title:
The topological susceptibility in finite temperature QCD and axion
  cosmology

abstract:
  We study the topological susceptibility in 2+1 flavor QCD above the chiral
crossover transition temperature using Highly Improved Staggered Quark action
and several lattice spacings, corresponding to temporal extent of the lattice,
$N_\tau=6,8,10$ and $12$. We observe very distinct temperature dependences of
the topological susceptibility in the ranges above and below $250$ MeV. While
for temperatures above $250$ MeV, the dependence is found to be consistent with
dilute instanton gas approximation, at lower temperatures the fall-off of
topological susceptibility is milder. We discuss the consequence of our results
for cosmology wherein we estimate the bounds on the axion decay constant and
the oscillation temperature if indeed the QCD axion is a possible dark matter
candidate.


title:
Low-temperature-compatible tunneling-current-assisted scanning microwave
  microscope utilizing a rigid coaxial resonator

abstract:
  We present a design for a tunneling-current-assisted scanning near-field
microwave microscope. For stable operation at cryogenic temperatures, making a
small and rigid microwave probe is important. Our coaxial resonator probe has a
length of approxomately 30 mm and can fit inside the 2-inch bore of a
superconducting magnet. The probe design includes an insulating joint, which
separates DC and microwave signals without degrading the quality factor. By
applying the SMM to the imaging of an electrically inhomogeneous
superconductor, we obtain the spatial distribution of the microwave response
with a spatial resolution of approximately 200 nm. Furthermore, we present an
analysis of our SMM probe based on a simple lumped-element circuit model along
with the near-field microwave measurements of silicon wafers having different
conductivities.


title:
High-Speed Magnetoresistive Random-Access Memory Random Number Generator
  Using Error-Correcting Code

abstract:
  A high-speed random number generator (RNG) circuit based on magnetoresistive
random-access memory (MRAM) using an error-correcting code (ECC) post
processing circuit is presented. ECC post processing increases the quality of
randomness by increasing the entropy of random number. { We experimentally show
that a small error-correcting capability circuit is sufficient for this post
processing. It is shown that the ECC post processing circuit powerfully
improves the quality of randomness with minimum overhead, ending up with
high-speed random number generation. We also show that coupling with a linear
feedback shift resistor is effective for improving randomness


title:
Injection to rapid diffusive shock acceleration at perpendicular shocks
  in partially ionized plasmas

abstract:
  We present a three-dimensional hybrid simulation of a collisionless
perpendicular shock in a partially ionized plasma for the first time. In this
simulation, the shock velocity and the upstream ionization fraction are Vsh ~
1333 km/s and fi ~ 0.5, that are typical values for isolated young supernova
remnants in the interstellar medium. We confirm previous two-dimensional
simulation results that downstream hydrogen atoms leak into the upstream
region, they are accelerated by the pickup process in the upstream region, and
large magnetic field fluctuations are generated both in the upstream and
downstream regions. In addition, we find that the magnetic field fluctuations
have three-dimensional structures and the leaking hydrogen atoms are injected
to the diffusive shock acceleration at the perpendicular shock after the pickup
process. The observed diffusive shock acceleration can be interpreted as the
shock drift acceleration with scattering. Particles are accelerated to v ~ 100
Vsh ~ 0.3c within ~ 100 gyroperiods in this simulation. The acceleration time
scale is faster than that of the diffusive shock acceleration in parallel
shocks. Our simulation results suggest that supernova remnants can accelerate
cosmic rays to 10^{15.5} eV (the knee) during the Sedov phase.


title:
Theoretical estimate on tensor-polarization asymmetry in proton-deuteron
  Drell-Yan process

abstract:
  Tensor-polarized parton distribution functions are new quantities in spin-one
hadrons such as the deuteron, and they could probe new quark-gluon dynamics in
hadron and nuclear physics. In charged-lepton deep inelastic scattering (DIS),
they are studied by the twist-two structure functions $b_1$ and $b_2$. The
HERMES collaboration found unexpectedly large $b_1$ values than a naive
theoretical expectation based on the standard deuteron model. The situation
should be significantly improved in the near future by an approved experiment
to measure $b_1$ at JLab (Thomas Jefferson National Accelerator Facility).
There is also an interesting indication in the HERMES result that finite
antiquark tensor polarization exists. It could play an important role in
solving a mechanism on tensor structure in the quark-gluon level. The
tensor-polarized antiquark distributions are not easily determined from the
charged-lepton DIS; however, they can be measured in a proton-deuteron
Drell-Yan process with a tensor-polarized deuteron target. In this article, we
estimate the tensor-polarization asymmetry for a possible Fermilab
Main-Injector experiment by using optimum tensor-polarized PDFs to explain the
HERMES measurement. We find that the asymmetry is typically a few percent. If
it is measured, it could probe new hadron physics, and such studies could
create an interesting field of high-energy spin physics. In addition, we find
that a significant tensor-polarized gluon distribution should exist due to
$Q^2$ evolution, even if it were zero at a low $Q^2$ scale. The
tensor-polarized gluon distribution has never been observed, so that it is an
interesting future project.


title:
Performance Analysis of ZF Receivers with Imperfect CSI for Uplink
  Massive MIMO Systems

abstract:
  We consider the uplink of massive multipleinput multiple-output systems in a
multicell environment. Since the base station (BS) estimates the channel state
information (CSI) using the pilot signals transmitted from the users, each BS
will have imperfect CSI in practice. Assuming zero-forcing method to eliminate
the multi-user interference, we derive the exact analytical expressions for the
probability density function (PDF) of the signal-to-interference-plus-noise
ratio (SINR), the corresponding achievable rate, the outage probability, and
the symbol error rate (SER) when the BS has imperfect CSI. An upper bound of
the SER is also derived for an arbitrary number of antennas at the BS.
Moreover, we derive the upper bound of the achievable rate for the case where
the number of antennas at the BS goes to infinity, and the analysis is verified
by presenting numerical results.


title: Onion-peeling inversion of stellarator images

abstract:
  An onion-peeling technique is developed for inferring the emissivity profile
of a stellarator plasma from a two-dimensional image acquired through a CCD or
CMOS camera. Each pixel in the image is treated as an integral of emission
along a particular line-of-sight. Additionally, the flux surfaces in the plasma
are partitioned into discrete layers, each of which is assumed to have uniform
emissivity. If the topology of the flux surfaces is known, this construction
permits the development of a system of linear equations that can be solved for
the emissivity of each layer. We present initial results of this method applied
to wide-angle visible images of the CNT stellarator plasma.


title: Policy Networks with Two-Stage Training for Dialogue Systems

abstract:
  In this paper, we propose to use deep policy networks which are trained with
an advantage actor-critic method for statistically optimised dialogue systems.
First, we show that, on summary state and action spaces, deep Reinforcement
Learning (RL) outperforms Gaussian Processes methods. Summary state and action
spaces lead to good performance but require pre-engineering effort, RL
knowledge, and domain expertise. In order to remove the need to define such
summary spaces, we show that deep RL can also be trained efficiently on the
original state and action spaces. Dialogue systems based on partially
observable Markov decision processes are known to require many dialogues to
train, which makes them unappealing for practical deployment. We show that a
deep RL method based on an actor-critic architecture can exploit a small amount
of data very efficiently. Indeed, with only a few hundred dialogues collected
with a handcrafted policy, the actor-critic deep learner is considerably
bootstrapped from a combination of supervised and batch RL. In addition,
convergence to an optimal policy is significantly sped up compared to other
deep RL methods initialized on the data with batch RL. All experiments are
performed on a restaurant domain derived from the Dialogue State Tracking
Challenge 2 (DSTC2) dataset.


title:
Unsupervised Learning of Word-Sequence Representations from Scratch via
  Convolutional Tensor Decomposition

abstract:
  Unsupervised text embeddings extraction is crucial for text understanding in
machine learning. Word2Vec and its variants have received substantial success
in mapping words with similar syntactic or semantic meaning to vectors close to
each other. However, extracting context-aware word-sequence embedding remains a
challenging task. Training over large corpus is difficult as labels are
difficult to get. More importantly, it is challenging for pre-trained models to
obtain word-sequence embeddings that are universally good for all downstream
tasks or for any new datasets. We propose a two-phased ConvDic+DeconvDec
framework to solve the problem by combining a word-sequence dictionary learning
model with a word-sequence embedding decode model. We propose a convolutional
tensor decomposition mechanism to learn good word-sequence phrase dictionary in
the learning phase. It is proved to be more accurate and much more efficient
than the popular alternating minimization method. In the decode phase, we
introduce a deconvolution framework that is immune to the problem of varying
sentence lengths. The word-sequence embeddings we extracted using
ConvDic+DeconvDec are universally good for a few downstream tasks we test on.
The framework requires neither pre-training nor prior/outside information.


title: Alice-Bob Physics: Coherent Solutions of Nonlocal KdV Systems

abstract:
  In natural and social science, many events happened at different space-times
may be closely correlated. Two events, $A$ (Alice) and $B$ (Bob) are defined
correlated if one event is determined by another, say, $B=\hat{f}A$ for
suitable $\hat{f}$ operators. Taking KdV and coupled KdV systems as examples,
we can find some types of models (AB-KdV systems) to exhibit the existence on
the correlated solutions linked with two events. The idea of this report is
valid not only for physical problems related to KdV systems but also for
problems described by arbitrary continuous or discrete models. The parity and
time reversal symmetries are extended to shifted parity and delayed time
reversal. The new symmetries are found to be useful not only to establish
AB-systems but also to find group invariant solutions of numerous AB-systems. A
new elegant form of the $N$-soliton solutions of the KdV equation and then the
AB-KdV systems is obtained. A concrete AB-KdV system derived from the nonlinear
inviscid dissipative and barotropic vorticity equation in a $\beta$-plane
channel is applied to the two correlated monople blocking events which is
responsible for the snow disaster in the winter of 2007/2008 happened in
Southern China.

categories: nlin.SI math-ph math.MP physics.class-ph


title: Raghavan Narsimhan's proof of L. Schwartz's perturbation theorem

abstract:
  Raghavan Narasimhan outlined a new proof of L. Schwartz's perturbation
theorem during a course of lectures at IMSc, Chennai in Spring 2007. The
details are given.


title: On the uniqueness of injective III$_1$ factor

abstract:
  We give a new proof of a theorem due to Alain Connes, that an injective
factor $N$ of type III$_1$ with separable predual and with trivial
bicentralizer is isomorphic to the Araki--Woods type III$_1$ factor
$R_{\infty}$. This, combined with the author's solution to the bicentralizer
problem for injective III$_1$ factors provides a new proof of the theorem that
up to $*$-isomorphism, there exists a unique injective factor of type III$_1$
on a separable Hilbert space.


title:
Resolving the VO$_2$ controversy: Mott mechanism dominates the
  insulator-to-metal transition

abstract:
  We consider a minimal model to investigate the metal-insulator transition in
VO$_2$. We adopt a Hubbard model with two orbital per unit cell, which captures
the competition between Mott and singlet-dimer localization. We solve the model
within Dynamical Mean Field Theory, characterizing in detail the
metal-insulator transition and finding new features in the electronic states.
We compare our results with available experimental data obtaining good
agreement in the relevant model parameter range. Crucially, we can account for
puzzling optical conductivity data obtained within the hysteresis region, which
we associate to a novel metallic state characterized by a split heavy
quasiparticle band. Our results show that the thermal-driven insulator-to-metal
transition in VO$_2$ is compatible with a Mott electronic mechanism, providing
fresh insight to a long standing "chicken-and-egg" debate and calling for
further research of "Mottronics" applications of this system.


title: Quark-Meson Coupling model based upon the Nambu-Jona Lasinio model

abstract:
  The NJL model for the octet baryons, using proper time regularization to
simulate some of the features of confinement, is solved self-consistently in
nuclear matter. This provides an alternative framework to the MIT bag model
which has been used in the quark-meson coupling model. After fitting the
parameters of the model to the saturation properties of symmetric nuclear
matter the model is used to explore the equation of state of pure neutron
matter as well as nuclear matter at densities relevant to heavy ion collisions.
With a view to future studies of high mass neutron stars, the binding of
hyperons is also explored.


title: Self-inversive polynomials, curves, and codes

abstract:
  We study connections between self-inversive and self-reciprocal polynomials,
reduction theory of binary forms, minimal models of curves, and formally
self-dual codes. We prove that if $\mathcal X$ is a superelliptic curve defined
over $\mathbb C$ and its reduced automorphism group is nontrivial or not
isomorphic to a cyclic group, then we can write its equation as $y^n = f(x)$ or
$y^n = x f(x)$, where $f(x)$ is a self-inversive or self-reciprocal polynomial.
Moreover, we state a conjecture on the coefficients of the zeta polynomial of
extremal formally self-dual codes.


title: On the field of moduli of superelliptic curves

abstract:
  A superelliptic curve $\X$ of genus $g\geq 2$ is not necessarily defined over
its field of moduli but it can be defined over a quadratic extension of it.
While a lot of work has been done by many authors to determine which
hyperelliptic curves are defined over their field of moduli, less is known for
superelliptic curves. In this paper we observe that if the reduced group of a
genus $g\geq 2$ superelliptic curve $\X$ is different from the trivial or
cyclic group, then $\X$ can be defined over its field of moduli; in the cyclic
situation we provide a sufficient condition for this to happen. We also
determine those families of superelliptic curves of genus at most $10$ which
might not be definable over their field of moduli.


title: Bounds on Lifting Continuous Markov Chains to Speed Up Mixing

abstract:
  It is often possible to speed up the mixing of a Markov chain $\{ X_{t} \}_{t
\in \mathbb{N}}$ on a state space $\Omega$ by \textit{lifting}, that is,
running a more efficient Markov chain $\{ \hat{X}_{t} \}_{t \in \mathbb{N}}$ on
a larger state space $\hat{\Omega} \supset \Omega$ that projects to $\{ X_{t}
\}_{t \in \mathbb{N}}$ in a certain sense. In [CLP99], Chen, Lov{\'a}sz and Pak
prove that for Markov chains on finite state spaces, the mixing time of any
lift of a Markov chain is at least the square root of the mixing time of the
original chain, up to a factor that depends on the stationary measure.
Unfortunately, this extra factor makes the bound in [CLP99] very loose for
Markov chains on large state spaces and useless for Markov chains on continuous
state spaces. In this paper, we develop an extension of the evolving set method
that allows us to refine this extra factor and find bounds for Markov chains on
continuous state spaces that are analogous to the bounds in [CLP99]. These
bounds also allow us to improve on the bounds in [CLP99] for some chains on
finite state spaces.


title:
Unified Band Theoretic Description of Electronic and Magnetic Properties
  of Vanadium Dioxide Phases

abstract:
  The debate about whether the insulating phases of vanadium dioxide (VO2) can
be described by band theory or must be described by a theory of strong electron
correlations remains unresolved even after decades of research. Energy-band
calculations using hybrid exchange functionals or including self-energy
corrections account for the insulating or metallic nature of different phases,
but have not yet successfully accounted for the observed magnetic orderings.
Strongly-correlated theories have had limited quantitative success. Here we
report that, by using hard pseudopotentials and an optimized hybrid exchange
functional, the energy gaps and magnetic orderings of both monoclinic VO2
phases and the metallic nature of the high-temperature rutile phase are
consistent with available experimental data, obviating an explicit role for
strong correlations. We also report a potential candidate for the newly-found
metallic monoclinic phase and present a detailed magnetic structure of the M2
monoclinic phase.


title: Surface code fidelity at finite temperatures

abstract:
  We study the dependence of the fidelity of the surface code in the presence
of a single finite-temperature massless bosonic environment after a quantum
error correction cycle. The three standard types of environment are considered:
super-Ohmic, Ohmic, and sub-Ohmic. Our results show that, for regimes relevant
to current experiments, quantum error correction works well even in the
presence of environment-induced, long-range inter-qubit interactions. A
threshold always exists at finite temperatures, although its temperature
dependence is very sensitive to the type of environment. For the super-Ohmic
case, the critical coupling constant separating high- from low-fidelity
decreases with increasing temperature. For both Ohmic and super-Ohmic cases,
the dependence of the critical coupling on temperature is weak. In all cases,
the critical coupling is determined by microscopic parameters of the
environment. For the sub-Ohmic case, it also depends strongly on the duration
of the QEC cycle.


title:
D* polarization as a probe to discriminate new physics in B --> D* tau
  nubar

abstract:
  The confirmation of excess in $R_{D^*}$ at the LHCb is an indication of
lepton flavor non-universality. Various different new physics operators and
their coupling strengths, which provide a good fit to $R_D$, $R_{D^*}$ and
$q^2$ spectra, were identfied previously. In this work, we try to find angular
observables in $\bar{B} \to D^* \tau \bar{\nu}$ which enable us to distinguish
between these new physics operators. We find that the $D^*$ polarization
fraction $f_L(q^2)$ is a good discriminant of scalar and tensor new physics
operators. The change in $\langle f_L(q^2) \rangle$, induced by scalar and
tensor operators, is about three times larger than the expected uncertainty in
the upcoming Belle measurement.


title:
Improvement of thermo-mechanical position stability of the beam position
  monitor in PLS-II

abstract:
  In the storage ring of PLS-II, we reduced mechanical displacement of electron
beam position monitors (e-BPMs) that is caused by heating during e-beam
storage. The orbit feedback system intends that the electron beam pass through
the center of the BPM, so to provide stable photon beam into beamlines the BPM
pickup itself must be stable to sub-micrometer precision. Thermal deformation
of the vacuum chambers on which the BPM pickups are mounted is inevitable when
the electron beam current is changed by unintended beam abort. We reduced this
deformation by improving the vacuum chamber support and by enhancing the water
cooling. We report the thermo-mechanical analysis and displacement measurements
of BPM pickups after the improvements.


title: A threshold-force model for adhesion and mode I fracture

abstract:
  We study the relation between a threshold-force based model at the
microscopic scale and mode I fracture at the macroscopic scale in a system of
discrete interacting springs. Specifically, we idealize the contact between two
surfaces as that between a rigid surface and a collection of springs with
long-range interaction and a constant tensile threshold force. We show that a
particular scaling similar to that of crack-tip stress in Linear Elastic
Fracture Mechanics leads to a macroscopic limit behavior. The model also
reproduces the scaling behaviors of the JKR model of adhesive contact. We
determine how the threshold force depends on the fracture energy and elastic
properties of the material. The model can be used to study rough-surface
adhesion.


title:
Solutions of random-phase approximation equation for
  positive-semidefinite stability matrix

abstract:
  It is mathematically proven that, if the stability matrix $\mathsf{S}$ is
positive-semidefinite, solutions of the random-phase approximation (RPA)
equation are all physical or belong to Nambu-Goldstone (NG) modes, and the
NG-mode solutions may form Jordan blocks of $\mathsf{N\,S}$ ($\mathsf{N}$ is
the norm matrix) but their dimension is not more than two. This guarantees that
the NG modes in the RPA can be separated out via canonically conjugate
variables.


title:
Finding Low-Rank Solutions via Non-Convex Matrix Factorization,
  Efficiently and Provably

abstract:
  A rank-$r$ matrix $X \in \mathbb{R}^{m \times n}$ can be written as a product
$U V^\top$, where $U \in \mathbb{R}^{m \times r}$ and $V \in \mathbb{R}^{n
\times r}$. One could exploit this observation in optimization: e.g., consider
the minimization of a convex function $f(X)$ over rank-$r$ matrices, where the
set of rank-$r$ matrices is modeled via the factorization $UV^\top$. Though
such parameterization reduces the number of variables, and is more
computationally efficient (of particular interest is the case $r \ll \min\{m,
n\}$), it comes at a cost: $f(UV^\top)$ becomes a non-convex function w.r.t.
$U$ and $V$.
  We study such parameterization for optimization of generic convex objectives
$f$, and focus on first-order, gradient descent algorithmic solutions. We
propose the Bi-Factored Gradient Descent (BFGD) algorithm, an efficient
first-order method that operates on the $U, V$ factors. We show that when $f$
is (restricted) smooth, BFGD has local sublinear convergence, and linear
convergence when $f$ is both (restricted) smooth and (restricted) strongly
convex. For several key applications, we provide simple and efficient
initialization schemes that provide approximate solutions good enough for the
above convergence results to hold.


title: Can realistic interaction be useful for nuclear mean-field approaches?

abstract:
  Recent applications of the M3Y-type semi-realistic interaction to the nuclear
mean-field approaches are presented: (i) Prediction of magic numbers and (ii)
isotope shifts of nuclei with magic proton numbers. The results exemplify that
realistic interaction, which is derived from the base $2N$ and $3N$
interaction, furnish a new theoretical instrument for advancing nuclear
mean-field approaches.


title:
Octahedral rotation patterns in strained EuFeO3 and other Pbnm
  perovskite films: Implications for hybrid improper ferroelectricity

abstract:
  We report the relationship between epitaxial strain and the crystallographic
orientation of the in-phase rotation axis and A-site displacements in Pbnm-type
perovskite films. Synchrotron diffraction measurements of EuFeO3 films under
strain states ranging from 2% compressive to 0.9% tensile on cubic or
rhombohedral substrates exhibit a combination of a-a+c- and a+a-c- rotational
patterns. We compare the EuFeO3 behavior with previously reported experimental
and theoretical work on strained Pbnm-type films on non-orthorhombic
substrates, as well as additional measurements from LaGaO3, LaFeO3, and
Eu0.7Sr0.3MnO3 films on SrTiO3. Compiling the results from various material
systems reveals a general strain dependence in which compressive strain
strongly favors a-a+c- and a+a-c- rotation patterns and tensile strain weakly
favors a-a-c+ structures. In contrast, EuFeO3 films grown on Pbnm-type GdScO3
under 2.3% tensile strain take on a uniform a-a+c- rotation pattern imprinted
from the substrate, despite strain energy considerations that favor the a-a-c+
pattern. These results point to the use of substrate imprinting as a more
robust route than strain for tuning the crystallographic orientations of the
octahedral rotations and A-site displacements needed to realize
rotation-induced hybrid improper ferroelectricity in oxide heterostructures.


title:
The adaptive Crouzeix-Raviart element method for convection-diffusion
  eigenvalue problems

abstract:
  The convection-diffusion eigenvalue problems are hot topics, and
computational mathematics community and physics community are concerned about
them in recent years. In this paper, we consider the a posteriori error
analysis and the adaptive algorithm of the Crouzeix-Raviart nonconforming
element method for the convection-diffusion eigenvalue problems. We give the
corresponding a posteriori error estimators, and prove their reliability and
efficiency. Finally, the numerical results validate the theoretical analysis
and show that the algorithm presented in this paper is efficient.


title:
Congruences between Heegner points and quadratic twists of elliptic
  curves

abstract:
  We establish a congruence formula between $p$-adic logarithms of Heegner
points for two elliptic curves with the same mod $p$ Galois representation. As
a first application, we use the congruence formula when $p=2$ to explicitly
construct many quadratic twists of analytic rank zero (resp. one) for a wide
class of elliptic curves $E$. We show that the number of twists of $E$ up to
twisting discriminant $X$ of analytic rank zero (resp. one) is $\gg
X/\log^{5/6}X$, improving the current best general bound towards Goldfeld's
conjecture due to Ono--Skinner (resp. Perelli--Pomykala). We also prove the
2-part of the Birch and Swinnerton-Dyer conjecture for many rank zero and rank
one twists of $E$, which was only recently established for specific CM elliptic
curves $E$.


title:
Collision tomography: Physical properties of possible progenitors of the
  Andromeda stellar stream

abstract:
  To unveil a progenitor of the Andromeda Giant Stellar Stream, we investigate
the interaction between an accreting satellite galaxy and the Andromeda Galaxy
using an $N$-body simulation. A comprehensive parameter study with 247 models
is performed by varying size and mass distribution of the progenitor dwarf
galaxy. We show that the binding energy of the progenitor is the crucial
parameter in reproducing the Andromeda Giant Stellar Stream and the shell-like
structures surrounding the Andromeda Galaxy. As a result of the simulations,
the progenitor must satisfy a simple scaling relation between the core radius,
the total mass and the tidal radius. Using this relation, we successfully
constrain the physical properties of the progenitors to have mass ranging from
$5\times10^8 M_\odot$ to $5\times10^9 M_\odot$ and central surface density
around $10^3\, M_\odot\, \mathrm{pc}^{-2}$. A detailed comparison between our
result and the nearby observed galaxies indicates that possible progenitors of
the Andromeda Giant Stellar Stream include a dwarf elliptical galaxy, a dwarf
irregular galaxy, and a small spiral galaxy.


title:
Constrained optimal rearrangement problem leading to a new type obstacle
  problem

abstract:
  We consider a new type of obstacle problem in the cylindrical domain
$\Omega=D\times (0,1)$ arising from minimization of the functional $$
\int_\Omega \frac{1}{2}|\nabla u|^2+\chi_{\{v>0\}}udx, $$ where $v(x')=\int_0^1
u(x', t) dt $. We prove several existence and regularity results and show that
the comparison principle does not hold for minimizers.
  This problem is derived from a classical optimal rearrangement problem in a
cylindrical domain, under the constraint that the force function does not
depend on the $x_n$ variable of the cylindrical axis.
  A mistake in the Theorem 4.2 of the previous version has been found. The
statement remains an open problem.


title: Degrees of Freedom of Cache-Aided Wireless Interference Networks

abstract:
  We study the role of caches in wireless interference networks. We focus on
content caching and delivery across a Gaussian interference network, where both
transmitters and receivers are equipped with caches. We provide a
constant-factor approximation of the system's degrees of freedom (DoF), for
arbitrary number of transmitters, number of receivers, content library size,
receiver cache size, and transmitter cache size (as long as the transmitters
combined can store the entire content library among them). We demonstrate
approximate optimality with respect to information-theoretic bounds that do not
impose any restrictions on the caching and delivery strategies. Our
characterization reveals three key insights. First, the approximate DoF is
achieved using a strategy that separates the physical and network layers. This
separation architecture is thus approximately optimal. Second, we show that
increasing transmitter cache memory beyond what is needed to exactly store the
entire library between all transmitters does not provide more than a
constant-factor benefit to the DoF. A consequence is that transmit zero-forcing
is not needed for approximate optimality. Third, we derive an interesting
trade-off between the receiver memory and the number of transmitters needed for
approximately maximal performance. In particular, if each receiver can store a
constant fraction of the content library, then only a constant number of
transmitters are needed. Our solution to the caching problem requires
formulating and solving a new communication problem, the symmetric multiple
multicast X-channel, for which we provide an exact DoF characterization.


title:
Systematic analysis of structural and magnetic properties of spinel
  $CoB_2O_4$(B=Cr,Mn and Fe)compounds from their electronic structures

abstract:
  The structural and magnetic properties of spinel compounds $CoB_2O_4$
(B=Cr,Mn and Fe) are studied using the DFT+U method and generalized gradient
approximation (GGA). We concentrate on understanding the trends in the
properties of these materials as the B cation changes, in terms of relative
strengths of crystal fields and exchange fields through an analysis of their
electronic densities of states. We find that the electron-electron correlation
plays a significant role in obtaining the correct structural and electronic
ground states. Significant structural distortion in CoMn$_{2}$O$_{4}$ and
"inverted" sublattice occupancy in CoFe$_{2}$O$_{4}$ affects the magnetic
exchange interactions substantially. The trends in the magnetic exchange
interactions are analysed in terms of the structural parameters and the
features in their electronic structures. We find that the Fe states in
CoFe$_{2}$O$_{4}$ are extremely localised, irrespective of the symmetry of the
site, which makes it very different from the features of the states of the B
cations in other two compounds. These results provide useful insights into the
trends in the properties of CoB$_{2}$O$_{4}$ compounds with variation of B
cation which would help in understanding the results of recent experiments on
doping of Mn and Cr in multiferroic CoCr$_{2}$O$_{4}$.


title: Information thermodynamics for a multi-feedback process with time delay

abstract:
  We investigate a measurement-feedback process of repeated operations with
time delay. During a finite-time interval, measurement on the system is
performed and the feedback protocol derived from the measurement outcome is
applied with time delay. This protocol is maintained into the next interval
until a new protocol from the next measurement is applied. Unlike a feedback
process without delay, both memories associated with previous and present
measurement outcomes are involved in the system dynamics, which naturally
brings forth a joint system described by a system state and two memory states.
The thermodynamic second law provides a lower bound for heat flow into a
thermal reservoir by the (3-state) Shannon entropy change of the joint system.
However, as the feedback protocol depends on memory states sequentially, we can
deduce a tighter bound for heat flow by integrating out irrelevant memory
states during dynamics. As a simple example, we consider the so-called cold
damping feedback process where the velocity of a particle is measured and a
dissipative feedback protocol is applied to decelerate the particle. We confirm
that the heat flow is well above the tightest bound. We also examine the
long-time limit of this feedback process, which turns out to exhibit an
interesting instability transition as well as heating by controlling parameters
such as measurement errors, time interval, protocol strength, and time delay
length. We discuss the underlying mechanism for instability and heating, which
might be unavoidable in reality.


title: One dimensional PIC simulation of relativistic Buneman instability

abstract:
  Spatio-temporal evolution of the relativistic Buneman instability has been
investigated in one dimension using an in-house developed particle-in-cell
simulation code. Starting from the excitation of the instability, its evolution
has been followed numerically till its quenching and beyond. As compared to the
well understood non-relativistic case, it is found that the maximum growth rate
($\gamma_{max}$) reduces due to relativistic effects and varies with
$\gamma_{e0}$ and m/M as $\gamma_{max} \sim
\frac{\sqrt{3}}{2\sqrt{\gamma_{e0}}}\biglb(\frac{m}{2M}\bigrb)^{1/3}$, where
$\gamma_{e0}$ is Lorentz factor associated with the initial electron drift
velocity ($v_{0}$) and (m/M) is the electron to ion mass ratio. Further it is
observed that in contrast to the non-relativistic results[Hirose,Plasma Phys.
20, 481(1978)] at the saturation point, ratio of electrostatic field energy
density ($\sum\limits_{k} |E_{k}|^{2}/8\pi$) to initial drift kinetic energy
density ($W_{0}$) scales with $\gamma_{e0}$ as $\sim 1/\gamma^{2}_{e0}$. These
simulation results are found to be in good agreement with that derived using
fluid theory.


title:
Understanding the internal structures of the $X(4140)$, $X(4274)$,
  $X(4500)$ and $X(4700)$

abstract:
  We investigate the newly observed $X(4500)$ and $X(4700)$ based on the
diquark-antidiquark configuration within the framework of QCD sum rules. Both
of them may be interpreted as the $D$-wave $cs\bar{c}\bar{s}$ tetraquark states
of $J^P = 0^+$, but with opposite color structures, which is remarkably similar
to the result obtained in Ref.~\cite{Chen:2010ze} that the $X(4140)$ and
$X(4274)$ can be both interpreted as the $S$-wave $cs\bar{c}\bar{s}$ tetraquark
states of $J^P = 1^+$, also with opposite color structures. However, the
extracted masses and these suggested assignments to these $X$ states do depend
on these running quark masses where $m_s (2 \mbox{ GeV}) = 95 \pm 5$ MeV and
$m_c (m_c) = 1.23 \pm 0.09$ GeV. As a byproduct, the masses of the
hidden-bottom partner states of the $X(4500)$ and $X(4700)$ are extracted to be
both around 10.64 GeV, which can be searched for in the $\Upsilon \phi$
invariant mass distribution.


title: Calculi for Intuitionistic Normal Modal Logic

abstract:
  This paper provides a call-by-name and a call-by-value term calculus, both of
which have a Curry-Howard correspondence to the box fragment of the
intuitionistic modal logic IK. The strong normalizability and the confluency of
the calculi are shown. Moreover, we define a CPS transformation from the
call-by-value calculus to the call-by-name calculus, and show its soundness and
completeness.


title: Alternative framework for quantifying coherence

abstract:
  We propose an alternative framework for quantifying coherence. The framework
is based on a natural property of coherence, the additivity of coherence for
subspace-independent states, which is described by an operation-independent
equality rather than operation-dependent inequalities and therefore applicable
to various physical contexts. Our framework is compatible with all the known
results on coherence measures but much more flexible and convenient for
applications, and by using it many open questions can be resolved.


title:
Cyber Attack Thread: A Control-flow Based Approach to Deconstruct and
  Mitigate Cyber Threats

abstract:
  Attacks in cyberspace have got attention due to risk at privacy, breach of
trust and financial losses for individuals as well as organizations. In recent
years, these attacks have become more complex to analyze technically, as well
as to detect and prevent from accessing confidential data. Although there are
many methodologies and mechanisms which have been suggested for cyber-attack
detection and prevention, but not from the perspective of an attacker. This
paper presents the cyber-defence as hindrances, faced by the attacker, by
understanding attack thread and defence possibilities with existing security
mechanisms. Seven phases of Cyber Attack Thread are introduced and technical
aspects are discussed with reference to APT attacks. The paper aims for
security practitioner and administrators as well as for the general audience to
understand the attack scenario and defensive security measures.


title: Yokohama to Ruby Valley : Around the World in 80 Years. II

abstract:
  We two had year-long research leaves in Japan, working together fulltime with
several Japanese plus Tony De Groot back in Livermore and Harald Posch in
Vienna. We summarize a few of the high spots from that very productive year (
1989-1990 ), followed by an additional fifteen years' work in Livermore, with
extensive travel. Next came our retirement in Nevada in 2005, which has turned
out to be a long-term working vacation. Carol narrates this part of our history
together.


title: Technical Aspects of Cyber Kill Chain

abstract:
  Recent trends in targeted cyber-attacks has increased the interest of
research in the field of cyber security. Such attacks have massive disruptive
effects on rganizations, enterprises and governments. Cyber kill chain is a
model to describe cyber-attacks so as to develop incident response and analysis
capabilities. Cyber kill chain in simple terms is an attack chain, the path
that an intruder takes to penetrate information systems over time to execute an
attack on the target. This paper broadly categories the methodologies,
techniques and tools involved in cyber-attacks. This paper intends to help a
cyber security researcher to realize the options available to an attacker at
every stage of a cyber-attack.


title: Approximation algorithms for the vertex happiness

abstract:
  We investigate the maximum happy vertices (MHV) problem and its complement,
the minimum unhappy vertices (MUHV) problem. We first show that the MHV and
MUHV problems are a special case of the supermodular and submodular
multi-labeling (Sup-ML and Sub-ML) problems, respectively, by re-writing the
objective functions as set functions. The convex relaxation on the Lov\'{a}sz
extension, originally presented for the submodular multi-partitioning (Sub-MP)
problem, can be extended for the Sub-ML problem, thereby proving that the
Sub-ML (Sup-ML, respectively) can be approximated within a factor of $2 -
\frac{2}{k}$ ($\frac{2}{k}$, respectively). These general results imply that
the MHV and the MUHV problems can also be approximated within $\frac{2}{k}$ and
$2 - \frac{2}{k}$, respectively, using the same approximation algorithms. For
MHV, this $\frac{2}{k}$-approximation algorithm improves the previous best
approximation ratio $\max \{\frac{1}{k}, \frac{1}{\Delta + 1}\}$, where
$\Delta$ is the maximum vertex degree of the input graph. We also show that an
existing LP relaxation is the same as the concave relaxation on the Lov\'{a}sz
extension for the Sup-ML problem; we then prove an upper bound of $\frac{2}{k}$
on the integrality gap of the LP relaxation. These suggest that the
$\frac{2}{k}$-approximation algorithm is the best possible based on the LP
relaxation. For MUHV, we formulate a novel LP relaxation and prove that it is
the same as the convex relaxation on the Lov\'{a}sz extension for the Sub-ML
problem; we then show a lower bound of $2 - \frac{2}{k}$ on the integrality gap
of the LP relaxation. Similarly, these suggest that the $(2 -
\frac{2}{k})$-approximation algorithm is the best possible based on the LP
relaxation. Lastly, we prove that this $(2 - \frac{2}{k})$-approximation is
optimal for the MUHV problem, assuming the Unique Games Conjecture.


title:
Projecting the distribution of planar Browian motion at a stopping time
  through an analytic function

abstract:
  A method is given of deriving the distribution of planar Brownian motion
evaluated at certain stopping times using analytic functions. This method
relies upon a generalization of the standard conformal invariance of harmonic
measure. A number of examples are given, including several in which the
stopping time in question is not the exit time of a domain. It is also shown
how appropriate choices of domains and stopping times can lead to new proofs of
identities, including Euler's Basel sum and a generalization of Leibniz's
formula for $\pi$.


title: Biharmonic hypersurfaces with constant scalar curvature in space forms

abstract:
  Let $M^n$ be a biharmonic hypersurface with constant scalar curvature in a
space form $\mathbb M^{n+1}(c)$. We show that $M^n$ has constant mean curvature
if $c>0$ and $M^n$ is minimal if $c\leq0$, provided that the number of distinct
principal curvatures is no more than 6. This partially confirms Chen's
conjecture and Generalized Chen's conjecture. As a consequence, we prove that
there exist no proper biharmonic hypersurfaces with constant scalar curvature
in Euclidean space $\mathbb E^{n+1}$ or hyperbolic space $\mathbb H^{n+1}$ for
$n<7$.


title:
A simulation study on image reconstruction in magnetic particle imaging
  with field-free-line encoding

abstract:
  The purpose of this study was to present image reconstruction methods for
magnetic particle imaging (MPI) with a field-free-line (FFL) encoding scheme
and to propose the use of the maximum likelihood-expectation maximization
(ML-EM) algorithm for improving the image quality of MPI. The feasibility of
these methods was investigated by computer simulations, in which the projection
data were generated by summing up the Fourier harmonics obtained from the MPI
signals based on the Langevin function. Images were reconstructed from the
generated projection data using the filtered backprojection (FBP) method and
the ML-EM algorithm. The effects of the gradient of selection magnetic field
(SMF), the strength of drive magnetic field (DMF), the diameter of magnetic
nanoparticles (MNPs), and the number of projection data on the image quality of
the reconstructed images were investigated. The spatial resolution of the
reconstructed images became better with increasing gradient of SMF and with
increasing diameter of MNPs up to approximately 30 nm. For the diameter greater
than approximately 30 nm, the spatial resolution was almost constant. It also
became better with decreasing strength of DMF. The image quality was improved
by use of the ML-EM algorithm compared to the FBP method, especially when the
strength of DMF was weak and the number of projection data was small. In
conclusion, we presented image reconstruction methods for MPI with an FFL
encoding scheme and our preliminary results suggest that the ML-EM algorithm
will be useful for improving the image quality of MPI.


title: Bringing Order to the Chaos in the Brickyard

abstract:
  An allegory published in 1963 titled Chaos in the Brickyard spoke to the
decline in the quality of research. In the intervening time greater awareness
of the issues and actions to improve research endeavors have emerged. Still,
problems persist. This paper is intended to clarify some of the challenges,
particularly with respect to quantitative research, then suggest ways to
improve the quality of published research. The paper highlights where feasible
refinements in analytical techniques can be made and provides a guide to
fundamental principles related to data analysis in research.


title:
Pressure sensing using vertically aligned carbon nanotubes on a flexible
  substrate

abstract:
  Sensing technologies have been under research and development for their
varied applications from microelectronics to space exploration. With the end of
Moores law in sight, there is growing demand for shrinking materials and
improving sensitivity and range of sensing of sensors. Carbon nanotubes (CNTs)
offer an excellent combination of small size (in the order of nanometers in two
dimensions and micrometers in the third dimension), varied current conductivity
(from insulating to metallic), flexibility, mechanical strength and feasibility
of mass production. Here we used CNTs to fabricate pressure sensors to sense
static loads of pressure and studied the characteristics of different methods
of building the sensors. We offer an adhesive-absorption technique of
fabrication of pressure sensors that tackles the issue of endurance of the
sensors to repeated operation. We demonstrate a significant change in
resistance of a vertically aligned forest of nanotubes upon application of
static loads. This study will enable building of better pressure sensors for
several applications.


title:
Fuzzy-Klassen Model for Development Disparities Analysis based on Gross
  Regional Domestic Product Sector of a Region

abstract:
  Analysis of regional development imbalances quadrant has a very important
meaning in order to see the extent of achievement of the development of certain
areas as well as the difference. Factors that could be used as a tool to
measure the inequality of development is to look at the average growth and
development contribution of each sector of Gross Regional Domestic Product
(GRDP) based on the analyzed region and the reference region. This study
discusses the development of a model to determine the regional development
imbalances using fuzzy approach system, and the rules of typology Klassen. The
model is then called fuzzy-Klassen. Implications Product Mamdani fuzzy system
is used in the model as an inference engine to generate output after
defuzzyfication process. Application of MATLAB is used as a tool of analysis in
this study. The test a result of Kota Cilegon is shows that there are
significant differences between traditional Klassen typology analyses with the
results of the model developed. Fuzzy model-Klassen shows GRDP sector
inequality Cilegon City is dominated by Quadrant I (K4), where status is the
sector forward and grows exponentially. While the traditional Klassen typology,
half of GRDP sector is dominated by Quadrant IV (K4) with a sector that is
lagging relative status.


title: PSDVec: a Toolbox for Incremental and Scalable Word Embedding

abstract:
  PSDVec is a Python/Perl toolbox that learns word embeddings, i.e. the mapping
of words in a natural language to continuous vectors which encode the
semantic/syntactic regularities between the words. PSDVec implements a word
embedding learning method based on a weighted low-rank positive semidefinite
approximation. To scale up the learning process, we implement a blockwise
online learning algorithm to learn the embeddings incrementally. This strategy
greatly reduces the learning time of word embeddings on a large vocabulary, and
can learn the embeddings of new words without re-learning the whole vocabulary.
On 9 word similarity/analogy benchmark sets and 2 Natural Language Processing
(NLP) tasks, PSDVec produces embeddings that has the best average performance
among popular word embedding tools. PSDVec provides a new option for NLP
practitioners.


title: Stimulated Brillouin scattering in metamaterials

abstract:
  We compute the SBS gain for a metamaterial comprising a cubic lattice of
dielectric spheres suspended in a background dielectric material. Theoretical
methods are presented to calculate the optical, acoustic, and opto-acoustic
parameters that describe the SBS properties of the material at long
wavelengths. Using the electromagnetic and strain energy densities we
accurately characterise the optical and acoustic properties of the
metamaterial. From a combination of energy density methods and perturbation
theory, we recover the appropriate terms of the photoelastic tensor for the
metamaterial. We demonstrate that electrostriction is not necessarily the
dominant mechanism in the enhancement and suppression of the SBS gain
coefficient in a metamaterial, and that other parameters, such as the Brillouin
linewidth, can dominate instead. Examples are presented that exhibit an order
of magnitude enhancement in the SBS gain as well as perfect suppression.


title: Stabilization Theory for Active Multi Port Networks

abstract:
  This paper proposes a theory for designing stable interconnection of linear
active multi-port networks at the ports. Such interconnections can lead to
unstable networks even if the original networks are stable with respect to
bounded port excitations. Hence such a theory is necessary for realising
interconnections of active multiport networks. Stabilization theory of linear
feedback systems using stable coprime factorizations of transfer functions has
been well known. This theory witnessed glorious developments in recent past
culminating into the $H_{\infty}$ approach to design of feedback systems.
However these important developments have seldom been utilized for network
interconnections due to the difficulty of realizing feedback signal flow graph
for multi-port networks with inputs and outputs as port sources and responses.
This paper resolves this problem by developing the stabilization theory
directly in terms of port connection description without formulation in terms
of signal flow graph of the implicit feedback connection. The stable port
interconnection results into an affine parametrized network function in which
the free parameter is itself a stable network function and describes all
stabilizing port compensations of a given network.


title: Nucleon matrix elements using the variational method in lattice QCD

abstract:
  The extraction of hadron matrix elements in lattice QCD using the standard
two- and three-point correlator functions demands careful attention to
systematic uncertainties. One of the most commonly studied sources of
systematic error is contamination from excited states. We apply the variational
method to calculate the axial vector current $g_{A}$, the scalar current
$g_{S}$ and the quark momentum fraction $\left<x\right>$ of the nucleon and we
compare the results to the more commonly used summation and two-exponential fit
methods. The results demonstrate that the variational approach offers a more
efficient and robust method for the determination of nucleon matrix elements.


title: Phase Retrieval via Incremental Truncated Wirtinger Flow

abstract:
  In the phase retrieval problem, an unknown vector is to be recovered given
quadratic measurements. This problem has received considerable attention in
recent times. In this paper, we present an algorithm to solve a nonconvex
formulation of the phase retrieval problem, that we call $\textit{Incremental
Truncated Wirtinger Flow}$. Given random Gaussian sensing vectors, we prove
that it converges linearly to the solution, with an optimal sample complexity.
We also provide stability guarantees of the algorithm under noisy measurements.
Performance and comparisons with existing algorithms are illustrated via
numerical experiments on simulated and real data, with both random and
structured sensing vectors.


title: On $\Pi$-permutable subgroups of finite groups

abstract:
  Let $\sigma =\{\sigma_{i} | i\in I\}$ be some partition of the set of all
primes $\Bbb{P}$ and $\Pi$ a non-empty subset of the set $\sigma$. A set ${\cal
H}$ of subgroups of a finite group $G$ is said to be a \emph{ complete Hall
$\Pi $-set} of $G$ if every member of ${\cal H}$ is a Hall
$\sigma_{i}$-subgroup of $G$ for some $\sigma_{i}\in \Pi$ and ${\cal H}$
contains exact one Hall $\sigma_{i}$-subgroup of $G$ for every $\sigma_{i}\in
\Pi$ such that $\sigma_i\cap \pi(G)\neq\emptyset$. A subgroup $H$ of $G$ is
called \emph{$\Pi$-quasinormal} or \emph{$\Pi$-permutable} in $G$ if $G$
possesses a complete Hall $\Pi$-set
  ${\cal H}=\{H_{1}, \ldots , H_{t} \}$ such that $AH_{i}^{x}=H_{i}^{x}A$ for
any $i$ and all $x\in G$. We study the embedding properties of $H$ under the
hypothesis that $H$ is $\Pi$-permutable in $G$. Some known results are
generalized.


title:
Conflict Resolution in Multiple Access Channels Supporting Simultaneous
  Successful Transmissions

abstract:
  We consider the Conflict Resolution Problem in the context of a
multiple-access system in which several stations can transmit their messages
simultaneously to the channel. We assume that there are n stations and that at
most k<= n stations are active at the same time, i.e, are willing to transmit a
message. If in a certain instant at most d<=k active stations transmit to the
channel then their messages are successfully transmitted, whereas if more than
d active stations transmit simultaneously then their messages are lost. In this
latter case we say that a conflict occurs. The present paper investigates
non-adaptive conflict resolution algorithms working under the assumption that
active stations receive a feedback from the channel that informs them on
whether their messages have been successfully transmitted. If a station becomes
aware that its message has been correctly sent over the channel then it becomes
immediately inactive. The measure to optimize is the number of time slots
needed to solve conflicts among all active stations. The fundamental question
is whether this measure decreases linearly with the number d of messages that
can be simultaneously transmitted with success. We give a positive answer to
this question by providing a conflict resolution algorithm that uses a 1/d
ratio of the number of time slots used by the optimal conflict resolution
algorithm for the case d=1. Moreover, we derive a lower bound on the number of
time slots needed to solve conflicts non-adaptively which is within a log (k/d)
factor from the upper bound. To this aim, we introduce a new combinatorial
structure that consists in a generalization of Komlos and Greenberg codes.
Constructions of these new codes are obtained via a new generalization of
selectors, whereas the non-existential result is implied by a non-existential
result for a new generalization of the locally thin families.


title:
Distributed stabilization control of rigid formations with prescribed
  orientation

abstract:
  Most rigid formation controllers reported in the literature aim to only
stabilize a rigid formation shape, while the formation orientation is not
controlled. This paper studies the problem of controlling rigid formations with
prescribed orientations in both 2-D and 3-D spaces. The proposed controllers
involve the commonly-used gradient descent control for shape stabilization, and
an additional term to control the directions of certain relative position
vectors associated with certain chosen agents. In this control framework, we
show the minimal number of agents which should have knowledge of a global
coordinate system (2 agents for a 2-D rigid formation and 3 agents for a 3-D
rigid formation), while all other agents do not require any global coordinate
knowledge or any coordinate frame alignment to implement the proposed control.
The exponential convergence to the desired rigid shape and formation
orientation is also proved. Typical simulation examples are shown to support
the analysis and performance of the proposed formation controllers.


title:
Constraining the Number of Positive Responses in Adaptive, Non-Adaptive,
  and Two-Stage Group Testing

abstract:
  Group testing is a well known search problem that consists in detecting the
defective members of a set of objects O by performing tests on properly chosen
subsets (pools) of the given set O. In classical group testing the goal is to
find all defectives by using as few tests as possible. We consider a variant of
classical group testing in which one is concerned not only with minimizing the
total number of tests but aims also at reducing the number of tests involving
defective elements. The rationale behind this search model is that in many
practical applications the devices used for the tests are subject to
deterioration due to exposure to or interaction with the defective elements. In
this paper we consider adaptive, non-adaptive and two-stage group testing. For
all three considered scenarios, we derive upper and lower bounds on the number
of "yes" responses that must be admitted by any strategy performing at most a
certain number t of tests. In particular, for the adaptive case we provide an
algorithm that uses a number of "yes" responses that exceeds the given lower
bound by a small constant. Interestingly, this bound can be asymptotically
attained also by our two-stage algorithm, which is a phenomenon analogous to
the one occurring in classical group testing. For the non-adaptive scenario we
give almost matching upper and lower bounds on the number of "yes" responses.
In particular, we give two constructions both achieving the same asymptotic
bound. An interesting feature of one of these constructions is that it is an
explicit construction. The bounds for the non-adaptive and the two-stage cases
follow from the bounds on the optimal sizes of new variants of d-cover free
families and (p,d)-cover free families introduced in this paper, which we
believe may be of interest also in other contexts.


title: Memory effect induced macroscopic-microscopic entanglement

abstract:
  We study optomechanical entanglement between an optical cavity field and a
movable mirror coupled to a non-Markovian environment. The non-Markovian
quantum state diffusion (NMQSD) approach and the non-Markovian master equation
are shown to be useful in investigating the entanglement generation between the
cavity field and the movable mirror. The simple model presented in this paper
demonstrates several interesting properties of optomechanical entanglement that
are associated with environment memory effects. It is evident that the
effective environment central frequency can be used to modulate the
optomechanical entanglement. In addition, we show that the maximum entanglement
may be achieved by properly choosing the effective detuning which is
significantly dependent on the strength of the memory effect of the
environment.


title:
A Low-Complexity Transceiver Design in Sparse Multipath Massive MIMO
  Channels

abstract:
  In this letter, we develop a low-complexity transceiver design, referred to
as semi-random beam pairing (SRBP), for sparse multipath massive MIMO channels.
By exploring a sparse representation of the MIMO channel in the virtual angular
domain, we generate a set of transmit-receive beam pairs in a semi-random way
to support the simultaneous transmission of multiple data streams. These data
streams can be easily separated at the receiver via a successive interference
cancelation (SIC) technique, and the power allocation among them are optimized
based on the classical waterfilling principle. The achieved degree of freedom
(DoF) and capacity of the proposed approach are analyzed. Simulation results
show that, compared to the conventional singular value decomposition
(SVD)-based method, the proposed transceiver design can achieve near-optimal
DoF and capacity with a significantly lower computational complexity.


title: Causal Bandits: Learning Good Interventions via Causal Inference

abstract:
  We study the problem of using causal models to improve the rate at which good
interventions can be learned online in a stochastic environment. Our formalism
combines multi-arm bandits and causal inference to model a novel type of bandit
feedback that is not exploited by existing approaches. We propose a new
algorithm that exploits the causal feedback and prove a bound on its simple
regret that is strictly better (in all quantities) than algorithms that do not
use the additional causal information.


title: Constrained N-body problems

abstract:
  We consider a problem of mass points interacting gravitationally whose motion
is subjected to certain holonomic constraints. The motion of points is
restricted to certain curves and surfaces. We illustrate the complicated
behaviour of trajectories of these systems using Poincar\'e cross sections. For
some models we prove the non-integrability analysing properties of the
differential Galois group of variational equations along certain particular
solutions of considered systems. Also some integrable cases are identified.


title:
Critical Casimir forces from the equation of state of quantum critical
  systems

abstract:
  The mapping between a classical length and inverse temperature as imaginary
time provides a direct equivalence between the Casimir force of a classical
system in $D$ dimensions and internal energy of a quantum system in
$d$$=$$D$$-$$1$ dimensions. The scaling functions of the critical Casimir force
of the classical system with periodic boundaries thus emerge from the analysis
of the symmetry related quantum critical point. We show that both
non-perturbative renormalization group and quantum Monte Carlo analysis of
quantum critical points provide quantitative estimates for the critical Casimir
force in the corresponding classical model, giving access to widely different
aspect ratios for the geometry of confined systems. In the light of these
results we propose protocols for the experimental realization of critical
Casimir forces for periodic boundaries through state-of-the-art cold-atom and
solid-state experiments.


title:
Rational sphere valued supercocycles in M-theory and type IIA string
  theory

abstract:
  We show that supercocycles on super $L_\infty$-algebras capture, at the
rational level, the twisted cohomological charge structure of the fields of
M-theory and of type IIA string theory. We show that rational 4-sphere-valued
supercocycles for M-branes in M-theory descend to supercocycles in type IIA
string theory with coefficients in the free loop space of the 4-sphere, to
yield the Ramond-Ramond fields in the rational image of twisted K-theory, with
the twist given by the B-field. In particular, we derive the M2/M5
$\leftrightarrow$ F1/Dp/NS5 correspondence via dimensional reduction of
sphere-valued super-$L_\infty$-cocycles.


title:
Deep CNNs along the Time Axis with Intermap Pooling for Robustness to
  Spectral Variations

abstract:
  Convolutional neural networks (CNNs) with convolutional and pooling
operations along the frequency axis have been proposed to attain invariance to
frequency shifts of features. However, this is inappropriate with regard to the
fact that acoustic features vary in frequency. In this paper, we contend that
convolution along the time axis is more effective. We also propose the addition
of an intermap pooling (IMP) layer to deep CNNs. In this layer, filters in each
group extract common but spectrally variant features, then the layer pools the
feature maps of each group. As a result, the proposed IMP CNN can achieve
insensitivity to spectral variations characteristic of different speakers and
utterances. The effectiveness of the IMP CNN architecture is demonstrated on
several LVCSR tasks. Even without speaker adaptation techniques, the
architecture achieved a WER of 12.7% on the SWB part of the Hub5'2000
evaluation test set, which is competitive with other state-of-the-art methods.


title: Jet Mass Dependence of Fragmentation in Positron-Proton Collisions

abstract:
  We propose the characterization of fragmentation functions by the energy
fraction x, a hadron takes away from the energy of the jet measured in the
frame co-moving with the jet. Besides, we propose the usage of the jet mass as
the fragmentation scale Q. We show that these two Lorentz-invariant variables
emerge naturally in a microcanonical ensemble with conserved fourmomentum.
Then, we construct a statistical hadronisation model, in which, two features of
the hadronic final states in various high-energy reactions (power law spectra
and negative-binomial multiplicity distributions) can be connected simply.
Finally, we analyse the scale dependence of the parameters of the model (power
of the spectrum and mean energy per hadron) in the phi^3 theory. Fitting
fragmentation functions in diffractive positron-proton collisions, we obtain a
prediction for the jet mass dependence of the hadron multiplicity distribution
inside jets.


title: On some properties of enhanced power graph

abstract:
  Given a group $G$, the enhanced power graph of $G$ denoted by
$\mathcal{G}_e(G)$, is the graph with vertex set $G$ and two distinct vertices
$x, y$ are edge connected in $\mathcal{G}_e(G)$ if there exists $z\in G $ such
that $x=z^m$ and $ y=z^n $, for some $m, n\in \mathbb{N}$. In this article, we
characterize the enhanced power graph $\mathcal{G}_e(G)$ of $G$. The graph
$\mathcal{G}_e(G)$ is complete if and only if $G$ is cyclic, and
$\mathcal{G}_e(G)$ is Eulerian if and only if $|G|$ is odd. We classify all
abelian groups and also all non-abelian $p-$groups $G$ for which
$\mathcal{G}_e(G)$ satisfies the cone property.


title: On the Wiener-Hopf compactification of a Symmetric Cone

abstract:
  Let V be a finite dimensional real Euclidean Jordan algebra with the identity
element 1. Let Q be the closed convex cone of squares. We show that the Wiener-
Hopf compactification of Q is the interval (1-Q) \cap (-1+Q). As a consequence,
we deduce that the K-groups of the Wiener-Hopf C^{*}-algebra associated to Q
are trivial.


title:
The tail distribution of the Derivative martingale and the global
  minimum of the branching random walk

abstract:
  In a seminal paper Biggins and Kyprianou \cite{BKy04} proved the existence of
a non degenerate limit for the {\it Derivative martingale} of the branching
random walk. As shown in \cite{Aid11} and \cite{Mad11}, this is an object of
central importance in the study of the extremes of the branching random walk.
In this paper we investigate the tail distribution of the limit of the {\it
Derivative Martingale} by mean of the study of the global minimum of the
branching random walk. This new approach leads us to extend the results of
\cite{Gui90} and \cite{Bur09} under slighter assumptions.


title:
Discovery of Latent Factors in High-dimensional Data Using Tensor
  Methods

abstract:
  Unsupervised learning aims at the discovery of hidden structure that drives
the observations in the real world. It is essential for success in modern
machine learning. Latent variable models are versatile in unsupervised learning
and have applications in almost every domain. Training latent variable models
is challenging due to the non-convexity of the likelihood objective. An
alternative method is based on the spectral decomposition of low order moment
tensors. This versatile framework is guaranteed to estimate the correct model
consistently. My thesis spans both theoretical analysis of tensor decomposition
framework and practical implementation of various applications. This thesis
presents theoretical results on convergence to globally optimal solution of
tensor decomposition using the stochastic gradient descent, despite
non-convexity of the objective. This is the first work that gives global
convergence guarantees for the stochastic gradient descent on non-convex
functions with exponentially many local minima and saddle points. This thesis
also presents large-scale deployment of spectral methods carried out on various
platforms. Dimensionality reduction techniques such as random projection are
incorporated for a highly parallel and scalable tensor decomposition algorithm.
We obtain a gain in both accuracies and in running times by several orders of
magnitude compared to the state-of-art variational methods. To solve real world
problems, more advanced models and learning algorithms are proposed. This
thesis discusses generalization of LDA model to mixed membership stochastic
block model for learning user communities in social network, convolutional
dictionary model for learning word-sequence embeddings, hierarchical tensor
decomposition and latent tree structure model for learning disease hierarchy,
and spatial point process mixture model for detecting cell types in
neuroscience.


title: Weibel instability driven by spatially anisotropic density structures

abstract:
  Observations of afterglows of gamma-ray bursts suggest (GRBs) that post-shock
magnetic fields are strongly amplified to about 100 times the shock-compressed
value. The Weibel instability appears to play an important role in generating
of the magnetic field. However, recent simulations of collisionless shocks in
homogeneous plasmas show that the magnetic field generated by the Weibel
instability rapidly decays. There must be some density fluctuations in
interstellar and circumstellar media. The density fluctuations are
anisotropically compressed in the downstream region of relativistic shocks. In
this paper, we study the Weibel instability in electron--positron plasmas with
the spatially anisotropic density distributions by means of two-dimensional
particle-in-cell simulations. We find that large magnetic fields are maintained
for a longer time by the Weibel instability driven by the spatially anisotropic
density structure. Particles anisotropically escape from the high density
region, so that the temperature anisotropy is generated and the Weibel
instability becomes unstable. Our simulation results suggest that the Weibel
instability driven by an anisotropic density structure can generate
sufficiently large magnetic fields and they can cover sufficiently large
regions to explain the afterglow emission of GRBs.


title:
Mean-parametrized Conway-Maxwell-Poisson regression models for dispersed
  counts

abstract:
  Conway-Maxwell-Poisson (CMP) distributions are flexible generalizations of
the Poisson distribution for modelling overdispersed or underdispersed counts.
The main hindrance to their wider use in practice seems to be the inability to
directly model the mean of counts, making them not compatible with nor
comparable to competing count regression models, such as the log-linear
Poisson, negative-binomial or generalized Poisson regression models. This note
illustrates how CMP distributions can be parametrized via the mean, so that
simpler and more easily-interpretable mean-models can be used, such as a
log-linear model. Other link functions are also available, of course. In
addition to establishing attractive theoretical and asymptotic properties of
the proposed model, its good finite-sample performance is exhibited through
various examples and a simulation study based on real datasets. Moreover, the
MATLAB routine to fit the model to data is demonstrated to be up to an order of
magnitude faster than the current software to fit standard CMP models, and over
two orders of magnitude faster than the recently proposed hyper-Poisson model.


title:
A charge-driven feedback loop in the resonance fluorescence of a single
  quantum dot

abstract:
  Semiconductor quantum dots can emit antibunched, single photons on demand
with narrow linewidths. However, the observed linewidths are broader than
lifetime measurements predict, due to spin and charge noise in the environment.
This noise randomly shifts the transition energy and destroys coherence and
indistinguishability of the emitted photons. Fortunately, the fluctuations can
be reduced by a stabilization using a suitable feedback loop. In this work we
demonstrate a fast feedback loop that manifests itself in a strong hysteresis
and bistability of the exciton resonance fluorescence signal. Field ionization
of photogenerated quantum dot excitons leads to the formation of a charged
interface layer that drags the emission line along over a frequency range of
more than 30 GHz. This internal charge-driven feedback loop could be used to
reduce the spectral diffusion and stabilize the emission frequency within
milliseconds, presently only limited by the sample structure, but already
faster than nuclear spin feedback.


title: Intrinsic Alignments of Galaxies in the Illustris Simulation

abstract:
  We study intrinsic alignments (IA) of galaxy image shapes within the
Illustris cosmic structure formation simulations. We investigate how IA
correlations depend on observable galaxy properties such as stellar mass,
apparent magnitude, redshift, and photometric type, and on the employed shape
measurement method. The correlations considered include the matter
density-intrinsic ellipticity (mI), galaxy density-intrinsic ellipticity (dI),
gravitational shear-intrinsic ellipticity (GI), and intrinsic
ellipticity-intrinsic ellipticity (II) correlations. We find stronger
correlations for more massive and more luminous galaxies, as well as for
earlier photometric types, in agreement with observations. Moreover, the
correlations significantly depend on the choice of shape estimator, even if
calibrated to serve as unbiased shear estimators. In particular, shape
estimators that down-weight the outer parts of galaxy images produce much
weaker IA signals on intermediate and large scales than methods employing flat
radial weights. The expected contribution of intrinsic alignments to the
observed ellipticity correlation in tomographic cosmic shear surveys may be
below one percent or several percent of the full signal depending on the
details of the shape measurement method. A comparison of our results to a tidal
alignment model indicates that such a model is able to reproduce the IA
correlations well on intermediate and large scales, provided the effect of
varying galaxy density is correctly taken into account. We also find that the
GI contributions to the observed ellipticity correlations could be inferred
directly from measurements of galaxy density-intrinsic ellipticity
correlations, except on small scales, where systematic differences between mI
and dI correlations are large.


title: Decidable Characterization of FO2(<,+1) and locality of DA

abstract:
  Several years ago Th\'erien and Wilke exhibited a decidable characterization
of the languages of words that are definable in FO2(<,+1). Their proof relies
on three separate ingredients. The first one is the characterization of the
languages that are definable in FO2(<) as those whose syntactic semigroup
belongs to the variety DA. Then, this result is combined with a wreath product
argument showing that being definable in FO2(<,+1) corresponds to having a
syntactic semigroup in DA*D. Finally, proving that membership of a semigroup in
DA*D is decidable requires a third ingredient: the "locality" of DA, a result
proved by Almeida. In this note we present a new self-contained and simple
proof that definability in FO2(<,+1) is decidable. We obtain the locality of DA
as a corollary.


title:
Generation and evolution of spin-, valley- and layer-polarized excited
  carriers in inversion-symmetric WSe2

abstract:
  Manipulation of spin and valley degrees of freedom is a key step towards
realizing novel quantum technologies, for which atomically thin transition
metal dichalcogenides (TMDCs) have been established as promising candidates. In
monolayer TMDCs, the lack of inversion symmetry gives rise to a spin-valley
correlation of the band structure allowing for valley-selective electronic
excitation with circularly polarized light. Here we show that, even in
centrosymmetric samples of 2H-WSe2, circularly polarized light can generate
spin-, valley- and layer-polarized excited states in the conduction band.
Employing time- and angle-resolved photoemission spectroscopy (trARPES) with
spin-selective excitation, the dynamics of valley and layer pseudospins of the
excited carriers are investigated. Complementary time-dependent density
functional theory (TDDFT) calculations of the excited state populations reveal
a strong circular dichroism of the spin-, valley- and layer-polarizations and a
pronounced 2D character of the excited states in the K valleys. We observe
scattering of carriers towards the global minimum of the conduction band on a
sub-100 femtosecond timescale to states with three-dimensional character
facilitating inter-layer charge transfer. Our results establish the optical
control of coupled spin-, valley- and layer-polarized states in centrosymmetric
materials and suggest the suitability of TMDC multilayer materials for
valleytronic and spintronic device concepts.


title: Small field axion inflation with sub-Planckian decay constant

abstract:
  We study an axion inflation model recently proposed within the framework of
type IIB superstring theory, where we pay a particular attention to a
sub-Planckian axion decay constant. Our axion potential can lead to the small
field inflation with a small tensor-to-scalar ratio, and a typical reheating
temperature can be as low as GeV.


title: Nonresonance adiabatic photon trap

abstract:
  Concept of high efficiency photon storage based on adiabatic confinement
between concave mirrors is presented and experimentally investigated. The
approach is insensitive to typical for Fabri-Perot cells requirements on
quality of accumulated radiation, tolerance of resonator elements and their
stability. Experiments have been carried out with the trap, which consists from
opposed concave cylindrical mirrors and conjugated with them spherical mirrors.
In result, high efficiency for accumulation of radiation with large angular
spread and spectrum width has been confirmed. As radiation source a commercial
fiber laser has been used.


title: On Kernel of the regulator map

abstract:
  By using the infinitesimal methods due to Bloch, Green and Griffiths, we
construct an infinitesimal form of the regulator map and verify that its kernel
is $\Omega^{1}_{\mathbb{C}/\mathbb{Q}}$, which suggests Question 1.1 seems
reasonable at the infinitesimal level.


title: Velocity Map Imaging the Scattering Plane of Gas Surface Collisions

abstract:
  The ability of gas-surface dynamics studies to resolve the velocity
distribution of the scattered species in the 2D sacattering plane has been
limited by technical capabilities and only a few different approaches have been
explored in recent years. In comparison, gas-phase scattering studies have been
transformed by the near ubiquitous use of velocity map imaging. We describe an
innovative means of introducing a surface within the electric field of a
typical velocity map imaging experiment. The retention of optimum velocity
mapping conditions was demonstrated by measurements of iodomethane-d3
photodissociation and SIMION calculations. To demonstrate the systems
capabilities the velocity distributions of ammonia molecules scattered from a
PTFE surface have been measured for multiple product rotational states.


title: Heat Engines for Dilatonic Born-Infeld Black Holes

abstract:
  In the context of dilaton coupled Einstein gravity with a negative
cosmological constant and a Born-Infeld field, we study heat engines where
charged black hole is the working substance. Using the existence of a notion of
thermodynamic mass and volume (which depend on the dilaton coupling), the
mechanical work takes place via the pdV terms present in the first law of
extended gravitational thermodynamics. Efficiency is analyzed as a function of
dilaton and Born-Infeld couplings, and results are compared with analogous
computations in the related conformal solutions in the Brans-Dicke Born-Infeld
theory and black holes in Anti de Sitter space-time.


title: On the Alexander polynomial of links in lens spaces

abstract:
  We show how the Alexander polynomial of links in lens spaces is related to
the classical Alexander polynomial of a link in the 3-sphere, obtained by
cutting out the exceptional lens space fibre. It follows from these
relationship that a certain normalization of the Alexander polynomial satisfies
a skein relation in lens spaces.


title:
In a search for a shape maximizing packing fraction for two-dimensional
  random sequential adsorption

abstract:
  Random sequential adsorption (RSA) of various two dimensional objects is
studied in order to find a shape which maximizes the saturated packing
fraction. This investigation was begun in our previous paper [Cie\'sla et al.,
Phys. Chem. Chem. Phys. 17, 24376 (2015)], where the densest packing was
studied for smoothed dimers. Here this shape is compared with a smoothed
$n$-mers, spherocylinders and ellipses. It is found that the highest packing
fraction out of the studied shapes is $0.58405 \pm 0.0001$ and is obtained for
ellipses having long-to-short axis ratio of $1.85$, which is also the largest
anisotropy among the investigated shapes.


title: Soft hairs on isolated horizon implanted by electromagnetic fields

abstract:
  Inspired by the recent proposal of soft hair on black holes in Phys. Rev.
Lett. 116, 231301 (2016), we have shown that an isolated horizon carries soft
hairs implanted by electromagnetic fields. The solution space and the
asymptotic symmetries of Einstein-Maxwell theory have been worked out
explicitly near isolated horizon. The conserved current has been computed and
an infinite number of near horizon charges have been introduced from the
electromagnetic fields associated to the asymptotic $U(1)$ symmetry near the
horizon, which indicates the fact that isolated horizon carries a large amount
of soft electric hairs. The soft electric hairs, i.e. asymptotic $U(1)$
charges, are shown to be equivalent to the electric multipole moments of
isolated horizons. It is further argued that the isolated horizon
supertranslation is from the ambiguity of its foliation and an analogue of
memory effect on horizon can be expected.


title:
First-principles photoemission spectroscopy of DNA and RNA nucleobases
  from Koopmans-compliant functionals

abstract:
  The need to interpret ultraviolet photoemission data strongly motivates the
refinement of first-principles techniques able to accurately predict spectral
properties. In this work we employ Koopmans-compliant functionals, constructed
to enforce piecewise linearity in approximate density functionals, to calculate
the structural and electronic properties of DNA and RNA nucleobases. Our
results show that not only ionization potentials and electron affinities are
accurately predicted with mean absolute errors < 0.1 eV, but also that
calculated photoemission spectra are in excellent agreement with experimental
ultraviolet photoemission spectra. In particular, the role and contribution of
different tautomers to the photoemission spectra are highlighted and discussed
in detail. The structural properties of nucleobases are also investigated,
showing an improved description with respect to local and semilocal
density-functional theory. Methodologically, our results further consolidate
the role of Koopmans-compliant functionals in providing, through
orbital-density-dependent potentials, accurate electronic and spectral
properties.


title:
Potential splitting approach to e-H and e-He${}^+$ scattering with zero
  total angular momentum

abstract:
  An approach based on splitting the reaction potential into a finite range
part and a long range tail part to describe few-body scattering in the case of
a Coulombic interaction is proposed. The solution to the Schr\"odinger equation
for the long range tail of the reaction potential is used as an incoming wave.
This reformulation of the scattering problem into an inhomogeneous
Schr\"odinger equation with asymptotic outgoing waves makes it suitable for
solving with the exterior complex scaling technique. The validity of the
approach is analyzed from a formal point of view and demonstrated numerically,
where the calculations are performed with the finite element method. The method
of splitting the potential in this way is illustrated with calculations of the
electron scattering on the hydrogen atom and the positive helium ion in energy
regions where resonances appear.


title: Towards Anthropo-inspired Computational Systems: the $P^3$ Model

abstract:
  This paper proposes a model which aim is providing a more coherent framework
for agents design. We identify three closely related anthropo-centered domains
working on separate functional levels. Abstracting from human physiology,
psychology, and philosophy we create the $P^3$ model to be used as a multi-tier
approach to deal with complex class of problems. The three layers identified in
this model have been named PhysioComputing, MindComputing, and MetaComputing.
Several instantiations of this model are finally presented related to different
IT areas such as artificial intelligence, distributed computing, software and
service engineering.


title:
Precession-driven dynamos in a full sphere and the role of large scale
  cyclonic vortices

abstract:
  Precession has been proposed as an alternative power source for planetary
dynamos. Previous hydrodynamic simulations suggested that precession can
generate very complex flows in planetary liquid cores [Y. Lin, P. Marti, and J.
Noir, "Shear-driven parametric instability in a precessing sphere," Physics of
Fluids 27, 046601 (2015)]. In the present study, we numerically investigate the
magnetohydrodynamics of a precessing sphere. We demonstrate precession driven
dynamos in different flow regimes, from laminar to turbulent flows. In
particular, we highlight the magnetic field generation by large scale cyclonic
vortices, which has not been explored previously. In this regime, dynamos can
be sustained at relatively low Ekman numbers and magnetic Prandtl numbers,
which paves the way for planetary applications.


title:
Spin-orbit coupling control of anisotropy, ground state and frustration
  in 5d2 Sr2MgOsO6

abstract:
  The influence of spin-orbit coupling (SOC) on the physical properties of the
5d2 system Sr2MgOsO6 is probed via a combination of magnetometry, specific heat
measurements, elastic and inelastic neutron scattering, and density functional
theory calculations. Although a significant degree of frustration is expected,
we find that Sr2MgOsO6 orders in a type I antiferromagnetic structure at the
remarkably high temperature of 108 K. The measurements presented allow for the
first accurate quantification of the size of the magnetic moment in a 5d2
system of 0.60(2) muB - a significantly reduced moment from the expected value
for such a system. Furthermore, significant anisotropy is identified via a spin
excitation gap, and we confirm by first principles calculations that SOC not
only provides the magnetocrystalline anisotropy, but also plays a crucial role
in determining both the ground state magnetic order and the size of the local
moment in this compound. Through comparison to Sr2ScOsO6, it is demonstrated
that SOC-induced anisotropy has the ability to relieve frustration in 5d2
systems relative to their 5d3 counterparts, providing an explanation of the
high TN found in Sr2MgOsO6.


title:
Topological origin of edge states in two-dimensional inversion-symmetric
  insulators and semimetals

abstract:
  Symmetries play an essential role in identifying and characterizing
topological states of matter. Here, we classify topologically two-dimensional
(2D) insulators and semimetals with vanishing spin-orbit coupling using
time-reversal ($\mathcal{T}$) and inversion ($\mathcal{I}$) symmetry. This
allows us to link the presence of edge states in $\mathcal{I}$ and
$\mathcal{T}$ symmetric 2D insulators, which are topologically trivial
according to the Altland-Zirnbauer table, to a $\mathbb{Z}_2$ topological
invariant. This invariant is directly related to the quantization of the Zak
phase. It also predicts the generic presence of edge states in Dirac
semimetals, in the absence of chiral symmetry. We then apply our findings to
bilayer black phosphorus and show the occurrence of a gate-induced topological
phase transition, where the $\mathbb{Z}_2$ invariant changes.


title: Optimal Sparsification for Some Binary CSPs Using Low-degree Polynomials

abstract:
  This paper analyzes to what extent it is possible to efficiently reduce the
number of clauses in NP-hard satisfiability problems, without changing the
answer. Upper and lower bounds are established using the concept of
kernelization. Existing results show that if NP is not contained in coNP/poly,
no efficient preprocessing algorithm can reduce n-variable instances of CNF-SAT
with d literals per clause, to equivalent instances with $O(n^{d-e})$ bits for
any e > 0. For the Not-All-Equal SAT problem, a compression to size
$\~O(n^{d-1})$ exists. We put these results in a common framework by analyzing
the compressibility of binary CSPs. We characterize constraint types based on
the minimum degree of multivariate polynomials whose roots correspond to the
satisfying assignments, obtaining (nearly) matching upper and lower bounds in
several settings. Our lower bounds show that not just the number of
constraints, but also the encoding size of individual constraints plays an
important role. For example, for Exact Satisfiability with unbounded clause
length it is possible to efficiently reduce the number of constraints to n+1,
yet no polynomial-time algorithm can reduce to an equivalent instance with
$O(n^{2-e})$ bits for any e > 0, unless NP is a subset of coNP/poly.


title:
Spatially resolved studies of the phases and morphology of
  methylammonium and formamidinium lead tri-halide perovskites

abstract:
  The family of organic-inorganic tri-halide perovskites including MA
(MethylAmmonium)PbI$_{3}$, MAPbI$_{3-x}$Cl$_{x}$, FA (FormAmidinium)PbI$_{3}$
and FAPbBr$_{3}$ are having a tremendous impact on the field of photovoltaic
cells due to their ease of deposition and efficiencies, but device performance
can be significanly affected by inhomogeneities. Here we report a study of
temperature dependent micro-photoluminescence which shows a strong spatial
inhomogeneity related to the presence of microcrystalline grains, which can be
both light and dark. In all of the tri-iodide based materials there is evidence
that the tetragonal to orthorhombic phase transition observed around 160K does
not occur uniformly across the sample with domain formation related to the
underlying microcrystallite grains, some of which remain in the high
temperature, tetragonal, phase even at very low temperatures. At low
temperature the tetragonal domains can be significantly influenced by local
defects in the layers. In FAPbBr$_{3}$ a more macroscopic domain structure is
observed with large numbers of grains forming phase correlated regions.


title:
Intrinsic noise and deviations from criticality in Boolean
  gene-regulatory networks

abstract:
  Gene regulatory networks can be successfully modeled as Boolean networks. A
much discussed hypothesis says that such model networks reproduce empirical
findings the best if they are tuned to operate at criticality, i.e. at the
borderline between their ordered and disordered phases. Critical networks have
been argued to lead to a number of functional advantages such as maximal
dynamical range, maximal sensitivity to environmental changes, as well as to an
excellent trade off between stability and flexibility. Here, we study the
effect of noise within the context of Boolean networks trained to learn complex
tasks under supervision. We verify that quasi-critical networks are the ones
learning in the fastest possible way --even for asynchronous updating rules--
and that the larger the task complexity the smaller the distance to
criticality. On the other hand, when additional sources of intrinsic noise in
the network states and/or in its wiring pattern are introduced, the optimally
performing networks become clearly subcritical. These results suggest that in
order to compensate for inherent stochasticity, regulatory and other type of
biological networks might become subcritical rather than being critical, all
the most if the task to be performed has limited complexity.


title:
Interaction and resistance: The recognition of intentions in new
  human-computer interaction

abstract:
  Just as AI has moved away from classical AI, human-computer interaction (HCI)
must move away from what I call 'good old fashioned HCI' to 'new HCI' - it must
become a part of cognitive systems research where HCI is one case of the
interaction of intelligent agents (we now know that interaction is essential
for intelligent agents anyway). For such interaction, we cannot just 'analyze
the data', but we must assume intentions in the other, and I suggest these are
largely recognized through resistance to carrying out one's own intentions.
This does not require fully cognitive agents but can start at a very basic
level. New HCI integrates into cognitive systems research and designs
intentional systems that provide resistance to the human agent.


title:
Survey on RGB, 3D, Thermal, and Multimodal Approaches for Facial
  Expression Recognition: History, Trends, and Affect-related Applications

abstract:
  Facial expressions are an important way through which humans interact
socially. Building a system capable of automatically recognizing facial
expressions from images and video has been an intense field of study in recent
years. Interpreting such expressions remains challenging and much research is
needed about the way they relate to human affect. This paper presents a general
overview of automatic RGB, 3D, thermal and multimodal facial expression
analysis. We define a new taxonomy for the field, encompassing all steps from
face detection to facial expression recognition, and describe and classify the
state of the art methods accordingly. We also present the important datasets
and the bench-marking of most influential methods. We conclude with a general
discussion about trends, important questions and future lines of research.


title:
IDNet: Smartphone-based Gait Recognition with Convolutional Neural
  Networks

abstract:
  Here, we present IDNet, a user authentication framework from
smartphone-acquired motion signals. Its goal is to recognize a target user from
their way of walking, using the accelerometer and gyroscope (inertial) signals
provided by a commercial smartphone worn in the front pocket of the user's
trousers. IDNet features several innovations including: i) a robust and
smartphone-orientation-independent walking cycle extraction block, ii) a novel
feature extractor based on convolutional neural networks, iii) a one-class
support vector machine to classify walking cycles, and the coherent integration
of these into iv) a multi-stage authentication technique. IDNet is the first
system that exploits a deep learning approach as universal feature extractors
for gait recognition, and that combines classification results from subsequent
walking cycles into a multi-stage decision making framework. Experimental
results show the superiority of our approach against state-of-the-art
techniques, leading to misclassification rates (either false negatives or
positives) smaller than 0.15% with fewer than five walking cycles. Design
choices are discussed and motivated throughout, assessing their impact on the
user authentication performance.


title: Quarkonium Contribution to Meson Molecules

abstract:
  Starting from a molecular picture for the X(3872) resonance, this state and
its J^{PC}=2++ HQSS partner [X2(4012)] are analyzed within a model which
incorporates possible mixings with 2P charmonium states. Since it is reasonable
to expect the bare chi_{c1}(2P) to be located above the D\bar D* threshold, but
relatively close to it, the presence of the charmonium state provides an
effective attraction that will contribute to bind the X(3872), but it will not
appear in the 2++ sector. Indeed in this latter sector, the chi_{c2}(2P) should
provide an effective small repulsion, because it is placed well below the
D*\bar D* threshold. We show how the 1++ and 2++ bare charmonium poles are
modified due to the D(*)\bar D(*) loop effects, and the first one is moved to
the complex plane. The meson loops produce, besides some shifts in the masses
of the charmonia, a finite width for the 1++ dressed charmonium state. On the
other hand, the X(3872) and X2(4012) start developing some charmonium content,
which is estimated by means of the compositeness Weinberg sum-rule. We also
show that for X(3872) molecular probabilities of around 70-90 %, the X2
resonance destabilizes and disappears from the spectrum, becoming either a
virtual state or being located deep into the complex plane, with decreasing
influence in the D* \bar D* scattering line.


title: Outdoor Field Experience with Autonomous RPC Based Stations

abstract:
  In the last two decades Resistive Plate Chambers were employed in the Cosmic
Ray Experiments COVER-PLASTEX and ARGO/YBJ. In both experiments the detectors
were housed indoors, likely owing to gas distribution requirements and the need
to control environment variables that directly affect RPCs operational
stability. But in experiments where Extended Air Shower (EAS) sampling is
necessary, large area arrays composed by dispersed stations are deployed,
rendering this kind of approach impossible. In this situation, it would be
mandatory to have detectors that could be deployed in small standalone
stations, with very rare opportunities for maintenance, and with good
resilience to environmental conditions. Aiming to meet these requirements, we
started some years ago the development of RPCs for Autonomous Stations. The
results from indoor tests and measurements were very promising, both concerning
performance and stability under very low gas flow rate, which is the main
requirement for Autonomous Stations. In this work we update the indoor results
and show the first ones concerning outdoor stable operation. In particular, a
dynamic adjustment of the high voltage is applied to keep gas gain constant.