title:
Experimental investigation of the radial structure of energetic particle
  driven modes

abstract:
  Alfv\'en eigenmodes (AEs) and energetic particle modes (EPMs) are often
excited by energetic particles (EPs) in tokamak plasmas. One of the main open
questions concerning EP driven instabilities is the non-linear evolution of the
mode structure. The aim of the present paper is to investigate the properties
of beta-induced AEs (BAEs) and EP driven geodesic acoustic modes (EGAMs)
observed in the ramp-up phase of off-axis NBI heated ASDEX Upgrade (AUG)
discharges. This paper focuses on the changes in the mode structure of
BAEs/EGAMs during the non-linear chirping phase. Our investigation has shown
that in case of the observed down-chirping BAEs the changes in the radial
structure are smaller than the uncertainty of our measurement. This behaviour
is most probably the consequence of that BAEs are normal modes, thus their
radial structure strongly depends on the background plasma parameters rather
than on the EP distribution. In the case of rapidly upward chirping EGAMs the
analysis consistently shows shrinkage of the mode structure. The proposed
explanation is that the resonance in the velocity space moves towards more
passing particles which have narrower orbit widths.


title: Safe, Remote-Access Swarm Robotics Research on the Robotarium

abstract:
  This paper describes the development of the Robotarium -- a remotely
accessible, multi-robot research facility. The impetus behind the Robotarium is
that multi-robot testbeds constitute an integral and essential part of the
multi-agent research cycle, yet they are expensive, complex, and time-consuming
to develop, operate, and maintain. These resource constraints, in turn, limit
access for large groups of researchers and students, which is what the
Robotarium is remedying by providing users with remote access to a
state-of-the-art multi-robot test facility. This paper details the design and
operation of the Robotarium as well as connects these to the particular
considerations one must take when making complex hardware remotely accessible.
In particular, safety must be built in already at the design phase without
overly constraining which coordinated control programs the users can upload and
execute, which calls for minimally invasive safety routines with provable
performance guarantees.


title: COARA: Code Offloading on Android with AspectJ

abstract:
  Smartphones suffer from limited computational capabilities and battery life.
A method to mitigate these problems is code offloading: executing application
code on a remote server. We introduce COARA, a middleware platform for code
offloading on Android that uses aspect-oriented programming (AOP) with AspectJ.
AOP allows COARA to intercept code for offloading without a customized compiler
or modification of the operating system. COARA requires minimal changes to
application source code, and does not require the application developer to be
aware of AOP. Since state transfer to the server is often a bottleneck that
hinders performance, COARA uses AOP to intercept the transmission of large
objects from the client and replaces them with object proxies. The server can
begin execution of the offloaded application code, regardless of whether all
required objects been transferred to the server. We run COARA with Android
applications from the Google Play store on a Nexus 4 running unmodified Android
4.3 to prove that our platform improves performance and reduces energy
consumption. Our approach yields speedups of 24x and 6x over WiFi and 3G
respectively.


title: Multi-objective design of quantum circuits using genetic programming

abstract:
  Quantum computing is a new way of data processing based on the concept of
quantum mechanics. Quantum circuit design is a process of converting a quantum
gate to a series of basic gates and is divided into two general categories
based on the decomposition and composition. In the second group, using
evolutionary algorithms and especially genetic algorithms, multiplication of
matrix gates was used to achieve the final characteristic of quantum circuit.
Genetic programming is a subfield of evolutionary computing in which computer
programs evolve to solve studied problems. In past research that has been done
in the field of quantum circuits design, only one cost metrics (usually quantum
cost) has been investigated. In this paper for the first time, a
multi-objective approach has been provided to design quantum circuits using
genetic programming that considers the depth and the cost of nearest neighbor
metrics in addition to quantum cost metric. Another innovation of this article
is the use of two-step fitness function and taking into account the equivalence
of global phase in quantum gates. The results show that the proposed method is
able to find a good answer in a short time.


title:
Stability of rigidly rotating supermassive stars against gravitational
  collapse

abstract:
  We revisit secular stability against quasi-radial collapse for rigidly
rotating supermassive stars (SMSs) in general relativity. We suppose that the
SMSs are in a nuclear-burning phase and can be modeled by polytropic equations
of state with the polytropic index $n_p$ slightly smaller than $3$. The
stability is determined in terms of the turning-point method. We find a fitting
formula of the stability condition for the plausible range of $n_p$ ($2.95 \alt
n_p \alt 3$) for SMSs. This condition reconfirms that, while non-rotating SMSs
with mass $\sim 10^5M_\odot$--$10^6M_\odot$ may undergo a
general-relativistically induced quasi-radial collapse, rigidly rotating SMSs
with a ratio of rotational to gravitational potential energy ($\beta$) of $\sim
10^{-2}$ are likely to be stable against collapse unless they are able to
accrete $\sim 5$ times more mass during the (relatively brief) hydrogen-burning
phase of their evolution. We discuss implications of our results.


title: An electronic-game framework for evaluating coevolutionary algorithms

abstract:
  One of the common artificial intelligence applications in electronic games
consists of making an artificial agent learn how to execute some determined
task successfully in a game environment. One way to perform this task is
through machine learning algorithms capable of learning the sequence of actions
required to win in a given game environment. There are several supervised
learning techniques able to learn the correct answer for a problem through
examples. However, when learning how to play electronic games, the correct
answer might only be known by the end of the game, after all the actions were
already taken. Thus, not being possible to measure the accuracy of each
individual action to be taken at each time step. A way for dealing with this
problem is through Neuroevolution, a method which trains Artificial Neural
Networks using evolutionary algorithms. In this article, we introduce a
framework for testing optimization algorithms with artificial agent controllers
in electronic games, called EvoMan, which is inspired in the action-platformer
game Mega Man II. The environment can be configured to run in different
experiment modes, as single evolution, coevolution and others. To demonstrate
some challenges regarding the proposed platform, as initial experiments we
applied Neuroevolution using Genetic Algorithms and the NEAT algorithm, in the
context of competitively coevolving two distinct agents in this game.


title:
Analysis and Optimization of Caching and Multicasting in Large-Scale
  Cache-Enabled Heterogeneous Wireless Networks

abstract:
  Heterogeneous wireless networks (HetNets) provide a powerful approach to meet
the dramatic mobile traffic growth, but also impose a significant challenge on
backhaul. Caching and multicasting at macro and pico base stations (BSs) are
two promising methods to support massive content delivery and reduce backhaul
load in HetNets. In this paper, we jointly consider caching and multicasting in
a large-scale cache-enabled HetNet with backhaul constraints. We propose a
hybrid caching design consisting of identical caching in the macro-tier and
random caching in the pico-tier, and a corresponding multicasting design. By
carefully handling different types of interferers and adopting appropriate
approximations, we derive tractable expressions for the successful transmission
probability in the general region as well as the high signal-to-noise ratio
(SNR) and user density region, utilizing tools from stochastic geometry. Then,
we consider the successful transmission probability maximization by optimizing
the design parameters, which is a very challenging mixed discrete-continuous
optimization problem due to the sophisticated structure of the successful
transmission probability. By using optimization techniques and exploring the
structural properties, we obtain a near optimal solution with superior
performance and manageable complexity. This solution achieves better
performance in the general region than any asymptotically optimal solution,
under a mild condition. The analysis and optimization results provide valuable
design insights for practical cache-enabled HetNets.


title: AGN Coronal Emission models I. The Predicted Radio Emission

abstract:
  Accretion discs in AGN may be associated with coronal gas, as suggested by
their X-ray emission. Stellar coronal emission includes radio emission, and AGN
corona may also be a significant source for radio emission in radio quiet (RQ)
AGN. We calculate the coronal properties required to produce the observed radio
emission in RQ AGN, either from synchrotron emission of power-law (PL)
electrons, or from cyclo-synchrotron emission of hot mildly-relativistic
thermal electrons. We find that a flat spectrum, as observed in about half of
RQ AGN, can be produced by corona with a disc or a spherical configuration,
which extends from the innermost regions out to a pc scale. A spectral break to
an optically thin power-law emission is expected around 300-1000 GHz, as the
innermost corona becomes optically thin. In case of thermal electrons, a sharp
spectral cutoff is expected above the break. The position of the break can be
measured with VLBI observations, which exclude the cold dust emission, and it
can be used to probe the properties of the innermost corona. Assuming
equipartition of the coronal thermal energy density, the PL electrons energy
density, and the magnetic field, we find that the energy density in a disc
corona should scale as $\sim R^{-1.3}$, to get a flat spectrum. In the
spherical case the energy density scales as $\sim R^{-2}$, and is $\sim 4\times
10^{-4}$ of the AGN radiation energy density. In paper II we derive additional
constraints on the coronal parameters from the Gudel-Benz relation, $L_{\rm
Radio}/L_{\rm X-ray}\sim 10^{-5}$, which RQ AGN follow.


title: Multi-Relational Learning at Scale with ADMM

abstract:
  Learning from multiple-relational data which contains noise, ambiguities, or
duplicate entities is essential to a wide range of applications such as
statistical inference based on Web Linked Data, recommender systems,
computational biology, and natural language processing. These tasks usually
require working with very large and complex datasets - e.g., the Web graph -
however, current approaches to multi-relational learning are not practical for
such scenarios due to their high computational complexity and poor scalability
on large data.
  In this paper, we propose a novel and scalable approach for multi-relational
factorization based on consensus optimization. Our model, called ConsMRF, is
based on the Alternating Direction Method of Multipliers (ADMM) framework,
which enables us to optimize each target relation using a smaller set of
parameters than the state-of-the-art competitors in this task.
  Due to ADMM's nature, ConsMRF can be easily parallelized which makes it
suitable for large multi-relational data. Experiments on large Web datasets -
derived from DBpedia, Wikipedia and YAGO - show the efficiency and performance
improvement of ConsMRF over strong competitors. In addition, ConsMRF
near-linear scalability indicates great potential to tackle Web-scale problem
sizes.


title: On Clustered Statistical MIMO Millimeter Wave Channel Simulation

abstract:
  The use of mmWave frequencies is one of the key strategies to achieve the
fascinating 1000x increase in the capacity of future 5G wireless systems. While
for traditional sub-6 GHz cellular frequencies several well-developed
statistical channel models are available for system simulation, similar tools
are not available for mmWave frequencies, thus preventing a fair comparison of
independently developed transmission and reception schemes. In this paper we
provide a simple albeit accurate statistical procedure for the generation of a
clustered MIMO channel model operating at mmWaves, for both the cases of slowly
and rapidly time-varying channels. Matlab scripts for channel generation are
also provided, along with an example of their use.


title: From Many-Particle Interference to Correlation Spectroscopy

abstract:
  We show how robust statistical features of a many-particle quantum state's
two-point correlations after transmission through a multi-mode random scatterer
can be used as a sensitive probe of the injected particles' mutual
indistinguishability. This generalises Hong-Ou-Mandel interference as a
diagnostic tool for many-particle transmission signals across multi-mode random
scatterers. Furthermore, we show how, from such statistical features of the
many-particle interference pattern, information can be deduced on the temporal
structure of the many-particle input state, by inspection of the many-particle
interference with an additional probe particle of tuneable distinguishability.


title: Note on Identities Inspired by New Soft Theorems

abstract:
  The new soft theorems, for both gravity and gauge amplitudes, have inspired a
number of works, including the discovery of new identities related to
amplitudes. In this note, we present the proof and discussion for two sets of
identities. The first set includes an identity involving the half-soft function
which had been used in the soft theorem for one-loop rational gravity
amplitudes, and another simpler identity as its byproduct. The second set
includes two identities involving the KLT momentum kernel, as the consistency
conditions of the KLT relation plus soft theorems for both gravity and gauge
amplitudes. We use the CHY formulation to prove the first identity, and
transform the second one into a convenient form for future discussion.


title:
A Direct Mapping of Max k-SAT and High Order Parity Checks to a Chimera
  Graph

abstract:
  We demonstrate a direct mapping of max k-SAT problems (and weighted max
k-SAT) to a Chimera graph, which is the non-planar hardware graph of the
devices built by D-Wave Systems Inc. We further show that this mapping can be
used to map a similar class of maximum satisfiability problems where the
clauses are replaced by parity checks over potentially large numbers of bits.
The latter is of specific interest for applications in decoding for
communication. We discuss an example in which the decoding of a turbo code,
which has been demonstrated to perform near the Shannon limit, can be mapped to
a Chimera graph. The weighted max k-SAT problem is the most general class of
satisfiability problems, so our result effectively demonstrates how any
satisfiability problem may be directly mapped to a Chimera graph. Our methods
faithfully reproduce the low energy spectrum of the target problems, so
therefore may also be used for maximum entropy inference.


title: Galaxy Redshifts from Discrete Optimization of Correlation Functions

abstract:
  We propose a new method of constraining the redshifts of individual
extragalactic sources based on celestial coordinates and their ensemble
statistics. Techniques from integer linear programming are utilized to optimize
simultaneously for the angular two-point cross- and autocorrelation functions.
Our novel formalism introduced here not only transforms the otherwise
hopelessly expensive, brute-force combinatorial search into a linear system
with integer constraints but also is readily implementable in off-the-shelf
solvers. We adopt Gurobi, a commercial optimization solver, and use Python to
build the cost function dynamically. The preliminary results on simulated data
show potential for future applications to sky surveys by complementing and
enhancing photometric redshift estimators. Our approach is the first
application of integer linear programming to astronomical analysis.


title:
A Characterization of the Non-Uniqueness of Nonnegative Matrix
  Factorizations

abstract:
  Nonnegative matrix factorization (NMF) is a popular dimension reduction
technique that produces interpretable decomposition of the data into parts.
However, this decompostion is not generally identifiable (even up to
permutation and scaling). While other studies have provide criteria under which
NMF is identifiable, we present the first (to our knowledge) characterization
of the non-identifiability of NMF. We describe exactly when and how
non-uniqueness can occur, which has important implications for algorithms to
efficiently discover alternate solutions, if they exist.


title: Symbolic powers of cover ideal of very well-covered and bipartite graphs

abstract:
  Let $G$ be a graph with $n$ vertices and $S=\mathbb{K}[x_1,\dots,x_n]$ be the
polynomial ring in $n$ variables over a field $\mathbb{K}$. Assume that $J(G)$
is the cover ideal of $G$ and $J(G)^{(k)}$ is its $k$-th symbolic power. We
prove that if $G$ is a very well-covered graph such that $J(G)$ has linear
resolution, then $J(G)^{(k)}$ has linear resolution, for every integer $k\geq
1$. We also prove that for a every very well-covered graph $G$, the depth of
symbolic powers of $J(G)$ forms a non-increasing sequence. Finally, we
determine a linear upper bound for the regularity of powers of cover ideal of
bipartite graph.


title: Algebraic Stability of Zigzag Persistence Modules

abstract:
  The stability theorem for persistent homology is a central result in
topological data analysis. While the original formulation of the result
concerns the persistence barcodes of $\mathbb{R}$-valued functions, the result
was later cast in a more general algebraic form, in the language of
\emph{persistence modules} and \emph{interleavings}. In this paper, we
establish an analogue of this algebraic stability theorem for zigzag
persistence modules. To do so, we functorially extend each zigzag persistence
module to a two-dimensional persistence module, and establish an algebraic
stability theorem for these extensions. One part of our argument yields a
stability result for free two-dimensional persistence modules.
  As an application of our main theorem, we strengthen a result of Bauer et al.
on the stability of the persistent homology of Reeb graphs. Our main result
also yields an alternative proof of the stability theorem for level set
persistent homology of Carlsson et al.


title: Depth, Stanley depth and regularity of ideals associated to graphs

abstract:
  Let $\mathbb{K}$ be a field and $S=\mathbb{K}[x_1,\dots,x_n]$ be the
polynomial ring in $n$ variables over $\mathbb{K}$. Let $G$ be a graph with $n$
vertices. Assume that $I=I(G)$ is the edge ideal of $G$ and $J=J(G)$ is its
cover ideal. We prove that ${\rm sdepth}(J)\geq n-\nu_{o}(G)$ and ${\rm
sdepth}(S/J)\geq n-\nu_{o}(G)-1$, where $\nu_{o}(G)$ is the ordered matching
number of $G$. We also prove the inequalities ${\rm sdepth}(J^k)\geq {\rm
depth}(J^k)$ and ${\rm sdepth}(S/J^k)\geq {\rm depth}(S/J^k)$, for every
integer $k\gg 0$, when $G$ is a bipartite graph. Moreover, we provide an
elementary proof for the known inequality ${\rm reg}(S/I)\leq \nu_{o}(G)$.


title: Detecting Localized Categorical Attributes on Graphs

abstract:
  Do users from Carnegie Mellon University form social communities on Facebook?
Do signal processing researchers from tightly collaborate with each other? Do
Chinese restaurants in Manhattan cluster together? These seemingly different
problems share a common structure: an attribute that may be localized on a
graph. In other words, nodes activated by an attribute form a subgraph that can
be easily separated from other nodes. In this paper, we thus focus on the task
of detecting localized attributes on a graph. We are particularly interested in
categorical attributes such as attributes in online social networks, ratings in
recommender systems and viruses in cyber-physical systems because they are
widely used in numerous data mining applications. To solve the task, we
formulate a statistical hypothesis testing problem to decide whether a given
attribute is localized or not. We propose two statistics: graph wavelet
statistic and graph scan statistic, both of which are provably effective in
detecting localized attributes. We validate the robustness of the proposed
statistics on both simulated data and two real-world applications: high
air-pollution detection and keyword ranking in a co-authorship network
collected from IEEE Xplore. Experimental results show that the proposed graph
wavelet statistic and graph scan statistic are effective and efficient.


title:
Kohn-Sham approach to Fermi gas superfluidity: the bilayer of fermionic
  polar molecules

abstract:
  By using a well established 'ab initio' theoretical approach developed in the
past to quantitatively study the superconductivity of condensed matter systems,
which is based on the Kohn-Sham Density Functional theory, I study the
superfluid properties and the BCS-BEC crossover of two parallel bi-dimensional
layers of fermionic dipolar molecules, where the pairing mechanism leading to
superfluidity is provided by the inter-layer coupling between dipoles. The
finite temperature superfluid properties of both the homogeneous system and one
were the fermions in each layer are confined by a square optical lattice are
studied at half filling conditions, and for different values of the strength of
the confining optical potential. The T=0 results for the homogeneous system are
found to be in excellent agreement with Diffusion Monte Carlo results. The
superfluid transition temperature in the BCS region is found to increase, for a
given inter-layer coupling, with the strength of the confining optical
potential. A transition occurs at sufficiently small interlayer distances,
where the fermions becomes localized within the optical lattice sites in a
square geometry with an increased effective lattice constant, forming a system
of localized composite bosons. This transition should be signalled by a sudden
drop in the superfluid fraction of the system.


title: $Z/m$-graded Lie algebras and perverse sheaves, II

abstract:
  We consider a fixed block for the equivariant perverse sheaves with nilpotent
support in the $1$-graded ccomponent of a semisimple cyclically graded Lie
algebra. We give a combinatorial parametrization of the simple objects in that
block.


title: Slopes of indecomposable F-isocrystals

abstract:
  We prove that for an indecomposable convergent or overconvergent F-isocrystal
on a smooth irreducible variety over a perfect field of characteristic p, the
gap between consecutive slopes at the generic point cannot exceed 1. (This may
be thought of as a crystalline analogue of the following consequence of
Griffiths transversality: for an indecomposable variation of complex Hodge
structures, there cannot be a gap between nonzero Hodge numbers.) As an
application, we deduce a refinement of a result of V.Lafforgue on the slopes of
Frobenius of an l-adic local system.
  We also prove similar statements for G-local systems (crystalline and l-adic
ones), where G is a reductive group.
  We translate our results on local systems into properties of the p-adic
absolute values of the Hecke eigenvalues of a cuspidal automorphic
representation of a reductive group over the adeles of a global field of
characteristic p>0.


title: Upper bounds for $B_h[g]$-sets with small $h$

abstract:
  For $g \geq 2$ and $h \geq 3$, we give small improvements on the maximum size
of a $B_h[g]$-set contained in the interval $\{1,2, \dots , N \}$. In
particular, we show that a $B_3[g]$-set in $\{1,2, \dots , N \}$ has at most
$(14.3 g N)^{1/3}$ elements. The previously best known bound was $(16
gN)^{1/3}$ proved by Cilleruelo, Ruzsa, and Trujillo. We also introduce a
related optimization problem that may be of independent interest.


title:
Hierarchically porous Ni monolith@branch-structured NiCo2O4 for high
  energy density supercapacitors

abstract:
  NiCo2O4 of varying nanostrucutures ranging from nanowires, nanoplates to
nano-plates@nanowires were successfully grown on microporous (MP) Ni foams via
one-step hydrothermal process. The investigation of electrochemical capacitance
favors Ni-Co2O4 of nanoplates@nanowires microstructures which possesses
specific capacitance of 1380.3 F/g and 1033F/g at 5A/g and 50A/g respectively
and 86.7% capacitance re-tention after 5000 cycles at 30A/g. The relationship
between morphology and specific capacitance was further explored by the model
of surface roughness factor (RF), which is indicative of the active
electrode-electrolyte interface areas. The RF of porous Ni@NiCo2O4 was
remarkably improved by employing hierarchically porous (HP) Ni monoliths as
substrates, which illustrates the model of high energy density (12.6 F/cm2)
electrodes for super-capacitors.


title:
Doron Gepner's Statistics on Words in {1,2,3} is (most probably)
  Asymptotically Logistic

abstract:
  Doron Gepner's word statistics, that came up in his research in conformal
field theory, is studied and it is conjectured that its scaled limiting
distribution is the Logistic distribution. We support this by proving
rigorously that the scaled limits of the first twelve moments do indeed
converge to those of the Logistic distribution. This is surprising, since
Gepner's statistics is a natural analog of the classical statistics called the
number of inversion, that is known to be asymptotically normal.


title: Bicycle-Sharing System Analysis and Trip Prediction

abstract:
  Bicycle-sharing systems, which can provide shared bike usage services for the
public, have been launched in many big cities. In bicycle-sharing systems,
people can borrow and return bikes at any stations in the service region very
conveniently. Therefore, bicycle-sharing systems are normally used as a
short-distance trip supplement for private vehicles as well as regular public
transportation. Meanwhile, for stations located at different places in the
service region, the bike usages can be quite skewed and imbalanced. Some
stations have too many incoming bikes and get jammed without enough docks for
upcoming bikes, while some other stations get empty quickly and lack enough
bikes for people to check out. Therefore, inferring the potential destinations
and arriving time of each individual trip beforehand can effectively help the
service providers schedule manual bike re-dispatch in advance. In this paper,
we will study the individual trip prediction problem for bicycle-sharing
systems. To address the problem, we study a real-world bicycle-sharing system
and analyze individuals' bike usage behaviors first. Based on the analysis
results, a new trip destination prediction and trip duration inference model
will be introduced. Experiments conducted on a real-world bicycle-sharing
system demonstrate the effectiveness of the proposed model.


title:
Two Superconducting Transitions in Single Crystal
  La$_{2-x}$Ba$_x$CuO$_4$

abstract:
  We use spatially-resolved transport techniques to investigate the
superconducting properties of single crystals La$_{2-x}$Ba$_x$CuO$_4$. We find
a new superconducting transition temperature $T_{cs}$ associated with the
ab-plane surface region which is considerably higher than the bulk $T_c$. The
effect is pronounced in the region of charge carrier doping $x$ with strong
spin-charge stripe correlations, reaching $T_{cs}=36$ K or 1.64$T_c$.


title: Design and implementation of the advanced cloud privacy threat modeling

abstract:
  Privacy-preservation for sensitive data has become a challenging issue in
cloud computing. Threat modeling as a part of requirements engineering in
secure software development provides a structured approach for identifying
attacks and proposing countermeasures against the exploitation of
vulnerabilities in a system . This paper describes an extension of Cloud
Privacy Threat Modeling (CPTM) methodology for privacy threat modeling in
relation to processing sensitive data in cloud computing environments. It
describes the modeling methodology that involved applying Method Engineering to
specify characteristics of a cloud privacy threat modeling methodology,
different steps in the proposed methodology and corresponding products. In
addition, a case study has been implemented as a proof of concept to
demonstrate the usability of the proposed methodology. We believe that the
extended methodology facilitates the application of a privacy-preserving cloud
software development approach from requirements engineering to design.


title: Exploring the Transient Radio Sky with VLITE: Early Results

abstract:
  We report on a search for radio transients at 340 MHz with the Jansky Very
Large Array (VLA) Low band Ionospheric and Transient Experiment (VLITE).
Between 2015 July 29 and 2015 September 27, operating in commensal mode, VLITE
imaged approximately 2800 pointings covering 12,000 deg$^2$ on the sky,
sampling timescales ranging from tens of seconds to several hours on a daily
basis. In addition, between 2015 February 25 and 2015 May 9, VLITE observed 55
epochs of roughly 2-4 hours each toward the COSMOS field. Using existing radio
source catalogs we have searched all the daily VLITE images for transients,
while for the COSMOS field we compared individual images and the summed image
to search for new sources in repeated observations of the same field. The wide
range of timescales makes VLITE sensitive to both coherent and incoherent
transient source classes. No new transients are found, allowing us to set
stringent upper limits on transients at milliJansky levels and at low
frequencies where comparatively few such surveys have been carried out to date.
An all-sky isotropic rate of bursting radio transients with similar rates,
duration, and intensity as the unusual transient GCRT J1745$-$3009, discovered
in wide-field monitoring toward the Galactic center, is ruled out with high
confidence. The resulting non-detections allows us to argue that this is a
coherent source, whose properties most resemble the growing class of nulling
pulsars. We end with a discussion of the future prospects for the detection of
transients by VLITE and other experiments.


title: Quantum-classical equivalence and ground-state factorization

abstract:
  We have performed an analytical study of quantum-classical equivalence for
quantum $XY$-spin chains with arbitrary interactions to explore the classical
counterpart of the factorizing magnetic fields that drive the system into a
separable ground state. We demonstrate that the factorizing line in parameter
space of a quantum model is equivalent to the so-called natural boundary that
emerges in mapping the quantum $XY$-model onto the two dimensional classical
Ising model. As a result, we show that the quantum systems with the
non-factorizable ground state could not be mapped onto the classical Ising
model. Based on the presented correspondence we suggest a promising method for
obtaining the factorizing field of quantum systems through the commutation of
the quantum Hamiltonian and the transfer matrix of the classical model.


title: Nonrelativistic Effective Field Theory for Axions

abstract:
  Axions can be described by a relativistic field theory with a real scalar
field $\phi$ whose self-interaction potential is a periodic function of $\phi$.
Low-energy axions, such as those produced in the early universe by the vacuum
misalignment mechanism, can be described more simply by a nonrelativistic
effective field theory with a complex scalar field $\psi$ whose effective
potential is a function of $\psi^*\psi$. We determine the coefficients in the
expansion of the effective potential to fifth order in $\psi^*\psi$ by matching
low-energy axion scattering amplitudes. In order to describe a Bose-Einstein
condensate of axions that is too dense to expand the effective potential in
powers of $\psi^*\psi$, we develop a sequence of systematically improvable
approximations to the effective potential that include terms of all orders in
$\psi^*\psi$.


title:
Development of the superconducting detectors and read-out for the X-IFU
  instrument on board of the X-ray observatory Athena

abstract:
  The Advanced Telescope for High-Energy Astrophysics (Athena) has been
selected by ESA as its second large-class mission. The future European X-ray
observatory will study the hot and energetic Universe with its launch foreseen
in 2028. Microcalorimeters based on superconducting Transition-edge sensor
(TES) are the chosen technology for the detectors array of the X-ray Integral
Field Unit (X-IFU) on board of Athena. The X-IFU is a 2-D imaging
integral-field spectrometer operating in the soft X-ray band (0.3 -12 keV). The
detector consists of an array of 3840 TESs coupled to X-ray absorbers and read
out in the MHz bandwidth using Frequency Domain Multiplexing (FDM) based on
Superconducting QUantum Interference Devices (SQUIDs). The proposed design
calls for devices with a high filling-factor, high quantum efficiency,
relatively high count-rate capability and an energy resolution of 2.5 eV at 5.9
keV. The paper will review the basic principle and the physics of the TES-based
microcalorimeters and present the state-of-the art of the FDM read-out.


title:
A generalized Lyapunov's inequality for a fractional boundary value
  problem

abstract:
  We prove existence of positive solutions to a nonlinear fractional boundary
value problem. Then, under some mild assumptions on the nonlinear term, we
obtain a smart generalization of Lyapunov's inequality. The new results are
illustrated through examples.


title: The wave function of the modified space time manifold

abstract:
  In the present paper it is considered space time manifold with four
commutative coordinates with Poinc\'are group of motion but different from
Poinc\'are Minkowski space time of the modern physics.


title: Turbulent Taylor-Couette flow with stationary inner cylinder

abstract:
  A series of direct numerical simulations of Taylor-Couette (TC) flow, the
flow between two coaxial cylinders, with the outer cylinder rotating and the
inner one fixed, were performed. Three cases, with outer cylinder Reynolds
numbers $Re_o$ of $Re_o=5.5\cdot10^4$, $Re_o=1.1\cdot10^5$ and
$Re_o=2.2\cdot10^5$ were considered. The radius ratio $\eta=r_i/r_o$ was fixed
to $\eta=0.909$ to mitigate the effects of curvature. The vertical aspect ratio
$\Gamma$ was fixed to $\Gamma=2.09$. Being linearly stable, outer cylinder
rotation TC flow is known to have very different behavior than pure inner
cylinder rotation TC flow. Here, we find that the flow nonetheless becomes
turbulent, but the torque required to drive the cylinders and level of velocity
fluctuations was found to be smaller than those for pure inner cylinder
rotation at comparable Reynolds numbers. The mean angular momentum profiles
showed a large gradient in the bulk, instead of the constant angular momentum
profiles of pure inner cylinder rotation. The near-wall mean and fluctuation
velocity profiles were found to coincide only very close to the wall, showing
large deviations from both pure inner cylinder rotation profiles and the
classic von Karman law of the wall elsewhere. Finally, transport of angular
velocity was found to occur mainly through intermittent bursts, and not through
wall-attached large-scale structures as is the case for pure inner cylinder
rotation.


title: Absence of the Gribov ambiguity in a quadratic gauge

abstract:
  The Gribov ambiguity exists in various gauges except algebraic gauges.
However, algebraic gauges are not Lorentz invariant, which is their fundamental
flaw. In addition, they are not generally compatible with the boundary
conditions on the gauge fields, which are needed to compactify the space i.e.,
the ambiguity continues to exist on a compact manifold. Here we discuss a
quadratic gauge fixing, which is Lorentz invariant. We consider an example of a
spherically symmetric gauge field configuration in which we prove that this
Lorentz invariant gauge removes the ambiguity on a compact manifold
$\mathbb{S}^3$, when a proper boundary condition on the gauge configuration is
taken into account. Thus, providing one example where the ambiguity is absent
on a compact manifold in the algebraic gauge. We also show that the \tmem{BRST}
invariance is preserved in this gauge.


title:
Gauge fields with respect to $d=(3+1)$ in the Kaluza-Klein theories and
  in the spin-charge-family theory

abstract:
  It is shown that in the spin-charge-family theory, as well as in all the
Kaluza-Klein like theories, vielbeins and spin connections manifest in
$d=(3+1)$ space equivalent vector gauge fields, when space with $d\ge5$
manifests large enough symmetry. The authors demonstrate this equivalence in
spaces with the symmetry of the metric tensor in the space out of $d=(3+1)$ -
$g^{\sigma \tau} = \eta^{\sigma \tau} \,f^{2}$ - for any scalar function $f$ of
the coordinates $x^{\sigma}$, where $x^{\sigma}$ denotes coordinates of space
out of $d=(3+1)$. Also the connection between vielbeins and scalar gauge fields
in $d=(3+1)$ (offering the explanation for the Higgs's scalar) is discussed.


title: Multi-Bias Non-linear Activation in Deep Neural Networks

abstract:
  As a widely used non-linear activation, Rectified Linear Unit (ReLU)
separates noise and signal in a feature map by learning a threshold or bias.
However, we argue that the classification of noise and signal not only depends
on the magnitude of responses, but also the context of how the feature
responses would be used to detect more abstract patterns in higher layers. In
order to output multiple response maps with magnitude in different ranges for a
particular visual pattern, existing networks employing ReLU and its variants
have to learn a large number of redundant filters. In this paper, we propose a
multi-bias non-linear activation (MBA) layer to explore the information hidden
in the magnitudes of responses. It is placed after the convolution layer to
decouple the responses to a convolution kernel into multiple maps by
multi-thresholding magnitudes, thus generating more patterns in the feature
space at a low computational cost. It provides great flexibility of selecting
responses to different visual patterns in different magnitude ranges to form
rich representations in higher layers. Such a simple and yet effective scheme
achieves the state-of-the-art performance on several benchmarks.


title: Rotationally Commensurate Growth of MoS2 on Epitaxial Graphene

abstract:
  Atomically thin MoS2/graphene heterostructures are promising candidates for
nanoelectronic and optoelectronic technologies. Among different graphene
substrates, epitaxial graphene (EG) on SiC provides several potential
advantages for such heterostructures including high electronic quality, tunable
substrate coupling, wafer-scale processability, and crystalline ordering that
can template commensurate growth. Exploiting these attributes, we demonstrate
here the thickness-controlled van der Waals epitaxial growth of MoS2 on EG via
chemical vapor deposition, giving rise to transfer-free synthesis of a
two-dimensional heterostructure with registry between its constituent
materials. The rotational commensurability observed between the MoS2 and EG is
driven by the energetically favorable alignment of their respective lattices
and results in nearly strain-free MoS2, as evidenced by synchrotron X-ray
scattering and atomic-resolution scanning tunneling microscopy (STM). The
electronic nature of the MoS2/EG heterostructure is elucidated with STM and
scanning tunneling spectroscopy, which reveals bias-dependent apparent
thickness, band bending, and a reduced bandgap of ~0.4 eV at the monolayer MoS2
edges.


title: Reduction of $SU_f(3)\supset SO(3)\supset A_4$ -- The scalar potential

abstract:
  We examine the possibility of the flavor symmetry being $SU_f(3)$ in which
the phenomenologically successful discreet symmetry $A_4$ is embedded. The
allowed quadratic and quartic potentials are constructed exploiting the full
symmetry chain $SU(3)\supset SO(4)\supset A_4$. The spontaneous symmetry
breaking involving the $SU(3)$ octet scalar fields is analyzed.


title: The geometry of the Gibbs measure of pure spherical spin glasses

abstract:
  We analyze the statics for pure $p$-spin spherical spin glass models with
$p\geq3$, at low enough temperature. With $F_{N,\beta}$ denoting the free
energy, we compute the second order (logarithmic) term of $NF_{N,\beta}$ and
prove that, for an appropriate centering $c_{N,\beta}$,
$NF_{N,\beta}-c_{N,\beta}$ is a tight sequence. We establish the absence of
temperature chaos and analyze the transition rate to disorder chaos of the
Gibbs measure and ground state. Those results follow from the following
geometric picture we prove for the Gibbs measure, of interest by itself:
asymptotically, the measure splits into infinitesimal spherical `bands'
centered at deep minima, playing the role of so-called `pure states'. For the
pure models, the latter makes precise the so-called picture of `many valleys
separated by high mountains' and significant parts of the TAP analysis from the
physics literature.


title: Weak-Link Phenomena in AC-Biased Transition Edge Sensors

abstract:
  It has been recently demonstrated that superconducting transition edge
sensors (TESs) behave as weak-links due to longitudinally induced
superconductivity from the leads with higher Tc. In this work we study the
implication of this behaviour for TES-based bolometers and microcalorimeter
under ac bias. The TESs are read-out at frequencies between 1 and 5 MHz by a
Frequency Domain Multiplexer based on a linearised two-stage SQUID amplifier
and high- Q lithographically made superconducting LC resonators. In particular,
we focus on SRON TiAu TES bolometers with a measured dark Noise Equivalent
Power (NEP) of $3.2 \cdot 10^{-19} W/Hz^{1/2}$ developed for the short
wavelength band for the instrument SAFARI on the SPICA telescope.


title:
Experimental Assessment of Aggregation Principles in
  Argumentation-enabled Collective Intelligence

abstract:
  On the Web, there is always a need to aggregate opinions from the crowd (as
in posts, social networks, forums, etc.). Different mechanisms have been
implemented to capture these opinions such as "Like" in Facebook, "Favorite" in
Twitter, thumbs-up/down, flagging, and so on. However, in more contested
domains (e.g. Wikipedia, political discussion, and climate change discussion)
these mechanisms are not sufficient since they only deal with each issue
independently without considering the relationships between different claims.
We can view a set of conflicting arguments as a graph in which the nodes
represent arguments and the arcs between these nodes represent the defeat
relation. A group of people can then collectively evaluate such graphs. To do
this, the group must use a rule to aggregate their individual opinions about
the entire argument graph. Here, we present the first experimental evaluation
of different principles commonly employed by aggregation rules presented in the
literature. We use randomized controlled experiments to investigate which
principles people consider better at aggregating opinions under different
conditions. Our analysis reveals a number of factors, not captured by
traditional formal models, that play an important role in determining the
efficacy of aggregation. These results help bring formal models of
argumentation closer to real-world application.


title:
Point Defects and Grain Boundaries in Rotationally Commensurate MoS2 on
  Epitaxial Graphene

abstract:
  With reduced degrees of freedom, structural defects are expected to play a
greater role in two-dimensional materials in comparison to their bulk
counterparts. In particular, mechanical strength, electronic properties, and
chemical reactivity are strongly affected by crystal imperfections in the
atomically thin limit. Here, ultra-high vacuum (UHV) scanning tunneling
microscopy (STM) and spectroscopy (STS) are employed to interrogate point and
line defects in monolayer MoS2 grown on epitaxial graphene (EG) at the atomic
scale. Five types of point defects are observed with the majority species
showing apparent structures that are consistent with vacancy and interstitial
models. The total defect density is observed to be lower than MoS2 grown on
other substrates, and is likely attributed to the van der Waals epitaxy of MoS2
on EG. Grain boundaries (GBs) with 30{\deg} and 60{\deg} tilt angles resulting
from the rotational commensurability of MoS2 on EG are more easily resolved by
STM than atomic force microscopy at similar scales due to the enhanced contrast
from their distinct electronic states. For example, band gap reduction to ~0.8
eV and ~0.5 eV is observed with STS for 30{\deg} and 60{\deg} GBs,
respectively. In addition, atomic resolution STM images of these GBs are found
to agree well with proposed structure models. This work offers quantitative
insight into the structure and properties of common defects in MoS2, and
suggests pathways for tailoring the performance of MoS2/graphene
heterostructures via defect engineering.


title:
Charge $2e/3$ superconductivity and topological degeneracies without
  localized zero modes in bilayer fractional quantum Hall states

abstract:
  It has been recently shown that non-Abelian defects with localized
parafermion zero modes can arise in conventional Abelian fractional quantum
Hall (FQH) states. Here we propose an alternate route to creating,
manipulating, and measuring topologically protected degeneracies in bilayer FQH
states coupled to superconductors, without the creation of localized
parafermion zero modes. We focus mainly on electron-hole bilayers, with a $\pm
1/3$ Laughlin FQH state in each layer, with boundaries that are
proximity-coupled to a superconductor. We show that the superconductor induces
charge $2e/3$ quasiparticle-pair condensation at each boundary of the FQH
state, and that this leads to (1) topologically protected degeneracies that can
be measured through charge sensing experiments and (2) a fractional charge
$2e/3$ AC Josephson effect. We demonstrate that an analog of non-Abelian
braiding is possible, despite the absence of a localized zero mode. We discuss
several practical advantages of this proposal over previous work, and also
extensions to electron-electron bilayers at $\nu = 2/3 + 1/3$ coupled to
superconductivity, and to electron-hole bilayers with only interlayer
tunneling.


title: Embedding complete holomorphic discs through discrete sets

abstract:
  Let U be the open unit disc in C and let B be the open unit ball in C^2. We
prove that every discrete subset of B is contained in the range f(U) of a
complete, proper holomorphic embedding f:U-->B. Here the completeness of f
means that for any path p:[0,1)-->U such that |p(t)|-->1 as t-->1, the path
t--> f(p(t)) from [0,1) to B has infinite length.


title: A constructive definition of the beta process

abstract:
  We derive a construction of the beta process that allows for the atoms with
significant measure to be drawn first. Our representation is based on an
extension of the Sethuraman (1994) construction of the Dirichlet process, and
therefore we refer to it as a stick-breaking construction. Our first proof uses
a limiting case argument of finite arrays. To this end, we present a finite
sieve approximation to the beta process that parallels that of Ishwaran &
Zarepour (2002) and prove its convergence to the beta process. We give a second
proof of the construction using Poisson process machinery. We use the Poisson
process to derive almost sure truncation bounds for the construction. We
conclude the paper by presenting an efficient sampling algorithm for
beta-Bernoulli and beta-negative binomial process models.


title:
Singularities of the biextension metric for families of abelian
  varieties

abstract:
  In this paper we study the singularities of the invariant metric of the
Poincar\'e bundle over a family of abelian varieties and their duals over a
base of arbitrary dimension. As an application of this study we prove the
effectiveness of the height jump divisors for families of pointed abelian
varieties. The effectiveness of the height jump divisor was conjectured by Hain
in the more general case of variations of polarized Hodge structures of weight
$-1$.


title: Consistent Perturbative Fixed Point Calculations in QCD and SQCD

abstract:
  We suggest how to consistently calculate the anomalous dimension $\gamma_*$
of the $\bar{\psi}\psi$ operator in finite order perturbation theory at an
infrared fixed point for asymptotically free theories. If the $n+1$ loop beta
function and $n$ loop anomalous dimension are known then $\gamma_*$ can be
calculated exactly and fully scheme independently through $O(\Delta_f^n )$
where $\Delta_f = \bar{N_f} - N_f$ and $N_f$ is the number of flavors and
$\bar{N}_f$ is the number of flavors above which asymptotic freedom is lost.
For a supersymmetric theory the calculation preserves supersymmetry order by
order in $\Delta_f$. We then compute $\gamma_*$ through $O(\Delta_f^2)$ for
supersymmetric QCD in the $\overline{\text{DR}}$ scheme and find that it
matches the exact known result. We find that $\gamma_*$ is astonishingly well
described in perturbation theory already at the few loops level throughout the
entire conformal window. We finally compute $\gamma_*$ through $O(\Delta_f^3)$
for QCD and a variety of other non-supersymmetric fermionic gauge theories.
Small values of $\gamma_*$ are observed for a large range of flavors.


title:
Stochastic simulation of urban environments. Application to Path-loss in
  wireless systems

abstract:
  We are interested in the assessment of electromagnetic Path-Loss in complex
environments. The Path-loss is the attenuation function $P$ of the
electromagnetic power at a distance $d$ of an antenna. In free-space, $P(d)
\propto 1/d^2$, in complex environments like cities, wave trajectory is altered
by successive reflections and absorptions, the path-loss is not theoretically
known and engineering rules postulate that $P(d) \simeq 1/d^{\gamma}, \,
\gamma>2$. We place in a stochastic geometry context to answer the problem
statistically. We present random models of 3D-city. These models reproduce main
real cities' features, can be calibrated with simple mean formulae and can be
fast simulated. For collections of random cities with the same mean morphology,
we estimate by Monte-Carlo ray tracing techniques their attenuation maps. By
averaging these maps, we show that the power expectancy actually follows a
function $\sim 1/d^{\gamma}$ with $\gamma$ depending on the environment
morphology.


title:
Observation of pair tunneling and coherent destruction of tunneling in
  arrays of optical waveguides

abstract:
  We report on the experimental realization of a photonic system that simulates
the one-dimensional two-particle Hubbard model. This analogy is realized by
means of two-dimensional arrays of coupled optical waveguides, fabricated using
femtosecond laser inscription. By tuning the analogous "interaction strength",
we reach the strongly-interacting regime of the Hubbard Hamiltonian, and
demonstrate the suppression of standard tunneling for individual "particles".
In this regime, the formation of bound states is identified through the direct
observation of pair tunneling. We then demonstrate the coherent destruction of
tunneling (CDT) for the paired particles in the presence of an engineered
oscillating force of high frequency. The precise control over the analogous
"interaction strength" and driving force offered by our experimental system
opens an exciting route towards quantum simulation of few-body physics in
photonics.


title:
Phase-plane analysis of the totally asymmetric simple exclusion process
  with binding kinetics and switching between antiparallel lanes

abstract:
  Motor protein motion on biopolymers can be described by models related to the
totally asymmetric simple exclusion process (TASEP). Inspired by experiments on
the motion of kinesin-4 motors on antiparallel microtubule overlaps, we analyze
a model incorporating the TASEP on two antiparallel lanes with binding kinetics
and lane switching. We determine the steady-state motor density profiles using
phase plane analysis of the steady-state mean field equations and kinetic Monte
Carlo simulations. We focus on the the density-density phase plane, where we
find an analytic solution to the mean-field model. By studying the phase space
flows, we determine the model's fixed points and their changes with parameters.
Phases previously identified for the single-lane model occur for low switching
rate between lanes. We predict a new multiple coexistence phase due to
additional fixed points that appear as the switching rate increases: switching
moves motors from the higher-density to the lower-density lane, causing local
jamming and creating multiple domain walls. We determine the phase diagram of
the model for both symmetric and general boundary conditions.


title:
Event excitation for event-driven control and optimization of
  multi-agent systems

abstract:
  We consider event-driven methods in a general framework for the control and
optimization of multi-agent systems, viewing them as stochastic hybrid systems.
Such systems often have feasible realizations in which the events needed to
excite an on-line event-driven controller cannot occur, rendering the use of
such controllers ineffective. We show that this commonly happens in
environments which contain discrete points of interest which the agents must
visit. To address this problem in event-driven gradient-based optimization
problems, we propose a new metric for the objective function which creates a
potential field guaranteeing that gradient values are non-zero when no events
are present and which results in eventual event excitation. We apply this
approach to the class of cooperative multi-agent data collection problems using
the event-driven Infinitesimal Perturbation Analysis (IPA) methodology and
include numerical examples illustrating its effectiveness.


title:
A Lloyd-model generalization: Conductance fluctuations in
  one-dimensional disordered systems

abstract:
  We perform a detailed numerical study of the conductance $G$ through
one-dimensional (1D) tight-binding wires with on-site disorder. The random
configurations of the on-site energies $\epsilon$ of the tight-binding
Hamiltonian are characterized by long-tailed distributions: For large
$\epsilon$, $P(\epsilon)\sim 1/\epsilon^{1+\alpha}$ with $\alpha\in(0,2)$. Our
model serves as a generalization of 1D Lloyd's model, which corresponds to
$\alpha=1$. First, we verify that the ensemble average $\left\langle -\ln
G\right\rangle$ is proportional to the length of the wire $L$ for all values of
$\alpha$, providing the localization length $\xi$ from $\left\langle-\ln
G\right\rangle=2L/\xi$. Then, we show that the probability distribution
function $P(G)$ is fully determined by the exponent $\alpha$ and
$\left\langle-\ln G\right\rangle$. In contrast to 1D wires with standard
white-noise disorder, our wire model exhibits bimodal distributions of the
conductance with peaks at $G=0$ and $1$. In addition, we show that $P(\ln G)$
is proportional to $G^\beta$, for $G\to 0$, with $\beta\le\alpha/2$, in
agreement to previous studies.


title:
Pareto Optimality and Strategy Proofness in Group Argument Evaluation
  (Extended Version)

abstract:
  An inconsistent knowledge base can be abstracted as a set of arguments and a
defeat relation among them. There can be more than one consistent way to
evaluate such an argumentation graph. Collective argument evaluation is the
problem of aggregating the opinions of multiple agents on how a given set of
arguments should be evaluated. It is crucial not only to ensure that the
outcome is logically consistent, but also satisfies measures of social
optimality and immunity to strategic manipulation. This is because agents have
their individual preferences about what the outcome ought to be. In the current
paper, we analyze three previously introduced argument-based aggregation
operators with respect to Pareto optimality and strategy proofness under
different general classes of agent preferences. We highlight fundamental
trade-offs between strategic manipulability and social optimality on one hand,
and classical logical criteria on the other. Our results motivate further
investigation into the relationship between social choice and argumentation
theory. The results are also relevant for choosing an appropriate aggregation
operator given the criteria that are considered more important, as well as the
nature of agents' preferences.


title: Phenomenological Lagrangians, gauge models and branes

abstract:
  Phenomenological Lagrangians for physical systems with spontaneously broken
symmetries are reformulated in terms of gauge field theory. Description of the
Dirac $p$-branes in terms of the Yang-Mills-Cartan gauge multiplets interacting
with gravity, is proved to be equivalent to their description as a closed
dynamical system with the symmetry $ISO(1,D-1)$ spontaneously broken to
$ISO(1,p)\times SO(D-p-1)$.


title:
Diagnosing Suboptimal Cotangent Disintegrations in Hamiltonian Monte
  Carlo

abstract:
  When properly tuned, Hamiltonian Monte Carlo scales to some of the most
challenging high-dimensional problems at the frontiers of applied statistics,
but when that tuning is suboptimal the performance leaves much to be desired.
In this paper I show how suboptimal choices of one critical degree of freedom,
the cotangent disintegration, manifest in readily observed diagnostics that
facilitate the robust application of the algorithm.


title: Quantifying the Diaspora of Knowledge in the Last Century

abstract:
  Academic research is driven by several factors causing different disciplines
to act as "sources" or "sinks" of knowledge. However, how the flow of authors'
research interests -- a proxy of human knowledge -- evolved across time is
still poorly understood. Here, we build a comprehensive map of such flows
across one century, revealing fundamental periods in the raise of interest in
areas of human knowledge. We identify and quantify the most attractive topics
over time, when a relatively significant number of researchers moved from their
original area to another one, causing what we call a "diaspora of the
knowledge" towards sinks of scientific interest, and we relate these points to
crucial historical and political events. Noticeably, only a few areas -- like
Medicine, Physics or Chemistry -- mainly act as sources of the diaspora,
whereas areas like Material Science, Chemical Engineering, Neuroscience,
Immunology and Microbiology or Environmental Science behave like sinks.


title:
A New Learning Method for Inference Accuracy, Core Occupation, and
  Performance Co-optimization on TrueNorth Chip

abstract:
  IBM TrueNorth chip uses digital spikes to perform neuromorphic computing and
achieves ultrahigh execution parallelism and power efficiency. However, in
TrueNorth chip, low quantization resolution of the synaptic weights and spikes
significantly limits the inference (e.g., classification) accuracy of the
deployed neural network model. Existing workaround, i.e., averaging the results
over multiple copies instantiated in spatial and temporal domains, rapidly
exhausts the hardware resources and slows down the computation. In this work,
we propose a novel learning method on TrueNorth platform that constrains the
random variance of each computation copy and reduces the number of needed
copies. Compared to the existing learning method, our method can achieve up to
68.8% reduction of the required neuro-synaptic cores or 6.5X speedup, with even
slightly improved inference accuracy.


title: Asymptotic Theory of Rerandomization in Treatment-Control Experiments

abstract:
  Although complete randomization ensures covariate balance on average, the
chance for observing significant differences between treatment and control
covariate distributions increases with many covariates. Rerandomization
discards randomizations that do not satisfy a predetermined covariate balance
criterion, generally resulting in better covariate balance and more precise
estimates of causal effects. Previous theory has derived finite sample theory
for rerandomization under the assumptions of equal treatment group sizes,
Gaussian covariate and outcome distributions, or additive causal effects, but
not for the general sampling distribution of the difference-in-means estimator
for the average causal effect. To supplement existing results, we develop
asymptotic theory for rerandomization without these assumptions, which reveals
a non-Gaussian asymptotic distribution for this estimator, specifically a
linear combination of a Gaussian random variable and a truncated Gaussian
random variable. This distribution follows because rerandomization affects only
the projection of potential outcomes onto the covariate space but does not
affect the corresponding orthogonal residuals. We also demonstrate that,
compared to complete randomization, rerandomization reduces the asymptotic
sampling variances and quantile ranges of the difference-in-means estimator.
Moreover, our work allows the construction of accurate large-sample confidence
intervals for the average causal effect, thereby revealing further advantages
of rerandomization over complete randomization.


title: Anticommutator Norm Formula for Projection Operators

abstract:
  We prove that for any two projection operators $f,g$ on Hilbert space, their
anticommutator norm is given by the formula \[\|fg + gf\| = \|fg\| +
\|fg\|^2.\] The result demonstrates an interesting contrast between the
commutator and anticommutator of two projection operators on Hilbert space.
Specifically, the norm of the anticommutator $\|fg + gf\|$ is a simple
quadratic function of the norm $\|fg\|$ while the commutator norm $\|fg - gf\|$
is not a function of $\|fg\|$. Nevertheless, the result gives the following
bounds that are functions of $\|fg\|$ on the commutator norm: $\|fg\| -
\|fg\|^2 \le \|fg - gf\| \le \|fg\|$.


title:
From compressed sensing to compressed bit-streams: practical encoders,
  tractable decoders

abstract:
  Compressed sensing is now established as an effective method for dimension
reduction when the underlying signals are sparse or compressible with respect
to some suitable basis or frame. One important, yet under-addressed problem
regarding the compressive acquisition of analog signals is how to perform
quantization. This is directly related to the important issues of how
"compressed" compressed sensing is (in terms of the total number of bits one
ends up using after acquiring the signal) and ultimately whether compressed
sensing can be used to obtain compressed representations of suitable signals.
Building on our recent work, we propose a concrete and practicable method for
performing "analog-to-information conversion". Following a compressive signal
acquisition stage, the proposed method consists of a quantization stage, based
on $\Sigma\Delta$ (sigma-delta) quantization, and a subsequent encoding
(compression) stage that fits within the framework of compressed sensing
seamlessly. We prove that, using this method, we can convert analog compressive
samples to compressed digital bitstreams and decode using tractable algorithms
based on convex optimization. We prove that the proposed AIC provides a nearly
optimal encoding of sparse and compressible signals. Finally, we present
numerical experiments illustrating the effectiveness of the proposed
analog-to-information converter.


title: Tailored Optical Polarization in Nano-Structured Metamaterials

abstract:
  A very efficient method for the calculation of the effective optical response
of nano-structured composite systems allows the design of metamaterials
tailored for specific optical polarization properties. We use our method to
design 2D periodic arrays of sub-wavelength dielectric inclusions within
nanometric supported metallic thin films which behave as either an almost
perfect linearly dichroic system, as a controllable source of circular
polarized light, as a system with a large circular dichroism, or as a circular
polarizer. All of these systems may be tuned over a wide energy range.


title:
Quasiplatonic curves with symmetry group ${\mathbb Z}_{2}^{2} \rtimes
  {\mathbb Z}_{m}$ are definable over ${\mathbb Q}$

abstract:
  It is well known that every closed Riemann surface $S$ of genus $g \geq 2$,
admitting a group $G$ of conformal automorphisms so that $S/G$ has triangular
signature, can be defined over a finite extension of ${\mathbb Q}$. It is
interesting to know, in terms of the algebraic structure of $G$, if $S$ can in
fact be defined over ${\mathbb Q}$. This is the situation if $G$ is either
abelian or isomorphic to $A \rtimes {\mathbb Z}_{2}$, where $A$ is an abelian
group. On the other hand, as shown by Streit and Wolfart, if $G = {\mathbb
Z}_{p} \rtimes {\mathbb Z}_{q}$ where $p,q>3$ are prime integers, then $S$ is
not necessarily definable over ${\mathbb Q}$. In this paper, we observe that if
$G={\mathbb Z}_{2}^{2} \rtimes {\mathbb Z}_{m}$ with $m \geq 3$, then $S$ can
be defined over ${\mathbb Q}$. Moreover, we describe explicit models for $S$,
the corresponding groups of automorphisms and an isogenous decomposition of
their Jacobian varieties as product of Jacobians of hyperelliptic Riemann
surfaces.


title: Inflationary Birefringence and Baryogenesis

abstract:
  A decade ago, the first leptogenesis model based on inflation was proposed,
where the complex phase of the inflaton field carries lepton number. If the
inflaton field is an axion, it can couple to gravitational waves and gauge
fields via. Chern-Simons invariants. Due to these couplings, birefringent
gravitational and gauge primordial perturbations are created during inflation
to generate a lepton asymmetry, establishing a possible connection between
non-vanishing TB-parity violating polarization cross-correlations and
leptogenesis. We also discuss the prospect for a subset of these models can
directly source circular (V-mode) polarization in the CMB.


title: N-expansive homeomorphisms with the shadowing property

abstract:
  We discuss the dynamics of $n$-expansive homeomorphisms with the shadowing
property defined on compact metric spaces. For every $n\in\mathbb{N}$, we
exhibit an $n$-expansive homeomorphism, which is not $(n-1)$-expansive, has the
shadowing property and admits an infinite number of chain-recurrent classes. We
discuss some properties of the local stable (unstable) sets of $n$-expansive
homeomorphisms with the shadowing property and use them to prove that some
types of the limit shadowing property are present. This deals some direction to
the problem of non-existence of topologically mixing $n$-expansive
homeomorphisms that are not expansive.


title: Asymptotic Analysis of Transport Equation in Annulus

abstract:
  We consider the diffusive limit of a steady neutron transport equation with
one-speed velocity in a two-dimensional annulus. A classical theorem states
that the solution can be approximated in $L^{\infty}$ by the leading order
interior solution plus the corresponding Knudsen layers in the diffusive limit.
In this paper, we construct a counterexample of this result via a different
boundary layer expansion with geometric correction.


title: Coordination of Players in Ride-Sharing Games by Signaling

abstract:
  Sharing unused vehicles is one practical solution for traffic congestion. We
propose an advanced vehicle-sharing service that maximizes the sharing of
vehicles and improves traffic efficiency by coordinating user trips via an
information system. We formulate ride-sharing games that model externalities in
vehicle sharing caused by insufficient vehicle supply. We show how Bayes
correlated equilibrium can coordinate players in ride-sharing games and verify
the resultant improvement in the price of anarchy.


title:
Compositional and temperature evolution of crystal structure of new
  thermoelectric compound LaOBiS2-xSex

abstract:
  We examined the crystal structure of the new thermoelectric material
LaOBiS2-xSex, whose thermoelectric performance is enhanced by Se substitution,
by using powder synchrotron X-ray diffraction and Rietveld refinement. The
emergence of metallic conductivity and enhancement of the thermoelectric power
factor of LaOBiS2-xSex can be explained with the higher in-plane chemical
pressure caused by the increase of Se concentration at the in-plane Ch1 site
(Ch = S, Se). High-temperature X-ray diffraction measurements for optimally
substituted LaOBiSSe revealed anomalously large atomic displacement parameters
(Uiso) for Bi and Ch atoms in the BiCh2 conduction layers. The anisotropic
analysis of the atomic displacement parameters (U11 and U33) for the in-plane
Bi and Ch1 sites suggested that Bi atoms exhibit large atomic displacement
along the c-axis direction above 300 K, which could be the origin of the low
thermal conductivity in LaOBiSSe. The large Bi vibration along the c-axis
direction could be related to in-plane rattling, which is a new strategy for
attaining low thermal conductivity and phonon-glass-electron-crystal states.


title:
Approximating (Unweighted) Tree Augmentation via Lift-and-Project (Part
  0: $1.8+\epsilon$ approximation for (Unweighted) TAP)

abstract:
  We study the unweighted Tree Augmentation Problem (TAP) via the Lasserre (Sum
of Squares) system. We prove an approximation guarantee of ($1.8+\epsilon$)
relative to an SDP relaxation, which matches the combinatorial approximation
guarantee of Even, Feldman, Kortsarz and Nutov in ACM TALG (2009), where
$\epsilon>0$ is a constant. We generalize the combinatorial analysis of
integral solutions of Even, et al., to fractional solutions by identifying some
properties of fractional solutions of the Lasserre system via the decomposition
result of Rothvo{\ss} (arXiv:1111.5473, 2011) and Karlin, Mathieu and Nguyen
(IPCO 2011).


title:
Crystal structure instability of FeSe grains: Formation of
  non-superconducting phase at the grain surface

abstract:
  We investigated the magnetization and crystal structure of FeSe
polycrystalline samples with various grain sizes. For the samples with large
grains, a large magnetic critical current density Jc was observed. For the
samples with small grains, superconductivity signals were not observed;
instead, magnetization hysteresis, which is not a result of superconductivity,
was observed. In the X-ray diffraction pattern for the samples with small
grains, broad additional peaks were observed, corresponding to the formation of
the non-superconducting (monoclinic) Fe-Se phase at the FeSe grain surface. The
crystal structure instability at the grain surface would be the reason for the
low superconducting properties of the Fe-chalcogenide polycrystalline wires
investigated thus far.


title: Pure Nash Equilibrium and Coordination of Players in Ride Sharing Games

abstract:
  In this study, we formulate positive and negative externalities caused by
changes in the supply of shared vehicles as ride sharing games. The study aims
to understand the price of anarchy (PoA) and its improvement via a coordination
technique in ride sharing games. A critical question is whether ride sharing
games exhibit a pure Nash equilibrium (pNE) since the PoA bound assumes it. Our
result shows a sufficient condition for a ride sharing game to have a finite
improvement property and a pNE similar to potential games. This is the first
step to analyze PoA bound and its improvement by coordination in ride sharing
games. We also show an example of coordinating players in ride sharing games
using signaling and evaluate the improvement in the PoA.


title: Lie algebroids as $L_\infty$ spaces

abstract:
  In this paper, we relate Lie algebroids to Costello's version of derived
geometry. For instance, we show that each Lie algebroid $L$-and the natural
generalization to dg Lie algebroids-provides an (essentially unique) $L_\infty$
space. More precisely, we construct a faithful functor from the category of Lie
algebroids to the category of $L_\infty$ spaces. Then we show that for each Lie
algebroid $L$, there is a fully faithful functor from the category of
representations up to homotopy of $L$ to the category of vector bundles over
the associated $L_\infty$ space. Indeed, this functor sends the adjoint complex
of $L$ to the tangent bundle of the $L_\infty$ space. Finally, we show that a
shifted-symplectic structure on a dg Lie algebroid $L$ produces a
shifted-symplectic structure on the associated $L_\infty$ space.


title: Regular characters of groups of type A_n over discrete valuation rings

abstract:
  Let O be a complete discrete valuation ring with finite residue field k of
odd characteristic. Let G be a general or special linear group or a unitary
group defined over O and let $\mathfrak{g}$ denote its Lie algebra. For every
positive integer l, let $K^l$ be the l-th principal congruence subgroup of
G(O). A continuous irreducible representation of G(O) is called regular of
level l if it is trivial on $K^{l+1}$ and its restriction to $K^l/K^{l+1}
\simeq \mathfrak{g}(k)$ consists of characters with G(k)-stabiliser of minimal
dimension. In this paper we construct the regular characters of G(O), compute
their degrees and show that the latter satisfy Ennola duality. We give explicit
uniform formulae for the regular part of the representation zeta functions of
these groups.


title: Notes on ergodic theorems in non-commutative symmetric spaces

abstract:
  In this paper we establish individual ergodic theorem for positive kernels
(or so called Danford Shwartz (DS+) operators acting on non commutative
symmetric spaces.


title: Orthogonal Polynomials from Hermitian Matrices II

abstract:
  This is the second part of the project `unified theory of classical
orthogonal polynomials of a discrete variable derived from the eigenvalue
problems of hermitian matrices.' In a previous paper, orthogonal polynomials
having Jackson integral measures were not included, since such measures cannot
be obtained from single infinite dimensional hermitian matrices. Here we show
that Jackson integral measures for the polynomials of the big $q$-Jacobi family
are the consequence of the recovery of self-adjointness of the unbounded Jacobi
matrices governing the difference equations of these polynomials. The recovery
of self-adjointness is achieved in an extended $\ell^2$ Hilbert space on which
a direct sum of two unbounded Jacobi matrices acts as a Hamiltonian or a
difference Schr\"odinger operator for an infinite dimensional eigenvalue
problem. The polynomial appearing in the upper/lower end of Jackson integral
constitutes the eigenvector of each of the two unbounded Jacobi matrix of the
direct sum. We also point out that the orthogonal vectors involving the
$q$-Meixner ($q$-Charlier) polynomials do not form a complete basis of the
$\ell^2$ Hilbert space, based on the fact that the dual $q$-Meixner polynomials
introduced in a previous paper fail to satisfy the orthogonality relation. The
complete set of eigenvectors involving the $q$-Meixner polynomials is obtained
by constructing the duals of the dual $q$-Meixner polynomials which require the
two component Hamiltonian formulation. An alternative solution method based on
the closure relation, the Heisenberg operator solution, is applied to the
polynomials of the big $q$-Jacobi family and their duals and $q$-Meixner
($q$-Charlier) polynomials.


title:
Global MHD Simulations of Accretion Disks in Cataclysmic Variables
  (CVs): I. The Importance of Spiral Shocks

abstract:
  We present results from the first global 3D MHD simulations of accretion
disks in Cataclysmic Variable (CV) systems in order to investigate the relative
importance of angular momentum transport via turbulence driven by the
magnetorotational instability (MRI) compared to that driven by spiral shock
waves. Remarkably, we find that even with vigorous MRI turbulence, spiral
shocks are an important component to the overall angular momentum budget, at
least when temperatures in the disk are high (so that Mach numbers are low). In
order to understand the excitation, propagation, and damping of spiral density
waves in our simulations more carefully, we perform a series of 2D global
hydrodynamical simulations with various equation of states and both with and
without mass inflow via the Lagrangian point (L1). Compared with previous
similar studies, we find the following new results. 1) Linear wave dispersion
relation fits the pitch angles of spiral density waves very well. 2) We
demonstrate explicitly that mass accretion is driven by the deposition of
negative angular momentum carried by the waves when they dissipate in shocks.
3) Using Reynolds stress scaled by gas pressure to represent the effective
angular momentum transport rate alpha_{eff} is not accurate when mass accretion
is driven by non-axisymmetric shocks. 4) Using the mass accretion rate measured
in our simulations to directly measure alpha defined in standard thin-disk
theory, we find 0.02 < alpha_{eff} < 0.05 for CV disks, consistent with
observed values in quiescent states of dwarf novae (DNe). In this regime the
disk may be too cool and neutral for the MRI to operate and spiral shocks are a
possible accretion mechanism. However, we caution that our simulations use
unrealistically low Mach numbers in this regime, and therefore future models
with more realistic thermodynamics and non-ideal MHD are warranted.


title: Axionic domain wall number related to U(1)$_{\rm anom}$ global symmetry

abstract:
  The QCD axion with $f_a$ at an intermediate scale, 10**9-10**12 GeV, seems in
conflict with the gravity spoil of global symmetries and may face the axionic
domain wall problem. We point out that the string compactifications with an
anomalous U(1) gauge symmetry, allowing desirable chiral matter spectra,
circumvent these two problems simultaneously.


title: Golden mean Siegel disk universality and renormalization

abstract:
  We provide a computer-assisted proof of one of the central open questions in
one-dimensional renormalization theory -- universality of the golden-mean
Siegel disks. We further show that for every function in the stable manifold of
the golden-mean renormalization fixed point the boundary of the Siegel disk is
a quasicircle which coincides with the closure of the critical orbit, and that
the dynamics on the boundary of the Siegel disk is rigid.
  Furthermore, we extend the renormalization from one-dimensional analytic maps
with a golden-mean Siegel disk to two-dimensional dissipative H\'enon-like maps
and show that the renormalization hyperbolicity result still holds in this
setting.


title:
Partially coherent electron transport in terahertz quantum cascade
  lasers based on a Markovian master equation for the density matrix

abstract:
  We derive a Markovian master equation for the single-electron density matrix,
applicable to quantum cascade lasers (QCLs). The equation conserves the
positivity of the density matrix, includes off-diagonal elements (coherences)
as well as in-plane dynamics, and accounts for electron scattering with phonons
and impurities. We use the model to simulate a terahertz-frequency QCL, and
compare the results with both experiment and simulation via nonequilibrium
Green's functions (NEGF). We obtain very good agreement with both experiment
and NEGF when the QCL is biased for optimal lasing. For the considered device,
we show that the magnitude of coherences can be a significant fraction of the
diagonal matrix elements, which demonstrates their importance when describing
THz QCLs. We show that the in-plane energy distribution can deviate far from a
heated Maxwellian distribution, which suggests that the assumption of
thermalized subbands in simplified density-matrix models is inadequate. We also
show that the current density and subband occupations relax towards their
steady-state values on very different time scales.


title: Renormalization of almost commuting pairs

abstract:
  In this paper we give a new prove of hyperbolicity of renormalization of
critical circle maps using the formalism of almost-commuting pairs. We extend
renormalization to two-dimensional dissipative maps of the annulus which are
small perturbations of one-dimensional critical circle maps. Finally, we
demontsrate that a two-dimensional map which lies in the stable set of the
renormalization operator possesses an attractor which is topologically a
circle. Such a circle is critical: the dynamics on it is topologically, but not
smoothly, conjugate to a rigid rotation.


title: Observation of Topological Nodal Fermion Semimetal Phase in ZrSiS

abstract:
  Unveiling new topological phases of matter is one of the current objectives
in condensed matter physics. Recent experimental discoveries of Dirac and Weyl
semimetals prompt to search for other exotic phases of matter. Here we present
a systematic angle-resolved photoemission spectroscopy (ARPES) study of ZrSiS,
a prime topological nodal semimetal candidate. Our wider Brillouin zone (BZ)
mapping shows multiple Fermi surface pockets such as the diamond-shaped Fermi
surface, ellipsoidal-shaped Fermi surface, and a small electron pocket
encircling at the zone center (G) point, the M point and the X point of the BZ,
respectively. We experimentally establish the spinless nodal fermion semimetal
phase in ZrSiS, which is supported by our first-principles calculations. Our
findings evidence that the ZrSiS-type of material family is a new platform to
explore exotic states of quantum matter, while these materials are expected to
provide an avenue for engineering two-dimensional topological insulator
systems.


title:
Density matrix renormalization group study in energy space for a
  single-impurity Anderson model and an impurity quantum phase transition

abstract:
  The density matrix renormalization group method is applied to obtain the
ground state phase diagram of the single impurity Anderson model on the
honeycomb lattice at half filling. The calculation of local static quantities
shows that the phase diagram contains two distinct phases, the local moment
(LM) phase and the asymmetric strong coupling (ASC) phase. These results are
supported by the local spin and charge excitation spectra, which exhibit
qualitatively different behavior in these two phases and also reveal the
existence of the valence fluctuating point at the phase boundary. For
comparison, we also study the low-energy effective pseudogap Anderson model.
Although the high-energy excitations are obviously different, we find that the
ground state phase diagram and the asymptotically low-energy excitations are in
good quantitative agreement with those for the single impurity Anderson model
on the honeycomb lattice, thus providing the first quantitative justification
for the previous studies based on low-energy approximate approaches.
Furthermore, we find that the lowest entanglement level is doubly degenerate
for the LM phase, whereas it is singlet for the ASC phase and is accidentally
three fold degenerate at the valence fluctuating point. Our results therefore
clearly demonstrate that the low-lying entanglement spectrum can be used to
determine with high accuracy the phase boundary of the impurity quantum phase
transition.


title:
The Geometry of Quantum Hall Effect: An Effective Action for all
  Dimensions

abstract:
  We present a general formula for the topological part of the effective action
for quantum Hall systems in higher dimensions, including fluctuations of the
gauge field and metric around background fields of a specified topological
class. The result is based on a procedure of integrating up from the Dolbeault
index density which applies for the degeneracies of Landau levels, combined
with some input from the standard descent procedure for anomalies. Features of
the topological action in (2+1), (4+1), (6+1) dimensions, including the
contribution due to gravitational anomalies, are discussed in some detail.


title:
Convergence Analysis of Quantized Primal-dual Algorithm in Network
  Utility Maximization Problems

abstract:
  This paper investigates the asymptotic and non-asymptotic behavior of the
quantized primal dual algorithm in network utility maximization problems, in
which a group of agents maximize the sum of their individual concave objective
functions under linear constraints. In the asymptotic scenario, we use the
information theoretic notion of differential entropy power to establish
universal lower bounds on the exponential convergence rates of joint primal
dual, primal and dual variables under optimum achieving quantization schemes.
These results provide trade offs between the speed of exponential convergence,
the agents objective functions, the communication bit rates, and the number of
agents and constraints. In the non-asymptotic scenario, we obtain lower bounds
on the mean square distance of joint primal dual, primal and dual variables
from the optimal solution for any finite time instance. These bounds hold
regardless of the quantization scheme used.


title: Robust Ferroelectricity in Monolayer Group-IV Monochalcogenides

abstract:
  Ferroelectricity usually fades away when materials are thinned down below a
critical value. Employing the first-principles density functional theory and
modern theory of polarization, we show that the unique ionic-potential
anharmonicity can induce spontaneous in-plane electrical polarizations and
ferroelectricity in monolayer group-IV monochalcogenides MX (M=Ge, Sn; X=S,
Se). Using Monte Carlo simulations with an effective Hamiltonian extracted from
the parameterized energy space, we show these materials exhibit a
two-dimensional ferroelectric phase transition that is described by
fourth-order Landau theory. We also show the ferroelectricity in these
materials is robust and the corresponding Curie temperature is higher than room
temperature, making these materials promising for realizing ultra-thin
ferroelectric devices of broad interest.

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


title: Classical chaos in atom-field systems

abstract:
  The relation between the onset of chaos and critical phenomena, like Quantum
Phase Transitions (QPT) and Excited-State Quantum Phase transitions (ESQPT), is
analyzed for atom-field systems. While it has been speculated that the onset of
hard chaos is associated with ESQPT based in the resonant case, the
off-resonant cases show clearly that both phenomena, ESQPT and chaos, respond
to different mechanisms. The results are supported in a detailed numerical
study of the dynamics of the semiclassical Hamiltonian of the Dicke model. The
appearance of chaos is quantified calculating the largest Lyapunov exponent for
a wide sample of initial conditions in the whole available phase space for a
given energy. The percentage of the available phase space with chaotic
trajectories is evaluated as a function of energy and coupling between the
qubit and bosonic part, allowing to obtain maps in the space of coupling and
energy, where ergodic properties are observed in the model. Different sets of
Hamiltonian parameters are considered, including resonant and off-resonant
cases.


title: Boundary combinatorics of orthogonal modular 4-folds

abstract:
  We study combinatorial problems related to the singularities and boundary
components of toroidal compactifications of orthogonal modular varieties. In
particular, those associated with the moduli of algebraic deformation
generalised Kummer 4-folds.


title: Character-Level Question Answering with Attention

abstract:
  We show that a character-level encoder-decoder framework can be successfully
applied to question answering with a structured knowledge base. We use our
model for single-relation question answering and demonstrate the effectiveness
of our approach on the SimpleQuestions dataset (Bordes et al., 2015), where we
improve state-of-the-art accuracy from 63.9% to 70.9%, without use of
ensembles. Importantly, our character-level model has 16x fewer parameters than
an equivalent word-level model, can be learned with significantly less data
compared to previous work, which relies on data augmentation, and is robust to
new entities in testing.


title: 750 GeV Diphoton Resonance in a Vector-like Extension of Hill Model

abstract:
  In this paper, we study the recent 750 GeV diphoton excess in the Hill Model
with vector-like fermions, in which the singlet-like Higgs boson is chosen as
750 GeV resonance and is mainly produced by the gluon fusion through
vector-like top and bottom quarks. Meanwhile its diphoton decay rate is greatly
enhanced by the vector-like lepton. Under the current experimental and
theoretical constraints, we present the viable parameter space that fits the
750 GeV diphoton signal strength at 13 TeV LHC. We find that the heavier
vector-like fermion masses are, the smaller mixing angle $\theta$ is required.
The mixing angle of singlet and doublet Higgs bosons is constrained within
$|\sin\theta| \lesssim 0.15$ in the condition of the perturbative Yukawa
couplings. In the allowed parameter space, the 750 GeV diphoton cross section
can be maximally enhanced to about 6 fb at 13 TeV LHC.


title: The neutrino floor at ultra-low threshold

abstract:
  By lowering their energy threshold direct dark matter searches can reach the
neutrino floor with experimental technology now in development. The 7Be flux
can be detected with $\sim 10$ eV nuclear recoil energy threshold and 50 kg-yr
exposure. The pep flux can be detected with $\sim 3$ ton-yr exposure, and the
first detection of the CNO flux is possible with similar exposure. The pp flux
can be detected with threshold of $\sim$ eV and only $\sim$ kg-yr exposure.
These can be the first pure neutral current measurements of the low-energy
solar neutrino flux. Measuring this flux is important for low mass dark matter
searches and for understanding the solar interior.


title: Waterdrop Stereo

abstract:
  This paper introduces depth estimation from water drops. The key idea is that
a single water drop adhered to window glass is totally transparent and convex,
and thus optically acts like a fisheye lens. If we have more than one water
drop in a single image, then through each of them we can see the environment
with different view points, similar to stereo. To realize this idea, we need to
rectify every water drop imagery to make radially distorted planar surfaces
look flat. For this rectification, we consider two physical properties of water
drops: (1) A static water drop has constant volume, and its geometric convex
shape is determined by the balance between the tension force and gravity. This
implies that the 3D geometric shape can be obtained by minimizing the overall
potential energy, which is the sum of the tension energy and the gravitational
potential energy. (2) The imagery inside a water-drop is determined by the
water-drop 3D shape and total reflection at the boundary. This total reflection
generates a dark band commonly observed in any adherent water drops. Hence,
once the 3D shape of water drops are recovered, we can rectify the water drop
images through backward raytracing. Subsequently, we can compute depth using
stereo. In addition to depth estimation, we can also apply image refocusing.
Experiments on real images and a quantitative evaluation show the effectiveness
of our proposed method. To our best knowledge, never before have adherent water
drops been used to estimate depth.


title:
Accurate and Efficient Solution of the Electronic Schr\"odinger Equation
  with the Coulomb Singularity by the Distributed Approximating Functional
  Method

abstract:
  We proposed a distributed approximating functional method for efficiently
describing the electronic dynamics in atoms and molecules in the presence of
the Coulomb singularities, using the kernel of a grid representation derived by
using the solutions of the Coulomb differential equation based upon the
Schwartz's interpolation formula, and a grid representation using the
Lobatto/Radau shape functions. The elements of the resulted Hamiltonian matrix
are confined in a narrow diagonal band, which is similar to that using the
(higher order) finite difference methods. However, the spectral convergence
properties of the original grid representations are retained in the proposed
distributed approximating functional method for solving the Schr\"odinger
equation involving the Coulomb singularity. Thus the method is effective for
solving the electronic Schr\"odinger equation using iterative methods where the
action of the Hamiltonian matrix on the wave function need to evaluate many
times. The method is investigated by examining its convergence behaviours for
calculating the electronic states of the H atom, H$_2^+$ molecule, the H atom
in a parallel magnetic and electric fields, as the radial basis functions.


title: Strained fold assisted transport in graphene systems

abstract:
  Deformations in graphene systems are central elements in the novel field of
{\it straintronics}. Various strain geometries have been proposed to produce
specific properties but their experimental realization has been limited.
Because strained folds can be engineered on graphene samples on appropriate
substrates, we study their effects on graphene transport properties. We show
the existence of an enhanced local density of states (LDOS) along the direction
of the strained fold that originates from localization of higher energy states,
and provides extra conductance channels at lower energies. In addition to
exhibit sublattice symmetry breaking, these states are valley polarized, with
quasi-ballistic properties in smooth disorder potentials. We confirmed that
these results persist in the presence of strong edge disorder, making these
geometries viable electronic waveguides. These findings could be tested in
properly engineered experimental settings.


title: On regularity lemmas and their algorithmic applications

abstract:
  Szemer\'edi's regularity lemma and its variants are some of the most powerful
tools in combinatorics. In this paper, we establish several results around the
regularity lemma. First, we prove that whether or not we include the condition
that the desired vertex partition in the regularity lemma is equitable has a
minimal effect on the number of parts of the partition. Second, we use an
algorithmic version of the (weak) Frieze--Kannan regularity lemma to give a
substantially faster deterministic approximation algorithm for counting
subgraphs in a graph. Previously, only an exponential dependence for the
running time on the error parameter was known, and we improve it to a
polynomial dependence. Third, we revisit the problem of finding an algorithmic
regularity lemma, giving approximation algorithms for several co-NP-complete
problems. We show how to use the weak Frieze--Kannan regularity lemma to
approximate the regularity of a pair of vertex subsets. We also show how to
quickly find, for each $\epsilon'>\epsilon$, an $\epsilon'$-regular partition
with $k$ parts if there exists an $\epsilon$-regular partition with $k$ parts.
Finally, we give a simple proof of the permutation regularity lemma which
improves the tower-type bound on the number of parts in the previous proofs to
a single exponential bound.


title:
Capturing Semantic Similarity for Entity Linking with Convolutional
  Neural Networks

abstract:
  A key challenge in entity linking is making effective use of contextual
information to disambiguate mentions that might refer to different entities in
different contexts. We present a model that uses convolutional neural networks
to capture semantic correspondence between a mention's context and a proposed
target entity. These convolutional networks operate at multiple granularities
to exploit various kinds of topic information, and their rich parameterization
gives them the capacity to learn which n-grams characterize different topics.
We combine these networks with a sparse linear model to achieve
state-of-the-art performance on multiple entity linking datasets, outperforming
the prior systems of Durrett and Klein (2014) and Nguyen et al. (2014).


title: Metastable states for an aggregation model with noise

abstract:
  We study the long-time effect of noise on pattern formation for the
aggregation model. We consider aggregation kernels that generate patterns
consisting of two delta-concentrations. Without noise, there is a one-parameter
family of admissible equilibria that consist of two concentrations whose mass
is not necessary equal. We show that when a small amount of noise is added, the
heavier concentration "leaks" its mass towards the lighter concentration over a
very long time scale, eventually resulting in the equilibration of the two
masses. We use exponentially small asymptotics to derive the long-time ODE's
that quantify this mass exchange. Our theory is validated using full numerical
simulations of the original model -- both of the original stochastic particle
system and its PDE limit. Our formal computations show that adding noise
destroys the degeneracy in the equilibrium solution and leads to a unique
symmetric steady state.


title: Rate-distortion Balanced Data Compression for Wireless Sensor Networks

abstract:
  This paper presents a data compression algorithm with error bound guarantee
for wireless sensor networks (WSNs) using compressing neural networks. The
proposed algorithm minimizes data congestion and reduces energy consumption by
exploring spatio-temporal correlations among data samples. The adaptive
rate-distortion feature balances the compressed data size (data rate) with the
required error bound guarantee (distortion level). This compression relieves
the strain on energy and bandwidth resources while collecting WSN data within
tolerable error margins, thereby increasing the scale of WSNs. The algorithm is
evaluated using real-world datasets and compared with conventional methods for
temporal and spatial data compression. The experimental validation reveals that
the proposed algorithm outperforms several existing WSN data compression
methods in terms of compression efficiency and signal reconstruction. Moreover,
an energy analysis shows that compressing the data can reduce the energy
expenditure, and hence expand the service lifespan by several folds.