title:
Forensics Acquisition and Analysis of instant messaging and VoIP
  applications

abstract:
  The advent of the Internet has significantly transformed the daily activities
of millions of people, with one of them being the way people communicate where
Instant Messaging (IM) and Voice over IP (VoIP) communications have become
prevalent. Although IM applications are ubiquitous communication tools
nowadays, it was observed that the relevant research on the topic of evidence
collection from IM services was limited. The reason is an IM can serve as a
very useful yet very dangerous platform for the victim and the suspect to
communicate. Indeed, the increased use of Instant Messengers on smart phones
has turned to be the goldmine for mobile and computer forensic experts. Traces
and Evidence left by applications can be held on smart phones and retrieving
those potential evidences with right forensic technique is strongly required.
Recently, most research on IM forensics focus on applications such as WhatsApp,
Viber and Skype. However, in the literature, there are very few forensic
analysis and comparison related to IM applications such as WhatsApp, Viber and
Skype and Tango on both iOS and Android platforms, even though the total users
of this application already exceeded 1 billion. Therefore, in this paper we
present forensic acquisition and analysis of these four IMs and VoIPs for both
iOS and Android platforms. We try to answer on how evidence can be collected
when IM communications are used. We also define taxonomy of target artefacts in
order to guide and structure the subsequent forensic analysis. Finally, a
review of the information that can become available via the IM vendor was
conducted. The achieved results of this research provided elaborative answers
on the types of artifacts that can be identified by these IM and VoIP
applications. We compare moreover the forensics analysis of these popular
applications: WhatApp, Skype, Viber and Tango.


title:
Construction by similarity method of the fundamental solution of the
  Dirichlet problem for Keldysh type equation in the half-space

abstract:
  For elliptic in the half-space and parabolic degenerating on the boundary
equation of Keldysh type we construct by similarity method the self-similar
solution, which is the approximation to the identity in the class of integrable
functions. This solution is the fundamental solution of the Dirichlet problem,
i.e. the solution of the Dirichlet problem with the Dirac delta-function in the
boundary condition. Solution of the Dirichlet problem with an arbitrary
function in the boundary condition can be written as the convolution of the
function with the fundamental solution of the Dirichlet problem, if a
convolution exists. For a bounded and piecewise continuous boundary function
convolution exists and is written in the form of an integral, which gives the
classical solution of the Dirichlet problem, and is a generalization of the
Poisson integral for the Laplace equation. If the boundary function is a
generalized function, the convolution is a generalized solution of the
Dirichlet problem.


title: Local conditions for exponentially many subdivisions

abstract:
  Given a graph $F$, let $s_t(F)$ be the number of subdivisions of $F$, each
with a different vertex set, which one can guarantee in a graph $G$ in which
every edge lies in at least $t$ copies of $F$. In 1990, Tuza asked for which
graphs $F$ and large $t$, one has that $s_t(F)$ is exponential in a power of
$t$. We show that, somewhat surprisingly, the only such $F$ are complete
graphs, and for every $F$ which is not complete, $s_t(F)$ is polynomial in $t$.
Further, for a natural strengthening of the local condition above, we also
characterise those $F$ for which $s_t(F)$ is exponential in a power of $t$.


title: A distributed voltage stability margin for power distribution networks

abstract:
  We consider the problem of characterizing and assessing the voltage stability
in power distribution networks. Different from previous formulations, we
consider the branch-flow parametrization of the power system state, which is
particularly effective for radial networks. Our approach to the voltage
stability problem is based on a local, approximate, yet highly accurate
characterization of the determinant of the power flow Jacobian. Our determinant
approximation allows us to construct a voltage stability index that can be
computed in a fully scalable and distributed fashion. We provide an upper bound
on the approximation error, and we show how the proposed index outperforms
other voltage indices that have been recently proposed in the literature.


title: $F$-divided sheaves trivialized by dominant maps are essentially finite

abstract:
  By a result of Biswas and Dos Santos, on a smooth and projective variety over
an algebraically closed field, a vector bundle trivialized by a proper and
surjective map is essentially finite, that is it corresponds to a
representation of the Nori fundamental group scheme. In this paper we obtain
similar results for non-proper non-smooth algebraic stacks over arbitrary
fields of characteristic $p>0$. As by-product we have the following partial
generalization of the Biswas-Dos Santos' result in positive characteristic: on
a pseudo-proper and inflexible stack of finite type over $k$ a vector bundle
which is trivialized by a proper and flat map is essentially finite.


title:
Self-similar sets, simple augmented trees, and their Lipschitz
  equivalence

abstract:
  Given an iterated function system (IFS) of contractive similitudes, the
theory of Gromov hyperbolic graph on the IFS has been established recently. In
the paper, we introduce a notion of simple augmented tree which is a Gromov
hyperbolic graph. By generalizing a combinatorial device of rearrangeable
matrix, we show that there exists a near-isometry between the simple augmented
tree and the symbolic space of the IFS, so that their hyperbolic boundaries are
Lipschitz equivalent. We then apply this to consider the Lipschitz equivalence
of self-similar sets with or without assuming the open set condition. Moreover,
we also provide a criterion for a self-similar set to be a Cantor-type set
which completely answers an open question raised in \cite{LaLu13}. Our study
extends the previous works.


title: Energy--momentum tensor on the lattice: recent developments

abstract:
  It is conceivable that the construction of the energy--momentum tensor (EMT)
in lattice field theory enlarges our ability in lattice field theory and also
deepens our understanding on EMT at the non-pertubative level. In this talk, I
will review recent developments in this enterprise.


title:
Mismatched Multi-Letter Successive Decoding for the Multiple-Access
  Channel

abstract:
  This paper studies channel coding for the discrete memoryless multiple-access
channel with a given (possibly suboptimal) decoding rule. A multi-letter
successive decoding rule depending on an arbitrary non-negative decoding metric
is considered, and achievable rate regions and error exponents are derived both
for the standard MAC (independent codebooks), and for the cognitive MAC (one
user knows both messages) with superposition coding. In the cognitive case, the
rate region and error exponent are shown to be tight with respect to the
ensemble average. The rate regions are compared with those of the
commonly-considered decoder that chooses the message pair maximizing the
decoding metric, and numerical examples are given for which successive decoding
yields a strictly higher sum rate for a given pair of input distributions.


title: Training Bit Fully Convolutional Network for Fast Semantic Segmentation

abstract:
  Fully convolutional neural networks give accurate, per-pixel prediction for
input images and have applications like semantic segmentation. However, a
typical FCN usually requires lots of floating point computation and large
run-time memory, which effectively limits its usability. We propose a method to
train Bit Fully Convolution Network (BFCN), a fully convolutional neural
network that has low bit-width weights and activations. Because most of its
computation-intensive convolutions are accomplished between low bit-width
numbers, a BFCN can be accelerated by an efficient bit-convolution
implementation. On CPU, the dot product operation between two bit vectors can
be reduced to bitwise operations and popcounts, which can offer much higher
throughput than 32-bit multiplications and additions.
  To validate the effectiveness of BFCN, we conduct experiments on the PASCAL
VOC 2012 semantic segmentation task and Cityscapes. Our BFCN with 1-bit weights
and 2-bit activations, which runs 7.8x faster on CPU or requires less than 1\%
resources on FPGA, can achieve comparable performance as the 32-bit
counterpart.


title: Flows in nonequilibrium quantum systems and quantum photosynthesis

abstract:
  A three level quantum system interacting with nonequilibrium environment is
investigated. The stationary state of the system is found (both for
non-coherent and coherent environment) and relaxation and decoherence to the
stationary state is described. The stationary state of the system will be
non-equilibrium and will generate flows. We describe the dependence of the
flows on the state of the environment.
  We also discuss application of this model to the problem of quantum
photosynthesis, in particular, to description of flows of excitons and
generation of excitonic coherences.


title: A remark on local fractional calculus and ordinary derivatives

abstract:
  In this short note we present a new general definition of local fractional
derivative, that depends on an unknown kernel. For some appropriate choices of
the kernel we obtain some known cases. We establish a relation between this new
concept and ordinary differentiation. Using such formula, most of the
fundamental properties of the fractional derivative can be derived directly.


title:
Learning to Generate Images of Outdoor Scenes from Attributes and
  Semantic Layouts

abstract:
  Automatic image synthesis research has been rapidly growing with deep
networks getting more and more expressive. In the last couple of years, we have
observed images of digits, indoor scenes, birds, chairs, etc. being
automatically generated. The expressive power of image generators have also
been enhanced by introducing several forms of conditioning variables such as
object names, sentences, bounding box and key-point locations. In this work, we
propose a novel deep conditional generative adversarial network architecture
that takes its strength from the semantic layout and scene attributes
integrated as conditioning variables. We show that our architecture is able to
generate realistic outdoor scene images under different conditions, e.g.
day-night, sunny-foggy, with clear object boundaries.


title: On magnetization of quark-gluon plasma at the LHC experiment energies

abstract:
  Large scale chromomagnetic, B_3, B_8, and usual magnetic,H, fields have to be
generated in QCD after the deconfinement phase transition (DPT) at temperatures
T larger than deconfinement temperature T_d. The two former fields are created
spontaneously due to asymptotic freedom of gluon intaractions. Whereas H is
produced due to either the feature of quarks to possess both electric and color
charges or a vacuum polarization in this case. At the polarization, the vacuum
quark loops mix the external fields. As a result, B_3, B_8 become the sources
generating H. The latter field appears at $T$ much lower than the electroweak
phase transition temperature T_ew. This mechanism should exhibit itself at the
LHC experiments on heavy ion collisions. It operates at the one-loop diagram
level for an effective potential. The created fields are temperature dependent
and occupying the macroscopic volume of quark-gluon plasma. The magnetization
influences different processes and may serve as a signal for the DPT.


title: Orbital periods and component masses of three double white dwarfs

abstract:
  The merger of close double white dwarfs (CDWDs) is one of the favourite
evolutionary channels for producing Type Ia supernovae (SN Ia). Unfortunately,
current theories of the evolution and formation of CDWDs are still poorly
constrained and have several serious uncertainties, which affect the predicted
SN Ia rates. Moreover, current observational constraints on this evolutionary
pathway for SN Ia mainly rely on only 18 double-lined and/or eclipsing CDWDs
with measured orbital and stellar parameters for both white dwarfs. In this
paper we present the orbital periods and the individual masses of three new
double-lined CDWDs, derived using a new method. This method employs mass
ratios, the Halpha core ratios and spectral model-fitting to constrain the
masses of the components of the pair. The three CDWDs are WD0028-474
(Porb=9.350 +- 0.007 hours, M1=0.60 +- 0.06 Msun, M2=0.45 +- 0.04 Msun),
HE0410-1137 (Porb = 12.208 +- 0.008 hours, M1= 0.51 +- 0.04 Msun, M2= 0.39 +-
0.03 Msun) and SDSSJ031813.25-010711.7 (Porb = 45.908 +- 0.006 hours, among the
longest period systems, M1= 0.40 +- 0.05 Msun, M2= 0.49 +- 0.05 Msun). While
the three systems studied here will merge in timescales longer than the Hubble
time and are expected to become single massive (>~0.9 Msun) white dwarfs rather
than exploding as SN Ia, increasing the small sample of CDWDs with determined
stellar parameters is crucial for a better overall understanding of their
evolution.


title: Highly dynamically evolved intermediate-age open clusters

abstract:
  We present a comprehensive UBVRI and Washington CT1T2 photometric analysis of
seven catalogued open clusters, namely: Ruprecht 3, 9, 37, 74, 150, ESO 324-15
and 436-2. The multi-band photometric data sets in combination with 2MASS
photometry and Gaia astrometry for the brighter stars were used to estimate
their structural parameters and fundamental astrophysical properties. We found
that Ruprecht 3 and ESO 436-2 do not show self-consistent evidence of being
physical systems. The remained studied objects are open clusters of
intermediate-age (9.0 < log(t yr-1) < 9.6), of relatively small size (r_cls ~
0.4 - 1.3 pc) and placed between 0.6 and 2.9 kpc from the Sun. We analized the
relationships between core, half-mass, tidal and Jacoby radii as well as
half-mass relaxation times to conclude that the studied clusters are in an
evolved dynamical stage. The cluster masses obtained by summing those of the
observed cluster stars resulted to be ~ 10-15 per cent of the masses of open
clusters of similar age located closer than 2 kpc from the Sun. We found that
cluster stars occupy volumes as large as those for tidally filled clusters.


title:
Mono-X Versus Direct Searches: Simplified Models for Dark Matter at the
  LHC

abstract:
  We consider simplified models for dark matter (DM) at the LHC, focused on
mono-Higgs, -Z, or -b produced in the final state. Our primary purpose is to
study the LHC reach of a relatively complete set of simplified models for these
final states, while comparing the reach of the mono-X DM search against direct
searches for the mediating particle. We find that direct searches for the
mediating particle, whether in di-jets, jets+MET, multi-b+MET, or di-boson+MET,
are usually stronger. We draw attention to the cases that the mono-X search is
strongest, which include regions of parameter space in inelastic DM, two Higgs
doublet, and squark mediated production models with a compressed spectrum.


title: Fully Convolutional Crowd Counting On Highly Congested Scenes

abstract:
  In this paper we advance the state-of-the-art for crowd counting in high
density scenes by further exploring the idea of a fully convolutional crowd
counting model introduced by (Zhang et al., 2016). Producing an accurate and
robust crowd count estimator using computer vision techniques has attracted
significant research interest in recent years. Applications for crowd counting
systems exist in many diverse areas including city planning, retail, and of
course general public safety. Developing a highly generalised counting model
that can be deployed in any surveillance scenario with any camera perspective
is the key objective for research in this area. Techniques developed in the
past have generally performed poorly in highly congested scenes with several
thousands of people in frame (Rodriguez et al., 2011). Our approach, influenced
by the work of (Zhang et al., 2016), consists of the following contributions:
(1) A training set augmentation scheme that minimises redundancy among training
samples to improve model generalisation and overall counting performance; (2) a
deep, single column, fully convolutional network (FCN) architecture; (3) a
multi-scale averaging step during inference. The developed technique can
analyse images of any resolution or aspect ratio and achieves state-of-the-art
counting performance on the Shanghaitech Part B and UCF CC 50 datasets as well
as competitive performance on Shanghaitech Part A.


title: The Coconut Model with Heterogeneous Strategies and Learning

abstract:
  In this paper, we develop an agent-based version of the Diamond search
equilibrium model - also called Coconut Model. In this model, agents are faced
with production decisions that have to be evaluated based on their expectations
about the future utility of the produced entity which in turn depends on the
global production level via a trading mechanism. While the original dynamical
systems formulation assumes an infinite number of homogeneously adapting agents
obeying strong rationality conditions, the agent-based setting allows to
discuss the effects of heterogeneous and adaptive expectations and enables the
analysis of non-equilibrium trajectories. Starting from a baseline
implementation that matches the asymptotic behavior of the original model, we
show how agent heterogeneity can be accounted for in the aggregate dynamical
equations. We then show that when agents adapt their strategies by a simple
temporal difference learning scheme, the system converges to one of the fixed
points of the original system. Systematic simulations reveal that this is the
only stable equilibrium solution.


title: Interaction Networks for Learning about Objects, Relations and Physics

abstract:
  Reasoning about objects, relations, and physics is central to human
intelligence, and a key goal of artificial intelligence. Here we introduce the
interaction network, a model which can reason about how objects in complex
systems interact, supporting dynamical predictions, as well as inferences about
the abstract properties of the system. Our model takes graphs as input,
performs object- and relation-centric reasoning in a way that is analogous to a
simulation, and is implemented using deep neural networks. We evaluate its
ability to reason about several challenging physical domains: n-body problems,
rigid-body collision, and non-rigid dynamics. Our results show it can be
trained to accurately simulate the physical trajectories of dozens of objects
over thousands of time steps, estimate abstract quantities such as energy, and
generalize automatically to systems with different numbers and configurations
of objects and relations. Our interaction network implementation is the first
general-purpose, learnable physics engine, and a powerful general framework for
reasoning about object and relations in a wide variety of complex real-world
domains.


title:
Dimethylsilanone generation from pyrolysis of polysiloxanes filled with
  nanosized silica and ceria/silica

abstract:
  Polydimethylsiloxane (PDMS) is a widely used organosilicon polymer often
employed in formulations with fine oxide particles for various high temperature
applications. Although PDMS is considered to be thermally stable and chemically
inert, it is not always clear how the oxide filler influences its
thermoresistance, decomposition chemistry and what reactive products are formed
in the underlying thermal reactions. In this work we use temperature programmed
desorption mass spectrometry (TPD MS) to study the pyrolysis of PDMS and its
composites with nanosized silica and ceria/silica. Our results suggest that the
elusive organosilicon compound - dimethylsilanone is generated from PDMS over a
broad temperature range (in some cases starting at 70${\deg}$C). The presence
of nano-oxides catalyzed this process. Ions characteristic of the fragmentation
of dimethylsilanone under electron ionization were assigned with the aid of DFT
structure calculations. Possible reaction mechanisms for generating
dimethylsilanone were discussed in the context of the calculated kinetic
parameters. Observed accompanying products of PDMS pyrolysis, such as
tetramethylcyclodisiloxane and hexamethylcyclotrisiloxane, indicate that
multiple channels are involved in the dimethylsilanone release.


title: Torsional and rotational coupling in non-rigid molecules

abstract:
  We analyze theoretically the interplay between the torsional and the
rotational motion of an aligned biphenyl-like molecule. To do so, we consider a
transition between two electronic states with different internal torsional
potentials, induced by means of a resonant laser pulse. The change in the
internal torsional potential provokes the motion of the torsional wavepacket in
the excited electronic state, modifying the structure of the molecule, and
hence, its inertia tensor. We find that this process has a strong impact on the
rotational wave function, displaying different behavior depending on the
electronic states involved and their associated torsional potentials. We
describe the dynamics of the system by considering the degree of alignment and
the expectations values of the angular momentum operators for the overall
rotation of the molecule.


title:
Non-thermal emission and dynamical state of massive galaxy clusters from
  CLASH sample

abstract:
  Massive galaxy clusters are the most violent large scale structures
undergoing merger events in the Universe. Based upon their morphological
properties in X-rays, they are classified as un-relaxed and relaxed clusters
and often host (a fraction of them) different types of non-thermal radio
emitting components, viz., haloes, mini-haloes, relics and phoenix within their
Intra Cluster Medium (ICM). The radio haloes show steep (alpha = -1.2) and
ultra steep (alpha < -1.5) spectral properties at low radio frequencies, giving
important insights on the merger (pre or post) state of the cluster. Ultra
steep spectrum radio halo emissions are rare and expected to be the dominating
population to be discovered via LOFAR and SKA in the future. Further, the
distribution of matter (morphological information), alignment of hot X-ray
emitting gas from the ICM with the total mass (dark + baryonic matter) and the
bright cluster galaxy (BCG) is generally used to study the dynamical state of
the cluster. We present here a multi wavelength study on 14 massive clusters
from the CLASH survey and show the correlation between the state of their
merger in X-ray and spectral properties (1.4 GHz - 150 MHz) at radio
wavelengths. Using the optical data we also discuss about the gas-mass
alignment, in order to understand the interplay between dark and baryonic
matter in massive galaxy clusters.


title:
Robust Coordinated Transmission and Generation Expansion Planning
  Considering Ramping Requirements and Construction Periods

abstract:
  Two critical issues have arisen in transmission expansion planning with the
rapid growth of wind power generation. First, severe power ramping events in
daily operation due to the high variability of wind power generation pose great
challenges to multi-year planning decision making. Second, the long
construction periods of transmission lines may not be able to keep pace with
the fast growing uncertainty due to the increasing integration of renewable
energy generation. To address such issues, we propose a comprehensive robust
planning model considering different resources, namely, transmission lines,
generators, and FACTS devices. Various factors are taken into account,
including flexibility requirement, construction period, and cost. We construct
the hourly net load ramping uncertainty (HLRU) set to characterize the
variation of hourly net load including wind power generation, and the annual
net load duration curve uncertainty (LDCU) set for the uncertainty of normal
annual net load duration curve. This results in a two-stage robust optimization
model with two different types of uncertainty sets, which are decoupled into
two different sets of subproblems to make the entire solution process
tractable. Numerical simulations with real-world data show that the proposed
model and solution method are effective to coordinate different flexible
resources, rendering robust expansion planning strategies.


title:
On Coreferring Text-extracted Event Descriptions with the aid of
  Ontological Reasoning

abstract:
  Systems for automatic extraction of semantic information about events from
large textual resources are now available: these tools are capable to generate
RDF datasets about text extracted events and this knowledge can be used to
reason over the recognized events. On the other hand, text based tasks for
event recognition, as for example event coreference (i.e. recognizing whether
two textual descriptions refer to the same event), do not take into account
ontological information of the extracted events in their process. In this
paper, we propose a method to derive event coreference on text extracted event
data using semantic based rule reasoning. We demonstrate our method considering
a limited (yet representative) set of event types: we introduce a formal
analysis on their ontological properties and, on the base of this, we define a
set of coreference criteria. We then implement these criteria as RDF-based
reasoning rules to be applied on text extracted event data. We evaluate the
effectiveness of our approach over a standard coreference benchmark dataset.


title:
ACCESS I: An Optical Transmission Spectrum of GJ 1214b Reveals a
  Heterogeneous Stellar Photosphere

abstract:
  GJ 1214b is the most studied sub-Neptune exoplanet to date. Recent
measurements have shown its near-infrared transmission spectrum to be flat,
pointing to a high-altitude opacity source in the exoplanet's atmosphere,
either equilibrium condensate clouds or photochemical hazes. Many photometric
observations have been reported in the optical by different groups, though
simultaneous measurements spanning the entire optical regime are lacking. We
present an optical transmission spectrum ($4,500-9,260$\AA) of GJ 1214b in 14
bins measured with Magellan/IMACS repeatedly over three transits. We measure a
mean planet-to-star radius ratio of ${R_{p}/R_{s} = 0.1146\pm{2\times10^{-4}}}$
and mean uncertainty of $\sigma(R_{p}/R_{s})=8.7\times10^{-4}$ in the spectral
bins. The optical transit depths are shallower on average than observed in the
near-infrared. We present a model for jointly incorporating the effects of a
composite photosphere and atmospheric transmission (CPAT) through the
exoplanet's limb, and use it to examine the cases of absorber and temperature
heterogeneities in the stellar photosphere. We find the optical and
near-infrared measurements are best explained by the combination of (1)
photochemical haze in the exoplanetary atmosphere with a mode particle size
$r=0.1~\mu$m and haze-forming efficiency $f_{haze}=10 \%$ and (2) faculae in
the unocculted stellar disk with a temperature contrast $\Delta
T=354^{+46}_{-46}$ K, assuming 3.2% surface coverage. The CPAT model can be
used to assess potential contributions of heterogeneous stellar photospheres to
observations of exoplanet transmission spectra, which will be important for
searches for spectral features in the optical.


title:
Plasma Dipole Oscillation Excited by Trapped Electrons Leading to Bursts
  of Coherent Radiation

abstract:
  Plasma dipole oscillation (PDO) depicted as harmonic motion of a spatially
localized block of electrons has, until now, been hypothetical. In practice,
the plasma oscillation occurs always as a part of a plasma wave. Studies on
radiation burst from plasmas have focused only on coupling of the plasma wave
and electromagnetic wave. Here we show that a very-high-field PDO can be
generated by the electrons trapped in a moving train of potential wells. The
electrons riding on the potential train coherently construct a local dipole
moment by charge separation. The subsequent PDO is found to persist stably
until its energy is emitted entirely via coherent radiation. In our novel
method, the moving potentials are provided by two slightly-detuned laser pulses
colliding in a non-magnetized plasma. The radiated energy reaches several
millijoules in the terahertz spectral region. The proposed method provides a
way of realizing the PDO as a new radiation source in the laboratory. PDO as a
mechanism of astrophysical radio-bursts is discussed.


title:
CC2 oscillator strengths within the local framework for calculating
  excitation energies (LoFEx)

abstract:
  In a recent work [Baudin and Kristensen, J. Chem. Phys. 144, 224106 (2016)],
we introduced a local framework for calculating excitation energies (LoFEx),
based on second-order approximated coupled cluster (CC2) linear-response
theory. LoFEx is a black-box method in which a reduced excitation orbital space
(XOS) is optimized to provide coupled cluster (CC) excitation energies at a
reduced computational cost. In this article, we present an extension of the
LoFEx algorithm to the calculation of CC2 oscillator strengths. Two different
strategies are suggested, in which the size of the XOS is determined based on
the excitation energy or the oscillator strength of the targeted transitions.
The two strategies are applied to a set of medium-sized organic molecules in
order to assess both the accuracy and the computational cost of the methods.
The results show that CC2 excitation energies and oscillator strengths can be
calculated at a reduced computational cost, provided that the targeted
transitions are local compared to the size of the molecule. To illustrate the
potential of LoFEx for large molecules, both strategies have been successfully
applied to the lowest transition of the bivalirudin molecule (4255 basis
functions) and compared with time-dependent density functional theory.


title:
On the spectral curvature of VHE blazar 1ES\,1011+496: Effect of spatial
  particle diffusion

abstract:
  A detailed multi-epoch study of the broadband spectral behaviour of the very
high energy (VHE) source, 1ES\,1011+496, provides us with valuable information
regarding the underlying particle distribution. Simultaneous observations of
the source at optical/ UV/ X-ray/ $\gamma$-ray during three different epochs,
as obtained from Swift-UVOT/ Swift-XRT/ Fermi-LAT, are supplemented with the
information available from the VHE telescope array, HAGAR. The longterm flux
variability at the Fermi-LAT energies is clearly found to be lognormal. It is
seen that the broadband spectral energy distribution (SED) of 1ES\,1011+496 can
be successfully reproduced by synchrotron and synchrotron self Compton emission
models. Notably, the observed curvature in the photon spectrum at X-ray
energies demands a smooth transition of the underlying particle distribution
from a simple power law to a power law with an exponential cutoff or a smooth
broken power law distribution, which may possibly arise when the escape of the
particles from the main emission region is energy dependent. Specifically, if
the particle escape rate is related to its energy as $E^{0.5}$ then the
observed photon spectrum is consistent with the ones observed during the
various epochs.


title:
Performances of Neutron Scattering Spectrometers on a Compact Neutron
  Source

abstract:
  There is currently a big effort put into the operation and construction of
world class neutron scattering facilities (SNS and SNS-TS2 in the US, J-PARC in
Japan, ESS in Europe, CSS in China, PIK in Russia). On the other hand, there
exists a network of smaller neutron scattering facilities which play a key role
in creating a large neutron scattering community who is able to efficiently use
the existing facilities. With the foreseen closure of the ageing nuclear
research reactors, especially in Europe there is a risk of seeing a shrinking
of the community who would then be able to use efficiently the world class
facilities. There is thus a reflection being conducted in several countries for
the replacement of smaller research reactors with low energy accelerator based
sources. We consider here a reference design for a compact neutron source based
on existing accelerator components. We estimate the performances of various
types of neutron scattering instruments built around such a source. The results
suggest that nowadays state of the art neutron scattering experiments could be
successfully performed on such a compact source and that it is thus a viable
replacement solution for neutron research reactors.


title: Devil's staircases in synthetic dimensions and gauge fields

abstract:
  We study interacting bosonic or fermionic atoms in a high synthetic magnetic
field in two dimensions spanned by continuous real space and a synthetic
dimension. Here, the synthetic dimension is provided by hyperfine spin states,
and the synthetic field is created by laser-induced transitions between them.
While the interaction is short-range in real space, it is long-range in the
synthetic dimension in sharp contrast with fractional quantum Hall systems.
Introducing an analog of the lowest-Landau-level approximation valid for large
transition amplitudes, we derive an effective one-dimensional lattice model, in
which density-density interactions turn out to play a dominant role. We show
that in the limit of a large number of internal states, the system exhibits a
cascade of crystal ground states, which is known as devil's staircase, in a way
analogous to the thin-torus limit of quantum Hall systems.


title: Video Captioning with Multi-Faceted Attention

abstract:
  Recently, video captioning has been attracting an increasing amount of
interest, due to its potential for improving accessibility and information
retrieval. While existing methods rely on different kinds of visual features
and model structures, they do not fully exploit relevant semantic information.
We present an extensible approach to jointly leverage several sorts of visual
features and semantic attributes. Our novel architecture builds on LSTMs for
sentence generation, with several attention layers and two multimodal layers.
The attention mechanism learns to automatically select the most salient visual
features or semantic attributes, and the multimodal layer yields overall
representations for the input and outputs of the sentence generation component.
Experimental results on the challenging MSVD and MSR-VTT datasets show that our
framework outperforms the state-of-the-art approaches, while ground truth based
semantic attributes are able to further elevate the output quality to a
near-human level.


title: On integral estimates of non-negative positive definite functions

abstract:
  Let $\ell>0$ be arbitrary. We introduce the extremal quantities $$
G(\ell):=\frac{\sup_{f} \int_{-\ell}^{\ell} f\,dx}{\int_{-1}^1 f\,dx},\quad
C(\ell):=\frac{\sup_{f} \sup_{a\in {\mathbb R}} \int_{a-\ell}^{a+\ell}
f\,dx}{\int_{-1}^1 f\,dx}, $$ where the supremum is taken over all not
identically zero non-negative positive definite functions. We are interested in
the question: how large can the above extremal quantities be?
  This problem was originally posed by Yu. Shteinikov and S. Konyagin for the
case $\ell=2$. In this note we obtain exact values for the right limits
$G(k+0)$ and $C(k+0)$ at natural numbers $k$, and sufficiently close bounds for
other values of $\ell$. We point out that the problem provides an extension of
the classical problem of Wiener.


title:
Quantum Key Distribution with High Order Fibonacci-like Orbital Angular
  Momentum States

abstract:
  The coding space in quantum communication could be expanded to
high-dimensional space by using orbital angular momentum (OAM) states of
photons, as both the capacity of the channel and security are enhanced. Here we
present a novel approach to realize high-capacity quantum key distribution
(QKD) by exploiting OAM states. The innovation of the proposed approach relies
on a unique type of entangledphoton source which produces entangled photons
with OAM randomly distributed among high order Fiboncci-like numbers and a new
physical mechanism for efficiently sharing keys. This combination of
entanglement with mathematical properties of high order Fibonacci sequences
provides the QKD protocol which is immune to photon-number-splitting attacks
and allows secure generation of long keys from few photons. Unlike other
protocols, reference frame alignment and active modulation of production and
detection bases are unnecessary.


title:
Neutrons production on the IPHI accelerator for the validation of the
  design of the compact neutron source SONATE

abstract:
  We aim at building an accelerator based compact neutron source which would
provide a thermal neutron flux on the order of 4E12 n.s-1.cm-2.sr-1. Such
brilliance would put compact neutron sources on par with existing medium flux
neutron research reactors. We performed the first neutron production tests on
the IPHI proton accelerator at Saclay. The neutron fluxes were measured using
gold foil activation and 3He detectors. The measured fluxes were compared with
MCNP and GEANT4 Monte Carlo simulations in which the whole experimental setup
was modelled. There is a good agreement between the experimental measurements
and the Monte-Carlo simulations. The available modelling tools will allow us to
optimize the whole Target Moderator Reflector assembly together with the
neutron scattering spectrometer geometries.


title: Persistent random walks. II. Functional Scaling Limits

abstract:
  We give a complete and unified description -- under some stability
assumptions -- of the functional scaling limits associated with some persistent
random walks for which the recurrent or transient type is studied in [1]. As a
result, we highlight a phase transition phenomenon with respect to the memory.
It turns out that the limit process is either Markovian or not according to --
to put it in a nutshell -- the rate of decrease of the distribution tails
corresponding to the persistent times. In the memoryless situation, the limits
are classical strictly stable L{\'e}vy processes of infinite variations.
However, we point out that the description of the critical Cauchy case fills
some lacuna even in the closely related context of Directionally Reinforced
Random Walks (DRRWs) for which it has not been considered yet. Besides, we need
to introduced some relevant generalized drift -- extended the classical one --
in order to study the critical case but also the situation when the limit is no
longer Markovian. It appears to be in full generality a drift in mean for the
Persistent Random Walk (PRW). The limit processes keeping some memory -- given
by some variable length Markov chain -- of the underlying PRW are called
arcsine Lamperti anomalous diffusions due to their marginal distribution which
are computed explicitly here. To this end, we make the connection with the
governing equations for L{\'e}vy walks, the occupation times of skew Bessel
processes and a more general class modelled on Lamperti processes. We also
stress that we clarify some misunderstanding regarding this marginal
distribution in the framework of DRRWs. Finally, we stress that the latter
situation is more flexible -- as in the first paper -- in the sense that the
results can be easily generalized to a wider class of PRWs without renewal
pattern.


title:
The stationary sine-Gordon equation on metric graphs: Exact analytical
  solutions for simple topologies

abstract:
  We consider the stationary sine-Gordon equation on metric graphs with simple
topologies. The vertex boundary conditions are provided by flux conservation
and matching of derivatives at the star graph vertex. Exact analytical
solutions are obtained. It is shown that the method can be extended for tree
and other simple graph topologies. Applications of the obtained results to
branched planar Josephson junctions and Josephson junctions with tricrystal
boundaries are discussed.

categories: nlin.SI cond-mat.supr-con math-ph math.MP


title: An Evaluation of Models for Runtime Approximation in Link Discovery

abstract:
  Time-efficient link discovery is of central importance to implement the
vision of the Semantic Web. Some of the most rapid Link Discovery approaches
rely internally on planning to execute link specifications. In newer works,
linear models have been used to estimate the runtime the fastest planners.
However, no other category of models has been studied for this purpose so far.
In this paper, we study non-linear runtime estimation functions for runtime
estimation. In particular, we study exponential and mixed models for the
estimation of the runtimes of planners. To this end, we evaluate three
different models for runtime on six datasets using 400 link specifications. We
show that exponential and mixed models achieve better fits when trained but are
only to be preferred in some cases. Our evaluation also shows that the use of
better runtime approximation models has a positive impact on the overall
execution of link specifications.


title: A biology journal that can teach physicists a lesson in peer review

abstract:
  This is a Commentary in $Physics~Today$ on the novel review process developed
by the biology journal $eLife$, with the suggestion that it be adopted by
physics journals.


title:
Generalised triangle groups of type (2,3,2) with no cyclic essential
  representations

abstract:
  A conjecture of Roseberger asserts that every generalised triangle group
either is virtually soluble or contains a non-abelian free subgroup. Modulo two
exceptional cases, we verify this conjecture for generalised triangle groups of
type (2,3,2) which do not admit essential representations onto the cyclic group
of order 6.


title:
Sharp Gagliardo-Nirenberg inequalities in fractional Coulomb-Sobolev
  spaces

abstract:
  We prove scaling invariant Gagliardo-Nirenberg type inequalities of the form
$$\|\varphi\|_{L^p(\mathbb{R}^d)}\le C\|\varphi\|_{\dot
H^{s}(\mathbb{R}^d)}^{\beta} \left(\iint_{\mathbb{R}^d \times \mathbb{R}^d}
\frac{|\varphi (x)|^q\,|\varphi (y)|^q}{|x - y|^{d-\alpha}} dx
dy\right)^{\gamma},$$ involving fractional Sobolev norms with $s>0$ and Coulomb
type energies with $0<\alpha<d$ and $q\ge 1$. We establish optimal ranges of
parameters for the validity of such inequalities and discuss the existence of
the optimisers. In the special case $p=\frac{2d}{d-2s}$ our results include a
new refinement of the fractional Sobolev inequality by a Coulomb term. We also
prove that if the radial symmetry is taken into account, then the ranges of
validity of the inequalities could be extended and such a radial improvement is
possible if and only if $\alpha>1$.


title:
The Precise and Powerful Chaos of the 5:2 Mean Motion Resonance with
  Jupiter

abstract:
  This work reexamines the dynamics of the 5:2 mean motion resonance with
Jupiter located in the Outer Belt at $a\sim 2.82$ AU. First, we compute
dynamical maps revealing the precise structure of chaos inside the resonance.
Being interested to verify the chaotic structures as sources of natural
transportation routes, we additionally integrate 1000 massless particles
initially placed along them and follow their orbital histories up to 5 Myr. As
many as 99.5\% of our test particles became Near-Earth Objects, 23.4\% migrated
to semi-major axis below 1 AU and more than 57\% entered the Hill sphere of
Earth. We have also observed a borderline defined by the $q \simeq 2.6$ AU
perihelion distance along which particles escape from the Solar System.


title:
Dust in clusters: separating the contribution of galaxies and
  intracluster media

abstract:
  We have analized a sample of 327 clusters of galaxies spanning the range
0.06-0.70 in redshift. Strong constraints on their mean intracluster emission
by dust have been obtained using maps and catalogs from the HERSCHEL HerMES
project; within a radius of 5 arcmin centered in each cluster, the 95% C.L.
limits obtained are 86.6, 48.2 and 30.9 mJy at the observed frequencies of 250,
350 and 500 $\mu$m. From these restrictions, and assuming physical parameters
typical of interstellar media in the Milky Way, we have obtained tight upper
limits on the visual extinction of background galaxies due to the intracluster
media: $A_V$(95% C.L.) <~$10^{-3}$ mags. Strong constraints are also obtained
for the mass of such dust; for instance using the data at 350 $\mu$m we
establish a 95% upper limit of $<10^9M_\odot$ within a circle with a radius of
5 arcmin centered in the clusters. This corresponds to a fraction of the total
mass of the clusters of $9.5\times 10^{-6}$, and indicates a deficiency in the
gas-to-dust ratio in the intracluster media by about three orders of magnitude
as regards the value found in the Milky Way. Computing the total infrared
luminosity of the clusters in three ranges of redshift (0.05-0.24, 0.24-0.42
and 0.42-0.71) and two ranges of mass ($<10^{14}$ and $>10^{14}M_\odot$)
respectively, a strong evolution of luminosity in redshift ($L\sim z^{1.5}$)
for both ranges of masses is found. The results indicate a strong declining in
star formation rate with time in the last $\sim 6$ Gyr.


title: Multilingual Multiword Expressions

abstract:
  The project aims to provide a semi-supervised approach to identify Multiword
Expressions in a multilingual context consisting of English and most of the
major Indian languages. Multiword expressions are a group of words which refers
to some conventional or regional way of saying things. If they are literally
translated from one language to another the expression will lose its inherent
meaning.
  To automatically extract multiword expressions from a corpus, an extraction
pipeline have been constructed which consist of a combination of rule based and
statistical approaches. There are several types of multiword expressions which
differ from each other widely by construction. We employ different methods to
detect different types of multiword expressions. Given a POS tagged corpus in
English or any Indian language the system initially applies some regular
expression filters to narrow down the search space to certain patterns (like,
reduplication, partial reduplication, compound nouns, compound verbs, conjunct
verbs etc.). The word sequences matching the required pattern are subjected to
a series of linguistic tests which include verb filtering, named entity
filtering and hyphenation filtering test to exclude false positives. The
candidates are then checked for semantic relationships among themselves (using
Wordnet). In order to detect partial reduplication we make use of Wordnet as a
lexical database as well as a tool for lemmatising. We detect complex
predicates by investigating the features of the constituent words. Statistical
methods are applied to detect collocations. Finally, lexicographers examine the
list of automatically extracted candidates to validate whether they are true
multiword expressions or not and add them to the multiword dictionary
accordingly.


title: Holographic duality and applications

abstract:
  In this thesis we review some results on the generalization of the
gauge/gravity duality to new cases by using T-duality and by including
fundamental matter, finding applications to condensed matter physics. First, we
construct new supersymmetric solutions of type IIA/B and eleven-dimensional
supergravity by using non-abelian T-duality. Second, we construct a type IIA
supergravity solution with D6-brane sources, dual to an unquenched massive
flavored version of the ABJM theory. Third, we study a probe D6-brane with
worldvolume gauge fields in the ABJM background, obtaining the dual description
of a quantum Hall system. Moreover, we consider a system of a probe D6-brane in
the ABJM background and study quantum phase transitions of its dual theory.


title:
Electroweak corrections to top quark pair production in association with
  a hard photon at hadron colliders

abstract:
  We present the next-to-leading order (NLO) electroweak (EW) corrections to
the top quark pair production associated with a hard photon at the current and
future hadron colliders. The dependence of the leading order (LO) and NLO EW
corrected cross sections on the photon transverse momentum cut are
investigated. We also provide the LO and NLO EW corrected distributions of the
transverse momentum of final top quark and photon and the invariant mass of top
quark pair and top-antitop-photon system. The results show that the NLO EW
corrections are significant in high energy regions due to the EW Sudakov
effect.


title:
Convex hulls of random walks: Expected number of faces and face
  probabilities

abstract:
  Consider a sequence of partial sums $S_i= \xi_1+\dots+\xi_i$, $1\leq i\leq
n$, starting at $S_0=0$, whose increments $\xi_1,\dots,\xi_n$ are random
vectors in $\mathbb R^d$, $d\leq n$. We are interested in the properties of the
convex hull $C_n:=\mathrm{Conv}(S_0,S_1,\dots,S_n)$. Assuming that the tuple
$(\xi_1,\dots,\xi_n)$ is exchangeable and a certain general position condition
holds, we prove that the expected number of $k$-dimensional faces of $C_n$ is
given by the formula $$ \mathbb E [f_k(C_n)] = \frac{2\cdot k!}{n!}
\sum_{l=0}^{\infty}\genfrac{[}{]}{0pt}{}{n+1}{d-2l}
\genfrac{\{}{\}}{0pt}{}{d-2l}{k+1}, $$ for all $0\leq k \leq d-1$, where
$\genfrac{[}{]}{0pt}{}{n}{m}$ and $\genfrac{\{}{\}}{0pt}{}{n}{m}$ are Stirling
numbers of the first and second kind, respectively.
  Further, we compute explicitly the probability that for given indices $0\leq
i_1<\dots <i_{k+1}\leq n$, the points $S_{i_1},\dots,S_{i_{k+1}}$ form a
$k$-dimensional face of $\mathrm{Conv}(S_0,S_1,\dots,S_n)$. This is done in two
different settings: for random walks with symmetrically exchangeable increments
and for random bridges with exchangeable increments. These results generalize
the classical one-dimensional discrete arcsine law for the position of the
maximum due to E. Sparre Andersen. All our formulae are distribution-free, that
is do not depend on the distribution of the increments $\xi_k$'s.
  The main ingredient in the proof is the computation of the probability that
the origin is absorbed by a joint convex hull of several random walks and
bridges whose increments are invariant with respect to the action of direct
product of finitely many reflection groups of types $A_{n-1}$ and $B_n$. This
probability, in turn, is related to the number of Weyl chambers of a
product-type reflection group that are intersected by a linear subspace in
general position.


title:
Topological defects in Floquet systems: Anomalous chiral modes and
  topological invariant

abstract:
  Backscattering-immune chiral modes arise along certain line defects in
three-dimensional materials. In this paper, we study Floquet chiral modes along
Floquet topological defects, namely, the defects come entirely from spatial
modulations of periodic driving. We define a precise topological invariant that
counts the number of Floquet chiral modes, which is expressed as an integral on
a five-dimensional torus parameterized by $(k_x,k_y,k_z,\theta,t)$. This work
demonstrates the possibility of creating chiral modes in three-dimensional bulk
materials by modulated driving. We hope that it will stimulate further studies
of Floquet topological defects.


title: Superfluidity in Bose-Hubbard circuits

abstract:
  A semiclassical theory is provided for the metastability regime-diagram of
atomtronic superfluid circuits. Such circuits typically exhibit
high-dimensional chaos; and non-linear resonances that couple the Bogoliubov
excitations manifest themselves. Contrary to the expectation these resonances
do not originate from the familiar Beliaev and Landau damping terms. Rather,
they are described by a variant of the Cherry Hamiltonian of celestial
mechanics. Consequently we study the induced decay process, and its dependence
on the number of sites and of condensed particles.


title: Disjoint-union partial algebras

abstract:
  Disjoint union is a partial binary operation returning the union of two sets
if they are disjoint and undefined otherwise. A disjoint-union partial algebra
of sets is a collection of sets closed under disjoint unions, whenever they are
defined. We provide a recursive first-order axiomatisation of the class of
partial algebras isomorphic to a disjoint-union partial algebra of sets but
prove that no finite axiomatisation exists. We do the same for other signatures
including one or both of disjoint union and subset complement, another partial
binary operation we define.
  Domain-disjoint union is a partial binary operation on partial functions,
returning the union if the arguments have disjoint domains and undefined
otherwise. For each signature including one or both of domain-disjoint union
and subset complement and optionally including composition, we consider the
class of partial algebras isomorphic to a collection of partial functions
closed under the operations. Again the classes prove to be axiomatisable, but
not finitely axiomatisable, in first-order logic.
  We define the notion of pairwise combinability. For each of the previously
considered signatures, we examine the class isomorphic to a partial algebra of
sets/partial functions under an isomorphism mapping arbitrary suprema of
pairwise combinable sets to the corresponding disjoint unions. We prove that
for each case the class is not closed under elementary equivalence.
  However, when intersection is added to any of the signatures considered, the
isomorphism class of the partial algebras of sets is finitely axiomatisable and
in each case we give such an axiomatisation.


title: Stellar dynamo models with prominent surface toroidal fields

abstract:
  Recent spectro-polarimetric observations of solar-type stars have shown the
presence of photospheric magnetic fields with a predominant toroidal component.
If the external field is assumed to be current-free it is impossible to explain
these observations within the framework of standard mean-field dynamo theory.
In this work it will be shown that if the coronal field of these stars is
assumed to be harmonic, the underlying stellar dynamo mechanism can support
photospheric magnetic fields with a prominent toroidal component even in the
presence of axisymmetric magnetic topologies. In particular it is argued that
the observed increase in the toroidal energy in low mass fast rotating stars
can be naturally explained with an underlying $\alpha\Omega$ mechanism.


title:
Statistics and structure of spanwise rotating turbulent channel flow at
  moderate Reynolds numbers

abstract:
  A study of fully developed plane turbulent channel flow subject to spanwise
system rotation through direct numerical simulations is presented. In order to
study both the influence of the Reynolds number and spanwise rotation on
channel flow, the Reynolds number $Re = U_b h/\nu$ is varied from a low 3000 to
a moderate $31\,600$ and the rotation number $Ro = 2 \Omega h/U_b$ is varied
from 0 to 2.7, where $U_b$ is the mean bulk velocity, $h$ the channel half gap
and $\Omega$ the system rotation rate. The mean streamwise velocity profile
displays also at higher $Re$ the characteristic linear part with a slope near
to $2 \Omega$ and a corresponding linear part in the profiles of the production
and dissipation rate of turbulent kinetic energy appears. With increasing $Ro$
a distinct unstable side with large spanwise and wall-normal Reynolds stresses
and a stable side with much weaker turbulence develops in the channel. The flow
starts to relaminarize on the stable side of the channel and persisting
turbulent-laminar patterns appear at higher $Re$. If $Ro$ is further increased
the flow on the stable side becomes laminar-like while at yet higher $Ro$ the
whole flow relaminarizes, although the calm periods might be disrupted by
repeating bursts of turbulence, as explained by Brethouwer (2016). The
influence of the Reynolds number is considerable, in particular on the stable
side of the channel where velocity fluctuations are stronger and the flow
relaminarizes less quickly at higher $Re$. Visualizations and statistics show
that at $Ro=0.15$ and 0.45 large-scale structures and large counter rotating
streamwise roll cells develop on the unstable side. These become less
noticeable and eventually vanish when $Ro$ raises, especially at higher $Re$.
At high $Ro$, the largest energetic structures are larger at lower $Re$.


title: Remarks on Lagrange Multiplier Rules in Set Valued Optimization

abstract:
  In this note, three Lagrange multiplier rules introduced in the literature
for set valued optimization problems are compared. A generalization of all
three results is given which proves that under rather mild assumptions, $x$ is
a weak solution to the constrained problem, if and only if it is a weak
solution to the Lagrangian.


title:
A Lie systems approach to the Riccati hierarchy and partial differential
  equations

abstract:
  It is proved that the members of the Riccati hierarchy, the so-called Riccati
chain equations, can be considered as particular cases of projective Riccati
equations, which greatly simplifies the study of the Riccati hierarchy. This
also allows us to characterize Riccati chain equations geometrically in terms
of the projective vector fields of a flat Riemannian metric and to easily
derive their associated superposition rules. Next, we establish necessary and
sufficient conditions under which it is possible to map second-order Riccati
chain equations into conformal Riccati equations through a local
diffeomorphism. This fact can be used to determine superposition rules for
particular higher-order Riccati chain equations which depend on fewer
particular solutions than in the general case. Therefore, we analyze the
properties of Euclidean, hyperbolic and projective vector fields on the plane
in detail. Finally, the use of contact transformations enables us to apply the
derived results to the study of certain integrable partial differential
equations, such as the Kaup-Kupershmidt and Sawada-Kotera equations.


title: Moment fluid equations for ions in weakly-ionized plasma

abstract:
  A new one-dimensional fluid model for ions in weakly-ionized plasma is
proposed. The model differs from the existing ones in two aspects. First, a
more accurate approximation of the collision terms in the fluid equations is
suggested. For this purpose, the results obtained using the Monte-Carlo kinetic
model of the ion swarm experiments are considered. Second, the ion energy
equation is taken into account. The fluid equations are closed using a simple
model of the ion velocity distribution function. The accuracy of the fluid
model is examined by comparing with the results of particle-in-cell/Monte Carlo
simulations. In particular, several test problems are considered using a
parallel plate model of the capacitively coupled radio-frequency discharge. It
is shown that the results obtained using the proposed fluid model are in good
agreement with those obtained from the simulations over a wide range of
discharge conditions. An approximation of the ion velocity distribution
function for the problem under consideration is also discussed.


title: The TeV supernova remnant shell HESS J1731-347 and its surroundings

abstract:
  HESS J1731-347 is a shell-type supernova remnant emitting both TeV gamma rays
and non-thermal X-ray photons, spatially coincident with the radio SNR
G353.6-0.7. Hadronic and leptonic scenarios (or a blend of both) are discussed
in the literature to explain the TeV emission from the object. In 2011, a
$\gamma$-ray excess was also found in the neighborhood of the source (HESS
J1729-345). Here we present results of an updated analysis obtained with the
meanwhile available additional H.E.S.S. data. Beyond HESS J1731-347, the
analysis reveals the morphology of the emission of the adjacent TeV source HESS
J1729-345 and the emission in between the two sources in greater detail. The
results permit us to correlate the TeV emission outside of the SNR with
molecular gas tracers, and to confront the data with scenarios in which the TeV
emission outside the SNR is produced by escaping cosmic rays.


title:
rCOSA: A Software Package for Clustering Objects on Subsets of
  Attributes

abstract:
  \texttt{rCOSA} is a software package interfaced to the R language. It
implements statistical techniques for clustering objects on subsets of
attributes in multivariate data. The main output of COSA is a dissimilarity
matrix that one can subsequently analyze with a variety of proximity analysis
methods. Our package extends the original COSA software (Friedman and Meulman,
2004) by adding functions for hierarchical clustering methods, least squares
multidimensional scaling, partitional clustering, and data visualization. In
the many publications that cite the COSA paper by Friedman and Meulman (2004),
the COSA program is actually used only a small number of times. This can be
attributed to the fact that thse original implementation is not very easy to
install and use. Moreover, the available software is out-of-date. Here, we
introduce an up-to-date software package and a clear guidance for this advanced
technique. The software package and related links are available for free at:
\url{https://github.com/mkampert/rCOSA}


title:
Factory of realities: on the emergence of virtual spatiotemporal
  structures

abstract:
  The ubiquitous nature of modern Information Retrieval and Virtual World give
rise to new realities. To what extent are these "realities" real? Which
"physics" should be applied to quantitatively describe them? In this essay I
dwell on few examples. The first is Adaptive neural networks, which are not
networks and not neural, but still provide service similar to classical ANNs in
extended fashion. The second is the emergence of objects looking like
Einsteinian spacetime, which describe the behavior of an Internet surfer like
geodesic motion. The third is the demonstration of nonclassical and even
stronger-than-quantum probabilities in Information Retrieval, their use.
  Immense operable datasets provide new operationalistic environments, which
become to greater and greater extent "realities". In this essay, I consider the
overall Information Retrieval process as an objective physical process,
representing it according to Melucci metaphor in terms of physical-like
experiments. Various semantic environments are treated as analogs of various
realities. The readers' attention is drawn to topos approach to physical
theories, which provides a natural conceptual and technical framework to cope
with the new emerging realities.


title:
Discovery of new TeV supernova remnant shells in the Galactic plane with
  H.E.S.S

abstract:
  Supernova remnants (SNRs) are prime candidates for efficient particle
acceleration up to the knee in the cosmic ray particle spectrum. In this work
we present a new method for a systematic search for new TeV-emitting SNR shells
in 2864 hours of H.E.S.S. phase I data used for the H.E.S.S. Galactic Plane
Survey. This new method, which correctly identifies the known shell
morphologies of the TeV SNRs covered by the survey, HESS J1731-347, RX
1713.7-3946, RCW 86, and Vela Junior, reveals also the existence of three new
SNR candidates. All three candidates were extensively studied regarding their
morphological, spectral, and multi-wavelength (MWL) properties. HESS J1534-571
was associated with the radio SNR candidate G323.7-1.0, and thus is classified
as an SNR. HESS J1912+101 and HESS J1614-518, on the other hand, do not have
radio or X-ray counterparts that would permit to identify them firmly as SNRs,
and therefore they remain SNR candidates, discovered first at TeV energies as
such. Further MWL follow up observations are needed to confirm that these newly
discovered SNR candidates are indeed SNRs.


title: Kassiopeia: A Modern, Extensible C++ Particle Tracking Package

abstract:
  The Kassiopeia particle tracking framework is an object-oriented software
package using modern C++ techniques, written originally to meet the needs of
the KATRIN collaboration. Kassiopeia features a new algorithmic paradigm for
particle tracking simulations which targets experiments containing complex
geometries and electromagnetic fields, with high priority put on calculation
efficiency, customizability, extensibility, and ease of use for novice
programmers. To solve Kassiopeia's target physics problem the software is
capable of simulating particle trajectories governed by arbitrarily complex
differential equations of motion, continuous physics processes that may in part
be modeled as terms perturbing that equation of motion, stochastic processes
that occur in flight such as bulk scattering and decay, and stochastic surface
processes occuring at interfaces, including transmission and reflection
effects. This entire set of computations takes place against the backdrop of a
rich geometry package which serves a variety of roles, including initialization
of electromagnetic field simulations and the support of state-dependent
algorithm-swapping and behavioral changes as a particle's state evolves. Thanks
to the very general approach taken by Kassiopeia it can be used by other
experiments facing similar challenges when calculating particle trajectories in
electromagnetic fields. It is publicly available at
https://github.com/KATRIN-Experiment/Kassiopeia


title: Improved Lipschitz approximation of $H$-perimeter minimizing boundaries

abstract:
  We prove two new approximation results of $H$-perimeter minimizing boundaries
by means of intrinsic Lipschitz functions in the setting of the Heisenberg
group $\mathbb{H}^n$ with $n\ge2$. The first one is an improvement of a result
of Monti and is the natural reformulation in $\mathbb{H}^n$ of the classical
Lipschitz approximation in $\mathbb{R}^n$. The second one is an adaptation of
the approximation via maximal function developed by De Lellis and Spadaro.


title: Non-linear quantum dynamics in strong and short electromagnetic fields

abstract:
  In our contribution we give a brief overview of two widely discussed quantum
processes: electron-positron pairs production off a probe photon propagating
through a polarized short-pulsed electromagnetic (e.m.) (e.g.\ laser) wave
field or generalized Breit-Wheeler process and a single a photon emission off
an electron interacting with the laser pules, so-called non-linear Compton
scattering. We show that at small and moderate laser field intensities the
shape and duration of the pulse are very important for the probability of
considered processes. However, at high intensities the multi-photon
interactions of the fermions with laser field are decisive and completely
determined all aspects of subthreshold electron-positron pairs and photon
production


title:
Equation of state of the SU($3$) Yang-Mills theory: a precise
  determination from a moving frame

abstract:
  The equation of state of the SU($3$) Yang-Mills theory is determined in the
deconfined phase with a precision of about 0.5%. The calculation is carried out
by numerical simulations of lattice gauge theory with shifted boundary
conditions in the time direction. At each given temperature, up to $230\, T_c$
with $T_c$ being the critical temperature, the entropy density is computed at
several lattice spacings so to be able to extrapolate the results to the
continuum limit with confidence. Taken at face value, above a few $T_c$ the
results exhibit a striking linear behaviour in $\ln(T/T_c)^{-1}$ over almost 2
orders of magnitude. Within errors, data point straight to the Stefan-Boltzmann
value but with a slope grossly different from the leading-order perturbative
prediction. The pressure is determined by integrating the entropy in the
temperature, while the energy density is extracted from $T s=(\epsilon + p )$.
The continuum values of the potentials are well represented by Pad\'e
interpolating formulas, which also connect them well to the Stefan-Boltzmann
values in the infinite temperature limit. The pressure, the energy and the
entropy densities are compared with results in the literature. The discrepancy
among previous computations near $T_c$ is analyzed and resolved thanks to the
high precision achieved.


title:
Echoes from the Abyss: Tentative evidence for Planck-scale structure at
  black hole horizons

abstract:
  In classical General Relativity (GR), an observer falling into an
astrophysical black hole is not expected to experience anything dramatic as she
crosses the event horizon. However, tentative resolutions to problems in
quantum gravity, such as the cosmological constant problem, or the black hole
information paradox, invoke significant departures from classicality in the
vicinity of the horizon. It was recently pointed out that such near-horizon
structures can lead to late-time echoes in the black hole merger gravitational
wave signals that are otherwise indistinguishable from GR. We search for
observational signatures of these echoes in the gravitational wave data
released by advanced Laser Interferometer Gravitational-Wave Observatory
(LIGO), following the three black hole merger events GW150914, GW151226, and
LVT151012. In particular, we look for repeating damped echoes with time-delays
of $8 M \log M$ (+spin corrections, in Planck units), corresponding to
Planck-scale departures from GR near their respective horizons. Accounting for
the "look elsewhere" effect due to uncertainty in the echo template, we find
tentative evidence for Planck-scale structure near black hole horizons at false
detection probability of $1\%$ (corresponding to $2.5\sigma$ significance
level). Future observations from interferometric detectors at higher
sensitivity, along with more physical echo templates, will be able to confirm
(or rule out) this finding, providing possible empirical evidence for
alternatives to classical black holes, such as in ${\it firewall}$ or ${\it
fuzzball}$ paradigms.


title:
Alpha Conjugate Neck Structures in the Collisions of 35 MeV/nucleon 40Ca
  with 40Ca

abstract:
  The de-excitation of alpha-conjugate nuclei produced in reactions of 35
MeV/nucleon 40Ca with 40Ca has been investigated. Particular emphasis is placed
on examining the dynamics of collisions leading to projectile-like fragment
exit channels. A general exploration of the reaction systematics reveals the
binary dissipative character of the collisions and a hierarchy effect similar
to that seen for heavier systems. Investigation of the subset of events
characterized by a total alpha-conjugate mass (alpha particles plus
alpha-conjugate fragments) equal to 40 and atomic number equal to 20 reveals a
dominance of alpha-conjugate exit channels. The hierarchy effect for these
channels leads to the production of alpha-clustered neck structures with
potentially exotic geometries and properties.


title: Optical Neutrality: Invisibility without Cloaking

abstract:
  We show that it is possible to design an invisible wavelength-sized
metal-dielectric metamaterial object without evoking cloaking. Our approach is
an extension of the neutral inclusion concept by Zhou and Hu [Phys.Rev.E 74,
026607 (2006)] to Mie scatterers. We demonstrate that an increase of metal
fraction in the metamaterial leads to a transition from dielectric-like to
metal-like scattering, which proceeds through invisibility or optical
neutrality of the scatterer. Formally this is due to cancellation of multiple
scattering orders, similarly to plasmonic cloaking introduced by Alu and
Engheta [Phys.Rev.E 72, 016623 (2005)], but without introduction of the
separation of the scatterer into cloak and hidden regions.

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


title: Higgs boson couplings: measurements and theoretical interpretation

abstract:
  This report will review the Higgs boson properties: the mass, the total width
and the couplings to fermions and bosons. The measurements have been performed
with the data collected in 2011 and 2012 at the LHC accelerator at CERN by the
ATLAS and CMS experiments. Theoretical frameworks to search for new physics are
also introduced and discussed.


title:
Predicting the rise of right-wing populism in response to unbalanced
  immigration

abstract:
  Among the central tenets of globalization is free migration of labor.
Although much has been written about its benefits, little is known about the
limitations of globalization, including how immigration affects the
anti-globalist sentiment. Analyzing polls data, we find that over the last
three years in a group of EU countries affected by the recent migrant crisis,
the percentage of right-wing (RW) populist voters in a given country depends on
the prevalence of immigrants in this country's population and the total
immigration inflow into the entire EU. The latter is likely due to the EU
resembling a supranational state, where the lack of inner borders causes that
"somebody else's problem" easily turns into "my problem". We further find that
the increase in the percentage of RW voters substantially surpasses the
immigration inflow, implying that if this process continues, RW populism may
democratically prevail and eventually lead to a demise of globalization. We
present evidence for tipping points in relation to the rise of RW populism.
Finally, we model these empirical findings using a complex network framework
wherein the success of globalization largely rests on the balance between
immigration and immigrant integration.


title:
Mitigation of relative intensity noise of Quantum Dash mode-locked
  lasers for PAM4 based optical interconnects using encoding techniques

abstract:
  Quantum Dash (Q-Dash) Passively Mode-Locked Lasers (PMLLs) exhibit
significant low frequency Relative Intensity Noise (RIN), due to the high Mode
Partition Noise (MPN), which prevents the implementation of multilevel
amplitude modulation formats such as PAM4. The authors demonstrate low
frequency RIN mitigation by employing 8B/10B and Manchester encoding with PAM4
modulation format. These encoding techniques reduce the overlap between the
modulation spectral content and the low-frequency RIN of the Q-Dash devices, at
the expense of increased overhead. The RIN of the 33.6 GHz free spectral range
Q-Dash PMLL was characterized, and the results obtained show very high levels
of RIN from DC to 4 GHz, but low levels for higher frequencies. The performance
improvement for 28 GBaud 8B/10B and Manchester encoded PAM4 signal has been
demonstrated compared to the case when no encoding is used. Finally, the effect
of RIN on the system performance was demonstrated by comparing the Bit Error
Rate (BER) performance of the PAM4 signaling obtained with an External Cavity
Laser (ECL) to those obtained with Q-Dash PMLL.


title:
Software-Defined Silicon Photonics based Metro Node for Spatial and
  Wavelength Superchannel Switching

abstract:
  Due to the growing popularity of optical superchannels and software defined
networking, reconfigurable optical add-drop multiplexer (ROADM) architectures
for superchannel switching have recently attracted significant attention.
ROADMs based on micro electro-mechanical system (MEMS) and liquid
crystal-on-silicon (LCoS) technologies are predominantly used. Motivated by
requirements for low power, high-speed, small area footprint and compact
switching solutions, we propose and demonstrate spatial and wavelength flexible
superchannel switching using monolithically integrated silicon photonics (SiP)
micro-ring resonators (MRR). We demonstrate the MRRs capabilities and potential
to be used as a fundamental building block in ROADMs. Unicast and multicast
switching operation of an entire superchannel is demonstrated after
transmission over 50 km of standard single mode fiber. The performance of each
sub-channel from the 120 Gb/s QPSK Nyquist superchannel is analyzed and
degradation in error vector magnitude performance was observed for outer
sub-channels due to the 3-dB bandwidth of the MRRs, which is comparable with
the superchannel bandwidth. However, all sub-channels for all switching cases
(unicast, multicast and bi-directional operation) exhibit performance far below
the 7% FEC limit. The switching time of the SiP MRR chip is such that high
capacity superchannel interconnects between users can be setup and reconfigured
on the microsecond timescale.


title: On the dearth of ultra-faint extremely metal poor galaxies

abstract:
  Local extremely metal-poor (XMP) galaxies are of particular astrophysical
interest since they allow us to look into physical processes characteristic of
the early Universe, from the assembly of galaxy disks to the formation of stars
in conditions of low metallicity. Given the luminosity-metallicity
relationship, all galaxies fainter than Mr < -13 are expected to be XMPs.
Therefore, XMPs should be common in galaxy surveys. However, they are not,
because several observational biases hamper their detection. This work compares
the number of faint XMPs in the SDSS-DR7 spectroscopic survey with the expected
number, given the known biases and the observed galaxy luminosity function. The
faint end of the luminosity function is poorly constrained observationally, but
it determines the expected number of XMPs. Surprisingly, the number of observed
faint XMPs (around 10) is over-predicted by our calculation, unless the upturn
in the faint end of the luminosity function is not present in the model. The
lack of an upturn can be naturally understood if most XMPs are central galaxies
in their low-mass dark matter halos, which are highly depleted in baryons due
to interaction with the cosmic ultraviolet background and to other physical
processes. Our result also suggests that the upturn towards low luminosity of
the observed galaxy luminosity function is due to satellite galaxies.


title: Lattice of infinite bending-resistant fibers

abstract:
  This article present the double-periodical lattice made of infinite elastic
fibers that withstand bending and tension. The model describes the elastic
properties of flat periodic structure. With this model the behavior of a
two-dimensional array of infinite fibers is simulated. The material that
contains a row of broken fibers is considered. These broken fibers form the
failure in the material that shapes like a long straight crack. The lattice is
tensioned in the direction, which is orthogonal to the direction of straight
crack. The conditions of fracture of this lattice are investigated. The closed
form expression for the stress in the first unbroken fiber and the expression
for fracture toughness are given. These values are the functions of mechanical
parameters of lattice and tensions in both families of fibers. The closed form
solution demonstrates a notable behavior of the material. Namely, the fracture
behavior of two-dimensional lattice is cardinally depends upon the pre-stress
in the material in the direction, parallel to crack direction. If the tension
in fibers that parallel to the crack direction exists, it stabilizes the crack
growth and makes the load distribution in the unbroken fibers more even. The
two-dimensional lattice behaves in the presence of tension in both directions
similarly to the plane elastic media. The finite length crack assumes the shape
of the elongated elliptic split. Another behavior of lattice occurs if the
fibers, parallel to crack direction, are unstressed. The character of stress
concentration near the crack differs. The load distribution at the crack tip
varies considerably. The first unbroken fiber carries higher load. The crack is
lens-shaped and the crack borders form at the tip the finite angle.


title:
Hungaria region as possible source of Trojans and satellites in the
  inner solar-system

abstract:
  The Hungaria Family (the closest region of the Main Belt to Mars) is an
important source of Planet-Crossing-Asteroids and even impactors of terrestrial
planets. We present the possibility that asteroids coming from the Hungaria
Family get captured into co-orbital motion with the terrestrial planets in the
inner solar system. Therefore we carried out long term numerical integrations
(up to 100 Myr) to analyze the migrations from their original location - the
Hungaria family region- into the inner solar system. During the integration
time we observed whether or not the Hungarias get captured into a co-orbital
motion with the terrestrial planets. Our results show that 5.5% of 200
Hungarias, selected as a sample of the whole group, escape from the Hungaria
region and the probability from that to become co-orbital objects (Trojans,
satellites or horseshoes) turns out to be about 3.3%: 1.8% for Mars and 1.5%
for the Earth. In addition, we distinguished in which classes of co-orbital
motion the asteroids get captured and for how long they stay there in stable
motion. Most of the escaped Hungarias become Quasi-satellites and the ones
captured as Trojans favor the L_5 lagrangian point. This work highlights that
the Hungaria region is a source of Mars and also Earth co-orbital objects.


title: Ebert's asymmetric Hat Game

abstract:
  The Hat Game (Ebert's Hat Problem) got much attention in the beginning of
this century; not in the last place by its connections to coding theory and
computer science. All players guess simultaneously the color of their own head
observing only the hat colors of the other players. It is also allowed for each
player to pass: no color is guessed. The team wins if at least one player
guesses his or her own hat color correct and none of the players has an
incorrect guess. This paper studies Ebert's hat problem, where the
probabilities of the colors may be different (asymmetric case). Our goal is to
maximize the probability of winning the game and to describe winning
strategies. In this paper we introduce the notion of an adequate set. The
construction of adequate sets is independent of underlying probabilities and we
use this fact in the analysis of the asymmetric case. Another point of interest
is the fact that computational complexity using adequate sets is much less than
using standard methods.


title: Sparsity Preserving Algorithms for Octagons

abstract:
  Known algorithms for manipulating octagons do not preserve their sparsity,
leading typically to quadratic or cubic time and space complexities even if no
relation among variables is known when they are all bounded. In this paper, we
present new algorithms, which use and return octagons represented as weakly
closed difference bound matrices, preserve the sparsity of their input and have
better performance in the case their inputs are sparse. We prove that these
algorithms are as precise as the known ones.


title: Enhanced Asymptotic Symmetry Algebra of 2+1 Dimensional Flat Space

abstract:
  In this paper we present a new set of asymptotic boundary conditions for
Einstein gravity in 2+1 dimensions with vanishing cosmological constant that
are a generalization of the Barnich-Comp{\`e}re boundary conditions
gr-qc/0610130. These new boundary conditions lead to an asymptotic symmetry
algebra that is generated by a $\mathfrak{bms}_3$ algebra and two affine
$\hat{\mathfrak{u}}(1)$ current algebras. We then apply these boundary
conditions to Topologically Massive Gravity (TMG) and determine how the
presence of the gravitational Chern-Simons term affects the central extensions
of the asymptotic symmetry algebra. We furthermore determine the thermal
entropy of solutions obeying our new boundary conditions for both Einstein
gravity and TMG.


title:
Nicolas-Auguste Tissot: A link between cartography and quasiconformal
  theory

abstract:
  Nicolas-Auguste Tissot (1824--1897) published a series of papers on
cartography in which he introduced a tool which became known later on, among
geographers, under the name of the "Tissot indicatrix." This tool was broadly
used during the twentieth century in the theory and in the practical aspects of
the drawing of geographical maps. The Tissot indicatrix is a graphical
representation of a field of ellipses on a map that describes its distortion.
Tissot studied extensively, from a mathematical viewpoint, the distortion of
mappings from the sphere onto the Euclidean plane that are used in drawing
geographical maps, and more generally he developed a theory for the distorsion
of mappings between general surfaces. His ideas are at the heart of the work on
quasiconformal mappings that was developed several decades after him by
Gr{\"o}tzsch, Lavrentieff, Ahlfors and Teichm{\"u}ller. Gr{\"o}tzsch mentions
the work of Tissot and he uses the terminology related to his name (in
particular, Gr{\"o}tzsch uses the Tissot indicatrix). Teichm{\"u}ller mentions
the name of Tissot in a historical section in one of his fundamental papers
where he claims that quasiconformal mappings were used by geographers, but
without giving any hint about the nature of Tissot's work. The name of Tissot
is also missing from all the historical surveys on quasiconformal mappings. In
the present paper, we report on this work of Tissot. We shall also mention some
related works on cartography, on the differential geometry of surfaces, and on
the theory of quasiconformal mappings. This will place Tissot's work in its
proper context. The final version of this paper will appear in the journal
Arch. Hist. Exact Sciences.


title: Sobolev algebra through a "carr\'e du champ" identity

abstract:
  We consider abstract Sobolev spaces of Bessel-type associated with an
operator. In this work, we pursue the study of algebra properties of such
functional spaces through the corresponding semigroup. As a follow-up of [4],
we show that under the extra property of a "carr\'e du champ identity" , this
algebra property holds in a wider range than previously shown.


title:
Non-singular spacetimes with a negative cosmological constant: II.
  Static solutions of the Einstein-Maxwell equations

abstract:
  We construct infinite-dimensional families of non-singular static space
times, solutions of the vacuum Einstein-Maxwell equations with a negative
cosmological constant. The families include an infinite-dimensional family of
solutions with the usual AdS conformal structure at conformal infinity.


title:
On the persistence of H\"older regular patches of density for the
  inhomogeneous Navier-Stokes equations

abstract:
  In our recent work dedicated to the Boussinesq equations [Danchin and Zhang
2016], we established the persistence of solutions with piecewise constant
temperature along interfaces with H\"older regularity. We here address the same
problem for the inhomogeneous Navier-Stokes equations satisfied by a viscous
incompressibleand inhomogeneous fluid. We establish that, indeed, in the
slightly inhomogeneous case, patches of densities with $\mathcal{C}^{1,
\varepsilon}$ regularity propagate for all time. As in [Danchin and Zhang
2016], our result follows from the conservation of H\"older regularityalong
vector fields moving with the flow. The proof of that latter result is based on
commutator estimates involving para-vector fields, and multiplier spaces. The
overall analysis is more complicated than in [Danchin and Zhang 2016] however,
since the coupling between the mass and velocity equations in the inhomogeneous
Navier-Stokes equations is \emph{quasilinear} while it is linear for the
Boussinesq equations.


title:
Modeling BSM effects on the Higgs transverse-momentum spectrum in an EFT
  approach

abstract:
  We consider the transverse-momentum distribution of a Higgs boson produced
through gluon fusion in hadron collisions. At small transverse momenta, the
large logarithmic terms are resummed up to next-to-leading-logarithmic (NLL)
accuracy. The resummed computation is consistently matched to the
next-to-leading-order (NLO) result valid at large transverse momenta. The
ensuing Standard Model prediction is supplemented by possible new-physics
effects parametrised through three dimension-six operators related to the
modification of the top and bottom Yukawa couplings, and to the inclusion of a
point-like Higgs-gluon coupling, respectively. We present resummed
transverse-momentum spectra including the effect of these operators at NLL+NLO
accuracy and study their impact on the shape of the distribution. We find that
such modifications, while affecting the total rate within the current
uncertainties, can lead to significant distortions of the spectrum. The proper
parametrization of such effects becomes increasingly important for experimental
analyses in Run II of the LHC.


title: The discrete Pompeiu problem on the plane

abstract:
  We say that a finite subset $E$ of the Euclidean plane $\mathbb{R}^2$ has the
discrete Pompeiu property with respect to isometries (similarities), if,
whenever $f:\mathbb{R}^2\to \mathbb{C}$ is such that the sum of the values of
$f$ on any congruent (similar) copy of $E$ is zero, then $f$ is identically
zero. We show that every parallelogram and every quadrangle with rational
coordinates has the discrete Pompeiu property w.r.t. isometries. We also
present a family of quadrangles depending on a continuous parameter having the
same property. We investigate the weighted version of the discrete Pompeiu
property as well, and show that every finite linear set with commensurable
distances has the weighted discrete Pompeiu property w.r.t. isometries, and
every finite set has the weighted discrete Pompeiu property w.r.t.
similarities.


title:
Non-Local effective SU(2) Polyakov-loop models from inverse Monte-Carlo
  methods

abstract:
  The strong-coupling expansion of the lattice gauge action leads to
Polyakov-loop models that effectively describe gluodynamics at low
temperatures, and together with the hopping expansion of the fermion
determinant provides insight into the QCD phase diagram at finite density and
low temperatures, although for rather heavy quarks. At higher temperatures the
strong-coupling expansion breaks down and it is expected that the interactions
between Polyakov loops become non-local. Here, we therefore test how well pure
SU(2) gluodynamics can be mapped onto different non-local Polyakov models with
inverse Monte-Carlo methods. We take into account Polyakov loops in higher
representations and gradually add interaction terms at larger distances. We are
particularly interested in extrapolating the range of non-local terms in
sufficiently large volumes and higher representations. We study the
characteristic fall-off in strength of the non-local couplings with the
interaction distance, and its dependence on the gauge coupling in order to
compare our results to existing proposals for non-local effective actions.


title:
Optical Spectra of Ultracool Dwarfs with the Southern African Large
  Telescope

abstract:
  New spectra of 81 ultracool dwarfs (spectral types M7 and later) are
discussed. Spectral classifications of 49 objects are available in the
literature, while 32 objects are newly classified. The known spectral types
were used to test an automated classification scheme, which relies primarily on
template fitting, supplemented by matching of spectral indices calibrated
against the template spectra. An attempt was made to quantify the uncertainty
in the spectral types, which is generally better than two subclasses. Objects
for which spectral types differ by more than one subclass from the literature
classifications are discussed individually. Discrepancies between automated
classifications based on respectively template fitting and spectral index
matching, may be useful for flagging objects with unusual spectra. Aside from
the 32 first-time classifications, alternative classifications are presented
for 32 previously classified dwarfs. Very large (equivalent width greater than
130 \AA) H$\alpha$ flares are reported for the known ultracool dwarf binary
2MASS J15200224$-$4422419; curiously, the object does not appear to have
quiescent emission lines. Non-zero equivalent width measurements are listed for
a further 29 objects.


title:
Analysis of scalar dissipation in terms of vorticity geometry in
  isotropic turbulence

abstract:
  The mechanisms promoting scalar dissipation through scalar gradient
production are scrutinized in terms of vorticity alignment with respect to
strain principal axes. For that purpose, a stochastic Lagrangian model for the
velocity gradient tensor and the scalar gradient vector is used. The model
results show that the major part of scalar dissipation occurs for stretched
vorticity, namely when the vorticity vector aligns with the extensional and
intermediate strain eigenvectors. More specifically, it appears that the mean
scalar dissipation is well represented by the sample defined by alignment with
the extensional strain, while the most intense scalar dissipation is promoted
by the set of events for which vorticity aligns with the intermediate strain.
This difference is explained by rather subtle mechanisms involving the
statistics of both the strain intensities and the scalar gradient alignment
resulting from these special alignments of vorticity. The analysis allowing for
the local flow structure confirms the latter scenario for both the strain-and
rotation-dominated events. However, despite the prevailing role of strain in
promoting scalar dissipation, the difference in the level of scalar dissipation
when vorticity aligns with either the extensional or the intermediate strain
mostly arises from rotation-dominated events.


title: A testable prediction from entropic gravity

abstract:
  I have shown conceptually that quantum state has a direct relationship to
gravitational constant due to entropic force posed by Verlinde's argument and
part of the Newton-Schr\"odinger equation (N-S) in the context of gravity
induced collapse of the wavefunction via Di\'osi-Penrose proposal. This direct
relationship can be used to measure gravitational constant using
state-of-the-art mater-wave interferometry to test the entropic gravity
argument.


title: Quantizing polaritons in inhomogeneous dissipative systems

abstract:
  In this article we provide a a general analysis of canonical quantization for
polaritons in dispersive and dissipative electromagnetic media. We compare
several approaches based either on the Huttner Barnett model [B. Huttner, S. M.
Barnett, Phys. Rev. A \textbf{46}, 4306 (1992)] or the Green function, Langevin
noise method [T. Gruner, D.-G. Welsch, Phys. Rev. A \textbf{53}, 1818 (1996)]
which includes only material oscillators as fundamental variables. We show in
order to preserve unitarity, causality and time symmetry one must necessarily
include with an equal footing both electromagnetic modes and material
fluctuations on the evolution equations. This becomes particularly relevant for
all nanophotonics and plasmonics problems involving spatially localized
antennas or devices.


title: On Cracking of Charged Anisotropic Polytropes

abstract:
  Recently in \cite{34}, the role of electromagnetic field on the cracking of
spherical polytropes has been investigated without perturbing charge parameter
explicitly. In this study, we have examined the occurrence of cracking of
anisotropic spherical polytropes through perturbing parameters like anisotropic
pressure, energy density and charge. We consider two different types of
polytropes in this study. We discuss the occurrence of cracking in two
different ways $(i)$ by perturbing polytropic constant, anisotropy and charge
parameter $(ii)$ by perturbing polytropic index, anisotropy and charge
parameter for each case. We conclude that cracking appears for a wide range of
parameters in both cases. Also, our results are reduced to \cite{33} in the
absence of charge.


title:
Aggressive Quadrotor Flight through Narrow Gaps with Onboard Sensing and
  Computing using Active Vision

abstract:
  We address one of the main challenges towards autonomous quadrotor flight in
complex environments, which is flight through narrow gaps. While previous works
relied on off-board localization systems or on accurate prior knowledge of the
gap position and orientation, we rely solely on onboard sensing and computing
and estimate the full state by fusing gap detection from a single onboard
camera with an IMU. This problem is challenging for two reasons: (i) the
quadrotor pose uncertainty with respect to the gap increases quadratically with
the distance from the gap; (ii) the quadrotor has to actively control its
orientation towards the gap to enable state estimation (i.e., active vision).
We solve this problem by generating a trajectory that considers geometric,
dynamic, and perception constraints: during the approach maneuver, the
quadrotor always faces the gap to allow state estimation, while respecting the
vehicle dynamics; during the traverse through the gap, the distance of the
quadrotor to the edges of the gap is maximized. Furthermore, we replan the
trajectory during its execution to cope with the varying uncertainty of the
state estimate. We successfully evaluate and demonstrate the proposed approach
in many real experiments. To the best of our knowledge, this is the first work
that addresses and achieves autonomous, aggressive flight through narrow gaps
using only onboard sensing and computing and without prior knowledge of the
pose of the gap.


title: SALT spectroscopy of evolved massive stars

abstract:
  Long-slit spectroscopy with the Southern African Large Telescope (SALT) of
central stars of mid-infrared nebulae detected with the Spitzer Space Telescope
and Wide-field Infrared Survey Explorer (WISE) led to the discovery of numerous
candidate luminous blue variables (cLBVs) and other rare evolved massive stars.
With the recent advent of the SALT fibre-fed high-resolution echelle
spectrograph (HRS), a new perspective for the study of these interesting
objects is appeared. Using the HRS we obtained spectra of a dozen newly
identified massive stars. Some results on the recently identified cLBV Hen
3-729 are presented.


title:
Comment on 'Attempts to test an alternative electrodynamic theory of
  superconductors by low-temperature scanning tunneling and atomic force
  microscopy'

abstract:
  It is argued that alternative electrodynamics of superconductivity proposed
by Hirsch lacks mathematical rigour and it is conceptually flawed. Gauge
non-invariance of the theory makes justification of the experiment reported in
[arXiv:1607.05060] to test its prediction doubtful. It seems even with improved
techniques the outcome would remain inconclusive.