title:
Measurements of the Higgs boson production and decay rates and
  constraints on its couplings from a combined ATLAS and CMS analysis of the
  LHC $pp$ collision data at $\sqrt{s}=$ 7 and 8 TeV

abstract:
  Combined ATLAS and CMS measurements of the Higgs boson production and decay
rates, as well as constraints on its couplings to vector bosons and fermions,
are presented. The combination is based on the analysis of five production
processes, namely gluon fusion, vector boson fusion, and associated production
with a $W$ or a $Z$ boson or a pair of top quarks, and of the six decay modes
$H \to ZZ, WW$, $\gamma\gamma, \tau\tau, bb$, and $\mu\mu$. All results are
reported assuming a value of 125.09 GeV for the Higgs boson mass, the result of
the combined measurement by the ATLAS and CMS experiments. The analysis uses
the CERN LHC proton--proton collision data recorded by the ATLAS and CMS
experiments in 2011 and 2012, corresponding to integrated luminosities per
experiment of approximately 5 fb$^{-1}$ at $\sqrt{s}=7$ TeV and 20 fb$^{-1}$ at
$\sqrt{s} = 8$ TeV. The Higgs boson production and decay rates measured by the
two experiments are combined within the context of three generic
parameterisations: two based on cross sections and branching fractions, and one
on ratios of coupling modifiers. Several interpretations of the measurements
with more model-dependent parameterisations are also given. The combined signal
yield relative to the Standard Model prediction is measured to be 1.09 $\pm$
0.11. The combined measurements lead to observed significances for the vector
boson fusion production process and for the $H \to \tau\tau$ decay of $5.4$ and
$5.5$ standard deviations, respectively. The data are consistent with the
Standard Model predictions for all parameterisations considered.


title:
Entropy bounds and quantum unique ergodicity for Hecke eigenfunctions on
  division algebras

abstract:
  We prove the arithmetic quantum unique ergodicity (AQUE) conjecture for
non-degenerate sequences of Hecke eigenfunctions on quotients $\Gamma
\backslash G/K$, where $G\simeq\mathrm{PGL}_{d}(\mathbb{R})$, $K$ is a maximal
compact subgroup of $G$ and $\Gamma<G$ is a lattice associated to a division
algebra over $\mathbb{Q}$ of prime degree $d$.
  More generally, we introduce a new method of proving positive entropy of
quantum limits, which applies to higher-rank groups. The result on AQUE is
obtained by combining this with a measure-rigidity theorem due to
Einsiedler-Katok, following a strategy first pioneered by Lindenstrauss


title: Zero modes in de Sitter background

abstract:
  There are five well-known zero modes among the fluctuations of the metric of
de~Sitter (dS) spacetime. For Euclidean signature, they can be associated with
certain spherical harmonics on the $S^4$ sphere, viz., the vector
representation $\bf5$ of the global $SO(5)$ isometry. They appear, for example,
in the perturbative calculation of the on-shell effective action of dS space,
as well as in models containing matter fields. These modes are shown to be
associated with collective modes of $S^4$ corresponding to certain coherent
fluctuations. When dS space is embedded in flat five dimensions $E^5,$ they may
be seen as a legacy of translation of the center of the $S^4$ sphere. Rigid
translations of the $S^4$-sphere on $E^5$ leave the classical action invariant
but are unobservable displacements from the point of view of gravitational
dynamics on $S^4.$ Thus, unlike similar moduli, the center of the sphere is not
promoted to a dynamical degree of freedom. As a result, these zero modes do not
signify the possibility of physically realizable fluctuations or flat
directions for the metric of dS space. They are not associated with Killing
vectors on $S^4$ but can be with certain non-isometric, conformal Killing forms
that locally correspond to a rescaling of the volume element $dV_4.$
  For convenience, we frame our discussion in the context of renormalizable
gravity, but the conclusions apply equally to the corresponding zero modes in
Einstein gravity. We expect that these zero modes will be present to all orders
in perturbation theory. They will occur for Lorentzian signature as well, so
long as the hyperboloid $H^4$ is locally stable, but there remain certain
infrared issues that need to be clarified. We conjecture that they will appear
in any gravitational theory having dS background as a locally stable solution
of the effective action, regardless of whether additional matter is included.


title: Performance of leader-follower multi-agent systems in directed networks

abstract:
  We consider leader-follower multi-agent systems in which the leader executes
the desired trajectory and the followers implement the consensus algorithm
subject to stochastic disturbances. The performance of the leader-follower
systems is quantified by using the steady-state variance of the deviation of
the followers from the leader. We study the asymptotic scaling of the variance
in directed lattices in one, two, and three dimensions. We show that in 1D and
2D the variance of the followers' deviation increases to infinity as one moves
away from the leader, while in 3D it remains bounded. We prove that the
variance scales as a square-root function in 1D and a logarithmic function in
2D lattices.


title: Natural Language Comprehension with the EpiReader

abstract:
  We present the EpiReader, a novel model for machine comprehension of text.
Machine comprehension of unstructured, real-world text is a major research goal
for natural language processing. Current tests of machine comprehension pose
questions whose answers can be inferred from some supporting text, and evaluate
a model's response to the questions. The EpiReader is an end-to-end neural
model comprising two components: the first component proposes a small set of
candidate answers after comparing a question to its supporting text, and the
second component formulates hypotheses using the proposed candidates and the
question, then reranks the hypotheses based on their estimated concordance with
the supporting text. We present experiments demonstrating that the EpiReader
sets a new state-of-the-art on the CNN and Children's Book Test machine
comprehension benchmarks, outperforming previous neural models by a significant
margin.


title:
Comments on the compatibility of thermodynamic equilibrium conditions
  with lattice propagators

abstract:
  In this paper the compatibility is analyzed of the non-perturbative equations
of state of quarks and gluons arising from the lattice with some natural
requirements for self-gravitating objects at equilibrium: the existence of an
equation of state (namely, the possibility to define the pressure as a function
of the energy density), the absence of superluminal propagation and Le
Chatelier's principle. It is discussed under which conditions it is possible to
extract an equation of state (in the above sense) from the non-perturbative
propagators arising from the fits of the latest lattice data. In the quark
case, there is a small but non-vanishing range of temperatures in which it is
not possible to define a single-valued functional relation between density and
pressure. Interestingly enough, a small change of the parameters appearing in
the fit of the lattice quark propagator (of around 10~\%) could guarantee the
fulfillment of all the three conditions (keeping alive, at the same time, the
violation of positivity of the spectral representation, which is the expected
signal of confinement). As far as gluons are concerned, the analysis shows very
similar results. Whether or not the non-perturbative quark and gluon
propagators satisfy these conditions can have a strong impact on the estimate
of the maximal mass of quark stars.


title:
Modelling dust processing and the evolution of grain sizes in the ISM
  using the method of moments

abstract:
  Interstellar dust grains do not have a single well-defined origin. Stars are
demonstrably dust producers, but also efficient destroyers of cosmic dust. Dust
destruction in the ISM is believed to be the result of SN shocks hitting the
ambient ISM gas (and dust) and lead to an increased rate of ion sputtering,
which reduces the dust mass. Grains located in cold molecular clouds can on the
other hand grow by condensation, thus providing a replenishment mechanism or
even a dominant channel of dust formation. In dense environments grains may
coagulate and form large composite grains and aggregates and if grains collide
with large enough energies they may be shattered, forming a range of smaller
debris grains. The present paper presents a statistical modelling approach
using the method of moments, which is computationally very inexpensive and may
therefore be an attractive option when combining dust processing with, e.g.,
detailed simulations of interstellar gas dynamics. A solar-neighbourhood-like
toy model of interstellar dust evolution is presented as an example.


title:
Near Horizon Symmetries of the Non-Extremal Black Hole Solutions of
  Generalized Minimal Massive Gravity

abstract:
  We consider the Generalized Minimal Massive Gravity (GMMG) model in the first
order formalism. We show that all the solutions of the Einstein gravity with
negative cosmological constants solve the equations of motion of considered
model. Then we find an expression for the off-shell conserved charges of this
model. By considering the near horizon geometry of a three dimensional black
hole in the Gaussian null coordinates, we find near horizon conserved charges
and their algebra. The obtained algebra is centrally extended. By writing the
algebra of conserved charges in terms of Fourier modes and considering the BTZ
black hole solution as an example, one can see that the charge associated with
rotations along $\mathcal{Y}_{0}$ coincides exactly with the angular momentum,
and he charge associated with time translations $\mathcal{T}_{0}$ is the
product of the black hole entropy and its temperature. As we expect, in the
limit when the GMMG tends to the Einstein gravity, all the result we obtain in
this paper reduce to the result of the paper \cite{5}.


title:
The spatial sign covariance matrix and its application for robust
  correlation estimation

abstract:
  We summarize properties of the spatial sign covariance matrix and especially
look at the relationship between its eigenvalues and those of the shape matrix
of an elliptical distribution. The explicit relationship known in the bivariate
case was used to construct the spatial sign correlation coefficient, which is a
non-parametric and robust estimator for the correlation coefficient within the
elliptical model. We consider a multivariate generalization, which we call the
multivariate spatial sign correlation matrix.


title:
Measuring the reliability of MCMC inference with bidirectional Monte
  Carlo

abstract:
  Markov chain Monte Carlo (MCMC) is one of the main workhorses of
probabilistic inference, but it is notoriously hard to measure the quality of
approximate posterior samples. This challenge is particularly salient in black
box inference methods, which can hide details and obscure inference failures.
In this work, we extend the recently introduced bidirectional Monte Carlo
technique to evaluate MCMC-based posterior inference algorithms. By running
annealed importance sampling (AIS) chains both from prior to posterior and vice
versa on simulated data, we upper bound in expectation the symmetrized KL
divergence between the true posterior distribution and the distribution of
approximate samples. We present Bounding Divergences with REverse Annealing
(BREAD), a protocol for validating the relevance of simulated data experiments
to real datasets, and integrate it into two probabilistic programming
languages: WebPPL and Stan. As an example of how BREAD can be used to guide the
design of inference algorithms, we apply it to study the effectiveness of
different model representations in both WebPPL and Stan.


title: Multilingual Visual Sentiment Concept Matching

abstract:
  The impact of culture in visual emotion perception has recently captured the
attention of multimedia research. In this study, we pro- vide powerful
computational linguistics tools to explore, retrieve and browse a dataset of
16K multilingual affective visual concepts and 7.3M Flickr images. First, we
design an effective crowdsourc- ing experiment to collect human judgements of
sentiment connected to the visual concepts. We then use word embeddings to
repre- sent these concepts in a low dimensional vector space, allowing us to
expand the meaning around concepts, and thus enabling insight about
commonalities and differences among different languages. We compare a variety
of concept representations through a novel evaluation task based on the notion
of visual semantic relatedness. Based on these representations, we design
clustering schemes to group multilingual visual concepts, and evaluate them
with novel metrics based on the crowdsourced sentiment annotations as well as
visual semantic relatedness. The proposed clustering framework enables us to
analyze the full multilingual dataset in-depth and also show an application on
a facial data subset, exploring cultural in- sights of portrait-related
affective visual concepts.


title:
Theoretical study of stimulated and spontaneous Hawking effects from an
  acoustic black hole in a hydrodynamically flowing fluid of light

abstract:
  We propose an experiment to detect and characterize the analog Hawking
radiation in an analog model of gravity consisting of a flowing
exciton-polariton condensate. Under a suitably designed coherent pump
configuration, the condensate features an acoustic event horizon for sound
waves that at the semiclassical level is equivalent to an astrophysical black
hole horizon. We show that a continuous-wave pump-and-probe spectroscopy
experiment allows to measure the analog Hawking temperature from the dependence
of the stimulated Hawking effect on the pump-probe detuning. We anticipate the
appearance of an emergent resonant cavity for sound waves between the pump beam
and the horizon, which results in marked oscillations on top of an overall
exponential frequency dependence. We finally analyze the spatial correlation
function of density fluctuations and identify the hallmark features of the
correlated pairs of Bogoliubov excitations created by the spontaneous Hawking
process, as well as novel signatures characterizing the emergent cavity.


title: Perfect Commuting-Operator Strategies for Linear System Games

abstract:
  Linear system games are a generalization of Mermin's magic square game
introduced by Cleve and Mittal. They show that perfect strategies for linear
system games in the tensor-product model of entanglement correspond to
finite-dimensional operator solutions of a certain set of non-commutative
equations. We investigate linear system games in the commuting-operator model
of entanglement, where Alice and Bob's measurement operators act on a joint
Hilbert space, and Alice's operators must commute with Bob's operators. We show
that perfect strategies in this model correspond to
possibly-infinite-dimensional operator solutions of the non-commutative
equations. The proof is based around a finitely-presented group associated to
the linear system which arises from the non-commutative equations.


title:
Semi-supervised structured output prediction by local linear regression
  and sub-gradient descent

abstract:
  We propose a novel semi-supervised structured output prediction method based
on local linear regression in this paper. The existing semi-supervise
structured output prediction methods learn a global predictor for all the data
points in a data set, which ignores the differences of local distributions of
the data set, and the effects to the structured output prediction. To solve
this problem, we propose to learn the missing structured outputs and local
predictors for neighborhoods of different data points jointly. Using the local
linear regression strategy, in the neighborhood of each data point, we propose
to learn a local linear predictor by minimizing both the complexity of the
predictor and the upper bound of the structured prediction loss. The
minimization problem is solved by sub-gradient descent algorithms. We conduct
experiments over two benchmark data sets, and the results show the advantages
of the proposed method.


title:
Semi-Supervised Domain Adaptation for Weakly Labeled Semantic Video
  Object Segmentation

abstract:
  Deep convolutional neural networks (CNNs) have been immensely successful in
many high-level computer vision tasks given large labeled datasets. However,
for video semantic object segmentation, a domain where labels are scarce,
effectively exploiting the representation power of CNN with limited training
data remains a challenge. Simply borrowing the existing pretrained CNN image
recognition model for video segmentation task can severely hurt performance. We
propose a semi-supervised approach to adapting CNN image recognition model
trained from labeled image data to the target domain exploiting both semantic
evidence learned from CNN, and the intrinsic structures of video data. By
explicitly modeling and compensating for the domain shift from the source
domain to the target domain, this proposed approach underpins a robust semantic
object segmentation method against the changes in appearance, shape and
occlusion in natural videos. We present extensive experiments on challenging
datasets that demonstrate the superior performance of our approach compared
with the state-of-the-art methods.


title: Screening of a charged impurity in graphene in a magnetic field

abstract:
  The electron states in the field of a charged impurity in graphene in a
magnetic field are studied numerically. It is shown that a charged impurity
removes the degeneracy of Landau levels converting them into bandlike
structures. As the charge of impurity grows, the repulsion of sublevels of
different Landau levels with the same value of orbital momentum takes place
leading to the redistribution of the wave function profiles of these sublevels
near the impurity. By studying the polarization effects, it is shown in
agreement with the recent experiments that the effective charge of impurity can
be very effectively tuned by chemical potential. If the chemical potential is
situated inside a Landau level, then the charge of impurity is strongly
diminished. In addition, the polarization function in this case has a peak at
zero momentum, which leads to the sign-changing oscillations of the screened
potential as a function of distance. If the chemical potential lies between the
Landau levels, then the screened potential does not change sign, the screening
is minimal, and the charged impurity can strongly affect the electron spectrum.


title:
Tropicalization of theta characteristics, double covers, and Prym
  varieties

abstract:
  We study the behavior of theta characteristics on an algebraic curve under
the specialization map to a tropical curve. We show that each effective theta
characteristic on the tropical curve is the specialization of $2^{g-1}$ even
theta characteristics and $2^{g-1}$ odd theta characteristics. We then study
the relationship between unramified double covers of a tropical curve and its
theta characteristics, and use this to define the tropical Prym variety.


title: The Formation and Imprinting of Network Effects Among the Business Elite

abstract:
  The business elite constitutes a small but strikingly influential subset of
the population, oftentimes affecting important societal outcomes such as the
consolidation of political power, the adoption of corporate governance
practices, and the stability of national economies more broadly. Here we
analyze a unique dataset of all MBA students at a top 5 MBA program. After
matching students on all available characteristics (e.g., age, grade scores,
industry experience, etc.) - i.e. creating twin pairs - we find that the
distinguishing characteristics between students who do well in job placement
and those who do not is their network. Further, we find that the network
differences between the successful and unsuccessful students develops within
the first month of class and persists thereafter, suggesting a network
imprinting that is persistent. Finally, we find that these effects are
pronounced for students who are at the extreme ends of the distribution on
other measures of success - students with the best expected job placement do
particularly poorly without the right network (descenders), whereas students
with worst expected job placement pull themselves to the top of the placement
hierarchy (ascenders) with the right network.


title: Superconductivity and Charge Density Wave in ZrTe$_{3-x}$Se$_{x}$

abstract:
  Charge density wave (CDW), the periodic modulation of the electronic charge
density, will open a gap on the Fermi surface that commonly leads to decreased
or vanishing conductivity. On the other hand superconductivity, a commonly
believed competing order, features a Fermi surface gap that results in infinite
conductivity. Here we report that superconductivity emerges upon Se doping in
CDW conductor ZrTe$_{3}$ when the long range CDW order is gradually suppressed.
Superconducting critical temperature $T_c(x)$ in ZrTe$_{3-x}$Se$_x$
(${0\leq}x\leq0.1$) increases up to 4 K plateau for
$0.04$$\leq$$x$$\leq$$0.07$. Further increase in Se content results in
diminishing $T_{c}$ and filametary superconductivity. The CDW modes from Raman
spectra are observed in $x$ = 0.04 and 0.1 crystals, where signature of
ZrTe$_{3}$ CDW order in resistivity vanishes. The electronic-scattering for
high $T_{c}$ crystals is dominated by local CDW fluctuations at high
temperures, the resistivity is linear up to highest measured $T=300K$ and
contributes to substantial in-plane anisotropy.


title:
On the detectability of CO molecules in the Interstellar Medium via
  X-ray spectroscopy

abstract:
  We present a study of the detectability of CO molecules in the Galactic
interstellar medium using high-resolution X-ray spectra obtained with the
XMM-Newton Reflection Grating Spectrometer. We analyzed 10 bright low mass
X-ray binaries (LMXBs) to study the CO contribution in their line-of-sights. A
total of 25 observations were fitted with the ISMabs X-ray absorption model
which includes photoabsorption cross-sections for O I, O II, O III and CO. We
performed a Monte-Carlo (MC) simulation analysis of the goodness of fit in
order to estimate the significance of the CO detection. We determine that the
statistical analysis prevents a significant detection of CO molecular X-ray
absorption features, except for the lines-of-sight toward XTE~J1718-330 and
4U~1636-53. In the case of XTE~J1817-330, this is the first report of the
presence of CO along its line-of-sight. Our results reinforce the conclusion
that molecules have a minor contribution to the absorption features in the O
K-edge spectral region. We estimate a CO column density lower limit to perform
a significant detection with XMM-Newton of N(CO) > 6x10^{16} cm-2 for typical
exposure times


title: Development of the MRPC for the TOF system of the MultiPurpose Detector

abstract:
  The Multipurpose Detector (MPD) \cite{cite1.MPD_CDR} is designed to study of
hot and dense baryonic matter in collisions of heavy ions over the atomic mass
range 1--197 at the centre of mass energy up to $\sqrt{S_{NN}}$ = 11 GeV (for
Au79+). The MPD experiment will be carried out at the JINR accelerator complex
NICA \cite{cite2.NICA_CDR} which is under construction. The barrel part of the
MPD consists of various detectors surrounding the interaction point. It
includes a precise tracking system (time projection chamber (TPC) and silicon
inner tracker (IT)) and high-performance particle identification system based
on time-of-flight (TOF) and calorimeter (ECal). The triple-stack multigap
resistive plate chamber is chosen as an active element of the TOF. It provides
good time resolution and long term stability.
  This article presents parameters of the MRPC obtained using the deuteron beam
of JINR accelerator Nuclotron. The time resolution is $\sim$40 ps with
efficiency of 99\%. Rate capability studies resulted with a time resolution of
60 ps and efficiency higher than 90\% on the beam with particle flux densities
up to 2 kHz/cm$^2$.


title:
Rejection of randomly coinciding events in Li$_2$$^{100}$MoO$_4$
  scintillating bolometers using light detectors based on the Neganov-Luke
  effect

abstract:
  Random coincidences of nuclear events can be one of the main background
sources in low-temperature calorimetric experiments looking for neutrinoless
double-beta decay, especially in those searches based on scintillating
bolometers embedding the promising double-beta candidate $^{100}$Mo, because of
the relatively short half-life of the two-neutrino double-beta decay of this
nucleus. We show in this work that randomly coinciding events of the
two-neutrino double decay of $^{100}$Mo in enriched Li$_2$$^{100}$MoO$_4$
detectors can be effectively discriminated by pulse-shape analysis in the light
channel if the scintillating bolometer is provided with a Neganov-Luke light
detector, which can improve the signal-to-noise ratio by a large factor,
assumed here at the level of $\sim 750$ on the basis of preliminary
experimental results obtained with these devices. The achieved pile-up
rejection efficiency results in a very low contribution, of the order of $\sim
6\times10^{-5}$ counts/(keV$\cdot$kg$\cdot$y), to the background counting rate
in the region of interest for a large volume ($\sim 90$ cm$^3$)
Li$_2$$^{100}$MoO$_4$ detector. This background level is very encouraging in
view of a possible use of the Li$_2$$^{100}$MoO$_4$ solution for a bolometric
tonne-scale next-generation experiment as that proposed in the CUPID project.


title:
Enhanced high dynamic range 3D shape measurement based on generalized
  phase-shifting algorithm

abstract:
  It is a challenge for Phase Measurement Profilometry (PMP) to measure objects
with a large range of reflectivity variation across the surface. Saturated or
dark pixels in the deformed fringe patterns captured by the camera will lead to
phase fluctuations and errors. Jiang et al. proposed a high dynamic range
real-time 3D shape measurement method without changing camera exposures. Three
inverted phase-shifted fringe patterns are used to complement three regular
phase-shifted fringe patterns for phase retrieval when any of the regular
fringe patterns are saturated. But Jiang's method still has some drawbacks: (1)
The phases in saturated pixels are respectively estimated by different formulas
for different cases. It is shortage of an universal formula; (2) it cannot be
extended to four-step phase-shifting algorithm because inverted fringe patterns
are the repetition of regular fringe patterns; (3) only three unsaturated
intensity values at every pixel of fringe patterns are chosen for phase
demodulation, lying idle the other unsaturated ones. We proposed a method for
enhanced high dynamic range 3D shape measurement based on generalized
phase-shifting algorithm, which combines the complementary technique of
inverted and regular fringe patterns with generalized phase-shifting algorithm.
Firstly, two sets of complementary phase-shifted fringe patterns, namely
regular and inverted fringe patterns are projected and collected. Then all
unsaturated intensity values at the same camera pixel from two sets of fringe
patterns are selected, and employed to retrieve the phase by generalized
phase-shifting algorithm. Finally, simulations and experiments are conducted to
prove the validity of the proposed method. The results are analyzed and
compared with Jiang's method, which demonstrate that the proposed method not
only expands the scope of Jiang's method, but also improves the measurement
accuracy.


title:
Intensity-only measurement of partially uncontrollable transmission
  matrix: demonstration with wave-field shaping in a microwave cavity

abstract:
  Transmission matrices (TMs) have become a powerful and widely used tool to
describe and control wave propagation in complex media. In certain scenarios
the TM is partially uncontrollable, complicating its identification and use. In
standard optical wavefront shaping experiments, uncontrollable reflections or
additional sources may be the cause; in reverberating cavities, uncontrollable
reflections off the walls have that effect. Here we employ phase retrieval
techniques to identify such a partially uncontrollable system's TM solely based
on random intensity-only reference measurements. We demonstrate the feasibility
of our method by focusing both on a single target as well as on multiple
targets in a microwave cavity, using a phase-binary
Spatial-Microwave-Modulator.


title: Multi-channel front-end board for SiPM readout

abstract:
  We describe a novel high-speed front-end electronic board (FEB) for
interfacing an array of 32 Silicon Photo-multipliers (SiPM) with a computer.
The FEB provides individually adjustable bias on the SiPMs, and performs
low-noise analog signal amplification, conditioning and digitization. It
provides event timing information accurate to 1.3 ns RMS. The back-end data
interface is realized on the basis of 100 Mbps Ethernet. The design allows
daisy-chaining of up to 256 units into one network interface, thus enabling
compact and efficient readout schemes for multi-channel scintillating
detectors, using SiPMs as photo-sensors.


title: On Deposition of the Product of Demazure Atoms and Demazure Characters

abstract:
  This paper studies the properties of Demazure atoms and characters using
linear operators and also tableaux-combinatorics. It proves the atom-positivity
property of the product of a dominating monomial and an atom, which was an open
problem. Furthermore, it provides a combinatorial proof to the key-positivity
property of the product of a dominating monomial and a key using skyline
fillings, an algebraic proof to the key-positivity property of the product of a
Schur function and a key using linear operator and verifies the first open case
for the conjecture of key-positivity of the product of two keys using linear
operators and polytopes.


title:
First simultaneous microlensing observations by two space telescopes:
  $Spitzer$ & $Swift$ reveal a brown dwarf in event OGLE-2015-BLG-1319

abstract:
  Simultaneous observations of microlensing events from multiple locations
allow for the breaking of degeneracies between the physical properties of the
lensing system, specifically by exploring different regions of the lens plane
and by directly measuring the "microlens parallax". We report the discovery of
a 30-55$M_J$ brown dwarf orbiting a K dwarf in microlensing event
OGLE-2015-BLG-1319. The system is located at a distance of $\sim$5 kpc toward
the Galactic bulge. The event was observed by several ground-based groups as
well as by $Spitzer$ and $Swift$, allowing the measurement of the physical
properties. However, the event is still subject to an 8-fold degeneracy, in
particular the well-known close-wide degeneracy, and thus the projected
separation between the two lens components is either $\sim$0.25 AU or $\sim$45
AU. This is the first microlensing event observed by $Swift$, with the UVOT
camera. We study the region of microlensing parameter space to which $Swift$ is
sensitive, finding that while for this event $Swift$ could not measure the
microlens parallax with respect to ground-based observations, it can be
important for other events. Specifically, for detecting nearby brown dwarfs and
free-floating planets in high magnification events.


title: On the nature of hydrostatic equilibrium in galaxy clusters

abstract:
  In this paper we investigate the level of hydrostatic equilibrium (HE) in the
intra-cluster medium of simulated galaxy clusters, extracted from
state-of-the-art cosmological hydrodynamical simulations performed with the
Smoothed-Particle-Hydrodynamic code GADGET-3. These simulations include several
physical processes, among which stellar and AGN feedback, and have been
performed with an improved version of the code that allows for a better
description of hydrodynamical instabilities and gas mixing processes.
Evaluating the radial balance between the gravitational and hydrodynamical
forces, via the gas accelerations generated, we effectively examine the level
of HE in every object of the sample, its dependence on the radial distance from
the center and on the classification of the cluster in terms of either
cool-coreness or dynamical state. We find an average deviation of 10-20% out to
the virial radius, with no evident distinction between cool-core and
non-cool-core clusters. Instead, we observe a clear separation between regular
and disturbed systems, with a more significant deviation from HE for the
disturbed objects. The investigation of the bias between the hydrostatic
estimate and the total gravitating mass indicates that, on average, this traces
very well the deviation from HE, even though individual cases show a more
complex picture. Typically, in the radial ranges where mass bias and deviation
from HE are substantially different, the gas is characterized by a significant
amount of random motions (>~30 per cent), relative to thermal ones. As a
general result, the HE-deviation and mass bias, at given interesting distance
from the cluster center, are not very sensitive to the temperature
inhomogeneities in the gas.


title:
Beyond the Kuiper Belt Edge: New High Perihelion Trans-Neptunian Objects
  With Moderate Semi-major Axes and Eccentricities

abstract:
  We have been conducting a survey for distant solar system objects beyond the
Kuiper Belt edge (~50 AU) with new wide-field cameras on the Subaru 8 meter and
CTIO 4 meter telescopes. We are interested in the orbits of objects that are
decoupled from the giant planet region in order to understand the structure of
the outer solar system, including whether a massive planet exists beyond a few
hundred AU as first reported by Trujillo and Sheppard (2014). In addition to
discovering extreme trans-Neptunian objects detailed elsewhere, we have found
several objects with high perihelia (q>40 AU) that differ from the extreme and
inner Oort cloud objects due to their moderate semi-major axes (50<a<100 AU)
and eccentricities (e<0.3). Newly discovered objects 2014 FZ71 and 2015 FJ345
have the third and fourth highest perihelia known after Sedna and 2012 VP113,
yet their orbits are not nearly as eccentric or distant. We found several of
these high perihelion but moderate orbit objects and observe that they are
mostly near Neptune mean motion resonances and have significant inclinations
(i>20 degrees). These moderate objects likely obtained their unusual orbits
through combined interactions with Neptune's mean motion resonances and the
Kozai resonance, similar to the origin scenarios for 2004 XR190. We also find
the distant 2008 ST291 has likely been modified by the MMR+KR mechanism through
the 6:1 Neptune resonance. We discuss these moderately eccentric, distant
objects along with some other interesting low inclination outer classical belt
objects like 2012 FH84 discovered in our ongoing survey.


title: Aspects of Galileon Non-Renormalization

abstract:
  We discuss non-renormalization theorems applying to galileon field theories
and their generalizations. Galileon theories are similar in many respects to
other derivatively coupled effective field theories, including general
relativity and $P(X)$ theories. In particular, these other theories also enjoy
versions of non-renormalization theorems that protect certain operators against
corrections from self-loops. However, we argue that the galileons are
distinguished by the fact that they are not renormalized even by loops of other
heavy fields whose couplings respect the galileon symmetry.


title:
Kompaneets Model Fitting of the Orion-Eridanus Superbubble II: Thinking
  Outside of Barnard's Loop

abstract:
  The Orion star-forming region is the nearest active high-mass star-forming
region and has created a large superbubble, the Orion-Eridanus superbubble.
Recent work by Ochsendorf et al. has extended the accepted boundary of the
superbubble. We fit Kompaneets models of superbubbles expanding in exponential
atmospheres to the new, larger shape of the Orion-Eridanus superbubble. We find
that this larger morphology of the superbubble is consistent with the evolution
of the superbubble being primarily controlled by expansion into the exponential
Galactic disk ISM if the superbubble is oriented with the Eridanus side farther
from the Sun than the Orion side. Unlike previous Kompaneets model fits that
required abnormally small scale heights for the Galactic disk (<40 pc), we find
morphologically consistent models with scale heights of 80 pc, similar to that
expected for the Galactic disk.


title: Asymptotic Entropy Bounds

abstract:
  We show that known entropy bounds constrain the information carried off by
radiation to null infinity. We consider distant, planar null hypersurfaces in
asymptotically flat spacetime. Their focussing and area loss can be computed
perturbatively on a Minkowski background, yielding entropy bounds in terms of
the energy flux of the outgoing radiation. In the asymptotic limit, we obtain
boundary versions of the Quantum Null Energy Condition, of the Generalized
Second Law, and of the Quantum Bousso Bound.


title:
Concise estimate of the expected number of detections for stellar-mass
  binary black holes by eLISA

abstract:
  We study prospects for detecting extragalactic binary black holes similar to
GW150914 by evolved Laser Interferometer Space Antenna (eLISA). We find that
the majority of detected binary black holes will not merge within reasonable
observation periods of eLISA in any configuration. While long-arm detectors are
highly desired for promoting multiband gravitational-wave astronomy by
increasing the detections of merging binaries, the number of total detections
can be increased also by improving the acceleration noise. A monochromatic
approximation works well to derive semiquantitative features of observational
prospects for non-merging binaries with clearly indicating the parameter
dependence. Our estimate also suggests that the number of galaxies in the error
volume is so small that the host galaxy may be determined uniquely with high
confidence.


title: Gap Opening in 3D: Single Planet Gaps

abstract:
  Giant planets can clear deep gaps when embedded in 2D (razor-thin) viscous
circumstellar disks. We show by direct simulation that giant planets are just
as capable of carving out gaps in 3D. Surface density maps are similar between
2D and 3D, even in detail. In particular, the scaling $\Sigma_{\rm gap} \propto
q^{-2}$ of gap surface density with planet mass, derived from a global
"zero-dimensional" balance of Lindblad and viscous torques, applies equally
well to results obtained at higher dimensions. Our 3D simulations reveal
extensive, near-sonic, meridional flows both inside and outside the gaps; these
large-scale circulations might bear on disk compositional gradients, in dust or
other chemical species. At high planet mass, gap edges are mildly Rayleigh
unstable and intermittently shed streams of material into the gap - less so in
3D than in 2D.


title:
The Evolution and Fate of Super-Chandrasekhar Mass White Dwarf Merger
  Remnants

abstract:
  We present stellar evolution calculations of the remnant of the merger of two
carbon-oxygen white dwarfs (CO WDs). We focus on cases that have a total mass
in excess of the Chandrasekhar mass. After the merger, the remnant manifests as
an $L \sim 3 \times 10^4 L_\odot$ source for $\sim 10^4$ yr. A dusty wind may
develop, leading these sources to be self-obscured and to appear similar to
extreme AGB stars. Roughly $\sim 10$ such objects should exist in the Milky Way
and M31 at any time. As found in previous work, off-center carbon fusion is
ignited within the merger remnant and propagates inward via a carbon flame,
converting the WD to an oxygen-neon (ONe) composition. By following the
evolution for longer than previous calculations, we demonstrate that after
carbon-burning reaches the center, neutrino-cooled Kelvin-Helmholtz contraction
leads to off-center neon ignition in remnants with masses $\ge 1.35 M_\odot$.
The resulting neon-oxygen flame converts the core to a silicon WD. Thus,
super-Chandrasekhar WD merger remnants do not undergo electron-capture induced
collapse as traditionally assumed. Instead, if the remnant mass remains above
the Chandrasekhar mass, we expect that it will form a low-mass iron core and
collapse to form a neutron star. Remnants that lose sufficient mass will end up
as massive, isolated ONe or Si WDs.


title:
Choose to smooth: Gaussian streaming with the truncated Zel'dovich
  approximation

abstract:
  We calculate the dark matter halo correlation function in redshift space
using the Gaussian streaming model (GSM). To determine the scale dependent
functions entering the streaming model we use local Lagrangian bias together
with Convolution Lagrangian perturbation theory (CLPT) which constitutes an
approximation to the Post-Zel'dovich approximation. On the basis of N-body
simulations we demonstrate that a smoothing of the initial conditions with the
Lagrangian radius improves the Zel'dovich approximation and its ability to
predict the displacement field of proto-halos. Based on this observation we
implement a "truncated" CLPT by smoothing the initial power spectrum and
investigate the dependence of the streaming model ingredients on the smoothing
scale. We find that the real space correlation functions of halos and their
mean pairwise velocity are optimised if the coarse graining scale is chosen to
be 1 Mpc/h at z=0, while the pairwise velocity dispersion is optimised if the
smoothing scale is chosen to be the Lagrangian size of the halo. We compare
theoretical results for the halo correlation function in redshift space to
measurements within the Horizon Run 2 N-body simulation halo catalog. We find
that this simple two-filter smoothing procedure in the spirit of the truncated
Zel'dovich approximation significantly improves the GSM+CLPT prediction of the
redshift space halo correlation function over the whole mass range from large
galaxy to galaxy cluster-sized halos.


title:
Static Einstein-Maxwell black holes with no spatial isometries in AdS
  space

abstract:
  We explicitly construct static black hole solutions to the fully non-linear,
D=4, Einstein-Maxwell-AdS equations that have no continuous spatial symmetries.
These black holes have a smooth, topologically spherical horizon (section), but
without isometries, and approach, asymptotically, global AdS spacetime. They
are interpreted as bound states of a horizon with the Einstein-Maxwell-AdS
solitons recently discovered, for appropriate boundary data. In sharp contrast
with the uniqueness results for Minkowski electrovacuum, the existence of these
black holes shows that single, equilibrium, BH solutions in AdS-electrovacuum
admit an arbitrary multipole structure.


title: Grand Unification without Proton Decay

abstract:
  It is commonly believed that grand unified theories (GUTs) predict proton
decay. This is because the exchange of extra GUT gauge bosons gives rise to
dimension 6 proton decay operators. We show that there exists a class of GUTs
in which these operators are absent. Many string and supergravity models in the
literature belong to this class.


title: Cold, clumpy accretion onto an active supermassive black hole

abstract:
  Supermassive black holes in galaxy centres can grow by the accretion of gas,
liberating energy that might regulate star formation on galaxy-wide scales. The
nature of the gaseous fuel reservoirs that power black hole growth is
nevertheless largely unconstrained by observations, and is instead routinely
simplified as a smooth, spherical inflow of very hot gas. Recent theory and
simulations instead predict that accretion can be dominated by a stochastic,
clumpy distribution of very cold molecular clouds - a departure from the "hot
mode" accretion model - although unambiguous observational support for this
prediction remains elusive. Here we report observations that reveal a cold,
clumpy accretion flow towards a supermassive black hole fuel reservoir in the
nucleus of the Abell 2597 Brightest Cluster Galaxy (BCG), a nearby (redshift
z=0.0821) giant elliptical galaxy surrounded by a dense halo of hot plasma.
Under the right conditions, thermal instabilities can precipitate from this hot
gas, producing a rain of cold clouds that fall toward the galaxy's centre,
sustaining star formation amid a kiloparsec-scale molecular nebula that
inhabits its core. The observations show that these cold clouds also fuel black
hole accretion, revealing "shadows" cast by the molecular clouds as they move
inward at about 300 kilometres per second towards the active supermassive black
hole in the galaxy centre, which serves as a bright backlight. Corroborating
evidence from prior observations of warmer atomic gas at extremely high spatial
resolution, along with simple arguments based on geometry and probability,
indicate that these clouds are within the innermost hundred parsecs of the
black hole, and falling closer towards it.


title: Strong CMB Constraint On P-Wave Annihilating Dark Matter

abstract:
  We consider a dark sector consisting of dark matter that is a Dirac fermion
and a scalar mediator. This model has been extensively studied in the past. If
the scalar couples to the dark matter in a parity conserving manner then dark
matter annihilation to two mediators is dominated by the P-wave channel and
hence is suppressed at very low momentum. The indirect detection constraint
from the anisotropy of the Cosmic Microwave Background is usually thought to be
absent in the model because of this suppression. In this letter we show that
dark matter annihilation to bound states occurs through the S-wave and hence
there is a constraint on the parameter space of the model from the Cosmic
Microwave Background.


title: The superradiant instability regime of the spinning Kerr black hole

abstract:
  Spinning Kerr black holes are known to be superradiantly unstable to massive
scalar perturbations. We here prove that the instability regime of the composed
Kerr-black-hole-massive-scalar-field system is bounded from above by the
dimensionless inequality $M\mu < m \cdot \sqrt{{{2(1+\gamma)
(1-\sqrt{1-\gamma^2}) - \gamma^2} \over {4\gamma^2}}}$, where $\{\mu,m\}$ are
respectively the proper mass and azimuthal harmonic index of the scalar field
and $\gamma\equiv r_-/r_+$ is the dimensionless ratio between the horizon radii
of the black hole. It is further shown that this {\it analytically} derived
upper bound on the superradiant instability regime of the spinning Kerr black
hole agrees with recent {\it numerical} computations of the instability
resonance spectrum.


title: Sifting Common Information from Many Variables

abstract:
  Measuring the relationship between any pair of variables is a rich and active
area of research that is central to scientific practice. In contrast,
characterizing the common information among any group of variables is typically
a theoretical exercise with few practical methods for high-dimensional data. A
promising solution would be a multivariate generalization of the famous Wyner
common information, but this approach relies on solving an apparently
intractable optimization problem. We leverage the recently introduced
information sieve decomposition to formulate an incremental version of the
common information problem that admits a simple fixed point solution, fast
convergence, and complexity that is linear in the number of variables. This
scalable approach allows us to demonstrate the usefulness of common information
in high-dimensional learning problems. The sieve outperforms standard methods
on dimensionality reduction tasks, solves a blind source separation problem
that cannot be solved with ICA, and accurately recovers structure in brain
imaging data.


title:
Spin-Orbit Interaction and Kondo Scattering at the PrAlO$_3$/SrTiO$_3$
  Interface: Effects of Oxygen Content

abstract:
  We report the effect of oxygen pressure during growth ($P_{O_{2}}$) on the
electronic and magnetic properties of PrAlO$_3$ films grown on $\rm
TiO_{2}$-terminated SrTiO$_3$ substrates. Resistivity measurements show an
increase in the sheet resistance as $P_{O_{2}}$ is increased. The temperature
dependence of the sheet resistance at low temperatures is consistent with Kondo
theory for $P_{O_{2}} \ge 10^{-5}$ torr. Hall effect data exhibit a complex
temperature dependence that suggests a compensated carrier density. We observe
behavior consistent with two different types of carriers at interfaces grown at
$P_{O_{2}} \ge 10^{-4}$ torr. For these interfaces, we measured a moderate
positive magnetoresistance (MR) due to a strong spin-orbit (SO) interaction at
low magnetic fields that evolves into a larger negative MR at high fields.
Positive high MR values are associated with samples where a fraction of
carriers are derived from oxygen vacancies. Analysis of the MR data permitted
the extraction of the SO interaction critical field ( e.g. $ H_{SO}=$1.25 T for
$P_{O_{2}}=10^{-5}$ torr). The weak anti-localization effect due to a strong SO
interaction becomes smaller for higher $P_{O_{2}}$ grown samples, where MR
values are dominated by the Kondo effect, particularly at high magnetic fields.


title:
A Total Molecular Gas Mass Census in z~2-3 Star-forming Galaxies: Low-J
  CO Excitation Probes of Galaxies' Evolutionary States

abstract:
  We present CO(1-0) observations obtained at the Karl G. Jansky Very Large
Array (VLA) for 14 z~2 galaxies with existing CO(3-2) measurements, including
11 galaxies which contain active galactic nuclei (AGN) and three submillimeter
galaxies (SMGs). We combine this sample with an additional 15 z~2 galaxies from
the literature that have both CO(1-0) and CO(3-2) measurements in order to
evaluate differences in CO excitation between SMGs and AGN host galaxies,
measure the effects of CO excitation on the derived molecular gas properties of
these populations, and to look for correlations between the molecular gas
excitation and other physical parameters. With our expanded sample of
CO(3-2)/CO(1-0) line ratio measurements, we do not find a statistically
significant difference in the mean line ratio between SMGs and AGN host
galaxies as found in the literature, instead finding r_3,1=1.03+/-0.50 for AGN
host galaxies and r_3,1=0.78+/-0.27 for SMGs (or r_3,1=0.90+/-0.40 for both
populations combined). We also do not measure a statistically significant
difference between the distributions of the line ratios for these populations
at the p=0.05 level, although this result is less robust. We find no excitation
dependence on the index or offset of the integrated Schmidt-Kennicutt relation
for the two CO lines, and obtain indices consistent with N=1 for the various
sub-populations. However, including low-z "normal" galaxies increases our
best-fit Schmidt-Kennicutt index to N~1.2. While we do not reproduce
correlations between the CO line width and luminosity, we do reproduce
correlations between CO excitation and star formation efficiency.


title:
A moving mesh unstaggered constrained transport scheme for
  magnetohydrodynamics

abstract:
  We present a constrained transport (CT) algorithm for solving the 3D ideal
magnetohydrodynamic (MHD) equations on a moving mesh, which maintains the
divergence-free condition on the magnetic field to machine-precision. Our CT
scheme uses an unstructured representation of the magnetic vector potential,
making the numerical method simple and computationally efficient. The scheme is
implemented in the moving mesh code Arepo. We demonstrate the performance of
the approach with simulations of driven MHD turbulence, a magnetized disc
galaxy, and a cosmological volume with primordial magnetic field. We compare
the outcomes of these experiments to those obtained with a previously
implemented Powell divergence-cleaning scheme. While CT and the Powell
technique yield similar results in idealized test problems, some differences
are seen in situations more representative of astrophysical flows. In the
turbulence simulations, the Powell cleaning scheme artificially grows the mean
magnetic field, while CT maintains this conserved quantity of ideal MHD. In the
disc simulation, CT gives slower magnetic field growth rate and saturates to
equipartition between the turbulent kinetic energy and magnetic energy, whereas
Powell cleaning produces a dynamically dominant magnetic field. Such difference
has been observed in adaptive-mesh refinement codes with CT and
smoothed-particle hydrodynamics codes with divergence-cleaning. In the
cosmological simulation, both approaches give similar magnetic amplification,
but Powell exhibits more cell-level noise. CT methods in general are more
accurate than divergence-cleaning techniques, and, when coupled to a moving
mesh can exploit the advantages of automatic spatial/temporal adaptivity and
reduced advection errors, allowing for improved astrophysical MHD simulations.

categories: astro-ph.IM astro-ph.CO physics.comp-ph physics.flu-dyn


title:
A Formal Semantic for UML 2.0 Activity Diagram based on Institution
  Theory

abstract:
  Giving a formal semantic to an UML Activity diagram (UML AD) is a hard task.
The reason of this difficulty is the ambiguity and the absence of a precise
formal semantic of such semi-formal formalism. A variety of semantics exist in
the literature having tackled the aspects covered by this language. We can give
as example denotational, functional and compositional semantics. To cope with
the recent tendency which gave a heterogeneous semantic to UML diagrams, we aim
to define an algebraic presentation of the semantic of UML AD. In this work, we
define a formal semantic of UML 2.0 AD based on institution theory. For UML AD
formalism, which is a graphical language, no precise formal semantic is given
to it. We use the institution theory to define the intended semantic. Thus, the
UML AD formalism will be defined in its own natural semantic.


title:
High Capacity Image Steganography using Adjunctive Numerical
  Representations with Multiple Bit-Plane Decomposition Methods

abstract:
  LSB steganography is a one of the most widely used methods for implementing
covert data channels in image file exchanges [1][2]. The low computational
complexity and implementation simplicity of the algorithm are significant
factors for its popularity with the primary reason being low image distortion.
Many attempts have been made to increase the embedding capacity of LSB
algorithms by expanding into the second or third binary layers of the image
while maintaining a low probability of detection with minimal distortive
effects [2][3][4]. In this paper, we introduce an advanced technique for
covertly embedding data within images using redundant number system
decomposition over non-standard digital bit planes. Both grayscale and
bit-mapped images are equally effective as cover files. It will be shown that
this unique steganography method has minimal visual distortive affects while
also preserving the cover file statistics, making it less susceptible to most
general steganography detection algorithms.


title:
Precision direct photon spectra at high energy and comparison to the 8
  TeV ATLAS data

abstract:
  The direct photon spectrum is computed to the highest currently available
precision and compared to ATLAS data from 8 TeV collisions at the LHC. The
prediction includes threshold resummation at next-to-next-to-next-to-leading
logarithmic order through the program PeTeR, matched to next-to-leading fixed
order with fragmentation effects using JetPhox and includes the resummation of
leading-logarithmic electroweak Sudakov effects. Remarkably, improved agreement
with data can be seen when each component of the calculation is added
successively. This comparison demonstrates the importance of both threshold
logs and electroweak Sudakov effects. Numerical values for the predictions are
included.


title: NOUS: Construction and Querying of Dynamic Knowledge Graphs

abstract:
  The ability to construct domain specific knowledge graphs (KG) and perform
question-answering or hypothesis generation is a transformative capability.
Despite their value, automated construction of knowledge graphs remains an
expensive technical challenge that is beyond the reach for most enterprises and
academic institutions. We propose an end-to-end framework for developing custom
knowledge graph driven analytics for arbitrary application domains. The
uniqueness of our system lies A) in its combination of curated KGs along with
knowledge extracted from unstructured text, B) support for advanced trending
and explanatory questions on a dynamic KG, and C) the ability to answer queries
where the answer is embedded across multiple data sources.


title: A Note on Optimality of Quantum Circuits over Metaplectic Basis

abstract:
  Metaplectic quantum basis is a universal multi-qutrit quantum basis, formed
by the ternary Clifford group and the axial reflection gate $R=|0\rangle
\langle 0| + |1\rangle \langle 1| - |2\rangle \langle 2|$. It is arguably, a
ternary basis with the simplest geometry. Recently Cui, Kliuchnikov, Wang and
the Author have proposed a compilation algorithm to approximate any two-level
Householder reflection to precision $\varepsilon$ by a metaplectic circuit of
$R$-count at most $C \, \log_3(1/\varepsilon) + O(\log \log 1/\varepsilon)$
with $C=8$. A new result in this note takes the constant down to $C=5$ for
non-exceptional target reflections under a certain credible number-theoretical
conjecture. The new method increases the chances of obtaining a truly optimal
circuit but may not guarantee the true optimality. Efficient approximations of
an important ternary quantum gate proposed by Howard, Campbell and others is
also discussed. Apart from this, the note is mostly didactical: we demonstrate
how to leverage Lenstra's integer geometry algorithm from 1983 for circuit
synthesis.


title:
Decentralized AP Selection in Large-Scale Wireless LANs Considering
  Multi-AP Interference

abstract:
  Densification of access points (APs) in wireless local area networks (WLANs)
increases the interference and the contention domains of each AP due to
multiple overlapped basic service sets (BSSs). Consequently, high interference
from multiple co-channel BSS at the target AP impairs system performance. To
improve system performance in the presence of multi-BSSs interference, we
propose a decentralized AP selection scheme that takes interference at the
candidate APs into account and selects AP that offers best
signal-interference-plus noise ratio (SINR). In the proposed algorithm, the AP
selection process is distributed at the user stations (STAs) and is based on
the estimated SINR in the downlink. Estimating SINR in the downlink helps
capture the effect of interference from neighboring BSSs or APs. Based on a
simulated large-scale 802.11 network, the proposed scheme outperforms the
strongest signal first (SSF) AP selection scheme used in current 802.11
standards as well as the mean probe delay (MPD) AP selection algorithm in [3];
it achieves 99% and 43% gains in aggregate throughput over SSF and MPD,
respectively. While increasing STA densification, the proposed scheme is shown
to increase aggregate network performance.


title: Vortex states in a non-Abelian magnetic field

abstract:
  A type-II superconductor survives in an external magnetic field by admitting
an Abrikosov lattice of quantized vortices. This is an imprint of the
Aharonov-Bohm effect created by the Abelian U(1) gauge field. The simplest
non-Abelian analogue of such a gauge field, which belongs to the SU(2) symmetry
group, can be found in topological insulators. Here we discover a
superconducting ground state with a lattice of SU(2) vortices in a simple
two-dimensional model that presents an SU(2) "magnetic" field (invariant under
time-reversal) to attractively interacting fermions. The model directly
captures the correlated topological insulator quantum well, and approximates
one channel for instabilities on the Kondo topological insulator surface. Due
to its simplicity, the model might become amenable to cold atom simulations in
the foreseeable future. The vitality of low-energy vortex states born out of
SU(2) "magnetic" fields is promising for the creation of incompressible vortex
liquids with non-Abelian fractional excitations.


title: Solving the Quantum Many-Body Problem with Artificial Neural Networks

abstract:
  The challenge posed by the many-body problem in quantum physics originates
from the difficulty of describing the non-trivial correlations encoded in the
exponential complexity of the many-body wave function. Here we demonstrate that
systematic machine learning of the wave function can reduce this complexity to
a tractable computational form, for some notable cases of physical interest. We
introduce a variational representation of quantum states based on artificial
neural networks with variable number of hidden neurons. A
reinforcement-learning scheme is then demonstrated, capable of either finding
the ground-state or describing the unitary time evolution of complex
interacting quantum systems. We show that this approach achieves very high
accuracy in the description of equilibrium and dynamical properties of
prototypical interacting spins models in both one and two dimensions, thus
offering a new powerful tool to solve the quantum many-body problem.


title:
Community detection in networks: Modularity optimization and maximum
  likelihood are equivalent

abstract:
  We demonstrate an exact equivalence between two widely used methods of
community detection in networks, the method of modularity maximization in its
generalized form which incorporates a resolution parameter controlling the size
of the communities discovered, and the method of maximum likelihood applied to
the special case of the stochastic block model known as the planted partition
model, in which all communities in a network are assumed to have statistically
similar properties. Among other things, this equivalence provides a
mathematically principled derivation of the modularity function, clarifies the
conditions and assumptions of its use, and gives an explicit formula for the
optimal value of the resolution parameter.


title: On additive bases of sets with small product set

abstract:
  We prove that finite sets of real numbers satisfying $|AA| \leq
|A|^{1+\epsilon}$ with sufficiently small $\epsilon > 0$ cannot have small
additive bases nor can they be written as a set of sums $B+C$ with $|B|, |C|
\geq 2$. The result can be seen as a real analog of the conjecture of
S\'ark\"ozy that multiplicative subgroups of finite fields of prime order are
additively irreducible.


title: Better Conditional Density Estimation for Neural Networks

abstract:
  The vast majority of the neural network literature focuses on predicting
point values for a given set of response variables, conditioned on a feature
vector. In many cases we need to model the full joint conditional distribution
over the response variables rather than simply making point predictions. In
this paper, we present two novel approaches to such conditional density
estimation (CDE): Multiscale Nets (MSNs) and CDE Trend Filtering. Multiscale
nets transform the CDE regression task into a hierarchical classification task
by decomposing the density into a series of half-spaces and learning boolean
probabilities of each split. CDE Trend Filtering applies a k-th order graph
trend filtering penalty to the unnormalized logits of a multinomial classifier
network, with each edge in the graph corresponding to a neighboring point on a
discretized version of the density. We compare both methods against plain
multinomial classifier networks and mixture density networks (MDNs) on a
simulated dataset and three real-world datasets. The results suggest the two
methods are complementary: MSNs work well in a high-data-per-feature regime and
CDE-TF is well suited for few-samples-per-feature scenarios where overfitting
is a primary concern.


title:
High refractive index Fresnel lens on a fiber fabricated by nanoimprint
  lithography for immersion applications

abstract:
  In this Letter we present a Fresnel lens fabricated on the end of an optical
fiber. The lens is fabricated using nanoimprint lithography of a functional
high refractive index material, which is suitable for mass production. The main
advantage of the presented Fresnel lens compared to a conventional fiber lens
is its high refractive index (n=1.69), which enables efficient light focusing
even inside other media such as water or adhesive. Measurement of the lens
performance in an immersion liquid (n=1.51) shows a near diffraction limited
focal spot of 810 nm in diameter at the 1/e2 intensity level for a wavelength
of 660 nm. Applications of such fiber lenses include integrated optics, optical
trapping and fiber probes.


title:
Cosmic Infrared Background anisotropies as a window into primordial
  non-Gaussianity

abstract:
  The angular power spectrum of the cosmic infrared background (CIB) is a
sensitive probe of the local primordial bispectrum. CIB measurements are
integrated over a large volume so that the scale dependent bias from the
primordial non-Gaussianity leaves a strong signal in the CIB power spectrum.
Although galactic dust dominates over the non-Gaussian CIB signal, it is
possible to mitigate the dust contamination with enough frequency channels,
especially if high frequencies such as the Planck 857 GHz channel are
available. We show that, in this case, measurements of the cosmic microwave
background from future space missions should be able to probe the local
bispectrum shape down to an amplitude |f_nl| < 1.


title: The role of cosmic ray pressure in accelerating galactic outflows

abstract:
  We study the formation of galactic outflows from supernova explosions (SNe)
with the moving-mesh code AREPO in a stratified column of gas with a surface
density similar to the Milky Way disk at the solar circle. We compare different
simulation models for SNe placement and energy feedback, including cosmic rays
(CR), and find that models that place SNe in dense gas and account for CR
diffusion are able to drive outflows with similar mass loading as obtained from
a random placement of SNe with no CRs. Despite this similarity, CR-driven
outflows differ in several other key properties including their overall
clumpiness and velocity. Moreover, the forces driving these outflows originate
in different sources of pressure, with the CR diffusion model relying on
non-thermal pressure gradients to create an outflow driven by internal pressure
and the random-placement model depending on kinetic pressure gradients to
propel a ballistic outflow. CRs therefore appear to be non-negligible physics
in the formation of outflows from the interstellar medium.


title:
Multi-messenger light curves from gamma-ray bursts in the internal shock
  model

abstract:
  Gamma-ray bursts (GRBs) are promising as sources of neutrinos and cosmic
rays. In the internal shock scenario, blobs of plasma emitted from a central
engine collide within a relativistic jet and form shocks, leading to particle
acceleration and emission. Motivated by present experimental constraints and
sensitivities, we improve the predictions of particle emission by investigating
time-dependent effects from multiple shocks. We produce synthetic light curves
with different variability timescales that stem from properties of the central
engine. For individual GRBs, qualitative conclusions about model parameters,
neutrino production efficiency, and delays in high-energy gamma rays can be
deduced from inspection of the gamma-ray light curves. GRBs with fast time
variability without additional prominent pulse structure tend to be efficient
neutrino emitters, whereas GRBs with fast variability modulated by a broad
pulse structure can be inefficient neutrino emitters and produce delayed
high-energy gamma-ray signals. Our results can be applied to quantitative tests
of the GRB origin of ultra-high-energy cosmic rays, and have the potential to
impact current and future multi-messenger searches.


title:
Subspace stabilizers and maximal subgroups of exceptional groups of Lie
  type

abstract:
  In 1998, Liebeck and Seitz introduced a constant $t(G)$, dependent on the
root system of a reductive algebraic group $G$ and proved that if $x$ is a
semisimple element of order greater than $t(G)$ in $G$ then there exists an
infinite subgroup of $G$ stabilizing the same subspaces of $L(G)$ as $x$. The
values for $t(G)$ are $12$, $68$, $124$ and $388$ for $G=G_2,F_4,E_6,E_7$
respectively. In this paper we obtain a similar result for these groups and the
minimal module $V_{\mathrm{min}}$, obtaining significantly smaller numbers,
namely $4$, $18$, $27$ and $75$ respectively (with some small conditions on the
element $x$ that are not important for applications). Note that both $t(G)$ and
these new bounds are sharp. As a corollary we eliminate several potential
maximal subgroups $\mathrm{PSL}_2(q_0)$ of these groups that seem difficult to
eliminate through other means, along with other groups.
  This paper forms part of the author's programme to vastly reduce the number
of putative maximal subgroups of exceptional groups of Lie type.


title:
Intermediate subalgebras and bimodules for crossed products of general
  von Neumann algebras

abstract:
  Let $G$ be a discrete group acting on a von Neumann algebra $M$ by properly
outer $*$-automorphisms. In this paper we study the containment $M \subseteq
M\rtimes_\alpha G$ of $M$ inside the crossed product. We characterize the
intermediate von Neumann algebras, extending earlier work of other authors in
the factor case. We also determine the $M$-bimodules that are closed in the
Bures topology and which coincide with the $w^*$-closed ones under a mild
hypothesis on $G$. We use these results to obtain a general version of Mercer's
theorem concerning the extension of certain isometric $w^*$-continuous maps on
$M$-bimodules to $*$-automorphisms of the containing von Neumann algebras.


title: Drawing the Almost Convex Set in an Integer Grid of Minimum Size

abstract:
  In 2001, K\'arolyi, Pach and T\'oth introduced a family of point sets to
solve an Erd\H{o}s-Szekeres type problem; which have been used to solve several
other Ed\H{o}s-Szekeres type problems. In this paper we refer to these sets as
nested almost convex sets. A nested almost convex set $\mathcal{X}$ has the
property that the interior of every triangle determined by three points in the
same convex layer of $\mathcal{X}$, contains exactly one point of
$\mathcal{X}$. In this paper, we introduce a characterization of nested almost
convex sets. Our characterization implies that there exists at most one (up to
order type) nested almost convex set of $n$ points. We use our characterization
to obtain a linear time algorithm to construct nested almost convex sets of $n$
points, with integer coordinates of absolute values at most $O(n^{\log_2 5})$.
Finally, we use our characterization to obtain an $O(n\log n)$-time algorithm
to determine whether a set of points is a nested almost convex set.


title:
Finite element method to solve the spectral problem for arbitrary
  self-adjoint extensions of the Laplace-Beltrami operator on manifolds with a
  boundary

abstract:
  A numerical scheme to compute the spectrum of a large class of self-adjoint
extensions of the Laplace-Beltrami operator on manifolds with boundary in any
dimension is presented. The algorithm is based on the characterisation of a
large class of self-adjoint extensions of Laplace-Beltrami operators in terms
of their associated quadratic forms. The convergence of the scheme is proved. A
two-dimensional version of the algorithm is implemented effectively and several
numerical examples are computed showing that the algorithm treats in a unified
way a wide variety of boundary conditions.


title:
Precision Studies of Observables in pp->W->l nu and pp->gamma,Z->l+l-
  processes at the LHC

abstract:
  This report was prepared in the context of the LPCC "Electroweak Precision
Measurements at the LHC WG" and summarizes the activity of a subgroup dedicated
to the systematic comparison of public Monte Carlo codes, which describe the
Drell-Yan processes at hadron colliders, in particular at the CERN Large Hadron
Collider (LHC). This work represents an important step towards the definition
of an accurate simulation framework necessary for very high-precision
measurements of electroweak (EW) observables such as the $W$ boson mass and the
weak mixing angle. All the codes considered in this report share at least
next-to-leading-order (NLO) accuracy in the prediction of the total cross
sections in an expansion either in the strong or in the EW coupling constant.
The NLO fixed-order predictions have been scrutinized at the technical level,
using exactly the same inputs, setup and perturbative accuracy, in order to
quantify the level of agreement of different implementations of the same
calculation. A dedicated comparison, again at the technical level, of three
codes that reach next-to-next-to-leading-order (NNLO) accuracy in quantum
chromodynamics (QCD) for the total cross section has also been performed. These
fixed-order results are a well-defined reference that allows a classification
of the impact of higher-order sets of radiative corrections. Several examples
of higher-order effects due to the strong or the EW interaction are discussed
in this common framework. Also the combination of QCD and EW corrections is
discussed, together with the ambiguities that affect the final result, due to
the choice of a specific combination recipe.


title:
The Kardar-Parisi-Zhang equation as scaling limit of weakly asymmetric
  interacting Brownian motions

abstract:
  We consider a system of infinitely many interacting Brownian motions that
models the height of a one-dimensional interface between two bulk phases. We
prove that the large scale fluctuations of the system are well approximated by
the solution to the KPZ equation provided the microscopic interaction is weakly
asymmetric. The proof is based on the martingale solutions of Goncalves and
Jara and the corresponding uniqueness result of Gubinelli and Perkowski.


title: Visualizing the unit ball for the Teichm\"uller metric

abstract:
  We describe a method to compute the norm on the cotangent space to the moduli
space of Riemann surfaces associated to the Finsler Teichm\"uller metric. Our
method involves computing the periods of abelian double covers and is easy to
implement for Riemann surfaces presented as algebraic curves using existing
tools for approximating period matrices of plane algebraic curves. We
illustrate our method by depicting the unit sphere in the cotangent space to
moduli space at a particular surface of genus zero with five punctures and by
corroborating the proof of a theorem of Royden's for our example.


title:
Long-time stability of breathers in Hamiltonian $\cal PT$-symmetric
  lattices

abstract:
  We consider the Hamiltonian version of a $\cal PT$-symmetric lattice that
describes dynamics of coupled pendula under a resonant periodic force. Using
the asymptotic limit of a weak coupling between the pendula, we prove the
nonlinear long-time stability of breathers (time-periodic solutions localized
in the lattice) by using the Lyapunov method. Breathers are saddle points of
the extended energy function, which are located between the continuous bands of
positive and negative energy. Nevertheless, we construct an approximate
Lyapunov function and estimate its evolution on a long but finite time
interval. The nonlinear stability analysis becomes possible for the $\cal
PT$-symmetric lattice only because of the existence of a Hamiltonian structure.


title: The Search for Signatures Of Transient Mass Loss in Active Stars

abstract:
  The habitability of an exoplanet depends on many factors. One such factor is
the impact of stellar eruptive events on nearby exoplanets. Currently this is
poorly constrained due to heavy reliance on solar scaling relationships and a
lack of experimental evidence. Potential impacts of Coronal Mass Ejections
(CMEs), which are a large eruption of magnetic field and plasma from a star,
are space weather and atmospheric stripping. A method for observing CMEs as
they travel though the stellar atmosphere is the type II radio burst, and the
new LOw Frequency ARray (LOFAR) provides a means for detection. We report on 15
hours of observation of YZ Canis Minoris (YZ CMi), a nearby M dwarf flare star,
taken in LOFAR's beam-formed observation mode for the purposes of measuring
transient frequency-dependent low frequency radio emission. The observations
utilized Low-Band Antenna (10-90 MHz) or High-Band Antenna (110-190 MHz) for
five three-hour observation periods. In this data set, there were no confirmed
type II events in this frequency range. We explore the range of parameter space
for type II bursts constrained by our observations Assuming the rate of shocks
is a lower limit to the rate at which CMEs occur, no detections in a total of
15 hours of observation places a limit of $\nu_{type II} < 0.0667$ shocks/hr $
\leq \nu_{CME}$ for YZ CMi due to the stochastic nature of the events and
limits of observational sensitivity. We propose a methodology to interpret
jointly observed flares and CMEs which will provide greater constraints to CMEs
and test the applicability of solar scaling relations.


title: Full Stark Control of Polariton States on a Spin-Orbit Hypersphere

abstract:
  The orbital angular momentum and the polarisation of light are physical
quantities widely investigated for classical and quantum information
processing. In this work we propose to take advantage of strong light-matter
coupling, circular-symmetric confinement, and transverse-electric
transverse-magnetic splitting to exploit states where these two degrees of
freedom are combined. To this end we develop a model based on a spin-orbit
Poincar\'{e} hypersphere. Then we consider the example of semiconductor
polariton systems and demonstrate full ultrafast Stark control of spin-orbit
states. Moreover, by controlling states on three different spin-orbit spheres
and switching from one sphere to another we demonstrate the control of
different logic bits within one single physical system.


title: Wake excited in plasma by an ultra-relativistic point-like bunch

abstract:
  A plasma flow behind a relativistic electron bunch propagating through a cold
plasma is found assuming that the transverse and longitudinal dimensions of the
bunch are small and the bunch can be treated as a point charge. In addition,
the bunch charge is assumed small. A simplified system of equations for the
plasma electrons is derived and it is shown that, through a simple rescaling of
variables, the bunch charge can be eliminated from the equations. These
equations have a unique solution, with an ion cavity formed behind the driver.
The equations are solved numerically and the scaling of the cavity dimensions
with the driver charge is obtained. A numerical solution for the case of a
positively charged driver is also found.


title:
Random Access in C-RAN for User Activity Detection with Limited-Capacity
  Fronthaul

abstract:
  Cloud-Radio Access Network (C-RAN) is characterized by a hierarchical
structure in which the baseband processing functionalities of remote radio
heads (RRHs) are implemented by means of cloud computing at a Central Unit
(CU). A key limitation of C-RANs is given by the capacity constraints of the
fronthaul links connecting RRHs to the CU. In this letter, the impact of this
architectural constraint is investigated for the fundamental functions of
random access and active User Equipment (UE) identification in the presence of
a potentially massive number of UEs. In particular, the standard C-RAN approach
based on quantize-and-forward and centralized detection is compared to a scheme
based on an alternative CU-RRH functional split that enables local detection.
Both techniques leverage Bayesian sparse detection. Numerical results
illustrate the relative merits of the two schemes as a function of the system
parameters.


title:
The Sound of APALM Clapping: Faster Nonsmooth Nonconvex Optimization
  with Stochastic Asynchronous PALM

abstract:
  We introduce the Stochastic Asynchronous Proximal Alternating Linearized
Minimization (SAPALM) method, a block coordinate stochastic proximal-gradient
method for solving nonconvex, nonsmooth optimization problems. SAPALM is the
first asynchronous parallel optimization method that provably converges on a
large class of nonconvex, nonsmooth problems. We prove that SAPALM matches the
best known rates of convergence --- among synchronous or asynchronous methods
--- on this problem class. We provide upper bounds on the number of workers for
which we can expect to see a linear speedup, which match the best bounds known
for less complex problems, and show that in practice SAPALM achieves this
linear speedup. We demonstrate state-of-the-art performance on several matrix
factorization problems.


title: Modeling quasi-dark states with Temporal Coupled-Mode Theory

abstract:
  Coupled resonators are commonly used to achieve tailored spectral responses
and allow novel functionalities in a broad range of applications, from optical
modulation and filtering in integrated photonic circuits to the study of
nonlinear dynamics in arrays of resonators. The Temporal Coupled-Mode Theory
(TCMT) provides a simple and general tool that is widely used to model these
devices and has proved to yield very good results in many different systems of
low-loss, weakly coupled resonators. Relying on TCMT to model coupled
resonators might however be misleading in some circumstances due to the
lumped-element nature of the model. In this article, we report an important
limitation of TCMT related to the prediction of dark states. Studying a coupled
system composed of three microring resonators, we demonstrate that TCMT
predicts the existence of a dark state that is in disagreement with
experimental observations and with the more general results obtained with the
Transfer Matrix Method (TMM) and the Finite-Difference Time-Domain (FDTD)
simulations. We identify the limitation in the TCMT model to be related to the
mechanism of excitation/decay of the supermodes and we propose a correction
that effectively reconciles the model with expected results. A comparison with
TMM and FDTD allows to verify both steady-state and transient solutions of the
modified-TCMT model. The proposed correction is derived from general
considerations, energy conservation and the non-resonant power circulating in
the system, therefore it provides good insight on how the TCMT model should be
modified to eventually account for the same limitation in a different
coupled-resonator design. Moreover, our discussion based on coupled microring
resonators can be useful for other electromagnetic resonant systems due to the
generality and far-reach of the TCMT formalism.


title: Some Algorithmic Results on Restrained Domination in Graphs

abstract:
  A set $D\subseteq V$ of a graph $G=(V,E)$ is called a restrained dominating
set of $G$ if every vertex not in $D$ is adjacent to a vertex in $D$ and to a
vertex in $V \setminus D$. The \textsc{Minimum Restrained Domination} problem
is to find a restrained dominating set of minimum cardinality. Given a graph
$G$, and a positive integer $k$, the \textsc{Restrained Domination Decision}
problem is to decide whether $G$ has a restrained dominating set of cardinality
a most $k$. The \textsc{Restrained Domination Decision} problem is known to be
NP-complete for chordal graphs. In this paper, we strengthen this
NP-completeness result by showing that the \textsc{Restrained Domination
Decision} problem remains NP-complete for doubly chordal graphs, a subclass of
chordal graphs. We also propose a polynomial time algorithm to solve the
\textsc{Minimum Restrained Domination} problem in block graphs, a subclass of
doubly chordal graphs. The \textsc{Restrained Domination Decision} problem is
also known to be NP-complete for split graphs. We propose a polynomial time
algorithm to compute a minimum restrained dominating set of threshold graphs, a
subclass of split graphs. In addition, we also propose polynomial time
algorithms to solve the \textsc{Minimum Restrained Domination} problem in
cographs and chain graphs. Finally, we give a new improved upper bound on the
restrained domination number, cardinality of a minimum restrained dominating
set in terms of number of vertices and minimum degree of graph. We also give a
randomized algorithm to find a restrained dominating set whose cardinality
satisfy our upper bound with a positive probability.


title: Counting Number Fields in Fibers

abstract:
  Let X be a projective curve over Q and t a non-constant Q-rational function
on X of degree n>1. For every integer a pick a points P(a) on X such that
t(P(a))=a. Dvornicich and Zannier (1994) proved that for large N the field
Q(P(1), ..., P(N)) is of degree at least exp(cN/log N) over Q, where c>0
depends only on X and t. In this note we extend this result, replacing Q by an
arbitrary number field.


title: Optimizing Spectral Learning for Parsing

abstract:
  We describe a search algorithm for optimizing the number of latent states
when estimating latent-variable PCFGs with spectral methods. Our results show
that contrary to the common belief that the number of latent states for each
nonterminal in an L-PCFG can be decided in isolation with spectral methods,
parsing results significantly improve if the number of latent states for each
nonterminal is globally optimized, while taking into account interactions
between the different nonterminals. In addition, we contribute an empirical
analysis of spectral algorithms on eight morphologically rich languages:
Basque, French, German, Hebrew, Hungarian, Korean, Polish and Swedish. Our
results show that our estimation consistently performs better or close to
coarse-to-fine expectation-maximization techniques for these languages.


title: Geometric Analysis on the Diederich-Forn{\ae}ss Index

abstract:
  We derive a sufficient condition on a bounded pseudoconvex domain
$\Omega\subset\mathbb{C}^2$ with smooth boundary such that $-(-\rho)^\eta$ is
plurisubharmonic on $\Omega$ for $\eta>0$ arbitrarily close to $1$ (the
supremum of $\eta$ is called Diederich-Forn{\ae}ss index, see Definition (df)).
This condition (see Theorem prop) extends a theorem of Forn{\ae}ss and Herbig
in 2007 and only requires restriction on Levi-flat sets of the boundary
$\partial\Omega$. Since the condition is on Levi-flat sets, it contains more
geometric information. As an application of this new condition, we discuss how
the geometry of the Levi-flat sets affects the Diederich-Forn{\ae}ss index.
Among other results, we show that the Diederich-Forn{\ae}ss index is $1$ if
only the Levi-flat sets form a real curve transversal to the holomorphic
tangent vector fields on $\partial\Omega$ (see Theorem [main]). We also give a
specific example (see Theorem [example]) on the bounded pseudoconvex domains
which verify the application but are neither of finite type nor admit a
plurisubharmonic defining function on the boundary.


title:
Resting state brain networks from EEG: Hidden Markov states vs.
  classical microstates

abstract:
  Functional brain networks exhibit dynamics on the sub-second temporal scale
and are often assumed to embody the physiological substrate of cognitive
processes. Here we analyse the temporal and spatial dynamics of these states,
as measured by EEG, with a hidden Markov model and compare this approach to
classical EEG microstate analysis. We find dominating state lifetimes of
100--150\,ms for both approaches. The state topographies show obvious
similarities. However, they also feature distinct spatial and especially
temporal properties. These differences may carry physiological meaningful
information originating from patterns in the data that the HMM is able to
integrate while the microstate analysis is not. This hypothesis is supported by
a consistently high pairwise correlation of the temporal evolution of EEG
microstates which is not observed for the HMM states and which seems unlikely
to be a good description of the underlying physiology. However, further
investigation is required to determine the robustness and the functional and
clinical relevance of EEG HMM states in comparison to EEG microstates.


title: Almost Congruence Extension Property for subgroups of free groups

abstract:
  In this paper we provide a sufficient condition for a subgroup of a free
group not to have the almost congruence extension property (ACEP). We also show
that any finitely generated subgroup of a free group satisfies some a
generalization of ACEP.


title:
How is a data-driven approach better than random choice in label space
  division for multi-label classification?

abstract:
  We propose using five data-driven community detection approaches from social
networks to partition the label space for the task of multi-label
classification as an alternative to random partitioning into equal subsets as
performed by RAkELd: modularity-maximizing fastgreedy and leading eigenvector,
infomap, walktrap and label propagation algorithms. We construct a label
co-occurence graph (both weighted an unweighted versions) based on training
data and perform community detection to partition the label set. We include
Binary Relevance and Label Powerset classification methods for comparison. We
use gini-index based Decision Trees as the base classifier. We compare educated
approaches to label space divisions against random baselines on 12 benchmark
data sets over five evaluation measures. We show that in almost all cases seven
educated guess approaches are more likely to outperform RAkELd than otherwise
in all measures, but Hamming Loss. We show that fastgreedy and walktrap
community detection methods on weighted label co-occurence graphs are 85-92%
more likely to yield better F1 scores than random partitioning. Infomap on the
unweighted label co-occurence graphs is on average 90% of the times better than
random paritioning in terms of Subset Accuracy and 89% when it comes to Jaccard
similarity. Weighted fastgreedy is better on average than RAkELd when it comes
to Hamming Loss.


title: Industrial Strength Formal Using Abstractions

abstract:
  Verification of concurrent systems with thousands of multiple threads and
transactions is a challenging problem not just for simulation or emulation but
also for formal. To get designs to work correctly and provide optimal PPA the
designers often use complex optimizations requiring sharing of multiple
resources amongst active threads and transactions using FIFOs, stallers,
pipelining, out-of-order scheduling, and complex layered arbitration. This is
true of most non-trivial designs irrespective of a specific application domain
such as CPU, GPU or communication. At the outset a lot of these application
domains look diverse and complex; however at some level of detail all of these
employ common design principles of sequencing, load balancing, arbitration and
hazard prevention. We present in this paper a key abstraction based methodology
for verifying ordering correctness and arbitration across a range of designs
which are derived from different application domains. We show how by using
abstractions and supporting them with invariants one can not only find deep
corner case bugs in sequentially very deep designs; we can also build
exhaustive proofs to prove the absence of critical bugs such as deadlock,
starvation, and loss of data integrity. We present experimental results on a
range of different designs and show that on some of the designs such as FIFOs
we can verify over 100 different types of FIFOs for ordering correctness using
a single assertion in a single testbench. We also show how the methodology of
FIFO verification can be adapted to verify over half-a-dozen different types of
arbiters including a very complex memory subsystem arbiter. We verify a
multi-clocked synchronizer and a packet based design from a networking domain
using the same abstraction as used in FIFO verification. The results
demonstrate the strength of our methodology which is both reusable and compact.


title: No Downlink Pilots are Needed in TDD Massive MIMO

abstract:
  We consider the Massive Multiple-Input Multiple-Output (MIMO) downlink with
maximum-ratio and zero-forcing processing and time-division duplex (TDD)
operation. To decode, the terminals must know their instantaneous effective
channel gain. Conventionally, it is assumed that by virtue of channel
hardening, this instantaneous gain is close to its average and hence that
terminals can rely on knowledge of that average (also known as statistical
channel information). However, in some propagation environments, such as
keyhole channels, channel hardening does not hold.
  We propose a blind algorithm to estimate the effective channel gain at each
user, that does not require any downlink pilots. We derive a capacity lower
bound of each user for our proposed scheme, applicable to any propagation
channel. Compared to the case of no downlink pilots (relying on channel
hardening), and compared to training-based estimation using downlink pilots,
our blind algorithm performs significantly better. The difference is especially
pronounced in environments that do not offer channel hardening.


title: Locally-Optimized Inter-Subject Alignment of Functional Cortical Regions

abstract:
  Inter-subject registration of cortical areas is necessary in functional
imaging (fMRI) studies for making inferences about equivalent brain function
across a population. However, many high-level visual brain areas are defined as
peaks of functional contrasts whose cortical position is highly variable. As
such, most alignment methods fail to accurately map functional regions of
interest (ROIs) across participants. To address this problem, we propose a
locally optimized registration method that directly predicts the location of a
seed ROI on a separate target cortical sheet by maximizing the functional
correlation between their time courses, while simultaneously allowing for
non-smooth local deformations in region topology. Our method outperforms the
two most commonly used alternatives (anatomical landmark-based AFNI alignment
and cortical convexity-based FreeSurfer alignment) in overlap between predicted
region and functionally-defined LOC. Furthermore, the maps obtained using our
method are more consistent across subjects than both baseline measures.
Critically, our method represents an important step forward towards predicting
brain regions without explicit localizer scans and deciphering the poorly
understood relationship between the location of functional regions, their
anatomical extent, and the consistency of computations those regions perform
across people.


title:
Combined single crystal polarized XAFS and XRD at high pressure: probing
  the interplay between lattice distortions and electronic order at multiple
  length scales in high $T_c$ cuprates

abstract:
  Some of the most exotic material properties derive from electronic states
with short correlation length (~10-500 {\AA}), suggesting that the local
structural symmetry may play a relevant role in their behavior. Here we discuss
the combined use of polarized x-ray absorption fine structure and x-ray
diffraction at high pressure as a powerful method to tune and probe structural
and electronic orders at multiple length scales. Besides addressing some of the
technical challenges associated with such experiments, we illustrate this
approach with results obtained in the cuprate La$_{1.875}$Ba$_{0.125}$CuO$_4$,
in which the response of electronic order to pressure can only be understood by
probing the structure at the relevant length scales.


title:
The Role of Non-ionizing Radiation Pressure in Star Formation: The
  Stability of Cores and Filaments

abstract:
  Stars form when filaments and dense cores in molecular clouds fragment and
collapse due to self-gravity. In the most basic analyses of gravitational
stability, the competition between self-gravity and thermal pressure sets the
critical (i.e. maximum stable) mass of spheres and the critical line density of
cylinders. Previous work has considered additional support from magnetic fields
and turbulence. Here, we consider the effects of non-ionizing radiation,
specifically the inward radiation pressure force that acts on dense structures
embedded in an isotropic radiation field. Using hydrostatic, isothermal models,
we find that irradiation lowers the critical mass and line density for
gravitational collapse, and can thus act as a trigger for star formation. For
structures with moderate central densities, $\sim10^3$ cm$^{-3}$, the
interstellar radiation field in the Solar vicinity has an order unity effect on
stability thresholds. For more evolved objects with higher central densities, a
significant lowering of stability thresholds requires stronger irradiation, as
can be found closer to the Galactic center or near stellar associations. Even
when strong sources of ionizing radiation are absent or extincted, our study
shows that interstellar irradiation can significantly influence the star
formation process.


title: A statistical inference course based on p-values

abstract:
  Introductory statistical inference texts and courses treat the point
estimation, hypothesis testing, and interval estimation problems separately,
with primary emphasis on large-sample approximations. Here I present an
alternative approach to teaching this course, built around p-values,
emphasizing provably valid inference for all sample sizes. Details about
computation and marginalization are also provided, with several illustrative
examples, along with a course outline.