title:
Spoofing Detection Goes Noisy: An Analysis of Synthetic Speech Detection
  in the Presence of Additive Noise

abstract:
  Automatic speaker verification (ASV) technology is recently finding its way
to end-user applications for secure access to personal data, smart services or
physical facilities. Similar to other biometric technologies, speaker
verification is vulnerable to spoofing attacks where an attacker masquerades as
a particular target speaker via impersonation, replay, text-to-speech (TTS) or
voice conversion (VC) techniques to gain illegitimate access to the system. We
focus on TTS and VC that represent the most flexible, high-end spoofing
attacks. Most of the prior studies on synthesized or converted speech detection
report their findings using high-quality clean recordings. Meanwhile, the
performance of spoofing detectors in the presence of additive noise, an
important consideration in practical ASV implementations, remains largely
unknown. To this end, we analyze the suitability of state-of-the-art synthetic
speech detectors under additive noise with a special focus on front-end
features. Our comparison includes eight acoustic feature sets, five related to
spectral magnitude and three to spectral phase information. Our extensive
experiments on ASVSpoof 2015 corpus reveal several important findings. Firstly,
all the countermeasures break down even at relatively high signal-to-noise
ratios (SNRs) and fail to generalize to noisy conditions. Secondly, speech
enhancement is not found helpful. Thirdly, GMM back-end generally outperforms
the more involved i-vector back-end. Fourthly, concerning the compared
features, the Mel-frequency cepstral coefficients (MFCCs) and subband spectral
centroid magnitude coefficients (SCMCs) perform the best on average though the
winner method depends on SNR and noise type. Finally, a study with two score
fusion strategies shows that combining different feature based systems improves
recognition accuracy for known and unknown attacks in both clean and noisy
conditions.


title: Universal fault-tolerant gates on concatenated stabilizer codes

abstract:
  It is an oft-cited fact that no quantum code can support a set of
fault-tolerant logical gates that is both universal and transversal. This no-go
theorem is generally responsible for the interest in alternative universality
constructions including magic state distillation. Widely overlooked, however,
is the possibility of non-transversal, yet still fault-tolerant, gates that
work directly on small quantum codes. Here we demonstrate precisely the
existence of such gates. In particular, we show how the limits of
non-transversality can be overcome by performing rounds of intermediate
error-correction to create logical gates on stabilizer codes that use no
ancillas other than those required for syndrome measurement. Moreover, the
logical gates we construct, the most prominent examples being Toffoli and
controlled-controlled-Z, often complete universal gate sets on their codes. We
detail such universal constructions for the smallest quantum codes, the 5-qubit
and 7-qubit codes, and then proceed to generalize the approach. One remarkable
result of this generalization is that any nondegenerate stabilizer code with a
complete set of fault-tolerant single-qubit Clifford gates has a universal set
of fault-tolerant gates. Another is the interaction of logical qubits across
different stabilizer codes, which, for instance, implies a broadly applicable
method of code switching.


title: On the Two-Dimensional Muskat Problem with Monotone Large Initial Data

abstract:
  We consider the evolution of two incompressible, immiscible fluids with
different densities in porous media, known as the Muskat problem [21], which in
two dimensions is analogous to the Hele-Shaw cell [26]. We establish, for a
class of large and monotone initial data, the global existence of weak
solutions. The proof is based on a local well-posedness result for the initial
data with certain specific asymptotics at spatial infinity and a new maximum
principle for the first derivative of the graph function.


title: A Copula Model for Non-Gaussian Multivariate Spatial Data

abstract:
  We propose a new copula model for replicated multivariate spatial data.
Unlike classical models that assume multivariate normality of the data, the
proposed copula is based on the assumption that some factors exist that affect
the joint spatial dependence of all measurements of each variable as well as
the joint dependence among these variables. The model is parameterized in terms
of a cross-covariance function that may be chosen from the many models proposed
in the literature. In addition, there are additive factors in the model that
allow tail dependence and reflection asymmetry of each variable measured at
different locations and of different variables to be modeled. The proposed
approach can therefore be seen as an extension of the linear model of
coregionalization widely used for modeling multivariate spatial data. The
likelihood of the model can be obtained in a simple form and therefore the
likelihood estimation is quite fast. The model is not restricted to the set of
data locations, and using the estimated copula, spatial data can be
interpolated at locations where values of variables are unknown. We apply the
proposed model to temperature and pressure data and compare its performance
with the performance of a popular model from multivariate geostatistics.


title:
Key role of lattice symmetry in the metal-insulator transition of NdNiO3
  films

abstract:
  Bulk NdNiO3 exhibits a metal-to-insulator transition (MIT) as the temperature
is lowered that is also seen in tensile strained films. In contrast, films that
are under a large compressive strain typically remain metallic at all
temperatures. To clarify the microscopic origins of this behavior, we use
position averaged convergent beam electron diffraction in scanning transmission
electron microscopy to characterize strained NdNiO3 films both above and below
the MIT temperature. We show that a symmetry lowering structural change takes
place in case of the tensile strained film, which undergoes an MIT, but is
absent in the compressively strained film. Using space group symmetry
arguments, we show that these results support the bond length
disproportionation model of the MIT in the rare-earth nickelates. Furthermore,
the results provide insights into the non-Fermi liquid phase that is observed
in films for which the MIT is absent.


title: Fundamentals of p-values: Introduction

abstract:
  We explain the concept of p-values presupposing only rudimentary probability
theory. We also use the occasion to introduce the notion of p-function, so that
p-values are values of a p-function. The explanation is restricted to the
discrete case with no outcomes of zero probability. We are going to address the
general case elsewhere.


title: Magnetic Resonance Force Detection using a Membrane Resonator

abstract:
  The availability of compact, low-cost magnetic resonance imaging instruments
would further broaden the substantial impact of this technology. We report
highly sensitive detection of magnetic resonance using low-stress silicon
nitride (SiN$_x$) membranes. We use these membranes as low-loss, high-frequency
mechanical oscillators and find they are able to mechanically detect
spin-dependent forces with high sensitivity enabling ultrasensitive magnetic
resonance detection. The high force detection sensitivity stems from their high
mechanical quality factor $Q\sim10^6$ combined with the low mass of the
resonator. We use this excellent mechanical force sensitivity to detect the
electron spin magnetic resonance using a SiN$_x$ membrane as a force detector.
The demonstrated force sensitivity at 300 K is 4 fN/$\sqrt{\mathrm{Hz}}$,
indicating a potential low temperature (4 K) sensitivity of 25
aN/$\sqrt{\mathrm{Hz}}$. Given their sensitivity, robust construction, large
surface area and low cost, SiN$_x$ membranes can potentially serve as the
central component of a compact room-temperature ESR and NMR instrument that has
superior spatial resolution to conventional approaches.


title:
Fractal dimensions of graph of Weierstrass-type function and local
  H\"older exponent spectra

abstract:
  We study several fractal properties of the Weierstrass-type function \[
W(x)=\sum_{n=0} ^\infty \lambda (x) \lambda(\tau x) \cdots \lambda (\tau
^{n-1}x)\, g(\tau ^n x), \] where $\tau :[0,1)\to[0,1)$ is a cookie cutter map
with possibly fractal repeller, and $\lambda$ and $g$ are functions with proper
regularity. In the first part, we determine the box dimension of the graph of
$W$ and Hausdorff dimension of its randomised version. In the second part, the
Housdorff spectrum of the local H\"older exponent is characterised in terms of
thermodynamic formalisms. Furthermore, in the randomised case, a novel formula
for the lifted Hausdorff spectrum on the graph is provided.


title: Multidimensional stability of large-amplitude Navier-Stokes shocks

abstract:
  Extending results of Humpherys-Lyng-Zumbrun in the one-dimensional case, we
use a combination of asymptotic ODE estimates and numerical Evans-function
computations to examine the multidimensional stability of planar Navier--Stokes
shocks across the full range of shock amplitudes, including the
infinite-amplitude limit, for monatomic or diatomic ideal gas equations of
state and viscosity and heat conduction coefficients $\mu$, $\mu +\eta$, and
$\nu=\kappa/c_v$ in the physical ratios predicted by statistical mechanics,
with Mach number $M>1.035$. Our results indicate unconditional stability within
the parameter range considered; this agrees with the results of Erpenbeck and
Majda for the corresponding inviscid case of Euler shocks. Notably, this study
includes the first successful numerical computation of an Evans function
associated with the multidimensional stability of a viscous shock wave. The
methods introduced may be used in principle to decide stability for any
$\gamma$-law gas, $\gamma>1$, and arbitrary $\mu>|\eta|\ge 0$, $\nu>0$ or,
indeed, for shocks of much more general models and equations, including in
particular viscoelasticity, combustion, and magnetohydrodynamics (MHD).


title:
Asymptotically Optimal Distributed Channel Allocation: a Competitive
  Game-Theoretic Approach

abstract:
  In this paper we consider the problem of distributed channel allocation in
large networks under the frequency-selective interference channel. Performance
is measured by the weighted sum of achievable rates. First we present a natural
non-cooperative game theoretic formulation for this problem. It is shown that,
when interference is sufficiently strong, this game has a pure price of anarchy
approaching infinity with high probability, and there is an asymptotically
increasing number of equilibria with the worst performance. Then we propose a
novel non-cooperative M Frequency-Selective Interference Game (M-FSIG), where
users limit their utility such that it is greater than zero only for their M
best channels, and equal for them. We show that the M-FSIG exhibits, with high
probability, an increasing number of optimal pure Nash equilibria and no bad
equilibria. Consequently, the pure price of anarchy converges to one in
probability in any interference regime. In order to exploit these results
algorithmically we propose a modified Fictitious Play algorithm that can be
implemented distributedly. We carry out simulations that show its fast
convergence to the proven pure Nash equilibria.


title:
Theory of Finite Size Effects for Electronic Quantum Monte Carlo
  Calculations of Liquids and Solids

abstract:
  Concentrating on zero temperature Quantum Monte Carlo calculations of
electronic systems, we give a general description of the theory of finite size
extrapolations of energies to the thermodynamic limit based on one and two-body
correlation functions. We introduce new effective procedures, such as using the
potential and wavefunction split-up into long and short range functions to
simplify the method and we discuss how to treat backflow wavefunctions. Then we
explicitly test the accuracy of our method to correct finite size errors on
example hydrogen and helium many-body systems and show that the finite size
bias can be drastically reduced for even small systems.


title: Template Adaptation for Face Verification and Identification

abstract:
  Face recognition performance evaluation has traditionally focused on
one-to-one verification, popularized by the Labeled Faces in the Wild dataset
for imagery and the YouTubeFaces dataset for videos. In contrast, the newly
released IJB-A face recognition dataset unifies evaluation of one-to-many face
identification with one-to-one face verification over templates, or sets of
imagery and videos for a subject. In this paper, we study the problem of
template adaptation, a form of transfer learning to the set of media in a
template. Extensive performance evaluations on IJB-A show a surprising result,
that perhaps the simplest method of template adaptation, combining deep
convolutional network features with template specific linear SVMs, outperforms
the state-of-the-art by a wide margin. We study the effects of template size,
negative set construction and classifier fusion on performance, then compare
template adaptation to convolutional networks with metric learning, 2D and 3D
alignment. Our unexpected conclusion is that these other methods, when combined
with template adaptation, all achieve nearly the same top performance on IJB-A
for template-based face verification and identification.


title: On the computation of the straight lines contained in a rational surface

abstract:
  In this paper we present an algorithm to compute the (real and complex)
straight lines contained in a rational surface, defined by a rational
parameterization. The algorithm relies on the well-known theorem of
Differential Geometry that characterizes real straight lines contained in a
surface as curves that are simultaneously asymptotic lines, and geodesics. We
also report on an implementation carried out in Maple 18, and we compare the
behavior of our algorithm with two brute-force approaches.


title:
The second largest eigenvalue and vertex-connectivity of regular
  multigraphs

abstract:
  Let $\mu_2(G)$ be the second smallest Laplacian eigenvalue of a graph $G$.
The vertex connectivity of $G$, written $\kappa(G)$, is the minimum size of a
vertex set $S$ such that $G-S$ is disconnected. Fiedler proved that $\mu_2(G)
\le \kappa(G)$ for a non-complete simple graph $G$; for this reason $\mu_2(G)$
is called the "algebraic connectivity" of $G$. We extend his result to
multigraphs. For a pair of vertices $u$ and $v$, let $m(u,v)$ be the number of
edges with endpoints $u$ and $v$. For a vertex $v$, let $m(v)=\max_{u \in N(v)}
m(v,u)$, where $N(v)$ is the set of neighbors of $v$, and let $m(G)=\max_{v \in
V(G)} m(v)$. We prove that for any multigraph $G$ whose underlying graph is not
a complete graph, $\mu_2(G) \le \kappa(G) m(G)$.
  We also prove that for any $d$-regular multigraph $G$ whose underlying graph
is not the complete graph with 2 vertices, if $\mu_2(G) > \frac d4$, then $G$
is 2-connected. For $t\ge2$ and infinitely many $d$, we construct $d$-regular
multigraphs $H$ with $\mu_2(H)=d$, $\kappa(H)=t$, and $m(H)=\frac dt$. These
graphs show that the inequality $\mu_2(G) \le \kappa(G) m(G)$ is sharp. In
addition, we prove that if $G$ is a $d$-regular multigraph whose underlying
graph is not a complete graph, then $\mu_2(G) \le d$; equality holds for the
graphs in the construction.


title: Critical radius and temperature for buckling in graphene

abstract:
  In this work, we find an analytical flat-membrane solution to the saddle
point equations, derived by Guinea et al. [Phys. Rev. B 89, 125428 (2014)], for
the case of a suspended graphene membrane of circular shape. We also find how
different buckled membrane solutions bifurcate from the flat membrane at
critical temperatures and membrane radii. The saddle point equations take into
account electron-phonon coupling and this coupling provides a residual stress
even for a flat graphene layer. Below a critical temperature (which is
exceedingly high for an infinite layer) or above a critical size that depend on
boundary conditions, different buckling modes that may be the germ of rippling
appear. Our results provide the opportunity to develop new feasible experiments
dealing with buckling in small suspended graphene membranes that could verify
them. These experiments may also be used to fit the phonon-electron coupling
constant or the bending energy.


title: Quantum Dynamics in Phase Space using Projected von Neumann Bases

abstract:
  We describe the mathematical underpinnings of the biorthogonal von Neumann
method for quantum mechanical simulations (PvB). In particular, we present a
detailed discussion of the important issue of non-orthogonal projection onto
subspaces of biorthogonal bases, and how this differs from orthogonal
projection. We present various representations of the Schr\"odinger equation in
the reduced basis and discuss their relative merits. We conclude with
illustrative examples and a discussion of the outlook and challenges ahead for
the PvB representation.


title:
Quantum Dynamics in Phase space using the Biorthogonal von Neumann
  bases: Algorithmic Considerations

abstract:
  The von Neumann lattice refers to a discrete basis of Gaussians located on a
lattice in phase space. It provides an attractive approach for solving quantum
mechanical problems, allowing the pruning of tensor-product basis sets using
phase space considerations. In a series of recent articles Shimshovitz et al.
[Phys. Rev. Lett. 109 7 (2012)], Takemoto et al. [Journal of Chemical Physics
137 1 (2012)] Machnes et al. [Journal of Chemical Physics, accepted (2016)]),
we have introduced two key new elements into the method: a formalism for
converging the basis and for efficient pruning by use of the biorthogonal
basis. In this paper we review the key components of the theory and then
present new, efficient and parallelizable iterative algorithms for solving the
time-independent and time-dependent Schr\"odinger equations. The algorithms
dynamically determine the active reduced basis iteratively without resorting to
classical analogs. These algorithmic developments, combined with the previous
formal developments, allow quantum dynamics to be performed directly and
economically in phase space. We provide two illustrative examples: double-well
tunneling and double ionization of helium.


title: Entanglement distillation from Greenberger-Horne-Zeilinger shares

abstract:
  We study the problem of converting a product of Greenberger-Horne-Zeilinger
(GHZ) states shared by subsets of several parties in an arbitrary way into GHZ
states shared by every party. Our result is that if SLOCC transformations are
allowed, then the best asymptotic rate is the minimum of bipartite log-ranks of
the initial state. This generalizes a result by Strassen on the asymptotic
subrank of the matrix multiplication tensor.


title:
On Paley-type and Hausdorff-Young-Paley-type inequalities for Jacobi
  expansions

abstract:
  We obtain Paley-type and Hausdorff-Young-Paley-type inequalities for Jacobi
expansions.


title:
Neutral Current Coherent Cross Sections -- Implications on Gaseous
  Spherical TPC's for detecting SN and Earth neutrinos

abstract:
  The detection of galactic supernova (SN) neutrinos represents one of the
future frontiers of low-energy neutrino physics and astrophysics. The neutron
coherence of neutral currents (NC) allows quite large cross sections in the
case of neutron rich targets, which can be exploited in detecting earth and sky
neutrinos by measuring nuclear recoils. They are relatively cheap and easy to
maintain. The relevant NC cross sections are not dependent on flavor
conversions and, thus, their measurement will provide useful information about
the neutrino source. In particular they will yield information about the
primary neutrino fluxes and perhaps about the spectrum after flavor conversions
in neutrino sphere.They might also provide some clues about the neutrino mass
hierarchy. The advantages of large gaseous low threshold and high resolution
detectors with time projection counters (TPC) are discussed.


title: Effective action approach to wave propagation in scalar QED plasmas

abstract:
  A relativistic quantum field theory with nontrivial background fields is
developed and applied to study waves in plasmas. The effective action of the
electromagnetic 4-potential is calculated ab initio from the standard action of
scalar QED using path integrals. The resultant effective action is gauge
invariant and contains nonlocal interactions, from which gauge bosons acquire
masses without breaking the local gauge symmetry. To demonstrate how the
general theory can be applied, we study a cold unmagnetized plasma and a cold
uniformly magnetized plasma. Using these two examples, we show that all linear
waves well-known in classical plasma physics can be recovered from relativistic
quantum results when taking the classical limit. In the opposite limit,
classical wave dispersion relations are modified substantially. In unmagnetized
plasmas, longitudinal waves propagate with nonzero group velocities even when
plasmas are cold. In magnetized plasmas, anharmonically spaced Bernstein waves
persist even when plasmas are cold. These waves account for cyclotron
absorption features observed in spectra of X-ray pulsars. Moreover, cutoff
frequencies of the two non-degenerate electromagnetic waves are redshifted by
different amounts. These corrections need to be taken into account in order to
correctly interpret diagnostic results in laser plasma experiments.


title:
Temporally Robust Global Motion Compensation by Keypoint-based
  Congealing

abstract:
  Global motion compensation (GMC) removes the impact of camera motion and
creates a video in which the background appears static over the progression of
time. Various vision problems, such as human activity recognition, background
reconstruction, and multi-object tracking can benefit from GMC. Existing GMC
algorithms rely on sequentially processing consecutive frames, by estimating
the transformation mapping the two frames, and obtaining a composite
transformation to a global motion compensated coordinate. Sequential GMC
suffers from temporal drift of frames from the accurate global coordinate, due
to either error accumulation or sporadic failures of motion estimation at a few
frames. We propose a temporally robust global motion compensation (TRGMC)
algorithm which performs accurate and stable GMC, despite complicated and
long-term camera motion. TRGMC densely connects pairs of frames, by matching
local keypoints of each frame. A joint alignment of these frames is formulated
as a novel keypoint-based congealing problem, where the transformation of each
frame is updated iteratively, such that the spatial coordinates for the start
and end points of matched keypoints are identical. Experimental results
demonstrate that TRGMC has superior performance in a wide range of scenarios.


title: Record Dynamics in the Parking Lot Model

abstract:
  We present an analytical and numerical study of the parking lot model (PLM)
of granular relaxation and make a connection to the aging dynamics of dense
colloids. As we argue, the PLM is a Kinetically Constrained Model which
features astronomically large equilibration times and displays a characteristic
aging behavior on all observable time scales. The density of parked cars
displays quasi-equilibrium Gaussian fluctuations interspersed by increasingly
rare intermittent events, quakes, which can lead to an increase of the density
to new record values. Defining active clusters as the shortest domains of
parked cars which must be re-arranged to allow further insertions, we find that
their typical length grows logarithmically with time for low enough
temperatures and show how the number of active clusters on average gradually
decreases as the system approaches equilibrium. We further characterize the
aging process in terms of the statistics of the record sized fluctuations in
the interstitial free volume which lead to quakes and show that quakes are
uncorrelated and that they can be approximately described as a Poisson process
in logarithmic time.


title: Structural Transitions at Ionic Liquids Interfaces

abstract:
  Recent advances in experimental and computational techniques have allowed for
an accurate description of the adsorption of ionic liquids on metallic
electrodes. It is now well established that they adopt a multi-layered
structure, and that the composition of the layers changes with the potential of
the electrode. In some cases, potential-driven ordering transitions in the
first adsorbed layer have been observed in experiments probing the interface on
the molecular scale or by molecular simulations. This perspective gives an
overview of the current understanding of such transitions and of their
potential impact on the physical and (electro)chemical processes at the
interface. In particular, peaks in the differential capacitance, slow dynamics
at the interface and changes in the reactivity have been reported in
electrochemical studies. Interfaces between ionic liquids and metallic
electrodes are also highly relevant for their friction properties, the
voltage-dependence of which opens the way to exciting applications.


title:
Performance Analysis and Optimization of a Hybrid Distributed Reverse
  Time Migration Application

abstract:
  Applications to process seismic data employ scalable parallel systems to
produce timely results. To fully exploit emerging processor architectures,
application will need to employ threaded parallelism within a node and message
passing across nodes. Today, MPI+OpenMP is the preferred programming model for
this task. However, tuning hybrid programs for clusters is difficult.
Performance tools can help users identify bottlenecks and uncover opportunities
for improvement. This poster describes our experiences of applying Rice
University's HPCToolkit and hardware performance counters to gain insight into
an MPI+OpenMP code that performs Reverse Time Migration (RTM) on a cluster of
multicore processors. The tools provided us with insights into the
effectiveness of the domain decomposition strategy, the use of threaded
parallelism, and functional unit utilization in individual cores. By applying
insights obtained from the tools, we were able to improve the performance of
the RTM code by roughly 30 percent.


title: Laplacian Eigenmaps from Sparse, Noisy Similarity Measurements

abstract:
  Manifold learning and dimensionality reduction techniques are ubiquitous in
science and engineering, but can be computationally expensive procedures when
applied to large data sets or when similarities are expensive to compute. To
date, little work has been done to investigate the tradeoff between
computational resources and the quality of learned representations. We present
both theoretical and experimental explorations of this question. In particular,
we consider Laplacian eigenmaps embeddings based on a kernel matrix, and
explore how the embeddings behave when this kernel matrix is corrupted by
occlusion and noise. Our main theoretical result shows that under modest noise
and occlusion assumptions, we can (with high probability) recover a good
approximation to the Laplacian eigenmaps embedding based on the uncorrupted
kernel matrix. Our results also show how regularization can aid this
approximation. Experimentally, we explore the effects of noise and occlusion on
Laplacian eigenmaps embeddings of two real-world data sets, one from speech
processing and one from neuroscience, as well as a synthetic data set.


title:
Bounded Solutions to nonlinear problems involving the fractional
  laplacian depending on parameters

abstract:
  The main goal of this paper is the study of two kinds of nonlinear problems
depending on parameters in unbounded domains. Using a nonstandard variational
approach, we first prove the existence of bounded solutions for nonlinear
eigenvalue problems involving the fractional Laplace operator and
nonlinearities that have subcritical growth. In the second part, based on a
variational principle of Ricceri [16], we study a fractional nonlinear problem
with two parameters and prove the existence of multiple solutions.


title: Dirac node lines in pure alkali earth metals

abstract:
  Beryllium is a simple alkali earth metal, but has been the target of
intensive studies for decades because of its unusual electron behaviors at
surfaces. Puzzling aspects include (i) severe deviations from the description
of the nearly free electron picture, (ii) anomalously large electron-phonon
coupling effect, and (iii) giant Friedal oscillations. The underlying origins
for such anomalous surface electron behaviors have been under active debate,
but with no consensus. Here, by means of first-principle calculations, we
discover that this pure metal system, surprisingly, harbors the Dirac node line
(DNL) that in turn helps to rationalize many of the existing puzzles. The DNL
is featured by a closed line consisting of linear band crossings and its
induced topological surface band agrees well with previous photoemission
spectroscopy observation on Be (0001) surface. We further reveal that each of
the elemental alakali earth metals of Mg, Ca, and Sr also harbors the DNL, and
speculate that the fascinating topological property of DNL might naturally
exist in other elemental metals as well.


title:
Alice-Bob systems, $P_s$-$T_d$-$C$ principles and multi-soliton
  solutions

abstract:
  To describe two-place physical problems, many possible models named Alice-Bob
(AB) systems are proposed. To find and to solve these systems, the Parity (P),
time reversal (T), charge conjugation (C), shifted-parity ($P_s$, parity with a
shift), delayed time reversal ($T_d$, time reversal with a delay) and their
possible combinations such as PT, PC, $P_sC$, $P_sT_d$ and $P_sT_dC$ etc. can
be successively used. Especially, some special types of $P_s$-$T_d$-$C$ group
invariant multi-soliton solutions for the KdV-KP-Toda type, mKdV-sG type, NLS
type and discrete $H_1$ type AB systems are explicitly constructed.


title: On a compressible non-isothermal model for nematic liquid crystals

abstract:
  We prove the existence of a weak solution to a non-isothermal compressible
model for nematic liquid crystals. An initial-boundary value problem is studied
in a bounded domain with large data. The existence of a global weak solution is
established through a three-level approximation, energy estimates, and weak
convergence for the adiabatic exponent \gamma>3/2.


title: Pufferfish Privacy Mechanisms for Correlated Data

abstract:
  Many modern databases include personal and sensitive correlated data, such as
private information on users connected together in a social network, and
measurements of physical activity of single subjects across time. However,
differential privacy, the current gold standard in data privacy, does not
adequately address privacy issues in this kind of data.
  This work looks at a recent generalization of differential privacy, called
Pufferfish, that can be used to address privacy in correlated data. The main
challenge in applying Pufferfish is a lack of suitable mechanisms. We provide
the first mechanism -- the Wasserstein Mechanism -- which applies to any
general Pufferfish framework. Since this mechanism may be computationally
inefficient, we provide an additional mechanism that applies to some practical
cases such as physical activity measurements across time, and is
computationally efficient. Our experimental evaluations indicate that this
mechanism provides privacy and utility for synthetic as well as real data in
two separate domains.


title: Avoiding zero-sum subsequences of prescribed length over the integers

abstract:
  Let $t$ and $k$ be a positive integers, and let $I_k=\{i\in \mathbb{Z}:\;
-k\leq i\leq k\}$. Let $\mathsf{s}'_t(I_k)$ be the smallest positive integer
$\ell$ such that every zero-sum sequence $S$ over $I_k$ of length $|S|\ge \ell$
contains a zero-sum subsequence of length $t$. If no such $\ell$ exists, then
let $\mathsf{s}'_t(I_k)=\infty$.
  In this paper, we prove that $\mathsf{s}'_t(I_k)$ is finite if and only if
every integer in $[1,D(I_k)]$ divides $t$, where $D(I_k)=\max\{2,2k-1\}$ is the
Davenport constant of $I_k$. Moreover, we prove that if $\mathsf{s}'_t(I_k)$ is
finite, then $t+k(k-1)\leq \mathsf{s}'_t(I_k)\leq t+(2k-2)(2k-3)$. We also show
that $\mathsf{s}'_t(I_k)=t+k(k-1)$ holds for $k\leq 3$ and conjecture that this
equality holds for any $k\geq1$.


title:
A sub-1-volt analog metal oxide memristive-based synaptic device for
  energy-efficient spike-based computing systems

abstract:
  Nanoscale metal oxide memristors have potential in the development of
brain-inspired computing systems that are scalable and efficient1-3. In such
systems, memristors represent the native electronic analogues of the biological
synapses. However, the characteristics of the existing memristors do not fully
support the key requirements of synaptic connections: high density, adjustable
weight, and low energy operation. Here we show a bilayer memristor that is
forming-free, low-voltage (~|0.8V|), energy-efficient (full On/Off switching at
~2pJ), and reliable. Furthermore, pulse measurements reveal the analog nature
of the memristive device, that is it can be directly programmed to intermediate
resistance states. Leveraging this finding, we demonstrate
spike-timing-dependent plasticity (STDP), a spike-based Hebbian learning rule4.
In those experiments, the memristor exhibits a marked change in the normalized
synaptic strength (>30 times) when the pre- and post-synaptic neural spikes
overlap. This demonstration is an important step towards the physical
construction of high density and high connectivity neural networks.


title: On Learning High Dimensional Structured Single Index Models

abstract:
  Single Index Models (SIMs) are simple yet flexible semi-parametric models for
machine learning, where the response variable is modeled as a monotonic
function of a linear combination of features. Estimation in this context
requires learning both the feature weights and the nonlinear function that
relates features to observations. While methods have been described to learn
SIMs in the low dimensional regime, a method that can efficiently learn SIMs in
high dimensions, and under general structural assumptions, has not been
forthcoming. In this paper, we propose computationally efficient algorithms for
SIM inference in high dimensions with structural constraints. Our general
approach specializes to sparsity, group sparsity, and low-rank assumptions
among others. Experiments show that the proposed method enjoys superior
predictive performance when compared to generalized linear models, and achieves
results comparable to or better than single layer feedforward neural networks
with significantly less computational cost.


title: Symmetry in Sphere-based Assembly Configuration Spaces

abstract:
  Many remarkably robust, rapid and spontaneous self-assembly phenomena in
nature can be modeled geometrically starting from a collection of rigid bunches
of spheres. This paper highlights the role of symmetry in sphere-based assembly
processes. Since spheres within bunches could be identical and bunches could be
identical as well, the underlying symmetry groups could be of large order that
grows with the number of participating spheres and bunches. Thus, understanding
symmetries and associated isomorphism classes of microstates correspond to
various types of macrostates can significantly reduce the complexity of
computing entropy and free energy, as well as paths and kinetics, in high
dimensional configuration spaces. In addition, a precise understanding of
symmetries is crucial for giving provable guarantees of algorithmic accuracy
and efficiency in such computations. In particular, this may aid in predicting
crucial assembly-driving interactions.
  This is a primarily expository paper that develops a novel, original
framework for dealing with symmetries in configuration spaces of assembling
spheres with the following goals. (1) We give new, formal definitions of
various concepts relevant to sphere-based assembly that occur in previous work,
and in turn, formal definitions of their relevant symmetry groups leading to
the main theorem concerning their symmetries. These previously developed
concepts include, for example, (a) assembly configuration spaces, (b)
stratification of assembly configuration space into regions defined by active
constraint graphs, (c) paths through the configurational regions, and (d)
coarse assembly pathways. (2) We demonstrate the new symmetry concepts to
compute sizes and numbers of orbits in two example settings appearing in
previous work. (3) We give formal statements of a variety of open problems and
challenges using the new conceptual definitions.


title: Minnaert resonances for acoustic waves in bubbly media

abstract:
  Through the application of layer potential techniques and Gohberg-Sigal
theory we derive an original formula for the Minnaert resonance frequencies of
arbitrarily shaped bubbles. We also provide a mathematical justification for
the monopole approximation of scattering of acoustic waves by bubbles at their
Minnaert resonant frequency. Our results are complemented by several numerical
examples which serve to validate our formula in two dimensions.


title: On roots of unity in orbits of rational functions

abstract:
  In this paper we characterise univariate rational functions over a number
field $\K$ having infinitely many points in the cyclotomic closure $\K^c$ for
which the orbit contains a root of unity. Our results are similar to previous
results of Dvornicich and Zannier describing all polynomials having infinitely
many preperiodic points in $\K^c$.


title: An efficient Exact-PGA algorithm for constant curvature manifolds

abstract:
  Manifold-valued datasets are widely encountered in many computer vision
tasks. A non-linear analog of the PCA, called the Principal Geodesic Analysis
(PGA) suited for data lying on Riemannian manifolds was reported in literature
a decade ago. Since the objective function in PGA is highly non-linear and hard
to solve efficiently in general, researchers have proposed a linear
approximation. Though this linear approximation is easy to compute, it lacks
accuracy especially when the data exhibits a large variance. Recently, an
alternative called exact PGA was proposed which tries to solve the optimization
without any linearization. For general Riemannian manifolds, though it gives
better accuracy than the original (linearized) PGA, for data that exhibit large
variance, the optimization is not computationally efficient. In this paper, we
propose an efficient exact PGA for constant curvature Riemannian manifolds
(CCM-EPGA). CCM-EPGA differs significantly from existing PGA algorithms in two
aspects, (i) the distance between a given manifold-valued data point and the
principal submanifold is computed analytically and thus no optimization is
required as in existing methods. (ii) Unlike the existing PGA algorithms, the
descent into codimension-1 submanifolds does not require any optimization but
is accomplished through the use of the Rimeannian inverse Exponential map and
the parallel transport operations. We present theoretical and experimental
results for constant curvature Riemannian manifolds depicting favorable
performance of CCM-EPGA compared to existing PGA algorithms. We also present
data reconstruction from principal components and directions which has not been
presented in literature in this setting.


title: Dark solitons in the Lugiato-Lefever equation with normal dispersion

abstract:
  The regions of existence and stability of dark solitons in the
Lugiato-Lefever model with normal chromatic dispersion are described. These
localized states are shown to be organized in a bifurcation structure known as
collapsed snaking implying the presence of a region in parameter space with a
finite multiplicity of dark solitons. For some parameter values dynamical
instabilities are responsible for the appearance of oscillations and temporal
chaos. The importance of the results for understanding frequency comb
generation in microresonators is emphasized.


title: Differential equations associated with Legendre polynomials

abstract:
  In this paper, we study non-linear differential equations associated with
Legendre polynomials and their applications. From our study of non- linear
differential equations, we derive some new and explicit identities for Legendre
polynomials.


title: Binomial Difference Ideals

abstract:
  In this paper, binomial difference ideals are studied. Three canonical
representations for Laurent binomial difference ideals are given in terms of
the reduced Groebner basis of Z[x]-lattices, regular and coherent difference
ascending chains, and partial characters over Z[x]-lattices, respectively.
Criteria for a Laurent binomial difference ideal to be reflexive, prime,
well-mixed, and perfect are given in terms of their support lattices. The
reflexive, well-mixed, and perfect closures of a Laurent binomial difference
ideal are shown to be binomial. Most of the properties of Laurent binomial
difference ideals are extended to the case of difference binomial ideals.
Finally, algorithms are given to check whether a given Laurent binomial
difference ideal I is reflexive, prime, well-mixed, or perfect, and in the
negative case, to compute the reflexive, well-mixed, and perfect closures of I.
An algorithm is given to decompose a finitely generated perfect binomial
difference ideal as the intersection of reflexive prime binomial difference
ideals.


title:
Anisotropic Black Phosphorus Synaptic Device for Neuromorphic
  Applications

abstract:
  Synapses are functional links between neurons, through which "information"
flows in the neural network. These connections vary significantly in strength,
typically resulting from the intrinsic heterogeneity in their chemical and
biological properties. Such heterogeneity is fundamental to the diversity of
neural activities, which together with other features of the brain enables
functions ranging from perception and recognition, to memory and reasoning.
Realizing such heterogeneity in synaptic electronics is critical towards
building artificial neural network with the potential for achieving the level
of complexity in biological systems. However, such intrinsic heterogeneity has
been very challenging to realize in current synaptic devices. Here, we
demonstrate the first black phosphorus (BP) synaptic device, which offers
intrinsic anisotropy in its synaptic characteristics directly resulting from
its low crystal symmetry. The charge transfer between the 2-nm native oxide of
BP and the BP channel is utilized to achieve the synaptic behavior. Key
features of biological synapses such as long-term plasticity with
heterogeneity, including long-term potentiation/depression and
spike-timing-dependent plasticity, are mimicked. With the anisotropic BP
synaptic devices, we also realize a simple compact heterogeneous
axon-multi-synapses network. This demonstration represents an important step
towards introducing intrinsic heterogeneity to artificial neuromorphic systems.


title:
High energy electromagnetic cascades in extragalactic space: physics and
  features

abstract:
  Using the analytic modeling of the electromagnetic cascades compared with
more precise numerical simulations we describe the physical properties of
electromagnetic cascades developing in the universe on CMB and EBL background
radiations. A cascade is initiated by very high energy photon or electron and
the remnant photons at large distance have two-component energy spectrum,
$\propto E^{-2}$ ($\propto E^{-1.9}$ in numerical simulations) produced at
cascade multiplication stage, and $\propto E^{-3/2}$ from Inverse Compton
electron cooling at low energies. The most noticeable property of the cascade
spectrum in analytic modeling is 'strong universality', which includes the
standard energy spectrum and the energy density of the cascade $\omega_{\rm
cas}$ as its only numerical parameter. Using numerical simulations of the
cascade spectrum and comparing it with recent Fermi LAT spectrum we obtained
the upper limit on $\omega_{\rm cas}$ stronger than in previous works. The new
feature of the analysis is "$E_{\max}$ rule". We investigate the dependence of
$\omega_{\rm cas}$ on the distribution of sources, distinguishing two cases of
universality: the strong and weak ones.


title: Quantum localization of Classical Mechanics

abstract:
  Quantum localization of classical mechanics within the BRST-BFV and BV (or
field-antifield) quantization methods are studied. It is shown that a special
choice of gauge fixing functions (or BRST-BFV charge) together with the unitary
limit leads to Hamiltonian localization in the path integral of the BRST-BFV
formalism. In turn, we find that a special choice of gauge fixing functions
being proportional to extremals of an initial non-degenerate classical action
together with a very special solution of the classical master equation result
in Lagrangian localization in the partition function of the BV formalism.


title: The critical orbit structure of quadratic polynomials in $\mathbb{Z}_p$

abstract:
  We study the forward orbit of the critical point for polynomials of the form
$f_c=z^2+c$ defined over $\mathbb{Z}_p$. Hubbard trees capture the dynamical
behavior for such maps with finite critical orbit in $\mathbb{C}$. We suggest a
notion of Hubbard trees in the non-Archimedean setting, and describe the
possible structures that arise for polynomials in $\mathbb{Z}_p$. As an
example, we take a closer look at the dynamics of $f_c$ for $c\in\mathbb{Z}_3$.


title: Note on the "size" of Schroedinger cats

abstract:
  We give some arguments to evaluate the "size" of Schrodinger cat for the flux
qubit, which has really different results from ref.[1] Korsbakken et al.
  [1] J.Korsbakken,F.K.Wilhelm and K.B.Whaley,Physics Scripta T137,014022
(2009)


title: Entanglement-assisted quantum metrology

abstract:
  Entanglement-assisted quantum communication employs pre-shared entanglement
between sender and receiver as a resource. We apply the same framework to
quantum metrology, introducing shared entanglement between the preparation and
the measurement stage, namely using some entangled ancillary system that does
not interact with the system to be sampled. This is known to be useless in the
noiseless case, but was recently shown to be useful in the presence of noise.
Here we detail how and when it can be of use. For example, surprisingly it is
useful when randomly time sharing two channels where ancillas do not help
(depolarizing). We show that it is useful for all levels of noise for many
noise models and propose a simple experiment to test these results.


title:
Soliton solutions of an integrable nonlocal modified Korteweg-de Vries
  equation through inverse scattering transform

abstract:
  It is well known that the nonlinear Schr\"odinger (NLS) equation is a very
important integrable equation. Ablowitz and Musslimani introduced and
investigated an integrable nonlocal NLS equation through inverse scattering
transform. Very recently, we proposed an integrable nonlocal modified
Korteweg-de Vries equation (mKdV) which can also be found in a paper of
Ablowitz and Musslimani. We have constructed the Darboux transformation and
soliton solutions for the nonlocal mKdV equation. In this paper, we will
investigate further the nonlocal mKdV equation. We will give its exact
solutions including soliton and breather through inverse scattering
transformation. These solutions have some new properties, which are different
from the ones of the mKdV equation.


title: Path connectivity of line graphs

abstract:
  Dirac showed that in a $(k-1)$-connected graph there is a path through each
$k$ vertices. The path $k$-connectivity $\pi_k(G)$ of a graph $G$, which is a
generalization of Dirac's notion, was introduced by Hager in 1986. In this
paper, we study path connectivity of line graphs.


title: The methodology of resonant equiangular composite quantum gates

abstract:
  The creation of composite quantum gates that implement quantum response
functions $\hat{U}(\theta)$ dependent on some parameter of interest $\theta$ is
often more of an art than a science. Through inspired design, a sequence of $L$
primitive gates also depending on $\theta$ can engineer a highly nontrivial
$\hat{U}(\theta)$ that enables myriad precision metrology, spectroscopy, and
control techniques. However, discovering new, useful examples of
$\hat{U}(\theta)$ requires great intuition to perceive the possibilities, and
often brute-force to find optimal implementations. We present a systematic and
efficient methodology for composite gate design of arbitrary length, where
phase-controlled primitive gates all rotating by $\theta$ act on a single spin.
We fully characterize the realizable family of $\hat{U}(\theta)$, provide an
efficient algorithm that decomposes a choice of $\hat{U}(\theta)$ into its
shortest sequence of gates, and show how to efficiently choose an achievable
$\hat{U}(\theta)$ that for fixed $L$, is an optimal approximation to objective
functions on its quadratures. A strong connection is forged with
\emph{classical} discrete-time signal processing, allowing us to swiftly
construct, as examples, compensated gates with optimal bandwidth that implement
arbitrary single spin rotations with sub-wavelength spatial selectivity.


title: On invariants for the Poincare equations and applications

abstract:
  We extend the Noether theory of invariants to the Poincare equations. We
apply this extension to the Maxwell-Lorentz equations coupled to the Abraham
rotating extended electron with the configuration space SO(3).


title: On the polarization of fermion in an intermediate state

abstract:
  We show that calculation of a final fermion polarization (for a pure initial
state) is equivalent to the problem of looking for complete polarization axis
of bispinor. This gives the method for calculation of polarization applicable
both for final and intermediate state fermions. We suggest to use fermion
propagator (bare or dressed) in form of spectral representation, which gives
the orthogonal off-shell energy projectors. This representation leads to
covariant separation of particle and antiparticle contributions and gives a
natural definition for polarization of intermediate state fermion. The most
evident application is related with consistent description of $t$-quark
polarization.


title: The Classification of Clifford Gates over Qubits

abstract:
  We examine the following problem: given a collection of Clifford gates,
describe the set of unitaries generated by circuits composed of those gates.
Specifically, we allow the standard circuit operations of composition and
tensor product, as well as ancillary workspace qubits as long as they start and
end in states uncorrelated with the input, which rule out common "magic state
injection" techniques that make Clifford circuits universal. We show that there
are exactly 57 classes of Clifford unitaries and present a full classification
characterizing the gate sets which generate them. This is the first attempt at
a quantum extension of the classification of reversible classical gates
introduced by Aaronson et al., another part of an ambitious program to classify
all quantum gate sets.
  The classification uses, at its center, a reinterpretation of the tableau
representation of Clifford gates to give circuit decompositions, from which
elementary generators can easily be extracted. The 57 different classes are
generated in this way, 30 of which arise from the single-qubit subgroups of the
Clifford group. At a high level, the remaining classes are arranged according
to the bases they preserve. For instance, the CNOT gate preserves the X and Z
bases because it maps X-basis elements to X-basis elements and Z-basis elements
to Z-basis elements. The remaining classes are characterized by more subtle
tableau invariants; for instance, the T_4 and phase gate generate a proper
subclass of Z-preserving gates.


title: Learning Typographic Style

abstract:
  Typography is a ubiquitous art form that affects our understanding,
perception, and trust in what we read. Thousands of different font-faces have
been created with enormous variations in the characters. In this paper, we
learn the style of a font by analyzing a small subset of only four letters.
From these four letters, we learn two tasks. The first is a discrimination
task: given the four letters and a new candidate letter, does the new letter
belong to the same font? Second, given the four basis letters, can we generate
all of the other letters with the same characteristics as those in the basis
set? We use deep neural networks to address both tasks, quantitatively and
qualitatively measure the results in a variety of novel manners, and present a
thorough investigation of the weaknesses and strengths of the approach.


title: Dense blocks of energetic ions driven by multi-petawatt lasers

abstract:
  Laser-driven ion accelerators have the advantages of compact size, high
density, and short bunch duration over conventional accelerators. Nevertheless,
it is still challenging to simultaneously enhance the yield and quality of
laser-driven ion beams for practical applications. Here we propose a scheme to
address this challenge via the use of emerging multi-petawatt lasers and a
density-modulated target. The density-modulated target permits its ions to be
uniformly accelerated as a dense block by laser radiation pressure. In
addition, the beam quality of the accelerated ions is remarkably improved by
embedding the target in a thick enough substrate, which suppresses hot electron
refluxing and thus alleviates plasma heating. Particle-in-cell simulations
demonstrate that almost all ions in a solid-density plasma of a few microns can
be uniformly accelerated to about 25% of the speed of light by a laser pulse at
an intensity around 1022 W/cm2. The resulting dense block of energetic ions may
drive fusion ignition and more generally create matter with unprecedented high
energy density.


title: Fast Learning from Distributed Datasets without Entity Matching

abstract:
  Consider the following data fusion scenario: two datasets/peers contain the
same real-world entities described using partially shared features, e.g.
banking and insurance company records of the same customer base. Our goal is to
learn a classifier in the cross product space of the two domains, in the hard
case in which no shared ID is available -- e.g. due to anonymization.
Traditionally, the problem is approached by first addressing entity matching
and subsequently learning the classifier in a standard manner. We present an
end-to-end solution which bypasses matching entities, based on the recently
introduced concept of Rademacher observations (rados). Informally, we replace
the minimisation of a loss over examples, which requires to solve entity
resolution, by the equivalent minimisation of a (different) loss over rados.
Among others, key properties we show are (i) a potentially huge subset of these
rados does not require to perform entity matching, and (ii) the algorithm that
provably minimizes the rado loss over these rados has time and space
complexities smaller than the algorithm minimizing the equivalent example loss.
Last, we relax a key assumption of the model, that the data is vertically
partitioned among peers --- in this case, we would not even know the existence
of a solution to entity resolution. In this more general setting, experiments
validate the possibility of significantly beating even the optimal peer in
hindsight.


title:
The vicinity of hyper-honeycomb $\beta$-Li2IrO3 to a three-dimensional
  Kitaev spin liquid state

abstract:
  Due to the combination of a substantial spin-orbit coupling and correlation
effects, iridium oxides hold a prominent place in the search for novel quantum
states of matter, including, e.g., Kitaev spin liquids and topological Weyl
states. We establish the promise of the very recently synthesized
hyper-honeycomb iridate $\beta$-Li2IrO3 in this regard. A detailed theoretical
analysis reveals the presence of large ferromagnetic first-neighbor Kitaev
interactions, while a second-neighbor antiferromagnetic Heisenberg exchange
drives the ground state from ferro to zigzag order via a three-dimensional
Kitaev spin liquid and an incommensurate phase. Experiment puts the system in
the latter regime but the Kitaev spin liquid is very close and reachable by a
slight modification of the ratio between the second- and first-neighbor
couplings, for instance via strain.


title: Two-phase heat conductors with a stationary isothermic surface

abstract:
  We consider a two-phase heat conductor in $\mathbb R^N$ with $N \geq 2$
consisting of a core and a shell with different constant conductivities.
Suppose that, initially, the conductor has temperature 0 and, at all times, its
boundary is kept at temperature 1.
  It is shown that, if there is a stationary isothermic surface in the shell
near the boundary, then the structure of the conductor must be spherical. Also,
when the medium outside the two-phase conductor has a possibly different
conductivity, we consider the Cauchy problem with $N \ge 3$ and the initial
condition where the conductor has temperature 0 and the outside medium has
temperature 1. Then we show that almost the same proposition holds true.


title: Distinguishing number and distinguishing index of join of two graphs

abstract:
  The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the
least integer $d$ such that $G$ has an vertex labeling (edge labeling) with $d$
labels that is preserved only by a trivial automorphism. In this paper we study
the distinguishing number and the distinguishing index of join of two graphs
$G$ and $H$, i.e., $G+H$. We prove that $0\leq D(G+H)-max\{D(G),D(H)\}\leq z$,
where $z$ is depends of the number of some induced subgraphs generated by some
suitable partitions of $V(G)$ and $V(H)$. Also, we prove that if $G$ is a
connected graph of order $n \geq 2$, then $D'(G+ \cdots +G)=2$, except
$D'(K_2+K_2)=3$.


title:
Existence of solutions of scalar field equations with fractional
  operator

abstract:
  In this paper, the existence of least energy solution and infinitely many
solutions is proved for the equation $(1-\Delta)^\alpha u = f(u)$ in
$\mathbf{R}^N$ where $0<\alpha<1$, $N \geq 2$ and $f(s)$ is a Berestycki-Lions
type nonlinearity. The characterization of the least energy by the mountain
pass value is also considered and the existence of optimal path is shown.
Finally, exploiting these results, the existence of positive solution for the
equation $(1-\Delta)^\alpha u = f(x,u)$ in $\mathbf{R}^N$ is established under
suitable conditions on $f(x,s)$.


title: Deciphering infant mortality. Part 1: empirical evidence

abstract:
  This paper is not (or at least not only) about human infant mortality. In
line with reliability theory, "infant" will refer here to the time interval
following birth during which the mortality (or failure) rate decreases. This
definition provides a systems science perspective in which birth constitutes a
sudden transition which falls within the field of application of the "Transient
Shock" (TS) conjecture put forward in Richmond et al. (2016c). This conjecture
provides predictions about the timing and shape of the death rate peak. (i) It
says that there will be a death rate spike whenever external conditions change
abruptly and drastically. (ii) It predicts that after a steep rising there will
be a much longer hyperbolic relaxation process. These predictions can be tested
by considering living organisms for which birth is a multi-step process. Thus,
for fish there are three states: egg, yolk-sac phase, young adult. The TS
conjecture predicts a mortality spike at the end of the yolk-sac phase, and
this timing is indeed confirmed by observation. Secondly, the hyperbolic nature
of the relaxation process can be tested using high accuracy Swiss statistics
which give postnatal death rates from one hour after birth up to the age of 10
years. It turns out that since the 19th century despite a great overall
reduction in infant mortality, the shape of the age-specific death rate has
remained basically unchanged. This hyperbolic pattern is not specific to
humans. It can also be found in small primates as recorded in the archives of
zoological gardens. Our ultimate objective is to set up a chain of cases which
starts from simple systems and then moves up step by step to more complex
organisms. The cases discussed here can be seen as initial landmarks.


title: Observational constraints on cosmological superstrings

abstract:
  From theoretical point of view and not being in contradiction with current
observational data, the cosmic strings should have fundamentally different
origin and are characterized by wide range of energies. The paper is devoted to
search for possible cosmological observational tests on superstring theory,
among them to identification of observational characteristics to distinguish
between cosmological superstring of different types. In the brane-world
scenario with an assumption of creation of cosmological superstrings it was
obtained the lower limit on the superstring tension as function of deficit
angle.


title:
Pionic contribution in the Drell-Yan dilepton production cross section
  in p-Cu collision in the framework of the shell and Fermi gas models

abstract:
  To investigate the high mass dilepton production cross section produced due
to the Drell-Yan process in hadronic collisions such as nucleon- nucleus, the
valence and sea quarks distribution functions inside nucleus is used. In this
study, in the framework of the shell and Fermi gas models, by adding quarks
distribution functions of pions inside nucleus besides the quarks distribution
functions of bound nucleons, the changes in the dilepton production cross
section were investigated. For this reason, pionic contribution in the
structure function of 63Cunucleus and its EMC ratio was first studied using the
aforementioned models. Then, in the framework of the Drell-Yan process using
GRV's nucleons and pions quarks distribution functions, the high mass dilepton
production cross section in p-cu collision was calculated and compared with the
available experimental data. The extracted results, based on the two mentioned
models, were greatly the same and by considering the pionic contribution, the
theoretical results were consistent with the experimental data.


title:
Using Twitter to Understand Public Interest in Climate Change: The case
  of Qatar

abstract:
  Climate change has received an extensive attention from public opinion in the
last couple of years, after being considered for decades as an exclusive
scientific debate. Governments and world-wide organizations such as the United
Nations are working more than ever on raising and maintaining public awareness
toward this global issue. In the present study, we examine and analyze Climate
Change conversations in Qatar's Twittersphere, and sense public awareness
towards this global and shared problem in general, and its various related
topics in particular. Such topics include but are not limited to politics,
economy, disasters, energy and sandstorms. To address this concern, we collect
and analyze a large dataset of 109 million tweets posted by 98K distinct users
living in Qatar -- one of the largest emitters of CO2 worldwide. We use a
taxonomy of climate change topics created as part of the United Nations Pulse
project to capture the climate change discourse in more than 36K tweets. We
also examine which topics people refer to when they discuss climate change, and
perform different analysis to understand the temporal dynamics of public
interest toward these topics.


title:
Unified Microscopic-Macroscopic Monte Carlo Simulations of Complex
  Organic Molecule Chemistry in Cold Cores

abstract:
  The recent discovery of methyl formate and dimethyl ether in the gas phase of
cold cores with temperatures as cold as 10 K challenges our previous
astrochemical models concerning the formation of complex organic molecules. The
strong correlation between the abundances and distributions of methyl formate
and dimethyl ether further shows that current astrochemical models may be
missing important chemical processes in cold astronomical sources. We
investigate a scenario in which complex organic molecules and the methoxy
radical can be formed on dust grains via a so-called "chain reaction"
mechanism, in a similar manner to CO$_2$. A unified gas-grain
microscopic-macroscopic Monte Carlo approach with both normal and interstitial
sites for icy grain mantles is used to perform the chemical simulations.
Reactive desorption with varying degrees of efficiency is included to enhance
the non-thermal desorption of species formed on cold dust grains. In addition,
varying degrees of efficiency for the surface formation of methoxy are also
included. The observed abundances of a variety of organic molecules in cold
cores can be reproduced in our models. The strong correlation between the
abundances of methyl formate and dimethyl ether in cold cores can also be
explained. Non-diffusive chemical reactions on dust grain surfaces may play a
key role in the formation of some complex organic molecules.


title:
The Death and Life of Great Italian Cities: A Mobile Phone Data
  Perspective

abstract:
  The Death and Life of Great American Cities was written in 1961 and is now
one of the most influential book in city planning. In it, Jane Jacobs proposed
four conditions that promote life in a city. However, these conditions have not
been empirically tested until recently. This is mainly because it is hard to
collect data about "city life". The city of Seoul recently collected pedestrian
activity through surveys at an unprecedented scale, with an effort spanning
more than a decade, allowing researchers to conduct the first study
successfully testing Jacobs's conditions. In this paper, we identify a valuable
alternative to the lengthy and costly collection of activity survey data:
mobile phone data. We extract human activity from such data, collect land use
and socio-demographic information from the Italian Census and Open Street Map,
and test the four conditions in six Italian cities. Although these cities are
very different from the places for which Jacobs's conditions were spelled out
(i.e., great American cities) and from the places in which they were recently
tested (i.e., the Asian city of Seoul), we find those conditions to be indeed
associated with urban life in Italy as well. Our methodology promises to have a
great impact on urban studies, not least because, if replicated, it will make
it possible to test Jacobs's theories at scale.


title: Finite orbits for nilpotent actions on the torus

abstract:
  A homeomorphism of the $2$-torus with Lefschetz number different from zero
has a fixed point. We give a version of this result for nilpotent groups of
diffeomorphisms. We prove that a nilpotent group of $2$-torus diffeomorphims
has finite orbits when the group has some element with Lefschetz number
different from zero.


title: Quantum superballistic diffusion in presence of white noise

abstract:
  As an unusual type of anomalous diffusion behavior, (transient)
superballistic transport is not well understood but it has been experimentally
observed recently. We here calculate the white noise effect (in Markov
approximation) on the quantum diffusion in 1D tight-binding model with
disordered and quasi-periodic region of size L attached to perfect lattices at
both ends. Here we show the effect of white noise on spreading of the wave
packet initially located at the center of the sublattice. We find threshold
values of the white noise strength, beyond which the quantum hyperdiffusion
does not occur. We predict from our numerical studies that the quantum
hyperdiffusion exponent can be tuned by the strength of applied white noise.
Therefore we can manually apply noise to a system to drive it to desired
diffusion rate.


title: Learning zeroth class dictionary for human action recognition

abstract:
  In this paper, a discriminative two-phase dictionary learning framework is
proposed for classifying human action by sparse shape representations, in which
the first-phase dictionary is learned on the selected discriminative frames and
the second-phase dictionary is built for recognition using reconstruction
errors of the first-phase dictionary as input features. We propose a "zeroth
class" trick for detecting undiscriminating frames of the test video and
eliminating them before voting on the action categories. Experimental results
on benchmarks demonstrate the effectiveness of our method.


title: Universal Entanglement Spectra of Gapped One-dimensional Field Theories

abstract:
  We discuss the entanglement spectrum of the ground state of a gapped
(1+1)-dimensional system in a phase near a quantum phase transition. In
particular, in proximity to a quantum phase transition described by a conformal
field theory (CFT), the system is represented by a gapped Lorentz invariant
field theory in the "scaling limit" (correlation length $\xi$ much larger than
microscopic 'lattice' scale $a$), and can be thought of as a CFT perturbed by a
relevant perturbation. We show that for such (1+1) gapped Lorentz invariant
field theories in infinite space, the low-lying entanglement spectrum obtained
by tracing out, say, left half-infinite space, is precisely equal to the
physical spectrum of the unperturbed gapless, i.e. conformal field theory
defined on a finite interval of length $L_\xi=$ $\log(\xi/a)$ with certain
boundary conditions. In particular, the low-lying entanglement spectrum of the
gapped theory is the finite-size spectrum of a boundary conformal field theory,
and is always discrete and universal. Each relevant perturbation, and thus each
gapped phase in proximity to the quantum phase transition, maps into a
particular boundary condition. A similar property has been known to hold for
Baxter's Corner Transfer Matrices in a very special class of fine-tuned, namely
integrable off-critical lattice models, for the entire entanglement spectrum
and independent of the scaling limit. In contrast, our result applies to
completely general gapped Lorentz invariant theories in the scaling limit,
without the requirement of integrability, for the low-lying entanglement
spectrum. - The finite-size spectra of the entanglement Hamiltonian and of the
physical Hamiltonian on an interval of length R exhibit entirely different
behaviors upon crossover from the critical regime $R \ll \xi$ to the gapped
regime $R \gg \xi$.


title: Clustering Financial Time Series: How Long is Enough?

abstract:
  Researchers have used from 30 days to several years of daily returns as
source data for clustering financial time series based on their correlations.
This paper sets up a statistical framework to study the validity of such
practices. We first show that clustering correlated random variables from their
observed values is statistically consistent. Then, we also give a first
empirical answer to the much debated question: How long should the time series
be? If too short, the clusters found can be spurious; if too long, dynamics can
be smoothed out.


title: On finite $ca$-$\mathfrak F$ groups and their applications

abstract:
  Let $\mathfrak F$ be a class of groups. A group $G$ is called $ca$-$\mathfrak
F$-group if its every non-abelian chief factor is simple and $H/K
\leftthreetimes C_G(H/K) \in \mathfrak F$ for every abelian chief factor $H/K$
of $G$. In this paper, we investigate the structure of a finite $ca$-$\mathfrak
F$-group. Properties of mutually permutable products of finite $ca$-$\mathfrak
F$-groups are studied.


title: Interconnections of input-output Hamiltonian systems with dissipation

abstract:
  Recently, negative imaginary and counter-clockwise systems have attracted
attention as an interesting class of systems, which is well-motivated by
applications. In this paper first the formulation and extension of negative
imaginary and counter-clockwise systems as (nonlinear) input-output Hamiltonian
systems with dissipation is summarized. Next it is shown how by considering the
time-derivative of the outputs a port-Hamiltonian system is obtained, and how
this leads to the consideration of alternate passive outputs for
port-Hamiltonian systems. Furthermore, a converse result to positive feedback
interconnection of input-output Hamiltonian systems with dissipation is
obtained, stating that the positive feedback interconnection of two linear
systems is an input-output Hamiltonian system with dissipation if and only if
the systems themselves are input-output Hamiltonian systems with dissipation.
This implies that the Poisson and resistive structure matrices can be redefined
in such a way that the interaction between the two systems only takes place via
the coupling term in the Hamiltonian of the interconnected system.
Subsequently, it is shown how network interconnection of (possibly nonlinear)
input-output Hamiltonian systems with dissipation results in another
input-output Hamiltonian system with dissipation, and how this leads to a
stability analysis of the interconnected system in terms of the Hamiltonians
and output mappings of the systems associated to the vertices, as well as the
topology of the network.


title:
Statistical Distribution of Intensity Fluctuations for Underwater
  Wireless Optical Channels in the Presence of Air Bubbles

abstract:
  In this paper, we experimentally investigate the statistical distribution of
intensity fluctuations for underwater wireless optical channels under different
channel conditions, namely fresh and salty underwater channels with and without
air bubbles. To do so, we first measure the received optical signal with a
large number of samples. Based on the normalized acquired data the channel
coherence time and the fluctuations probability density function (PDF) are
obtained for different channel scenarios. Our experimental results show that
salt attenuates the received signal while air bubbles mainly introduce severe
intensity fluctuations. Moreover, we observe that log-normal distribution
precisely fits the acquired data PDF for scintillation index ($\sigma^2_I$)
values less than $0.1$, while Gamma-Gamma and K distributions aptly predict the
intensity fluctuations for $\sigma^2_I>1$. Since neither of these distributions
are capable of predicting the received irradiance for $0.1<\sigma^2_I<1$, we
propose a combination of an exponential and a log-normal distributions to
perfectly describe the acquired data PDF for such regimes of scintillation
index.


title: All extensions of $C_2$ by $C_{2^{n+1}}\times C_{2^{n+1}}$ are good

abstract:
  Let $C_{m} $ be a cyclic group of order $m$. We prove that if the group $G$
fits into an extension $1\to C_{2^{n+1}}^2\to G\to C_2\to 1$ then $G$ is good
in the sense of Hopkins-Kuhn-Ravenel, i.e., $K(s)^*(BG)$ is evenly generated by
transfers of Euler classes of complex representations of subgroups of $G$.
Previously this fact was known for $n=1$.


title: The mineral clouds on HD 209458b and HD189733b

abstract:
  3D atmosphere model results are used to comparatively study the kinetic,
non-equilibrium cloud formation in the atmospheres of two example planets
guided by the giant gas planets HD209458b and HD189733b. Rather independently
of hydrodynamic model differences, our cloud modelling suggests that both
planets are covered in mineral clouds throughout the entire modelling domain.
Both planets harbour chemically complex clouds that are made of mineral
particles that have a height-dependent material composition and size. The
remaining gas-phase element abundances strongly effects the molecular
abundances of the atmosphere in the cloud forming regions. Hydrocarbon and
cyanopolyyne molecules can be rather abundant in the inner, dense part of the
atmospheres of HD189733b and HD209458b. No one value for metallicity and the
C/O ratio can be used to describe an extrasolar planet. Our results concerning
the presence and location of water in relation to the clouds explain some of
the observed differences between the two planets. In HD189733b, strong water
features have been reported while such features appear less strong for
HD209458b. By considering the location of the clouds in the two atmospheres, we
see that obscuring clouds exist high in the atmosphere of HD209458b, but much
deeper in HD189733b. We further conclude that the (self-imposed) degeneracy of
cloud parameters in retrieval methods can only be lifted if the cloud formation
processes are accurately modelled in contrast to prescribing them by
independent parameters.

categories: astro-ph.EP astro-ph.SR physics.ao-ph physics.flu-dyn


title:
Resolving coiled shapes reveals new reorientation behaviors in C.
  elegans

abstract:
  We exploit the reduced space of C. elegans postures to develop a novel
tracking algorithm which captures both simple shapes and also self-occluding
coils, an important, yet unexplored, component of worm behavior. We apply our
algorithm to show that visually complex, coiled sequences are a superposition
of two simpler patterns: the body wave dynamics and a head-curvature pulse. We
demonstrate the precise coiled dynamics of an escape response and uncover new
behaviors in spontaneous, large amplitude coils; deep reorientations occur
through classical Omega-shaped postures and also through larger, new postural
excitations which we label here as delta-turns. We find that omega and delta
turns occur independently, the serpentine analog of a random left-right step,
suggesting a distinct triggering mechanism. We also show that omega and delta
turns display approximately equal rates and adapt to food-free conditions on a
similar timescale, a simple strategy to avoid navigational bias.


title:
Extension of Frame's type inequalities to Bessel and modified Bessel
  functions

abstract:
  Our aim is to extend some trigonometric inequalities to Bessel functions.
Moreover, we extend the hyperbolic analogue of these trigonometric
inequalities. As an application of these results we present a generalization of
Cusa-type inequality to modified Bessel function. Our main motivation to write
this paper is a recent publication of Chen and S\'andor, which we wish to
complement.


title: Superlubricity of Graphene Nanoribbons on Gold Surfaces

abstract:
  The state of vanishing friction known as superlubricity has important
applications for energy saving and increasing the lifetime of devices.
Superlubricity detected with atomic force microscopy appears in examples like
sliding large graphite flakes or gold nanoclusters across surfaces. However,
the origin of the behavior is poorly understood due to the lack of a
controllable nano-contact. We demonstrate graphene nanoribbons superlubricity
when sliding on gold with a joint experimental and computational approach. The
atomically well-defined contact allows us to trace the origin of
superlubricity, unravelling the role played by edges, surface reconstruction
and ribbon elasticity. Our results pave the way to the scale-up of
superlubricity toward the realization of frictionless coatings.


title: A comprehensive study of sparse codes on abnormality detection

abstract:
  Sparse representation has been applied successfully in abnormal event
detection, in which the baseline is to learn a dictionary accompanied by sparse
codes. While much emphasis is put on discriminative dictionary construction,
there are no comparative studies of sparse codes regarding abnormality
detection. We comprehensively study two types of sparse codes solutions -
greedy algorithms and convex L1-norm solutions - and their impact on
abnormality detection performance. We also propose our framework of combining
sparse codes with different detection methods. Our comparative experiments are
carried out from various angles to better understand the applicability of
sparse codes, including computation time, reconstruction error, sparsity,
detection accuracy, and their performance combining various detection methods.
Experiments show that combining OMP codes with maximum coordinate detection
could achieve state-of-the-art performance on the UCSD dataset [14].


title:
Energy-spread measurement of triple-pulse electron beams based on the
  magnetic dispersion principle

abstract:
  The energy-spread of the triple-pulse electron beam generated by the
Dragon-II linear induction accelerator is measured using the method of energy
dispersion in the magnetic field. A sector magnet is applied for energy
analyzing of the electron beam, which has a bending radius of 300 mm and a
deflection angle of 90 degrees. For each pulse, both the time-resolved and the
integral images of the electron position at the output port of the bending beam
line are recorded by a streak camera and a CCD camera, respectively.
Experimental results demonstrate an energy-spread of less than +-2.0% for the
electron pulses. The cavity voltage waveforms obtained by different detectors
are also analyzed for comparison.


title:
Synergizing superresolution optical fluctuation imaging with single
  molecule localization microscopy

abstract:
  Single molecule localization microscopy (SMLM) techniques enable imaging
biological samples well beyond the diffraction limit of light, but they vary
significantly in their spatial and temporal resolutions. High-order statistical
analysis of temporal fluctuations as in superresolution optical fluctuation
imaging (SOFI) also enable imaging beyond diffraction limit, but usually at a
lower resolution as compared to SMLM. Since the same data format is acquired
for both methods, their algorithms can be applied to the same data set, and
thus may be combined synergistically to improve overall imaging performance.
Here, we find that SOFI converges much faster than SMLM, provides additive
information to SMLM, and can efficiently reject background. We then show how
SOFI-assisted SMLM imaging can improve SMLM image reconstruction by rejecting
common sources of background, especially under low signal-to-background
conditions. The performance of our approach was evaluated using a realistic
simulation of fluorescence imaging we developed and further demonstrated on
experimental SMLM images of the plasma membrane of activated fixed and live T
cells. Our approach significantly enhances SMLM performance under demanding
imaging conditions and could set an example for synergizing additional imaging
techniques.


title:
A simple proof of the strong integrality for full colored HOMFLYPT
  invariants

abstract:
  By using the HOMFLY skein theory. We prove a strong integrality theorem for
the reduced colored HOMFLYPT invariants defined by a basis in the full HOMFLY
skein of the annulus.


title:
Geodesics, retracts, and the norm-preserving extension property in the
  symmetrized bidisc

abstract:
  A set $V$ in a domain $U$ in $\mathbb{C}^n$ has the {\em norm-preserving
extension property} if every bounded holomorphic function on $V$ has a
holomorphic extension to $U$ with the same supremum norm. We prove that an
algebraic subset of the {\em symmetrized bidisc} \[ G := \{(z+w,zw):|z|<1, |w|
< 1 \} \] has the norm-preserving extension property if and only if it is
either a singleton, $G$ itself, a complex geodesic of $G$, or the union of the
set $\{(2z,z^2): |z|<1\}$ and a complex geodesic of degree $1$ in $G$. We also
prove that the complex geodesics in $G$ coincide with the nontrivial
holomorphic retracts in $G$. Thus, in contrast to the case of the ball or the
bidisc, there are sets in $G$ which have the norm-preserving extension property
but are not holomorphic retracts of $G$. In the course of the proof we obtain a
detailed classification of the complex geodesics in $G$ modulo automorphisms of
$G$. We give applications to von Neumann-type inequalities for
$\Gamma$-contractions (that is, commuting pairs of operators for which the
closure of $G$ is a spectral set) and for symmetric functions of commuting
pairs of contractive operators. We find three other domains that contain sets
with the norm-preserving extension property which are not retracts: they are
the spectral ball of $2\times 2$ matrices, the tetrablock and the pentablock.
We also identify the subsets of the bidisc which have the norm-preserving
extension property for symmetric functions.


title: On Physical Web Browser

abstract:
  In this paper, we present the Physical Web Browser project for web
applications depending on the environment. At this moment, many of users all
over the world visit websites using their mobile devices only. Any mobile
device (e.g., smartphone) has sensors to capture the environmental information.
This information (context) could be analyzed and used within the web
applications. There are, at least, two models for using this information.
Firstly, we can use context information for data gathering requests in a web
application. In this case, the output depends on the context. It is the
classical model for context-aware data retrieval. In the second model, we can
use context-aware data for improving user experience (for changing and tuning
user interfaces). In other words, we present a way for the adaptation of web
applications depending on the environment.


title: A function determined by a hypersurface of positive characteristic

abstract:
  Let R be a formal power series ring over a perfect field k of prime
characteristic p, and let m be the maximal ideal of R. Suppose f is a non-zero
element in m. In this paper, we introduce a function xi (x) associated with a
hypersurface defined on the closed interval [0, 1] in R. The Hilbert-Kunz
function and the F-signature of a hypersurface appear as the values of our
function xi (x) on the interval s endpoints.


title:
Molecular-scale Description of SPAN80 Desorption from the Squalane-Water
  Interface

abstract:
  Extensive all-atom molecular dynamics calculations on the water-squalane
interface for nine different loadings with sorbitan monooleate (SPAN80), at
$T=300$K, are analyzed for the surface tension equation of state, desorption
free energy profiles as they depend on loading, and to evaluate escape times
for absorbed SPAN80 into the bulk phases. These results suggest that loading
only weakly affects accommodation of a SPAN80 molecule by this squalane-water
interface. Specifically, the surface tension equation of state is simple
through the range of high tension to high loading studied, and the desorption
free energy profiles are weakly dependent on loading here. The perpendicular
motion of the centroid of the SPAN80 head-group ring is well-described by a
diffusional model near the minimum of the desorption free energy profile.
Lateral diffusional motion is weakly dependent on loading. Escape times
evaluated on the basis of a diffusional model and the desorption free energies
are $7\times 10^{-2}$ s (into the squalane) and $3\times 10^2$ h (into the
water). The latter value is consistent with irreversible absorption observed by
related experimental work.


title: Higher-order variational problems of Herglotz type with time delay

abstract:
  We study, using an optimal control point of view, higher-order variational
problems of Herglotz type with time delay. Main results are higher-order
Euler-Lagrange and DuBois-Reymond necessary optimality conditions as well as a
higher-order Noether type theorem for delayed variational problems of Herglotz
type.


title:
Spin Coherence and $^{14}$N ESEEM Effects of Nitrogen-Vacancy Centers in
  Diamond with X-band Pulsed ESR

abstract:
  Pulsed ESR experiments are reported for ensembles of negatively-charged
nitrogen-vacancy centers (NV$^-$) in diamonds at X-band magnetic fields
(280-400 mT) and low temperatures (2-70 K). The NV$^-$ centers in synthetic
type IIb diamonds (nitrogen impurity concentration $<1$~ppm) are prepared with
bulk concentrations of $2\cdot 10^{13}$ cm$^{-3}$ to $4\cdot 10^{14}$ cm$^{-3}$
by high-energy electron irradiation and subsequent annealing. We find that a
proper post-radiation anneal (1000$^\circ$C for 60 mins) is critically
important to repair the radiation damage and to recover long electron spin
coherence times for NV$^-$s. After the annealing, spin coherence times of T$_2
= 0.74$~ms at 5~K are achieved, being only limited by $^{13}$C nuclear spectral
diffusion in natural abundance diamonds. At X-band magnetic fields, strong
electron spin echo envelope modulation (ESEEM) is observed originating from the
central $^{14}$N nucleus. The ESEEM spectral analysis allows for accurate
determination of the $^{14}$N nuclear hypefine and quadrupole tensors. In
addition, the ESEEM effects from two proximal $^{13}$C sites (second-nearest
neighbor and fourth-nearest neighbor) are resolved and the respective $^{13}$C
hyperfine coupling constants are extracted.


title:
Infinite-dimensional Bayesian approach for inverse scattering problems
  of a fractional Helmholtz equation

abstract:
  In this paper, we focus on a new wave equation described wave propagation in
the attenuation medium. In the first part of this paper, based on the
time-domain space fractional wave equation, we formulate the frequency-domain
equation named as fractional Helmholtz equation. According to the physical
interpretations, this new model could be divided into two separate models:
loss-dominated model and dispersion-dominated model. For the loss-dominated
model (it is an integer- and fractional-order mixed elliptic equation), a
well-posedness theory has been established and the Lipschitz continuity of the
scattering field with respect to the scatterer has also been
established.Because the complexity of the dispersion-dominated model (it is an
integer- and fractional-order mixed elliptic system), we only provide a
well-posedness result for sufficiently small wavenumber. In the second part of
this paper, we generalize the Bayesian inverse theory in infinite-dimension to
allow a part of the noise depends on the target function (the function needs to
be estimated). Then, we prove that the estimated function tends to be the true
function if both the model reduction error and the white noise vanish. At last,
our theory has been applied to the loss-dominated model with absorbing boundary
condition.


title: Pose for Action - Action for Pose

abstract:
  In this work we propose to utilize information about human actions to improve
pose estimation in monocular videos. To this end, we present a pictorial
structure model that exploits high-level information about activities to
incorporate higher-order part dependencies by modeling action specific
appearance models and pose priors. However, instead of using an additional
expensive action recognition framework, the action priors are efficiently
estimated by our pose estimation framework. This is achieved by starting with a
uniform action prior and updating the action prior during pose estimation. We
also show that learning the right amount of appearance sharing among action
classes improves the pose estimation. We demonstrate the effectiveness of the
proposed method on two challenging datasets for pose estimation and action
recognition with over 80,000 test images.


title:
Influence of the "second gap" on the transparency-conductivity
  compromise in transparent conducting oxides: an ab initio study

abstract:
  Transparent conducting oxides (TCOs) are essential to many technologies.
These materials are doped (\emph{n}- or \emph{p}-type) oxides with a large
enough band gap (ideally $>$3~eV) to ensure transparency. However, the high
carrier concentration present in TCOs lead additionally to the possibility for
optical transitions from the occupied conduction bands to higher states for
\emph{n}-type materials and from lower states to the unoccupied valence bands
for \emph{p}-type TCOs. The "second gap" formed by these transitions might
limit transparency and a large second gap has been sometimes proposed as a
design criteria for high performance TCOs. Here, we study the influence of this
second gap on optical absorption using \emph{ab initio} computations for
several well-known \emph{n}- and \emph{p}-type TCOs. Our work demonstrates that
most known \emph{n}-type TCOs do not suffer from second gap absorption in the
visible even at very high carrier concentrations. On the contrary,
\emph{p}-type oxides show lowering of their optical transmission for high
carrier concentrations due to second gap effects. We link this dissimilarity to
the different chemistries involved in \emph{n}- versus typical \emph{p}-type
TCOs. Quantitatively, we show that second gap effects lead to only moderate
loss of transmission (even in p-type TCOs) and suggest that a wide second gap,
while beneficial, should not be considered as a needed criteria for a working
TCO.


title:
AP-Cloud: Adaptive Particle-in-Cloud Method for Optimal Solutions to
  Vlasov-Poisson Equation

abstract:
  We propose a new adaptive Particle-in-Cloud (AP-Cloud) method for obtaining
optimal numerical solutions to the Vlasov-Poisson equation. Unlike the
traditional particle-in-cell (PIC) method, which is commonly used for solving
this problem, the AP-Cloud adaptively selects computational nodes or particles
to deliver higher accuracy and efficiency when the particle distribution is
highly non-uniform. Unlike other adaptive techniques for PIC, our method
balances the errors in PDE discretization and Monte Carlo integration, and
discretizes the differential operators using a generalized finite difference
(GFD) method based on a weighted least square formulation. As a result,
AP-Cloud is independent of the geometric shapes of computational domains and is
free of artificial parameters. Efficient and robust implementation is achieved
through an octree data structure with 2:1 balance. We analyze the accuracy and
convergence order of AP-Cloud theoretically, and verify the method using an
electrostatic problem of a particle beam with halo. Simulation results show
that the AP-Cloud method is substantially more accurate and faster than the
traditional PIC, and it is free of artificial forces that are typical for some
adaptive PIC techniques.


title:
Rotational Symmetry Breaking in a Trigonal superconductor Nb-doped
  Bi2Se3

abstract:
  The search for unconventional superconductivity has been focused on materials
with strong spin-orbit coupling and unique crystal lattices. Doped bismuth
selenide (Bi$_2$Se$_3$) is a strong candidate given the topological insulator
nature of the parent compound and its triangular lattice. The coupling between
the physical properties in the superconducting state and its underlying crystal
symmetry is a crucial test for unconventional superconductivity. In this paper,
we report direct evidence that the superconducting magnetic response couples
strongly to the underlying 3-fold crystal symmetry in the recently discovered
superconductor with trigonal crystal structure, niobium (Nb)-doped bismuth
selenide (Bi$_2$Se$_3$). More importantly, we observed that the magnetic
response is greatly enhanced along one preferred direction spontaneously
breaking the rotational symmetry. Instead of a simple 3-fold crystalline
symmetry, the superconducting hysteresis loop shows dominating 2-fold and
4-fold symmetry. This observation confirms the breaking of the rotational
symmetry and indicates the presence of nematic order in the superconducting
ground state of Nb-doped Bi$_2$Se$_3$. Further, heat capacity measurements
display an exponential decay in superconducting state and suggest that there is
no line node in the superconducting gap. These observations provide strong
evidence of odd-parity topological superconductivity.


title: A Wave Packet Approach to Interacting Fermions

abstract:
  In this thesis, we study the breakdown of the Fermi liquid state in cuprate
superconductors using the renormalization group (RG). We seek to extend earlier
work on the crossover from the Fermi liquid state to the pseudo gap phase based
on RG flows in the so-called saddle point regime. Progress in the derivation of
effective models for the conjectured spin liquid state has been hindered, by
the difficulties involved in solving the strong coupling low energy
Hamiltonian. We tackle the problem by introducing an orthogonal wave packet
basis, the so-called Wilson-Wannier (WW) basis, that can be used to interpolate
between the momentum space and the real space descriptions.
  We show how to combine the WW basis with the RG, such that the RG is used to
eliminate high-energy degrees of freedom, and the remaining strongly correlated
system is solved approximately in the WW basis. We exemplify the approach for
different one-dimensional model systems, and find good qualitative agreement
with exact solutions even for very simple approximations.
  Finally, we reinvestigate the saddle point regime of the two-dimensional
Hubbard model. We show that the anti-nodal states are driven to an insulating
spin-liquid state with strong singlet pairing correlations, thus corroborating
earlier conjectures.


title: Deep Interactive Object Selection

abstract:
  Interactive object selection is a very important research problem and has
many applications. Previous algorithms require substantial user interactions to
estimate the foreground and background distributions. In this paper, we present
a novel deep learning based algorithm which has a much better understanding of
objectness and thus can reduce user interactions to just a few clicks. Our
algorithm transforms user provided positive and negative clicks into two
Euclidean distance maps which are then concatenated with the RGB channels of
images to compose (image, user interactions) pairs. We generate many of such
pairs by combining several random sampling strategies to model user click
patterns and use them to fine tune deep Fully Convolutional Networks (FCNs).
Finally the output probability maps of our FCN 8s model is integrated with
graph cut optimization to refine the boundary segments. Our model is trained on
the PASCAL segmentation dataset and evaluated on other datasets with different
object classes. Experimental results on both seen and unseen objects clearly
demonstrate that our algorithm has a good generalization ability and is
superior to all existing interactive object selection approaches.