bidelman & MacConnell
'weak-metal' candidates by Beers et al. We use this combined sample to identify
possible members of the suggested halo stream of stars by Helmi et al. and
Chiba & Beers, as well as stars that may be associated with stripped debris
from the putative parent dwarf of the globular cluster Omega Centauri,
suggested to exist by previous authors. We identify a clear increase in the
cumulative frequency of carbon-enhanced metal-poor (CEMP) stars with declining
metallicity, as well as an increase in the fraction of CEMP stars with distance
from the Galactic plane, consistent with previous results. We also identify a
relatively large number of CEMP stars with kinematics consistent with the
metal-weak thick-disk population, with possible implications for its origin.


title: Superconformal Algebraic Approach to Hadron Structure

abstract:
  Fundamental aspects of nonperturbative QCD dynamics which are not obvious
from its classical Lagrangian, such as the emergence of a mass scale and
confinement, the existence of a zero mass bound state, the appearance of
universal Regge trajectories and the breaking of chiral symmetry are
incorporated from the onset in an effective theory based on superconformal
quantum mechanics and its embedding in a higher dimensional gravitational
theory. In addition, superconformal quantum mechanics gives remarkable
connections between the light meson and nucleon spectra. This new approach to
hadron physics is also suitable to describe nonperturbative QCD observables
based on structure functions, such as GPDs, which are not amenable to a
first-principle computation. The formalism is also successful in the
description of form factors, the nonperturbative behavior of the strong
coupling and diffractive processes. We also discuss in this article how the
framework can be extended rather successfully to the heavy-light hadron sector.


title:
Teichm\"uller space of negatively curved metrics on Complex Hyperbolic
  Manifolds is not contractible

abstract:
  In this paper we prove that for all $n=4k-2$, $k\ge2$ there exists a closed
smooth complex hyperbolic manifold $M$ with real dimension $n$ having
non-trivial $\pi_1(\mathcal{T}^{<0}(M))$. $\mathcal{T}^{<0}(M)$ denotes the
Teichm\"uller space of all negatively curved Riemannian metrics on $M$, which
is the topological quotient of the space of all negatively curved metrics
modulo the space of self-diffeomorphisms of $M$ that are homotopic to the
identity.


title:
Emulating Batteries with Deferrable Energy Demand: Fundamental
  Trade-offs and Scheduling Policies

abstract:
  We investigate the ability of a homogeneous collection of deferrable energy
loads to behave as a battery; that is, to absorb and release energy in a
controllable fashion up to fixed and predetermined limits on volume, charge
rate and discharge rate. We derive explicit bounds on the battery capacity that
can be offered, and show that there is a fundamental trade-off between the
abilities of collective load to absorb and release energy at high aggregate
rates. Finally, we introduce a new class of dynamic priority-driven feedback
policies that balance these abilities, and characterize the batteries that they
can emulate.


title: Periodic Parallelogram Polyominoes

abstract:
  A periodic parallelogram polyomino is a parallelogram polyomino such that we
glue the first and the last column. In this work we extend a bijection between
ordered trees and parallelogram polyominoes in order to compute the generating
function of periodic parallelogram polyominoes with respect to the height, the
width and the intrinsic thickness, a new statistic unrelated to the existing
statistics on parallelogram polyominoes. Moreover we define a rotation over
periodic parallelogram polyominoes, which induces a partitioning in equivalent
classes called strips. We also compute the generating function of strips using
the theory of P\'olya.


title:
Radio Measurements of the stellar proper motions in the core of the
  Orion Nebula Cluster

abstract:
  Using multi-epoch VLA observations, covering a time baseline of 29.1 years,
we have measured the proper motions of 88 young stars with compact radio
emission in the core of the Orion Nebula Cluster (ONC) and the neighboring
BN/KL region. Our work increases the number of young stars with measured proper
motion at radio frequencies by a factor of 2.5 and enables us to perform a
better statistical analysis of the kinematics of the region than was previously
possible. Most stars (79 out of 88) have proper motions consistent with a
Gaussian distribution centered on
$\overline{\mu_{\alpha}\cos{\delta}}=1.07\pm0.09\quad{\rm mas\,yr^{-1}}$, and
$\overline{\mu_{\delta}}=-0.84\pm0.16\quad{\rm mas\,yr^{-1}}$, with velocity
dispersions of $\sigma_{\alpha}=1.08\pm0.07\quad{\rm mas\,\,yr^{-1}},$
$\sigma_{\delta}=1.27\pm0.15\quad{\rm mas\,\,yr^{-1}}$. We looked for organized
movements of these stars but found no clear indication of radial
expansion/contraction or rotation. The remaining nine stars in our sample show
peculiar proper motions that differ from the mean proper motions of the ONC by
more than 3-$\sigma$. One of these stars, V 1326 Ori, could have been expelled
from the Orion Trapezium 7,000 years ago. Two could be related to the
multi-stellar disintegration in the BN/KL region, in addition to the previously
known sources BN, I and n. The others either have high uncertainties (so their
anomalous proper motions are not firmly established) or could be foreground
objects.


title: Integrality Gaps of Integer Knapsack Problems

abstract:
  We obtain optimal lower and upper bounds for the (additive) integrality gaps
of integer knapsack problems. In a randomised setting, we show that the
integrality gap of a "typical" knapsack problem is drastically smaller than the
integrality gap that occurs in a worst case scenario.


title:
Determination of the scalar polarizabilities of the proton using beam
  asymmetry $\Sigma_{3}$ in Compton scattering

abstract:
  The scalar dipole polarizabilities, $\alpha_{E1}$ and $\beta_{M1}$, are
fundamental properties related to the internal dynamics of the nucleon. The
currently accepted values of the proton polarizabilities were determined by
fitting to unpolarized proton Compton scattering cross section data. The
measurement of the beam asymmetry $\Sigma_{3}$ in a certain kinematical range
provides an alternative approach to the extraction of the scalar
polarizabilities. At the Mainz Microtron (MAMI) the beam asymmetry was measured
for Compton scattering below pion photoproduction threshold for the first time.
The results are compared with model calculations and the influence of the
experimental data on the extraction of the scalar polarizabilities is
determined.


title:
Generic behavior of a piecewise smooth vector field with non-smooth
  switching surface

abstract:
  This paper consists in discussing some issues on generic local classification
of typical singularities of $2D$ piecewise smooth vector fields when the
switching set is an algebraic variety. The main focus is to obtain
classification results concerning structural stability and generic codimension
one bifurcations.


title:
Chimera states and the interplay between initial conditions and
  non-local coupling

abstract:
  Chimera states are complex spatio-temporal patterns that consist of
coexisting domains of coherent and incoherent dynamics. We study chimera states
in a network of non-locally coupled Stuart-Landau oscillators. We investigate
the impact of initial conditions in combination with non-local coupling. Based
on an analytical argument, we show how the coupling phase and the coupling
strength are linked to the occurrence of chimera states, flipped profiles of
the mean phase velocity, and the transition from a phase- to an
amplitude-mediated chimera state.


title:
On Helson matrices: moment problems, non-negativity, boundedness, and
  finite rank

abstract:
  We study Helson matrices (also known as multiplicative Hankel matrices), i.e.
infinite matrices of the form $M(\alpha) = \{\alpha(nm)\}_{n,m=1}^\infty$,
where $\alpha$ is a sequence of complex numbers. Helson matrices are considered
as linear operators on $\ell^2(\mathbb{N})$. By interpreting Helson matrices as
Hankel matrices in countably many variables we use the theory of multivariate
moment problems to show that $M(\alpha)$ is non-negative if and only if
$\alpha$ is the moment sequence of a measure $\mu$ on $\mathbb{R}^\infty$,
assuming that $\alpha$ does not grow too fast. We then characterize the
non-negative bounded Helson matrices $M(\alpha)$ as those where the
corresponding moment measures $\mu$ are Carleson measures for the Hardy space
of countably many variables. Finally, we give a complete description of the
Helson matrices of finite rank, in parallel with the classical Kronecker
theorem on Hankel matrices.


title:
Bound state structure and electromagnetic form factor beyond the ladder
  approximation

abstract:
  We investigate the response of the bound state structure of a two-boson
system, within a Yukawa model with a scalar boson exchange, to the inclusion of
the cross-ladder contribution to the ladder kernel of the Bethe-Salpeter
equation. The equation is solved by means of the Nakanishi integral
representation and light-front projection. The valence light-front wave
function and the elastic electromagnetic form factor beyond the impulse
approximation, with the inclusion of the two-body current, generated by the
cross-ladder kernel, are computed. The valence wave function and
electromagnetic form factor, considering both ladder and ladder plus
cross-ladder kernels, are studied in detail. Their asymptotic forms are found
to be quite independent of the inclusion of the cross-ladder kernel, for a
given binding energy. The asymptotic decrease of form factor agrees with the
counting rules. This analysis can be generalized to fermionic systems, with a
wide application in the study of the meson structure.


title:
Persistent energy-time entanglement covering multiple resonances of an
  on-chip biphoton frequency comb

abstract:
  We investigate the time-frequency signatures of an on-chip biphoton frequency
comb (BFC) generated from a silicon nitride microring resonator. Using a
Franson interferometer, we examine the multifrequency nature of the photon pair
source in a time entanglement measurement scheme; having multiple frequency
modes from the BFC results in a modulation of the interference pattern. This
measurement together with a Schmidt mode decomposition shows that the generated
continuous variable energy-time entangled state spans multiple pair-wise modes.
Additionally, we demonstrate nonlocal dispersion cancellation, a foundational
concept in time-energy entanglement, suggesting the potential of the chip-scale
BFC for large-alphabet quantum key distribution.


title:
Cloud clearing in the wake of Saturn's Great Storm of 2010 - 2011 and
  suggested new constraints on Saturn's He/H2 ratio

abstract:
  Saturn's Great Storm of 2010 - 2011 produced a planet-encircling wake that
slowly transitioned from a region that was mainly dark at 5 microns in February
2011 to a region that was almost entirely bright and remarkably uniform by
December of 2012. The uniformity and high emission levels suggested that the
entire wake region had been cleared not only of the ammonia clouds that the
storm had generated and exposed, but also of any other aerosols that might
provide significant blocking of the thermal emission from Saturn's deeper and
warmer atmospheric layers. Our analysis of VIMS wake spectra from December 2012
provides no evidence of ammonia ice absorption, but shows that at least one
significant cloud layer remained behind: a non-absorbing layer of 3 - 4 optical
depths (at 2 microns) extending from 150 to ~400 mbar. A second layer of
absorbing and scattering particles, with less than 1 optical depth and located
near 1 bar, is also suggested, but its existence as a model requirement depends
on what value of the He/H2 ratio is assumed. The observations can be fit well
with just a single (upper) cloud layer for a He/H2 ratio of 0.064 in
combination with a PH3 deep volume mixing ratio of 5 ppm. At lower He/H2
ratios, the observed spectra can be modeled without particles in this region.
At higher ratios, in order to fit the brightest wake spectrum, models must
include either significant cloud opacity in this region, or significantly
increased absorption by PH3, NH3, and AsH3. As the exceptional horizontal
uniformity in the late wake is most easily understood as a complete removal of
a deep cloud layer, and after considering independent constraints on trace gas
mixing ratios, we conclude that the existence of this remarkable wake
uniformity is most consistent with a He/H2 mixing ratio of 0.055 (+0.010,
-0.015), which is on the low side of the 0.038 - 0.135 range of previous
estimates.


title:
Hanbury Brown and Twiss noise correlations in a topological
  superconductor beam splitter

abstract:
  We study Hanbury-Brown and Twiss current cross-correlations in a
three-terminal junction where a central topological superconductor (TS)
nanowire, bearing Majorana bound states at its ends, is connected to two normal
leads. Relying on a non-perturbative Green function formalism, our calculations
allow us to provide analytical expressions for the currents and their
correlations at subgap voltages, while also giving exact numerical results
valid for arbitrary external bias. We show that when the normal leads are
biased at voltages $V_1$ and $V_2$ smaller than the gap, the sign of the
current cross-correlations is given by $-\mbox{sgn}(V_1 \, V_2)$. In
particular, this leads to positive cross-correlations for opposite voltages, a
behavior in stark contrast with the one of a standard superconductor, which
provides a direct evidence of the presence of the Majorana zero-mode at the
edge of the TS. We further extend our results, varying the length of the TS
(leading to an overlap of the Majorana bound states) as well as its chemical
potential (driving it away from half-filling), generalizing the boundary TS
Green function to those cases. In the case of opposite bias voltages,
$\mbox{sgn}(V_1 \, V_2)=-1$, driving the TS wire through the topological
transition leads to a sign change of the current cross-correlations, providing
yet another signature of the physics of the Majorana bound state.


title: Tricks from Deep Learning

abstract:
  The deep learning community has devised a diverse set of methods to make
gradient optimization, using large datasets, of large and highly complex models
with deeply cascaded nonlinearities, practical. Taken as a whole, these methods
constitute a breakthrough, allowing computational structures which are quite
wide, very deep, and with an enormous number and variety of free parameters to
be effectively optimized. The result now dominates much of practical machine
learning, with applications in machine translation, computer vision, and speech
recognition. Many of these methods, viewed through the lens of algorithmic
differentiation (AD), can be seen as either addressing issues with the gradient
itself, or finding ways of achieving increased efficiency using tricks that are
AD-related, but not provided by current AD systems.
  The goal of this paper is to explain not just those methods of most relevance
to AD, but also the technical constraints and mindset which led to their
discovery. After explaining this context, we present a "laundry list" of
methods developed by the deep learning community. Two of these are discussed in
further mathematical detail: a way to dramatically reduce the size of the tape
when performing reverse-mode AD on a (theoretically) time-reversible process
like an ODE integrator; and a new mathematical insight that allows for the
implementation of a stochastic Newton's method.


title: Anomalous Transport In Magnetized Shear Flow

abstract:
  After the initial stage of fast expanding of the hot Universe comes epoch of
temperature fall and subsequent formation of dense clouds of hydrogen. Due to
process of accretion some of this clouds became compact objects. Initially
accretion is spherical, but then take the shape of the disk, and this 2D disk
collect matter more efficient than 3D sphere. Accretion disks provide the
mechanism of redistribution of angular moment and extraction of potential
energy,leads to occurrence of compact objects from gas clouds. To fall moving
along a spiral trajectory on the central gravitating body, a particle rotation
around must reduce angular moment and energy. Outward of angular moment and
movement of gas particles in the opposite direction (to the central body)
happens due to of viscose friction. We can think that the disc is composed of
multiple adjacent rings friction each other, each inner ring has a large
angular velocity to the adjacent outer ring and thus friction of the drive ring
decreased the rate of internal. The occurrence of intense dissipation in
accretion flows is among the long-standing unsolved problems in astrophysics.
Revealing how the magnetized turbulence creates shear stress tensor is of
primary importance to understand the heating mechanism and the transport of
angular momentum in accretion disks. The transport of angular momentum at
greatly enhanced rates is important for the main problem of cosmogony, that is
understanding the dynamics of creation of compact astrophysical objects.
Without a theory explaining the enhanced energy dissipation in accretion flows
of turbulent magnetized plasma we would have no clear picture of how our solar
system has been created, why the angular momentum of the Sun is only 2% of the
angular momentum of solar system, while carrying 99% of the solar system's
mass.


title:
Continuous Matrix Product States for Quantum Fields: an Energy
  Minimization Algorithm

abstract:
  The generalization of matrix product states (MPS) to continuous systems, as
proposed in the breakthrough paper [F. Verstraete, J.I. Cirac, Phys. Rev. Lett.
104, 190405(2010)], provides a powerful variational ansatz for the ground state
of strongly interacting quantum field theories in one spatial dimension. A
continuous MPS (cMPS) approximation to the ground state can be obtained by
simulating an Euclidean time evolution. In this Letter we propose a cMPS
optimization algorithm based instead on energy minimization by gradient
methods, and demonstrate its performance by applying it to the Lieb Liniger
model (an integrable model of an interacting bosonic field) directly in the
thermodynamic limit. We observe a very significant computational speed-up, of
more than two orders of magnitude, with respect to simulating an Euclidean time
evolution. As a result, much larger cMPS bond dimension D can be reached (e.g.
D = 256 with moderate computational resources) thus helping unlock the full
potential of the cMPS representation for ground state studies.


title: Randomized Experimental Design via Geographic Clustering

abstract:
  Web-based services often run randomized experiments to improve their
products. A popular way to run these experiments is to use geographical regions
as units of experimentation, since this does not require tracking of individual
users or browser cookies. Since users may issue queries from multiple
geographical locations, geo-regions cannot be considered independent and
interference may be present in the experiment. In this paper, we study this
problem, and first present GeoCUTS, a novel algorithm that forms geographical
clusters to minimize interference while preserving balance in cluster size. We
use a random sample of anonymized traffic from Google Search to form a graph
representing user movements, then construct a geographically coherent
clustering of the graph. Our main technical contribution is a statistical
framework to measure the effectiveness of clusterings. Furthermore, we perform
empirical evaluations showing that the performance of GeoCUTS is comparable to
hand-crafted geo-regions with respect to both novel and existing metrics.


title:
A description of the assembly map for the Baum-Connes conjecture with
  coefficients

abstract:
  In this note we set a configuration space description of the equivariant
connective K-homology groups with coefficients in a unital C*-algebra for
proper actions. Over this model we define a connective assembly map and prove
that in this setting is possible to recover the analytic assembly map.


title:
What do central counterparties default funds really cover? A
  network-based stress test answer

abstract:
  In the last years, increasing efforts have been put into the development of
effective stress tests to quantify the resilience of financial institutions.
Here we propose a stress test methodology for central counterparties based on a
network characterization of clearing members, whose links correspond to direct
credits and debits. This network constitutes the ground for the propagation of
financial distress: equity losses caused by an initial shock with both
exogenous and endogenous components reverberate within the network and are
amplified through credit and liquidity contagion channels. At the end of the
dynamics, we determine the vulnerability of each clearing member, which
represents its potential equity loss. We apply the proposed framework to the
Fixed Income asset class of CC&G, the central counterparty operating in Italy
whose main cleared securities are Italian Government Bonds. We consider two
different scenarios: a distributed, plausible initial shock, as well as a shock
corresponding to the cover 2 regulatory requirement (the simultaneous default
of the two most exposed clearing members). Although the two situations lead to
similar results after an unlimited reverberation of shocks on the network, the
distress propagation is much more hasty in the latter case, with a large number
of additional defaults triggered at early stages of the dynamics. Our results
thus show that setting a default fund to cover insolvencies only on a cover 2
basis may not be adequate for taming systemic events, and only very
conservative default funds, such as CC&G's one, can face total losses due to
the shock propagation. Overall, our network-based stress test represents a
refined tool for calibrating default fund amounts.


title:
Formation and Fractionation of CO (carbon monoxide) in diffuse clouds
  observed at optical and radio wavelengths

abstract:
  We modelled \HH\ and CO formation incorporating the fractionation and
selective photodissociation affecting CO when \AV\ $\la2$mag. UV absorption
measurements typically have N(\cotw)/N(\coth) $\approx 65$ that are reproduced
with the standard UV radiation and little density dependence at n(H)
$\approx32-1024\pccc$: Densities n(H) $\la256\pccc$ avoid overproducing CO.
Sightlines observed in mm-wave absorption and a few in UV show enhanced \coth\
by factors of 2-4 and are explained by higher n(H) $\ga256\pccc$ and/or weaker
radiation. The most difficult observations to understand are UV absorptions
having N(\cotw)/N(\coth) $>$100 and N(CO)$\ga10^{15}\pcc$. Plots of \WCO\ vs.
N(CO) show that \WCO\ remains linearly proportional to N(CO) even at high
opacity owing to sub-thermal excitation. \cotw\ and \coth\ have nearly the same
curve of growth so their ratios of column density/integrated intensity are
comparable even when different from the isotopic abundance ratio. For
n(H)$\ga128\pccc$, plots of \WCO\ vs N(CH) are insensitive to n(H), and
\WCO/N(CO)$\approx1\Kkms/(10^{15}~{\rm CO}\pcc)$: This compensates for small
CO/\HH\ to make \WCO\ more readily detectable. Rapid increases of N(CO) with
n(H), N(H) and N(\HH) often render the CO bright, ie a small CO-\HH\ conversion
factor. For n(H) $\la64\pccc$ CO enters the regime of truly weak excitation
where \WCO $\propto$n(H)N(CO). \WCO\ is a strong function of the average \HH\
fraction and models with \WCO=1\Kkms\ fall in the narrow range \mfH2\=0.65-0.8,
or \mfH2\=0.4-0.5 at \WCO\=0.1\Kkms. The insensitivity of easily-detected CO
emission to gas with small \mfH2\ implies that even deep CO surveys using broad
beams may not discover substantially more emission.


title:
On the dynamics of minimal homeomorphisms of $\mathbb{T}^2$ which are
  not pseudo-rotations

abstract:
  We prove that any minimal $2$-torus homeomorphism which is isotopic to the
identity and whose rotation set is not just a point exhibits uniformly bounded
rotational deviations on the perpendicular direction to the rotation set. As a
consequence of this, we show that any such homeomorphism is topologically
mixing and we prove Franks-Misiurewicz conjecture under the assumption of
minimality.


title:
Direct Characterization of Band Bending in GaP/Si(001) Heterostructures
  with Hard X-ray Photoelectron Spectroscopy

abstract:
  We apply hard X-ray photoelectron spectroscopy (HAXPES) to investigate the
electronic structures in ~50-nm thick epitaxial GaP layers grown on Si(001)
under different conditions. Depth profiles of the local binding energies for
the core levels are obtained by measuring the photoemission spectra at
different incident photon energies between 3 and 7 keV and analyzing them with
simple numerical models. The obtained depth profiles are in quantitative
agreement with the band bending determinations for the same samples in a
previous coherent phonon spectroscopic study. Our results demonstrate the
applicability of the HAXPES with varying incident photon energy to characterize
the electric potential profiles at buried semiconductor heterointerfaces.


title:
Evaluation the Impact of Library and Information Science Master's Degree
  (MLIS) on Graduates in Iran

abstract:
  The study aimed to examine the effect of MLIS degree on graduates in Iran
from different dimensions. The study examined the effects of MLIS on scientific
progress, the development of subject expertise, employment, individual
characteristics, skills and capabilities, and scientific activities of Iran's
graduates. The study was a descriptive-survey and researcher-made questionnaire
is used for data collection. The overall effect average of degree of MLIS on
Iranian graduates was equal to 3/25. The findings showed that the average
effect of MLIS degree associated with each studied factors on the graduates in
the country were: Scientific progress (3/13), development of subject expertise
(3/27), employment (3/27), individual characteristics (2/75), skills and
capabilities (3/48), scientific activities (3/57(. Discussion: Based on the
results, the effect of MLIS degree on Iranian graduates was more than moderate.
Generally, it can be concluded that MLIS courses at universities in the
country, can increase the value of a master's degree of graduates at an
acceptable level, but is not perfect; it seems that the authorities should
increase their efforts to promote the value of a master's degree in graduates.


title:
Understanding the 2016 US Presidential Election using ecological
  inference and distribution regression with census microdata

abstract:
  We combine fine-grained spatially referenced census data with the vote
outcomes from the 2016 US presidential election. Using this dataset, we perform
ecological inference using distribution regression (Flaxman et al, KDD 2015)
with a multinomial-logit regression so as to model the vote outcome Trump,
Clinton, Other / Didn't vote as a function of demographic and socioeconomic
features. Ecological inference allows us to estimate "exit poll" style results
like what was Trump's support among white women, but for entirely novel
categories. We also perform exploratory data analysis to understand which
census variables are predictive of voting for Trump, voting for Clinton, or not
voting for either. All of our methods are implemented in Python and R, and are
available online for replication.


title:
Non-thermal radiation from a pulsar wind interacting with an
  inhomogeneous stellar wind

abstract:
  Binaries hosting a massive star and a non-accreting pulsar are powerful
non-thermal emitters due to the interaction of the pulsar and the stellar wind.
The winds of massive stars are thought to be inhomogeneous, which could have an
impact on the non-thermal emission. We study numerically the impact of the
presence of inhomogeneities or clumps in the stellar wind on the high-energy
non-thermal radiation of high-mass binaries hosting a non-accreting pulsar. We
compute the trajectories and physical properties of the streamlines in the
shocked pulsar wind without clumps, with a small clump, and with a large one.
This information is used to compute the synchrotron and inverse Compton
emission from the non-thermal populations, accounting also for the effect of
gamma-ray absorption through pair creation. A specific study is done for PSR
B1259-63/LS2883. When stellar wind clumps perturb the two-wind interaction
region, the associated non-thermal radiation in the X-ray band,of synchrotron
origin, and in the GeV-TeV band, of inverse Compton origin, is affected by
several effects: (i) strong changes in the the plasma velocity direction that
result in Doppler boosting factor variations, (ii) strengthening of the
magnetic field that mainly enhances the synchrotron radiation, (iii)
strengthening of the pulsar wind kinetic energy dissipation at the shock,
potentially available for particle acceleration, and (iv) changes in the rate
of adiabatic losses that affect the lower energy part of the non-thermal
particle population. The radiation above 100 GeV detected, presumably, during
the post-periastron crossing of the Be star disc in PSR B1259-63/LS2883, can be
roughly reproduced assuming that the crossing of the disc is modeled as the
encounter with a large inhomogeneity.


title: Improved Distance Queries and Cycle Counting by Frobenius Normal Form

abstract:
  Consider an unweighted, directed graph $G$ with the diameter $D$. In this
paper, we introduce the framework for counting cycles and walks of given length
in matrix multiplication time $\widetilde{O}(n^\omega)$. The framework is based
on the fast decomposition into Frobenius normal form and the Hankel
matrix-vector multiplication. It allows us to solve the All-Nodes Shortest
Cycles, All-Pairs All Walks problems efficiently and also give some improvement
upon distance queries in unweighted graphs.


title: Weight Reduction for Quantum Codes

abstract:
  We present an algorithm that takes a CSS stabilizer code as input, and
outputs another CSS stabilizer code such that the stabilizer generators all
have weights $O(1)$ and such that $O(1)$ generators act on any given qubit. The
number of logical qubits is unchanged by the procedure, while we give bounds on
the increase in number of physical qubits and in the effect on distance and
other code parameters, such as soundness (as a locally testable code) and
"cosoundness" (defined later). Applications are discussed, including to codes
from high-dimensional manifolds which have logarithmic weight stabilizers.
Assuming a conjecture in geometry\cite{hdm}, this allows the construction of
CSS stabilizer codes with generator weight $O(1)$ and almost linear distance.
Another application of the construction is to increasing the distance to $X$ or
$Z$ errors, whichever is smaller, so that the two distances are equal.


title:
Convolution, Fourier analysis, and distributions generated by Riesz
  bases

abstract:
  In this note we discuss notions of convolutions generated by biorthogonal
systems of elements of a Hilbert space. We develop the associated biorthogonal
Fourier analysis and the theory of distributions, discuss properties of
convolutions and give a number of examples.


title:
Limits of applicability of the quasilinear approximation to the
  electrostatic wave-plasma interaction

abstract:
  The limitation of the Quasilinear Theory (QLT) to describe the diffusion of
electrons and ions in velocity space when interacting with a spectrum of large
amplitude electrostatic Langmuir, Upper and Lower hybrid waves, is analyzed. We
analytically and numerically estimate the threshold for the amplitude of the
waves above which the QLT breaks down, using a test particle code. The
evolution of the velocity distribution, the velocity-space diffusion
coefficients, the driven current, and the heating of the particles are
investigated, for the interaction with small and large amplitude electrostatic
waves, i.e. in both regimes, there where QLT is valid and there where it
clearly breaks down.


title: Perturbations of ultralight vector field dark matter

abstract:
  We study the dynamics of cosmological perturbations in models of dark matter
based on ultralight coherent vector fields. Very much as for scalar field dark
matter, we find two different regimes in the evolution: for modes with $k^2\ll
{\cal H}ma$, we have a particle-like behaviour indistinguishable from cold dark
matter, whereas for modes with $k^2\gg {\cal H}ma$, we get a wave-like
behaviour in which the sound speed is non-vanishing and of order $c_s^2\simeq
k^2/m^2a^2$. This implies that, also in these models, structure formation could
be suppressed on small scales. However, unlike the scalar case, the fact that
the background evolution contains a non-vanishing homogeneous vector field
implies that, in general, the evolution of the three kinds of perturbations
(scalar, vector and tensor) can no longer be decoupled at the linear level.
More specifically, in the particle regime, the three types of perturbations are
actually decoupled, whereas in the wave regime, the three vector field
perturbations generate one scalar-tensor and two vector-tensor perturbations in
the metric. Also in the wave regime, we find that a non-vanishing anisotropic
stress is present in the perturbed energy-momentum tensor giving rise to a
gravitational slip of order $(\Phi-\Psi)/\Phi\sim c_s^2$. Moreover in this
regime the amplitude of the tensor to scalar ratio of the scalar-tensor modes
is also $h/\Phi\sim c_s^2$. This implies that small-scale density perturbations
are necessarily associated to the presence of gravity waves in this model. We
compare their spectrum with the sensitivity of present and future gravity waves
detectors.


title: On the PBF neutrino losses in superfluid cores of neutron stars

abstract:
  Axial anomalous contributions into neutrino PBF losses due to triplet pairing
of neutrons are still ignored in modeling the evolution of neutron stars. In
this paper, the influence of the anomalous axial contributions onto the rate of
neutron stars cooling is estimated.


title:
Dual-Comb Coherent Raman Spectroscopy with Lasers of 1-GHz Pulse
  Repetition Frequency

abstract:
  We extend the technique of multiplex coherent Raman spectroscopy with two
femtosecond mode-locked lasers to oscillators of a pulse repetition frequency
of 1 GHz. We demonstrate spectra of liquids, which span 1100 cm$^{-1}$ of Raman
shifts. At a resolution of 6 cm$^{-1}$, their measurement time may be as short
as 5 microseconds for a refresh rate of 2 kHz. The waiting period between
acquisitions is improved ten-fold compared to previous experiments with two
lasers of 100-MHz repetition frequencies.


title: Flexible Length Polar Codes through Graph Based Augmentation

abstract:
  The structure of polar codes inherently requires block lengths to be powers
of two. In this paper, we investigate how different block lengths can be
realized by coupling of several short-length polar codes. For this, we first
analyze "code augmentation" to better protect the semipolarized channels,
improving the BER performance under belief propagation decoding. Several serial
and parallel augmentation schemes are discussed. A coding gain of $0.3$ dB at a
BER of $10^{-5}$ can be observed for the same total rate and length. Further,
we extend this approach towards coupling of several "sub-polar codes", leading
to a reduced computational complexity and enabling the construction of flexible
length polar codes.


title: Quantum Racah matrices and 3-strand braids in representation [3,3]

abstract:
  This paper is a next step in the project of systematic description of colored
knot polynomials started in arXiv:1506.00339. In this paper, we managed to
explicitly find the $\textit{inclusive}$ Racah matrices, i.e. the whole set of
mixing matrices in channels $R^{\otimes 3}\longrightarrow Q$ with all possible
$Q$, for $R=[3,3]$. The case $R=[3,3]$ is a multiplicity free case as well as
$R=[2,2]$ obtained in arXiv:1605.03098. The calculation is made possible by the
use of highest weight method with the help of Gelfand-Tseitlin tables. The
result allows one to evaluate and investigate $[3,3]$-colored polynomials for
arbitrary 3-strand knots, and this confirms many previous conjectures on
various factorizations, universality, and differential expansions. With the
help of a method developed in arXiv:1605.04881 we manage to calculate {\it
exclusive} Racah matrices $S$ and $\bar S$ in $R=[3,3]$. Our results confirm a
calculation of these matrices in arXiv:1606.06015, which was based on the
conjecture of explicit form of differential expansion for twist knots. Explicit
answers for Racah matrices and $[3,3]$-colored polynomials for 3-strand knots
up to 10 crossings are available at http://knotebook.org.


title: Effective field theory for magnetic compactifications

abstract:
  Magnetic flux plays an important role in compactifications of field and
string theories in two ways, it generates a multiplicity of chiral fermion zero
modes and it can break supersymmetry. We derive the complete four-dimensional
effective action for N=1 supersymmetric Abelian and non-Abelian gauge theories
in six dimensions compactified on a torus with flux. The effective action
contains the tower of charged states and it accounts for the mass spectrum of
bosonic and fermionic fields as well as their level-dependent interactions.
This allows us to compute quantum corrections to the mass and couplings of
Wilson lines. We find that the one-loop corrections vanish, contrary to the
case without flux. This can be traced back to the spontaneous breaking of a
symmetry of the six-dimensional theory by the background gauge field, with the
Wilson line as Goldstone boson.


title:
Applying Chatbots to the Internet of Things: Opportunities and
  Architectural Elements

abstract:
  Internet of Things (IoT) is emerging as a significant technology in shaping
the future by connecting physical devices or things with internet. It also
presents various opportunities for intersection of other technological trends
which can allow it to become even more intelligent and efficient. In this paper
we focus our attention on the integration of Intelligent Conversational
Software Agents or Chatbots with IoT. Literature surveys have looked into
various applications, features, underlying technologies and known challenges of
IoT. On the other hand, Chatbots are being adopted in greater numbers due to
major strides in development of platforms and frameworks. The novelty of this
paper lies in the specific integration of Chatbots in the IoT scenario. We
analyzed the shortcomings of existing IoT systems and put forward ways to
tackle them by incorporating chatbots. A general architecture is proposed for
implementing such a system, as well as platforms and frameworks, both
commercial and open source, which allow for implementation of such systems.
Identification of the newer challenges and possible future directions with this
new integration, have also been addressed.


title:
On the geometry of the singular locus of a codimension one foliation in
  $\mathbb{P}^n$

abstract:
  We will work with codimension one holomorphic foliations over the complex
projective space, represented by integrable forms $\omega\in
H^0(\Omega^1_{\PP^n}(e))$. Our main result is that, under suitable hypotheses,
the Kupka set of the singular locus of $\omega\in H^0(\Omega^1_{\PP^3}(e))$,
defined algebraically as a scheme, turns out to be arithmetically
Cohen-Macaulay. As a consequence, we prove the connectedness of the Kupka set
in $\PP^n$, and the splitting of the tangent sheaf of the foliation, provided
that it is locally free.


title: Graphene-based three-body amplification of photon heat tunneling

abstract:
  We consider a three slabs configuration including two non-doped single layer
graphene on insulating silicon dioxide (G/SiO2) substrates and one non-doped
suspended single layer graphene (SG). The suspended layer is placed between two
G/SiO2 layers. Without SG layer, the heat flux has maximum at Plasmon frequency
supported by the G/SiO2 slabs. In three slabs configuration, the photon heat
tunneling is amplified between two G/SiO2 layers significantly, only for
specific range of vacuum gap between SG layer and G/SiO2 layers and Plasmon
frequency, due to the coupling of modes between each G/SiO2 layer and SG layer.
Since, the SG layer is a single atomic layer, the photon heat tunneling
assisted by this configuration does not depend on the thickness of middle layer
and in consequence, it can enable novel applications for nanoscale thermal
management.


title: Disconnected diagrams with twisted-mass fermions

abstract:
  The latest results from the Twisted-Mass collaboration on disconnected
diagrams at the physical value of the pion mass are presented. In particular,
we focus on the sigma terms, the axial charges and the momentum fraction, all
of them for the nucleon. A detailed error analysis for each observable follows,
showing the strengths and weaknesses of the one-end trick. Alternatives are
discussed.


title:
Many-body dynamics of the decay of excitons of different charges in a
  quantum dot

abstract:
  We calculate the photoluminescence spectrum of a single semiconductor quantum
dot strongly coupled to a continuum as a function of light frequency, gate
voltage, and magnetic field. The spectrum is dominated by the recombination of
several excitonic states which can be considered as quantum quenchs in which
the many-body nature of the system is suddenly changed between initial and
final states. This is associated with an Anderson orthogonality catastrophe
with a power-law singularity at the threshold. We explain the main features
observed experimentally in the region of stability of the trion $X^-$, the
neutral exciton $X^0$ and the gate voltage induced transition between them.


title: Slopes of modular forms and the ghost conjecture

abstract:
  We formulate a conjecture on slopes of overconvergent p-adic cuspforms of any
p-adic weight in the Gamma_0(N)-regular case. This conjecture unifies a
conjecture of Buzzard on classical slopes and more recent conjectures on slopes
"at the boundary of weight space".


title:
Exploring the Thermal State of the Low-Density Intergalactic Medium at
  z=3 with an Ultra-High Signal-to-Noise QSO Spectrum

abstract:
  At low densities the standard ionisation history of the intergalactic medium
(IGM) predicts a decreasing temperature of the IGM with decreasing density once
hydrogen (and helium) reionisation is complete. Heating the high-redshift,
low-density IGM above the temperature expected from photo-heating is difficult,
and previous claims of high/rising temperatures in low density regions of the
Universe based on the probability density function (PDF) of the opacity in
Lyman-$\alpha$ forest data at $2<z<4$ have been met with considerable
scepticism, particularly since they appear to be in tension with other
constraints on the temperature-density relation (TDR). We utilize here an
ultra-high signal-to-noise spectrum of the QSO HE0940-1050 and a novel
technique to study the low opacity part of the PDF. We show that there is
indeed evidence (at 90% confidence level) that a significant volume fraction of
the under-dense regions at $z \sim 3$ has temperatures as high or higher than
those at densities comparable to the mean and above. We further demonstrate
that this conclusion is nevertheless consistent with measurements of a slope of
the TDR in over-dense regions that imply a decreasing temperature with
decreasing density, as expected if photo-heating of ionised hydrogen is the
dominant heating process. We briefly discuss implications of our findings for
the need to invoke either spatial temperature fluctuations, as expected during
helium reionization, or additional processes that heat a significant volume
fraction of the low-density IGM.


title: Georges de Rham 1903--1990

abstract:
  This is an English translation of the obituary notice by Beno Eckmann,
appearing in Elemente der Mathematik 47.3 (1992) 118--122 (in German).


title:
Regularization of p-adic String Amplitudes, and Multivariate Local Zeta
  Functions

abstract:
  We prove that the p-adic Koba-Nielsen type string amplitudes are bona fide
integrals. We attach to these amplitudes Igusa-type integrals depending on
several complex parameters and show that these integrals admit meromorphic
continuations as rational functions. Then we use these functions to regularize
the Koba-Nielsen amplitudes. As far as we know, there is no a similar result
for the Archimedean Koba-Nielsen amplitudes. We also discuss the existence of
divergencies and the connections with multivariate Igusa's local zeta
functions.


title: An abstract theory of singular operators

abstract:
  We introduce a class of operators on abstract measure spaces, which unifies
the Calder\'on-Zygmund operators on spaces of homogeneous type, the maximal
functions and the martingale transforms. We prove that such operators can be
dominated by simple sparse operators with a definite form of the domination
constant. Applying these estimates, we improve several results obtained by
different authors in recent years.