title:
Two Iterative Proximal-Point Algorithms for the Calculus of
  Divergence-based Estimators with Application to Mixture Models

abstract:
  Estimators derived from an EM algorithm are not robust since they are based
on the maximization of the likelihood function. We propose a proximal-point
algorithm based on the EM algorithm which aim to minimize a divergence
criterion. Resulting estimators are generally robust against outliers and
misspecification. An EM-type proximal-point algorithm is also introduced in
order to produce robust estimators for mixture models. Convergence properties
of the two algorithms are treated. We relax an identifiability condition
imposed on the proximal term in the literature; a condition which is generally
not fulfilled by mixture models. The convergence of the introduced algorithms
is discussed on a two-component Weibull mixture and a two-component Gaussian
mixture entailing a condition on the initialization of the EM algorithm in
order for the later to converge. Simulations on mixture models using different
statistical divergences are provided to confirm the validity of our work and
the robustness of the resulting estimators against outliers in comparison to
the EM algorithm.


title: $\tau$-Tilting Theory and $\tau$-Slices

abstract:
  Comparing the module categories of an algebra and of the endomorphism algebra
of a given support $\tau$-tilting module, we give a generalization of the
Brenner-Butler's tilting theorem in the framework of $\tau$-tilting theory.
Afterwards we define $\tau$-slices and prove that complete slices of tilted
algebras and local slices of cluster tilted algebras are examples of complete
$\tau$-slices. Then we apply this concept to the study of simply connected
tilted algebras. Finally, we study the one-point extensions and the
split-by-nilpotent extensions of an algebra with $\tau$-slices.


title: Strongly Interacting Light Dark Matter

abstract:
  In the presence of approximate global symmetries that forbid relevant
interactions, strongly coupled light Dark Matter (DM) can appear weakly coupled
at small energy and generate a sizable relic abundance. Fundamental principles
like unitarity restrict these symmetries to a small class, where the leading
interactions are captured by effective operators up to dimension-8. Chiral
symmetry, spontaneously broken global symmetries and non-linearly realized
supersymmetry are examples of this. Their DM candidates (composite fermions,
pseudo Nambu-Goldstone Bosons and Goldstini) are interesting targets for LHC
missing-energy searches.


title: The Last Gasp of Dark Matter Effective Theory

abstract:
  We discuss an interesting class of models, based on strongly coupled Dark
Matter (DM), where sizable effects can be expected in LHC missing energy (MET)
searches, compatibly with a large separation of scales. In this case, an
effective field theory (EFT) is appropriate (and sometimes necessary) to
describe the most relevant interactions at the LHC. The selection rules implied
by the structure of the new strong dynamics shape the EFT in an unusual way,
revealing the importance of higher-derivative interactions previously ignored.
We compare indications from relic density and direct detection experiments with
consistent LHC constraints, and asses the relative importance of the latter.
Our analysis provides an interesting and well-motivated scenario to model MET
at the LHC in terms of a handful of parameters.


title:
Quasinormal modes of nonlinear electromagnetic black holes from unstable
  null geodesics

abstract:
  The expressions for the quasinormal modes (QNMs) of black holes with
nonlinear electrodynamics, calculated in the eikonal approximation, are
presented. In the eikonal limit QNMs of black holes are determined by the
parameters of the circular null geodesics. The unstable circular null orbits
are derived from the effective metric that is the one obeyed by light rays
under the influence of a nonlinear electromagnetic field. As an illustration we
calculate the QNMs of four nonlinear electromagnetic black holes, two singular
and two regular, namely from Euler-Heisenberg and Born-Infeld theories, for
singular, and the magnetic Bardeen black hole and the one derived by Bronnikov
for regular ones. Comparison is shown with the QNMs of the linear
electromagnetic counterpart, their Reissner-Nordstr\"{o}m black hole.


title: Is there substructure around M87?

abstract:
  We present a general method to identify infalling substructure in discrete
datasets with position and line-of-sight velocity data. We exploit the fact
that galaxies falling onto a brightest cluster galaxy (BCG) in a virialised
cluster, or dwarf satellites falling onto a central galaxy like the Milky Way,
follow nearly radial orbits. If the orbits are exactly radial, we show how to
find the probability distribution for a satellite's energy, given a tracer
density for the satellite population, by solving an Abel integral equation.
This is an extension of Eddington (1916)'s classical formula for the isotropic
distribution function. When applied to a system of galaxies, clustering in
energy space can then be quantified using the Kullback-Leibler divergence, and
groups of objects can be identified which, though separated in the sky, may be
falling in on the same orbit. This method is tested using mock data and applied
to the satellite galaxy population around M87, the BCG in Virgo, and a number
of associations are found which may represent infalling galaxy groups.


title: Monitoring of the process of system information broadcasting in time

abstract:
  One of the fundamental problems of modern physics is how the classical world,
the 2nd Law of Thermodynamics and the whole irreversibility emerges from the
quantum reality with reversible evolution. This relates to the problem of
measurement transforming quantum, non-copyable data, towards intersubjective,
copyable classical knowledge. We use the quantum state discrimination to show
in a central system model how it's evolution leads to the broadcasting of the
classical information. We analyze the process of orthogonalization and
decoherence, their time scales and dependence on the environment.


title:
Narrow escape to small windows on a small ball modeling the viral entry
  into the cell nucleus

abstract:
  A certain class of viruses replicates inside a cell if they can enter the
nucleus through one of many small target pores, before being permanently
trapped or degraded. We adopt for viral motion a switching stochastic process
model and we estimate here the probability and the conditional mean first
passage time for a viral particle to attain alive the nucleus. The cell nucleus
is covered with thousands of small absorbing nuclear pores and the minimum
distance between them defines the smallest spatial scale that limits the
efficiency of stochastic simulations. Using the Neuman-Green's function method
to solve the steady-state Fokker-Planck equation, we derive asymptotic formula
for the probability and mean arrival time to a small window for various pores'
distributions, that agree with stochastic simulations. These formulas reveal
how key geometrical parameters defines the cytoplasmic stage of viral
infection.


title: Real-Time Anomaly Detection for Streaming Analytics

abstract:
  Much of the worlds data is streaming, time-series data, where anomalies give
significant information in critical situations. Yet detecting anomalies in
streaming data is a difficult task, requiring detectors to process data in
real-time, and learn while simultaneously making predictions. We present a
novel anomaly detection technique based on an on-line sequence memory algorithm
called Hierarchical Temporal Memory (HTM). We show results from a live
application that detects anomalies in financial metrics in real-time. We also
test the algorithm on NAB, a published benchmark for real-time anomaly
detection, where our algorithm achieves best-in-class results.


title:
Inferring monopartite projections of bipartite networks: an
  entropy-based approach

abstract:
  Bipartite networks are currently regarded as providing a major insight into
the organization of many real-world systems, unveiling the mechanisms driving
the interactions occurring between distinct groups of nodes. One of the most
important issues encountered when modeling bipartite networks is devising a way
to obtain a (monopartite) projection on the layer of interest, which preserves
as much as possible the information encoded into the original bipartite
structure. In the present paper we propose an algorithm to obtain
statistically-validated projections of bipartite networks, according to which
any two nodes sharing a statistically-significant number of neighbors are
linked. Since assessing the statistical significance of nodes similarity
requires a proper statistical benchmark, here we consider a set of four null
models, defined within the exponential random graph framework. Our algorithm
outputs a matrix of link-specific p-values, from which a validated projection
is straightforwardly obtainable, upon running a multiple hypothesis testing
procedure. Finally, we test our method on an economic network (i.e. the
countries-products World Trade Web representation) and a social network (i.e.
MovieLens, collecting the users' ratings of a list of movies). In both cases
non-trivial communities are detected: while projecting the World Trade Web on
the countries layer reveals modules of similarly-industrialized nations,
projecting it on the products layer allows communities characterized by an
increasing level of complexity to be detected; in the second case, projecting
MovieLens on the films layer allows clusters of movies whose affinity cannot be
fully accounted for by genre similarity to be individuated.

categories: physics.soc-ph cs.SI physics.data-an q-fin.GN


title: Polynomials Inducing the Zero Function on Local Rings

abstract:
  For a Noetherian local ring (R, m) having a finite residue field of
cardinality q, we study the connections between the ideal Z(R) of R[x], which
is the set of polynomials that vanish on R, and the ideal Z(m), the polynomials
that vanish on m, using what we call pi-polynomials: polynomials of the form
p(x) = \prod_{i = 1}^{q} (x - c_i), where c1, ..., cq is a set of
representatives of the residue classes of m. When R is Henselian we prove that
p(R) = m and show that a generating set for Z(R) may be obtained from a
generating set for Z(m) by composing with p(x). When m is principal and has
index of nilpotency e, we prove that if e \leq q then Z(m) = (x, m)^e, and if e
= q + 1 then Z(m) = (x, m)^e + (x^q - m^{q - 1} x). When R is finite, we prove
that Z(R) = \cap_{i = 1}^{q} Z(c_i + m) is a minimal primary decomposition. We
determine when Z(R) is nonzero, regular, or principal, respectively, and do the
same for Z(m). We prove that when R is complete, repeated application of p(x) +
x to elements of R will produce a sequence converging to the roots of p(x). We
show that Z(R) is the intersection of the principal ideals generated by the
pi-polynomials.


title: Two Triple binomial sum supercongruences

abstract:
  In a recent article, Apagodu and Zeilberger
(http://arxiv.org/abs/1606.03351)discuss some applications of an algorithm for
finding and proving congruence identities (modulo primes) of indefinite sums of
many combinatorial sequence. At the end, they propose some supercongruences as
conjectures. Here we prove one of them, including a new companion enumerating
abelian squares, and we leave some remarks for the others.


title:
Theory of electron and phonon transport in nano and molecular quantum
  devices: Design strategies for molecular electronics and thermoelectricity

abstract:
  Understanding the electronic and phononic transport properties of junctions
consisting of a scattering region such as a nanoscale matters or molecules
connected to two or more electrodes is the central basis for future nano and
molecular scale applications. The theoretical and mathematical techniques to
treat electron and phonon transport are leading to model the physical
properties of nano and molecular scale junctions. My aim in this paper is to
review the theoretical and mathematical techniques to treat electron and phonon
transport in nano and molecular scale junctions leading to models of their
physical properties. This helps not only to understand the experimental
observations but also provides a vital design tool to develop strategies for
molecular electronic building blocks, thermoelectric device and sensors.


title:
Anomalous transport near the Lifshitz transition at the
  LaAlO$_3$/SrTiO$_3$ interface

abstract:
  The two-dimensional electron liquid, at the (001) interface between band
insulators {L}a{A}l{O}$_3$ and {S}r{T}i{O}$_3$, undergoes Lifshitz transition
as the interface is doped with carriers. At a critical carrier density, two new
orbitals populate at the Fermi level, with a concomitant change in the Fermi
surface topology. Using dynamical mean-field theory, formulated within a
realistic three-orbital model, we study the influence of the Lifshitz
transition and local electron correlations on the transport properties. We look
at the thermal conductivity, optical conductivity, Seebeck coefficient and
angle resolved photoemission spectra and find that at a critical density, both
the thermal and dc conductivities rise sharply to higher values while the
Seebeck coefficient shows a cusp. The inter-orbital electron-electron
interaction transfers spectral weight near the $\Gamma$ point towards lower
energy, thereby reducing the critical density. In the presence of external
magnetic field, the critical density further reduces due to exchange splitting.
Beyond a sufficiently large field, multiple cusps appear in the Seebeck
coefficient revealing multiple Lifshitz transitions.


title:
Terahertz radiation from accelerating charge carriers in graphene under
  ultrafast photoexcitation

abstract:
  We study the generation of THz radiation from the acceleration of ultrafast
photoexcited charge carriers in graphene in the presence of a DC electric
field. Our model is based on calculating the transient current density from the
time-dependent distribution function which is determined using the Boltzmann
transport equation within a relaxation time approximation. We include the
time-dependent generation of carriers by the pump pulse by solving for the
carrier generation rate using the Bloch equations in the rotating wave
approximation (RWA). The linearly polarized pump pulse generates an anisotropic
distribution of photoexcited carriers in the $k_x-k_y$ plane. The collision
integral in the Boltzmann equation includes a term that leads to the
\textit{thermalization} of carriers via carrier-carrier scattering to an
effective temperature above the lattice temperature, as well as a
\textit{cooling} term which leads to energy relaxation via inelastic
carrier-phonon scattering. The radiated signal is proportional to the time
derivative of the transient current density. In spite of the fact that the
magnitude of the velocity is the same for all the carriers in graphene, there
is still emitted radiation from the photoexcited charge carriers with frequency
components in the THz range due to a change in the \textit{direction} of
velocity of the photoexcited carriers in the external electric field as well as
\textit{cooling} of the photoexcited carriers on a sub-picosecond time scale.


title:
Scaling of collision strengths for highly-excited states of ions of the
  H- and He-like sequences

abstract:
  Emission lines from highly-excited states (n >= 5) of H- and He-like ions
have been detected in astrophysical sources and fusion plasmas. For such
excited states, R-matrix or distorted wave calculations for electron-impact
excitation are very limited, due to the large size of the atomic basis set
needed to describe them. Calculations for n >= 6 are also not generally
available. We study the behaviour of the electron-impact excitation collision
strengths and effective collision strengths for the most important transitions
used to model electron collision dominated astrophysical plasmas, solar, for
example. We investigate the dependence on the relevant parameters: the
principal quantum number n or the nuclear charge Z. We also estimate the
importance of coupling to highly-excited states and the continuum by comparing
the results of different sized calculations. We provide analytic formulae to
calculate the electron-impact excitation collision strengths and effective
collision strengths to highly-excited states (n >= 8) of H- and He-like ions.
These extrapolated effective collision strengths can be used to interpret
astrophysical and fusion plasma via collisional-radiative modelling.


title:
Adjusting for Dropout Variance in Batch Normalization and Weight
  Initialization

abstract:
  We show how to adjust for the variance introduced by dropout with corrections
to weight initialization and Batch Normalization, yielding higher accuracy.
Though dropout can preserve the expected input to a neuron between train and
test, the variance of the input differs. We thus propose a new weight
initialization by correcting for the influence of dropout rates and an
arbitrary nonlinearity's influence on variance through simple corrective
scalars. Since Batch Normalization trained with dropout estimates the variance
of a layer's incoming distribution with some inputs dropped, the variance also
differs between train and test. After training a network with Batch
Normalization and dropout, we simply update Batch Normalization's variance
moving averages with dropout off and obtain state of the art on CIFAR-10 and
CIFAR-100 without data augmentation.


title:
An algebraic multigrid method for $Q_2-Q_1$ mixed discretizations of the
  Navier-Stokes equations

abstract:
  Algebraic multigrid (AMG) preconditioners are considered for discretized
systems of partial differential equations (PDEs) where unknowns associated with
different physical quantities are not necessarily co-located at mesh points.
Specifically, we investigate a $Q_2-Q_1$ mixed finite element discretization of
the incompressible Navier-Stokes equations where the number of velocity nodes
is much greater than the number of pressure nodes. Consequently, some velocity
degrees-of-freedom (dofs) are defined at spatial locations where there are no
corresponding pressure dofs. Thus, AMG approaches leveraging this co-located
structure are not applicable. This paper instead proposes an automatic AMG
coarsening that mimics certain pressure/velocity dof relationships of the
$Q_2-Q_1$ discretization. The main idea is to first automatically define coarse
pressures in a somewhat standard AMG fashion and then to carefully (but
automatically) choose coarse velocity unknowns so that the spatial location
relationship between pressure and velocity dofs resembles that on the finest
grid. To define coefficients within the inter-grid transfers, an energy
minimization AMG (EMIN-AMG) is utilized. EMIN-AMG is not tied to specific
coarsening schemes and grid transfer sparsity patterns, and so it is applicable
to the proposed coarsening. Numerical results highlighting solver performance
are given on Stokes and incompressible Navier-Stokes problems.


title: Characterizing octagonal and rectangular fibers for MAROON-X

abstract:
  We report on the scrambling performance and focal-ratio-degradation (FRD) of
various octagonal and rectangular fibers considered for MAROON-X. Our
measurements demonstrate the detrimental effect of thin claddings on the FRD of
octagonal and rectangular fibers and that stress induced at the connectors can
further increase the FRD. We find that fibers with a thick, round cladding show
low FRD. We further demonstrate that the scrambling behavior of non-circular
fibers is often complex and introduce a new metric to fully capture non-linear
scrambling performance, leading to much lower scrambling gain values than are
typically reported in the literature (<1000 compared to 10,000 or more). We
find that scrambling gain measurements for small-core, non-circular fibers are
often speckle dominated if the fiber is not agitated.


title: Covariant Differential Calculi on $SP_q^{1|2}$

abstract:
  A unitary orthosymplectic quantum supergroup is introduced. Two covariant
differential calculi on the quantum superspace $SP_q^{1|2}$ are presented. The
$h$-deformed symplectic superspaces via a contraction of the $q$-deformed
symplectic superspaces are obtained. A new $h$-deformation of the Heisenberg
superalgebra is given.


title:
Understanding the focusing of charged particle for 2D sheet beam in a
  cusped magnetic field

abstract:
  The requirement of axial magnetic field for focusing and transportation of
sheet beam using cusped magnets is less as compared to solenoid magnetic fields
which is uniform. There is often some confusion about how a cusped magnetic
field focuses high current density sheet beam because it is generally
understood that non-uniform magnetic field cannot guide the particle beam along
its axis of propagation .In this paper, we perform simple analysis of the
dynamics of sheet beam in a cusped magnetic field with single electron model
and emphasize an intuitive understanding of interesting features (as beam
geometry, positioning of permanent magnets, particle radius,particle
velocity,radius of curvature of particle inside cusped magnetic field)


title: The QCD equation of state at finite density from analytical continuation

abstract:
  We determine the equation of state of QCD at finite chemical potential, to
order $(\mu_B/T)^6$, for a system of 2+1 quark flavors. The simulations are
performed at the physical mass for the light and strange quarks on several
lattice spacings; the results are continuum extrapolated using lattices of up
to $N_t=16$ temporal resolution. The QCD pressure and interaction measure are
calculated along the isentropic trajectories in the $(T,~\mu_B)$ plane
corresponding to the RHIC Beam Energy Scan collision energies. Their behavior
is determined through analytic continuation from imaginary chemical potentials
of the baryonic density. We also determine the Taylor expansion coefficients
around $\mu_B=0$ from the simulations at imaginary chemical potentials.
Strangeness neutrality and charge conservation are imposed, to match the
experimental conditions.


title:
Optimal non-circular fiber geometries for image scrambling in
  high-resolution spectrographs

abstract:
  Optical fibers are a key component for high-resolution spectrographs to
attain high precision in radial velocity measurements. We present a custom
fiber with a novel core geometry - a 'D'-shape. From a theoretical standpoint,
such a fiber should provide superior scrambling and modal noise mitigation,
since unlike the commonly used circular and polygonal fiber cross sections, it
shows chaotic scrambling. We report on the fabrication process of a test fiber
and compare the optical properties, scrambling performance, and modal noise
behavior of the D-fiber with those of common polygonal fibers.


title: The Zero-Error Feedback Capacity of State-Dependent Channels

abstract:
  The zero-error feedback capacity of the Gelfand-Pinsker channel is
established. It can be positive even if the channel's zero-error capacity is
zero in the absence of feedback. Moreover, the error-free transmission of a
single bit may require more than one channel use. These phenomena do not occur
when the state is revealed to the transmitter causally, a case that is solved
here using Shannon strategies. Cost constraints on the channel inputs or
channel states are also discussed, as is the scenario where---in addition to
the message---also the state sequence must be recovered.


title:
Mass ordering of spectra from fragmentation of saturated gluon states in
  high multiplicity proton-proton collisions

abstract:
  The mass ordering of mean transverse momentum $\left<p_T\right>$ and of the
Fourier harmonic coefficient $v_2 (p_T)$ of azimuthally anisotropic particle
distributions in high energy hadron collisions is often interpreted as evidence
for the hydrodynamic flow of the matter produced. We investigate an alternative
initial state interpretation of this pattern in high multiplicity proton-proton
collisions at the LHC. The QCD Yang-Mills equations describing the dynamics of
saturated gluons are solved numerically with initial conditions obtained from
the Color Glass Condensate based IP-Glasma model. The gluons are subsequently
fragmented into various hadron species employing the well established Lund
string fragmentation algorithm of the PYTHIA event generator. We find that this
ab initio initial state approach reproduces characteristic features of bulk
spectra, in particular the particle mass dependence of $\left<p_T\right>$ and
$v_2 (p_T)$.


title: Is the Multigrid Method Fault Tolerant? The Two-Grid Case

abstract:
  The predicted reduced resiliency of next-generation high performance
computers means that it will become necessary to take into account the effects
of randomly occurring faults on numerical methods. Further, in the event of a
hard fault occurring, a decision has to be made as to what remedial action
should be taken in order to resume the execution of the algorithm. The action
that is chosen can have a dramatic effect on the performance and
characteristics of the scheme. Ideally, the resulting algorithm should be
subjected to the same kind of mathematical analysis that was applied to the
original, deterministic variant.
  The purpose of this work is to provide an analysis of the behaviour of the
multigrid algorithm in the presence of faults. Multigrid is arguably the method
of choice for the solution of large-scale linear algebra problems arising from
discretization of partial differential equations and it is of considerable
importance to anticipate its behaviour on an exascale machine. The analysis of
resilience of algorithms is in its infancy and the current work is perhaps the
first to provide a mathematical model for faults and analyse the behaviour of a
state-of-the-art algorithm under the model. It is shown that the Two Grid
Method fails to be resilient to faults. Attention is then turned to identifying
the minimal necessary remedial action required to restore the rate of
convergence to that enjoyed by the ideal fault-free method.


title: McStas and Mantid integration

abstract:
  McStas and Mantid are two well established software frameworks within the
neutron scattering community. McStas has been primarily used for simulating the
neutron transport of instruments, while Mantid has been primarily used for data
reduction. We report here the status of our work done on the interoperability
between the instrument simulation software McStas and the data reduction
software Mantid. This provides a demonstration of how to successfully link
together two software that otherwise have been developed independently, and in
particular here show how this has been achieved for an instrument simulation
software and a data reduction software. This paper will also provide examples
of some of the expected future enhanced analysis that can be achieved from
combining accurate instrument and sample simulations with software for
correcting raw data. In the case of this work for raw data collected at large
scale neutron facilities.


title: Quantum control in nearly non-degenerate qubits interacting with light

abstract:
  We consider the time evolution of nearly degenerate two-state systems with an
external interaction. Conditions in which full population transfer is possible
when the two-states become degenerate are considered. A new variation of the
coupled differential equations for the probability amplitudes suggests a
possible singularity in the time evolution of the system. The singularity
occurs at the point in time where full control in the degenerate limit is
achieved. We solve this new variation to derive more information about
non-degenerate population control. The new results of numerical calculations
for occupational probabilities of non-degenerate systems are presented and
interpreted. These results are used to understand how population control breaks
down as the photon energy and the energy of the system are changed.
Applications are discussed, with an emphasis on interactions of twisted-vortex
and plane-wave photons with a variety of targets, including macroscopic gas
cells of atoms, of large single crystals, and of molecules.


title:
Probing CP violation with T2K, NO$\nu$A and DUNE in the presence of
  non-unitarity

abstract:
  The presence of non-unitary neutrino mixing can affect the measurement of the
three-neutrino leptonic Dirac CP phase and hamper efforts to probe CP violation
due to degeneracies of the extra non-unitary CP phase with the standard CP
phase. We study the effect of including non-unitarity on probing CP violation
with the long-baseline experiments NO$\nu$A, T2K and DUNE. We analyze the
effect of non-unitary mixing at the level of oscillation probabilities
associated with the relevant baselines, and present the CP violation
sensitivity for the individual experiments and their combination. Our results
show that there is an improvement in the CP violation sensitivity of the
combination compared to the individual experiments.


title:
Actionable and Political Text Classification using Word Embeddings and
  LSTM

abstract:
  In this work, we apply word embeddings and neural networks with Long
Short-Term Memory (LSTM) to text classification problems, where the
classification criteria are decided by the context of the application. We
examine two applications in particular. The first is that of Actionability,
where we build models to classify social media messages from customers of
service providers as Actionable or Non-Actionable. We build models for over 30
different languages for actionability, and most of the models achieve accuracy
around 85%, with some reaching over 90% accuracy. We also show that using LSTM
neural networks with word embeddings vastly outperform traditional techniques.
Second, we explore classification of messages with respect to political
leaning, where social media messages are classified as Democratic or
Republican. The model is able to classify messages with a high accuracy of
87.57%. As part of our experiments, we vary different hyperparameters of the
neural networks, and report the effect of such variation on the accuracy. These
actionability models have been deployed to production and help company agents
provide customer support by prioritizing which messages to respond to. The
model for political leaning has been opened and made available for wider use.


title: Networked SIS Epidemics with Awareness

abstract:
  We study an SIS epidemic process over a static contact network where the
nodes have partial information about the epidemic state. They react by limiting
their interactions with their neighbors when they believe the epidemic is
currently prevalent. A node's awareness is weighted by the fraction of infected
neighbors in their social network, and a global broadcast of the fraction of
infected nodes in the entire network. The dynamics of the benchmark (no
awareness) and awareness models are described by discrete-time Markov chains,
from which mean-field approximations (MFA) are derived. The states of the MFA
are interpreted as the nodes' probabilities of being infected. We show a
sufficient condition for existence of a "metastable", or endemic, state of the
awareness model coincides with that of the benchmark model. Furthermore, we use
a coupling technique to give a full stochastic comparison analysis between the
two chains, which serves as a probabilistic analogue to the MFA analysis. In
particular, we show that adding awareness reduces the expectation of any
epidemic metric on the space of sample paths, e.g. eradication time or total
infections. We characterize the reduction in expectations in terms of the
coupling distribution. In simulations, we evaluate the effect social distancing
has on contact networks from different random graph families (geometric,
Erd\H{o}s-Renyi, and scale-free random networks).


title: Tunable point nodes from line node semimetals via application of light

abstract:
  We propose that illumination with light provides a useful platform for
creating tunable semimetals. We show that by shining light on semimetals with a
line degeneracy, one can convert them to a point node semimetal. These point
nodes are adjustable and their position can be controlled by simply rotating
the incident light beam. We also discuss the implications of this change in
Fermi surface topology, as manifested in transport observables.


title: Fast Predictive Image Registration

abstract:
  We present a method to predict image deformations based on patch-wise image
appearance. Specifically, we design a patch-based deep encoder-decoder network
which learns the pixel/voxel-wise mapping between image appearance and
registration parameters. Our approach can predict general deformation
parameterizations, however, we focus on the large deformation diffeomorphic
metric mapping (LDDMM) registration model. By predicting the LDDMM
momentum-parameterization we retain the desirable theoretical properties of
LDDMM, while reducing computation time by orders of magnitude: combined with
patch pruning, we achieve a 1500x/66x speed up compared to GPU-based
optimization for 2D/3D image registration. Our approach has better prediction
accuracy than predicting deformation or velocity fields and results in
diffeomorphic transformations. Additionally, we create a Bayesian probabilistic
version of our network, which allows evaluation of deformation field
uncertainty through Monte Carlo sampling using dropout at test time. We show
that deformation uncertainty highlights areas of ambiguous deformations. We
test our method on the OASIS brain image dataset in 2D and 3D.


title:
Mechanism of all-optical control of ferromagnetic multilayers with
  circularly polarized light

abstract:
  Time-resolved imaging reveals that the helicity dependent all-optical
switching (HD-AOS) of Co/Pt ferromagnetic multilayers proceeds by two stages.
First one involves the helicity independent and stochastic nucleation of
reversed magnetic domains. At the second stage circularly polarized light
breaks the degeneracy between the magnetic domains and promotes the preferred
direction of domain wall (DW) motion. The growth of the reversed domain from
the nucleation cite, for a particular helicity, leads to full magnetic
reversal. This study demonstrates a novel mechanism of HD-AOS mediated by the
deterministic displacement of DWs.


title: Production of Energetic Light Fragments in CEM, LAQGSM, and MCNP6

abstract:
  We extend the cascade-exciton model (CEM), and the Los Alamos version of the
quark-gluon string model (LAQGSM), event generators of the Monte-Carlo
N-particle transport code version 6 (MCNP6), to describe production of
energetic light fragments (LF) heavier than 4He from various nuclear reactions
induced by particles and nuclei at energies up to about 1 TeV/nucleon. In these
models, energetic LF can be produced via Fermi break-up, preequilibrium
emission, and coalescence of cascade particles. Initially, we study several
variations of the Fermi break-up model and choose the best option for these
models. Then, we extend the modified exciton model (MEM) used by these codes to
account for a possibility of multiple emission of up to 66 types of particles
and LF (up to 28Mg) at the preequilibrium stage of reactions. Then, we expand
the coalescence model to allow coalescence of LF from nucleons emitted at the
intranuclear cascade stage of reactions and from lighter clusters, up to
fragments with mass numbers A < 8, in the case of CEM, and A < 13, in the case
of LAQGSM. Next, we modify MCNP6 to allow calculating and outputting spectra of
LF and heavier products with arbitrary mass and charge numbers. The improved
version of CEM is implemented into MCNP6. Finally, we test the improved
versions of CEM, LAQGSM, and MCNP6 on a variety of measured nuclear reactions.
The modified codes give an improved description of energetic LF from particle-
and nucleus-induced reactions; showing a good agreement with a variety of
available experimental data. They have an improved predictive power compared to
the previous versions and can be used as reliable tools in simulating
applications involving such types of reactions.


title: How to quench a galaxy

abstract:
  We show how the interplay between active galactic nuclei (AGN) and merger
history determines whether a galaxy quenches star formation at high redshift.
We first simulate, in a full cosmological context, a galaxy of total dynamical
mass $10^{12}\,M_{\odot}$ at $z=2$. Then we systematically alter the accretion
history of the galaxy by minimally changing the linear overdensity in the
initial conditions. This "genetic modification" approach allows the generation
of three sets of $\Lambda$CDM initial conditions leading to maximum merger
ratios of 1:10, 1:5 and 2:3 respectively. The changes leave the final halo
mass, large scale structure and local environment unchanged, providing a
controlled numerical experiment. Interaction between the AGN physics and
mergers in the three cases lead respectively to a star-forming,
temporarily-quenched and permanently-quenched galaxy. However the differences
do not primarily lie in the black hole accretion rates, but in the kinetic
effects of the merger: the galaxy is resilient against AGN feedback unless its
gaseous disk is first disrupted. Typical accretion rates are comparable in the
three cases, falling below $0.1\,M_{\odot}$ yr$^{-1}$, equivalent to around
$2\%$ of the Eddington rate or $10^{-3}$ times the pre-quenching star formation
rate, in agreement with observations. This low level of black hole accretion
can be sustained even when there is insufficient dense cold gas for star
formation. Conversely, supernova feedback is too distributed to generate
outflows in high-mass systems, and cannot maintain quenching over periods
longer than the halo gas cooling time.


title: Spacetime Equals Entanglement

abstract:
  We study the Hilbert space structure of classical spacetimes under the
assumption that entanglement in holographic theories determines semiclassical
geometry. We show that this simple assumption has profound implications; for
example, a superposition of classical spacetimes may lead to another classical
spacetime. Despite its unconventional nature, this picture admits the standard
interpretation of superpositions of well-defined semiclassical spacetimes in
the limit that the number of holographic degrees of freedom becomes large. We
illustrate these ideas using a model for the holographic theory of cosmological
spacetimes.


title: Anomalous conductances in an ultracold quantum wire

abstract:
  We analyze the recently measured anomalous transport properties of an
ultracold gas through a ballistic constriction [S. Krinner et al., PNAS
201601812 (2016)]. The quantized conductance observed at weak interactions
increases several-fold as the gas is made strongly interacting, which cannot be
explained by the Landauer theory of single-channel transport. We show that this
phenomenon is due to the multichannel Andreev reflections at the edges of the
constriction, where the interaction and confinement result in a superconducting
state. Andreev processes convert atoms of otherwise reflecting channels into
the condensate propagating through the constriction, leading to a significant
excess conductance. Furthermore, we find the spin conductance being suppressed
by superconductivity; the agreement with experiment provides an additional
support for our model.

categories: cond-mat.quant-gas cond-mat.mes-hall cond-mat.supr-con physics.atom-ph


title:
Hawking radiation and the Stefan-Boltzmann law: The effective radius of
  the black-hole quantum atmosphere

abstract:
  It has recently been suggested [S. B. Giddings, Phys. Lett. B {\bf 754}, 39
(2016)] that the Hawking black-hole radiation spectrum originates from an
effective quantum "atmosphere" which extends well outside the black-hole
horizon. In particular, comparing the Hawking radiation power of a
$(3+1)$-dimensional Schwarzschild black hole of horizon radius $r_{\text{H}}$
with the familiar Stefan-Boltzmann radiation power of a $(3+1)$-dimensional
flat space perfect blackbody emitter, Giddings concluded that the source of the
Hawking semi-classical black-hole radiation is a quantum region outside the
Schwarzschild black-hole horizon whose effective radius $r_{\text{A}}$ is
characterized by the relation $\Delta r\equiv r_{\text{A}}-r_{\text{H}}\sim
r_{\text{H}}$. It is of considerable physical interest to test the general
validity of Giddings's intriguing conclusion. To this end, we study the Hawking
radiation of $(D+1)$-dimensional Schwarzschild black holes. We find that the
dimensionless radii $r_{\text{A}}/r_{\text{H}}$ which characterize the
black-hole quantum atmospheres, as determined from the Hawking black-hole
radiation power and the $(D+1)$-dimensional Stefan-Boltzmann radiation law, are
a decreasing function of the number $D+1$ of spacetime dimensions. In
particular, it is shown that radiating $(D+1)$-dimensional Schwarzschild black
holes are characterized by the relation
$(r_{\text{A}}-r_{\text{H}})/r_{\text{H}}\ll1$ in the large $D\gg1$ regime. Our
results therefore suggest that, at least in some physical cases, the Hawking
emission spectrum originates from quantum excitations very near the black-hole
horizon.


title:
Far-infrared line spectra of active galaxies from the Herschel/PACS
  Spectrometer: the complete database

abstract:
  We present a coherent database of spectroscopic observations of far-IR
fine-structure lines from the Herschel/PACS archive for a sample of 170 local
AGN, plus a comparison sample of 20 starburst galaxies and 43 dwarf galaxies.
Published Spitzer/IRS and Herschel/SPIRE line fluxes are included to extend our
database to the full 10-600 $\mu m$ spectral range. The observations are
compared to a set of CLOUDY photoionisation models to estimate the above
physical quantities through different diagnostic diagrams. We confirm the
presence of a stratification of gas density in the emission regions of the
galaxies, which increases with the ionisation potential of the emission lines.
The new [OIV]25.9$\mu m$/[OIII]88$\mu m$ vs [NeIII]15.6$\mu m$/[NeII]12.8$\mu
m$ diagram is proposed as the best diagnostic to separate: $i)$ AGN activity
from any kind of star formation; and $ii)$ low-metallicity dwarf galaxies from
starburst galaxies. Current stellar atmosphere models fail to reproduce the
observed [OIV]25.9$\mu m$/[OIII]88$\mu m$ ratios, which are much higher when
compared to the predicted values. Finally, the ([NeIII]15.6$\mu m$ +
[NeII]12.8$\mu m$)/([SIV]10.5$\mu m$ + [SIII]18.7$\mu m$) ratio is proposed as
a promising metallicity tracer to be used in obscured objects, where optical
lines fail to accurately measure the metallicity. The diagnostic power of mid-
to far-infrared spectroscopy shown here for local galaxies will be of crucial
importance to study galaxy evolution during the dust-obscured phase at the peak
of the star formation and black-hole accretion activity ($1 < z < 4$). This
study will be addressed by future deep spectroscopic surveys with present and
forthcoming facilities such as JWST, ALMA, and SPICA.


title: Superconductivity from Doublon Condensation in the Ionic Hubbard Model

abstract:
  In the ionic Hubbard model, the onsite repulsion $U$, which drives a Mott
insulator and the ionic potential $V$, which drives a band insulator, compete
with each other to open up a window of charge fluctuations when $U \sim V$. We
study this model on square and cubic lattices in the limit of large $U$ and
$V$, with $V\sim U$. Using an effective Hamiltonian and a slave boson approach
with both doublons and holes, we find that the system undergoes a phase
transition as a function of $V$ from an antiferromagnetic Mott insulator to a
paramagnetic insulator with strong singlet correlations, which is driven by a
condensate of "neutral" doublon-hole pairs. On further increasing $V$, the
system undergoes another phase transition to a superconducting phase driven by
condensate of "charged" doublons and holes. The superfluid phase, characterized
by presence of coherent (but gapped) fermionic quasiparticle, and $hc/e$ flux
quantization, has a high $T_c \sim t $ which shows a dome shaped behaviour as a
function of $V$. The paramagnetic insulator phase has a deconfined U(1) gauge
field and associated gapless photon excitations. We also discuss how these
phases can be detected in the ultracold atom context.


title: ALMA Observations of the Debris Disk of Solar Analogue Tau Ceti

abstract:
  We present 1.3 mm observations of the Sun-like star $\tau$ Ceti with the
Atacama Large Millimeter/submillimeter Array (ALMA) that probe angular scales
of $\sim1$'' (4 AU). This first interferometric image of the $\tau$ Ceti
system, which hosts both a debris disk and possible multiplanet system, shows
emission from a nearly face-on belt of cold dust with a position angle of
$90^\circ$ surrounding an unresolved central source at the stellar position. To
characterize this emission structure, we fit parametric models to the
millimeter visibilities. The resulting best-fit model yields an inner belt edge
of $6.2^{+9.8}_{-4.6}$ AU, consistent with inferences from lower resolution,
far-infrared Herschel observations. While the limited data at sufficiently
short baselines preclude us from placing stronger constraints on the belt
properties and its relation to the proposed five planet system, the
observations do provide a strong lower limit on the fractional width of the
belt, $\Delta R/R > 0.75$ with $99\%$ confidence. This fractional width is more
similar to broad disks such as HD 107146 than narrow belts such as the Kuiper
Belt and Fomalhaut. The unresolved central source has a higher flux density
than the predicted flux of the stellar photosphere at 1.3 mm. Given previous
measurements of an excess by a factor of $\sim2$ at 8.7 mm, this emission is
likely due to a hot stellar chromosphere.


title: Random Functions via Dyson Brownian Motion: Progress and Problems

abstract:
  We develope a computationally efficient extension of the Dyson Brownian
Motion (DBM) algorithm to generate random function in C2 locally. We further
explain that random functions generated via DBM show an unstable growth as the
traversed distance increases. This feature restricts the use of such functions
considerably if they are to be used to model globally defined ones. The latter
is the case if one uses random functions to model landscapes in string theory.
We provide a concrete example, based on a simple axionic potential often used
in cosmology, to highlight this problem and also offer an ad hoc modification
of DBM that suppresses this growth to some degree.


title: Dark energy from the motions of neutrinos

abstract:
  We demonstrate that a scalar field is unable to reverse its direction of
motion while continuously exchanging energy with another fluid. If the rate of
transfer is modulated by the scalar's acceleration, the field can undergo a
rapid process of freezing, despite being displaced from the local minimum of
its potential. This enables dark energy to form from any potential, regardless
of its shape. The field's equation of state mimicks that of a cosmological
constant. We present a physically motivated realisation in the form of a
derivative neutrino-majoron coupling. Coherent motions, which form only once
the neutrinos become non-relativistic, could be responsible for instigating the
freezing process. This would provide a natural resolution to the dark energy
coincidence problem, while avoiding the dynamical instabilities associated with
mass-varying neutrino models. Finally we discuss possible means by which this
model could be experimentally verified.


title: Pseudo-Marginal Hamiltonian Monte Carlo

abstract:
  Bayesian inference in the presence of an intractable likelihood function is
computationally challenging. When following a Markov chain Monte Carlo (MCMC)
approach to approximate the posterior distribution in this context, one
typically either uses MCMC schemes which target the joint posterior of the
parameters and some auxiliary latent variables, or pseudo-marginal
Metropolis--Hastings (MH) schemes. The latter mimic a MH algorithm targeting
the marginal posterior of the parameters by approximating unbiasedly the
intractable likelihood. However, in scenarios where the parameters and
auxiliary variables are strongly correlated under the posterior and/or this
posterior is multimodal, Gibbs sampling or Hamiltonian Monte Carlo (HMC) will
perform poorly and the pseudo-marginal MH algorithm, as any other MH scheme,
will be inefficient for high dimensional parameters. We propose here an
original MCMC algorithm, termed pseudo-marginal HMC, which combines the
advantages of both HMC and pseudo-marginal schemes. Specifically, the
pseudo-marginal HMC method is controlled by a precision parameter N,
controlling the approximation of the likelihood and, for any N, it samples the
marginal posterior of the parameters. Additionally, as N tends to infinity, its
sample trajectories and acceptance probability converge to those of an ideal,
but intractable, HMC algorithm which would have access to the marginal
posterior of parameters and its gradient. We demonstrate through experiments
that pseudo-marginal HMC can outperform significantly both standard HMC and
pseudo-marginal MH schemes.


title:
Antagonistic effects of nearest-neighbor repulsion on the
  superconducting pairing dynamics in the doped Mott insulator regime

abstract:
  The nearest-neighbor superexchange-mediated mechanism for d_{x^2-y^2}-wave
superconductivity in the one-band Hubbard model faces the challenge that
nearest-neighbor Coulomb repulsion can be larger than superexchange. To answer
this question, we use cellular dynamical mean-field theory (CDMFT) with a
continuous-time quantum Monte Carlo solver to determine the superconducting
phase diagram as a function of temperature and doping for on-site repulsion
$U=9t$ and nearest-neighbor repulsion $V=0,2t,4t$. In the underdoped regime,
$V$ increases the CDMFT superconducting transition temperature $T_c^d$ even
though it decreases the superconducting order parameter at low temperature for
all dopings. However, $V$ decreases $T_c^d$ in the overdoped regime. We gain
insight into these paradoxical results through a detailed study of the
frequency dependence of the anomalous spectral function, extracted at finite
temperature via the MaxEntAux method for analytic continuation. A systematic
study of dynamical positive and negative contributions to pairing reveals that
even though $V$ has a high-frequency depairing contribution, it also has a low
frequency pairing contribution since it can reinforce superexchange through
$J=4t^2/(U-V)$. Retardation is thus crucial to understand pairing in doped Mott
insulators, as suggested by previous zero-temperature studies. We also comment
on the tendency to charge order for large $V$ and on the persistence of d-wave
superconductivity over extended-$s$ or s+d-wave.


title:
Contents of partitions and the combinatorics of permutation
  factorizations in genus 0

abstract:
  The central object of study is a formal power series that we call the content
series, a symmetric function involving an arbitrary underlying formal power
series $f$ in the contents of the cells in a partition. In previous work we
have shown that the content series satisfies the KP equations. The main result
of this paper is a new partial differential equation for which the content
series is the unique solution, subject to a simple initial condition. This
equation is expressed in terms of families of operators that we call
$\mathcal{U}$ and $\mathcal{D}$ operators, whose action on the Schur symmetric
function $s_{\lambda}$ can be simply expressed in terms of powers of the
contents of the cells in $\lambda$. Among our results, we construct the
${\mathcal{U}}$ and ${\mathcal{D}}$ operators explicitly as partial
differential operators in the underlying power sum symmetric functions. We also
give a combinatorial interpretation for the content series in terms of the
Jucys-Murphy elements in the group algebra of the symmetric group. This leads
to an interpretation for the content series as a generating series for branched
covers of the sphere by a Riemann surface of arbitrary genus $g$. As particular
cases, by suitable choice of the underlying series $f$, the content series
specializes to the generating series for three known classes of branched
covers: Hurwitz numbers, monotone Hurwitz numbers, and $m$-hypermap numbers. We
apply our pde to give new proofs of the explicit formulas for these three
classes of number in genus $0$. In the case of the $m$-hypermap numbers of
Bousquet-M\'elou and Schaeffer, this is the first algebraic proof of this
result.


title:
A Pacemaker with P=2.48 hour Modulated the Generator of Flares in the
  X-ray Light Curve of Sgr A* in the year 2012

abstract:
  In an intensive observational campaign in the 9 month duration of Chandra
X-ray Visionary Project that was conducted in the year 2012, 39 large X-ray
flares of Sgr A* were recorded. An analysis of the times of the observed flares
reveals that the 39 flares are separated in time by intervals that are grouped
around integer numbers times 0.10333 days. This time interval is thus the
period of a uniform grid of equally spaced points on the time axis. The
grouping of the flares around tic marks of this grid is derived from the data
with at least a 3.2 {\sigma} level of statistical significance. No signal of
any period can be found among 22 flares recorded by Chandra in the years
2013-2014. If the 0.10333 d period is that of a nearly circular Keplerian orbit
around the blackhole at the center of the Galaxy, its radius is at 7.6
Schwarzschild radii. Large flares were more likely to be triggered when the
agent responsible for their outbursts was near the peri-center phase of its
slightly eccentric orbit.


title:
ALMA Reveals Weak [NII] Emission in "Typical" Galaxies and Intense
  Starbursts at z=5-6

abstract:
  We report interferometric measurements of [NII] 205 um fine-structure line
emission from a representative sample of three galaxies at z=5-6 using the
Atacama Large (sub)Millimeter Array (ALMA). These galaxies were previously
detected in [CII] and far-infrared continuum emission and span almost two
orders of magnitude in star formation rate (SFR). Our results show at least two
different regimes of ionized inter-stellar medium properties for galaxies in
the first billion years of cosmic time, separated by their L_[CII]/L_[NII]
ratio. We find extremely low [NII] emission compared to [CII] (L_
[CII]/L_[NII]=68 [+200/-28]) from a "typical" L*_UV star-forming galaxy, likely
directly or indirectly (by its effect on the radiation field) related to low
dust abundance and low metallicity. The infrared-luminous modestly star-forming
Lyman Break Galaxy (LBG) in our sample is characterized by an ionized-gas
fraction (L_[CII]/L_[NII]<=20) typical of local star-forming galaxies and shows
evidence for spatial variations in its ionized-gas fraction across an extended
gas reservoir. The extreme SFR, warm and compact dusty starburst AzTEC-3 shows
an ionized fraction higher than expected given its star-formation rate surface
density (L_[CII]/L_[NII]=22+/-8) suggesting that [NII] dominantly traces a
diffuse ionized medium rather than star-forming HII regions in this type of
galaxy. This highest redshift sample of [NII] detections provides some of the
first constraints on ionized and neutral gas modeling attempts and on the
structure of the inter-stellar medium at z=5-6 in "normal" galaxies and
starbursts.


title: Parton Fragmentation Functions

abstract:
  The field of fragmentation functions of light quarks and gluons is reviewed.
In addition to integrated fragmentation functions, attention is paid to the
dependence of fragmentation functions on transverse momenta and on polarization
degrees of freedom. Higher-twist and di-hadron fragmentation functions are
considered as well. Moreover, the review covers both theoretical and
experimental developments in single-inclusive hadron production in
electron-positron annihilation, deep-inelastic lepton-nucleon scattering, and
proton-proton collisions.


title: Log-Concave Duality in Estimation and Control

abstract:
  In this paper we generalize the estimation-control duality that exists in the
linear-quadratic-Gaussian setting. We extend this duality to maximum a
posteriori estimation of the system's state, where the measurement and
dynamical system noise are independent log-concave random variables. More
generally, we show that a problem which induces a convex penalty on noise terms
will have a dual control problem. We provide conditions for strong duality to
hold, and then prove relaxed conditions for the piecewise linear-quadratic
case. The results have applications in estimation problems with nonsmooth
densities, such as log-concave maximum likelihood densities. We conclude with
an example reconstructing optimal estimates from solutions to the dual control
problem, which has implications for sharing solution methods between the two
types of problems.


title:
Orbital Stability of Periodic Traveling-Wave Solutions for a Dispersive
  Equation

abstract:
  In this paper we establish the orbital stability of periodic traveling waves
for a general class of dispersive equations. We use the Implicit Function
Theorem to guarantee the existence of smooth solutions depending of the
corresponding wave speed. Essentially, our method establishes that if the
linearized operator has only one negative eigenvalue which is simple and zero
is a simple eigenvalue the orbital stability is determined provided that a
convenient condition about the average of the wave is satisfied. We use our
approach to prove the orbital stability of periodic dnoidal waves associated
with the Kawahara equation.


title:
The Replica-Symmetric Prediction for Compressed Sensing with Gaussian
  Matrices is Exact

abstract:
  This paper considers the fundamental limit of compressed sensing for i.i.d.
signal distributions and i.i.d. Gaussian measurement matrices. Its main
contribution is a rigorous characterization of the asymptotic mutual
information (MI) and minimum mean-square error (MMSE) in this setting. Under
mild technical conditions, our results show that the limiting MI and MMSE are
equal to the values predicted by the replica method from statistical physics.
This resolves a well-known problem that has remained open for over a decade.


title:
Direct Imaging Discovery of a Jovian Exoplanet Within a Triple Star
  System

abstract:
  Direct imaging allows for the detection and characterization of exoplanets
via their thermal emission. We report the discovery via imaging of a young
Jovian planet in a triple star system and characterize its atmospheric
properties through near-infrared spectroscopy. The semi-major axis of the
planet is closer relative to that of its hierarchical triple star system than
for any known exoplanet within a stellar binary or triple, making HD 131399
dynamically unlike any other known system. The location of HD 131399Ab on a
wide orbit in a triple system demonstrates that massive planets may be found on
long and possibly unstable orbits in multi-star systems. HD 131399Ab is one of
the lowest mass (4+/-1 MJup) and coldest (850+/-50 K) exoplanets to have been
directly imaged.


title: Optimal Auction Design for Flexible Consumers

abstract:
  We study the problem of designing revenue-maximizing auctions for allocating
multiple goods to flexible consumers. In our model, each consumer is interested
in a subset of goods known as its flexibility set and wants to consume one good
from this set. A consumer's flexibility set and its utility from consuming a
good from its flexibility set are its private information. We focus on the case
of nested flexibility sets --- each consumer's flexibility set can be one of
$k$ nested sets. We provide several examples where such nested flexibility sets
may arise. We characterize the allocation rule for an incentive compatible,
individually rational and revenue-maximizing auction as the solution to an
integer program. The corresponding payment rule is described by an integral
equation. We then leverage the nestedness of flexibility sets to simplify the
optimal auction and provide a complete characterization of allocations and
payments in terms of simple thresholds.


title: Kaon fluctuations from lattice QCD

abstract:
  We show that it is possible to isolate a set of kaon fluctuations in lattice
QCD. By means of the Hadron Resonance Gas (HRG) model, we calculate the actual
kaon second-to-first fluctuation ratio, which receives contribution from
primordial kaons and resonance decays, and show that it is very close to the
one obtained for primordial kaons in the Boltzmann approximation. The latter
only involves the strangeness and electric charge chemical potentials, which
are functions of $T$ and $\mu_B$ due to the experimental constraint on
strangeness and electric charge, and can therefore be calculated on the
lattice. This provides an unambiguous method to extract the kaon freeze-out
temperature, by comparing the lattice results to the experimental values for
the corresponding fluctuations.


title:
Large-strain poroelastic plate theory for polymer gels with applications
  to swelling-induced morphing of composite plates

abstract:
  We derive a large-strain plate model that allows to describe transient,
coupled processes involving elasticity and solvent migration, by performing a
dimensional reduction of a three-dimensional poroelastic theory. We apply the
model to polymer gel plates, for which a specific kinematic constraint and
constitutive relations hold. Finally, we assess the accuracy of the plate model
with respect to the parent three-dimensional model through two numerical
benchmarks, solved by means of the finite element method. Our results show that
the theory offers an efficient computational framework for the study of
swelling-induced morphing of composite gel plates.


title:
Accelerating dark-matter axion searches with quantum measurement
  technology

abstract:
  The axion particle, a consequence of an elegant hypothesis that resolves the
strong-CP problem of quantum chromodynamics, is a plausible origin for
cosmological dark matter. In searches for axionic dark matter that detect the
conversion of axions to microwave photons, the quantum noise associated with
microwave vacuum fluctuations will soon limit the rate at which parameter space
is searched. Here we show that this noise can be partially overcome either by
squeezing the quantum vacuum using recently developed Josephson parametric
devices, or by using superconducting qubits to count microwave photons. The
recently demonstrated ability of superconducting qubits to make QND
measurements of microwave photons offers great advantages over destructive
photon counting methods such as those using Rydberg atoms.


title: Strain-induced pseudomagnetic field in Dirac semimetal borophene

abstract:
  A tight-binding model of 8-Pmmn borophene, a two-dimensional boron crystal,
is developed. We confirm that the crystal hosts massless Dirac fermions and the
Dirac points are protected by symmetry. Strain is introduced into the model,
and it is shown to induce a pseudomagnetic field vector potential and a scalar
potential. The dependence of the potentials on the strain tensor is calculated.
The physical effects controlled by pseudomagnetic field are discussed.


abstract:
  This is the Proceedings of the 2016 ICML Workshop on Human Interpretability
in Machine Learning (WHI 2016), which was held in New York, NY, June 23, 2016.
  Invited speakers were Susan Athey, Rich Caruana, Jacob Feldman, Percy Liang,
and Hanna Wallach.


title: The AFLOW Library of Crystallographic Prototypes

abstract:
  An easily available resource of common crystal structures is essential for
researchers, teachers, and students. For many years this was provided by the
U.S. Naval Research Laboratory's $Crystal\ Lattice\ Structures$ web page, which
contained nearly 300 crystal structures, including a majority of those which
were given $Strukturbericht$ designations. This article presents the updated
version of the database, now including 288 standardized structures in 92 space
groups. Similar to what was available on the web page before, we present a
complete description of each structure, including the formulas for the
primitive vectors, all of the basis vectors, and the AFLOW commands to generate
the standardied cells. We also present a brief discussion of crystal systems,
space groups, primitive and conventional lattices, Wyckoff positions, Pearson
symbols and $Strukturbericht$ designations.


title: Adversarial examples in the physical world

abstract:
  Most existing machine learning classifiers are highly vulnerable to
adversarial examples. An adversarial example is a sample of input data which
has been modified very slightly in a way that is intended to cause a machine
learning classifier to misclassify it. In many cases, these modifications can
be so subtle that a human observer does not even notice the modification at
all, yet the classifier still makes a mistake. Adversarial examples pose
security concerns because they could be used to perform an attack on machine
learning systems, even if the adversary has no access to the underlying model.
Up to now, all previous work have assumed a threat model in which the adversary
can feed data directly into the machine learning classifier. This is not always
the case for systems operating in the physical world, for example those which
are using signals from cameras and other sensors as an input. This paper shows
that even in such physical world scenarios, machine learning systems are
vulnerable to adversarial examples. We demonstrate this by feeding adversarial
images obtained from cell-phone camera to an ImageNet Inception classifier and
measuring the classification accuracy of the system. We find that a large
fraction of adversarial examples are classified incorrectly even when perceived
through the camera.


title: Conserved energies for the cubic NLS in 1-d

abstract:
  We consider the cubic Nonlinear Schr\"odinger Equation (NLS) as well as the
modified Korteweg-de Vries (mKdV) equation in one space dimension. We prove
that for each $s>-\frac12$ there exists a conserved energy which is equivalent
to the $H^s$ norm of the solution. For the Korteweg-de Vries (KdV) equation
there is a similar conserved energy for every $s\ge -1$.


title: Learning from Multiway Data: Simple and Efficient Tensor Regression

abstract:
  Tensor regression has shown to be advantageous in learning tasks with
multi-directional relatedness. Given massive multiway data, traditional methods
are often too slow to operate on or suffer from memory bottleneck. In this
paper, we introduce subsampled tensor projected gradient to solve the problem.
Our algorithm is impressively simple and efficient. It is built upon projected
gradient method with fast tensor power iterations, leveraging randomized
sketching for further acceleration. Theoretical analysis shows that our
algorithm converges to the correct solution in fixed number of iterations. The
memory requirement grows linearly with the size of the problem. We demonstrate
superior empirical performance on both multi-linear multi-task learning and
spatio-temporal applications.


title:
A primal-dual method for conic constrained distributed optimization
  problems

abstract:
  We consider cooperative multi-agent consensus optimization problems over an
undirected network of agents, where only those agents connected by an edge can
directly communicate. The objective is to minimize the sum of agent-specific
composite convex functions over agent-specific private conic constraint sets;
hence, the optimal consensus decision should lie in the intersection of these
private sets. We provide convergence rates both in sub-optimality,
infeasibility and consensus violation; examine the effect of underlying network
topology on the convergence rates of the proposed decentralized algorithms; and
show how to extend these methods to handle time-varying communications networks
and to solve problems with resource sharing constraints.


title: Multi-level Contextual RNNs with Attention Model for Scene Labeling

abstract:
  Context in image is crucial for scene labeling while existing methods only
exploit local context generated from a small surrounding area of an image patch
or a pixel, by contrast long-range and global contextual information is
ignored. To handle this issue, we in this work propose a novel approach for
scene labeling by exploring multi-level contextual recurrent neural networks
(ML-CRNNs). Specifically, we encode three kinds of contextual cues, i.e., local
context, global context and image topic context in structural recurrent neural
networks (RNNs) to model long-range local and global dependencies in image. In
this way, our method is able to `see' the image in terms of both long-range
local and holistic views, and make a more reliable inference for image
labeling. Besides, we integrate the proposed contextual RNNs into hierarchical
convolutional neural networks (CNNs), and exploit dependence relationships in
multiple levels to provide rich spatial and semantic information. Moreover, we
novelly adopt an attention model to effectively merge multiple levels and show
that it outperforms average- or max-pooling fusion strategies. Extensive
experiments demonstrate that the proposed approach achieves new
state-of-the-art results on the CamVid, SiftFlow and Stanford-background
datasets.


abstract:
  A data-driven method for improving the correlation estimation in serial
ensemble Kalman filters is introduced. The method finds a linear map that
transforms, at each assimilation cycle, the poorly estimated sample correlation
into an improved correlation. This map is obtained from an offline training
procedure without any tuning as the solution of a linear regression problem
that uses appropriate sample correlation statistics obtained from historical
data assimilation products. In an idealized OSSE with the Lorenz-96 model and
for a range of cases of linear and nonlinear observation models, the proposed
scheme improves the filter estimates, especially when the ensemble size is
small relative to the dimension of the state space.


title: Graph Construction with Label Information for Semi-Supervised Learning

abstract:
  In the literature, most existing graph-based semi-supervised learning (SSL)
methods only use the label information of observed samples in the label
propagation stage, while ignoring such valuable information when learning the
graph. In this paper, we argue that it is beneficial to consider the label
information in the graph learning stage. Specifically, by enforcing the weight
of edges between labeled samples of different classes to be zero, we explicitly
incorporate the label information into the state-of-the-art graph learning
methods, such as the Low-Rank Representation (LRR), and propose a novel
semi-supervised graph learning method called Semi-Supervised Low-Rank
Representation (SSLRR). This results in a convex optimization problem with
linear constraints, which can be solved by the linearized alternating direction
method. Though we take LRR as an example, our proposed method is in fact very
general and can be applied to any self-representation graph learning methods.
Experiment results on both synthetic and real datasets demonstrate that the
proposed graph learning method can better capture the global geometric
structure of the data, and therefore is more effective for semi-supervised
learning tasks.


title:
A Search for $0^+$ States in $^{50}$Cr: Implications for the
  Superallowed $\beta$-decay of $^{50}$Mn

abstract:
  A $^{52}$Cr$(p,t)$$^{50}$Cr two-neutron pickup reaction was performed using
the Q3D magnetic spectrograph at the Maier-Leibnitz-Laboratorium in Garching,
Germany. Excited states in $^{50}$Cr were observed up to an excitation energy
of 5.3 MeV. Despite significantly increased sensitivity and resolution over
previous work, no evidence of the previously assigned first excited $0^+$ state
was found. As a result, the $0^+_2$ state is reassigned at an excitation energy
of $E_x=3895.0(5)$ keV in $^{50}$Cr. This reassignment directly impacts direct
searches for a non-analogue Fermi $\beta^+$ decay branch in $^{50}$Mn. These
results also show better systematic agreement with the theoretical predictions
for the $0^+$ state spectrum in $^{50}$Cr using the same formalism as the
isospin-symmetry-breaking correction calculations for superallowed nuclei. The
experimental data are also compared to $ab$-$initio$ shell-model predictions
using the IM-SRG formalism based on $NN$ and $3N$ forces from chiral-EFT in the
$pf$-shell for the first time.


title:
Models for the 3-D axisymmetric gravitational potential of the Milky Way
  Galaxy - A detailed modelling of the Galactic disk

abstract:
  Aims. Galaxy mass models based on simple and analytical functions for the
density and potential pairs have been widely proposed in the literature. Disk
models constrained by kinematic data alone give information on the global disk
structure only very near the Galactic plane. We attempt to circumvent this
issue by constructing disk mass models whose three-dimensional structures are
constrained by a recent Galactic star counts model in the near-infrared and
also by observations of the hydrogen distribution in the disk. Our main aim is
to provide models for the gravitational potential of the Galaxy that are fully
analytical but also with a more realistic description of the density
distribution in the disk component. Methods. From the disk model directly based
on the observations (here divided into the thin and thick stellar disks and the
HI and H$_2$ disks subcomponents), we produce fitted mass models by combining
three Miyamoto-Nagai disk profiles of any "model order" (1, 2, or 3) for each
disk subcomponent. The Miyamoto-Nagai disks are combined with models for the
bulge and "dark halo" components and the total set of parameters is adjusted by
observational kinematic constraints. A model which includes a ring density
structure in the disk, beyond the solar Galactic radius, is also investigated.
Results. The Galactic mass models return very good matches to the imposed
observational constraints. In particular, the model with the ring density
structure provides a greater contribution of the disk to the rotational support
inside the solar circle. The gravitational potential models and their
associated force-fields are described in analytically closed forms, and in
addition, they are also compatible with our best knowledge of the stellar and
gas distributions in the disk component. The gravitational potential models are
suited for investigations of orbits in the Galactic disk.


title: Fermionic Correlators from Integrability

abstract:
  We study three-point functions of single-trace operators in the su(1|1)
sector of planar N = 4 SYM borrowing several tools based on Integrability. In
the most general configuration of operators in this sector, we have found a
determinant expression for the tree-level structure constants. We then compare
the predictions of the recently proposed hexagon program against all available
data. We have obtained a match once additional sign factors are included when
the two hexagon form-factors are assembled together to form the structure
constants. In the particular case of one BPS and two non-BPS operators we
managed to identify the relevant form-factors with a domain wall partition
function of a certain six-vertex model. This partition function can be
explicitly evaluated and factorizes at all loops. In addition, we use this
result to compute the structure constants and show that at strong coupling in
the so-called BMN regime, its leading order contribution has a determinant
expression.


title: A lower bound for the least prime in an arithmetic progression

abstract:
  Fix $k$ a positive integer, and let $\ell$ be coprime to $k$. Let $p(k,\ell)$
denote the smallest prime equivalent to $\ell \pmod{k}$, and set $P(k)$ to be
the maximum of all the $p(k,\ell)$. We seek lower bounds for $P(k)$. In
particular, we show that for almost every $k$ one has $P(k) \gg \phi(k) \log k
\log_2 k \log_4 k / \log_3 k,$ answering a question of Ford, Green, Konyangin,
Maynard, and Tao. We rely on their recent work on large gaps between primes.
Our main new idea is to use sieve weights to capture not only primes, but also
small multiples of primes. We also give a heuristic which suggests that
$\liminf_{k} \frac{P(k)}{ \phi(k) \log^2 k} = 1.$


title: Polynomial Bound on the Local Betti Numbers of a Real Analytic Germ

abstract:
  This article proves the existence of a bound on the sum of local Betti
numbers of a real analytic germ by a polynomial function of its multiplicity.
This result can be interpreted as a localization of the classical
Oleinik-Petrovsky bound (also known as Thom-Milnor bound) on the sum of Betti
numbers of a semi-algebraic set.
  The proof relies on an interplay between geometric and algebraic arguments
whose key elements are the tangent cone of the germ, the Thom-Mather
topological trivialization theorem, the Oleinik-Petrovsky bound, and a result
by D. Mumford and J. Heintz bounding the degrees of the generators of an ideal
by a polynomial function of the geometric degree of its associated variety.
  Our result is then applied to yield bounds on invariants from singularity
theory, such as the Lipschitz-Killing curvature invariants and the Vitushkin
variations (which include the local density of a germ).


title: Quantum Fokker-Planck-Kramers equation and entropy production

abstract:
  We use a canonical quantization procedure to set up a quantum
Fokker-Planck-Kramers equation that accounts for quantum dissipation in a
thermal environment. The dissipation term is chosen to ensure that the
thermodynamic equilibrium is described by the Gibbs state. An expression for
the quantum entropy production is also provided which properly describes
quantum systems in a nonequilibrium stationary state. The time-dependent
solution is given for a quantum harmonic oscillator in contact with a heat
bath. We also obtain the stationary solution for a system of two coupled
harmonic oscillators in contact with reservoirs at distinct temperatures, from
which we obtain the entropy production and the quantum thermal conductance.


title:
Interpreting the cosmic far-infrared background anisotropies using a gas
  regulator model

abstract:
  Cosmic far-infrared background (CFIRB) is a powerful probe of the history of
star formation rate (SFR) and the connection between baryons and dark matter
across cosmic time. In this work, we explore to which extent the CFIRB
anisotropies can be reproduced by a simple physical framework for galaxy
evolution, the gas regulator (bathtub) model. This model is based on continuity
equations for gas, stars, and metals, taking into account cosmic gas accretion,
star formation, and gas ejection. We model the large-scale galaxy bias and
small-scale shot noise self-consistently, and we constrain our model using the
CFIRB power spectra measured by Planck. Because of the simplicity of the
physical model, the goodness of fit is limited. We compare our model
predictions with the observed correlation between CFIRB and gravitational
lensing, bolometric infrared luminosity functions, and submillimetre source
counts. The strong clustering of CFIRB indicates a large galaxy bias, which
corresponds to haloes of mass $10^{12.5} M_\odot$ at z=2, higher than the mass
associated with the peak of the star formation efficiency. We also find that
the far-infrared luminosities of haloes above $10^{12} M_\odot$ are higher than
the expectation from the SFR observed in ultraviolet and optical surveys.


title:
Screen Content Image Segmentation Using Robust Regression and Sparse
  Decomposition

abstract:
  This paper considers how to separate text and/or graphics from smooth
background in screen content and mixed document images and proposes two
approaches to perform this segmentation task. The proposed methods make use of
the fact that the background in each block is usually smoothly varying and can
be modeled well by a linear combination of a few smoothly varying basis
functions, while the foreground text and graphics create sharp discontinuity.
The algorithms separate the background and foreground pixels by trying to fit
background pixel values in the block into a smooth function using two different
schemes. One is based on robust regression, where the inlier pixels will be
considered as background, while remaining outlier pixels will be considered
foreground. The second approach uses a sparse decomposition framework where the
background and foreground layers are modeled with a smooth and sparse
components respectively. These algorithms have been tested on images extracted
from HEVC standard test sequences for screen content coding, and are shown to
have superior performance over previous approaches. The proposed methods can be
used in different applications such as text extraction, separate coding of
background and foreground for compression of screen content, and medical image
segmentation.


title: On the non-uniqueness of the instantaneous frequency

abstract:
  In this article, we investigate the debated Instantaneous Frequency (IF)
topic. Here, we show that IF is non-unique inherently. We explain how this
non-uniqueness can be quantified and explained from a mathematical perspective.
The non-uniqueness of the IF can also be observed if different methods of
adaptive signal processing are used. We will also show that even if we know the
physical origin of an oscillatory signal, e.g. linear second order ordinary
differential equation, the non-uniqueness is still present. All in all, we will
end up with the conclusion that, without any a priori assumption about the
relationship of the envelope and phase function of an oscillatory signal, there
is not any preferred neither best representation of the IF of such oscillatory
signal.


title:
Formal Requirement Elicitation and Debugging for Testing and
  Verification of Cyber-Physical Systems

abstract:
  A framework for the elicitation and debugging of formal specifications for
Cyber-Physical Systems is presented. The elicitation of specifications is
handled through a graphical interface. Two debugging algorithms are presented.
The first checks for erroneous or incomplete temporal logic specifications
without considering the system. The second can be utilized for the analysis of
reactive requirements with respect to system test traces. The specification
debugging framework is applied on a number of formal specifications collected
through a user study. The user study establishes that requirement errors are
common and that the debugging framework can resolve many insidious
specification errors.


title:
Spin accumulation in asymmetric topological insulator thin films in out
  of plane magnetic fields

abstract:
  In this work we study the spin accumulation due to an in-plane electric field
in an asymmetric topological insulator (TI) thin film system with an out of
plane magnetic field and an in-plane magnetization. A TI thin film differs from
the more typically studied thick TI system in that the former has both a top
and a bottom surface where the states localized at both surfaces can couple to
each other due to the finite thickness. In typical spin torque experiments on
TI thin film systems, the top and bottom surfaces of the film are asymmetric as
the former is in contact with a ferromagnetic layer while the latter is
adjacent to a non magnetic substrate. This may lead to differing (i) potentials
and (ii) magnetization strengths experienced by the top and bottom surface
states. We show, via Kubo formula calculations, that each of these two effects
can lead to in-plane spin accumulation perpendicular to the magnetization
direction which are otherwise absent in a top-bottom symmetric TI thin film
system. This spin accumulation results from the breaking of the antisymmetry of
the spin accumulation around the zero magnetic field equal energy contours.


title:
On the Misalignment between Chromospheric Features and the Magnetic
  Field on the Sun

abstract:
  Observations of the upper chromosphere shows an enormous amount of intricate
fine structure. Much of this comes in the form of linear features which are
most often assumed to be well aligned with the direction of the magnetic field
in the low plasma beta regime thought to dominate the upper chromosphere. We
use advanced radiative MHD simulations including the effects of ion-neutral
interactions (using the generalized Ohm's law) in the partially ionized
chromosphere to show that the magnetic field is often not well aligned with
chromospheric features. This occurs where the ambipolar diffusion is large,
i.e., ions and neutral populations decouple as the ion-neutral collision
frequency drops allowing the field to slip through the neutral population,
currents perpendicular to the field are strong, and thermodynamic timescales
are longer than or similar to the those of ambipolar diffusion. We find this
often happens in dynamic spicule or fibril-like features at the top of the
chromosphere. This has important consequences for field extrapolation methods
which increasingly use such upper chromospheric features to help constrain the
chromospheric magnetic field: our results invalidate the underlying assumption
that these features are aligned with the field. In addition, our results cast
doubt on results from 1D hydrodynamic models, which assume that plasma remains
on the same field lines. Finally, our simulations show that ambipolar diffusion
significantly alters the amount of free energy available in the coronal part of
our simulated volume, which is likely to have consequences for studies of flare
initiation.


title:
Online Learning Schemes for Power Allocation in Energy Harvesting
  Communications

abstract:
  We consider the problem of power allocation over a time-varying channel with
unknown distribution in energy harvesting communication systems. In this
problem, the transmitter has to choose the transmit power based on the amount
of stored energy in its battery with the goal of maximizing the average rate
obtained over time. We model this problem as a Markov decision process (MDP)
with the transmitter as the agent, the battery status as the state, the
transmit power as the action and the rate obtained as the reward. The average
reward maximization problem over the MDP can be solved by a linear program (LP)
that uses the transition probabilities for the state-action pairs and their
reward values to choose a power allocation policy. Since the rewards associated
the state-action pairs are unknown, we propose two online learning algorithms:
UCLP and Epoch-UCLP that learn these rewards and adapt their policies along the
way. The UCLP algorithm solves the LP at each step to decide its current policy
using the upper confidence bounds on the rewards, while the Epoch-UCLP
algorithm divides the time into epochs, solves the LP only at the beginning of
the epochs and follows the obtained policy in that epoch. We prove that the
reward losses or regrets incurred by both these algorithms are upper bounded by
constants. Epoch-UCLP incurs a higher regret compared to UCLP, but reduces the
computational requirements substantially. We also show that the presented
algorithms work for online learning in cost minimization problems like the
packet scheduling with power-delay tradeoff with minor changes.


title:
Double-quantum spin-relaxation limits to coherence of near-surface
  nitrogen-vacancy centers

abstract:
  We probe the relaxation dynamics of the full three-level spin system of
near-surface nitrogen-vacancy (NV) centers in diamond to define a $T_{1}$
relaxation time that helps resolve the $T_{2} \leq 2T_{1}$ coherence limit of
the NV's subset qubit superpositions. We find that double-quantum spin
relaxation via electric field noise dominates $T_{1}$ of near-surface NVs at
low applied magnetic fields. Furthermore, we differentiate $1/f^{\alpha}$
spectra of electric and magnetic field noise using a novel noise-spectroscopy
technique, with broad applications in probing surface-induced decoherence at
material interfaces.


title: On a conjecture of Cheeger

abstract:
  This note details how a recent structure theorem for normal $1$-currents
proved by the first and third author allows to prove a conjecture of Cheeger
concerning the structure of Lipschitz differentiability spaces. More precisely,
we show that the push-forward of the measure from a Lipschitz differentiability
space under a chart is absolutely continuous with respect to Lebesgue measure.


title: A Photometrically Calibrated Benchmark For Monocular Visual Odometry

abstract:
  We present a dataset for evaluating the tracking accuracy of monocular visual
odometry and SLAM methods. It contains 50 real-world sequences comprising more
than 100 minutes of video, recorded across dozens of different environments --
ranging from narrow indoor corridors to wide outdoor scenes. All sequences
contain mostly exploring camera motion, starting and ending at the same
position. This allows to evaluate tracking accuracy via the accumulated drift
from start to end, without requiring ground truth for the full sequence. In
contrast to existing datasets, all sequences are photometrically calibrated. We
provide exposure times for each frame as reported by the sensor, the camera
response function, and dense lens attenuation factors. We also propose a novel,
simple approach to non-parametric vignette calibration, which requires minimal
set-up and is easy to reproduce. Finally, we thoroughly evaluate two existing
methods (ORB-SLAM and DSO) on the dataset, including an analysis of the effect
of image resolution, camera field of view, and the camera motion direction.


title: Action Recognition with Joint Attention on Multi-Level Deep Features

abstract:
  We propose a novel deep supervised neural network for the task of action
recognition in videos, which implicitly takes advantage of visual tracking and
shares the robustness of both deep Convolutional Neural Network (CNN) and
Recurrent Neural Network (RNN). In our method, a multi-branch model is proposed
to suppress noise from background jitters. Specifically, we firstly extract
multi-level deep features from deep CNNs and feed them into 3d-convolutional
network. After that we feed those feature cubes into our novel joint LSTM
module to predict labels and to generate attention regularization. We evaluate
our model on two challenging datasets: UCF101 and HMDB51. The results show that
our model achieves the state-of-art by only using convolutional features.


title: A Large deviation and an escape rate result for special semi-flows

abstract:
  In this paper we consider a smooth flow $(\Lambda,\Phi^t)$ builded from
suspending over a (non-invertible topologically mixing) subshift of finite
type, and we equip it with an equilibrium measure $\nu$ on $\Lambda.$ The two
main theorems are a large deviation and an escape rate result. The first
theorem gives an explicit formula for $X>0$ and $Y$ such that
$$\nu\left\{x\in\Lambda: \left|\int F\circ \Phi^s (x) ds-\int F
d\mu\right|>\epsilon\right\}\leq \exp(-Xt+\log t+Y)$$ for
$t\gg>1\gg\epsilon>0,$ where $F:\Lambda\to\mathbb{R}$ is smooth. The second
theorem gives an explicit lower bound for the asymptotic behaviour of the
escape rate of $\nu$ through a small hole.


title:
Coherent control using kinetic energy and the geometric phase of a
  conical intersection

abstract:
  Conical intersections (CI) between molecular potential energy surfaces with
non-vanishing non-adiabatic couplings generally occur in any molecule
consisting of at least three atoms. They play a fundamental role in describing
the molecular dynamics beyond the Born-Oppenheimer approximation and have been
used to understand a large variety of effects, from photofragmentation and
isomerization to more exotic applications such as exciton fission in
semiconductors. However, few studies have used the features of a CI as a tool
for coherent control. Here we demonstrate two modes of control around a conical
intersection. The first uses a continuous light field to control the population
on the two intersecting electronic states in the vicinity of a CI. The second
uses a pulsed light field to control wavepackets that are subjected to the
geometric phase shift in transit around a CI. This second technique is likely
to be useful for studying the role of nuclear dynamics in electronic coherence
phenomena.


title: Uncovering Locally Discriminative Structure for Feature Analysis

abstract:
  Manifold structure learning is often used to exploit geometric information
among data in semi-supervised feature learning algorithms. In this paper, we
find that local discriminative information is also of importance for
semi-supervised feature learning. We propose a method that utilizes both the
manifold structure of data and local discriminant information. Specifically, we
define a local clique for each data point. The k-Nearest Neighbors (kNN) is
used to determine the structural information within each clique. We then employ
a variant of Fisher criterion model to each clique for local discriminant
evaluation and sum all cliques as global integration into the framework. In
this way, local discriminant information is embedded. Labels are also utilized
to minimize distances between data from the same class. In addition, we use the
kernel method to extend our proposed model and facilitate feature learning in a
high-dimensional space after feature mapping. Experimental results show that
our method is superior to all other compared methods over a number of datasets.


title: Localized Sparsifying Preconditioner for Periodic Indefinite Systems

abstract:
  This paper introduces the localized sparsifying preconditioner for the
pseudospectral approximations of indefinite systems on periodic structures. The
work is built on top of the recently proposed sparsifying preconditioner with
two major modifications. First, the local potential information is utilized to
improve the accuracy of the preconditioner. Second, an FFT based method to
compute the local stencil is proposed to reduce the setup time of the
algorithm. Numerical results show that the iteration number of this improved
method grows only mildly as the problem size grows, which implies that solving
pseudospectral approximation systems is computationally as efficient as solving
sparse systems, up to a mildly growing factor.


title: Database-Backed Web Applications in the Wild: How Well Do They Work?

abstract:
  Most modern database-backed web applications are built upon Object Relational
Mapping (ORM) frameworks. While ORM frameworks ease application development by
abstracting persistent data as objects, such convenience often comes with a
performance cost. In this paper, we present CADO, a tool that analyzes the
application logic and its interaction with databases using the Ruby on Rails
ORM framework. CADO includes a static program analyzer, a profiler and a
synthetic data generator to extract and understand application's performance
characteristics. We used CADO to analyze the performance problems of 27
real-world open-source Rails applications, covering domains such as online
forums, e-commerce, project management, blogs, etc. Based on the results, we
uncovered a number of issues that lead to sub-optimal application performance,
ranging from issuing queries, how result sets are used, and physical design. We
suggest possible remedies for each issue, and highlight new research
opportunities that arise from them.


title: CPDY: Extending the Dolev-Yao Attacker with Physical-Layer Interactions

abstract:
  We propose extensions to the Dolev-Yao attacker model to make it suitable for
arguments about security of Cyber-Physical Systems. The Dolev-Yao attacker
model uses a set of rules to define potential actions by an attacker with
respect to messages (i.e. information) exchanged between parties during a
protocol execution. As the traditional Dolev-Yao model considers only
information (exchanged over a channel controlled by the attacker), the model
cannot directly be used to argue about the security of cyber-physical systems
where physical-layer interactions are possible. Our Dolev-Yao extension, called
cyber-physical Dolev-Yao (CPDY) attacker model, allows additional orthogonal
interaction channels between the parties. In particular, such orthogonal
channels can be used to model physical-layer mechanical, chemical, or
electrical interactions between components. In addition, we discuss the
inclusion of physical properties such as location or distance in the rule set.
We present an example set of additional rules for the Dolev-Yao attacker, using
those we are able to formally discover physical attacks that previously could
only be found by empirical methods or detailed physical process models.


title:
Closability of Quadratic Forms Associated to Invariant Probability
  Measures of SPDEs

abstract:
  By using the integration by parts formula of a Markov operator, the
closability of quadratic forms associated to the corresponding invariant
probability measure is proved. The general result is applied to the study of
semilinear SPDEs, infinite-dimensional stochastic Hamiltonian systems, and
semilinear SPDEs with delay.


title: Base-$b$ analogues of classic combinatorial objects

abstract:
  We study the properties of the base-$b$ binomial coefficient defined by Jiu
and the second author, introduced in the context of a digital binomial theorem.
After introducing a general summation formula, we derive base-$b$ analogues of
the Stirling numbers of the second kind, the Fibonacci numbers and the
classical exponential function.