title: Liquid state of hydrogen bond network in ice

abstract:
  Here we show that the Coulomb interaction between violations of the
Bernal-Fowler rules leads to a temperature induced step-wise increase in their
concentration by 6-7 orders of magnitude. This first-order phase transition is
accompanied by commensurable decrease in the relaxation time and can be
interpreted as melting of the hydrogen bond network. The new phase with the
melted hydrogen lattice and survived oxygen one is unstable in the bulk of ice,
and further drastic increase in the concentrations of oxygen interstitials and
vacancies accomplishes the ice melting. The fraction of broken hydrogen bonds
immediately after the melting is about 0.07 of their total number that implies
an essential conservation of oxygen lattice in water.


title: Virtual Reality based Learning Systems

abstract:
  This article is based on studies of the existing literature, focusing on the
states-of-the-arts on virtual reality (VR) and its potential uses in learning.
Different platforms have been used to improve the learning effects of VR that
offers exciting opportunities in various fields. As more and more students want
in a distance, part-time, or want to continue their education, VR has attracted
considerable attention in learning, training, and traditional education. VR
based learning enables operators to bring together all disciplinary resources
in a common playground. The VR base multimedia platform has successfully
demonstrated great potential of education and training. In this paper, we will
discuss existing systems and their uses and address the technical challenges
and future directions.


title: A variant of the Euclid-Mullin sequence containing every prime

abstract:
  We consider a generalization of Euclid's proof of the infinitude of primes
and show that it leads to variants of the Euclid-Mullin sequence that provably
contain every prime number.


title: Weak ergodicity breaking induced by global memory effects

abstract:
  We study the phenomenon of weak ergodicity breaking for a class of globally
correlated random walk dynamics defined over a finite set of states. The
persistence in a given state or the transition to another one depends on the
whole previous temporal history of the system. A set of waiting time
distributions, associated to each state, set the random times between
consecutive steps. Their mean value is finite for all states. The probability
density of time-averaged observables is obtained for different memory
mechanisms. This statistical object explicitly shows departures between time
and ensemble averages. While the mean residence time in each state may result
divergent, we demonstrate that this condition is in general not necessary for
breaking ergodicity. Hence, global memory effects are an alternative mechanism
able to induce this property. Analytical and numerical calculations support
these results.


title:
Magnon Waves on Chains of YIG particles: Dispersion Relations, Faraday
  Rotation, and Power Transmission

abstract:
  We calculate the dispersion relations for magnon waves on a periodic chain of
spherical or cylindrical Yttrium Iron Garnet (YIG) particles. We use the
quasistatic approximation, appropriate when $kd \ll 1$, where $k$ is the wave
number and $d$ the interparticle spacing. In this regime, because of the
magnetic dipole-dipole interaction between the localized magnetic excitations
on neighboring particles, dispersive magnon waves can propagate along the
chain. The waves are analogous to plasmonic waves generated by electric
dipole-dipole interactions between plasmons on neighboring metallic particles.
The magnon waves can be longitudinal ($L$), transverse ($T$), or elliptically
polarized. We find that a linearly polarized magnon wave undergoes a Faraday
rotation as it propagates along the chain. The amount of Faraday rotation can
be tuned by varying the off-diagonal component of the permeability tensor. We
also discuss the possibility of wireless power transmission along the chain
using these coupled magnon waves.


title: Ueda's peak set theorem for general von Neumann algebras

abstract:
  We extend Ueda's peak set theorem for subdiagonal subalgebras of tracial
finite von Neumann algebras, to sigma-finite von Neumann algebras (that is, von
Neumann algebras with a faithful state; which includes those on a separable
Hilbert space, or with separable predual.) To achieve this extension completely
new strategies had to be invented at certain key points, ultimately resulting
in a more operator algebraic proof of the result. Ueda showed in the case of
finite von Neumann algebras that his peak set theorem is the fountainhead of
many other very elegant results, like the uniqueness of the predual of such
subalgebras, a highly refined F and M Riesz type theorem, and a Gleason-Whitney
theorem. The same is true in our more general setting, and indeed we obtain a
quite strong variant of the last mentioned theorem. We also show that set
theoretic issues dash hopes for extending the theorem to some other large
general classes of von Neumann algebras, for example finite or semi-finite
ones. Indeed certain cases of Ueda's peak set theorem, for a von Neumann
algebra M, may be seen as `set theoretic statements' about M that require the
sets to not be `too large'.


title: Interaction Pursuit with Feature Screening and Selection

abstract:
  Understanding how features interact with each other is of paramount
importance in many scientific discoveries and contemporary applications. Yet
interaction identification becomes challenging even for a moderate number of
covariates. In this paper, we suggest an efficient and flexible procedure,
called the interaction pursuit (IP), for interaction identification in
ultra-high dimensions. The suggested method first reduces the number of
interactions and main effects to a moderate scale by a new feature screening
approach, and then selects important interactions and main effects in the
reduced feature space using regularization methods. Compared to existing
approaches, our method screens interactions separately from main effects and
thus can be more effective in interaction screening. Under a fairly general
framework, we establish that for both interactions and main effects, the method
enjoys the sure screening property in screening and oracle inequalities in
selection. Our method and theoretical results are supported by several
simulation and real data examples.


title:
Manifestation of chirality in the vortex lattice in a two-dimensional
  topological superconductor

abstract:
  We study the vortex lattice in a two-dimensional s-wave topological
superconductor with Rashba spin-orbit coupling and Zeeman field by solving the
Bogoliubov-de Gennes equations self-consistently for the superconducting order
parameter. We find that when spin-orbit coupling is relatively weak, one of the
two underlying chiralities in the topological superconducting state can be
strongly manifest in the vortex core structure and govern the response of the
system to vorticity and a nonmagnetic impurity where the vortex is pinned. The
Majorana zero mode in the vortex core is found to be robust against the
nonmagnetic impurity in that it remains effectively a zero-energy bound state
regardless of the impurity potential strength and the major chirality. The spin
polarization of the Majorana bound state depends on the major chirality for
weak spin-orbit coupling, while it is determined simply by the vorticity when
spin-orbit coupling is relatively strong.


title: Algorithms to Compute the Lyndon Array

abstract:
  We first describe three algorithms for computing the Lyndon array that have
been suggested in the literature, but for which no structured exposition has
been given. Two of these algorithms execute in quadratic time in the worst
case, the third achieves linear time, but at the expense of prior computation
of both the suffix array and the inverse suffix array of x. We then go on to
describe two variants of a new algorithm that avoids prior computation of
global data structures and executes in worst-case n log n time. Experimental
evidence suggests that all but one of these five algorithms require only linear
execution time in practice, with the two new algorithms faster by a small
factor. We conjecture that there exists a fast and worst-case linear-time
algorithm to compute the Lyndon array that is also elementary (making no use of
global data structures such as the suffix array).


title:
On the Error Detection Capability of Combined LDPC and CRC Codes for
  Space Telecommand Transmissions

abstract:
  We present a method for estimating the undetected error rate when a cyclic
redundancy check (CRC) is performed on the output of the decoder of short
low-density parity-check (LDPC) codes. This system is of interest for
telecommand links, where new LDPC codes have been designed for updating the
current standard. We show that these new LDPC codes combined with CRC are
adequate for complying with the stringent requirements of this kind of
transmissions in terms of error detection.


title:
Logarithmic degenerations of Landau-Ginzburg models for toric orbifolds
  and global tt^* geometry

abstract:
  We discuss the behavior of Landau-Ginzburg models for toric orbifolds near
the large volume limit. This enables us to express mirror symmetry as an
isomorphism of Frobenius manifolds which aquire logarithmic poles along a
boundary divisor. If the toric orbifold admits a crepant resolution we
construct a global moduli space on the B-side and show that the associated
tt^*-geometry exists globally.


title:
An approach towards the proof of the strong Goldbach's conjecture for
  sufficiently large even integers

abstract:
  We approach a new proof of the strong Goldbach's conjecture for sufficiently
large even integers by applying the Dirichlet's series. Using the Perron
formula and the Residue Theorem in complex variable integration, one could show
that any large even integer is demonstrated as a sum of two primes. In this
paper,the Riemann Hypothesis is assumed to be true in throughout the paper. A
novel function is defined on the natural numbers set.This function is a typical
sieve function.Then based on this function,several new functions are
represented and using the Prime Number Theorem,Sabihi's theorem, and the
Sabihi's second conjecture,the strong Goldbach's conjecture is proved for
sufficiently large even integers.


title:
Looking for imprints of the first stellar generations in metal-poor
  bulge field stars

abstract:
  Context. Efforts to look for signatures of the first stars have concentrated
on metal-poor halo objects. However, the low end of the bulge metallicity
distribution has been shown to host some of the oldest objects in the Milky Way
and hence this Galactic component potentially offers interesting targets to
look at imprints of the first stellar generations. As a pilot project, we
selected bulge field stars already identified in the ARGOS survey as having
[Fe/H] ~ -1 and oversolar [alpha/Fe] ratios, and we used FLAMES-UVES to obtain
detailed abundances of key elements that are believed to reveal imprints of the
first stellar generations. Aims. The main purpose of this study is to analyse
selected ARGOS stars using new high-resolution (R~45,000) and
high-signal-to-noise (S/N >100) spectra. We aim to derive their stellar
parameters and elemental ratios, in particular the abundances of C, N, the
alpha-elements O, Mg, Si, Ca, and Ti, the odd-Z elements Na and Al, the
neutron-capture s-process dominated elements Y, Zr, La, and Ba, and the
r-element Eu. Methods. High-resolution spectra of five field giant stars were
obtained at the 8m VLT UT2-Kueyen telescope with the UVES spectrograph in
FLAMES-UVES configuration. Spectroscopic parameters were derived based on the
excitation and ionization equilibrium of Fe I and Fe II. The abundance analysis
was performed with a MARCS LTE spherical model atmosphere grid and the
Turbospectrum spectrum synthesis code.


title: Notes on compact nilspaces

abstract:
  These notes form the second part of a detailed account of the theory of
nilspaces developed by Camarena and Szegedy. Here we focus on nilspaces
equipped with a compact topology that is compatible with the cube structure,
called compact nilspaces. The material in these notes relies on the first part
of our exposition (available as arXiv:1601.03693), and it expands on the third
chapter of the paper of Camarena and Szegedy, providing more detailed proofs of
their results. To that end we also include several additional results that are
implicit in their paper.


title:
The $\ell$-adic trace formula for dg-categories and Bloch's conductor
  conjecture

abstract:
  Building on recent results by A. Blanc, M. Robalo and the authors, we present
an $\ell$-adic trace formula for smooth and proper dg-categories over a base
$\mathbb{E}_{\infty}$-algebra $B$. We also give a variant when $B$ is only an
$\mathbb{E}_2$-algebra. As an application of this trace formula, we propose a
strategy of proof of Bloch's conductor conjecture. This is a research
announcement and detailed proofs will appear elsewhere.


title:
Spin splitting of electron states in lattice-mismatched (110)-oriented
  quantum wells

abstract:
  We show that for lattice-mismatched zinc-blende-type (110)-grown quantum
wells a significant contribution to the zero-magnetic-field spin splitting of
electron subbands comes from strain-induced spin-orbit coupling. Combining
envelope function theory and atomistic tight-binding approach we calculate
spin-orbit splitting constants for realistic quantum wells. It is found that
the strain due to lattice mismatch in conventional GaAs/AlGaAs structures may
noticeably modify the spin splitting while in InGaAs/GaAs structures it plays a
major role and may even change the sign of the spin splitting constant.


title: Fibered faces, veering triangulations, and the arc complex

abstract:
  We study the connections between subsurface projections in curve and arc
complexes in fibered 3-manifolds and Agol's veering triangulation. The main
theme is that large-distance subsurfaces in fibers are associated to large
simplicial regions in the veering triangulation, and this correspondence holds
uniformly for all fibers in a given fibered face of the Thurston norm.


title:
Molecular force spectroscopy of kinetochore-microtubule attachment {\it
  in silico}: Mechanical signatures of an unusual catch bond and collective
  effects

abstract:
  Measurement of the life time of attachments formed by a single microtubule
(MT) with a single kinetochore (kt) {\it in-vitro} under force-clamp conditions
had earlier revealed a catch-bond-like behavior. In the past the physical
origin of this apparently counter-intuitive phenomenon was traced to the nature
of the force-dependence of the (de-)polymerization kinetics of the MTs. Here
first the same model MT-kt attachment is subjected to external tension that
increases linearly with time until rupture occurs. In our {\it force-ramp}
experiments {\it in-silico}, the model displays the well known `mechanical
signatures' of a catch-bond probed by molecular force spectroscopy. Exploiting
this new evidence, we have further strengthened the analogy between MT-kt
attachments and common ligand-receptor bonds in spite of the crucial
differences in their underlying physical mechanisms. We then extend the
formalism to model the stochastic kinetics of an attachment formed by a bundle
of multiple parallel microtubules with a single kt considering the effect of
rebinding under force-clamp and force-ramp conditions. From numerical studies
of the model we predict the trends of variation of the mean life time and mean
rupture force with the increasing number of MTs in the bundle. Both the mean
life time and the mean rupture force display nontrivial nonlinear dependence on
the maximum number of MTs that can attach simultaneously to the same kt.


title: The structure theory of Nilspaces I

abstract:
  This paper forms the first part of a series by the authors [GMV2,GMV3]
concerning the structure theory of nilspaces of Antol\'in Camarena and Szegedy.
A nilspace is a compact space $X$ together with closed collections of cubes
$C^n(X)\subseteq X^{2^n}$, $n=1,2,\ldots$ satisfying some natural axioms.
Antol\'in Camarena and Szegedy proved that from these axioms it follows that
(certain) nilspaces are isomorphic (in a strong sense) to an inverse limit of
nilmanifolds. The aim of our project is to provide a new self-contained
treatment of this theory and give new applications to topological dynamics.
  This paper provides an introduction to the project from the point of view of
applications to higher order Fourier analysis. We define and explain the basic
definitions and constructions related to cubespaces and nilspaces and develop
the weak structure theory, which is the first stage of the proof of the main
structure theorem for nilspaces. Vaguely speaking, this asserts that a nilspace
can be built as a finite tower of extensions where each of the successive
fibers is a compact abelian group.
  We also make some modest innovations and extensions to this theory. In
particular, we consider a class of maps that we term fibrations, which are
essentially equivalent to what are termed fiber-surjective morphisms by
Anatol\'in Camarena and Szegedy, and we formulate and prove a relative analogue
of the weak structure theory alluded to above for these maps. These results
find applications elsewhere in the project.


title:
Extremes of Gaussian Random Fields with regularly varying dependence
  structure

abstract:
  Let $X(t), t\in \mathcal{T}$ be a centered Gaussian random field with
variance function $\sigma^2(\cdot)$ that attains its maximum at the unique
point $t_0\in \mathcal{T}$, and let $M(\mathcal{T}):=\sup_{t\in \mathcal{T}}
X(t)$. For $\mathcal{T}$ a compact subset of $\R$, the current literature
explains the asymptotic tail behaviour of $M(\mathcal{T})$ under some
regularity conditions including that $1- \sigma(t)$ has a polynomial decrease
to 0 as $t \to t_0$. In this contribution we consider more general case that
$1- \sigma(t)$ is regularly varying at $t_0$. We extend our analysis to random
fields defined on some compact $\mathcal{T}\subset \R^2$, deriving the exact
tail asymptotics of $M(\mathcal{T})$ for the class of Gaussian random fields
with variance and correlation functions being regularly varying at $t_0$. A
crucial novel element is the analysis of families of Gaussian random fields
that do not possess locally additive dependence structures, which leads to
qualitatively new types of asymptotics.


title:
Observational analysis of the well--correlated diffuse bands: 6196 and
  6614 \AA

abstract:
  We confirm, using spectra from seven observatories, that the diffuse bands
6196 and 6614 are very tightly correlated. However, their strength ratio is not
constant as well as profile shapes. Apparently the two interstellar features do
not react in unison to the varying physical conditions of different
interstellar clouds.


title: The structure theory of Nilspaces II: Representation as nilmanifolds

abstract:
  This paper forms the second part of a series by the authors [GMV1,GMV3]
concerning the structure theory of nilspaces of Antol\'in Camarena and Szegedy.
A nilspace is a compact space $X$ together with closed collections of cubes
$C_n(X)\subseteq X^{2^n}$, $n=1,2,\ldots$ satisfying some natural axioms. From
these axioms it follows that a nilspace can be built as a finite tower of
extensions where each of the successive fibers is a compact abelian group.
  Our main result is a new proof of a result due to Antol\'in Camarena and
Szegedy [CS12], stating that if each of these groups is a torus then $X$ is
isomorphic (in a strong sense) to a nilmanifold $G/\Gamma$. We also extend the
theorem to a setting where the nilspace arises from a dynamical system $(X,T)$.
These theorems are a key stepping stone towards the general structure theorem
in [GMV3] (which again closely resembles the main theorem of [CS12]).
  The main technical tool, enabling us to deduce algebraic information from
topological data, consists of existence and uniqueness results for solutions of
certain natural functional equations, again modelled on the theory in [CS12].


title: Logic of Local Inference for Contextuality in Quantum Physics and Beyond

abstract:
  Contextuality in quantum physics provides a key resource for quantum
information and computation. The topological approach in [Abramsky and
Brandenburger, New J. Phys., 2011, Abramsky et al., CSL 2015, 2015]
characterizes contextuality as "global inconsistency" coupled with "local
consistency", revealing it to be a phenomenon also found in many other fields.
This has yielded a logical method of detecting and proving the "global
inconsistency" part of contextuality. Our goal is to capture the other, "local
consistency" part, which requires a novel approach to logic that is sensitive
to the topology of contexts. To achieve this, we formulate a logic of local
inference by using context-sensitive theories and models in regular categories.
This provides a uniform framework for local consistency, and lays a foundation
for high-level methods of detecting, proving, and moreover using contextuality
as computational resource.


title:
The structure theory of Nilspaces III: Inverse limit representations and
  topological dynamics

abstract:
  This paper forms the third part of a series by the authors [GMV1,GMV2]
concerning the structure theory of nilspaces. A nilspace is a compact space $X$
together with closed collections of cubes $C^n(X)\subseteq X^{2^n}$,
$n=1,2,\ldots$, satisfying some natural axioms. Our goal is to extend the
structure theory of nilspaces obtained by Antol\'in Camarena and Szegedy, and
to provide new proofs.
  Our main result is that, under the technical assumption that $C^n(X)$ is a
connected space for all $n$, then $X$ is isomorphic (in a strong sense) to an
inverse limit of nilmanifolds. This is a direct and slight generalization of
the main result of Antol\'in Camarena and Szegedy.
  We also apply our methods to obtain structure theorems in the setting of
topological dynamics. Specifically, if $H$ is a group (subject to very mild
topological assumptions) and $(H,X)$ is a minimal dynamical system, then we
give a simple characterization of the maximal pronilfactor of $X$. This
generalizes the case $H = \mathbb{Z}$, which is a theorem of Host, Kra and
Maass, although even in that case we give a significantly different proof.


title: A handle is enough for a hard game of Pull

abstract:
  We are going to show that some variants of a puzzle called Pull in which the
boxes have handles (i.e. we can only pull the boxes in certain directions) are
NP-hard


title: D rare/forbidden decays at BESIII

abstract:
  In this document we present the latest result on rare/forbidden decays for D
mesons at the BESIII experiment. Based on 2.92/fb data taken at the
center-of-mass energy 3.773 GeV with the BESIII detector, the flavor-changing
neutral current process of neutral D decays into two gammas is searched using a
double tag technique, while the decays of charged D decays into a charged
kaon/pion plus two electrons/positrons are studied based on a single tag
method. The resulting upper limits are still above the Standard Model
predictions.


title: Parity-time symmetry under magnetic flux

abstract:
  We study a parity-time (PT) symmetric ring lattice, with one pair of balanced
gain and loss located at opposite positions. The system remains PT-symmetric
when threaded by a magnetic flux; however, the PT symmetry is sensitive to the
magnetic flux, in the presence of a large balanced gain and loss, or in a large
system. We find a threshold gain/loss, above which, any nontrivial magnetic
flux breaks the PT symmetry. We obtain the maximally tolerable magnetic flux
for the exact PT-symmetric phase, which is approximately linearly dependent on
a weak gain/loss.


title:
Anomalous localized resonance phenomena in the nonmagnetic,
  finite-frequency regime

abstract:
  The phenomenon of anomalous localized resonance (ALR) is observed at the
interface between materials with positive and negative material parameters and
is characterized by the fact that, when a given source is placed near the
interface, the electric and magnetic fields start to have very fast and large
oscillations around the interface as the absorption in the materials becomes
very small while they remain smooth and regular away from the interface.
  In this paper, we discuss the phenomenon of anomalous localized resonance
(ALR) in the context of an infinite slab of homogeneous, nonmagnetic material
($\mu=1$) with permittivity $\epsilon_s=-1-\mathrm{i}\delta$ for some small
loss $\delta \ll 1$ surrounded by positive, nonmagnetic, homogeneous media. We
explicitly characterize the limit value of the product between frequency and
the width of slab beyond which the ALR phenomenon does not occur and analyze
the situation when the phenomenon is observed. In addition, we also construct
sources for which the ALR phenomenon never appears.


title:
Rational first integrals of geodesic equations and generalised hidden
  symmetries

abstract:
  We discuss novel generalisations of Killing tensors, which are introduced by
considering rational first integrals of geodesic equations. We introduce the
notion of inconstructible generalised Killing tensors, which cannot be
constructed from ordinary Killing tensors. Moreover, we introduce
inconstructible rational first integrals, which are constructed from
inconstructible generalised Killing tensors, and provide a method for checking
the inconstructibility of a rational first integral. Using the method, we show
that the rational first integral of the Collinson-O'Donnell solution is not
inconstructible. We also provide several examples of metrics admitting an
inconstructible rational first integral in two and four dimensions, by using
the Maciejewski-Przybylska system. Furthermore, we attempt to generalise other
hidden symmetries such as Killing-Yano tensors.


title:
Synthesis, characterization and physical properties of layered
  bismuthide PtBi$_2$

abstract:
  We report details of single crystal growth of stoichiometric bismuthide
PtBi$_2$ whose structure consists of alternate stacking of Pt layer sandwiched
by Bi bilayer along the $c$-axis. The compound crystallizes in space group P-3
with a hexagonal unit cell of $a$=$b$=6.553$\AA$, $c$=6.165$\AA$. The
magnetization data show opposite sign for fields parallel and perpendicular to
the Pt layers, respectively. The $T$-dependent resistivity is typical of a
metal and the magnetic response shows clear two types of charge carriers and
the validity of the semi-classical Kohler's rule. Its physical properties was
discussed in comparison with recently proposed topological superconductor
$\beta$-PdBi$_2$.


title:
Quasi-integrability in deformed sine-Gordon models and infinite towers
  of conserved charges

abstract:
  We have studied the space-reflection symmetries of some soliton solutions of
deformed sine-Gordon models in the context of the quasi-integrability concept.
Considering a dual pair of anomalous Lax representations of the deformed model
we compute analytically and numerically an infinite number of alternating
conserved and asymptotically conserved charges through a modification of the
usual techniques of integrable field theories. The charges associated to
two-solitons with a definite parity under space-reflection symmetry, i.e.
kink-kink (odd parity) and kink-antikink (even parity) scatterings with equal
and opposite velocities, split into two infinite towers of conserved and
asymptotically conserved charges. For two-solitons without definite parity
under space-reflection symmetry (kink-kink and kink-antikink scatterings with
unequal and opposite velocities) our numerical results show the existence of
the asymptotically conserved charges only. However, we show that in the
center-of-mass reference frame of the two solitons the parity symmetries and
their associated set of exactly conserved charges can be restored. Moreover,
the positive parity breather-like (kink-antikink bound state) solution exhibits
a tower of exactly conserved charges and a subset of charges which are periodic
in time. We back up our results with extensive numerical simulations which also
demonstrate the existence of long lived breather-like states in these models.
The time evolution has been simulated by the 4th order Runge-Kutta method
supplied with non-reflecting boundary conditions.


title:
Phase Balancing of Two and Three-Agent Heterogeneous Gain Systems With
  Extensions to Multiple Agents

abstract:
  This paper studies the phase balancing of a two and three-agent system where
the agents are coupled through heterogeneous controller gains. Balancing refers
to the situation in which the movement of agents causes the position of their
centroid to become stationary. We generalize existing results and show that by
using heterogeneous controller gains, the velocity directions of the agents in
balanced formation can be controlled. The effect of heterogeneous gains on the
reachable set of these velocity directions is further analyzed. For the
two-agents case, the locus of steady-state location of the centroid is also
analyzed against the variations in the heterogeneous controller gains.
Simulations are given to illustrate the theoretical findings.


title:
Formation of plano-convex micro-lens array in fused silica glass using
  CO2 laser assisted reshaping technique

abstract:
  We report on fabricating high-fill-factor plano-convex spherical and square
micro-lens arrays on fused silica glass surface using CO2 laser assisted
reshaping technique. Initially, periodic micro-pillars have been encoded on the
glass surface by means of a femtosecond laser beam. Afterwards, the
micro-pillars are polished several times by irradiating a CO2 laser beam on top
of the micro-pillars. Consequently, spherical micro-lens array with micro-lens
size of 50 um x 50 um and square micro-lens array with micro-lens size of 100
um x 100 um are formed on fused silica glass surface. We also study the
intensity distribution of light passed through the spherical micro-lens array
engraved glass sample. The simulation result shows that, the focal length of
the spherical micro-lens array is 35 um. Furthermore, we investigate the
optical properties of the micro-lens array engraved glass samples. The proposed
CO2 laser based reshaping technique is simple and fast that shows promises in
fabrication arrays of smooth micro-lenses in various transparent materials.


title:
The violation of a uniqueness theorem and an invariant in the
  application of Poincar\'{e}--Perron theorem to Heun's equation

abstract:
  The domain of convergence of a Heun function obtained through the
Poincar\'{e}--Perron (P--P) theorem is not absolute convergence but conditional
one [2]. We show that a uniqueness theorem is not available if we apply the
P--P theorem into the Heun's equation. We verify that the uniqueness theorem is
only applicable when a local Heun function is absolutely convergent.


title: A simple and provable algorithm for sparse diagonal CCA

abstract:
  Given two sets of variables, derived from a common set of samples, sparse
Canonical Correlation Analysis (CCA) seeks linear combinations of a small
number of variables in each set, such that the induced canonical variables are
maximally correlated. Sparse CCA is NP-hard.
  We propose a novel combinatorial algorithm for sparse diagonal CCA, i.e.,
sparse CCA under the additional assumption that variables within each set are
standardized and uncorrelated. Our algorithm operates on a low rank
approximation of the input data and its computational complexity scales
linearly with the number of input variables. It is simple to implement, and
parallelizable. In contrast to most existing approaches, our algorithm
administers precise control on the sparsity of the extracted canonical vectors,
and comes with theoretical data-dependent global approximation guarantees, that
hinge on the spectrum of the input data. Finally, it can be straightforwardly
adapted to other constrained variants of CCA enforcing structure beyond
sparsity.
  We empirically evaluate the proposed scheme and apply it on a real
neuroimaging dataset to investigate associations between brain activity and
behavior measurements.

categories: stat.ML cs.DS cs.IT math.IT math.OC stat.ME


title:
Coding Schemes for Securing Cyber-Physical Systems Against Stealthy Data
  Injection Attacks

abstract:
  This paper considers a method of coding the sensor outputs in order to detect
stealthy false data injection attacks. An intelligent attacker can design a
sequence of data injection to sensors and actuators that pass the state
estimator and statistical fault detector, based on knowledge of the system
parameters. To stay undetected, the injected data should increase the state
estimation errors while keep the estimation residues small. We employ a coding
matrix to change the original sensor outputs to increase the estimation
residues under intelligent data injection attacks. This is a low cost method
compared with encryption schemes over all sensor measurements in communication
networks. We show the conditions of a feasible coding matrix under the
assumption that the attacker does not have knowledge of the exact coding
matrix. An algorithm is developed to compute a feasible coding matrix, and, we
show that in general, multiple feasible coding matrices exist. To defend
against attackers who estimates the coding matrix via sensor and actuator
measurements, time-varying coding matrices are designed according to the
detection requirements. A heuristic algorithm to decide the time length of
updating a coding matrix is then proposed.


title:
Variable Selection in Seemingly Unrelated Regressions with Random
  Predictors

abstract:
  This paper considers linear model selection when the response is
vector-valued and the predictors are randomly observed. We propose a new
approach that decouples statistical inference from the selection step in a
"post-inference model summarization" strategy. We study the impact of predictor
uncertainty on the model selection procedure. The method is demonstrated
through an application to asset pricing.


title: 2-Dimensional Finite Impulse Response Graph-Temporal Filters

abstract:
  Finite impulse response (FIR) graph filters play a crucial role in the field
of signal processing on graphs. However, when the graph signal is time-varying,
the state of the art FIR graph filters do not capture the time variations of
the input signal. In this work, we propose an extension of FIR graph filters to
capture also the signal variations over time. By considering also the past
values of the graph signal, the proposed FIR graph filter extends naturally to
a 2-dimensional filter, capturing jointly the signal variations over the graph
and time. As a particular case of interest we focus on 2-dimensional separable
graph-temporal filters, which can be implemented in a distributed fashion at
the price of higher communication costs. This allows us to give filter
specifications and perform the design independently in the graph and temporal
domain. The work is concluded by analyzing the proposed approach for stochastic
graph signals, where the first and second order moments of the output signal
are characterized.


title:
Damped Infinite Energy Solutions of the 3D Euler and Boussinesq
  Equations

abstract:
  We revisit a family of infinite-energy solutions of the 3D incompressible
Euler equations proposed by Gibbon et al. [9] and shown to blowup in finite
time by Constantin [6]. By adding a damping term to the momentum equation we
examine how the damping coefficient can arrest this blowup. Further, we show
that similar infinite-energy solutions of the inviscid 3D Boussinesq system
with damping can develop a singularity in finite time as long as the damping
effects are insufficient to arrest the (undamped) 3D Euler blowup in the
associated damped 3D Euler system.


title:
Asymptotic analysis of multi-lumps solutions in the
  Kadomtsev-Petviashvili-(I) equation

abstract:
  Inspired by the works of Y. Ohta and J. Yang, one constructs the lumps
solutions in the Kadomtsev-Petviashvili-(I) equation using the Grammian
determinants. It is shown that the locations of peaks will depend on the real
roots of Wronskian of the orthogonal polynomials for the asymptotic behaviors
in some particular cases. Also, one can prove that all the locations of peaks
are on a vertical line when time approaches - $\infty$, and then they will be
on a horizontal line when time approaches $\infty$, i.e., there is a rotation
$\frac{\pi}{2}$ after interaction.


title:
Universality of fractal to non-fractal morphological transitions in
  stochastic growth processes

abstract:
  Stochastic growth processes give rise to diverse intricate structures
everywhere and across all scales in nature. Despite the seemingly unrelated
complex phenomena at their origin, the Laplacian growth theory has succeeded in
unifying their treatment under one framework, nonetheless, important aspects
regarding fractal to non-fractal morphological transitions, coming from the
competition between screening and anisotropy-driven forces, still lacks a
comprehensive description. Here we provide such unified description,
encompassing all the known characteristics for these transitions, as well as
new universal ones, through the statistical mix of basic models of
particle-aggregation and the introduction of a phenomenological physically
meaningful dimensionality function, that characterizes the fractality of a
symmetry-breaking process induced by a generalized anisotropy-driven force. We
also show that the generalized Laplacian growth (dielectric breakdown) model
belongs to this class. Moreover, our results provide important insights on the
dynamical origins of mono/multi-fractality in pattern formation, that generally
occur in far-from-equilibrium processes.


title:
Observation and Simulation of the Variable Gamma-ray Emission from
  PSR~J2021+4026

abstract:
  Pulsars are rapidly spinning and highly magnetized neutron stars, with highly
stable rotational period and gradual spin-down over a long timescale due to the
loss of radiation. Glitches refer to the events that suddenly increase the
rotational speed of a pulsar. The exact causes of glitches and the resulting
processes are not fully understood. It is generally believed that couplings
between the normal matter and the superfluid components, and the starquakes,
are the common causes of glitches. In this study, one famous glitching pulsar,
PSR~J2021+4026, is investigated. PSR~J2021+4026 is the first variable gamma-ray
pulsar observed by Fermi. From the gamma-ray observations, it is found that the
pulsar experienced a significant flux drop, an increase in the spin-down rate,
a change in the pulse profile and a shift in the spectral cut-off to a lower
energy, simultaneously around 2011 October 16. To explain these effects on the
high-energy emissions by the glitch of PSR~J2021+4026, we hypothesized the
glitch to be caused by the rearrangement of the surface magnetic field due to
the crustal plate tectonic activities on the pulsar which is triggered by a
starquake. In this glitch event, the inclination angle of the magnetic dipole
axis is slightly shifted. This proposition is then tested by numerical modeling
using a three-dimensional two-layer outer gap model. The simulation results
indicate that a modification of the inclination angle can affect the pulse
profile and the spectral properties, which can explain the observation changes
after the glitch.


title: Improving Crowdsourced Live Streaming with Aggregated Edge Networks

abstract:
  Recent years have witnessed a dramatic increase of user-generated video
services. In such user-generated video services, crowdsourced live streaming
(e.g., Periscope, Twitch) has significantly challenged today's edge network
infrastructure: today's edge networks (e.g., 4G, Wi-Fi) have limited uplink
capacity support, making high-bitrate live streaming over such links
fundamentally impossible. In this paper, we propose to let broadcasters (i.e.,
users who generate the video) upload crowdsourced video streams using
aggregated network resources from multiple edge networks. There are several
challenges in the proposal: First, how to design a framework that aggregates
bandwidth from multiple edge networks? Second, how to make this framework
transparent to today's crowdsourced live streaming services? Third, how to
maximize the streaming quality for the whole system? We design a
multi-objective and deployable bandwidth aggregation system BASS to address
these challenges: (1) We propose an aggregation framework transparent to
today's crowdsourced live streaming services, using an edge proxy box and
aggregation cloud paradigm; (2) We dynamically allocate geo-distributed cloud
aggregation servers to enable MPTCP (i.e., multi-path TCP), according to
location and network characteristics of both broadcasters and the original
streaming servers; (3) We maximize the overall performance gain for the whole
system, by matching streams with the best aggregation paths.


title: Fluctuations in Hertz chains at equilibrium

abstract:
  We examine the long-term behaviour of non-integrable, energy-conserved, 1D
systems of macroscopic grains interacting via a contact-only generalized Hertz
potential and held between stationary walls. Existing dynamical studies showed
the absence of energy equipartitioning in such systems, hence their long-term
dynamics was described as quasi-equilibrium. Here we show that these systems do
in fact reach thermal equilibrium at sufficiently long times, as indicated by
the calculated heat capacity. As a byproduct, we show how fluctuations of
system quantities, and thus the distribution functions, are influenced by the
Hertz potential. In particular, the variance of the system's kinetic energy
probability density function is reduced by a factor related to the contact
potential.


title:
Towards the Classification of Finite Simple Groups with exactly Three or
  Four Supercharacter Theories

abstract:
  A supercharacter theory for a finite group $G$ is a set of superclasses each
of which is a union of conjugacy classes together with a set of sums of
irreducible characters called supercharacters that together satisfy certain
compatibility conditions.The aim of this paper is to give a description of some
finite simple groups with exactly three or four supercharacter theories.


title:
About the existence of solutions for a hybrid nonlinear generalized
  fractional pantograph equation

abstract:
  The main purpose of this paper is to study the existence of solutions for the
following hybrid nonlinear fractional pantograph equation $$
\left\{\begin{aligned} &D_{0+}^\alpha
\left[\frac{x(t)}{f(t,x(t),x(\varphi(t)))}\right]=g(t,x(t),x(\rho(t))),\,\,0<t<1\\
&x(0)=0, \end{aligned} \right. $$ where $\alpha\in (0,1)$, $\varphi$ and $\rho$
are functions from $[0,1]$ into itself and $D_{0+}^\alpha$ denotes the
Riemann-Liouville fractional derivative. The main tool of our study is a
generalization of Darbo's fixed point theorem associated to measures of
non-compactness. Also, we present an example illustrating our results.


title:
Existence of a unique positive solution for a singular fractional
  boundary value problem

abstract:
  In the present work, we discuss the existence of a unique positive solution
of a boundary value problem for nonlinear fractional order equation with
singularity. Precisely, order of equation $D_{0+}^\alpha u(t)=f(t,u(t))$
belongs to $(3,4]$ and $f$ has a singularity at $t=0$ and as a boundary
conditions we use $u(0)=u(1)=u'(0)=u'(1)=0$. Using fixed point theorem, we
prove the existence of unique positive solution of the considered problem.


title: New Signal Designs for Enhanced Spatial Modulation

abstract:
  In this paper, we present three new signal designs for Enhanced Spatial
Modulation (ESM), which was recently introduced by the present authors. The
basic idea of ESM is to convey information bits not only by the index(es) of
the active transmit antenna(s) as in conventional Spatial Modulation (SM), but
also by the types of the signal constellations used. The original ESM schemes
were designed with reference to single-stream SM and involved one or more
secondary modulations in addition to the primary modulation. Compared to
single-stream SM, they provided either higher throughput or improved
signal-to-noise ratio (SNR). In the present paper, we focus on multi-stream SM
(MSM) and present three new ESM designs leading to increasing SNR gains when
they are operated at the same spectral efficiency. The secondary signal
constellations used in the first two designs are based on a single geometric
interpolation step in the signal constellation plane, while the third design
also makes use of additional constellations derived through a second
interpolation step. The new ESM signal designs are described for MIMO systems
with four transmit antennas two of which are active, but we also briefly
present extensions to higher numbers of antennas. Theoretical analysis and
simulation results indicate that the proposed designs provide a significant SNR
gain over MSM.


title:
Geodesic motion in the spacetime of a static charged black hole in
  $f(R)$ gravity

abstract:
  In the present paper we study the geodesic motion of test particles and light
rays in the spacetime of a static charged black hole in $f(R)$ gravity. The
complete set of analytic solutions of the geodesic equations in the spacetime
of this black hole are presented. The geodesic equations are solved in terms of
Weierstrass elliptic $\wp$ function and derivatives of Kleinian $\sigma$
function. With the help of parametric diagrams and effective potentials we
analyze the geodesic motion and give a list of all possible orbit types. The
different types of the resulting orbits are characterized in terms of the
conserved energy, angular momentum, charge and cosmological constant.


title:
Detailed study of geodesics in the Kerr-Newman-(A)dS spactime and the
  rotating charged black hole spacetime in $f(R)$ gravity

abstract:
  We perform a detailed study of the geodesic equations in the spacetime of the
static and rotating charged black hole corresponding to the Kerr-Newman-(A)dS
spacetime. We derive the equations of motion for test particles and light rays
and present their solutions in terms of the Weierstrass $\wp$, $\zeta$ and
$\sigma$ functions as well as the Kleinian $\sigma$ function. With the help of
parametric diagrams and effective potentials we analyze the geodesic motion and
classify the possible orbit types. This spacetime is also a solution of $f(R)$
gravity with a constant curvature scalar.


title:
Reeb components with complex leaves and their symmetries I : The
  automorphism groups and Schr\"oder's equation on the half line

abstract:
  We review the standard Hopf construction of Reeb components with leafwise
complex structure and determine the group of leafwise holomorphic smooth
automorphisms for tame Reeb components in the case of complex leaf dimension
one. For this, we solve the Schr\"oder type functional equation on the half
line for expanding diffeomorphism. As a result, we see that the automorphism
group of one with trivial linear holonomy on the boundary contains an infinite
dimensional vector space, while in the case of non-trivial linear holonomy the
group is of finite dimensional.


title:
Quantile-based optimization under uncertainties using adaptive Kriging
  surrogate models

abstract:
  Uncertainties are inherent to real-world systems. Taking them into account is
crucial in industrial design problems and this might be achieved through
reliability-based design optimization (RBDO) techniques. In this paper, we
propose a quantile-based approach to solve RBDO problems. We first transform
the safety constraints usually formulated as admissible probabilities of
failure into constraints on quantiles of the performance criteria. In this
formulation, the quantile level controls the degree of conservatism of the
design. Starting with the premise that industrial applications often involve
high-fidelity and time-consuming computational models, the proposed approach
makes use of Kriging surrogate models (a.k.a. Gaussian process modeling).
Thanks to the Kriging variance (a measure of the local accuracy of the
surrogate), we derive a procedure with two stages of enrichment of the design
of computer experiments (DoE) used to construct the surrogate model. The first
stage globally reduces the Kriging epistemic uncertainty and adds points in the
vicinity of the limit-state surfaces describing the system performance to be
attained. The second stage locally checks, and if necessary, improves the
accuracy of the quantiles estimated along the optimization iterations.
Applications to three analytical examples and to the optimal design of a car
body subsystem (minimal mass under mechanical safety constraints) show the
accuracy and the remarkable efficiency brought by the proposed procedure.


title:
Star formation laws in both Galactic massive clumps and external
  galaxies: An extensive study with dust continuum, HCN (4-3), and CS (7-6)

abstract:
  We observed 146 Galactic clumps in HCN (4-3) and CS (7-6) with the Atacama
Submillimeter Telescope Experiment (ASTE) 10-m telescope. A tight linear
relationship between star formation rate and gas mass traced by dust continuum
emission was found for both Galactic clumps and the high redshift (z>1) star
forming galaxies (SFGs), indicating a constant gas depletion time of ~100 Myr
for molecular gas in both Galactic clumps and high z SFGs. However, low z
galaxies do not follow this relation and seem to have a longer global gas
depletion time. The correlations between total infrared luminosities (L_TIR)
and molecular line luminosities (L'_mol) of HCN (4-3) and CS (7-6) are tight
and sublinear extending down to clumps with LTIR~10^{3} L_sun. These
correlations become linear when extended to external galaxies. A bimodal
behavior in the LTIR--L'mol correlations was found for clumps with different
dust temperature, luminosity-to-mass ratio, and sigmaline/sigmavir. Such
bimodal behavior may be due to evolutionary effects. The slopes of LTIR--L'mol
correlations become more shallow as clumps evolve. We compared our results with
lower J transition lines in wu et al. (2010). The correlations between clump
masses and line luminosities are close to linear for low effective excitation
density tracers but become sublinear for high effective excitation density
tracers for clumps with LTIR larger than LTIR~10^4.5 Lsun. High effective
excitation density tracers cannot linearly trace the total clump masses,
leading to a sublinear correlations for both Mclump-L'mol and LTIR-L'mol
relations.


title:
Synchronization failure caused by interplay between noise and network
  heterogeneity

abstract:
  We investigate synchronization in complex networks of noisy phase
oscillators. We find that, while too weak a coupling is not sufficient for the
whole system to synchronize, too strong a coupling induces a nontrivial type of
phase slip among oscillators, resulting in synchronization failure. Thus, an
intermediate coupling range for synchronization exists, which becomes narrower
when the network is more heterogeneous. Analyses of two noisy oscillators
reveal that nontrivial phase slip is a generic phenomenon when noise is present
and coupling is strong. Therefore, the low synchronizability of heterogeneous
networks can be understood as a result of the difference in effective coupling
strength among oscillators with different degrees; oscillators with high
degrees tend to undergo phase slip while those with low degrees have weak
coupling strengths that are insufficient for synchronization.


title: Hyperbolic 3-Manifolds Groups are Subgroup Conjugacy Separable

abstract:
  A group $G$ is called subgroup conjugacy separable if for every pair of
non-conjugate finitely generated subgroups of $G$, there exists a finite
quotient of $G$ where the images of these subgroups are not conjugate. It is
proved that the fundamental group of a hyperbolic 3-manifold (closed or with
cusps) is subgroup conjugacy separable.


title: Coordinate Descent Face-Off: Primal or Dual?

abstract:
  Randomized coordinate descent (RCD) methods are state-of-the-art algorithms
for training linear predictors via minimizing regularized empirical risk. When
the number of examples ($n$) is much larger than the number of features ($d$),
a common strategy is to apply RCD to the dual problem. On the other hand, when
the number of features is much larger than the number of examples, it makes
sense to apply RCD directly to the primal problem. In this paper we provide the
first joint study of these two approaches when applied to L2-regularized ERM.
First, we show through a rigorous analysis that for dense data, the above
intuition is precisely correct. However, we find that for sparse and structured
data, primal RCD can significantly outperform dual RCD even if $d \ll n$, and
vice versa, dual RCD can be much faster than primal RCD even if $n \ll d$.
Moreover, we show that, surprisingly, a single sampling strategy minimizes both
the (bound on the) number of iterations and the overall expected complexity of
RCD. Note that the latter complexity measure also takes into account the
average cost of the iterations, which depends on the structure and sparsity of
the data, and on the sampling strategy employed. We confirm our theoretical
predictions using extensive experiments with both synthetic and real data sets.


title:
Two-dimensional $\chi^{2}$ solitons generated by the downconversion of
  Airy waves

abstract:
  Conversion of truncated Airy waves (AWs) carried by the second-harmonic (SH)
component into axisymmetric $\chi^{2}$ solitons is considered in the 2D system
with the quadratic nonlinearity. The spontaneous conversion is driven by the
parametric instability of the SH wave. The input in the form of the AW vortex
is considered too. As a result, one, two, or three stable solitons emerge in a
well-defined form, unlike the recently studied 1D setting, where the picture is
obscured by radiation jets. Shares of the total power captured by the emerging
solitons and conversion efficiency are found as functions of parameters of the
AW input.


title:
Quasi steady state approximation of the small clusters in
  Becker-D\"oring equations leads to boundary conditions in the
  Lifshitz-Slyozov limit

abstract:
  This papers addresses the connection between two classical models of phase
transition phenomena describing different stages of the growth of clusters. The
Becker-D\"oring model (BD) describes discrete-sized clusters through an
infinite set of ordinary differential equations. The Lifshitz-Slyozov equation
(LS) is a transport partial differential equation on the continuous half-line
$x\in (0,+\infty)$. We introduce a scaling parameter $\varepsilon>0$, which
accounts for the grid size of the state space in the BD model, and recover the
LS model in the limit $\varepsilon\to 0$. The connection has been already
proven in the context of outgoing characteristic at the boundary $x=0$ for the
LS model, when small clusters tend to shrink. The main novelty of this work
resides in a new estimate on the growth of small clusters, which behave at a
fast time scale. Through a rigorous quasi steady state approximation, we derive
boundary conditions for the incoming characteristic case, when small clusters
tend to grow.


title:
Liquid-liquid transition in supercooled aqueous solution involving a
  low-temperature phase similar to low-density amorphous water

abstract:
  The striking anomalies in physical properties of supercooled water that were
discovered in the 1960-70s, remain incompletely understood and so provide both
a source of controversy amongst theoreticians, and a stimulus to
experimentalists and simulators to find new ways of penetrating the
"crystallization curtain" that effectively shields the problem from solution.
Recently a new door on the problem was opened by showing that, in ideal
solutions, made using ionic liquid solutes, water anomalies are not destroyed
as earlier found for common salt and most molecular solutes, but instead are
enhanced to the point of precipitating an apparently first order liquid-liquid
transition. The evidence was a spike in apparent heat capacity during cooling
that could be fully reversed during reheating before any sign of ice
crystallization appeared. Here, we use decoupled-oscillator infrared
spectroscopy to define the structural character of this phenomenon using
similar down and upscan rates as in the calorimetric study. Thin-film samples
also permit slow scans (1 K/min) in which the transition has a width of less
than 1 K, and is fully reversible. The OH spectrum changes discontinuously at
the phase-transition temperature, indicating a discrete change in hydrogen-bond
structure. The spectral changes show that the low-temperature liquid is more
strongly hydrogen bonded and less disordered as compared to the
high-temperature liquid. The spectrum of the low-temperature liquid is
essentially that seen in low-density amorphous water. This similarity suggests
that the liquid-liquid transition observed here also exists in neat undercooled
water, providing a unified explanation for many of its anomalies.


title:
Marginal resonances and intermittent behaviour in the motion in the
  vicinity of a separatrix

abstract:
  A condition upon which sporadic bursts (intermittent behaviour) of the
relative energy become possible is derived for the motion in the chaotic layer
around the separatrix of non-linear resonance. This is a condition for the
existence of a marginal resonance, i.e. a resonance located at the border of
the layer. A separatrix map in Chirikov's form [Chirikov, B. V., Phys. Reports
52, 263 (1979)] is used to describe the motion. In order to provide a
straightforward comparison with numeric integrations, the separatrix map is
synchronized to the surface of the section farthest from the saddle point. The
condition of intermittency is applied to clear out the nature of the phenomenon
of bursts of the eccentricity of chaotic asteroidal trajectories in the 3/1
mean motion commensurability with Jupiter. On the basis of the condition, a new
intermittent regime of resonant asteroidal motion is predicted and then
identified in numeric simulations.


title:
A quasiperiodically forced skew-product on the cylinder without
  fixed-curves

abstract:
  In [FJJK] the Sharkovski\u{i} Theorem was extended to periodic orbits of
strips of quasiperiodic skew products in the cylinder. In this paper we deal
with the following natural question that arises in this setting: Does
Sharkovski\u{i} Theorem holds when restricted to curves instead of general
strips?mWe answer this question in the negative by constructing a
counterexample: We construct a map having a periodic orbit of period 2 of
curves (which is, in fact, the upper and lower circles of the cylinder) and
without any invariant curve. In particular this shows that there exist
quasiperiodic skew products in the cylinder without invariant curves.


title: On Explore-Then-Commit Strategies

abstract:
  We study the problem of minimising regret in two-armed bandit problems with
Gaussian rewards. Our objective is to use this simple setting to illustrate
that strategies based on an exploration phase (up to a stopping time) followed
by exploitation are necessarily suboptimal. The results hold regardless of
whether or not the difference in means between the two arms is known. Besides
the main message, we also refine existing deviation inequalities, which allow
us to design fully sequential strategies with finite-time regret guarantees
that are (a) asymptotically optimal as the horizon grows and (b) order-optimal
in the minimax sense. Furthermore we provide empirical evidence that the theory
also holds in practice and discuss extensions to non-gaussian and
multiple-armed case.


title: Partial orders on metric measure spaces

abstract:
  A partial order on the set of metric measure spaces is defined; it
generalizes the Lipschitz order of Gromov. We show that our partial order is
closed when metric measure spaces are equipped with the Gromov-weak topology
and give a new characterization for the Lipschitz order. We will then consider
some probabilistic applications. The main importance is given to the study of
Fleming-Viot processes with different resampling rates. Besides that
application we also consider tree-valued branching processes and two semigroups
on metric measure spaces.


title: Critical bases for ternary alphabets

abstract:
  Glendinning and Sidorov discovered an important feature of the
Komornik-Loreti constant $q'\approx1.78723$ in non-integer base expansions on
two-letter alphabets: in bases $1<q<q'$ only countably numbers have unique
expansions, while for $q\ge q'$ there is a continuum of such numbers. We
investigate the analogous question for ternary alphabets.


title:
Dominance of outflowing electric currents on decaparsec to kiloparsec
  scales in extragalactic jets

abstract:
  Helical magnetic fields embedded in the jets of active galactic nuclei (AGNs)
are required by the broad range of theoretical models that advocate for
electromagnetic launching of the jets. In most models, the direction of the
magnetic field is random, but if the axial field is generated by a Cosmic
Battery generated by current in the direction of rotation in the accretion
disk, there is a correlation between the directions of the spin of the AGN
accretion disk and of the axial field, which leads to a specific direction for
the axial electric current, azimuthal magnetic field, and the resulting
observed transverse Faraday-rotation (FR) gradient across the jet, due to the
systematic change in the line-of-sight magnetic field.
  We consider new observational evidence for the presence of a nested helical
magnetic-field structure such as would be brought about by the operation of the
Cosmic Battery, and make predictions about the expected behavior of transverse
FR gradients observed on decaparsec and kiloparsec scales. The collected
results can be understood if the dominant azimuthal field on parsec scales
corresponds to an axial electric current flowing inward along the jet, whereas
the (weaker) dominant azimuthal field on kiloparsec scales corresponds to a
outward-flowing current in the outer sheath of the jet and/or an extended disk
wind.


title: 2-categories and cyclic homology

abstract:
  The topic of this thesis is the application of distributive laws between
comonads to the theory of cyclic homology. Explicitly, our main aims are: 1) To
study how the cyclic homology of associative algebras and of Hopf algebras in
the original sense of Connes and Moscovici arises from a distributive law, and
to clarify the role of different notions of bimonad in this generalisation. 2)
To extend the procedure of twisting the cyclic homology of a unital associative
algebra to any duplicial object defined by a distributive law. 3) To study the
universality of Bohm and Stefan's approach to constructing duplicial objects,
which we do in terms of a 2-categorical generalisation of Hochschild
(co)homology. 4) To characterise those categories whose nerve admits a
duplicial structure.


title:
Search for top squark pair production in compressed-mass-spectrum
  scenarios in proton-proton collisions at sqrt(s) = 8 TeV using the alpha[T]
  variable

abstract:
  An inclusive search is performed for supersymmetry in final states containing
jets and an apparent imbalance in transverse momentum, pt[miss], due to the
production of unobserved weakly interacting particles in pp collisions at a
centre-of-mass energy of 8 TeV. The data, recorded with the CMS detector at the
CERN LHC, correspond to an integrated luminosity of 18.5 inverse femtobarns.
The dimensionless kinematic variable alpha[T] is used to discriminate between
events with genuine pt[miss] associated with unobserved particles and spurious
values of pt[miss] arising from jet energy mismeasurements. No excess of event
yields above the expected standard model backgrounds is observed. The results
are interpreted in terms of constraints on the parameter space of several
simplified models of supersymmetry that assume the pair production of top
squarks. The search provides sensitivity to a broad range of top squark decay
modes, including the two-body decay top squark to c chi0, where c is a charm
quark and chi0 is the lightest neutralino, as well as the four-body decay top
squark to b f f' chi0, where b is a bottom quark and f and f' are fermions
produced in the decay of an intermediate off-shell W boson. These modes
dominate in scenarios in which the top squark and lightest neutralino are
nearly degenerate in mass. For these modes, top squarks with masses as large as
260 and 230 GeV are excluded, respectively, for the two- and four-body decays.


title:
MacWilliams type identities on the Lee and Euclidean weights for linear
  codes over $\mathbb{Z}_{\ell}$

abstract:
  Motivated by the works of Shiromoto [3] and Shi et al. [4], we study the
existence of MacWilliams type identities with respect to Lee and Euclidean
weight enumerators for linear codes over $\mathbb{Z}_{\ell}.$ Necessary and
sufficient conditions for the existence of MacWilliams type identities with
respect to Lee and Euclidean weight enumerators for linear codes over
$\mathbb{Z}_{\ell}$ are given. Some examples about such MacWilliams type
identities are also presented.


title: Reimagining the Living Room

abstract:
  An attempt to seek out and understand emerging trends and some of the
challenges we face when dealing with an increasing amount and complexity of
entertainment technologies in our homes, particularly in spaces that are both
private and public. Accepting the premise that this influx of technologies will
continue, the author identified some of the challenges that consumers,
manufacturers, distributors and creators of content are facing today in
incorporating these technologies into home life. Anticipating an imminent
transformation, the author proposes a new approach to smart homes and an
updated model for content distribution.


title:
Wasserstein approximations of the L\'evy area random walk via polynomial
  perturbations of Gaussian distributions

abstract:
  We construct a coupling between the random walk composed of L\'evy area
increments from a $d$-dimensional Brownian motion and a random walk composed of
quadratic polynomials of Gaussian random variables. This coupling construction
is used to produce a new pathwise approximation scheme for stochastic
differential equations in the preprint [Flint-Lyons-2015]. The coupling
arguments of the present paper are based extensively on the recent coupling
results of Davie concerning a multidimensional variant of the
Koml\'os-Major-Tusn\'ady theorem and Wasserstein estimates for polynomial
perturbations of Gaussian measures.


title:
Harder-Narasimhan stacks for principal bundles in higher dimensions and
  arbitrary characteristics

abstract:
  Let $G$ be a split reductive group over a field $k$ of arbitrary
characteristic, chosen suitably. Let $X\to S$ be a smooth projective morphism
of locally noetherian $k$-schemes, with geometrically connected fibers. We show
that for each Harder-Narasimhan type $\tau$ for principal $G$-bundles, all
pairs consisting of a principal $G$-bundle on a fiber of $X\to S$ together with
a given canonical reduction of HN-type $\tau$ form an algebraic stack
$Bun_{X/S}^{\tau}(G)$ over $S$. The forgetful $1$-morphism $Bun_{X/S}^{\tau}(G)
\to Bun_{X/S}(G)$ to the algebraic stack of all principal $G$-bundles on fibers
of $X\to S$ is a schematic morphism, which is of finite type, separated,
radicial, and induces an isomorphism on residue fields of all points of
$Bun_{X/S}^{\tau}(G)$. It factors via an open substack $Bun_{X/S}^{\ngtr
\tau}(G)$ of $Bun_{X/S}(G)$, inducing a finite morphism $Bun_{X/S}^{\tau}(G)
\to Bun_{X/S}^{\ngtr \tau}(G)$. This is a closed embedding if the Behrend
conjecture is satisfied by $G$. The results of this paper hold in arbitrary
characteristic, and in fact it gives better proofs of the results of our
earlier papers which had assumed the characteristic to be zero. Along the way
we give a new proof of the existence of a canonical reduction over any base
field in all dimensions, and we also prove openness of semistability and
semicontinuity of canonical type in a family.


title:
Optimal Scalar Linear Index Codes for One-Sided Neighboring
  Side-Information Problems

abstract:
  The capacity of symmetric instance of the multiple unicast index coding
problem with neighboring antidotes (side-information) with number of messages
equal to the number of receivers was given by Maleki \textit{et al.} In this
paper, we construct matrices of size $ m \times n (m \geq n)$ over $F_q$ such
that any $n$ adjacent rows of the matrix are linearly independent. By using
such matrices, we give an optimal scalar linear index codes over $F_q$ for the
symmetric one-sided antidote problems considered by Maleki \textit{et al.} for
any given number of messages and one-sided antidotes. The constructed codes are
independent of field size and hence works over every field.


title:
Arithmetic with X-ray images of galaxy clusters: effective equation of
  state for small-scale perturbations in the ICM

abstract:
  We discuss a novel technique of manipulating X-ray images of galaxy clusters
to reveal the nature of small-scale density/temperature perturbations in the
intra cluster medium (ICM). As we show, this technique can be used to
differentiate between sound waves and isobaric perturbations in Chandra images
of the Perseus and M87/Virgo clusters. The comparison of the manipulated images
with the radio data and with the results of detailed spectral analysis shows
that this approach successfully classifies the types of perturbations and helps
to reveal their nature. For the central regions (5-100 kpc) of the M87 and
Perseus clusters this analysis suggests that observed images are dominated by
isobaric perturbations, followed by perturbations caused by bubbles of
relativistic plasma and weak shocks. Such a hierarchy is best explained in a
"slow" AGN feedback scenario, when much of the mechanical energy output of a
central black hole is captured by the bubble enthalpy that is gradually
released during buoyant rise of the bubbles. The "image arithmetic" works best
for prominent structure and for datasets with excellent statistics, visualizing
the perturbations with a given effective equation of state. The same approach
can be extended to faint perturbations via cross-spectrum analysis of surface
brightness fluctuations in X-ray images in different energy bands.


title:
Identifying Gene-Environment Interactions with A Least Relative Error
  Approach

abstract:
  For complex diseases, the interactions between genetic and environmental risk
factors can have important implications beyond the main effects. Many of the
existing interaction analyses conduct marginal analysis and cannot accommodate
the joint effects of multiple main effects and interactions. In this study, we
conduct joint analysis which can simultaneously accommodate a large number of
effects. Significantly different from the existing studies, we adopt loss
functions based on relative errors, which offer a useful alternative to the
"classic" methods such as the least squares and least absolute deviation.
Further to accommodate censoring in the response variable, we adopt a weighted
approach. Penalization is used for identification and regularized estimation.
Computationally, we develop an effective algorithm which combines the
majorize-minimization and coordinate descent. Simulation shows that the
proposed approach has satisfactory performance. We also analyze lung cancer
prognosis data with gene expression measurements.


title:
Oscillation Frequencies for Simultaneous Trapping of Heteronuclear
  Alkali Atoms

abstract:
  We investigate oscillation frequencies for simultaneous trapping of more than
one type of alkali atoms in a common optical lattice. For this purpose, we
present numerical results for magic trapping conditions, where the oscillation
frequencies for two different kind of alkali atoms using laser lights in the
wavelength range 500-1200 nm are same. These wavelengths will be of immense
interest for studying static and dynamic properties of boson-boson,
boson-fermion, fermion-fermion, and boson-boson-boson mixtures involving
different isotopes of Li, Na, K, Rb, Cs and Fr alkali atoms. In addition to
this, we were also able to locate a magic wavelength around 808.1 nm where all
the three Li, K, and Rb atoms are found to be suitable for oscillating at the
same frequency in a common optical trap.


title: Coded Caching Clusters with Device-to-Device Communications

abstract:
  We consider a geographically constrained caching community where popular data
files are cached on mobile terminals and distributed through Device-to-Device
(D2D) communications. Further, to ensure availability, data files are protected
against user mobility, or churn, with erasure coding. Communication and storage
costs (in units of energy) are considered. We focus on finding the coding
method that minimizes the overall cost in the network. Closed-form expressions
for the expected energy consumption incurred by data delivery and redundancy
maintenance are derived, and it is shown that coding significantly decreases
the overall energy consumption -- by more than 90% in a realistic scenario. It
is further shown that D2D caching can also yield notable economical savings for
telecommunication operators. Our results are illustrated by numerical examples
and verified by extensive computer simulations.


title: Classification of smooth horizontal Schubert varieties

abstract:
  We show that the smooth horizontal Schubert subvarieties of a rational
homogeneous variety $G/P$ are homogeneously embedded cominuscule $G'/P'$, and
are classified by subdiagrams of a Dynkin diagram. This generalizes the
classification of smooth Schubert varieties in cominuscule $G/P$.


title:
Tight (Lower) Bounds for the Fixed Budget Best Arm Identification Bandit
  Problem

abstract:
  We consider the problem of \textit{best arm identification} with a
\textit{fixed budget $T$}, in the $K$-armed stochastic bandit setting, with
arms distribution defined on $[0,1]$. We prove that any bandit strategy, for at
least one bandit problem characterized by a complexity $H$, will misidentify
the best arm with probability lower bounded by
$$\exp\Big(-\frac{T}{\log(K)H}\Big),$$ where $H$ is the sum for all sub-optimal
arms of the inverse of the squared gaps. Our result disproves formally the
general belief - coming from results in the fixed confidence setting - that
there must exist an algorithm for this problem whose probability of error is
upper bounded by $\exp(-T/H)$. This also proves that some existing strategies
based on the Successive Rejection of the arms are optimal - closing therefore
the current gap between upper and lower bounds for the fixed budget best arm
identification problem.


title:
On the chain rule formulas for divergences and applications to
  conservation laws

abstract:
  In this paper we prove a nonautonomous chain rule formula for the
distributional divergence of the composite function
$\boldsymbol{v}(x)=\boldsymbol{B}(x,u(x))$, where $\boldsymbol{B}(\cdot,t)$ is
a divergence--measure vector field and $u$ is a function of bounded variation.
As an application, we prove a uniqueness result for scalar conservation laws
with discontinuous flux.


title:
Spatially resolved electronic structure of an isovalent nitrogen center
  in GaAs

abstract:
  Small numbers of nitrogen dopants dramatically modify the electronic
properties of GaAs, generating very large shifts in the conduction-band
energies with nonlinear concentration dependence, and impurity-associated
spatially-localized resonant states within the conduction band. Cross-sectional
scanning tunneling microscopy provides the local electronic structure of single
nitrogen dopants at the (110) GaAs surface, yielding highly anisotropic spatial
shapes when the empty states are imaged. Measurements of the resonant states
relative to the GaAs surface states and their spatial extent allow an
unambiguous assignment of specific features to nitrogen atoms at different
depths below the cleaved (110) surface. Multiband tight binding calculations
around the resonance energy of nitrogen in the conduction band match the imaged
features. The spatial anisotropy is attributed to the tetrahedral symmetry of
the bulk lattice. Additionally, the voltage dependence of the electronic
contrast for two features in the filled state imaging suggest these features
could be related to a locally modified surface state.


title: A New Ferromagnetic Superconductor: CsEuFe$_4$As$_4$

abstract:
  Superconductivity (SC) and ferromagnetism (FM) are in general antagonistic,
which makes their coexistence very rare. Following our recent discovery of
robust coexistence of SC and FM in RbEuFe$_4$As$_4$ [Y. Liu et al., arXiv:
1605.04396 (2016)], here we report another example of such a coexistence in its
sister compound CsEuFe$_4$As$_4$, synthesized for the first time. The new
material exhibits bulk SC at 35.2 K and Eu$^{2+}$-spin ferromagnetic ordering
at 15.5 K, demonstrating that it is a new robust ferromagnetic superconductor.


title:
Enhanced light-vapor interactions and all optical switching in a chip
  scale micro-ring resonator coupled with atomic vapor

abstract:
  The coupling of atomic and photonic resonances serves as an important tool
for enhancing light-matter interactions and enables the observation of
multitude of fascinating and fundamental phenomena. Here, by exploiting the
platform of atomic-cladding wave guides, we experimentally demonstrate the
resonant coupling of rubidium vapor and an atomic cladding micro ring
resonator. Specifically, we observed cavity-atom coupling in the form of Fano
resonances having a distinct dependency on the relative frequency detuning
between the photonic and the atomic resonances. Moreover, we were able to
significantly enhance the efficiency of all optical switching in the V-type
pump-probe scheme. The coupled system of micro-ring resonator and atomic vapor
is a promising building block for a variety of light vapor experiments, as it
offers a very small footprint, high degree of integration and extremely strong
confinement of light and vapor. As such it may be used for important
applications, such as all optical switching, dispersion engineering (e.g. slow
and fast light) and metrology, as well as for the observation of important
effects such as strong coupling, Purcell enhancement and bistability.


title: Global sensitivity analysis using low-rank tensor approximations

abstract:
  In the context of global sensitivity analysis, the Sobol' indices constitute
a powerful tool for assessing the relative significance of the uncertain input
parameters of a model. We herein introduce a novel approach for evaluating
these indices at low computational cost, by post-processing the coefficients of
polynomial meta-models belonging to the class of low-rank tensor
approximations. Meta-models of this class can be particularly efficient in
representing responses of high-dimensional models, because the number of
unknowns in their general functional form grows only linearly with the input
dimension. The proposed approach is validated in example applications, where
the Sobol' indices derived from the meta-model coefficients are compared to
reference indices, the latter obtained by exact analytical solutions or
Monte-Carlo simulation with extremely large samples. Moreover, low-rank tensor
approximations are confronted to the popular polynomial chaos expansion
meta-models in case studies that involve analytical rank-one functions and
finite-element models pertinent to structural mechanics and heat conduction. In
the examined applications, indices based on the novel approach tend to converge
faster to the reference solution with increasing size of the experimental
design used to build the meta-model.


title: Rate Control under Heavy Traffic with Strategic Servers

abstract:
  We consider a large queueing system that consists of many strategic servers
that are weakly interacting. Each server processes jobs from its unique
critically loaded buffer and controls the rate of arrivals and departures
associated with its queue to minimize its expected cost. The rates and the cost
functions in addition to depending on the control action, can depend, in a
symmetric fashion, on the size of the individual queue and the empirical
measure of the states of all queues in the system. In order to determine an
approximate Nash equilibrium for this finite player game we construct a
Lasry-Lions type mean-field game (MFG) for certain reflected diffusions that
governs the limiting behavior. Under conditions, we establish the convergence
of the Nash-equilibrium value for the finite size queuing system to the value
of the MFG.


title:
A Self-Managed Architecture for Sensor Networks Based on Real Time Data
  Analysis

abstract:
  Wireless sensor networks (WSNs) have been adopted as merely data producers
for years. However, the data collected by WSNs can also be used to manage their
operation and avoid unnecessary measurements that do not provide any new
knowledge about the environment. The benefits are twofold because wireless
sensor nodes may save their limited energy resources and also reduce the
wireless medium occupancy. We present a self-managed platform that collects and
stores data from sensor nodes, analyzes its contents and uses the built
knowledge to adjust the operation of the entire network. The system
architecture facilitates the incorporation of traditional WSNs into the
Internet of Things by abstracting the lower communication layers and allowing
decisions based on the data relevance. Finally, we demonstrate the platform
optimizing a WSN's operation at runtime, based on different real-time data
analysis.


title: Market Dynamics of Best-Response with Lookahead

abstract:
  One attractive approach to market dynamics is the level $k$ model in which a
level $0$ player adopts a very simple response to current conditions, a level
$1$ player best-responds to a model in which others take level $0$ actions, and
so forth. (This is analogous to $k$-ply exploration of game trees in AI, and to
receding-horizon control in control theory.) If players have deterministic
mental models with this kind of finite-level response, there is obviously no
way their mental models can all be consistent. Nevertheless, there is
experimental evidence that people act this way in many situations, motivating
the question of what the dynamics of such interactions lead to.
  We address this question in the setting of Fisher Markets with constant
elasticities of substitution (CES) utilities, in the weak gross substitutes
(WGS) regime. We show that despite the inconsistency of the mental models, and
even if players' models change arbitrarily from round to round, the market
converges to its unique equilibrium. (We show this for both synchronous and
asynchronous discrete-time updates.) Moreover, the result is computationally
feasible in the sense that the convergence rate is linear, i.e., the distance
to equilibrium decays exponentially fast. To the best of our knowledge, this is
the first result that demonstrates, in Fisher markets, convergence at any rate
for dynamics driven by a plausible model of seller incentives. Even for the
simple case of (level $0$) best-response dynamics, where we observe that
convergence at some rate can be derived from recent results in convex
optimization, our result is the first to demonstrate a linear rate of
convergence.


title: Flexible constrained de Finetti reductions and applications

abstract:
  De Finetti theorems show how sufficiently exchangeable states are
well-approximated by convex combinations of i.i.d. states. Recently, it was
shown that in many quantum information applications a more relaxed de Finetti
reduction (i.e. only a matrix inequality between the symmetric state and one of
de Finetti form) is enough, and that it leads to more concise and elegant
arguments. Here we show several uses and general flexible applicability of a
constrained de Finetti reduction in quantum information theory, which was
recently discovered by Duan, Severini and Winter. In particular we show that
the technique can accommodate other symmetries commuting with the permutation
action, and permutation-invariant linear constraints. We then demonstrate that,
in some cases, it is also fruitful with convex constraints, in particular
separability in a bipartite setting. This is a constraint particularly
interesting in the context of the complexity class $\mathrm{QMA}(2)$ of
interactive quantum Merlin-Arthur games with unentangled provers, and our
results relate to the soundness gap amplification of $\mathrm{QMA}(2)$
protocols by parallel repetition. It is also relevant for the regularization of
certain entropic channel parameters. Finally, we explore an extension to
infinite-dimensional systems, which usually pose inherent problems to de
Finetti techniques in the quantum case.


title: Heisenberg Necklace Model in Magnetic Field

abstract:
  Motivated by the experimental realizations of nearly one-dimensional spin-1/2
Heisenberg model found in chain cuprates SrCuO$_2$ and Sr$_2$CuO$_3$, which
remain in a quantum-critical Luttinger liquid state down to temperatures that
are much lower than in-chain exchange coupling, we consider the perturbation to
this state caused by interactions with nuclear spins on the same sites. We
study the low-energy sector of the Heisenberg Necklace model and estimate the
effect of the coupling between the nuclear and the electronic spins on the
overall spins dynamics and its dependence on the magnetic field. We find that
the Necklace model has a characteristic energy scale, $\Lambda \sim
J^{1/3}(\gamma I)^{2/3}$, at which the coupling between spins of the necklace
and the spins of the Heisenberg chain becomes strong. In the strong magnetic
field $\mu_B B > \Lambda$ the low energy spectrum is gapless, but two gapless
bosonic modes have different velocities whose ratio at strong fields approaches
a universal number, $\sqrt 2 +1$. In the case of Sr$_2$CuO$_3$ the energy scale
$\Lambda $ is sizable and comparable to the Neel ordering temperature induced
by the inter-chain coupling, and thus could noticeably modify the low
temperature magnon dynamics. We further find that the above energy scale is
insensitive to strong magnetic field, $\mu_B B \gg \Lambda \sim J^{1/3}(\gamma
I)^{2/3}$, and therefore the interaction with nuclear spins cannot lead to
unusually strong magnetic field dependence of the magnon spectrum observed by
ESR in Sr$_2$CuO$_3$, which has been attributed to the magnon interaction with
the Higgs mode.


title: Shock-Turbulence Interaction in Core-Collapse Supernovae

abstract:
  Nuclear shell burning in the final stages of the lives of massive stars is
accompanied by strong turbulent convection. The resulting fluctuations aid
supernova explosion by amplifying the non-radial flow in the post-shock region.
In this work, we investigate the physical mechanism behind this amplification
using a linear perturbation theory. We model the shock wave as a
one-dimensional planar discontinuity and consider its interaction with
vorticity and entropy perturbations in the upstream flow. We find that, as the
perturbations cross the shock, their total turbulent kinetic energy is
amplified by a factor of $\sim\!2$, while the average linear size of turbulent
eddies decreases by about the same factor. These values are not sensitive to
the parameters of the upstream turbulence and the nuclear dissociation
efficiency at the shock. Finally, we discuss the implication of our results for
the supernova explosion mechanism. We show that the upstream perturbations can
decrease the critical neutrino luminosity for producing explosion by several
percent.


title: Semi-supervised Zero-Shot Learning by a Clustering-based Approach

abstract:
  In some of object recognition problems, labeled data may not be available for
all categories. Zero-shot learning utilizes auxiliary information (also called
signatures) describing each category in order to find a classifier that can
recognize samples from categories with no labeled instance. In this paper, we
propose a novel semi-supervised zero-shot learning method that works on an
embedding space corresponding to abstract deep visual features. We seek a
linear transformation on signatures to map them onto the visual features, such
that the mapped signatures of the seen classes are close to labeled samples of
the corresponding classes and unlabeled data are also close to the mapped
signatures of one of the unseen classes.
  We use the idea that the rich deep visual features provide a representation
space in which samples of each class are usually condensed in a cluster. The
effectiveness of the proposed method is demonstrated through extensive
experiments on four public benchmarks improving the state-of-the-art prediction
accuracy on three of them.


title:
Long-term multi-wavelength variability and correlation study of
  Markarian 421 from 2007 to 2009

abstract:
  We study the multi-band variability and correlations of the TeV blazar Mrk
421 on year time scales, which can bring additional insight on the processes
responsible for its broadband emission. We observed Mrk 421 in the very high
energy (VHE) gamma-ray range with the Cherenkov telescope MAGIC-I from March
2007 to June 2009 for a total of 96 hours of effective time after quality cuts.
The VHE flux variability is quantified with several methods, including the
Bayesian Block algorithm, which is applied to data from Cherenkov telescopes
for the first time. The 2.3 year long MAGIC light curve is complemented with
data from the Swift/BAT and RXTE/ASM satellites and the KVA, GASP-WEBT, OVRO,
and Mets\"ahovi telescopes from February 2007 to July 2009, allowing for an
excellent characterisation of the multi-band variability and correlations over
year time scales. Mrk 421 was found in different gamma-ray emission states
during the 2.3 year long observation period. Flares and different levels of
variability in the gamma-ray light curve could be identified with the Bayesian
Block algorithm. The same behaviour of a quiet and active emission was found in
the X-ray light curves measured by Swift/BAT and the RXTE/ASM, with a direct
correlation in time. The behaviour of the optical light curve of GASP-WEBT and
the radio light curves by OVRO and Mets\"ahovi are different as they show no
coincident features with the higher energetic light curves and a less variable
emission. The fractional variability is overall increasing with energy. The
comparable variability in the X-ray and VHE bands and their direct correlation
during both high- and low-activity periods spanning many months show that the
electron populations radiating the X-ray and gamma-ray photons are either the
same, as expected in the Synchrotron-Self-Compton mechanism, or at least
strongly correlated, as expected in electromagnetic cascades.


title:
Connecting the LHC diphoton excess to the Galatic center gamma-ray
  excess

abstract:
  The recent LHC Run-2 data have shown a possible excess in diphoton events,
suggesting the existence of a new resonance $\phi$ with mass $M\sim 750$~GeV.
If $\phi$ plays the role of a portal particle connecting the Standard Model and
the invisible dark sector, the diphoton excess should be correlated with
another photon excess, namely, the excess in the diffuse gamma rays towards the
Galactic center, which can be interpreted by the annihilation of dark
matter(DM). We investigate the necessary conditions for a consistent
explanation for the two photon excesses, especially the requirement on the
width-to-mass ratio $\Gamma/M$ and $\phi$ decay channels, in a collection of DM
models where the DM particle can be scalar, fermionionic and vector, and $\phi$
can be generated through $s$-channel $gg$ fusion or $q\bar q$ annihilation. We
show that the minimally required $\Gamma/M$ is determined by a single parameter
proportional to $(m_{\chi}/M)^{n}$, where the integer $n$ depends on the nature
of the DM particle. We find that for the scalar DM model with $\phi$ generated
from $q\bar q$ annihilation, the minimally required $\Gamma/M$ can be as low as
$\mathcal{O}(10^{-3})$. For the scalar DM model with $\phi$ generated from $gg$
fusion and fermionic DM model with $\phi$ from $q\bar q$ annihilation, the
required $\Gamma/M$ are typically of $\mathcal{O}(10^{-2})$. The vector DM
models, however, require very large $\Gamma/M$ of order one. For the DM models
which can consistently explain both the excesses,the predicted cross sections
for gamma-ray line are typically of
$\mathcal{O}(10^{-31}-10^{-29})~\text{cm}^{3}\text{s}^{-1}$, which are close to
the current limits from the Fermi-LAT experiment.


title:
Sequence-specific polyampholyte phase separation in membraneless
  organelles

abstract:
  Liquid-liquid phase separation of charge/aromatic-enriched intrinsically
disordered proteins (IDPs) is critical in the biological function of
membraneless organelles. Much of the physics of this recent discovery remains
to be elucidated. Here we present a theory in the random phase approximation to
account for electrostatic effects in polyampholyte phase separations, yielding
predictions consistent with recent experiments on the IDP Ddx4. The theory is
applicable to any charge pattern and thus provides a general analytical
framework for studying sequence dependence of IDP phase separation.


title: Michaelis-Menten dynamics in protein subnetworks

abstract:
  To understand the behaviour of complex systems it is often necessary to use
models that describe the dynamics of subnetworks. It has previously been
established using projection methods that such subnetwork dynamics generically
involves memory of the past, and that the memory functions can be calculated
explicitly for biochemical reaction networks made up of unary and binary
reactions. However, many established network models involve also
Michaelis-Menten kinetics, to describe e.g. enzymatic reactions. We show that
the projection approach to subnetwork dynamics can be extended to such
networks, thus significantly broadening its range of applicability. To derive
the extension we construct a larger network that represents enzymes and enzyme
complexes explicitly, obtain the projected equations, and finally take the
limit of fast enzyme reactions that gives back Michaelis-Menten kinetics. The
crucial point is that this limit can be taken in closed form. The outcome is a
simple procedure that allows one to obtain a description of subnetwork
dynamics, including memory functions, starting directly from any given network
of unary, binary and Michaelis-Menten reactions. Numerical tests show that this
closed form enzyme elimination gives a much more accurate description of the
subnetwork dynamics than the simpler method that represents enzymes explicitly,
and is also more efficient computationally.


title: A survey of systems for massive stream analytics

abstract:
  The immense growth of data demands switching from traditional data processing
solutions to systems, which can process a continuous stream of real time data.
Various applications employ stream processing systems to provide solutions to
emerging Big Data problems. Open-source solutions such as Storm, Spark
Streaming, and S4 are the attempts to answer key stream processing questions.
The recent introduction of real time stream processing commercial solutions
such as Amazon Kinesis, IBM Infosphere Stream reflect industry requirements.
The system and application related challenges to handle massive stream of real
time data analytics are an active field of research.
  In this paper, we present a comparative analysis of the existing
state-of-the-art stream processing solutions. We also include various
application domains, which are transforming their business model to benefit
from these large scale stream processing systems.


title: Phonon singularities on volt-ampere curves of niobium point contacts

abstract:
  The volt-ampere curves and their second derivatives were studied for niobium
point contacts at low temperatures in the voltage range corresponding to the
characteristic phonon energies. It was found that while for the dirty contacts
in the normal state no PC spectra of phonons could be detected, in the
superconducting state there were singularities in the I-V curves corresponding
to maxima either in the first or in the second derivatives. The singularities
observed were due to the energy dependence of the excess current. We suppose
that the origin of these singularities is due to the inelastic transitions of
electrons between chemical potentials of Cooper pairs at both sides of the
contact, which differ in energy by $eV$. These transitions are possible if $\xi
\left(0 \right)\gtrsim d \sim{{\Lambda}_{\varepsilon}}$ ($\xi (0)$ being the
coherence length, $d$, the contact diameter,
${{\Lambda}_{\varepsilon}}={{({{l}_{i}}\cdot {{l}_{\varepsilon}})}^{1/2}}$,
where ${{l}_{i}}$ and ${{l}_{\varepsilon}}$ being the elastic and inelastic
electron mean free paths, respectively).


title: Motor control by precisely timed spike patterns

abstract:
  A fundamental problem in neuroscience is to understand how sequences of
action potentials ("spikes") encode information about sensory signals and motor
outputs. Although traditional theories of neural coding assume that information
is conveyed by the total number of spikes fired (spike rate), recent studies of
sensory and motor activity have shown that far more information is carried by
the millisecond-scale timing patterns of action potentials (spike timing).
However, it is unknown whether or how subtle differences in spike timing drive
differences in perception or behavior, leaving it unclear whether the
information carried by spike timing actually plays a causal role in brain
function. Here we demonstrate how a precise spike timing code is read out
downstream by the muscles to control behavior. We provide both correlative and
causal evidence to show that the nervous system uses millisecond-scale
variations in the timing of spikes within multi-spike patterns to regulate a
relatively simple behavior - respiration in the Bengalese finch, a songbird.
These findings suggest that a fundamental assumption of current theories of
motor coding requires revision, and that significant improvements in
applications, such as neural prosthetic devices, can be achieved by using
precise spike timing information.