title: Semiclassical approaches to nuclear dynamics

abstract:
  The extended Gutzwiller trajectory approach is presented for the
semiclassical description of nuclear collective dynamics, in line with the main
topics of the fruitful activity of V.G. Solovjov. Within the Fermi-liquid
droplet model, the leptodermous effective surface approximation was applied to
calculations of energies, sum rules and transition densities for the
neutron-proton asymmetry of the isovector giant-dipole resonance and found to
be in good agreement with the experimental data. By using the Strutinsky shell
correction method, the semiclassical collective transport coefficients such as
nuclear inertia, friction, stiffness, and moments of inertia can be derived
beyond the quantum perturbation approximation of the response function theory
and the cranking model.The averaged particle-number dependence of the low-lying
collective vibrational states are described in good agreement with basic
experimental data, mainly due to an enhancement of the collective inertia as
compared to its irrotational flow value. Shell components of the moment of
inertia are derived in terms of the periodic-orbit free-energy shell
corrections. A good agreement between the semiclassical extended Thomas-Fermi
moments of inertia with shell corrections and the quantum results is obtained
for different nuclear deformations and particle numbers. Shell effects are
shown to be exponentially dampted out with increasing temperature in all the
transport coefficients.


title: A Characterization of Symplectic Grassmannians

abstract:
  We provide a characterization of Symplectic Grassmannians in terms of their
Varieties of Minimal Rational Tangents.


title:
Quasinormal Modes of Asymptotically (A)dS Black Hole in Lovelock
  Background

abstract:
  We study the quasinormal modes of the massless scalar field in asymptotically
(A)dS black holes in Lovelock spacetime by using the sixth order of the WKB
approximation. We consider the effects of the second and third order of
Lovelock coupling constants on quasinormal frequencies spectrum as well as
cosmological constant.


title:
Remarks on $\tau$-functions for the difference Painlev\'e equations of
  type $E_8$

abstract:
  We investigate the structure of $\tau$-functions for the elliptic difference
Painlev\'e equation of type $E_8$. Introducing the notion of ORG
$\tau$-functions for the $E_8$ lattice, we construct some particular solutions
which are expressed in terms of elliptic hypergeometric integrals. Also, we
discuss how this construction is related to the framework of lattice
$\tau$-functions associated with the configuration of generic nine points in
the projective plane.


title:
Comparison of quantum discord and fully entangled fraction of two
  classes of $d\otimes d^2$ states

abstract:
  The quantumness of a generic state is the resource of many applications in
quantum information theory and it is interesting to survey the measures which
are able to detect its trace in the properties of the state. In this work we
study the quantum discord and fully entangled fraction of two classes of
bipartite states and compare their behaviors. These classes are complements to
the $d\otimes d$ Werner and isotropic states, in the sense that each class
possesses the same purification as the corresponding complemental class of
states. Our results show that maximally entangled mixed states are also
maximally discordant states, leading to a generalization of the well-known fact
that all maximally entangled pure states have also maximum quantum discord.
Moreover, it is shown that the separability-entanglement boundary of a Werner
or isotropic state is manifested as an inflection point in the diagram of
quantum discord of the corresponding complemental state.


title: Galactic membership of BL Her type variable stars

abstract:
  As the RR Lyrae stars evolve on the Hertzsprung-Russell diagram they are
believed to become short period Type II Cepheids, known as BL Her type (with a
pulsation period from $1$ to $3-8$ days). Assuming that their mass is around
$0.5 - 0.6 {\rm M}_{\odot}$, and that they are low metallicity objects, they
were thought to belong to the halo of the Milky Way. We investigated seven
Galactic short period Type II Cepheids (BL Her, SW Tau, V553 Cen, DQ And, BD
Cas, V383 Cyg, and KT Com) in order to establish their membership within the
Galactic structure using the kinematic approach. $Gaia$ should provide us with
more data needed to conduct the study of the whole sample.


title: Surface-wave pulse routing around sharp corners

abstract:
  The ability to perfectly guide surface electromagnetic waves around
ultra-sharp corners without back-scattering and radiation is in great demand
for various photonic and plasmonic applications. This is fundamentally
difficult to realize because of the dramatic momentum mismatch and wave nature
of radiation at the sharp corners. Here we experimentally demonstrate that a
simple photonic structure, a periodic square array of metallic cylinders
standing on a metal surface, can behaves as a surface-wave photonic crystal
with complete photonic band gap to overcome this bottleneck simply. A
line-defect waveguide can support and guide surface waves around ultra-sharp
corners without perceptible radiation and reflection, achieving almost perfect
transmission efficiency in a broad frequency range. We also demonstrate an
ideal T-shaped splitter to split input surface waves equally into two arms and
a square radiation-suppressed plasmonic open resonator with high quality
factors by simply inducing line-defects in this fully open surface-wave
photonic crystal.


title: Reflectivity properties of graphene with nonzero mass-gap parameter

abstract:
  The reflectivity properties of graphene with nonzero mass-gap parameter are
investigated in the framework of Dirac model using the polarization tensor in
(2+1)-dimensional space-time. For this purpose, a more simple explicit
representation for the polarization tensor along the real frequency axis is
found. The approximate analytic expressions for the polarization tensor and for
the reflectivities of graphene are obtained in different frequency regions at
any temperature. We show that the nonzero mass-gap parameter has a profound
effect on the reflectivity of graphene. Specifically, at zero temperature the
reflectivity of gapped graphene goes to zero with vanishing frequency. At
nonzero temperature the same reflectivities are equal to unity at zero
frequency. We also find the resonance behavior of the reflectivities of gapped
graphene at both zero and nonzero temperature at the border frequency
determined by the width of the gap. At nonzero temperature the reflectifities
of graphene drop to zero in the vicinity of some frequency smaller than the
border frequency. Our analytic results are accompanied with numerical
computations performed over a wide frequency region. The developed formalism
can be used in devising nanoscale optical detectors, optoelectronic switches
and in other optical applications of graphene.


title:
Multiple testing with optimal individual tests in Gaussian graphical
  model selection

abstract:
  Gaussian Graphical Model selection problem is considered. Concentration graph
is identified by multiple decision procedure based on individual tests. Optimal
unbiased individual tests are constructed. It is shown that optimal tests are
equivalent to sample partial correlation tests. Associated multiple decision
procedure is compared with standard procedure.


title:
Enhancing Intrinsic Stability of Hybrid Perovskite Solar Cell by Strong,
  yet Balanced, Electronic Coupling

abstract:
  In the past few years, the meteoric development of hybrid organic--inorganic
perovskite solar cells (PSC) astonished the community. The efficiency has
already reached the level needed for commercialization; however, the
instability hinders its deployment on the market. Here, we report a mechanism
to chemically stabilize PSC absorbers. We propose to replace the widely used
methylammonium cation (\ce{CH3NH3+}) by alternative molecular cations allowing
an enhanced electronic coupling between the cation and the \ce{PbI6} octahedra
while maintaining the band gap energy within the suitable range for solar
cells. The mechanism exploits establishing a balance between the
electronegativity of the materials' constituents and the resulting ionic
electrostatic interactions. The calculations demonstrate the concept of
enhancing the electronic coupling, and hence the stability, by exploring the
stabilizing features of \ce{CH3PH3+}, \ce{CH3SH2+}, and \ce{SH3+} cations,
among several other possible candidates. Chemical stability enhancement hence
results from a strong, yet balanced, electronic coupling between the cation and
the halides in the octahedron. This shall unlock the hindering instability
problem for PSCs and allow them to hit the market as a serious low-cost
competitor to silicon based solar cell technologies.


title:
Initial rigid response and softening transition of highly stretchable
  kirigami sheet materials

abstract:
  We study, experimentally and theoretically, the mechanical response of sheet
materials on which line cracks or cuts are arranged in a simple pattern. Such
sheet materials, often called kirigami (the Japanese words, kiri and gami,
stand for cut and paper, respectively), demonstrate a unique mechanical
response promising for various engineering applications such as stretchable
batteries: kirigami sheets possess a mechanical regime in which sheets are
highly stretchable and very soft compared with the original sheets without line
cracks, by virtue of out-of-plane deformation. However, this regime starts
after a transition from an initial stiff regime governed by in-plane
deformation. In other words, the softness of the kirigami structure emerges as
a result of a transition from the two-dimensional to three-dimensional
deformation, i.e., from stretching to bending. We clarify the physical origins
of the transition and mechanical regimes, which are revealed to be governed by
simple scaling laws. The results could be useful for controlling and designing
the mechanical response of sheet materials including cell sheets for medical
regeneration and relevant to the development of materials with tunable
stiffness and mechanical force sensors.

categories: cond-mat.soft cond-mat.mtrl-sci cond-mat.stat-mech nlin.AO physics.pop-ph


title: Text Flow: A Unified Text Detection System in Natural Scene Images

abstract:
  The prevalent scene text detection approach follows four sequential steps
comprising character candidate detection, false character candidate removal,
text line extraction, and text line verification. However, errors occur and
accumulate throughout each of these sequential steps which often lead to low
detection performance. To address these issues, we propose a unified scene text
detection system, namely Text Flow, by utilizing the minimum cost (min-cost)
flow network model. With character candidates detected by cascade boosting, the
min-cost flow network model integrates the last three sequential steps into a
single process which solves the error accumulation problem at both character
level and text line level effectively. The proposed technique has been tested
on three public datasets, i.e, ICDAR2011 dataset, ICDAR2013 dataset and a
multilingual dataset and it outperforms the state-of-the-art methods on all
three datasets with much higher recall and F-score. The good performance on the
multilingual dataset shows that the proposed technique can be used for the
detection of texts in different languages.


title: On the performance of optimal double circulant even codes

abstract:
  In this note, we investigate the performance of optimal double circulant even
codes which are not self-dual, as measured by the decoding error probability in
bounded distance decoding. To do this, we classify the optimal double circulant
even codes that are not self-dual which have the smallest weight distribution
for lengths up to $72$. We also give some restrictions on the weight
enumerators of (extremal) self-dual $[54,27,10]$ codes with shadows of minimum
weight $3$. Finally, we consider the performance of extremal self-dual codes of
lengths $88$ and $112$.


title:
Gas velocity patterns in simulated galaxies: Observational diagnostics
  of spiral structure theories

abstract:
  There are two theories of stellar spiral arms in isolated disc galaxies that
model stellar spiral arms with different longevities: quasi-stationary density
wave theory, which characterises spirals as rigidly rotating, long-lived
patterns (i.e. steady spirals), and dynamic spiral theory, which characterises
spirals as differentially rotating, transient, recurrent patterns (i.e. dynamic
spirals). In order to discriminate between these two spiral models
observationally, we investigated the differences between the gas velocity
patterns predicted by these two spiral models in hydrodynamic simulations. We
found that the azimuthal phases of the velocity patterns relative to the gas
density peaks (i.e. gaseous arms) differ between the two models, as do the gas
flows; nevertheless, the velocity patterns themselves are similar for both
models. Such similarity suggests that the mere existence of streaming motions
does not conclusively confirm the steady spiral model. However, we found that
the steady spiral model shows that the gaseous arms have radial streaming
motions well inside the co-rotation radius, whereas the dynamic spiral model
predicts that the gaseous arms tend to have tangential streaming motions. These
differences suggest that the gas velocity patterns around spiral arms will
enable distinction between the spiral theories.


title:
Equivalence groupoid of a class of variable coefficient Korteweg--de
  Vries equations

abstract:
  We classify the admissible transformations in a class of variable coefficient
Korteweg--de Vries equations. As a result, full description of the structure of
the equivalence groupoid of the class is given. The class under study is
partitioned into six disjoint normalized subclasses. The widest possible
equivalence group for each subclass is found which appears to be generalized
extended in five cases. Ways for improvement of transformational properties of
the subclasses are proposed using gaugings of arbitrary elements and mapping
between classes. The group classification of one of the subclasses is carried
out as an illustrative example.


title: Micro-mechanical Failure Analysis of Wet Granular Matter

abstract:
  We employ a novel fluid-particle model to study the shearing behavior of
granular soils under different saturation levels, ranging from the dry material
via the capillary bridge regime to higher saturation levels with percolating
clusters. The full complexity of possible liquid morphologies is taken into
account, implying the formation of isolated arbitrary-sized liquid clusters
with individual Laplace pressures that evolve by liquid exchange via films on
the grain surface. Liquid clusters can grow in size, shrink, merge and split,
depending on local conditions, changes of accessible liquid and the pore space
morphology determined by the granular phase. This phase is represented by a
discrete particle model based on Contact Dynamics, where capillary forces
exerted from a liquid phase add to the motion of spherical particles. We study
the macroscopic response of the system due to an external compression force at
various liquid contents with the help of triaxial shear tests. Additionally,
the change in liquid cluster distributions during the compression due to the
deformation of the pore space is evaluated close to the critical load.


title:
M(H) dependence and size distribution of SPIONs measured by atomic
  magnetometry

abstract:
  We demonstrate that the quasistatic recording of the magnetic excitation
function M(H) of superparamagnetic iron oxide magnetic nanoparticle (SPION)
suspensions by an atomic magnetometer allows a precise determination of the
sample's iron mass content mFe and the particle size distribution.


title: Stationary bubble formation and cavity collapse in wedge-shaped hoppers

abstract:
  The hourglass is one of the apparatuses familiar to everyone, but reveals
intriguing behaviors peculiar to granular materials, and many issues are
remained to be explored. In this study, we examined the dynamics of falling
sand in a special form of hourglass, i.e., a wedge-shaped hopper, when a
suspended granular layer is stabilized to a certain degree. As a result, we
found remarkably different dynamic regimes of bubbling and cavity. In the
bubbling regime, bubbles of nearly equal size are created in the sand at a
regular time interval. In the cavity regime, a cavity grows as sand beads fall
before a sudden collapse of the cavity. Bubbling found here is quite visible to
a level never discussed in the physics literature and the cavity regime is a
novel phase, which is neither continuous, intermittent nor completely blocked
phase. We elucidate the physical conditions necessary for the bubbling and
cavity regimes and develop simple theories for the regimes to successfully
explain the observed phenomena by considering the stability of a suspended
granular layer and clogging of granular flow at the outlet of the hopper. The
bubbling and cavity regimes could be useful for mixing a fluid with granular
materials.

categories: cond-mat.soft cond-mat.mtrl-sci cond-mat.stat-mech physics.geo-ph physics.pop-ph


title: Discordant voting processes on finite graphs

abstract:
  We consider an asynchronous voting process on graphs which we call discordant
voting, and which can be described as follows. Initially each vertex holds one
of two opinions, red or blue say. Neighbouring vertices with different opinions
interact pairwise. After an interaction both vertices have the same colour. The
quantity of interest is T, the time to reach consensus , i.e. the number of
interactions needed for all vertices have the same colour.
  An edge whose endpoint colours differ (i.e. one vertex is coloured red and
the other one blue) is said to be discordant. A vertex is discordant if its is
incident with a discordant edge. In discordant voting, all interactions are
based on discordant edges. Because the voting process is asynchronous there are
several ways to update the colours of the interacting vertices. Push: Pick a
random discordant vertex and push its colour to a random discordant neighbour.
Pull: Pick a random discordant vertex and pull the colour of a random
discordant neighbour. Oblivious: Pick a random endpoint of a random discordant
edge and push the colour to the other end point.
  We show that E(T), the expected time to reach consensus, depends strongly on
the underlying graph and the update rule. For connected graphs on n vertices,
and an initial half red, half blue colouring the following hold. For oblivious
voting, E(T) =n^2/4 independent of the underlying graph. For the complete graph
K_n, the push protocol has E(T)= Theta(n log(n)), whereas the pull protocol has
E(T)= Theta(2^n). For the cycle C_n all three protocols have E(T) = Theta(n^2).
For the star graph however, the pull protocol has E(T)=O(n^2), whereas the push
protocol is slower with E(T) = Theta(n^2 log(n)).
  The wide variation in E(T) for the pull protocol is to be contrasted with the
well known model of synchronous pull voting, for which E(T) = O(n) on many
classes of expanders.


title: Is the Dark Halo of the Milky Way Prolate?

abstract:
  We introduce the flattening equation, which relates the shape of the dark
halo to the angular velocity dispersions and the density of a tracer population
of stars. It assumes spherical alignment of the velocity dispersion tensor, as
seen in the data on stellar halo stars in the Milky Way. The angular anisotropy
and gradients in the angular velocity dispersions drive the solutions towards
prolateness, whilst the gradient in the stellar density is a competing effect
favouring oblateness. We provide an efficient numerical algorithm to integrate
the flattening equation. Using tests on mock data, we show that the there is a
strong degeneracy between circular speed and flattening, which can be
circumvented with informative priors. Therefore, we advocate the use of the
flattening equation to test for oblateness or prolateness, though the precise
value of the flattening $q$ can only be measured with the addition of the
radial Jeans equation. We apply the flattening equation to a sample extracted
from the Sloan Digital Sky Survey of $\sim 15000$ halo stars with full phase
space information and errors. We find that between Galactocentric radii of 5
and 10 kpc, the shape of the dark halo is prolate, whilst even mildly oblate
models are disfavoured. Strongly oblate models are ruled out. Specifically, for
a logarithmic halo model, if the asymptotic circular speed $v_0$ lies between
$210$ and 250 kms$^{-1}$, then we find the axis ratio of the equipotentials $q$
satisfies $1.5 \lesssim q \lesssim 2$.


title:
An inverse source problem for a two-parameter anomalous diffusion with
  local time datum

abstract:
  We determine the space-dependent source term for a two-parameter fractional
diffusion problem subject to nonlocal non-self-adjoint boundary conditions and
two local time-distinct datum. A bi-orthogonal pair of bases is used to
construct a series representation of the solution and the source term. The two
local time conditions spare us from measuring the fractional integral initial
conditions commonly associated with fractional derivatives. On the other hand,
they lead to delicate $2\times 2$ linear systems for the Fourier coefficients
of the source term and of the fractional integral of the solution at $t=0$. The
asymptotic behavior and estimates of the generalized Mittag-Leffler function
are used to establish the solvability of these linear systems, and to obtain
sufficient conditions for the existence of our construction. Analytical and
numerical examples are provided.


title:
Spin Hall Conductivity in the impure two-dimensional Rashba s-wave
  superconductor

abstract:
  Based on the Kubo formula approach, the spin Hall conductivity (SHC) of a
two-dimensional (2D) Rashba s-wave superconductor in the presence of
nonmagnetic impurities is calculated. We will show that by increasing the
superconducting gap, the SHC decreases monotonically to zero, while by
decreasing the concentration of impurities at zero gap, the SHC closes to the
clean limit universal value . As a function of the impurity relaxation rate at
and (is the spin-orbit coupling in unit of), we will show that in the dirty
limit () the SHC vanishes, and by increasing the relaxation time () the SHC
depends on the value of superconducting gap (), is changed from zero for full
gap to in zero gap. At low temperatures, the SHC goes to zero exponentially and
near the critical temperature depending on the concentration of the scattering
centers, the SHC will tend to the value of normal state. We will also show that
the SHC is independent of spin-orbit coupling () in the clean limit.


title: Spectral homogenization for a Robin-Neumann problem

abstract:
  We consider a Neumann-Robin spectral problem in a perforated domain $\Omeps$.
By homogenization techniques we find the suitable homogenized problem and we
discuss the asymptotics of eigenpairs, as the size of the perforation tends to
zero. Our results involve an approach based on Vi\v{s}\'ik lemma and the Mosco
convergence of eigenspaces. We prove that eigenpairs of our problem converge to
eigenpairs of the homogenized problem with rate $\sqrt{\eps}$.


title:
The Role of Vector Mesons for Emergent Scale-Chiral Symmetry in Nuclear
  Interactions

abstract:
  When a light scalar dilaton $\sigma$ and the light-quark vector mesons
$V=(\rho,\omega)$ are incorporated into an effective scale-invariant hidden
local symmetric (sHLS) Lagrangian, scale symmetry for $\sigma$ and local gauge
symmetry for $V$, both invisible in QCD in the vacuum, arise as emergent
symmetries at a density above $n_{1/2}\sim 2n_0$, a phenomenon highly relevant
for massive compact stars, hitherto unobserved in standard chiral pertubative
approaches. What takes place involves a topology change at $n_{1/2}$, and as
the density increases beyond, (1) exposes a parity doubling in the nucleon
structure, (2) triggers drastic change in the nuclear tensor force and (3)
stiffens the nuclear symmetry energy as density exceeds $n_{1/2}$. It results
from an intricate interplay between the two hidden symmetries that the $\rho$
meson moves toward the vector manifestation (VM) fixed point where
$m_\rho\rightarrow 0$ and the velocity of sound $v_s$ in the dense matter
approaches the conformal symmetry value $v_s/c=\sqrt{1/3}$, indicating a
presence of an infrared fixed point at which the dilaton mass vanishes.


title:
Phenomenological model for spectral broadening of incoherent light in
  fibers via self-phase modulation and dispersion

abstract:
  A phenomenological model for spectral broadening of incoherent light in
silica fibers via self-phase modulation and dispersion is presented, aiming at
providing a qualitative and readily accessible description of incoherent light
spectral broadening. In this model, the incoherent light is approximated by a
cosine power-modulated light with modulation parameters depending on the
coherent time and the dispersion in fibers. A simple and practical method for
spectral broadening predictions is given and demonstrated by both the
straightforward NLSE-based numerical modeling and series of experiments
including narrowband and broadband incoherent light in passive fibers and fiber
amplifiers.


title: Universal corner contributions to entanglement negativity

abstract:
  It has been realised that corners in entangling surfaces can induce new
universal contributions to the entanglement entropy and R\'enyi entropy. In
this paper we study universal corner contributions to entanglement negativity
in three- and four-dimensional CFTs using both field theory and holographic
techniques. We focus on the quantity $\chi$ defined by the ratio of the
universal part of the entanglement negativity over that of the entanglement
entropy, which may characterise the amount of distillable entanglement. We find
that for most of the examples $\chi$ takes bigger values for singular
entangling regions, which may suggest increase in distillable entanglement.
However, there also exist counterexamples where distillable entanglement
decreases for singular surfaces. We also explore the behaviour of $\chi$ as the
coupling varies and observe that for singular entangling surfaces, the amount
of distillable entanglement is mostly largest for free theories, while
counterexample exists for free Dirac fermion in three dimensions. For
holographic CFTs described by higher derivative gravity, $\chi$ may increase or
decrease, depending on the sign of the relevant parameters. Our results may
reveal a more profound connection between geometry and distillable
entanglement.


title:
On the Optimal Dividend Problem for Insurance Risk Models with
  Surplus-Dependent Premiums

abstract:
  This paper concerns an optimal dividend distribution problem for an insurance
company with surplus-dependent premium. In the absence of dividend payments,
such a risk process is a particular case of so-called piecewise deterministic
Markov processes. The control mechanism chooses the size of dividend payments.
The objective consists in maximazing the sum of the expected cumulative
discounted dividend payments received until the time of ruin and a penalty
payment at the time of ruin, which is an increasing function of the size of the
shortfall at ruin. A complete solution is presented to the corresponding
stochastic control problem. We identify the associated Hamilton-Jacobi-Bellman
equation and find necessary and sufficient conditions for optimality of a
single dividend-band strategy, in terms of particular Gerber-Shiu functions. A
number of concrete examples are analyzed.


title: Torsional Newton-Cartan geometry from Galilean gauge theory

abstract:
  Using the recently advanced Galilean gauge theory (GGT) we give a
comprehensive construction of torsional Newton Cartan geometry. The coupling of
a Galilean symmetric model with background NC geometry following GGT is
illustrated by a free nonrelativistic scalar field theory. The issue of spatial
diffeomorphisn \cite{SW, BMM3} is focussed from a new angle. The expression of
the torsionful connection is worked out which is in complete parallel with the
relativistic theory. Also smooth transition of the connection to its well known
torsionless expression is demonstrated. A complete (implicit) expression of the
torsion tensor for the Newton Cartan spacetime is provided where the first
order variables occur in a suggestive way. The well known result for the
temporal part of torsion is reproduced from our expression.


title: Gessel polynomials, rooks, and extended Linial arrangements

abstract:
  We study a family of polynomials associated with ascent-descent statistics on
labeled rooted plane k-ary trees introduced by Gessel, from a rook-theoretic
perspective. We generalize the excedance statistic on permutations to maximal
nonattacking rook placements on certain rectangular boards by decomposing them
into boards of staircase shape. We then relate the number of maximal
nonattacking rook placements on certain skew boards to the number of regions in
extended Linial arrangements by establishing a relation between the factorial
polynomial of those boards to the characteristic polynomial of extended Linial
arrangements. Furthermore, we give a combinatorial interpretation of the number
of bounded regions in extended Linial arrangements in the setting of labeled
rooted plane k-ary trees. Finally, using the work of Goldman-Joichi-White, we
identify graphs whose chromatic polynomials equal the characteristic
polynomials of extended Linial arrangements upto a straightforward
normalization.


title:
Characterization of the Spontaneous Light Emission of the PMTs used in
  the Double Chooz Experiment

abstract:
  During the commissioning of the first of the two detectors of the Double
Chooz experiment, an unexpected and dominant background caused by the emission
of light inside the optical volume has been observed. A specific study of the
ensemble of phenomena called "Light Noise" has been carried out in-situ, and in
an external laboratory, in order to characterize the signals and to identify
the possible processes underlying the effect. Some mechanisms of instrumental
noise originating from the PMTs were identified and it has been found that the
leading one arises from the light emission localized on the photomultiplier
base and produced by the combined effect of heat and high voltage across the
transparent epoxy resin covering the electric components. The correlation of
the rate and the amplitude of the signal with the temperature has been
observed. For the first detector in operation the induced background has been
mitigated using online and offline analysis selections based on timing and
light pattern of the signals, while a modification of the photomultiplier
assembly has been implemented for the second detector in order to blacken the
PMT bases.


title:
Why and How to Pay Different Attention to Phrase Alignments of Different
  Intensities

abstract:
  This work studies comparatively two typical sentence pair classification
tasks: textual entailment (TE) and answer selection (AS), observing that phrase
alignments of different intensities contribute differently in these tasks. We
address the problems of identifying phrase alignments of flexible granularity
and pooling alignments of different intensities for these tasks. Examples for
flexible granularity are alignments between two single words, between a single
word and a phrase and between a short phrase and a long phrase. By intensity we
roughly mean the degree of match, it ranges from identity over surface-form
co-occurrence, rephrasing and other semantic relatedness to unrelated words as
in lots of parenthesis text. Prior work (i) has limitations in phrase
generation and representation, or (ii) conducts alignment at word and phrase
levels by handcrafted features or (iii) utilizes a single attention mechanism
over alignment intensities without considering the characteristics of specific
tasks, which limits the system's effectiveness across tasks. We propose an
architecture based on Gated Recurrent Unit that supports (i) representation
learning of phrases of arbitrary granularity and (ii) task-specific focusing of
phrase alignments between two sentences by attention pooling. Experimental
results on TE and AS match our observation and are state-of-the-art.


title: Small Neutrino Masses: Another Anthropic principle aspect?

abstract:
  This year's Physics Nobel prize for the discovery of neutrino oscillations
which resolved the problem of the missing solar neutrinos and the atmospheric
muon neutrinos implies that at least one of the three neutrino species has a
tiny mass. The neutrino oscillations measure the mass difference squared, and
the individual neutrino masses have yet to be accurately ascertained. Particle
theory has so far not given a predictive picture for neutrino masses. Here we
propose that the anthropic principle may be relevant, as it is frequently
invoked to understand other aspects of the universe, including the precise
values of fine structure constant or nuclear coupling constant or even the
proton-electron mass ratio.


title: Fractal structure of iterative time profiles

abstract:
  The scope of the paper is the theoretical analysis of the time rate in which
a dynamical system reaches a stable stationary state or stable oscillations.
The method used for the analysis is based on the so-called iterative time
profiles, demonstrating a chaotic and fractal nature of some of the profiles.
The results were presented in the form of two and three-dimensional graphs.


title: Evidence of Online Performance Deterioration in User Sessions on Reddit

abstract:
  This article presents evidence of performance deterioration in online user
sessions quantified by studying a massive dataset containing over 55 million
comments posted on Reddit in April 2015. After segmenting the sessions (i.e.,
periods of activity without a prolonged break) depending on their intensity
(i.e., how many posts users produced during sessions), we observe a general
decrease in the quality of comments produced by users over the course of
sessions. We propose mixed-effects models that capture the impact of session
intensity on comments, including their length, quality, and the responses they
generate from the community. Our findings suggest performance deterioration:
Sessions of increasing intensity are associated with the production of shorter,
progressively less complex comments, which receive declining quality scores (as
rated by other users), and are less and less engaging (i.e., they attract fewer
responses). Our contribution evokes a connection between cognitive and
attention dynamics and the usage of online social peer production platforms,
specifically the effects of deterioration of user performance.


title:
An Experiment and Detection Scheme for Cavity-based Cold Dark Matter
  Searches

abstract:
  A resonance detection scheme and some useful ideas for cavity-based searches
of light cold dark matter particles (such as axions) are presented, as an
effort to aid in the on-going endeavors in this direction as well as for future
experiments, especially in possibly developing a table-top experiment. The
scheme is based on our idea of a resonant detector, incorporating an integrated
Tunnel Diode (TD) and a GaAs HEMT/HFET (High Electron Mobility
Transistor/Heterogenous FET) transistor amplifier, weakly coupled to a cavity
in a strong transverse magnetic field. The TD-amplifier combination is
suggested as a sensitive and simple technique to facilitate resonance detection
within the cavity while maintaining excellent noise performance, whereas our
proposed Halbach magnet array could serve as a low-noise and permanent solution
replacing the conventional electromagnets scheme. We present some preliminary
test results which demonstrate resonance detection from simulated test signals
in a small optimal axion mass range with superior Signal-to-Noise Ratios (SNR).
Our suggested design also contains an overview of a simpler on-resonance dc
signal read-out scheme replacing the complicated heterodyne readout. We believe
that all these factors and our propositions could possibly improve or at least
simplify the resonance detection and read-out in cavity-based DM particle
detection searches (and other spectroscopy applications) and reduce the
complications (and associated costs), in addition to reducing the
electromagnetic interference and background.


title: Algebraic semantics for hybrid logics

abstract:
  We introduce hybrid algebras as algebraic semantics for hybrid languages with
nominals and, possibly, the satisfaction operator. We establish a duality
between hybrid algebras and the descriptive two-sorted general frames of Ten
Cate. We show that all axiomatic extensions of the basic hybrid logics, with or
without the satisfaction operator, are complete with respect to their classes
of hybrid algebras. Moreover, we show that by adding the usual non-orthodox
rules to these logics, they become complete with respect to their classes of
permeated hybrid algebras, corresponding to strongly descriptive two-sorted
general frames.


title:
Observations of the Quadrantid meteor shower from 2008 to 2012: orbits
  and emission spectra

abstract:
  The activity of the Quadrantids in January during several years (2008, 2010,
2011 and 2012) has been investigated in the framework of the SPanish Meteor
Network (SPMN). For this purpose, an array of high-sensitivity CCD video
devices and CCD all-sky cameras have been used to obtain multi-station
observations of these meteors. These allowed us to obtain precise radiant and
orbital information about this meteoroid stream. This paper presents a large
set of orbital data (namely, 85 orbits) of Quadrantid meteoroids. Most meteors
produced by these particles were recorded during the activity peak of this
shower. Besides, we discuss four Quadrantid emission spectra. The tensile
strength of Quadrantid meteoroids has been also obtained.


title: Golomb's conjecture on prime gaps

abstract:
  Question 10208b (1992) of the American Mathematical Monthly asked: does there
exist an increasing sequence $\{a_k\}$ of positive integers and a constant $B >
0$ having the property that $\{ a_k + n\}$ contains no more than $B$ primes for
every integer $n$? A positive answer to this question became known as Golomb's
conjecture. In this note we give a negative answer, making use of recent
progress in prime number theory.


title:
Dynamics of Zonal Flows: Failure of Wave-Kinetic Theory, and New
  Geometrical Optics Approximations

abstract:
  The self-organization of turbulence into regular zonal flows can be
fruitfully investigated with quasilinear methods and statistical descriptions.
A wave kinetic equation that assumes asymptotically large-scale zonal flows is
pathological. From an exact description of quasilinear dynamics emerges two
better geometrical optics approximations. These involve not only the mean flow
shear but also the second and third derivative of the mean flow. One
approximation takes the form of a new wave kinetic equation, but is only valid
when the zonal flow is quasi-static and wave action is conserved.


title:
A functorial extension of the Magnus representation to the category of
  three-dimensional cobordisms

abstract:
  Let $R$ be an integral domain and $G$ be a subgroup of its group of units. We
consider the category $\mathbf{\mathsf{Cob}}_G$ of 3-dimensional cobordisms
between oriented surfaces with connected boundary, equipped with a
representation of their fundamental group in $G$. Under some mild conditions on
$R$, we construct a monoidal functor from $\mathbf{\mathsf{Cob}}_G$ to the
category $\mathbf{\mathsf{pLagr}}_R$ consisting of "pointed Lagrangian
relations" between skew-Hermitian $R$-modules. We call it the "Magnus functor"
since it contains the Magnus representation of mapping class groups as a
special case. Our construction is inspired from the work of Cimasoni and Turaev
on the extension of the Burau representation of braid groups to the category of
tangles. It can also be regarded as a $G$-equivariant version of a TQFT-like
functor that has been described by Donaldson. The study and computation of the
Magnus functor is carried out using classical techniques of low-dimensional
topology. When $G$ is a free abelian group and $R = Z[G]$ is the group ring of
$G$, we relate the Magnus functor to the "Alexander functor" (which has been
introduced in a prior work using Alexander-type invariants), and we deduce a
factorization formula for the latter.


title: Non-Central Multivariate Chi-Square and Gamma Distributions

abstract:
  A (p-1)-variate integral representation is given for the cumulative
distribution function of the general p-variate non-central gamma distribution
with a non-centrality matrix of any admissible rank. The real part of products
of well known analytical functions is integrated over arguments from (-pi,pi).
To facilitate the computation, these formulas are given more detailed for p=2
and p=3. These (p-1)-variate integrals are also derived for the diagonal of a
non-central complex Wishart Matrix. Furthermore, some alternative formulas are
given for the cases with an associated "one-factorial" (pxp)-correlation matrix
R, i.e. R differs from a suitable diagonal matrix only by a matrix of rank 1,
which holds in particular for all (3x3)-R with no vanishing correlation.


title: Injective Presentations of Induced Modules over Cluster-Tilted Algebras

abstract:
  Every cluster-tilted algebra $B$ is the relation extension $C\ltimes
\text{Ext}^2_C(DC,C)$ of a tilted algebra $C$. A $B$-module is called induced
if it is of the form $M\otimes_C B$ for some $C$-module $M$. We study the
relation between the injective presentations of a $C$-module and the injective
presentations of the induced $B$-module. Our main result is an explicit
construction of the modules and morphisms in an injective presentation of any
induced $B$-module. In the case where the $C$-module, and hence the $B$-module,
is projective, our construction yields an injective resolution. In particular,
it gives a module theoretic proof of the well-known 1-Gorenstein property of
cluster-tilted algebras.


title: Dark Energy and Dark Matter from an additional adiabatic fluid

abstract:
  The Dark Sector is described by an additional barotropic fluid which evolves
adiabatically during the universe's history and whose adiabatic exponent
$\gamma$ is derived from the standard definitions of specific heats. Although
in general $\gamma$ is a function of the redshift, the Hubble parameter and its
derivatives, we find that our assumptions lead necessarily to solutions with
$\gamma = $ constant in a FLRW universe. The adiabatic fluid acts effectively
as the sum of two distinct components, one evolving like non-relativistic
matter and the other depending on the value of the adiabatic index. This makes
the model particularly interesting as a way of simultaneously explaining the
nature of both Dark Energy and Dark Matter, at least at the level of the
background cosmology. The $\Lambda$CDM model is included in this family of
theories when $\gamma = 0$. We fit our model to SNIa, $H(z)$ and BAO data,
discussing the model selection criteria. The implications for the
early-universe and the growth of small perturbations in this model are also
discussed.


title: Fidelity Susceptibility as Holographic PV-Criticality

abstract:
  It is well known that entropy can be used to holographically establish a
connection between geometry, thermodynamics and information theory. In this
paper, we will use complexity to holographically establish a connection between
geometry, thermodynamics and information theory. Thus, we will analyse the
relation between holographic complexity, fidelity susceptibility, and
thermodynamics in extended phase space. We will demonstrate that fidelity
susceptibility (which is the informational complexity dual to a maximum volume
in AdS) can be related to the thermodynamical volume (which is conjugate to the
cosmological constant in the extended thermodynamic phase space). Thus, this
letter establishes a relation between geometry, thermodynamics, and information
theory, using complexity.


title: q-Gamow States for intermediate energies

abstract:
  In a recent paper [Nuc. Phys. A {\bf 948}, (2016) 19] we have demonstrated
the possible existence of Tsallis' q-Gamow states. Now, accelerators'
experimental evidence for Tsallis' distributions has been ascertained only at
very high energies. Here, instead, we develop a different set of q-Gamow states
for which the associated q-Breit-Wigner distribution could easily be found at
intermediate energies, for which accelerators are available at many locations.
In this context, it should be strongly emphasized [Physica A {\bf 388} (2009)
601] that, empirically, one never exactly and unambiguously "detects" pure
Gaussians, but rather q-Gaussians. A prediction is made via Eq.(3.30)

categories: cond-mat.stat-mech math-ph math.MP nucl-th quant-ph


title: Jordan counterparts of Rickart and Baer $*$-algebras

abstract:
  There are Jordan analogues of annihilators in Jordan algebras which are
called Jordan annihilators. The present paper is devoted to investigation of
those Jordan algebras every Jordan annihilator of which is generated by an
idempotent as an inner ideal. We prove that a finite dimensional unital Jordan
algebra satisfies this condition if and only if it has no nilpotent elements,
and in this case it is a direct sum of simple Jordan algebras.


title:
Non-triviality Conditions for Integer-valued Polynomial Rings on
  Algebras

abstract:
  Let $D$ be a commutative domain with field of fractions $K$ and let $A$ be a
torsion-free $D$-algebra such that $A \cap K = D$. The ring of integer-valued
polynomials on $A$ with coefficients in $K$ is ${\rm Int}_K(A) = \{f \in K[X]
\mid f(A) \subseteq A\}$, which generalizes the classic ring ${\rm Int}(D) =
\{f \in K[X] \mid f(D) \subseteq D\}$ of integer-valued polynomials on $D$.
  The condition on $A \cap K$ implies that $D[X] \subseteq {\rm Int}_K(A)
\subseteq {\rm Int}(D)$, and we say that ${\rm Int}_K(A)$ is nontrivial if
${\rm Int}_K(A) \ne D[X]$. For any integral domain $D$, we prove that if $A$ is
finitely generated as a $D$-module, then ${\rm Int}_K(A)$ is nontrivial if and
only if ${\rm Int}(D)$ is nontrivial. When $A$ is not necessarily finitely
generated but $D$ is Dedekind, we provide necessary and sufficient conditions
for ${\rm Int}_K(A)$ to be nontrivial. These conditions also allow us to prove
that, for $D$ Dedekind, the domain ${\rm Int}_K(A)$ has Krull dimension 2.


title: Jordan counterparts of Rickart and Baer $*$-algebras, II

abstract:
  We introduce and investigate new classes of Jordan algebras which are close
to but wider than Rickart and Baer Jordan algebras considered in our previous
paper. Such Jordan algebras are called RJ- and BJ-algebras respectively.
Criterions are given for a Jordan algebra to be a BJ-algebra. Also, it is
proved that every finite dimensional Jordan algebra without nilpotent elements,
which have square roots, is a BJ-algebra.


title:
A Hodge theoretic criterion for finite Weil--Petersson degenerations
  over a higher dimensional base

abstract:
  We give a Hodge-theoretic criterion for a Calabi--Yau variety to have finite
Weil--Petersson distance on higher dimensional bases up to a set of codimension
$\geq 2$. The main tool is variation of Hodge structures and variation of mixed
Hodge structures.
  We also give a description on the codimension 2 locus for the moduli space of
Calabi--Yau threefolds. We prove that the points lying on exactly one finite
and one infinite divisor have infinite Weil--Petersson distance along angular
slices. Finally, by giving a classification of the dominant term of the
candidates of the Weil--Petersson potential, we prove that the points on the
intersection of exact two infinite divisors have infinite distance measured by
the metric induced from the dominant terms of the candidates of the
Weil--Petersson potential.


title:
On the Sample Complexity of End-to-end Training vs. Semantic Abstraction
  Training

abstract:
  We compare the end-to-end training approach to a modular approach in which a
system is decomposed into semantically meaningful components. We focus on the
sample complexity aspect, in the regime where an extremely high accuracy is
necessary, as is the case in autonomous driving applications. We demonstrate
cases in which the number of training examples required by the end-to-end
approach is exponentially larger than the number of examples required by the
semantic abstraction approach.


title: Fermi's golden rule: its derivation and breakdown by an ideal model

abstract:
  Fermi's golden rule is of great importance in quantum dynamics. However, in
many textbooks on quantum mechanics, its contents and limitations are obscured
by the approximations and arguments in the derivation, which are inevitable
because of the generic setting considered. Here we propose to introduce it by
an ideal model, in which the quasi-continuum band consists of equaldistant
levels extending from $-\infty $ to $+\infty $, and each of them couples to the
discrete level with the same strength. For this model, the transition
probability in the first order perturbation approximation can be calculated
analytically by invoking the Poisson summation formula. It turns out to be a
\emph{piecewise linear} function of time, demonstrating on one hand the key
features of Fermi's golden rule, and on the other hand that the rule breaks
down beyond the \emph{Heisenberg time}, even when the first order perturbation
approximation itself is still valid.


title: Concurrent Credit Portfolio Losses

abstract:
  We consider the problem of concurrent portfolio losses in two non-overlapping
credit portfolios. In order to explore the full statistical dependence
structure of such portfolio losses, we estimate their empirical pairwise
copulas. Instead of a Gaussian dependence, we typically find a strong asymmetry
in the copulas. Concurrent large portfolio losses are much more likely than
small ones. Studying the dependences of these losses as a function of portfolio
size, we moreover reveal that not only large portfolios of thousands of
contracts, but also medium-sized and small ones with only a few dozens of
contracts exhibit notable portfolio loss correlations. Anticipated
idiosyncratic effects turn out to be negligible. These are troublesome insights
not only for investors in structured fixed-income products, but particularly
for the stability of the financial sector.


title: Graph Balancing with Two Edge Types

abstract:
  In the graph balancing problem the goal is to orient a weighted undirected
graph to minimize the maximum weighted in-degree. This special case of makespan
minimization is NP-hard to approximate to a factor better than 3/2 even when
there are only two types of edge weights. In this note we describe a simple 3/2
approximation for the graph balancing problem with two-edge types, settling
this very special case of makespan minimization.


title: Upper bounds on the slope of certain fibered surfaces

abstract:
  We establish the slope equality and give an upper bound of the slope for
finite cyclic covering fibrations of an elliptic surface including bielliptic
fibrations of genus greater than 5. We also give an upper bound of the slope
for triple cyclic covering fibrations of a ruled surface and hyperelliptic
fibrations, which provides a new proof of Xiao's upper bound.


title:
Influence of counter-rotating interaction on quantum phase transition in
  Dicke-Hubbard lattice: an extended coherent state approach

abstract:
  We investigate the ground state behavior of the Dicke-Hubbard model including
counter-rotating-terms. By generalizing an extended coherent state approach
within mean-field theory, we self-consistently obtain the ground state energy
and delocalized order parameter. Localization-delocalization quantum phase
transition of photons is clearly observed by breaking the parity symmetry.
Particularly, Mott lobes are fully suppressed, and the delocalized order
parameter shows monotonic enhancement by increasing qubit-cavity coupling
strength, in sharp contrast to the Dicke-Hubbard model under rotating-wave
approximation. Moreover, the corresponding phase boundaries are stabilized by
decreasing photon hopping strength, compared to the Rabi-Hubbard model.


title: The Intragroup versus the Intracluster Medium

abstract:
  Galaxy groups differ from clusters primarily by way of their lower masses,
M~10^14 M_sun vs. M~10^15 M_sun. We discuss how mass affects the thermal state
of the intracluster or the intragroup medium, specifically as to their entropy
levels and radial profiles. We show that entropy is produced in both cases by
the continuing inflow of intergalactic gas across the system boundary into the
gravitational potential well. The inflow is highly supersonic in clusters, but
weakly so in groups. The former condition implies strong accretion shocks with
substantial conversion of a large inflow kinetic into thermal energy, whereas
the latter condition implies less effective conversion of lower energies. These
features produce a conspicuous difference in entropy deposition at the current
boundary. Thereafter, adiabatic compression of the hot gas into the potential
well converts such time histories into radial profiles throughout a cluster or
a group. In addition, in both cases a location of the system at low z in the
accelerating universe or in a poor environment will starve out the inflow and
the entropy production, and produce flattening or even bending down of the
outer profile. We analyze in detail the sharp evidence provided by the two
groups ESO 3060170 and RXJ1159+5531 that have been recently observed in X rays
out to their virial radii, and find a close and detailed match with our
expectations.


title:
Modelling the Structure of a Protein Domain (N-terminal of XPB) Linked
  with Protein Synthesis, DNA Damage Repair, Rare Diseases, Cancer
  Therapeutics, and Tuberculosis

abstract:
  In this work, we develop first near-complete 3D models for NTD-hXPB - the
N-terminal protein domain of the human transcription factor XPB. The results
are very significant as NTD-hXPB plays a critical role in the synthesis of
proteins (specifically transcription) and DNA damage repair (specifically
nucleotide excision repair). NTD-hXPB is directly implicated in rare diseases
XP-B, XP-CS, and TTD2, whose symptoms include neurodegenerative disorders,
premature aging, and decreased fertility. NTDhXPB is also linked to anti-cancer
therapies. As a bi-product we derived 3D models of NTD-mXPB - homologue of
NTD-hXPB in mycobacterium tuberculosis aka MTB (causative agent of most cases
of tuberculosis, which surpassed HIV as #1 infectious disease killer in 2014).
These could be potential target for TB therapeutics. Our ab-initio modelling
protocol takes advantage of recent powerful advances (prediction of contact
residues) in protein structure modeling. Our protocol also includes human in
the loop, inspired by the prevailing theory that computational abilities of
human minds can be powerfully harnessed in engineering/problem-solving. Using
the developed models in this paper, we are able to propose significant insights
into (a) the role of NTD-hXPB in the process of transcription and DNA damage
repair (specifically NER), (b) the critical interactions of NTD-hXPB with
another co-labourer protein p52, (c) diseases associated with NTD-hXPB, and (d)
alterations in functionalities between NTD-hXPB (in human) and NTD-mXPB (in TB
pathogen).


title:
Any admissible harmonic Ritz value set is possible for prescribed GMRES
  residual norms

abstract:
  We show that any admissible harmonic Ritz value set is possible for
prescribed GMRES residual norms, which is a complement for the results in
[Duintjer Tebbens and Meurant, {\it SIAM J. Matrix Anal. Appl.}, 33 (2012), no.
3, pp. 958--978].


title:
Existence and smoothness of the stable foliation for sectional
  hyperbolic attractors

abstract:
  We prove the existence of a contracting invariant topological foliation in a
full neighborhood for partially hyperbolic attractors. Under certain bunching
conditions it can then be shown that this stable foliation is smooth.
Specialising to sectional hyperbolic attractors, we give a verifiable condition
for bunching. In particular, we show that the stable foliation for the
classical Lorenz equation (and nearby vector fields) is better than $C^1$ which
is crucial for recent results on exponential decay of correlations. In fact the
foliation is at least $C^{1.278}$.


title:
Interplay between anisotropy and spatial dispersion in metamaterial
  waveguide

abstract:
  We analyze spectrum of waveguide modes of an arbitrary uniaxial anisotropic
metamaterial slab with non-local electromagnetic response whose permittivity
tensor could be described within Drude approximation. Spatial dispersion was
introduced within the hydrodynamical model. Both anisotropy and spatial
dispersion were considered as perturbations. This helps to distinguish their
effect on the spectrum of the slab and to analyze lifting of the degeneracy of
eigenmodes at plasma frequency in detail. Spatial dispersion is shown to result
in break of the singularity in the den- sity of optical states in the
hyperbolic regime and in suppression of negative dispersion induced by
anisotropy. Mutual effect of spatial dispersion and anisotropy can bring light
to a complete stop at certain frequencies.


title:
A numerical study of the transition to oscillatory flow in 3D lid-driven
  cubic cavity flows

abstract:
  In this article, three dimensional (3D) lid-driven cubic cavity flows have
been studied numerically for various values of Reynolds number ($Re$). The
numerical solution of the Navier-Stokes equations modeling incompressible
viscous fluid flow in a cubic cavity is obtained via a methodology combining a
first order accurate operator-splitting, $L^2$-projection Stokes solver, a
wave-like equation treatment of the advection and finite element methods. The
numerical results obtained for Re$=$400, 1000, and 3200 show a good agreement
with available numerical and experimental results in literature. Simulation
results predict that the critical Re$_{cr}$ for the transition from steady flow
to oscillatory (a Hopf bifurcation) is somewhere in [1870, 1875] for the mesh
size $h=1/96$. Via studying the flow field distortion of fluid flow at Re
before and after Re$_{cr}$, the occurrence of the first pair of
Taylor-G\"ortler-like vortices is connected to the flow field distortion at the
transition from steady flow to oscillatory flow in 3D lid-driven cubic cavity
flows for Re $< 2000$.


title: Bars and spheroids in gravimetry problem

abstract:
  The direct gravimetry problem is solved by dividing each deposit body into a
set of vertical adjoining bars, whereas in the inverse problem, each deposit
body is modelled by a homogeneous ellipsoid of revolution (spheroid).
Well-known formulae for the z-component of gravitational intensity for a
spheroid are transformed to a convenient form. Parameters of a spheroid are
determined by minimizing the Tikhonov smoothing functional with constraints on
the parameters, which makes the ill-posed inverse problem by unique and stable.
The Bulakh algorithm for initial estimating the depth and mass of a deposit is
modified. The proposed technique is illustrated by numerical model examples of
deposits in the form of two and five bodies. The inverse gravimetry problem is
interpreted as a gravitational tomography problem or, in other words, as
"introscopy" of Earth's crust and mantle.


title: Beyond the diffraction limit via optical amplification

abstract:
  In a previous article we suggested a method to overcome the diffraction limit
behind a telescope. We refer to theory and recent numerical simulations, and
test whether it is indeed possible to use photon amplification to enhance the
angular resolution of a telescope or a microscope beyond the diffraction limit.
An essential addition is the proposal to select events with above-average ratio
of stimulated to spontaneous photons. We find that the diffraction limit of a
telescope is surpassed by a factor ten for an amplifier gain of 200, if the
analysis is restricted to a tenth of the incoming astronomical photons. A gain
of 70 is sufficient with a hundredth of the photons.


title: Memory and Information Processing in Recurrent Neural Networks

abstract:
  Recurrent neural networks (RNN) are simple dynamical systems whose
computational power has been attributed to their short-term memory. Short-term
memory of RNNs has been previously studied analytically only for the case of
orthogonal networks, and only under annealed approximation, and uncorrelated
input. Here for the first time, we present an exact solution to the memory
capacity and the task-solving performance as a function of the structure of a
given network instance, enabling direct determination of the
function--structure relation in RNNs. We calculate the memory capacity for
arbitrary networks with exponentially correlated input and further related it
to the performance of the system on signal processing tasks in a supervised
learning setup. We compute the expected error and the worst-case error bound as
a function of the spectra of the network and the correlation structure of its
inputs and outputs. Our results give an explanation for learning and
generalization of task solving using short-term memory, which is crucial for
building alternative computer architectures using physical phenomena based on
the short-term memory principle.


title: Three stage towers of 5-class fields

abstract:
  With K=Q((3812377)^(1/2)) we give the first example of an algebraic number
field possessing a 5-class tower of exact length L(5,K)=3. The rigorous proof
is conducted by means of the p-group generation algorithm, showing the
existence of a unique finite metabelian 5-group G with abelianization [5,5]
having the kernels (M(1),G^5) and targets ([25,5,5,5],[5,5]^5) of Artin
transfers T(i):G-->M(i)/M(i)' to its six maximal subgroups M(i), prescribed by
arithmetical invariants of K. Thus, G must be the second 5-class group G(5,2,K)
of the real quadratic field K but cannot be its 5-class tower group G(5,K),
since the relation rank d(2,G)=4 is too big. We provide evidence of exactly
five non-isomorphic extensions H of G having the required relation rank
d(2,H)=3 and derived length dl(H)=3 whose metabelianization H/H'' is isomorphic
to G. Consequently, G(5,K) must be one of the five non-metabelian groups H.


title: Counting faces of graphical zonotopes

abstract:
  It is a classical fact that the number of vertices of the graphical zonotope
$Z_\Gamma$ is equal to the number of acyclic orientations of a graph $\Gamma$.
We show that the $f$-polynomial of $Z_\Gamma$ is obtained as the principal
specialization of the $q$-analog of the chromatic symmetric function of
$\Gamma$.


title: Bounce and cyclic cosmology in weakly broken galileon theories

abstract:
  We investigate the bounce and cyclicity realization in the framework of
weakly broken galileon theories. We study bouncing and cyclic solutions at the
background level, reconstructing the potential and the galileon functions that
can give rise to a given scale factor, and presenting analytical expressions
for the bounce requirements. We proceed to a detailed investigation of the
perturbations, which after crossing the bouncing point give rise to various
observables, such as the scalar and tensor spectral indices and the
tensor-to-scalar ratio. Although the scenario at hand shares the disadvantage
of all bouncing models, namely that it provides a large tensor-to-scalar ratio,
introducing an additional light scalar significantly reduces it through the
kinetic amplification of the isocurvature fluctuations.


title:
The discrete sign problem: uniqueness, recovery algorithms and phase
  retrieval applications

abstract:
  In this paper we consider the following real-valued and finite dimensional
specific instance of the 1-D classical phase retrieval problem. Let ${\bf
F}\in\mathbb{R}^N$ be an $N$-dimensional vector, whose discrete Fourier
transform has a compact support. The sign problem is to recover ${\bf F}$ from
its magnitude $|{\bf F}|$. First, in contrast to the classical 1-D phase
problem which in general has multiple solutions, we prove that with sufficient
over-sampling, the sign problem admits a unique solution. Next, we show that
the sign problem can be viewed as a special case of a more general piecewise
constant phase problem. Relying on this result, we derive a computationally
efficient and robust to noise sign recovery algorithm. In the noise-free case
and with a sufficiently high sampling rate, our algorithm is guaranteed to
recover the true sign pattern. Finally, we present two phase retrieval
applications of the sign problem: (i) vectorial phase retrieval with three
measurement vectors; and (ii) recovery of two well separated 1-D objects.


title: Sum rules and large deviations for spectral measures on the unit circle

abstract:
  This work is a companion paper of Gamboa, Nagel, Rouault (J. Funct. Anal.
2016). We continue to explore the connections between large deviations for
random objects issued from random matrix theory and sum rules. Here, we are
concerned essentially with measures on the unit circle whose support is an arc
that is possibly proper. We particularly focus on two matrix models. The first
one is the Gross-Witten ensemble. In the gapped regime we give a probabilistic
interpretation of a Simon sum rule. The second matrix model is the Hua-Pickrell
ensemble. Unlike the Gross-Witten ensemble the potential is here infinite at
one point. Surprisingly, but as in the above mentioned paper, we obtain a
completely new sum rule for the deviation to the equilibrium measure of the
Hua-Pickrell ensemble. The extension to matrix measures is also studied.


title: On Hurwitz--Severi numbers

abstract:
  For a point $p\in CP^2$ and a triple $(g,d,\ell)$ of non-negative integers we
define a {\em Hurwitz--Severi number} ${\mathfrak H}_{g,d,\ell}$ as the number
of generic irreducible plane curves of genus $g$ and degree $d+\ell$ having an
$\ell$-fold node at $p$ and at most ordinary nodes as singularities at the
other points, such that the projection of the curve from $p$ has a prescribed
set of local and remote tangents and lines passing through nodes. In the cases
$d+\ell\ge g+2$ and $d+2\ell \ge g+2 > d+\ell$ we express the Hurwitz--Severi
numbers via appropriate ordinary Hurwitz numbers. The remaining case
$d+2\ell<g+2$ is still widely open.


title: Syntactic complexity of bifix-free languages

abstract:
  We study the properties of syntactic monoids of bifix-free regular languages.
In particular, we solve an open problem concerning syntactic complexity: We
prove that the cardinality of the syntactic semigroup of a bifix-free language
with state complexity $n$ is at most $(n-1)^{n-3}+(n-2)^{n-3}+(n-3)2^{n-3}$ for
$n\ge 6$. The main proof uses a large construction with the method of injective
function. Since this bound is known to be reachable, and the values for $n \le
5$ are known, this completely settles the problem. We also prove that
$(n-2)^{n-3} + (n-3)2^{n-3} - 1$ is the minimal size of the alphabet required
to meet the bound for $n \ge 6$. Finally, we show that the largest transition
semigroups of minimal DFAs which recognize bifix-free languages are unique up
to renaming the states.


title: Stretching magnetism with an electric field in a nitride semiconductor

abstract:
  By direct magnetization measurements, performed employing a new detection
scheme, we demonstrate an electrical control of magnetization in wurtzite
(Ga,Mn)N. In this dilute magnetic insulator the Fermi energy is pinned by Mn
ions in the mid-gap region, and the Mn3+ ions show strong single-ion
anisotropy. We establish that (Ga,Mn)N sustains an electric field up to at
least 5 MV/cm, indicating that Mn doping turns GaN into a worthwhile
semi-insulating material. Under these conditions, the magnetoelectric coupling
may be driven by the inverse piezoelectric effect that stretches the elementary
cell along the c axis and, thus, affects the magnitude of magnetic anisotropy.
We develop a corresponding theory and show that it describes the experimentally
determined dependence of magnetization on the electric field quantitatively
with no adjustable parameters as a function of the magnetic field and
temperature. In this way, our work bridges two research domains developed so
far independently: piezoelectricity of wurtzite semiconductors and electrical
control of magnetization in hybrid and composite magnetic structures containing
piezoelectric components.


title:
Indirect reciprocity can overcome free-rider problems on costly moral
  assessment

abstract:
  Indirect reciprocity is one of the major mechanisms of the evolution of
cooperation. Because constant monitoring and accurate evaluation in moral
assessments tend to be costly, indirect reciprocity can be exploited by cost
evaders. A recent study crucially showed that a cooperative state achieved by
indirect reciprocators is easily destabilized by cost evaders in the case with
no supportive mechanism. Here, we present a simple and widely applicable
solution that considers pre-assessment of cost evaders. In the pre-assessment,
those who fail to pay for costly assessment systems are assigned a nasty image
that leads to being rejected by discriminators. We demonstrate that considering
the pre-assessment can crucially stabilize reciprocal cooperation for a broad
range of indirect reciprocity models. In particular for the most leading social
norms we analyse the conditions under which a prosocial state becomes locally
stable.


title:
An information theoretic formulation of the Dictionary Learning and
  Sparse Coding Problems on Statistical Manifolds

abstract:
  In this work, we propose a novel information theoretic framework for
dictionary learning (DL) and sparse coding (SC) on a statistical manifold (the
manifold of probability distributions). Unlike the traditional DL and SC
framework, our new formulation {\it does not explicitly incorporate any
sparsity inducing norm in the cost function but yet yields SCs}. Moreover, we
extend this framework to the manifold of symmetric positive definite matrices,
$\mathcal{P}_n$. Our algorithm approximates the data points, which are
probability distributions, by the weighted Kullback-Leibeler center (KL-center)
of the dictionary atoms. The KL-center is the minimizer of the maximum
KL-divergence between the unknown center and members of the set whose center is
being sought. Further, {\it we proved that this KL-center is a sparse
combination of the dictionary atoms}. Since, the data reside on a statistical
manifold, the data fidelity term can not be as simple as in the case of the
vector-space data. We therefore employ the geodesic distance between the data
and a sparse approximation of the data element. This cost function is minimized
using an acceleterated gradient descent algorithm. An extensive set of
experimental results show the effectiveness of our proposed framework. We
present several experiments involving a variety of classification problems in
Computer Vision applications. Further, we demonstrate the performance of our
algorithm by comparing it to several state-of-the-art methods both in terms of
classification accuracy and sparsity.


title: Benedicks' Theorem for the Weyl Transform

abstract:
  If the set of points where a function is nonzero is of finite measure, and
its Weyl transform is a finite rank operator, then the function is identically
zero.


title:
A multilevel based reweighting algorithm with joint regularizers for
  sparse recovery

abstract:
  Sparsity is one of the key concepts that allows the recovery of signals that
are subsampled at a rate significantly lower than required by the
Nyquist-Shannon sampling theorem. Our proposed framework uses arbitrary
multiscale transforms, such as those build upon wavelets or shearlets, as a
sparsity promoting prior which allow to decompose the image into different
scales such that image features can be optimally extracted. In order to further
exploit the sparsity of the recovered signal we combine the method of
reweighted $\ell^1$, introduced by Cand\`es et al., with iteratively updated
weights accounting for the multilevel structure of the signal. This is done by
directly incorporating this approach into a split Bregman based algorithmic
framework. Furthermore, we add total generalized variation (TGV) as a second
regularizer into the split Bregman algorithm. The resulting algorithm is then
applied to a classical and widely considered task in signal- and image
processing which is the reconstruction of images from their Fourier
measurements. Our numerical experiments show a highly improved performance at
relatively low computational costs compared to many other well established
methods and strongly suggest that sparsity is better exploited by our method.


title:
Exact closed probability-free kinetic equation for system of classical
  particles with retarded interactions: towards microscopic foundation of
  kinetics

abstract:
  The exact closed equation of motion for microscopic distribution function of
classical many-body system with account of interactions retardation between
particles is derived. It is shown that interactions retardation leads to
irreversible behaviour of many-body systems.
  PACS: 05.20.Dd ; 05.60.-k; 45.20.-d


title:
A simple proof of heavy tail estimates for affine type Lipschitz
  recursions

abstract:
  We study the affine recursion $X_n = A_nX_{n-1}+B_n$ where $(A_n,B_n)\in
{\mathbb R}^+ \times {\mathbb R} $ is an i.i.d. sequence and recursions $X_n =
\Phi_n(X_{n-1})$ defined by Lipschitz transformations such that $\Phi (x)\geq
Ax+B$. It is known that under appropriate hypotheses the stationary solution
$X$ has regularly varying tail, i.e. $$\lim_{t\to\infty} t^{\alpha} {\mathbb
P}[X>t] = C. $$ However positivity of $C$ in general is either unknown or
requires some additional involved arguments. In this paper we give a simple
proof that $C>0$. This applies, in particular, to the case when Kesten-Goldie
assumptions are satisfied.


title:
Thickness dependent interlayer transport in vertical MoS2 Josephson
  junctions

abstract:
  We report on observations of thickness dependent Josephson coupling and
multiple Andreev reflections (MAR) in vertically stacked molybdenum disulfide
(MoS2) - molybdenum rhenium (MoRe) Josephson junctions. MoRe, a chemically
inert superconductor, allows for oxide free fabrication of high transparency
vertical MoS2 devices. Single and bilayer MoS2 junctions display relatively
large critical currents (up to 2.5 uA) and the appearance of sub-gap structure
given by MAR. In three and four layer thick devices we observe orders of
magnitude lower critical currents (sub-nA) and reduced quasiparticle gaps due
to proximitized MoS2 layers in contact with MoRe. We anticipate that this
device architecture could be easily extended to other 2D materials.


title:
Giant magnetoresistance, three-dimensional Fermi surface and origin of
  resistivity plateau in YSb semimetal

abstract:
  Very strong magnetoresistance and a resistivity plateau impeding low
temperature divergence due to insulating bulk are hallmarks of topological
insulators and are also present in topological semimetals where the plateau is
induced by magnetic field, when time-reversal symmetry (protecting surface
states in topological insulators) is broken. Similar features were observed in
a simple rock-salt-structure LaSb, leading to a suggestion of the possible
non-trivial topology of 2D states in this compound. We show that its sister
compound YSb is also characterized by giant magnetoresistance exceeding one
thousand percent and low-temperature plateau of resistivity. We thus performed
in-depth analysis of YSb Fermi surface by band calculations, magnetoresistance,
and Shubnikov--de Haas effect measurements, which reveals only
three-dimensional Fermi sheets. Kohler scaling applied to magnetoresistance
data accounts very well for its low-temperature upturn behavior. The
field-angle-dependent magnetoresistance demonstrates a 3D-scaling yielding
effective mass anisotropy perfectly agreeing with electronic structure and
quantum oscillations analysis, thus providing further support for 3D-Fermi
surface scenario of magnetotransport, without necessity of invoking
topologically non-trivial 2D states. We discuss data implying that analogous
field-induced properties of LaSb can also be well understood in the framework
of 3D multiband model.


title: A simple model of scientific progress - with examples

abstract:
  One of the main goals of scientific research is to provide a description of
the empirical data which is as accurate and comprehensive as possible, while
relying on as few and simple assumptions as possible. In this paper, I propose
a definition of the notion of "few and simple assumptions" that is not affected
by known problems. This leads to the introduction of a simple model of
scientific progress that is based only on empirical accuracy and conciseness.
An essential point in this task is the understanding of the role played by
"measurability" in the formulation of a scientific theory. This is the key to
prevent artificially concise formulations. The model is confronted here with
many possible objections and with challenging cases of real progress. Although
I cannot exclude that the model might have some limitations, it includes all
the cases of genuine progress examined here, and no spurious one. In this
model, I stress the role of the "state of the art", which is the collection of
all the theories that are the only legitimate source of scientific predictions.
Progress is a global upgrade of the state of the art.


title:
Relative information entropy in cosmology: The problem of information
  entanglement

abstract:
  The necessary information to distinguish a local inhomogeneous mass density
field from its spatial average on a compact domain of the universe can be
measured by relative information entropy. The Kullback-Leibler (KL) formula
arises very naturally in this context, however, it provides a very complicated
way to compute the mutual information between spatially separated but causally
connected regions of the universe in a realistic, inhomogeneous model. To
circumvent this issue, by considering a parametric extension of the KL measure,
we develop a simple model to describe the mutual information which is entangled
via the gravitational field equations. We show that the Tsallis relative
entropy can be a good approximation in the case of small inhomogeneities, and
for measuring the independent relative information inside the domain, we
propose the R\'enyi relative entropy formula.


title: Telling the spin of the di-photon resonance

abstract:
  We argue that the spin of the 750 GeV resonance can be determined at the
99.7% confidence level in the di-photon channel with as few as 10 fb$^{-1}$ of
luminosity. This result is true if the resonance is produced by gluon fusion
(independently of the selection cuts) while an appropriate choice of selection
cuts is needed if quark production is sub-dominantly present--which is the case
of the Kaluza-Klein gravitational excitation under the hypothesis of a spin-2
resonance. A proportionally larger luminosity is required if the model for the
spin-2 resonance includes a dominant production by quarks or in the absence of
an efficient separation of the signal from the background.


title: Science and Illusions

abstract:
  It is mostly agreed that Popper's criterion of falsifiability fails to
provide a useful demarcation between science and pseudo-science, because ad-hoc
assumptions are always able to save any theory that conflicts with the
empirical data (a.k.a. the Duhem-Quine problem), and a characterization of
ad-hoc assumptions is lacking. Moreover, adding some testable predictions is
not very difficult. It should be emphasized that these problems do not simply
make Popper's demarcation approximate (if it were so, all our problems would be
solved!), they make it totally useless. More in general, no philosophical
criterion of demarcation is presently able to rule out even some of the most
blatant cases of pseudo-science, not even approximatively (in any well defined
sense of approximation). This is in sharp contrast with our firm belief that
some theories are clearly not scientific. Where does this belief come from? In
this paper I argue that it is necessary and possible to recognize the notion of
syntactic simplicity that is able to tell the difference between empirically
equivalent scientific and non-scientific theories, with a confidence that is
adequate to many important practical purposes, and it fully agrees with the
judgments generally held in the scientific community.


title: Game-theoretic characterization of the Gurarii space

abstract:
  We present a simple and natural infinite game building an increasing chain of
finite-dimensional Banach spaces. We show that one of the players has a
strategy with the property that, no matter how the other player plays, the
completion of the union of the chain is linearly isometric to the Gurarii
space.


title: Determining Parameters Leading to Chaotic Dynamics in Systems

abstract:
  Many biological ecosystems exhibit chaotic behavior, demonstrated either
analytically using parameter choices in an associated dynamical systems model
or empirically through analysis of experimental data. In this paper, we provide
a computational framework which can be used to both explore the parameter space
for the existence of positive Lyapunov exponents and visualize the connections
between parameters leading to these positive values. We demonstrate the
effectiveness of the framework on several dynamical systems used to model
bacterial populations with a nutrient source. We provide sample graphics to
show the possible ways this framework can be used to gather insight of an
underlying system without requiring detailed mathematical analysis.


title:
Visualization of Jacques Lacan's Registers of the Psychoanalytic Field,
  and Discovery of Metaphor and of Metonymy. Analytical Case Study of Edgar
  Allan Poe's "The Purloined Letter"

abstract:
  We start with a description of Lacan's work that we then take into our
analytics methodology. In a first investigation, a Lacan-motivated template of
the Poe story is fitted to the data. A segmentation of the storyline is used in
order to map out the diachrony. Based on this, it will be shown how synchronous
aspects, potentially related to Lacanian registers, can be sought. This
demonstrates the effectiveness of an approach based on a model template of the
storyline narrative. In a second and more comprehensive investigation, we
develop an approach for revealing, that is, uncovering, Lacanian register
relationships. Objectives of this work include the wide and general application
of our methodology. This methodology is strongly based on the "letting the data
speak" Correspondence Analysis analytics platform of Jean-Paul Benz\'ecri, that
is also the geometric data analysis, both qualitative and quantitative
analytics, developed by Pierre Bourdieu.


title:
The $L^p$-diameter of the group of area-preserving diffeomorphisms of
  $S^2$

abstract:
  We show that for each $p \geq 1,$ the $L^p$-metric on the group of
area-preserving diffeomorphisms of the two-sphere has infinite diameter. This
solves the last open case of a conjecture of Shnirelman from 1985. Our methods
extend to yield stronger results on the large-scale geometry of the
corresponding metric space, completing an answer to a question of Kapovich from
2012. Our proof uses configuration spaces of points on the two-sphere,
quasi-morphisms, optimally chosen braid diagrams, and, as a key element, the
cross-ratio map $X_4(\mathbb{C} P^1) \to \mathcal{M}_{0,4} \cong \mathbb{C} P^1
\setminus \{\infty,0,1\}$ from the configuration space of $4$ points on
$\mathbb{C} P^1$ to the moduli space of complex rational curves with $4$ marked
points.

categories: math.GT math-ph math.DG math.DS math.MP math.SG


title: RHOG: A Refinement-Operator Library for Directed Labeled Graphs

abstract:
  This document provides the foundations behind the functionality provided by
the $\rho$G library (https://github.com/santiontanon/RHOG), focusing on the
basic operations the library provides: subsumption, refinement of directed
labeled graphs, and distance/similarity assessment between directed labeled
graphs. $\rho$G development was initially supported by the National Science
Foundation, by the EAGER grant IIS-1551338.


title: Statistical analyses of hydrophobic interactions: A mini-review

abstract:
  This review focuses on the striking recent progress in solving for
hydrophobic interactions between small inert molecules. We discuss several new
understandings. Firstly, the _inverse _temperature phenomenology of hydrophobic
interactions, _i.e., strengthening of hydrophobic bonds with increasing
temperature, is decisively exhibited by hydrophobic interactions between
atomic-scale hard sphere solutes in water. Secondly, inclusion of attractive
interactions associated with atomic-size hydrophobic reference cases leads to
substantial, non-trivial corrections to reference results for purely repulsive
solutes. Hydrophobic bonds are _weakened by adding solute dispersion forces to
treatment of reference cases. The classic statistical mechanical theory for
those corrections is not accurate in this application, but molecular
quasi-chemical theory shows promise. Finally, because of the masking roles of
excluded volume and attractive interactions, comparisons that do not
discriminate the different possibilities face an interpretive danger.


title: Energy criterion for the spectral stability of discrete breathers

abstract:
  Discrete breathers are ubiquitous structures in nonlinear anharmonic models
ranging from the prototypical example of the Fermi-Pasta-Ulam model to
Klein-Gordon nonlinear lattices, among many others. We propose a general
criterion for the emergence of instabilities of discrete breathers analogous to
the well-established Vakhitov-Kolokolov criterion for solitary waves. The
criterion involves the change of monotonicity of the discrete breather's energy
as a function of the breather frequency. Our analysis suggests and numerical
results corroborate that breathers with increasing (decreasing)
energy-frequency dependence are generically unstable in soft (hard) nonlinear
potentials.


title:
Strong instability of standing waves for nonlinear Schr\"odinger
  equations with harmonic potential

abstract:
  We study strong instability of standing waves $e^{i\omega t}
\phi_{\omega}(x)$ for nonlinear Schr\"odinger equations with
$L^2$-supercritical nonlinearity and a harmonic potential, where
$\phi_{\omega}$ is a ground state of the corresponding stationary problem. We
prove that $e^{i\omega t} \phi_{\omega}(x)$ is strongly unstable if
$\partial_{\lambda}^2 E(\phi_{\omega}^{\lambda}) |_{\lambda=1}\le 0$, where $E$
is the energy and $v^{\lambda}(x)=\lambda^{N/2} v(\lambda x)$ is the
$L^2$-invariant scaling.


title:
Online Combinatorial Optimization for Interconnected Refrigeration
  Systems: Linear Approximation and Submodularity

abstract:
  Commercial refrigeration systems consume 7% of the total commercial energy
consumption in the United States. Improving their energy efficiency contributes
to the sustainability of global energy systems and the supermarket business
sector. This paper proposes a new control method that can save the energy
consumption of multi-case supermarket refrigerators by explicitly taking into
account their interconnected and switched system dynamics. Its novelty is a
bilevel combinatorial optimization formulation to generate ON/OFF control
actions for expansion valves and compressors. The inner optimization module
keeps display case temperatures in a desirable range and the outer optimization
module minimizes energy consumption. In addition to its energy-saving
capability, the proposed controller significantly reduces the frequency of
compressor switchings by employing a conservative compressor control strategy.
However, solving this bilevel optimization problem associated with
interconnected and switched systems is a computationally challenging task. To
solve the problem in near real time, we propose two approximation algorithms
that can solve both the inner and outer optimization problems at once. The
first algorithm uses a linear approximation, and the second is based on the
submodular structure of the optimization problem. Both are (polynomial-time)
scalable algorithms and generate near-optimal solutions with performance
guarantees. Our work complements existing optimization-based control methods
(e.g., MPC) for supermarket refrigerators, as our algorithms can be adopted as
a tool for solving combinatorial optimization problems arising in these
methods.


title: Privacy, Discovery, and Authentication for the Internet of Things

abstract:
  Automatic service discovery is essential to realizing the full potential of
the Internet of Things (IoT). While discovery protocols like Multicast DNS,
Apple AirDrop, and Bluetooth Low Energy have gained widespread adoption across
both IoT and mobile devices, most of these protocols do not offer any form of
privacy control for the service, and often leak sensitive information such as
service type, device hostname, device owner's identity, and more in the clear.
  To address the need for better privacy in both the IoT and the mobile
landscape, we develop two protocols for private service discovery and private
mutual authentication. Our protocols provide private and authentic service
advertisements, zero round-trip (0-RTT) mutual authentication, and are provably
secure in the Canetti-Krawczyk key-exchange model. In contrast to alternatives,
our protocols are lightweight and require minimal modification to existing
key-exchange protocols. We integrate our protocols into an existing open-source
distributed applications framework, and provide benchmarks on multiple hardware
platforms: Intel Edisons, Raspberry Pis, smartphones, laptops, and desktops.
Finally, we discuss some privacy limitations of the Apple AirDrop protocol (a
peer-to-peer file sharing mechanism) and show how to improve the privacy of
Apple AirDrop using our private mutual authentication protocol.


title: Zeeman Doppler maps: the true and the spurious

abstract:
  Numerical models of atomic diffusion in magnetic atmospheres of ApBp stars
predict abundance structures that differ from the empirical abundance maps
derived with (Zeeman) Doppler mapping (ZDM). Whereas both equilibrium abundance
stratification calculations and stationary solutions to the time-dependent
diffusion equations predict (warped) rings about the magnetic equator in
dipole-like magnetic geometries, spot-like structures dominate published maps.
An in-depth analysis of this apparent disagreement investigates the
detectability by means of ZDM of a variety of abundance structures, including
(warped) rings predicted by theory, but also some complex spot-like structures.
As it turns out, a number of published maps have to be considered spurious
either because strong magnetic fields have been neglected or because they are
based on spectra where photon noise dominates over the signal of the alleged
abundance structures. Even when spectra of high signal to noise ratio are
available, it can prove altogether impossible to correctly recover shapes,
positions and abundances of a mere handful of spots, even using all 4 Stokes
parameters and knowing the field geometry, the recovery of (warped) rings can
be equally challenging. Inversions -- based on just one or two spectral lines
-- of complex abundance maps usually admit of multiple solutions. It turns out
that there is no guarantee that a properly chosen regularisation function will
lead to the true abundance map. Attention is drawn to the need for a study that
would elucidate the relation between the stratified, field-dependent abundance
structures predicted by diffusion theory and empirical maps obtained by means
of "canonical" ZDM, i.e. with mean atmospheres and unstratified abundances.
Finally we point out difficulties arising from the 3D nature of the atomic
diffusion process in magnetic ApBp star atmospheres.


title:
Sparse p-Adic Data Coding for Computationally Efficient and Effective
  Big Data Analytics

abstract:
  We develop the theory and practical implementation of p-adic sparse coding of
data. Rather than the standard, sparsifying criterion that uses the $L_0$
pseudo-norm, we use the p-adic norm. We require that the hierarchy or tree be
node-ranked, as is standard practice in agglomerative and other hierarchical
clustering, but not necessarily with decision trees. In order to structure the
data, all computational processing operations are direct reading of the data,
or are bounded by a constant number of direct readings of the data, implying
linear computational time. Through p-adic sparse data coding, efficient storage
results, and for bounded p-adic norm stored data, search and retrieval are
constant time operations. Examples show the effectiveness of this new approach
to content-driven encoding and displaying of data.


title: A new distance law of planets and satellites in the solar system

abstract:
  In the 1960s, it has been substantiated that an equation of Schrodinger type
could describe the diffusion phenomena, and the main consequence from this
finding has been that there would be wave property in the diffusion processes
as well. This theory has been immediately proved through laboratorial
experiments. Afterwards the theory was applied to the primordial nebula which
was thought to surround the protosun, and has found the consistency of the
prediction of the theory with current distance distribution of the planets to
be excellent. At the end of 20th century new satellites of planets were
discovered. On the basis of the new data, the theory is tested thoroughly and
the result allows us to come to the conclusion that the basic process for the
distances of the planets from the protosun to be determined has been the
diffusion of the primordial nebula consisting of mainly molecular gas.


title: Limits to Verification and Validation of Agentic Behavior

abstract:
  Verification and validation of agentic behavior have been suggested as
important research priorities in efforts to reduce risks associated with the
creation of general artificial intelligence (Russell et al 2015). In this paper
we question the appropriateness of using language of certainty with respect to
efforts to manage that risk. We begin by establishing a very general formalism
to characterize agentic behavior and to describe standards of acceptable
behavior. We show that determination of whether an agent meets any particular
standard is not computable. We discuss the extent of the burden associated with
verification by manual proof and by automated behavioral governance. We show
that to ensure decidability of the behavioral standard itself, one must further
limit the capabilities of the agent. We then demonstrate that if our concerns
relate to outcomes in the physical world, attempts at validation are futile.
Finally, we show that layered architectures aimed at making these challenges
tractable mistakenly equate intentions with actions or outcomes, thereby
failing to provide any guarantees. We conclude with a discussion of why
language of certainty should be eradicated from the conversation about the
safety of general artificial intelligence.


title: BinderCracker: Assessing the Robustness of Android System Services

abstract:
  In Android, communications between apps and system services are supported by
a transaction-based Inter-Process Communication (IPC) mechanism. Binder, as the
cornerstone of this IPC mechanism, separates two communicating parties as
client and server. As with any client-server model, the server should not make
any assumption on the validity (sanity) of client-side transaction. To our
surprise, we find this principle has frequently been overlooked in the
implementation of Android system services. In this paper, we demonstrate the
prevalence and severity of this vulnerability surface and try to answer why
developers keep making this seemingly simple mistake. Specifically, we design
and implement BinderCracker, an automatic testing framework that supports
parameter-aware fuzzing and has identified more than 100 vulnerabilities in six
major versions of Android, including the latest version Android 6.0,
Marshmallow. Some of the vulnerabilities have severe security implications,
causing privileged code execution or permanent Denial-of-Service (DoS). We
analyzed the root causes of these vulnerabilities to find that most of them
exist because system service developers only considered exploitations via
public APIs. We thus highlight the deficiency of testing only on client-side
public APIs and argue for the necessity of testing and protection on the Binder
interface - the actual security boundary. Specifically, we discuss the
effectiveness and practicality of potential countermeasures, such as
precautionary testing and runtime diagnostic.


title:
Deep Imaging in Scattering Media with Single Photon Selective Plane
  Illumination Microscopy (SPIM)

abstract:
  In most biological tissues, light scattering due to small differences in
refractive index limits the depth of optical imaging systems. Two-photon
microscopy (2PM), which significantly reduces the scattering of the excitation
light, has emerged as the most common method to image deep within scattering
biological tissue. This technique, however, requires high-power pulsed lasers
that are both expensive and difficult to integrate into compact portable
systems. In this paper, using a combination of theoretical and experimental
techniques, we show that Selective Plane Illumination Microscopy (SPIM) can
image nearly as deep as 2PM without the need for a high-powered pulsed laser.
Compared to other single photon imaging techniques like epifluorescence and
confocal microscopy, SPIM can image more than twice as deep in scattering media
(approximately 10 times the mean scattering length). These results suggest that
SPIM has the potential to provide deep imaging in scattering media in
situations where 2PM systems would be too large or costly.