title: Instagram photos reveal predictive markers of depression

abstract:
  Using Instagram data from 166 individuals, we applied machine learning tools
to successfully identify markers of depression. Statistical features were
computationally extracted from 43,950 participant Instagram photos, using color
analysis, metadata components, and algorithmic face detection. Resulting models
outperformed general practitioners' average diagnostic success rate for
depression. These results held even when the analysis was restricted to posts
made before depressed individuals were first diagnosed. Photos posted by
depressed individuals were more likely to be bluer, grayer, and darker. Human
ratings of photo attributes (happy, sad, etc.) were weaker predictors of
depression, and were uncorrelated with computationally-generated features.
These findings suggest new avenues for early screening and detection of mental
illness.


title: The Magnetic Cataclysmic Variable LSQ1725-64

abstract:
  We present new photometry and spectroscopy of the 94m eclipsing binary
LSQ1725-64 that provide insight into the fundamental parameters and
evolutionary state of this system. We confirm that LSQ1725-64 is a magnetic
cataclysmic variable whose white dwarf has a surface-averaged magnetic field
strength of $12.5 \pm 0.5$ MG measured from Zeeman splitting. The spectral type
and colour of the secondary, as well as the eclipse length, are consistent with
other secondaries that have not yet evolved through the period minimum expected
for cataclysmic variables. We observe two different states of mass transfer and
measure the transition between the two to occur over about 45 orbital cycles.
In the low state, we observe photometric variations that we hypothesize to
arise predominantly from two previously heated magnetic poles of the white
dwarf. Our precise eclipse measurements allow us to determine binary parameters
of LSQ1725-64 and we find it contains a high mass ($0.97 \pm 0.03\ M_{\odot}$)
white dwarf if we assume a typical mass-radius relationship for a CO core white
dwarf. We also measure an eclipse of the accretion stream after the white dwarf
eclipse, and use it to estimate an upper limit of the mass transfer rate. This
derived limit is consistent with that expected from angular momentum loss via
gravitational radiation alone.


title:
A Cardy Formula for Three-Point Coefficients: How the Black Hole Got its
  Spots

abstract:
  Modular covariance of torus one-point functions constrains the three point
function coefficients of a two dimensional CFT. This leads to an asymptotic
formula for the average value of light-heavy-heavy three point coefficients,
generalizing Cardy's formula for the high energy density of states. The
derivation uses certain asymptotic properties of one-point conformal blocks on
the torus. Our asymptotic formula matches a dual AdS_3 computation of one point
functions in a black hole background. This is evidence that the BTZ black hole
geometry emerges upon course-graining over a suitable family of heavy
microstates.


title:
Properties of an $\alpha$ particle in a Bohrium $270$ Nucleus under the
  Generalized Symmetric Woods-Saxon Potential

abstract:
  The energy eigenvalues and the wave functions of an $\alpha$ particle in a
Bohrium $270$ nucleus were calculated by solving Schr\"odinger equation for
Generalized Symmetric Woods-Saxon potential. Using the energy spectrum by
excluding and including the quasi-bound eigenvalues, entropy, internal energy,
Helmholtz energy, and specific heat, as functions of reduced temperature were
calculated. Stability and emission characteristics are interpreted in terms of
the wave and thermodynamic functions. The kinetic energy of a decayed $\alpha$
particle was calculated using the quasi-bound states, which is found close to
the experimental value.


title: Charge diffusion and the butterfly effect in striped holographic matter

abstract:
  Recently, it has been proposed that the butterfly velocity - a speed at which
quantum information propagates - may provide a fundamental bound on diffusion
constants in dirty incoherent metals. We analytically compute the charge
diffusion constant and the butterfly velocity in charge-neutral holographic
matter with long wavelength "hydrodynamic" disorder in a single spatial
direction. In this limit, we find that the butterfly velocity does not set a
sharp lower bound for the charge diffusion constant.


title: Deep vs. shallow networks : An approximation theory perspective

abstract:
  The paper briefy reviews several recent results on hierarchical architectures
for learning from examples, that may formally explain the conditions under
which Deep Convolutional Neural Networks perform much better in function
approximation problems than shallow, one-hidden layer architectures. The paper
announces new results for a non-smooth activation function - the ReLU function
- used in present-day neural networks, as well as for the Gaussian networks. We
propose a new definition of relative dimension to encapsulate different notions
of sparsity of a function class that can possibly be exploited by deep networks
but not by shallow ones to drastically reduce the complexity required for
approximation and learning.


title: CP violation in multibody decays of beauty baryons

abstract:
  Beauty baryons are being observed in large numbers in the LHCb detector. The
rich kinematic distributions of their multibody decays are therefore becoming
accessible and provide us with new opportunities to search for CP violation. We
analyse the angular distributions of some three- and four-body decays of
spin-$1/2$ baryons using the Jacob-Wick helicity formalism. The asymmetries
that provide access to small differences of CP-odd phases between decay
amplitudes of identical CP-even phases are notably discussed. The understanding
gained on processes featuring specific resonant intermediate states allows us
to establish which asymmetries are relevant for what purpose. It is for
instance shown that some CP-odd angular asymmetries measured by the LHCb
collaboration in the $\Lambda_b \to \Lambda\,\varphi \to p\,\pi\, K^+ K^-$
decay are expected to vanish identically.


title: Bosonic quadratic Hamiltonians

abstract:
  We discuss self-adjoint operators given formally by expressions quadratic in
bosonic creation and annihilation operators. We give conditions when they can
be defined as self-adjoint operators, possibly after an infinite
renormalization. We also discuss explicit formulas for their infimum.
  Our main motivation comes from Local Quantum Field Theory, which furnishes
interesting examples of bosonic quadratic Hamiltonians that require an infinite
renormalization.


title:
Study of $\boldsymbol{(\alpha,p)}$ and $\boldsymbol{(\alpha,n)}$
  reactions with a Multi-Sampling Ionization Chamber

abstract:
  A large number of $(\alpha,p)$ and $(\alpha,n)$ reactions are known to play a
fundamental role in nuclear astrophysics. This work presents a novel technique
to study these reactions with the active target system MUSIC whose segmented
anode allows the investigation of a large energy range of the excitation
function with a single beam energy. In order to verify the method, we performed
a direct measurements of the previously measured reactions
$^{17}$O$(\alpha,n)^{20}$Ne, $^{23}$Na$(\alpha,p)^{26}$Mg, and
$^{23}$Na$(\alpha,n)^{26}$Al. These reactions were investigated in inverse
kinematics using $^{4}$He gas in the detector to study the excitation function
in the range of about 2 to 6 MeV in the center of mass. We found good agreement
between the cross sections of the $^{17}$O$(\alpha,n)^{20}$Ne reaction measured
in this work and previous measurements. Furthermore we have successfully
performed a simultaneous measurement of the $^{23}$Na$(\alpha,p)^{26}$Mg and
$^{23}$Na$(\alpha,n)^{26}$Al reactions.


title: Reviving Quintessence with an Exponential Potential

abstract:
  We examine a quintessence model with a modified exponential potential given
by $V(\phi) = V_0(1+e^{-\lambda \phi})$. Unlike quintessence with a standard
exponential potential, our model can yield an acceptable accelerated expansion
at late times, while producing a distinct "early dark energy" signature at high
redshift. We determine the evolution of the equation of state parameter,
$w_\phi$, and the density parameter, $\Omega_\phi$, as a function of the scale
factor. The strongest constraints on the model come from cosmic microwave
background observations rather than supernova data. The former give the limit
$\lambda > 13$. This model predicts a value of the effective neutrino number
during Big Bang nucleosynthesis larger than the standard model value. It also
provides a partial solution to the coincidence problem, in that the ratio of
the quintessence energy density is always within a few orders of magnitude of
the background radiation or matter density from the early universe up to the
present, but it does not explain why the accelerated expansion is beginning
near the present day, suggesting that these two different ways of
characterizing the coincidence problem are not entirely equivalent.


title:
Study of the astrophysically important
  $\boldsymbol{^{23}\mathrm{Na}(\alpha,p)^{26}\mathrm{Mg}}$ and
  $\boldsymbol{^{23}\mathrm{Na}(\alpha,n)^{26}\mathrm{Al}}$ reactions

abstract:
  The $^{23}$Na$(\alpha,p)^{26}$Mg and $^{23}$Na$(\alpha,n)^{26}$Al reactions
are important for our understanding of the $^{26}$Al abundance in massive
stars. The aim of this work is to report on a direct and simultaneous
measurement of these astrophysically important reactions using an active target
system. The reactions were investigated in inverse kinematics using $^{4}$He as
the active target gas in the detector. We measured the excitation functions in
the energy range of about 2 to 6 MeV in the center of mass. We have found that
the cross sections of the $^{23}$Na$(\alpha,p)^{26}$Mg and the
$^{23}$Na$(\alpha,n)^{26}$Al reactions are in good agreement with previous
experiments, and with statistical model calculations.


title: The Effect Of AGN Heating On The Low-Redshift Ly{\alpha} Forest

abstract:
  We investigate the effects of AGN heating and the ultraviolet background on
the low-redshift Lyman-$\alpha$ forest column density distribution (CDD) using
the Illustris simulation. We show that Illustris reproduces observations at $z
=0.1$ in the column density range $10^{12.5} - 10^{13.5}$cm$^{-2}$, relevant
for the "photon underproduction crisis." We attribute this to the inclusion of
AGN feedback, which changes the gas distribution so as to mimic the effect of
extra photons, as well as the use of the Faucher-Gigu\`ere ultraviolet
background, which is more ionizing at $z=0.1$ than the Haardt & Madau
background previously considered. We show that the difference between
simulations run with smoothed particle hydrodynamics and simulations using a
moving mesh is small in this column density range but can be more significant
at larger column densities. We further consider the effect of supernova
feedback, Voigt profile fitting and finite resolution, all of which we show to
have little influence on the CDD. Finally, we identify a discrepancy between
our simulations and observations at column densities $10^{14} -
10^{16}$cm$^{-2}$, where Illustris produces too few absorbers, which suggests
the AGN feedback model should be further refined. Since the "photon
underproduction crisis" primarily affects lower column density systems, we
conclude that AGN feedback and standard ionizing background models can resolve
the crisis.


title: Dynamics of atmospheres with a non-dilute condensible component

abstract:
  The diversity of characteristics for the host of recently discovered
exoplanets opens up a great deal of fertile new territory for geophysical fluid
dynamics, particularly when the fluid flow is coupled to novel thermodynamics,
radiative transfer or chemistry. In this paper, we survey one of these new
areas-the climate dynamics of atmospheres with a non-dilute condensible
component, defined as the situation in which a condensible component of the
atmosphere makes up a substantial fraction of the atmospheric mass within some
layer. Non-dilute dynamics can occur for a wide range of condensibles,
generically applying near both the inner and the outer edges of the
conventional habitable zone and in connection with runaway greenhouse
phenomena. It also applies in a wide variety of other planetary circumstances.
We first present a number of analytical results developing some key features of
non-dilute atmospheres, and then show how some of these features are manifest
in simulations with a general circulation model adapted to handle non-dilute
atmospheres. We find that non-dilute atmospheres have weak horizontal
temperature gradients even for rapidly rotating planets, and that their
circulations are largely barotropic. The relative humidity of the condensible
component tends towards 100% as the atmosphere becomes more non-dilute, which
has important implications for runaway greenhouse thresholds. Non-dilute
atmospheres exhibit a number of interesting organized convection features, for
which there is not yet any adequate theoretical understanding.


title: Povrchov\'e f\'azov\'e p\v{r}echody a kritick\'e jevy

abstract:
  Brief introduction to the theory of surface phase transitions at planar
interfaces, such as wetting phenomena (in Czech).


title:
Explicit construction of local conserved operators in disordered
  many-body systems

abstract:
  The presence and character of local integrals of motion -- quasi-local
operators that commute with the Hamiltonian -- encode valuable information
about the dynamics of a quantum system. In particular, strongly disordered
many-body systems can generically avoid thermalisation when there are
extensively many such operators. In this work, we explicitly construct local
conserved operators in $1$D spin chains by directly minimising their commutator
with the Hamiltonian. We demonstrate the existence of an extensively large set
of local integrals of motion in the many-body localised phase of the disordered
XXZ spin chain. These operators are shown to have exponentially decaying tails,
in contrast to the ergodic phase where the decay is (at best) polynomial in the
size of the subsystem. We study the algebraic properties of localised
operators, and confirm that in the many-body localised phase they are
well-described by "dressed" spin operators.

categories: cond-mat.dis-nn cond-mat.stat-mech cond-mat.str-el quant-ph


title: Semigroups --- A Computational Approach

abstract:
  The question whether there exists an integral solution to the system of
linear equations with non-negative constraints, $A\x = \b, \, \x \ge 0$, where
$A \in \Z^{m\times n}$ and ${\mathbf b} \in \Z^m$, finds its applications in
many areas, such as operation research, number theory and statistics. In order
to solve this problem, we have to understand the semigroup generated by the
columns of the matrix $A$ and the structure of the "holes" which are the
difference between the semigroup generated by the columns of the matrix $A$ and
its saturation. In this paper, we discuss the implementation of an algorithm by
Hemmecke, Takemura, and Yoshida that computes the set of holes of a semigroup,
% generated by the columns of $A$ and we discuss applications to problems in
combinatorics. Moreover, we compute the set of holes for the common diagonal
effect model, and we show that the $n$th linear ordering polytope has the
integer-decomposition property for $n\leq 7$. The software is available at
  \url{http://ehrhart.math.fu-berlin.de/People/fkohl/HASE/}.


title: New Method for Building Geodesic Lines in Riemann Geometry

abstract:
  New perspective form of equations for geodesic lines in Riemann Geometry was
found. This method is based on the use of differential forms in differential
equations as arguments of differentiation. At that, these forms do not have a
requirement of completeness, and that extends capabilities of equation
transformation, makes their writing very flexible and extend their scope of
application.


title:
Approximation algorithms for the maximum weight internal spanning tree
  problem

abstract:
  Given a vertex-weighted connected graph $G = (V, E)$, the maximum weight
internal spanning tree (MwIST for short) problem asks for a spanning tree $T$
of $G$ such that the total weight of the internal vertices in $T$ is maximized.
The un-weighted variant, denoted as MIST, is NP-hard and APX-hard, and the
currently best approximation algorithm has a proven performance ratio $13/17$.
The currently best approximation algorithm for MwIST only has a performance
ratio $1/3 - \epsilon$, for any $\epsilon > 0$. In this paper, we present a
simple algorithm based on a novel relationship between MwIST and the maximum
weight matching, and show that it achieves a better approximation ratio of
$1/2$. When restricted to claw-free graphs, a special case been previously
studied, we design a $7/12$-approximation algorithm.


title:
Competing interactions in population-imbalanced two-component
  Bose-Einstein condensates

abstract:
  We consider a two-component Bose-Einstein condensate with and without
synthetic "spin-orbit" interactions in two dimensions. Density- and
phase-fluctuations of the condensate are included, allowing us to study the
impact of thermal fluctuations and density-density interactions on the physics
originating with spin-orbit interactions. In the absence of spin-orbit
interactions, we find that inter-component density interactions deplete the
minority condensate. The thermally driven phase transition is driven by coupled
density and phase-fluctuations, but is nevertheless shown to be a
phase-transition in the Kosterlitz-Thouless universality class with close to
universal amplitude ratios irrespective of whether both the minority- and
majority condensates exist in the ground state, or only one condensate exists.
In the presence of spin-orbit interactions we observe three separate phases,
depending on the strength of the spin-orbit coupling and inter-component
density-density interactions: a phase-modulated phase with uniform amplitudes
for small intercomponent interactions, a completely imbalanced, effectively
single-component, condensate for intermediate spin-orbit coupling strength and
suficciently large inter-component interactions, and a phase-modulated
\textit{and} amplitude-modulated phase for sufficiently large values of both
the spin-orbit coupling and the inter-component density-density interactions.
The phase which is modulated by a single $\bv q$-vector only is observed to
transition into an isoptropic liquid through a strong de-pinning transition
with periodic boundary conditions, which weakens with open boundaries.


title: On the Relation of Schatten Norms and the Thompson Metric

abstract:
  The Thompson metric provides key geometric insights in the study or
non-linear matrix equations and in many optimization problems. However, knowing
that an approximate solution is within d_T units of the actual solution in the
Thompson metric provides little insight into how good the approximation is as a
matrix or vector approximation. That is, bounding the Thompson metric between
an approximate and accurate solution to a problem does not provide obvious
bounds either for the spectral or the Frobenius norm, both Schatten norms, of
the difference between the approximation and accurate solution. This paper
reports an upper bound on the Schatten norm of X - Y related to both the
Thompson metric between X and Y and the maximum of their Schatten norms. This
paper reports a similar but slightly tighter bound for the Frobenius norm of X
- Y.


title:
Exponential Family Mixed Membership Models for Soft~Clustering of
  Multivariate Data

abstract:
  For several years, model-based clustering methods have successfully tackled
many of the challenges presented by data-analysts. However, as the scope of
data analysis has evolved, some problems may be beyond the standard mixture
model framework. One such problem is when observations in a dataset come from
overlapping clusters, whereby different clusters will possess similar
parameters for multiple variables. In this setting, mixed membership models, a
soft clustering approach whereby observations are not restricted to single
cluster membership, have proved to be an effective tool. In this paper, a
method for fitting mixed membership models to data generated by a member of an
exponential family is outlined. The method is applied to count data obtained
from an ultra running competition, and compared with a standard mixture model
approach.


title:
Controlling the Rotational and Hyperfine State of Ultracold
  $^{87}$Rb$^{133}$Cs Molecules

abstract:
  We demonstrate coherent control of both the rotational and hyperfine state of
ultracold, chemically stable $^{87}$Rb$^{133}$Cs molecules with external
microwave fields. We create a sample of ~2000 molecules in the lowest hyperfine
level of the rovibronic ground state N = 0. We measure the transition
frequencies to 8 different hyperfine levels of the N = 1 state at two magnetic
fields ~23 G apart. We determine accurate values of rotational and hyperfine
coupling constants that agree well with previous calculations. We observe Rabi
oscillations on each transition, allowing complete population transfer to a
selected hyperfine level of N = 1. Subsequent application of a second microwave
pulse allows transfer of molecules back to a different hyperfine level of N =
0.


title:
Invariant Subspaces of Riesz Spectral Systems with Application to Fault
  Detection and Isolation

abstract:
  A large class of hyperbolic and parabolic partial differential equation (PDE)
systems, such as reaction-diffusion processes, when expressed in the
infinite-dimensional (Inf-D) framework can be represented as Riesz spectral
(RS) systems. Compared to the finite dimensional (Fin-D) systems, the geometric
theory of Inf-D systems for addressing certain fundamental control problems,
such as disturbance decoupling and fault detection and isolation (FDI), is
rather quite limited due to complexity and existence of various types of
invariant subspaces notions. Interestingly enough, these invariant concepts are
equivalent for Fin-D systems, although they are different in Inf-D
representation. In this work, first equivalence of various types of invariant
subspaces that are defined for RS systems are investigated. This enables one to
define and specify the unobservability subspace for RS systems. Specifically,
necessary and sufficient conditions are derived for equivalence of various
types of conditioned invariant subspaces. Moreover, by using duality
properties, various controlled invariant subspaces are developed. It is then
shown that finite-rankness of the output operator enables one to derive
algorithms for computing invariant subspaces that under certain conditions, and
unlike methods in the literature, converge in a finite number of steps. A
geometric FDI methodology for RS systems is then developed by invoking the
introduced invariant subspaces. Finally, necessary and sufficient conditions
for solvability of the FDI problem are provided and analyzed


title: Dynamically Generated Patterns in Dense Suspensions of Active Filaments

abstract:
  We use Langevin dynamics simulations to study dynamical behaviour of a dense
planar layer of active semi-flexible filaments. Using the strength of active
force and the thermal persistence length as parameters, we map a detailed phase
diagram and identify several non-equilibrium phases in this system. In addition
to a slowly flowing melt phase, we observe that for sufficiently high activity,
collective flow accompanied by signatures of local polar and nematic order
appears in the system. This state is also characterised by strong density
fluctuations. Furthermore, we identify an activity-driven cross-over from this
state of coherently flowing bundles of filaments to a phase with no global
flow, formed by individual filaments coiled into rotating spirals. This
suggests a mechanism where the system responds to activity by changing the
shape of active agents, an effect with no analogue in systems of active
particles without internal degrees of freedom.


title: Auxiliary fermion approach to the RIXS spectrum in a doped cuprate

abstract:
  We describe a method for calculating the resonant inelastic X-ray scattering
(RIXS) response---including the dynamics of the transient core hole---of
many-body systems with non-trivial gap structure encoded in their single
particle Green's function. Our approach introduces auxiliary fermions in order
to obtain a form amenable to the determinant method of Benjamin et al. [PRL 112
247002 (2014)], and is applicable to systems where interactions are most
strongly felt through a renormalization of the single particle propagator. As a
test case we consider the Yang Rice Zhang ansatz describing cuprate phenomena
in the underdoped `pseudogap' regime, and show that including the core hole
dynamics pushes the RIXS peaks towards higher energy transfer, improving
agreement with experiments.


title: Floware: Balanced Flow Monitoring in Software Defined Networks

abstract:
  OpenFlow is a protocol implementing Software Defined Networking, a new
networking paradigm, which segregates packet forwarding and accounting
(performed on switches) from the routing decisions and advanced protocols
(executed on a central controller). This segregation increases agility and
flexibility of a networking infrastructure and reduces its operational
expenses. OpenFlow controllers expose standard interfaces to facilitate variety
of networking applications. In particular, a monitoring application can use
these interfaces to push into the OpenFlow switches rules that collect traffic
flow statistics at different aggregation levels. The aggregation level
determines the monitoring accuracy and the induced network overhead. In this
paper, we propose Floware an OpenFlow application that allows discovery and
monitoring of active flows at any required aggregation level. Floware balances
the monitoring overhead among many switches in order to reduce its negative
effect on network performance. In addition, Floware integrates with monitoring
systems based on legacy protocols such as NetFlow. We demonstrate the
application with soft switches emulated in Mininet, the Floodlight controller,
and the NetFlow Analyzer as a legacy network analysis and intrusion detection
system. Evaluation results demonstrate the positive impact of balanced
monitoring.


title: Approximate search with quantized sparse representations

abstract:
  This paper tackles the task of storing a large collection of vectors, such as
visual descriptors, and of searching in it. To this end, we propose to
approximate database vectors by constrained sparse coding, where possible atom
weights are restricted to belong to a finite subset. This formulation
encompasses, as particular cases, previous state-of-the-art methods such as
product or residual quantization. As opposed to traditional sparse coding
methods, quantized sparse coding includes memory usage as a design constraint,
thereby allowing us to index a large collection such as the BIGANN
billion-sized benchmark. Our experiments, carried out on standard benchmarks,
show that our formulation leads to competitive solutions when considering
different trade-offs between learning/coding time, index size and search
quality.


title:
Experimental and ab initio ultrafast carrier dynamics in plasmonic
  nanoparticles

abstract:
  Ultrafast pump-probe measurements of plasmonic nanostructures probe the
non-equilibrium behavior of excited carriers, which involves several competing
effects obscured in typical empirical analyses. Here we present pump-probe
measurements of plasmonic nanoparticles along with a complete theoretical
description based on first-principles calculations of carrier dynamics and
optical response, free of any fitting parameters. We account for detailed
electronic-structure effects in the density of states, excited carrier
distributions, electron-phonon coupling, and dielectric functions which allow
us to avoid effective electron temperature approximations. Using this
calculation method, we obtain excellent quantitative agreement with spectral
and temporal features in transient-absorption measurements. In both our
experiments and calculations, we identify the two major contributions of the
initial response with distinct signatures: short-lived highly non-thermal
excited carriers and longer-lived thermalizing carriers.


title: Uniform Limit Theorem and tail estimates for parametric u-statistics

abstract:
  We deduce in this paper the sufficient conditions for weak convergence of
centered and normed deviation of the u-statistics with values in the space of
the real valued continuous function defined on some compact metric space.
  We obtain also a non-asymptotic and non-improvable up to multiplicative
constant moment and exponential tail estimates for distribution for the uniform
norm of centered and naturally normed deviation of u-statistics by means of its
martingale representation.
  Our results are formulated in a very popular and natural terms of metric
entropy in the distance (distances) generated by the introduced random
processes (fields).


title: Sharp Weight Hardy-Sobolev inequalities for Grand Lebesgue Spaces

abstract:
  We give in this short paper the exact value for norms of two operators of
Hardy-Sobolev type acting between two weight Grand Lebesgue Space (GLS) based
on the whole multidimensional Euclidean space.


title: Trigonometric approximation in Sobolev-Grand Lebesgue Spaces

abstract:
  We study in this short preprint the theory of trigonometric approximation in
the so-called Banach functional rearrangement invariant Sobolev-Grand Lebesgue
Spaces.


title: Tight Network Topology Dependent Bounds on Rounds of Communication

abstract:
  We prove tight network topology dependent bounds on the round complexity of
computing well studied $k$-party functions such as set disjointness and element
distinctness. Unlike the usual case in the CONGEST model in distributed
computing, we fix the function and then vary the underlying network topology.
This complements the recent such results on total communication that have
received some attention. We also present some applications to distributed graph
computation problems.
  Our main contribution is a proof technique that allows us to reduce the
problem on a general graph topology to a relevant two-party communication
complexity problem. However, unlike many previous works that also used the same
high level strategy, we do not reason about a two-party communication problem
that is induced by a cut in the graph. To `stitch' back the various lower
bounds from the two party communication problems, we use the notion of timed
graph that has seen prior use in network coding. Our reductions use some tools
from Steiner tree packing and multi-commodity flow problems that have a delay
constraint.


title: On symmetric 3-wise intersecting families

abstract:
  A family of sets is said to be symmetric if its automorphism group is
transitive, and $3$-wise intersecting if any three sets in the family have
nonempty intersection. Frankl conjectured in 1981 that if $\mathcal{A}$ is a
symmetric $3$-wise intersecting family of subsets of $\{1,2,\dots,n\}$, then
$|\mathcal{A}| = o(2^n)$. Here, we give a short proof of Frankl's conjecture
using a 'sharp threshold' result of Friedgut and Kalai.


title:
Ranks of the Rational Points of Abelian Varieties over Ramified Fields,
  and Iwasawa Theory for Primes with Non-Ordinary Reduction

abstract:
  Let $A$ be an abelian variety defined over a number field $F$. Suppose its
dual abelian variety $A'$ has good non-ordinary reduction at the primes above
$p$. Let $F_{\infty}/F$ be a $\mathbb Z_p$-extension, and for simplicity,
assume that there is only one prime $\mathfrak p$ of $F_{\infty}$ above $p$,
and $F_{\infty, \mathfrak p}/\mathbb Q_p$ is totally ramified and abelian. (For
example, we can take $F=\mathbb Q(\zeta_{p^N})$ for some $N$, and
$F_{\infty}=\mathbb Q(\zeta_{p^{\infty}})$.) As Perrin-Riou did, we use
Fontaine's theory of group schemes to construct series of points over each
$F_{n, \mathfrak p}$ which satisfy norm relations associated to the Dieudonne
module of $A'$ (in the case of elliptic curves, simply the Euler factor at
$\mathfrak p$), and use these points to construct characteristic power series
$\bf L_{\alpha} \in \mathbb Q_p[[X]]$ analogous to Mazur's characteristic
polynomials in the case of good ordinary reduction. By studying $\bf
L_{\alpha}$, we obtain a weak bound for $\text{rank} E(F_n)$.
  In the second part, we establish a more robust Iwasawa Theory for elliptic
curves, and find a better bound for their ranks under the following conditions:
Take an elliptic curve $E$ over a number field $F$. The conditions for $F$ and
$F_{\infty}$ are the same as above. Also as above, we assume $E$ has
supersingular reduction at $\mathfrak p$. We discover that we can construct
series of local points which satisfy finer norm relations under some conditions
related to the logarithm of $E/F_{\mathfrak p}$. Then, we apply Sprung's and
Perrin-Riou's insights to construct \textit{integral} characteristic
polynomials $\bf L_{alg}^{\sharp}$ and $\bf L_{alg}^{\flat}$. One of the
consequences of this construction is that if $\bf L_{alg}^{\sharp}$ and $\bf
L_{alg}^{\flat}$ are not divisible by a certain power of $p$, then
$E(F_{\infty})$ has a finite rank modulo torsions.


title:
Cluster size convergence of the density matrix embedding theory and its
  dynamical cluster formulation: a study with an auxiliary-field quantum Monte
  Carlo solver

abstract:
  We investigate the cluster size convergence of the energy and observables
using two forms of density matrix embedding theory (DMET): the original cluster
form (CDMET) and a new formulation motivated by the dynamical cluster
approximation (DCA-DMET). Both methods are applied to the half-filled one- and
two-dimensional Hubbard models using a sign-problem free auxiliary-field
quantum Monte Carlo (AFQMC) impurity solver, which allows for the treatment of
large impurity clusters of up to 100 sites. While CDMET is more accurate at
smaller impurity cluster sizes, DCA- DMET exhibits faster asymptotic
convergence towards the thermodynamic limit (TDL). We use our two formulations
to produce new accurate estimates for the energy and local moment of the
two-dimensional Hubbard model for U/t = 2, 4, 6. These results compare
favourably with the best data available in literature, and help resolve earlier
uncertainties in the moment for U/t = 2.


title:
Sharp value for the norm of composition and multiplicative operators
  between two different Grand Lebesgue spaces

abstract:
  We calculate in this paper the norm of composition, multiplicative and
product operator, generated by multiplicative and measurable argument
transformation between two different ordinary Lebesgue-Riesz and Grand Lebesgue
spaces.
  We set ourselves the aim to obtain the exact expression for the norm of the
considered operators by means of building of appropriate examples.


title:
Can Ab Initio Theory Explain the Phenomenon of Parity Inversion in
  ${}^{11}$Be?

abstract:
  The weakly bound exotic ${}^{11}$Be nucleus, famous for its ground-state
parity inversion and distinct n+ ${}^{10}$Be halo structure, is investigated
from first principles using chiral two- and three-nucleon forces. An explicit
treatment of continuum effects is found to be indispensable. We study the
sensitivity of the ${}^{11}$Be spectrum to the details of the three-nucleon
force and demonstrate that only certain chiral interactions are capable of
reproducing the parity inversion. With such interactions, the extremely large
E1 transition between the bound states is reproduced. We compare our
photodisintegration calculations to conflicting experimental data and predict a
distinct dip around the $3/2^-_1$ resonance energy. Finally, we predict
low-lying $3/2^+$ and $9/2^+$ resonances that are not or not sufficiently
measured in experiments.


title: On the Regular Emptiness Problem of Subzero Automata

abstract:
  Subzero automata is a class of tree automata whose acceptance condition can
express probabilistic constraints. Our main result is that the problem of
determining if a subzero automaton accepts some regular tree is decidable.


title: Nominal Cellular Automata

abstract:
  The emerging field of Nominal Computation Theory is concerned with the theory
of Nominal Sets and its applications to Computer Science. We investigate here
the impact of nominal sets on the definition of Cellular Automata and on their
computational capabilities, with a special focus on the emergent behavioural
properties of this new model and their significance in the context of
computation-oriented interpretations of physical phenomena. A preliminary
investigation of the relations between Nominal Cellular Automata and Wolfram's
Elementary Cellular Automata is also carried out.


title: An Erlang Implementation of Multiparty Session Actors

abstract:
  By requiring co-ordination to take place using explicit message passing
instead of relying on shared memory, actor-based programming languages have
been shown to be effective tools for building reliable and fault-tolerant
distributed systems. Although naturally communication-centric, communication
patterns in actor-based applications remain informally specified, meaning that
errors in communication are detected late, if at all.
  Multiparty session types are a formalism to describe, at a global level, the
interactions between multiple communicating entities. This article describes
the implementation of a prototype framework for monitoring Erlang/OTP
gen_server applications against multiparty session types, showing how previous
work on multiparty session actors can be adapted to a purely actor-based
language, and how monitor violations and termination of session participants
can be reported in line with the Erlang mantra of "let it fail". Finally, the
framework is used to implement two case studies: an adaptation of a
freely-available DNS server, and a chat server.


title: Multi-Threaded Actors

abstract:
  In this paper we introduce a new programming model of multi-threaded actors
which feature the parallel processing of their messages. In this model an actor
consists of a group of active objects which share a message queue. We provide a
formal operational semantics, and a description of a Java-based implementation
for the basic programming abstractions describing multi-threaded actors.
Finally, we evaluate our proposal by means of an example application.


title: An Abstract Semantics of the Global View of Choreographies

abstract:
  We introduce an abstract semantics of the global view of choreographies. Our
semantics is given in terms of pre-orders and can accommodate different lower
level semantics. We discuss the adequacy of our model by considering its
relation with communicating machines, that we use to formalise the local view.
Interestingly, our framework seems to be more expressive than others where
semantics of global views have been considered. This will be illustrated by
discussing some interesting examples.


title:
Architecture Diagrams: A Graphical Language for Architecture Style
  Specification

abstract:
  Architecture styles characterise families of architectures sharing common
characteristics. We have recently proposed configuration logics for
architecture style specification. In this paper, we study a graphical notation
to enhance readability and easiness of expression. We study simple architecture
diagrams and a more expressive extension, interval architecture diagrams. For
each type of diagrams, we present its semantics, a set of necessary and
sufficient consistency conditions and a method that allows to characterise
compositionally the specified architectures. We provide several examples
illustrating the application of the results. We also present a polynomial-time
algorithm for checking that a given architecture conforms to the architecture
style specified by a diagram.


title:
A Modular Formalization of Reversibility for Concurrent Models and
  Languages

abstract:
  Causal-consistent reversibility is the reference notion of reversibility for
concurrency. We introduce a modular framework for defining causal-consistent
reversible extensions of concurrent models and languages. We show how our
framework can be used to define reversible extensions of formalisms as
different as CCS and concurrent X-machines. The generality of the approach
allows for the reuse of theories and techniques in different settings.


title: Worlds of Events: Deduction with Partial Knowledge about Causality

abstract:
  Interactions between internet users are mediated by their devices and the
common support infrastructure in data centres. Keeping track of causality
amongst actions that take place in this distributed system is key to provide a
seamless interaction where effects follow causes. Tracking causality in large
scale interactions is difficult due to the cost of keeping large quantities of
metadata; even more challenging when dealing with resource-limited devices. In
this paper, we focus on keeping partial knowledge on causality and address
deduction from that knowledge.
  We provide the first proof-theoretic causality modelling for distributed
partial knowledge. We prove computability and consistency results. We also
prove that the partial knowledge gives rise to a weaker model than classical
causality. We provide rules for offline deduction about causality and refute
some related folklore. We define two notions of forward and backward
bisimilarity between devices, using which we prove two important results.
Namely, no matter the order of addition/removal, two devices deduce similarly
about causality so long as: (1) the same causal information is fed to both. (2)
they start bisimilar and erase the same causal information. Thanks to our
establishment of forward and backward bisimilarity, respectively, proofs of the
latter two results work by simple induction on length.


title: A Step Towards Checking Security in IoT

abstract:
  The Internet of Things (IoT) is smartifying our everyday life. Our starting
point is IoT-LySa, a calculus for describing IoT systems, and its static
analysis, which will be presented at Coordination 2016. We extend the mentioned
proposal in order to begin an investigation about security issues, in
particular for the static verification of secrecy and some other security
properties.


title: Galois groups of iterates of some unicritical polynomials

abstract:
  We prove that the arboreal Galois representations attached to certain
unicritical polynomials have finite index in an infinite wreath product of
cyclic groups, and we prove surjectivity for some small degree examples,
including a new family of quadratic polynomials. To do this, we use a
combination of local techniques including the Chabauty-Coleman method and the
Mordell-Weil sieve.


title: Dihedral branched covers of four-manifolds

abstract:
  Given a closed oriented PL four-manifold $X$ and a closed surface $B$
embedded in $X$ with isolated cone singularities, we give a formula for the
signature of an irregular dihedral cover of $X$ branched along $B$. For $X$
simply-connected, we deduce a necessary condition on the intersection form of a
simply-connected irregular dihedral branched cover of $(X, B)$. When the
singularities on $B$ are two-bridge slice, we prove that the necessary
condition on the intersection form of the cover is sharp. For $X$ a
simply-connected PL four-manifold with non-zero second Betti number, we
construct infinite families of simply-connected PL manifolds which are
irregular dihedral branched coverings of $X$. Given two four-manifolds $X$ and
$Y$ whose intersection forms are odd, we obtain a necessary and sufficient
condition for $Y$ to be homeomorphic to an irregular dihedral $p$-fold cover of
$X$, branched over a surface with a two-bridge slice singularity.


title:
A weak form of beyond endoscopic decomposition for the stable trace
  formula of odd orthogonal groups

abstract:
  We show that the cuspidal component of the stable trace formula of a special
odd orthogonal group over a number field, satisfies a weak form of beyond
endoscopic decomposition. We also study the $r$-stable trace formula, when $r$
is the standard or the second fundamental representation of the dual group. The
results are consequences of Arthur's works on endoscopic classification of
automorphic representations, together with known results concerning a class of
Langlands $L$-functions for special odd orthogonal groups.


title: Comultiplication for shifted Yangians and quantum open Toda lattice

abstract:
  We study a coproduct in type A quantum open Toda lattice in terms of a
coproduct in the shifted Yangian of sl_2. At the classical level this
corresponds to the multiplication of scattering matrices of euclidean SU(2)
monopoles. We also study coproducts for shifted Yangians for any simply-laced
Lie algebra.


title:
Modeling the Effect of Dissolved Hydrogen Sulfide on Mg2+-water Complex
  on Dolomite {104} Surfaces

abstract:
  The key kinetic barrier to dolomite formation is related to the surface
Mg2+-H2O complex, which hinders binding of surface Mg2+ ions to the CO3 2- ions
in solution. It has been proposed that this reaction can be catalyzed by
dissolved hydrogen sulfide. To characterize the role of dissolved hydrogen
sulfide in the dehydration of surface Mg 2+ ions, ab initio simulations based
on density functional theory (DFT) were carried out to study the thermodynamics
of competitive adsorption of hydrogen sulfide and water on dolomite (104)
surfaces from solution. We find that water is thermodynamically more stable on
the surface with the difference in adsorption energy of -13.6 kJ/mol (in
vacuum) and -12.8 kJ/mol (in aqueous solution). However, aqueous hydrogen
sulfide adsorbed on the surface increases the Mg2+-H2O distances on surrounding
surface sites. Two possible mechanisms were proposed for the catalytic effects
of adsorbed hydrogen sulfide on the anhydrous Ca-Mg-carbonate crystallization
at low temperature.


title: Temporal Learning and Sequence Modeling for a Job Recommender System

abstract:
  We present our solution to the job recommendation task for RecSys Challenge
2016. The main contribution of our work is to combine temporal learning with
sequence modeling to capture complex user-item activity patterns to improve job
recommendations. First, we propose a time-based ranking model applied to
historical observations and a hybrid matrix factorization over time re-weighted
interactions. Second, we exploit sequence properties in user-items activities
and develop a RNN-based recommendation model. Our solution achieved 5$^{th}$
place in the challenge among more than 100 participants. Notably, the strong
performance of our RNN approach shows a promising new direction in employing
sequence modeling for recommendation systems.


title:
Non-perturbative Solution to the Quantum Interaction Problem via
  Schwinger's Action Principle

abstract:
  The most realistic situations in quantum mechanics involve the interaction
between two or more systems. In the most of reliable models, the form and
structure of the interactions generate differential equations which are, in the
most of cases, almost impossible to solve exactly. In this paper, using the
Schwinger Quantum Action Principle, we found the time transformation function
that solves exactly the harmonic oscillator interacting with a set of other
harmonic coupled oscillators. In order to do it, we have introduced a new
special set of creation and annihilation operators which leads directly to the
\emph{dressed states} associated to the system, which are the real quantum
states of the interacting \emph{\textquotedblleft
field-particle\textquotedblright} system. To obtain the closed solution, it is
introduced in the same foot a set of \emph{normal mode} creation and
annihilation operators of the system related to the first ones by an orthogonal
transformation. We find the eigenstates, amplitude transitions and the system
spectra without any approximation. At last, we show that the Schwinger
Variational Principle provides the solutions in a free representation way.

categories: quant-ph cond-mat.other hep-th math-ph math.MP physics.atom-ph


title: On near optimal control of systems with slow observables

abstract:
  The paper deals with a problem of control of a system characterized by the
fact that the influence of controls on the dynamics of certain functions of
state variables (called observables) is relatively weak and the rates of change
of these observables are much slower than the rates of change of the state
variables themselves. The contributions of the paper are twofold. Firstly, the
averaged system whose solutions approximate the trajectories of the slow
observables is introduced, and it is shown that the optimal value of the
problem of optimal control with time discounting criterion considered on the
solutions of the system with slow observables (this problem is referred to as
perturbed) converges to the optimal value of the corresponding problem of
optimal control of the averaged system. Secondly, a way how an asymptotically
optimal control of the perturbed problem can be constructed on the basis of an
optimal solution of the averaged problem is indicated, sufficient and necessary
optimality conditions for the averaged problem are stated, and a way how a near
optimal solution of the latter can be constructed numerically is outlined (the
construction being illustrated with an example).


title: An Algebraic Characterization of the Point-Pushing Subgroup

abstract:
  The point-pushing subgroup P(S) of the mapping class group Mod(S) of a
surface with marked point is an embedding of \pi_1(S) given by pushing the
marked point around loops. We prove that for g>=3, the subgroup P(S) is the
unique normal, genus g surface subgroup of Mod(S). As a corollary to this
uniqueness result, we give a new proof that Out(Mod^{\pm}(S))=1, where Out
denotes the outer automorphism group; a proof which does not use automorphisms
of complexes of curves. Ingredients in our proof of this characterization
theorem include combinatorial group theory, representation theory, the Johnson
theory of the Torelli group, surface topology, and the theory of Lie algebras.


title: Transitivity reinforcement in the coevolving voter model

abstract:
  One of the fundamental structural properties of many networks is triangle
closure. Whereas the influence of this transitivity on a variety of contagion
dynamics has been previously explored, existing models of coevolving or
adaptive network systems use rewiring rules that randomize away this important
property. In contrast, we study here a modified coevolving voter model dynamics
that explicitly reinforces and maintains such clustering. Employing extensive
numerical simulations, we establish that the transitions and dynamical states
observed in coevolving voter model networks without clustering are altered by
reinforcing transitivity in the model. We then use a semi-analytical framework
in terms of approximate master equations to predict the dynamical behaviors of
the model for a variety of parameter settings.


title: Galactoseismology and the Local Density of Dark Matter

abstract:
  We model vertical breathing mode perturbations in the Milky Way's stellar
disc and study their effects on estimates of the local dark matter density,
surface density, and vertical force. Evidence for these perturbations, which
involve compression and expansion of the Galactic disc perpendicular to its
midplane, come from the SEGUE, RAVE, and LAMOST surveys. We show that their
existence may lead to systematic errors of $10\%$ or greater in the vertical
force $K_z(z)$ at $|z|=1.1\,{\rm kpc}$. These errors translate to $\gtrsim
25\%$ errors in estimates of the local dark matter density. Using different
mono-abundant subpopulations as tracers offers a way out: if the inferences
from all tracers in the Gaia era agree, then the dark matter determination will
be robust. Disagreement in the inferences from different tracers will signal
the breakdown of the unperturbed model and perhaps provide the means for
determining the nature of the perturbation.


title: Distributed learning with regularized least squares

abstract:
  We study distributed learning with the least squares regularization scheme in
a reproducing kernel Hilbert space (RKHS). By a divide-and-conquer approach,
the algorithm partitions a data set into disjoint data subsets, applies the
least squares regularization scheme to each data subset to produce an output
function, and then takes an average of the individual output functions as a
final global estimator or predictor. We show with error bounds in expectation
in both the $L^2$-metric and RKHS-metric that the global output function of
this distributed learning is a good approximation to the algorithm processing
the whole data in one single machine. Our error bounds are sharp and stated in
a general setting without any eigenfunction assumption. The analysis is
achieved by a novel second order decomposition of operator differences in our
integral operator approach. Even for the classical least squares regularization
scheme in the RKHS associated with a general kernel, we give the best learning
rate in the literature.


title:
Superresolving Imaging of Irregular Arrays of Thermal Light Sources
  using Multiphoton Interferences

abstract:
  We propose to use multiphoton interferences of photons emitted from
statistically independent thermal light sources in combination with linear
optical detection techniques to reconstruct, i.e., image, arbitrary source
geometries in one dimension with subclassical resolution. The scheme is an
extension of earlier work [Phys. Rev. Lett. 109, 233603 (2012)] where N
regularly spaced sources in one dimension were imaged by use of the Nth-order
intensity correlation function. Here, we generalize the scheme to reconstruct
any number of independent thermal light sources at arbitrary separations in one
dimension exploiting intensity correlation functions of order $m \geq 3$. We
present experimental results confirming the imaging protocol and provide a
rigorous mathematical proof for the obtained subclassical resolution.


title: Improved treatment of blocking effect at finite temperature

abstract:
  The blocking effect caused by the odd particle on the pairing properties of
systems with odd number of fermions at finite temperature interacting via the
monopole pairing force is studied within several approximations. The results
are compared with the predictions obtained by using the exact solutions of the
pairing Hamiltonian. The comparison favors the approximation with the odd
particle occupying the top level, which is the closest to the Fermi surface and
whose occupation number decreases with increasing temperature.


title: On q-integrals over order polytopes

abstract:
  A combinatorial study of multiple $q$-integrals is developed. This includes a
$q$-volume of a convex polytope, which depends upon the order of
$q$-integration. A multiple $q$-integral over an order polytope of a poset is
interpreted as a generating function of linear extensions of the poset.
Specific modifications of posets are shown to give predictable changes in
$q$-integrals over their respective order polytopes. This method is used to
combinatorially evaluate some generalized $q$-beta integrals. One such
application is a combinatorial interpretation of a $q$-Selberg integral. New
generating functions for generalized Gelfand-Tsetlin patterns and reverse plane
partitions are established. A $q$-analogue to a well known result in Ehrhart
theory is generalized using $q$-volumes and $q$-Ehrhart polynomials.


title: An Accurate Gaussian Process-Based Early Warning System for Dengue Fever

abstract:
  Dengue fever is a mosquito-borne disease present in all Brazilian territory.
Brazilian government, however, lacks an accurate early warning system to
quickly predict future dengue outbreaks. Such system would help health
authorities to plan their actions and to reduce the impact of the disease in
the country. However, most attempts to model dengue fever use parametric models
which enforce a specific expected behaviour and fail to capture the inherent
complexity of dengue dynamics. Therefore, we propose a new Bayesian
non-parametric model based on Gaussian processes to design an accurate and
flexible model that outperforms previous/standard techniques and can be
incorporated into an early warning system, specially at cities from Southeast
and Center-West regions. The model also helps understanding dengue dynamics in
Brazil through the analysis of the covariance functions generated.


title: Multi-source Hierarchical Prediction Consolidation

abstract:
  In big data applications such as healthcare data mining, due to privacy
concerns, it is necessary to collect predictions from multiple information
sources for the same instance, with raw features being discarded or withheld
when aggregating multiple predictions. Besides, crowd-sourced labels need to be
aggregated to estimate the ground truth of the data. Because of the imperfect
predictive models or human crowdsourcing workers, noisy and conflicting
information is ubiquitous and inevitable. Although state-of-the-art aggregation
methods have been proposed to handle label spaces with flat structures, as the
label space is becoming more and more complicated, aggregation under a label
hierarchical structure becomes necessary but has been largely ignored. These
label hierarchies can be quite informative as they are usually created by
domain experts to make sense of highly complex label correlations for many
real-world cases like protein functionality interactions or disease
relationships.
  We propose a novel multi-source hierarchical prediction consolidation method
to effectively exploits the complicated hierarchical label structures to
resolve the noisy and conflicting information that inherently originates from
multiple imperfect sources. We formulate the problem as an optimization problem
with a closed-form solution. The proposed method captures the smoothness
overall information sources as well as penalizing any consolidation result that
violates the constraints derived from the label hierarchy. The hierarchical
instance similarity, as well as the consolidation result, are inferred in a
totally unsupervised, iterative fashion. Experimental results on both synthetic
and real-world datasets show the effectiveness of the proposed method over
existing alternatives.


title: Femtosecond soliton diode on heterojunction Bragg-grating structure

abstract:
  We numerically propose a scheme for realizing an all-optical femtosecond
soliton diode based on a tailored heterojunction Bragg grating, which is
designed by two spatially asymmetric chirped cholesteric liquid crystals. Our
simulations demonstrate that with the consideration of optical nonlinearity,
not only the femtosecond diode effect with nonreciprocal transmission ratio up
to 120 can be achieved, but also the optical pulse evolving into soliton which
maintains its shape during propagation through the sample is observed. Further,
the influence of pulse width and the carrier wavelength to the femtosecond
diode effect is also discussed in detail. Our demonstrations might suggest a
new direction for experimentally realizing the femtosecond soliton diode based
on the cholesteric liquid crystals.


title:
The complex circumnuclear environment of the broad-line radio galaxy 3C
  390.3 revealed by Chandra HETG

abstract:
  We present the first high spectral resolution X-ray observation of the
broad-line radio galaxy 3C 390.3 obtained with the high energy transmission
grating (HETG) spectrometer on board the Chandra X-ray Observatory. The
spectrum shows complex emission and absorption features in both the soft X-rays
and Fe K band. We detect emission and absorption lines in the energy range
between E = 700-1000 eV associated with ionized Fe L transitions (Fe XVII-XX).
An emission line at the energy of E=6.4 keV consistent with the Fe K\alpha is
also observed. Our best-fit model requires at least three different components:
(i) a hot emission component likely associated with the hot interstellar medium
in this elliptical galaxy with temperature kT=0.5+/-0.1 keV; (ii) a warm
absorber with ionization parameter log\xi=2.3+/-0.5 erg s^{-1} cm, column
density logN_H=20.7+/-0.1 cm^{-2}, and outflow velocity of v_{out}<150 km
s^{-1}; (iii) a lowly ionized reflection component in the Fe K band likely
associated with the optical broad line region or the outer accretion disk.
These evidences suggest the possibility that we are looking directly down the
ionization cone of this active galaxy and that the central X-ray source only
photoionizes along the unobscured cone. This is overall consistent with the
angle-dependent unified picture of active galactic nuclei.


title:
Static Structural Signatures of Nearly Jammed Disordered and Ordered
  Hard-Sphere Packings: Direct Correlation Function

abstract:
  Dynamical signatures are known to precede jamming in hard-particle systems,
but static structural signatures have proven more elusive. The observation that
compressing hard-particle packings towards jamming causes growing
hyperuniformity has paved the way for the analysis of jamming as an "inverted
critical point" in which the direct correlation function $c(r)$ diverges. We
establish quantitative relationships between various singularities in $c(r)$
and the total correlation function $h(r)$ that provide a concrete means of
identifying features that must be expressed in $c(r)$ if one hopes to reproduce
details in the pair correlation function accurately. We also analyze systems of
three-dimensional monodisperse hard-spheres of diameter $D$ as they approach
ordered and disordered jammed configurations. For the latter, we use the
Lubachevsky-Stillinger (LS) and Torquato-Jiao (TJ) packing algorithms, which
both generate disordered packings, but can show perceptible structural
differences. We identify a short-ranged scaling $c(r) \propto -1/r$ as $r
\rightarrow 0$ and show that this, along with the developing delta function at
$c(D)$, is a consequence of the growing long-rangedness in $c(r)$. Near the
freezing density, we identify qualitative differences in the structure factor
$S(k)$ as well as $c(r)$ between TJ- and LS-generated configurations and link
them to differences in the protocols' packing dynamics. Configurations from
both algorithms have structure factors that approach zero in the low-wavenumber
limit as jamming is approached and are shown to exhibit a corresponding
power-law decay in $c(r)$ for large $r$ as a consequence. Our work advances the
notion that static signatures are exhibited by hard-particle packings as they
approach jamming and underscores the utility of the direct correlation function
as a means of monitoring for an incipient rigid network.


title:
Parametrization of the nucleus-nucleus gamma-ray production cross
  sections below 100 GeV/nucleon: Subthreshold pions and Hard photons

abstract:
  "Subthreshold pions" and so-called "hard photons" are two important channels
for producing less than 1 GeV $\gamma$-rays and $e^\pm$ pairs from nuclear
collisions with energy per nucleon below the $\pi$-meson production threshold.
I use publicly available experimental data to parametrize these two channels'
$\gamma$-ray and $e^\pm$ production cross sections and extend the pion
contribution to these particles spectra at higher energies using their
corresponding spectra from $pp$ interactions. These parametrizations are valid
for collision energy $T_p\leq 100$ A GeV and agree reasonably well with the
available experimental data. The new parametrizations allow, for the first
time, accurate studies of astrophysical $\gamma$-rays below 1 GeV.


title:
Codimension-two Bifurcations Induce Hysteresis Behavior and
  Multistabilities in Delay-coupled Kuramoto Oscillators

abstract:
  Hysteresis phenomena and multistability play crucial roles in the dynamics of
coupled oscillators, which are now interpreted from the point of view of
codimension-two bifurcations. On the Ott-Antonsen's manifold, complete
bifurcation sets of delay-coupled Kuramoto model are derived regarding coupling
strength and delay as bifurcation parameters. It is rigorously proved that the
system must undergo Bautin bifurcations for some critical values, thus there
always exists saddle-node bifurcation of periodic solutions inducing hysteresis
loop. With the aid of center manifold reduction method and the Matlab Package
DDE-Biftool, the location of Bautin and double Hopf points and detailed
dynamics are theoretically determined. We find that, near these critical
points, at most four coherent states (two of which are stable) and a stable
incoherent state may coexist, and that the system undergoes Neimark-Sacker
bifurcation of periodic solutions. Finally, the clear scenarios about the
synchronous transition in delayed Kuramoto model are depicted.


title:
Close Encounters of the Higher Kind Emulating Constructor Classes in
  Standard ML

abstract:
  We implement a library for encoding constructor classes in Standard ML,
including elaboration from minimal definitions, and automatic instantiation of
superclasses.


title: Uplink-Downlink Duality for Integer-Forcing

abstract:
  Consider a Gaussian multiple-input multiple-output (MIMO) multiple-access
channel (MAC) with channel matrix $\mathbf{H}$ and a Gaussian MIMO broadcast
channel (BC) with channel matrix $\mathbf{H}^{\mathsf{T}}$. For the MIMO MAC,
the integer-forcing architecture consists of first decoding integer-linear
combinations of the transmitted codewords, which are then solved for the
original messages. For the MIMO BC, the integer-forcing architecture consists
of pre-inverting the integer-linear combinations at the transmitter so that
each receiver can obtain its desired codeword by decoding an integer-linear
combination. In both cases, integer-forcing offers higher achievable rates than
zero-forcing while maintaining a similar implementation complexity. This paper
establishes an uplink-downlink duality relationship for integer-forcing, i.e.,
any sum rate that is achievable via integer-forcing on the MIMO MAC can be
achieved via integer-forcing on the MIMO BC with the same sum power and vice
versa. Using this duality relationship, it is shown that integer-forcing can
operate within a constant gap of the MIMO BC sum capacity. Finally, the paper
proposes a duality-based iterative algorithm for the non-convex problem of
selecting optimal beamforming and equalization vectors, and establishes that it
converges to a local optimum.


title: Some Contributions to Sequential Monte Carlo Methods for Option Pricing

abstract:
  Pricing options is an important problem in financial engineering. In many
scenarios of practical interest, financial option prices associated to an
underlying asset reduces to computing an expectation w.r.t.~a diffusion
process. In general, these expectations cannot be calculated analytically, and
one way to approximate these quantities is via the Monte Carlo method; Monte
Carlo methods have been used to price options since at least the 1970's. It has
been seen in Del Moral, P. \& Shevchenko, P.V. (2014) `Valuation of barrier
options using Sequential Monte Carlo' and Jasra, A. \& Del Moral, P. (2011)
`Sequential Monte Carlo for option pricing' that Sequential Monte Carlo (SMC)
methods are a natural tool to apply in this context and can vastly improve over
standard Monte Carlo. In this article, in a similar spirit to Del Moral, P. \&
Shevchenko, P.V. (2014) `Valuation of barrier options using sequential Monte
Carlo' and Jasra, A. \& Del Moral, P. (2011) `Sequential Monte Carlo for option
pricing' we show that one can achieve significant gains by using SMC methods by
constructing a sequence of artificial target densities over time. In
particular, we approximate the optimal importance sampling distribution in the
SMC algorithm by using a sequence of weighting functions. This is demonstrated
on two examples, barrier options and target accrual redemption notes (TARN's).
We also provide a proof of unbiasedness of our SMC estimate.


title: Finite groups whose $n$-maximal subgroups are $\sigma$-subnormal

abstract:
  Let $\sigma =\{\sigma_{i} | i\in I\}$ be some partition of the set of all
primes $\Bbb{P}$. A set ${\cal H}$ of subgroups of $G$ is said to be a
\emph{complete Hall $\sigma $-set} of $G$ if every member $\ne 1$ of ${\cal H}$
is a Hall $\sigma_{i}$-subgroup of $G$, for some $i\in I$, and $\cal H$
contains exact one Hall $\sigma_{i}$-subgroup of $G$ for every $\sigma_{i}\in
\sigma (G)$. A subgroup $H$ of $G$ is said to be: \emph{$\sigma$-permutable} or
\emph{$\sigma$-quasinormal} in $G$ if $G$ possesses a complete Hall
$\sigma$-set set ${\cal H}$ such that $HA^{x}=A^{x}H$ for all $A\in {\cal H}$
and $x\in G$: \emph{${\sigma}$-subnormal} in $G$ if there is a subgroup chain
$A=A_{0} \leq A_{1} \leq \cdots \leq A_{t}=G$ such that either
$A_{i-1}\trianglelefteq A_{i}$ or $A_{i}/(A_{i-1})_{A_{i}}$ is a finite
$\sigma_{i}$-group for some $\sigma_{i}\in \sigma$ for all $i=1, \ldots t$.
  If each $n$-maximal subgroup of $G$ is $\sigma$-subnormal
($\sigma$-quasinormal, respectively) in $G$ but, in the case $ n > 1$, some
$(n-1)$-maximal subgroup is not $\sigma$-subnormal (not $\sigma$-quasinormal,
respectively)) in $G$, we write $m_{\sigma}(G)=n$ ($m_{\sigma q}(G)=n$,
respectively).
  In this paper, we show that the parameters $m_{\sigma}(G)$ and $m_{\sigma
q}(G)$ make possible to bound the $\sigma$-nilpotent length $ \ l_{\sigma}(G)$
(see below the definitions of the terms employed), the rank $r(G)$ and the
number $|\pi (G)|$ of all distinct primes dividing the order $|G|$ of a finite
soluble group $G$.
  We also give conditions under which a finite group is $\sigma$-soluble or
$\sigma$-nilpotent, and describe the structure of a finite soluble group $G$ in
the case when $m_{\sigma}(G)=|\pi (G)|$. Some known results are generalized.


title: Approximated integrability of the Dicke model

abstract:
  A very approximate second integral of motion of the Dicke model is identified
within a broad region above the ground state, and for a wide range of values of
the external parameters. This second integral, obtained from a Born Oppenheimer
approximation, classifies the whole regular part of the spectrum in bands
labelled by its corresponding eigenvalues. Results obtained from this
approximation are compared with exact numerical diagonalization for finite
systems in the superradiant phase, obtaining a remarkable accord. The region of
validity of our approach in the parameter space, which includes the resonant
case, is unveiled. The energy range of validity goes from the ground state up
to a certain upper energy where chaos sets in, and extends far beyond the range
of applicability of a simple harmonic approximation around the minimal energy
configuration. The upper energy validity limit increases for larger values of
the coupling constant and the ratio between the level splitting and the
frequency of the field. These results show that the Dicke model behaves like a
two-degree of freedom integrable model for a wide range of energies and values
of the external parameters.


title: A Practical Quantum Instruction Set Architecture

abstract:
  We introduce an abstract machine architecture for classical/quantum
computations---including compilation---along with a quantum instruction
language called Quil for explicitly writing these computations. With this
formalism, we discuss concrete implementations of the machine and non-trivial
algorithms targeting them. The introduction of this machine dovetails with
ongoing development of quantum computing technology, and makes possible
portable descriptions of recent classical/quantum algorithms.


title:
Study of weak corrections to Drell-Yan, top-quark pair and dijet
  Production at high energies with MCFM

abstract:
  Electroweak (EW) corrections can be enhanced at high energies due to the soft
or collinear radiation of virtual and real $W$ and $Z$ bosons that result in
Sudakov-like corrections of the form $\alpha_W^l\log^n(Q^2/M_{W,Z}^2)$, where
$\alpha_W =\alpha/(4\pi\sin^2\theta_W)$ and $n\le 2l-1$. The inclusion of EW
corrections in predictions for hadron colliders is therefore especially
important when searching for signals of possible new physics in distributions
probing the kinematic regime $Q^2 \gg M_V^2$. Next-to-leading order (NLO) EW
corrections should also be taken into account when their size
($\mathcal{O}(\alpha)$) is comparable to that of QCD corrections at
next-to-next-to-leading order (NNLO) ($\mathcal{O}(\alpha_s^2)$). To this end
we have implemented the NLO weak corrections to the Neutral-Current Drell-Yan
process, top-quark pair production and di-jet production in the parton-level
Monte-Carlo program MCFM. This enables a combined study with the corresponding
QCD corrections at NLO and NNLO. We provide both the full NLO weak corrections
and their Sudakov approximation since the latter is often used for a fast
evaluation of weak effects at high energies and can be extended to higher
orders. With both the exact and approximate results at hand, the validity of
the Sudakov approximation can be readily quantified


title:
Evolution of Insulator-Metal Phase Transitions in Epitaxial Tungsten
  Oxide Films during Electrolyte-Gating

abstract:
  An interface between an oxide and an electrolyte gives rise to various
processes as exemplified by electrostatic charge accumulation/depletion and
electrochemical reactions such as intercalation/decalation under electric
field. Here we directly compare typical device operations of those in electric
double layer transistor geometry by adopting ${A}$-site vacant perovskite
WO$_3$ epitaxial thin films as a channel material and two different
electrolytes as gating agent. $\textit{In situ}$ measurements of x-ray
diffraction and channel resistance performed during the gating revealed that in
both the cases WO$_3$ thin film reaches a new metallic state through multiple
phase transitions, accompanied by the change in out-of-plane lattice constant.
Electrons are electrostatically accumulated from the interface side with an
ionic liquid, while alkaline metal ions are more uniformly intercalated into
the film with a polymer electrolyte. We systematically demonstrate this
difference in the electrostatic and electrochemical processes, by comparing
doped carrier density, lattice deformation behavior, and time constant of the
phase transitions.


title:
Investigation of the role of polysaccharide in the dolomite growth at
  low temperature by using atomistic simulations

abstract:
  Dehydration of water from surface Mg2+ is most likely the rate-limiting step
in the dolomite growth at low temperature. Here, we investigate the role of
polysaccharide in this step using classical molecular dynamics (MD)
calculations. Free energy (potential of mean force, PMF) calculations have been
performed for water molecules leaving the first two hydration layers above the
dolomite (104) surface under the following three conditions: without catalyst,
with monosaccharide (mannose) and with oligosaccharide (three units of
mannose). MD simulations reveal that there is no obvious effect of
monosaccharide in lowering the dehydration barrier for surface Mg2+. However,
we found that there are metastable configurations of oligosaccharide, which can
decrease the dehydration barrier of surface Mg2+ by about 0.7-1.1 kcal/mol. In
these configurations, the molecule lies relatively flat on the surface and
forms a bridge shape. The hydrophobic space near the surface created by the
non-polar -CH groups of the oligosaccharide in the bridge conformation is the
reason for the observed reduction of dehydration barrier.


title:
Magnetoresistance generated from charge-spin conversion by anomalous
  Hall effect in metallic ferromagnetic/nonmagnetic bilayers

abstract:
  A theoretical formulation of magnetoresistance effect in a metallic
ferromagnetic/nonmagnetic bilayer originated from the charge-spin conversion by
the anomalous Hall effect is presented. Analytical expressions of the
longitudinal and transverse resistivities in both nonmagnet and ferromagnet are
obtained by solving the spin diffusion equation. The magnetoresistance
generated from charge-spin conversion purely caused by the anomalous Hall
effect in the ferromagnet is found to be proportional to the square of the spin
polarizations in the ferromagnet and has fixed sign. We also find additional
magnetoresistances in both nonmagnet and ferromagnet arising from the mixing of
the spin Hall and anomalous Hall effects. The sign of this mixing resistance
depends on those of the spin Hall angle in the nonmagnet and the spin
polarizations of the ferromagnet.


title: On Error Bound Moduli for Locally Lipschitz and Regular Functions

abstract:
  In this paper we study local error bound moduli for a locally Lipschitz and
regular function via its outer limiting subdifferential set. We show that the
distance of 0 from the outer limiting subdifferential of the support function
of the subdifferential set, which is essentially the distance of 0 from the end
set of the subdifferential set, is an upper estimate of the local error bound
modulus. This upper estimate becomes tight for a convex function under some
regularity conditions. We show that the distance of 0 from the outer limiting
subdifferential set of a lower $\mathcal{C}^1$ function is equal to the local
error bound modulus.


title:
Z-contrast imaging and ab initio study on "d" superstructure in
  sedimentary dolomite

abstract:
  Nano-precipitates with tripled periodicity along the c-axis are observed in a
Ca-rich dolomite sample from Proterozoic carbonate rocks with "molar tooth"
structure. This observation is consistent with previous description of d
reflections. High-angle annular dark-field STEM imaging (or Z-contrast imaging)
that avoids dynamic diffraction as seen in electron diffraction and
high-resolution TEM imaging modes, confirms that d reflections correspond to
nanoscale precipitates aligned parallel to (001) of the host dolomite. The
lamellae precipitates have a cation ordering sequence of Ca-Ca-Mg-Ca-Ca- Mg
along the c direction resulting in a chemical composition of Ca0.67Mg0.33CO3.
This superstructure is attributed to the extra or d reflections, thus is
referred to as the d superstructure in this study. The structure can be simply
described as interstratified calcite/dolomite. The crystal structure of the d
superstructure calculated from density functional theory (DFT) has a space
group of P31c and has a and c unit-cell parameters of 4.879 and 16.260 {\AA},
respectively, values between those of dolomite and calcite. The detailed
structural characteristics and parameters obtained from ab initio calculations
are also reported in this paper. The method of combining Z-contrast imaging and
ab initio calculations can be used for solving structures of other
nano-precipitates and nano-phases.


title: Some applications of matrix inequalities in R\'enyi entropy

abstract:
  The R{\'e}nyi entropy is one of the important information measures that
generalizes Shannon's entropy. The quantum R{\'e}nyi entropy has a fundamental
role in quantum information theory, therefore, bounding this quantity is of
vital importance. Another important quantity is R{\'e}nyi relative entropy on
which R{\'e}nyi generalization of the conditional entropy, and mutual
information are defined based. Thus, finding lower bound for R{\'e}nyi relative
entropy is our goal in this paper. We use matrix inequalities to prove new
bounds on the entropy of type $\beta$, R{\'e}nyi entropy.


title:
STEM investigation of exsolution lamellae and "c" reflections in Ca-rich
  dolomite from the Platteville Formation, western Wisconsin

abstract:
  Dolomite crystals in partially dolomitized limestone from the Platteville
Formation are both compositionally and microstructurally heterogeneous. A
single dolomite crystal usually contains three phases: the host Ca-rich
dolomite [Ca1.14Mg0.86(CO3)2], an Fe-bearing dolomite
[Ca1.06Mg0.80Fe0.14(CO3)2], and calcite inclusions. These three phases show
similar orientations. The Ca-rich dolomite exhibits modulated microstructures
with wavelength ranging from 7 to 30 nm. The modulated microstructures are not
evident in Fe-bearing dolomite. Modulations in the Ca-rich dolomite have three
predominant orientation ranges in the studied sample: from (205) to (104), from
(001) to (-101), and ~(110), which are consistent with previous studies.
Bright-field (BF) and high-angle annular dark-field (HAADF) images confirm that
these modulations are due to chemical variation rather than strain or
diffraction contrast. The Ca-rich lamellae are Mg-rich calcite with
compositions ranging from Ca0.85Mg0.15CO3 to Ca0.70Mg0.30CO3. The observed
results indicate that these Ca-rich exsolution lamellae formed during
diagenesis. In this study, three kinds of "c"-reflections, which are weak spots
in the halfway position between the principal reflections along the (104)*,
(112)*, and (110)* directions, have been found in the diffraction patterns of
some Ca-rich dolomite. Mg-Ca ordering in x-y planes was not observed directly
in Z-contrast images. FFT patterns from the Z-contrast images do not show
"c"-reflections. STEM images confirm that the "c"-reflections could result from
multiple diffraction between the host dolomite and twinned Mg-calcite
nano-lamellae under TEM imaging and diffraction modes.


title: Magnetic lattices for ultracold atoms and degenerate quantum gases

abstract:
  We review recent developments in the use of magnetic lattices as a
complementary tool to optical lattices for trapping periodic arrays of
ultracold atoms and degenerate quantum gases. Recent advances include the
realisation of Bose-Einstein condensation in multiple sites of a magnetic
lattice of one-dimensional microtraps, the trapping of ultracold atoms in
square and triangular magnetic lattices, and the fabrication of magnetic
lattice structures with sub-micron period suitable for quantum tunnelling
experiments. Finally, we describe a proposal to utilise long-range interacting
Rydberg atoms in a large spacing magnetic lattice to create interactions
between atoms on neighbouring sites.


title: Finite-time response function of uniformly accelerated entangled atoms

abstract:
  We examine the transition probability from the ground state to a final
entangled state of a system of uniformly accelerated two-level atoms weakly
coupled with a massless scalar field in Minkowski vacuum. Using time-dependent
perturbation theory we evaluate the finite-time response function and we
identify the mutual influence of atoms via the quantum field as a coherence
agent in each response function terms. The associated thermal spectrum
perceived by the atoms is found for a finite time interval. By considering
modifications of specific parameters of our setup, we also analyze how the
transition probabilities are affected by the smoothness of the switching of the
atom-field coupling. In addition, we study the mean life of the symmetric
maximally entangled state for different accelerations. Our calculations reveal
that smooth switching is more efficient than sudden switching concerning the
reduction of the decay of the entangled state. The possible relevance of our
results is discussed.


title: Gravity Gradient Tensor Eigendecomposition for Spacecraft Positioning

abstract:
  In this Note, a new approach to spacecraft positioning based on GGT inversion
is presented. The gravity gradient tensor is initially measured in the
gradiometer reference frame (GRF) and then transformed to the Earth-Centered
Earth-Fixed (ECEF) frame via attitude information as well as Earth rotation
parameters. Matrix Eigen-Decomposition is introduced to directly translate GGT
into position based on the fact that the eigenvalues and eigenvectors of GGT
are simplespecific functions of spherical coordinates of the observation
position. without the need of an initial position. Unlike the strategy of
inertial navigation aiding, no prediction or first guess of the spacecraft
position is needed. The method makes use of the J2 gravity model, and is
suitable for space navigation where higher frequency terrain contributions to
the GGT signals can be neglected.


title: Low-Earth Orbit Determination from Gravity Gradient Measurements

abstract:
  An innovative orbit determination method which makes use of gravity gradients
for Low-Earth-Orbiting satellites is proposed. The measurement principle of
gravity gradiometry is briefly reviewed and the sources of measurement error
are analyzed. An adaptive hybrid least squares batch filter based on
linearization of the orbital equation and unscented transformation of the
measurement equation is developed to estimate the orbital states and the
measurement biases. The algorithm is tested with the actual flight data from
the European Space Agency Gravity field and steady-state Ocean Circulation
Explorer. The orbit determination results are compared with the GPS-derived
orbits. The radial and cross-track position errors are on the order of tens of
meters, whereas the along-track position error is over one order of magnitude
larger. The gravity gradient based orbit determination method is promising for
potential use in GPS-denied spacecraft navigation.


title: Bi-Arc Digraphs and Conservative Polymorphisms

abstract:
  In this paper we study the class of bi-arc digraphs, important from two
seemingly unrelated perspectives. On the one hand, they are precisely the
digraphs that admit certain polymorphisms of interest in the study of
constraint satisfaction problems; on the other hand, they are a very broad
generalization of interval graphs.
  Bi-arc digraphs is the class of digraphs that admit conservative semilattice
polymorphisms. There is much interest in understanding structures that admit
particular types of polymorphisms, and especially in their recognition
algorithms. (Such problems are referred to as metaproblems.) Surprisingly, the
class of bi-arc digraphs also describes the class of digraphs that admit
certain other kinds of conservative polymorphisms. Thus solving the recognition
problem for bi-arc digraphs solves the metaproblem for digraphs for several
types of conservative polymorphisms. The complexity of the recognition problem
for digraphs with conservative semilattice polymorphisms was an open problem,
while it was known to be NP-complete for certain more complex relational
structures. We complement our result by providing a complete dichotomy
classification of which general relational structures have polynomial or
NP-complete recognition problems for the existence of conservative semilattice
polymorphisms.
  Bi-arc digraphs also generalizes the class of interval graphs; in fact it
reduces to the class of interval graphs for symmetric and reflexive digraphs.
It is much broader than interval graphs and includes other generalizations of
interval graphs such as co-threshold tolerance graphs and adjusted interval
digraphs. Yet, it is still a reasonable extension of interval graphs, in the
sense that it keeps much of the appeal of interval graphs.
  Our main result is a forbidden obstruction characterization of, and a
polynomial recognition for, the class of bi-arc digraphs.


title:
Enabling My Robot To Play Pictionary : Recurrent Neural Networks For
  Sketch Recognition

abstract:
  Freehand sketching is an inherently sequential process. Yet, most approaches
for hand-drawn sketch recognition either ignore this sequential aspect or
exploit it in an ad-hoc manner. In our work, we propose a recurrent neural
network architecture for sketch object recognition which exploits the long-term
sequential and structural regularities in stroke data in a scalable manner.
Specifically, we introduce a Gated Recurrent Unit based framework which
leverages deep sketch features and weighted per-timestep loss to achieve
state-of-the-art results on a large database of freehand object sketches across
a large number of object categories. The inherently online nature of our
framework is especially suited for on-the-fly recognition of objects as they
are being drawn. Thus, our framework can enable interesting applications such
as camera-equipped robots playing the popular party game Pictionary with human
players and generating sparsified yet recognizable sketches of objects.


title:
Experimental observation of coherent cavity soliton frequency combs in
  silica microspheres

abstract:
  We report on the experimental observation of coherent cavity soliton
frequency combs in silica microspheres. Specifically, we demonstrate that
careful alignment of the microsphere relative to the coupling fiber taper
allows for the suppression of higher-order spatial modes, reducing mode
interactions and enabling soliton formation. Our measurements show that the
temporal cavity solitons have sub-100-fs durations, exhibit considerable Raman
self-frequency shift, and generally come in groups of three or four,
occasionally with equidistant spacing in the time domain. RF amplitude noise
measurements and spectral interferometry confirm the high coherence of the
observed soliton frequency combs, and numerical simulations show good agreement
with experiments.


title: Learning Sentimental Influences from Users' Behaviors

abstract:
  Modeling interpersonal influence on different sentimental polarities is a
fundamental problem in opinion formation and viral marketing. There has not
been seen an effective solution for learning sentimental influences from users'
behaviors yet. Previous related works on information propagation directly
define interpersonal influence between each pair of users as a parameter, which
is independent from each others, even if the influences come from or affect the
same user. And influences are learned from user's propagation behaviors, namely
temporal cascades, while sentiments are not associated with them. Thus we
propose to model the interpersonal influence by latent influence and
susceptibility matrices defined on individual users and sentiment polarities.
Such low-dimensional and distributed representations naturally make the
interpersonal influences related to the same user coupled with each other, and
in turn, reduce the model complexity. Sentiments act on different rows of
parameter matrices, depicting their effects in modeling cascades. With the
iterative optimization algorithm of projected stochastic gradient descent over
shuffled mini-batches and Adadelta update rule, negative cases are repeatedly
sampled with the distribution of infection frequencies users, for reducing
computation cost and optimization imbalance. Experiments are conducted on
Microblog dataset. The results show that our model achieves better performance
than the state-of-the-art and pair-wise models. Besides, analyzing the
distribution of learned users' sentimental influences and susceptibilities
results some interesting discoveries.


title: Tuning magnetic spirals beyond room temperature with chemical disorder

abstract:
  In the past years, magnetism-driven ferroelectricity and gigantic
magnetoelectric effects have been reported for a number of frustrated magnets
with spiral magnetic orders. Such materials are of high current interest due to
their potential for spintronics and low-power magnetoelectric devices. However,
their low magnetic order temperatures (typically <100K) greatly restrict their
fields of application. Here we demonstrate that the stability domain of the
spiral phase in the perovskite YBaCuFeO5 can be enlarged by more than 150K
through a controlled manipulation of the Fe/Cu chemical disorder. Moreover we
show that this novel mechanism can stabilize the magnetic spiral state of
YBaCuFeO5 above the symbolic value of 25{\deg}C at zero magnetic field. Our
findings demonstrate that the properties of a magnetic spiral, including its
wavelength and stability range, can be engineered through the control of
chemical disorder, offering a great potential for the design of materials with
magnetoelectric properties beyond room temperature.


title: The Cold Dust Content of the Oxygen-Rich Supernova Remnant G292.0+1.8

abstract:
  We present far-infrared images of the Galactic oxygen-rich supernova remnant
(SNR) G292.0+1.8, acquired with the PACS and SPIRE instruments of the Herschel
Space Observatory. We find that the SNR shell is detected in the PACS blue (100
micron) band, but not in the red (160 micron) band, broadly consistent with
results from AKARI observations. There is no discernible emission from
G292.0+1.8 in SPIRE imagery at 250, 350 and 500 micron. Comparing the 100
micron emission to that observed with Spitzer, at 24 and 70 micron, we find a
very similar appearance for G292.0+1.8 at all three wavelengths. The IR
emission is dominated by dust from non-radiative circumstellar shocks. In
addition, the radiatively shocked O-rich clump known as the 'Spur' on the
eastern side of G292.0+1.8, is clearly detected in the PACS blueimages, with
marginal detection in the red. Fitting the existing 14-40 micron IRS spectra of
the Spur together with photometric measurements from 70 micron MIPS and 100
micron PACS photometry, we place an upper limit of <~ 0.04 solar masses, of
ejecta dust mass in the Spur, under the most conservative assumption that the
ejecta dust has a temperature of 15 K. Modeling the dust continuum in the IRS
spectra at four positions around the rim, we estimate postshock densities
ranging from n_p = 3.5 cm^-3 to 11 cm^-3. The integrated spectrum of the entire
SNR, dominated by swept up circumstellar dust, can be fit with a two-component
dust model with a silicate component at 62 K and graphite component at 40 K for
a total dust mass of 0.023 solar masses.


title:
Automatic text extraction and character segmentation using maximally
  stable extremal regions

abstract:
  Text detection and segmentation is an important prerequisite for many content
based image analysis tasks. The paper proposes a novel text extraction and
character segmentation algorithm using Maximally Stable Extremal Regions as
basic letter candidates. These regions are then subjected to thresholding and
thereafter various connected components are determined to identify separate
characters. The algorithm is tested along a set of various JPEG, PNG and BMP
images over four different character sets; English, Russian, Hindi and Urdu.
The algorithm gives good results for English and Russian character set; however
character segmentation in Urdu and Hindi language is not much accurate. The
algorithm is simple, efficient, involves no overhead as required in training
and gives good results for even low quality images. The paper also proposes
various challenges in text extraction and segmentation for multilingual inputs.


title: Searching for magnetar powered merger-novae from short GRBs

abstract:
  The merger of a double neutron star (NS-NS) binary may result in a rapidly
rotating massive NS with an extremely strong magnetic field (i.e., a
millisecond magnetar). In this case, the magnetic spin-down of the NS remnant
provides an additional source of sustained energy injection, which would
continuously power the merger ejecta. The thermal emission from the merger
ejecta would give rise to a bright optical "magnetar-powered merger-nova". In
this work, we carry out a complete search for magnetar-powered merger-nova from
Swift short gamma-ray burst (SGRB) sample. We focus on short GRBs with extended
emission or internal plateau, which may signify the presence of magnetars as
the central engine. We eventually find three candidates of magnetar-powered
merger-nova from the late observations of GRB 050724, GRB 070714B and GRB
061006. With standard parameter values, the magnetar remnant scenario could
well interpret the multi-band data of all three bursts, including the extended
emission and their late chromatic features in the optical and X-ray data. The
peak luminosities of these merger-novae reach several times $10^{42}~{\rm
erg~s^{-1}}$, more than one order of magnitude brighter than the traditional
"kilo-novae" with peak luminosity of $\sim 10^{41}~{\rm erg~s^{-1}}$. Intense,
multi-color late time observations of short GRBs are encouraged to identify
more merger-novae in the future.


title:
Blue-sky bifurcation of ion energies and the limits of neutral-gas
  sympathetic cooling of trapped ions

abstract:
  Sympathetic cooling of trapped ions through collisions with neutral buffer
gases is critical to a variety of modern scientific fields, including
fundamental chemistry, mass spectrometry, nuclear and particle physics, and
atomic and molecular physics. Despite its widespread use over four decades,
there remain open questions regarding its fundamental limitations. To probe
these limits, here we examine the steady-state evolution of up to ten barium
ions immersed in a gas of three-million laser-cooled calcium atoms. We observe
and explain the emergence of nonequilibrium behavior as evidenced by
bifurcations in the ion steady-state temperature, parameterized by ion number.
We show that this behavior leads to limitations in creating and maintaining
translationally cold samples of trapped ions using neutral-gas sympathetic
cooling. These results may provide a route to studying nonequilibrium
thermodynamics.


title:
The DoF Region of the Three-Receiver MIMO Broadcast Channel with Side
  Information and Its Relation to Index Coding Capacity

abstract:
  We consider the three-receiver Gaussian multiple-input multiple-output (MIMO)
broadcast channel with an arbitrary number of antennas at each of the
transmitter and the receivers. We investigate the degrees-of-freedom (DoF)
region of the channel when each receiver requests a private message, and may
know some of the messages requested by the other receivers as receiver message
side information (RMSI). We establish the DoF region of the channel for all 16
possible non-isomorphic RMSI configurations by deriving tight inner and outer
bounds on the region. To derive the inner bounds, we first propose a scheme for
each RMSI configuration which exploits both the null space and the side
information of the receivers. We then use these schemes in conjunction with
time sharing for 15 RMSI configurations, and with time sharing and two-symbol
extension for the remaining one. To derive the outer bounds, we construct
enhanced versions of the channel for each RMSI configuration, and upper bound
their DoF region. After establishing the DoF region, in the case where all the
nodes have the same number of antennas, we introduce some common properties of
the DoF region, and the capacity region of the index coding problem.