title:
Effects of electrode surface roughness on motional heating of trapped
  ions

abstract:
  Electric field noise is a major source of motional heating in trapped ion
quantum computation. While the influence of trap electrode geometries on
electric field noise has been studied in patch potential and surface adsorbate
models, only smooth surfaces are accounted for by current theory. The effects
of roughness, a ubiquitous feature of surface electrodes, are poorly
understood. We investigate its impact on electric field noise by deriving a
rough-surface Green's function and evaluating its effects on adsorbate-surface
binding energies. At cryogenic temperatures, heating rate contributions from
adsorbates are predicted to exhibit an exponential sensitivity to local surface
curvature, leading to either a large net enhancement or suppression over smooth
surfaces. For typical experimental parameters, orders-of-magnitude variations
in total heating rates can occur depending on the spatial distribution of
absorbates. Through careful engineering of electrode surface profiles, our
results suggests that heating rates can be tuned over orders of magnitudes.


title:
The large graph limit of a stochastic epidemic model on a dynamic
  multilayer network

abstract:
  We consider an SIR-type (Susceptible $\to$ Infected $\to$ Recovered)
stochastic epidemic process with multiple modes of transmission on a contact
network. The network is given by a random graph following a multilayer
configuration model where edges in different layers correspond to potentially
infectious contacts of different types. We assume that the graph structure
evolves in response to the epidemic via activation or deactivation of edges. We
derive a large graph limit theorem that gives a system of ordinary differential
equations (ODEs) describing the evolution of quantities of interest, such as
the proportions of infected and susceptible vertices, as the number of nodes
tends to infinity. Analysis of the limiting system elucidates how the coupling
of edge activation and deactivation to infection status affects disease
dynamics, as illustrated by a two-layer network example with edge types
corresponding to community and healthcare contacts. Our theorem extends some
earlier results deriving the deterministic limit of stochastic SIR processes on
static, single-layer configuration model graphs. We also describe precisely the
conditions for equivalence between our limiting ODEs and the systems obtained
via pair approximation, which are widely used in the epidemiological and
ecological literature to approximate disease dynamics on networks. Potential
applications include modeling Ebola dynamics in West Africa, which was the
motivation for this study.


title:
The Power of Principled Bayesian Methods in the Study of Stellar
  Evolution

abstract:
  It takes years of effort employing the best telescopes and instruments to
obtain high-quality stellar photometry, astrometry, and spectroscopy. Stellar
evolution models contain the experience of lifetimes of theoretical
calculations and testing. Yet most astronomers fit these valuable models to
these precious datasets by eye. We show that a principled Bayesian approach to
fitting models to stellar data yields substantially more information over a
range of stellar astrophysics. We highlight advances in determining the ages of
star clusters, mass ratios of binary stars, limitations in the accuracy of
stellar models, post-main-sequence mass loss, and the ages of individual white
dwarfs. We also outline a number of unsolved problems that would benefit from
principled Bayesian analyses.


title:
On the compressibility effect in test particle acceleration by
  magnetohydrodynamic turbulence

abstract:
  The effect of compressibility in charged particle energization by
magnetohydrodynamic (MHD) fields is studiedin the context of test particle
simulations. This problem is relevant to the solar wind and the solar corona
due to the compressible nature of the flow in those astrophysical scenarios. We
consider turbulent electromagnetic fields obtained from direct numerical
simulations of the MHD equations with a strong background magnetic field. In
order to explore the flow compressibilty effect over the particle dynamics we
performed different numerical experiments: an incompressible case, and two weak
compressible cases with Mach number M = 0.1 and M = 0.25. We analyze the
behavior of protons and electrons in those turbulent fields, which are well
known to form aligned current sheets in the direction of the guide magnetic
field. What we call protons and electrons are test particles with scales
comparable to (for protons) and much smaller than (for electrons) the
dissipative scale of MHD turbulence, maintaining the correct mass ratio me /mi.
For these test particles we show that compressibility enhances the efficiency
of proton acceleration, and that the energization is caused by perpendicular
electric fields generated between currents sheets. On the other hand, electrons
remain magnetized and display an almost adiabatic motion, with no effect of
compressibility observed. Another set of numerical experiments takes into
account two fluid modifications, namely electric field due to Hall effect and
electron pressure gradient. We show that the electron pressure has an important
contribution to electron acceleration allowing highly parallel energization. In
contrast, no significant effect of these additional terms is observed for the
protons.


title: Nonempirical Range-separated Hybrid Functionals for Solids and Molecules

abstract:
  Dielectric-dependent hybrid (DDH) functionals were recently shown to yield
accurate energy gaps and dielectric constants for a wide variety of solids, at
a computational cost considerably less than that of GW calculations. The
fraction of exact exchange included in the definition of DDH functionals
depends (self-consistently) on the dielectric constant of the material. Here we
introduce a range-separated (RS) version of DDH functionals where short and
long-range components are matched using system dependent, non-empirical
parameters. We show that RS DDHs yield accurate electronic properties of
inorganic and organic solids, including energy gaps and absolute ionization
potentials. Furthermore we show that these functionals may be generalized to
finite systems.


title:
Micro-Synchrophasors for Power Distribution Monitoring, a Technology
  Review

abstract:
  The smart grid revolution is creating a paradigm shift in distribution
networks that is marked by new, significant intermittencies and uncertainties
in power supply and demand. These developments include the dramatic increase in
the adoption of distributed energy resources (DER), electric vehicles, energy
storage, and controllable loads. This transformation imposes new challenges on
existing distribution infrastructure and system operations for stockholders,
engineers, operators and customers. Unfortunately, distribution networks
historically lag behind transmission networks in terms of observability,
measurement accuracy, and data granularity. The changes in the operation of the
electric grid dramatically increase the need for tools to monitor and manage
distribution networks in a fast, reliable and accurate fashion. This paper
describes the development process of a network of high-precision micro phasor
measurement units or uPMUs, beginning with an overview of the uPMU technology
that provides synchronous measurements of voltage phase angles, or
synchrophasors. Next, the uPMU network and communications infrastructure are
discussed, followed by an analysis of potential diagnostic and control
applications of uPMU data in the electric grid at the distribution level.


title:
Controlling Spin-Polarization in Graphene by Cloaking Magnetic and
  Spin-Orbit Scatterers

abstract:
  We consider spin-dependent scatterers with large scattering cross-sections in
graphene -a Zeeman-like and an intrinsic spin-orbit coupling impurity- and show
that a gated ring around them can be engineered to produce an effcient control
of the spin dependent transport, like current spin polarization and spin Hall
angle. Our analysis is based on a spin-dependent partial-waves expansion of the
electronic wave-functions in the continuum approximation, described by the
Dirac equation.


title: Boundaries of VP and VNP

abstract:
  One fundamental question in the context of the geometric complexity theory
approach to the VP vs. VNP conjecture is whether VP = $\overline{\textrm{VP}}$,
where VP is the class of families of polynomials that are of polynomial degree
and can be computed by arithmetic circuits of polynomial size, and
$\overline{\textrm{VP}}$ is the class of families of polynomials that are of
polynomial degree and can be approximated infinitesimally closely by arithmetic
circuits of polynomial size. The goal of this article is to study the
conjecture in (Mulmuley, FOCS 2012) that $\overline{\textrm{VP}}$ is not
contained in VP.
  Towards that end, we introduce three degenerations of VP (i.e., sets of
points in $\overline{\textrm{VP}}$), namely the stable degeneration Stable-VP,
the Newton degeneration Newton-VP, and the p-definable one-parameter
degeneration VP*. We also introduce analogous degenerations of VNP. We show
that Stable-VP $\subseteq$ Newton-VP $\subseteq$ VP* $\subseteq$ VNP, and
Stable-VNP = Newton-VNP = VNP* = VNP. The three notions of degenerations and
the proof of this result shed light on the problem of separating
$\overline{\textrm{VP}}$ from VP.
  Although we do not yet construct explicit candidates for the polynomial
families in $\overline{\textrm{VP}}\setminus$VP, we prove results which tell us
where not to look for such families. Specifically, we demonstrate that the
families in Newton-VP $\setminus$ VP based on semi-invariants of quivers would
have to be non-generic by showing that, for many finite quivers (including some
wild ones), any Newton degeneration of a generic semi-invariant can be computed
by a circuit of polynomial size. We also show that the Newton degenerations of
perfect matching Pfaffians, monotone arithmetic circuits over the reals, and
Schur polynomials have polynomial-size circuits.


title:
A probabilistic max-plus numerical method for solving stochastic control
  problems

abstract:
  We consider fully nonlinear Hamilton-Jacobi-Bellman equations associated to
diffusion control problems involving a finite set-valued (or switching) control
and possibly a continuum-valued control. We construct a lower complexity
probabilistic numerical algorithm by combining the idempotent expansion
properties obtained by McEneaney, Kaise and Han (2011) for solving such
problems with a numerical probabilistic method such as the one proposed by
Fahim, Touzi and Warin (2011) for solving some fully nonlinear parabolic
partial differential equations. Numerical tests on a small example of pricing
and hedging an option are presented.


title: Unethical Research: How to Create a Malevolent Artificial Intelligence

abstract:
  Cybersecurity research involves publishing papers about malicious exploits as
much as publishing information on how to design tools to protect
cyber-infrastructure. It is this information exchange between ethical hackers
and security experts, which results in a well-balanced cyber-ecosystem. In the
blooming domain of AI Safety Engineering, hundreds of papers have been
published on different proposals geared at the creation of a safe machine, yet
nothing, to our knowledge, has been published on how to design a malevolent
machine. Availability of such information would be of great value particularly
to computer scientists, mathematicians, and others who have an interest in AI
safety, and who are attempting to avoid the spontaneous emergence or the
deliberate creation of a dangerous AI, which can negatively affect human
activities and in the worst case cause the complete obliteration of the human
species. This paper provides some general guidelines for the creation of a
Malevolent Artificial Intelligence (MAI).


title: Brascamp-Lieb Inequality and Its Reverse: An Information Theoretic View

abstract:
  We generalize a result by Carlen and Cordero-Erausquin on the equivalence
between the Brascamp-Lieb inequality and the subadditivity of relative entropy
by allowing for random transformations (a broadcast channel). This leads to a
unified perspective on several functional inequalities that have been gaining
popularity in the context of proving impossibility results. We demonstrate that
the information theoretic dual of the Brascamp-Lieb inequality is a convenient
setting for proving properties such as data processing, tensorization,
convexity and Gaussian optimality. Consequences of the latter include an
extension of the Brascamp-Lieb inequality allowing for Gaussian random
transformations, the determination of the multivariate Wyner common information
for Gaussian sources, and a multivariate version of Nelson's hypercontractivity
theorem. Finally we present an information theoretic characterization of a
reverse Brascamp-Lieb inequality involving a random transformation (a multiple
access channel).


title: Ab initio no-core solutions for $^6$Li

abstract:
  We solve for properties of $^6$Li in the ab initio No-Core Full Configuration
approach and we separately solve for its ground state and $J^{\pi}=2_{2}^{+}$
resonance with the Gamow Shell Model in the Berggren basis. We employ both the
JISP16 and chiral NNLO$_{opt}$ realistic nucleon-nucleon interactions and
investigate the ground state energy, excitation energies, point proton
root-mean-square radius and a suite of electroweak observables. We also extend
and test methods to extrapolate the ground state energy, point proton
root-mean-square radius, and electric quadrupole moment. We attain improved
estimates of these observables in the No-Core Full Configuration approach by
using basis spaces up through N$_{max}$=18 that enable more definitive
comparisons with experiment. Using the Density Matrix Renormalization Group
approach with the JISP16 interaction, we find that we can significantly improve
the convergence of the Gamow Shell Model treatment of the $^6$Li ground state
and $J^{\pi}=2_{2}^{+}$ resonance by adopting a natural orbital single-particle
basis.


title:
The It\^o SDEs and Fokker--Planck equations with Osgood and Sobolev
  coefficients

abstract:
  We study the degenerated It\^o SDE on $\mathbb R^d$ whose drift coefficient
only fulfills a mixed Osgood and Sobolev regularity. Under suitable assumptions
on the gradient of the diffusion coefficient and on the divergence of the drift
coefficient, we prove the existence and uniqueness of generalized stochastic
flows associated to such equations. We also prove the uniqueness of solutions
to the corresponding Fokker--Planck equation by using the probabilistic method.


title: Finite-Block-Length Analysis in Classical and Quantum Information Theory

abstract:
  Coding technology is used in several information processing tasks. In
particular, when noise during transmission disturbs communications, coding
technology is employed to protect the information. However, there are two types
of coding technology: coding in classical information theory and coding in
quantum information theory. Although the physical media used to transmit
information ultimately obey quantum mechanics, we need to choose the type of
coding depending on the kind of information device, classical or quantum, that
is being used. In both branches of information theory, there are many elegant
theoretical results under the ideal assumption that an infinitely large system
is available. In a realistic situation, we need to account for finite size
effects. The present paper reviews finite size effects in classical and quantum
information theory with respect to various topics, including applied aspects.


title:
Hubble Space Telescope Observations of Accretion-Induced Star Formation
  in the Tadpole Galaxy Kiso 5639

abstract:
  The tadpole galaxy Kiso 5639 has a slowly rotating disk with a drop in
metallicity at its star-forming head, suggesting that star formation was
triggered by the accretion of metal-poor gas. We present multi-wavelength HST
WFC3 images of UV through I band plus Halpha to search for peripheral emission
and determine the properties of various regions. The head has a mass in young
stars of ~10^6 Mo and an ionization rate of 6.4x10^51 s^{-1}, equivalent to
~2100 O9-type stars. There are four older star-forming regions in the tail, and
an underlying disk with a photometric age of ~1 Gyr. The mass distribution
function of 61 star clusters is a power law with a slope of -1.73+-0.51.
Fourteen young clusters in the head are more massive than 10^4 Mo, suggesting a
clustering fraction of 30%-45%. Wispy filaments of Halpha emission and young
stars extend away from the galaxy. Shells and holes in the head HII region
could be from winds and supernovae. Gravity from the disk should limit the
expansion of the HII region, although hot gas might escape through the holes.
The star formation surface density determined from Halpha in the head is
compared to that expected from likely pre-existing and accreted gas. Unless the
surface density of the accreted gas is a factor of ~3 or more larger than what
was in the galaxy before, the star formation rate has to exceed the usual
Kennicutt-Schmidt rate by a factor of >5.


title: Explosive Chromospheric Evaporation in a Circular-ribbon Flare

abstract:
  In this paper, we report our multiwavelength observations of the C4.2
circular-ribbon flare in active region (AR) 12434 on 2015 October 16. The
short-lived flare was associated with positive magnetic polarities and a
negative polarity inside, as revealed by the photospheric line-of-sight
magnetograms. Such magnetic pattern is strongly indicative of a magnetic null
point and spine-fan configuration in the corona. The flare was triggered by the
eruption of a mini-filament residing in the AR, which produced the inner flare
ribbon (IFR) and the southern part of a closed circular flare ribbon (CFR).
When the eruptive filament reached the null point, it triggered null point
magnetic reconnection with the ambient open field and generated the bright CFR
and a blowout jet. Raster observations of the \textit{Interface Region Imaging
Spectrograph} (\textit{IRIS}) show plasma upflow at speed of 35$-$120 km
s$^{-1}$ in the Fe {\sc xxi} 1354.09 {\AA} line ($\log T\approx7.05$) and
downflow at speed of 10$-$60 km s$^{-1}$ in the Si {\sc iv} 1393.77 {\AA} line
($\log T\approx4.8$) at certain locations of the CFR and IFR during the
impulsive phase of flare, indicating explosive chromospheric evaporation.
Coincidence of the single HXR source at 12$-$25 keV with the IFR and
calculation based on the thick-target model suggest that the explosive
evaporation was most probably driven by nonthermal electrons.


title: RORS: Enhanced Rule-based OWL Reasoning on Spark

abstract:
  The rule-based OWL reasoning is to compute the deductive closure of an
ontology by applying RDF/RDFS and OWL entailment rules. The performance of the
rule-based OWL reasoning is often sensitive to the rule execution order. In
this paper, we present an approach to enhancing the performance of the
rule-based OWL reasoning on Spark based on a locally optimal executable
strategy. Firstly, we divide all rules (27 in total) into four main classes,
namely, SPO rules (5 rules), type rules (7 rules), sameAs rules (7 rules), and
schema rules (8 rules) since, as we investigated, those triples corresponding
to the first three classes of rules are overwhelming (e.g., over 99% in the
LUBM dataset) in our practical world. Secondly, based on the interdependence
among those entailment rules in each class, we pick out an optimal rule
executable order of each class and then combine them into a new rule execution
order of all rules. Finally, we implement the new rule execution order on Spark
in a prototype called RORS. The experimental results show that the running time
of RORS is improved by about 30% as compared to Kim & Park's algorithm (2015)
using the LUBM200 (27.6 million triples).


title:
False positive probabilties for all Kepler Objects of Interest: 1284
  newly validated planets and 428 likely false positives

abstract:
  We present astrophysical false positive probability calculations for every
Kepler Object of Interest (KOI)---the first large-scale demonstration of a
fully automated transiting planet validation procedure. Out of 7056 KOIs, we
determine that 1935 have probabilities <1% to be astrophysical false positives,
and thus may be considered validated planets. 1284 of these have not yet been
validated or confirmed by other methods. In addition, we identify 428 KOIs
likely to be false positives that have not yet been identified as such, though
some of these may be a result of unidentified transit timing variations. A side
product of these calculations is full stellar property posterior samplings for
every host star, modeled as single, binary, and triple systems. These
calculations use 'vespa', a publicly available Python package able to be easily
applied to any transiting exoplanet candidate.


title: From the Sinai's walk to the Brox diffusion using bilinear forms

abstract:
  Using the generators, we establish a connection between the Sinai's random
walk and the so-called Brox process. We first find the Dirichlet form of the
Brox diffusion, and then prove that it is the limit of the Dirichlet form of
the Sinai's random walk. This also gives a natural way to connect between the
Brox diffusion and the Brownian motion.


title: When Do Luxury Cars Hit the Road? Findings by A Big Data Approach

abstract:
  In this paper, we focus on studying the appearing time of different kinds of
cars on the road. This information will enable us to infer the life style of
the car owners. The results can further be used to guide marketing towards car
owners. Conventionally, this kind of study is carried out by sending out
questionnaires, which is limited in scale and diversity. To solve this problem,
we propose a fully automatic method to carry out this study. Our study is based
on publicly available surveillance camera data. To make the results reliable,
we only use the high resolution cameras (i.e. resolution greater than $1280
\times 720$). Images from the public cameras are downloaded every minute. After
obtaining 50,000 images, we apply faster R-CNN (region-based convoluntional
neural network) to detect the cars in the downloaded images and a fine-tuned
VGG16 model is used to recognize the car makes. Based on the recognition
results, we present a data-driven analysis on the relationship between car
makes and their appearing times, with implications on lifestyles.


title:
A unified model of grain alignment: radiative alignment of interstellar
  grains with magnetic inclusions

abstract:
  The radiative torque (RAT) alignment of interstellar grains with ordinary
paramagnetic susceptibilities has been supported by earlier studies. The
alignment of such grains depends on the so-called RAT parameter $q^{\max}$ that
is determined by the grain shape. In this paper, we elaborate our model of RAT
alignment for grains with enhanced magnetic susceptibility due to iron
inclusions, such that RAT alignment is magnetically enhanced for which we term
MRAT mechanism. Such grains can get aligned with high angular momentum at the
so-called high-J attractor points, achieving a high degree of alignment. Using
our analytical model of RATs we derive the critical value of the magnetic
relaxation parameter $\delta_{m}$ to produce high-J attractor points as
functions of $q^{\max}$ and the anisotropic radiation angle relative to the
magnetic field $\psi$. We find that if about $10\%$ of total iron abundance
present in silicate grains are forming iron clusters, it is sufficient to
produce high-J attractor points for all reasonable values of $q^{\max}$. To
calculate the degree of grain alignment, we carry out numerical simulations of
MRAT alignment by including stochastic excitations from gas collisions and
magnetic fluctuations. We show that large grains can achieve perfect alignment
when the high-J attractor point is present, regardless of the values of
$q^{\max}$. Our obtained results pave the way for physical modeling of
polarized thermal dust emission as well as magnetic dipole emission. We also
find that millimeter-sized grains in accretion disks may be aligned with the
magnetic field if they are incorporated with iron nanoparticles.


title:
Photoenhanced spin/valley polarization and tunneling magnetoresistance
  in ferromagnetic-normal-ferromagnetic silicene junction

abstract:
  We theoretically demonstrate a simple way to significantly enhance the
spin/valley polarizations and tunnel- ing magnetoresistnace (TMR) in a
ferromagnetic-normal-ferromagnetic (FNF) silicene junction by applying a
circularly polarized light in off-resonant regime to the second ferromagnetic
(FM) region. We show that the fully spin-polarized current can be realized in
certain ranges of light intensity. Increasing the incident energy in the
presence of light will induce a transition of perfect spin polarization from
positive to negative or vice versa depending on magnetic configuration
(parallel or anti-parallel) of FNF junction. Additionally, under a circularly
polarized light, valley polarization is very sensitive to electric field and
the perfect valley polarization can be achieved even when staggered electric
field is much smaller than exchange field. The most important result we would
like to emphasize in this paper is that the perfect spin polarization and 100%
TMR induced by a circularly polarized light are completely independent of
barrier height in normal region. Furthermore, the sign reversal of TMR can be
observed when the polarized direction of light is changed. A condition for
observing the 100% TMR is also reported. Our results are expected to be
informative for real applications of FNF silicene junction, especially in
spintronics.


title: Two Dimensional Phosphorus Oxides as Energy and Information Materials

abstract:
  Two-dimensional (2D) black phosphorus (i.e., phosphorene) has become a rising
star in electronics. Recently, 2D phosphorus oxides with higher stability have
been synthesized. In this work, we systematically explore the structures and
properties of 2D phosphorus oxides on the basis of global optimization approach
and first-principles calculations. We find that the structural features of 2D
phosphorus oxides PxOy vary with the oxygen concentration. When the oxygen
content is poor, the most stable 2D PxOy can be obtained by adsorbing O atoms
on phosphorene. However, when the oxygen concentration becomes rich, stable
structures are no longer based on phosphorene and will contain P-O-P motifs.
For the 2D P4O4, we find that it has a direct band gap (about 2.24 eV), good
optical absorption, and high stability in water, suggesting that it may be good
candidate for photochemical water splitting application. Interestingly, 2D P2O3
adopt two possible stable ferroelectric structures (P2O3-I and P2O3-II) as the
lowest energy configurations within a given layer thickness. The electric
polarizations of P2O3-I and P2O3-II are perpendicular and parallel to the
lateral plane, respectively. We propose that 2D P2O3 could be used in a novel
nanoscale multiple-state memory device. Our work suggests that 2D phosphorus
oxides may be excellent functional materials.


title:
Dynamics and thermalization of Bose-Einstein condensate in Sinai
  oscillator trap

abstract:
  We study numerically the evolution of Bose-Einstein condensate in the Sinai
oscillator trap described by the Gross-Pitaevskii equation in two dimensions.
In the absence of interactions this trap mimics the properties of Sinai
billiards where the classical dynamics is chaotic and the quantum evolution is
described by generic properties of quantum chaos and random matrix theory. We
show that, above a certain border, the nonlinear interactions between atoms
lead to the emergence of dynamical thermalization which generates the
statistical Bose-Einstein distribution over eigenmodes of the system without
interactions. Below the thermalization border the evolution remains
quasi-integrable. Such a Sinai oscillator trap, formed by the oscillator
potential and a repulsive disk located in the vicinity of the center, had been
already realized in rst experiments with the Bose-Einstein condensate formation
by Ketterle group in 1995 and we argue that it can form a convenient test bed
for experimental investigations of dynamical of thermalization. Possible links
and implications for Kolmogorov turbulence in absence of noise are also
discussed.


title: Transport Analysis of Infinitely Deep Neural Network

abstract:
  We investigated the feature map inside deep neural networks (DNNs) by
tracking the transport map. We are interested in the role of depth (why do DNNs
perform better than shallow models?) and the interpretation of DNNs (what do
intermediate layers do?) Despite the rapid development in their application,
DNNs remain analytically unexplained because the hidden layers are nested and
the parameters are not faithful. Inspired by the integral representation of
shallow NNs, which is the continuum limit of the width, or the hidden unit
number, we developed the flow representation and transport analysis of DNNs.
The flow representation is the continuum limit of the depth or the hidden layer
number, and it is specified by an ordinary differential equation with a vector
field. We interpret an ordinary DNN as a transport map or a Euler broken line
approximation of the flow. Technically speaking, a dynamical system is a
natural model for the nested feature maps. In addition, it opens a new way to
the coordinate-free treatment of DNNs by avoiding the redundant parametrization
of DNNs. Following Wasserstein geometry, we analyze a flow in three aspects:
dynamical system, continuity equation, and Wasserstein gradient flow. A key
finding is that we specified a series of transport maps of the denoising
autoencoder (DAE). Starting from the shallow DAE, this paper develops three
topics: the transport map of the deep DAE, the equivalence between the stacked
DAE and the composition of DAEs, and the development of the double continuum
limit or the integral representation of the flow representation. As partial
answers to the research questions, we found that deeper DAEs converge faster
and the extracted features are better; in addition, a deep Gaussian DAE
transports mass to decrease the Shannon entropy of the data distribution.


title: Random eigenvalues from a stochastic heat equation

abstract:
  In this paper we prove the convergence of the eigenvalues of a random matrix
that approximates a random Schr\"{o}dinger operator. Originally, such random
operator arises from a stochastic heat equation. The proof uses a detailed
topological analysis of certain spaces of functions where the operators act.


title: Testing Einstein's Equivalence Principle with Short Gamma-ray Bursts

abstract:
  Einstein's equivalence principle (EEP) can be tested by the time delay
between photons with different energies passing through a gravitational field.
As one of the most energetic explosions in the Universe, gamma-ray bursts
(GRBs) provide an effective tool to test the accuracy of EEP. In this paper, we
use the continuous spectra of 20 short GRBs detected by the Swift/BAT to test
the validity of EEP. Taking the duration of GRBs as the upper limit of the time
delay induced by EEP violation (assuming that the high energy photons arrive
later than the low energy photons), the difference of the parameterized
post-Newtonian parameter is constrained with high accuracy. The strictest
constraint, $|\gamma(150~{\rm keV})-\gamma(15~{\rm keV})|<5.59\times 10^{-10}$
from GRB 150101B, is about $1\sim 2$ orders of magnitude tighter than previous
constraints. Moreover, our result is more statistically significant than
previous results because we use the continuous spectra instead of isolated
photons.


title: Causal Evolutions of Bulk Local Excitations from CFT

abstract:
  Bulk localized excited states in an AdS spacetime can be constructed from
Ishibashi states with respect to the global conformal symmetry in the dual CFT.
We study boundary two point functions of primary operators in the presence of
bulk localized excitations in two dimensional CFTs. From two point functions in
holographic CFTs, we observe causal propagations of radiations when the mass of
dual bulk scalar field is close to the BF bound. This behavior for holographic
CFTs is consistent with the locality and causality in classical gravity duals.
We also show that this cannot be seen in free fermion CFTs. Moreover, we find
that the short distance behavior of two point functions is universal and obeys
the relation which generalizes the first law of entanglement entropy.


title: Expediting Support for Social Learning with Behavior Modeling

abstract:
  An important research problem for Educational Data Mining is to expedite the
cycle of data leading to the analysis of student learning processes and the
improvement of support for those processes. For this goal in the context of
social interaction in learning, we propose a three-part pipeline that includes
data infrastructure, learning process analysis with behavior modeling, and
intervention for support. We also describe an application of the pipeline to
data from a social learning platform to investigate appropriate goal-setting
behavior as a qualification of role models. Students following appropriate goal
setters persisted longer in the course, showed increased engagement in hands-on
course activities, and were more likely to review previously covered materials
as they continued through the course. To foster this beneficial social
interaction among students, we propose a social recommender system and show
potential for assisting students in interacting with qualified goal setters as
role models. We discuss how this generalizable pipeline can be adapted for
other support needs in online learning settings.


title:
Fermi energy dependence of first- and second-order Raman spectra in
  graphene: Kohn anomaly and quantum interference effect

abstract:
  Intensity of the first- and the second-order Raman spectra are calculated as
a function of the Fermi energy. We show that the Kohn anomaly effect, i.e.,
phonon frequency renormalization, in the first-order Raman spectra originates
from the phonon renormalization by the interband electron-hole excitation,
whereas in the second-order Raman spectra, a competition between the interband
and intraband electron-hole excitations takes place. By this calculation, we
confirm the presence of different dispersive behaviors of the Raman peak
frequency as a function of the Fermi energy for the first- and the second-order
Raman spectra, as observed in experiments. Moreover, the calculated results of
the Raman intensity sensitively depend on the Fermi energy for both the first-
and the second-order Raman spectra. These results thus also show the importance
of quantum interference effect phenomena.


title: A stabilizer interpretation of double shuffle Lie algebras

abstract:
  According to Racinet's work, the scheme of double shuffle and regularization
relations between cyclotomic analogues of multiple zeta values has the
structure of a torsor over a pro-unipotent $\mathbb Q$-algebraic group
$\sf{DMR}_0$, which is an algebraic subgroup of a pro-unipotent $\mathbb
Q$-algebraic group of outer automorphisms of a free Lie algebra. We show that
the harmonic (stuffle) coproduct of double shuffle theory may be viewed as an
element of a module over the above group, and that $\sf{DMR}_0$ identifies with
the stabilizer of this element. We identify the tangent space at origin of
$\sf{DMR}_0$ with the stabilizer Lie algebra of the harmonic coproduct, thereby
obtaining an alternative proof of Racinet's result stating that this space is a
Lie algebra (the double shuffle Lie algebra).


title: The growth of digital sums of powers of 2

abstract:
  We give an elementary proof that the sum of the digits of $2^n$ in base 10 is
greater than $\log_4 n$. In particular, the limit of the sum of digits of $2^n$
is infinite.


title: Model's sparse representation based on reduced mixed GMsFE basis methods

abstract:
  In this paper, we propose a model's sparse representation based on reduced
mixed generalized multiscale finite element (GMsFE) basis methods for elliptic
PDEs with random inputs. Mixed generalized multiscale finite element method
(GMsFEM) is one of the accurate and efficient approaches to solve multiscale
problem in a coarse grid with local mass conservation. When the inputs of the
PDEs are parameterized by the random variables, the GMsFE basis functions
usually depend on the random parameters. This leads to a large number degree of
freedoms for the mixed GMsFEM and substantially impacts on the computation
efficiency. In order to overcome the difficulty, we develop reduced mixed GMsFE
basis methods such that the multiscale basis functions are independent of the
random parameters and span a low-dimensional space. To this end, a greedy
algorithm is used to find a set of optimal samples from a training set
scattered in the parameter space. Reduced mixed GMsFE basis functions are
constructed based on the optimal samples using two optimal sampling strategies:
basis-oriented cross-validation and proper orthogonal decomposition. Although
the dimension of the space spanned by the reduced mixed GMsFE basis functions
is much smaller than the dimension of the original full order model, the online
computation still depends on the number of coarse degree of freedoms. To
significantly improve the online computation, we integrate the reduced mixed
GMsFE basis methods with sparse tensor approximation and obtain a sparse
representation for the model's outputs. The sparse representation is very
efficient for evaluating the model's outputs for many instances of parameters.
To illustrate the efficacy of the proposed methods, we present a few numerical
examples for multsicale problems with random inputs.


title: Cogalois theory and Drinfeld modules

abstract:
  In this paper we generalize the results of \cite{sanchez} to rank one
Drinfeld modules with class number one. We show that, in the present form,
there does not exist a cogalois theory for Drinfeld modules of rank or class
number larger than one. We also consider the torsion of the Carlitz module for
the extension ${\mathbb{F}}_{q}(T)(\Lambda_{P^{n}})
/{\mathbb{F}}_{q}(T)(\Lambda_{P})$.


title: Kinematics of M51-type interacting galaxies

abstract:
  We present a kinematic catalogue for 21 M51-type galaxies. It consists of
radial velocity distributions observed with long slit spectroscopy along
different position angles, for both the main and satellite components. We
detect deviations from circular motion in most of the main galaxies of each
pair, due to the gravitational perturbation produced by the satellite galaxy.
However some systems do not show significant distortions in their radial
velocity curves. We found some differences between the directions of the
photometric and kinematic major axes in the main galaxies with a bar subsystem.
The Tully-Fisher relation in the B-band and Ks-band for the present sample of
M51-type systems is flatter when compared with isolated galaxies. Using the
radial velocity data set, we built a synthetic normalized radial velocity
distribution, as a reference for future modeling of these peculiar systems. The
synthetic rotation curve, representing the typical rotation curve of the main
galaxy in an M51-type pair, is near to solid body-like inside 4 kpc, and then
is nearly flat within the radial range 5-15 kpc. The relative position angles
between the main galaxy major axis and the companion location, as well as the
velocity difference amplitude, indicate that the orbital motion of the
satellite has a large projection on the main galaxy equatorial plane. In
addition, the radial velocity differences between the two galaxies indicate
that the satellite orbital motion is within the range of amplitudes of the main
galaxy rotation curve and all the M51-type systems studied here except for one,
are gravitationally bounded.


title: A simple identity for derivatives of the arctangent function

abstract:
  We present an identity for the derivatives of the arctangent function as an
alternative to the Adegoke - Layeni - Lampret formula. We show that algorithmic
implementation of the proposed identity can significantly accelerate the
computation since this approach requires no symbolic programming in
determination of the derivatives for the arctangent function.


title: Quantum decay and amplification in a non-Hermitian unstable continuum

abstract:
  The decay of a bound state weakly-coupled to a non-Hermitian tight-binding
unstable continuum, i.e. a continuum of states comprising energies with
positive imaginary part, is theoretically investigated. As compared to quantum
decay in an Hermitian continuum, in the non-Hermitian case a richer scenario
can be found as a result of non-unitary dynamics. Different behaviors are
observed depending on the kind of instability of the continuum. These include
complete or fractional decay in convectively-unstable continua, the absence of
quantum decay for a bound state with energy embedded in the continuum loop, and
unstable (secular) growth with pseudo exponential amplification in the
absolutely-unstable regime. Analytical results are presented for a
nearest-neighboring tight-binding continuum with asymmetric hopping rates
$\kappa_1$ and $\kappa_2$, which shows a transition from convective to absolute
instability when the sign $\kappa_1 \kappa_2$ changes from positive to
negative. In the convectively unstable regime the model describes the decay of
a bound state coupled to a tight-binding lattice with an imaginary gauge field,
which shows a pseudo-Hermitian dynamics. In the absolutely-unstable regime,
pseudo-Hermitian dynamics is broken and a pseudo exponential secular growth is
observed.


title: Energy-Preserving Integrators Applied to Nonholonomic Systems

abstract:
  We introduce energy-preserving integrators for nonholonomic mechanical
systems. We will see that the nonholonomic dynamics is completely determined by
a triple $({\mathcal D}^*, \Pi, \mathcal{H})$, where ${\mathcal D}^*$ is the
dual of the vector bundle determined by the nonholonomic constraints, $\Pi$ is
an almost-Poisson bracket (the nonholonomic bracket) and $\mathcal{H}:{\mathcal
D}^{*}\rightarrow \mathbb{R}$ is a Hamiltonian function. For this triple, we
can apply energy-preserving integrators, in particular, we show that discrete
gradients can be used in the numerical integration of nonholonomic dynamics. By
construction, we achieve preservation of the constraints and of the energy of
the nonholonomic system. Moreover, to facilitate their applicability to complex
systems which cannot be easily transformed into the aforementioned
almost-Poisson form, we rewrite our integrators using just the initial
information of the nonholonomic system. The derived procedures are tested on
several examples: A chaotic quartic nonholonomic mechanical system, the
Chaplygin sleigh system, the Suslov problem and a continuous gearbox driven by
an asymmetric pendulum. Their performace is compared with other standard
methods in nonholonomic dynamics, and their merits verified in practice.


title:
Analytical Approximation for Newtonian Boson Stars in Four and Five
  Dimensions -- A Poor Person's Approach to Rotating Boson Stars

abstract:
  In this paper, we study rotating boson stars in the large coupling limit as
well as in the Newtonian limit. We investigate the equilibrium solutions in
four and five dimensions by adopting some analytical approximations. We show
that the relations among the radius, angular momentum, Newtonian energy and
quadrupole moment (for the four-dimensional solution) of the boson star can be
qualitatively realized for the minimal number of boson star parameters.


title: Nuclear Activity in Circumnuclear Ring Galaxies

abstract:
  We have analyzed the frequency and properties of the nuclear activity in a
sample of galaxies with circumnuclear rings and spirals (CNRs). This sample was
compared with a control sample of galaxies with very similar global properties
but without circumnuclear rings. We discuss the relevance of the results in
regard to the AGN feeding processes and present the following results: (i)
bright companion galaxies seem not to be important for the appearance of CNRs,
which appear to be more related to intrinsic properties of the host galaxies or
to minor merger processes; (ii) the proportion of strong bars in galaxies with
an AGN and a CNR is somewhat higher than the expected ratio of strongly barred
AGN galaxies from the results of Ho and co-workers; (iii) the incidence of
Seyfert activity coeval with CNRs is clearly larger than the rate expected from
the morphological distribution of the host galaxies; (iv) the rate of Sy 2 to
Sy 1 type galaxies with CNRs is about three times larger than the expected
ratio for galaxies without CNRs and is opposite to that predicted by the
geometric paradigm of the classical unified model for AGNs, although it does
support the hy-pothesis that Sy 2 activity is linked to circumnuclear star
formation. The possible selection effects of the sample are discussed, and we
conclude that the detected trends are strong enough to justify high quality
observations of as large as possible sets of galaxies with circumnuclear rings
and their matched control samples.


title:
Practicality of Nested Risk Measures for Dynamic Electric Vehicle
  Charging

abstract:
  We consider the sequential decision problem faced by the manager of an
electric vehicle (EV) charging station, who aims to satisfy the charging demand
of the customer while minimizing cost. Since the total time needed to charge
the EV up to capacity is often less than the amount of time that the customer
is away, there are opportunities to exploit electricity spot price variations
within some reservation window. We formulate the problem as a finite horizon
Markov decision process (MDP) and consider a risk-averse objective function by
optimizing under a dynamic risk measure constructed using a convex combination
of expected value and conditional value at risk (CVaR). It has been recognized
that the objective function of a risk-averse MDP lacks a practical
interpretation. Therefore, in both academic and industry practice, the dynamic
risk measure objective is often not of primary interest; instead, the
risk-averse MDP is used as a computational tool for solving problems with
predefined "practical" risk and reward objectives (termed the base model). In
this paper, we study the extent to which the two sides of this framework are
compatible with each other for the EV setting -- roughly speaking, does a "more
risk-averse" MDP provide lower risk in the practical sense as well? In order to
answer such a question, the effect of the degree of dynamic risk-aversion on
the optimal MDP policy is analyzed. Based on these results, we also propose a
principled approximation approach to finding an instance of the risk-averse MDP
whose optimal policy behaves well under the practical objectives of the base
model. Our numerical experiments suggest that EV charging stations can be
operated at a significantly higher level of profitability if dynamic charging
is adopted and a small amount of risk is tolerated.


title: Wave-Particle Duality in N-Path Interference

abstract:
  Bohr's principle of complementarity, in the context of a two-slit
interference experiment, is understood as the quantitative measures of wave and
particle natures following a duality relation ${\mathcal D}^2+{\mathcal V}^2
\le 1$. Here ${\mathcal D}$ is a measure of distinguishability of the two
paths, and ${\mathcal V}$ is the visibility of interference. It is shown that
such a relation can be formulated for $N-$slit or $N-$path interference too,
with the proviso that the wave nature is characterized by a measure of {\em
coherence} (${\mathcal C}$). This new relation, ${\mathcal D}^2+{\mathcal C}^2
\le 1$ is shown to be tight, and reduces to the known duality relation for the
case $N=2$. A recently introduced similar relation (Bagan et al., 2016) is
shown to be inadequate for the purpose.


title:
A Dynamical Model for Gas Flows, Star Formation, and Nuclear Winds in
  Galactic Centres

abstract:
  We present a dynamical model for gas transport, star formation, and winds in
the nuclear regions of galaxies, focusing on the Milky Way's Central Molecular
Zone (CMZ). In our model angular momentum and mass are transported by a
combination of gravitational and bar-driven acoustic instabilities. In
gravitationally-unstable regions the gas can form stars, and the resulting
feedback drives both turbulence and a wind that ejects mass from the CMZ. We
show that the CMZ is in a quasi-steady state where mass deposited at large
radii by the bar is transported inward to a star-forming, ring-shaped region at
$\sim 100$ pc from the Galactic Centre, where the shear reaches a minimum. This
ring undergoes episodic starbursts, with bursts lasting $\sim 5-10$ Myr
occurring at $\sim 20-40$ Myr intervals. During quiescence the gas in the ring
is not fully cleared, but is driven out of a self-gravitating state by the
momentum injected by expanding supernova remnants. Starbursts also drive a wind
off the star-forming ring, with a time-averaged mass flux comparable to the
star formation rate. We show that our model agrees well with the observed
properties of the CMZ, and places it near a star formation minimum within the
evolutionary cycle. We argue that such cycles of bursty star formation and
winds should be ubiquitous in the nuclei of barred spiral galaxies, and show
that the resulting distribution of galactic nuclei on the Kennicutt-Schmidt
relation is in good agreement with that observed in nearby galaxies.


title:
Application of a thermodynamical framework for transport analysis to the
  derivation of Dirac's value function

abstract:
  From a non-equilibrium thermodynamical framework for transport analysis based
on Onsager's Regression Hypothesis, we derive the value function first
described by Dirac for isotope separation. This application of the framework is
interpreted as both further validation of the transport framework and as a
generalization of Dirac's value function. The framework for the analysis of
transport phenomena is introduced, first. From the entropy of mixing, and in
the presence of gradients in thermodynamic potentials, this framework generates
a dynamical transport model from which Dirac's value function is derived as a
measure of separative work performed. Dirac's value function is thus shown to
be a measure of separative work for systems that are described by the entropy
of mixing. As a further demonstration of its generality, the result is applied
to a two-quantity, single spatial-dimension spin magnetization system.


title:
Gaussian-type Isoperimetric Inequalities in $RCD(K,\infty)$ probability
  spaces for positive $K$

abstract:
  In this paper we adapt the well-estabilished $\Gamma$-calculus techniques to
the context of $RCD(K,\infty)$ spaces, proving Bobkov's local isoperimetric
inequality and, when $K$ is positive, the Gaussian isoperimetric inequality in
this class of spaces. The proof relies on the measure-valued $\Gamma_2$
operator introduced by Savar\'e.


title:
Practical decoy-state round-robin differential-phaseshift quantum key
  distribution

abstract:
  To overcome the signal disturbance from the transmission process, recently, a
new type of protocol named round-robin differential-phase-shift(RRDPS) quantum
key distribution[Nature 509, 475(2014)] is proposed. It can estimate how much
information has leaked to eavesdropper without monitoring bit error rates. In
this paper, we compare the performance of RRDPS using different sources without
and with decoy-state method, such as weak coherent pulses(WCPs) and heralded
single photon source(HSPS). For practical implementations, we propose finite
decoy-state method for RRDPS, the performance of which is close to the infinite
one. Taking WCPs as an example, the three-intensity decoystate protocol can
distribute secret keys over a distance of 128 km when the length of pulses
packet is 32, which confirms the great practical interest of our method.


title:
On the universal cover and the fundamental group of an
  $RCD^*(K,N)$-space

abstract:
  The main goal of the paper is to prove the existence of the universal cover
for $RCD^*(K,N)$-spaces. This generalizes earlier work of C. Sormani and the
second named author on the existence of universal covers for Ricci limit
spaces. As a result, we also obtain several structure results on the (revised)
fundamental group of such spaces. These are the first topological results for
$RCD^{*}(K,N)$-spaces without extra structural-topological assumptions (such as
semi-local simple connectedness).


title:
Comment on "Anomalous Discontinuity at the Percolation Critical Point of
  Active Gels"

abstract:
  In their recent work Sheinman et al. [Phys. Rev. Lett. 114, 098104 (2015)]
introduce a variation of percolation which they call no-enclaves percolation
(NEP). The main claims are 1) the salient physics captured in NEP is closer to
what happens experimentally; 2) The Fisher exponent of NEP, is $\tau=1.82(1)$;
3) Due to the different Fisher exponent, NEP constitutes a universality class
distinct from random percolation (RP). While we fully agree with 1) and found
NEP to be a very interesting variation of random percolation, we disagree with
2) and 3). We will demonstrate that $\tau$ is exactly $2$, directly derivable
from RP, and thus there is no foundation of a new universality class.


title:
Asymptotic Analysis of Multicell Massive MIMO over Rician Fading
  Channels

abstract:
  This work considers the downlink of a multicell massive MIMO system in which
$L$ base stations (BSs) of $N$ antennas each communicate with $K$
single-antenna user equipments randomly positioned in the coverage area. Within
this setting, we are interested in evaluating the sum rate of the system when
MRT and RZF are employed under the assumption that each intracell link forms a
MIMO Rician fading channel. The analysis is conducted assuming that $N$ and $K$
grow large with a non-trivial ratio $N/K$ under the assumption that the data
transmission in each cell is affected by channel estimation errors, pilot
contamination, and an arbitrary large scale attenuation. Numerical results are
used to validate the asymptotic analysis in the finite system regime and to
evaluate the network performance under different settings. The asymptotic
results are also instrumental to get insights into the interplay among system
parameters.


title: Topological spin-transfer drag driven by skyrmion diffusion

abstract:
  We study the spin-transfer drag mediated by the Brownian motion of skyrmions.
The essential idea is illustrated in a two-terminal geometry, in which a thin
film of a magnetic insulator is placed in between two metallic reservoirs. An
electric current in one of the terminals pumps topological charge into the
magnet via a spin-transfer torque. The charge diffuses over the bulk of the
system as stable skyrmion textures. By Onsager's reciprocity, the topological
charge leaving the magnet produces an electromotive force in the second
terminal. The voltage signal decays algebraically with the separation between
contacts, in contrast to the exponential suppression of the spin drag driven by
non-protected excitations like magnons. We show how this topological effect can
be used as a tool to characterize the phase diagram of chiral magnets and thin
films with interfacial Dzyaloshinskii-Moriya interactions.


title:
Preconditioned Implicit-Exponential (IMEXP) Time Integrators for Stiff
  Differential Equations

abstract:
  We propose two new classes of time integrators for stiff DEs: the
implicit-explicit exponential (IMEXP) and the hybrid exponential methods. In
contrast to the existing exponential schemes, the new methods offer significant
computational advantages when used with preconditioners. Any preconditioner can
be used with any of these new schemes. This leads to a broader applicability of
exponential methods. The proof of stability and convergence of these
integrators and numerical demonstration of their efficiency are presented.


title: The irreducible characters of the alternating Hecke algebras

abstract:
  This paper computes the irreducible characters of the alternating Hecke
algebras, which are deformations of the group algebras of the alternating
groups. More precisely, we compute the values of the irreducible characters of
the semisimple alternating Hecke algebras on a set of elements indexed by
minimal length conjugacy class representatives and we show that these character
values determine the irreducible characters completely. As an application we
determine a splitting field for the alternating Hecke algebras in the
semisimple case.


title:
Hierarchical Partition-Based Anonymous Routing Protocol(HPAR) in Manet
  for Efficient and Secure Transmission

abstract:
  Anonymous routing protocols are used in MANET's to hide the nodes from
outsiders in order to protect from various attacks. HPAR partitions the network
area dynamically into zones and chooses nodes in zones randomly as intermediate
relay nodes .This relay nodes help in secure routing. In HPAR anonymity
protection is given to source, destination and route. HPAR have low cost and
provide high level of protection. It has techniques to counter various attacks.


title: A method to measure vacuum birefringence at FCC-ee

abstract:
  It is well-known that the Heisenberg-Euler-Schwinger effective Lagrangian
predicts that a vacuum with a strong static electromagnetic field turns
birefringent. We propose a scheme that can be implemented at the planned
FCC-ee, to measure the nonlinear effect of vacuum birefringence in
electrodynamics arising from QED corrections. Our scheme employs a pulsed laser
to create Compton backscattered photons off a high energy electron beam, with
the FCC-ee as a particularly interesting example. These photons will pass
through a strong static magnetic field, which changes the state of polarization
of the radiation - an effect proportional to the photon energy. This change
will be measured by the use of an aligned single-crystal, where a large
difference in the pair production cross-sections can be achieved. In the
proposed experimental setup the birefringence effect gives rise to a difference
in the number of pairs created in the analyzing crystal, stemming from the fact
that the initial laser light has a varying state of polarization, achieved with
a rotating quarter wave plate. Evidence for the vacuum birefringent effect will
be seen as a distinct peak in the Fourier transform spectrum of the
pair-production rate signal. This tell-tale signal can be significantly above
background with only few hours of measurement, in particular at high energies.


title: Hypersurfaces with central convex cross-sections

abstract:
  A hypersurface $M$ in $\mathbb{R}^n$, $n \geq 4$, has central ovaloid
property if $M$ intersects some hyperplane transversally along an ovaloid and
every such ovaloid on $M$ has central symmetry. We show that a complete,
connected, smooth hypersurface with central ovaloid property must either be a
cylinder over a central ovaloid or else quadric.


title: Generating Random Earthquake Events for PTHA

abstract:
  In order to perform probabilistic tsunami hazard assessment (PTHA) based on
subduction zone earthquakes, it is necessary to start with a catalog of
possible future events along with the annual probability of occurance, or a
probability distribution of such events that can be easily sampled. For
nearfield events, the distribution of slip on the fault can have a significant
effect on the resulting tsunami. We present an approach to defining a
probability distribution based on subdividing the fault geometry into many
subfaults and prescribing a desired covariance matrix relating slip on one
subfault to slip on any other subfault. The eigenvalues and eigenvectors of
this matrix are then used to define a Karhunen-Lo\`eve expansion for random
slip patterns. This is similar to a spectral representation of random slip
based on Fourier series but conforms to a general fault geometry. We show that
only a few terms in this series are needed to represent the features of the
slip distribution that are most important in tsunami generation, first with a
simple one-dimensional example where slip varies only in the down-dip direction
and then on a portion of the Cascadia Subduction Zone.


title:
Magnetic field induced dynamical instabilities in an anti-ferromagnetic
  spin-1 Bose-Einstein condensate

abstract:
  We theoretically investigate four types of dynamical instability, in
particular the periodic and oscillatory type $I_O$, in an anti-ferromagnetic
spin-1 Bose-Einstein condensate in a nonzero magnetic field, by employing the
coupled-mode theory and numerical method. This is in sharp contrast to the
dynamical stability of the same system in zero field. Remarkably, a pattern
transition from a periodic dynamical instability $I_O$ to a uniform one $III_O$
occurs at a critical magnetic field. All the four types of dynamical
instability and the pattern transition are ready to be detected in $^{23}$Na
condensates within the availability of the current experimental techniques.


title: Flavor Violation in the Scalar Sector

abstract:
  In many extensions of the Standard Model, the alignment in flavor space of
the fermion mass matrices and the Yukawa coupling matrices can be broken. The
physical scalar boson $h(125)$ could then have flavor changing couplings. In
this talk, we summarize constraints on such couplings from rare decay searches,
and we investigate current and future detection prospects at the LHC. We
emphasize the importance of several yet unexplored final states: (i) anomalous
single top + $h$ production in $p p \to t h$, arising from $tuh$ couplings (but
not from the more widely studied $tch$ couplings); (ii) $p p \to t + (H^0 \to h
h)$ through $tuh$ couplings in the context of a Two Higgs Doublet Model (2HDM),
perhaps the simplest model with flavor violation in the scalar sector; (iii) $p
p \to H^0 \to \tau\mu$ in the 2HDM context. For all of these processes, we
perform a detailed phenomenological studies. Finally, we comment on the
possibility of flavor violation combined with CP violation, which may be
interesting if the current CMS hint for $h \to \tau\mu$ gets corroborated.


title:
Tight Chromatic Number for a class of Graphs with two forbidden
  subgraphs

abstract:
  Although the chromatic number of a graph is not known in general, attempts
have been made to find good bounds for the number. Here we prove that for a
graph G with two forbidden subgraphs and maximum degree less than or equal to
2{\omega} - 3, {\chi} equals its maximum clique size. We also give examples to
show that the condition is necessary.


title: Numerical Studies on Time Resolution of Micro-Pattern Gaseous Detectors

abstract:
  The Micro-Pattern Gaseous Detectors offer excellent spatial and temporal
resolution in harsh radiation environments of high-luminosity colliders. In
this work, an attempt has been made to establish an algorithm for estimating
the time resolution of different MPGDs. It has been estimated numerically on
the basis of two aspects, statistics and distribution of primary electrons and
their diffusion in gas medium, while ignoring their multiplication. The effect
of detector design parameters, field configuration and the composition of gas
mixture on the resolution have also been investigated. Finally, a modification
in the numerical approach considering the threshold limit of detecting the
signal has been done and tested for the RPC detector for its future
implementation in case of MPGDs.


title: Critical window for the configuration model: finite third moment degrees

abstract:
  We investigate the component sizes of the critical configuration model, as
well as the related problem of critical percolation on a supercritical
configuration model. We show that, at criticality, the finite third moment
assumption on the asymptotic degree distribution is enough to guarantee that
the sizes of the largest connected components are of the order $n^{2/3}$ and
the re-scaled component sizes (ordered in a decreasing manner) converge to the
ordered excursion lengths of an inhomogeneous Brownian Motion with a parabolic
drift. We use percolation to study the evolution of these component sizes while
passing through the critical window and show that the vector of percolation
cluster-sizes, considered as a process in the critical window, converge to the
multiplicative coalescent process in the sense of finite dimensional
distributions. This behavior was first observed for Erd\H{o}s-R\'enyi random
graphs by Aldous (1997) and our results provide support for the empirical
evidences that the nature of the phase transition for a wide array of
random-graph models are universal in nature. Further, we show that the
re-scaled component sizes and surplus edges converge jointly under a strong
topology, at each fixed location of the scaling window.


title: An Efficient and Flexible Spike Train Model via Empirical Bayes

abstract:
  Accurate statistical models of neural spike responses can characterize the
information carried by neural populations. But the limited samples of spike
counts during recording usually result in model overfitting. Besides, current
models assume spike counts to be Poisson-distributed, which ignores the fact
that many neurons demonstrate over-dispersed spiking behaviour. Although the
Negative Binomial Generalized Linear Model (NB-GLM) provides a powerful tool
for modeling over-dispersed spike counts, the maximum likelihood-based standard
NB-GLM leads to highly variable and inaccurate parameter estimates. Thus, we
propose a hierarchical parametric empirical Bayes method to estimate the neural
spike responses among neuronal population. Our method integrates both
Generalized Linear Models (GLMs) and empirical Bayes theory, which aims to (1)
improve the accuracy and reliability of parameter estimation, compared to the
maximum likelihood-based method for NB-GLM and Poisson-GLM; (2) effectively
capture the over-dispersion nature of spike counts from both simulated data and
experimental data; and (3) provide insight into both neural interactions and
spiking behaviours of the neuronal populations. We apply our approach to study
both simulated data and experimental neural data. The estimation of simulation
data indicates that the new framework can accurately predict mean spike counts
simulated from different models and recover the connectivity weights among
neural populations. The estimation based on retinal neurons demonstrate the
proposed method outperforms both NB-GLM and Poisson-GLM in terms of the
predictive log-likelihood of held-out data. Codes are available in
https://doi.org/10.5281/zenodo.4704423


title:
Finite Commutative Rings with a MacWilliams Type Relation for the
  m-Spotty Hamming Weight Enumerators

abstract:
  Let $R$ be a finite commutative ring. We prove that a MacWilliams type
relation between the m-spotty weight enumerators of a linear code over $R$ and
its dual hold, if and only if, $R$ is a Frobenius (equivalently,
Quasi-Frobenius) ring, if and only if, the number of maximal ideals and minimal
ideals of $R$ are the same, if and only if, for every linear code $C$ over $R$,
the dual of the dual $C$ is $C$ itself. Also as an intermediate step, we
present a new and simpler proof for the commutative case of Wood's theorem
which states that $R$ has a generating character if and only if $R$ is a
Frobenius ring.


title:
Electric-field-induced interferometric resonance of a one-dimensional
  spin-orbit-coupled electron

abstract:
  We consider a one-dimensional spin-orbit-coupled nanowire quantum dot, driven
by external electric and magnetic fields, and theoretically formulate an
electric mechanism to interfere its electron orbits. Owing to the existence of
spin-orbit coupling and a pulsed electric field, different spin-orbit states
are shown to interfere with each other, generating intriguing
interference-resonant patterns. We also reveal that an in-plane magnetic field
does not affect the strength interval of any neighboring resonant peaks, but
contributes a weak shift of each peak, which is sensitive to the direction of
the magnetic field. We find that this proposed external-field-controlled scheme
should be regarded as a new type of quantum-dot-based interferometry. Finally,
this interferometry has an important application in precisely measuring
relative experimental parameters, such as the Rashba and Dresselhaus
spin-orbit-coupling strengths, as well as the Lande-g factor.


title:
A Large Scale, Low Frequency Murchison Widefield Array Survey of
  Galactic HII regions between 260< l <\340

abstract:
  We have compiled a catalogue of HII regions detected with the Murchison
Widefield Array (MWA) between 72 and 231MHz. The multiple frequency bands
provided by the MWA allow us identify the characteristic spectrum generated by
the thermal Bremsstrahlung process in HII regions. We detect 302 HII regions
between 260 < l < 340 and report on the positions, sizes, peak, integrated flux
density, and spectral indices of these HII regions. By identifying the point at
which HII regions transition from the optically thin to thick regime we derive
the physical properties including the electron density, ionised gas mass and
ionising photon flux, towards 61 HII regions. This catalogue of HII regions
represents the most extensive and uniform low frequency survey of HII regions
in the Galaxy to date.


title:
Recent Progress in Shearlet Theory: Systematic Construction of Shearlet
  Dilation Groups, Characterization of Wavefront Sets, and New Embeddings

abstract:
  The class of generalized shearlet dilation groups has recently been developed
to allow the unified treatment of various shearlet groups and associated
shearlet transforms that had previously been studied on a case-by-case basis.
We consider several aspects of these groups: First, their systematic
construction from associative algebras, secondly, their suitability for the
characterization of wavefront sets, and finally, the question of constructing
embeddings into the symplectic group in a way that intertwines the
quasi-regular representation with the metaplectic one. For all questions, it is
possible to treat the full class of generalized shearlet groups in a
comprehensive and unified way, thus generalizing known results to an infinity
of new cases. Our presentation emphasizes the interplay between the algebraic
structure underlying the construction of the shearlet dilation groups, the
geometric properties of the dual action, and the analytic properties of the
associated shearlet transforms.


title:
A new set of equations describing immiscible two-phase flow in isotropic
  porous media

abstract:
  Based on non-equilibrium thermodynamics we derive a set of general equations
relating the partial volumetric flow rates to each other and to the total
volumetric flow rate in immiscible two-phase flow in porous media. These
equations together with the conservation of saturation reduces the immiscible
two-phase flow problem to a single-phase flow problem of a complex fluid. We
discuss the new equation in terms of the relative permeability equations. We
test the equations on model systems, both analytically and numerically.


title:
The evolution of the [OII], H{\beta} and [OIII] emission-line luminosity
  functions over the last nine billions years

abstract:
  Emission line galaxies are one of the main tracers of the large-scale
structure to be targeted by the next-generation dark energy surveys. To provide
a better understanding of the properties and statistics of these galaxies, we
have collected spectroscopic data from the VVDS and DEEP2 deep surveys and
estimated the galaxy luminosity functions (LFs) of three distinct emission
lines, [OII] ($0.5 < z < 1.3$), H{\beta} ($0.3 < z < 0.8$) and [OIII] ($0.3 < z
< 0.8$). Our measurements are based on 35,639 emission line galaxies and cover
a volume of $\sim10^7$Mpc$^3$. We present the first measurement of the H{\beta}
LF at these redshifts. We have also compiled LFs from the literature that were
based on independent data or covered different redshift ranges, and we fit the
entire set over the whole redshift range with analytic Schechter and Saunders
models, assuming a natural redshift dependence of the parameters. We find that
the characteristic luminosity ($L_*$) and density ($\phi_*$) of all LFs
increase with redshift. Using the Schechter model over the redshift ranges
considered, we find that, for [OII] emitters, the characteristic luminosity
$L_*(z=0.5)=3.2\times10^{41}$ erg/s increases by a factor of $2.7 \pm 0.2$ from
z=0.5 to 1.3; for H{\beta} emitters $L_*(z=0.3)=1.3\times10^{41}$ erg/s
increases by a factor of $2.0 \pm 0.2$ from z=0.3 to 0.8; and for [OIII]
emitters $L_*(z=0.3)=7.3\times10^{41}$ erg/s increases by a factor of $3.5 \pm
0.4$ from z=0.3 to 0.8.


title: Nonequilibrium physics aspects of probabilistic cellular automata

abstract:
  Probabilistic cellular automata (PCA) are used to model a variety of discrete
spatially extended systems undergoing parallel-updating. We propose an
embedding of a number of classical nonequilibrium concepts in the PCA-world. We
start from time-symmetric PCA, satisfying detailed balance, and we give their
Kubo formula for linear response. Close-to-detailed balance we investigate the
form of the McLennan distribution and the minimum entropy production principle.
More generally, when time-symmetry is broken in the stationary process, there
is a fluctuation symmetry for a corresponding entropy flux. For linear response
around nonequilibria we also give the appropriate formula which is now not only
entropic in nature.


title: Performance Analysis of the Gradient Comparator LMS Algorithm

abstract:
  The sparsity-aware zero attractor least mean square (ZA-LMS) algorithm
manifests much lower misadjustment in strongly sparse environment than its
sparsity-agnostic counterpart, the least mean square (LMS), but is shown to
perform worse than the LMS when sparsity of the impulse response decreases. The
reweighted variant of the ZA-LMS, namely RZA-LMS shows robustness against this
variation in sparsity, but at the price of increased computational complexity.
The other variants such as the l 0 -LMS and the improved proportionate
normalized LMS (IPNLMS), though perform satisfactorily, are also
computationally intensive. The gradient comparator LMS (GC-LMS) is a practical
solution of this trade-off when hardware constraint is to be considered. In
this paper, we analyse the mean and the mean square convergence performance of
the GC-LMS algorithm in detail. The analyses satisfactorily match with the
simulation results.


title:
Adaptive Combination of l0 LMS Adaptive Filters for Sparse System
  Identification in Fluctuating Noise Power

abstract:
  Recently, the l0-least mean square (l0-LMS) algorithm has been proposed to
identify sparse linear systems by employing a sparsity-promoting continuous
function as an approximation of l0 pseudonorm penalty. However, the performance
of this algorithm is sensitive to the appropriate choice of the some parameter
responsible for the zero-attracting intensity. The optimum choice for this
parameter depends on the signal-to-noise ratio (SNR) prevailing in the system.
Thus, it becomes difficult to fix a suitable value for this parameter,
particularly in a situation where SNR fluctuates over time. In this work, we
propose several adaptive combinations of differently parameterized l0-LMS to
get an overall satisfactory performance independent of the SNR, and discuss
some issues relevant to these combination structures. We also demonstrate an
efficient partial update scheme which not only reduces the number of
computations per iteration, but also achieves some interesting performance gain
compared with the full update case. Then, we propose a new recursive least
squares (RLS)-type rule to update the combining parameter more efficiently.
Finally, we extend the combination of two filters to a combination of M number
adaptive filters, which manifests further improvement for M > 2.


title:
Coherently coupling distinct spin ensembles through a high-$T_c$
  superconducting resonator

abstract:
  The problem of coupling multiple spin ensembles through cavity photons is
revisited by using PyBTM organic radicals and a high-$T_c$ superconducting
coplanar resonator. An exceptionally strong coupling is obtained and up to
three spin ensembles are simultaneously coupled. The ensembles are made
physically distinguishable by chemically varying the $g$ factor and by
exploiting the inhomogeneities of the applied magnetic field. The coherent
mixing of the spin and field modes is demonstrated by the observed multiple
anticrossing, along with the simulations performed within the input-output
formalism, and quantified by suitable entropic measures.


title: Natural (non-)informative priors for skew-symmetric distributions

abstract:
  In this paper, we present an innovative method for constructing proper priors
for the skewness (shape) parameter in the skew-symmetric family of
distributions. The proposed method is based on assigning a prior distribution
on the perturbation effect of the shape parameter, which is quantified in terms
of the Total Variation distance. We discuss strategies to translate prior
beliefs about the asymmetry of the data into an informative prior distribution
of this class. We show via a Monte Carlo simulation study that our
noninformative priors induce posterior distributions with good frequentist
properties, similar to those of the Jeffreys prior. Our informative priors
yield better results than their competitors from the literature. We also
propose a scale- and location-invariant prior structure for models with unknown
location and scale parameters and provide sufficient conditions for the
propriety of the corresponding posterior distribution. Illustrative examples
are presented using simulated and real data.


title: Spatial and kinematic segregation in star cluster merger remnants

abstract:
  Globular clusters which exhibit chemical and dynamical complexity have been
suggested to be the stripped nuclei of dwarf galaxies (e.g., M54, $\omega$
Cen). We use $N$-body simulations of nuclear star clusters forming via the
mergers of star clusters to explore the persistence of substructure in the
phase space. We find that the observed level of differentiation is difficult to
reconcile with the observed if nuclear clusters form wholly out of the mergers
of star clusters. Only the star clusters that merged most recently retain
sufficiently distinct kinematics to be distinguishable from the rest of the
nuclear cluster though the critical factor is the number of merger events not
the elapsed time. In situ star formation must therefore be included to explain
the observed properties of nuclear star clusters, in good agreement with
previous results.


title: An Algorithm for Koml\'os Conjecture Matching Banaszczyk's bound

abstract:
  We consider the problem of finding a low discrepancy coloring for sparse set
systems where each element lies in at most t sets. We give an efficient
algorithm that finds a coloring with discrepancy O((t log n)^{1/2}), matching
the best known non-constructive bound for the problem due to Banaszczyk. The
previous algorithms only achieved an O(t^{1/2} log n) bound. The result also
extends to the more general Koml\'{o}s setting and gives an algorithmic
O(log^{1/2} n) bound.


title: Complete spectral data for analytic Anosov maps of the torus

abstract:
  Using analytic properties of Blaschke factors we construct a family of
analytic hyperbolic diffeomorphisms of the torus for which the spectral
properties of the associated transfer operator acting on a suitable Hilbert
space can be computed explicitly. As a result, we obtain explicit expressions
for the decay of correlations of analytic observables without resorting to any
kind of perturbation argument.


title:
The effect of spacers on the performance of Micromegas detectors: a
  numerical investigation

abstract:
  Micromegas detector is considered to be a promising candidate for a large
variety of high-rate experiments. Micromegas of various geometries have already
been established as appropriate for these experiments for their performances in
terms of gas gain uniformity, energy and space point resolution, and their
capability to efficiently pave large read-out surfaces with minimum dead zone.
The present work investigates the effect of spacers on different detector
characteristics of Micromegas detectors having various amplification gaps and
mesh hole pitches. Numerical simulation has been used as a tool of exploration
to evaluate the effect of such dielectric material on detector performance.
Some of the important and fundamental characteristics such as electron
transparency, gain and signal of the Micromegas detector have been estimated.


title: Separating Topological Noise from Features using Persistent Entropy

abstract:
  In this paper, we derive a simple method for separating topological noise
from topological features using a novel measure for comparing persistence
barcodes called persistent entropy.


title: On Mobile Cloud for Smart City Applications

abstract:
  This paper is devoted to mobile cloud services in Smart City projects. As per
mobile cloud computing paradigm, the data processing and storage are moved from
the mobile device to a cloud. In the same time, Smart City services typically
contain a set of applications with data sharing options. Most of the services
in Smart Cities are actually mashups combined data from several sources. This
means that access to all available data is vital to the services. And the
mobile cloud is vital because the mobile terminals are one of the main sources
for data gathering. In our work, we discuss criteria for selecting mobile cloud
services.


title:
Learning theory estimates with observations from general stationary
  stochastic processes

abstract:
  This paper investigates the supervised learning problem with observations
drawn from certain general stationary stochastic processes. Here by
\emph{general}, we mean that many stationary stochastic processes can be
included. We show that when the stochastic processes satisfy a generalized
Bernstein-type inequality, a unified treatment on analyzing the learning
schemes with various mixing processes can be conducted and a sharp oracle
inequality for generic regularized empirical risk minimization schemes can be
established. The obtained oracle inequality is then applied to derive
convergence rates for several learning schemes such as empirical risk
minimization (ERM), least squares support vector machines (LS-SVMs) using given
generic kernels, and SVMs using Gaussian kernels for both least squares and
quantile regression. It turns out that for i.i.d.~processes, our learning rates
for ERM recover the optimal rates. On the other hand, for non-i.i.d.~processes
including geometrically $\alpha$-mixing Markov processes, geometrically
$\alpha$-mixing processes with restricted decay, $\phi$-mixing processes, and
(time-reversed) geometrically $\mathcal{C}$-mixing processes, our learning
rates for SVMs with Gaussian kernels match, up to some arbitrarily small extra
term in the exponent, the optimal rates. For the remaining cases, our rates are
at least close to the optimal rates. As a by-product, the assumed generalized
Bernstein-type inequality also provides an interpretation of the so-called
"effective number of observations" for various mixing processes.


title:
The renormalization method based on the Taylor expansion and
  applications for asymptotic analysis

abstract:
  Based on the Taylor expansion, we propose a renormalization method for
asymptotic analysis. The standard renormalization group (RG) method for
asymptotic analysis can be derived out from this new method, and hence the
mathematical essence of the RG method is also recovered. The biggest advantage
of the proposed method is that the secular terms in perturbation series are
automatically eliminated, but in usual perturbation theory, we need more
efforts and tricks to eliminate these terms. At the same time, the mathematical
foundation of the method is simple and the logic of the method is very clear,
therefore, it is very easy in practice. As application, we obtain the uniform
valid asymptotic solutions to some problems including vector field, boundary
layer and boundary value problems of nonlinear wave equations. Moreover, we
discuss the normal form theory and reduction equations of dynamical systems.
Furthermore, by combining the topological deformation and the RG method, a
modified method namely the homotopy renormalization method (for simplicity,
HTR) wasproposed to overcome the weaknesses of the standard RG method. In this
HTR method, since there is a freedom to choose the first order approximate
solution in perturbation expansion, we can improve the global solution. In
particular, for those equations including no a small parameter, the HTR method
can also be applied. Some concrete applications including multi-solutions
problems, the forced Duffing equation and the Blasius equation are given.

categories: math-ph cond-mat.dis-nn hep-th math.CA math.DS math.MP


title:
Search for Majorana Neutrinos near the Inverted Mass Hierarchy Region
  with KamLAND-Zen

abstract:
  We present an improved search for neutrinoless double-beta ($0\nu\beta\beta$)
decay of $^{136}$Xe in the KamLAND-Zen experiment. Owing to purification of the
xenon-loaded liquid scintillator, we achieved a significant reduction of the
$^{110m}$Ag contaminant identified in previous searches. Combining the results
from the first and second phase, we obtain a lower limit for the
$0\nu\beta\beta$ decay half-life of $T_{1/2}^{0\nu} > 1.07 \times 10^{26}$ yr
at 90% C.L., an almost sixfold improvement over previous limits. Using commonly
adopted nuclear matrix element calculations, the corresponding upper limits on
the effective Majorana neutrino mass are in the range 61-165 meV. For the most
optimistic nuclear matrix elements, this limit reaches the bottom of the
quasi-degenerate neutrino mass region.


title: Top Quark Properties Measurements in CMS

abstract:
  Recent top quark properties measurements made with the CMS detector at the
LHC are presented. The measurements summarized include spin correlation of top
quark pairs, asymmetries, top quark mass, and the underlying event in top quark
pair events. The results are compared to the standard model predictions and new
physics models.


title: Path-Additions of Graphs

abstract:
  Path-addition is an operation that takes a graph and adds an internally
vertex-disjoint path between two vertices together with a set of supplementary
edges. Path-additions are just the opposite of taking minors.
  We show that some classes of graphs are closed under path-addition, including
non-planar, right angle crossing, fan-crossing free, quasi-planar, (aligned)
bar 1-visibility, and interval graphs, whereas others are not closed, including
all subclasses of planar graphs, bounded treewidth, k-planar, fan-planar,
outer-fan planar, outer-fan-crossing free, and bar (1,j)-visibility graphs.


title:
Compact Hash Codes for Efficient Visual Descriptors Retrieval in Large
  Scale Databases

abstract:
  In this paper we present an efficient method for visual descriptors retrieval
based on compact hash codes computed using a multiple k-means assignment. The
method has been applied to the problem of approximate nearest neighbor (ANN)
search of local and global visual content descriptors, and it has been tested
on different datasets: three large scale public datasets of up to one billion
descriptors (BIGANN) and, supported by recent progress in convolutional neural
networks (CNNs), also on the CIFAR-10 and MNIST datasets. Experimental results
show that, despite its simplicity, the proposed method obtains a very high
performance that makes it superior to more complex state-of-the-art methods.


title: Carbon Nitride Frameworks and Dense Crystalline Polymorphs

abstract:
  We used ab initio random structure searching (AIRSS) to investigate
polymorphism in C3N4 carbon nitride as a function of pressure. Our calculations
reveal new framework structures, including a particularly stable chiral
polymorph of space group P43212 containing mixed sp2 and sp3-bonding, that we
have produced experimentally and recovered to ambient conditions. As pressure
is increased a sequence of structures with fully sp3-bonded C atoms and
three-fold coordinated N atoms is predicted, culminating in a dense Pnma phase
above 250 GPa. Beyond 650 GPa we find that C3N4 becomes unstable to
decomposition into diamond and pyrite-structured CN2.


title:
Sharp Sufficient Conditions for Stable Recovery of Block Sparse Signals
  by Block Orthogonal Matching Pursuit

abstract:
  In this paper, we use the block orthogonal matching pursuit (BOMP) algorithm
to recover block sparse signals $\x$ from measurements $\y=\A\x+\v$, where $\v$
is an $\ell_2$-bounded noise vector (i.e., $\|\v\|_2\leq \epsilon$ for some
constant $\epsilon$). We investigate some sufficient conditions based on the
block restricted isometry property (block-RIP) for exact (when $\v=\0$) and
stable (when $\v\neq\0$) recovery of block sparse signals $\x$. First, on the
one hand, we show that if $\A$ satisfies the block-RIP with
$\delta_{K+1}<1/\sqrt{K+1}$, then every block $K$-sparse signal $\x$ can be
exactly or stably recovered by BOMP in $K$ iterations. On the other hand, we
show that, for any $K\geq 1$ and $1/\sqrt{K+1}\leq \delta<1$, there exists a
matrix $\A$ satisfying the block-RIP with $\delta_{K+1}=\delta$ and a block
$K$-sparse signal $\x$ such that BOMP may fail to recover $\x$ in $K$
iterations. Then, we study some sufficient conditions for recovering block
$\alpha$-strongly-decaying $K$-sparse signals. We show that if $\A$ satisfies
the block-RIP with $\delta_{K+1}<\sqrt{2}/2$, then every
$\alpha$-strongly-decaying block $K$-sparse signal can be exactly or stably
recovered by BOMP in $K$ iterations under some conditions on $\alpha$. Our
newly found sufficient condition on the block-RIP of $\A$ is less restrictive
than that for $\ell_1$ minimization for this special class of sparse signals.
Furthermore, for any $K\geq 1$, $\alpha>1$ and $\sqrt{2}/2\leq \delta<1$, the
recovery of $\x$ may fail in $K$ iterations for a sensing matrix $\A$ which
satisfies the block-RIP with $\delta_{K+1}=\delta$. Finally, we study some
sufficient conditions for partial recovery of block sparse signals.
Specifically, if $\A$ satisfies the block-RIP with $\delta_{K+1}<\sqrt{2}/2$,
then BOMP is guaranteed to recover some blocks of $\x$ if these blocks satisfy
a sufficient condition.


title: Generalized Kato-Riesz decomposition

abstract:
  We shall say that a bounded linear operator $T$ acting on a Banach space $X$
admits a generalized Kato-Riesz decomposition if there exists a pair of
$T$-invariant closed subspaces $(M,N)$ such that $X=M\oplus N$, the reduction
$T_M$ is Kato and $T_N$ is Riesz. In this paper we define and investigate the
generalized Kato-Riesz spectrum of an operator. For $T$ is said to be
generalized Drazin-Riesz invertible if there exists a bounded linear operator
$S $ acting on $X$ such that $TS=ST$, $STS=S$, $ TST-T$ is Riesz. We
investigate generalized Drazin-Riesz invertible operators and also,
characterize bounded linear operators which can be expressed as a direct sum of
a Riesz operator and a bounded below (resp. surjective, upper (lower)
semi-Fredholm, Fredholm, upper (lower) semi-Weyl, Weyl) operator. In particular
we characterize the single-valued extension property at a point
$\lambda_0\in{\mathbb C}$ in the case that $\lambda_0-T$ admits a generalized
Kato-Riesz decomposition.


title: Investigation of Ion Backflow in Bulk Micromegas Detectors

abstract:
  The operation of gas detectors is often limited by secondary effects,
originating from avalanche-induced photons and ions. Ion backflow is one of the
effects limiting the operation of a gas detector at high flux, by giving rise
to space charge which disturbs the electric field locally. For the Micromegas
detector, a large fraction of the secondary positive ions created in the
avalanche can be stopped at the micro-mesh. The present work involves
measurements of the ion backflow fraction (using an experimental setup
comprising of two drift planes) in bulk Micromegas detectors as a function of
detector design parameters. These measured characteristics have also been
compared in detail to numerical simulations using the Garfield framework that
combines packages such as neBEM, Magboltz and Heed. Further, the effect of
using a second micro-mesh on ion backflow and other parameters has been studied
numerically.


title: The intrinsic "sense" of stochastic differential equations

abstract:
  A free choice of the integration sense would lead to the paradox that the
number of possible equations (thus of solutions for a given model) can vary
under a mere change of the variables. This is shown by a specific change which
neutralizes the sense (by establishing a constant coupling with the noise). Its
inverse singles out the Stratonovich sense, by means of the Ito formula.


title: Finite W-algebras for gl_N

abstract:
  We study the quantum finite W-algebras W(gl_N,f), associated to the Lie
algebra gl_N, and its arbitrary nilpotent element f. We construct for such an
algebra an r_1 x r_1 matrix L(z) of Yangian type, where r_1 is the number of
maximal parts of the partition corresponding to f. The matrix L(z) is the
quantum finite analogue of the operator of Adler type which we introduced in
the classical affine setup. As in the latter case, the matrix L(z) is obtained
as a generalized quasideterminant. It should encode the whole structure of
W(gl_N,f), including explicit formulas for generators and the commutation
relations among them. We describe in all detail the examples of principal,
rectangular and minimal nilpotent elements.


title: Revisited Design Criteria For STBCs With Reduced Complexity ML Decoding

abstract:
  The design of linear STBCs offering a low-complexity ML decoding using the
well known Sphere Decoder (SD) has been extensively studied in last years. The
first considered approach to derive design criteria for the construction of
such codes is based on the Hurwitz-Radon (HR) Theory for mutual orthogonality
between the weight matrices defining the linear code. This appproach served to
construct new families of codes admitting fast sphere decoding such as
multi-group decodable, fast decodable, and fast-group decodable codes. In a
second Quadratic Form approach, the Fast Sphere Decoding (FSD) complexity of
linear STBCs is captured by a Hurwitz Radon Quadratic Form (HRQF) matrix based
in its essence on the HR Theory. In this work, we revisit the structure of
weight matrices for STBCs to admit Fast Sphere decoding. We first propose novel
sufficient conditions and design criteria for reduced-complexity ML decodable
linear STBCs considering an arbitrary number of antennas and linear STBCs of an
arbitrary coding rate. Then we apply the derived criteria to the three families
of codes mentioned above and provide analytical proofs showing that the FSD
complexity depends only on the weight matrices and their ordering and not on
the channel gains or the number of antennas and explain why the so far used HR
theory-based approaches are suboptimal.


title:
A Measure on the space of Lipschitz isometric maps of a compact
  1-manifold into $\mathbb R^2$

abstract:
  Let $M$ be a compact 1-manifold. Given a continuous function $g:M\to \mathbb
R_+$ we consider the following ordinary differential equation:
$\|\dot{f}(t)\|=g(t)$, where $f:M\to \mathbb R^2$. We construct a probability
measure on the space of almost everywhere differentiable solutions of this
differential equation and study this measure. A solution of this equation can
be viewed as an isometric immersion of a compact 1-manifold into $\mathbb R^2$.
Nash's convergence technique in the proof of isometric $C^1$-immersion theorem
plays an important role in the construction.


title:
Holographic method for site-resolved detection of a 2D array of
  ultracold atoms

abstract:
  We propose a novel approach to site-resolved detection of a 2D gas of
ultracold atoms in an optical lattice. A near resonant laser beam is coherently
scattered by the atomic array and its interference pattern is holographically
recorded by superimposing it with a reference laser beam on a CCD chip. Fourier
transformation of the recorded intensity pattern reconstructs the atomic
distribution in the lattice with single-site resolution. The holographic
detection method requires only a few hundred scattered photons per atom in
order to achieve a high reconstruction fidelity. Therefore, additional cooling
during detection might not be necessary even for light atomic elements such as
lithium.


title:
Giant magnetocaloric effect near room temperature in the
  off-stoichiometric Mn-Co-Ge alloy

abstract:
  We report a giant magnetocaloric effect near room temperature in an
off-stoichiometric Mn-Co-Ge alloy, across the magnetostructural transition. The
isothermal entropy change accompanying this transition has a peak value of
nearly 40 J/kg-K near 297 K and a refrigerant capacity of 270 J/kg with the hot
end at 302.5 K and cold end at 293.5 K. We also present an experimental
protocol to avoid spurious peaks in the magnetocaloric effect across a sharp
first order magnetostructural transition, not confined to Mn-Co-Ge alone, where
metastability during the transition could influence the measured magnetization
and thus the estimated entropy change. The estimated entropy change in the
present off-stoichiometric Mn-Co-Ge alloy is possibly the highest reported
value near room temperature in undoped Mn-Co-Ge alloys and underlines the
potential of the alloy for technological applications in room temperature
magnetic refrigeration.