title: Momentum space topology of QCD

abstract:
  We discuss the possibility to consider quark matter as the topological
material. We consider hadronic phase (HP), the quark - gluon plasma phase
(QGP), and the hypothetical color - flavor locking (CFL) phase. In those phases
we identify the relevant topological invariants in momentum space. The
formalism is developed, which relates those invariants and massless fermions
that reside on vortices and at the interphases. This formalism is illustrated
by the example of vortices in the CFL phase.


title: Role of dissipation in realistic Majorana nanowires

abstract:
  We carry out a realistic simulation of Majorana nanowires in order to
understand the latest high- quality experimental data [H. Zhang et al.,
arXiv:1603.04069 (2016)] and, in the process, develop a comprehensive picture
for what physical mechanisms may be operational in realistic nanowires leading
to discrepancies between minimal theory and experimental observations (e.g.,
weakness and broadening of the zero-bias peak and breaking of particle-hole
symmetry). Our focus is on understanding specific intriguing features in the
data, and our goal is to establish matters of principle controlling the physics
of the best possible nanowires available in current experiments. We identify
dissipation, finite temperature, multi-sub-band effects, and the finite tunnel
barrier as the four most important physical mechanisms controlling the
zero-bias conductance peak. Our theoretical results including these realistic
effects agree well with the best available experimental data in ballistic
nanowires.


title: On the stability of a space vehicle riding on an intense laser beam

abstract:
  The Breakthrough Starshot Initiative is suggested to develop the concept of
propelling a nano-scale spacecraft by the radiation pressure of an intense
laser beam. If such a nanocraft could be accelerated to 20 percent of light
speed, it could reach the vicinity of our nearest potentially habitable
exoplanet within our life time and capture its images and obtain other
scientific data. In this project the nanocraft is a gram-scale robotic
spacecraft comprising two main parts: StarChip and Lightsail.
  To achieve the goal of the project it is necessary to solve a number of
outstanding scientific problems. One of these tasks is to make sure that the
nanocraft position and orientation inside the intense laser beam column is
stable. The nanocraft driven by intense laser beam pressure acting on its
Lightsail is sensitive to the torques and lateral forces reacting on the
surface of the sail. These forces influence the orientation and lateral
displacement of the spacecraft, thus affecting its dynamics. If unstable the
nanocraft might be expelled from the area of laser beam. In choosing the models
for nanocraft stability studies we are using several assumptions: 1.
configuration of nanocraft is treated as rigid body (applicability of Euler
equations); 2. flat or concave shape of circular sail; 3. mirror reflection of
laser beam from surface of the Lightsail. We found conditions of position
stability for spherical and conical shape of the sail. The simplest stable
configurations require the StarChip to be removed from the sail to make the
distance to the center of mass of nanocraft bigger than curvature radius of the
sail. Stability criteria do not require the spinning of the nanocraft. A flat
sail is never stable (even with spinning).


title:
Black TiO2 nanotubes formed by high energy proton implantation show
  noble-metal-co-catalyst free photocatalytic H2-evolution

abstract:
  We apply high-energy proton ion-implantation to modify TiO2 nanotubes
selectively at their tops. In the proton-implanted region we observe the
creation of intrinsic co-catalytic centers for photocatalytic H2-evolution. We
find proton implantation to induce specific defects and a characteristic
modification of the electronic properties not only in nanotubes but also on
anatase single crystal (001) surfaces. Nevertheless, for TiO2 nanotubes a
strong synergetic effect between implanted region (catalyst) and implant-free
tube segment (absorber) can be obtained.


title:
Scattering states of position-dependent mass Schr\"odinger equation with
  non central potential

abstract:
  In this paper, we study the time-independent Schr\"odinger equation within
the formalism of position dependent effective mass. For a generalized
decomposition of the non-central effective potential, the deformed
Schr\"odinger equation can be easily solved analytically through separation of
variables. The energy eigenvalues and the normalization constant of the radial
wave functions are obtained, as well as the scattering phase shifts.


title: One-Dimensional Random Walk in Multi-Zone Environment

abstract:
  We study a symmetric random walk (RW) in one spatial dimension in
environment, formed by several zones of finite width, where the probability of
transition between two neighboring points and corresponding diffusion
coefficient are considered to be differently fixed. We derive analytically the
probability to find a walker at the given position and time. The probability
distribution function is found and has no Gaussian form because of properties
of adsorption in the bulk of zones and partial reflection at the separation
points. Time dependence of the mean squared displacement of a walker is studied
as well and revealed the transient anomalous behavior as compared with ordinary
RW.


title: Of Mountains and Molehills : Gravitational Waves from Neutron Stars

abstract:
  Surface asymmetries of accreting neutron stars are investigated for their
mass quadrupole moment content. Though the amplitude of the gravitational waves
from such asymmetries seem to be beyond the limit of detectability of the
present generation of detectors, it appears that rapidly rotating neutron stars
with strong magnetic fields residing in HMXBs would be worth considering for
targeted search for continuous gravitational waves with the next generation of
instruments.


title: Landau levels for electromagnetic wave

abstract:
  In this paper we show that the frequencies of propagating electromagnetic
wave (photon) in rotating dielectric medium obey Landau quantization. We show
that the degeneracy of right and left helicities of photons is broken on the
lowest Landau level. In homogeneous space this level is shown to be helical,
i.e. left and right helical photons counter-propagate. This leads to helical
vortical effect for photons.


title: Gravitational Waves- a new window to Cosmos

abstract:
  With the detection of Gravitational waves just about an year ago Einstein`s
general theory of relativity- a space-time theory of gravity, got established
on a firmer footing than any other theory in physics. Gravitational waves are
just propagating disturbances in the gravitational field of extremely strong
sources caused by some catastrophic event associated with cosmic bodies, like
binary black hole coalescence, or neutron star mergers. As these events happen
very far away in cosmos, and the signal strength would be extremely weak, it
requires extraordinary detection and analysis technology to observe an event on
earth. Luckily the joint collaboration LIGO-VIRGO, have so far detected two
events in September and December of 2015 during their analysis of observations
made with the laser interferometers over the last few observing sessions. The
talk will give a brief theoretical sketch of the analysis required for
describing the waves resulting from mass motion in the realm of general
relativity, and point out, the serious and sincere efforts of the past fifty
years that went into the final success. An attempt will be made to point out
the enormous scope that is available for the new generation of students and
researchers in pursuing the topic as a new window for possibly viewing the
Universe with the implications for the studies of Dark matter, Dark energy and
Cosmology as a whole.


title:
Modified Hawking temperature and entropic force: a prescription in FRW
  model

abstract:
  The idea of Verlinde that gravity is an entropic force caused by information
changes associated with the positions of material bodies, is used in the
present work for the FRW model of the Universe. Using modified Hawking
temperature, the Friedmann equations are derived on any horizon. For the
validity of the first law of thermodynamics (i.e., Clausius relation) it is
found that there is modification of Bekenstein entropy on the horizon. However,
using equipartition law of energy, Bekenstein entropy is recovered.


title:
Thermodynamics and Superradiant Phase Transitions in a three-level Dicke
  Model

abstract:
  We analyse the thermodynamic properties of a generalised Dicke model, i.e. a
collection of three-level systems interacting with two bosonic modes. We show
that at finite temperatures the system undergoes first-order phase transitions
only, which is in contrast to the zero-temperature case where a second-order
phase transition exist as well. We discuss the free energy and prominent
expectation values. The limit of vanishing temperature is discussed as well.


title: Renormalized jellium model for colloidal mixtures

abstract:
  In an attempt to quantify the role of polydispersity in colloidal
suspensions, we present an efficient implementation of the renormalized jellium
model for a mixture of spherical charged colloids. The different species may
have different size, charge and density. Advantage is taken from the fact that
the electric potential pertaining to a given species obeys a Poisson's equation
that is species independent; only boundary conditions do change from a species
to the next. All species are coupled through the renormalized background
(jellium) density, that is determined self-consistently. The corresponding
predictions are compared to the results of Monte Carlo simulations of binary
mixtures, where Coulombic interactions are accounted for exactly, at the
primitive model level (structureless solvent with fixed dielectric
permittivity). An excellent agreement is found.


title: CAKE: The Coincidence Array for K600 Experiments

abstract:
  The combination of a magnetic spectrometer and ancillary detectors such as
silicon detectors is a powerful tool for the study of nuclear reactions and
nuclear structure. This paper discusses the recently commissioned silicon array
called the CAKE which is designed for use with the K600 magnetic spectrometer
at iThemba LABS.


title:
Unifying Type II Supernova Light Curves with Dense Circumstellar
  Material

abstract:
  A longstanding problem in the study of supernovae (SNe) has been the
relationship between the Type IIP and Type IIL subclasses. Whether they come
from distinct progenitors or they are from similar stars with some property
that smoothly transitions from one class to another has been the subject of
much debate. Here we show using one-dimensional radiation-hydrodynamic SN
models that the multi-band light curves of SNe IIL are well fit by ordinary red
supergiants surrounded by dense circumstellar material (CSM). The inferred
extent of this material, coupled with a typical wind velocity of ~10-100 km/s,
suggests enhanced activity by these stars during the last ~months to ~years of
their lives, which may be connected with advanced stages of nuclear burning.
Furthermore, we find that even for more plateau-like SNe that dense CSM
provides a better fit to the first ~20 days of their light curves, indicating
that the presence of such material may be more widespread than previously
appreciated. Here we choose to model the CSM with a wind-like density profile,
but it is unclear whether this just generally represents some other mass
distribution, such as a recent mass ejection, thick disk, or even inflated
envelope material. Better understanding the exact geometry and density
distribution of this material will be an important question for future studies.


title:
The Highest-Energy Cosmic Rays Cannot be Dominantly Protons from Steady
  Sources

abstract:
  The bulk of observed ultrahigh energy cosmic rays could be light or heavier
elements, and originate from an either steady or transient population of
sources. This leaves us with four general categories of sources. Energetic
requirements set a lower limit on single source luminosities, while the
distribution of particle arrival directions in the sky sets a lower limit on
the source number density. The latter constraint depends on the angular
smearing in the skymap due to the magnetic deflections of the charged particles
during their propagation from the source to the Earth. We contrast these limits
with the luminosity functions from surveys of existing luminous steady objects
in the nearby universe, and strongly constrain one of the four categories of
source models, namely, steady proton sources. The possibility that cosmic rays
with energy $> 8\times 10^{19}\,$eV are dominantly pure protons coming from
steady sources is excluded at 95\% confidence level, under the safe assumption
that protons experience less than $30^\circ$ magnetic deflection on flight.


title:
Constraints on the bulk Lorentz factor of Gamma-Ray Burst jets from
  Fermi/LAT upper limits

abstract:
  It is largely recognized that Gamma-Ray Burst (GRB) jets involve
ultra-relativistic motion. However, the value of the Lorentz factor Gamma_0 is
still not clear and only lower limits are known for most bursts. We suggest
here a new method to obtain upper limits on Gamma_0. The early high-energy
synchrotron afterglow flux depends strongly on Gamma_0. Upper limits on GeV
emission therefore provide uppers limit on Gamma_0. Applying this method to 190
Fermi GRBs that have not been detected by the Fermi-LAT we place upper limits
on the high-energy afterglow flux, and in turn on Gamma_0. For bursts at a
typical redshift z=2, we find values of the order of 200 (and above) for a
homogeneous density medium, and in the range 100-400 for a wind-like medium.
These upper limits are consistent with (and are very close to) lower limits and
direct estimates inferred using other methods, suggesting that the typical
Lorentz factors of GRB jets are of order a few hundred.


title:
Observation of discrete time-crystalline order in a disordered dipolar
  many-body system

abstract:
  Understanding quantum dynamics away from equilibrium is an outstanding
challenge in the modern physical sciences. It is well known that
out-of-equilibrium systems can display a rich array of phenomena, ranging from
self-organized synchronization to dynamical phase transitions. More recently,
advances in the controlled manipulation of isolated many-body systems have
enabled detailed studies of non-equilibrium phases in strongly interacting
quantum matter. As a particularly striking example, the interplay of periodic
driving, disorder, and strong interactions has recently been predicted to
result in exotic "time-crystalline" phases, which spontaneously break the
discrete time-translation symmetry of the underlying drive. Here, we report the
experimental observation of such discrete time-crystalline order in a driven,
disordered ensemble of $\sim 10^6$ dipolar spin impurities in diamond at
room-temperature. We observe long-lived temporal correlations at integer
multiples of the fundamental driving period, experimentally identify the phase
boundary and find that the temporal order is protected by strong interactions;
this order is remarkably stable against perturbations, even in the presence of
slow thermalization. Our work opens the door to exploring dynamical phases of
matter and controlling interacting, disordered many-body systems.

categories: quant-ph cond-mat.dis-nn cond-mat.mes-hall cond-mat.str-el physics.atom-ph


title:
Evidence for strong evolution in galaxy environmental quenching
  efficiency between z = 1.6 and z = 0.9

abstract:
  We analyse the evolution of environmental quenching efficiency, the fraction
of quenched cluster galaxies that would be star-forming if they were in the
field, as a function of redshift in 14 spectroscopically confirmed galaxy
clusters with 0.87 < z < 1.63 from the Spitzer Adaptation of the Red-Sequence
Cluster Survey (SpARCS). The clusters are the richest in the survey at each
redshift. Passive fractions rise from $42_{-13}^{+10}$\% at z ~ 1.6 to
$80_{-9}^{+12}$\% at z ~ 1.3 and $88_{-3}^{+4}$\% at z < 1.1, outpacing the
change in passive fraction in the field. Environmental quenching efficiency
rises dramatically from $16_{-19}^{+15}$ at z ~ 1.6 to $62_{-15}^{+21}\% at z ~
1.3 and $73_{-7}^{+8}$\% at z $\lesssim$ 1.1. This work is the first to show
direct observational evidence for a rapid increase in the strength of
environmental quenching in galaxy clusters at z ~ 1.5, where simulations show
cluster-mass halos undergo non-linear collapse and virialisation.


title: Cornering Natural SUSY at LHC Run II and Beyond

abstract:
  We derive the latest constraints on various simplified models of natural SUSY
with light higgsinos, stops and gluinos, using a detailed and comprehensive
reinterpretation of the most recent 13 TeV ATLAS and CMS searches with $\sim
15$ fb$^{-1}$ of data. We discuss the implications of these constraints for
fine-tuning of the electroweak scale. While the most "vanilla" version of SUSY
(the MSSM with $R$-parity and flavor-degenerate sfermions) with 10% fine-tuning
is ruled out by the current constraints, models with decoupled valence squarks
or reduced missing energy can still be fully natural. However, in all of these
models, the mediation scale must be extremely low ($<100$ TeV). We conclude by
considering the prospects for the high-luminosity LHC era, where we expect the
current limits on particle masses to improve by up to $\sim 1$ TeV, and discuss
further model-building directions for natural SUSY that are motivated by this
work.


title: Lepton-Flavor Violating Mediators

abstract:
  We present a framework where dark matter interacts with the Standard Model
through a light, spin-0 mediator that couples chirally to pairs of
different-flavor leptons. This flavor violating final state weakens bounds on
new physics coupled to leptons from terrestrial experiments and cosmic-ray
measurements. As an example, we apply this framework to construct a model for
the Fermi-LAT excess of GeV $\gamma$-rays from the galactic center. We comment
on the viability of this portal for self-interacting dark matter explanations
of small scale structure anomalies and embeddings in flavor models. Models of
this type are shown to be compatible with the muon anomalous magnetic moment
anomaly. We review current experimental constraints and identify possible
future theoretical and experimental directions.


title:
A new catalog of homogenised absorption line indices for Milky Way
  globular clusters from high-resolution integrated spectroscopy

abstract:
  We perform integrated spectroscopy of 24 Galactic globular clusters. Spectra
are observed from one core radius for each cluster with a high wavelength
resolution of ~2.0 A FWHM. In combination with two existing data sets from
Puzia et al. (2002) and Schiavon et al. (2005), we construct a large database
of Lick spectral indices for a total of 53 Galactic globular clusters with a
wide range of metallicities, -2.4 < [Fe/H] < 0.1, and various horizontal-branch
morphologies. The empirical index-to-metallicity conversion relationships are
provided for the 20 Lick indices for the use of deriving metallicities for
remote, unresolved stellar systems.


title: Crossover from quantum to classical transport

abstract:
  Understanding the crossover from quantum to classical transport phenomena has
become of fundamental importance not only for technological applications due to
the creation of sub-10nm transistors - an important building block of our
modern life - but also for elucidating the role played by quantum mechanics in
the evolutionary fitness of biological complexes. This article provides a basic
introduction into the nature of charge and energy transport in the quantum and
classical regimes. It discusses the characteristic transport properties in both
limits, and demonstrates how they can be connected through the loss of quantum
mechanical coherence. The salient features of the crossover physics are
identified, and their importance in opening new transport regimes and in
understanding efficient and robust energy transport in biological complexes are
demonstrated.


title: Complexity of Formation in Holography

abstract:
  It was recently conjectured that the quantum complexity of a holographic
boundary state can be computed by evaluating the gravitational action on a bulk
region known as the Wheeler-DeWitt patch. We apply this complexity=action
duality to evaluate the `complexity of formation' (arXiv:1509.07876,
arXiv:1512.04993), i.e., the additional complexity arising in preparing the
entangled thermofield double state with two copies of the boundary CFT compared
to preparing the individual vacuum states of the two copies. We find that for
boundary dimensions $d>2$, the difference in the complexities grows linearly
with the thermal entropy at high temperatures. For the special case $d=2$, the
complexity of formation is a fixed constant, independent of the temperature. We
compare these results to those found using the complexity=volume duality.


title:
Fundamental matrices and Green matrices for non-homogeneous elliptic
  systems

abstract:
  In this paper, we establish existence, uniqueness, and scale-invariant
estimates for fundamental solutions of non-homogeneous second order elliptic
systems with bounded measurable coefficients in $\mathbb{R}^n$ and for the
corresponding Green functions in arbitrary open sets. We impose certain
non-homogeneous versions of de Giorgi-Nash-Moser bounds on the weak solutions
and investigate in detail the assumptions on the lower order terms sufficient
to guarantee such conditions.


title:
Molecular gas properties of a lensed star-forming galaxy at z~3.6: a
  case study

abstract:
  We report on the galaxy MACSJ0032-arc at z=3.6314 discovered during the
Herschel Lensing snapshot Survey of massive galaxy clusters, and strongly
lensed by the cluster MACSJ0032.1+1808. The successful detections of its
rest-frame UV, optical, FIR, millimeter, and radio continua, and of its CO
emission enable us to characterize, for the first time at such a high redshift,
the stellar, dust, and molecular gas properties of a compact star-forming
galaxy with a size smaller than 2.5 kpc, a fairly low stellar mass of 4.8x10^9
Msun, and a moderate IR luminosity of 4.8x10^11 Lsun. We find that the bulk of
the molecular gas mass and star formation seems to be spatially decoupled from
the rest-frame UV emission. About 90% of the total star formation rate is
undetected at rest-frame UV wavelengths because of severe obscuration by dust,
but is seen through the thermal FIR dust emission and the radio synchrotron
radiation. The observed CO(4-3) and CO(6-5) lines demonstrate that high-J
transitions, at least up to J=6, remain excited in this galaxy, whose CO
spectral line energy distribution resembles that of high-redshift submm
galaxies, even though the IR luminosity of MACSJ0032-arc is ten times lower.
This high CO excitation is possibly due to the compactness of the galaxy. We
find evidence that this high CO excitation has to be considered in the balance
when estimating the CO-to-H2 conversion factor. The inferred depletion time of
the molecular gas in MACSJ0032-arc supports the decrease in the gas depletion
timescale of galaxies with redshift, although to a lesser degree than predicted
by galaxy evolution models. Instead, the measured molecular gas fraction as
high as 60-79% in MACSJ0032-arc favors the continued increase in the gas
fraction of galaxies with redshift as expected, despite the plateau observed
between z~1.5 and z~2.5.


title:
Search for heavy resonances decaying into a vector boson and a Higgs
  boson in final states with charged leptons, neutrinos, and b quarks

abstract:
  A search for heavy resonances decaying to a Higgs boson and a vector boson is
presented. The analysis is performed using data samples collected in 2015 by
the CMS experiment at the LHC in proton-proton collisions at a center-of-mass
energy of 13 TeV, corresponding to integrated luminosities of 2.2-2.5 inverse
femtobarns. The search is performed in channels in which the vector boson
decays into leptonic final states (Z to nu nu, W to l nu, and Z to l l, with l
= e, mu), while the Higgs boson decays to collimated b quark pairs detected as
a single massive jet. The discriminating power of a jet mass requirement and a
b jet tagging algorithm are exploited to suppress the standard model
backgrounds. The event yields observed in data are consistent with the
background expectation. In the context of a theoretical model with a heavy
vector triplet, a resonance with mass less than 2 TeV is excluded at 95%
confidence level. The results are also interpreted in terms of limits on the
parameters of the model, improving on the reach of previous searches.


title:
The Gribov problem in presence of background field for $SU(2)$
  Yang-Mills theory

abstract:
  The Gribov problem in the presence of a background field is analyzed: in
particular, we study the Gribov copies equation in the Landau-De Witt gauge as
well as the semi-classical Gribov gap equation. As background field, we choose
the simplest non-trivial one which corresponds to a constant gauge potential
with non-vanishing component along the Euclidean time direction. This kind of
constant non-Abelian background fields is very relevant in relation with (the
computation of) the Polyakov loop but it also appears when one considers the
non-Abelian Schwinger effect. We show that the Gribov copies equation is
affected directly by the presence of the background field, constructing an
explicit example. The analysis of the Gribov gap equation shows that the larger
the background field, the smaller the Gribov mass parameter. These results
strongly suggest that the relevance of the Gribov copies (from the path
integral point of view) decreases as the size of the background field
increases.


title: From weak cofibration categories to model categories

abstract:
  In [BaSc2] the authors introduced a much weaker homotopical structure than a
model category, called a "weak cofibration category". We further showed that a
small weak cofibration category induces in a natural way a model category
structure on its ind-category, provided the ind-category satisfies a certain
two out of three property. The purpose of this paper is to serve as a companion
to the papers above, proving results which say that if a certain property or
structure exists in the weak cofibration category, then the same property or
structure also holds in the induced model structure on the ind-category.
Namely, we consider the property of being left proper and the structures of a
monoidal category and a category tensored over a monoidal category (in a way
that is compatible with the weak cofibration structure). For the purpose of
future reference, we consider the more general situation where we only have an
"almost model structure" on the ind-category.


title: Time-independent wormholes

abstract:
  We study two-sided static wormholes with an exact Killing symmetry that
translates both mouths of the wormhole toward the future. This differs from the
familiar Kruskal wormhole whose time translation is future-directed only in one
asymptotic region and is instead past-directed in the other. Our spacetimes are
solutions to Einstein-Hilbert gravity sourced by scalar domain walls. Explicit
examples are found in the thin wall approximation. More generally, we show that
such spacetimes can arise in the presence of scalar fields with potentials that
are $C^1$ but not $C^2$ and find examples numerically. However, solutions with
an exact such Killing symmetry are forbidden when the scalar potential is
smooth. Finally, we consider the mutual information of boundary regions
associated with such wormholes in AdS/CFT. Although the interior of our
solutions are unstable, we find that even mutual informations between opposite
boundaries are already thermalized at any finite $t$ in the sense that they
agree with the $t\rightarrow \infty$ limit of results from the familiar
AdS-Kruskal solution.


title: Low rank matrix recovery from Clifford orbits

abstract:
  We prove that low-rank matrices can be recovered efficiently from a small
number of measurements that are sampled from orbits of a certain matrix group.
As a special case, our theory makes statements about the phase retrieval
problem. Here, the task is to recover a vector given only the amplitudes of its
inner product with a small number of vectors from an orbit. Variants of the
group in question have appeared under different names in many areas of
mathematics. In coding theory and quantum information, it is the complex
Clifford group; in time-frequency analysis the oscillator group; and in
mathematical physics the metaplectic group. It affords one particularly small
and highly structured orbit that includes and generalizes the discrete Fourier
basis: While the Fourier vectors have coefficients of constant modulus and
phases that depend linearly on their index, the vectors in said orbit have
phases with a quadratic dependence. In quantum information, the orbit is used
extensively and is known as the set of stabilizer states. We argue that due to
their rich geometric structure and their near-optimal recovery properties,
stabilizer states form an ideal model for structured measurements for phase
retrieval. Our results hold for $m\geq C \kappa_r r d \log(d)$ measurements,
where the oversampling factor k varies between $\kappa_r=1$ and $\kappa_r =
r^2$ depending on the orbit. The reconstruction is stable towards both additive
noise and deviations from the assumption of low rank. If the matrices of
interest are in addition positive semidefinite, reconstruction may be performed
by a simple constrained least squares regression. Our proof methods could be
adapted to cover orbits of other groups.


title: BONNSAI: correlated stellar observables in Bayesian methods

abstract:
  In an era of large spectroscopic surveys of stars and big data, sophisticated
statistical methods become more and more important in order to infer
fundamental stellar parameters such as mass and age. Bayesian techniques are
powerful methods because they can match all available observables
simultaneously to stellar models while taking prior knowledge properly into
account. However, in most cases it is assumed that observables are uncorrelated
which is generally not the case. Here, we include correlations in the Bayesian
code BONNSAI by incorporating the covariance matrix in the likelihood function.
We derive a parametrisation of the covariance matrix that, in addition to
classical uncertainties, only requires the specification of a correlation
parameter that describes how observables co-vary. Our correlation parameter
depends purely on the method with which observables have been determined and
can be analytically derived in some cases. This approach therefore has the
advantage that correlations can be accounted for even if information for them
are not available in specific cases but are known in general. Because the new
likelihood model is a better approximation of the data, the reliability and
robustness of the inferred parameters are improved. We find that neglecting
correlations biases the most likely values of inferred stellar parameters and
affects the precision with which these parameters can be determined. For
example, we apply our technique to massive OB stars, but emphasise that it is
valid for any type of stars. For effective temperatures and surface gravities
determined from atmosphere modelling, we find that masses can be underestimated
on average by $0.5\sigma$ and mass uncertainties overestimated by a factor of
about 2 when neglecting correlations. At the same time, the age precisions are
underestimated over a wide range of stellar parameters. [abridged]


title: Sextet Model with Wilson Fermions

abstract:
  We present new results from our ongoing study of the SU(3) sextet model with
two flavors in the two-index symmetric representation of the gauge group. In
the simulations use unimproved Wilson fermions to investigate the infrared
properties of the model. We have previously presented results for the spectrum
of the model in the weak coupling regime. Here, to better understand the
overall behavior of the lattice model, we map its non-trivial phase structure
in the space of bare parameters. At strong coupling, we observe a first order
phase transition when decreasing the bare quark mass. This first order
transition weakens when moving towards weaker couplings with an endpoint at a
finite value of the bare coupling, after which it appears to be a continuous
transition. We also investigate the behavior of the mass spectrum and
scale-setting observable, as a function of the quark mass, and show that their
qualitative behavior change significantly when moving from the strong coupling
into the weak coupling phase.


title:
Distributed Spatial Multiplexing Systems with Hardware Impairments and
  Imperfect Channel Estimation under Rank-$1$ Rician Fading Channels

abstract:
  The performance of a multiuser communication system with single-antenna
transmitting terminals and a multi-antenna base-station receiver is
analytically investigated. The system operates under independent and
non-identically distributed rank-$1$ Rician fading channels with imperfect
channel estimation and residual hardware impairments (compensation algorithms
are assumed, which mitigate the main impairments) at the transceiver. The
spatial multiplexing mode of operation is considered where all the users are
simultaneously transmitting their streams to the receiver. Zero-forcing is
applied along with successive interference cancellation (SIC) as a means for
efficient detection of the received streams. New analytical closed-form
expressions are derived for some important performance metrics, namely, the
outage probability and ergodic capacity of the entire system. Both the
analytical expressions and simulation results show the impact of imperfect
channel estimation and hardware impairments to the overall system performance
in the usage scenarios of massive MIMO and mmWave communication systems.


title: Gaussian Process Kernels for Popular State-Space Time Series Models

abstract:
  In this paper we investigate a link between state- space models and Gaussian
Processes (GP) for time series modeling and forecasting. In particular, several
widely used state- space models are transformed into continuous time form and
corresponding Gaussian Process kernels are derived. Experimen- tal results
demonstrate that the derived GP kernels are correct and appropriate for
Gaussian Process Regression. An experiment with a real world dataset shows that
the modeling is identical with state-space models and with the proposed GP
kernels. The considered connection allows the researchers to look at their
models from a different angle and facilitate sharing ideas between these two
different modeling approaches.


title: Composite Genus One Belyi Maps

abstract:
  Motivated by a demand for explicit genus 1 Belyi maps from theoretical
physics, we give an efficient method of explicitly computing genus one Belyi
maps by (1) composing covering maps from elliptic curves to the Riemann sphere
with simpler (univariate) genus zero Belyi maps, as well as by (2) composing
further with isogenies between elliptic curves. This gives many new explicit
dessins on the doubly periodic plane, including several which have been
realized in the physics literature as so-called brane-tilings in the context of
quiver gauge theories.


title:
Optimal Power Allocation and Active Interference Mitigation for Spatial
  Multiplexed MIMO Cognitive Systems

abstract:
  In this paper, the performance of an underlay multiple-input multiple-output
(MIMO) cognitive radio system is analytically studied. In particular, the
secondary transmitter operates in a spatial multiplexing transmission mode,
while a zero-forcing (ZF) detector is employed at the secondary receiver.
Additionally, the secondary system is interfered by multiple randomly
distributed single-antenna primary users (PUs). To enhance the performance of
secondary transmission, optimal power allocation is performed at the secondary
transmitter with a constraint on the interference temperature (IT) specified by
the PUs. The outage probability of the secondary receiver is explicitly derived
in an exact closed-form expression. Also, some special cases of practical
interest, including co-located PUs and massive MIMO, are discussed. Further, to
mitigate instantaneous excessive interference onto PUs caused by the
time-average IT, an iterative antenna reduction algorithm is developed for the
secondary transmitter and, accordingly, the average number of transmit antennas
is analytically computed. Extensive numerical and simulation results
corroborate the effectiveness of our analysis.


title: A statistical framework for fair predictive algorithms

abstract:
  Predictive modeling is increasingly being employed to assist human
decision-makers. One purported advantage of replacing human judgment with
computer models in high stakes settings-- such as sentencing, hiring, policing,
college admissions, and parole decisions-- is the perceived "neutrality" of
computers. It is argued that because computer models do not hold personal
prejudice, the predictions they produce will be equally free from prejudice.
There is growing recognition that employing algorithms does not remove the
potential for bias, and can even amplify it, since training data were
inevitably generated by a process that is itself biased. In this paper, we
provide a probabilistic definition of algorithmic bias. We propose a method to
remove bias from predictive models by removing all information regarding
protected variables from the permitted training data. Unlike previous work in
this area, our framework is general enough to accommodate arbitrary data types,
e.g. binary, continuous, etc. Motivated by models currently in use in the
criminal justice system that inform decisions on pre-trial release and
paroling, we apply our proposed method to a dataset on the criminal histories
of individuals at the time of sentencing to produce "race-neutral" predictions
of re-arrest. In the process, we demonstrate that the most common approach to
creating "race-neutral" models-- omitting race as a covariate-- still results
in racially disparate predictions. We then demonstrate that the application of
our proposed method to these data removes racial disparities from predictions
with minimal impact on predictive accuracy.


title: Dis-S2V: Discourse Informed Sen2Vec

abstract:
  Vector representation of sentences is important for many text processing
tasks that involve clustering, classifying, or ranking sentences. Recently,
distributed representation of sentences learned by neural models from unlabeled
data has been shown to outperform the traditional bag-of-words representation.
However, most of these learning methods consider only the content of a sentence
and disregard the relations among sentences in a discourse by and large.
  In this paper, we propose a series of novel models for learning latent
representations of sentences (Sen2Vec) that consider the content of a sentence
as well as inter-sentence relations. We first represent the inter-sentence
relations with a language network and then use the network to induce contextual
information into the content-based Sen2Vec models. Two different approaches are
introduced to exploit the information in the network. Our first approach
retrofits (already trained) Sen2Vec vectors with respect to the network in two
different ways: (1) using the adjacency relations of a node, and (2) using a
stochastic sampling method which is more flexible in sampling neighbors of a
node. The second approach uses a regularizer to encode the information in the
network into the existing Sen2Vec model. Experimental results show that our
proposed models outperform existing methods in three fundamental information
system tasks demonstrating the effectiveness of our approach. The models
leverage the computational power of multi-core CPUs to achieve fine-grained
computational efficiency. We make our code publicly available upon acceptance.


title: Origin of Kinks in Energy Dispersion of Strongly Correlated Matter

abstract:
  We investigate the origin of ubiquitous low energy kinks found in Angle
Resolved Photoemission (ARPES) experiments in a variety of correlated matter.
Such kinks are unexpected from weakly interacting electrons and hence
identifying their origin should lead to fundamental insights in strongly
correlated matter. We devise a protocol for extracting the kink momentum and
energy from the experimental data which relies solely on the two asymptotic
tangents of each dispersion curve, away from the feature itself. It is thereby
insensitive to the different shapes of the kinks as seen in experiments. The
body of available data is then analyzed using this method. We proceed to
discuss two alternate theoretical explanations of the origin of the kinks. Some
theoretical proposals invoke local Bosonic excitations (Einstein phonons or
other modes with spin or charge character), located exactly at the energy of
observed kinks, leading to a momentum independent self energy of the electrons.
A recent alternate is the theory of extremely correlated Fermi liquids (ECFL).
This theory predicts kinks in the dispersion arising from a momentum dependent
self energy of correlated electrons. We present the essential results from both
classes of theories, and identify experimental features that can help
distinguish between the two mechanisms. The ECFL theory is found to be
consistent with currently available data on kinks in the nodal direction of
cuprate superconductors, but conclusive tests require higher resolution energy
distribution curve data.


title:
Higher-curvature Corrections to Holographic Entanglement with Momentum
  Dissipation

abstract:
  We study the effects of Gauss-Bonnet corrections on some nonlocal probes
(entanglement entropy, $n$-partite information and Wilson loop) in the
holographic model with momentum relaxation. Higher-curvature terms as well as
scalar fields make in fact nontrivial correction to the coefficient of
universal term in entanglement entropy. We use holographic methods to study
such corrections. Moreover, holographic calculation indicates that mutual and
tripartite information undergo a transition beyond which they identically
change their values. We find that the behavior of transition curves depends on
the sign of the Gauss-Bonnet coupling $\lambda$. The transition for $\lambda>0$
takes place in larger separation of subsystems than that of $\lambda<0$.
Finally, we examine the behavior of modified part of the force between external
point-like objects as a function of Gauss-Bonnet coupling and its sign.


title: Octonions in random matrix theory

abstract:
  The octonions are one of the four normed division algebras, together with the
real, complex and quaternion number systems. The latter three hold a primary
place in random matrix theory, where in applications to quantum physics they
are determined as the entries of ensembles of Hermitian random by symmetry
considerations. Only for $N=2$ is there an existing analytic theory of
Hermitian random matrices with octonion entries. We use a Jordan algebra
viewpoint to provide an analytic theory for $N=3$. We then proceed to consider
the matrix structure $X^\dagger X$, when $X$ has random octonion entries.
Analytic results are obtained from $N=2$, but are observed to break down in the
$3 \times 3$ case.


title:
Scalable, chip-based optically-controlled gates for quantum information
  processing

abstract:
  Here we present a simple and robust method to build on-the-fly configurable
quantum gates based on a photonic exchange between quantum nodes. The idea is
based on a high reflectivity of Bragg grating structures near resonant
wavelengths. The control is exerted by applying an external strongly
off-resonant or even a static electromagnetic field and taking advantage of the
Kerr effect. When the nonlinear phase shift is strong enough, the Bragg mirror
disappears, thereby allowing a transmission of a wave packet from one node to
another. An example of a protocol for quantum logic gates that relies on this
framework is offered.


title: The linear-non-linear frontier for the Goldstone Higgs

abstract:
  The minimal $SO(5)/SO(4)$ sigma model is used as a template for the
ultraviolet completion of scenarios in which the Higgs particle is a low-energy
remnant of some high-energy dynamics, enjoying a (pseudo) Nambu-Goldstone boson
ancestry. Varying the $\sigma$ mass allows to sweep from the perturbative
regime to the customary non-linear implementations. The low-energy benchmark
effective non-linear Lagrangian for bosons and fermions is obtained,
determining as well the operator coefficients including linear corrections. At
first order in the latter, three effective bosonic operators emerge which are
independent of the explicit soft breaking assumed. The Higgs couplings to
vector bosons and fermions turn out to be quite universal: the linear
corrections are proportional to the explicit symmetry breaking parameters.
Furthermore, we define an effective Yukawa operator which allows a simple
parametrization and comparison of different heavy fermion ultraviolet
completions. In addition, one particular fermionic completion is explored in
detail, obtaining the corresponding leading low-energy fermionic operators.


title:
Generalizing second order macroscopic models via relative velocity of
  disturbances propagation in traffic flow

abstract:
  In this paper, we present a new approach that generalizes the existing
second-order hydrodynamic traffic models. In the proposed approach, we use the
expression for the relative velocity of disturbances propagation in traffic
flow. We show that properties of any phenomenological model are fully defined
by how the relative velocity of disturbances propagation expressed in the
model. We verify the proposed approach through simulations of the Interstate
580 freeway segment in California, USA, with traffic measurements from the
Performance Measurement System (PeMS).


title:
Derivation, calibration and verification of macroscopic model for urban
  traffic flow. Part 2

abstract:
  In this paper, we propose a unified procedure for calibration of macroscopic
second-order multilane traffic models. The focus is on calibrating the
fundamental diagram using the combination stationary detector data and GPS
traces. GPS traces are used in estimation of the deceleration wave speed. Thus
calibrated model adequately represents the three phases of traffic: free flow,
synchronized flow and the wide moving jam. The proposed approach was validated
in simulation using stationary detection data and GPS traces from the Moscow
Ring Road. Simulation showed that the proposed second-order model is more
accurate than the first-order LWR model.


title:
Scaling properties of first-passage quantities on the fractal and
  transfractal scale free networks

abstract:
  In this paper, we consider the random walk process on a kind of fractal (or
transfractal) scale free networks, which also called as $(u,v)$ flowers, and we
focus on the global first passage time (GFPT) and first return time (FRT).
Here, we present method to derive exactly the probability generation function,
mean and variance of the GFPT and FRT for a given hub (i.e., node with the
highest degree) and then the scaling properties of the mean and the variance of
the GFPT and FRT are disclosed. Our results show that, for the case of $u>1$,
while the networks are fractals, the mean of the GFPT scales with the volume of
the network as $\langle GMFPT_t\rangle \sim N_t^{{2}/{d_s}}$, where $\langle *
\rangle$ denotes the mean of random variable $*$, $N_t$ is the volume of the
network with generation $t$ and $d_s$ is the spectral dimension of the network;
but, for the case of $u=1$, while the networks are nonfractals, the mean of the
GFPT scales as $\langle GMFPT_t\rangle \sim N_t^{{2}/{\tilde{d}_s}}$, where
$\tilde{d}_s$ is the transspectral dimension of the network, which is
introduced in this paper. Results also show that, the variance of the GFPT
scales as $Var(GFPT_t) \sim \langle GFPT_{t}\rangle^2$, where $Var(*)$ denotes
variance of of random variable $*$; whereas the variance of the FRT scales as
$Var(FRT_t) \sim \langle FRT_{t} \rangle \langle GFPT_{t}\rangle$.
%$Var(GFPT_t) \sim \langle GFPT_{t}\rangle^2$ and $Var(FRT_t) \sim \langle
FRT_{t} \rangle \langle GFPT_{t}\rangle$, where $Var(GFPT_t)$ and $Var(FRT_t)$
denote the variance of the GFPT and the FRT, $\langle GFPT_{t}\rangle$ and
$\langle FRT_{t}\rangle$ denote the mean of the GFPT and the FRT respectively.


title:
Infinite-dimensional Log-Determinant divergences II: Alpha-Beta
  divergences

abstract:
  This work presents a parametrized family of divergences, namely Alpha-Beta
Log- Determinant (Log-Det) divergences, between positive definite unitized
trace class operators on a Hilbert space. This is a generalization of the
Alpha-Beta Log-Determinant divergences between symmetric, positive definite
matrices to the infinite-dimensional setting. The family of Alpha-Beta Log-Det
divergences is highly general and contains many divergences as special cases,
including the recently formulated infinite dimensional affine-invariant
Riemannian distance and the infinite-dimensional Alpha Log-Det divergences
between positive definite unitized trace class operators. In particular, it
includes a parametrized family of metrics between positive definite trace class
operators, with the affine-invariant Riemannian distance and the square root of
the symmetric Stein divergence being special cases. For the Alpha-Beta Log-Det
divergences between covariance operators on a Reproducing Kernel Hilbert Space
(RKHS), we obtain closed form formulas via the corresponding Gram matrices.


title: Estimation and Inference for Very Large Linear Mixed Effects Models

abstract:
  Linear mixed models with large imbalanced crossed random effects structures
pose severe computational problems for maximum likelihood estimation and for
Bayesian analysis. The costs can grow as fast as $N^{3/2}$ when there are N
observations. Such problems arise in any setting where the underlying factors
satisfy a many to many relationship (instead of a nested one) and in electronic
commerce applications, the N can be quite large. Methods that do not account
for the correlation structure can greatly underestimate uncertainty. We propose
a method of moments approach that takes account of the correlation structure
and that can be computed at O(N) cost. The method of moments is very amenable
to parallel computation and it does not require parametric distributional
assumptions, tuning parameters or convergence diagnostics. For the regression
coefficients, we give conditions for consistency and asymptotic normality as
well as a consistent variance estimate. For the variance components, we give
conditions for consistency and we use consistent estimates of a mildly
conservative variance estimate. All of these computations can be done in O(N)
work. We illustrate the algorithm with some data from Stitch Fix where the
crossed random effects correspond to clients and items.


title:
Unbiased (reference-free) phase field imaging for general optical fields
  including phase discontinuities

abstract:
  A new numerically and experimentally tested measurement method for the local
electrical light field including its phase is presented. The method is based on
Self Referencing Interferograms (SRI) such as shearing interferograms. The
complex electric field is the solution vector of a linear equation with the
pixel resolved interference term E_2* E_1 as a parameter. Linearization of the
non linear equations is achieved by using preknowledge in the intensity as
obtained by a conventional image detetctor. The resulting linear equations are
not based on any approximation, iterative perturbation expansion etc. but are
exact. The method is non iterative and stable against noise for arbitrarily
chosen test fields. Allowed fields can exhibit highly fluctuating
amplitudes/phases on the pixel scale, areas of vanishing amplitude and Pi phase
jumps. The spatial resolution is of pixel size. No reference beam and no
diaphragms are used. The new method can be implemented as a fast, one shot per
frame video system. An outlook on the space resolved measurement of non
classical two photon states (including vacuum squeezed coherent states) is
given.


title: Thermodynamics of black holes in rainbow gravity

abstract:
  In this paper, we investigate the thermodynamic properties of black holes
under the influence of rainbow gravity. In the metric of Schwarzschild,
Reissner-Nordstrom and Reissner-Nordstrom-de-Sitter black hole surrounded by
quintessence, we consider a rainbow function and derive the existence of
remnant and critical masses of a black hole. Using the Hawking temperature
relation we derive the heat capacity and the entropy of the rainbow gravity
inspired black holes and closely study the relation between entropy and area of
the horizon for different values of n of the rainbow function.


title:
Many body heat radiation and heat transfer in the presence of a
  non-absorbing background medium

abstract:
  Heat radiation and near-field radiative heat transfer can be strongly
manipulated by adjusting geometrical shapes, optical properties, or the
relative positions of the objects involved. Typically these objects are
considered as embedded in vacuum. By applying the methods of fluctuational
electrodynamics, we derive general closed-form expressions for heat radiation
and heat transfer in a system of $N$ arbitrary objects embedded in a passive
non-absorbing background medium. Taking into account the principle of
reciprocity, we explicitly prove the symmetry and positivity of transfer in any
such system. Regarding applications, we find that the heat radiation of a
sphere as well as the heat transfer between two parallel plates is strongly
enhanced by the presence of a background medium. Regarding near- and far-field
transfer through a gas like air, we show that a microscopic model (based on gas
particles) and a macroscopic model (using a dielectric contrast) yield
identical results. We also compare the radiative transfer through a medium like
air and the energy transfer found from kinetic gas theory.


title:
Observations of the X-ray pulsar LMC X-4 with NuSTAR: limit on the
  magnetic field and tomography of the system in the fluorescent iron line

abstract:
  We present results of the spectral and timing analysis of the X-ray pulsar
LMC X-4 with the NuSTAR observatory in the broad energy range 3-79 keV. Along
with the detailed analysis of the averaged source spectrum, the high-precision
pulse phased-resolved spectra were obtained for the first time. It has been
shown that the comptonization model gives the best approximation of the
obtained spectra. The evolution of its parameters was traced depending on the
pulse phase as well. The search for the possible cyclotron absorption line was
performed for all energy spectra in the 5-55 keV energy range. The obtained
upper limit for the depth of the cyclotron absorption line $\tau\simeq0.15$
($3\sigma$) indicates no cyclotron absorption line in this energy range, which
provides an estimate of the magnitude of the magnetic field on the surface of
the neutron star: $B < 3 \times 10^{11}$ G or $B > 6.5 \times 10^{12}$ G. The
latter one is agree with the estimate of the magnetic field obtained from the
analysis of the power spectrum of the pulsar: $B \sim 3 \times 10^{13}$ G.
Based on results of the pulse phase-resolved spectroscopy we revealed a delay
between maxima of the source emission and the equivalent width of the
fluorescent iron line. This delay can be apparently associated with the travel
time of photons between the emitting regions in the vicinity of the neutron
star and the relatively cold regions where this emission is reflected
(presumably, at the inflowing stream or at the place of an interaction of the
stream and the outer edge of the accretion disk).


title: Holographic dark energy with the sign-changeable interaction term

abstract:
  We use three IR cutoffs, including the future event horizon, the Hubble and
Granda-Oliveros (GO) cutoffs, to construct three holographic models of dark
energy. Additionally, we consider a Friedmann-Robertson-Walker (FRW) universe
filled by a dark matter (DM) and a dark energy that interact with each other
through a mutual sign-changeable interaction. Thereinafter, we address the
evolution of the some cosmological parameters, such as the equation of state
and dimensionless density parameters of dark energy as well as the deceleration
parameter, during the cosmic evolution from the matter dominated era until the
late time acceleration. We observe that a holographic dark energy (HDE) model
with Hubble cutoff interacting with DM may be in line with the current
universe. Our study shows that models with the future event horizon as the IR
cutoff or the GO cutoff are in good agreement with the observational data. In
fact, we find out that these obtained models can predict the universe
transition from a deceleration phase to the acceleration one in a compatible
way with observations. The three obtained models may also allow the equation of
state parameter to cross the phantom line, a result which depends on the values
of the system's constants such as the value of the interaction coupling
constant.


title:
Reading a Single Qubit System Using Weak Measurement with Variable
  Strength

abstract:
  Acquiring information about an unknown qubit in a superposition of two states
is essential in any computation process. Quantum measurement, or sharp
measurement, is usually used to read the information contents of that unknown
qubit system. Quantum measurement is an irreversible operation that makes the
superposition collapses to one of the two possible states in a probabilistic
way. In this paper, a quantum algorithm will be proposed to read the
information in an unknown qubit without applying sharp measurement on that
qubit. The proposed algorithm will use a quantum feedback control scheme by
applying sharp measurement iteratively on an auxiliary qubit weakly entangled
with the unknown qubit. The information contents of the unknown qubit can be
read by counting the outcomes from the sharp measurement on the auxiliary
qubit. Iterative measurements on the auxiliary qubit will make the amplitudes
of the superposition move in a random walk manner where a weak measurement is
applied on the unknown qubit which can be reversed when the random walk takes
opposite steps to decrease the disturbance introduced to the system. The
proposed algorithm will define the strength of the weak measurement so that it
can be controlled by adding an arbitrary number of dummy qubits $\mu$ to the
system. This will make the measurement process slowdown to an arbitrary scale
so that the effect of the sharp measurement on the unknown qubit is reached
after $O(\mu^2)$ measurements on the auxiliary qubit.


title:
Modeling Ambiguity, Subjectivity, and Diverging Viewpoints in Opinion
  Question Answering Systems

abstract:
  Product review websites provide an incredible lens into the wide variety of
opinions and experiences of different people, and play a critical role in
helping users discover products that match their personal needs and
preferences. To help address questions that can't easily be answered by reading
others' reviews, some review websites also allow users to pose questions to the
community via a question-answering (QA) system. As one would expect, just as
opinions diverge among different reviewers, answers to such questions may also
be subjective, opinionated, and divergent. This means that answering such
questions automatically is quite different from traditional QA tasks, where it
is assumed that a single `correct' answer is available. While recent work
introduced the idea of question-answering using product reviews, it did not
account for two aspects that we consider in this paper: (1) Questions have
multiple, often divergent, answers, and this full spectrum of answers should
somehow be used to train the system; and (2) What makes a `good' answer depends
on the asker and the answerer, and these factors should be incorporated in
order for the system to be more personalized. Here we build a new QA dataset
with 800 thousand questions---and over 3.1 million answers---and show that
explicitly accounting for personalization and ambiguity leads both to
quantitatively better answers, but also a more nuanced view of the range of
supporting, but subjective, opinions.


title: Almost Optimal Streaming Algorithms for Coverage Problems

abstract:
  Maximum coverage and minimum set cover problems --collectively called
coverage problems-- have been studied extensively in streaming models. However,
previous research not only achieve sub-optimal approximation factors and space
complexities, but also study a restricted set arrival model which makes an
explicit or implicit assumption on oracle access to the sets, ignoring the
complexity of reading and storing the whole set at once. In this paper, we
address the above shortcomings, and present algorithms with improved
approximation factor and improved space complexity, and prove that our results
are almost tight. Moreover, unlike most of previous work, our results hold on a
more general edge arrival model. More specifically, we present (almost) optimal
approximation algorithms for maximum coverage and minimum set cover problems in
the streaming model with an (almost) optimal space complexity of
$\tilde{O}(n)$, i.e., the space is {\em independent of the size of the sets or
the size of the ground set of elements}. These results not only improve over
the best known algorithms for the set arrival model, but also are the first
such algorithms for the more powerful {\em edge arrival} model. In order to
achieve the above results, we introduce a new general sketching technique for
coverage functions: This sketching scheme can be applied to convert an
$\alpha$-approximation algorithm for a coverage problem to a
$(1-\eps)\alpha$-approximation algorithm for the same problem in streaming, or
RAM models. We show the significance of our sketching technique by ruling out
the possibility of solving coverage problems via accessing (as a black box) a
$(1 \pm \eps)$-approximate oracle (e.g., a sketch function) that estimates the
coverage function on any subfamily of the sets.


title: Real singlet scalar dark matter extension of the Georgi-Machacek model

abstract:
  The Georgi-Machacek model extends the Standard Model Higgs sector with the
addition of isospin-triplet scalar fields in such a way as to preserve the
custodial symmetry. The presence of higher-isospin scalars contributing to
electroweak symmetry breaking offers the interesting possibility that the
couplings of the 125 GeV Higgs boson to both gluons and vector boson pairs
could be larger than those of the Standard Model Higgs boson. Constraining this
possibility using measurements of Higgs production and decay at the CERN Large
Hadron Collider is notoriously problematic if a new, non-Standard Model decay
mode of the 125 GeV Higgs boson is present. We study an implementation of this
scenario in which the Georgi-Machacek model is extended by a real singlet
scalar dark matter candidate, and require that the singlet scalar account for
all the dark matter in the universe. The combination of the observed dark
matter relic density and direct detection constraints exclude singlet scalar
masses below about 57 GeV. Higgs measurements are not yet precise enough to be
very sensitive to $h\rightarrow SS$ in the remaining allowed kinematic region,
so that constraints from Higgs measurements are so far the same as in the GM
model without a singlet scalar. We also find that, above the Higgs pole, a
substantial region of parameter space yielding the correct dark matter relic
density can escape the near-future direct detection experiments DEAP and
XENON~1T for dark matter masses as low as 120 GeV and even have a direct
detection cross section below the neutrino floor for $m_S\gtrsim 150$ GeV. This
is in contrast to the singlet scalar dark matter extension of the Standard
Model, for which these future experiments are expected to exclude dark matter
masses above the Higgs pole up to the multi-TeV range.


title:
The Effect of Pok\'emon Go on The Pulse of the City: A Natural
  Experiment

abstract:
  Pok\'emon Go, a location-based game that uses augmented reality techniques,
received unprecedented media coverage due to claims that it allowed for greater
access to public spaces, increasing the number of people out on the streets,
and generally improving health, social, and security indices. However, the true
impact of Pok\'emon Go on people's mobility patterns in a city is still largely
unknown. In this paper, we perform a natural experiment using data from mobile
phone networks to evaluate the effect of Pok\'emon Go on the pulse of a big
city: Santiago, capital of Chile. We found significant effects of the game on
the floating population of Santiago compared to movement prior to the game's
release in August 2016: in the following week, up to 13.8\% more people spent
time outside at certain times of the day, even if they do not seem to go out of
their usual way. These effects were found by performing regressions using count
models over the states of the cellphone network during each day under study.
The models used controlled for land use, daily patterns, and points of interest
in the city.
  Our results indicate that, on business days, there are more people on the
street at commuting times, meaning that people did not change their daily
routines but slightly adapted them to play the game. Conversely, on Saturday
and Sunday night, people indeed went out to play, but favored places close to
where they live.
  Even if the statistical effects of the game do not reflect the massive change
in mobility behavior portrayed by the media, at least in terms of expanse, they
do show how "the street" may become a new place of leisure. This change should
have an impact on long-term infrastructure investment by city officials, and on
the drafting of public policies aimed at stimulating pedestrian traffic.


title:
Noether Symmetries of a Modified Model in Teleparallel Gravity and a New
  Approach for Exact Solutions

abstract:
  In this paper, we have presented the Noether symmetries of flat FRW spacetime
in the context of a new action in Teleparallel Gravity which we construct it
based on $f(R)$ version. This modified action contains a coupling between
scalar field potential and magnetism. Also, we introduce an innovative approach
(B.N.S. Approach) for exact solutions which carry more conserved currents than
Noether approach. By data analysis of the exact solutions, obtained from
Noether approach, late time acceleration and phase crossing are realized, and
some deep connections with observational data such as the age of the universe,
the present amounts of the scale factor as well as the state and deceleration
parameters are observed. In B.N.S. approach, we have considered dark energy
dominated era.


title:
Fractional Fokker-Planck-Kolmogorov equations associated with stochastic
  differential equations in a bounded domain

abstract:
  This paper is devoted to the fractional generalization of the Fokker-Planck
equation associated with a stochastic differential equation in a bounded
domain. The driving process of the stochastic differential equation is a L\'evy
process subordinated to the inverse of L\'evy's mixed stable subordinators. The
Fokker-Planck equation is given through the general Waldenfels operator, while
the boundary condition is given through the general Wentcel's boundary
condition. As a fractional operator a distributed order differential operator
with a Borel mixing measure is considered. In the paper fractional
generalizations of the Fokker-Planck equation are derived and the existence of
a unique solution of the corresponding initial-boundary value problems is
proved.


title: Pseudo-Hermitian systems with PT-symmetry: Degeneracy and Krein space

abstract:
  We show in the present paper that pseudo-Hermitian Hamiltonian systems with
even PT-symmetry admit a degeneracy structure. This kind of degeneracy is
expected traditionally in the odd PT-symmetric systems which is appropriate to
the fermions as shown by Jones-Smith and Mathur [1] who extended PT-symmetric
quantum mechanics to the case of odd time-reversal symmetry. We establish that
the pseudo-Hermitian Hamiltonians with even PT-symmetry admit a degeneracy
structure if the operator PT anticommutes with the metric operator {\eta} which
is necessarily indefinite. We also show that the Krein space formulation of the
Hilbert space is the convenient framework for the implementation of unbroken
PT-symmetry. These general results are illustrated with great details for
four-level pseudo-Hermitian Hamiltonian with even PT-symmetry.


title: The outburst of the X-ray nova GRS 1739-278 in September, 2016

abstract:
  During the scanning observations of the Galactic Center region in August -
September 2016 we detected the new outburst of the historical X-ray nova GRS
1739-278, the black hole candidate LMXB system. In this letter we present
results of INTEGRAL and Swift-XRT observations taken during the outburst. In
hard X-ray band (20-60 keV) the flux from the source raised from $\sim$11 to
$\sim$30 mCrab between 3 and 14 of September. For nearly 8 days the source has
been observed at this flux level and then faded to $\sim$15 mCrab. The
broadband quasi-simultaneous spectrum obtained during the outburst is well
described by the absorbed powerlaw with the photon index $\Gamma=1.86\pm0.07$
in broad energy range 0.5-150 keV, with absorption corresponding to
${N_{H}}=2.3\times10^{22}$ cm$^{-2}$ assuming solar abundance. Based on this we
can conclude that the source was in the low/hard state. From the lightcurve and
spectra we propose that this outburst was `failed', i.e. amount of accreted
matter was not sufficient to achieve the high/soft spectral state with dominant
soft blackbody component as seen in normal outbursts of black hole candidates.


title: A variational principle for a non-integrable model

abstract:
  We develop a new robust technique to deduce variance principles for
non-integrable discrete systems. To illustrate this technique, we show the
existence of a variational principle for graph homomorphisms from $\Z^m$ to a
$d$-regular tree. This seems to be the first non-trivial example of a
variational principle in a non-integrable model. Instead of relying on
integrability, the technique is based on a discrete Kirszbraun theorem and a
concentration inequality obtained through the dynamic of the model. As a
consequence of this result, we obtain the existence of a continuum of
shift-invariant ergodic gradient Gibbs measures for graph homomorphisms from
$\Z^m$ to a regular tree.


title: Cleaning large correlation matrices: tools from random matrix theory

abstract:
  This review covers recent results concerning the estimation of large
covariance matrices using tools from Random Matrix Theory (RMT). We introduce
several RMT methods and analytical techniques, such as the Replica formalism
and Free Probability, with an emphasis on the Marchenko-Pastur equation that
provides information on the resolvent of multiplicatively corrupted noisy
matrices. Special care is devoted to the statistics of the eigenvectors of the
empirical correlation matrix, which turn out to be crucial for many
applications. We show in particular how these results can be used to build
consistent "Rotationally Invariant" estimators (RIE) for large correlation
matrices when there is no prior on the structure of the underlying process. The
last part of this review is dedicated to some real-world applications within
financial markets as a case in point. We establish empirically the efficacy of
the RIE framework, which is found to be superior in this case to all previously
proposed methods. The case of additively (rather than multiplicatively)
corrupted noisy matrices is also dealt with in a special Appendix. Several open
problems and interesting technical developments are discussed throughout the
paper.

categories: cond-mat.stat-mech math.ST q-fin.ST stat.TH


title: Solvability, Structure and Analysis for Minimal Parabolic Subgroups

abstract:
  We examine the structure of the Levi component $MA$ in a minimal parabolic
subgroup $P = MAN$ of a real reductive Lie group $G$ and work out the cases
where $M$ is metabelian, equivalently where $\mathfrak{p}$ is solvable. When
$G$ is a linear group we verify that $\mathfrak{p}$ is solvable if and only if
$M$ is commutative. In the general case $M$ is abelian modulo the center $Z_G$,
we indicate the exact structure of $M$ and $P$, and we work out the precise
Plancherel Theorem and Fourier Inversion Formulae. This lays the groundwork for
comparing tempered representations of $G$ with those induced from generic
representations of $P$.


title:
Evolutionary optimization of PAW data-sets for accurate high pressure
  simulations

abstract:
  We examine the challenge of performing accurate electronic structure
calculations at high pressures by comparing the results of all-electron full
potential linearized augmented-plane-wave calculations with those of the
projector augmented wave (PAW) method. In particular, we focus on developing an
automated and consistent way of generating transferable PAW data-sets that can
closely produce the all electron equation of state defined from zero to
arbitrary high pressures. The technique we propose is an evolutionary search
procedure that exploits the ATOMPAW code to generate atomic data-sets and the
Quantum ESPRESSO software suite for total energy calculations. We demonstrate
different aspects of its workability by optimizing PAW basis functions of some
elements relatively abundant in planetary interiors. In addition, we introduce
a new measure of atomic data-set goodness by considering their performance
uniformity over an enlarged pressure range.


title:
Electric control of Dirac quasiparticles by spin-orbit torque in an
  antiferromagnet

abstract:
  Spin-orbitronics and Dirac quasiparticles are two fields of condensed matter
physics initiated independently about a decade ago. Here we predict that Dirac
quasiparticles can be controlled by the spin-orbit torque reorientation of the
N\'{e}el vector in an antiferromagnet. Using CuMnAs as an example, we formulate
symmetry criteria allowing for the co-existence of Dirac quasiparticles and
N\'{e}el spin-orbit torques. We identify the non-symmorphic crystal symmetry
protection of Dirac band crossings whose on and off switching is mediated by
the N\'{e}el vector reorientation. We predict that this concept, verified by
minimal model and density functional calculations in the CuMnAs semimetal
antiferromagnet, can lead to a topological metal-insulator transition driven by
the N\'{e}el vector and to the corresponding topological anisotropic
magnetoresistance.


title: Pattern formation of a nonlocal, anisotropic interaction model

abstract:
  We consider a class of interacting particle models with anisotropic,
repulsive-attractive interaction forces whose orientations depend on an
underlying tensor field. An example of this class of models is the so-called
K\"ucken-Champod model describing the formation of fingerprint patterns. This
class of models can be regarded as a generalization of a gradient flow of a
nonlocal interaction potential which has a local repulsion and a long-range
attraction structure. In contrast to isotropic interaction models the
anisotropic forces in our class of models cannot be derived from a potential.
The underlying tensor field introduces an anisotropy leading to complex
patterns which do not occur in isotropic models. This anisotropy is
characterized by one parameter in the model. We study the variation of this
parameter, describing the transition between the isotropic and the anisotropic
model, analytically and numerically. We analyze the equilibria of the
corresponding mean-field partial differential equation and investigate pattern
formation numerically in two dimensions by studying the dependence of the
parameters in the model on the resulting patterns.


title: An elliptic sequence is not a sampled linear recurrence sequence

abstract:
  Let $E$ be an elliptic curve defined over the rationals and in minimal
Weierstrass form, and let $P=(x_1/z_1^2,y_1/z_1^3)$ be a rational point of
infinite order on $E$, where $x_1,y_1,z_1$ are coprime integers. We show that
the integer sequence $(z_n)$ defined by $nP=(x_n/z_n^2,y_n/z_n^3)$ for all
$n\ge 1$ does not eventually coincide with $(u_{n^2})$ for any choice of linear
recurrence sequence $(u_n)$ with integer values.


title:
Nonlinear Bosonization and Refermionization in One Dimension with the
  Keldysh Functional Integral

abstract:
  We develop a self-contained approach to bosonization and refermionization
using the Keldysh functional integral. Starting from fermionic particles, we
bosonize the system and obtain a description in terms of the Tomonaga-Luttinger
liquid, with, in addition, an infinite series of interaction terms arising from
the curvature of the fermionic particle spectrum. We explicitly calculate the
leading interaction term and check its consistency with a different approach
based on the Matsubara framework, within which we calculate the second leading
interaction term, as well. Moreover, we bosonize weakly and strongly
interacting bosonic particles, and, finally, refermionize interacting phonons
into non-interacting fermionic quasiparticles. The work culminates in a map
between bosonic and fermionic particles and effective bosonic and fermionic
excitations, representing phonons and fermionic quasiparticles.


title: Efficient Pattern Matching in Elastic-Degenerate Strings

abstract:
  In this paper, we extend the notion of gapped strings to elastic-degenerate
strings. An elastic-degenerate string can been seen as an ordered collection of
k > 1 seeds (substrings/subpatterns) interleaved by elastic-degenerate symbols
such that each elastic-degenerate symbol corresponds to a set of two or more
variable length strings. Here, we present an algorithm for solving the pattern
matching problem with (solid) pattern and elastic-degenerate text, running in
O(N+{\alpha}{\gamma}nm) time; where m is the length of the given pattern; n and
N are the length and total size of the given elastic-degenerate text,
respectively; {\alpha} and {\gamma} are small constants, respectively
representing the maximum number of strings in any elastic-degenerate symbol of
the text and the largest number of elastic-degenerate symbols spanned by any
occurrence of the pattern in the text. The space used by the algorithm is
linear in the size of the input for a constant number of elastic-degenerate
symbols in the text; {\alpha} and {\gamma} are so small in real applications
that the algorithm is expected to work very efficiently in practice.


title:
Atomki anomaly and dark matter in a radiative seesaw model with gauged
  $B-L$ symmetry

abstract:
  Motivated by recently reported anomalies in a decay of an excited state of
beryllium by the Atomki collaboration, we study a radiative seesaw model with
gauged $B-L$ symmetry and a $Z_2$ parity. Assuming that the anomalies originate
from the decay of the $B-L$ gauge boson followed by the nuclear decay, the mass
of the lightest right-handed neutrino or the dark matter candidate can be
determined below $10$ GeV. We show that for this mass range, the model can
explain the anomalies in the beryllium decay and the relic dark matter
abundance consistent with neutrino masses. We also predict its spin-independent
cross section in direct detection experiments for this mass range.


title:
Interface structure, band alignment and built-in potentials at
  LaFeO$_3$/$\textit{n}$-SrTiO$_3$ heterojunctions

abstract:
  Interface structure at polar/non-polar interfaces has been shown to be a key
factor in controlling emergent behavior in oxide heterostructures, including
the LaFeO$_3$/$\textit{n}$-SrTiO$_3$ system. We demonstrate via high energy
resolution x-ray photoemission that epitaxial LaFeO$_3$/$\textit{n}$-SrTiO$_3$
(001) heterojunctions engineered to have opposite interface polarities exhibit
very similar band offsets and potential gradients within the LaFeO$_3$ films.
However, differences in the potential gradient within the SrTiO$_3$ layer
depending on polarity may promote hole diffusion into LaFeO$_3$ for
applications in photocatalysis.


title:
Asynchronous Transmission over Gaussian Interference Channels with
  Stochastic Data Arrival

abstract:
  This paper addresses a Gaussian interference channel with two
transmitter-receiver~(Tx-Rx) pairs under stochastic data arrival~(GIC-SDA).
Information bits arrive at the transmitters according to independent and
asynchronous Bernoulli processes~(Tx-Tx~asynchrony). Each information source
turns off after generating a given total number of bits. The transmissions are
\textit{asynchronous} (Tx-Rx~asynchrony) in the sense that each Tx sends a
codeword to its Rx immediately after there are enough bits available in its
buffer. Such asynchronous style of transmission is shown to significantly
reduce the transmission delay in comparison with the existing Tx-Rx synchronous
transmission schemes. The receivers learn the activity frames of both
transmitters by employing sequential joint-typicality detection. As a
consequence, the GIC-SDA under Tx-Rx asynchrony is represented by a standard
GIC with state known at the receivers. The cardinality of the state space is
$\binom{2N_1+2N_2}{2N_2}$ in which $N_1, N_2$ are the numbers of transmitted
codewords by the two transmitters. Each realization of the state imposes two
sets of constraints on $N_1, N_2$ referred to as the geometric and reliability
constraints. In a scenario where the transmitters are only aware of the
statistics of Tx-Tx~asynchrony, it is shown how one designs $N_1,N_2$ to
achieve target transmission rates for both users and minimize the probability
of unsuccessful decoding.


title:
A Physician Advisory System for Chronic Heart Failure Management Based
  on Knowledge Patterns

abstract:
  Management of chronic diseases such as heart failure, diabetes, and chronic
obstructive pulmonary disease (COPD) is a major problem in health care. A
standard approach that the medical community has devised to manage widely
prevalent chronic diseases such as chronic heart failure (CHF) is to have a
committee of experts develop guidelines that all physicians should follow.
These guidelines typically consist of a series of complex rules that make
recommendations based on a patient's information. Due to their complexity,
often the guidelines are either ignored or not complied with at all, which can
result in poor medical practices. It is not even clear whether it is humanly
possible to follow these guidelines due to their length and complexity. In the
case of CHF management, the guidelines run nearly 80 pages. In this paper we
describe a physician-advisory system for CHF management that codes the entire
set of clinical practice guidelines for CHF using answer set programming. Our
approach is based on developing reasoning templates (that we call knowledge
patterns) and using these patterns to systemically code the clinical guidelines
for CHF as ASP rules. Use of the knowledge patterns greatly facilitates the
development of our system. Given a patient's medical information, our system
generates a recommendation for treatment just as a human physician would, using
the guidelines. Our system will work even in the presence of incomplete
information. Our work makes two contributions: (i) it shows that highly complex
guidelines can be successfully coded as ASP rules, and (ii) it develops a
series of knowledge patterns that facilitate the coding of knowledge expressed
in a natural language and that can be used for other application domains. This
paper is under consideration for acceptance in TPLP.


title: A Higher-order Calculus of Computational Fields

abstract:
  The complexity of large-scale distributed systems, particularly when deployed
in physical space, calls for new mechanisms to address composability and
reusability of collective adaptive behaviour. Computational fields have been
proposed as an effective abstraction to fill the gap between the macro-level of
such systems (specifying a system's collective behaviour) and the micro-level
(individual devices' actions of computation and interaction to implement that
collective specification), thereby providing a basis to better facilitate the
engineering of collective APIs and complex systems at higher levels of
abstraction. This paper proposes a full formal foundation for field
computations, in terms of a core (higher-order) calculus of computational
fields containing a few key syntactic constructs, and equipped with typing,
denotational and operational semantics. Critically, this allows formal
establishment of a link between the micro- and macro-levels of collective
adaptive systems, by a result of full abstraction and adequacy for the
(aggregate) denotational semantics with respect to the (per-device) operational
semantics.


title:
A recommender system for efficient discovery of new anomalies in
  large-scale access logs

abstract:
  We present a novel, non-standard recommender system for large-scale security
policy management(SPM). Our system Helios discovers and recommends unknown and
unseen anomalies in large-scale access logs with minimal supervision and no
starting information on users and items. Typical recommender systems assume
availability of user- and item-related information, but such information is not
usually available in access logs. To resolve this problem, we first use
discrete categorical labels to construct categorical combinations from access
logs in a bootstrapping manner. Then, we utilize rank statistics of entity rank
and order categorical combinations for recommendation. From a double-sided cold
start, with minimal supervision, Helios learns to recommend most salient
anomalies at large-scale, and provides visualizations to security experts to
explain rationale behind the recommendations. Our experiments show Helios to be
suitable for large-scale applications: from cold starts, in less than 60
minutes, Helios can analyze roughly 4.6 billion records in logs of 400GB with
about 300 million potential categorical combinations, then generate ranked
categorical combinations as recommended discoveries. We also show that, even
with limited computing resources, Helios accelerates unknown and unseen anomaly
discovery process for SPM by 1 to 3 orders of magnitude, depending on use
cases. In addition, Helios' design is flexible with metrics and measurement
fields used for discoveries and recommendations. Overall, our system leads to
more efficient and customizable SPM processes with faster discoveries of unseen
and unknown anomalies.


title: Studies on Thin-shells and Thin-shell Wormholes

abstract:
  The study of traversable wormholes is very hot topic for the past 30 years.
One of the best possible way to make traversable wormhole is using the
thin-shells to cut and paste two spacetime which has tunnel from one region of
space-time to another, through which a traveler might freely pass in wormhole
throat. These geometries need an exotic matter which involves a stress-energy
tensor that violates the null energy condition. However, this method can be
used to minimize the amount of the exotic matter. The goal of this thesis study
is to study on thin-shell and thin-shell wormholes in general relativity in 2+1
and 3+1 dimensions. We also investigate the stability of such objects.


title: Predicting First Impressions with Deep Learning

abstract:
  Describable visual facial attributes are now commonplace in human biometrics
and affective computing, with existing algorithms even reaching a sufficient
point of maturity for placement into commercial products. These algorithms
model objective facets of facial appearance, such as hair and eye color,
expression, and aspects of the geometry of the face. A natural extension, which
has not been studied to any great extent thus far, is the ability to model
subjective attributes that are assigned to a face based purely on visual
judgements. For instance, with just a glance, our first impression of a face
may lead us to believe that a person is smart, worthy of our trust, and perhaps
even our admiration - regardless of the underlying truth behind such
attributes. Psychologists believe that these judgements are based on a variety
of factors such as emotional states, personality traits, and other physiognomic
cues. But work in this direction leads to an interesting question: how do we
create models for problems where there is no ground truth, only measurable
behavior? In this paper, we introduce a new convolutional neural network-based
regression framework that allows us to train predictive models of crowd
behavior for social attribute assignment. Over images from the AFLW face
database, these models demonstrate strong correlations with human crowd
ratings.


title:
Image Segmentation for Fruit Detection and Yield Estimation in Apple
  Orchards

abstract:
  Ground vehicles equipped with monocular vision systems are a valuable source
of high resolution image data for precision agriculture applications in
orchards. This paper presents an image processing framework for fruit detection
and counting using orchard image data. A general purpose image segmentation
approach is used, including two feature learning algorithms; multi-scale
Multi-Layered Perceptrons (MLP) and Convolutional Neural Networks (CNN). These
networks were extended by including contextual information about how the image
data was captured (metadata), which correlates with some of the appearance
variations and/or class distributions observed in the data. The pixel-wise
fruit segmentation output is processed using the Watershed Segmentation (WS)
and Circular Hough Transform (CHT) algorithms to detect and count individual
fruits. Experiments were conducted in a commercial apple orchard near
Melbourne, Australia. The results show an improvement in fruit segmentation
performance with the inclusion of metadata on the previously benchmarked MLP
network. We extend this work with CNNs, bringing agrovision closer to the
state-of-the-art in computer vision, where although metadata had negligible
influence, the best pixel-wise F1-score of $0.791$ was achieved. The WS
algorithm produced the best apple detection and counting results, with a
detection F1-score of $0.858$. As a final step, image fruit counts were
accumulated over multiple rows at the orchard and compared against the
post-harvest fruit counts that were obtained from a grading and counting
machine. The count estimates using CNN and WS resulted in the best performance
for this dataset, with a squared correlation coefficient of $r^2=0.826$.


title: Kirwan surjectivity for quiver varieties

abstract:
  For algebraic varieties defined by hyperkahler or, more generally, algebraic
symplectic reduction, it is a long-standing question whether the "hyperkahler
Kirwan map" on cohomology is surjective. We resolve this question in the
affirmative for Nakajima quiver varieties. We also establish similar results
for other cohomology theories and for the derived category. Our proofs use only
classical topological and geometric arguments.


title: Controlling Thermal Expansion: a Metal Organic Frameworks Route

abstract:
  Controlling thermal expansion is an important, not yet resolved, and
challenging problem in materials research. A conceptual design is introduced
here for the first time, for the use of MOFs as platforms for controlling
thermal expansion devices that can operate in the negative, zero and positive
expansion regimes. A detailed computer simulation study, based on molecular
dynamics, is presented to support the targeted application. MOF-5 has been
selected as model material along with three molecules of similar size and known
differences in terms of the nature of host--guest interactions. It has been
shown that adsorbate molecules can control, in a colligative way, the thermal
expansion of the solid, so that changing the adsorbate molecules induces the
solid to have positive, zero or negative thermal expansion. We analyze in-depth
the distortion mechanisms, beyond the ligand metal junction to cover the ligand
distortions, and the energetic and entropic effect on the thermo-structural
behavior. We provide an unprecedented atomistic insight on the effect of
adsorbates on the thermal expansion of MOFs, as a basic tool towards
controlling the thermal expansion.


title:
Socratic Learning: Augmenting Generative Models to Incorporate Latent
  Subsets in Training Data

abstract:
  A challenge in training discriminative models like neural networks is
obtaining enough labeled training data. Recent approaches use generative models
to combine weak supervision sources, like user-defined heuristics or knowledge
bases, to label training data. Prior work has explored learning accuracies for
these sources even without ground truth labels, but they assume that a single
accuracy parameter is sufficient to model the behavior of these sources over
the entire training set. In particular, they fail to model latent subsets in
the training data in which the supervision sources perform differently than on
average. We present Socratic learning, a paradigm that uses feedback from a
corresponding discriminative model to automatically identify these subsets and
augments the structure of the generative model accordingly. Experimentally, we
show that without any ground truth labels, the augmented generative model
reduces error by up to 56.06% for a relation extraction task compared to a
state-of-the-art weak supervision technique that utilizes generative models.


title:
Graviton KK resonant mode in the correction of the Newton's law from 6D
  braneworlds

abstract:
  In this work, we derive an expression for the correction in the Newton's law
of gravitation due to the gravitational Kaluza-Klein states in a general thick
string-like braneworld scenario in six dimensions. In order to analyze
corrections to Newton's law we study the gravity fluctuations in a 3-brane
placed in a transverse resolved conifold and use suitable numerical methods to
attain the massive spectrum and the corresponding eigenfunctions. Such
braneworld model has a resolution parameter which removes the conical
singularity. The correction has an exponentially suppressed mass term and
depends on the values of the eigenfunctions and warp factors computed at the
core peak of the brane. The spectrum is real and monotonically increased, as
desired. However, the resolution parameter must assume moderate values to have
physically acceptable states. Moreover, the trapped massless mode regains the
4D gravity and it is displaced from the origin, sharing similar profile with
the energy density of brane for small values of resolution parameter. Finally,
for the singular conifold, we found that a non-first eigenstate is a resonant
mode. Such excited state is the largest contributor to corrections in the
Newtonian potential.


title:
Revised Geometric Estimates of the North Galactic Pole and the Sun's
  Height Above the Galactic Midplane

abstract:
  Astronomers are entering an era of {\mu}as-level astrometry utilizing the
5-decade-old IAU Galactic coordinate system that was only originally defined to
$\sim$0{\deg}.1 accuracy, and where the dynamical centre of the Galaxy (Sgr A*)
is located $\sim$0{\deg}.07 from the origin. We calculate new independent
estimates of the North Galactic Pole (NGP) using recent catalogues of Galactic
disc tracer objects such as embedded and open clusters, infrared bubbles, dark
clouds, and young massive stars. Using these catalogues, we provide two new
estimates of the NGP. Solution 1 is an "unconstrained" NGP determined by the
galactic tracer sources, which does not take into account the location of Sgr
A*, and which lies 90{\deg}.120$\,\pm\,$0{\deg}.029 from Sgr A*, and Solution 2
is a "constrained" NGP which lies exactly 90{\deg} from Sgr A*. The
"unconstrained" NGP has ICRS position: $\alpha_{NGP}$ = 192{\deg}.729 $\,\pm\,$
0{\deg}.035, $\delta_{NGP}$ = 27{\deg}.084 $\,\pm\,$ 0{\deg}.023 and $\theta\,$
= 122{\deg}.928 $\,\pm\,$ 0{\deg}.016. The "constrained" NGP which lies exactly
90{\deg} away from Sgr A* has ICRS position: $\alpha_{NGP}$ = 192{\deg}.728
$\,\pm\,$0{\deg}.010, $\delta_{NGP}$ = 26{\deg}.863 $\,\pm\,$ 0{\deg}.019 and
$\theta\,$ = 122{\deg}.928 $\,\pm\,$ 0{\deg}.016. The difference between the
solutions is likely due to the Sun lying above the Galactic midplane.
Considering the angular separation between Sgr A* and our unconstrained NGP,
and if one adopts the recent estimate of the Galactocentric distance for the
Sun of $R_{0}$ = 8.2$\,\pm\,$0.1 kpc, then we estimate that the Sun lies
$z_{\odot}$ $\simeq$ 17$\,\pm\,$5 pc above the Galactic midplane. Our value of
$z_{\odot}$ is consistent with the true median of 55 previous estimates
published over the past century of the Sun's height above the Galactic
mid-plane ($z_{\odot}$ $\simeq$ 17$\,\pm\,$2 pc).


title:
Irreducible subquotients of generic gelfand-tsetlin modules over
  uq(gl(n))

abstract:
  We provide a classification and explicit bases of tableaux of all irreducible
subquotients of generic Gelfand-Tsetlin modules over Uq(gl(n)) where q
different 1 and -1.


title: Fast Bayesian Non-Negative Matrix Factorisation and Tri-Factorisation

abstract:
  We present a fast variational Bayesian algorithm for performing non-negative
matrix factorisation and tri-factorisation. We show that our approach achieves
faster convergence per iteration and timestep (wall-clock) than Gibbs sampling
and non-probabilistic approaches, and do not require additional samples to
estimate the posterior. We show that in particular for matrix tri-factorisation
convergence is difficult, but our variational Bayesian approach offers a fast
solution, allowing the tri-factorisation approach to be used more effectively.