title: EPOpt: Learning Robust Neural Network Policies Using Model Ensembles

abstract:
  Sample complexity and safety are major challenges when learning policies with
reinforcement learning for real-world tasks, especially when the policies are
represented using rich function approximators like deep neural networks.
Model-based methods where the real-world target domain is approximated using a
simulated source domain provide an avenue to tackle the above challenges by
augmenting real data with simulated data. However, discrepancies between the
simulated source domain and the target domain pose a challenge for simulated
training. We introduce the EPOpt algorithm, which uses an ensemble of simulated
source domains and a form of adversarial training to learn policies that are
robust and generalize to a broad range of possible target domains, including
unmodeled effects. Further, the probability distribution over source domains in
the ensemble can be adapted using data from target domain and approximate
Bayesian methods, to progressively make it a better approximation. Thus,
learning on a model ensemble, along with source domain adaptation, provides the
benefit of both robustness and learning/adaptation.


title:
Theoretical description of mixed-field orientation of asymmetric top
  molecules: a time-dependent study

abstract:
  We present a theoretical study of the mixed-field-orientation of asymmetric
top molecules in tilted static electric field and non-resonant linearly
polarized laser pulse by solving the time-dependent Schr\"odinger equation.
Within this framework, we compute the mixed-field orientation of a state
selected molecular beam of benzonitrile (C$_7$H$_5$N) and compare with the
experimental observations [J. L. Hansen et al., Phys. Rev. A 83, 023406
(2011)], and with our previous time-independent descriptions [J. J. Omiste et
al., Phys. Chem. Chem. Phys. 13, 18815 (2011)]. For an excited rotational
state, we investigate the field-dressed dynamics for several field
configurations as those used in the mixed-field experiments. The non-adiabatic
phenomena and their consequences on the rotational dynamics are analyzed in
detail.


title:
Total Ionizing Dose and Synergistic Effect of Magnetoresistive Random
  Access Memory

abstract:
  Magetoresistive Random Access Memory (MRAM) was irradiated by 60Co
{\gamma}-rays and electron beam. The test of synergistic effect was performed
under additional magnetic field when irradiation. We analyzed Total Ionizing
Dose (TID) and synergistic damage mechanism of MRAM. DC, AC and function
parameters of the memory were tested in radiation and annealing by Very Large
Scale Integrated circuit (VLSI) test system. The radiation sensitive parameters
were obtained through analyzing the data. Because magnetic field imposed on
MRAM when the test of synergistic effect, Shallow Trench Isolation (STI)
leakage or Frenkel-Poole emission of synergistic effect was smaller than that
of TID, and radiation damage of synergistic effect was lower than that of TID.


title: On the gravitational stability of the Maclaurin disk

abstract:
  We study the global gravitational stability of a gaseous self-gravitating
Maclaurin disk in the absence of a halo. Further, we replace Newtonian gravity
with the specific Modified gravity theory known as MOG in the relevant
literature. MOG is an alternative theory for addressing the dark matter problem
without invoking exotic dark matter particles, and possesses two free
parameters $\alpha$ and $\mu_0$ in the weak field limit. We derive the
equilibrium gravitational potential of the Maclaurin disk in MOG and develop a
semi-analytic method for studying the response of the disk to linear
non-axysymmetric perturbations. The eigenvalue spectrum of the normal modes of
the disk is obtained and its physical meaning has been explored. We show that
Maclaurin disks are less stable in MOG than in Newtonian gravity. In fact both
parameters $(\alpha,\mu_0)$ have destabilizing effects on the disk.
Interestingly $\mu_0$ excites only the bar mode $m=2$ while $\alpha$ affects
all the modes. More specifically, when $\alpha>1$, the bar mode is strongly
unstable and unlike in Newtonian gravity can not be avoided, at least in the
weak field limit, with increasing the pressure support of the disk.


title: Sufficiently Myopic Adversaries are Blind

abstract:
  In this work we consider a communication problem in which a sender, Alice,
wishes to communicate with a receiver, Bob, over a channel controlled by an
adversarial jammer, James, who is {\em myopic}. Roughly speaking, for
blocklength $n$, the codeword $X^n$ transmitted by Alice is corrupted by James
who must base his adversarial decisions (of which locations of $X^n$ to corrupt
and how to corrupt them) not on the codeword $X^n$ but on $Z^n$, an image of
$X^n$ through a noisy memoryless channel. More specifically, our communication
model may be described by two channels. A memoryless channel $p(z|x)$ from
Alice to James, and an {\it Arbitrarily Varying Channel} from Alice to Bob,
$p(y|x,s)$ governed by a state $X^n$ determined by James. In standard
adversarial channels the states $S^n$ may depend on the codeword $X^n$, but in
our setting $S^n$ depends only on James's view $Z^n$.
  The myopic channel captures a broad range of channels and bridges between the
standard models of memoryless and adversarial (zero-error) channels. In this
work we present upper and lower bounds on the capacity of myopic channels. For
a number of special cases of interest we show that our bounds are tight. We
extend our results to the setting of {\em secure} communication in which we
require that the transmitted message remain secret from James. For example, we
show that if (i) James may flip at most a $p$ fraction of the bits communicated
between Alice and Bob, and (ii) James views $X^n$ through a binary symmetric
channel with parameter $q$, then once James is "sufficiently myopic" (in this
case, when $q>p$), then the optimal communication rate is that of an adversary
who is "blind" (that is, an adversary that does not see $X^n$ at all), which is
$1-H(p)$ for standard communication, and $H(q)-H(p)$ for secure communication.
A similar phenomenon exists for our general model of communication.


title: Configuration dependent reflection induced by dissipated localized modes

abstract:
  We study the one photon scattering problem for a super cavity (SC) coupling
with two two-level atoms. With atomic decay, we find a sudden drop in
reflection at $\Delta=0$ for the two atoms in the node-antinode configuration
but not in the antinode-node one. The underlying mechanism is due to the
scatterer has a configuration dependent localized dissipated eigen-mode at
$\Delta=0$. In the node-antinode configuration, the eigen-mode localized near
the input side, which can transport the photon into the SC. By exciting the
atom at the node, the photon can leak into the reservoir due to atomic decay,
which causes the sudden drop at $\Delta=0$ in reflection. In the antinode-node
case, however, the eigen-mode is localized near the output side, no photon can
be transported into the SC and leads to completely reflection at $\Delta=0$. A
similar phenomenon has been observed in a recent experiment of X-ray quantum
optics [Nature \textbf{482}, 199 (2012)] but with a much more complicated
explanation due to electromagnetically induced transparency.


title:
Existence and stability of a blow-up solution with a new prescribed
  behavior for a heat equation with a critical nonlinear gradient term

abstract:
  We consider the semilinear heat equation, to which we add a nonlinear
gradient term, with a critical power. We construct a solution which blows up in
finite time. We also give a sharp description of its blow-up profile. The proof
relies on the reduction of the problem to a finite dimensional one, and uses
the index theory to conclude.
  Thanks to the interpretation of the parameters of the finite-dimensional
problem in terms of the blow-up time and point, we also show the stability of
the constructed solution with respect to initial data. This note presents the
results and the main arguments. For the details, we refer to our paper
\cite{TZ15}.


title: Local stationarity and time-inhomogeneous Markov chains

abstract:
  In this paper, we study a notion of local stationarity for discrete time
Markov chains which is useful for applications in statistics. In the spirit of
some locally stationary processes introduced in the literature, we consider
triangular arrays of time-inhomogeneous Markov chains, defined by some families
of contracting Markov kernels. Using the Dobrushin's contraction coefficients
for various metrics, we show that the distribution of such Markov chains can be
approximated locally with the distribution of ergodic Markov chains and we also
study some mixing properties. From our approximation results in Wasserstein
metrics, we recover several properties obtained for autoregressive processes.
Moreover, using the total variation distance or more generally some distances
induced by a drift function, we consider new models, such as finite state space
Markov chains with time-varying transition matrices or some time-varying
versions of integer-valued autoregressive processes. For these two examples,
nonparametric kernel estimation of the transition matrix is discussed.
\end{abstract}


title:
Word2Vec vs DBnary: Augmenting METEOR using Vector Representations or
  Lexical Resources?

abstract:
  This paper presents an approach combining lexico-semantic resources and
distributed representations of words applied to the evaluation in machine
translation (MT). This study is made through the enrichment of a well-known MT
evaluation metric: METEOR. This metric enables an approximate match (synonymy
or morphological similarity) between an automatic and a reference translation.
Our experiments are made in the framework of the Metrics task of WMT 2014. We
show that distributed representations are a good alternative to lexico-semantic
resources for MT evaluation and they can even bring interesting additional
information. The augmented versions of METEOR, using vector representations,
are made available on our Github page.


title:
Channel Selection Scheme for Cooperative Routing Protocols in Cognitive
  Radio Networks

abstract:
  Cognitive radio networks (CRNs) propose a smart solution for spectrum usage
inefficiency. Routing protocols for CRNs follow different criteria to choose
the best route to the destination and to avoid the interference with primary
users. Some protocols use cooperative communication techniques to achieve the
full coexistence between secondary users (SUs) and primary users (PUs).
Although using such cross-layer techniques have a great impact on the quality
of the chosen routes, the existing work do not choose the best channel to send
the data over. Thus, the available spectrum is not utilized efficiently. In
this work, we propose CSCR, a channel selection scheme for cooperation-based
routing protocols in CRNs. The proposed scheme increases the spectrum
utilization through integrating the channels selection in the route discovery
phase of the cooperation-based routing protocols. The best channels, that are
less congested with primary users and that lead to minimum switching overhead,
are chosen while constructing the cooperative group. Evaluating CSCR via NS2
simulations shows that it outperforms its counterparts in terms of goodput,
end-to-end delay, and packet delivery ratio. The proposed scheme can enhance
the network goodput, in some cases, by more than 150%, as compared to other
related protocols.


title: Surrogate-assisted network analysis of nonlinear time series

abstract:
  The performance of recurrence networks and symbolic networks to detect weak
nonlinearities in time series is compared to the nonlinear prediction error.
For the synthetic data of the Lorenz system, the network measures show a
comparable performance. In the case of relatively short and noisy real-world
data from active galactic nuclei, the nonlinear prediction error yields more
robust results than the network measures. The tests are based on surrogate data
sets. The correlations in the Fourier phases of data sets from some surrogate
generating algorithms are also examined. The phase correlations are shown to
have an impact on the performance of the tests for nonlinearity.


title: A remark on local activity and passivity

abstract:
  We study local activity and its opposite, local passivity, for linear systems
and show that generically an eigenvalue of the system matrix with positive real
part implies local activity. If all state variables are port variables we prove
that the system is locally active if and only if the system matrix is not
dissipative. Local activity was suggested by Leon Chua as an indicator for the
emergence of complexity of nonlinear systems. We propose an abstract scheme
which indicates how local activity could be applied to nonlinear systems and
list open questions about possible consequences for complexity.


title:
The Simulation Model Partitioning Problem: an Adaptive Solution Based on
  Self-Clustering (Extended Version)

abstract:
  This paper is about partitioning in parallel and distributed simulation. That
means decomposing the simulation model into a numberof components and to
properly allocate them on the execution units. An adaptive solution based on
self-clustering, that considers both communication reduction and computational
load-balancing, is proposed. The implementation of the proposed mechanism is
tested using a simulation model that is challenging both in terms of structure
and dynamicity. Various configurations of the simulation model and the
execution environment have been considered. The obtained performance results
are analyzed using a reference cost model. The results demonstrate that the
proposed approach is promising and that it can reduce the simulation execution
time in both parallel and distributed architectures.


title: Two-dimensional pseudo-gravity model

abstract:
  We analyze a simple macroscopic model describing the evolution of a cloud of
particles confined in a magneto-optical trap. The behavior of the particles is
mainly driven by self--consistent attractive forces. In contrast to the
standard model of gravitational forces, the force field does not result from a
potential; moreover, the non linear coupling is more singular than the coupling
based on the Poisson equation. We establish the existence of solutions, under a
suitable smallness condition on the total mass, or, equivalently, for a
sufficiently large diffusion coefficient. When a symmetry assumption is
fulfilled, the solutions satisfy strengthened estimates (exponential moments).
We also investigate the convergence of the $N$-particles description towards
the PDE system in the mean field regime.


title:
Robust Quaternion-based Cooperative Manipulation without Force/Torque
  Information

abstract:
  This paper proposes a task-space control protocol for the collaborative
manipulation of a single object by N robotic agents. The proposed methodology
is decentralized in the sense that each agent utilizes information associated
with its own and the object's dynamic/kinematic parameters and no on-line
communication takes place. Moreover, no feedback of the contact forces/torques
is required, therefore employment of corresponding sensors is avoided. An
adaptive version of the control scheme is also introduced, where the agents'
and object's dynamic parameters are considered unknown. We also use unit
quaternions to represent the object's orientation. In addition, load sharing
coefficients between the agents are employed and internal force regulation is
guaranteed. Finally, experimental studies with two robotic arms verify the
validity and effectiveness of the proposed control protocol.


title:
Central Limit Theorem and Large Deviation Principle for Continuous Time
  Open Quantum Walks

abstract:
  Open Quantum Walks (OQWs), originally introduced by S. Attal, are quantum
generalizations of classical Markov chains. Recently, natural continuous time
models of OQW have been developed by C. Pellegrini. These models, called
Continuous Time Open Quantum Walks (CTOQWs), appear as natural continuous time
limits of discrete time OQWs. In particular they are quantum extensions of
continuous time Markov chains. This article is devoted to the study of
homogeneous CTOQW on $\mathbb{Z}^d$. We focus namely on their associated
quantum trajectories which allow us to prove a Central Limit Theorem for the
"position" of the walker as well as a Large Deviation Principle.


title:
Unitary monodromy implies the smoothness along the real axis for some
  Painlev\'{e} VI equation, I

abstract:
  In this paper, we study the Painlev\'{e} VI equation with parameter $(\frac
{9}{8},\frac{-1}{8},\frac{1}{8},\frac{3}{8})$. We prove
  (i) An explicit formula to count the number of poles of an algebraic solution
with the monodromy group $D_{N}$, where $D_{N}$ is the dihedral group of order
$2N$.
  (ii) There are only four solutions without poles in $\mathbb{C}\backslash
\left \{ 0,1\right \} $.
  (iii) If the monodromy group of the associated linear ODE of a solution
$\lambda \left( t\right) $ is unitary, then $\lambda ( t) $ has no poles in
$\mathbb{R}% \backslash \{ 0,1\} $.


title: Gauged Baby Skyrme Model with Chern-Simons term

abstract:
  The properties of the multisoliton solutions of the (2+1)-dimensional
Maxwell-Chern-Simons-Skyrme model are investigated numerically. Coupling to the
Chern-Simons term allows for existence of the electrically charge solitons
which may also carry magnetic fluxes. Two particular choices of the potential
term is considered: (i) the weakly bounded potential and (ii) the double vacuum
potential. In the absence of the gauge interaction in the former case the
individual constituents of the multisoliton configuration are well separated,
while in the latter case the rotational invariance of the configuration remains
unbroken. It is shown that coupling of the planar multi-Skyrmions to the
electric and magnetic field strongly affects the pattern of interaction between
the constituents. We analyze the dependency of the structure of the solutions,
the energies, angular momenta, electric and magnetic fields of the
configurations on the gauge coupling constant $g$, and the electric potential.
It is found that, generically, the coupling to the Chern-Simons term strongly
affects the usual pattern of interaction between the skyrmions, in particular
the electric repulsion between the solitons may break the multisoliton
configuration into partons. We show that as the gauge coupling becomes strong,
both the magnetic flux and the electric charge of the solutions become
quantized although they are not topological numbers.


title:
Stimulated Raman scattering in the relativistic regime in near-critical
  plasmas

abstract:
  Interaction of a high intensity short laser pulse with near-critical plasmas
allows to achieve extremely high coupling efficiency and transfer laser energy
to energetic ions. One dimensional Particle-In-Cell (PIC) simulations are
considered to detail the processes involved in the energy transfer. A
confrontation of the numerical results with the theory highlights a key role
played by the process of stimulated Raman scattering in the relativistic
regime. The interaction of a 1 ps laser pulse (I $\sim$ 6.10$^{18}$ W.cm$^2$)
with an under-critical (0.5 $n_c$) homogeneous plasma leads to a very high
plasma absorption reaching 68 % of the laser pulse energy. This permits a
homogeneous electron heating all along the plasma and an efficient ion
acceleration at the plasma edges and in cavities.


title:
A Mean-Field Matrix-Analytic Method for Bike Sharing Systems under
  Markovian Environment

abstract:
  To reduce automobile exhaust pollution, traffic congestion and parking
difficulties, bike-sharing systems are rapidly developed in many countries and
more than 500 major cities in the world over the past decade. In this paper, we
discuss a large-scale bike-sharing system under Markovian environment, and
propose a mean-field matrix-analytic method in the study of bike-sharing
systems through combining the mean-field theory with the time-inhomogeneous
queues as well as the nonlinear QBD processes. Firstly, we establish an
empirical measure process to express the states of this bike-sharing system.
Secondly, we apply the mean-field theory to establishing a time-inhomogeneous
MAP(t)/MAP(t)/1/K+2L+1 queue, and then to setting up a system of mean-field
equations. Thirdly, we use the martingale limit theory to show the asymptotic
independence of this bike-sharing system, and further analyze the limiting
interchangeability as N goes to infinity and t goes to infinity. Based on this,
we discuss and compute the fixed point in terms of a nonlinear QBD process.
Finally, we analyze performance measures of this bike-sharing system, such as,
the mean of stationary bike number at any station and the stationary
probability of problematic stations. Furthermore, we use numerical examples to
show how the performance measures depend on the key parameters of this
bike-sharing system. We hope the methodology and results of this paper are
applicable in the study of more general large-scale bike-sharing systems.


title: Informative Path Planning and Mapping with Multiple UAVs in Wind Fields

abstract:
  Informative path planning (IPP) is used to design paths for robotic sensor
platforms to extract the best/maximum possible information about a quantity of
interest while operating under a set of constraints, such as the dynamic
feasibility of vehicles. The key challenges of IPP are the strong coupling in
multiple layers of decisions: the selection of locations to visit, the
allocation of sensor platforms to those locations; and the processing of the
gathered information along the paths. This paper presents a systematic
procedure for IPP and environmental mapping using multiple UAV sensor
platforms. It (a) selects the best locations to observe, (b) calculates the
cost and finds the best paths for each UAV, and (c) estimates the measurement
value within a given region using the Gaussian process (GP) regression
framework. An illustrative example of RF intensity field mapping is presented
to demonstrate the validity and applicability of the proposed approach.


title:
Jupiter's Para-H$_2$ Distribution from SOFIA/FORCAST and Voyager/IRIS
  17-37 $\mu$m Spectroscopy

abstract:
  Spatially resolved maps of Jupiter's far-infrared 17-37 $\mu$m
hydrogen-helium collision-induced spectrum were acquired by the FORCAST
instrument on the Stratospheric Observatory for Infrared Astronomy (SOFIA) in
May 2014. Spectral scans in two grisms covered the broad S(0) and S(1)
absorption lines, in addition to contextual imaging in eight broad-band filters
(5-37 $\mu$m) with spatial resolutions of 2-4". The spectra were inverted to
map the zonal-mean temperature and para-H$_2$ distribution ($f_p$, the fraction
of the para spin isomer with respect to the ortho spin isomer) in Jupiter's
upper troposphere (the 100-700 mbar range). We compared these to a reanalysis
of Voyager-1 and -2 IRIS spectra covering the same spectral range. Para-H$_2$
increases from equator to pole, with low-$f_p$ air at the equator representing
sub-equilibrium conditions (i.e., less para-H$_2$ than expected from thermal
equilibration), and high-$f_p$ air and possible super-equilibrium at higher
latitudes. In particular, we confirm the continued presence of a region of
high-$f_p$ air at high northern latitudes discovered by Voyager/IRIS, and an
asymmetry with generally higher $f_p$ in the north than in the south. We note
that existing collision-induced absorption databases lack opacity from
(H$_2$)$_2$ dimers, leading to under-prediction of the absorption near the S(0)
and S(1) peaks. There appears to be no spatial correlation between para-H$_2$
and tropospheric ammonia, phosphine and cloud opacity derived from Voyager/IRIS
at mid-infrared wavelengths (7-15 $\mu$m). We note, however, that para-H$_2$
tracks the similar latitudinal distribution of aerosols within Jupiter's upper
tropospheric and stratospheric hazes observed in reflected sunlight, suggesting
that catalysis of hydrogen equilibration within the hazes (and not the main
clouds) may govern the equator-to-pole gradient. [Abridged]


title: On a realization of $\{\beta\}$-expansion in QCD

abstract:
  We suggest a simple algebraic approach to fix the elements of the $\{ \beta
\}$-expansion for renormalization group invariant quantities, which uses
additional degrees of freedom. The approach is discussed in detail for N$^2$LO
calculations in QCD with the MSSM gluino -- an additional degree of freedom. We
derive the formulae of the $\{ \beta \}$-expansion for the nonsinglet Adler
$D$-function and Bjorken polarized sum rules in the actual N$^3$LO within this
quantum field theory scheme with the MSSM gluino and the scheme with the second
additional degree of freedom. We discuss the properties of the $\{ \beta
\}$-expansion for higher orders considering the N$^4$LO as an example.


title: Spectral analysis of the sdO standard star Feige 34

abstract:
  We present our current work on the spectral analysis of the hot sdO star
Feige 34. We combine high S/N optical spectra and fully-blanketed non-LTE model
atmospheres to derive its fundamental parameters (Teff, log g) and helium
abundance. Our best fits indicate Teff =63 000 K, log g=6.0 and log
N(He)/N(H)=-1.8. We also use available ultraviolet spectra (IUE and FUSE) to
measure metal abundances. We find the star to be enriched in iron and nickel by
a factor of ten with respect to the solar values, while lighter elements have
subsolar abundances. The FUSE spectrum suggests that the spectral lines could
be broadened by rotation.


title: Miyamoto involutions in axial algebras of Jordan type half

abstract:
  Nonassociative commutative algebras $A$ generated by idempotents $e$ whose
adjoint operators ${\rm ad}_e\colon A \rightarrow A$, given by $x \mapsto xe$,
are diagonalizable and have few eigenvalues are of recent interest. When
certain fusion (multiplication) rules between the associated eigenspaces are
imposed, the structure of these algebras remains rich yet rather rigid. For
example vertex operator algebras give rise to such algebras. The connection
between the Monster algebra and Monster group extends to many axial algebras
which then have interesting groups of automorphisms.
  Axial algebras of Jordan type $\eta$ are commutative algebras generated by
idempotents whose adjoint operators have a minimal polynomial dividing
$(x-1)x(x-\eta)$, where $\eta \notin \{0,1\}$ is fixed, with well-defined and
restrictive fusion rules. The case of $\eta \neq \frac{1}{2}$ was thoroughly
analyzed by Hall, Rehren, and Shpectorov in a recent paper, in which axial
algebras were introduced. Here we focus on the case where $\eta=\frac{1}{2}$,
which is much less understood and is of a different nature.


title: Spatial Dynamics of Urban Growth Based on Entropy and Fractal Dimension

abstract:
  The fractal dimension growth of urban form can be described with sigmoid
functions such as logistic function due to squashing effect. The sigmoid curves
of fractal dimension suggest a type of spatial replacement dynamics of urban
evolution. How to understand the underlying rationale of the fractal dimension
curves is a pending problem. This study is based on two previous findings.
First, normalized fractal dimension proved to equal normalized spatial entropy;
second, a sigmoid function proceeds from an urban-rural interaction model.
Defining urban space-filling measurement by spatial entropy, and defining rural
space-filling measurement by information gain, we can construct a new
urban-rural interaction and coupling model. From this model, we can derive the
logistic equation of fractal dimension growth strictly. This indicates that
urban growth results from the unity of opposites between spatial entropy
increase and information increase. In a city, an increase in spatial entropy is
accompanied by a decrease in urban land availability. An inference is that
urban growth struggles between the force of urban space-filling and the force
of urban space-saving. This work presents a set of urban models of spatial
dynamics, which help us understand urban evolution from the angle of view of
entropy and fractals.


title: Analysis of ionic conductance of carbon nanotubes

abstract:
  We use space-charge (SC) theory (also called the capillary pore model) to
describe the ionic conductance, $G$, of charged carbon nanotubes (CNTs). Based
on the reversible adsorption of hydroxyl ions to CNT pore walls, we use a
Langmuir isotherm for surface ionization and make calculations as function of
pore size, salt concentration $c$, and pH. Using realistic values for surface
site density and pK, SC theory well describes published experimentally data on
the conductance of CNTs. At extremely low salt concentration, when the electric
potential becomes uniform across the pore, and surface ionization is low, we
derive the scaling $G\sim \sqrt{c}$, while for realistic salt concentrations,
SC theory does not lead to a simple power law for $G(c)$.


title: An Euler-Poincar\'e formula for depth zero Bernstein projector

abstract:
  Work of Bezrukavnikov--Kazhdan--Varshavsky uses an equivariant system of
trivial idempotents of Moy--Prasad groups to obtain an Euler--Poincar\'e
formula for the r--depth Bernstein projector. We establish an Euler--Poincar\'e
formula for the projector to an individual depth zero Bernstein component in
terms of an equivariant system of Peter--Weyl idempotents of parahoric
subgroups P associated to a block of the reductive quotient of P.


title: On the Schertz conjecture

abstract:
  Schertz conjectured that every finite abelian extension of imaginary
quadratic fields can be generated by the norm of the Siegel-Ramachandra
invariants. We shall present a conditional proof of his conjecture by means of
the characters on class groups and the second Kronecker limit formula.


title: Spatial Analysis of Cities Using Renyi Entropy and Fractal Parameters

abstract:
  The spatial distributions of cities fall into two groups: one is the simple
distribution with characteristic scale (e.g. exponential distribution), and the
other is the complex distribution without characteristic scale (e.g. power-law
distribution). The latter belongs to scale-free distributions, which can be
modeled with fractal geometry. However, fractal dimension is not suitable for
the former distribution. In contrast, spatial entropy can be used to measure
any types of urban distributions. This paper is devoted to generalizing
multifractal parameters by means of dual relation between Euclidean and fractal
geometries. The main method is mathematical derivation and empirical analysis,
and the theoretical foundation is the discovery that the normalized fractal
dimension is equal to the normalized entropy. Based on this finding, a set of
useful spatial indexes termed dummy multifractal parameters are defined for
geographical analysis. These indexes can be employed to describe both the
simple distributions and complex distributions. The dummy multifractal indexes
are applied to the population density distribution of Hangzhou city, China. The
calculation results reveal the feature of spatio-temporal evolution of
Hangzhou's urban morphology. This study indicates that fractal dimension and
spatial entropy can be combined to produce a new methodology for spatial
analysis of city development.


title:
A Novel Nanoporous Graphite Based on Graphynes: First Principles
  Structure and Carbon Dioxide Preferential Physisorption

abstract:
  Ubiquitous graphene is a stricly 2D material representing an ideal adsorbing
platform due to its large specific surface area as well as its mechanical
strength and resistance to both thermal and chemical stresses. However,
graphene as a bulk material has the tendency to form irreversible agglomerates
leading to 3D graphitic structures with a significant decrease of the area
available for adsorption and no room for gas intercalation. In this paper a
novel nanoporous graphite formed by graphtriyne sheets is introduced: its 3D
structure is theoretically assessed by means of electronic structure and
molecular dynamics computations within the DFT level of theory. It is found
that the novel layered carbon allotrope is almost as compact as pristine
graphite but the inherent porosity of the 2D graphyne sheets and its relative
stacking leads to nanochannels that cross the material and whose sub-nanometer
size could allow the diffusion and storage of gas species. A molecular
prototype of the nanochannel is used to accurately determine first principles
adsorption energies and enthalpies for CO2, N2, H2O and H2 within the pores.
The proposed porous graphite presents no significant barrier for gas diffusion
and it shows a high propensity for CO2 physisorption with respect to the other
relevant components in both pre- and post-combustion gas streams.


title:
Nash-Peering: A New Techno-Economic Framework for Internet
  Interconnections

abstract:
  The current framework of Internet interconnections, based on transit and
settlement-free peering relations, has systemic problems that often cause
peering disputes. We propose a new techno-economic interconnection framework
called Nash-Peering, which is based on the principles of Nash Bargaining in
game theory and economics. Nash-Peering constitutes a radical departure from
current interconnection practices, providing a broader and more economically
efficient set of interdomain relations. In particular, the direction of payment
is not determined by the direction of traffic or by rigid customer-provider
relationships but based on which AS benefits more from the interconnection. We
argue that Nash-Peering can address the root cause of various types of peering
disputes.


title:
Computationally Secure Optical Transmission Systems with Optical
  Encryption at Line Rate

abstract:
  We propose a novel system for optical encryption based on an optical XOR and
optical Linear Feedback Shift Register (oLFSRs). Though we choose LFSR for its
ability to process optical signals at line rate, we consider the fact that it
offers no cryptographic security. To address the security shortfall, we propose
implementation of parallel oLFSRs, whereby the resulting key-stream at line
rate is controlled electronically by a nonlinear random number generator at
speeds much lower than the optical line rate, which makes the system
practically relevant. The analysis of computational security shows that the
proposed system is secure against wiretapping and can be engineered with the
state of the art optical components.


title:
Extensive degeneracy, Coulomb phase and magnetic monopoles in an
  artificial realization of the square ice model

abstract:
  Artificial spin ice systems have been introduced as a possible mean to
investigate frustration effects in a well-controlled manner by fabricating
lithographically-patterned two-dimensional arrangements of interacting magnetic
nanostructures. This approach offers the opportunity to visualize
unconventional states of matter, directly in real space, and triggered a wealth
of studies at the frontier between nanomagnetism, statistical thermodynamics
and condensed matter physics. Despite the strong efforts made these last ten
years to provide an artificial realization of the celebrated square ice model,
no simple geometry based on arrays of nanomagnets succeeded to capture the
macroscopically degenerate ground state manifold of the corresponding model.
Instead, in all works reported so far, square lattices of nanomagnets are
characterized by a magnetically ordered ground state consisting of local
flux-closure configurations with alternating chirality. Here, we show
experimentally and theoretically, that all the characteristics of the square
ice model can be observed if the artificial square lattice is properly
designed. The spin configurations we image after demagnetizing our arrays
reveal unambiguous signatures of an algebraic spin liquid state characterized
by the presence of pinch points in the associated magnetic structure factor.
Local excitations, i.e. classical analogues of magnetic monopoles, are found to
be free to evolve in a massively degenerated, divergence-free vacuum. We thus
provide the first lab-on-chip platform allowing the investigation of collective
phenomena, including Coulomb phases and ice-like physics.


title:
Some remarks on the differences between ordinates of consecutive zeta
  zeros

abstract:
  If $0 < \gamma_1 \le \gamma_2 \le \gamma_3 \le \ldots$ denote ordinates of
complex zeros of the Riemann zeta-function $\zeta(s)$, then several results
involving the maximal order of $\gamma_{n+1}-\gamma_n$ and the sum $$
\sum_{0<\gamma_n\le T}{(\gamma_{n+1}-\gamma_n)}^k \qquad(k>0) $$ are proved.


title: Interactions in Higher-Spin Gravity: a Holographic Perspective

abstract:
  This thesis is an elaboration of recent results on the holographic
re-construction of metric-like interactions in higher-spin gauge theories on
anti-de Sitter space (AdS), employing their conjectured holographic duality
with free conformal field theories (CFTs). After reviewing the general approach
and establishing the necessary intermediate results, we extract explicit
expressions for the complete cubic action on AdS$_{d+1}$ and the quartic
self-interaction of the scalar on AdS$_4$ for the type A minimal bosonic
higher-spin theory from the three- and four- point correlation functions of
single-trace operators in the free scalar $O\left(N\right)$ vector model. For
this purpose tools were developed to evaluate tree-level three-point Witten
diagrams involving fields of arbitrary integer spin and the conformal partial
wave expansions of tree-level four-point Witten diagrams, which are underpinned
by the ambient space formulation of AdS space and CFT. We also discuss the
implications of the holographic duality on the locality properties of
interactions in higher-spin gauge theories.


title: Towards a theory of superplasticity

abstract:
  This work deals with an investigation of general principles of
superplasticity (SP) in deformed materials. It is shown that a non-linear, wave
plastic deformation is the basic process for all plastic deformation phenomena,
it makes an individual contribution into these phenomena, allows describing
them from the same standpoints, and offers a way to follow the relationship
between the physics of defects and the mechanics of plasticity. It is to be
noted that macro and meso defects - discontinuities in the vector fields of
macro and meso elastic displacements, are no less fundamental than are the
microdefects - dislocations and disclinations, it is the latter which form the
process of localized macrodeformation. General mechanisms of this process are
analyzed in this study. Constitutive equation of superplastic state is
obtained, which relates the strain rate, its rotational modes, local
irreversible stresses, temperature, and density of heat and mass transfer.
Special cases and their derived relations are analyzed. It is shown that SP is
determined by plastic equilibrium concurrent with the composition and structure
fluctuations. An expression is obtained for the superplastic flow velocity,
containing three terms: velocity of wave plastic macroprocess, increased by
fluctuations, velocity prescribed by the gradient of external sources
(diffusion, etc.), and velocity of the delayed intragranular slip. It should be
noted that transformation is a characteristic and necessary feature of SP flow.
In the absence of transformations, deformation occurs via creep. Fragmentation
of the deforming region and grain-boundary sliding (GBS) are discussed and so
are their mechanisms and characteristic features. Formulas are derived for the
strain rate under conditions of GBS and the reasons for its non-monotonic
dependence on grain size, applied stresses and temperature are analyzed.


title: A construction of dualizing categories by tensor products of categories

abstract:
  It is shown that the idempotent completion of the additive hull of the tensor
product of the residue category of the category of paths of a locally finite
quiver modulo an admissible ideal and a dualizing category is dualizing.
Furthermore, the category of finitely presented functors over such tensor
product category is dualizing and has almost split sequences. As applications,
the categories of all kinds of complexes are proved to have almost split
sequences.


title:
Observations of Ellerman bomb emission features in He I D3 and He I
  10830 {\AA}

abstract:
  Context. Ellerman bombs (EBs) are short-lived emission features,
characterized by extended wing emission in hydrogen Balmer lines. Until now, no
distinct signature of EBs has been found in the He I 10830 {\AA} line, and
conclusive observations of EBs in He I D 3 have never been reported. Aims. We
aim to study the signature of EBs in neutral helium triplet lines. Methods. The
observations consist of 10 consecutive SST/TRIPPEL raster scans close to the
limb, featuring the H$\beta$, He I D3 and He I 10830 {\AA} spectral regions. We
also obtained raster scans with IRIS and make use of the SDO/AIA 1700 {\AA}
channel. We use Hazel to invert the neutral helium triplet lines. Results.
Three EBs in our data show distinct emission signatures in neutral helium
triplet lines, most prominently visible in the He I D3 line. The helium lines
have two components: a broad and blue-shifted emission component associated
with the EB, and a narrower absorption component formed in the overlying
chromosphere. One of the EBs in our data shows evidence of strong velocity
gradients in its emission component. The emission component of the other two
EBs could be fitted using a constant slab. Our analysis hints towards thermal
Doppler motions having a large contribution to the broadening for helium and
IRIS lines. We conclude that the EBs must have high temperatures to exhibit
emission signals in neutral helium triplet lines. An order of magnitude
estimate places our observed EBs in the range of $T\sim 2\cdot 10^4-10^5$ K.


title:
Bridging the gap between atomistic and macroscopic models of homogeneous
  nucleation

abstract:
  Macroscopic theories of nucleation such as classical nucleation theory
envision that clusters of the bulk stable phase form inside the bulk metastable
phase. Molecular dynamics simulations are often used to elucidate nucleation
mechanisms, by capturing the microscopic configurations of all the atoms. In
this letter, we introduce a thermodynamic model that links macroscopic theories
and atomic-scale simulations and thus provide a simple and elegant framework
for testing the limits of classical nucleation theory.


title:
Robustness analysis of spatiotemporal models in the presence of
  extrinsic fluctuations

abstract:
  We analyze the governing partial differential equations of a model of
pole-to-pole oscillations of the MinD protein in a bacterial cell. The
sensitivity to extrinsic noise in the parameters of the model is explored. Our
analysis shows that overall, the oscillations are robust to extrinsic
perturbations in the sense that small perturbations in reaction coefficients
result in small differences in the frequency and in the amplitude. However, a
combination of analysis and simulation also reveals that the oscillations are
more sensitive to some extrinsic time-scales than to others.


title:
An Iterative Approach for Time Integration Based on Discontinuous
  Galerkin Methods

abstract:
  We present a new class of iterative schemes for solving initial value
problems (IVP) based on discontinuous Galerkin (DG) methods. Starting from the
weak DG formulation of an IVP, we derive a new iterative method based on a
preconditioned Picard iteration. Using this approach, we can systematically
construct explicit, implicit and semi-implicit schemes with arbitrary order of
accuracy. We also show that the same schemes can be constructed by solving a
series of correction equations based on the DG weak formulation. The accuracy
of the schemes is proven to be $\min\{2p+1, K+1\}$ with $p$ the degree of the
DG polynomial basis and $K$ the number of iterations. The stability is explored
numerically; we show that the implicit schemes are $A$-stable at least for $0
\leq p \leq 9$. Furthermore, we combine the methods with a multilevel strategy
to accelerate their convergence speed. The new multilevel scheme is intended to
provide a flexible framework for high order space-time discretizations and to
be coupled with space-time multigrid techniques for solving partial
differential equations (PDEs). We present numerical examples for ODEs and PDEs
to analyze the performance of the new methods. Moreover, the newly proposed
class of methods, due to its structure, is also a competitive and promising
candidate for parallel in time algorithms such as Parareal, PFASST, multigrid
in time, etc.


title:
Controlling a self-organizing system of individuals guided by a few
  external agents -- particle description and mean-field limit

abstract:
  Optimal control of large particle systems with collective dynamics by few
agents is a subject of high practical importance (e.g. in evacuation dynamics),
but still limited mathematical basis. In particular the transition from
discrete optimal control to a continuum setting as the number of particles
tends to infinity is by far not fully understood. In this paper we contribute
to this issue by studying a canonical model of controlling an interacting
particle system into a certain spatial region by repulsive forces from few
external agents, which might be interpreted as shepherd dogs leading sheep to
their home.
  We discuss the appropriate modelling of such a problem and the associated
optimality systems, providing some connections between the Lagrange multipliers
in the discrete and continuum setting. As control strategies we investigate an
Instantaneous Control and a global Optimal Control approach.
  The solutions of a family of control problems for the particle system with
external agents are numerically compared to the mean-field controls as the
number of particles tends to infinity. In both cases, this leads to a high
dimensional phase space requiring tailored optimization strategies. All control
problems arising are solved using adjoint information to compute the descent
directions. The numerical results indicate the convergence of controls for both
optimization strategies.


title: Mobility Map Computations for Autonomous Navigation using an RGBD Sensor

abstract:
  In recent years, the numbers of life-size humanoids as well as their mobile
capabilities have steadily grown. Stable walking motion and control for
humanoid robots are active fields of research. In this scenario an open
question is how to model and analyse the scene so that a motion planning
algorithm can generate an appropriate walking pattern. This paper presents the
current work towards scene modelling and understanding, using an RGBD sensor.
The main objective is to provide the humanoid robot iCub with capabilities to
navigate safely and interact with various parts of the environment. In this
sense we address the problem of traversability analysis of the scene, focusing
on classification of point clouds as a function of mobility, and hence walking
safety.


title:
A Study of Factuality, Objectivity and Relevance: Three Desiderata in
  Large-Scale Information Retrieval?

abstract:
  Much of the information processed by Information Retrieval (IR) systems is
unreliable, biased, and generally untrustworthy [1], [2], [3]. Yet, factuality
& objectivity detection is not a standard component of IR systems, even though
it has been possible in Natural Language Processing (NLP) in the last decade.
Motivated by this, we ask if and how factuality & objectivity detection may
benefit IR. We answer this in two parts. First, we use state-of-the-art NLP to
compute the probability of document factuality & objectivity in two TREC
collections, and analyse its relation to document relevance. We find that
factuality is strongly and positively correlated to document relevance, but
objectivity is not. Second, we study the impact of factuality & objectivity to
retrieval effectiveness by treating them as query independent features that we
combine with a competitive language modelling baseline. Experiments with 450
TREC queries show that factuality improves precision >10% over strong
baselines, especially for uncurated data used in web search; objectivity gives
mixed results. An overall clear trend is that document factuality & objectivity
is much more beneficial to IR when searching uncurated (e.g. web) documents vs.
curated (e.g. state documentation and newswire articles). To our knowledge,
this is the first study of factuality & objectivity for back-end IR,
contributing novel findings about the relation between relevance and
factuality/objectivity, and statistically significant gains to retrieval
effectiveness in the competitive web search task.


title: Disentanglements of corank 2 map-germs: two examples

abstract:
  We compute the homology of the multiple point spaces of stable perturbations
of two germs $(\mathbb{C}^n,0)\to (\mathbb{C}^{n+1},0)$ of corank 2, one with
$n=3$ and one with $n=5$. We use a variety of techniques based on the image
computing spectral sequence ICSS. We provide a reasonably detailed introduction
to the ICSS, including some low-dimensional examples of its use. The paper is
partly expository.


title: Formulas for Jacobi forms and generalized Frobenius partitions

abstract:
  Since their introduction by Andrews, generalized Frobenius partitions have
interested a number of authors, many of whom have worked out explicit formulas
for their generating functions in specific cases. This has uncovered
interesting combinatorial structure and led to proofs of a number of
congruences. In this paper, we show how Andrews' generating functions can be
cast in the framework of Eichler and Zagier's Jacobi forms. This reformulation
allows us to compute explicit formulas for the generalized Frobenius partition
generating functions (and in fact provides formulas for further functions of
potential combinatorial interest), and it leads to a recursion formula to
calculate them in terms of infinite $q$-products.


title: Light sterile neutrinos and pseudoscalar interactions in cosmology

abstract:
  The Short BaseLine (SBL) neutrino oscillations anomalies hint at the presence
of a sterile neutrino with a mass of around 1 eV. However, such neutrino is
highly incompatible with the cosmological data, in particular from the Cosmic
Microwave Background (CMB), if no new physics is assumed. An interesting
possibility for reconciling the 1 eV sterile neutrino presence in cosmology is
related to the existence of a new pseudoscalar interaction. If the sterile
neutrinos experience such a pseudoscalar interaction, the cosmological analyses
of the full CMB data prefer a sterile neutrino mass that is fully compatible
with the SBL determinations. The additional interaction allows to obtain also
an improved compatibility of the cosmological predictions with the local
measurements of the Hubble parameter.


title:
A Decision Procedure for String Logic with Equations, Regular Membership
  and Length Constraints

abstract:
  In this paper, we consider the satisfiability problem for string logic with
equations, regular membership and Presburger constraints over length functions.
The difficulty comes from multiple occurrences of string variables making
state-of-the-art algorithms non-terminating. Our main contribution is to show
that the satisfiability problem in a fragment where no string variable occurs
more than twice in an equation is decidable. In particular, we propose a
semi-decision procedure for arbitrary string formulae with word equations,
regular membership and length functions. The essence of our procedure is an
algorithm to enumerate an equivalent set of solvable disjuncts for the formula.
We further show that the algorithm always terminates for the aforementioned
decidable fragment. Finally, we provide a complexity analysis of our decision
procedure to prove that it runs, in the worst case, in factorial time.


title:
First observation of a reactor-status effect on the beta+ decay rate of
  22Na

abstract:
  In the search for an electron antineutrino detection method with sensitivity
below the 1.8 MeV threshold for the inverse beta decay reaction, beta decay
counting experiments with ca. 3 kBq 22Na and 60Co sources were conducted at
unit #1 (2.775 GW_th) of the Koeberg Nuclear Power Station in South Africa. The
setup consisted of one NaI crystal to measure de-excitation and annihilation
photons associated with beta decay. Its volume and well shape were chosen to
use coincidence summing in order to differentiate between electron capture and
beta+ emission in 22Na. The setup was shielded from the reactor core by 8 m of
uninterrupted concrete. Background radiation, responsible for ca. 1% of the
total countrate with either source, increased by merely 3% when the reactor
status changed from OFF to ON. Normalized countrates of three energy
regions-of-interest (TOT, MED, HI) were parameterized to jointly describe the
time dependence of two instrumental effects and a reactor-status step function
in a least-squares regression analysis. With the 22Na source, the fractional
countrate changes in the step from reactor OFF to ON were: (delA/A)_TOT =
[-3.02 +- 0.14(stat) +- 0.07(syst)] x 10^-4, (delA/A)_MED = [+1.44 +-
0.42(stat) +- 0.07(syst)] x 10^-4, and (delA/A)_HI = [-2.70 +- 0.26(stat) +-
0.04(syst)] x 10^-4. The uncertainty budget is incomplete because it does not
contain the possible influence from environmental factors and the finite
stability of the MCA clock-oscillator. No reactor-status dependence was
observed with the 60Co source. The corresponding cross sections are [1.55 +-
0.07(stat)] x 10^-25 cm^2 for EC + beta+ decay in 22Na and [0.5 +- 1.5(stat)] x
10^-26 cm^2 for beta- decay of 60Co. The negative sign for TOT and HI activity
changes in 22Na points to an antineutrino related interference effect on the
beta+ decay of 22Na and rules out reactor neutron induced reactions.


title: Ground-based Transit Observation of the Habitable-zone Super-Earth K2-3d

abstract:
  We report the first ground-based transit observation of K2-3d, a 1.5 R_Earth
planet supposedly within the habitable zone around a bright M-dwarf host star,
using the Okayama 188 cm telescope and the multi(grz)-band imager MuSCAT.
Although the depth of the transit (0.7 mmag) is smaller than the photometric
precisions (1.2, 0.9, and 1.2 mmag per 60 s for the g, r, and z bands,
respectively), we marginally but consistently identify the transit signal in
all three bands, by taking advantage of the transit parameters from K2, and by
introducing a novel technique that leverages multi-band information to reduce
the systematics caused by second-order extinction. We also revisit previously
analyzed Spitzer transit observations of K2-3d to investigate the possibility
of systematic offsets in transit timing, and find that all the timing data can
be explained well by a linear ephemeris. We revise the orbital period of K2-3d
to be 44.55612 \pm 0.00021 days, which corrects the predicted transit times for
2019, i.e., the era of the James Webb Space Telescope, by \sim80 minutes. Our
observation demonstrates that (1) even ground-based, 2 m class telescopes can
play an important role in refining the transit ephemeris of small-sized,
long-period planets, and that (2) a multi-band imager is useful to reduce the
systematics of atmospheric origin, in particular for bluer bands and for
observations conducted at low-altitude observatories.


title: The High Energy Radiation Pattern from BFKLex

abstract:
  We discuss a recent study on high-energy jet production in the multi-Regge
limit done with the use of the Monte Carlo event generator BFKLex which
includes collinear improvements in the form of double-log contributions. We
will show results for the average transverse momentum and azimuthal angle of
the final state jets when at least one of them is very forward in rapidity and
another one is very backward. We also discuss the introduction of a new
observable which accounts for the average rapidity ratio among subsequent
emissions.


title: Commuting Hopf-Galois Structures on a Separable Extension

abstract:
  Let $ L/K $ be a finite separable extension of local or global fields in any
characteristic, let $ H_{1}, H_{2} $ be two Hopf algebras giving Hopf-Galois
structures on the extension, and suppose that the actions of $ H_{1}, H_{2} $
on $ L $ commute. We show that a fractional ideal $ {\mathfrak B} $ of $ L $ is
free over its associated order in $ H_{1} $ if and only if it is free over its
associated order in $ H_{2} $. We also study which properties these associated
orders share.


title: On Correlated-noise Analyses Applied To Exoplanet Light Curves

abstract:
  Time-correlated noise is a significant source of uncertainty when modeling
exoplanet light-curve data. A correct assessment of correlated noise is
fundamental to determine the true statistical significance of our findings.
Here we review three of the most widely used correlated-noise estimators in the
exoplanet field, the time-averaging, residual-permutation, and
wavelet-likelihood methods. We argue that the residual-permutation method is
unsound in estimating the uncertainty of parameter estimates. We thus recommend
to refrain from this method altogether. We characterize the behavior of the
time averaging's rms-vs.-bin-size curves at bin sizes similar to the total
observation duration, which may lead to underestimated uncertainties. For the
wavelet-likelihood method, we note errors in the published equations and
provide a list of corrections. We further assess the performance of these
techniques by injecting and retrieving eclipse signals into synthetic and real
Spitzer light curves, analyzing the results in terms of the relative-accuracy
and coverage-fraction statistics. Both the time-averaging and
wavelet-likelihood methods significantly improve the estimate of the eclipse
depth over a white-noise analysis (a Markov-chain Monte Carlo exploration
assuming uncorrelated noise). However, the corrections are not perfect, when
retrieving the eclipse depth from Spitzer datasets, these methods covered the
true (injected) depth within the 68\% credible region in only $\sim$45--65\% of
the trials. Lastly, we present our open-source model-fitting tool, Multi-Core
Markov-Chain Monte Carlo ({MC$^3$}). This package uses Bayesian statistics to
estimate the best-fitting values and the credible regions for the parameters
for a (user-provided) model. {MC$^3$} is a Python/C code, available at
https://github.com/pcubillos/MCcubed.


title:
Thermalization and Return to Equilibrium on Finite Quantum Lattice
  Systems

abstract:
  Thermal states are the bedrock of statistical physics. Nevertheless, when and
how they actually arise in closed quantum systems is not fully understood. We
consider this question for systems with local Hamiltonians on finite quantum
lattices. In a first step, we show that states with exponentially decaying
correlations equilibrate after a quantum quench. Then we show that the
equilibrium state is locally equivalent to a thermal state, provided that the
free energy of the equilibrium state is sufficiently small and the thermal
state has exponentially decaying correlations. As an application, we look at a
related important question: When are thermal states stable against noise? In
other words, if we locally disturb a closed quantum system in a thermal state,
will it return to thermal equilibrium? We rigorously show that this occurs when
the correlations in the thermal state are exponentially decaying. All our
results come with finite-size bounds, which are crucial for the growing field
of quantum thermodynamics and other physical applications.


title:
The Cross-section of Expected Returns on Penny Stocks: Are Low-hanging
  Fruits Not-so Sweet?

abstract:
  In this paper, we study the determinants of expected returns on the listed
penny stocks from two perspectives. Traditionally financial economics
literature has been devoted to study the macro and micro determinants of
expected returns on stocks (Subrahmanyam, 2010). Very few research has been
carried out on penny stocks (Liu, Rhee, & Zhang, 2011; Nofsinger & Verma,
2014). Our study is an effort to contribute more empirical evidence on penny
stocks in the emerging market context. We see the return dynamics of penny
stocks from corporate governance perspective. Issues such as shareholding
patters are considered to be of much significance when it comes to understand
the price movements. Using cross-sectional data on 167 penny stocks listed in
the National Stock Exchange of India, we show that (i) Returns of portfolio of
lower market-cap penny stocks are significantly different(higher) than that of
higher market-cap penny stocks. (ii)Returns of portfolio lower P/E stocks are
significantly different (higher) than that of higher P/E stocks. Similarly,
returns of portfolio of lower P/B stocks are significantly different (higher)
than that of higher P/B stocks, and returns of portfolio of lower priced penny
stocks are significantly different(higher) than that of higher priced penny
stocks. (iii) Trading volume differences due to alphabetism are insignificant.
(iv)Differences in returns of portfolios based on beta and shareholding
patterns are insignificant.


title: Hybrid Spectrum Sharing in mmWave Cellular Networks

abstract:
  While spectrum at millimeter wave (mmWave) frequencies is less scarce than at
traditional frequencies below 6 GHz, still it is not unlimited, in particular
if we consider the requirements from other services using the same band and the
need to license mmWave bands to multiple mobile operators. Therefore, an
efficient spectrum access scheme is critical to harvest the maximum benefit
from emerging mmWave technologies. In this paper, we introduce a new hybrid
spectrum access scheme for mmWave networks, where data is aggregated through
two mmWave carriers with different characteristics. In particular, we consider
the case of a hybrid spectrum scheme between a mmWave band with exclusive
access and a mmWave band where spectrum is pooled between multiple operators.
To the best of our knowledge, this is the first study proposing hybrid spectrum
access for mmWave networks and providing a quantitative assessment of its
benefits. Our results show that this approach provides major advantages with
respect to traditional fully licensed or fully unlicensed spectrum access
schemes, though further work is needed to achieve a more complete understanding
of both technical and non technical implications.


title: Muonic vacuum polarization correction to the bound-electron $g$-factor

abstract:
  The muonic vacuum polarization contribution to the $g$-factor of the electron
bound in a nuclear potential is investigated theoretically. The electric as
well as the magnetic loop contributions are evaluated. We found these muonic
effects to be observable in planned trapped-ion experiments with light and
medium-heavy highly charged ions. The enhancement due to the strong Coulomb
field boosts these contributions much above the corresponding terms in the
free-electron $g$-factor. Due to their magnitude, muonic vacuum polarization
terms are also significant in planned determinations of the fine-structure
constant from the bound-electron $g$-factor.


title: Improved Bounds on Sidon Sets via Lattice Packings of Simplices

abstract:
  A $ B_h $ set (or Sidon set of order $ h $) in an Abelian group $ G $ is any
subset $ \{b_0, b_1, \ldots,b_{n}\} $ of $ G $ with the property that all the
sums $ b_{i_1} + \cdots + b_{i_h} $ are different up to the order of the
summands. Let $ \phi(h,n) $ denote the order of the smallest Abelian group
containing a $ B_h $ set of cardinality $ n + 1 $. It is shown that \[ \lim_{h
\to \infty} \frac{ \phi(h,n) }{ h^n } = \frac{1}{n! \delta_L(\triangle^n)} , \]
where $ \delta_L(\triangle^n) $ is the lattice packing density of an $ n
$-simplex in Euclidean space. This determines the asymptotics exactly in cases
where this density is known ($ n \leq 3 $) and gives improved bounds on $
\phi(h,n) $ in the remaining cases. The corresponding geometric
characterization of bases of order $ h $ in finite Abelian groups in terms of
lattice coverings by simplices is also given.

categories: math.CO cs.CG cs.IT math.GR math.IT math.NT


title:
Inclusive three jet production at the LHC at 7 and 13 TeV collision
  energies

abstract:
  We discuss briefly a recent study of new observables in LHC inclusive events
with three tagged jets. One jet is in the forward direction, the second is in
the backward direction and well-separated in rapidity from the first, whereas,
the third tagged jet is to be found in more central regions of the detector.
Taking into consideration that non-tagged mini-jet emissions are allowed and
that they may be accounted for by the BFKL gluon Green function, we project the
cross sections on azimuthal-angle components and define suitable ratios based
on these projections which can provide several distinct tests of the BFKL
dynamics.


title: Tailoring Accelerating Beams in Phase Space

abstract:
  An appropriate design of wavefront will enable light fields propagating along
arbitrary trajectories thus forming accelerating beams in free space. Previous
ways of designing such accelerating beams mainly rely on caustic methods, which
start from diffraction integrals and only deal with two-dimensional fields.
Here we introduce a new perspective to construct accelerating beams in phase
space by designing the corresponding Wigner distribution function (WDF). We
find such a WDF-based method is capable of providing both the initial field
distribution and the angular spectrum in need by projecting the WDF into the
real space and the Fourier space respectively. Moreover, this approach applies
to the construction of both two- and three-dimensional fields, greatly
generalizing previous caustic methods. It may therefore open up a new route to
construct highly-tailored accelerating beams and facilitate applications
ranging from particle manipulation and trapping to optical routing as well as
material processing.


title: A Borel maximal cofinitary group

abstract: We construct a Borel maximal cofinitary group.


title: Inter-layer synchronization in non-identical multi-layer networks

abstract:
  Inter-layer synchronization is a dynamical state occurring in multi-layer
networks composed of identical nodes. The state corresponds to have all layers
synchronized, with nodes in each layer which do not necessarily evolve in
unison. So far, the study of such a solution has been restricted to the case in
which all layers had an identical connectivity structure. When layers are not
identical, the inter-layer synchronous state is no longer a stable solution of
the system. Nevertheless, when layers differ in just a few links, an
approximate treatment is still feasible, and allows one to gather information
on whether and how the system may wander around an inter-layer synchronous
configuration. We report the details of an approximate analytical treatment for
a two-layer multiplex, which results in the introduction of an extra inertial
term accounting for structural differences. Numerical validation of the
predictions highlights the usefulness of our approach, especially for small or
moderate topological differences in the intra-layer coupling. Moreover, we
identify a non-trivial relationship between the betweenness centrality of the
missing links and the intra-layer coupling strength. Finally, by the use of two
multiplexed identical layers of electronic circuits in a chaotic regime, we
study the loss of inter-layer synchronization as a function of the betweenness
centrality of the removed links.


title: The Generalized Slices of Hermitian K-Theory

abstract:
  We compute the generalized slices (as defined by Spitzweck-{\O}stv{\ae}r) of
the motivic spectrum KO (representing hermitian K-theory) in terms of motivic
cohomology and (a version of) generalized motivic cohomology, obtaining good
agreement with the situation in classical topology and the results predicted by
Markett-Schlichting. As an application, we compute the homotopy sheaves of
(this version of) generalized motivic cohomology, which establishes a version
of a conjecture of Morel.


title:
Discriminating between Thermal and Nonthermal Cosmic Relic Neutrinos
  through Annual Modulation at PTOLEMY

abstract:
  If massive neutrinos are Dirac particles, the proposed PTOLEMY experiment
will hopefully be able to discover cosmic neutrino background via $\nu^{}_e +
{^3}{\rm H} \to {^3}{\rm He} + e^-$ with a capture rate of $\Gamma^{}_{\rm D}
\approx 4~{\rm yr}^{-1}$. Recently, it has been pointed out that right-handed
components of Dirac neutrinos could also be copiously produced in the early
Universe and become an extra thermal or nonthermal ingredient of cosmic relic
neutrinos, enhancing the capture rate to $\Gamma^{}_{\rm D} \approx 5.1~{\rm
yr}^{-1}$ or $\Gamma^{}_{\rm D} \approx 6.1~{\rm yr}^{-1}$. In this work, we
investigate the possibility to distinguish between thermal and nonthermal
spectra of cosmic relic neutrinos by measuring the annual modulation of the
capture rate. For neutrino masses of $0.1~{\rm eV}$, we have found the
amplitude of annual modulation in the standard case is ${\cal M} \approx
0.05\%$, which will be increased to $0.1\%$ and $0.15\%$ in the presence of
additional thermal and nonthermal right-handed neutrinos, respectively. The
future detection of such a modulation will be helpful in understanding the
Majorana or Dirac nature of massive neutrinos.


title:
Prospects for PWNe and SNRs science with the ASTRI mini-array of
  pre-production small-sized telescopes of the Cherenkov Telescope Array

abstract:
  The development and construction of the Cherenkov Telescope Array (CTA) opens
up new opportunities for the study of very high energy (VHE, E>100 GeV)
sources. As a part of CTA, the ASTRI project, led by INAF, has one of the main
goals to develop one of the mini-arrays of CTA pre-production telescopes,
proposed to be installed at the CTA southern site. Thanks to the innovative
dual-mirror optical design of its small-sized telescopes, the ASTRI mini-array
will be characterized by a large field of view, an excellent angular
resolutioerrorn and a good sensitivity up to energies of several tens of TeV.
Pulsar wind nebulae, along with Supernova Remnants, are among the most abundant
sources that will be identified and investigated, with the ultimate goal to
move significantly closer to an understanding of the origin of cosmic rays
(CR). As part of the ongoing effort to investigate the scientific capabilities
for both CTA as a whole and the ASTRI mini-array, we performed simulations of
the Vela X region. We simulated its extended VHE gamma-ray emission using the
results of the detailed H.E.S.S. analysis of this source. We estimated the
resolving capabilities of the diffuse emission and the detection significance
of the pulsar with both CTA as a whole and the ASTRI mini-array. Moreover with
these instruments it will be possible to observe the high-energy end of SNRs
spectrum, searching for particles with energies near the cosmic-rays "knee"
(E~10^15 eV). We simulated a set of ASTRI mini-array observations for one young
and an evolved SNRs in order to test the capabilities of this instrument to
discover and study PeVatrons on the Galactic plane.


title:
A Fast Gradient Method for Nonnegative Sparse Regression with Self
  Dictionary

abstract:
  A nonnegative matrix factorization (NMF) can be computed efficiently under
the separability assumption, which asserts that all the columns of the given
input data matrix belong to the cone generated by a (small) subset of them. The
provably most robust methods to identify these conic basis columns are based on
nonnegative sparse regression and self dictionaries, and require the solution
of large-scale convex optimization problems. In this paper we study a
particular nonnegative sparse regression model with self dictionary. As opposed
to previously proposed models, this model yields a smooth optimization problem
where the sparsity is enforced through linear constraints. We show that the
Euclidean projection on the polyhedron defined by these constraints can be
computed efficiently, and propose a fast gradient method to solve our model. We
compare our algorithm with several state-of-the-art methods on synthetic data
sets and real-world hyperspectral images.


title: Chiral potential renormalized in harmonic-oscillator space

abstract:
  We renormalize the chiral effective field theory (EFT) potential in
harmonic-oscillator (HO) model space. The low energy constants (LECs) are
utilized to absorb not just the ultra-violet part of the physics due to the
cutoff, but also the infrared part due to the truncation of model space. We use
the inverse J-matrix method to reproduce the nucleon-nucleon (NN) scattering
phase shifts in the given model space. We demonstrate that by including the NLO
correction, the nucleon-nucleon scattering in the continuum could be well
reproduced in the truncated HO trap space up to laboratory energy $T_{lab}=100$
MeV with number of HO basis $n_{max}$ as small as 10. A perturbative power
counting starts at subleading order is adopted in this work, and how to extract
the perturbative contribution is demonstrated. Our work serves as the input to
perform ab-initio calculations.


title: Point Source Detection and Flux Determination with PGWave

abstract:
  One of the largest uncertainties in the Point Source (PS) studies, at
Fermi-LAT energies, is the uncertainty in the diffuse background. In general
there are two approaches for PS analysis: background-dependent methods, that
include modeling of the diffuse background, and background-independent methods.
In this work we study PGWave, which is one of the background-independent
methods, based on wavelet filtering to find significant clusters of gamma rays.
PGWave is already used in the Fermi-LAT catalog pipeline for finding candidate
sources. We test PGWave, not only for source detection, but especially to
estimate the flux without the need of a background model. We use Monte Carlo
(MC) simulation to study the accuracy of PS detection and estimation of the
flux. We present preliminary results of these MC studies.


title: Explaining unusual line profiles of SN 2006gy

abstract:
  Origin of enigmatic line profiles of extremely luminous type IIn supernova
SN~2006gy on day 96 is explored. Among conceivable possibilities the most
preferred is the model that suggests holes in the optically thick cool dense
shell (CDS). The line radiation emitted at the inner side of the opaque CDS
escapes through the holes thus producing unusual line profile with the emission
shifted redward. The holes could emerge as a result of a vigorous
Rayleigh-Taylor instability leading to the CDS fragmentation. The model light
curve with the CDS fragmentation is shown to be consistent with the SN~2006gy
bolometric light curve.


title:
Confidence regions for high-dimensional generalized linear models under
  sparsity

abstract:
  We study asymptotically normal estimation and confidence regions for
low-dimensional parameters in high-dimensional sparse models. Our approach is
based on the $\ell_1$-penalized M-estimator which is used for construction of a
bias corrected estimator. We show that the proposed estimator is asymptotically
normal, under a sparsity assumption on the high-dimensional parameter,
smoothness conditions on the expected loss and an entropy condition. This leads
to uniformly valid confidence regions and hypothesis testing for
low-dimensional parameters. The present approach is different in that it allows
for treatment of loss functions that we not sufficiently differentiable, such
as quantile loss, Huber loss or hinge loss functions. We also provide new
results for estimation of the inverse Fisher information matrix, which is
necessary for the construction of the proposed estimator. We formulate our
results for general models under high-level conditions, but investigate these
conditions in detail for generalized linear models and provide mild sufficient
conditions. As particular examples, we investigate the case of quantile loss
and Huber loss in linear regression and demonstrate the performance of the
estimators in a simulation study and on real datasets from genome-wide
association studies. We further investigate the case of logistic regression and
illustrate the performance of the estimator on simulated and real data.


title:
Improved Lower Bound on DHP: Towards the Equivalence of DHP and DLP for
  Important Elliptic Curves Used for Implementation

abstract:
  In 2004, Muzereau et al. showed how to use a reduction algorithm of the
discrete logarithm problem to Diffie-Hellman problem in order to estimate lower
bound on Diffie-Hellman problem on elliptic curves. They presented their
estimates for various elliptic curves that are used in practical applications.
In this paper, we show that a much tighter lower bound for Diffie-Hellman
problem on those curves can be achieved, if one uses the multiplicative group
of a finite field as an auxiliary group. Moreover, improved lower bound
estimates on Diffie-Hellman problem for various recommended curves are also
given which are the tightest; thus, leading us towards the equivalence of
Diffie-Hellman problem and the discrete logarithm problem for these recommended
elliptic curves.


title:
Time evolution of linearized gauge field fluctuations on a real-time
  lattice

abstract:
  Classical real-time lattice simulations play an important role in
understanding non-equilibrium phenomena in gauge theories and are used in
particular to model the prethermal evolution of heavy-ion collisions. Due to
instabilities, small quantum fluctuations on top of the classical background
may significantly affect the dynamics of the system. In this paper we argue for
the need for a numerical calculation of a system of classical gauge fields and
small linearized fluctuations in a way that keeps the separation between the
two manifest. We derive and test an explicit algorithm to solve these equations
on the lattice, maintaining gauge invariance and Gauss's law.


title: Spectral triples on $O_N$

abstract:
  We give a construction of an odd spectral triple on the Cuntz algebra
$O_{N}$, whose $K$-homology class generates the odd $K$-homology group
$K^1(O_{N})$. Using a metric measure space structure on the Cuntz-Renault
groupoid, we introduce a singular integral operator which is the formal
analogue of the logarithm of the Laplacian on a Riemannian manifold. Assembling
this operator with the infinitesimal generator of the gauge action on $O_{N}$
yields a $\theta$-summable spectral triple whose phase is finitely summable.
The relation to previous constructions of Fredholm modules and spectral triples
on $O_{N}$ is discussed.


title: Eigenvalue bounds for the signless $p$-Laplacian

abstract:
  We consider the signless $p$-Laplacian of a graph, a generalisation of the
usual signless Laplacian (the case $p=2$). We show a Perron-Frobenius property
and basic inequalites for the largest eigenvalue and provide upper and lower
bounds for the smallest eigenvalue in terms of a parameter related to the
bipartiteness. The latter result generalises bounds by Desai and Rao and,
interestingly, in the limit $p\to 1$ upper and lower bounds coincide.


title: Consistency Relation and Non-Gaussianity in a Galileon Inflation

abstract:
  We study a particular Galileon inflation in the light of Planck2015
observational data in order to constraint the model parameter space. We study
the spectrum of the primordial modes of the density perturbations by expanding
the action up to the second order in perturbations. Then we pursue by expanding
the action up to the third order and find the three point correlation functions
to find the amplitude of the non-Gaussianity of the primordial perturbations in
this setup. We study the amplitude of the non-Gaussianity both in equilateral
and orthogonal configurations and test the model with recent observational
data. Our analysis shows that for some ranges of the non-minimal coupling
parameter, the model is consistent with observation and it is also possible to
have large non-Gaussianity which would be observable by future improvements in
experiments. Moreover, we obtain the tilt of the tensor power spectrum and test
the standard inflationary consistency relation ($r=-8n_T$) against the latest
bounds from the Planck2015 dataset. We find a slight deviation from the
standard consistency relation in this setup. Nevertheless, such a deviation
seems not to be sufficiently remarkable to be detected confidently.


title:
Engineering of orbital angular momentum supermodes in coupled optical
  waveguides

abstract:
  In this work we demonstrate the existence of orbital angular momentum (OAM)
bright and dark supermodes in a three-evanescently coupled cylindrical
waveguides system. Bright and dark supermodes are characterized by their
coupling and decoupling from one of the waveguides, respectively. In addition,
we demonstrate that complex couplings between modes of different waveguides
appear naturally due to the characteristic spiral phase-front of OAM modes in
two-dimensional configurations where the waveguides are arranged forming a
triangle. Finally, by adding dissipation to the waveguide uncoupled to the dark
supermode, we are able to filter it out, allowing for the design of OAM mode
clonners and inverters.


title: Neumann Cheeger constants on graphs

abstract:
  For any subgraph of a graph, the Laplacian with Neumann boundary condition
was introduced by Chung and Yau [CY94]. In this paper, motivated by the
Riemannian case, we introduce the Cheeger constants for Neumann problems and
prove corresponding Cheeger estimates for first nontrivial eigenvalues.


title:
Explosive transitions in complex networks' structure and dynamics:
  percolation and synchronization

abstract:
  Percolation and synchronization are two phase transitions that have been
extensively studied since already long ago. A classic result is that, in the
vast majority of cases, these transitions are of the second-order type, i.e.
continuous and reversible. Recently, however, explosive phenomena have been
reported in com- plex networks' structure and dynamics, which rather remind
first-order (discontinuous and irreversible) transitions. Explosive
percolation, which was discovered in 2009, corresponds to an abrupt change in
the network's structure, and explosive synchronization (which is concerned,
instead, with the abrupt emergence of a collective state in the networks'
dynamics) was studied as early as the first models of globally coupled phase
oscillators were taken into consideration. The two phenomena have stimulated
investigations and de- bates, attracting attention in many relevant fields. So
far, various substantial contributions and progresses (including experimental
verifications) have been made, which have provided insights on what structural
and dynamical properties are needed for inducing such abrupt transformations,
as well as have greatly enhanced our understanding of phase transitions in
networked systems. Our intention is to offer here a monographic review on the
main-stream literature, with the twofold aim of summarizing the existing
results and pointing out possible directions for future research.


title: Thermality and excited state R\'enyi entropy in two-dimensional CFT

abstract:
  We evaluate one-interval R\'enyi entropy and entanglement entropy for the
excited states of two-dimensional conformal field theory (CFT) on a cylinder,
and examine their differences from the ones for the thermal state. We assume
the interval to be short so that we can use operator product expansion (OPE) of
twist operators to calculate R\'enyi entropy in terms of sum of one-point
functions of OPE blocks. We find that the entanglement entropy for highly
excited state and thermal state behave the same way after appropriate
identification of the conformal weight of the state with the temperature.
However, there exists no such universal identification for the R\'enyi entropy
in the short-interval expansion. Therefore, the highly excited state does not
look thermal when comparing its R\'enyi entropy to the thermal state one. As
the R\'enyi entropy captures the higher moments of the reduced density matrix
but the entanglement entropy only the average, our results imply that the
emergence of thermality depends on how refined we look into the entanglement
structure of the underlying pure excited state.


title:
Actuator Development at IAAT for the Cherenkov Telescope Array Medium
  Size Telescopes

abstract:
  The Cherenkov Telescope Array (CTA) will be the future observatory for TeV
gamma-ray astronomy. In order to increase the sensitivity and to extend the
energy coverage beyond the capabilities of current facilities, its design
concept features telescopes of three different size classes. Based on the
experience from H.E.S.S. phase II, the Institute for Astronomy and Astrophysics
T\"ubingen (IAAT) develops actuators for the mirror control system of the CTA
Medium Size Telescopes (MSTs). The goals of this effort are durability, high
precision, and mechanical stability under all environmental conditions. Up to
now, several revisions were developed and the corresponding prototypes were
extensively tested. In this contribution our latest design revision proposed
for the CTA MSTs are presented.


title:
FMEA Based Risk Assessment of Component Failure Modes in Industrial
  Radiography

abstract:
  Industrial radiography has its inimitable role in non-destructive
examinations. Industrial radiography devices, consisting of significantly high
activity of the radioisotopes, are operated manually by remotely held control
unit. Malfunctioning of these devices may cause potential exposure to the
operator and nearby public, and thus should be practiced under a systematic
risk control. To ensure the radiation safety, proactive risk assessment should
be implemented. Risk assessment in industrial radiography using the Failure
Modes & Effect Analysis (FMEA) for the design and operation of industrial
radiography exposure devices has been carried out in this study. Total 56
component failure modes were identified and Risk Priority Numbers (RPNs) were
assigned by the FMEA expert team, based on the field experience and reported
failure data of various components. Results shows all the identified failure
modes have RPN in the range of 04 to 216 and most of the higher RPN are due to
low detectability and high severity levels. Assessment reveals that increasing
failure detectability is a practical and feasible approach to reduce the risk
in most of the failure modes of industrial radiography devices. Actions for
reducing RPN for each failure mode have been suggested. Feasibility of FMEA for
risk assessment in industrial radiography has been established by this study


title: One valued primitives and the F. and M. Riesz theorem

abstract:
  For a non-simply connected domain Omega in C and f a holomorphic function on
Omega we prove that f admits one-valued primitives of any order in Omega, if
and only if, it extends holomorphically in the simply connected envelope of
Omega . This leads to a generalization of the F. and M. Riesz theorem.


title: A cumulative approach to quantification for sentiment analysis

abstract:
  We estimate sentiment categories proportions for retrieval within large
retrieval sets. In general, estimates are produced by counting the
classification outcomes and then by adjusting such category sizes taking into
account misclassification error matrix. However, both the accuracy of the
classifier and the precision of the retrieval produce a large number of errors
that makes difficult the application of an aggregative approach to sentiment
analysis as a reliable and efficient estimation of proportions for sentiment
categories.
  The challenge for real time analytics during retrieval is thus to overcome
misclassification errors, and more importantly, to apply sentiment
classification or any other similar post-processing analytics at retrieval
time. We present a non-aggregative approach that can be applied to very large
retrieval sets of queries.


title:
Monaural Multi-Talker Speech Recognition using Factorial Speech
  Processing Models

abstract:
  A Pascal challenge entitled monaural multi-talker speech recognition was
developed, targeting the problem of robust automatic speech recognition against
speech like noises which significantly degrades the performance of automatic
speech recognition systems. In this challenge, two competing speakers say a
simple command simultaneously and the objective is to recognize speech of the
target speaker. Surprisingly during the challenge, a team from IBM research,
could achieve a performance better than human listeners on this task. The
proposed method of the IBM team, consist of an intermediate speech separation
and then a single-talker speech recognition. This paper reconsiders the task of
this challenge based on gain adapted factorial speech processing models. It
develops a joint-token passing algorithm for direct utterance decoding of both
target and masker speakers, simultaneously. Comparing it to the challenge
winner, it uses maximum uncertainty during the decoding which cannot be used in
the past two-phased method. It provides detailed derivation of inference on
these models based on general inference procedures of probabilistic graphical
models. As another improvement, it uses deep neural networks for joint-speaker
identification and gain estimation which makes these two steps easier than
before producing competitive results for these steps. The proposed method of
this work outperforms past super-human results and even the results were
achieved recently by Microsoft research, using deep neural networks. It
achieved 5.5% absolute task performance improvement compared to the first
super-human system and 2.7% absolute task performance improvement compared to
its recent competitor.


title:
Non-vanishing cohomology classes in uniform lattices of
  $\text{SO}(n,\mathbb{H})$ and automorphic representations

abstract:
  Let $X$ denote the non-compact globally Hermitian symmetric space of type
$DIII$, namely, $\text{SO}(n,\mathbb{H})/\text{U}(n)$. Let $\Lambda$ be a
uniform torsionless lattice in $\text{SO}(n,\mathbb{H})$. In this note we
construct certain complex analytic submanifolds in the locally symmetric space
$X_\Gamma:=\Gamma\backslash \text{SO}(n,\mathbb{H})/\text{U}(n)$ for certain
finite index sub lattices $\Gamma\subset \Lambda$ and show that their dual
cohomology classes in $H^*(X_\Gamma;\mathbb{C})$ are not in the image of the
Matsushima homomorphism $H^*(X_u; \mathbb{C})\to H^*(X_\Gamma;\mathbb{C})$,
where $X_u=\text{SO}(2n)/\text{U}(n)$ is the compact dual of $X$. These
submanifold arise as sub-locally symmetric spaces which are totally geodesic,
and, when $\Lambda$ satisfies certain additional conditions, they are
non-vanishing `special cycles'. Using the fact that $X_\Lambda$ is a K\"ahler
manifold, we deduce the occurrence in $L^2(\Lambda\backslash
\text{SO}(n,\mathbb{H})$ of a certain irreducible representation
$(\mathcal{A}_\mathfrak{q}, A_\mathfrak{q})$ with non-zero multiplicity when
$n\ge 9$. The representation $\mathcal{A}_\mathfrak{q}$ is associated to a
certain $\theta$-stable parabolic subalgebra $\mathfrak{q}$ of
$\mathfrak{g}_0:=\mathfrak{so}(n,\mathbb{H})$. Denoting the smooth
$\text{U}(n)$-finite vectors of $A_{\mathfrak{q}}$ by
$A_{\mathfrak{q},\text{U}(n)}$, the representation $\mathcal{A}_\mathfrak{q}$
is characterised by the property that
$H^{p,p}(\mathfrak{g}_0\otimes\mathbb{C},\text{U}(n);
A_{\mathfrak{q},\text{U}(n)})\cong
H^{p-n+2,p-n+2}(\text{SO}(2n-2)/\text{U}(n-1);\mathbb{C}),~p\ge 0$, for $n\ge
9$.


title: Self-referential Functions

abstract:
  We introduce the concept of fractels for functions and discuss their analytic
and algebraic properties. We also consider the representation of polynomials
and analytic functions using fractels, and the consequences of these
representations in numerical analysis.


title: Discrete intrinsic localized modes in a microelectromechanical resonator

abstract:
  Intrinsic Localized Modes (ILMs) or Discrete Breathers (DBs) are produced
through a non-linear vibration localization phenomenon. While Anderson
localization is due to lattice defects, the nonlinearity of lattices provides
the basis for ILM excitation. Over the past two decades, these ILMs have been
realized in a wide range of physical systems including photonic crystals,
nonlinear atomic lattices, anti-ferromagnets, coupled Josephson junction arrays
and coupled cantilevers. This paper brings out the feasibility of exciting ILMs
in a standalone mechanical resonator. Through piezoelectric driving and optical
visualization, various intriguing features of ILMs have been recorded. The ILMs
in our system are observed as spectral bushes and their frequencies are much
lower than that of the drive frequency. The excitation of ILMs is mediated
through large amplitude instability following autoparametric excitation of a
sub-harmonic mode. The spatial prevalence of discrete ILM excitations is at
antinodes of the sub-harmonic mode. Further, the ILMs have been observed to be
time-variant and various events including attraction-repulsion (or
splitting-merging) of ILMs and hopping occur during the time evolution of ILMs.


title:
The roles of stellar feedback and galactic environment in star forming
  molecular clouds

abstract:
  Feedback from massive stars is thought to play an important role in the
evolution of molecular clouds. In this work we analyse the effects of stellar
winds and supernovae (SNe) in the evolution of two massive ($\sim
10^6\,M_\odot$) giant molecular clouds (GMCs): one gravitationally bound
collapsing cloud and one unbound cloud undergoing disruption by galactic shear.
These two clouds have been extracted from a large scale galaxy model and are
re-simulated at a spatial resolution of $\sim 0.01$ pc, including feedback from
winds, SNe, and the combined effect of both. We find that stellar winds stop
accretion of gas onto sink particles, and can also trigger star formation in
the shells formed by the winds, although the overall effect is to reduce the
global star formation rate of both clouds. Furthermore, we observe that winds
tend to escape through the corridors of diffuse gas. The effect of SNe is not
so prominent and the star formation rate is similar to models neglecting
stellar feedback. We find that most of the energy injected by the SNe is
radiated away, but overdense areas are created by multiple and concurrent SN
events especially in the most virialised cloud. Our results suggest that the
impact of stellar feedback is sensitive to the morphology of star forming
clouds, which is set by large scale galactic flows, being of greater importance
in clouds undergoing gravitational collapse.


title: Maximally symmetric stabilizer MUBs in even prime-power dimensions

abstract:
  One way to construct a maximal set of mutually unbiased bases (MUBs) in a
prime-power dimensional Hilbert space is by means of finite phase-space
methods. MUBs obtained in this way are covariant with respect to some subgroup
of the group of all affine symplectic phase-space transformations. However,
this construction is not canonical: as a consequence, many different choices of
covariance sugroups are possible. In particular, when the Hilbert space is
$2^n$ dimensional, it is known that covariance with respect to the full group
of affine symplectic phase-space transformations can never be achieved. Here we
show that in this case there exist two essentially different choices of maximal
subgroups admitting covariant MUBs. For both of them, we explicitly construct a
family of $2^n$ covariant MUBs. We thus prove that, contrary to the odd
dimensional case, maximally covariant MUBs are very far from being unique.


title:
Compressible Relativistic Magnetohydrodynamic Turbulence in
  Magnetically-Dominated Plasmas And Implications for A Strong-Coupling Regime

abstract:
  In this Letter, we report compressible mode effects on relativistic
magnetohydrodynamic (RMHD) turbulence in Poynting-dominated plasmas using
3-dimensional numerical simulations. We decomposed fluctuations in the
turbulence into 3 MHD modes (fast, slow, and Alfv\'en) following the procedure
mode decomposition in (Cho & Lazarian 2002), and analyzed their energy spectra
and structure functions separately. We also analyzed the ratio of compressible
mode to Alfv\'en mode energy with respect to its Mach number. We found the
ratio of compressible mode increases not only with the Alfv\'en Mach number but
with the background magnetization, which indicates a strong coupling between
the fast and Alfv\'en modes and appearance of a new regime of RMHD turbulence
in Poynting-dominated plasmas where the fast and Alfv\'en modes strongly
couples and cannot be separated, different from the non-relativistic MHD case.
This finding will affect particle acceleration efficiency obtained by assuming
Alfv\'enic critical balance turbulence, and will change the resulting photon
spectra by non-thermal electrons.

categories: astro-ph.HE astro-ph.SR physics.flu-dyn physics.plasm-ph


title:
Domain Adaptation with Soft-margin multiple feature-kernel learning
  beats Deep Learning for surveillance face recognition

abstract:
  Face recognition (FR) is the most preferred mode for biometric-based
surveillance, due to its passive nature of detecting subjects, amongst all
different types of biometric traits. FR under surveillance scenario does not
give satisfactory performance due to low contrast, noise and poor illumination
conditions on probes, as compared to the training samples. A state-of-the-art
technology, Deep Learning, even fails to perform well in these scenarios. We
propose a novel soft-margin based learning method for multiple feature-kernel
combinations, followed by feature transformed using Domain Adaptation, which
outperforms many recent state-of-the-art techniques, when tested using three
real-world surveillance face datasets.


title:
On the numerical study of percolation and epidemic critical properties
  in networks

abstract:
  The static properties of the fundamental model for epidemics of diseases
allowing immunity (susceptible-infected-removed model) are known to be
derivable by an exact mapping to bond percolation. Yet when performing
numerical simulations of these dynamics in a network a number of subtleties
must be taken into account in order to correctly estimate the transition point
and the associated critical properties. We expose these subtleties and identify
the different quantities which play the role of criticality detector in the two
dynamics.