title:
Production and Distribution of $^{44}$Ti and $^{56}$Ni in a
  Three-dimensional Supernova Model Resembling Cassiopeia A

abstract:
  The spatial and velocity distributions of nuclear species synthesized in the
innermost regions of core-collapse supernovae can yield important clues about
explosion asymmetries and the operation of the still disputed explosion
mechanism. Recent observations of radioactive $^{44}$Ti with high-energy
satellite telescopes (Nuclear Spectroscopic Telescope Array [NuSTAR], INTEGRAL)
have measured gamma-ray line details, which provide direct evidence of
large-scale explosion asymmetries in SN 1987A and in Cassiopeia A (Cas A) even
by mapping of the spatial brightness distribution (NuSTAR). Here we discuss a
3D simulation of a neutrino-driven explosion, using a parameterized neutrino
engine, whose $^{44}$Ti distribution is mostly concentrated in one hemisphere
pointing opposite to the neutron star (NS) kick velocity. Both exhibit
intriguing resemblance to the observed morphology of the Cas A remnant,
although neither the progenitor nor the explosion was fine-tuned for a perfect
match. Our results demonstrate that the asymmetries observed in this remnant
can, in principle, be accounted for by a neutrino-driven explosion, and that
the high $^{44}$Ti abundance in Cas A may be explained without invoking rapid
rotation or a jet-driven explosion, because neutrino-driven explosions
generically eject large amounts of high-entropy matter. The recoil acceleration
of the NS is connected to mass ejection asymmetries and is opposite to the
direction of the stronger explosion, fully compatible with the gravitational
tugboat mechanism. Our results also imply that Cas A and SN 1987A could possess
similarly "one-sided" Ti and Fe asymmetries, with the difference that Cas A is
viewed from a direction with large inclination angle to the NS motion, whereas
the NS in SN 1987A should have a dominant velocity component pointing toward
us.


title: Drying paint: from micro-scale dynamics to mechanical instabilities

abstract:
  Charged colloidal dispersions make up the basis of a broad range of
industrial and commercial products, from paints to coatings and additives in
cosmetics. During drying, an initially liquid dispersion of such particles is
slowly concentrated into a solid, displaying a range of mechanical
instabilities in response to highly variable internal pressures. Here we
summarise the current appreciation of this process by pairing an
advection-diffusion model of particle motion with a Poisson-Boltzmann cell
model of inter-particle interactions, to predict the concentration gradients
around a drying colloidal film. We then test these predictions with osmotic
compression experiments on colloidal silica, and small-angle x-ray scattering
experiments on silica dispersions drying in Hele-Shaw cells. Finally, we use
the details of the microscopic physics at play in these dispersions to explore
how two macroscopic mechanical instabilities -- shear-banding and fracture --
can be controlled.


title:
Piecewise-differentiable trajectory outcomes in mechanical systems
  subject to unilateral constraints

abstract:
  We provide conditions under which trajectory outcomes in mechanical systems
subject to unilateral constraints depend piecewise-differentiably on initial
conditions, even as the sequence of constraint activations and deactivations
varies. This builds on prior work that provided conditions ensuring existence,
uniqueness, and continuity of trajectory outcomes, and extends previous
differentiability results that applied only to fixed constraint (de)activation
sequences. We discuss extensions of our result and implications for assessing
stability and controllability.


title: Distributed Computation of Mixing Time

abstract:
  The mixing time of a graph is an important metric, which is not only useful
in analyzing connectivity and expansion properties of the network, but also
serves as a key parameter in designing efficient algorithms. We present an
efficient distributed algorithm for computing the mixing time of undirected
graphs. Our algorithm estimates the mixing time $\tau_s$ (with respect to a
source node $s$) of any $n$-node undirected graph in $O(\tau_s \log n)$ rounds.
Our algorithm is based on random walks and require very little memory and use
lightweight local computations, and work in the CONGEST model. Hence our
algorithm is scalable under bandwidth constraints and can be an helpful
building block in the design of topologically aware networks.


title: Instability of strong magnetic field and neutrino magnetic dipole moment

abstract:
  Vacuum instability of the strong electromagnetic field has been discussed
since long time ago. The instability of the strong electric field due to
creation of electron pairs is one of the examples, which is known as Schwinger
process. What matters are the coupling of particles to the electromagnetic
field and the mass of the particle to be produced. The critical electric field
for electrons in the minimal coupling is ~ m^2/e . Spin 1/2 neutral particles
but with magnetic dipole moments can interact with the electromagnetic field
through Pauli coupling. The instability of the particular vacuum under the
strong magnetic field can be formulated as the emergence of imaginary parts of
the effective potential. In this talk, the development of the imaginary part in
the effective potential as a function of the magnetic field strength is
discussed for the configurations of the uniform magnetic field and the
inhomogeneous magnetic field. Neutrinos are the lightest particle(if not photon
or gluon) in the "standard model", of which electromagnetic property is poorly
known experimentally. Recently the observation of neutrino oscillation shows
the necessity of neutrino masses. It implies that the standard model is
subjected to be modified such that non-trivial electromagnetic structure of
neutrino should be reconsidered although they are assigned to be neutral. And
the possibility of anomalous electromagnetic form factor is an open question
theoretically and experimentally. In this talk, the implication of
non-vanishing magnetic dipole moment of neutrinos is also discussed: the
instability of the strong magnetic field and the enhancement of neutrino
production in high energy collider experiments.


title:
Beyond mean-field properties of binary dipolar Bose mixtures at low
  temperatures

abstract:
  We rigorously analyze the low-temperature properties of homogeneous
three-dimensional two-component Bose mixture with dipole-dipole interaction.
For such a system the effective hydrodynamic action that governs the behavior
of low-energy excitations is derived. The infrared structure of the exact
single-particle Green's functions is obtained in terms of macroscopic
parameters, namely the inverse compressibility and the superfluid density
matrices. Within one-loop approximation we calculate the anisotropic superfluid
and condensate densities and give the beyond mean-field stability condition for
the binary dipolar Bose gas. A brief variational derivation of the coupled
equations that describe macroscopic hydrodynamics of the system in the external
non-uniform potential at zero temperature is presented.


title:
On the numerical solution of the Klein-Gordon equation by Exponential
  B-spline collocation method

abstract:
  In the present study, we solve initial boundary value problem construted on
nonlinear Klein-Gordon equation. The collocation method on exponential cubic
B-spline functions forming a set of basis for the functions defined in the same
interval is set up for the numerical approach. The efficiency and validity of
the proposed method are determined by computing the error between the numerical
and the analytical solutions. The preservation of conserved quantities is also
a good indicator of validity of the method.


title: The low-frequency radio emission in blazar PKS2155-304

abstract:
  We report radio imaging and monitoring observations in the frequency range
0.235 - 2.7 GHz during the flaring mode of PKS 2155-304, one of the brightest
BL Lac objects. The high sensitivity GMRT observations not only reveal extended
kpc-scale jet and FRI type lobe morphology in this erstwhile `extended-core'
blazar but also delineate the morphological details, thanks to its arcsec scale
resolution. The radio light curve during the end phase of the outburst measured
in 2008 shows high variability (8.5%) in the jet emission in the GHz range,
compared to the lower core variability (3.2%) seen at the lowest frequencies.
The excess of flux density with a very steep spectral index in the MHz range
supports the presence of extra diffuse emission at low frequencies. The
analysis of multi wavelength (radio/ optical/ gamma-ray) light curves at
different radio frequencies confirms the variability of the core region and
agrees with the scenario of high energy emission in gamma-rays due to inverse
Compton emission from a collimated relativistic plasma jet followed by
synchrotron emission in radio. Clearly, these results give an interesting
insight of the jet emission mechanisms in blazars and highlight the importance
of studying such objects with low frequency radio interferometers like LOFAR
and the SKA and its precursor instruments.


title:
MBE-grown 232-270 nm Deep-UV LEDs using Monolayer thin Binary GaN/AlN
  quantum heterostructures

abstract:
  Electrically injected deep ultra-violet (UV) emission is obtained using
monolayer (ML) thin GaN/AlN quantum structures as active regions. The emission
wavelength is tuned by controlling the thickness of ultrathin GaN layers with
monolayer precision using plasma assisted molecular beam epitaxy (PAMBE).
Single peaked emission spectra is achieved with narrow full width at half
maximum (FWHM) for three different light emitting diodes (LEDs) operating at
232 nm, 246 nm and 270 nm. 232 nm (5.34 eV) is the shortest EL emission
wavelength reported so far using GaN as the light emitting material and
employing polarization-induced doping.


title:
Vietnamese Named Entity Recognition using Token Regular Expressions and
  Bidirectional Inference

abstract:
  This paper describes an efficient approach to improve the accuracy of a named
entity recognition system for Vietnamese. The approach combines regular
expressions over tokens and a bidirectional inference method in a sequence
labelling model. The proposed method achieves an overall $F_1$ score of 89.66%
on a test set of an evaluation campaign, organized in late 2016 by the
Vietnamese Language and Speech Processing (VLSP) community.


title:
Acoustic Reflector Localization: Novel Image Source Reversion and Direct
  Localization Methods

abstract:
  Acoustic reflector localization is an important issue in audio signal
processing, with direct applications in spatial audio, scene reconstruction,
and source separation. Several methods have recently been proposed to estimate
the 3D positions of acoustic reflectors given room impulse responses (RIRs). In
this article, we categorize these methods as "image-source reversion", which
localizes the image source before finding the reflector position, and "direct
localization", which localizes the reflector without intermediate steps. We
present five new contributions. First, an onset detector, called the clustered
dynamic programming projected phase-slope algorithm, is proposed to
automatically extract the time of arrival for early reflections within the RIRs
of a compact microphone array. Second, we propose an image-source reversion
method that uses the RIRs from a single loudspeaker. It is constructed by
combining an image source locator (the image source direction and range (ISDAR)
algorithm), and a reflector locator (using the loudspeaker-image bisection
(LIB) algorithm). Third, two variants of it, exploiting multiple loudspeakers,
are proposed. Fourth, we present a direct localization method, the ellipsoid
tangent sample consensus (ETSAC), exploiting ellipsoid properties to localize
the reflector. Finally, systematic experiments on simulated and measured RIRs
are presented, comparing the proposed methods with the state-of-the-art. ETSAC
generates errors lower than the alternative methods compared through our
datasets. Nevertheless, the ISDAR-LIB combination performs well and has a run
time 200 times faster than ETSAC.


title: The infochemical core

abstract:
  Vocalizations and less often gestures have been the object of linguistic
research over decades. However, the development of a general theory of
communication with human language as a particular case requires a clear
understanding of the organization of communication through other means.
Infochemicals are chemical compounds that carry information and are employed by
small organisms that cannot emit acoustic signals of optimal frequency to
achieve successful communication. Here the distribution of infochemicals across
species is investigated when they are ranked by their degree or the number of
species with which it is associated (because they produce or they are sensitive
to it). The quality of the fit of different functions to the dependency between
degree and rank is evaluated with a penalty for the number of parameters of the
function. Surprisingly, a double Zipf (a Zipf distribution with two regimes
with a different exponent each) is the model yielding the best fit although it
is the function with the largest number of parameters. This suggests that the
world wide repertoire of infochemicals contains a chemical nucleus shared by
many species and reminiscent of the core vocabularies found for human language
in dictionaries or large corpora.


title: Electromagnetic shift arising from the Heisenberg-Euler dipole

abstract:
  We show that photons may be redshifted or blueshifted when interacting with
the field of an overcritical dipole, which incorporates the one-loop QED
corrections coming from vacuum polarization. Using the effective metric, it
follows that such effect depends on the polarization of the photon. The shifts,
plotted against the azimuthal angle for various values of the magnetic field,
may show an intensity comparable to the gravitational redshift for a magnetar.
To obtain these results, we have corrected previous literature.


title:
Asymptotic expansions for moments of number of comparisons used by the
  randomized quick sort algorithm

abstract:
  We calculate asymptotic expansions for the moments of number of comparisons
used by the randomized quick sort algorithm using the singularity analysis of
certain generating functions.


title: Structure of irreducibly covariant quantum channels for finite groups

abstract:
  We obtain an explicit characterization of linear maps, in particular, quantum
channels, which are covariant with respect to an irreducible representation
($U$) of a finite group ($G$), whenever $U \otimes U^c$ is simply reducible
(with $U^c$ being the contragradient representation). Using the theory of group
representations, we obtain the spectral decomposition of any such linear map.
The eigenvalues and orthogonal projections arising in this decomposition are
expressed entirely in terms of representation characteristics of the group $G$.
This in turn yields necessary and sufficient conditions on the eigenvalues of
any such linear map for it to be a quantum channel. We also obtain a wide class
of quantum channels which are irreducibly covariant by construction. For
two-dimensional irrreducible representations of the symmetric group $S(3)$, and
the quaternion group $Q$, we also characterize quantum channels which are both
irreducibly covariant and entanglement breaking.


title: Measurement of light diffusion in ZnO nanowire forests

abstract:
  Optimum design of efficient nanowire solar cells requires better
understanding of light diffusion in a nanowire array. Here we demonstrate that
our recently developed ultrafast all-optical shutter can be used to directly
measure the dwell time of light in a nanowire array. Our measurements on
disordered ZnO nanowire arrays, "nanowire forests," indicate that the photon
mean free path and the dwell time of light can be well predicted from SEM
images.


title: The coupling of Poisson sigma models to topological backgrounds

abstract:
  We extend the coupling to the topological backgrounds, recently worked out
for the 2-dimensional BF-model, to the most general Poisson sigma models. The
coupling involves the choice of a Casimir function on the target manifold and
modifies the BRST transformations. This in turn induces a change in the BRST
cohomology of the resulting theory. The observables of the coupled theory are
analyzed and their geometrical interpretation is given. We finally couple the
theory to 2-dimensional topological gravity: this is the first step to study a
topological string theory in propagation on a Poisson manifold. As an
application, we show that the gauge-fixed vectorial supersymmetry of the
Poisson sigma models has a natural explanation in terms of the theory coupled
to topological gravity.


title:
Langevin Diffusion for Population Based Sampling with an Application in
  Bayesian Inference for Pharmacodynamics

abstract:
  We propose an algorithm for the efficient and robust sampling of the
posterior probability distribution in Bayesian inference problems. The
algorithm combines the local search capabilities of the Manifold Metropolis
Adjusted Langevin transition kernels with the advantages of global exploration
by a population based sampling algorithm, the Transitional Markov Chain Monte
Carlo (TMCMC). The Langevin diffusion process is determined by either the
Hessian or the Fisher Information of the target distribution with appropriate
modifications for non positive definiteness. The present methods is shown to be
superior over other population based algorithms, in sampling probability
distributions for which gradients are available and is shown to handle
otherwise unidentifiable models. We demonstrate the capabilities and advantages
of the method in computing the posterior distribution of the parameters in a
Pharmacodynamics model, for glioma growth and its drug induced inhibition,
using clinical data.


title: On the class of diffusion operators for fast quantum search

abstract:
  Grover's quantum search algorithm evolves a quantum system from a known
source state $|s\rangle$ to an unknown target state $|t\rangle$ using the
selective phase inversions, $I_{s}$ and $I_{t}$, of these two states. In one of
the generalizations of Grover's algorithm, $I_{s}$ is replaced by a general
diffusion operator $D_{s}$ having $|s\rangle$ as an eigenstate and $I_{t}$ is
replaced by a general selective phase rotation $I_{t}^{\phi}$. A fast quantum
search is possible as long as the operator $D_{s}$ and the angle $\phi$
satisfies certain conditions. These conditions are very restrictive in nature.
Specifically, suppose $|\ell\rangle$ denote the eigenstates of $D_{s}$
corresponding to the eigenphases $\theta_{\ell}$. Then the sum of the terms
$|\langle \ell|t\rangle|^{2}\cot(\theta_{\ell}/2)$ over all $\ell \neq s$ has
to be almost equal to $\cot(\phi/2)$ for a fast quantum search. In this paper,
we show that this condition can be significantly relaxed by introducing
appropriate modifications of the algorithm. This allows access to a more
general class of diffusion operators for fast quantum search.


title: Special relativistic hydrodynamics with gravitation

abstract:
  The special relativistic hydrodynamics with weak gravity is hitherto unknown
in the literature. Whether such an asymmetric combination is possible was
unclear. Here, the hydrodynamic equations with Poisson-type gravity considering
fully relativistic velocity and pressure under the weak gravity and the
action-at-a-distance limit are consistently derived from Einstein's general
relativity. Analysis is made in the maximal slicing where the Poisson's
equation becomes much simpler than our previous study in the zero-shear gauge.
Also presented is the hydrodynamic equations in the first post-Newtonian
approximation, now under the {\it general} hypersurface condition. Our
formulation includes the anisotropic stress.


title: Dark Energy or local acceleration?

abstract:
  We find that an observer with a suitable acceleration relative to the frame
comoving whit the cosmic fluid, in the context of the FRW decelerating
universe, measures the same cosmological redshift as the LambdaCDM model. The
estimated value of this acceleration is beta = 1.4x10^-9m/s^2. The problem of a
too high peculiar velocity can be solved assuming, for the observer, a sort of
helical motion.


title: Stability issues of nonlocal gravity during primordial inflation

abstract:
  We study the cosmological evolution of some nonlocal gravity models, when the
initial conditions are set during a phase of primordial inflation. We examine
in particular three models, the so-called RT, RR and $\Delta_4$ models,
previously introduced by our group. We find that the RR and $\Delta_4$ models
have a stable evolution also during inflation. The RT model has an apparent
instability, but we show that, because of the smallness of the scale associated
to the nonlocal term compared to the inflationary scale, this instability is
innocuous and also the RT model has a viable evolution even when its initial
conditions are set during a phase of primordial inflation.


title:
Generation of ultra broadband coherent supercontinuum in tapered and
  dispersion managed silicon nanophotonic waveguides

abstract:
  Tapered and dispersion managed (DM) silicon nanophotonic waveguides are
investigated for the generation of optimal ultra broadband supercontinuum (SC).
DM waveguides are structures showing a longitudinally dependent group velocity
dispersion that results from the variation of the waveguide width with the
propagation distance. For the generation of optimal SC, a genetic algorithm has
been used to find the best dispersion map. This allows for the generation of
highly coherent supercontinuums that span over 1.14 octaves from 1300 nm to
2860 nm and 1.25 octaves from 1200 nm to 2870 nm at -20 dB level for the
tapered and DM waveguides respectively, for a 2 $\mu$m, 200 fs and 6.4 pJ input
pulse. The comparison of these two structures with the usually considered
optimal fixed width waveguide shows that the SC is broader and flatter in the
more elaborated DM waveguide, while the high coherence is ensured by the
varying dispersion.


title:
The boundary Harnack principle for nonlocal elliptic operators in
  non-divergence form

abstract:
  We prove a boundary Harnack inequality for nonlocal elliptic operators $L$ in
non-divergence form with bounded measurable coefficients. Namely, our main
result establishes that if $Lu_1=Lu_2=0$ in $\Omega\cap B_1$, $u_1=u_2=0$ in
$B_1\setminus\Omega$, and $u_1,u_2\geq0$ in $\mathbb R^n$, then $u_1$ and $u_2$
are comparable in $B_{1/2}$. The result applies to arbitrary open sets
$\Omega$.
  When $\Omega$ is Lipschitz, we show that the quotient $u_1/u_2$ is H\"older
continuous up to the boundary in $B_{1/2}$.


title:
Study of timing characteristics of a 3 m long plastic scintillator
  counter using waveform digitizers

abstract:
  A plastic scintillator bar with dimensions 300 cm x 2.5 cm x 11 cm was
exposed to a focused muon beam to study its light yield and timing
characteristics as a function of position and angle of incidence. The
scintillating light was read out at both ends by photomultiplier tubes whose
pulse shapes were recorded by waveform digitizers. Results obtained with the
WAVECATCHER and SAMPIC digitizers are analyzed and compared. A discussion of
the various factors affecting the timing resolution is presented. Prospects for
applications of plastic scintillator technology in large-scale particle physics
detectors with timing resolution around 100 ps are provided in light of the
results.


title:
Variational principles for dissipative (sub)systems, with applications
  to the theory of linear dispersion and geometrical optics

abstract:
  Applications of variational methods are typically restricted to conservative
systems. Some extensions to dissipative systems have been reported too but
require ad hoc techniques such as the artificial doubling of the dynamical
variables. Here, a different approach is proposed. We show that, for a broad
class of dissipative systems of practical interest, variational principles can
be formulated using constant Lagrange multipliers and Lagrangians nonlocal in
time, which allow treating reversible and irreversible dynamics on the same
footing. A general variational theory of linear dispersion is formulated as an
example. In particular, we present a variational formulation for linear
geometrical optics in a general dissipative medium, which is allowed to be
nonstationary, inhomogeneous, nonisotropic, and exhibit both temporal and
spatial dispersion simultaneously.


title: Pion Electromagnetic Form Factor at Lower and Higher Momentum Transfer

abstract:
  The pion electromagnetic form factor is calculated at lower and higher
momentum transfer in order to explore constituent quark models and the
differences among those models. In particular, the light-front constituent
quark model is utilized here to calculate the pion electromagnetic form factor
at lower and higher energies. The matrix elements of the electromagnetic
current, are calculated with both "plus" and "minus" components of the
electromagnetic current in the light-front. Further, the electromagnetic form
factor is compared with other models in the literature and experimental data.


title: Stylometric Analysis of Early Modern Period English Plays

abstract:
  Function word adjacency networks (WANs) are used to study the authorship of
plays from the Early Modern English period. In these networks, nodes are
function words and directed edges between two nodes represent the relative
frequency of directed co-appearance of the two words. For every analyzed play,
a WAN is constructed and these are aggregated to generate author profile
networks. We first study the similarity of writing styles between Early English
playwrights by comparing the profile WANs. The accuracy of using WANs for
authorship attribution is then demonstrated by attributing known plays among
six popular playwrights. Moreover, the WAN method is shown to outperform other
frequency-based methods on attributing Early English plays. In addition, WANs
are shown to be reliable classifiers even when attributing collaborative plays.
For several plays of disputed co-authorship, a deeper analysis is performed by
attributing every act and scene separately, in which we both corroborate
existing breakdowns and provide evidence of new assignments.


title:
On Metric Subregularity for Convex Constraint Systems by Primal
  Equivalent Conditions

abstract:
  In this paper, we mainly study metric subregularity for a convex constraint
system defined by a convex set-valued mapping and a convex constraint subset.
The main work is to provide several primal equivalent conditions for metric
subregularity by contingent cone and graphical derivative. Further it is proved
that these primal equivalent conditions can characterize strong basic
constraint qualification of convex constraint system given by Zheng and Ng
[SIAM J. Optim., 18(2007), pp. 437-460].


title: Markov Chain Truncation for Doubly-Intractable Inference

abstract:
  Computing partition functions, the normalizing constants of probability
distributions, is often hard. Variants of importance sampling give unbiased
estimates of a normalizer Z, however, unbiased estimates of the reciprocal 1/Z
are harder to obtain. Unbiased estimates of 1/Z allow Markov chain Monte Carlo
sampling of "doubly-intractable" distributions, such as the parameter posterior
for Markov Random Fields or Exponential Random Graphs. We demonstrate how to
construct unbiased estimates for 1/Z given access to black-box importance
sampling estimators for Z. We adapt recent work on random series truncation and
Markov chain coupling, producing estimators with lower variance and a higher
percentage of positive estimates than before. Our debiasing algorithms are
simple to implement, and have some theoretical and empirical advantages over
existing methods.


title:
Existence and Lipschitz stability for $\alpha$-dissipative solutions of
  the two-component Hunter-Saxton system

abstract:
  We establish the concept of $\alpha$-dissipative solutions for the
two-component Hunter-Saxton system under the assumption that either
$\alpha(x)=1$ or $0\leq \alpha(x)<1$ for all $x\in \mathbb{R}$. Furthermore, we
investigate the Lipschitz stability of solutions with respect to time by
introducing a suitable parametrized family of metrics in Lagrangian
coordinates. This is necessary due to the fact that the solution space is not
invariant with respect to time.


title: The $p$-curvature conjecture and monodromy about simple closed loops

abstract:
  The Grothendieck-Katz $p$-curvature conjecture is an analogue of the Hasse
Principle for differential equations. It states that a set of arithmetic
differential equations on a variety has finite monodromy if its $p$-curvature
vanishes modulo $p$, for almost all primes $p$. We prove that if the variety is
a generic curve, then every simple closed loop on the curve has finite
monodromy.


title:
Nonvolatile quantum memory enables sensor unlimited nanoscale
  spectroscopy of finite quantum systems

abstract:
  In nanoscale metrology applications, measurements are commonly limited by the
performance of the sensor. Here we show that in nuclear magnetic resonance
(NMR) spectroscopy measurements using single nitrogen-vacancy (NV) centers in
diamond, the NV sensor electron spin limits spectral resolution down to a few
hundred Hz, which constraints the characterization and coherent control of
finite spin systems, and furthermore, is insufficient for high resolution NMR
spectroscopy aiming at single molecule recognition and structure analysis of
the latter. To overcome the limitation, we support an NV electron spin sensor
with a nuclear spin qubit acting as quantum and classical memory allowing for
intermediate nonvolatile storage of metrology information, while suppressing
the deleterious back-action of the sensor onto the system under investigation.
We demonstrate quantum and classical memory lifetimes of 8 ms and 4 minutes
respectively under ambient conditions. Furthermore, we design and test
measurement and decoupling protocols, which exploit such memory qubits
efficiently. Using our hybrid quantum-classical sensor device, we achieve high
resolution NMR spectra with linewidths of single spins down to 13 Hz. Our work
is therefore a prerequisite for high resolution NMR spectroscopy on nanoscopic
quantum systems down to the single level.


title:
Multi-Phase Hadamard receivers for classical communication on lossy
  bosonic channels

abstract:
  A scheme for transferring classical information over a lossy bosonic channel
is proposed by generalizing the proposal presented in Phys. Rev. Lett. 106,
240502 (2011) by Guha. It employs codewords formed by products of coherent
states of fixed mean photon number with multiple phases which, through a
passive unitary transformation, reduce to a Pulse-Position Modulation code with
multiple pulse phases. The maximum information rate achievable with optimal,
yet difficult to implement, detection schemes is computed and shown to saturate
the classical capacity of the channel in the low energy regime. An easy to
implement receiver based on a conditional Dolinar detection scheme is also
proposed finding that, while suboptimal, it allows for improvements in an
intermediate photon-number regime with respect to previous proposals.


title: Almost abelian twists and AdS/CFT

abstract:
  A large class of the recently found unimodular nonabelian homogeneous
Yang-Baxter deformations of the AdS_5 x S^5 superstring can be realized as
sequences of noncommuting TsT transformations. I show that many of them are
duals to various noncommutative versions of supersymmetric Yang-Mills theory,
structurally determined directly in terms of the associated r matrices, in line
with previous expectations in the literature.


title:
First-principles investigation of the structural, dynamical and
  dielectric properties of kesterite, stannite and PMCA phases of Cu2ZnSnS4

abstract:
  Cu2ZnSnS4 (CZTS) is a promising material as an absorber in photovoltaic
applications. The measured efficiency, however, is far from the theoretically
predicted value for the known CZTS phases. To improve the understanding of this
discrepancy we investigate the structural, dynamical, and dielectric of the
three main phases of CZTS (kesterite, stannite, and PMCA) using density
functional perturbation theory (DFPT). The effect of the exchange-correlation
functional on the computed properties is analyzed. A qualitative agreement of
the theoretical Raman spectrum with measurements is observed. However, none of
the phases correspond to the experimental spectrum within the error bar that is
usually to be expected for DFPT. This corroborates the need to consider cation
disorder and other lattice defects extensively in this material.


title:
Simulating the formation of massive seed black holes in the early
  Universe. III: The influence of X-rays

abstract:
  The direct collapse black hole (DCBH) model attempts to explain the observed
number density of supermassive black holes in the early Universe by positing
that they grew from seed black holes with masses of $10^{4}$-$10^{5} \: {\rm
M_{\odot}}$ that formed by the quasi-isothermal collapse of gas in metal-free
protogalaxies cooled by atomic hydrogen emission. For this model to work,
H$_{2}$ formation must be suppressed in at least some of these systems by a
strong extragalactic radiation field. The predicted number density of DCBH
seeds is highly sensitive to the minimum value of the ultraviolet (UV) flux
required to suppress H$_{2}$ formation, $J_{\rm crit}$. In this paper, we
examine how the value of $J_{\rm crit}$ varies as we vary the strength of a
hypothetical high-redshift X-ray background. We confirm earlier findings that
when the X-ray flux $J_{\rm X}$ is large, the critical UV flux scales as
$J_{\rm crit} \propto J_{\rm X}^{1/2}$. We also carefully explore possible
sources of uncertainty arising from how the X-rays are modelled. We use a
reaction-based reduction technique to analyze the chemistry of H$_{2}$ in the
X-ray illuminated gas and identify a critical subset of 35 chemical reactions
that must be included in our chemical model in order to predict $J_{\rm crit}$
accurately. We further show that $J_{\rm crit}$ is insensitive to the details
of how secondary ionization or He$^{+}$ recombination are modelled, but does
depend strongly on the assumptions made regarding the column density of the
collapsing gas.


title:
Rotationally corrected scaling invariant solutions to the Navier-Stokes
  equations

abstract:
  We introduce new classes of solutions to the three dimensional Navier-Stokes
equations in the whole and half spaces that add rotational correction to
self-similar and discretely self-similar solutions. We construct forward
solutions in these new classes for arbitrarily large initial data in $L^3_w$ on
the whole and half spaces. We also comment on the backward case.


title:
Probing a pseudoscalar at the LHC in light of $R(D^{(*)})$ and muon g-2
  excesses

abstract:
  We study the excesses of $R(D^{(*)})$ and muon $g-2$ in the framework of a
two-Higgs-doublet model with top quark flavor-changing neutral-current (FCNC)
couplings. Considering the relevant theoretical and experimental constraints,
we find that the $R(D^{(*)})$ and muon $g-2$ excesses can be simultaneously
explained in a parameter space allowed by the constraints. In such a parameter
space the pseudoscalar ($A$) has a mass between 20 GeV and 150 GeV so that it
can be produced from the top quark FCNC decay $t\to A c$. Focusing on its
dominant decay $A\to \tau\bar{\tau}$, we perform a detailed simulation on
$pp\to t\bar{t}\to Wb Ac\to jjbc\tau\bar{\tau}$ and find that the $2\sigma$
upper limits from a data set of 30 (100) fb$^{-1}$ at the 13 TeV LHC can mostly
(entirely) exclude such a parameter space.


title:
Alternative Schemes of Predicting Lepton Mixing Parameters from Discrete
  Flavor and CP Symmetry

abstract:
  We suggest two alternative schemes to predict lepton mixing angles as well as
$CP$ violating phases from a discrete flavor symmetry group combined with $CP$
symmetry. In the first scenario, the flavor and $CP$ symmetry is broken to the
residual groups of the structure $Z_2\times CP$ in the neutrino and charged
lepton sectors. The resulting lepton mixing matrix depends on two free
parameters $\theta_{\nu}$ and $\theta_{l}$. This type of breaking pattern is
extended to the quark sector. In the second scheme, an abelian subgroup
contained in the flavor group is preserved by the charged lepton mass matrix
and the neutrino mass matrix is invariant under a single remnant $CP$
transformation, all lepton mixing parameter are determined in terms of three
free parameters $\theta_{1, 2, 3}$. We derive the most general criterion to
determine whether two distinct residual symmetries lead to the same mixing
pattern if the redefinition of the free parameters $\theta_{\nu, l}$ and
$\theta_{1, 2, 3}$ is taken into account. We have studied the lepton mixing
patterns arising from the flavor group $S_4$ and $CP$ symmetry which are
subsequently broken to all of the possible residual symmetries discussed in
this work.


title:
Reparameterization Gradients through Acceptance-Rejection Sampling
  Algorithms

abstract:
  Variational inference using the reparameterization trick has enabled
large-scale approximate Bayesian inference in complex probabilistic models,
leveraging stochastic optimization to sidestep intractable expectations. The
reparameterization trick is applicable when we can simulate a random variable
by applying a differentiable deterministic function on an auxiliary random
variable whose distribution is fixed. For many distributions of interest (such
as the gamma or Dirichlet), simulation of random variables relies on
acceptance-rejection sampling. The discontinuity introduced by the
accept-reject step means that standard reparameterization tricks are not
applicable. We propose a new method that lets us leverage reparameterization
gradients even when variables are outputs of a acceptance-rejection sampling
algorithm. Our approach enables reparameterization on a larger class of
variational distributions. In several studies of real and synthetic data, we
show that the variance of the estimator of the gradient is significantly lower
than other state-of-the-art methods. This leads to faster convergence of
stochastic gradient variational inference.


title: Recursive constructions of k-normal polynomials over finite fields

abstract:
  The paper is devoted to produce infinite sequences of $k$-normal polynomials
$F_{u}(x)\in \mathbb{F}_{q}[x]$ of degrees $np^{u} ~ (u\geq 0)$, for a suitably
chosen initial $k$-normal polynomial $F_{0}(x)\in \mathbb{F}_{q}[x]$ of degree
$n$ over $\mathbb{F}_{q}$ by iteratively applying the transformation
$x\rightarrow \frac{x^p-x}{x^p-x+\delta}$, where $\delta\in \mathbb{F}_{q}$ and
$0\leq k\leq n-1$.


title:
A New Eye on the VHE Transient Universe with the HAWC Online Flare
  Monitor

abstract:
  The High Altitude Water Cherenkov (HAWC) Observatory recently began
full-scale operations, surveying 2/3 of the entire sky at very high energy
(VHE; E > 100 GeV). This new view of the sky offers the opportunity to detect
flares from blazars, facilitating studies of the mechanisms powering their
central engines and providing an avenue to constrain the properties of
particles and fields in intergalactic space. The HAWC Collaboration has
implemented an online flare monitor to search for rapid and extreme transient
activity from a set of blazars either known or suspected to produce VHE
emission. The goal of this project is to issue alerts sufficiently rapidly to
form a complete multiwavelength picture of the flare. We describe the current
status of the online flare monitor, demonstrating its ability to detect flares
via a study of the blazars Markarian 421 and Markarian 501 in offline data.


title:
Beatification: Flattening the Poisson Bracket for Two-Dimensional Fluid
  and Plasma Theories

abstract:
  A perturbative method called beatification is presented for a class of
two-dimensional fluid and plasma theories. The Hamiltonian systems considered,
namely the Euler, Vlasov-Poisson, Hasegawa-Mima, and modified Hasegawa-Mima
equations, are naturally described in terms of noncanonical variables. The
beatification procedure amounts to finding the correct transformation that
removes the explicit variable dependence from a noncanonical Poisson bracket
and replaces it with a fixed dependence on a chosen state in phase space. As
such, beatification is a major step toward casting the Hamiltonian system in
its canonical form, thus enabling or facilitating the use of analytical and
numerical techniques that require or favor a representation in terms of
canonical, or beatified, Hamiltonian variables.

categories: physics.flu-dyn math-ph math.MP physics.plasm-ph


title:
The OmegaWhite survey for Short-Period Variable Stars III: Follow-up
  Photometric and Spectroscopic Observations

abstract:
  We present photometric and spectroscopic follow-up observations of
short-period variables discovered in the OmegaWhite survey: a wide-field
high-cadence g-band synoptic survey targeting the Galactic Plane. We have used
fast photometry on the SAAO 1.0-m and 1.9-m telescopes to obtain light curves
of 27 variables, and use these results to validate the period and amplitude
estimates from the OmegaWhite processing pipeline. Furthermore, 57 sources (44
unique, 13 also with new light curves) were selected for spectroscopic
follow-up using either the SAAO 1.9-m telescope or the Southern African Large
Telescope. We find many of these variables have spectra which are consistent
with being delta Scuti type pulsating stars. At higher amplitudes, we detect
four possible pulsating white dwarf/subdwarf sources and an eclipsing
cataclysmic variable. Due to their rarity, these targets are ideal candidates
for detailed follow-up studies. From spectroscopy, we confirm the symbiotic
binary star nature of two variables identified as such in the SIMBAD database.
We also report what could possibly be the first detection of the `Bump Cepheid'
phenomena in a delta Scuti star, with OW J175848.21-271653.7 showing a
pronounced 22% amplitude dip lasting 3 minutes during each pulsational cycle
peak. However, the precise nature of this target is still uncertain as it
exhibits the spectral features of a B-type star.


title: Low-rank and Sparse Soft Targets to Learn Better DNN Acoustic Models

abstract:
  Conventional deep neural networks (DNN) for speech acoustic modeling rely on
Gaussian mixture models (GMM) and hidden Markov model (HMM) to obtain binary
class labels as the targets for DNN training. Subword classes in speech
recognition systems correspond to context-dependent tied states or senones. The
present work addresses some limitations of GMM-HMM senone alignments for DNN
training. We hypothesize that the senone probabilities obtained from a DNN
trained with binary labels can provide more accurate targets to learn better
acoustic models. However, DNN outputs bear inaccuracies which are exhibited as
high dimensional unstructured noise, whereas the informative components are
structured and low-dimensional. We exploit principle component analysis (PCA)
and sparse coding to characterize the senone subspaces. Enhanced probabilities
obtained from low-rank and sparse reconstructions are used as soft-targets for
DNN acoustic modeling, that also enables training with untranscribed data.
Experiments conducted on AMI corpus shows 4.6% relative reduction in word error
rate.


title:
New Insights in the Spectral Variability and Physical Conditions of the
  X-ray Absorbers in NGC 4151

abstract:
  We investigate the relationship between the long term X-ray spectral
variability in the Seyfert 1.5 galaxy NGC 4151 and its intrinsic absorption, by
comparing the 2014 simultaneous ultraviolet/X-Ray observations taken with
Hubble STIS Echelle and Chandra HETGS with archival observations from Chandra,
XMM-Newton and Suzaku. The observations are divided into "high" and "low"
states, with the low states showing strong and unabsorbed extended emission at
energies below 2 keV. Our X-ray model consists of a broken powerlaw, neutral
reflection and the two dominant absorption components identified by Kraemer et
al. (2005), hereafter KRA2005, X-High and D+Ea, which are present in all
epochs. The model fittings suggest that the absorbers are very stable, with the
principal changes in the intrinsic absorption resulting from variations in the
ionization state of the gas as the ionizing continuum varies. However, the low
states show evidence of larger column densities in one or both of the
absorbers. Among plausible explanations for the column increase, we discuss the
possibility of an expanding/contracting X-ray corona. As suggested by KRA2005,
there seem to be contributions from magnetohydrodynamic (MHD) winds to the mass
outflow. Along with the ultra fast outflow absorber identified by Tombesi et
al. (2010), X-High is consistent with being magnetically driven. On the other
hand, it is unlikely that D+Ea is part of the MHD flow, and it is possible that
it is radiatively accelerated. These results suggest that at a sufficiently
large radial distance there is a break point between MHD-dominated and
radiatively driven outflows.


title: Probing TMDs in heavy quarkonium production in $pp$ collision

abstract:
  We present a recent calculation of $J/\psi$ and $\Upsilon$ production in
unpolarized $pp$ collision and show that this can be used to probe the
unpolarized gluon as well as the linearly polarized gluon transverse momentum
dependent parton distributions (TMDs). We use the color evaporation model for
the heavy quarkonium production and use a generalized factorized form of the
cross section. We compare the results with experimental data.


title:
Beta-functions of non-linear $\sigma$-models for disordered and
  interacting electron systems

abstract:
  We provide and study complete sets of one-loop renormalization group
equations of several Finkel'stein non-linear $\sigma$-models, the effective
field theories describing the diffusive quantum fluctuations in correlated
disordered systems. We consider different cases according to the presence of
certain symmetries induced by the original random Hamiltonians, and we show
that, for interacting systems, the Cartan's classification of symmetry classes
is not enough to uniquely determine their scaling behaviors.


title:
Origin of asymmetries in X-ray emission lines from the blast wave of the
  2014 outburst of nova V745 Sco

abstract:
  The symbiotic nova V745 Sco was observed in outburst on 2014 February 6. Its
observations by the Chandra X-ray Observatory at days 16 and 17 have revealed a
spectrum characterized by asymmetric and blue-shifted emission lines. Here we
investigate the origin of these asymmetries through three-dimensional
hydrodynamic simulations describing the outburst during the first 20 days of
evolution. The model takes into account thermal conduction and radiative
cooling and assumes a blast wave propagates through an equatorial density
enhancement. From the simulations, we synthesize the X-ray emission and derive
the spectra as they would be observed with Chandra. We find that both the blast
wave and the ejecta distribution are efficiently collimated in polar directions
due to the presence of the equatorial density enhancement. The majority of the
X-ray emission originates from the interaction of the blast with the equatorial
density enhancement and is concentrated on the equatorial plane as a ring-like
structure. Our "best-fit" model requires a mass of ejecta in the outburst
$M_{ej} \approx 3\times 10^{-7}\,M_{\odot}$ and an explosion energy $E_b
\approx 3 \times 10^{43}$ erg and reproduces the distribution of emission
measure vs temperature and the evolution of shock velocity and temperature
inferred from the observations. The model predicts asymmetric and blue-shifted
line profiles similar to those observed and explains their origin as due to
substantial X-ray absorption of red-shifted emission by ejecta material. The
comparison of predicted and observed Ne and O spectral line ratios reveals no
signs of strong Ne enhancement and suggests the progenitor is a CO white dwarf.


title:
Semantic Decomposition and Recognition of Long and Complex Manipulation
  Action Sequences

abstract:
  Understanding continuous human actions is a non-trivial but important problem
in computer vision. Although there exists a large corpus of work in the
recognition of action sequences, most approaches suffer from problems relating
to vast variations in motions, action combinations, and scene contexts. In this
paper, we introduce a novel method for semantic segmentation and recognition of
long and complex manipulation action tasks, such as "preparing a breakfast" or
"making a sandwich". We represent manipulations with our recently introduced
"Semantic Event Chain" (SEC) concept, which captures the underlying
spatiotemporal structure of an action invariant to motion, velocity, and scene
context. Solely based on the spatiotemporal interactions between manipulated
objects and hands in the extracted SEC, the framework automatically parses
individual manipulation streams performed either sequentially or concurrently.
Using event chains, our method further extracts basic primitive elements of
each parsed manipulation. Without requiring any prior object knowledge, the
proposed framework can also extract object-like scene entities that exhibit the
same role in semantically similar manipulations. We conduct extensive
experiments on various recent datasets to validate the robustness of the
framework.


title:
Packet Error Rate Analysis of Uncoded Schemes in Block-Fading Channels
  using Extreme Value Theory

abstract:
  We present a generic approximation of the packet error rate (PER) function of
uncoded schemes in the AWGN channel using extreme value theory (EVT). The PER
function can assume both the exponential and the Gaussian Q-function bit error
rate (BER) forms. The EVT approach leads us to a best closed-form
approximation, in terms of accuracy and computational efficiency, of the
average PER in block-fading channels. The numerical analysis shows that the
approximation holds tight for any value of SNR and packet length whereas the
earlier studies approximate the average PER only at asymptotic SNRs and packet
lengths.


title:
Fast and direct nonparametric procedures in the L-moment homogeneity
  test

abstract:
  Regional frequency analysis is an important tool to properly estimate
hydrological characteristics at ungauged or partially gauged sites in order to
prevent hydrological disasters. The delineation of homogeneous groups of sites
is an important first step in order to transfer information and obtain accurate
quantile estimates at the target site. The Hosking-Wallis homogeneity test is
usually used to test the homogeneity of the selected sites. Despite its
usefulness and good power, it presents some drawbacks including the subjective
choice of a parametric distribution for the data and a poorly justified
rejection threshold. The present paper addresses these drawbacks by integrating
nonparametric procedures in the L-moment homogeneity test. To assess the
rejection threshold, three resampling methods (permutation, bootstrap and
P\'olya resampling) are considered. Results indicate that permutation and
bootstrap methods perform better than the parametric Hosking-Wallis test in
terms of power as well as in time and procedure simplicity. A real-world case
study shows that the nonparametric tests agree with the HW test concerning the
homogeneity of the volume and the bivariate case while they disagree for the
peak case, but that the assumptions of the HW test are not well respected.


title:
Effects of active-sterile neutrino mixing during primordial
  nucleosynthesis

abstract:
  In the present work, we discuss the effects of the inclusion of
sterile-active neutrino oscillations during the production of primordial
light-nuclei. We assume that the sterile neutrino mass-eigenstate might
oscillate with the two lightest active neutrino mass- eigenstates, with mixing
angles ${\phi}_1$ and ${\phi}_2$. We also allow a constant renormalization
(represented by a parameter (${\zeta}$)) of the sterile neutrino occupation
factor. Taking ${\zeta}$ and the mixing angles as free parameters, we have
computed distribution functions of active and sterile neutrinos and primordial
abundances. Using observable data we set constrains in the free parameters of
the model. It is found that the data on primordial abundances are consistent
with small mixing angles and with a value of ${\zeta}$ smaller than 0.65 at
3${\sigma}$ level.


title: "Butterfly Effect" vs Chaos in Energy Futures Markets

abstract:
  In this paper we test for the sensitive dependence on initial conditions (the
so called "butterfly effect") of energy futures time series (heating oil,
natural gas), and thus the determinism of those series. This paper is
distinguished from previous studies in the following points: first, we reread
existent works in the literature on energy markets, enlightening the role of
\emph{butterfly effect} in chaos definition (introduced by Devaney), using this
definition to prevent us from misleading results about ostensible chaoticity of
the price series. Second, we test for the time series for sensitive dependence
on initial conditions, introducing a coefficient that describes the determinism
rate of the series and that represents its reliability level (in percentage).
The introduction of this reliability level is motivated by the fact that time
series generated from stochastic systems also might show sensitive dependence
on initial conditions. According to this perspective, the maximum reliability
level obtained here is too low to be able to ensure that there is strong
evidence of sensitive The maximum reliability level obtained here was been
$\simeq 56\% $, too low to ensure strong evidence of sensitive dependence on
initial conditions.


title: Spin Relaxation in GaAs: Importance of Electron-Electron Interactions

abstract:
  We study spin relaxation in n-type bulk GaAs, due to the Dyakonov--Perel
mechanism, using ensemble Monte Carlo methods. Our results confirm that spin
relaxation time increases with the electronic density in the regime of moderate
electronic concentrations and high temperature. We show that the
electron-electron scattering in the non-degenerate regime significantly slows
down spin relaxation. This result supports predictions by Glazov and Ivchenko.
Most importantly, our findings highlight the importance of many-body
interactions for spin dynamics: we show that only by properly taking into
account electron-electron interactions within the simulations, results for the
spin relaxation time---with respect to both electron density and
temperature---will reach good {\it quantitative} agreement with corresponding
experimental data. Our calculations contain no fitting parameters.


title:
Compact ring-based X-ray source with on-orbit and on-energy laser-plasma
  injection

abstract:
  We report here the results of a one week long investigation into the
conceptual design of an X-ray source based on a compact ring with on-orbit and
on-energy laser-plasma accelerator. We performed these studies during the June
2016 USPAS class "Physics of Accelerators, Lasers, and Plasma..." applying the
art of inventiveness TRIZ. We describe three versions of the light source with
the constraints of the electron beam with energy $1\,\rm{GeV}$ or $3\,\rm{GeV}$
and a magnetic lattice design being normal conducting (only for the
$1\,\rm{GeV}$ beam) or superconducting (for either beam). The electron beam
recirculates in the ring, to increase the effective photon flux. We describe
the design choices, present relevant parameters, and describe insights into
such machines.


title:
Coercivity condition for higher order moments for nonlinear SPDEs and
  existence of solution under local monotonicity

abstract:
  Higher order moment estimates for solutions to nonlinear SPDEs governed by
locally-monotone operators are obtained under appropriate coercivity condition.
These are then used to extend known existence and uniqueness results for
nonlinear SPDEs under local monotonicity conditions to allow derivatives in the
operator acting on the solution under the stochastic integral.


title:
Area-preserving diffeomorphism of the hyperbolic plane and K-surfaces in
  Anti-de Sitter space

abstract:
  We prove that any weakly acausal curve $\Gamma$ in the boundary of Anti-de
Sitter (2+1)-space is the asymptotic boundary of two spacelike $K$-surfaces,
one of which is past-convex and the other future-convex, for every
$K\in(-\infty,-1)$. The curve $\Gamma$ is the graph of a quasisymmetric
homeomorphism of the circle if and only if the $K$-surfaces have bounded
principal curvatures. Moreover in this case a uniqueness result holds.
  The proofs rely on a well-known correspondence between spacelike surfaces in
Anti-de Sitter space and area-preserving diffeomorphisms of the hyperbolic
plane. In fact, an important ingredient is a representation formula, which
reconstructs a spacelike surface from the associated area-preserving
diffeomorphism.
  Using this correspondence we then deduce that, for any fixed
$\theta\in(0,\pi)$, every quasisymmetric homeomorphism of the circle admits a
unique extension which is a $\theta$-landslide of the hyperbolic plane. These
extensions are quasiconformal.


title:
Correlation between opposite-helicity gravitons: Imprints on
  gravity-wave and microwave backgrounds

abstract:
  We examine some of the roots of parity violation for gravitons and uncover a
closely related new effect: correlations between right and left handed
gravitons. Such correlators have spin 4 if they involve gravitons moving along
the same direction, and spin zero for gravitons moving with opposite
directions. In the first case, the most immediate implication would be a degree
of linear polarization for the tensor vacuum fluctuations, which could be seen
by gravity wave detectors sensitive enough to probe the primordial background,
its degree of polarization and anisotropies. Looking at the anisotropy of the
gravity waves linear polarization we identify the parity respecting and
violating components of the effect. The imprint on the CMB temperature and
polarization would be more elusive, since it averages to zero in the two-point
functions, appearing only in their cosmic variance or in fourth order
correlators. In contrast, spin zero correlations would have an effect on the
two point function of the CMB temperature and polarization, enhancing the $BB$
component if they were anti-correlations. Such correlations represent an
amplitude for the production of standing waves, as first envisaged by
Grishchuk, and could also leave an interesting signature for gravity wave
detectors.


title:
Two approaches to modeling the interaction of small and medium
  price-taking traders with a stock exchange by mathematical programming
  techniques

abstract:
  The paper presents two new approaches to modeling the interaction of small
and medium pricetaking traders with a stock exchange. In the framework of these
approaches, the traders can form and manage their portfolios of financial
instruments traded on a stock exchange with the use of linear, integer, and
mixed programming techniques. Unlike previous authors publications on the
subject, besides standard securities, the present publication considers
derivative financial instruments such as futures and options contracts.


title:
Singularity of a combustion wave profile: a clue to the multicomponent
  theory for liquid-gas filtration combustion

abstract:
  We study a nonlinear wave for a system of balance laws in one space
dimension, which describes combustion for two-phase (gas and liquid) flow in
porous medium. The problem is formulated for a general $N$-component liquid for
modeling the strong multicomponent effects reported recently for an application
to light oil recovery by air injection. Despite the immense complexity of the
model, the problem allows analytic solution. The clue to this solution is a
special form of a folding singularity, which occurs at an internal point of the
wave profile. Analysis of this singularity provides a missing determining
relation for wave parameters. This result is not only interesting for the
application under consideration, but also motivates a deeper mathematical study
of such singularities for general systems of balance laws.


title:
Assessing magnetic torques and energy fluxes in close-in star-planet
  systems

abstract:
  Planets in close-in orbit interact with the magnetized wind of their hosting
star. This magnetic interaction was proposed to be a source for enhanced
emissions in the chromosphere of the star, and to participate in setting the
migration time-scale of the close-in planet. The efficiency of the magnetic
interaction is know to depend on the magnetic properties of the host star, of
the planet, and on the magnetic topology of the interaction. We use a global,
three-dimensional numerical model of close-in star planet systems, based on the
magnetohydrodynamics approximation, to compute a grid of simulations for
varying properties of the orbiting planet. We propose a simple parametrization
of the magnetic torque that applies to the planet, and of the energy flux
generated by the interaction. The dependancy upon the planet properties and the
wind properties are clearly identified in the derived scaling laws, which can
be used in secular evolution codes to take into account the effect of magnetic
interactions in planet migration. They can also be used to estimate a potential
magnetic source of enhanced emissions in observed close-in star-planet systems,
in order to constrain observationally possible exoplanetary magnetic fields.


title:
Symmetry protected topological phases of 1D interacting fermions with
  spin-charge separation

abstract:
  The low energy behavior of a huge variety of one-dimensional interacting
spinful fermionic systems exhibits spin-charge separation, described in the
continuum limit by two sine-Gordon models decoupled in the charge and spin
channels. Interaction is known to induce, besides the gapless Luttinger liquid
phase, eight possible gapped phases, among which are the Mott, Haldane,
charge-/spin-density, and bond-ordered wave insulators, and the Luther Emery
liquid. Here we prove that some of these physically distinct phases have
nontrivial topological properties, notably the presence of degenerate protected
edge modes with fractionalized charge/spin. Moreover, we show that the eight
gapped phases are in one-to-one correspondence with the symmetry-protected
topological (SPT) phases classified by group cohomology theory in the presence
of particle-hole symmetry P. The latter result is also exploited to
characterize SPT phases by measurable nonlocal order parameters which follow
the system evolution to the quantum phase transition. The implications on the
appearance of exotic orders in the class of microscopic Hubbard Hamiltonians,
possibly without P symmetry at higher energies, are discussed.


title: A machine learned classifier for RR Lyrae in the VVV survey

abstract:
  Variable stars of RR Lyrae type are a prime tool to obtain distances to old
stellar populations in the Milky Way, and one of the main aims of the Vista
Variables in the Via Lactea (VVV) near-infrared survey is to use them to map
the structure of the Galactic Bulge. Due to the large number of expected
sources, this requires an automated mechanism for selecting RR Lyrae,and
particularly those of the more easily recognized type ab (i.e.,
fundamental-mode pulsators), from the 10^6-10^7 variables expected in the VVV
survey area. In this work we describe a supervised machine-learned classifier
constructed for assigning a score to a K_s-band VVV light curve that indicates
its likelihood of being ab-type RR Lyrae. We describe the key steps in the
construction of the classifier, which were the choice of features, training
set, selection of aperture and family of classifiers. We find that the AdaBoost
family of classifiers give consistently the best performance for our problem,
and obtain a classifier based on the AdaBoost algorithm that achieves a
harmonic mean between false positives and false negatives of ~7% for typical
VVV light curve sets. This performance is estimated using cross-validation and
through the comparison to two independent datasets that were classified by
human experts.


title:
Relatively-Smooth Convex Optimization by First-Order Methods, and
  Applications

abstract:
  The usual approach to developing and analyzing first-order methods for smooth
convex optimization assumes that the gradient of the objective function is
uniformly smooth with some Lipschitz constant $L$. However, in many settings
the differentiable convex function $f(\cdot)$ is not uniformly smooth -- for
example in $D$-optimal design where $f(x):=-\ln \det(HXH^T)$, or even the
univariate setting with $f(x) := -\ln(x) + x^2$. Herein we develop a notion of
"relative smoothness" and relative strong convexity that is determined relative
to a user-specified "reference function" $h(\cdot)$ (that should be
computationally tractable for algorithms), and we show that many differentiable
convex functions are relatively smooth with respect to a correspondingly
fairly-simple reference function $h(\cdot)$. We extend two standard algorithms
-- the primal gradient scheme and the dual averaging scheme -- to our new
setting, with associated computational guarantees. We apply our new approach to
develop a new first-order method for the $D$-optimal design problem, with
associated computational complexity analysis. Some of our results have a
certain overlap with the recent work \cite{bbt}.


title: A multirate numerical scheme for large-scale vehicle traffic simulation

abstract:
  Nowadays the city-wide traffic contains hundreds of thousands of vehicles
with different scenarios of their behavior. If a microscopic approach is used
it leads to solving tremendous systems of ordinary differential equations whose
components have a wide range of variation rates. The given paper has introduced
a multirate numerical scheme with a self-adjusting time stepping strategy.
Instead of using a single step size for the whole system we have determined the
step size for each component by estimating its own local variation. We also
performed the stability analysis for the developed scheme. The presented
multirate scheme provides a significant speed-up in processor times compared to
the corresponding single-rate one. The use of multiple time steps admits
parallel computing.


title: Feasibility Based Large Margin Nearest Neighbor Metric Learning

abstract:
  Large margin nearest neighbor (LMNN) is a metric learner which optimizes the
performance of the popular $k$NN classifier. However, its resulting metric
relies on pre-selected target neighbors. In this paper, we address the
feasibility of LMNN's optimization constraints regarding these target points,
and introduce a mathematical measure to evaluate the size of the feasible
region of the optimization problem. We enhance the optimization framework of
LMNN by a weighting scheme which prefers data triplets which yield a larger
feasible region. This increases the chances to obtain a good metric as the
solution of LMNN's problem. We evaluate the performance of the resulting
feasibility-based LMNN algorithm using synthetic and real datasets. The
empirical results show an improved accuracy for different types of datasets in
comparison to regular LMNN.


title: Anti-patterns and the energy efficiency of Android applications

abstract:
  The boom in mobile apps has changed the traditional landscape of software
development by introducing new challenges due to the limited resources of
mobile devices, e.g., memory, CPU, network bandwidth and battery. The energy
consumption of mobile apps is nowadays a hot topic and researchers are actively
investigating the role of coding practices on energy efficiency. Recent studies
suggest that design quality can conflict with energy efficiency. Therefore, it
is important to take into account energy efficiency when evolving the design of
a mobile app. The research community has proposed approaches to detect and
remove anti-patterns (i.e., poor solutions to design and implementation
problems) in software systems but, to the best of our knowledge, none of these
approaches have included anti-patterns that are specific to mobile apps and--or
considered the energy efficiency of apps. In this paper, we fill this gap in
the literature by analyzing the impact of eight type of anti-patterns on a
testbed of 59 android apps extracted from F-Droid. First, we (1) analyze the
impact of anti-patterns in mobile apps with respect to energy efficiency; then
(2) we study the impact of different types of anti-patterns on energy
efficiency. We found that then energy consumption of apps containing
anti-patterns and not (refactored apps) is statistically different. Moreover,
we find that the impact of refactoring anti-patterns can be positive (7 type of
anti-patterns) or negative (2 type of anti-patterns). Therefore, developers
should consider the impact on energy efficiency of refactoring when applying
maintenance activities.


title: Fast L1-NMF for Multiple Parametric Model Estimation

abstract:
  In this work we introduce a comprehensive algorithmic pipeline for multiple
parametric model estimation. The proposed approach analyzes the information
produced by a random sampling algorithm (e.g., RANSAC) from a machine
learning/optimization perspective, using a \textit{parameterless} biclustering
algorithm based on L1 nonnegative matrix factorization (L1-NMF). The proposed
framework exploits consistent patterns that naturally arise during the RANSAC
execution, while explicitly avoiding spurious inconsistencies. Contrarily to
the main trends in the literature, the proposed technique does not impose
non-intersecting parametric models. A new accelerated algorithm to compute
L1-NMFs allows to handle medium-sized problems faster while also extending the
usability of the algorithm to much larger datasets. This accelerated algorithm
has applications in any other context where an L1-NMF is needed, beyond the
biclustering approach to parameter estimation here addressed. We accompany the
algorithmic presentation with theoretical foundations and numerous and diverse
examples.


title:
Relativistic calculations of the non-resonant two-photon ionization of
  neutral atoms

abstract:
  The non-resonant two-photon one-electron ionization of neutral atoms is
studied theoretically in the framework of relativistic second-order
perturbation theory and independent particle approximation. In particular, the
importance of relativistic and screening effects in the total two-photon
ionization cross section is investigated. Detailed computations have been
carried out for the K-shell ionization of neutral Ne, Ge, Xe, and U atoms. The
relativistic effects significantly decrease the total cross section, for the
case of U, for example, they reduce the total cross section by a factor of two.
Moreover, we have found that the account for the screening effects of the
remaining electrons leads to occurrence of an unexpected minimum in the total
cross section at the total photon energies equal to the ionization threshold,
for the case of Ne, for example, the cross section drops there by a factor of
three.


title:
Minimizing the number of independent sets in triangle-free regular
  graphs

abstract:
  Recently, Davies, Jenssen, Perkins, and Roberts gave a very nice proof of the
result (due, in various parts, to Kahn, Galvin-Tetali, and Zhao) that the
independence polynomial of a $d$-regular graph is maximized by disjoint copies
of $K_{d,d}$. Their proof uses linear programming bounds on the distribution of
a cleverly chosen random variable. In this paper, we use this method to give
lower bounds on the independence polynomial of regular graphs. We also give new
bounds on the number of independent sets in triangle-free regular graphs.


title:
Tomographic docking suggests the mechanism of auxin receptor TIR1
  selectivity

abstract:
  We study the binding of plant hormone IAA on its receptor TIR1 introducing a
novel computational method that we call tomographic docking and that accounts
for interactions occurring along the depth of the binding pocket. Our results
suggest that selectivity is related to constraints that potential ligands
encounter on their way from the surface of the protein to their final position
at the pocket bottom. Tomographic docking helps develop specific hypotheses
about ligand binding, distinguishing binders from non-binders, and suggests
that binding is a three-step mechanism, consisting of engagement with a niche
in the back wall of the pocket, interaction with a molecular filter which
allows or precludes further descent of ligands, and binding on the pocket base.
Only molecules that are able to descend the pocket and bind at its base allow
the co-receptor IAA7 to bind on the complex, thus behaving as active auxins.
Analyzing the interactions at different depths, our new method helps in
identifying critical residues that constitute preferred future study targets
and in the quest for safe and effective herbicides. Also, it has the potential
to extend the utility of docking from ligand searches to the study of processes
contributing to selectivity.


title: Design Mining Microbial Fuel Cell Cascades

abstract:
  Microbial fuel cells (MFCs) perform wastewater treatment and electricity
production through the conversion of organic matter using microorganisms. For
practical applications, it has been suggested that greater efficiency can be
achieved by arranging multiple MFC units into physical stacks in a cascade with
feedstock flowing sequentially between units. In this paper, we investigate the
use of computational intelligence to physically explore and optimise
(potentially) heterogeneous MFC designs in a cascade, i.e. without simulation.
Conductive structures are 3-D printed and inserted into the anodic chamber of
each MFC unit, augmenting a carbon fibre veil anode and affecting the
hydrodynamics, including the feedstock volume and hydraulic retention time, as
well as providing unique habitats for microbial colonisation. We show that it
is possible to use design mining to identify new conductive inserts that
increase both the cascade power output and power density.


title:
Propagation and synchronization of reverberatory bursts in developing
  cultured networks

abstract:
  Developing networks of neural systems can exhibit spontaneous, synchronous
activities called neural bursts, which can be important in the organization of
functional neural circuits. Before the network matures, the activity level of a
burst can reverberate in repeated rise-and-falls in periods of hundreds of
milliseconds following an initial wave-like propagation of spiking activity,
while the burst itself lasts for seconds. To investigate the spatiotemporal
structure of the reverberatory bursts, we culture dissociated, rat cortical
neurons on a high-density multi-electrode array to record the dynamics of
neural activity over the growth and maturation of the network. We find the
synchrony of the spiking significantly reduced following the initial wave and
the activities become broadly distributed spatially. The synchrony recovers as
the system reverberates until the end of the burst. Using a propagation model
we infer the spreading speed of the spiking activity, which increases as the
culture ages. We perform computer simulations of the system using a
physiological model of spiking networks in two spatial dimensions and find the
parameters that reproduce the observed resynchronization of spiking in the
bursts. An analysis of the simulated dynamics suggests that the depletion of
synaptic resources causes the resynchronization. The spatial propagation
dynamics of the simulations match well with observations over the course of a
burst and point to an interplay of the synaptic efficacy and the noisy neural
self-activation in producing the morphology of the bursts.


title:
Monotonicity-based regularization for phantom experiment data in
  Electrical Impedance Tomography

abstract:
  In electrical impedance tomography, algorithms based on minimizing the
linearized-data-fit residuum have been widely used due to their real-time
implementation and satisfactory reconstructed images. However, the resulting
images usually tend to contain ringing artifacts. In this work, we shall
minimize the linearized-data-fit functional with respect to a linear constraint
defined by the monotonicity relation in the framework of real electrode
setting. Numerical results of standard phantom experiment data confirm that
this new algorithm improves the quality of the reconstructed images as well as
reduce the ringing artifacts.


title: Measures on the square as sparse graph limits

abstract:
  We study a metric on the set of finite graphs in which two graphs are
considered to be similar if they have similar bounded dimensional "factors". We
show that limits of convergent graph sequences in this metric can be
represented by symmetric Borel measures on $[0,1]^2$. This leads to a
generalization of dense graph limit theory to sparse graph sequences.


title:
Motivic random variables and representation stability II: Hypersurface
  sections

abstract:
  We prove geometric and cohomological stabilization results for the universal
smooth degree $d$ hypersurface section of a fixed smooth projective variety as
$d$ goes to infinity. We show that relative configuration spaces of the
universal smooth hypersurface section stabilize in the completed Grothendieck
ring of varieties, and deduce from this the stabilization of the Hodge Euler
characteristic of natural families of local systems constructed from the
vanishing cohomology. We prove explicit formulas for the stable values using a
probabilistic interpretation, along with the natural analogs in point counting
over finite fields. We explain how these results provide new geometric examples
of a weak version of representation stability for symmetric, symplectic, and
orthogonal groups. This interpretation of representation stability was studied
in the prequel for configuration spaces.


title:
Potential-inserted quantum well design for quantum cascade terahertz
  lasers

abstract:
  We report on a new design of terahertz quantum cascade laser based on a
single, potential-inserted quantum well active region. The quantum well
properties are engineered through single monolayer InAs inserts. The modeling
is based on atomistic, spds* tight-binding calculations, and performances are
compared to that of the classical three-well design. We obtain a 100% increase
of the oscillator strength per unit length, while maintaining a high, nearly
temperature-independent contrast between phonon-induced relaxation times of the
upper and lower lasing states. The improved performances are expected to allow
THz lasing at room temperature.


title:
Refined regularity of the blow-up set linked to refined asymptotic
  behavior for the semilinear heat equation

abstract:
  We consider $u(x,t)$, a solution of $\partial_tu = \Delta u + |u|^{p-1}u$
which blows up at some time $T > 0$, where $u:\mathbb{R}^N \times[0,T) \to
\mathbb{R}$, $p > 1$ and $(N-2)p < N+2$. Define $S \subset \mathbb{R}^N$ to be
the blow-up set of $u$, that is the set of all blow-up points. Under suitable
nondegeneracy conditions, we show that if $S$ contains a $(N-\ell)$-dimensional
continuum for some $\ell \in \{1,\dots, N-1\}$, then $S$ is in fact a
$\mathcal{C}^2$ manifold. The crucial step is to derive a refined asymptotic
behavior of $u$ near blow-up. In order to obtain such a refined behavior, we
have to abandon the explicit profile function as a first order approximation
and take a non-explicit function as a first order description of the singular
behavior. This way we escape logarithmic scales of the variable $(T-t)$ and
reach significant small terms in the polynomial order $(T-t)^\mu$ for some $\mu
> 0$. The refined asymptotic behavior yields geometric constraints of the
blow-up set, leading to more regularity on $S$.


title:
Motivic random variables and representation stability I: Configuration
  spaces

abstract:
  We prove a motivic stabilization result for the cohomology of the local
systems on configuration spaces of varieties over $\mathbb{C}$ attached to
character polynomials. Our approach interprets the stabilization as a
probabilistic phenomenon based on the asymptotic independence of certain
*motivic random variables*, and gives explicit universal formulas for the
limits in terms of the exponents of a motivic Euler product for the Kapranov
zeta function. The result can be thought of as a weak but explicit version of
representation stability for the cohomology of ordered configuration spaces. In
the sequel we find similar stability results in spaces of smooth hypersurface
sections, providing new examples to be investigated through the lens of
representation stability for symmetric, symplectic and orthogonal groups.


title:
The Resolvent Matrix of the Truncated Hausdorff Matrix Moment Problem
  via New Dyukarev-Stieltjes Parameters and Extremal Solutions via Continued
  Fractions

abstract:
  We obtain a new multiplicative decomposition of the resolvent matrix of the
truncated Hausdorff matrix moment (THMM) problem in the case of an odd and even
number of moments via new Dyukarev-Stieltjes matrix (DSM) parameters. Explicit
interrelations between new DSM parameters and orthogonal matrix polynomials on
a finite interval $[a,b]$, as well as the Schur complements of the block Hankel
matrices constructed through the moments of the THMM problem are given.
Additionally, the extremal solutions of the THMM problem are represented via
matrix continued fractions in terms of the DSM parameters.


title: Polynomial-time algorithm for determining the graph isomorphism (v.2)

abstract:
  We develop the methodology of positioning graph vertices relative to each
other to solve the problem of determining isomorphism of two undirected graphs.
Based on the position of the vertex in one of the graphs, it is determined the
corresponding vertex in the other graph.
  For the selected vertex of the undirected graph, we define the neighborhoods
of the vertices. Next, we construct the auxiliary directed graph, spawned by
the selected vertex. The vertices of the digraph are positioned by special
characteristics --- vectors, which locate each vertex of the digraph relative
the found neighborhoods.
  This enabled to develop the algorithm for determining graph isomorphism, the
runing time of which is equal to $O(n^4)$.


title:
Structured Unit Testable Templated Code for Efficient Code Review
  Process

abstract:
  Modern software development teams are distributed across onsite and off-shore
locations. Each team has developers with varying experience levels and English
communication skills. In such a diverse development environment it is important
to maintain the software quality, coding standards, timely delivery of features
and bug fixes. It is also important to reduce testing effort, minimize side
effects such as change in functionality, user experience or application
performance. Code reviews are intended to control code quality. Unfortunately,
many projects lack enforcement of processes and standards because of
approaching deadlines, live production issues and lack of resource
availability. This study examines a novel structured, unit testable templated
code method to enforce code review standards with an intent to reduce coding
effort, minimize revisions and eliminate functional and performance side
effects on the system. The proposed method would also result in unit-testable
code that can also be easily rolled back and increase team productivity. The
baseline for traditional code review processes using metrics such as code
review duration, bug regression rate, revision count was measured. These
metrics were then compared with results from the proposed code review process
that used structured unit testable templated code. The performance on 2 large
enterprise level applications spanning over 2 years and 9 feature and
maintenance release cycles was evaluated. The structured unit testable
templated code method resulted in a decrease in total code review time,
revision count and coding effort. It also decreased the number of live
production issues caused by code churn or side effects of bug fix when compared
to traditional code review process.


title: Anomalous ferroelectric switching dynamics in single crystalline SrTiO3

abstract:
  Pure SrTiO3 in bulk form is known to be an incipient ferroelectric where the
quantum fluctuations of lattice positions prevent long range ferroelectric
ordering at a finite temperature. We show evidence and identify the origin of
ferroelectric relaxation up to nearly room temperature in single crystalline
SrTiO3. Strikingly, the origin of the observed ferroelectric switching is
intrinsic which is the coherent switching of surface nanopolar regions and not
due to the nucleation and growth of domains, as described by the
Kolmogorov-Avrami-Ishibashi Model.


title:
Approximate pricing of European and Barrier claims in a local-stochastic
  volatility setting

abstract:
  We derive asymptotic expansions for the prices of a variety of European and
barrier-style claims in a general local-stochastic volatility setting. Our
method combines Taylor series expansions of the diffusion coefficients with an
expansion in the correlation parameter between the underlying asset and
volatility process. Rigorous accuracy results are provided for European-style
claims. For barrier-style claims, we include several numerical examples to
illustrate the accuracy and versatility of our approximations.


title:
Using Centroidal Voronoi Tessellations to Scale Up the Multi-dimensional
  Archive of Phenotypic Elites Algorithm

abstract:
  The recently introduced Multi-dimensional Archive of Phenotypic Elites
(MAP-Elites) is an evolutionary algorithm capable of producing a large archive
of diverse, high-performing solutions in a single run. It works by discretizing
a continuous feature space into unique regions according to the desired
discretization per dimension. While simple, this algorithm has a main drawback:
it cannot scale to high-dimensional feature spaces since the number of regions
increase exponentially with the number of dimensions. In this paper, we address
this limitation by introducing a simple extension of MAP-Elites that has a
constant, pre-defined number of regions irrespective of the dimensionality of
the feature space. Our main insight is that methods from computational geometry
could partition a high-dimensional space into well-spread geometric regions. In
particular, our algorithm uses a centroidal Voronoi tessellation (CVT) to
divide the feature space into a desired number of regions; it then places every
generated individual in its closest region, replacing a less fit one if the
region is already occupied. We demonstrate the effectiveness of the new
"CVT-MAP-Elites" algorithm in high-dimensional feature spaces through
comparisons against MAP-Elites in maze navigation and hexapod locomotion tasks.


title: On the existence of $3$- and $4$-kernels in digraphs

abstract:
  Let $D = (V(D), A(D))$ be a digraph. A subset $S \subseteq V(D)$ is
$k$-independent if the distance between every pair of vertices of $S$ is at
least $k$, and it is $\ell$-absorbent if for every vertex $u$ in $V(D)
\setminus S$ there exists $v \in S$ such that the distance from $u$ to $v$ is
less than or equal to $\ell$. A $k$-kernel is a $k$-independent and
$(k-1)$-absorbent set. A kernel is simply a $2$-kernel.
  A classical result due to Duchet states that if every directed cycle in a
digraph $D$ has at least one symmetric arc, then $D$ has a kernel. We propose a
conjecture generalizing this result for $k$-kernels and prove it true for $k =
3$ and $k = 4$.


title:
Simultaneous Configuration Formation and Information Collection by
  Modular Robotic Systems

abstract:
  We consider the configuration formation problem in modular robotic systems
where a set of singleton modules that are spatially distributed in an
environment are required to assume appropriate positions so that they can
configure into a new, user-specified target configuration, while simultaneously
maximizing the amount of information collected while navigating from their
initial to final positions. Each module has a limited energy budget to expend
while moving from its initial to goal location. To solve this problem, we
propose a budget-limited, heuristic search-based algorithm that finds a path
that maximizes the entropy of the expected information along the path. We have
analytically proved that our proposed approach converges within finite time.
Experimental results show that our planning approach has lower run-time than an
auction-based allocation algorithm for selecting modules' spots.


title:
Direct determination of zero-field splitting for single Co$^{2+}$ ion
  embedded in a CdTe/ZnTe quantum dot

abstract:
  When Co$^{2+}$ impurity is embedded in semiconductor structure, crystal
strain strongly influences zero-filed splitting between Co$^{2+}$ states with
spin projection $S_z = \pm 3/2$ and $S_z = \pm 1/2$. Experimental evidences of
this effect have been given in previous studies, however direct measurement of
the strain induced zero-field splitting has been inaccessible so far. Here this
splitting is determined thanks to magneto-optical studies of individual
Co$^{2+}$ ion in epitaxial CdTe quantum dot in ZnTe barrier. Using partially
allowed optical transitions we measure strain induced zero-field splitting of
Co$^{2+}$ ion directly on excitonic photoluminescence spectrum. Moreover, by
observation of anticrossing of $S_z = + 3/2$ and $S_z = - 1/2$ Co$^{2+}$ spin
states in magnetic field, we determine axial and in-plane components of crystal
field acting on Co$^{2+}$. Proposed technique can be applied for optical
determination of zero-field splitting of other transition metal ions in quantum
dots.


title: A Devastating Example for the Halfer Rule

abstract:
  How should we update de dicto beliefs in the face of de se evidence? The
Sleeping Beauty problem divides philosophers into two camps, halfers and
thirders. But there is some disagreement among halfers about how their position
should generalize to other examples. A full generalization is not always given;
one notable exception is the Halfer Rule, under which the agent updates her
uncentered beliefs based on only the uncentered part of her evidence. In this
brief article, I provide a simple example for which the Halfer Rule prescribes
credences that, I argue, cannot be reasonably held by anyone. In particular,
these credences constitute an egregious violation of the Reflection Principle.
I then discuss the consequences for halfing in general.


title: Gravitational Collapse in Repulsive $R+\mu^4/R$ Gravity

abstract:
  In this paper we work out collapsing conditions for a spherical star in the
weak field limit of the $R+\mu^4/R$ gravity and discuss the importance of the
parameter $\mu$ to generate different criteria in the theory. Such criteria are
proved to be resulting in a variety of different fates for the evolution of the
outer shells of stars. Furthermore, we investigate the special case of
violating the first junction condition and point out corresponding
contradictions to the normal cases. These results show that the consistency of
the $R+\mu^4/R$ theory of gravity with the common astrophysical predictions
relies highly on the adoption of the parameter $\mu$ and satisfaction/violation
of the first junction condition. For those anomalous results, further
observational attempts are mandatory.


title: Deep Amortized Inference for Probabilistic Programs

abstract:
  Probabilistic programming languages (PPLs) are a powerful modeling tool, able
to represent any computable probability distribution. Unfortunately,
probabilistic program inference is often intractable, and existing PPLs mostly
rely on expensive, approximate sampling-based methods. To alleviate this
problem, one could try to learn from past inferences, so that future inferences
run faster. This strategy is known as amortized inference; it has recently been
applied to Bayesian networks and deep generative models. This paper proposes a
system for amortized inference in PPLs. In our system, amortization comes in
the form of a parameterized guide program. Guide programs have similar
structure to the original program, but can have richer data flow, including
neural network components. These networks can be optimized so that the guide
approximately samples from the posterior distribution defined by the original
program. We present a flexible interface for defining guide programs and a
stochastic gradient-based scheme for optimizing guide parameters, as well as
some preliminary results on automatically deriving guide programs. We explore
in detail the common machine learning pattern in which a 'local' model is
specified by 'global' random values and used to generate independent observed
data points; this gives rise to amortized local inference supporting global
model learning.


title: Analysis of the (CR) equation in higher dimensions

abstract:
  This paper is devoted to the analysis of the continuous resonant (CR)
equation, in dimensions greater than 2. This equation arises as the large box
(or high frequency) limit of the nonlinear Schrodinger equation on the torus,
and was derived in a companion paper by the same authors. We initiate the
investigation of the structure of (CR), its local well-posedness, and the
existence of stationary waves.


title: Topological order and equilibrium in a condensate of exciton-polaritons

abstract:
  We report the observation of the Berezinskii-Kosterlitz-Thouless transition
for a 2D gas of exciton-polaritons, and through the joint measurement of the
first-order coherence both in space and time we bring compelling evidence of a
thermodynamic equilibrium phase transition in an otherwise open
driven/dissipative system. This is made possible thanks to long polariton
lifetimes in high-quality samples with small disorder and in a reservoir-free
region far away from the excitation spot, that allow topological ordering to
prevail. The observed quasi-ordered phase, characteristic for an equilibrium 2D
bosonic gas, with a decay of coherence in both spatial and temporal domains
with the same algebraic exponent, is reproduced with numerical solutions of
stochastic dynamics, proving that the mechanism of pairing of the topological
defects (vortices) is responsible for the transition to the algebraic order.
Finally, measurements in the weak-coupling regime confirm that polariton
condensates are fundamentally different from photon lasers and constitute
genuine quantum degenerate macroscopic states.


title: Heavy right-handed neutrino dark matter in left-right models

abstract:
  We show that in a class of non-supersymmetric left-right extensions of the
Standard Model (SM), the lightest right-handed neutrino (RHN) can play the role
of thermal Dark Matter (DM) in the Universe for a wide mass range from TeV to
PeV. Our model is based on the gauge group $SU(3)_c \times SU(2)_L\times
SU(2)_R\times U(1)_{Y_L}\times U(1)_{Y_R}$ in which a heavy copy of the SM
fermions are introduced and the stability of the RHN DM is guaranteed by an
automatic $Z_2$ symmetry present in the leptonic sector. In such models the
active neutrino masses are obtained via the type-II seesaw mechanism. We find a
lower bound on the RHN DM mass of order TeV from relic density constraints, as
well as an unitarity upper bound in the multi-TeV to PeV scale, depending on
the entropy dilution factor. The RHN DM could be made long-lived by
soft-breaking of the $Z_2$ symmetry and provides a concrete example of decaying
DM interpretation of the PeV neutrinos observed at IceCube.


title:
Emergence of ferroelectric switching in self organized Pr0.67Ca0.33MnO3
  nanocrystal array

abstract:
  We discuss the emergence of low dimensional ferroelectricity in
self-organized Pr0.67Ca0.33MnO3 nanocrystalline arrays deposited on Si
substrate. We observe sharp switching of electric polarization under external
electric eld with nearly rectangular hysteresis loops which persist up to 150
K. We discuss the polarization switching kinetics within the framework of
Kolmogorov-Avrami-Ishibashi Model which gives maximum domain wall speed of ~1
m/s. Polarized Raman spectroscopy shows evidence of isolated ferroelectric
domains even at room temperature.


title: Moment-sequence transforms

abstract:
  We classify all functions which, when applied term by term, leave invariant
the sequences of moments of positive measures on the real line. Rather
unexpectedly, these functions are built of absolutely monotonic components, or
reflections of them, with possible discontinuities at the endpoints. Even more
surprising is the fact that functions preserving moments of three point masses
must preserve moments of all measures. Our proofs exploit the semidefiniteness
of the associated Hankel matrices and the complete monotonicity of the Laplace
transforms of the underlying measures. As a byproduct, we characterize the
entrywise transforms which preserve totally non-negative Hankel matrices, and
those which preserve all totally non-negative matrices. The latter class is
surprisingly rigid: such maps must be constant or linear. We also examine
transforms in the multivariable setting, which reveals a new class of piecewise
absolutely monotonic functions.


title:
Gerstenhaber bracket on the Hochschild cohomology via an arbitrary
  resolution

abstract:
  We prove formulas of different types that allow to calculate the Gerstenhaber
bracket on the Hochschild cohomology of an algebra using some arbitrary
projective bimodule resolution for it. Using one of these formulas, we give a
new short proof of the derived invariance of the Gerstenhaber algebra structure
on Hochschild cohomology. Also we give some new formulas for the Connes'
differential on the Hochschild homology that lead to formulas for BV
differential on the Hochschild cohomology in the case of symmetric algebras.
Finally, we use one of the obtained formulas to get a full description of the
BV structure and, correspondingly, the Gerstenhaber algebra structure on the
Hochschild cohomology of a class of symmetric algebras.


title: Product measures without utilizing integrals

abstract: We show that product measures can be handled without resorting to integrals.