title: Assessing the Treatment Effect Heterogeneity with a Latent Variable

abstract:
  The average treatment effect (ATE) is popularly used to assess the treatment
effect. However, the ATE implicitly assumes a homogenous treatment effect even
amongst individuals with different characteristics. In this paper, we mainly
focus on assessing the treatment effect heterogeneity, which has important
implications in designing the optimal individual treatment regimens and in
policy making. The treatment benefit rate (TBR) and treatment harm rate (THR)
have been defined to characterize the magnitude of heterogeneity for binary
outcomes. When the outcomes are continuous, we extend the definitions of the
TBR and THR to compare the difference between potential outcomes with a
pre-specified level c. Unlike the ATE, these rates involve the joint
distribution of the potential outcomes and can not be identified without
further assumptions even in randomized clinical trials. In this article, we
assume the potential outcomes are independent conditional on the observed
covariates and an unmeasured latent variable. Under this assumption, we prove
the identification of the TBR and THR in non-separable (generalized) linear
models for both continuous and binary outcomes. We then propose estimators and
derive their asymptotic distributions. In the simulation studies, we implement
our proposed methods to assess the performance of our estimators and carry out
a sensitive analysis for different underlying distribution for the latent
variable. Finally, we illustrate the proposed methods in two randomized
controlled trials.


title:
Quantification of Human Movement for Assessment in Automated Exercise
  Coaching

abstract:
  Quantification of human movement is a challenge in many areas, ranging from
physical therapy to robotics. We quantify of human movement for the purpose of
providing automated exercise coaching in the home. We developed a model-based
assessment and inference process that combines biomechanical constraints with
movement assessment based on the Microsoft Kinect camera. To illustrate the
approach, we quantify the performance of a simple squatting exercise using two
model-based metrics that are related to strength and endurance, and provide an
estimate of the strength and energy-expenditure of each exercise session. We
look at data for 5 subjects, and show that for some subjects the metrics
indicate a trend consistent with improved exercise performance.


title: The Rise of Social Botnets: Attacks and Countermeasures

abstract:
  Online social networks (OSNs) are increasingly threatened by social bots
which are software-controlled OSN accounts that mimic human users with
malicious intentions. A social botnet refers to a group of social bots under
the control of a single botmaster, which collaborate to conduct malicious
behavior while mimicking the interactions among normal OSN users to reduce
their individual risk of being detected. We demonstrate the effectiveness and
advantages of exploiting a social botnet for spam distribution and
digital-influence manipulation through real experiments on Twitter and also
trace-driven simulations. We also propose the corresponding countermeasures and
evaluate their effectiveness. Our results can help understand the potentially
detrimental effects of social botnets and help OSNs improve their bot(net)
detection systems.


title:
Magneto-intersubband resistance oscillations in GaAs quantum wells
  placed in a tilted magnetic field

abstract:
  The magnetotransport of highly mobile 2D electrons in wide GaAs single
quantum wells with three populated subbands placed in titled magnetic fields is
studied. The bottoms of the lower two subbands have nearly the same energy
while the bottom of the third subband has a much higher energy ($E_1\approx
E_2<<E_3$). At zero in-plane magnetic fields magneto-intersubband oscillations
(MISO) between the $i^{th}$ and $j^{th}$ subbands are observed and obey the
relation $\Delta_{ij}=E_j-E_i=k\cdot\hbar\omega_c$, where $\omega_c$ is the
cyclotron frequency and $k$ is an integer. An application of in-plane magnetic
field produces dramatic changes in MISO and the corresponding electron
spectrum. Three regimes are identified. At $\hbar\omega_c \ll \Delta_{12}$ the
in-plane magnetic field increases considerably the gap $\Delta_{12}$, which is
consistent with the semi-classical regime of electron propagation. In contrast
at strong magnetic fields $\hbar\omega_c \gg \Delta_{12}$ relatively weak
oscillating variations of the electron spectrum with the in-plane magnetic
field are observed. At $\hbar\omega_c \approx \Delta_{12}$ the electron
spectrum undergoes a transition between these two regimes through magnetic
breakdown. In this transition regime MISO with odd quantum number $k$
terminate, while MISO corresponding to even $k$ evolve $continuously$ into the
high field regime corresponding to $\hbar\omega_c \gg \Delta_{12}$


title: General purpose multiplexing device for cryogenic microwave systems

abstract:
  We introduce and experimentally characterize a general purpose device for
signal processing in circuit quantum electrodynamics systems. The device is a
broadband two-port microwave circuit element with three modes of operation: it
can transmit, reflect, or invert incident signals between 4 and 8 GHz. This
property makes it a versatile tool for lossless signal processing at cryogenic
temperatures. In particular, rapid switching (less than or equal to 15 ns)
between these operation modes enables several multiplexing readout protocols
for superconducting qubits. We report the device's performance in a two-channel
code domain multiplexing demonstration. The multiplexed data are recovered with
fast readout times (up to 400 ns) and infidelities less than 0.01 for probe
powers greater than 7 fW, in agreement with the expectation for binary
signaling with Gaussian noise.


title:
Rotating Wave Solutions to Lattice Dynamical Systems I: The
  Anti-Continuum Limit

abstract:
  Rotating waves are a fascinating feature of a wide array of complex systems,
particularly those arising in the study of many chemical and biological
processes. With many rigorous mathematical investigations of rotating waves
relying on the model exhibiting a continuous Euclidean symmetry, this work is
aimed at understanding these nonlinear waves in the absence of such symmetries.
Here we will consider a spatially discrete lattice dynamical system of
Ginzburg-Landau type and prove the existence of rotating waves in the
anti-continuum limit. This result is achieved by providing a link between the
work on phase systems stemming from the study of identically coupled
oscillators on finite lattices to carefully track the solutions as the size of
the lattice grows. It is shown that in the infinite square lattice limit of
these phase systems that a rotating wave solution exists, which can be extended
to the Ginzburg-Landau system of study here. The results of this work provide a
necessary first step in the investigation of rotating waves as solutions to
lattice dynamical systems in an effort to understand the dynamics of such
solutions outside of the idealized situation where the underlying symmetry of a
differential equation can be exploited.


title:
Tweeting the Mind and Instagramming the Heart: Exploring Differentiated
  Content Sharing on Social Media

abstract:
  Understanding the usage of multiple OSNs (Online Social Networks) has been of
significant research interest as it helps in identifying the unique and
distinguishing trait in each social media platform that contributes to its
continued existence. The comparison between the OSNs is insightful when it is
done based on the representative majority of the users holding active accounts
on all the platforms. In this research, we collected a set of user profiles
holding accounts on both Twitter and Instagram, these platforms being of
prominence among a majority of users. An extensive textual and visual analysis
on the media content posted by these users revealed that both these platforms
are indeed perceived differently at a fundamental level with Instagram engaging
more of the users' heart and Twitter capturing more of their mind. These
differences got reflected in almost every microscopic analysis done upon the
linguistic, topical and visual aspects.


title: Bikei Homology

abstract:
  We introduce a modified homology and cohomology theory for involutory
biquandles (also known as \textit{bikei}). We use bikei 2-cocycles to enhance
the bikei counting invariant for unoriented knots and links as well as
unoriented and non-orientable knotted surfaces in $\mathbb{R}^4$.


title: Multilayer optical calculations

abstract:
  When light hits a multilayer planar stack, it is reflected, refracted, and
absorbed in a way that can be derived from the Fresnel equations. The analysis
is treated in many textbooks, and implemented in many software programs, but
certain aspects of it are difficult to find explicitly and consistently worked
out in the literature. Here, we derive the formulas underlying the
transfer-matrix method of calculating the optical properties of these stacks,
including oblique-angle incidence, absorption-vs-position profiles, and
ellipsometry parameters. We discuss and explain some strange consequences of
the formulas in the situation where the incident and/or final (semi-infinite)
medium are absorptive, such as calculating $T>1$ in the absence of gain. We
also discuss some implementation details like complex-plane branch cuts.
Finally, we derive modified formulas for including one or more "incoherent"
layers, i.e. very thick layers in which interference can be neglected. This
document was written in conjunction with the "tmm" Python software package,
which implements these calculations.


title: Kinks in two-phase lipid bilayer membranes

abstract:
  Common models for two-phase lipid bilayer membranes are based on an energy
that consists of an elastic term for each lipid phase and a line energy at
interfaces. Although such an energy controls only the length of interfaces, the
membrane surface is usually assumed to be at least $C^1$ across phase
boundaries. We consider the spontaneous curvature model for closed rotationally
symmetric two-phase membranes without excluding tangent discontinuities at
interfaces a priorily. We introduce a family of energies for smooth surfaces
and phase fields for the lipid phases and derive a sharp interface limit that
coincides with the $\Gamma$-limit on all reasonable membranes and extends the
classical model by assigning a bending energy also to tangent discontinuities.
The theoretical result is illustrated by numerical examples.


title: Baryons and the Borromeo

abstract:
  The kernels in the tangible matter of our everyday experience are composed of
light quarks. At least, they are light classically; but they don't remain
light. Dynamical effects within the Standard Model of Particle Physics change
them in remarkable ways, so that in some configurations they appear nearly
massless, but in others possess masses on the scale of light nuclei. Modern
experiment and theory are exposing the mechanisms responsible for these
remarkable transformations. The rewards are great if we can combine the
emerging sketches into an accurate picture of confinement, which is such a
singular feature of the Standard Model; and looming larger amongst the emerging
ideas is a perspective that leads to a Borromean picture of the proton and its
excited states.


title:
Global stability in some one-dimensional non-autonomous discrete
  periodic population models

abstract:
  For some one-dimensional discrete-time autonomous population models, local
stability implies global stability of the positive equilibrismo point. One of
the known techniques is the enveloping method. In this paper we extend the
enveloping method to one single periodic population models. We show that, under
certain conditions, "individual enveloping" implies "periodic enveloping" in
one-dimensional periodic population models.


title:
Computational complexity of exterior products and multi-particle
  amplitudes of non-interacting fermions in entangled states

abstract:
  Noninteracting bosons were proposed to be used for a demonstration of
quantum-computing supremacy in a boson-sampling setup. A similar demonstration
with fermions would require that the fermions are initially prepared in an
entangled state. I suggest that pairwise entanglement of fermions would be
sufficient for this purpose. Namely, it is shown that computing multi-particle
scattering amplitudes for fermions entangled pairwise in groups of four
single-particle states is #P hard. In linear algebra, such amplitudes are
expressed as exterior products of two-forms of rank two. In particular, a
permanent of a NxN matrix may be expressed as an exterior product of N^2
two-forms of rank two in dimension 2N^2, which establishes the #P-hardness of
the latter.


title: Two types of invariant Subspaces in the polydisc

abstract:
  It is known that the structure of invariant subspaces of the Hardy space
$H^2(\mathbb D^n)$ on the polydisc $\mathbb{D}^n$ is very complicated; hence,
we need good examples help us to understand the structure of invariant
subspaces of $H^2(\mathbb D^n)$. In this paper, we define two types of
invariant subspaces of $H^2(\mathbb D^n)$. Then, we give a characterization of
these types invariant subspaces in view of the Beurling-Lax-Halmos Theorem.
Unitary equivalence is also studied in this paper.


title: Coherent excited states in superconductors due to a microwave field

abstract:
  We describe theoretically the depairing effect of a microwave field on
diffusive s-wave superconductors. The ground state of the superconductor is
altered qualitatively in analogy to the depairing due to a dc current. In
contrast to dc-depairing the density of states acquires, for microwaves with
frequency $\omega_0$, steps at multiples of the photon energy $\Delta\pm
n\hbar\omega_0$ and shows an exponential-like tail in the subgap regime. We
show that this ac-depairing explains the measured frequency shift of a
superconducting resonator with microwave power at low temperatures.


title: Efficient Authentication of Outsourced String Similarity Search

abstract:
  Cloud computing enables the outsourcing of big data analytics, where a third
party server is responsible for data storage and processing. In this paper, we
consider the outsourcing model that provides string similarity search as the
service. In particular, given a similarity search query, the service provider
returns all strings from the outsourced dataset that are similar to the query
string. A major security concern of the outsourcing paradigm is to authenticate
whether the service provider returns sound and complete search results. In this
paper, we design AutoS3, an authentication mechanism of outsourced string
similarity search. The key idea of AutoS3 is that the server returns a
verification object VO to prove the result correctness. First, we design an
authenticated string indexing structure named MBtree for VO construction.
Second, we design two lightweight authentication methods named VS2 and EVS2
that can catch the service provider various cheating behaviors with cheap
verification cost. Moreover, we generalize our solution for top k string
similarity search. We perform an extensive set of experiment results on real
world datasets to demonstrate the efficiency of our approach.


title:
Charge transfer and electron-phonon coupling in monolayer FeSe on Nb
  doped SrTiO$_3$

abstract:
  Monolayer films of FeSe grown on SrTiO$_3$ substrates are electron doped
relative to bulk and exhibit a significantly higher superconducting transition
temperatures. We present density functional calculations and a modified
Schottky model incorporating the strong paraelectricity of SrTiO$_3$ which
demonstrate that the doping may be due to charge transfer from SrTiO$_3$
impurity bands driven by work function mismatch. Physically relevant levels of
Nb doping are shown to lead to doping of the FeSe compatible with observation.
The coupling of electrons in FeSe to polar phonons in the depletion regime of
the SrTiO$_3$ is calculated. A $\lambda\sim 0.4$ is found; the coupling to
long-wavelength phonons is found to be dominant.


title: Revisiting Active Perception

abstract:
  Despite the recent successes in robotics, artificial intelligence and
computer vision, a complete artificial agent necessarily must include active
perception. A multitude of ideas and methods for how to accomplish this have
already appeared in the past, their broader utility perhaps impeded by
insufficient computational power or costly hardware. The history of these
ideas, perhaps selective due to our perspectives, is presented with the goal of
organizing the past literature and highlighting the seminal contributions. We
argue that those contributions are as relevant today as they were decades ago
and, with the state of modern computational tools, are poised to find new life
in the robotic perception systems of the next decade.


title: A note on the kernel of a pair of linear maps

abstract:
  The kernel of a pair of linear systems is studied in the framework of
commutative ring theory with applications to behavioral perspective of linear
systems


title: Support and Rank Varieties of Totally Acyclic Complexes

abstract:
  Support and rank varieties of modules over a group algebra of an elementary
abelian p-group have been well studied. In particular, Avrunin and Scott showed
that in this setting, the rank and support varieties are equivalent. Avramov
and Buchweitz proved an analogous result for pairs of modules over arbitrary
commutative local complete intersection rings. In this paper we study support
and rank varieties in the triangulated category of totally acyclic chain
complexes over a complete intersection ring and show that these varieties are
also equivalent.


title:
SGO: An ultrafast engine for ab initio atomic structure global
  optimization by differential evolution

abstract:
  This paper presents a fast method for global search of atomic structures at
ab initio level. The structures global optimization (SGO) engine consists of a
high-efficiency differential evolution algorithm, accelerated local relaxation
methods and an ultrafast plane-wave density functional theory code run on GPU
machines. It can search the global-minimum configurations of crystals,
two-dimensional materials and quantum clusters without symmetry restriction in
a very short time (half or several hours). The engine is also able to search
the energy landscape of a given system, which is useful for exploration of
materials properties for emerging applications. The exploration of carbon
monolayer and platinum atomic clusters found several new stable configurations.


title:
Spatial conductivity mapping of unprotected and capped black phosphorus
  using microwave microscopy

abstract:
  Thin layers of black phosphorus present an ideal combination of a 2D material
with a tunable direct bandgap and high carrier mobility. However the material
suffers from degradation in ambient conditions due to an oxidation reaction
which involves water, oxygen and light. We have measured the spatial profile of
the conductivity on flakes of black phosphorus as a function of time using
scanning microwave impedance microscopy. A microwave excitation (3 GHz) allows
to image a conducting sample even when covered with a dielectric layer. We
observe that on bare black phosphorus, the conductivity changes drastically
over the whole surface within a day. We demonstrate that the degradation
process is slowed down considerably by covering the material with a 10 nm layer
of hafnium oxide. It is stable for more than a week, opening up a route towards
stable black phosphorus devices in which the high dielectric constant of
hafnium oxide can be exploited. Covering black phosphorus with a 15 nm boron
nitride flake changes the degradation process qualitatively, it is dominated by
the edges of the flake indicating a diffusive process and happens on the scale
of days.


title:
Codebook Design for Millimeter-Wave Channel Estimation with Hybrid
  Precoding Structure

abstract:
  In this paper, we study hierarchical codebook design for channel estimation
in millimeter-wave (mmWave) communications with a hybrid precoding structure.
Due to the limited saturation power of mmWave power amplifier (PA), we take the
per-antenna power constraint (PAPC) into consideration. We first propose a
metric, i.e., generalized detection probability (GDP), to evaluate the quality
of \emph{an arbitrary codeword}. This metric not only enables an optimization
approach for mmWave codebook design, but also can be used to compare the
performance of two different codewords/codebooks. To the best of our knowledge,
GDP is the first metric particularly for mmWave codebook design for channel
estimation. We then propose an approach to design a hierarchical codebook
exploiting BeaM Widening with Multi-RF-chain Sub-array technique (BMW-MS). To
obtain crucial parameters of BMW-MS, we provide two solutions, namely a
low-complexity search (LCS) solution to optimize the GDP metric and a
closed-form (CF) solution to pursue a flat beam pattern. Performance
comparisons show that BMW-MS/LCS and BMW-MS/CF achieve very close performances,
and they outperform the existing alternatives under the PAPC.


title: High efficiency dielectric metasurfaces at visible wavelengths

abstract:
  Metasurfaces are planar optical elements that hold promise for overcoming the
limitations of refractive and conventional diffractive optics1-3. Dielectric
metasurfaces demonstrated thus far4-10 are limited to transparency windows at
infrared wavelengths because of significant optical absorption and loss at
visible wavelengths. It is critical that new materials and fabrication
techniques be developed for dielectric metasurfaces at visible wavelengths to
enable applications such as three-dimensional displays, wearable optics and
planar optical systems11. Here, we demonstrate high performance titanium
dioxide dielectric metasurfaces in the form of holograms for red, green and
blue wavelengths with record absolute efficiency (>78%). We use atomic layer
deposition of amorphous titanium dioxide that exhibits low surface roughness of
0.738 nm and ideal optical properties. To fabricate the metasurfaces we use a
lift-off-like process that allows us to produce highly anisotropic nanofins
with shape birefringence. This process is applicable to any optical element and
can be implemented using a broad class of materials.


title: Discriminative models for robust image classification

abstract:
  A variety of real-world tasks involve the classification of images into
pre-determined categories. Designing image classification algorithms that
exhibit robustness to acquisition noise and image distortions, particularly
when the available training data are insufficient to learn accurate models, is
a significant challenge. This dissertation explores the development of
discriminative models for robust image classification that exploit underlying
signal structure, via probabilistic graphical models and sparse signal
representations.
  Probabilistic graphical models are widely used in many applications to
approximate high-dimensional data in a reduced complexity set-up. Learning
graphical structures to approximate probability distributions is an area of
active research. Recent work has focused on learning graphs in a discriminative
manner with the goal of minimizing classification error. In the first part of
the dissertation, we develop a discriminative learning framework that exploits
the complementary yet correlated information offered by multiple
representations (or projections) of a given signal/image. Specifically, we
propose a discriminative tree-based scheme for feature fusion by explicitly
learning the conditional correlations among such multiple projections in an
iterative manner. Experiments reveal the robustness of the resulting graphical
model classifier to training insufficiency.


title:
Vertex-algebraic structure of principal subspaces of the basic modules
  for twisted Affine Kac-Moody Lie algebras of type $A_{2n-1}^{(2)}, D_n^{(2)},
  E_6^{(2)}$

abstract:
  We obtain a presentation of principal subspaces of basic modules for the
twisted affine Kac-Moody Lie algebras of type $A_{2n-1}^{(2)}$, $D_n^{(2)}$ and
$E_6^{(2)}$. Using this presentation, we construct exact sequences among these
principal subspaces, and use these exact sequences to obtain recursions
satisfied by graded dimensions of the principal subspaces. Solving these
recursions, we obtain the graded dimensions of the principal subspaces.


title: Learning to Blend Computer Game Levels

abstract:
  We present an approach to generate novel computer game levels that blend
different game concepts in an unsupervised fashion. Our primary contribution is
an analogical reasoning process to construct blends between level design models
learned from gameplay videos. The models represent probabilistic relationships
between elements in the game. An analogical reasoning process maps features
between two models to produce blended models that can then generate new level
chunks. As a proof-of-concept we train our system on the classic platformer
game Super Mario Bros. due to its highly-regarded and well understood level
design. We evaluate the extent to which the models represent stylistic level
design knowledge and demonstrate the ability of our system to explain levels
that were blended by human expert designers.


title:
Solving the "Magic Angle" Challenge in Determining Molecular Orientation
  at Interfaces

abstract:
  We introduce a novel method to determine the orientation heterogeneity (mean
tilt angle and orientational distribution) of molecules at interfaces using
heterodyne two-dimensional sum frequency generation spectroscopy. By doing so,
we not only have solved the long-standing "magic angle" challenge, i.e. the
measurement of molecular orientation by assuming a narrow orientational
distribution results in ambiguities, but we also are able to determine the
orientational distribution, which is otherwise difficult to measure. We applied
our new method to a CO2 reduction catalyst/gold interface and found that the
catalysts formed a monolayer with a mean tilt angle between the quasi-C3
symmetric axis of the catalysts and the surface normal of 53 deg, with 5 deg
orientational distribution. Although applied to a specific system, this method
is a general way to determine the orientation heterogeneity of an
ensemble-averaged molecular interface, which can potentially be applied to a
wide-range of energy material, catalytic and biological interfaces.


title: Pairwise Choice Markov Chains

abstract:
  As datasets capturing human choices grow in richness and scale --
particularly in online domains -- there is an increasing need for choice models
that escape traditional choice-theoretic axioms such as regularity, stochastic
transitivity, and Luce's choice axiom. In this work we introduce the Pairwise
Choice Markov Chain (PCMC) model of discrete choice, an inferentially tractable
model that does not assume any of the above axioms while still satisfying the
foundational axiom of uniform expansion, a considerably weaker assumption than
Luce's choice axiom. We show that the PCMC model significantly outperforms the
Multinomial Logit (MNL) model in prediction tasks on both synthetic and
empirical datasets known to exhibit violations of Luce's axiom. Our analysis
also synthesizes several recent observations connecting the Multinomial Logit
model and Markov chains; the PCMC model retains the Multinomial Logit model as
a special case.


title: Baryon Octet Electromagnetic Form Factors in a confining NJL model

abstract:
  Electromagnetic form factors of the baryon octet are studied using a
Nambu--Jona-Lasinio model which utilizes the proper-time regularization scheme
to simulate aspects of colour confinement. In addition, the model also
incorporates corrections to the dressed quarks from vector meson correlations
in the t-channel and the pion cloud. Comparison with recent chiral
extrapolations of lattice QCD results shows a remarkable level of consistency.
For the charge radii we find the surprising result $r_{E}^p < r_{E}^{\Sigma^+}$
and $|r_{E}^n| < |r_{E}^{\Xi^0}|$, whereas the magnetic radii have a pattern
largely consistent with a naive expectation based on the dressed quark masses.


title: Modeling the photoacoustic signal during the porous silicon formation

abstract:
  Within this work, the kinetics of the growing stage of porous silicon (PS)
during the etching process was studied using the photoacoustic technique. A
p-type Si with low resistivity was used as a substrate. An extension of
Rosencwaig and Gersho model is proposed in order to analyze the temporary
changes that take place in the amplitude of the photoacoustic signal during the
PS growth. The solution of the heat equation takes into account the modulated
laser beam, the changes in the reflectance of the PS-backing heterostructure,
the electrochemical reaction, and the Joule effect as thermal sources. The
model includes the time-dependence of the sample thickness during the
electrochemical etching of PS. The changes in the reflectance are identified as
the laser reflections in the internal layers of the system. The reflectance is
modeled by an additional sinusoidal-monochromatic light source and its
modulated frequency is related to the velocity of the PS growth. The chemical
reaction and the DC components of the heat sources are taken as an average
value from the experimental data. The theoretical results are in agreement with
the experimental data and hence provided a method to determine variables of the
PS growth, such as the etching velocity and the thickness of the porous layer
during the growing process.


title:
Computing AIC for black-box models using Generalised Degrees of Freedom:
  a comparison with cross-validation

abstract:
  Generalised Degrees of Freedom (GDF), as defined by Ye (1998 JASA
93:120-131), represent the sensitivity of model fits to perturbations of the
data. As such they can be computed for any statistical model, making it
possible, in principle, to derive the number of parameters in machine-learning
approaches. Defined originally for normally distributed data only, we here
investigate the potential of this approach for Bernoulli-data. GDF-values for
models of simulated and real data are compared to model complexity-estimates
from cross-validation. Similarly, we computed GDF-based AICc for randomForest,
neural networks and boosted regression trees and demonstrated its similarity to
cross-validation. GDF-estimates for binary data were unstable and
inconsistently sensitive to the number of data points perturbed simultaneously,
while at the same time being extremely computer-intensive in their calculation.
Repeated 10-fold cross-validation was more robust, based on fewer assumptions
and faster to compute. Our findings suggest that the GDF-approach does not
readily transfer to Bernoulli data and a wider range of regression approaches.


title:
Coupling vs decoupling approaches for PDE/ODE systems modeling
  intercellular signaling

abstract:
  We consider PDE/ODE systems for the simulation of intercellular signaling in
multicellular environments. The intracellular processes for each cell described
here by ODEs determine the long-time dynamics, but the PDE part dominates the
solving effort. Thus, it is not clear if commonly used decoupling methods can
outperform a coupling approach. Based on a sensitivity analysis, we present a
systematic comparison between coupling and decoupling approaches for this class
of problems and show numerical results. For biologically relevant
configurations of the model, our quantitative study shows that a coupling
approach performs much better than a decoupling one.


title: Non-parametric latent modeling and network clustering

abstract:
  The paper exposes a non-parametric approach to latent and co-latent modeling
of bivariate data, based upon alternating minimization of the Kullback-Leibler
divergence (EM algorithm) for complete log-linear models. For categorical data,
the iterative algorithm generates a soft clustering of both rows and columns of
the contingency table. Well-known results are systematically revisited, and
some variants are presumably original. In particular, the consideration of
square contingency tables induces a clustering algorithm for weighted networks,
differing from spectral clustering or modularity maximization techniques. Also,
we present a co-clustering algorithm applicable to HMM models of general kind,
distinct from the Baum-Welch algorithm. Three case studies illustrate the
theory.


title: The imprint of the analogue Hawking effect in subcritical flows

abstract:
  We study the propagation of low frequency shallow water waves on a one
dimensional flow of varying depth. When taking into account dispersive effects,
the linear propagation of long wavelength modes on uneven bottoms excites new
solutions of the dispersion relation which possess a much shorter wavelength.
The peculiarity is that one of these new solutions has a negative energy. When
the flow becomes supercritical, this mode has been shown to be responsible for
the (classical) analog of the Hawking effect. For subcritical flows, the
production of this mode has been observed numerically and experimentally, but
the precise physics governing the scattering remained unclear. In this work, we
provide an analytic treatment of this effect in subcritical flows. We analyze
the scattering of low frequency waves using a new perturbative series, derived
from a generalization of the Bremmer series. We show that the production of
short wavelength modes is governed by a complex value of the position: a
complex turning point. Using this method, we investigate various flow profiles,
and derive the main characteristics of the induced spectrum.


title: Hamiltonian-Based Algorithm for Optimal Control

abstract:
  This paper proposes an algorithmic technique for a class of optimal control
problems where it is easy to compute a pointwise minimizer of the Hamiltonian
associated with every applied control. The algorithm operates in the space of
relaxed controls and projects the final result into the space of ordinary
controls. It is based on the descent direction from a given relaxed control
towards a pointwise minimizer of the Hamiltonian. This direction comprises a
form of gradient projection and for some systems, is argued to have
computational advantages over direct gradient directions. The algorithm is
shown to be applicable to a class of hybrid optimal control problems. The
theoretical results, concerning convergence of the algorithm, are corroborated
by simulation examples on switched-mode hybrid systems as well as on a problem
of balancing transmission- and motion energy in a mobile robotic system.


title:
Renormalization and periods in perturbative Algebraic Quantum Field
  Theory

abstract:
  In this paper I give an overview of mathematical structures appearing in
perturbative algebraic quantum field theory (pAQFT) in the case of the massless
scalar field on Minkowski spacetime. I also show how these relate to
Kontsevich-Zagier periods. Next, I review the pAQFT version of the
renormalization group flow and reformulate it in terms of Feynman graphs. This
allows me to relate Kontsevich-Zagier periods to numbers appearing in computing
the pAQFT $\beta$-function.


title: Topological strength of magnetic skyrmions

abstract:
  We deal with magnetic structures that attain integer and half-integer
skyrmion numbers. We model and solve the problem analytically, and show how the
solutions appear in materials that engender distinct, very specific physical
properties, and use them to describe their topological features. In particular,
we found a way to model skyrmion with a large transition region correlated with
the presence of a two-peak skyrmion number density. Moreover, we run into the
issue concerning the topological strength of a vortex-like structure and
suggest an experimental realization, important to decide how to modify and
measure the topological strength of the magnetic structure.


title:
Extended Magnetic Exchange Interactions in the High-Temperature
  Ferromagnet MnBi

abstract:
  The high-temperature ferromagnet MnBi continues to receive attention as a
candidate to replace rare-earth-containing permanent magnets in applications
above room temperature. This is due to a high Curie temperature, large magnetic
moments, and a coercivity that increases with temperature. The synthesis of
MnBi also allows for crystals that are free of interstitial Mn, enabling more
direct access to the key interactions underlying the physical properties of
binary Mn-based ferromagnets. In this work, we use inelastic neutron scattering
to measure the spin waves of MnBi in order to characterize the magnetic
exchange at low temperature. Consistent with the spin reorientation that occurs
below 140 K, we do not observe a spin gap in this system above our experimental
resolution. A Heisenberg model was fit to the spin wave data in order to
characterize the long-range nature of the exchange. It was found that
interactions up to sixth nearest neighbor are required to fully parameterize
the spin waves. Surprisingly, the nearest-neighbor term is antiferromagnetic,
and the realization of a ferromagnetic ground state relies on the more numerous
ferromagnetic terms beyond nearest neighbor, suggesting that the ferromagnetic
ground state arises as a consequence of the long-ranged interactions in the
system.


title:
Radio Synchrotron Fluctuation Statistics as a Probe of Magnetized
  Interstellar Turbulence

abstract:
  We investigate how observations of synchrotron intensity fluctuations can be
used to probe the sonic and Alfv\'enic Mach numbers of interstellar turbulence,
based on mock observations performed on simulations of magnetohydrodynamic
turbulence. We find that the structure function slope, and a diagnostic of
anisotropy that we call the integrated quadrupole ratio modulus, both depend on
the Alfv\'enic Mach number. However, these statistics also depend on the
orientation of the mean magnetic field in the synchrotron emitting region
relative to our line of sight, and this creates a degeneracy that cannot be
broken by observations of synchrotron intensity alone. We conclude that the
polarization of synchrotron emission could be analyzed to break this
degeneracy, and suggest that this will be possible with the Square Kilometre
Array.


title: Best-of-K Bandits

abstract:
  This paper studies the Best-of-K Bandit game: At each time the player chooses
a subset S among all N-choose-K possible options and observes reward max(X(i) :
i in S) where X is a random vector drawn from a joint distribution. The
objective is to identify the subset that achieves the highest expected reward
with high probability using as few queries as possible. We present
distribution-dependent lower bounds based on a particular construction which
force a learner to consider all N-choose-K subsets, and match naive extensions
of known upper bounds in the bandit setting obtained by treating each subset as
a separate arm. Nevertheless, we present evidence that exhaustive search may be
avoided for certain, favorable distributions because the influence of
high-order order correlations may be dominated by lower order statistics.
Finally, we present an algorithm and analysis for independent arms, which
mitigates the surprising non-trivial information occlusion that occurs due to
only observing the max in the subset. This may inform strategies for more
general dependent measures, and we complement these result with independent-arm
lower bounds.


title: Symplectic and Poisson derived geometry and deformation quantization

abstract:
  We review recent results and ongoing investigations of the symplectic and
Poisson geometry of derived moduli spaces, and describe applications to
deformation quantization of such spaces.


title: XGBoost: A Scalable Tree Boosting System

abstract:
  Tree boosting is a highly effective and widely used machine learning method.
In this paper, we describe a scalable end-to-end tree boosting system called
XGBoost, which is used widely by data scientists to achieve state-of-the-art
results on many machine learning challenges. We propose a novel sparsity-aware
algorithm for sparse data and weighted quantile sketch for approximate tree
learning. More importantly, we provide insights on cache access patterns, data
compression and sharding to build a scalable tree boosting system. By combining
these insights, XGBoost scales beyond billions of examples using far fewer
resources than existing systems.


title: Neutrino emission, Equation of State and the role of strong gravity

abstract:
  Neutron-star mergers are interesting for several reasons: they are proposed
as the progenitors of short gamma-ray bursts, they have been speculated to be a
site for the synthesis of heavy elements, and they emit gravitational waves
possibly detectable at terrestrial facilities. The understanding of the merger
process, from the pre-merger stage to the final compact object-accreting system
involves detailed knowledge of numerical relativity and nuclear physics. In
particular, key ingredients for the evolution of the merger are neutrino
physics and the matter equation of state. We present some aspects of neutrino
emission from binary neutron star mergers showing the impact that the equation
of state has on neutrinos and discuss some spectral quantities relevant to
their detection such as energies and luminosities far from the source.


title: Mechanical EPR entanglement with a finite-bandwidth squeezed reservoir

abstract:
  We describe a scheme for entangling mechanical resonators which is efficient
also beyond the resolved sideband regime. It employs the radiation pressure
force of the squeezed light produced by a degenerate optical parametric
oscillator, which acts as a reservoir of quantum correlations (squeezed
reservoir), and it is effective when the spectral bandwidth of the reservoir
and the fields frequencies are appropriately selected. It allows for the steady
state preparation of mechanical resonatrs in entangled EPR states and can be
extended to the preparation of many entangled pairs of resonators which
interact with the same light field, in a situation in which the optomechanical
system realizes a star-like harmonic network.


title: Permutation p-value approximation via generalized Stolarsky invariance

abstract:
  It is common for genomic data analysis to use $p$-values from a large number
of permutation tests. The multiplicity of tests may require very tiny
$p$-values in order to reject any null hypotheses and the common practice of
using randomly sampled permutations then becomes very expensive. We propose an
inexpensive approximation to $p$-values for two sample linear test statistics,
derived from Stolarsky's invariance principle. The method creates a
geometrically derived set of approximate $p$-values for each hypothesis. The
average of that set is used as a point estimate $\hat p$ and our generalization
of the invariance principle allows us to compute the variance of the $p$-values
in that set. We find that in cases where the point estimate is small the
variance is a modest multiple of the square of the point estimate, yielding a
relative error property similar to that of saddlepoint approximations. On a
Parkinson's disease data set, the new approximation is faster and more accurate
than the saddlepoint approximation. We also obtain a simple probabilistic
explanation of Stolarsky's invariance principle.


title:
Strong monogamy of multi-party quantum entanglement for partially
  coherently superposed states

abstract:
  We provide an evidence for the validity of strong monogamy inequality of
multi-party quantum entanglement using square of convex-roof extended
negativity(SCREN). We first consider a large class of multi-qudit mixed state
that are in a partially coherent superposition of a generalized W-class state
and the vacuum, and provide some useful properties about this class of states.
We show that monogamy inequality of multi-qudit entanglement in terms of SCREN
holds for this class of states. We further show that SCREN strong monogamy
inequality of multi-qudit entanglement also holds for this class of states.
Thus SCREN is a good alternative to characterize the monogamous and strongly
monogamous properties of multi-qudit entanglement.


title:
Improvement on Fermionic properties and new isotope production in
  molecular dynamics simulations

abstract:
  By considering momentum transfer in the Fermi constraint procedure, the
stability of the initial nuclei and fragments produced in heavy-ion collisions
can be further improved in the quantum molecular dynamics simulations. The case
of the phase space occupation probability larger than one is effectively
reduced with the proposed procedure. Simultaneously, the energy conservation
can be better described for both individual nuclei and heavy-ion reactions.
With the revised version of the improved quantum molecular dynamics (ImQMD)
model, the fusion excitation functions of $^{16}$O+$^{186}$W and the central
collisions of Au+Au at 35 AMeV are re-examined. The fusion cross sections at
sub-barrier energies and the charge distribution of fragments are relatively
better reproduced due to the reduction of spurious nucleon emission. The charge
and isotope distribution of fragments in Xe+Sn, U+U and Zr+Sn at intermediate
energies are also predicted. More unmeasured extremely neutron-rich fragments
with $Z=16-28$ are observed in the central collisions of $^{238}$U+$^{238}$U
than that of $^{96}$Zr+$^{124}$Sn, which indicates that multi-fragmentation of
U+U may offer a fruitful pathway to new neutron-rich isotopes.


title:
Generalized entanglement constraints in multi-qubit systems in terms of
  Tsallis entropy

abstract:
  We provide generalized entanglement constraints in multi-qubit systems in
terms of Tsallis entropy. Using quantum Tsallis entropy of order $q$, we first
provide a generalized monogamy inequality of multi-qubit entanglement for $q=2$
or $3$. This generalization encapsulates multi-qubit CKW-type inequality as a
special case. We further provide a generalized polygamy inequality of
multi-qubit entanglement in terms of Tsallis-$q$ entropy for $1 \leq q \leq2$
or $3 \leq q \leq 4$, which also contains the multi-qubit polygamy inequality
as a special case.


title: On tangent cones at infinity of algebraic varieties

abstract:
  In this paper, we establish the following version at infinity of Whitney's
theorem [6, 7]: Geometric and algebraic tangent cones at infinity of complex
algebraic varieties coincide. The proof of this fact is based on a geometric
characterization of geometric tangent cones at infinity and using the global \L
ojasiewicz inequality with explicit exponents for complex algebraic varieties.
We also show that tangent cones at infinity of complex algebraic varieties can
be computed using Gr\"obner bases.


title:
Suppression of spin-exciton state in hole overdoped iron-based
  superconductors

abstract:
  The mechanism of Cooper pair formation in iron-based superconductors remains
a controversial topic. The main question is whether spin or orbital
fluctuations are responsible for the pairing mechanism. To solve this problem,
a crucial clue can be obtained by examining the remarkable enhancement of
magnetic neutron scattering signals appearing in a superconducting phase. The
enhancement is called spin resonance for a spin fluctuation model, in which
their energy is restricted below twice the superconducting gap value (2Ds),
whereas larger energies are possible in other models such as an orbital
fluctuation model. Here we report the doping dependence of low-energy magnetic
excitation spectra in Ba1-xKxFe2As2 for 0.5<x<0.84 studied by inelastic neutron
scattering. We find that the behavior of the spin resonance dramatically
changes from optimum to overdoped regions. Strong resonance peaks are observed
clearly below 2Ds in the optimum doping region, while they are absent in the
overdoped region. Instead, there is a transfer of spectral weight from energies
below 2Ds to higher energies, peaking at values of 3Ds for x = 0.84. These
results suggest a reduced impact of magnetism on Cooper pair formation in the
overdoped region.


title: megaman: Manifold Learning with Millions of points

abstract:
  Manifold Learning is a class of algorithms seeking a low-dimensional
non-linear representation of high-dimensional data. Thus manifold learning
algorithms are, at least in theory, most applicable to high-dimensional data
and sample sizes to enable accurate estimation of the manifold. Despite this,
most existing manifold learning implementations are not particularly scalable.
Here we present a Python package that implements a variety of manifold learning
algorithms in a modular and scalable fashion, using fast approximate neighbors
searches and fast sparse eigendecompositions. The package incorporates
theoretical advances in manifold learning, such as the unbiased Laplacian
estimator and the estimation of the embedding distortion by the Riemannian
metric method. In benchmarks, even on a single-core desktop computer, our code
embeds millions of data points in minutes, and takes just 200 minutes to embed
the main sample of galaxy spectra from the Sloan Digital Sky Survey ---
consisting of 0.6 million samples in 3750-dimensions --- a task which has not
previously been possible.


title:
Distributed Control for Charging Multiple Electric Vehicles with
  Overload Limitation

abstract:
  Severe pollution induced by traditional fossil fuels arouses great attention
on the usage of plug-in electric vehicles (PEVs) and renewable energy. However,
large-scale penetration of PEVs combined with other kinds of appliances tends
to cause excessive or even disastrous burden on the power grid, especially
during peak hours. This paper focuses on the scheduling of PEVs charging
process among different charging stations and each station can be supplied by
both renewable energy generators and a distribution network. The distribution
network also powers some uncontrollable loads. In order to minimize the on-grid
energy cost with local renewable energy and non-ideal storage while avoiding
the overload risk of the distribution network, an online algorithm consisting
of scheduling the charging of PEVs and energy management of charging stations
is developed based on Lyapunov optimization and Lagrange dual decomposition
techniques. The algorithm can satisfy the random charging requests from PEVs
with provable performance. Simulation results with real data demonstrate that
the proposed algorithm can decrease the time-average cost of stations while
avoiding overload in the distribution network in the presence of random
uncontrollable loads.


title: Finite type modules and Bethe Ansatz for quantum toroidal gl(1)

abstract:
  We study highest weight representations of the Borel subalgebra of the
quantum toroidal gl(1) algebra with finite-dimensional weight spaces. In
particular, we develop the q-character theory for such modules. We introduce
and study the subcategory of `finite type' modules. By definition, a module
over the Borel subalgebra is finite type if the Cartan like current \psi^+(z)
has a finite number of eigenvalues, even though the module itself can be
infinite dimensional.
  We use our results to diagonalize the transfer matrix T_{V,W}(u;p) analogous
to those of the six vertex model. In our setting T_{V,W}(u;p) acts in a tensor
product W of Fock spaces and V is a highest weight module over the Borel
subalgebra of quantum toroidal gl(1) with finite-dimensional weight spaces.
Namely we show that for a special choice of finite type modules $V$ the
corresponding transfer matrices, Q(u;p) and T(u;p), are polynomials in u and
satisfy a two-term TQ relation. We use this relation to prove the Bethe Ansatz
equation for the zeroes of the eigenvalues of Q(u;p). Then we show that the
eigenvalues of T_{V,W}(u;p) are given by an appropriate substitution of
eigenvalues of Q(u;p) into the q-character of V.


title:
Leveraging Crowd for Game-based Learning: A Case Study of Privacy
  Education Game Design and Evaluation by Crowdsourcing

abstract:
  As the Internet grows in importance, it is vital to develop methods and
techniques for educating end-users to improve their awareness of online
privacy. Web-based education tools have been proven effective in many domains
and have been increasingly adopted by many online professional and educational
services. However, the design and development of Web-based education tools for
online privacy is still in the early stage. The traditional solutions always
involve privacy experts who have sophisticated expertise. Such involvement can
make the tool development costly. Furthermore, it is not clear how inspiring
and effective these education tools are to general users of varying
backgrounds, specially to novice users who have rarely dealt with online
privacy issues before. In this paper, we design, develop, and evaluate a
game-based privacy learning system by leveraging the wisdom of a crowd of
non-experts on Amazon Mechanic Turk. Empirical study demonstrates that the
crowd can provide high-quality ideas of designing and developing a practical,
educational privacy learning game.


title:
The Landscape of Domain Name Typosquatting: Techniques and
  Countermeasures

abstract:
  With more than 294 million registered domain names as of late 2015, the
domain name ecosystem has evolved to become a cornerstone for the operation of
the Internet. Domain names today serve everyone, from individuals for their
online presence to big brands for their business operations. Such ecosystem
that facilitated legitimate business and personal uses has also fostered
"creative" cases of misuse, including phishing, spam, hit and traffic stealing,
online scams, among others. As a first step towards this misuse, the
registration of a legitimately-looking domain is often required. For that,
domain typosquatting provides a great avenue to cybercriminals to conduct their
crimes.
  In this paper, we review the landscape of domain name typosquatting,
highlighting models and advanced techniques for typosquatted domain names
generation, models for their monetization, and the existing literature on
countermeasures. We further highlight potential fruitful directions on
technical countermeasures that are lacking in the literature.


title: The low-energy N=4 SYM effective action in diverse harmonic superspaces

abstract:
  We review various superspace approaches to the description of the low-energy
effective action in N=4 super Yang-Mills (SYM) theory. We consider the
four-derivative part of the low-energy effective action in the Coulomb branch.
The typical components of this effective action are the gauge field F^4/X^4 and
the scalar field Wess-Zumino terms. We construct N=4 supersymmetric completions
of these terms in the framework of different harmonic superspaces supporting
N=2,3,4 supersymmetries. These approaches are complementary to each other in
the sense that they make manifest different subgroups of the total SU(4)
R-symmetry group. We show that the effective action acquires an extremely
simple form in those superspaces which manifest the non-anomalous maximal
subgroups of SU(4). The common characteristic feature of our construction is
that we restore the superfield effective actions exclusively by employing the
N=4 supersymmetry and/or superconformal PSU(2,2|4) symmetry.


title:
The leptonic CP phase is determined by an equation involving the PMNS
  matrix elements

abstract:
  Several approximate equalities among the matrix elements of CKM and PMNS
imply that hidden symmetries may exist and be common for both quark and
neutrino sectors. The CP phase of the CKM matrix ($\delta_{\rm CKM}$) is
involved in these equalities and can be investigated when these equalities turn
into several equations. As we substitute those experimentally measured values
of the three mixing angles into the equations for quarks, it is noted that one
of the equations which holds exactly has a solution $\delta_{\rm
CKM}=68.95^\circ$. That value accords with $(69.1^{+2.02}_{-3.85})^\circ$
determined from available data. Generalizing the scenario to the lepton sector,
the same equality determines the leptonic CP phase $\delta_{\rm PMNS}$ to be $
276.10^\circ$. Thus we predict the value of $\delta_{\rm PMNS}$ from the
equation. So far there is no direct measurement on $\delta_{\rm PMNS}$ yet, but
a recent analysis based on the neutrino oscillation data prefers the phase
close to $270^\circ$.


title:
An ergodic algorithm for generating knots with a prescribed injectivity
  radius

abstract:
  The first algorithm for sampling the space of thick equilateral knots, as a
function of thickness, will be described. This algorithm is based on previous
algorithms of applying random reflections.
  To prove the existence of the algorithm, we describe a method for turning any
knot into the regular planar polygon using only thickness non-decreasing moves.
This approach ensures that the algorithm has a positive probability of
connecting any two knots with the required thickness constraint and so is
ergodic. This ergodic sampling unlocks the ability to analyze the effects of
thickness on properties of the geometric knot such as radius of gyration.
  This algorithm will be shown to be faster than previous methods for
generating thick knots, and the data from this algorithm shows that the radius
of gyration increases strongly with thickness and that the growth exponent for
radius of gyration increases with thickness.


title:
Atom-atom interactions around the band edge of a photonic crystal
  waveguide

abstract:
  Tailoring the interactions between quantum emitters and single photons
constitutes one of the cornerstones of quantum optics. Coupling a quantum
emitter to the band edge of a photonic crystal waveguide (PCW) provides a
unique platform for tuning these interactions. In particular, the crossover
from propagating fields $E(x) \propto e^{\pm ik_x x}$ outside the bandgap to
localized fields $E(x) \propto e^{-\kappa_x |x|}$ within the bandgap should be
accompanied by a transition from largely dissipative atom-atom interactions to
a regime where dispersive atom-atom interactions are dominant. Here, we
experimentally observe this transition for the first time by shifting the band
edge frequency of the PCW relative to the $\rm D_1$ line of atomic cesium for
$\bar{N}=3.0\pm 0.5$ atoms trapped along the PCW. Our results are the initial
demonstration of this new paradigm for coherent atom-atom interactions with low
dissipation into the guided mode.


title: Unscented External Force and Torque Estimation for Quadrotors

abstract:
  In this paper, we describe an algorithm, based on the well-known Unscented
Quaternion Estimator, to estimate external forces and torques acting on a
quadrotor. This formulation uses a non-linear model for the quadrotor dynamics,
naturally incorporates process and measurement noise, requires only a few
parameters to be tuned manually, and uses singularity-free unit quaternions to
represent attitude. We demonstrate in simulation that the proposed algorithm
can outperform existing methods. We then highlight how our approach can be used
to generate force and torque profiles from experimental data, and how this
information can later be used for controller design. Finally, we show how the
resulting controllers enable a quadrotor to stay in the wind field of a moving
fan.


title:
Onset, timing, and exposure therapy of stress disorders: mechanistic
  insight from a mathematical model of oscillating neuroendocrine dynamics

abstract:
  The hypothalamic-pituitary-adrenal (HPA) axis is a neuroendocrine system that
regulates numerous physiological processes. Disruptions in the activity of the
HPA axis are correlated with many stress-related diseases such as
post-traumatic stress disorder (PTSD) and major depressive disorder. In this
paper, we characterize "normal" and "diseased" states of the HPA axis as basins
of attraction of a dynamical system describing the inhibition of peptide
hormones such as corticotropin-releasing hormone (CRH) and adrenocorticotropic
hormone (ACTH) by circulating glucocorticoids such as cortisol (CORT). In
addition to including key physiological features such as ultradian oscillations
in cortisol levels and self-upregulation of CRH neuron activity, our model
distinguishes the relatively slow process of cortisol-mediated CRH biosynthesis
from rapid trans-synaptic effects that regulate the CRH secretion process.
Crucially, we find that the slow regulation mechanism mediates external
stress-driven transitions between the stable states in novel, intensity,
duration, and timing-dependent ways. These results indicate that the timing of
traumatic events may be an important factor in determining if and how patients
will exhibit hallmarks of stress disorders. Our model also suggests a mechanism
whereby exposure therapy of stress disorders such as PTSD may act to normalize
downstream dysregulation of the HPA axis.


title:
Mean-field study of hot beta-stable protoneutron star matter: Impact of
  the symmetry energy and nucleon effective mass

abstract:
  A consistent Hartree-Fock study of the equation of state (EOS) of asymmetric
nuclear matter at finite temperature has been performed using realistic choices
of the effective, density dependent nucleon-nucleon (NN) interaction, which
were successfully used in different nuclear structure and reaction studies.
Given the importance of the nuclear symmetry energy in the neutron star
formation, EOS's associated with different behaviors of the symmetry energy
were used to study hot asymmetric nuclear matter. The slope of the symmetry
energy and nucleon effective mass with increasing baryon density was found to
affect the thermal properties of nuclear matter significantly. Different
density dependent NN interactions were further used to study the EOS of hot
protoneutron star (PNS) matter of the $npe\mu\nu$ composition in
$\beta$-equilibrium. The hydrostatic configurations of PNS in terms of the
maximal gravitational mass $M_{\rm max}$ and radius, central density, pressure
and temperature at the total entropy per baryon $S/A= 1,2$ and 4 have been
determined in both the neutrino-free and neutrino-trapped scenarios. The
obtained results show consistently a strong impact of the symmetry energy and
nucleon effective mass on thermal properties and composition of hot PNS matter.
$M_{\rm max}$ values obtained for the (neutrino-free) $\beta$-stable PNS at
$S/A=4$ were used to assess time $t_{\rm BH}$ of the collapse of 40 $M_\odot$
protoneutron progenitor to black hole, based on a correlation between $t_{\rm
BH}$ and $M_{\rm max}$ found from the hydrodynamic simulation by Hempel {\it et
al.}.


title:
Canonical description of 1D few-body systems with short range
  interaction

abstract:
  We address the fundamental interplay between indistinguishability and
interactions when discreteness effects are neglected in systems with strictly
fixed number of particles. For this end we supplement cluster expansions
(many-body canonical techniques where quantum statistics is treated exactly)
with short-time/large volume dynamical information where interparticle forces
are described non-perturbatively. This approach, specially suitable for the
few-body case where it overcomes the inappropriate use of virial expansions,
can be consistently combined with scaling considerations, minimal ground-state
information and strong coupling expansions in such a way that a single
interaction event provides most of the thermodynamic and spectral properties of
1D systems with short range interactions. Our analytical results, in excellent
agreement with numerical simulations, show a form of universal integrability of
interaction effects for arbitrary confinements.


title:
Implicit Discourse Relation Classification via Multi-Task Neural
  Networks

abstract:
  Without discourse connectives, classifying implicit discourse relations is a
challenging task and a bottleneck for building a practical discourse parser.
Previous research usually makes use of one kind of discourse framework such as
PDTB or RST to improve the classification performance on discourse relations.
Actually, under different discourse annotation frameworks, there exist multiple
corpora which have internal connections. To exploit the combination of
different discourse corpora, we design related discourse classification tasks
specific to a corpus, and propose a novel Convolutional Neural Network embedded
multi-task learning system to synthesize these tasks by learning both unique
and shared representations for each task. The experimental results on the PDTB
implicit discourse relation classification task demonstrate that our model
achieves significant gains over baseline systems.


title:
Microwave imaging of a hot flux rope structure during the pre-impulsive
  stage of an eruptive M7.7 solar flare

abstract:
  Corona structures and processes during the pre-impulsive stage of solar
eruption are crucial to understanding the physics leading to the subsequent
explosive energy release. Here we present the first microwave imaging study of
a hot flux rope structure during the pre-impulsive stage of an eruptive M7.7
solar flare, with the Nobeyama Radioheliograph (NoRH) at 17 GHz. The flux rope
is also observed by the SDO/AIA in its hot passbands of 94 and 131 \AA\. In the
microwave data, it is revealed as an overall arcade-like structure consisting
of several intensity enhancements bridged by generally weak emissions, with
brightness temperatures ($T_B$) varying from ~10,000~K to ~20,000 K. Locations
of microwave intensity enhancements along the structure remain relatively fixed
at certain specific parts of the flux rope, indicating that the distribution of
emitting electrons is affected by the large scale magnetic configuration of the
twisted flux rope. Wavelet analysis shows a pronounced 2-min period of the
microwave $T_B$ variation during the pre-impulsive stage of interest. The
period agrees well with that reported for AIA sunward-contracting loops and
upward ejective plasmoids (suggested to be reconnection outflows). This
suggests that both periodicities are controlled by the same reconnection
process that takes place intermittently at a 2-min time scale. We infer that at
least a part of the emission is excited by non-thermal energetic electrons via
the gyro-synchrotron mechanism. The study demonstrates the potential of
microwave imaging in exploring the flux rope magnetic geometry and relevant
reconnection process during the onset of solar eruption.


title: A combinatorial formula expressing periodic $R$-polynomials

abstract:
  In 1980, Lusztig introduced the periodic Kazhdan-Lusztig polynomials, which
are conjectured to have important information about the characters of
irreducible modules of a reductive group over a field of positive
characteristic, and also about those of an affine Kac-Moody algebra at the
critical level. The periodic Kazhdan-Lusztig polynomials can be computed by
using another family of polynomials, called the periodic $R$-polynomials. In
this paper, we prove a (closed) combinatorial formula expressing periodic
$R$-polynomials in terms of the "doubled" Bruhat graph associated to a finite
Weyl group and a finite root system.


title: Spherical averages in the space of marked lattices

abstract:
  A marked lattice is a $d$-dimensional Euclidean lattice, where each lattice
point is assigned a mark via a given random field on ${\mathbb Z}^d$. We prove
that, if the field is strongly mixing with a faster-than-logarithmic rate, then
for every given lattice and almost every marking, large spheres become
equidistributed in the space of marked lattices. A key aspect of our study is
that the space of marked lattices is not a homogeneous space, but rather a
non-trivial fiber bundle over such a space. As an application, we prove that
the free path length in a crystal with random defects has a limiting
distribution in the Boltzmann-Grad limit.


title: A Novel Design of Linear Phase Non-uniform Digital Filter Banks

abstract:
  In many applications such as wireless communications and subband adaptive
filtering, we need to design non-uniform filter banks (NUFB), which may lead to
better performances and reduced hardware complexity when compared to uniform
filter bank. NUFB satisfying linear phase property for all the constituent
filters, are desirable in applications such as speech and image processing and
in communication. This paper proposes a novel design of non-uniform modified
discrete fourier transform filter bank (MDFT FB). Here, each non-uniform
channel is obtained by merging the nearby channels of a uniform MDFT FB. The
reported works of non-uniform cosine modulated filter banks (CMFBs) do not
satisfy linear phase property for all the constituent filters. In this work, we
introduce the design of a non-uniform MDFT FB which satisfies linear phase
property for all the constituent filters. The proposed design of the
non-uniform MDFT FB is checked utilizing the alias cancellation among the
channels, distortion and flatness condition of the channels. A condition is
derived to find the channels when merged with adjacent channels, will cause
aliasing in M channels. In the design and implementation of the proposed
non-uniform MDFT FB, the structure of the uniform MDFT filter bank is preserved
and hence all the advantages of MDFT FB over the DFT filter bank, are
guaranteed. Hence without increasing the design complexity, the non-uniform
MDFT FB is designed.


title:
Heterogeneous dynamics and its length scale in simple ionic liquid
  models: A computational study

abstract:
  We numerically investigate the dynamic heterogeneity and its length scale
found in the coarse-grained ionic liquid model systems. In our ionic liquid
model systems, cations are modeled as dimers with positive charge, while anions
are modeled as monomers with negative charge, respectively. To study the effect
of the charge distributions on the cations, two ionic liquid models with
different charge distributions are used and the model with neutral charge is
also considered as a counterpart. To reveal the heterogeneous dynamics in the
model systems, we examine spatial distributions of displacement and time
distributions of exchange and persistence times. All the models show
significant increase of the dynamic heterogeneity as the temperature is
lowered. The dynamic heterogeneity is quantified via the well-known four-point
susceptibility which measures the fluctuation of a time correlation function.
The dynamic correlation length is calculated by fitting the dynamic structure
factor, S4(k,t), with Ornstein-Zernike form at the time scale at which the
dynamic heterogeneity reaches the maximum value. Obtained time and length
scales exhibit a power law relation at the low temperatures, similar to various
supercooled liquid models. Especially, the charged model systems show unusual
crossover behaviors which are not observed in the uncharged model system. We
ascribe the crossover behavior to the enhanced cage effect caused by charges on
the particles.


title: Bipartite Correlation Clustering -- Maximizing Agreements

abstract:
  In Bipartite Correlation Clustering (BCC) we are given a complete bipartite
graph $G$ with `+' and `-' edges, and we seek a vertex clustering that
maximizes the number of agreements: the number of all `+' edges within clusters
plus all `-' edges cut across clusters. BCC is known to be NP-hard.
  We present a novel approximation algorithm for $k$-BCC, a variant of BCC with
an upper bound $k$ on the number of clusters. Our algorithm outputs a
$k$-clustering that provably achieves a number of agreements within a
multiplicative ${(1-\delta)}$-factor from the optimal, for any desired accuracy
$\delta$. It relies on solving a combinatorially constrained bilinear
maximization on the bi-adjacency matrix of $G$. It runs in time exponential in
$k$ and $\delta^{-1}$, but linear in the size of the input.
  Further, we show that, in the (unconstrained) BCC setting, an
${(1-\delta)}$-approximation can be achieved by $O(\delta^{-1})$ clusters
regardless of the size of the graph. In turn, our $k$-BCC algorithm implies an
Efficient PTAS for the BCC objective of maximizing agreements.


title: Chaotic dynamics of a bouncing coin

abstract:
  We study the dynamics of a bouncing coin whose motion is restricted to the
two-dimensional plane. Such coin model is equivalent to the system of two equal
masses connected by a rigid rod, making elastic collisions with a flat
boundary. We first describe the coin system as a point billiard with a
scattering boundary. Then we analytically verify that the billiard map acting
on the two disjoint sets produces a Smale horseshoe structure. We also prove
that any random sequence of coin collisions can be realized by choosing an
appropriate initial condition.


title: Hardy's Theorem for Gabor transform

abstract:
  We establish analogues of Hardy's theorem for Gabor transform on locally
compact abelian groups, Euclidean motion group and several general classes of
nilpotent Lie groups which include Heisenberg groups, thread-like nilpotent Lie
groups, $2$-NPC nilpotent Lie groups and low-dimensional nilpotent Lie groups.


title:
Gamma-Gamma Absorption in the Broad Line Region Radiation Fields of
  Gamma-Ray Blazars

abstract:
  The expected level of gamma-gamma absorption in the Broad Line Region (BLR)
radiation field of gamma-ray loud Flat Spectrum Radio Quasars (FSRQs)is
evaluated as a function of the location of the gamma-ray emission region. This
is done self-consistently with parameters inferred from the shape of the
spectral energy distribution (SED) in a single-zone leptonic EC-BLR model
scenario. We take into account all geometrical effects both in the calculation
of the gamma-gamma opacity and the normalization of the BLR radiation energy
density. As specific examples, we study the FSRQs 3C279 and PKS 1510-089,
keeping the BLR radiation energy density at the location of the emission region
fixed at the values inferred from the SED. We confirm previous findings that
the optical depth due to $\gamma\gamma$ absorption in the BLR radiation field
exceeds unity for both 3C279 and PKS 1510-089 for locations of the gamma-ray
emission region inside the inner boundary of the BLR. It decreases
monotonically, with distance from the central engine and drops below unity for
locations within the BLR. For locations outside the BLR, the BLR radiation
energy density required for the production of GeV gamma-rays rapidly increases
beyond observational constraints, thus making the EC-BLR mechanism implausible.
Therefore, in order to avoid significant gamma-gamma absorption by the BLR
radiation field, the gamma-ray emission region must therefore be located near
the outer boundary of the BLR.


title: Galactic-Center Hyper-Shell Model for the North Polar Spurs

abstract:
  The bipolar-hyper shell (BHS) model for the North Polar Spurs (NPS-E, -W, and
Loop I) and counter southern spurs (SPS-E and -W) is revisited based on
numerical hydrodynamical simulations. Propagations of shock waves produced by
energetic explosive events in the Galactic Center are examined. Distributions
of soft X-ray brightness on the sky at 0.25, 0.7, and 1.5 keV in a +/-50 deg x
+/-50 deg region around the Galactic Center are modeled by thermal emission
from high-temperature plasma in the shock-compressed shell considering
shadowing by the interstellar HI and H2 gases. The result is compared with the
ROSAT wide field X-ray images in R2, 4 and 6 bands. The NPS and southern spurs
are well reproduced by the simulation as shadowed dumbbell-shaped shock waves.
We discuss the origin and energetics of the event in relation to the starburst
and/or AGN activities in the Galactic Center. [ High resolution pdf is
available at http://www.ioa.s.u-tokyo.ac.jp/~sofue/htdocs/2016bhs/ ]


title:
Laser slowing of CaF molecules to near the capture velocity of a
  molecular MOT

abstract:
  Laser slowing of CaF molecules down to the capture velocity of a
magneto-optical trap (MOT) for molecules is achieved. Starting from a two-stage
buffer gas beam source, we apply frequency-broadened "white-light" slowing and
observe approximately 6x10^4 CaF molecules with velocities near 10\,m/s. CaF is
a candidate for collisional studies in the mK regime. This work represents a
significant step towards magneto-optical trapping of CaF.


title:
Transformation-mediated Plasticity in CuZr based Metallic Glass
  Composites: A Quantitative Mechanistic Understanding

abstract:
  In this paper, we present a thorough stress analysis of the Cu-Zr
metallic-glass composite with embedded B2 particles subject to a martensitic
transformation. Within the framework of the Eshelby theory, we are able to
explain, in a quantitative manner, (1) the formation of three types of shear
bands with distinct morphologies as observed experimentally in the severely
deformed Cu-Zr metallic-glass composite and (2) the work hardening ability of
the Cu-Zr metallic-glass composite as related to the coupled effects of elastic
back stress and elastic mismatch caused by the martensitic transformation.
Furthermore, we also discuss the issues about the stress affected zone of the
individual B2 phase and the stability of the crystalline-amorphous interface.
Given the general agreement between the theoretical and experimental findings,
we believe that the outcome of our current work can lead to a deeper
understanding of the transformation-induced plasticity in the Cu-Zr based
metallic glass composites, which should be very useful to the design of the
metallic-glass composites with improved ductility.


title:
Numerical Invariants of Totally Imaginary Quadratic
  $\mathbb{Z}[\sqrt{p}]$-orders

abstract:
  Let $A$ be a real quadratic order of discriminant $p$ or $4p$ with a prime
$p$. In this paper we classify all proper totally imaginary quadratic
$A$-orders $B$ with index $w(B)=[B^\times: A^\times]>1$. We also calculate
numerical invariants of these orders including the class number, the index
$w(B)$ and the numbers of local optimal embeddings of these orders into
quaternion orders. These numerical invariants are useful for computing the
class numbers of totally definite quaternion algebras.


title: Topological substitutions and Rauzy fractals

abstract:
  We consider two families of planar self-similar tilings of different nature:
the tilings consisting of translated copies of the fractal sets defined by an
iterated function system, and the tilings obtained as a geometrical realization
of a topological substitution (an object of purely combinatorial nature). We
establish a link between the two families in a specific case, by defining an
explicit topological substitution and by proving that it generates the same
tilings as those associated with the Tribonacci Rauzy fractal.


title:
Asymptotically optimal, sequential, multiple testing procedures with
  prior information on the number of signals

abstract:
  Assuming that data are collected sequentially from independent streams, we
consider the simultaneous testing of multiple binary hypotheses under two
general setups; when the number of signals (correct alternatives) is known in
advance, and when we only have a lower and an upper bound for it. In each of
these setups, we propose feasible procedures that control, without any
distributional assumptions, the familywise error probabilities of both type I
and type II below given, user-specified levels. Then, in the case of i.i.d.
observations in each stream, we show that the proposed procedures achieve the
optimal expected sample size, under every possible signal configuration,
asymptotically as the two error probabilities vanish at arbitrary rates. A
simulation study is presented in a completely symmetric case and supports
insights obtained from our asymptotic results, such as the fact that knowledge
of the exact number of signals roughly halves the expected number of
observations compared to the case of no prior information.


title: Appearances of pseudo-bosons from Black-Scholes equation

abstract:
  It is a well known fact that the Black-Scholes equation admits an alternative
representation as a Schr\"odinger equation expressed in terms of a non
self-adjoint hamiltonian. We show how {\em pseudo-bosons}, linear or not,
naturally arise in this context, and how they can be used in the computation of
the pricing kernel.


title:
Full-Color Computational Imaging with Single-Pixel Detectors Based on a
  2D Discrete Cosine Transform

abstract:
  We propose and demonstrate a computational imaging technique that uses
structured illumination based on a two-dimensional discrete cosine transform to
perform imaging with a single-pixel detector. A scene is illuminated by a
projector with two sets of orthogonal patterns, then by applying an inverse
cosine transform to the spectra obtained from the single-pixel detector a
full-color image is retrieved. This technique can retrieve an image from
sub-Nyquist measurements, and the background noise is easily canceled to give
excellent image quality. Moreover, the experimental setup is very simple.


title: Shear-driven instabilities and shocks in the atmospheres of hot Jupiters

abstract:
  General circulation models of the atmosphere of hot Jupiters have shown the
existence of a supersonic eastward equatorial jet. In this paper, we
investigate the effects of compressibility on the atmospheric dynamics by
solving the standard Euler equations. This is done by means of a series of
simulations performed in the framework of the equatorial beta-plane
approximation using the finite volume shock-capturing code RAMSES. At low
resolution, we recover the classical results described in the literature: we
find a strong and steady supersonic equatorial jet of a few km/s that displays
no signature of shocks. We next show that the jet zonal velocity depends
significantly on the grid meridional resolution. When that resolution is fine
enough to properly resolve the jet, the latter is subject to a Kelvin-Helmholtz
instability. The jet zonal mean velocity displays regular oscillations with a
typical timescale of few days and a significant amplitude of about 15% of the
jet velocity. We also find compelling evidence for the development of a
vertical shear instability at pressure levels of a few bars. It seems to be
responsible for an increased downward kinetic energy flux, significantly
affecting the temperature of the deep atmosphere, and appears to act as a form
of drag on the equatorial jet. This instability also creates velocity
fluctuations that propagate upward and steepen into weak shocks at pressure
levels of a few mbars. We conclude that hot Jupiter equatorial jets are
potentially unstable to both a barotropic Kelvin-Helmholtz instability and a
vertical shear instability. Upon confirmation using more realistic models, both
instabilities could result in significant time variability of the atmospheric
winds, may provide a small scale dissipation mechanism in the flow, and might
have consequences for the internal evolution of hot Jupiters.


title:
Deriving field theories for particles of arbitrary spin with and without
  supersymmetry

abstract:
  We review the derivation of light-cone interaction vertices for fermionic and
bosonic fields of arbitrary spin. The resulting amplitudes and their
factorization properties are discussed. We then show how this symmetry-based
approach works for theories with extended supersymmetry like N=4 Yang-Mills
theory and N=8 supergravity.


title: Cross-connections of the singular transformation semigroup

abstract:
  Cross-connection is a construction of regular semigroups using certain
categories called normal categories which are abstractions of the partially
ordered sets of principal left (right) ideals of a semigroup. We describe the
cross-connections in the semigroup $Sing(X)$ of all non-invertible
transformations on a set $X$. The categories involved are characterized as the
powerset category $\mathscr{P}(X)$ and the category of partitions $\Pi(X)$. We
describe these categories and show how a permutation on $X$ gives rise to a
cross-connection. Further we prove that every cross-connection between them is
induced by a permutation and construct the regular semigroups that arise from
the cross-connections. We show that each of the cross-connection semigroups
arising this way is isomorphic to $Sing(X)$. We also describe the right
reductive subsemigroups of $Sing(X)$ with the category of principal left ideals
isomorphic to $\mathscr{P}(X)$. This study sheds light into the more general
theory of cross-connections and also provides an alternate way of studying the
structure of $Sing(X)$.


title: Optical Properties of Graphene in Magnetic and Electric fields

abstract:
  Optical properties of graphene are explored by using the generalized
tight-binding model. The main features of spectral structures, the form,
frequency, number and intensity, are greatly enriched by the complex
relationship among the interlayer atomic interactions, the magnetic
quantization and the Coulomb potential energy. Absorption spectra have the
shoulders, asymmetric peaks and logarithmic peaks, coming from the band-edge
states of parabolic dispersions, the constant-energy loops and the saddle
points, respectively. The initial forbidden excitation region is only revealed
in even-layer AA stacking systems. Optical gaps and special structures can be
generated by an electric field. The delta-function-like structures in
magneto-optical spectra, which present the single, twin and double peaks, are
associated with the symmetric, asymmetric and splitting Landau-level energy
spectra, respectively. The single peaks due to the non-tilted Dirac cones
exhibit the nearly uniform intensity. The AAB stacking possesses more
absorption structures, compared to the other stackings. The diverse
magneto-optical selection rules are mainly determined by the well-behaved,
perturbed and undefined Landau modes. The frequent anti-crossings in the
magnetic- and electric-field-dependent energy spectra lead to the increase of
absorption peaks and the reduced intensities. Part of theoretical calculations
are consistent with the experimental measurements, and the others need further
detailed examinations.


title: Temporal code versus rate code for binary Information Sources

abstract:
  Neuroscientists formulate very different hypotheses about the nature of
neural code. At one extreme, it has been argued that neurons encode information
in relatively slow changes of individual spikes arriving "rates codes" and the
irregularity in the spike trains reflects noise in the system, while in the
other extreme this irregularity is the temporal codes thus the precise timing
of every spike carries additional information about the input. It is known that
in the estimation of Shannon information the patterns and temporal structures
are taken into account, while the rate code is determined by firing rate. We
compare these types of codes for binary Information Sources which model encoded
spike-trains. Assuming that the information transmitted by a neuron is governed
by uncorrelated stochastic process or by process with a memory we compare the
information transmission rates carried by such spike-trains with their firing
rates. We showed that the crucial role in the relation between information and
firing rates is played by a quantity which we call "jumping" parameter. It
corresponds to the probabilities of transitions from no-spike-state to the
spike-state and vice versa. For low values of jumping parameter the quotient of
information and firing rates is monotonically decreasing function of firing
rate, thus there is straightforward, one-to-one, relation between temporal and
rate codes. On the contrary, it turns out that for large enough jumping
parameter this quotient is non-monotonic function of firing rate and it
exhibits a global maximum, in this case optimal firing rate exists. Moreover,
there is no one-to-one relation between information and firing rates, so the
temporal and rate codes differ qualitatively. This leads to the observation
that the behavior of the quotient of information and firing rates for large
jumping parameter is important in the context of bursting phenomena.


title:
Strongly Modulated Ambipolar Characteristics of Few-layer Black
  Phosphorus in Oxygen

abstract:
  Two-dimensional black phosphorus has been configured as field-effect
transistors, showing an intrinsic symmetric ambipolar transport characteristic.
Here, we demonstrate the strongly modulated ambipolar characteristics of
few-layer black phosphorus in oxygen. Pure oxygen exposure can dramatically
decrease the electron mobility of black phosphorus without degrading the hole
transport. The transport characteristics can be nearly recovered upon annealing
in Argon. This reveals that oxygen molecules are physisorbed on black
phosphorus. In contrast, oxygen exposure upon light illumination exhibits a
significant attenuation for both electron and hole transport, originating from
the photoactivated oxidation of black phosphorus, which is corroborated by in
situ X-ray photoelectron spectroscopy characterization. Our findings clarify
the predominant role of oxygen in modulating ambipolar characteristics of black
phosphorus, thereby providing deeper insight to the design of black phosphorus
based complementary electronics.


title: The decay of $\Lambda_b\rightarrow p~K^-$ in QCD factorization approach

abstract:
  With only the tree level operator, the decay of $\Lambda_b\rightarrow pK$ is
predicted to be one order smaller than the experimental data. The QCD penguin
effects should be taken into account. In this paper, we explore the one-loop
QCD corrections to the decay of $\Lambda_b\to pK$ within the framework of QCD
factorization approach. For the baryon system, the diquark approximation is
adopted. The transition hadronic matrix elements between $\Lambda_b$ and $p$
are calculated in the light front quark model. The branching ratio of
$\Lambda_b\rightarrow pK$ is predicted to be about $4.85\times 10^{-6}$ which
is consistent with experimental data $(4.9\pm 0.9)\times 10^{-6}$. The CP
violation is about 5\% in theory.


title:
Conclusive Identification of Quantum Channels via Monogamy of Quantum
  Correlations

abstract:
  We investigate the action of local and global noise on monogamy of quantum
correlations, when monogamy scores are considered as observables, and
three-qubit systems are subjected to global noise and various local noisy
channels, namely, amplitude-damping, phase-damping, and depolarizing channels.
We show that the dynamics of monogamy scores corresponding to negativity and
quantum discord, in the case of generalized W states, as inputs to the noisy
channels, can exhibit non-monotonic dynamics with respect to increasing noise
parameter, which is in contrast to the monotonic decay of monogamy scores when
generalized Greenberger-Horne-Zeilinger states are exposed to noise. We
quantify the persistence of monogamy against noise via a characteristic value
of the noise parameter, and show that depolarizing noise destroys monogamy of
quantum correlation faster compared to other noisy channels. We demonstrate
that the negativity monogamy score is more robust than the quantum discord
monogamy score, when the noise is of the phase-damping type. We also
investigate the variation of monogamy with increasing noise for arbitrary
three-qubit pure states as inputs. Finally, depending on these results, we
propose a two-step protocol, which can conclusively identify the type of noise
applied to the quantum system, by using generalized Greenberger-Horne-Zeilinger
and generalized W states as resource states. We discuss a possible
generalization of the results to higher number of parties.


title: Semiparametric generalized linear models for time-series data

abstract:
  Time-series data in population health and epidemiology often involve
non-Gaussian responses. In this note, we propose a semiparametric generalized
linear models framework for time-series data that does not require
specification of a working conditional response distribution for the data.
Instead, the underlying response distribution is treated as an
infinite-dimensional parameter which is estimated simultaneously with the usual
finite-dimensional parameters via a maximum empirical likelihood approach. A
general consistency result for the resulting estimators is given. Simulations
suggest that both estimation and inferences using the proposed method can
perform as well as correctly-specified parametric models even for moderate
sample sizes, but can be more robust than parametric methods under model
misspecification. The method is used to analyse the Polio dataset from Zeger
(1988) and a recent Kings Cross assault dataset from Menendez et al. (2015).


title: A class of minimal submanifolds in spheres

abstract:
  We introduce a class of minimal submanfolds $M^n$, $n\geq 3$, in spheres
$\mathbb{S}^{n+2}$ that are ruled by totally geodesic spheres of dimension
$n-2$. If simply-connected, such a submanifold admits a one-parameter
associated family of equally ruled minimal isometric deformations that are
genuine. As for compact examples, there are plenty of them but only for
dimensions $n=3$ and $n=4$. In the first case, we have that $M^3$ must be a
$\mathbb{S}^1$-bundle over a minimal torus $T^2$ in $\mathbb{S}^5$ and in the
second case $M^4$ has to be a $\mathbb{S}^2$-bundle over a minimal sphere
$\mathbb{S}^2$ in $\mathbb{S}^6$. In addition, we provide new examples in
relation to the well-known Chern-do Carmo-Kobayashi problem since taking the
torus $T^2$ to be flat yields a minimal submanifolds $M^3$ in $\mathbb{S}^5$
with constant scalar curvature.


title:
Solving the scattering of N photons on a two-level atom without
  computation

abstract:
  We propose a novel approach for solving the scattering of light onto a
two-level atom coupled to a one-dimensional waveguide. We first express the
physical quantity of interest in terms of Feynman diagrams and treat the atom
as a non-saturable linear beamsplitter. By using the atomic response to our
advantage, a relevant substitution is then made that captures the nonlinearity
of the atom, and the final result is obtained in terms of simple integrals over
the initial incoming wavepackets. The procedure is not limited to
post-scattering quantities and allows for instance to derive the atomic
excitation during the scattering event.


title: Cosmological hysteresis in cyclic universe from membrane paradigm

abstract:
  Cosmological hysteresis is a purely thermodynamical phenomenon caused by the
gradient in pressure, hence the characteristic equation of state during the
expansion and contraction phases of the universe are different, provided that
the universe bounces and recollapses. During hysteresis pressure asymmetry is
created due to the presence of a single scalar field in the dynamical process.
Also such an interesting scenario has vivid implications in cosmology when
applied to variants of modified gravity models described within the framework
of membrane paradigm. Cyclic universe along with scalar field leads to the
increase in the amplitude of the cosmological scale factor at each consecutive
cycles of the universe. Detailed analysis shows that the conditions which
creates a universe with an ever increasing expansion, depend on the signature
of the hysteresis loop integral $\oint pdV$ and on membrane model parameters.


title: Optimized Kernel Entropy Components

abstract:
  This work addresses two main issues of the standard Kernel Entropy Component
Analysis (KECA) algorithm: the optimization of the kernel decomposition and the
optimization of the Gaussian kernel parameter. KECA roughly reduces to a
sorting of the importance of kernel eigenvectors by entropy instead of by
variance as in Kernel Principal Components Analysis. In this work, we propose
an extension of the KECA method, named Optimized KECA (OKECA), that directly
extracts the optimal features retaining most of the data entropy by means of
compacting the information in very few features (often in just one or two). The
proposed method produces features which have higher expressive power. In
particular, it is based on the Independent Component Analysis (ICA) framework,
and introduces an extra rotation to the eigen-decomposition, which is optimized
via gradient ascent search. This maximum entropy preservation suggests that
OKECA features are more efficient than KECA features for density estimation. In
addition, a critical issue in both methods is the selection of the kernel
parameter since it critically affects the resulting performance. Here we
analyze the most common kernel length-scale selection criteria. Results of both
methods are illustrated in different synthetic and real problems. Results show
that 1) OKECA returns projections with more expressive power than KECA, 2) the
most successful rule for estimating the kernel parameter is based on maximum
likelihood, and 3) OKECA is more robust to the selection of the length-scale
parameter in kernel density estimation.


title: Constructions and nonexistence results for suitable sets of permutations

abstract:
  A set of $N$ permutations of $\{1,2,\dots,v\}$ is $(N,v,t)$-suitable if each
symbol precedes each subset of $t-1$ others in at least one permutation. The
central problems are to determine the smallest $N$ for which such a set exists
for given $v$ and $t$, and to determine the largest $v$ for which such a set
exists for given $N$ and $t$. These extremal problems were the subject of
classical studies by Dushnik in 1950 and Spencer in 1971. We give examples of
suitable sets of permutations for new parameter triples $(N,v,t)$. We relate
certain suitable sets of permutations with parameter $t$ to others with
parameter $t+1$, thereby showing that one of the two infinite families recently
presented by Colbourn can be constructed directly from the other. We prove an
exact nonexistence result for suitable sets of permutations using elementary
combinatorial arguments. We then establish an asymptotic nonexistence result
using Ramsey's theorem.


title:
Biharmonic C-parallel Legendrian submanifolds in 7-dimensional Sasakian
  space forms

abstract:
  This paper corrects the classification result for biharmonic C-parallel
Legendrian submanifolds presented by D. Fetcu and C. Oniciuc in [Tohoku Math.
J. 64 (2012), 195-222].