title:
Apparent Contact Angle and Contact Angle Hysteresis on Liquid Infused
  Surfaces

abstract:
  We theoretically investigate the apparent contact angle and contact angle
hysteresis of a droplet placed on a liquid infused surface. We show that the
apparent contact angle is not uniquely defined by material parameters, but also
has a strong dependence on the relative size between the droplet and its
surrounding wetting ridge formed by the infusing liquid. We derive a closed
form expression for the contact angle in the limit of vanishing wetting ridge,
and compute the correction for small but finite ridge, which corresponds to an
effective line tension term. We also predict contact angle hysteresis on liquid
infused surfaces generated by the pinning of the contact lines by the surface
corrugations. Our analytical expressions for both the apparent contact angle
and contact angle hysteresis can be interpreted as `weighted sums' between the
contact angles of the infusing liquid relative to the droplet and surrounding
gas phases, where the weighting coefficients are given by ratios of the fluid
surface tensions.


title:
Comparing Published Scientific Journal Articles to Their Pre-print
  Versions

abstract:
  Academic publishers claim that they add value to scholarly communications by
coordinating reviews and contributing and enhancing text during publication.
These contributions come at a considerable cost: U.S. academic libraries paid
$1.7 billion for serial subscriptions in 2008 alone. Library budgets, in
contrast, are flat and not able to keep pace with serial price inflation. We
have investigated the publishers' value proposition by conducting a comparative
study of pre-print papers and their final published counterparts. This
comparison had two working assumptions: 1) if the publishers' argument is
valid, the text of a pre-print paper should vary measurably from its
corresponding final published version, and 2) by applying standard similarity
measures, we should be able to detect and quantify such differences. Our
analysis revealed that the text contents of the scientific papers generally
changed very little from their pre-print to final published versions. These
findings contribute empirical indicators to discussions of the added value of
commercial publishers and therefore should influence libraries' economic
decisions regarding access to scholarly publications.


title: Species tree inference from gene splits by Unrooted STAR methods

abstract:
  The $\text{NJ}_{st}$ method was proposed by Liu and Yu to infer a species
tree topology from unrooted topological gene trees. While its statistical
consistency under the multispecies coalescent model was established only for a
4-taxon tree, simulations demonstrated its good performance on gene trees
inferred from sequences for many taxa. Here we prove the statistical
consistency of the method for an arbitrarily large species tree. Our approach
connects $\text{NJ}_{st}$ to a generalization of the STAR method of Liu, Pearl
and Edwards, and a previous theoretical analysis of it. We further show
$\text{NJ}_{st}$ utilizes only the distribution of splits in the gene trees,
and not their individual topologies. Finally, we discuss how multiple samples
per taxon per gene should be handled for statistical consistency.


title: Calabi-Yau structures on categories of matrix factorizations

abstract:
  We write out explicit proper Calabi-Yau structures, i. e. non-degenerate
cyclic cocycles on the differential graded categories of matrix factorizations
of regular functions with isolated critical points. The formulas involve the
Kapustin-Li trace and its "higher corrections".


title: The Small Satellites of Pluto as Observed by New Horizons

abstract:
  The New Horizons mission has provided resolved measurements of Pluto's moons
Styx, Nix, Kerberos, and Hydra. All four are small, with equivalent spherical
diameters of $\approx$40 km for Nix and Hydra and ~10 km for Styx and Kerberos.
They are also highly elongated, with maximum to minimum axis ratios of
$\approx$2. All four moons have high albedos ( $\approx$50-90 %) suggestive of
a water-ice surface composition. Crater densities on Nix and Hydra imply
surface ages $\gtrsim$ 4 Ga. The small moons rotate much faster than
synchronous, with rotational poles clustered nearly orthogonal to the common
pole directions of Pluto and Charon. These results reinforce the hypothesis
that the small moons formed in the aftermath of a collision that produced the
Pluto-Charon binary.


title: Ptolemy constant and uniformity

abstract:
  We study Ptolemy constant and uniformity constant in various plane domains
including triangles, quadrilaterals and ellipses.


title: Surface Compositions Across Pluto and Charon

abstract:
  The New Horizons spacecraft mapped colors and infrared spectra across the
encounter hemispheres of Pluto and Charon. The volatile ices CH$_4$, CO, and
N$_2$, that dominate Pluto's surface, have complicated spatial distributions
resulting from sublimation, condensation, and glacial flow acting over seasonal
and geological timescales. Pluto's H$_2$O ice "bedrock" is also mapped, with
isolated outcrops occurring in a variety of settings. Pluto's surface exhibits
complex regional color diversity associated with its distinct provinces.
Charon's color pattern is simpler, dominated by neutral low latitudes and a
reddish northern polar region. Charon near infrared spectra reveal highly
localized areas with strong NH$_3$ absorption tied to small craters with
relatively fresh-appearing impact ejecta.


title:
On Resilience Analysis and Quantification for Wide-Area Control of Power
  Systems

abstract:
  Wide-area control is an effective mean to reduce inter-area oscillations of
large power systems. Its dependence on communication of remote measurement
signals makes the closed-loop system vulnerable to cyber attacks. This paper
develops a framework to analyze and quantify resilience of a given wide-area
controller under disruptive attacks on certain communication links. Resilience
of a given controller is measured in terms of closed-loop eigenvalues under the
worst possible attack strategy. The computation of such a resilience index is
challenging especially for large-scale power systems due to the discrete nature
of the attack strategies. To address the challenge, we propose an
optimization-based formulation and a convex relaxation approach to facilitate
the computation. Conditions under which the relaxation is exact are derived and
an efficient algorithm with guaranteed convergence is also developed. The
proposed framework and the algorithm allow us to quantify resilience for given
wide-area controllers and also provide sufficient conditions to guarantee
closed-loop stability under all possible communication attacks. Simulations are
performed on the IEEE 39-bus system to illustrate the proposed resilience
analysis and computation framework.


title:
Developing Atmospheric Retrieval Methods for Direct Imaging Spectroscopy
  of Gas Giants in Reflected Light I: Methane Abundances and Basic Cloud
  Properties

abstract:
  Upcoming space-based coronagraphic instruments in the next decade will
perform reflected light spectroscopy and photometry of cool, directly imaged
extrasolar giant planets. We are developing a new atmospheric retrieval
methodology to help assess the science return and inform the instrument design
for such future missions, and ultimately interpret the resulting observations.
Our retrieval technique employs a geometric albedo model coupled with both a
Markov chain Monte Carlo Ensemble Sampler (emcee) and a multimodal nested
sampling algorithm (MultiNest) to map the posterior distribution. This
combination makes the global evidence calculation more robust for any given
model, and highlights possible discrepancies in the likelihood maps. As a
proof-of-concept, our current atmospheric model contains 1 or 2 cloud layers,
methane as a major absorber, and a H$_2$-He background gas. This 6-to-9
parameter model is appropriate for Jupiter-like planets and can be easily
expanded in the future. In addition to deriving the marginal likelihood
distribution and confidence intervals for the model parameters, we perform
model selection to determine the significance of methane and cloud detection as
a function of expected signal-to-noise in the presence of spectral noise
correlations. After internal validation, the method is applied to realistic
spectra of Jupiter, Saturn, and HD 99492 c, a model observing target. We find
that the presence or absence of clouds and methane can be determined with high
confidence, while parameter uncertainties are model-dependent and correlated.
Such general methods will also be applicable to the interpretation of direct
imaging spectra of cloudy terrestrial planets.


title: Electronic Structure Theory of Weakly Interacting Bilayers

abstract:
  We derive electronic structure models for weakly interacting bilayers such as
graphene-graphene and graphene-hexagonal boron nitride, based on density
functional theory calculations followed by Wannier transformation of electronic
states. These transferable interlayer coupling models can be applied to
investigate the physics of bilayers with arbitrary translations and twists. The
functional form, in addition to the dependence on the distance, includes the
angular dependence that results from higher angular momentum components in the
Wannier $p_z$ orbitals. We demonstrate the capabilities of the method by
applying it to a rotated graphene bilayer, which produces the analytically
predicted renormalization of the Fermi velocity, van Hove singularities in the
density of states, and Moir\'{e} pattern of the electronic localization at
small twist angles. We further extend the theory to obtain the effective
couplings by integrating out neighboring layers. This approach is instrumental
for the design of van der Walls heterostructures with desirable electronic
features and transport properties and for the derivation of low-energy theories
for graphene stacks, including proximity effects from other layers.


title:
Clustering Comparable Corpora of Russian and Ukrainian Academic Texts:
  Word Embeddings and Semantic Fingerprints

abstract:
  We present our experience in applying distributional semantics (neural word
embeddings) to the problem of representing and clustering documents in a
bilingual comparable corpus. Our data is a collection of Russian and Ukrainian
academic texts, for which topics are their academic fields. In order to build
language-independent semantic representations of these documents, we train
neural distributional models on monolingual corpora and learn the optimal
linear transformation of vectors from one language to another. The resulting
vectors are then used to produce `semantic fingerprints' of documents, serving
as input to a clustering algorithm.
  The presented method is compared to several baselines including `orthographic
translation' with Levenshtein edit distance and outperforms them by a large
margin. We also show that language-independent `semantic fingerprints' are
superior to multi-lingual clustering algorithms proposed in the previous work,
at the same time requiring less linguistic resources.


title: $\Lambda$ Scattering Equations

abstract:
  The CHY representation of scattering amplitudes is based on integrals over
the moduli space of a punctured sphere. We replace the punctured sphere by a
double-cover version. The resulting scattering equations depend on a parameter
$\Lambda$ controlling the opening of a branch cut. The new representation of
scattering amplitudes possesses an enhanced redundancy which can be used to
fix, modulo branches, the location of four punctures while promoting $\Lambda$
to a variable. Via residue theorems we show how CHY formulas break up into sums
of products of smaller (off-shell) ones times a propagator. This leads to a
powerful way of evaluating CHY integrals of generic rational functions, which
we call the $\Lambda$ algorithm.


title:
Spontaneous Formation of Surface Magnetic Structure from Large-scale
  Dynamo in Strongly-stratified Convection

abstract:
  We report the first successful simulation of spontaneous formation of surface
magnetic structures from a large-scale dynamo by strongly-stratified thermal
convection in Cartesian geometry. The large-scale dynamo observed in our
strongly-stratified model has physical properties similar to those in earlier
weakly-stratified convective dynamo simulations, indicating that the
$\alpha^2$-type mechanism is responsible for it. Additionally to the
large-scale dynamo, we find that large-scale structures of the vertical
magnetic field are spontaneously formed in the convection zone surface only for
the case of strongly-stratified atmosphere. The organization of the vertical
magnetic field proceeds in the upper convection zone within tens of convective
turn-over time and band-like bipolar structures are recurrently-appeared in the
dynamo-saturated stage. We examine possibilities of several candidates as the
origin of the surface magnetic structure formation, and then suggest the
existence of an as-yet-unknown mechanism for the self-organization of the
large-scale magnetic structure, which should be inherent in the
strongly-stratified convective atmosphere.


title: Optimal Designs for Longitudinal and Functional Data

abstract:
  We propose novel optimal designs for longitudinal data for the common
situation where the resources for longitudinal data collection are limited, by
determining the optimal locations in time where measurements should be taken.
As for all optimal designs, some prior information is needed to implement the
proposed optimal designs. We demonstrate that this prior information may come
from a pilot longitudinal study that has irregularly measured and noisy
measurements, where for each subject one has available a small random number of
repeated measurements that are randomly located on the domain. A second
possibility of interest is that a pilot study consists of densely measured
functional data and one intends to take only a few measurements at
strategically placed locations in the domain for the future collection of
similar data. We construct optimal designs by targeting two criteria: (a)
Optimal designs to recover the unknown underlying smooth random trajectory for
each subject from a few optimally placed measurements such that squared
prediction errors are minimized; (b) Optimal designs that minimize prediction
errors for functional linear regression with functional or longitudinal
predictors and scalar responses, again from a few optimally placed
measurements. The proposed optimal designs address the need for sparse data
collection when planning longitudinal studies, by taking advantage of the close
connections between longitudinal and functional data analysis. We demonstrate
in simulations that the proposed designs perform considerably better than
randomly chosen design points and include a motivating data example from the
Baltimore longitudinal study of aging. The proposed designs are shown to have
an asymptotic optimality property.


title:
Random attractor of the 3D viscous primitive equations driven by
  fractional noises

abstract:
  We develop a new and general method to prove the the existence of the random
attractor (strong attractor) for the primitive equations (PEs) of large-scale
ocean and atmosphere dynamics under $non$-$periodic$ boundary conditions and
driven by infinite-dimensional additive fractional Wiener processes. In
contrast to our new method, the common method, compact Sobolev embedding
theorem, is to obtain the uniform $a$ $priori$ estimates in some Sobolev space
whose regularity is high enough. But this is very complicated for the 3D
stochastic PEs with the $non$-$periodic$ boundary conditions. Therefore, the
existence of universal attractor ( weak attractor) was established in previous
work.
  The main idea of our method is that we first derive that $\mathbb{P}$-almost
surely the solution operator of stochastic PEs is compact. Then we construct a
compact absorbing set by virtue of the compact property of the the solution
operator and the existence of a absorbing set. We should point out that our
method has some advantages over the common method of using compact Sobolev
embedding theorem, i.e., if the random attractor in some Sobolev space do exist
in view of the common method, our method would then further implies the
existence of random attractor in this space. The present work provides a
general way for proving the existence of random attractor for common classes of
dissipative stochastic partial differential equations and improves the existing
results concerning random attractor of stochastic PEs. In a forth coming paper,
we use this new method to prove the existence of strong attractor for the
stochastic moist primitive equations, improving the results, the existence of
weak (universal) attractor of the deterministic model.


title: Churn analysis using deep convolutional neural networks and autoencoders

abstract:
  Customer temporal behavioral data was represented as images in order to
perform churn prediction by leveraging deep learning architectures prominent in
image classification. Supervised learning was performed on labeled data of over
6 million customers using deep convolutional neural networks, which achieved an
AUC of 0.743 on the test dataset using no more than 12 temporal features for
each customer. Unsupervised learning was conducted using autoencoders to better
understand the reasons for customer churn. Images that maximally activate the
hidden units of an autoencoder trained with churned customers reveal ample
opportunities for action to be taken to prevent churn among strong data, no
voice users.


title:
Model order reduction for Linear Noise Approximation using time-scale
  separation (Extended Version)

abstract:
  In this paper, we focus on model reduction of biomolecular systems with
multiple time-scales, modeled using the Linear Noise Approximation. Considering
systems where the Linear Noise Approximation can be written in singular
perturbation form, with $\epsilon$ as the singular perturbation parameter, we
obtain a reduced order model that approximates the slow variable dynamics of
the original system. In particular, we show that, on a finite time-interval,
the first and second moments of the reduced system are within an
$O(\epsilon)$-neighborhood of the first and second moments of the slow variable
dynamics of the original system. The approach is illustrated on an example of a
biomolecular system that exhibits time-scale separation.


title:
Ratio between two $\Lambda$ and $\bar{\Lambda}$ production mechanisms in
  $p$ scattering

abstract:
  We consider $\Lambda$ and $\bar{\Lambda}$ production in a wide range of
proton scattering experiments. The produced $\Lambda$ and $\bar{\Lambda}$ may
or may not contain a diquark remnant of the beam proton. The ratio of these two
production mechanisms is found to be a simple universal function $r = [
\kappa/(y_p - y) ]^i$ of the rapidity difference $y_p - y$ of the beam proton
and the produced $\Lambda$ or $\bar{\Lambda}$, valid over four orders of
magnitude, from $r \approx 0.01$ to $r \approx 100$, with $\kappa = 2.86 \pm
0.03 \pm 0.07$, and $i = 4.39 \pm 0.06 \pm 0.15$.


title:
Observational Investigation of Energy Release in the Lower Solar
  Atmosphere of a Solar Flare

abstract:
  We study flare processes in the lower solar atmosphere using observational
data for a M1-class flare of June 12, 2014, obtained by New Solar Telescope
(NST/BBSO) and Helioseismic Magnetic Imager (HMI/SDO). The main goal is to
understand triggers and manifestations of the flare energy release in the lower
layers of the solar atmosphere (the photosphere and chromosphere) using
high-resolution optical observations and magnetic field measurements. We
analyze optical images, HMI Dopplergrams and vector magnetograms, and use
Non-Linear Force-Free Field (NLFFF) extrapolations for reconstruction of the
magnetic topology. The NLFFF modelling reveals interaction of oppositely
directed magnetic flux-tubes in the PIL. These two interacting magnetic flux
tubes are observed as a compact sheared arcade along the PIL in the
high-resolution broad-band continuum images from NST. In the vicinity of the
PIL, the NST H alpha observations reveal formation of a thin three-ribbon
structure corresponding to the small-scale photospheric magnetic arcade.
Presented observational results evidence in favor of location of the primary
energy release site in the dense chromosphere where plasma is partially ionized
in the region of strong electric currents concentrated near the polarity
inversion line. Magnetic reconnection may be triggered by two interacting
magnetic flux tubes with forming current sheet elongated along the PIL.


title: Electric dipole polarizability from first principles calculations

abstract:
  The electric dipole polarizability quantifies the low-energy behaviour of the
dipole strength and is related to critical observables such as the radii of the
proton and neutron distributions. Its computation is challenging because most
of the dipole strength lies in the scattering continuum. In this paper we
combine integral transforms with the coupled-cluster method and compute the
dipole polarizability using bound-state techniques. Employing different
interactions from chiral effective field theory, we confirm the strong
correlation between the dipole polarizability and the charge radius, and study
its dependence on three-nucleon forces. We find good agreement with data for
the 4He, 40Ca, and 16O nuclei, and predict the dipole polarizability for the
rare nucleus 22O.


title:
Effects of multi-jet coupling on propulsive performance in underwater
  pulsed jets

abstract:
  Despite the importance of pulsed jets for underwater propulsion, the effect
of multiple-jet interactions remains poorly understood. We experimentally
investigate how interactions between neighboring jets in a pulsed-jet thruster
affect the thruster's propulsive performance. Using high-speed fluorescence
imaging, we investigate the mutual influence of two pulsed jets under
conditions relevant to low-speed maneuvering in a vehicle ($Re\approx350,$
$L/D\leq2$). Thrust production and propulsive efficiency are evaluated for
different nozzle spacings using a new force estimation technique based on the
fluorescence data. This analysis reveals that, compared to non-interacting
jets, the efficiency and thrust generated by the pair of interacting jets can
fall by as much as 10\% when the jets are brought into close proximity.
Empirically, the thrust $T$ falls off with the non-dimensional jet spacing
$\widetilde{\Delta}$ as $T=T_\infty(1-Co \widetilde{\Delta}^{-6})$ for a thrust
coupling coefficient $Co=2.04 \pm 0.11.$ Finally, we predict this leading order
dependence of thrust on spacing using a model that relates the thrust and
efficiency drop to streamline curvature and vortex induction at the nozzles.


title: Learning Dense Correspondence via 3D-guided Cycle Consistency

abstract:
  Discriminative deep learning approaches have shown impressive results for
problems where human-labeled ground truth is plentiful, but what about tasks
where labels are difficult or impossible to obtain? This paper tackles one such
problem: establishing dense visual correspondence across different object
instances. For this task, although we do not know what the ground-truth is, we
know it should be consistent across instances of that category. We exploit this
consistency as a supervisory signal to train a convolutional neural network to
predict cross-instance correspondences between pairs of images depicting
objects of the same category. For each pair of training images we find an
appropriate 3D CAD model and render two synthetic views to link in with the
pair, establishing a correspondence flow 4-cycle. We use ground-truth
synthetic-to-synthetic correspondences, provided by the rendering engine, to
train a ConvNet to predict synthetic-to-real, real-to-real and
real-to-synthetic correspondences that are cycle-consistent with the
ground-truth. At test time, no CAD models are required. We demonstrate that our
end-to-end trained ConvNet supervised by cycle-consistency outperforms
state-of-the-art pairwise matching methods in correspondence-related tasks.


title:
Multiple Asteroid Systems: Dimensions and Thermal Properties from
  Spitzer Space Telescope and Ground-Based Observations

abstract:
  Photometric lightcurves were also obtained for 14 of them during the Spitzer
observations to provide the context of the observations and reliable estimates
of their absolute magnitudes. The extracted mid-IR spectra were analyzed using
a modified standard thermal model (STM) and a thermophysical model (TPM) that
takes into account the shape and geometry of the large primary at the time of
the Spitzer observation. We derived a reliable estimate of the size, albedo,
and beaming factor for each of these asteroids, representing three main
taxonomic groups: C, S, and X. For large (volume-equivalent system diameter Deq
$\lt$ 130 km) binary asteroids, the TPM analysis indicates a low thermal
inertia ($\Gamma$ < $\sim$100 J s-1/2K-1m-2) and their emissivity spectra
display strong mineral features, implying that they are covered with a thick
layer of thermally insulating regolith. The smaller (surface-equivalent system
diameter Deff $\lt$17 km) asteroids also show some emission lines of minerals,
but they are significantly weaker, consistent with regoliths with coarser
grains, than those of the large binary asteroids. The average bulk densities of
these multiple asteroids vary from 0.7-1.7 g/cm3 (P-, C- type) to $\sim$2 g/cm3
(S-type). The highest density is estimated for the M-type (22) Kalliope (3.2
$\pm$ 0.9 g/cm3). The spectral energy distributions (SED) and emissivity
spectra, made available as a supplement document, could help to constrain the
surface compositions of these asteroids.


title: Interference Energy Spectrum of the Infinite Square Well

abstract:
  Certain superposition states of the 1-D infinite square well have transient
zeros at locations other than the nodes of the eigenstates that comprise them.
It is shown that if an infinite potential barrier is suddenly raised at some or
all of these zeros, the well can be split into multiple adjacent infinite
square wells without affecting the wavefunction. This effects a change of the
energy eigenbasis of the state to a basis that does not commute with the
original, and a subsequent measurement of the energy now reveals a completely
different spectrum, which we call the {interference energy spectrum} of the
state. This name is appropriate because the same splitting procedure applied at
the stationary nodes of any eigenstate does not change the measurable energy of
the state. Of particular interest, this procedure can result in measurable
energies that are greater than the energy of the highest mode in the original
superposition, raising questions about the conservation of energy akin to those
that have been raised in the study of superoscillations. An analytic derivation
is given for the interference spectrum of a given wavefunction $\Psi(x,t)$ with
$N$ known zeros located at points $s_i = (x_i, t_i)$. Numerical simulations
were used to verify that a barrier can be rapidly raised at a zero of the
wavefunction without significantly affecting it. The interpretation of this
result with respect to the conservation of energy and the energy-time
uncertainty relation is discussed, and the idea of alternate energy eigenbases
is fleshed out. The question of whether or not a preferred discrete energy
spectrum is an inherent feature of a particle's quantum state is examined.


title: On the design of optimal compliant walls for turbulence control

abstract:
  This paper employs the theoretical framework developed by Luhar et al. (J.
Fluid Mech., 768, 415-441) to consider the design of compliant walls for
turbulent skin friction reduction. Specifically, the effects of simple
spring-damper walls are contrasted with the effects of more complex walls
incorporating tension, stiffness and anisotropy. In addition, varying mass
ratios are tested to provide insight into differences between aerodynamic and
hydrodynamic applications. Despite the differing physical responses, all the
walls tested exhibit some important common features. First, the effect of the
walls (positive or negative) is greatest at conditions close to resonance, with
sharp transitions in performance across the resonant frequency or phase speed.
Second, compliant walls are predicted to have a more pronounced effect on
slower-moving structures because such structures generally have larger
wall-pressure signatures. Third, two-dimensional (spanwise constant) structures
are particularly susceptible to further amplification. These features are
consistent with many previous experiments and simulations, suggesting that
mitigating the rise of such two-dimensional structures is essential to
designing performance-improving walls. For instance, it is shown that further
amplification of such large-scale two-dimensional structures explains why the
optimal anisotropic walls identified by Fukagata et al. via DNS (J. Turb., 9,
1-17) only led to drag reduction in very small domains. The above observations
are used to develop design and methodology guidelines for future research on
compliant walls.


title:
On the noncommutative deformation of the operator graph corresponding to
  the Klein group

abstract:
  We study the noncommutative operator graph ${\mathcal L}_{\theta }$ depending
on complex parameter $\theta $ recently introduced by M.E. Shirokov to
construct channels with positive quantum zero-error capacity having vanishing
n-shot capacity. We define the noncommutative group $G$ and the algebra
${\mathcal A}_{\theta }$ which is a quotient of ${\mathbb C}G$ with respect to
the special algebraic relation depending on $\theta $ such that the matrix
representation $\phi $ of ${\mathcal A}_{\theta }$ results in the algebra
${\mathcal M}_{\theta }$ generated by ${\mathcal L}_{\theta }$. In the case of
$\theta =\pm 1$ $\phi $ is degenerated to the faithful representation of
${\mathbb C}K_4$, where $K_4$ is the Klein group. Thus, ${\mathcal L}_{\theta
}$ can be considered as a noncommutative deformation of the graph associated
with the Klein group.


title:
A correlation between the HI 21-cm absorption strength and impact
  parameter in external galaxies

abstract:
  By combining the data from surveys for HI 21-cm absorption at various impact
parameters in near-by galaxies, we report an anti-correlation between the 21-cm
absorption strength (velocity integrated optical depth) and the impact
parameter. Also, by combining the 21-cm absorption strength with that of the
emission, giving the neutral hydrogen column density, we find no evidence that
the spin temperature of the gas (degenerate with the covering factor) varies
significantly across the disk. This is consistent with the uniformity of spin
temperature measured across the Galactic disk. Furthermore, comparison with the
Galactic distribution suggests that intervening 21-cm absorption preferentially
arises in disks of high inclinations (near face-on). We also investigate the
hypothesis that 21-cm absorption is favourably detected towards compact radio
sources. Although there is insufficient data to determine whether there is a
higher detection rate towards quasar, rather than radio galaxy, sight-lines,
the 21-cm detections intervene objects with a mean turnover frequency of 5 x
10^8 Hz, compared to 1 x 10^8 Hz for the non-detections. Since the turnover
frequency is anti-correlated with radio source size, this does indicate a
preferential bias for detection towards compact background radio sources.


title: A Model-based Approach for Effective Service Delivery

abstract:
  With the prevalence of X-as-a-Service (e.g., software as a service, platform
as a service, infrastructure as a service, etc.) and users' growing demand on
good services, QoS (Quality of Service) assurance is becoming increasingly
important to service delivery. Traditional service delivery mainly focuses on
function or information provisioning, and does not give high priority to
quality assurance. In this paper, we tackle the QoS assurance problem in a
systematic way, from model to system. We first decompose traditional services
into three components - namely software application, data and resource, then
define models for these three kinds of basic services, and propose a set of
operations for service publishing and composition. To illustrate our approach,
we present a prototype system, the Platform as a Service (PaaS) system, which
is developed in support of our framework and shows how QoS can be ensured
through real-time monitoring and dynamic scaling (up or down).


title: Natural SU(2)-structures on tangent sphere bundles

abstract:
  We define and study natural $\mathrm{SU}(2)$-structures, in the sense of
Conti-Salamon, on the total space $\cal S$ of the tangent sphere bundle of any
given oriented Riemannian 3-manifold $M$. We recur to a fundamental exterior
differential system of Riemannian geometry. Essentially, two types of
structures arise: the contact-hypo and the non-contact and, for each, we study
the conditions for being hypo, nearly-hypo or double-hypo. We discover new
double-hypo structures on $S^3\times S^2$, of which the well-known
Sasaki-Einstein are a particular case. Hyperbolic geometry examples also
appear. In the search of the associated metrics, we find a theorem, useful for
explicitly determining the metric, which applies to all
$\mathrm{SU}(2)$-structures in general. Within our application to tangent
sphere bundles, we discover a whole new class of metrics specific to
3d-geometry. The evolution equations of Conti-Salamon are considered; leading
to a new integrable $\mathrm{SU}(3)$-structure on ${\cal S}\times\mathbb{R}_+$
associated to any flat $M$.


title: Optimal Sensor Positioning (OSP); A Probability Perspective Study

abstract:
  We propose a method to optimally position a sensor system, which consists of
multiple sensors, each has limited range and viewing angle, and they may fail
with a certain failure rate. The goal is to find the optimal locations as well
as the viewing directions of all the sensors and achieve the maximal
surveillance of the known environment. We setup the problem using the level set
framework. Both the environment and the viewing range of the sensors are
represented by level set functions. Then we solve a system of ordinary
differential equations (ODEs) to find the optimal viewing directions and
locations of all sensors together. Furthermore, we use the intermittent
diffusion, which converts the ODEs into stochastic differential equations
(SDEs), to find the global maximum of the total surveillance area. The
numerical examples include various failure rates of sensors, different rate of
importance of surveillance region, and 3-D setups. They show the effectiveness
of the proposed method.


title: A canonical connection on sub-Riemannian contact manifolds

abstract:
  We construct a canonically defined affine connection in sub-Riemannian
contact geometry. Our method mimics that of the Levi-Civita connection in
Riemannian geometry. We compare it with the Tanaka-Webster connection in the
three-dimensional case.


title:
An Adaptive Learning Mechanism for Selection of Increasingly More
  Complex Systems

abstract:
  Recently it has been demonstrated that causal entropic forces can lead to the
emergence of complex phenomena associated with human cognitive niche such as
tool use and social cooperation. Here I show that even more fundamental traits
associated with human cognition such as 'self-awareness' can easily be
demonstrated to be arising out of merely a selection for 'better regulators';
i.e. systems which respond comparatively better to threats to their existence
which are internal to themselves. A simple model demonstrates how indeed the
average self-awareness for a universe of systems continues to rise as less
self-aware systems are eliminated. The model also demonstrates however that the
maximum attainable self-awareness for any system is limited by the plasticity
and energy availability for that typology of systems. I argue that this rise in
self-awareness may be the reason why systems tend towards greater complexity.


title: Investigating light NMSSM pseudoscalar states with boosted ditau tagging

abstract:
  We study a class of realizations of the Next-to-Minimal Supersymmetric
Standard Model that is motivated by dark matter and Higgs data, and in which
the lightest pseudoscalar Higgs boson mass is smaller than twice the bottom
quark mass and greater than twice the tau lepton mass. In such scenarios, the
lightest pseudoscalar Higgs boson can be copiously produced at the LHC from the
decay of heavier superpartners and will dominantly further decay into a pair of
tau leptons that is generally boosted. We make use of a boosted object tagging
technique designed to tag such a ditau jet, and estimate the sensitivity of the
LHC to the considered supersymmetric scenarios with 20 to 50~fb$^{-1}$ of
proton-proton collisions at a center-of-mass energy of 13~TeV.


title:
Unidirectional, dual-comb lasing under multiple pulse formation
  mechanisms in a passively mode-locked fiber ring laser

abstract:
  Dual-comb lasers from which asynchronous ultrashort pulses can be
simultaneously generated have recently become an interesting research subject.
They could be an intriguing alternative to the current dual-laser
optical-frequency-comb source with highly sophisticated electronic control
systems. If generated through a common light path traveled by all pulses, the
common-mode noises between the spectral lines of different pulse trains could
be significantly reduced. Therefore, coherent dual-comb generation from a
completely common-path, unidirectional lasing cavity would be an interesting
territory to explore. In this paper, we demonstrate such a dual-comb lasing
scheme based on a nanomaterial saturable absorber with additional pulse
narrowing and broadening mechanisms concurrently introduced into a mode-locked
fiber laser. The interactions between multiple soliton formation mechanisms
result in unusual bifurcation into two-pulse states with quite different
characteristics. Simultaneous oscillation of pulses with four-fold difference
in pulsewidths and tens of Hz repetition rate difference is observed. The
coherence between these spectral-overlapped, picosecond and femtosecond pulses
is further verified by the corresponding asynchronous cross-sampling and
dual-comb spectroscopy measurements.


title: Several special complex structures and their deformation properties

abstract:
  We introduce a natural map from the space of pure-type complex differential
forms on a complex manifold to the corresponding one on the infinitesimal
deformations of this complex manifold. By use of this map, we generalize an
extension formula in a recent work of K. Liu, X. Yang and the first author. As
direct corollaries, we prove several deformation invariance theorems for Hodge
numbers. Moreover, we also study the Gauduchon cone and its relation with the
balanced cone in the K\"ahler case, and show that the limit of the Gauduchon
cone in the sense of D. Popovici for a generic fiber in a K\"ahlerian family is
contained in the closure of the Gauduchon cone for this fiber.


title: Half Heusler Alloys for Efficient Thermoelectric Power Conversion

abstract:
  Half-Heusler (HH) phases (space group F43m, Clb) are increasingly gaining
attention as promising thermoelectric materials in view of their thermal
stability, scalability, and environmental benignity as well as efficient power
output. Until recently, the verifiable dimensionless figure of merit (ZT) of HH
phases has remained moderate near 1, which limits the power conversion
efficiency of these materials. We report herein ZT~1.3 in n-type (Hf,Zr)NiSn
alloys near 850 K developed through elemental substitution and simultaneously
embedment of nanoparticles in the HH matrix, obtained by annealing the samples
close to their melting temperatures. Introduction of mass fluctuation and
scattering centers play a key role in the high ZT measured, as shown by the
reduction of thermal conductivity and increase of thermopower. Based on
computation, the power conversion efficiency of a n-p couple module based on
the new n-type (Hf,Zr,Ti)NiSn particles-in-matrix composite and recently
reported high-ZT p-type HH phases is expected to reach 13%, comparable to that
of state-of-the-art materials, but with the mentioned additional materials and
environmental attributes. Since the high efficiency is obtained without tuning
the microstructure of the Half-Heusler phases, it leaves room for further
optimization.


title: Stability of Valuations and Koll\'ar Components

abstract:
  We prove that among all Koll\'ar components obtained by plt blow ups of a klt
singularity $o \in (X, D)$, there is at most one that is (log-)K-semistable. We
achieve this by showing that if such a Koll\'ar component exists, it uniquely
minimizes the normalized volume function introduced in [Li15a] among all
divisorial valuations. Conversely, we show any divisorial minimizer of the
normalized volume function yields a K-semistable Koll\'ar component. We also
prove that for any klt singularity, the infimum of the normalized function is
always approximated by the normalized volumes of Koll\'ar components.


title:
Contingency-Constrained Unit Commitment With Intervening Time for System
  Adjustments

abstract:
  The N-1-1 contingency criterion considers the con- secutive loss of two
components in a power system, with intervening time for system adjustments. In
this paper, we consider the problem of optimizing generation unit commitment
(UC) while ensuring N-1-1 security. Due to the coupling of time periods
associated with consecutive component losses, the resulting problem is a very
large-scale mixed-integer linear optimization model. For efficient solution, we
introduce a novel branch-and-cut algorithm using a temporally decomposed
bilevel separation oracle. The model and algorithm are assessed using multiple
IEEE test systems, and a comprehensive analysis is performed to compare system
performances across different contingency criteria. Computational results
demonstrate the value of considering intervening time for system adjustments in
terms of total cost and system robustness.


title: Fermionic instantons

abstract:
  We demonstrate the existence of a broad class of non-perturbative fermionic
solutions to the Euclidean supergravity equations of motion, which are half-BPS
and nonsingular, possess zero action, and obey an (anti)self-duality condition.
These are identified as fermionic instantons associated to the status of the
gravitino as the gauge field of local supersymmetry. By explicitly constructing
these configurations from combinations of (anti)self-dual Yang-Mills gauge
fields and Killing spinors, we may leverage the ADHM method and generalisations
thereof to provide all possible solutions on certain gravitational backgrounds.
As one may expect, these solutions generate and are in turn intrinsically
dependent upon spacetime torsion.


title: Dynamical effect of gas on spiral pattern speed in galaxies

abstract:
  In the density wave theory of spiral structure, the grand-design two-armed
spiral pattern is taken to rotate rigidly in a galactic disc with a constant,
definite pattern speed. The observational measurement of the pattern speed of
the spiral arms, though difficult, has been achieved in a few galaxies such as
NGC 6946, NGC 2997, and M 51 which we consider here. We examine whether the
theoretical dispersion relation permits a real solution for wavenumber
corresponding to a stable wave, for the observed rotation curve and the pattern
speed values. We find that the disc when treated to consist of stars alone, as
is usually done in literature, does not generally support a stable density wave
for the observed pattern speed. Instead the inclusion of the low velocity
dispersion component, namely, gas, is essential to obtain a stable density
wave. Further, we obtain a theoretical range of allowed pattern speeds that
correspond to a stable density wave at a certain radius, and check that for the
three galaxies considered, the observed pattern speeds fall in the respective
prescribed range. The inclusion of even a small amount (~ 15 %) of gas by mass
fraction in the galactic disc is shown to have a significant dynamical effect
on the dispersion relation and hence on the pattern speed that is likely to be
seen in a real, gas-rich spiral galaxy.


title:
On the Stability and Accuracy of Partially and Fully Implicit Schemes
  for Phase Field Modeling

abstract:
  We study in this paper the accuracy and stability of partially and fully
implicit schemes for phase field modeling. Through theoretical and numerical
analysis of Allen-Cahn and Cahn-Hillard models, we investigate the potential
problems of using partially implicit schemes, demonstrate the importance of
using fully implicit schemes and discuss the limitation of energy stability
that are often used to evaluate the quality of a numerical scheme for
phase-field modeling. In particular, we make the following observations: 1. a
convex splitting scheme (CSS in short) can be equivalent to some fully implicit
scheme (FIS in short) with a much different time scaling and thus it may lack
numerical accuracy; 2. most implicit schemes (in discussions) are energy-stable
if the time-step size is sufficiently small; 3. a traditionally known
conditionally energy-stable scheme still possess an unconditionally
energy-stable physical solution; 4. an unconditionally energy-stable scheme is
not necessarily better than a conditionally energy-stable scheme when the time
step size is not small enough; 5. a first-order FIS for the Allen-Cahn model
can be devised so that the maximum principle will be valid on the discrete
level and hence the discrete phase variable satisfies $|u_h(x)|\le 1$ for all
$x$ and, furthermore, the linearized discretized system can be effectively
preconditioned by discrete Poisson operators.


title:
Topological classification of sesquilinear forms: reduction to the
  nonsingular case

abstract:
  Two sesquilinear forms $\Phi:\mathbb C^m\times\mathbb C^m\to \mathbb C$ and
$\Psi:\mathbb C^n\times\mathbb C^n\to \mathbb C$ are called topologically
equivalent if there exists a homeomorphism $\varphi :\mathbb C^m\to \mathbb
C^n$ (i.e., a continuous bijection whose inverse is also a continuous
bijection) such that $\Phi(x,y)=\Psi(\varphi (x),\varphi (y))$ for all $x,y\in
\mathbb C^m$. R.A.Horn and V.V.Sergeichuk in 2006 constructed a regularizing
decomposition of a square complex matrix $A$; that is, a direct sum
$SAS^*=R\oplus J_{n_1}\oplus\dots\oplus J_{n_p}$, in which $S$ and $R$ are
nonsingular and each $J_{n_i}$ is the $n_i$-by-$n_i$ singular Jordan block. In
this paper, we prove that $\Phi$ and $\Psi$ are topologically equivalent if and
only if the regularizing decompositions of their matrices coincide up to
permutation of the singular summands $J_{n_i}$ and replacement of $R\in\mathbb
C^{r\times r}$ by a nonsingular matrix $R'\in\mathbb C^{r\times r}$ such that
$R$ and $R'$ are the matrices of topologically equivalent forms. Analogous
results for real and complex bilinear forms are also obtained.


title: Repo Haircuts and Economic Capital: A Theory of Repo Pricing

abstract:
  A repurchase agreement lets investors borrow cash to buy securities.
Financier only lends to securities' market value after a haircut and charges
interest. Repo pricing is characterized with its puzzling dual pricing
measures: repo haircut and repo spread. This article develops a repo haircut
model by designing haircuts to achieve high credit criteria, and identifies
economic capital for repo's default risk as the main driver of repo pricing. A
simple repo spread formula is obtained that relates spread to haircuts negative
linearly. An investor wishing to minimize all-in funding cost can settle at an
optimal combination of haircut and repo rate. The model empirically reproduces
repo haircut hikes concerning asset backed securities during the financial
crisis. It explains tri-party and bilateral repo haircut differences,
quantifies shortening tenor's risk reduction effect, and sets a limit on excess
liquidity intermediating dealers can extract between money market funds and
hedge funds.


title: Solar cycle 25: another moderate cycle?

abstract:
  Surface flux transport simulations for the descending phase of cycle 24 using
random sources (emerging bipolar magnetic regions) with empirically determined
scatter of their properties provide a prediction of the axial dipole moment
during the upcoming activity minimum together with a realistic uncertainty
range. The expectation value for the dipole moment around 2020 $(2.5\pm1.1\,$G)
is comparable to that observed at the end of cycle 23 (about $2\,$G). The
empirical correlation between the dipole moment during solar minimum and the
strength of the subsequent cycle thus suggests that cycle 25 will be of
moderate amplitude, not much higher than that of the current cycle. However,
the intrinsic uncertainty of such predictions resulting from the random scatter
of the source properties is considerable and fundamentally limits the
reliability with which such predictions can be made before activity minimum is
reached.


title:
Gap Risk KVA and Repo Pricing: An Economic Capital Approach in the
  Black-Scholes-Merton Framework

abstract:
  Although not a formal pricing consideration, gap risk or hedging errors are
the norm of derivatives businesses. Starting with the gap risk during a margin
period of risk of a repurchase agreement (repo), this article extends the
Black-Scholes-Merton option pricing framework by introducing a reserve capital
approach to the hedging error's irreducible variability. An extended partial
differential equation is derived with two new terms for expected gap loss and
economic capital charge, leading to the gap risk economic value adjustment and
capital valuation adjustment (KVA) respectively. Practical repo pricing
formulae is obtained showing that the break-even repo rate decomposes into cost
of fund and economic capital charge in KVA. At zero haircut, a one-year term
repo on main equities could command a capital charge as large as 50 basis
points for a 'BBB' rated borrower.


title: Spin-1 Quantum Walks

abstract:
  We study the quantum walks of two interacting spin-1 bosons. We derive an
exact solution for the time-dependent wave function that describes the
two-particle dynamics governed by the one-dimensional spin-1 Bose-Hubbard
model. We show that propagation dynamics in real space and mixing dynamics in
spin space are correlated via the spin-dependent interaction in this system.
The spin-mixing dynamics has two characteristic frequencies in the limit of
large spin-dependent interactions. One of the characteristic frequencies is
determined by the energy difference between two bound states, and the other
frequency relates to the cotunneling process of a pair of spin-1 bosons.
Furthermore, we numerically analyze the growth of the spin correlations in
quantum walks. We find that long-range spin correlations emerge showing a clear
dependence on the sign of the spin-dependent interaction and the initial state.


title: Finiteness properties of direct products of algebraic structures

abstract:
  We consider the preservation of properties of being finitely generated, being
finitely presented and being residually finite under direct products in the
context of different types of algebraic structures. The structures considered
include Mal'cev algebras (including groups, rings and other classical algebras,
as well as loops), idempotent algebras (including lattices), semigroups, and
algebras in congruence modular varieties. We aim to identify as broad classes
as possible in which the 'expected' preservation results (AxB satisfies
property P if and only if A and B satisfy P) hold, and to exhibit ways in which
they may fail outside those classes.


title:
On the Importance of Very-light Internally-subsonic AGN Jets in
  Radio-mode AGN Feedback

abstract:
  Radio-mode AGN feedback plays a key role in the evolution of galaxy groups
and clusters. Its physical origin lies in the kpc-scale interaction of AGN jets
with the intracluster medium. Large-scale jet simulations often initiate light
internally-supersonic jets with density contrast $0.01<\eta<1$. Here we argue
for the first time for the importance of very-light ($\eta<0.01$)
internally-subsonic jets. We investigated the shapes of young X-ray cavities
produced in a suite of hydrodynamic simulations, and found that bottom-wide
cavities are always produced by internally-subsonic jets, while
internally-supersonic jets inflate cylindrical, center-wide, or top-wide
cavities. We found examples of real cavities with shapes analogous to those
inflated in our simulations by internally-subsonic and internally-supersonic
jets, suggesting a dichotomy of AGN jets according to their internal Mach
numbers. We further studied the long-term cavity evolution, and found that old
cavities resulted from light jets spread along the jet direction, while those
produced by very light jets are significantly elongated along the perpendicular
direction. The northwestern ghost cavity in Perseus is pancake-shaped,
providing tentative evidence for the existence of very light jets. Our
simulations show that very-light internally-subsonic jets decelerate faster and
rise much slower in the ICM than light internally-supersonic jets, possibly
depositing a larger fraction of jet energy to cluster cores and alleviating the
problem of low coupling efficiencies found previously. The internal Mach number
points to the jet's energy content, and internally-subsonic jets are
energetically dominated by non-kinetic energy, such as thermal energy, cosmic
rays, or magnetic fields.


title:
On some generalizations of mean value theorems for arithmetic functions
  of two variables

abstract:
  Let $f: \mathbb{N}^2 \mapsto \mathbb{C}$ be an arithmetic function of two
variables. We study the existence of the limit:
  \[\displaystyle \lim_{x \to \infty} \frac{1}{x^2 (\log x)^{k-1}} \sum_{n_1 ,
n_2 \le x} f (n_1, n_2) \] where $k$ is a fixed positive integer. Moreover, we
express this limit as an infinite product over all prime numbers in the case
that $f$ is a multiplicative function of two variables. This study is a
generalization of Cohen-van der Corput's results to the case of two variables.


title: Observation of spatio-temporal pattern in magnetised rf plasmas

abstract:
  We address an experimental observation of pattern formation in a magnetised
rf plasma. The experiments are carried out in a electrically grounded aluminium
chamber which is housed inside a rotatable superconducting magnetic coil. The
plasma is formed by applying a rf voltage in parallel plate electrodes in
push-pull mode under the background of argon gas. The time evolution of plasma
intensity shows that a homogeneous plasma breaks into several concentric radial
spatiotemoral bright and dark rings. These rings propagate radially at
considerably low pressure and a constant magnetic field. These patterns are
observed to trap small dust particles/grains in their potential. Exploiting
this property of the patterns, a novel technique to measure the electric field
associated with the patterns is described. The resulting estimates of the
corresponding field intensity are presented. At other specific discharge
parameters the plasma shows a range of special type of characteristic
structures observed in certain other chemical, mechanical and biological
systems.


title: Strong shellability of simplicial complexes

abstract:
  Imposing a strong condition on the linear order of shellable complexes, we
introduce strong shellability. Basic properties, including the existence of
dimension-decreasing strong shelling orders, are developed with respect to
nonpure strongly shellable complexes. Meanwhile, pure strongly shellable
complexes can be characterized by the corresponding codimension one graphs. In
addition, we show that the facet ideals of pure strongly shellable complexes
have linear quotients.


title: Cognitive state classification using transformed fMRI data

abstract:
  One approach, for understanding human brain functioning, is to analyze the
changes in the brain while performing cognitive tasks. Towards this, Functional
Magnetic Resonance (fMR) images of subjects performing well-defined tasks are
widely utilized for task-specific analyses. In this work, we propose a
procedure to enable classification between two chosen cognitive tasks, using
their respective fMR image sequences. The time series of expert-marked
anatomically-mapped relevant voxels are processed and fed as input to the
classical Naive Bayesian and SVM classifiers. The processing involves use of
random sieve function, phase information in the data transformed using Fourier
and Hilbert transformations. This processing results in improved
classification, as against using the voxel intensities directly, as
illustrated. The novelty of the proposed method lies in utilizing the phase
information in the transformed domain, for classifying between the cognitive
tasks along with random sieve function chosen with a particular probability
distribution. The proposed classification procedure is applied on a publicly
available dataset, StarPlus data, with 6 subjects performing the two distinct
cognitive tasks of watching either a picture or a sentence. The classification
accuracy stands at an average of 65.6%(using Naive Bayes classifier) and
76.4%(using SVM classifier) for raw data. The corresponding classification
accuracy stands at 96.8% and 97.5% for Fourier transformed data. For Hilbert
transformed data, it is 93.7% and 99%, for 6 subjects, on 2 cognitive tasks.


title: Edgewise strongly shellable clutters

abstract:
  When $\mathcal{C}$ is a chordal clutter in the sense of Woodroofe or
Emtander, we show that the complement clutter is edgewise strongly shellable.
When $\mathcal{C}$ is indeed a finite simple graph, we study various
characterizations of chordal graphs from the point of view of strong
shellability. In particular, the generic graph $G_T$ of a tree is shown to be
bi-strongly shellable. We also characterize edgewise strongly shellable
bipartite graphs in terms of constructions from upward sequences.
\end{abstract}


title: On Types of Observables in Constrained Theories

abstract:
  The Kuchar observables notion is shown to apply only to a limited range of
theories. Relational mechanics, slightly inhomogeneous cosmology and
supergravity are used as examples that require further notions of observables.
A suitably general notion of A-observables is then given to cover all of these
cases. `A' here stands for `algebraic substructure'; A-observables can be
defined by association with each closed algebraic substructure of a theory's
constraints. Both constrained algebraic structures and associated notions of
A-observables form bounded lattices.


title: Hopf algebraic structures of quantum toroidal algebras

abstract:
  We formulate a simplified set of generators for the quantum toroidal algebra
of type A, based on which we introduce a finite Hopf algebra structure for the
quantum algebra and realize it as a double algebra.


title: Triplet Probabilistic Embedding for Face Verification and Clustering

abstract:
  Despite significant progress made over the past twenty five years,
unconstrained face verification remains a challenging problem. This paper
proposes an approach that couples a deep CNN-based approach with a
low-dimensional discriminative embedding learned using triplet probability
constraints to solve the unconstrained face verification problem. Aside from
yielding performance improvements, this embedding provides significant
advantages in terms of memory and for post-processing operations like subject
specific clustering. Experiments on the challenging IJB-A dataset show that the
proposed algorithm performs comparably or better than the state of the art
methods in verification and identification metrics, while requiring much less
training data and training time. The superior performance of the proposed
method on the CFP dataset shows that the representation learned by our deep CNN
is robust to extreme pose variation. Furthermore, we demonstrate the robustness
of the deep features to challenges including age, pose, blur and clutter by
performing simple clustering experiments on both IJB-A and LFW datasets.


title:
Its All on the Square- The Importance of the Sum of Squares and Making
  the General Linear Model Simple

abstract:
  Statistics is one of the most valuable of disciplines. Science is based on
proof and it alone produces results, other approaches are not, and do not.
Statistics is the only acceptable language of proof in science. Yet statistics
is difficult to understand for a large percentage of those who will be
evaluating and even doing research. Reasons for this difficulty may be that
statistics operates counter to the way people think, as well as the widespread
phobia of numeracy. Adding to the difficulty is that undergraduate textbooks
tend to make statistical tests seem to be an unorganized conglomeration of
unrelated procedures, and this leads to a failure of students to understand
that all of the parametric procedures they are studying in an introductory
course are ultimately doing the same thing and stem from common sources. In
statistics, precisely because the material is complex, the presentation must be
simple! This article endeavors to do just that.


title: Extending the Harper Identity to Iterated Belief Change

abstract:
  The field of iterated belief change has focused mainly on revision, with the
other main operator of AGM belief change theory, i.e. contraction, receiving
relatively little attention. In this paper we extend the Harper Identity from
single-step change to define iterated contraction in terms of iterated
revision. Specifically, just as the Harper Identity provides a recipe for
defining the belief set resulting from contracting A in terms of (i) the
initial belief set and (ii) the belief set resulting from revision by not-A, we
look at ways to define the plausibility ordering over worlds resulting from
contracting A in terms of (iii) the initial plausibility ordering, and (iv) the
plausibility ordering resulting from revision by not-A. After noting that the
most straightforward such extension leads to a trivialisation of the space of
permissible orderings, we provide a family of operators for combining
plausibility orderings that avoid such a result. These operators are
characterised in our domain of interest by a pair of intuitively compelling
properties, which turn out to enable the derivation of a number of iterated
contraction postulates from postulates for iterated revision. We finish by
observing that a salient member of this family allows for the derivation of
counterparts for contraction of some well known iterated revision operators, as
well as for defining new iterated contraction operators.


title: Affine Szab\'o connections on smooth manifolds

abstract:
  In this paper, we introduce a new structure, namely, affine Szab\'o
connection. We prove that, on $2$-dimensional affine manifolds, the affine
Szab\'o structure is equivalent to one of the cyclic parallelism of the Ricci
tensor. A characterization for locally homogeneous affine Szab\'o surface is
obtained. Examples of two- and three-dimensional affine Szab\'o manifolds are
also given.


title: What lattice theorists can do for superstring/M-theory

abstract:
  The gauge/gravity duality provides us with nonperturbative formulation of
superstring/M-theory. Although inputs from gauge theory side are crucial for
answering many deep questions associated with quantum gravitational aspects of
superstring/M-theory, many of the important problems have evaded analytic
approaches. For them, lattice gauge theory is the only hope at this moment. In
this review I give a list of such problems, putting emphasis on problems within
reach in a five-year span, including both Euclidean and real-time simulations.


title: On three dimensional affine Szab\'o manifolds

abstract:
  In this paper, we consider the cyclic parallel Ricci tensor condition, which
is a necessary condition for an affine manifold to be Szab\'o. We show that, in
dimension $3$, there are affine manifolds which satisfy the cyclic parallel
Ricci tensor but are not Szab\'o. Conversely, it is known that in dimension
$2$, the cyclic parallel Ricci tensor forces the affine manifold to be Szab\'o.
Examples of $3$-dimensional affine Szabo manifolds are also given. Finally, we
give some properties of Riemannian extensions defined on the cotangent bundle
over an affine Szab\'o manifold.


title: Are IRIS bombs connected to Ellerman bombs?

abstract:
  Recent observations by the Interface Region Imaging Spectrograph (IRIS) have
revealed pockets of hot gas ($\sim$2--8$\times$10$^{4}$ K) potentially
resulting from magnetic reconnection in the partially ionized lower solar
atmosphere (IRIS bombs; IBs). Using joint observations between IRIS and the
Chinese New Vacuum Solar Telescope, we have identified ten IBs. We find that
three are unambiguously and three others are possibly connected to Ellerman
bombs (EBs), which show intense brightening of the extended H$_{\alpha}$ wings
without leaving an obvious signature in the H$_{\alpha}$ core. These bombs
generally reveal the following distinct properties: (1) The
O~{\sc{iv}}~1401.156\AA{} and 1399.774\AA{} lines are absent or very weak; (2)
The Mn~{\sc{i}}~2795.640\AA{} line manifests as an absorption feature
superimposed on the greatly enhanced Mg~{\sc{ii}}~k line wing; (3) The
Mg~{\sc{ii}}~k and h lines show intense brightening in the wings and no
dramatic enhancement in the cores; (4) Chromospheric absorption lines such as
Ni~{\sc{ii}}~1393.330\AA{} and 1335.203\AA{} are very strong; (5) The 1700\AA{}
images obtained with the Atmospheric Imaging Assembly on board the Solar
Dynamics Observatory reveal intense and compact brightenings. These properties
support the formation of these bombs in the photosphere, demonstrating that EBs
can be heated much more efficiently than previously thought. We also
demonstrate that the Mg~{\sc{ii}}~k and h lines can be used to investigate EBs
similarly to H$_{\alpha}$, which opens a promising new window for EB studies.
The remaining four IBs obviously have no connection to EBs and they do not have
the properties mentioned above, suggesting a higher formation layer possibly in
the chromosphere.


title: On twisted Riemannian extensions associated with Szab\'o metrics

abstract:
  Let $M$ be an $n$-dimensional manifold with a torsion free affine connection
$\nabla$ and let $T^*M$ be the cotangent bundle. In this paper, we consider
some of the geometrical aspect of a twisted Riemannian extension which provide
a link between the affine geometry of $(M,\nabla)$ and the neutral signature
pseudo-Riemannian geometry of $T^*M$. We investigate the spectral geometry of
the Szab\'o operator on $M$ and on $T^*M$.


title: Sasakian Finsler structures on pulled-back bundle

abstract:
  Under a pulled-back approach given in [1] and firstly presented in [2], we
introduce, in this paper, the concepts of almost contact and normal almost
contact Finsler structures on the pulled-back bundle. Properties of structures
partly Sasakians are studied. Using the hh-curvature tensor of Chern connection
given in [2], we obtain some characterizations of horizontally Finslerian
K-contact structures via the horizontal Ricci tensor and the flag curvature.


title:
Quasi Generalized CR-lightlike submanifolds of indefinite nearly
  Sasakian manifolds

abstract:
  In this paper, we introduce and study a new class of CR-lightlike submanifold
of an indefinite nearly Sasakian manifold, called Quasi Generalized
Cauchy-Riemann (QGCR) lightlike submanifold. We give some characterization
theorems for the existence of QGCR-lightlike submanifolds and finally derive
necessary and sufficient conditions for some distributions to be integrable.


title:
A significant hardening and rising shape detected in the MeV/GeV nuFnu
  spectrum from the recently-discovered very-high-energy blazar S4 0954+65
  during the bright optical flare in 2015 February

abstract:
  We report on Fermi Large Area Telescope (LAT) and multi-wavelength results on
the recently-discovered very-high-energy (VHE, $E>$ 100 GeV) blazar S4 0954+65
($z=0.368$) during an exceptionally bright optical flare in 2015 February.
During the time period (2015 February, 13/14, or MJD 57067) when the MAGIC
telescope detected VHE $\gamma$-ray emission from the source, the Fermi-LAT
data indicated a significant spectral hardening at GeV energies, with a
power-law photon index of $1.8 \pm 0.1$---compared with the 3FGL value
(averaged over four years of observation) of $2.34 \pm 0.04$. In contrast,
Swift/XRT data showed a softening of the X-ray spectrum, with a photon index of
$1.72 \pm 0.08$ (compared with $1.38 \pm 0.03$ averaged during the flare from
MJD 57066 to 57077), possibly indicating a modest contribution of synchrotron
photons by the highest-energy electrons superposed on the inverse Compton
component. Fitting of the quasi-simultaneous ($<1$ day) broadband spectrum with
a one-zone synchrotron plus inverse-Compton model revealed that GeV/TeV
emission could be produced by inverse-Compton scattering of external photons
from the dust torus. We emphasize that a flaring blazar showing high flux of
$\gtrsim 1.0 \times 10^{-6}$ photons cm$^{-2}$ s$^{-1}$ ($E>$ 100 MeV) and a
hard spectral index of $\Gamma_{\rm GeV} < 2.0$ detected by Fermi-LAT on daily
time scales is a promising target for TeV follow-up by ground-based Cherenkov
telescopes to discover high-redshift blazars, investigate their temporal
variability and spectral features in the VHE band, and also constrain the
intensity of the extragalactic background light.


title: Coverage analysis of information dissemination in throwbox-augmented DTN

abstract:
  This paper uses a bipartite network model to calculate the coverage achieved
by a delay-tolerant information dissemination algorithm in a specialized
setting. The specialized Delay Tolerant Network (DTN) system comprises static
message buffers or throwboxes kept in popular places besides the mobile agents
hopping from one place to another. We identify that an information
dissemination technique that exploits the throwbox infrastructure can cover
only a fixed number of popular places irrespective of the time spent. We notice
that such DTN system has a natural bipartite network correspondence where two
sets are the popular places and people visiting those places. This helps
leveraging the theories of evolving bipartite networks (BNW) to provide an
appropriate explanation of the observed temporal invariance of information
coverage over the DTN. In this work, we first show that information coverage
can be estimated by the size of the largest component in the thresholded
one-mode projection of BNW. Next, we also show that exploiting a special
property of BNW, the size of the largest component size can be calculated from
the degree distribution. Combining these two, we derive a closed form simple
equation to accurately predict the amount of information coverage in DTN which
is almost impossible to achieve using the traditional techniques such as
epidemic or Markov modeling. The equation shows that full coverage quickly
becomes extremely difficult to achieve if the number of places increases while
variation in agent's activity helps in covering more places.


title:
Comparative Study of Instance Based Learning and Back Propagation for
  Classification Problems

abstract:
  The paper presents a comparative study of the performance of Back Propagation
and Instance Based Learning Algorithm for classification tasks. The study is
carried out by a series of experiments will all possible combinations of
parameter values for the algorithms under evaluation. The algorithm's
classification accuracy is compared over a range of datasets and measurements
like Cross Validation, Kappa Statistics, Root Mean Squared Value and True
Positive vs False Positive rate have been used to evaluate their performance.
Along with performance comparison, techniques of handling missing values have
also been compared that include Mean or Mode replacement and Multiple
Imputation. The results showed that parameter adjustment plays vital role in
improving an algorithm's accuracy and therefore, Back Propagation has shown
better results as compared to Instance Based Learning. Furthermore, the problem
of missing values was better handled by Multiple imputation method, however,
not suitable for less amount of data.


title: Binary Multi-Level Routing Protocol for Mobile Ad Hoc Networks

abstract:
  Routing in mobile ad hoc networks (MANETs) presents a big challenge,
especially when support for a large number of nodes is needed. This paper
extends the local visibility concept of the recent DHT-based URBAN_XOR routing
protocol, which aims to reduce routing table sizes while keeping efficiency
high. Our main contribution is providing a guarantee that if any two nodes are
connected through other nodes, they are able to communicate with each other. We
propose a new route acquisition method that aims to reduce the total amount of
overhead traffic and improve convergence rate. In addition, we introduce an
abstraction for describing the network structure that makes it easy to
understand and analyze. Compared to existing approaches in ad hoc routing, the
new protocol supports the following features: scalability, guaranteed
connectivity assuming network convergence, absence of single points of failure,
low path-stretch, and mobility.


title: Permutations of context-free, ET0L and indexed languages

abstract:
  For a language $L$, we consider its cyclic closure, and more generally the
language $C^k(L)$, which consists of all words obtained by partitioning words
from $L$ into $k$ factors and permuting them. We prove that the classes of ET0L
and EDT0L languages are closed under the operators $C^k$. This both sharpens
and generalises Brandst\"adt's result that if $L$ is context-free then $C^k(L)$
is context-sensitive and not context-free in general for $k\geq 3$. We also
show that the cyclic closure of an indexed language is indexed.


title: The Origin of the Rotation Profiles in Star Forming Clouds

abstract:
  Angular momentum distribution and its redistribution are of crucial
importance in formation and evolution of circumstellar disks. Many molecular
line observations toward young stellar objects indicate that radial
distributions of the specific angular momentum $j$ are more or less universal.
In small scales, typically $R\lesssim$ 100 AU, the specific angular momenta
distribute like $j\propto r^{1/2}$, indicating existence of rotationally
supported disk. In outer regions, $R\gtrsim$ 5000 AU, $j$ increases as the
radius increases and the slope is steeper than unity, which is supposed to
reflect the original angular momentum distributions in the maternal molecular
clouds. And lastly there is a connecting region, 100 AU $\lesssim R \lesssim$
5000 AU, in which $j$-distribution looks almost flat. While this is often
interpreted as a consequence of conservation of the specific angular momentum,
it actually is insufficient and requires a stronger condition that the initial
distribution of $j$ must be spatially uniform. However, this requirement is
unrealistic and inconsistent with observations. In this work, we propose a
simple alternative explanation; the flat $j$ profile is produced by strong
prolongation due to the large velocity gradient in the accreting flow no matter
what the initial $j$ distribution is. We provide a simple analytic model for
gravitational collapse of molecular clouds. This model can be used to estimate
ages of protostars based solely on the observed rotation profile. We
demonstrate its validity in comparison with hydrodynamic simulations, and apply
the model to young stellar objects such as L1527 IRS, TMC-1A and B335.


title:
Uniform approximation of Bloch functions and the boundedness of the
  integration operator on $H^\infty$

abstract:
  We obtain a necessary and sufficient condition for the operator of
integration to be bounded on $H^\infty$ in a simply connected domain. The main
ingredient of the proof is a new result on uniform approximation of Bloch
functions. This gives a full characterization of symbols of certain Volterra
operators that act on bounded analytic functions in the disc if the symbol is
assumed to be univalent. Without this assumption the answer is not known, and
as the example at the end of the paper shows, the natural answer is definitely
false.


title: Tachyon warm-intermediate inflation in the light of Planck data

abstract:
  We study the main properties of the warm inflationary model based on Barrow's
solution for the scale factor of the universe. Within this framework we
calculate analytically the basic slow roll parameters for different versions of
warm inflation. We test the performance of this inflationary scenario against
the latest observational data and we verify that the predicted spectral index
and the tensor-to-scalar fluctuation ratio are in excellent agreement with
those of {\it Planck 2015}. Finally, we find that the current predictions are
consistent with those of viable inflationary models.


title:
Determination of hadron-quark phase transition line from lattice QCD and
  two-solar-mass neutron star observations

abstract:
  We aim at drawing the hadron-quark phase transition line in the QCD phase
diagram by using the two phase model (TPM) in which the entanglement
Polyakov-loop extended Nambu--Jona-Lasinio (EPNJL) model with vector-type
four-quark interaction is used for the quark phase and the relativistic mean
field (RMF) model is for the hadron phase. Reasonable TPM is constructed by
using lattice QCD data and neutron star observations as reliable constraints.
For the EPNJL model, we determine the strength of vector-type four-quark
interaction at zero quark chemical potential from lattice QCD data on quark
number density normalized by its Stefan-Boltzmann limit. For the hadron phase,
we consider three RMF models, NL3, TM1 and model proposed by Maruyama, Tatsumi,
Endo and Chiba (MTEC). We find that MTEC is most consistent with the neutron
star observations and TM1 is the second best. Assuming that the hadron-quark
phase transition occurs in the core of neutron star, we explore the
density-dependence of vector-type four-quark interaction. Particularly for the
critical baryon chemical potential at zero temperature, we determine a range
for the quark phase to occur in the core of neutron star.


title:
Some remarks on quasi generalized CR-null geometry in indefinite nearly
  cosymplectic manifolds

abstract:
  In [21], the authors initiated the study of quasi generalized CR (QGCR)-null
submanifolds. In this paper, attention is drawn to some distributions on
ascreen QGCR-null submanifolds in an indefinite nearly cosymplectic manifold.
We characterize totally umbilical and irrotational ascreen QGCR-null
submanifolds. We finally discuss the geometric effects of geodesity conditions
on such submanifold.


title:
Fractional boundary charges in quantum dot arrays with density
  modulation

abstract:
  We show that fractional charges can be realized at the boundaries of a linear
array of tunnel coupled quantum dots in the presence of a periodically
modulated onsite potential. While the charge fractionalization mechanism is
similar to the one in polyacetylene, here the values of fractional charges can
be tuned to arbitrary values by varying the phase of the onsite potential or
the total number of dots in the array. We also find that the fractional
boundary charges, unlike the in-gap bound states, are stable against static
random disorder. We discuss the minimum array size where fractional boundary
charges can be observed.


title: Covert Quantum Communication

abstract:
  We extend covert communication to the quantum regime by showing that covert
quantum communication is possible over optical channels with noise arising
either from the environment or from the sender's lab. In particular, we show
that sequences of qubits can be transmitted covertly by using both a single
photon and a coherent state encoding. We study the possibility of performing
covert quantum key distribution and show that positive key rates and covertness
can be achieved simultaneously. Covert communication requires a secret key
between sender and receiver, which raises the problem of how this key can be
regenerated covertly. We show that covert QKD consumes more key than it can
generate and propose instead a hybrid protocol for covert key regeneration that
uses pseudorandom number generators (PRNGs) together with covert QKD to
regenerate secret keys. The security of the new key is guaranteed by QKD while
the security of the covert communication is at least as strong as the security
of the PRNG.


title: Geometric classification of graph $C^*$-algebras over finite graphs

abstract:
  We address the classification problem for graph $C^*$-algebras of finite
graphs (finitely many edges and vertices), containing the class of
Cuntz-Krieger algebras as a prominent special case. Contrasting earlier work,
we do not assume that the graphs satisfy the standard condition (K), so that
the graph $C^*$-algebras may come with uncountable ideal structures.
  We find that in this generality, stable isomorphism of graph $C^*$-algebras
does not coincide with the geometric notion of Cuntz move equivalence. However,
adding a modest condition on the graphs, the two notions are proved to be
mutually equivalent and equivalent to the $C^*$-algebras having isomorphic
$K$-theories. This proves in turn that under this condition, the graph
$C^*$-algebras are in fact classifiable by $K$-theory, providing in particular
complete classification when the $C^*$-algebras in question are either of real
rank zero or type I/postliminal. The key ingredient in obtaining these results
is a characterization of Cuntz move equivalence using the adjacency matrices of
the graphs.
  Our results are applied to discuss the classification problem for the quantum
lens spaces defined by Hong and Szyma\'nski, and to complete the classification
of graph $C^*$-algebras associated to all simple graphs with four vertices or
less.


title: Random walks and induced Dirichlet forms on self-similar sets

abstract:
  Let $K$ be a self-similar set satisfying the open set condition. Following
Kaimanovich's elegant idea, it has been proved that on the symbolic space $X$
of $K$ a natural augmented tree structure ${\mathfrak E}$ exists; it is
hyperbolic, and the hyperbolic boundary $\partial_HX$ with the Gromov metric is
H\"older equivalent to $K$. In this paper we consider certain reversible random
walks with return ratio $0< \lambda <1$ on $(X, {\mathfrak E})$. We show that
the Martin boundary ${\mathcal M}$ can be identified with $\partial_H X$ and
$K$. With this setup and a device of Silverstein, we obtain precise estimates
of the Martin kernel and the Na\"{i}m kernel in terms of the Gromov product.
Moreover, the Na\"{i}m kernel turns out to be a jump kernel satisfying the
estimate $\Theta (\xi, \eta) \asymp |\xi-\eta|^{-(\alpha+ \beta)}$, where
$\alpha$ is the Hausdorff dimension of $K$ and $\beta$ depends on $\lambda$.
For suitable $\beta$, the kernel defines a regular non-local Dirichlet form on
$K$. This extends the results of Kigami concerning random walks on certain
trees with Cantor-type sets as boundaries.


title:
Discovery of an X-ray Emitting Contact Binary System 2MASS
  J11201034$-$2201340

abstract:
  We report the detection of orbital modulation, a model solution, and X-ray
properties of a newly discovered contact binary, 2MASS J11201034$-$2201340. We
serendipitously found this X-ray point source outside the error ellipse when
searching for possible X-ray counterparts of $\gamma$-ray millisecond pulsars
among the unidentified objects detected by the {\it Fermi Gamma-ray Space
Telescope}. The optical counterpart of the X-ray source (unrelated to the
$\gamma$-ray source) was then identified using archival databases. The
long-term CRTS survey detected a precise signal with a period of
$P=0.28876208(56)$ days. A follow-up observation made by the SLT telescope of
Lulin Observatory revealed the binary nature of the object. Utilizing archived
photometric data of multi-band surveys, we construct the spectral energy
distribution, which is well fitted by a K2V spectral template. The fitting
result of the orbital profile using the Wilson--Devinney code suggests that
2MASS J11201034-2201340 is a short-period A-type contact binary and the more
massive component has a cool spot. The X-ray emission was first noted in
observations made by \swift\, then further confirmed and characterized by an
\xmm\ observation. The X-ray spectrum can be described by a power law or
thermal Bremsstrahlung. Unfortunately, we could not observe significant X-ray
orbital modulation. Finally, according to the spectral energy distribution,
this system is estimated to be 690 pc from Earth with a calculated X-ray
intensity of $(0.7-1.5)\times 10^{30}$ erg s$^{-1}$, which is in the expected
range of an X-ray emitting contact binary.


title: Improving Raw Image Storage Efficiency by Exploiting Similarity

abstract:
  To improve the temporal and spatial storage efficiency, researchers have
intensively studied various techniques, including compression and
deduplication. Through our evaluation, we find that methods such as photo tags
or local features help to identify the content-based similar- ity between raw
images. The images can then be com- pressed more efficiently to get better
storage space sav- ings. Furthermore, storing similar raw images together
enables rapid data sorting, searching and retrieval if the images are stored in
a distributed and large-scale envi- ronment by reducing fragmentation. In this
paper, we evaluated the compressibility by designing experiments and observing
the results. We found that on a statistical basis the higher similarity photos
have, the better com- pression results are. This research helps provide a clue
for future large-scale storage system design.


title: The Nature of CME-Flare Associated Coronal Dimming

abstract:
  Coronal mass ejections (CMEs) are often accompanied by coronal dimming
evident in extreme ultraviolet (EUV) and soft X-ray observations. The locations
of dimming are sometimes considered to map footpoints of the erupting flux
rope. As the emitting material expands in the corona, the decreased plasma
density leads to reduced emission observed in spectral and irradiance
measurements. Therefore, signatures of dimming may reflect properties of CMEs
in the early phase of its eruption. In this study, we analyze the event of
flare, CME, and coronal dimming on December 26, 2011. We use the data from the
Atmospheric Imaging Assembly (AIA) on Solar Dynamics Observatories (SDO) for
disk observations of the dimming, and analyze images taken by EUVI, COR1, and
COR2 onboard the Solar Terrestrial Relations Observatories to obtain the height
and velocity of the associated CMEs observed at the limb. We also measure
magnetic reconnection rate from flare observations. Dimming occurs in a few
locations next to the flare ribbons, and it is observed in multiple EUV
passbands. Rapid dimming starts after the onset of fast reconnection and CME
acceleration, and its evolution well tracks the CME height and flare
reconnection. The spatial distribution of dimming exhibits cores of deep
dimming with a rapid growth, and their light curves are approximately linearly
scaled with the CME height profile. From the dimming analysis, we infer the
process of the CME expansion, and estimate properties of the CME.


title:
Ferroelectric domain inversion and its stability in lithium niobate thin
  film on insulator with different thicknesses

abstract:
  Ferroelectric domain inversion and its effect on the stability of lithium
niobate thin films on insulator (LNOI) are experimentally characterized. Two
sets of specimens with different thicknesses varying from submicron to microns
are selected. For micron thick samples (~28 um), domain structures are achieved
by pulsed electric field poling with electrodes patterned via photolithography.
No domain structure deterioration has been observed for a month as inspected
using polarizing optical microscopy and etching. As for submicron (540 nm)
films, large-area domain inversion is realized by scanning a biased conductive
tip in a piezoelectric force microscope. A graphic processing method is taken
to evaluate the domain retention. A domain life time of 25.0 h is obtained and
possible mechanisms are discussed. Our study gives a direct reference for
domain structure-related applications of LNOI, including guiding wave nonlinear
frequency conversion, nonlinear wavefront tailoring, electro-optic modulation,
and piezoelectric devices.


title:
Interpretation of the structure function of rotation measure in the
  interstellar medium

abstract:
  The observed structure function (SF) of rotation measure (RM) varies as a
broken power-law function of angular scales. The systematic shallowness of its
spectral slope is inconsistent with the standard Kolmogorov scaling. This
motivates us to examine the statistical analysis on RM fluctuations. The
correlations of RM constructed by Lazarian & Pogosyan (2016) are demonstrated
to be adequate in explaining the observed features of RM SFs through a direct
comparison between the theoretically obtained and observationally measured SF
results. By segregating the density and magnetic field fluctuations and
adopting arbitrary indices for their respective power spectra, we find that
when the SFs of RM and emission measure have a similar form over the same range
of angular scales, the statistics of the RM fluctuations reflect the properties
of density fluctuations. RM SFs can be used to evaluate the mean magnetic field
along the line of sight, but cannot serve as an informative source on the
properties of turbulent magnetic field in the interstellar medium. We identify
the spectral break of RM SFs as the inner scale of a shallow spectrum of
electron density fluctuations, which characterizes the typical size of discrete
electron density structures in the observed region.


title: Global well-posedness for the full compressible Navier-Stokes equations

abstract:
  In this paper, we mainly study the Cauchy problem for the full compressible
Navier-Stokes equations in Sobolev spaces. We establish the global
well-posedness of the equations with small initial data by using Friedrich's
method and compactness arguments.


title: K-theory and phase transitions at high energies

abstract:
  The duality between $E_8\times E_8$ heteritic string on manifold $K3\times
T^2$ and Type IIA string compactified on a Calabi-Yau manifold induces a
correspondence between vector bundles on $K3\times T^2$ and Calabi-Yau
manifolds. Vector bundles over compact base space $K3\times T^2$ form the set
of isomorphism classes, which is a semi-ring under the operation of Whitney sum
and tensor product. The construction of semi-ring $Vect\ X$ of isomorphism
classes of complex vector bundles over X leads to the ring $KX=K(Vect\ X)$,
called Grothendieck group. As K3 has no isometries and no non-trivial
one-cycles, so vector bundle winding modes arise from the $T^2$
compactification. Since we have focused on supergravity in d=11, there exist
solutions in d=10 for which space-time is Minkowski space and extra dimensions
are $K3\times T^2$. The complete set of soliton solutions of supergravity
theory is characterized by RR charges, identified by K-theory. Toric
presentation of Calabi-Yau through Batyrev's toric approximation enables us to
connect transitions between Calabi-Yau manifolds, classified by enhanced
symmetry group, with K-theory classification.


title: Online Row Sampling

abstract:
  Finding a small spectral approximation for a tall $n \times d$ matrix $A$ is
a fundamental numerical primitive. For a number of reasons, one often seeks an
approximation whose rows are sampled from those of $A$. Row sampling improves
interpretability, saves space when $A$ is sparse, and preserves row structure,
which is especially important, for example, when $A$ represents a graph.
  However, correctly sampling rows from $A$ can be costly when the matrix is
large and cannot be stored and processed in memory. Hence, a number of recent
publications focus on row sampling in the streaming setting, using little more
space than what is required to store the outputted approximation [KL13,
KLM+14].
  Inspired by a growing body of work on online algorithms for machine learning
and data analysis, we extend this work to a more restrictive online setting: we
read rows of $A$ one by one and immediately decide whether each row should be
kept in the spectral approximation or discarded, without ever retracting these
decisions. We present an extremely simple algorithm that approximates $A$ up to
multiplicative error $\epsilon$ and additive error $\delta$ using $O(d \log d
\log(\epsilon||A||_2/\delta)/\epsilon^2)$ online samples, with memory overhead
proportional to the cost of storing the spectral approximation. We also present
an algorithm that uses $O(d^2$) memory but only requires
$O(d\log(\epsilon||A||_2/\delta)/\epsilon^2)$ samples, which we show is
optimal.
  Our methods are clean and intuitive, allow for lower memory usage than prior
work, and expose new theoretical properties of leverage score based matrix
approximation.


title: Streaming Label Learning for Modeling Labels on the Fly

abstract:
  It is challenging to handle a large volume of labels in multi-label learning.
However, existing approaches explicitly or implicitly assume that all the
labels in the learning process are given, which could be easily violated in
changing environments. In this paper, we define and study streaming label
learning (SLL), i.e., labels are arrived on the fly, to model newly arrived
labels with the help of the knowledge learned from past labels. The core of SLL
is to explore and exploit the relationships between new labels and past labels
and then inherit the relationship into hypotheses of labels to boost the
performance of new classifiers. In specific, we use the label
self-representation to model the label relationship, and SLL will be divided
into two steps: a regression problem and a empirical risk minimization (ERM)
problem. Both problems are simple and can be efficiently solved. We further
show that SLL can generate a tighter generalization error bound for new labels
than the general ERM framework with trace norm or Frobenius norm
regularization. Finally, we implement extensive experiments on various
benchmark datasets to validate the new setting. And results show that SLL can
effectively handle the constantly emerging new labels and provides excellent
classification performance.


title:
An Origin of Multiple Ring Structure and Hidden Planets in HL Tau: A
  Unified Picture by Secular Gravitational Instability

abstract:
  Recent ALMA observation has revealed multiple ring structures formed in a
protoplanetary disk around HL Tau. Prior to the ALMA observation of HL Tau,
theoretical analysis of secular gravitational instability (GI) described a
possible formation of multiple ring structures with separations of 13 AU around
a radius of 100 AU in protoplanetary disks under certain conditions. In this
article, we reanalyze the viability of secular GI by adopting the physical
values inferred from the observations. We derive the radial distributions of
the most unstable wavelength and the growth timescale of secular GI and verify
that secular GI can form the ring structures observed in HL Tau. When a
turbulent viscosity coefficient $\alpha$ remains small in inner region of the
disk, secular GI grows in the whole disk. Thus, the formation of planetary mass
objects should occur first in the inner region as a result of gravitational
fragmentation after the non-linear growth of secular GI. In this case,
resulting objects are expected to create the gaps at $r$ ~ 10 AU and ~ 30 AU.
As a result, all ring structures in HL Tau can be created by secular GI. If
this scenario is realized in HL Tau, the outer region corresponds to the
earlier growth phase of the most unstable mode of secular GI, and the inner
region corresponds to the outcome of the non-linear growth of secular GI.
Therefore, this interpretation suggests that we are possibly witnessing both
the beginning and end of planet formation in HL Tau.


title: Parts for the Whole: The DCT Norm for Extreme Visual Recovery

abstract:
  Here we study the extreme visual recovery problem, in which over 90\% of
pixel values in a given image are missing. Existing low rank-based algorithms
are only effective for recovering data with at most 90\% missing values. Thus,
we exploit visual data's smoothness property to help solve this challenging
extreme visual recovery problem. Based on the Discrete Cosine Transformation
(DCT), we propose a novel DCT norm that involves all pixels and produces smooth
estimations in any view. Our theoretical analysis shows that the total
variation (TV) norm, which only achieves local smoothness, is a special case of
the proposed DCT norm. We also develop a new visual recovery algorithm by
minimizing the DCT and nuclear norms to achieve a more visually pleasing
estimation. Experimental results on a benchmark image dataset demonstrate that
the proposed approach is superior to state-of-the-art methods in terms of peak
signal-to-noise ratio and structural similarity.


title: AdS/dS CFT Correspondence

abstract:
  We propose and study a holographic dual of the type IIB superstring theory of
AdS_5 x S^5 in terms of the N=4 superconformal Yang-Mills theory on dS_4. We
use the bulk to boundary formalism to evaluate the boundary correlation
functions and verify that it agrees with the expected result in dS conformal
field theory. The gauge theory is expected to be UV finite and enjoy exact
SL(2,Z) strong-weak duality. As the string theory Green-Schwarz sigma model
carries an infinite number of classically conserved charges, it also suggest
that the superconformal Yang-Mills theory is integrable and deserves further
studies.