title:
A two weight fractional singular integral theorem with side conditions,
  energy and k-energy dispersed

abstract:
  This paper is a sequel to our paper Rev. Mat. Iberoam. 32 (2016), no. 1,
79-174. Let T be a standard fractional Calderon Zygmund operator. Assume
appropriate Muckenhoupt and quasienergy side conditions. Then we show that T is
bounded from one weighted space to another if the quasicube testing conditions
hold for T and its dual, and if the quasiweak boundedness property holds for T.
Conversely, if T is bounded, then the quasitesting conditions hold, and the
quasiweak boundedness condition holds. If the vector of fractional Riesz
transforms (or more generally a strongly elliptic vector of transforms) is
bounded, then the appropriate Muckenhoupt conditions hold. We do not know if
our quasienergy conditions are necessary in higher dimensions, except for
certain situations in which one of the measures is one-dimensional as in
arXiv:1310.4820 and arXiv:1505.07822v4, and for certain side conditions placed
on the measures such as doubling and k-energy dispersed, which when k=n-1 is
similar to the condition of uniformly full dimension in Lacey and Wick
arXiv:1312.6163v3.


title: Potts model coupled to causal triangulations

abstract:
  In this work we study the annealed Potts model coupled to two dimensional
causal triangulations with periodic boundary condition. Using duality on a
torus, we provide a relation between the free energy of the Potts model coupled
CTs and its dual. This duality relation follows from the FK representation for
the Potts model. In order to determine a region where the critical curve for
the model can be located we use the duality relation and the high-temperature
expansion. This is done by outlining a region where the infinite-volume Gibbs
measure exists and is unique and a region where the finite-volume Gibbs mea-
sure has no weak limit (in fact, does not exist if the volume is large enough).
We also provide lower and upper bounds for the infinite- volume free energy.


title:
SPARC: Accurate and efficient finite-difference formulation and parallel
  implementation of Density Functional Theory: Isolated clusters

abstract:
  As the first component of SPARC (Simulation Package for Ab-initio Real-space
Calculations), we present an accurate and efficient finite-difference
formulation and parallel implementation of Density Functional Theory (DFT) for
isolated clusters. Specifically, utilizing a local reformulation of the
electrostatics, the Chebyshev polynomial filtered self-consistent field
iteration, and a reformulation of the non-local component of the force, we
develop a framework using the finite-difference representation that enables the
efficient evaluation of energies and atomic forces to within the desired
accuracies in DFT. Through selected examples consisting of a variety of
elements, we demonstrate that SPARC obtains exponential convergence in energy
and forces with domain size; systematic convergence in the energy and forces
with mesh-size to reference plane-wave result at comparably high rates; forces
that are consistent with the energy, both free from any noticeable `egg-box'
effect; and accurate ground-state properties including equilibrium geometries
and vibrational spectra. In addition, for systems consisting up to thousands of
electrons, SPARC displays weak and strong parallel scaling behavior that is
similar to well-established and optimized plane-wave implementations, but with
a significantly reduced prefactor. Overall, SPARC represents an attractive
alternative to plane-wave codes for practical DFT simulations of isolated
clusters.


title: The landscape of software failure cause models

abstract:
  The software engineering field has a long history of classifying software
failure causes. Understanding them is paramount for fault injection, focusing
testing efforts or reliability prediction. Since software fails in manifold
complex ways, a broad range of software failure cause models is meanwhile
published in dependability literature. We present the results of a meta-study
that classifies publications containing a software failure cause model in topic
clusters. Our results structure the research field and can help to identify
gaps. We applied the systematic mapping methodology for performing a repeatable
analysis.
  We identified 156 papers presenting a model of software failure causes. Their
examination confirms the assumption that a large number of the publications
discusses source code defects only. Models of fault-activating state conditions
and error states are rare. Research seems to be driven mainly by the need for
better testing methods and code-based quality improvement. Other motivations
such as online error detection are less frequently given. Mostly, the IEEE
definitions or orthogonal defect classification is used as base terminology.
The majority of use cases comes from web, safety- and security-critical
applications.


title:
A little walk from physical to biological complexity: protein folding
  and stability

abstract:
  As an example of topic where biology and physics meet, we present the issue
of protein folding and stability, and the development of thermodynamics-based
bioinformatics tools that predict the stability and thermal resistance of
proteins and the change of these quantities upon amino acid substitutions.
These methods are based on knowledge-driven statistical potentials, derived
from experimental protein structures using the inverse Boltzmann law. We also
describe an application of these predictors, which contributed to the
understanding of the mechanisms of aggregation of a particular protein known to
cause a neuronal disease.


title:
On the structure of the power graph and the enhanced power graph of a
  group

abstract:
  Let $G$ be a group. The \emph{power graph} of $G$ is a graph with the vertex
set $G$, having an edge between two elements whenever one is a power of the
other. We characterize nilpotent groups whose power graphs have finite
independence number. For a bounded exponent group, we prove its power graph is
a perfect graph and we determine its clique/chromatic number. Furthermore, it
is proved that for every group $G$, the clique number of the power graph of $G$
is at most countably infinite. We also measure how close the power graph is to
the \emph{commuting graph} by introducing a new graph which lies in between. We
call this new graph as the \emph{enhanced power graph}. For an arbitrary pair
of these three graphs we characterize finite groups for which this pair of
graphs are equal.


title:
Grasping for a Purpose: Using Task Goals for Efficient Manipulation
  Planning

abstract:
  In this paper we propose an approach for efficient grasp selection for
manipulation tasks of unknown objects. Even for simple tasks such as
pick-and-place, a unique solution is rare to occur. Rather, multiple candidate
grasps must be considered and (potentially) tested till a successful,
kinematically feasible path is found. To make this process efficient, the
grasps should be ordered such that those more likely to succeed are tested
first. We propose to use grasp manipulability as a metric to prioritize grasps.
We present results of simulation experiments which demonstrate the usefulness
of our metric. Additionally, we present experiments with our physical robot
performing simple manipulation tasks with a small set of different household
objects.


title:
SPARC: Accurate and efficient finite-difference formulation and parallel
  implementation of Density Functional Theory: Extended systems

abstract:
  As the second component of SPARC (Simulation Package for Ab-initio Real-space
Calculations), we present an accurate and efficient finite-difference
formulation and parallel implementation of Density Functional Theory (DFT) for
extended systems. Specifically, employing a local formulation of the
electrostatics, the Chebyshev polynomial filtered self-consistent field
iteration, and a reformulation of the non-local force component, we develop a
finite-difference framework wherein both the energy and atomic forces can be
efficiently calculated to within desired accuracies in DFT. We demonstrate
using a wide variety of materials systems that SPARC achieves high convergence
rates in energy and forces with respect to spatial discretization to reference
plane-wave result; exponential convergence in energies and forces with respect
to vacuum size for slabs and wires; energies and forces that are consistent and
display negligible `egg-box' effect; accurate properties of crystals, slabs,
and wires; and negligible drift in molecular dynamics simulations. We also
demonstrate that the weak and strong scaling behavior of SPARC is similar to
well-established and optimized plane-wave implementations for systems
consisting up to thousands of electrons, but with a significantly reduced
prefactor. Overall, SPARC represents an attractive alternative to plane-wave
codes for performing DFT simulations of extended systems.


title:
Effects of Translation-Rotation Coupling on the Displacement Probability
  Distribution Functions of Boomerang Colloidal Particles

abstract:
  Prior studies have shown that low symmetry particles such as micro-boomerangs
exhibit behaviour of Brownian motion rather different from that of high
symmetry particles because convenient tracking points (TPs) are usually
inconsistent with the center of hydrodynamic stress (CoH) where the
translational and rotational motions are decoupled. In this paper we study the
effects of the translation-rotation coupling on the displacement probability
distribution functions (PDFs) of the boomerang colloid particles with symmetric
arms. By tracking the motions of different points on the particle symmetry
axis, we show that as the distance between the TP and the CoH is increased, the
effects of translation-rotation coupling becomes pronounced, making the
short-time 2D PDF for fixed initial orientation to change from elliptical to
crescent shape and the angle averaged PDFs from ellipsoidal-particle-like PDF
to a shape with a Gaussian top and long displacement tails. We also observed
that at long times the PDFs revert to Gaussian. This crescent shape of 2D PDF
provides a clear physical picture of the non-zero mean displacements observed
in boomerangs particles.


title: Wireless Content Caching for Small Cell and D2D Networks

abstract:
  The fifth generation wireless networks must provide fast and reliable
connectivity while coping with the ongoing traffic growth. It is of paramount
importance that the required resources, such as energy and bandwidth, do not
scale with traffic. While the aggregate network traffic is growing at an
unprecedented rate, users tend to request the same popular contents at
different time instants. Therefore, caching the most popular contents at the
network edge is a promising solution to reduce the traffic and the energy
consumption over the backhaul links. In this paper, two scenarios are
considered, where caching is performed either at a small base station, or
directly at the user terminals, which communicate using \ac{D2D}
communications. In both scenarios, joint design of the transmission and caching
policies is studied when the user demands are known in advance. This joint
design offers two different caching gains, namely, the \textit{pre-downloading}
and \textit{local caching gains}. It is shown that the finite cache capacity
limits the attainable gains, and creates an inherent tradeoff between the two
types of gains. In this context, a continuous time optimization problem is
formulated to determine the optimal transmission and caching policies that
minimize a generic cost function, such as energy, bandwidth, or throughput. The
jointly optimal solution is obtained by demonstrating that caching files at a
constant rate is optimal, which allows to reformulate the problem as a
finite-dimensional convex program. The numerical results show that the proposed
joint transmission and caching policy dramatically reduces the total cost,
which is particularised to the total energy consumption at the \ac{MBS}, as
well as to the total economical cost for the service provider, when users
demand economical incentives for delivering content to other users over the D2D
links.


title:
Constructing multi-scale gravitational energy spectra from molecular
  cloud surface density PDF -- Interplay between turbulence and gravity

abstract:
  (Abridged) We derive an analytical formula which provides estimates on
multiscale gravitational energy distribution using the observed surface density
PDF. Our analytical formalism also enables one to convert the observed column
density PDF into an estimated volume density PDF, and to obtain average radial
density profile $\rho(r)$. For a region with $N_{\rm col} \sim N^{-\gamma_{\rm
N}}$, the gravitational energy spectra is $E_{\rm p}(k)\sim k^{-4(1 -
1/\gamma_{\rm N})}$. We apply the formula to observations of molecular clouds,
and find that a scaling index of $-2$ of the surface density PDF implies that
$\rho \sim r^{-2}$ and $E_{\rm p}(k) \sim k^{-2}$. The results are valid from
the cloud scale (a few parsec) to around $\sim 0.1 \;\rm pc$. Because of the
resemblance the scaling index of the gravitational energy spectrum and the that
of the kinetic energy power spectrum of the Burgers turbulence (where $E\sim
k^{-2}$), our result indicates that gravity can act effectively against
turbulence over a multitude of physical scales. This is the critical scaling
index which divides molecular clouds into two categories: clouds like Orion and
Ophiuchus have shallower power laws, and the amount of gravitational energy is
too large for turbulence to be effective inside the cloud. Because gravity
dominates, we call this type of cloud g-type clouds. On the other hand, clouds
like the California molecular cloud and the Pipe nebula have steeper power
laws, and turbulence can overcome gravity if it can cascade effectively from
the large scale. We call this type of cloud t-type clouds. The analytical
formula can be used to determine if gravity is dominating cloud evolution when
the column density probability distribution function (PDF) can be reliably
determined.


title:
Simple approach for calculating the binding free energy of a multivalent
  particle

abstract:
  We present a simple yet accurate numerical approach to compute the free
energy of binding of multivalent objects on a receptor-coated surface. The
method correctly accounts for the fact that one ligand can bind to at most one
receptor. The numerical approach is based on a saddle-point approximation to
the computation of a complex residue. We compare our theory with the powerful
Valence-Limited Interaction Theory (VLIT) (J. Chem. Phys. 137, 094108(2012), J.
Chem. Phys. 138, 021102(2013)) and find excellent agreement in the regime where
that theory is expected to work. However, the present approach even works for
low receptor/ligand densities, where VLIT breaks down.


title:
Necessary and Sufficient Conditions for Convergence of First-Rare-Event
  Times for Perturbed Semi-Markov Processes

abstract:
  Necessary and sufficient conditions for convergence in distribution of
first-rare-event times and convergence in Skorokhod J-topology of
first-rare-event-time processes for perturbed semi-Markov processes with finite
phase space are obtained.


title: The motive of a smooth Theta divisor

abstract:
  We prove a motivic version of the Lefschetz hyperplane theorem for a smooth
ample divisor $\Theta$ on an Abelian variety. We use this to construct a motive
$P$ that realizes the primitive cohomology of $\Theta$.


title:
Universal Optimal Estimation of the Polarization of Light with Arbitrary
  Photon Statistics

abstract:
  A universal and optimal method for the polarimetry of light with arbitrary
photon statistics is presented. The method is based on the continuous
maximum-likelihood positive operator-valued measure (ML-POVM) for pure
polarization states over the surface of the Bloch sphere. The success
probability and the mean fidelity are used as the figures of merit to show its
performance. The POVM is found to attain the collective bound of polarization
estimation with respect to the mean fidelity. As demonstrations, explicit
results for the N photon Fock state, the phase-randomized coherent state
(Poisson distribution), and the thermal light are obtained. It is found that
the estimation performances for the Fock state and the Poisson distribution are
almost identical, while that for the thermal light is much worse. This suggests
that thermal light leaks less information to an eavesdropper and hence could
potentially provide more security in polarization-encoded quantum communication
protocols than a single-mode laser beam as customarily considered. Finally,
comparisons against an optimal adaptive measurement with classical
communications are made to show the better and more stable performance of the
continuous ML-POVM.


title:
One-loop divergences in non-Abelian supersymmetric theories regularized
  by BRST-invariant version of the higher derivative regularization

abstract:
  We consider a general non-Abelian renormalizable ${\cal N}=1$ supersymmetric
gauge theory, regularized by higher covariant derivatives without breaking the
BRST invariance, and calculate one-loop divergences for a general form of
higher derivative regulator and of the gauge fixing term. It is demonstrated
that the momentum integrals giving the one-loop $\beta$-function are integrals
of double total derivatives independently of a particular choice of the higher
derivative term. Evaluating them we reproduce the well-known result for the
one-loop $\beta$-function. Also we find that the three-point ghost vertices
with a single line of the quantum gauge superfield are not renormalized in the
considered approximation.


title:
Optimal approximations of the Fokker-Planck-Kolmogorov equation:
  projection, maximum likelihood eigenfunctions and Galerkin methods

abstract:
  We study optimal finite dimensional approximations of the generally
infinite-dimensional Fokker-Planck-Kolmogorov (FPK) equation, finding the curve
in a given finite-dimensional family that best approximates the exact solution
evolution. For a first local approximation we assign a manifold structure to
the family and a metric. We then project the vector field of the partial
differential equation (PDE) onto the tangent space of the chosen family, thus
obtaining an ordinary differential equation for the family parameter. A second
global approximation will be based on projecting directly the exact solution
from its infinite dimensional space to the chosen family using the nonlinear
metric projection. This will result in matching expectations with respect to
the exact and approximating densities for particular functions associated with
the chosen family, but this will require knowledge of the exact solution of
FPK. A first way around this is a localized version of the metric projection
based on the assumed density approximation. While the localization will remove
global optimality, we will show that the somewhat arbitrary assumed density
approximation is equivalent to the mathematically rigorous vector field
projection. More interestingly we study the case where the approximating family
is defined based on a number of eigenfunctions of the exact equation. In this
case we show that the local vector field projection provides also the globally
optimal approximation in metric projection, and for some families this
coincides with a Galerkin method.


title: Evidence of strong proton shape fluctuations from incoherent diffraction

abstract:
  We show within the saturation framework that measurements of exclusive vector
meson production at high energy provide evidence for strong geometric
fluctuations of the proton. In comparison, the effect of saturation scale and
color charge fluctuations is weak. This knowledge will allow detailed future
measurements of the incoherent cross section to tightly constrain the
fluctuating geometry of the proton as a function of the parton momentum
fraction $x$.


title: An optimal algorithm for bandit convex optimization

abstract:
  We consider the problem of online convex optimization against an arbitrary
adversary with bandit feedback, known as bandit convex optimization. We give
the first $\tilde{O}(\sqrt{T})$-regret algorithm for this setting based on a
novel application of the ellipsoid method to online learning. This bound is
known to be tight up to logarithmic factors. Our analysis introduces new tools
in discrete convex geometry.


title:
Simple and Accurate Dependency Parsing Using Bidirectional LSTM Feature
  Representations

abstract:
  We present a simple and effective scheme for dependency parsing which is
based on bidirectional-LSTMs (BiLSTMs). Each sentence token is associated with
a BiLSTM vector representing the token in its sentential context, and feature
vectors are constructed by concatenating a few BiLSTM vectors. The BiLSTM is
trained jointly with the parser objective, resulting in very effective feature
extractors for parsing. We demonstrate the effectiveness of the approach by
applying it to a greedy transition-based parser as well as to a globally
optimized graph-based parser. The resulting parsers have very simple
architectures, and match or surpass the state-of-the-art accuracies on English
and Chinese.


title: Overpartitions related to the mock theta function $\omega(q)$

abstract:
  It was recently shown that $q\omega(q)$, where $\omega(q)$ is one of the
third order mock theta functions, is the generating function of
$p_{\omega}(n)$, the number of partitions of a positive integer $n$ such that
all odd parts are less than twice the smallest part. In this paper, we study
the overpartition analogue of $p_{\omega}(n)$, and express its generating
function in terms of a ${}_3\phi_{2}$ basic hypergeometric series and an
infinite series involving little $q$-Jacobi polynomials. This is accomplished
by obtaining a new seven parameter $q$-series identity which generalizes a deep
identity due to the first author as well as its generalization by R.P.~Agarwal.
We also derive two interesting congruences satisfied by the overpartition
analogue, and some congruences satisfied by the associated smallest parts
function.


title: Paschke Dilations

abstract:
  In 1973 Paschke defined a factorization for completely positive maps between
C*-algebras. In this paper we show that for normal maps between von Neumann
algebras, this factorization has a universal property, and coincides with
Stinespring's dilation for normal maps into B(H).


title:
High-spin structure of $^{87}$Sr and $^{87}$Zr nuclei : shell model
  interpretation

abstract:
  In the present work we report a comprehensive analysis of shell model results
for high-spin states of $^{87}$Sr and $^{87}$Zr for recently available
experimental data within the full $f_{5/2}pg_{9/2}$ model space using JUN45 and
jj44b effective interactions developed for this model space. In this work we
have compared the energy levels, electromagnetic transition probabilities,
quadrupole and magnetic moments with available experimental data. We have
confirmed structure of high-spin states of these two nuclei which were
tentatively assigned in the recent experimental work. In the case of $^{87}$Sr,
for positive parity states up to $\sim$ 7.5 MeV, both interactions predict very
good agreement with experimental data, while negative parity states are
slightly suppressed in jj44b calculation.For the $^{87}$Zr nucleus, the jj44b
interaction predicts higher energies for the negative parity states beyond $J
\geq 27/2^{-}$. The configuration, which have one hole in $\nu g_{9/2}$
orbital, is responsible for generating the states in $^{87}$Sr. In the case of
$^{87}$Zr, low-lying positive parity states come with the configuration having
three holes in the $\nu g_{9/2}$, while the odd-parity states have
configuration $\nu (f_{5/2}^{-1}g_{9/2}^{-2})$.


title:
Signal of right-handed currents using $B\to K^*\ell^+\ell^-$ observables
  at the kinematic endpoint

abstract:
  The decay mode $B\to K^*\ell^+\ell^-$ is one of the most promising modes to
probe physics beyond the standard model (SM), since the angular distribution of
the decay products enable measurement of several constraining observables. LHCb
has recently measured these observables using $3fb^{-1}$ of data as a binned
function of $q^2$, the dilepton invariant mass squared. We find that LHCb data
implies evidence for right-handed currents, which are absent in the SM. These
conclusions are derived in the maximum $q^2$ limit and are free from hadronic
corrections. Our approach differs from other approaches that probe new physics
at low $q^2$ as it does not require estimates of hadronic parameters but relies
instead on heavy quark symmetries that are reliable at the maximum $q^2$
kinematic endpoint.


title:
On the radial solutions of a stationary Schr\"odinger system with a
  nonlinear random operator

abstract:
  In this paper, we are concerned with the existence of nonnegative solutions
for a nonlinear elliptic system. Our results are obtained by an application of
the Arzela--Ascoli theorem.


title: Spin transport in fully hexagonal boron nitride encapsulated graphene

abstract:
  We study fully hexagonal boron nitride (hBN)-encapsulated graphene spin valve
devices at room temperature. The device consists of a graphene channel
encapsulated between two crystalline hBN flakes; thick-hBN flake as a bottom
gate dielectric substrate which masks the charge impurities from SiO2/Si
substrate and single-layer thin-hBN flake as a tunnel barrier. Full
encapsulation prevents the graphene from coming in contact with any
polymer/chemical during the lithography and thus gives homogeneous charge and
spin transport properties across different regions of the encapsulated
graphene. Further, even with the multiple electrodes in between the injection
and the detection electrodes which are in conductivity mismatch regime, we
observe spin transport over 12.5 um long distance under the thin-hBN
encapsulated graphene channel, demonstrating the clean interface and the
pin-hole free nature of the thin-hBN as an efficient tunnel barrier.


title:
A Bochner type classification theorem for exceptional orthogonal
  polynomials

abstract:
  It was recently conjectured that every system of exceptional orthogonal
polynomials is related to classical orthogonal polynomials by a sequence of
Darboux transformations. In this paper we prove this conjecture, which paves
the road to a complete classification of all exceptional orthogonal
polynomials. In some sense, this paper can be regarded as the extension of
Bochner's result for classical orthogonal polynomials to the exceptional class.
As a supplementary result, we derive a canonical form for exceptional operators
based on a bilinear formalism, and prove that every exceptional operator has
trivial monodromy at all primary poles.


title: Field-driven quantum phase transitions in $S=1/2$ spin chains

abstract:
  We study the magnetization process of a 1D extended Heisenberg model, the
$J$-$Q$ model, as a function of an external magnetic field. In this model, $J$
represents the traditional antiferromagnetic Heisenberg exchange and $Q$ is the
strength of a competing four-spin interaction. Without external field, this
system hosts a twofold-degenerate dimerized (valence-bond solid) state above a
critical value $q_c\approx 0.85$ where $q\equiv Q/J$. The dimer order is
destroyed and replaced by a partially polarized translationally invariant state
at a critical field value. We find magnetization jumps (metamagnetism) between
the partially polarized and fully polarized state for $q>q_{\rm min}$, where we
have calculated $q_{\rm min}=2/9$ exactly. For $q>q_{\rm min}$ two magnons
(flipped spins on a fully polarized background) attract and form a bound state.
Quantum Monte Carlo studies confirm that the bound state corresponds to the
first step of an instability leading to a finite magnetization jump for
$q>q_{\rm min}$. Our results show that neither geometric frustration nor
spin-anisotropy are necessary conditions for metamagnetism. Working in the
two-magnon subspace, we also find evidence pointing to the existence of
metamagnetism in the unfrustrated $J_1$-$J_2$ chain ($J_1>0$, $J_2<0$), but
only if $J_2$ is spin-anisotropic. We also investigate quantum-critical scaling
near the transition into the fully polarized state for $q\le q_{\rm min}$ at
$T>0$. While the expected `zero-scale-factor' universality is clearly seen for
$q=0$ and $q\ll q_{\rm min}$; closer to $q_{\rm min}$ we find that extremely
low temperatures are required to observe the asymptotic behavior, due to the
influence of the tricritical point at $q_{\rm min}$, which leads to a
cross-over at a temperature $T^*(q)$ between logarithmic tricritical scaling
and zero-scale-factor universality, with $T^*(q)\to 0$ when $q\to q_{\rm min}$.


title: An Ensemble EM Algorithm for Bayesian Variable Selection

abstract:
  We study the Bayesian approach to variable selection in the context of linear
regression. Motivated by a recent work by Rockova and George (2014), we propose
an EM algorithm that returns the MAP estimate of the set of relevant variables.
Due to its particular updating scheme, our algorithm can be implemented
efficiently without inverting a large matrix in each iteration and therefore
can scale up with big data. We also show that the MAP estimate returned by our
EM algorithm achieves variable selection consistency even when $p$ diverges
with $n$. In practice, our algorithm could get stuck with local modes, a common
problem with EM algorithms. To address this issue, we propose an ensemble EM
algorithm, in which we repeatedly apply the EM algorithm on a subset of the
samples with a subset of the covariates, and then aggregate the variable
selection results across those bootstrap replicates. Empirical studies have
demonstrated the superior performance of the ensemble EM algorithm.


title:
Tracing dynamics of laser-induced fields on ultra-thin foils using
  complementary imaging with streak deflectometry

abstract:
  We present a detailed study of the electric and magnetic fields, which are
created on plasma vacuum interfaces as a result of highly intense
laser-matter-interactions. For the field generation ultra-thin polymer foils
were irradiated with high intensity femtosecond and picosecond laser pulses
with ultra-high contrast. To determine the temporal evolution and the spatial
distribution of these fields the proton streak deflectometry method has been
developed further and applied in two different imaging configurations. It
enabled us to gather complementary information about the investigated field
structure, in particular about the influence of different field components
(parallel and normal to the target surface) and the impact of a moving ion
front. The applied ultra-high laser contrast significantly increased the
reproducibility of the experiment and improved the accuracy of the imaging
method. In order to explain the experimental observations, which were obtained
by applying ultra-short laser pulses, two different analytical models have been
studied in detail. Their ability to reproduce the streak deflectometry
measurements was tested on the basis of three-dimensional particle simulations.
A modification and combination of the two models allowed for an extensive and
accurate reproduction of the experimental results in both imaging
configurations. The controlled change of the laser pulse duration from 50
femtoseconds to 2.7 picoseconds led to a transition of the dominating force
acting on the probing proton beam at the rear side of the polymer foil. The
applied proton deflectometry method allowed for an unambiguous determination of
the magnetic field polarity at the rear side of the ultra-thin foil.


title:
Properties of the random-singlet phase: from the disordered Heisenberg
  chain to an amorphous valence-bond solid

abstract:
  We use a strong-disorder renormalization group (SDRG) method and ground-state
quantum Monte Carlo (QMC) simulations to study S=1/2 spin chains with random
couplings, calculating disorder-averaged spin and dimer correlations. The QMC
simulations demonstrate logarithmic corrections to the power-law decaying
correlations obtained with the SDRG scheme. The same asymptotic forms apply
both for systems with standard Heisenberg exchange and for certain multi-spin
couplings leading to spontaneous dimerization in the clean system. We show that
the logarithmic corrections arise in the valence-bond (singlet pair) basis from
a contribution that can not be generated by the SDRG scheme. In the model with
multi-spin couplings, where the clean system dimerizes spontaneously, random
singlets form between spinons localized at domain walls in the presence of
disorder. This amorphous valence-bond solid is asymptotically a random-singlet
state and only differs from the random-exchange Heisenberg chain in its
short-distance properties.


title: Coherent absorption of N00N states

abstract:
  Recent results in deeply subwavelength thickness films demonstrated coherent
control and logical gate operations with both classical and single photon light
sources. However, quantum processing and devices typically involve more than
one photon and non-trivial input quantum states. Here we experimentally
investigate two-photon N00N state coherent absorption in a multilayer graphene
film. Depending on the N00N state input phase, it is possible to selectively
choose between single or two photon absorption of the input state in the
graphene film. These results demonstrate that coherent absorption in the
quantum regime exhibits unique features opening up applications in multiphoton
spectroscopy and imaging.


title: On the overlaps between eigenvectors of correlated random matrices

abstract:
  We obtain general, exact formulas for the overlaps between the eigenvectors
of large correlated random matrices, with additive or multiplicative noise.
These results have potential applications in many different contexts, from
quantum thermalisation to high dimensional statistics. We find that the
overlaps only depend on measurable quantities, and do not require the knowledge
of the underlying "true" (noiseless) matrices. We apply our results to the case
of empirical correlation matrices, that allow us to estimate reliably the width
of the spectrum of the true correlation matrix, even when the latter is very
close to the identity. We illustrate our results on the example of stock
returns correlations, that clearly reveal a non trivial structure for the bulk
eigenvalues. We also apply our results to the problem of matrix denoising in
high dimension.


title:
On the potential of atmospheric Cherenkov telescope arrays for resolving
  TeV gamma-ray sources in the Galactic Plane

abstract:
  The potential of an array of imaging atmospheric Cherenkov telescopes to
detect gamma-ray sources in complex regions has been investigated. The basic
characteristics of the gamma-ray instrument have been parametrized using simple
analytic representations. In addition to the ideal (Gaussian form) point spread
function (PSF), the impact of more realistic non-Gaussian PSFs with tails has
been considered. Simulations of isolated point-like and extended sources have
been used as a benchmark to test and understand the response of the instrument.
The capability of the instrument to resolve multiple sources has been analyzed
and the corresponding instrument sensitivities calculated. The results are of
particular interest for weak gamma-ray emitters located in crowded regions of
the Galactic plane, where the chance of clustering of two or more gamma-ray
sources within 1 degree is high.


title: Interpreting the $X(5568)$

abstract:
  A variety of options for interpreting the D\O{} state, $X(5568)$, are
examined. We find that threshold, cusp, molecular, and tetraquark models are
all unfavoured. Several experimental tests for unravelling the nature of the
signal are suggested.


title:
Associative algebras for (logarithmic) twisted modules for a vertex
  operator algebra

abstract:
  We construct two associative algebras from a vertex operator algebra $V$ and
a general automorphism $g$ of $V$. The first, called $g$-twisted zero-mode
algebra, is a subquotient of what we call $g$-twisted universal enveloping
algebra of $V$. These algebras are generalizations of the corresponding
algebras introduced and studied by Frenkel-Zhu and Nagatomo-Tsuchiya in the
(untwisted) case that $g$ is the identity. The other is a generalization of the
$g$-twisted version of Zhu's algebra for suitable $g$-twisted modules
constructed by Dong-Li-Mason when the order of $g$ is finite. We are mainly
interested in $g$-twisted $V$-modules introduced by the first author in the
case that $g$ is of infinite order and does not act on $V$ semisimply. In this
case, twisted vertex operators in general involve the logarithm of the
variable. We construct functors between categories of suitable modules for
these associative algebras and categories of suitable (logarithmic) $g$-twisted
$V$-modules. Using these functors, we prove that the $g$-twisted zero-mode
algebra and the $g$-twisted generalization of Zhu's algebra are in fact
isomorphic.


title:
The GMRT 150 MHz All-sky Radio Survey: First Alternative Data Release
  TGSS ADR1

abstract:
  We present the first full release of a survey of the 150 MHz radio sky,
observed with the Giant Metrewave Radio Telescope between April 2010 and March
2012 as part of the TGSS project. Aimed at producing a reliable compact source
survey, our automated data reduction pipeline efficiently processed more than
2000 hours of observations with minimal human interaction. Through application
of innovative techniques such as image-based flagging, direction-dependent
calibration of ionospheric phase errors, correcting for systematic offsets in
antenna pointing, and improving the primary beam model, we created good quality
images for over 95 percent of the 5336 pointings. Our data release covers
36,900 square degrees (or 3.6 pi steradians) of the sky between -53 deg and +90
deg DEC, which is 90 percent of the total sky. The majority of pointing images
have a background RMS noise below 5 mJy/beam with an approximate resolution of
25" x 25" (or 25" x 25" / cos (DEC - 19 deg) for pointings south of 19 deg
DEC). We have produced a catalog of 0.62 Million radio sources derived from an
initial, high reliability source extraction at the 7 sigma level. For the bulk
of the survey, the measured overall astrometric accuracy is better than 2" in
RA and DEC, while the flux density accuracy is estimated at ~10 percent. Within
the scope of the TGSS ADR project, the source catalog as well as 5336 mosaic
images (5 deg x 5 deg) and an image cutout service, are made publicly available
online as a service to the astronomical community. Next to enabling a wide
range of different scientific investigations, we anticipate that these survey
products provide a solid reference for various new low-frequency radio aperture
array telescopes (LOFAR, LWA, MWA, SKA-low), and can play an important role in
characterizing the EoR foreground. The TGSS ADR project aims at continuously
improving the quality of the survey data products.


title: Gauge Invariants and Correlators in Flavoured Quiver Gauge Theories

abstract:
  In this paper we study the construction of holomorphic gauge invariant
operators for general quiver gauge theories with flavour symmetries. Using a
characterisation of the gauge invariants in terms of equivalence classes
generated by permutation actions, along with representation theory results in
symmetric groups and unitary groups, we give a diagonal basis for the 2-point
functions of holomorphic and anti-holomorphic operators. This involves a
generalisation of the previously constructed Quiver Restricted Schur operators
to the flavoured case. The 3-point functions are derived and shown to be given
in terms of networks of symmetric group branching coefficients. The networks
are constructed through cutting and gluing operations on the quivers.


title: Scanning Josephson spectroscopy on the atomic scale

abstract:
  The Josephson effect provides a direct method to probe the strength of the
pairing interaction in superconductors. By measuring the phase fluctuating
Josephson current between a superconducting tip of a scanning tunneling
microscope (STM) and a BCS superconductor with isolated magnetic adatoms on its
surface, we demonstrate that the spatial variation of the pairing order
parameter can be characterized on the atomic scale. This system provides an
example where the local pairing potential suppression is not directly reflected
in the spectra measured via quasipartcile tunneling. Spectroscopy with such
superconducting tips also show signatures of previously unexplored Andreev
processes through individual impurity-bound Shiba states. The atomic resolution
achieved here establishes scanning Josephson spectroscopy as a promising
technique for the study of novel superconducting phases.


title: Measures on Hilbert-Schmidt operators and algebraic quantum field theory

abstract:
  We present a general construction of non-Gaussian probability measures on the
space of distributional kernels obeying a natural extension of the
Osterwalder-Schrader axioms of Euclidean quantum field theory in arbitrary
space-time dimension $d$. These measures may be interpreted as corresponding to
scalar massive quantum fields with polynomial self-interaction. As a
consequence, we obtain examples of non-free models satisfying the Haag-Kastler
axioms of algebraic quantum field theory for arbitrary $d$. When $d<4$ we are
able to transfer the measures to the space of distributions and verify the
standard Osterwalder-Schrader axioms, hence, by a well-known reconstruction
theorem, we also obtain quantum field theory models satisfying the axioms of
Wightman.


title:
Water on Silicene: Hydrogen Bond Autocatalysis Induced
  Physisorption-Chemisorption-Dissociation Transition

abstract:
  A single water molecule has nothing special. However, macroscopic water
displays many anomalous properties at the interface, such as a high surface
tension, hydrophobicity and hydrophillicity. Although the underlying mechanism
is still elusive, hydrogen bond is expected to have played an important role.
An interesting question is if the few-water molecule clusters will be
qualitatively different from a single molecule. Using adsorption behavior as an
example, by carefully choosing two-dimensional silicene as the substrate
material, we demonstrate that water monomer, dimer and trimer show contrasting
properties. The additional water molecules in dimer and trimer induce a
transition from physisorption to chemisorption then to dissociation on
silicene. Such a hydrogen bond autocatalytic effect is expected to have a broad
application potential in silicene-based water molecule sensor and metal-free
catalyst for water dissociation.


title: Critical collapse of rotating radiation fluids

abstract:
  We present results from the first fully relativistic simulations of the
critical collapse of rotating radiation fluids. We observe critical scaling
both in subcritical evolutions, in which case the fluid disperses to infinity
and leaves behind flat space, and in supercritical evolutions that lead to the
formation of black holes. We measure the mass and angular momentum of these
black holes, and find that both show critical scaling with critical exponents
that are consistent with perturbative results. The critical exponents are
universal; they are not affected by angular momentum, and are independent of
the direction in which the critical curve, which separates subcritical from
supercritical evolutions in our two-dimensional parameter space, is crossed. In
particular, these findings suggest that the angular momentum decreases more
rapidly than the square of the mass, so that, as criticality is approached, the
collapse leads to the formation of a non-spinning black hole. We also
demonstrate excellent agreement of our numerical data with new closed-form
extensions of power-law scalings that describe the mass and angular momentum of
rotating black holes formed close to criticality.


title:
Adaptive Mitigation of Multi-Virus Propagation: A Passivity-Based
  Approach

abstract:
  Malware propagation poses a growing threat to networked systems such as
computer networks and cyber-physical systems. Current approaches to defending
against malware propagation are based on patching or filtering susceptible
nodes at a fixed rate. When the propagation dynamics are unknown or uncertain,
however, the static rate that is chosen may be either insufficient to remove
all viruses or too high, incurring additional performance cost. In this paper,
we formulate adaptive strategies for mitigating multiple malware epidemics when
the propagation rate is unknown, using patching and filtering-based defense
mechanisms. In order to identify conditions for ensuring that all viruses are
asymptotically removed, we show that the malware propagation, patching, and
filtering processes can be modeled as coupled passive dynamical systems. We
prove that the patching rate required to remove all viruses is bounded above by
the passivity index of the coupled system, and formulate the problem of
selecting the minimum-cost mitigation strategy. Our results are evaluated
through numerical study.


title: MINLP in Transmission Expansion Planning

abstract:
  Transmission expansion planning requires forecasts of demand for electric
power and a model of the underlying physics, i.e., power flows. We present
three approaches to deriving exact solutions to the transmission expansion
planning problem in the alternating-current model, for a given load.


title: A Fast Parameterized Algorithm for Co-Path Set

abstract:
  The k-CO-PATH SET problem asks, given a graph G and a positive integer k,
whether one can delete k edges from G so that the remainder is a collection of
disjoint paths. We give a linear-time fpt algorithm with complexity
O^*(1.588^k) for deciding k-CO-PATH SET, significantly improving the previously
best known O^*(2.17^k) of Feng, Zhou, and Wang (2015). Our main tool is a new
O^*(4^{tw(G)}) algorithm for CO-PATH SET using the Cut&Count framework, where
tw(G) denotes treewidth. In general graphs, we combine this with a branching
algorithm which refines a 6k-kernel into reduced instances, which we prove have
bounded treewidth.


title:
Double-phase transition and giant positive magnetoresistance in the
  quasi-skutterudite Gd$_3$Ir$_4$Sn$_{13}$

abstract:
  The magnetic, thermodynamic and electrical/thermal transport properties of
the caged-structure quasi-skutterudite Gd$_3$Ir$_4$Sn$_{13}$ are
re-investigated. The magnetization $M(T)$, specific heat $C_p(T)$ and the
resistivity $\rho(T)$ reveal a double-phase transition -- at $T_{N1}\sim$ 10~K
and at $T_{N2}\sim$ 8.8~K -- which was not observed in the previous report on
this compound. The antiferromagnetic transition is also visible in the thermal
transport data, thereby suggesting a close connection between the electronic
and lattice degrees of freedom in this Sn-based quasi-skutterudite. The
temperature dependence of $\rho(T)$ is analyzed in terms of a power-law for
resistivity pertinent to Fermi liquid picture. Giant, positive
magnetoresistance (MR) $\approx$ 80$\%$ is observed in Gd$_3$Ir$_4$Sn$_{13}$ at
2~K with the application of 9~T. The giant MR and the double magnetic
transition can be attributed to the quasi-cages and layered antiferromagnetic
structure of Gd$_3$Ir$_4$Sn$_{13}$ vulnerable to structural distortions and/or
dipolar or spin-reorientation effects. The giant value of MR observed in this
class of 3:4:13 type alloys, especially in a Gd-compound, is the highlight of
this work.


title:
Exceptional collections and the bicanonical map of Keum's fake
  projective planes

abstract:
  We apply the recent results of Galkin et al. [GKMS15] to study some
geometrical features of Keum's fake projective planes. Among other things, we
show that the bicanonical map of Keum's fake projective planes is always an
embedding. Moreover, we construct a nonstandard exceptional collection on the
unique fake projective plane $X$ with $H_{1}(X;
\mathbb{Z})=(\mathbb{Z}/2\mathbb{Z})^{4}$.


title: On Data Dependence in Distributed Stochastic Optimization

abstract:
  We study a distributed consensus-based stochastic gradient descent (SGD)
algorithm and show that the rate of convergence involves the spectral
properties of two matrices: the standard spectral gap of a weight matrix from
the network topology and a new term depending on the spectral norm of the
sample covariance matrix of the data. This data-dependent convergence rate
shows that distributed SGD algorithms perform better on datasets with small
spectral norm. Our analysis method also allows us to find data-dependent
convergence rates as we limit the amount of communication. Spreading a fixed
amount of data across more nodes slows convergence; for asymptotically growing
data sets we show that adding more machines can help when minimizing
twice-differentiable losses.


title: Linear Sum Assignment with Edition

abstract:
  We consider the problem of transforming a set of elements into another by a
sequence of elementary edit operations, namely substitutions, removals and
insertions of elements. Each possible edit operation is penalized by a
non-negative cost and the cost of a transformation is measured by summing the
costs of its operations. A solution to this problem consists in defining a
transformation having a minimal cost, among all possible transformations. To
compute such a solution, the classical approach consists in representing
removal and insertion operations by augmenting the two sets so that they get
the same size. This allows to express the problem as a linear sum assignment
problem (LSAP), which thus finds an optimal bijection (or permutation, perfect
matching) between the two augmented sets. While the LSAP is known to be
efficiently solvable in polynomial time complexity, for instance with the
Hungarian algorithm, useless time and memory are spent to treat the elements
which have been added to the initial sets. In this report, we show that the
problem can be formalized as an extension of the LSAP which considers only one
additional element in each set to represent removal and insertion operations. A
solution to the problem is no longer represented as a bijection between the two
augmented sets. We show that the considered problem is a binary linear program
(BLP) very close to the LSAP. While it can be solved by any BLP solver, we
propose an adaptation of the Hungarian algorithm which improves the time and
memory complexities previously obtained by the approach based on the LSAP. The
importance of the improvement increases as the size of the two sets and their
absolute difference increase. Based on the analysis of the problem presented in
this report, other classical algorithms can be adapted.


title: A ranking approach to global optimization

abstract:
  We consider the problem of maximizing an unknown function over a compact and
convex set using as few observations as possible. We observe that the
optimization of the function essentially relies on learning the induced
bipartite ranking rule of f. Based on this idea, we relate global optimization
to bipartite ranking which allows to address problems with high dimensional
input space, as well as cases of functions with weak regularity properties. The
paper introduces novel meta-algorithms for global optimization which rely on
the choice of any bipartite ranking method. Theoretical properties are provided
as well as convergence guarantees and equivalences between various optimization
methods are obtained as a by-product. Eventually, numerical evidence is given
to show that the main algorithm of the paper which adapts empirically to the
underlying ranking structure essentially outperforms existing state-of-the-art
global optimization algorithms in typical benchmarks.


title: Some Results on Generalized Multiplicative Perfect Numbers

abstract:
  In this article, based on ideas and results by J. S\'andor (2001, 2004), we
define $k$-multiplicatively $e$-perfect numbers and $k$-multiplicatively
$e$-superperfect numbers and prove some results on them. We also characterize
the $k$-$T_0T^\ast$-perfect numbers defined by Das and Saikia (2013) in
details.


title: Theoretical description of nuclear collective excitations

abstract:
  Density functional theory is a preferred microscopic method for calculation
of nuclear properties over the whole nuclear chart. Besides ground-state
properties, which are calculated by Hartree-Fock theory, nuclear excitations
can be described by means of Random Phase Approximation (RPA). The main
objective of the present work is to give Skyrme RPA formalism for spherically
symmetric nuclei, using the techniques of angular-momentum coupling. Various
auxiliary topics, such as Hartree-Fock theory, Coulomb integral, center-of-mass
corrections and pairing, are treated as well. RPA method is derived also for
axially deformed nuclei. The derived formulae are then implemented in the
computer code and utilized for calculation of some physical results. After
thorough investigation of the precision aspects of the calculation, the
following topics are treated as examples: toroidal nature of the low-energy
(pygmy) part of the E1 resonance, giant resonances of various multipolarities
in deformed nucleus Sm-154, and magnetic dipole (M1) transitions in deformed
Cr-50.
  Keywords: Random Phase Approximation, Skyrme functional, giant resonances in
nuclei, reduced matrix elements
  I thank Jiri Mares and F. Knapp for their comments, which were taken into
account in the first revision.


title: Input graph: the hidden geometry in controlling complex networks

abstract:
  The ability to control a complex network towards a desired behavior relies on
our understanding of the complex nature of these social and technological
networks. The existence of numerous control schemes in a network promotes us to
wonder: what is the underlying relationship of all possible input nodes? Here
we introduce input graph, a simple geometry that reveals the complex
relationship between all control schemes and input nodes. We prove that the
node adjacent to an input node in the input graph will appear in another
control scheme, and the connected nodes in input graph have the same type in
control, which they are either all possible input nodes or not. Furthermore, we
find that the giant components emerge in the input graphs of many real
networks, which provides a clear topological explanation of bifurcation
phenomenon emerging in dense networks and promotes us to design an efficient
method to alter the node type in control. The findings provide an insight into
control principles of complex networks and offer a general mechanism to design
a suitable control scheme for different purposes.


title: Comparison of Coronal Extrapolation Methods for Cycle 24 Using HMI Data

abstract:
  Two extrapolation models of the solar coronal magnetic field are compared
using magnetogram data from the SDO/HMI instrument. The two models, a
horizontal current-current sheet-source surface (HCCSSS) model and a potential
field-source surface (PFSS) model differ in their treatment of coronal
currents. Each model has its own critical variable, respectively the radius of
a cusp surface and a source surface, and it is found that adjusting these
heights over the period studied allows better fit between the models and the
solar open flux at 1 AU as calculated from the Interplanetary Magnetic Field
(IMF). The HCCSSS model provides the better fit for the overall period from
2010 November to 2015 May as well as for two subsets of the period - the
minimum/rising part of the solar cycle, and the recently-identified peak in the
IMF from mid-2014 to mid-2015 just after solar maximum. It is found that a
HCCSSS cusp surface height of 1.7 Rsun provides the best fit to the IMF for the
overall period, while 1.7 & 1.9 Rsun give the best fits for the two subsets.
The corresponding values for the PFSS source surface height are 2.1, 2.2 and
2.0 Rsun respectively. This means that the HCCSSS cusp surface rises as the
solar cycle progresses while the PFSS source surface falls.


title:
On the number of equivalence classes of invertible Boolean functions
  under action of permutation of variables on domain and range

abstract:
  Let $V_n$ be the number of equivalence classes of invertible maps from
$\{0,1\}^n$ to $\{0,1\}^n$, under action of permutation of variables on domain
and range. So far, the values $V_n$ have been known for $n\le 6$. This paper
describes the procedure by which the values of $V_n$ are calculated for $n\le
30$.


title: NetMemex: Providing Full-Fidelity Traffic Archival

abstract:
  NetMemex explores efficient network traffic archival without any loss of
information. Unlike NetFlow-like aggregation, NetMemex allows retrieving the
entire packet data including full payload, which makes it useful in forensic
analysis, networked and distributed system research, and network
administration. Different from packet trace dumps, NetMemex performs
sophisticated data compression for small storage space use and optimizes the
data layout for fast query processing. NetMemex takes advantage of high-speed
random access of flash drives and inexpensive storage space of hard disk
drives. These efforts lead to a cost-effective yet high-performance full
traffic archival system. We demonstrate that NetMemex can record full-fidelity
traffic at near-Gbps rates using a single commodity machine, handling common
queries at up to 90.1 K queries/second, at a low storage cost comparable to
conventional hard disk-only traffic archival solutions.


title: Fourier-transform Ghost Imaging with Hard X-rays

abstract:
  Knowledge gained through X-ray crystallography fostered structural
determination of materials and greatly facilitated the development of modern
science and technology in the past century. Atomic details of sample structures
is achievable by X-ray crystallography, however, it is only applied to
crystalline structures. Imaging techniques based on X-ray coherent diffraction
or zone plates are capable of resolving the internal structure of
non-crystalline materials at nanoscales, but it is still a challenge to achieve
atomic resolution. Here we demonstrate a novel lensless Fourier-transform ghost
imaging method with pseudo-thermal hard X-rays by measuring the second-order
intensity correlation function of the light. We show that high resolution
Fourier-transform diffraction pattern of a complex amplitude sample can be
achieved at Fresnel region and the amplitude and phase distributions of a
sample in spatial domain can be retrieved successfully. The method of lensless
X-ray Fourier-transform ghost imaging extends X-ray crystallography to
non-crystalline samples, and its spatial resolution is limited only by the
wavelength of the X-ray, thus atomic resolution should be routinely obtainable.
Since highly coherent X-ray source is not required, comparing to conventional
X-ray coherent diffraction imaging, the method can be implemented with
laboratory X-ray sources, and it also provides a potential solution for
lensless diffraction imaging with fermions, such as neutron and electron where
the intensive coherent source usually is not available.


title: Linear and Nonlinear Frequency-Division Multiplexing

abstract:
  Two signal multiplexing schemes for optical fiber communication are
considered: Wavelength-division multiplexing (WDM) and nonlinear
frequency-division multiplexing (NFDM), based on the nonlinear Fourier
transform (NFT). Achievable information rates (AIRs) of NFDM and WDM are
compared in a network scenario with an ideal lossless model of the optical
fiber in the defocusing regime. It is shown that the NFDM AIR is greater than
the WDM AIR subject to a bandwidth and average power constraint, in a
representative system with one symbol per user. The improvement results from
nonlinear signal multiplexing.


title:
Existence of nontrivial topologically protected states at grain
  boundaries in bilayer graphene: signatures and electrical switching

abstract:
  Recent experiments [L. Ju et al., Nature, 2015, 520, 650] confirm the
existence of gapless states at domain walls created in gated bilayer graphene,
when the sublattice stacking is changed from AB to BA. These states are
significant because they are topologically protected, valley-polarized and give
rise to conductance along the domain wall. Current theoretical models predict
the appearance of such states only at domain walls, which preserve the
sublattice order. Here we show that the appearance of the topologically
protected states in stacking domain walls can be much more common in bilayer
graphene, since they can also emerge in unexpected geometries, e.g., at grain
boundaries with atomic-scale topological defects. We focus on a bilayer system
in which one of the layers contains a line of octagon-double pentagon defects,
that mix graphene sublattices. We demonstrate that gap states are preserved
even with pentagonal defects. Remarkably, unlike previous predictions, the
number of gap states changes by inverting the gate polarization, yielding an
asymmetric conductance along the grain boundary under gate reversal. This
effect, linked to defect states, should be detectable in transport measurements
and could be exploited in electrical switches.


title:
Friction coefficient and viscosity of polymer brushes with and without
  free polymers as slip agents

abstract:
  There is ample evidence that polymer brushes reduce friction between
surfaces. Several industrial applications take advantage of this fact, such as
those in plastic bag production, where the brushes act as slip agents; however,
the complex mechanisms that give rise to such reduction of friction are not yet
fully understood. In this work we report coarse grained, dissipative particle
dynamics simulations carried out for surfaces functionalized with erukamide
brushes, a polymer commonly used in the plastics industry as a slip agent
between surfaces. We calculate their rheological properties, such as the
coefficient of friction (COF) and the viscosity, {\eta}, as functions of the
number of chains grafted on the surfaces under the influence of stationary,
Couette flow. Moreover, we consider also the case when a fraction of the
erukamide chains is not adsorbed and moves freely between the surfaces. We show
that the COF reaches an equilibrium value of about 0.29 in these two cases, in
agreement with experimental results. On other hand, the viscosity grows
monotonically, as a result of the increasing collisions when the erukamide
content is increased. The force between brushes is found to be in agreement
with predictions from scaling theories. We find that the addition to free
chains helps stabilize the film formed by the brushes and the solvent, as
others have found experimentally. The mechanisms that give rise to these
phenomena are studied in detail.


title: Rapid building detection using machine learning

abstract:
  This work describes algorithms for performing discrete object detection,
specifically in the case of buildings, where usually only low quality RGB-only
geospatial reflective imagery is available. We utilize new candidate search and
feature extraction techniques to reduce the problem to a machine learning (ML)
classification task. Here we can harness the complex patterns of contrast
features contained in training data to establish a model of buildings. We avoid
costly sliding windows to generate candidates; instead we innovatively stitch
together well known image processing techniques to produce candidates for
building detection that cover 80-85% of buildings. Reducing the number of
possible candidates is important due to the scale of the problem. Each
candidate is subjected to classification which, although linear, costs time and
prohibits large scale evaluation. We propose a candidate alignment algorithm to
boost classification performance to 80-90% precision with a linear time
algorithm and show it has negligible cost. Also, we propose a new concept
called a Permutable Haar Mesh (PHM) which we use to form and traverse a search
space to recover candidate buildings which were lost in the initial
preprocessing phase.


title: A symmetric difference-differential Lax pair for Painlev\'e VI

abstract:
  We present a Lax pair for the sixth Painlev\'e equation arising as a
continuous isomonodromic deformation of a system of linear difference equations
with an additional symmetry structure. We call this a symmetric
difference-differential Lax pair. We show how the discrete isomonodromic
deformations of the associated linear problem gives us a discrete version of
the fifth Painlev\'e equation. By considering degenerations we obtain symmetric
difference-differential Lax pairs for the fifth Painlev\'e equation and the
various degenerate versions of the third Painlev\'e equation.


title: Internet Computing: Using Reputation to Select Workers from a Pool

abstract:
  The assignment and execution of tasks over the Internet is an inexpensive
solution in contrast with supercomputers. We consider an Internet-based
Master-Worker task computing approach, such as SETI@home. A master process
sends tasks, across the Internet, to worker processors. Workers execute, and
report back a result. Unfortunately, the disadvantage of this approach is the
unreliable nature of the worker processes. Through different studies, workers
have been categorized as either malicious (always report an incorrect result),
altruistic (always report a correct result), or rational (report whatever
result maximizes their benefit). We develop a reputation-based mechanism that
guarantees that, eventually, the master will always be receiving the correct
task result. We model the behavior of the rational workers through
reinforcement learning, and we present three different reputation types to
choose, for each computational round, the most reputable from a pool of
workers. As workers are not always available, we enhance our reputation scheme
to select the most responsive workers. We prove sufficient conditions for
eventual correctness under the different reputation types. Our analysis is
complemented by simulations exploring various scenarios. Our simulation results
expose interesting trade-offs among the different reputation types, workers
availability, and cost.


title: Academic Torrents: Scalable Data Distribution

abstract:
  As competitions get more popular, transferring ever-larger data sets becomes
infeasible and costly. For example, downloading the 157.3 GB 2012 ImageNet data
set incurs about $4.33 in bandwidth costs per download. Downloading the full
ImageNet data set takes 33 days. ImageNet has since become popular beyond the
competition, and many papers and models now revolve around this data set. For
sharing such an important resource to the machine learning community, the
sharers of ImageNet must shoulder a large bandwidth burden. Academic Torrents
reduces this burden for disseminating competition data, and also increases
download speeds for end users. Academic Torrents is run by a pending
nonprofit.. By augmenting an existing HTTP server with a peer-to-peer swarm,
requests get re-routed to get data from downloaders. While existing systems
slow down with more users, the benefits of Academic Torrents grow, with
noticeable effects even when only one other person is downloading.


title: Irrelevance of the boundary on the magnetization of metals

abstract:
  The macroscopic current density responsible for the mean magnetization
$\mathbf{M}$ of a uniformly magnetized bounded sample is localized near its
surface. In order to evaluate $\mathbf{M}$ one needs the current distribution
in the whole sample: bulk and boundary. In recent years it has been shown that
the boundary has no effect on $\mathbf{M}$ in insulators: therein, $\mathbf{M}$
admits an alternative expression, not based on currents. $\mathbf{M}$ can be
expressed in terms of the bulk electron distribution only, which is
"nearsighted" (exponentially localized); this virtue is not shared by metals,
having a qualitatively different electron distribution. We show, by means of
simulations on paradigmatic model systems, that even in metals the $\mathbf{M}$
value can be retrieved in terms of the bulk electron distribution only.


title:
Nonlinear Transient Dynamics of Photoexcited Silicon Nanoantenna for
  Ultrafast All-Optical Signal Processing

abstract:
  Optically generated electron-hole plasma in high-index dielectric
nanostructures was demonstrated as a means of tuning of their optical
properties. However, until now an ultrafast operation regime of such plasma
driven nanostructures has not been attained. Here, we perform pump-probe
experiments with resonant silicon nanoparticles and report on dense optical
plasma generation near the magnetic dipole resonance with ultrafast (about 2.5
ps) relaxation rate. Basing on experimental results, we develop an analytical
model describing transient response of a nanocrystalline silicon nanoparticle
to an intense laser pulse and show theoretically that plasma induced optical
nonlinearity leads to ultrafast reconfiguration of the scattering power
pattern. We demonstrate 100 fs switching to unidirectional scattering regime
upon irradiation of the nanoparticle by an intense femtosecond pulse. Our work
lays the foundation for developing ultracompact and ultrafast all-optical
signal processing devices.


title: Floquet bound states around defects and adatoms in graphene

abstract:
  Recent studies have focused on laser-induced gaps in graphene which have been
shown to have a topological origin, thereby hosting robust states at the sample
edges. While the focus has remained mainly on these topological chiral edge
states, the Floquet bound states around defects lack a detailed study. In this
paper we present such a study covering large defects of different shape and
also vacancy-like defects and adatoms at the dynamical gap at $\hbar\Omega/2$
($\hbar\Omega$ being the photon energy). Our results, based on analytical
calculations as well as numerics for full tight-binding models, show that the
bound states are chiral and appear in a number which grows with the defect
size. Furthermore, while the bound states exist regardless the type of the
defect's edge termination (zigzag, armchair, mixed), the spectrum is strongly
dependent on it. In the case of top adatoms, the bound states quasi-energies
depend on the adatoms energy. The appearance of such bound states might open
the door to the presence of topological effects on the bulk transport
properties of dirty graphene.


title: Combinatorial bases of basic modules for $C_{n}\sp{(1)}$

abstract:
  J.~Lepowsky and R.~L.~Wilson initiated the approach to combinatorial
Rogers-Ramanujan type identities via vertex operator constructions of standard
(i.e. integrable highest weight) representations of affine Kac-Moody Lie
algebras. A.~Meurman and M.~Primc developed further this approach for
$\mathfrak{sl}(2,\mathbb C)\widetilde{}\ $ by using vertex operator algebras
and Verma modules. In this paper we use the same method to construct
combinatorial bases of basic modules for affine Lie algebras of type
$C_{n}\sp{(1)}$ and, as a consequence, we obtain a series of Rogers-Ramanujan
type identities. A major new insight is a combinatorial parametrization of
leading terms of defining relations for level one standard modules for affine
Lie algebra of type $C_{n}\sp{(1)}$.


title: Narrow-line Seyfert 1 galaxies - rebels of the AGN family

abstract:
  Narrow-line Seyfert 1 galaxies, with their extreme properties, defy our
current knowledge of active galactic nuclei and relativistic jet systems. They
excite, and might help us answer, many questions concerning the evolution and
unification of AGN, but still remain a poorly studied class of AGN as such.
  We did an extensive study of a large sample of NLS1s using various
statistical methods, for example, multiwavelength correlations and principal
component analysis. We wanted to examine how and where in NLS1s different kinds
of radiation are produced, and how the emission properties are connected to
other intrinsic AGN properties. In addition we present the early results of our
ongoing research about the large-scale environments of NLS1s. We also introduce
the Mets\"ahovi Radio Observatory NLS1 survey and its first results, and show
some early results for individual sources.


title: Symbolic Reachability Analysis of B through ProB and LTSmin

abstract:
  We present a symbolic reachability analysis approach for B that can provide a
significant speedup over traditional explicit state model checking. The
symbolic analysis is implemented by linking ProB to LTSmin, a high-performance
language independent model checker. The link is achieved via LTSmin's PINS
interface, allowing ProB to benefit from LTSmin's analysis algorithms, while
only writing a few hundred lines of glue-code, along with a bridge between ProB
and C using ZeroMQ. ProB supports model checking of several formal
specification languages such as B, Event-B, Z and TLA. Our experiments are
based on a wide variety of B-Method and Event-B models to demonstrate the
efficiency of the new link. Among the tested categories are state space
generation and deadlock detection; but action detection and invariant checking
are also feasible in principle. In many cases we observe speedups of several
orders of magnitude. We also compare the results with other approaches for
improving model checking, such as partial order reduction or symmetry
reduction. We thus provide a new scalable, symbolic analysis algorithm for the
B-Method and Event-B, along with a platform to integrate other model checking
improvements via LTSmin in the future.


title:
Controlling Search in Very large Commonsense Knowledge Bases: A Machine
  Learning Approach

abstract:
  Very large commonsense knowledge bases (KBs) often have thousands to millions
of axioms, of which relatively few are relevant for answering any given query.
A large number of irrelevant axioms can easily overwhelm resolution-based
theorem provers. Therefore, methods that help the reasoner identify useful
inference paths form an essential part of large-scale reasoning systems. In
this paper, we describe two ordering heuristics for optimization of reasoning
in such systems. First, we discuss how decision trees can be used to select
inference steps that are more likely to succeed. Second, we identify a small
set of problem instance features that suffice to guide searches away from
intractable regions of the search space. We show the efficacy of these
techniques via experiments on thousands of queries from the Cyc KB. Results
show that these methods lead to an order of magnitude reduction in inference
time.


title:
New orbital ephemerides for the dipping source 4U 1323-619: constraining
  the distance to the source

abstract:
  4U 1323-619 is a low mass X-ray binary system that shows type I X-ray bursts
and dips. The most accurate estimation of the orbital period is 2.941923(36)
hrs and a distance from the source that is lower than 11 kpc has been proposed.
We aim to obtain the orbital ephemeris, the orbital period of the system, as
well as its derivative to compare the observed luminosity with that predicted
by the theory of secular evolution. We took the advantage of about 26 years of
X-ray data and grouped the selected observations when close in time. We folded
the light curves and used the timing technique, obtaining 12 dip arrival times.
We fit the delays of the dip arrival times both with a linear and a quadratic
function. We locate 4U 1323-619 within a circular area centred at RA (J2000)=
201.6543\degree and DEC (J2000)= -62.1358\degree with an associated error of
0.0002\degree, and confirm the detection of the IR counterpart already
discussed in literature. We estimate an orbital period of P=2.9419156(6) hrs
compatible with the estimations that are present in the literature, but with an
accuracy ten times higher. We also obtain a constraint on the orbital period
derivative for the first time, estimating $\dot{P}=(8\pm 13)\times 10^{-12}$
s/s. Assuming that the companion star is in thermal equilibrium in the lower
main sequence, and is a neutron star of 1.4 M$_{\odot}$, we infer a mass of
0.28$\pm$0.03 M$_{\odot}$ for the companion star. Assuming a distance of 10
kpc, we obtained a luminosity of (4.3$\pm$0.5)$\times 10^{36}$ erg s$^{-1}$,
which is not in agreement with what is predicted by the theory of secular
evolution. Using a 3D extinction map of the K$_{s}$ radiation in our Galaxy, we
obtain a distance of 4.2$^{+0.8}_{-0.7}$ kpc at 68\% confidence level.
(Abridged)


title:
Investigation of Prediction Accuracy, Sensitivity, and Parameter
  Stability of Large-Scale Propagation Path Loss Models for 5G Wireless
  Communications

abstract:
  This paper compares three candidate large-scale propagation path loss models
for use over the entire microwave and millimeter-wave (mmWave) radio spectrum:
the alpha-beta-gamma (ABG) model, the close-in (CI) free space reference
distance model, and the CI model with a frequency-weighted path loss exponent
(CIF). Each of these models have been recently studied for use in standards
bodies such as 3GPP, and for use in the design of fifth generation (5G)
wireless systems in urban macrocell, urban microcell, and indoor office and
shopping mall scenarios. Here we compare the accuracy and sensitivity of these
models using measured data from 30 propagation measurement datasets from 2 GHz
to 73 GHz over distances ranging from 4 m to 1238 m. A series of sensitivity
analyses of the three models show that the physically-based two-parameter CI
model and three-parameter CIF model offer computational simplicity, have very
similar goodness of fit (i.e., the shadow fading standard deviation), exhibit
more stable model parameter behavior across frequencies and distances, and
yield smaller prediction error in sensitivity testing across distances and
frequencies, when compared to the four-parameter ABG model. Results show the CI
model with a 1 m close-in reference distance is suitable for outdoor
environments, while the CIF model is more appropriate for indoor modeling. The
CI and CIF models are easily implemented in existing 3GPP models by making a
very subtle modification -- by replacing a floating non-physically based
constant with a frequency-dependent constant that represents free space path
loss in the first meter of propagation.


title: Fast Large Scale Structure Perturbation Theory using 1D FFTs

abstract:
  The usual fluid equations describing the large-scale evolution of mass
density in the universe can be written as local in the density, velocity
divergence, and velocity potential fields. As a result, the perturbative
expansion in small density fluctuations, usually written in terms of
convolutions in Fourier space, can be written as a series of products of these
fields evaluated at the same location in configuration space. Based on this, we
establish a new method to numerically evaluate the 1-loop power spectrum (i.e.,
Fourier transform of the 2-point correlation function) with one-dimensional
Fast Fourier Transforms. This is exact and a few orders of magnitude faster
than previously used numerical approaches. Numerical results of the new method
are in excellent agreement with the standard quadrature integration method.
This fast model evaluation can in principle be extended to higher loop order
where existing codes become painfully slow. Our approach follows by writing
higher order corrections to the 2-point correlation function as, e.g., the
correlation between two second-order fields or the correlation between a linear
and a third-order field. These are then decomposed into products of
correlations of linear fields and derivatives of linear fields. The method can
also be viewed as evaluating three-dimensional Fourier space convolutions using
products in configuration space, which may also be useful in other contexts
where similar integrals appear.


title:
Rotational properties of the Haumea family members and candidates:
  Short-term variability

abstract:
  Haumea is one of the most interesting and intriguing transneptunian objects
(TNOs). It is a large, bright, fast rotator, and its spectrum indicates nearly
pure water ice on the surface. It has at least two satellites and a dynamically
related family of more than ten TNOs with very similar proper orbital
parameters and similar surface properties. The Haumean family is the only one
currently known in the transneptunian belt. Various models have been proposed
but the formation of the family remains poorly understood. In this work, we
have investigated the rotational properties of the family members and
unconfirmed family candidates with short-term variability studies, and report
the most complete review to date. We present results based on five years of
observations and report the short-term variability of five family members, and
seven candidates. The mean rotational periods, from Maxwellian fits to the
frequency distributions, are 6.27+/-1.19 h for the confirmed family members,
6.44+/-1.16 h for the candidates, and 7.65+/-0.54 h for other TNOs (without
relation to the family). According to our study, there is a suggestion that
Haumea family members rotate faster than other TNOs, however, the sample of
family member is still too limited for a secure conclusion. We also highlight
the fast rotation of 2002 GH32. This object has a 0.36+/-0.02 mag amplitude
lightcurve and a rotational period of about 3.98 h. Assuming 2002 GH32 is a
triaxial object in hydrostatic equilibrium, we derive a lower limit to the
density of 2.56 g cm^-3. This density is similar to Haumea's and much more
dense than other small TNO densities.


title:
Optical properties of potential-inserted quantum wells in the near
  infrared and Terahertz ranges

abstract:
  We propose an engineering of the optical properties of GaAs/AlGaAs quantum
wells using AlAs and InAs monolayer insertions. A quantitative study of the
effects of the monolayer position and the well thickness on the interband and
intersubband transitions, based on the extended-basis sp3d5s* tight-binding
model, is presented. The effect of insertion on the interband transitions is
compared with existing experimental data. As for intersubband transitions, we
show that in a GaAs/AlGaAs quantum well including two AlAs and one InAs
insertions, a three level {e1 , e2 , e3 } system where the transition energy
e3-e2 is lower and the transition energy e2-e1 larger than the longitudinal
optical phonon energy (36 meV) can be engineered together with a e3-e2
transition energy widely tunable through the TeraHertz range.


title: U-CATCH: Using Color ATtribute of image patCHes in binary descriptors

abstract:
  In this study, we propose a simple yet very effective method for extracting
color information through binary feature description framework. Our method
expands the dimension of binary comparisons into RGB and YCbCr spaces, showing
more than 100% matching improve ment compared to non-color binary descriptors
for a wide range of hard-to-match cases. The proposed method is general and can
be applied to any binary descriptor to make it color sensitive. It is faster
than classical binary descriptors for RGB sampling due to the abandonment of
grayscale conversion and has almost identical complexity (insignificant
compared to smoothing operation) for YCbCr sampling.


title:
Quantum thermalization through entanglement in an isolated many-body
  system

abstract:
  The concept of entropy is fundamental to thermalization, yet appears at odds
with basic principles in quantum mechanics. Statistical mechanics relies on the
maximization of entropy for a system at thermal equilibrium. However, an
isolated many-body system initialized in a pure state will remain pure during
Schr\"{o}dinger evolution, and in this sense has static, zero entropy. The
underlying role of quantum mechanics in many-body physics is then seemingly
antithetical to the success of statistical mechanics in a large variety of
systems. Here we experimentally study the emergence of statistical mechanics in
a quantum state, and observe the fundamental role of quantum entanglement in
facilitating this emergence. We perform microscopy on an evolving quantum
system, and we see thermalization occur on a local scale, while we measure that
the full quantum state remains pure. We directly measure entanglement entropy
and observe how it assumes the role of the thermal entropy in thermalization.
Although the full state remains measurably pure, entanglement creates local
entropy that validates the use of statistical physics for local observables. In
combination with number-resolved, single-site imaging, we demonstrate how our
measurements of a pure quantum state agree with the Eigenstate Thermalization
Hypothesis and thermal ensembles in the presence of a near-volume law in the
entanglement entropy.


title: Exponentials and Laplace transforms on nonuniform time scales

abstract:
  We formulate a coherent approach to signals and systems theory on time
scales. The two derivatives from the time-scale calculus are used, i.e., nabla
(forward) and delta (backward), and the corresponding eigenfunctions, the
so-called nabla and delta exponentials, computed. With these exponentials, two
generalised discrete-time Laplace transforms are deduced and their properties
studied. These transforms are compatible with the standard Laplace and $Z$
transforms. They are used to study discrete-time linear systems defined by
difference equations. These equations mimic the usual continuous-time equations
that are uniformly approximated when the sampling interval becomes small.
Impulse response and transfer function notions are introduced. This implies a
unified mathematical framework that allows us to approximate the classic
continuous-time case when the sampling rate is high or to obtain the standard
discrete-time case, based on difference equations, when the time grid becomes
uniform.


title:
Generalized automorphic sheaves and the proportionality principle of
  Hirzebruch-Mumford

abstract:
  We axiomatize the algebraic properties of toroidal compactifications of
(mixed) Shimura varieties and their automorphic vector bundles. A notion of
generalized automorphic sheaf is proposed which includes sheaves of
(meromorphic) sections of automorphic vector bundles with prescribed vanishing
and pole orders along strata in the compactification, and their quotients.
These include, for instance, sheaves of Jacobi forms and weakly holomorphic
modular forms. Using this machinery we give a short and purely algebraic proof
of the proportionality theorem of Hirzebruch and Mumford.


title: The Evasiveness Conjecture and Graphs on 2p Vertices

abstract:
  The Evasiveness conjecture have been proved for properties of graphs on a
prime-power number of vertices and the six vertices case. The ten vertices case
is still unsolved. In this paper we study the size of the automorphism group of
a graph on $2p$ vertices to estimate the Euler characteristic of monotone
non-evasive graph properties and get some conditions such graph properties must
satisfy. We also do this by means of Oliver groups and give some lower bounds
for the dimension of the simplicial complex associated to a nontrivial monotone
non-evasive graph property. We apply our results to graphs on ten vertices to
get conditions on potential counterexamples to the evasiveness conjecture in
the ten vertices case.


title: Possible ground fog detection from SLI imagery of Titan

abstract:
  Titan, with its thick, nitrogen-dominated atmosphere, has been seen from
satellite and terrestrial observations to harbour methane clouds. To
investigate whether atmospheric features such as clouds could also be visible
from the surface of Titan, data taken with the Side Looking Imager (SLI)
on-board the Huygens probe after landing have been analysed to identify any
potential atmospheric features. In total, 82 SLI images were calibrated,
processed and examined for features. The calibrated images show a smooth
vertical radiance gradient across the images, with no other discernible
features. After mean-frame subtraction, six images contained an extended,
horizontal feature that had a radiance value that lay outside the 95%
confidence limit of the predicted radiance when compared to regions higher and
lower in the images. The change in optical depth of these features were found
to be between 0.005 and 0.014. It is considered that these features most likely
originate from the presence of a fog bank close to the horizon that rises and
falls during the period of observation.


title:
Fermi surface evolution of Na-doped PbTe studied through density
  functional theory calculations and Shubnikov-de Haas measurements

abstract:
  We present a combined experimental and theoretical study of the evolution of
the low-temperature Fermi surface of lead telluride, PbTe, when holes are
introduced through sodium substitution on the lead site. Our Shubnikov-de-Haas
measurements for samples with carrier concentrations up to
$9.4\times10^{19}$cm$^{-3}$ (0.62 Na atomic $\%$) show the qualitative features
of the Fermi surface evolution (topology and effective mass) predicted by our
density functional (DFT) calculations within the generalized gradient
approximation (GGA): we obtain perfect ellipsoidal L-pockets at low and
intermediate carrier concentrations, evolution away from ideal ellipsoidicity
for the highest doping studied, and cyclotron effective masses increasing
monotonically with doping level, implying deviations from perfect parabolicity
throughout the whole band. Our measurements show, however, that standard DFT
calculations underestimate the energy difference between the L-point and
$\Sigma$-line valence band maxima, since our data are consistent with
occupation of a single Fermi surface pocket over the entire doping range
studied, whereas the calculations predict an occupation of the $\Sigma$-pockets
at higher doping. Our results for low and intermediate compositions are
consistent with a non-parabolic Kane-model dispersion, in which the L-pockets
are ellipsoids of fixed anisotropy throughout the band, but the effective
masses depend strongly on Fermi energy.


title: Stability Structures of Conjunctive Boolean Networks

abstract:
  A Boolean network is a finite dynamical system, whose variables take values
from a binary set. The value update rule for each variable is a Boolean
function, depending on a selected subset of variables. Boolean networks have
been widely used in modeling gene regulatory networks. We focus in this paper
on a special class of Boolean networks, termed as conjunctive Boolean networks.
A Boolean network is conjunctive if the associated value update rule is
comprised of only AND operations. It is known that any trajectory of a finite
dynamical system will enter a periodic orbit. We characterize in this paper all
periodic orbits of a conjunctive Boolean network whose underlying graph is
strongly connected. In particular, we establish a bijection between the set of
periodic orbits and the set of binary necklaces of a certain length. We further
investigate the stability of a periodic orbit. Specifically, we perturb a state
in the periodic orbit by changing the value of a single entry of the state. The
trajectory, with the perturbed state being the initial condition, will enter
another (possibly the same) periodic orbit in finite time steps. We then
provide a complete characterization of all such transitions from one periodic
orbit to another. In particular, we construct a digraph, with the vertices
being the periodic orbits, and the (directed) edges representing the
transitions among the orbits. We call such a digraph the stability structure of
the conjunctive Boolean network.


title: Criteria of efficiency for conformal prediction

abstract:
  We study optimal conformity measures for various criteria of efficiency of
classification in an idealised setting. This leads to an important class of
criteria of efficiency that we call probabilistic; it turns out that the most
standard criteria of efficiency used in literature on conformal prediction are
not probabilistic unless the problem of classification is binary. We consider
both unconditional and label-conditional conformal prediction.


title: Controlling open quantum systems: Tools, achievements, and limitations

abstract:
  The advent of quantum devices, which exploit the two essential elements of
quantum physics, coherence and entanglement, has sparked renewed interest in
the control of open quantum systems. Successful implementations face the
challenge to preserve the relevant nonclassical features at the level of device
operation. A major obstacle is decoherence which is caused by interaction with
the environment. Optimal control theory is a tool that can be used to identify
control strategies in the presence of decoherence. We review here recent
advances in optimal control methodology that allow for tackling typical tasks
in device operation for open quantum systems and discuss examples of
relaxation-optimized dynamics. Optimal control theory is also a useful tool to
exploit the environment for control. We discuss examples and point out possible
future extensions.


title:
Taxi Dispatch with Real-Time Sensing Data in Metropolitan Areas: A
  Receding Horizon Control Approach

abstract:
  Traditional taxi systems in metropolitan areas often suffer from
inefficiencies due to uncoordinated actions as system capacity and customer
demand change. With the pervasive deployment of networked sensors in modern
vehicles, large amounts of information regarding customer demand and system
status can be collected in real time. This information provides opportunities
to perform various types of control and coordination for large-scale
intelligent transportation systems. In this paper, we present a receding
horizon control (RHC) framework to dispatch taxis, which incorporates highly
spatiotemporally correlated demand/supply models and real-time GPS location and
occupancy information. The objectives include matching spatiotemporal ratio
between demand and supply for service quality with minimum current and
anticipated future taxi idle driving distance. Extensive trace-driven analysis
with a data set containing taxi operational records in San Francisco shows that
our solution reduces the average total idle distance by 52%, and reduces the
supply demand ratio error across the city during one experimental time slot by
45%. Moreover, our RHC framework is compatible with a wide variety of
predictive models and optimization problem formulations. This compatibility
property allows us to solve robust optimization problems with corresponding
demand uncertainty models that provide disruptive event information.


title:
Modeling and Estimation of Discrete-Time Reciprocal Processes via
  Probabilistic Graphical Models

abstract:
  Reciprocal processes are acausal generalizations of Markov processes
introduced by Bernstein in 1932. In the literature, a significant amount of
attention has been focused on developing dynamical models for reciprocal
processes. In this paper, we provide a probabilistic graphical model for
reciprocal processes. This leads to a principled solution of the smoothing
problem via message passing algorithms. For the finite state space case,
convergence analysis is revisited via the Hilbert metric.


title: A Magellanic Origin of the DES Dwarfs

abstract:
  We establish the connection between the Magellanic Clouds (MCs) and the dwarf
galaxy candidates discovered in the Dark Energy Survey (DES) by building a
dynamical model of the MC satellite populations, based on an extensive suite of
tailor-made numerical simulations. Our model takes into account the response of
the Galaxy to the MCs infall, the dynamical friction experienced by the MCs and
the disruption of the MC satellites by their hosts. The simulation suite
samples over the uncertainties in the MC's proper motions, the masses of the MW
and the Clouds themselves and allows for flexibility in the intrinsic volume
density distribution of the MC satellites. As a result, we can accurately
reproduce the DES satellites' observed positions and kinematics. Assuming that
Milky Way (MW) dwarfs follow the distribution of subhaloes in $\Lambda$CDM, we
further demonstrate that, of 14 observed satellites, the MW halo contributes
fewer than 4 (8) of these with 68% (95%) confidence and that 7 (12) DES dwarfs
have probabilities greater than 0.7 (0.5) of belonging to the LMC.
Marginalising over the entire suite, we constrain the total number of the
Magellanic satellites at ~70, the mass of the LMC around $10^{11}M_\odot$ and
show that the Clouds have likely endured only one Galactic pericentric passage
so far. Finally, we give predictions for the line-of-sight velocities and the
proper motions of the satellites discovered in the vicinity of the LMC.


title: On associating Fast Radio Bursts with afterglows

abstract:
  A radio source that faded over six days, with a redshift of $z\approx0.5$
host, has been identified by Keane et al. (2016) as the transient afterglow to
a fast radio burst (FRB 150418). We report follow-up radio and optical
observations of the afterglow candidate and find a source that is consistent
with an active galactic nucleus. If the afterglow candidate is nonetheless a
prototypical FRB afterglow, existing slow-transient surveys limit the fraction
of FRBs that produce afterglows to 0.25 for afterglows with fractional
variation, $m=2|S_1-S_2|/(S_1+S_2)\geq0.7$, and 0.07 for $m\geq1$, at 95%
confidence. In anticipation of a barrage of bursts expected from future FRB
surveys, we provide a simple framework for statistical association of FRBs with
afterglows. Our framework properly accounts for statistical uncertainties, and
ensures consistency with limits set by slow-transient surveys.


title: Computing the Approximate Convex Hull in High Dimensions

abstract:
  In this paper, an effective method with time complexity of
$\mathcal{O}(K^{3/2}N^2\log \frac{K}{\epsilon_0})$ is introduced to find an
approximation of the convex hull for $N$ points in dimension $n$, where $K$ is
close to the number of vertices of the approximation. Since the time complexity
is independent of dimension, this method is highly suitable for the data in
high dimensions. Utilizing a greedy approach, the proposed method attempts to
find the best approximate convex hull for a given number of vertices. The
approximate convex hull can be a helpful substitute for the exact convex hull
for on-line processes and applications that have a favorable trade off between
accuracy and parsimony.