title: Ultralow Thermal Conductivity in Full-Heusler Semiconductors

abstract:
  Semiconducting half- and, to a lesser extent, full-Heusler compounds are
promising thermoelectric materials due to their compelling electronic
properties with large power factors. However, intrinsically high thermal
conductivity resulting in a limited thermoelectric efficiency has so far
impeded their widespread use in practical applications. Here, we report the
computational discovery of a class of hitherto unknown stable semiconducting
full-Heusler compounds with ten valence electrons ($X_2YZ$, $X$=Ca, Sr, and Ba;
$Y$= Au and Hg; $Z$=Sn, Pb, As, Sb, and Bi) through high-throughput $ab-initio$
screening. These new compounds exhibit ultralow lattice thermal conductivity
$\kappa_{\text{L}}$ close to the theoretical minimum due to strong anharmonic
rattling of the heavy noble metals, while preserving high power factors, thus
resulting in excellent phonon-glass electron-crystal materials.


title: Is classical flat Kasner spacetime flat in quantum gravity?

abstract:
  Quantum nature of classical flat Kasner spacetime is studied using effective
spacetime description in loop quantum cosmology. We find that even though the
spacetime curvature vanishes at the classical level, non-trivial quantum
gravitational effects can arise. For the standard loop quantization of
Bianchi-I spacetime, which uniquely yields universal bounds on expansion and
shear scalars and results in a generic resolution of strong singularities, we
find that a flat Kasner metric is not a physical solution of the effective
spacetime description, except in a limit. The lack of a flat Kasner metric at
the quantum level results from a novel feature of the loop quantum Bianchi-I
spacetime: quantum geometry induces non-vanishing spacetime curvature
components, making it not Ricci flat even when no matter is present. The
non-curvature singularity of the classical flat Kasner spacetime is avoided,
and the effective spacetime transits from a flat Kasner spacetime in asymptotic
future, to a Minkowski spacetime in asymptotic past. Interestingly, for an
alternate loop quantization which does not share some of the fine features of
the standard quantization, flat Kasner spacetime with expected classical
features exists. In this case, even with non-trivial quantum geometric effects,
the spacetime curvature vanishes. These examples show that the character of
even a flat classical vacuum spacetime can alter in a fundamental way in
quantum gravity and is sensitive to the quantization procedure.


title:
Animation and Chirplet-Based Development of a PIR Sensor Array for
  Intruder Classification in an Outdoor Environment

abstract:
  This paper presents the development of a passive infra-red sensor tower
platform along with a classification algorithm to distinguish between human
intrusion, animal intrusion and clutter arising from wind-blown vegetative
movement in an outdoor environment. The research was aimed at exploring the
potential use of wireless sensor networks as an early-warning system to help
mitigate human-wildlife conflicts occurring at the edge of a forest. There are
three important features to the development. Firstly, the sensor platform
employs multiple sensors arranged in the form of a two-dimensional array to
give it a key spatial-resolution capability that aids in classification.
Secondly, given the challenges of collecting data involving animal intrusion,
an Animation-based Simulation tool for Passive Infra-Red sEnsor (ASPIRE) was
developed that simulates signals corresponding to human and animal intrusion
and some limited models of vegetative clutter. This speeded up the process of
algorithm development by allowing us to test different hypotheses in a
time-efficient manner. Finally, a chirplet-based model for intruder signal was
developed that significantly helped boost classification accuracy despite
drawing data from a smaller number of sensors. An SVM-based classifier was used
which made use of chirplet, energy and signal cross-correlation-based features.
The average accuracy obtained for intruder detection and classification on
real-world and simulated data sets was in excess of 97%.


title:
Electron-photon interaction in a quantum point contact coupled to a
  microwave resonator

abstract:
  We study a single-mode cavity weakly coupled to a voltage-biased quantum
point contact. In a perturbative analysis, the lowest order predicts a thermal
state for the cavity photons, driven by the emission noise of the conductor.
The cavity is thus emptied as all transmission probabilities of the quantum
point contact approach one or zero. Two-photon processes are identified at
higher coupling, and pair absorption dominates over pair emission for all bias
voltages. As a result, the number of cavity photons, the cavity damping rate
and the second order coherence $g^{(2)}$ are all reduced and exhibit less
bunching than the thermal state. These results are obtained with a Keldysh path
integral formulation and reproduced with rate equations. They can be seen as a
backaction of the cavity measuring the electronic noise. Extending the standard
$P(E)$ theory to a steady-state situation, we compute the modified noise
properties of the conductor and find quantitative agreement with the
perturbative calculation.


title:
Multipliers of Hilbert Spaces of Analytic Functions on the Complex
  Half-Plane

abstract:
  It follows, from a generalised version of Paley-Wiener theorem, that the
Laplace transform is an isometry between certain spaces of weighted $L^2$
functions defined on $(0, \infty)$ and (Hilbert) spaces of analytic functions
on the right complex half-plane (for example Hardy, Bergman or Dirichlet
spaces). We can use this fact to investigate properties of multipliers and
multiplication operators on the latter type of spaces. In this paper we present
a full characterisation of multipliers in terms of a generalised concept of a
Carleson measure. Under certain conditions, these spaces of analytic functions
are not only Hilbert spaces but also Banach algebras, and are therefore
contained within their spaces of multipliers. We provide some necessary as well
as sufficient conditions for this to happen and look at its consequences.


title: Reversible Image Merging for Low-level Machine Vision

abstract:
  In this paper a hierarchical model for pixel clustering and image
segmentation is developed. In the model an image is hierarchically structured.
The original image is treated as a set of nested images, which are capable to
reversibly merge with each other. An object is defined as a structural element
of an image, so that, an image is regarded as a maximal object. The simulating
of none-hierarchical optimal pixel clustering by hierarchical clustering is
studied. To generate a hierarchy of optimized piecewise constant image
approximations, estimated by the standard deviation of approximation from the
image, the conversion of any hierarchy of approximations into the hierarchy
described in relation to the number of intensity levels by convex sequence of
total squared errors is proposed.


title: On closest isotropic tensors and their norms

abstract:
  An anisotropic elasticity tensor can be approximated by the closest tensor
belonging to a higher symmetry class. The closeness of tensors depends on the
choice of a criterion. We compare the closest isotropic tensors obtained using
four approaches: the Frobenius 36-component norm, the Frobenius 21-component
norm, the operator norm and the L2 slowness-curve fit. We find that the
isotropic tensors are similar to each other within the range of expected
measurement errors.


title: A Possible Link Between Pyriproxyfen and Microcephaly

abstract:
  The Zika virus is the primary suspect in the large increase in microcephaly
cases in 2015-6 in Brazil, however its role is unconfirmed despite individual
cases of viral infections found in neural tissue. Here we consider the
alternative that the insecticide pyriproxyfen, used in Brazilian drinking water
for mosquito control, may actually be the cause. Pyriproxifen is an analog of
juvenile hormone, which corresponds in mammals to regulatory molecules
including retinoic acid, a vitamin A metabolite, with which it has
cross-reactivity and whose application during development causes microcephaly.
Methoprene, another juvenile hormone analog approved as an insecticide has
metabolites that bind to the retinoid X receptor, and causes developmental
disorders in mammals. Isotretinoin is another example of a retinoid causing
microcephaly in human babies via activation of the retinoid X receptor.
Moreover, tests of pyriproxyfen by the manufacturer, Sumitomo, widely quoted as
giving no evidence for developmental toxicity, actually found some evidence for
such an effect, including low brain mass and arhinencephaly--incomplete
formation of the anterior cerebral hemispheres--in rat pups. Finally, the
pyriproxyfen use in Brazil is unprecedented--it has never before been applied
to a water supply on such a scale. Claims that it is not being used in Recife,
the epicenter of microcephaly cases, do not distinguish the metropolitan area
of Recife, where it is widely used, and the municipality, where it is not.
Given this combination of information we strongly recommend that the use of
pyriproxyfen in Brazil be suspended pending further investigation.


title: Lecture notes: Astrophysical fluid dynamics

abstract:
  These lecture notes and example problems are based on a course given at the
University of Cambridge in Part III of the Mathematical Tripos.
  Fluid dynamics is involved in a very wide range of astrophysical phenomena,
such as the formation and internal dynamics of stars and giant planets, the
workings of jets and accretion discs around stars and black holes, and the
dynamics of the expanding Universe. Effects that can be important in
astrophysical fluids include compressibility, self-gravitation and the
dynamical influence of the magnetic field that is 'frozen in' to a highly
conducting plasma.
  The basic models introduced and applied in this course are Newtonian gas
dynamics and magnetohydrodynamics (MHD) for an ideal compressible fluid. The
mathematical structure of the governing equations and the associated
conservation laws are explored in some detail because of their importance for
both analytical and numerical methods of solution, as well as for physical
interpretation. Linear and nonlinear waves, including shocks and other
discontinuities, are discussed. The spherical blast wave resulting from a
supernova, and involving a strong shock, is a classic problem that can be
solved analytically. Steady solutions with spherical or axial symmetry reveal
the physics of winds and jets from stars and discs. The linearized equations
determine the oscillation modes of astrophysical bodies, as well as determining
their stability and their response to tidal forcing.


title: On a question of Etnyre and Van Horn-Morris

abstract:
  We answer Question 6.12 in the paper "Monoids in the mapping class group"
written by Etnyre and Van Horn-Morris.


title: Indiscreet logarithms in finite fields of small characteristic

abstract:
  Recently, several striking advances have taken place regarding the discrete
logarithm problem (DLP) in finite fields of small characteristic, despite
progress having remained essentially static for nearly thirty years, with the
best known algorithms being of subexponential complexity. In this expository
article we describe the key insights and constructions which culminated in two
independent quasi-polynomial algorithms. To put these developments into both a
historical and a mathematical context, as well as to provide a comparison with
the cases of so-called large and medium characteristic fields, we give an
overview of the state-of-the-art algorithms for computing discrete logarithms
in all finite fields. Our presentation aims to guide the reader through the
algorithms and their complexity analyses ab initio.


title: Nonlinear elasticity of semiflexible filament networks

abstract:
  We develop a continuum theory for equilibrium elasticity of a network of
crosslinked semiflexible filaments, spanning the full range between flexible
entropy-driven chains to stiff athermal rods. We choose the 3-chain
constitutive model over several plausible candidates, and derive analytical
expressions for the elastic energy at arbitrary strain, with the corresponding
stress-strain relationship. The theory fits well to a wide range of
experimental data on simple shear in different filament networks,
quantitatively matching the differential shear modulus variation with stress,
with only two adjustable parameters (which represent the filament stiffness and
pre-tension in the network, respectively). The general theory accurately
describes the crossover between the positive and negative Poynting effect
(normal stress on imposed shear) on increasing the stiffness of filaments
forming the network.


title:
Distinguishing number and distinguishing index of natural and fractional
  powers of graphs

abstract:
  The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the
least integer $d$ such that $G$ has an vertex labeling (edge labeling) with $d$
labels that is preserved only by a trivial automorphism. For any $n \in
\mathbb{N}$, the $n$-subdivision of $G$ is a simple graph $G^{\frac{1}{n}}$
which is constructed by replacing each edge of $G$ with a path of length $n$.
The $m^{th}$ power of $G$, is a graph with same set of vertices of $G$ and an
edge between two vertices if and only if there is a path of length at most $m$
between them. The fractional power of $G$, denoted by $G^{\frac{m}{n}}$ is
$m^{th}$ power of the $n$-subdivision of $G$ or $n$-subdivision of $m$-th power
of $G$. In this paper we study the distinguishing number and distinguishing
index of natural and fractional powers of $G$. We show that the natural powers
more than two of a graph distinguished by three edge labels. Also we show that
for a connected graph $G$ of order $n \geqslant 3$ with maximum degree $\Delta
(G)$, $D(G^{\frac{1}{k}})\leqslant min\{s: 2^k+\sum^s_{n=3}n^{k-1}\geqslant
\Delta (G)\}$ and for $m\geqslant 3$, $D'(G^{\frac{m}{k}})\leqslant 3$.


title: On the Existence of Mock Injective Modules for Algebraic Groups

abstract:
  Let $G$ be an affine algebraic group scheme over an algebraically closed
field $k$ of characteristic $p>0$, and let $G_r$ denote the $r$-th Frobenius
kernel of $G$. Motivated by recent work of Friedlander, the authors investigate
the class of mock injective $G$-modules, which are defined to be those rational
$G$-modules that are injective on restriction to $G_r$ for all $r\geq 1$. In
this paper the authors provide necessary and sufficient conditions for the
existence of non-injective mock injective $G$-modules, thereby answering a
question raised by Friedlander. Furthermore, the authors investigate the
existence of non-injective mock injectives with simple socles. Interesting
cases are discovered that show that this can occur for reductive groups, but
will not occur for their Borel subgroups.


title: Type decomposition in NIP theories

abstract:
  We prove that any type in an NIP theory can be decomposed into a stable part
(a generically stable partial type) and a distal-like quotient.


title:
Spectral classification and properties of the O Vz stars in the Galactic
  O-Star Spectroscopic Survey (GOSSS)

abstract:
  On the basis of the Galactic O-Star Spectroscopic Survey (GOSSS), a detailed
systematic investigation of the O Vz stars is presented. The currently used
spectral classification criteria are rediscussed, and the Vz phenomenon is
recalibrated through the addition of a quantitative criterion based on the
equivalent widths of the He I 4471, He II 4542, and He II 4686 spectral lines.
The GOSSS O Vz and O V populations resulting from the newly adopted spectral
classification criteria are comparatively analyzed. The locations of the O Vz
stars are probed, showing a concentration of the most extreme cases toward the
youngest star forming regions. The occurrence of the Vz spectral peculiarity in
a solar-metallicity environment, as predicted by the fastwind code, is also
investigated, confirming the importance of taking into account several
processes for the correct interpretation of the phenomenon.


title:
New Exact and Numerical Solutions of the (Convection-)Diffusion Kernels
  on SE(3)

abstract:
  We consider hypo-elliptic diffusion and convection-diffusion on $\mathbb{R}^3
\rtimes S^2$, the quotient of the Lie group of rigid body motions SE(3) in
which group elements are equivalent if they are equal up to a rotation around
the reference axis. We show that we can derive expressions for the convolution
kernels in terms of eigenfunctions of the PDE, by extending the approach for
the SE(2) case. This goes via application of the Fourier transform of the PDE
in the spatial variables, yielding a second order differential operator. We
show that the eigenfunctions of this operator can be expressed as (generalized)
spheroidal wave functions. The same exact formulas are derived via the Fourier
transform on SE(3). We solve both the evolution itself, as well as the
time-integrated process that corresponds to the resolvent operator.
Furthermore, we have extended a standard numerical procedure from SE(2) to
SE(3) for the computation of the solution kernels that is directly related to
the exact solutions. Finally, we provide a novel analytic approximation of the
kernels that we briefly compare to the exact kernels.


title:
Tiered Forensic Methodology Model for Digital Field Triage by
  Non-Digital Evidence Specialists

abstract:
  Due to budgetary constraints and the high level of training required, digital
forensic analysts are in short supply in police forces the world over. This
inevitably leads to a prolonged time taken between an investigator sending the
digital evidence for analysis and receiving the analytical report back. In an
attempt to expedite this procedure, various process models have been created to
place the forensic analyst in the field conducting a triage of the digital
evidence. By conducting triage in the field, an investigator is able to act
upon pertinent information quicker, while waiting on the full report. The work
presented as part of this paper focuses on the training of front-line personnel
in the field triage process, without the need of a forensic analyst attending
the scene. The premise has been successfully implemented within
regular/non-digital forensics, i.e., crime scene investigation. In that field,
front-line members have been trained in specific tasks to supplement the
trained specialists. The concept of front-line members conducting triage of
digital evidence in the field is achieved through the development of a new
process model providing guidance to these members. To prove the model's
viability, an implementation of this new process model is presented and
evaluated. The results outlined demonstrate how a tiered response involving
digital evidence specialists and non-specialists can better deal with the
increasing number of investigations involving digital evidence.


title:
Effect of relativistic motion on witnessing non-classicality of quantum
  states

abstract:
  We show that the operational definition of non-classicality of a quantum
state depends on the motion of the observer. We use the relativistic
Unruh-DeWitt detector model to witness nonclassicality of the probed field
state. It turns out that the witness based on the properties of the
P-representation of the quantum state depends on the trajectory of the
detector. Inertial and noninertial motion of the device have qualitatively
different impact on the performance of the witness.


title:
Applying universal scaling laws to identify the best molecular design
  paradigms for second-order nonlinear optics

abstract:
  We apply scaling and the theory of the fundamental limits of the second-order
molecular susceptibility to identify material classes with ultralarge
nonlinear-optical response. Size effects are removed by normalizing all
nonlinearities to get intrinsic values so that the scaling behavior of a series
of molecular homologues can be determined. Several new figures of merit are
proposed that quantify the desirable properties for molecules that can be
designed by adding a sequence of repeat units, and used in the assessment of
the data. Three molecular classes are found. They are characterized by
sub-scaling, nominal scaling, or super-scaling. Super-scaling homologues most
efficiently take advantage of increased size. We apply our approach to data
currently available in the literature to identify the best super-scaling
molecular paradigms with the aim of identifying desirable traits of new
materials.


title: Canonical invariance of spatially covariant scalar-tensor theory

abstract:
  We investigate invariant canonical transformations of a spatially covariant
scalar-tensor theory of gravity, called the XG theory, by which the action or
the Hamiltonian and the primary constraints keep their forms invariant. We
derive the Hamiltonian in a non perturbative manner and complete the
Hamiltonian analysis for all regions of the theory. We confirm that the theory
has at most 3 degrees of freedom in all regions of the theory as long as the
theory has the symmetry under the spatial diffeormorphism. Then, we derive the
invariant canonical transformation by using the infinitesimal transformation.
The invariant metric transformation of the XG theory contains a vector product
as well as the disformal transformation. The vector product and the disformal
factor can depend on the higher order derivative terms of the scalar field and
the metric. In addition, we discover the invariant canonical transformation
which transforms the momentum of the metric. Using the invariant
transformation, we study the relation between the Horndeski theory and the GLPV
theory, and find that we can not obtain the arbitrary GLPV theory from the
Horndeski theory through the invariant canonical transformation we have found.


title:
Employee Trust Based Industrial Device Deployment and Initial Key
  Establishment

abstract:
  An efficient key management system is required to support cryptography. Most
key management systems use either pre-installed shared keys or install initial
security parameters using out-of-band channels. These methods create an
additional burden for engineers who manage the devices in industrial plants.
Hence, device deployment in industrial plants becomes a challenging task in
order to achieve security. In this work, we present a device deployment
framework that can support key management using the existing trust towards
employees in a plant. This approach reduces the access to initial security
parameters by employees, rather it helps to bind the trust of the employee with
device commissioning. Thus, this approach presents a unique solution to the
device deployment problem. Further, through a proof-of-concept implementation
and security analysis using the AVISPA tool, we present that our framework is
feasible to implement and satisfies our security objectives.


title: Counting isospectral manifolds

abstract:
  Given a simple Lie group $H$ of real rank at least $2$ we show that the
maximum cardinality of a set of isospectral non-isometric $H$-locally symmetric
spaces of volume at most $x$ grows at least as fast as $x^{c\log x/ (\log\log
x)^2}$ where $c = c(H)$ is a positive constant. In contrast with the real rank
$1$ case, this bound comes surprisingly close to the total number of such
spaces as estimated in a previous work of Belolipetsky and Lubotzky [BL]. Our
proof uses Sunada's method, results of [BL], and some deep results from number
theory. We also discuss an open number-theoretical problem which would imply an
even faster growth estimate.


title:
Current Challenges and Future Research Areas for Digital Forensic
  Investigation

abstract:
  Given the ever-increasing prevalence of technology in modern life, there is a
corresponding increase in the likelihood of digital devices being pertinent to
a criminal investigation or civil litigation. As a direct consequence, the
number of investigations requiring digital forensic expertise is resulting in
huge digital evidence backlogs being encountered by law enforcement agencies
throughout the world. It can be anticipated that the number of cases requiring
digital forensic analysis will greatly increase in the future. It is also
likely that each case will require the analysis of an increasing number of
devices including computers, smartphones, tablets, cloud-based services,
Internet of Things devices, wearables, etc. The variety of new digital evidence
sources pose new and challenging problems for the digital investigator from an
identification, acquisition, storage and analysis perspective. This paper
explores the current challenges contributing to the backlog in digital
forensics from a technical standpoint and outlines a number of future research
topics that could greatly contribute to a more efficient digital forensic
process.


title: Constructive reflection principles for regular theories

abstract:
  Classically, any structure for a signature {\Sigma} may be completed to a
model of a desired regular theory T by means of the chase construction or small
object argument. Moreover, this exhibits Mod(T) as weakly reflective in
Str({\Sigma}).
  We investigate this in the constructive setting. The basic construction is
unproblematic, however, it is no longer a weak reflection. Indeed, we show that
various reflection principles for models of regular theories are equivalent to
choice principles in the ambient set theory. However, the embedding of a
structure into its chase-completion still satisfies a conservativity property,
which suffices for applications such as the completeness of regular logic with
respect to Tarski (i.e. set) models.
  Unlike most constructive developments of predicate logic, we do not assume
that equality between symbols in the signature is decidable. While in this
setting, we also give a version of one classical lemma which is trivial over
discrete signatures but more interesting here: the abstraction of constants in
a proof to variables.


title: Semiclassical resolvent bounds in dimension two

abstract:
  We give an elementary proof of weighted resolvent bounds for semiclassical
Schr\"odinger operators in dimension two. We require the potential function to
be Lipschitz with long range decay. The resolvent norm grows exponentially in
the inverse semiclassical parameter, but near infinity it grows linearly. Our
result covers the missing case from the work of Datchev.


title: Hierarchical Compound Poisson Factorization

abstract:
  Non-negative matrix factorization models based on a hierarchical
Gamma-Poisson structure capture user and item behavior effectively in extremely
sparse data sets, making them the ideal choice for collaborative filtering
applications. Hierarchical Poisson factorization (HPF) in particular has proved
successful for scalable recommendation systems with extreme sparsity. HPF,
however, suffers from a tight coupling of sparsity model (absence of a rating)
and response model (the value of the rating), which limits the expressiveness
of the latter. Here, we introduce hierarchical compound Poisson factorization
(HCPF) that has the favorable Gamma-Poisson structure and scalability of HPF to
high-dimensional extremely sparse matrices. More importantly, HCPF decouples
the sparsity model from the response model, allowing us to choose the most
suitable distribution for the response. HCPF can capture binary, non-negative
discrete, non-negative continuous, and zero-inflated continuous responses. We
compare HCPF with HPF on nine discrete and three continuous data sets and
conclude that HCPF captures the relationship between sparsity and response
better than HPF.


title: Tuning emergent magnetism in a Hund's impurity

abstract:
  The recently proposed theoretical concept of a Hund's metal is regarded as a
key to explain the exotic magnetic and electronic behavior occuring in the
strongly correlated electron systems of multiorbital metallic materials.
However, a tuning of the abundance of parameters, that determine these systems,
is experimentally challenging. Here, we investigate the smallest possible
realization of a Hund's metal, a Hund's impurity, realized by a single magnetic
impurity strongly hybridized to a metallic substrate. We experimentally control
all relevant parameters including magnetic anisotropy and hybridization by
hydrogenation with the tip of a scanning tunneling microscope and thereby tune
it through a regime from emergent magnetic moments into a multi-orbital Kondo
state. Our comparison of the measured temperature and magnetic field dependent
spectral functions to advanced many-body theories will give relevant input for
their application to non-Fermi liquid transport, complex magnetic order, or
unconventional superconductivity.


title: Exclusive Jet Measurement in Special LHC Runs - Feasibility Studies

abstract:
  The feasibility studies of the central exclusive jet production at the LHC
using the proton tagging technique are presented. Three classes of data taking
scenarios are considered: double tag at high pile-up, single tag at low pile-up
and double tag at low pile-up. Analyses were performed at the c.m. energy of 14
TeV for the ATLAS experiment, but are also valid for the CMS/TOTEM detectors.


title:
A Comprehensive Statistical Description of Radio-Through-$\gamma$-Ray
  Spectral Energy Distributions of All Known Blazars

abstract:
  We combined multi-wavelength data for blazars from the Roma-BZCAT catalog and
analyzed hundreds of X-ray spectra. We present the fluxes and Spectral Energy
Distributions (SEDs), in 12 frequency bands from radio to $\gamma$-rays, for a
final sample of 2214 blazars. Using a model-independent statistical approach,
we looked for systematic trends in the SEDs; the most significant trends
involved the radio luminosities and X-ray spectral indices of the blazars. We
used a Principal Component Analysis (PCA), to determine the basis vectors of
the blazar SEDs and, in order to maximize the size of the sample, imputed
missing fluxes using the K-nearest neighbors method. Using more than an order
of magnitude more data than was available when Fossati et al. (1997, 1998)
first reported trends of SED shape with blazar luminosity, we confirmed the
anti-correlation between radio luminosity and synchrotron peak frequency,
although with greater scatter than was seen in the smaller sample. The same
trend can be seen between bolometric luminosity and synchrotron peak frequency.
Finally, we used all available blazar data to determine an empirical SED
description that depends only on the radio luminosity at 1.4~GHz and the
redshift. We verified that this statistically significant relation was not a
result of the luminosity-luminosity correlations that are natural in
flux-limited samples (i.e., where the correlation is actually caused by the
redshift rather than the luminosity).


title: The torsion-free rank of homology in towers of soluble pro-p groups

abstract:
  We show that for every finitely presented pro-$p$
nilpotent-by-abelian-by-finite group $G$ there is an upper bound on
$\dim_{\mathbb{Q}_p} (H_1(M, \mathbb{Z}_p) \otimes_{\mathbb{Z}_p} \mathbb{Q}_p
)$, as $M$ runs through all pro-$p$ subgroups of finite index in $G$.


title: Dark matter astrophysical uncertainties and the neutrino floor

abstract:
  The search for weakly interacting massive particles (WIMPs) by direct
detection faces an encroaching background due to coherent neutrino-nucleus
scattering. For a given WIMP mass the cross section at which neutrinos
constitute a dominant background is dependent on the uncertainty on the flux of
each neutrino source from either the Sun, supernovae or atmospheric cosmic ray
collisions. However there are also considerable uncertainties with regard to
the astrophysical ingredients to the predicted WIMP signal. Uncertainties in
the velocity of the Sun with respect to the Milky Way dark matter halo, the
local density of WIMPs, and the shape of the local WIMP speed distribution all
have an effect on the expected event rate in direct detection experiments and
hence will change the region of the WIMP parameter space for which neutrinos
are a significant background. In this work we extend the WIMP+neutrino analysis
to account for the uncertainty in the astrophysics dependence of the WIMP
signal. We show the effect of uncertainties on projected discovery limits with
an emphasis on low WIMP masses (less than 10 GeV) when Solar neutrino
backgrounds are most important. We find that accounting for astrophysical
uncertainties changes the shape of the neutrino floor as a function of WIMP
mass but also causes it to appear at cross sections up to an order of magnitude
larger, extremely close to existing experimental limits - indicating that
neutrino backgrounds will become an issue sooner than previously thought. We
also explore how neutrinos hinder the estimation of WIMP parameters and how
astrophysical uncertainties impact the discrimination of WIMPs and neutrinos
with the use of their respective time dependencies.


title:
Liouville properties and critical value of fully nonlinear elliptic
  operators

abstract:
  We prove some Liouville properties for sub- and supersolutions of fully
nonlinear degenerate elliptic equations in the whole space. Our assumptions
allow the coefficients of the first order terms to be large at infinity,
provided they have an appropriate sign, as in Ornstein- Uhlenbeck operators. We
give two applications. The first is a stabilization property for large times of
solutions to fully nonlinear parabolic equations. The second is the solvability
of an ergodic Hamilton-Jacobi-Bellman equation that identifies a unique
critical value of the operator.


title: Nematicity in LaFeAsO$_{1-x}$F$_x$

abstract:
  Orbital ordering has recently emerged as another important state in iron
based superconductors, and its role for superconductivity as well as its
connection to magnetic order and orthorhombic lattice distortion are heavily
debated. In order to search for signatures of this so-called nematic phase in
oxypnictides, we revisit the normal state properties of the pnictide
superconductor LaFeAsO$_{1-x}$F$_x$ with a focus on resistivity, Nernst effect,
thermal expansion, and $^{75}$As NMR data. The transport properties at the
underdoped level $x=0.05$ exhibit pronounced anomalies at about the same
temperature where undoped LaFeAsO develops long-range nematic ordering, i.e. at
about 160 K. Furthermore, the $^{75}$As-NMR spin-lattice relaxation rate
$1/(T_1T)$ reveals a progressive slowing down of spin fluctuations. Yet,
long-range magnetic order and also a detectable orthorhombic lattice distortion
are absent. Thus, we conclude from the data that short-range orbital-nematic
ordering or a slowly fluctuating form of it sets in near 160 K. Remarkably, all
anomalies in the transport and also the indications of slow spin fluctuations
disappear close to optimal doping $x=0.1$ which suggests that in
LaFeAsO$_{1-x}$F$_x$ the nematic phase actually competes with
superconductivity.


title: New results on metric-locating-dominating sets of graphs

abstract:
  A dominating set $S$ of a graph is a metric-locating-dominating set if each
vertex of the graph is uniquely distinguished by its distances from the
elements of $S$, and the minimum cardinality of such a set is called the
metric-location-domination number. In this paper, we undertake a study that, in
general graphs and specific families, relates metric-locating-dominating sets
to other special sets: resolving sets, dominating sets, locating-dominating
sets and doubly resolving sets. We first characterize classes of trees
according to certain relationships between their metric-location-domination
number and their metric dimension and domination number. Then, we show
different methods to transform metric-locating-dominating sets into
locating-dominating sets and doubly resolving sets. Our methods produce new
bounds on the minimum cardinalities of all those sets, some of them involving
parameters that have not been related so far.


title:
Tunneling into thin superconducting films: interface-induced
  quasiparticle lifetime reduction

abstract:
  Scanning tunneling spectroscopy measurements of superconducting thin
lanthanum films grown on a normal metal tungsten substrate reveal an
extraordinarily large broadening of the coherence peaks. The observed
broadening corresponds to very short electron-like quasiparticle lifetimes in
the tunneling process. A thorough analysis considering the different relaxation
processes reveals that the dominant mechanism is an efficient quasiparticle
relaxation at the interface between the superconducting film and the underlying
substrate. This process is of general relevance to scanning tunneling
spectroscopy studies on thin superconducting films and enables measurements of
film thicknesses via a spectroscopic method.


title:
The orientation as a signature of cultural identity: The historic
  churches of Lanzarote

abstract:
  The orientation of Christian churches is a well-known distinctive feature of
their architecture. There is a general tendency to align their apses in the
solar range, favoring orientations close to the east (astronomical equinox),
although the alignments in the opposite direction, namely, with the apse
towards the west, are not unusual. The case of the churches built in northwest
Africa before the arrival of Islam is paradigmatic in this regard, and may
reflect earlier traditions. The Canary Islands is the western end of this North
African cultural koine, so we thought it would be relevant to study a compact
set of old churches in one of the islands of the archipelago, choosing to start
our project with Lanzarote. We have measured the orientation of a total of 30
churches built prior to 1810, as well as a few buildings of later times, nearly
a complete sample of all the island Christian sanctuaries. The analysis of this
sample indicates that a definite orientation pattern was followed on the island
but, unlike the standard one often found in most of the Christian world, this
prototype is twofold. On the one hand, the representative orientation to the
east (or west) is present. However, the sample has also a marked orientation
towards the north-northeast, which is as far as we know a pattern exclusive of
Lanzarote. We analyze the reasons for this rule and suggest that one possible
explanation could be a rather prosaic one, namely, that sometimes earthly needs
are more relevant than religious beliefs.


title: Issues of Regional Development and Evaluation Problems

abstract:
  Region of the country is treated as an open megasystem that consists of many
interconnected complex network systems. Classification of such systems on the
basis of ordered motion of flows is performed. The main approaches to
investigation of complex systems are described. Theory of evaluation is
considered as a tool for analysis of network systems. Purpose and subject of
evaluation of the systems are formulated. The main problems of evaluation are
analyzed and the ways of further research are determined.


title:
Comment on "Elastic Membrane Deformations Govern Interleaflet Coupling
  of Lipid-Ordered Domains"

abstract:
  In lieu of abstract, first paragraph reads: Galimzyanov et al. [1] find that
line tension between thick liquid-ordered ($L_{o}$) and thinner
liquid-disordered ($L_{d}$) registered lipid bilayer phases is minimised by an
asymmetric "slip region", length $L\!\sim\!5\,\textrm{nm}$ (Fig. 1). They claim
that line tensions alone explain domain registration, without "direct"
(area-dependent) inter-leaflet interaction [2,3]. We show this is unfounded,
without direct interaction their results would predict
\textit{antiregistration}, dependent on composition. To find equilibrium from
line energies, line \textit{tensions} must be combined with interfacial lengths
for given states at given composition. This was not done in [1].


title: Mean-field instabilities and cluster formation in nuclear reactions

abstract:
  We review recent results on intermediate mass cluster production in heavy ion
collisions at Fermi energy and in spallation reactions. Our studies are based
on modern transport theories, employing effective interactions for the nuclear
mean-field and incorporating two-body correlations and fluctuations. Namely we
will consider the Stochastic Mean Field (SMF) approach and the recently
developed Boltzmann-Langevin One Body (BLOB) model. We focus on cluster
production emerging from the possible occurrence of low-density mean-field
instabilities in heavy ion reactions. Within such a framework, the respective
role of one and two-body effects, in the two models considered, will be
carefully analysed. We will discuss, in particular, fragment production in
central and semi-peripheral heavy ion collisions, which is the object of many
recent experimental investigations. Moreover, in the context of spallation
reactions, we will show how thermal expansion may trigger the development of
mean-field instabilities, leading to a cluster formation process which competes
with important re-aggregation effects.


title:
Quantum network protocol for qudits with use of quantum repeaters and
  Pauli Z-type operational errors

abstract:
  In this chapter a quantum communication protocol with use of repeaters is
presented. The protocol is constructed for qudits i.e. the generalized quantum
information units. One-dit teleportation is based on the generalized Pauli-Z
(phase-flip) gate's correction. This approach avoids using Pauli-X and Hadamard
gates unlike in other known protocols based on quantum repeaters which were
constructed for qubits and qudits. It is also important to mention that the
repeaters based on teleportation protocol, described in this chapter, allow a
measurement in the standard base (what simplifies the measurement process) and
the use of teleportation causes only Pauli-Z operational errors.


title: Nonlinear Generalization of Den Hartog's Equal-Peak Method

abstract:
  This study addresses the mitigation of a nonlinear resonance of a mechanical
system. In view of the narrow bandwidth of the classical linear tuned vibration
absorber, a nonlinear absorber, termed the nonlinear tuned vibration absorber
(NLTVA), is introduced in this paper. An unconventional aspect of the NLTVA is
that the mathematical form of its restoring force is tailored according to the
nonlinear restoring force of the primary system. The NLTVA parameters are then
determined using a nonlinear generalization of Den Hartog's equal-peak method.
The mitigation of the resonant vibrations of a Duffing oscillator is considered
to illustrate the proposed developments.


title: Electromagnetic fields, size, and copy of a single photon

abstract:
  Photons are almost involved in each field of science and daily life of
everyone. However, there are still some fundamental and puzzling questions such
as what a photon is.The expressions of electromagnetic fields of a photon are
here proposed. On the basis of the present expressions, we calculate the
energy, momentum, and spin angular momentum of a photon, derive the relations
between the photon size and wavelength, and reveal the differences between a
photon and its copy. The results show that the present expressions properly
describe the particle characteristics of a photon; the length of a photon is
half of the wavelength, and the radius is proportional to square root of the
wavelength; a photon can ionize a hydrogen atom at the ground state only if its
radius is less than the Bohr radius; a photon and its copy have the phase
difference of {\pi} and constitute a phase-entangled photon pair; the
phase-entangled n-photon train results from the sequential stimulated emissions
and belongs to the Fock state. A laser beam is an ensemble of the n-photon
trains and belongs to the coherent state. The threshold power of a laser is
equal to the power of the n-photon train. These provide a bridge between the
wave theory of light and quantum optics and will further advance research and
application of the related fields.


title: Ropelength, crossing number and finite type invariants of links

abstract:
  Ropelength and embedding thickness are related measures of geometric
complexity of classical knots and links in Euclidean space. In their recent
work, Freedman and Krushkal posed a question regarding lower bounds for
embedding thickness of $n$-component links in terms of the Milnor linking
numbers. The main goal of the current paper is to provide such estimates and
thus generalizing the known linking number bound. In the process, we collect
several facts about finite type invariants and ropelength/crossing number of
knots. We give examples of families of knots, where such estimates behave
better than the well-known knot-genus estimate.


title: Approximate Agreement under Mobile Byzantine Faults

abstract:
  In this paper we address Approximate Agreement problem in the Mobile
Byzantine faults model. Our contribution is threefold. First, we propose the
the first mapping from the existing variants of Mobile Byzantine models to the
Mixed-Mode faults model.This mapping further help us to prove the correctness
of class MSR (Mean-Subsequence-Reduce) Approximate Agreement algorithms in the
Mobile Byzantine fault model, and is of independent interest. Secondly, we
prove lower bounds for solving Approximate Agreement under all existing Mobile
Byzantine faults models. Interestingly, these lower bounds are different from
the static bounds. Finally, we propose matching upper bounds. Our paper is the
first to link the Mobile Byzantine Faults models and the Mixed-Mode Faults
models, and we advocate that a similar approach can be adopted in order to
prove the correctness of other classical distributed building blocks (e.g.
agreement, clock synchronization, interactive consistency etc) under Mobile
Byzantine Faults model.


title:
Dynamical Gravitational Coupling as a Modified Theory of General
  Relativity

abstract:
  A modified theory of general relativity is proposed, where the gravitational
constant is replaced by a dynamical variable in space-time. The dynamics of the
gravitational coupling is described by a family of parametrized null geodesics,
implying that the gravitational coupling at a space-time point is determined by
solving transport equations along all null geodesics through this point.
  General relativity with dynamical gravitational coupling (DGC) is introduced.
We motivate DGC from general considerations and explain how it arises in the
context of causal fermion systems. The underlying physical idea is that the
gravitational coupling is determined by microscopic structures on the Planck
scale which propagate with the speed of light.
  In order to clarify the mathematical structure, we analyze the conformal
behavior and prove local existence and uniqueness of the time evolution. The
differences to Einstein's theory are worked out in the examples of the
Friedmann-Robertson-Walker model and the spherically symmetric collapse of a
shell of matter. Potential implications for the problem of dark matter and for
inflation are discussed. It is shown that the effects in the solar system are
too small for being observable in present-day experiments.


title: Inflating without a flat potential: Viscous inflation

abstract:
  Bulk viscosity leads to negative pressure, which is a key ingredient for
successful inflation. We build an inflationary model where the slow-roll of the
inflaton field is driven by a viscous component instead of the flat potential
commonly used. Since viscosity does not contribute to the energy density of the
Universe, the Hubble rate depends only on the kinetic energy of the inflaton.
The power spectrum is almost scale-invariant, with a tilt depending on the
slow-roll parameters defined within the model.


title: Gravitational waves in the $f(R,T)$ theory of gravity

abstract:
  There is a host of alternative theories of gravitation in the literature,
among them the $f(R,T)$ recently elaborated by Harko and collaborators. In
these theories the $R$ and $T$ are respectively the Ricci scalar and the trace
of the energy momentum tensor. There is already in literature a series of
studies of different forms of the $f(R,T)$ functions as well as their
cosmological consequences. However, there is not so far in the literature
studies related to the gravitational waves in $f(R,T)$ gravity. Here we
consider such an issue, in particular studying the putative extra polarization
models that can well appear in such theories. To do that, we consider different
functional forms for $f(R,T)$.


title:
Tunable scattering cancellation of light using anisotropic cylindrical
  cavities

abstract:
  Engineered core-shell cylinders are good candidates for applications in
invisibility and cloaking.In particular, hyperbolic nanotubes demonstrate
tunable ultra-low scattering cross section in the visible spectral range. In
this work we investigate the limits of validity of the condition for
invisibility, which was shown to rely on reaching an epsilon near zero in one
of the components of the effective permittivity tensor of the anisotropic
metamaterial cavity. For incident light polarized perpendicularly to the
scatterer axis, critical deviations are found in low-birefringent arrangements
and also with high-index cores. We demonstrate that the ability of anisotropic
metallodielectric nanocavities to dramatically reduce the scattered light is
associated with a multiple Fano-resonance phenomenon. We extensively explore
such resonant effect to identify tunable windows of invisibility.


title:
Interaction induced Dirac fermions from quadratic band touching in
  bilayer graphene

abstract:
  We revisit the effect of local interactions on the quadratic band touching
(QBT) of Bernal stacked bilayer graphene models using renormalization group
(RG) arguments and quantum Monte Carlo simulations of the Hubbard model. We
present an RG argument which predicts, contrary to previous studies, that weak
interactions do not flow to strong coupling even if the free dispersion has a
QBT. Instead they generate a linear term in the dispersion, which causes the
interactions to flow back to weak coupling. Consistent with this RG scenario,
in unbiased quantum Monte Carlo simulations of the Hubbard model we find
compelling evidence that antiferromagnetism turns on at a finite $U/t$, despite
the $U=0$ hopping problem having a QBT. The onset of antiferromagnetism takes
place at a continuous transition which is consistent with a dynamical critical
exponent $z=1$ as expected for 2+1 d Gross-Neveu criticality. We conclude that
generically in models of bilayer graphene, even if the free dispersion has a
QBT, small local interactions generate a Dirac phase with no symmetry breaking
and that there is a finite-coupling transition out of this phase to a
symmetry-broken state.


title:
Maximum Entropy Functions: Approximate Gacs-Korner for Distributed
  Compression

abstract:
  Consider two correlated sources $X$ and $Y$ generated from a joint
distribution $p_{X,Y}$. Their G\'acs-K\"orner Common Information, a measure of
common information that exploits the combinatorial structure of the
distribution $p_{X,Y}$, leads to a source decomposition that exhibits the
latent common parts in $X$ and $Y$. Using this source decomposition we
construct an efficient distributed compression scheme, which can be efficiently
used in the network setting as well. Then, we relax the combinatorial
conditions on the source distribution, which results in an efficient scheme
with a helper node, which can be thought of as a front-end cache. This
relaxation leads to an inherent trade-off between the rate of the helper and
the rate reduction at the sources, which we capture by a notion of optimal
decomposition. We formulate this as an approximate G\'acs-K\"orner
optimization. We then discuss properties of this optimization, and provide
connections with the maximal correlation coefficient, as well as an efficient
algorithm, both through the application of spectral graph theory to the induced
bipartite graph of $p_{X,Y}$.


title: Shortcut sets for the locus of plane Euclidean networks

abstract:
  We study the problem of augmenting the locus $\mathcal{N}_{\ell}$ of a plane
Euclidean network $\mathcal{N}$ by inserting iteratively a finite set of
segments, called \emph{shortcut set}, while reducing the diameter of the locus
of the resulting network. There are two main differences with the classical
augmentation problems: the endpoints of the segments are allowed to be points
of $\mathcal{N}_{\ell}$ as well as points of the previously inserted segments
(instead of only vertices of $\mathcal{N}$), and the notion of diameter is
adapted to the fact that we deal with $\mathcal{N}_{\ell}$ instead of
$\mathcal{N}$. This increases enormously the hardness of the problem but also
its possible practical applications to network design. Among other results, we
characterize the existence of shortcut sets, compute them in polynomial time,
and analyze the role of the convex hull of $\mathcal{N}_{\ell}$ when inserting
a shortcut set. Our main results prove that, while the problem of minimizing
the size of a shortcut set is NP-hard, one can always determine in polynomial
time whether inserting only one segment suffices to reduce the diameter.


title:
Planar quantum quenches: Computation of exact time-dependent correlation
  functions at large $N$

abstract:
  We study a quantum quench of an integrable quantum field theory in the planar
infinite-$N$ limit. Unlike isovector-valued $O(N)$ models, matrix-valued field
theories in the infinite-$N$ limit are not solvable by the Hartre-Fock
approximation, and are nontrivial interacting theories. We study quenches with
initial states that are color-charge neutral, correspond to
integrability-preserving boundary conditions, and that lead to nontrivial
correlation functions of operators. We compute exactly at infinite $N$, the
time-dependent one- and two-point correlation functions of the energy-momentum
tensor and renormalized field operator after this quench using known exact form
factors. This computation can be done fully analytically, due the simplicity of
the initial state and the form factors in the planar limit. We also show that
this type of quench preserves factorizability at all times, allows for particle
transmission from the pre-quench state, while still having nontrivial
interacting post-quench dynamics.


title:
Detangling People: Individuating Multiple Close People and Their Body
  Parts via Region Assembly

abstract:
  Today's person detection methods work best when people are in common upright
poses and appear reasonably well spaced out in the image. However, in many real
images, that's not what people do. People often appear quite close to each
other, e.g., with limbs linked or heads touching, and their poses are often not
pedestrian-like. We propose an approach to detangle people in multi-person
images. We formulate the task as a region assembly problem. Starting from a
large set of overlapping regions from body part semantic segmentation and
generic object proposals, our optimization approach reassembles those pieces
together into multiple person instances. It enforces that the composed body
part regions of each person instance obey constraints on relative sizes, mutual
spatial relationships, foreground coverage, and exclusive label assignments
when overlapping. Since optimal region assembly is a challenging combinatorial
problem, we present a Lagrangian relaxation method to accelerate the lower
bound estimation, thereby enabling a fast branch and bound solution for the
global optimum. As output, our method produces a pixel-level map indicating
both 1) the body part labels (arm, leg, torso, and head), and 2) which parts
belong to which individual person. Our results on three challenging datasets
show our method is robust to clutter, occlusion, and complex poses. It
outperforms a variety of competing methods, including existing detector CRF
methods and region CNN approaches. In addition, we demonstrate its impact on a
proxemics recognition task, which demands a precise representation of "whose
body part is where" in crowded images.


title: Open clusters in AurOB2

abstract:
  We study the area around the HII region Sh 2-234, including the young open
cluster Stock 8, to investigate the extent and definition of the association
Aur OB2 and the possible role of triggering in massive cluster formation. We
obtained Str\"omgren and J,H,Ks photometry for Stock 8 and Str\"omgren
photometry for two other cluster candidates in the area, which we confirm as
young open clusters and name Alicante 11 and Alicante 12. We took spectroscopy
of 33 early-type stars in the area, including the brightest cluster members. We
calculate a common distance of $2.80^{+0.27}_{-0.24}$ kpc for the three open
clusters and surrounding association. We derive an age 4-6 Ma for Stock 8, and
do not find a significantly different age for the other clusters or the
association. The star LSV +34 23, with spectral type O8 II(f), is likely the
main source of ionization of Sh 2-234. We observe an important population of
pre-main sequence stars, some of them with disks, associated with the B-type
members lying on the main-sequence. We interpret the region as an area of
recent star formation with some residual and very localized ongoing star
formation. We do not find evidence for sequential star formation on a large
scale. The classical definition of Aur OB2 has to be reconsidered, because its
two main open clusters, Stock 8 and NGC 1893, are not at the same distance.
Stock 8 is probably located in the Perseus arm, but other nearby HII regions
whose distances also place them in this arm show quite different distances and
radial velocities and, therefore, are not connected.


title: The Effect of Distortions on the Prediction of Visual Attention

abstract:
  Existing saliency models have been designed and evaluated for predicting the
saliency in distortion-free images. However, in practice, the image quality is
affected by a host of factors at several stages of the image processing
pipeline such as acquisition, compression and transmission. Several studies
have explored the effect of distortion on human visual attention; however, none
of them have considered the performance of visual saliency models in the
presence of distortion. Furthermore, given that one potential application of
visual saliency prediction is to aid pooling of objective visual quality
metrics, it is important to compare the performance of existing saliency models
on distorted images. In this paper, we evaluate several state-of-the-art visual
attention models over different databases consisting of distorted images with
various types of distortions such as blur, noise and compression with varying
levels of distortion severity. This paper also introduces new improved
performance evaluation metrics that are shown to overcome shortcomings in
existing performance metrics. We find that the performance of most models
improves with moderate and high levels of distortions as compared to the near
distortion-free case. In addition, model performance is also found to decrease
with an increase in image complexity.


title: Nevanlinna-Pick interpolation problem in the ball

abstract:
  We solve a three point Nevanlinna-Pick problem in the Euclidean ball. In
particular, we determine a class of rational functions that interpolate this
problem.


title:
Measuring Water Vapor and Ash in Volcanic Eruptions with a
  Millimeter-Wave Radar/Imager

abstract:
  Millimeter-wave remote sensing technology can significantly improve
measurements of volcanic eruptions, yielding new insights into eruption
processes and improving forecasts of drifting volcanic ash for aviation safety.
Radiometers can measure water vapor density and temperature inside eruption
clouds, improving on existing measurements with infrared cameras that are
limited to measuring the outer cloud surface. Millimeter-wave radar can measure
the 3D mass distribution of volcanic ash inside eruption plumes and their
nearby drifting ash clouds. Millimeter wavelengths are better matched to
typical ash particle sizes, offering better sensitivity than longer wavelength
existing weather radar measurements, as well as the unique ability to directly
measure ash particle size in-situ. Here we present sensitivity calculations in
the context of developing the WAMS (Water and Ash Millimeter-wave Spectrometer)
instrument. WAMS, a radar/radiometer system designed to use off-the-shelf
components, would be able to measure water vapor and ash throughout an entire
eruption cloud, a unique capability.


title:
On an equation involving fractional powers with one prime and one almost
  prime variables

abstract:
  In this paper we consider the equation $[p^{c}] + [m^{c}] = N$, where $N$ is
a sufficiently large integer, and prove that if $1 < c < \frac{29}{28}$, then
it has a solution in a prime $p$ and an almost prime $m$ with at most $\left[
\frac{52}{29 - 28 c}\right] + 1 $ prime factors.


title:
Landau-Khalatnikov-Fradkin transformations in Reduced Quantum
  Electrodynamics

abstract:
  We derive the Landau-Khalatnikov-Frandkin transformation (LKFT) for the
fermion propagator in quantum electrodynamics (QED) described within a
brane-world inspired framework where photons are allowed to move in $d_\gamma$
space-time (bulk) dimensions, while electrons remain confined to a
$d_e$-dimensional brane, with $d_e < d_\gamma$, referred to in the literature
as reduced quantum electrodynamics, RQED$_{d_\gamma,d_e}$. Specializing to the
case of graphene, namely, RQED$_{4,3}$ with massless fermions, we derive the
nonperturbative form of the fermion propagator starting from its bare
counterpart and then compare its weak coupling expansion to known one- and
two-loop perturbative results. The agreement of the gauge-dependent terms of
order $\alpha$ and $\alpha^{2}$ is reminiscent from the structure of LKFT in
ordinary QED in arbitrary space-time dimensions and provides strong constraints
for the multiplicative renormalizability of RQED$_{d_\gamma,d_e}$.


title:
Algorithms for stochastic optimization with functional or expectation
  constraints

abstract:
  This paper considers the problem of minimizing an expectation function over a
closed convex set, coupled with a {\color{black} functional or expectation}
constraint on either decision variables or problem parameters. We first present
a new stochastic approximation (SA) type algorithm, namely the cooperative SA
(CSA), to handle problems with the constraint on devision variables. We show
that this algorithm exhibits the optimal ${\cal O}(1/\epsilon^2)$ rate of
convergence, in terms of both optimality gap and constraint violation, when the
objective and constraint functions are generally convex, where $\epsilon$
denotes the optimality gap and infeasibility. Moreover, we show that this rate
of convergence can be improved to ${\cal O}(1/\epsilon)$ if the objective and
constraint functions are strongly convex. We then present a variant of CSA,
namely the cooperative stochastic parameter approximation (CSPA) algorithm, to
deal with the situation when the constraint is defined over problem parameters
and show that it exhibits similar optimal rate of convergence to CSA. It is
worth noting that CSA and CSPA are primal methods which do not require the
iterations on the dual space and/or the estimation on the size of the dual
variables. To the best of our knowledge, this is the first time that such
optimal SA methods for solving functional or expectation constrained stochastic
optimization are presented in the literature.


title:
Fundamental Limits of Coded Caching: Improved Delivery Rate-Cache
  Capacity Trade-off

abstract:
  A centralized coded caching system, consisting of a server delivering N
popular files, each of size F bits, to K users through an error-free shared
link, is considered. It is assumed that each user is equipped with a local
cache memory with capacity MF bits, and contents can be proactively cached into
these caches over a low traffic period; however, without the knowledge of the
user demands. During the peak traffic period each user requests a single file
from the server. The goal is to minimize the number of bits delivered by the
server over the shared link, known as the delivery rate, over all user demand
combinations. A novel coded caching scheme for the cache capacity of M= (N-1)/K
is proposed. It is shown that the proposed scheme achieves a smaller delivery
rate than the existing coded caching schemes in the literature when K > N >= 3.
Furthermore, we argue that the delivery rate of the proposed scheme is within a
constant multiplicative factor of 2 of the optimal delivery rate for cache
capacities 1/K <= M <= (N-1)/K, when K > N >= 3.


title:
Secure Communication through Wireless-Powered Friendly Jamming: Jointly
  Online Optimization over Geography, Energy and Time

abstract:
  Exploring the interference-emitting friendly jammers to protect the sensitive
communications in the presence of eavesdroppers has increasingly being
investigated in literature. In parallel, scavenging energy from abient radio
signals for energy-constrained devices, namely \emph{wireless energy
harvesting} (WEH), has also drawn significant attention. Without relying on
external energy supply, the wireless-powered friendly jammer by WEH from
legitimate wireless devices is an effective approach to prolong their lifetime
and gain the flexibility in deployments. This paper studies the online
optimization of the placement and WEH of a set of friendly jammers in a
geographic location with the energy-efficiency (EE) consideration. We adopt a
simple "time switching" protocol where power transfer and jammer-assisted
secure communications occur in different time blocks when WEH requests are
launched. Our scheme has the following important advantages: 1) The proposed
online jammers placement and interfering power allocation to attack
eavesdroppers is the first distributed and scalable solutions within any
specified geographic region, 2) We model the WEH for jammers as a \emph{JAM-NET
lifetime maximization problem}, where online scheduling algorithms with
heterogeneous energy demands of each jammer (from energy sources) are designed,
3) Under our model, the problem of placing a minimum number of jammers with
distance-based power assignments is NP-hard, and near optimal PTAS
approximation algorithms are provided, 4) When durations of the eavesdropping
and legitimate communicating are available and the scenario is extended to the
multi-channels setting, our results are strengthened to see further improved EE
and reduced number of jammers. Simulations back up our theory.


title: Olivier Chesneau's work on novae

abstract:
  Olivier Chesneau founded a brand new field of observational astrophysics with
his attempts to resolve the novae expanding fireball from the very first days
of the explosion. With the images he could get, he showed that novae do indeed
explode in an aspherical way, leading to a change of paradigm for the physics
of these yet-poorly understood catastrophic systems. He also set the stage for
a new way of estimating novae distances, by directly measuring the sky-size of
the fireball and comparing it with spectroscopic scales, taking into account
the tremendous effects of the fireball geometry.


title:
Embedded star formation in the extended narrow line region of Centaurus
  A: extreme mixing observed by MUSE

abstract:
  We present a detailed study of the complex ionization structure in a small
(~250 pc) extended narrow line region (ENLR) cloud near Centaurus A using the
Multi Unit Spectroscopic Explorer. This cloud is located in the so-called outer
filament of ionized gas (about 15 kpc from the nucleus) where jet-induced star
formation has been suggested to occur by different studies. We find that,
despite the small size, a mixture of ionization mechanisms is operating,
resulting in considerable complexity in the spatial ionization structure. The
area includes two H II regions where star formation is occurring and another
location where star formation must have ceased very recently. Interestingly,
the extreme Balmer decrement of one of the star forming regions
(H_alpha/H_beta~6) indicates that it is still heavily embedded in its natal
cocoon of gas and dust. At all three locations a continuum counterpart is found
with spectra matching those of O/B stars local to Centaurus A. The H II regions
are embedded in a larger gas complex which is photoionized by the radiation of
the central active galactic nucleus (AGN), but the O/B stars affect the spatial
ionization pattern in the ENLR cloud very locally. In particular, in the
surroundings of the youngest star forming region, we can isolate a tight mixing
sequence in the diagnostic diagram going from gas with ionization due to a pure
stellar continuum to gas only photoionized by the AGN. These results emphasize
the complexity and the mixture of processes occurring in star forming regions
under the influence of an AGN radiation. This is relevant for our understanding
of AGN-induced star formation suggested to occur in a number of objects,
including this region of Centaurus A. They also illustrate that these young
stars influence the gas over only a limited region.


title: Olivier Chesneau's work on massive stars

abstract:
  Olivier Chesneau challenged several fields of observational stellar
astrophysics with bright ideas and an impressive amount of work to make them
real in the span of his career, from his first paper on P Cygni in 2000, up to
his last one on V838 Mon in 2014. He was using all the so-called high-angular
resolution techniques since it helped his science to be made, namely study in
details the inner structure of the environments around stars, be it small mass
(AGBs), more massive (supergiant stars), or explosives (Novae). I will focus
here on his work on massive stars.


title: Extensions of Theories from Soft Limits

abstract:
  We study a variety of field theories with vanishing single soft limits. In
all cases, the structure of the soft limit is controlled by a larger theory,
which provides an extension of the original one by adding more fields and
interactions. Our main example is the $U(N)$ non-linear sigma model in its CHY
representation. Its extension is a theory in which the NLSM Goldstone bosons
interact with a cubic biadjoint scalar. Other theories we study and extend are
the special Galileon and Born-Infeld theory, including its maximally
supersymmetric version in four dimensions, the DBI-Volkov-Akulov theory. In all
the cases, we propose the CHY representation of the complete tree-level
S-matrix of the extended theories. In fact, CHY formulas are the key technique
for studying the single soft limit behavior of the original theories. As a
byproduct, we show that the tree-level S-matrix of the extended NLSM theory can
be constructed using a very compact BCFW-like recursion relation, where
physical poles are at most linear in the deformation parameter.


title: Observational Constraints on Neutron Star Masses and Radii

abstract:
  Precise and reliable measurements of the masses and radii of neutron stars
with a variety of masses would provide valuable guidance for improving models
of the properties of cold matter with densities above the saturation density of
nuclear matter. Several different approaches for measuring the masses and radii
of neutron stars have been tried or proposed, including analyzing the X-ray
fluxes and spectra of the emission from neutron stars in quiescent low-mass
X-ray binary systems and thermonuclear burst sources; fitting the
energy-dependent X-ray waveforms of rotation-powered millisecond pulsars, burst
oscillations with millisecond periods, and accretion-powered millisecond
pulsars; and modeling the gravitational radiation waveforms of coalescing
double neutron star and neutron star -- black hole binary systems. We describe
the strengths and weaknesses of these approaches, most of which currently have
substantial systematic errors, and discuss the prospects for decreasing the
systematic errors in each method.


title:
Dipolar Rings of Microscopic Ellipsoids: Magnetic Manipulation and Cell
  Entrapment

abstract:
  We study the formation and dynamics of dipolar rings composed by microscopic
ferromagnetic ellipsoids, which self-assemble in water by switching the
direction of the applied field. We show how to manipulate these fragile
structures and control their shape via application of external static and
oscillating magnetic fields. We introduce a theoretical framework which
describes the ring deformation under an applied field, allowing to understand
the underlying physical mechanism. Our microscopic rings are finally used to
capture, entrap and later release a biological cell via magnetic command, i.e.
performing a simple operation which can be implemented in other microfluidic
devices which make use of ferromagnetic particles.


title: Measurement of the properties of the $\Xi_b^{*0}$ baryon

abstract:
  We perform a search for near-threshold $\Xi_b^0$ resonances decaying to
$\Xi_b^- \pi^+$ in a sample of proton-proton collision data corresponding to an
integrated luminosity of 3 fb$^{-1}$ collected by the LHCb experiment. We
observe one resonant state, with the following properties:
  \begin{eqnarray*}
  m(\Xi_b^{*0}) - m(\Xi_b^-) - m(\pi^+) &=& 15.727 \pm 0.068 \, (\mathrm{stat})
\pm 0.023 \, (\mathrm{syst}) \, \mathrm{MeV}/c^2,
  \Gamma(\Xi_b^{*0}) &=& 0.90 \pm 0.16 \, (\mathrm{stat}) \pm 0.08 \,
(\mathrm{syst}) \, \mathrm{MeV}
  .
  \end{eqnarray*} This confirms the previous observation by the CMS
collaboration. The state is consistent with the $J^P=3/2^+$ $\Xi_b^{*0}$
resonance expected in the quark model. This is the most precise determination
of the mass and the first measurement of the natural width of this state. We
have also measured the ratio
  \begin{align*} \frac{\sigma(pp \to \Xi_b^{*0} X){\cal{B}}(\Xi_b^{*0} \to
\Xi_b^- \pi^+)}{\sigma(pp \to \Xi_b^- X)}
  = 0.28 \pm 0.03 \, (\mathrm{stat}) \pm 0.01 \, (\mathrm{syst}) . \end{align*}


title: Superconnections, theta series, and period domains

abstract:
  We use superconnections to define and study some natural differential forms
on period domains $\mathbb{D}$ that parametrize polarized Hodge structures of
given type on a rational quadratic vector space $V$. These forms depend on a
choice of vectors $v_1,\ldots,v_r \in V$ and have a Gaussian shape that peaks
on the locus where $v_1,\ldots,v_r$ become Hodge classes. We show that they can
be rescaled so that one can form theta series by summing over a lattice $L^r
\subset V^r$. These series define differential forms on arithmetic quotients
$\Gamma \backslash \mathbb{D}$. We compute their cohomology class explicitly in
terms of the cohomology classes of Hodge loci in $\Gamma \backslash
\mathbb{D}$. When the period domain is a hermitian symmetric domain of type IV,
we show that the components of our forms of appropriate degree recover the
forms introduced by Kudla and Millson. In particular, our results provide
another way to establish the main properties of these forms.


title:
Boundedness and exponential convergence of a chemotaxis model for tumor
  invasion

abstract:
  We revisit the following chemotaxis system modeling tumor invasion
\begin{equation*} \begin{cases} u_t=\Delta u-\nabla \cdot(u\nabla v),&
x\in\Omega, t>0,\\ v_t=\Delta v+wz,& x\in\Omega, t>0,\\ w_t=-wz,& x\in\Omega,
t>0,\\ z_t=\Delta z-z+u, & x\in\Omega, t>0,\\ \end{cases} \end{equation*} in a
smooth bounded domain $\Omega \subset \mathbb{R}^n(n\geq 1)$ with homogeneous
Neumann boundary and initial conditions. This model was recently proposed by
Fujie et al. \cite{FIY14} as a model for tumor invasion with the role of
extracellular matrix incorporated, and was analyzed by Fujie et al.
\cite{FIWY16}, showing the uniform boundedness and convergence for $n\leq 3$.
In this work, we first show that the $L^\infty$-boundedness of the system can
be reduced to the boundedness of
$\|u(\cdot,t)\|_{L^{\frac{n}{4}+\epsilon}(\Omega)}$ for some $\epsilon>0$
alone, and then, for $n\geq 4$, if the initial data
$\|u_0\|_{L^{\frac{n}{4}}}$, $\|z_0\|_{L^\frac{n}{2}}$ and $\|\nabla v_0
\|_{L^n}$ are sufficiently small, we are able to establish the
$L^\infty$-boundedness of the system. Furthermore, we show that boundedness
implies exponential convergence with explicit convergence rate, which resolves
the open problem left in \cite{FIWY16}.


title: Breaking the color-reddening degeneracy in type Ia supernovae

abstract:
  A new method to study the intrinsic color and luminosity of type Ia
supernovae (SNe Ia) is presented. A metric space built using principal
component analysis (PCA) on spectral series SNe Ia between -12.5 and +17.5 days
from B maximum is used as a set of predictors. This metric space is built to be
insensitive to reddening. Hence, it does not predict the part of color excess
due to dust-extinction. At the same time, the rich variability of SN Ia spectra
is a good predictor of a large fraction of the intrinsic color variability.
Such metric space is a good predictor of the epoch when the maximum in the B-V
color curve is reached. Multivariate Partial Least Square (PLS) regression
predicts the intrinsic B band light-curve and the intrinsic B-V color curve up
to a month after maximum. This allows to study the relation between the light
curves of SNe Ia and their spectra. The total-to-selective extinction ratio RV
in the host-galaxy of SNe Ia is found, on average, to be consistent with
typical Milky-Way values. This analysis shows the importance of collecting
spectra to study SNe Ia, even with large sample publicly available. Future
automated surveys as LSST will provide a large number of light curves. The
analysis shows that observing accompaning spectra for a significative number of
SNe will be important even in the case of "normal" SNe Ia.


title: On finite free Fisher information for eigenvectors of a modular operator

abstract:
  Suppose $M$ is a von Neumann algebra equipped with a faithful normal state
$\varphi$ and generated by a finite set $G=G^*$, $|G|\geq 2$. We show that if
$G$ consists of eigenvectors of the modular operator $\Delta_\varphi$ with
finite free Fisher information, then the centralizer $M^\varphi$ is a
$\mathrm{II}_1$ factor and $M$ is either a type $\mathrm{II}_1$ factor or a
type $\mathrm{III}_\lambda$ factor, $0<\lambda\leq 1$, depending on the
eigenvalues of $G$. Furthermore, $(M^\varphi)'\cap M=\mathbb{C}$, $M^\varphi$
does not have property $\Gamma$, and $M$ is full provided it is type
$\mathrm{III}_\lambda$, $0<\lambda<1$.


title: Single-Image Depth Perception in the Wild

abstract:
  This paper studies single-image depth perception in the wild, i.e.,
recovering depth from a single image taken in unconstrained settings. We
introduce a new dataset "Depth in the Wild" consisting of images in the wild
annotated with relative depth between pairs of random points. We also propose a
new algorithm that learns to estimate metric depth using annotations of
relative depth. Compared to the state of the art, our algorithm is simpler and
performs better. Experiments show that our algorithm, combined with existing
RGB-D data and our new relative depth annotations, significantly improves
single-image depth perception in the wild.


title:
Multi-objective Optimizations of a Normal Conducting RF Gun Based Ultra
  Fast Electron Diffraction Beamline

abstract:
  We present the results of multi-objective genetic algorithm optimizations of
a potential single shot ultra fast electron diffraction beamline utilizing a
100 MV/m 1.6 cell normal conducting rf (NCRF) gun, as well as a 9 cell 2pi/3
bunching cavity placed between two solenoids. Optimizations of the transverse
projected emittance as a function of bunch charge are presented and discussed
in terms of the scaling laws derived in the charge saturation limit.
Additionally, optimization of the transverse coherence length as a function of
final rms bunch length at the sample location have been performed for a charge
of 1e6 electrons. Analysis of the solutions is discussed, as are the effects of
disorder induced heating. In particular, for a charge of $10^6$ electrons and
final beam size greater than or equal to 25 microns, we found a relative
coherence length of 0.07, 0.1, and 0.2 nm/micron for a final bunch length of
approximately 5, 30, and 100 fs, respectively. These results demonstrate the
viability of using genetic algorithms in the design and operation of ultrafast
electron diffraction beamlines.


title:
Reducing current noise in cryogenic experiments by vacuum-insulated
  cables

abstract:
  We measure the current noise of several cryogenic cables in a pulse tube
based dilution refrigerator at frequencies between about 1~mHz and 50~kHz. We
show that vibration-induced noise can be efficiently suppressed by using
vacuum-insulated cables between room temperature and the 2nd pulse tube stage.
A noise peak below 4 fA at the 1.4~Hz operation frequency of the pulse tube,
and a white noise density of 0.44 fA/\sqrt{Hz} in the millihertz range are
obtained.


title: A global take on congestion in urban areas

abstract:
  We analyze the congestion data collected by a GPS device company (TomTom) for
almost 300 urban areas in the world. Using simple scaling arguments and data
fitting we show that congestion during peak hours in large cities grows
essentially as the square root of the population density. This result, at odds
with previous publications showing that gasoline consumption decreases with
density, confirms that density is indeed an important determinant of
congestion, but also that we need urgently a better theoretical understanding
of this phenomena. This incomplete view at the urban level leads thus to the
idea that thinking about density by itself could be very misleading in
congestion studies, and that it is probably more useful to focus on the spatial
redistribution of activities and residences.


title: The Standard Model Higgs as the origin of the hot Big Bang

abstract:
  If the Standard Model (SM) Higgs is weakly coupled to the inflationary
sector, the Higgs is expected to be universally in the form of a condensate
towards the end of inflation. The Higgs decays rapidly after inflation - via
non-perturbative effects - into an out-of-equilibrium distribution of SM
species, which thermalize soon afterwards. If the post-inflationary equation of
state of the universe is stiff, $w \simeq +1$, the SM species eventually
dominate the total energy budget. This provides a natural origin for the
relativistic thermal plasma of SM species, required for the onset of the `hot
Big Bang' era. The viability of this scenario requires the inflationary Hubble
scale $H_*$ to be lower than the instability scale for Higgs vacuum decay, the
Higgs not to generate too large curvature perturbations at cosmological scales,
and the SM dominance to occur before Big Bang Nucleosynthesis. We show that
successful reheating into the SM can only be obtained in the presence of a
non-minimal coupling to gravity $\xi \gtrsim 1$, with a reheating temperature
of $T_{\rm RH} \gtrsim \mathcal{O}(10^{10})\xi^{3/2}(H_*/10^{14}{\rm
GeV})^2~{\rm GeV}$.


title: Stochastic Perron for Stochastic Target Problems

abstract:
  In this paper, we adapt stochastic Perron's method to analyze a stochastic
target problem with unbounded controls in a jump diffusion set-up. With this
method, we construct a viscosity sub-solution and super-solution to the
associated Hamiltonian-Jacobi-Bellman (HJB) equations. Under comparison
principles, uniqueness of the viscosity solutions holds and the value function
coincides with the unique solution in the parabolic interior. Since classical
control problems can be analyzed under the framework of stochastic target
problems (with unbounded controls), we use our results to generalize the
results in ArXiv:1212.2170 to problems with controlled jumps.


title: Temperature-dependent Hysteresis in MAPbI3 Solar Cells

abstract:
  Hysteresis in the current-voltage characteristics of hybrid organic-inorganic
perovskite-based solar cells is one of the fundamental aspects of these cells
that we do not understand well. One possible cause, suggested for the
hysteresis, is polarization of the perovskite layer under applied voltage and
illumination bias, due to ion migration within the perovskite. To study this
problem systemically current-voltage characteristics of both regular (light
incident through the electron conducting contact) and so-called inverted (light
incident through the hole conducting contact) perovskite cells were studied at
different temperatures and scan rates. We explain our results by assuming that
the effects of scan rate and temperature on hysteresis are strongly correlated
to ion migration within the device, with the rate-determining step being ion
migration at/across the interfaces of the perovskite layer with the contact
materials. By correlating between the scan rate with the measurement
temperature we show that the inverted and regular cells operate in different
hysteresis regimes, with different activation energies of 0.28+-0.04 eV and
0.59+-0.09 eV, respectively. We suggest that the differences, observed between
the two architectures are due to different rates of ion migration close to the
interfaces, and conclude that the diffusion coefficient of migrating ions in
the inverted cells is 3 orders of magnitude higher than in the regular cells,
leading to different accumulation rates of ions near the interfaces. Analysis
of VOC as a function of temperature shows that the main recombination mechanism
is trap-assisted (Shockley-Read Hall, SRH) in the space charge region, similar
to what is the case for other thin film inorganic solar cells.


title: The liftable mapping class group of balanced superelliptic covers

abstract:
  The hyperelliptic mapping class group has been studied in various contexts
within topology and algebraic geometry. What makes this study tractable is that
there is a surjective map from the hyperelliptic mapping class group to a
mapping class group of a punctured sphere. The more general family of
superelliptic mapping class groups does not, in general, surject on to a
mapping class group of a punctured sphere, but on to a finite index subgroup.
We call this finite index subgroup the liftable mapping class group. In order
to initiate the generalization of results on the hyperelliptic mapping class
group to the broader family of superelliptic mapping class groups, we study an
intermediate family called the balanced superelliptic mapping class group. We
compute the index of the liftable mapping class group in the full mapping class
group of the sphere and show that the liftable mapping class group is
independent of the degree of the cover. We also build a presentation for the
liftable mapping class group, compute its abelianization, and show that the
balanced superelliptic mapping class group has finite abelianization. Although
our calculations focus on the subfamily of balanced superelliptic mapping class
groups, our techniques can be extended to any superelliptic mapping class
group, even those not within the balanced family.


title: The Euclidean distribution of Fast Radio Bursts

abstract:
  We investigate whether current data on the distribution of observed flux
densities of Fast Radio Bursts (FRBs) are consistent with a constant source
density in Euclidean space. We use the number of FRBs detected in two surveys
with different characteristics along with the observed signal-to-noise ratios
of the detected FRBs in a formalism similar to a V/V_max-test to constrain the
distribution of flux densities. We find consistency between the data and a
Euclidean distribution. Any extension of this model is therefore not
data-driven and needs to be motivated separately. As a byproduct we also obtain
new improved limits for the FRB rate at 1.4 GHz, which had not been constrained
in this way before.


title: The expected number of Z-eigenvalues of a real gaussian tensor

abstract:
  A real number $\lambda$ is called a Z-eigenvalue of a tensor $A$, if
$\lambda$ is an eigenvalue of $A$ and the corresponding eigenvector $v$ is real
and satisfies $v^Tv=1$. In this paper we compute the expected number of
Z-eigenvalues of a real gaussian tensor and its asymptotic behaviour. Here we
call a tensor $A=(A_{i_0,\ldots,i_{d}}) \in\mathbb{R}^{n^{d+1}}$ gaussian, when
the $A_{i_0,\ldots,i_{d}}$ are centered gaussian random variables with variance
$\sigma^2= 1$.


title:
The nature of composite fermions and the role of particle hole symmetry:
  A microscopic account

abstract:
  Motivated by the issue of particle-hole symmetry for the composite fermion
Fermi sea at the half filled Landau level, Dam T. Son has made an intriguing
proposal [Phys. Rev. X {\bf 5}, 031027 (2015)] that composite fermions are
Dirac particles. We ask what features of the Dirac-composite fermion theory and
its various consequences may be reconciled with the well established
microscopic theory of the fractional quantum Hall effect and the 1/2 state,
which is based on {\em non-relativistic} composite fermions. Starting from the
microscopic theory, we derive the assertion of Son that the particle-hole
transformation of electrons at filling factor $\nu=1/2$ corresponds to an
effective time reversal transformation (i.e.
$\{\vec{k}_j\}$$\rightarrow$$\{-\vec{k}_j\}$) for composite fermions, and
discuss how this connects to the absence of $2k_{\rm F}$ backscattering in the
presence of a particle-hole symmetric disorder. By considering bare holes in
various composite-fermion $\Lambda$ levels (analogs of electronic Landau
levels) we determine the $\Lambda$ level spacing and find it to be very nearly
independent of the $\Lambda$ level index, consistent with a parabolic
dispersion for the underlying composite fermions. Finally, we address the
compatibility of the Chern-Simons theory with the lowest Landau level
constraint, and find that the wave functions of the mean-field Chern-Simons
theory, as well as a class of topologically similar wave functions, are
surprisingly accurate when projected into the lowest Landau level. These
considerations lead us to introduce a "normal form" for the unprojected wave
functions of the $n/(2pn-1)$ states that correctly capture the topological
properties even without lowest Landau level projection.


title:
Inverse Reinforcement Learning with Simultaneous Estimation of Rewards
  and Dynamics

abstract:
  Inverse Reinforcement Learning (IRL) describes the problem of learning an
unknown reward function of a Markov Decision Process (MDP) from observed
behavior of an agent. Since the agent's behavior originates in its policy and
MDP policies depend on both the stochastic system dynamics as well as the
reward function, the solution of the inverse problem is significantly
influenced by both. Current IRL approaches assume that if the transition model
is unknown, additional samples from the system's dynamics are accessible, or
the observed behavior provides enough samples of the system's dynamics to solve
the inverse problem accurately. These assumptions are often not satisfied. To
overcome this, we present a gradient-based IRL approach that simultaneously
estimates the system's dynamics. By solving the combined optimization problem,
our approach takes into account the bias of the demonstrations, which stems
from the generating policy. The evaluation on a synthetic MDP and a transfer
learning task shows improvements regarding the sample efficiency as well as the
accuracy of the estimated reward functions and transition models.


title: Dynamic Approaches for Some Time Inconsistent Problems

abstract:
  In this paper we investigate possible approaches to study general
time-inconsistent optimization problems without assuming the existence of
optimal strategy. This leads immediately to the need to refine the concept of
time-consistency as well as any method that is based on Pontryagin's Maximum
Principle. The fundamental obstacle is the dilemma of having to invoke the {\it
Dynamic Programming Principle} (DPP) in a time-inconsistent setting, which is
contradictory in nature. The main contribution of this work is the introduction
of the idea of the "dynamic utility" under which the original time inconsistent
problem (under the fixed utility) becomes a time consistent one. As a benchmark
model, we shall consider a stochastic controlled problem with multidimensional
backward SDE dynamics, which covers many existing time-inconsistent problems in
the literature as special cases, and we argue that the time inconsistency is
essentially equivalent to the lack of {\it comparison principle}. We shall
propose three approaches aiming at reviving the DPP in this setting: the
duality approach, the dynamic utility approach, and the master equation
approach. Unlike the game approach in many existing works in continuous time
models, all our approaches produce the same value as the original static
problem.


title: Two photons co- and counter-propagating through $N$ cross-Kerr sites

abstract:
  A cross-Kerr interaction produces a phase shift on two modes of light
proportional to the number of photons in both modes, and is sometimes called
cross-phase modulation. Cross-Kerr nonlinearities have many applications in
classical and quantum nonlinear optics, including the possibility of a
deterministic and all-optical controlled-phase gate. We calculate the one- and
two-photon S-matrix for fields propagating in a medium where the cross-Kerr
interaction is spatially distributed at discrete interaction sites comprised of
atoms. For the interactions considered, we analyze the cases where the photons
co-propagate and counter-propagate through the medium and give a physical
interpretation to the differences between the two cases. Finally, we obtain the
S-matrix in the limit of infinitely long chains, showing that it corresponds to
a perfect controlled-phase operation.


title:
Removing Clouds and Recovering Ground Observations in Satellite Image
  Sequences via Temporally Contiguous Robust Matrix Completion

abstract:
  We consider the problem of removing and replacing clouds in satellite image
sequences, which has a wide range of applications in remote sensing. Our
approach first detects and removes the cloud-contaminated part of the image
sequences. It then recovers the missing scenes from the clean parts using the
proposed "TECROMAC" (TEmporally Contiguous RObust MAtrix Completion) objective.
The objective function balances temporal smoothness with a low rank solution
while staying close to the original observations. The matrix whose the rows are
pixels and columnsare days corresponding to the image, has low-rank because the
pixels reflect land-types such as vegetation, roads and lakes and there are
relatively few variations as a result. We provide efficient optimization
algorithms for TECROMAC, so we can exploit images containing millions of
pixels. Empirical results on real satellite image sequences, as well as
simulated data, demonstrate that our approach is able to recover underlying
images from heavily cloud-contaminated observations.


title: Room temperature Tamm-Plasmon Exciton-Polaritons with a WSe2 monolayer

abstract:
  Solid state cavity quantum electrodynamics is a rapidly advancing field which
explores the frontiers of light-matter coupling. Plasmonic approaches are of
particular interest in this field, since they carry the potential to squeeze
optical modes to spaces significantly below the diffraction limit1,2, enhancing
light-matter coupling. They further serve as an architecture to design
ultra-fast, non-linear integrated circuits with smallest footprints3.
Transition metal dichalcogenides are ideally suited as the active material in
such circuits as they interact strongly with light at the ultimate monolayer
limit4. Here, we implement a Tamm-plasmon-polariton structure, and study the
coupling to a monolayer of WSe2, hosting highly stable excitons5.
Exciton-Polariton formation at room temperature is manifested in the
characteristic energy-momentum dispersion relation studied in
photoluminescence, featuring an anti-crossing between the exciton and photon
modes with a Rabi-splitting of 23.5 meV. Creating polaritonic quasi-particles
in plasmonic architectures with atomic monolayers under ambient conditions is a
crucial step towards compact, highly non-linear integrated photonic and
polaritonic circuits6,7.


title:
Charge and spin diffusion on the metallic side of the metal-insulator
  transition: a self-consistent approach

abstract:
  We develop a self-consistent theory describing the spin and spatial electron
diffusion in the impurity band of doped semiconductors under the effect of a
weak spin-orbit coupling. The resulting low-temperature spin-relaxation time
and diffusion coefficient are calculated within different schemes of the
self-consistent framework. The simplest of these schemes qualitatively
reproduces previous phenomenological developments, while more elaborate
calculations provide corrections that approach the values obtained in numerical
simulations. The results are universal for zinc-blende semiconductors with
electron conductance in the impurity band, and thus they are able to account
for the measured spin-relaxation times of materials with very different
physical parameters. From a general point of view, our theory opens a new
perspective for describing the hopping dynamics in random quantum networks.


title:
Generalized random sequential adsorption on Erd\H{o}s-R\'enyi random
  graphs

abstract:
  We investigate Random Sequential Adsorption (RSA) on a random graph via the
following greedy algorithm: Order the $n$ vertices at random, and sequentially
declare each vertex either active or frozen, depending on some local rule in
terms of the state of the neighboring vertices. The classical RSA rule declares
a vertex active if none of its neighbors is, in which case the set of active
nodes forms an independent set of the graph. We generalize this
nearest-neighbor blocking rule in three ways and apply it to the
Erd\H{o}s-R\'enyi random graph. We consider these generalizations in the
large-graph limit $n\to\infty$ and characterize the jamming constant, the
limiting proportion of active vertices in the maximal greedy set.


title:
Study of the terahertz spectra of crystalline materials using NDDO
  semi-empirical methods: polyethylene, poly(vinylidene fluoride) form II and
  $\alpha$-D-glucose

abstract:
  Semi-empirical quantum chemistry methods offer a very interesting compromise
between accuracy and computational load. In order to assess the performance of
NDDO methods in the interpretation of terahertz spectra, the low frequency
vibration modes of three crystalline materials, namely, polyethylene,
poly(vinylidene fluoride) form II and $\alpha$-D-glucose have been studied
using the PM6 and PM7 Hamiltonians and the results have been compared with the
experimental data and former calculations. The results show good qualitative or
semi-quantitative agreement with the experimentally observed terahertz spectra.