title: EIT ground-state cooling of long ion strings

abstract:
  Electromagnetically-induced-transparency (EIT) cooling is a ground-state
cooling technique for trapped particles. EIT offers a broader cooling range in
frequency space compared to more established methods. In this work, we
experimentally investigate EIT cooling in strings of trapped atomic ions. In
strings of up to 18 ions, we demonstrate simultaneous ground state cooling of
all radial modes in under 1 ms. This is a particularly important capability in
view of emerging quantum simulation experiments with large numbers of trapped
ions. Our analysis of the EIT cooling dynamics is based on a novel technique
enabling single-shot measurements of phonon numbers, by rapid adiabatic passage
on a vibrational sideband of a narrow transition.


title: Key Issues Review: Numerical studies of turbulence in stars

abstract:
  The numerical simulation of turbulence in stars has led to a rich set of
possibilities regarding stellar pulsations, asteroseismology, thermonuclear
yields, and formation of neutron stars and black holes. The breaking of
symmetry by turbulent flow grows in amplitude as collapse is approached, which
insures that the conditions at the onset of collapse are not spherical. This
lack of spherical symmetry has important implications for the mechanism of
explosion and ejected nucleosynthesis products. Numerical resolution of several
different types of three--dimensional (3D) stellar simulations are compared; it
is suggested that core collapse simulations may be under-resolved.
  New physical effects which appear in 3D are summarized.
  Connections between simulations of progenitor explosion and observations of
supernova remnants (SNR) are discussed.
  Present treatment of boundaries, for mixing regions during He--burning,
requires revision.


title: Predicate Gradual Logic and Linguistics

abstract:
  There are several major proposals for treating donkey anaphora such as
discourse representation theory and the likes, or E-Type theories and the
likes. Every one of them works well for a set of specific examples that they
use to demonstrate validity of their approaches. As I show in this paper,
however, they are not very generalisable and do not account for essentially the
same problem that they remedy when it manifests in other examples. I propose
another logical approach. I develoop logic that extends a recent, propositional
gradual logic, and show that it can treat donkey anaphora generally. I also
identify and address a problem around the modern convention on existential
import. Furthermore, I show that Aristotle's syllogisms and conversion are
realisable in this logic.


title:
Four-dimensional black holes with scalar hair in nonlinear
  electrodynamics

abstract:
  We consider a gravitating system consisting of a scalar field minimally
coupled to gravity with a self-interacting potential and a U(1) nonlinear
electromagnetic field. Solving analytically and numerically the coupled system
for both power-law and Born-Infeld type electrodynamics, we find charged hairy
black hole solutions. Then, we study the thermodynamics of these solutions and
we find that at a low temperature the topological charged black hole with
scalar hair is thermodynamically preferred, whereas the topological charged
black hole without scalar hair is thermodynamically preferred at a high
temperature for power-law electrodynamics. Interestingly enough, these phase
transitions occur at a fixed critical temperature and do not depend on the
exponent $p$ of the nonlinearity electrodynamics.


title: Supervised Matrix Factorization for Cross-Modality Hashing

abstract:
  Matrix factorization has been recently utilized for the task of multi-modal
hashing for cross-modality visual search, where basis functions are learned to
map data from different modalities to the same Hamming embedding. In this
paper, we propose a novel cross-modality hashing algorithm termed Supervised
Matrix Factorization Hashing (SMFH) which tackles the multi-modal hashing
problem with a collective non-matrix factorization across the different
modalities. In particular, SMFH employs a well-designed binary code learning
algorithm to preserve the similarities among multi-modal original features
through a graph regularization. At the same time, semantic labels, when
available, are incorporated into the learning procedure. We conjecture that all
these would facilitate to preserve the most relevant information during the
binary quantization process, and hence improve the retrieval accuracy. We
demonstrate the superior performance of SMFH on three cross-modality visual
search benchmarks, i.e., the PASCAL-Sentence, Wiki, and NUS-WIDE, with
quantitative comparison to various state-of-the-art methods


title: Shellable weakly compact subsets of $C[0,1]$

abstract:
  We show that for every weakly compact subset $K$ of $C[0,1]$ with finite
Cantor-Bendixson rank, there is a reflexive Banach lattice $E$ and an operator
$T:E\rightarrow C[0,1]$ such that $K\subseteq T(B_E)$. On the other hand, we
exhibit an example of a weakly compact set of $C[0,1]$ homeomorphic to
$\omega^\omega+1$ for which such $T$ and $E$ cannot exist. This answers a
question of M. Talagrand in the 80's.


title: Theoretical interpretation of a spin-two diphoton excess

abstract:
  A spin-two resonance would have couplings to the SM, suppressed via
higher-dimensional operators. Therefore, a sizeable cross-section would
indicate that the scale of additional new phenomena cannot be too far above the
750 GeV mark. Below I present some theoretical arguments to place the resonance
in a wider framework: a manifestation of new extra-dimensions, or a glueball of
a new strong sector. In each case, I identify some conditions the UV theory
must satisfy to accommodate other experimental bounds. Based on those, I draw
correlations with associated phenomena we expect to find in future searches.


title:
Optical parametric amplification and oscillation assisted by
  low-frequency stimulated emission

abstract:
  Optical parametric amplification/oscillation provide a powerful tool for
coherent light generation in spectral regions inaccessible to lasers.
Parametric gain is based on a frequency {\it down-conversion} process, and thus
it can not be realized for signal waves at a frequency $\omega_3$ {\it higher}
than the frequency of the pump wave $\omega_1$. In this work we suggest a route
toward the realization of {\it up-conversion} optical parametric amplification
and oscillation, i.e. amplification of the signal wave by a coherent pump wave
of lower frequency, assisted by stimulated emission of the auxiliary idler
wave. When the signal field is resonated in an optical cavity, parametric
oscillation is obtained. Design parameters for the observation of up-conversion
optical parametric oscillation at $\lambda_3=465$ nm are given for a
periodically-poled lithium-niobate (PPLN) crystal doped with Nd$^{3+}$ ions.


title:
Extracting Wyner's Common Information Using Polar Codes and Polar
  Lattices

abstract:
  Explicit constructions of polar codes and polar lattices for both lossless
and lossy Gray-Wyner problems are studied. Polar codes are employed to extract
Wyner's common information of doubly symmetric binary source; polar lattices
are then extended to extract that of a pair of Gaussian sources or multiple
Gaussian sources. With regard to the discrete sources, the entire best-known
region of the lossless Gray-Wyner problem are achieved by specifying the test
channels to construct polar codes without time-sharing. As a result, we are
able to give an interpretation that the Wyner's common information remains the
same to the lossy case when the distortion is small [1]. Finally, the entire
best-known lossy Gray-Wyner region for discrete sources can also be achieved
using polar codes. With regard to the Gaussian sources, the best-known lossy
Gray-Wyner region for bivariate Gaussian sources with a specific covariance
matrix [1] can be achieved by using polar lattices. Moreover, we prove that
extracting Wyner's common information of a pair of Gaussian sources is
equivalent to implementing the lossy compression for a single Gaussian source,
which implies that the common information can be extracted by a polar lattice
for quantization. Furthermore, we extend this result to the case of multiple
Gaussian sources.


title: Conditions for observing emergent SU(4) symmetry in a double quantum dot

abstract:
  We analyze conditions for the observation of a low energy SU(4) fixed point
in capacitively coupled quantum dots. One problem, due to dots with different
couplings to their baths, has been considered by Tosi, Roura-Bas and Aligia
(2015). They showed how symmetry can be effectively restored via the adjustment
of individual gates voltages, but they make the assumption of infinite on-dot
and inter-dot interaction strengths. A related problem is the difference in the
magnitudes between the on-dot and interdot strengths for capacitively coupled
quantum dots. Here we examine both factors, based on a two site Anderson model,
using the numerical renormalization group to calculate the local spectral
densities on the dots and the renormalized parameters that specify the low
energy fixed point. Our results support the conclusions of Tosi et al. that low
energy SU(4) symmetry can be restored, but asymptotically achieved only if the
inter-dot interaction $U_{12}$ is greater than or of the order of the band
width of the coupled conduction bath $D$, which might be difficult to achieve
experimentally. By comparing the SU(4) Kondo results for a total dot occupation
$n_{\rm tot}=1$ and $n_{\rm tot}=2$ we conclude that the temperature dependence
of the conductance is largely determined by the constraints of the Friedel sum
rule rather than the SU(4) symmetry and suggest that an initial increase of the
conductance with temperature is a distinguishing characteristic feature of an
$n_{\rm tot}=1$ universal SU(4) fixed point.


title: Parametric initial conditions for core-collapse supernova simulations

abstract:
  We investigate a method to construct parametrized progenitor models for
core-collapse supernova simulations. Different from all modern core-collapse
supernova studies, which rely on progenitor models from stellar evolution
calculations, we follow the methodology of Baron & Cooperstein (1990) to
construct initial models. Choosing parametrized spatial distributions of
entropy and electron fraction as a function of mass coordinate and solving the
equation of hydrostatic equilibrium, we obtain the initial density structures
of our progenitor models. First, we calculate structures with parameters
fitting broadly the evolutionary model s11.2 of Woosley et al. (2002). We then
demonstrate the reliability of our method by performing general relativistic
hydrodynamic simulations in spherical symmetry with the isotropic diffusion
source approximation to solve the neutrino transport. Our comprehensive
parameter study shows that initial models with a small central entropy
($\lesssim 0.4\,k_B$ nucleon$^{-1}$) can explode even in spherically symmetric
simulations. Models with a large entropy ($\gtrsim 6\,k_B$ nucleon$^{-1}$) in
the Si/O layer have a rather large explosion energy ($\sim 4\times 10^{50}$
erg) at the end of the simulations, which is still rapidly increasing.


title: Convergence of a Newton algorithm for semi-discrete optimal transport

abstract:
  Many problems in geometric optics or convex geometry can be recast as optimal
transport problems: this includes the far-field reflector problem, Alexandrov's
curvature prescription problem, etc. A popular way to solve these problems
numerically is to assume that the source probability measure is absolutely
continuous while the target measure is finitely supported. We refer to this
setting as semi-discrete optimal transport. Among the several algorithms
proposed to solve semi-discrete optimal transport problems, one currently needs
to choose between algorithms that are slow but come with a convergence speed
analysis (e.g. Oliker-Prussner) or algorithms that are much faster in practice
but which come with no convergence guarantees Algorithms of the first kind rely
on coordinate-wise increments and the number of iterations required to reach
the solution up to an error of $\epsilon$ is of order $N^3/\epsilon$, where $N$
is the number of Dirac masses in the target measure. On the other hand,
algorithms of the second kind typically rely on the formulation of the
semi-discrete optimal transport problem as an unconstrained convex optimization
problem which is solved using a Newton or quasi-Newton method.
  The purpose of this article is to bridge this gap between theory and practice
by introducing a damped Newton's algorithm which is experimentally efficient
and by proving the global convergence of this algorithm with optimal rates. The
main assumptions is that the cost function satisfies a condition that appears
in the regularity theory for optimal transport (the Ma-Trudinger-Wang
condition) and that the support of the source density is connected in a
quantitative way (it must satisfy a weighted Poincar\'e-Wirtinger inequality).


title:
NuSTAR discovery of a cyclotron line in the accreting X-ray pulsar IGR
  J16393-4643

abstract:
  The high-mass X-ray binary and accreting X-ray pulsar IGR J16393-4643 was
observed by NuSTAR in the 3-79 keV energy band for a net exposure time of 50
ks. We present the results of this observation which enabled the discovery of a
cyclotron resonant scattering feature with a centroid energy of 29.3(+1.1/-1.3)
keV. This allowed us to measure the magnetic field strength of the neutron star
for the first time: B = (2.5+/-0.1)e12 G. The known pulsation period is now
observed at 904.0+/-0.1 s. Since 2006, the neutron star has undergone a
long-term spin-up trend at a rate of P' = -2e-8 s/s (-0.6 s per year, or a
frequency derivative of nu' = 3e-14 Hz/s ). In the power density spectrum, a
break appears at the pulse frequency which separates the zero slope at low
frequency from the steeper slope at high frequency. This addition of angular
momentum to the neutron star could be due to the accretion of a quasi-spherical
wind, or it could be caused by the transient appearance of a prograde accretion
disk that is nearly in corotation with the neutron star whose magnetospheric
radius is around 2e8 cm.


title:
Norm-1 Regularized Consensus-based ADMM for Imaging with a Compressive
  Antenna

abstract:
  This paper presents a novel norm-one-regularized, consensus-based imaging
algorithm, based on the Alternating Direction Method of Multipliers (ADMM).
This algorithm is capable of imaging composite dielectric and metallic targets
by using limited amount of data. The distributed capabilities of the ADMM
accelerates the convergence of the imaging. Recently, a Compressive Reflector
Antenna (CRA) has been proposed as a way to provide high-sensing-capacity with
a minimum cost and complexity in the hardware architecture. The ADMM algorithm
applied to the imaging capabilities of the Compressive Antenna (CA) outperforms
current state of the art iterative reconstruction algorithms, such as
Nesterov-based methods, in terms of computational cost; and it ultimately
enables the use of a CA in quasi-real-time, compressive sensing imaging
applications.


title: Anomalous dimensions of scalar operators in $QED_3$

abstract:
  The infrared dynamics of $2+1$ dimensional quantum electrodynamics (QED$_3$)
with a large number $N$ of fermion flavors is governed by an interacting CFT
that can be studied in the $1/N$ expansion. We use the $1/N$ expansion to
calculate the scaling dimensions of all the lowest three scalar operators that
transform under the $SU(N)$ flavor symmetry as a Young diagram with two columns
of not necessarily equal heights and that have vanishing topological charge. In
the case of $SU(N)$ singlets, we study the mixing of $(\bar \psi_i \psi^i)(\bar
\psi_j \psi^j)$ and $F_{\mu\nu} F^{\mu\nu}$, which are the lowest dimension
parity-even singlets. Our results suggest that these operators are irrelevant
for all $N>1$.


title: Analyzing In-Game Movements of Soccer Players at Scale

abstract:
  It is challenging to get access to datasets related to the physical
performance of soccer players. The teams consider such information highly
confidential, especially if it covers in-game performance.Hence, most of the
analysis and evaluation of the players' performance do not contain much
information on the physical aspect of the game, creating a blindspot in
performance analysis. We propose a novel method to solve this issue by deriving
movement characteristics of soccer players. We use event-based datasets from
data provider companies covering 50+ soccer leagues allowing us to analyze the
movement profiles of potentially tens of thousands of players without any major
investment. Our methodology does not require expensive, dedicated player
tracking system deployed in the stadium. We also compute the similarity of the
players based on their movement characteristics and as such identify potential
candidates who may be able to replace a given player. Finally, we quantify the
uniqueness and consistency of players in terms of their in-game movements. Our
study is the first of its kind that focuses on the movements of soccer players
at scale, while it derives novel, actionable insights for the soccer industry
from event-based datasets.


title: On the Multiplexing Gain of Discrete-Time MIMO Phase Noise Channels

abstract:
  The capacity of a point-to-point discrete-time multi-input-multiple-output
(MIMO) channel with phase uncertainty (MIMO phase noise channel) is still open.
As a matter of fact, even the pre-log (multiplexing gain) of the capacity in
the high signal-to-noise ratio (SNR) regime is unknown in general. We make some
progresses in this direction for two classes of such channels. With phase noise
on the individual paths of the channel (model A), we show that the multiplexing
gain is 1/2, which implies that the capacity does not scale with the channel
dimension at high SNR. With phase noise at both the input and output of the
channel (model B), the multiplexing gain is upper-bounded by 1/2
min{nt,(nr-2)^+ + 1}, and lower-bounded by 1/2 min{nt, floor((nr+1)/2)}, where
nt and nr are the number of transmit and receive antennas, respectively. The
multiplexing gain is enhanced to 1/2 min{nt,nr} without receive phase noise,
and to 1/2 min{2nt-1,nr} without transmit phase noise. In all the cases of
model B, the multiplexing gain scales linearly with min{nt,nr}. Our main
results rely on the derivation of non-trivial upper and lower bounds on the
capacity of such channels.


title: Superconducting Quantum Interference Single-Electron Transistor

abstract:
  We propose the concept of a quantized single-electron source based on the
interplay between Coulomb blockade and magnetic flux-controllable
superconducting proximity effect. We show that flux dependence of the induced
energy gap in the density of states of a nanosized metallic wire can be
exploited as an efficient tunable energy barrier which enables charge pumping
configurations with enhanced functionalities. This control parameter strongly
affects the charging landscape of a normal metal island with non-negligible
Coulombic energy. Under a suitable evolution of a time-dependent magnetic flux
the structure behaves likewise a turnstile for single electrons in a fully
electrostatic regime.


title:
On the cohomology ring of narrow Lagrangian 3-manifolds, quantum
  Reidemeister torsion, and the Landau-Ginzburg superpotential

abstract:
  Let $L$ be a closed, orientable, monotone Lagrangian 3-manifold of a
symplectic manifold $(M, \omega)$, for which there exists a local system such
that the corresponding Lagrangian quantum homology vanishes. We show that its
cohomology ring satisfies a certain dichotomy, which depends only on the parity
of the first Betti number of $L$. Essentially, the triple cup product on the
first cohomology group is shown to be either of maximal rank or identically
zero. This in turn influences the Landau-Ginzburg superpotential of $L$: either
one of its partial derivatives do not vanish on the corresponding local system,
or it is globally constant. We use this to prove that quantum Reidemeister
torsion is invariant and can be expressed in terms of open Gromov-Witten
invariants of $L$.


title: Reliable Prediction Intervals for Local Linear Regression

abstract:
  This paper introduces two methods for estimating reliable prediction
intervals for local linear least-squares regressions, named Bounded Oscillation
Prediction Intervals (BOPI). It also proposes a new measure for comparing
interval prediction models named Equivalent Gaussian Standard Deviation (EGSD).
The experimental results compare BOPI to other methods using coverage
probability, Mean Interval Size and the introduced EGSD measure. The results
were generally in favor of the BOPI on considered benchmark regression
datasets. It also, reports simulation studies validating the BOPI method's
reliability.


title:
Single and double production of the Higgs boson at hadron and lepton
  colliders in minimal composite Higgs models

abstract:
  In the composite Higgs models, originally proposed by Georgi and Kaplan, the
Higgs boson is a pseudo Nambu-Goldstone boson (pNGB) of spontaneous breaking of
a global symmetry. In the minimal version of such models, global SO(5) symmetry
is spontaneously broken to SO(4), and the pNGBs form an isospin doublet field,
which corresponds to the Higgs doublet in the Standard Model (SM). Predicted
coupling constants of the Higgs boson can in general deviate from the SM
predictions, depending on the compositeness parameter. The deviation pattern is
determined also by the detail of the matter sector. We comprehensively study
how the model can be tested via measuring single and double production
processes of the Higgs boson at LHC and future electron-positron colliders. The
possibility to distinguish the matter sector among the minimal composite Higgs
models is also discussed. In addition, we point out differences in the cross
section of double Higgs boson production from the prediction in other new
physics models.


title: Plasmon effects in photoemission

abstract:
  We develop the concept of scattering matrix and we use it to perform stable
numerical calculations of photo-emission from nano-tips. Electrons move in an
external space and time dependent nonperturbative electric field. We apply our
algorithm for different strengths and spatial configurations of the field.


title:
Charge Fractionalization in Oxide Heterostructures: A Field Theoretical
  Model

abstract:
  LaAlO$_{3}$/SrTiO$_{3}$ heterostructure with polar and non-polar constituents
has been shown to exhibit interface metallic conductivity due to fractional
charge transfer to the interface. The interface reconstruction by electron
redistribution along (001) orientation, in which half of an electron is
transferred per two dimensional unit cell to the adjacent planes, resulting in
a net transfer of half of the charge, to both the interface and top most atomic
planes, has been ascribed to a polar discontinuity at the interface in the
Polar Catastrophe model. This avoids the divergence of electrostatic potential,
as the number of layers are increased, producing an oscillatory electric field
and finite potential. Akin to the description of charge fractionalization in
quasi one-dimensional polyacetylene by the field theoretic Jackiw-Rebbi model
with fermions interacting with topologically non-trivial background field, we
show an analogous connection between polar catastrophe model and Bell-Rajaraman
model, where the charge fractionalization occurs in the soliton free sector as
an end effect.


title:
Graphoepitaxy for translational and orientational ordering of monolayers
  of rectangular nanoparticles

abstract:
  The combinations of particle aspect ratio and enthalpic-barrier templates
that lead to translational and orientational ordering of monolayers of
rectangular particles are determined using Monte Carlo simulations and density
functional theory. For sufficiently high enthalpic barriers, we find that only
specific combinations of particle sizes and template spacings lead to ordered
arrays. The pattern multiplication factor provided by the template extends to
approximately ten times the smallest dimension of the particle.


title:
The 750 GeV Diphoton excess, Dark Matter and Constraints from the
  IceCube experiment

abstract:
  Recent LHC data show hints of a new resonance in the diphoton distribution at
an invariant mass of 750 GeV. Interestingly, this new particle might be both CP
odd and play the role of a portal into the dark matter sector. Under these
assumptions and motivated by the fact that the requirement of $SU(2)_L$
invariance automatically implies the coupling of this alleged new resonance to
$ZZ$ and $Z\gamma$, we investigate the current and future constraints coming
from the indirect searches performed through the neutrino telescope IceCube. We
show that these constraints can be stronger than the ones from direct detection
experiments if the dark matter mass is larger than a few hundred GeV.
Furthermore, in the scenario in which the dark matter is a scalar particle, the
IceCube data limit the cross section between the DM and the proton to values
close to the predicted ones for natural values of the parameters.


title:
An introduction to affine Grassmannians and the geometric Satake
  equivalence

abstract:
  We introduce various affine Grassmannians, study their geometric properties,
and give some applications. We also discuss the geometric Satake equivalence.
These are the expanded lecture notes for a mini-course in 2015 PCMI summer
school. References updated and more details added.


title:
Mapping Temporal Variables into the NeuCube for Improved Pattern
  Recognition, Predictive Modelling and Understanding of Stream Data

abstract:
  This paper proposes a new method for an optimized mapping of temporal
variables, describing a temporal stream data, into the recently proposed
NeuCube spiking neural network architecture. This optimized mapping extends the
use of the NeuCube, which was initially designed for spatiotemporal brain data,
to work on arbitrary stream data and to achieve a better accuracy of temporal
pattern recognition, a better and earlier event prediction and a better
understanding of complex temporal stream data through visualization of the
NeuCube connectivity. The effect of the new mapping is demonstrated on three
bench mark problems. The first one is early prediction of patient sleep stage
event from temporal physiological data. The second one is pattern recognition
of dynamic temporal patterns of traffic in the Bay Area of California and the
last one is the Challenge 2012 contest data set. In all cases the use of the
proposed mapping leads to an improved accuracy of pattern recognition and event
prediction and a better understanding of the data when compared to traditional
machine learning techniques or spiking neural network reservoirs with arbitrary
mapping of the variables.


title: Short Wavelength Oscillations with Right-Handed Neutrinos

abstract:
  The standard model is extended with three right-handed, singlet neutrinos
with general couplings permitted by the $SU(2)_{L}\times U(1)$ symmetry. The
traditional oscillations are accounted for, as usually, by three left-handed
neutrinos. The article investigates new structures that develop when the masses
of the right-handed states are in the eV range. The new states interfere and
oscillate with the standard light neutrinos. New structures appear when the
detectors average over short wavelengths. I use these results to present and
classify properties of the observed anomalies in the MiniBooNe, reactor and
Gallium-detector experiments.


title:
Enhancement on Laser Intensity and Proton Acceleration Using Micro-tube
  Plasma Lens Targets

abstract:
  A hollow cylindrical micron-scale structure is proposed to enhance and
manipulate the laser plasma interaction. It is shown through 3-D
particle-in-cell simulations that the incident laser pulse intensity is
enhanced within the tube. A detailed study of the intensification optimizes the
tube dimensions and provides a characterization of the in-tube intensity. By
coupling the micro-tube plasma lens to a traditional flat interface, we show an
increase in on-target intensity. We detail proton energy enhancement as a
potential application of the micro-tube plasma lens target, where the tube
structure acts to focus the light and provide additional electrons that enhance
the accelerating sheath field.


title: A Nonlocal Poisson-Fermi Model for Ionic Solvent

abstract:
  We propose a nonlocal Poisson-Fermi model for ionic solvent that includes ion
size effects and polarization correlations among water molecules in the
calculation of electrostatic potential. It includes the previous Poisson-Fermi
models as special cases, and its solution is the convolution of a solution of
the corresponding nonlocal Poisson dielectric model with a Yukawa-type kernel
function. Moreover, the Fermi distribution is shown to be a set of optimal
ionic concentration functions in the sense of minimizing an electrostatic
potential free energy. Finally, numerical results are reported to show the
difference between a Poisson-Fermi solution and a corresponding Poisson
solution.


title:
Muon reconstruction performance of the ATLAS detector in proton--proton
  collision data at $\sqrt{s}$=13 TeV

abstract:
  This article documents the performance of the ATLAS muon identification and
reconstruction using the first LHC dataset recorded at $\sqrt{s}$ = 13 TeV in
2015. Using a large sample of $J/\psi\to\mu\mu$ and $Z\to\mu\mu$ decays from
3.2 fb$^{-1}$ of $pp$ collision data, measurements of the reconstruction
efficiency, as well as of the momentum scale and resolution, are presented and
compared to Monte Carlo simulations. The reconstruction efficiency is measured
to be close to $99\%$ over most of the covered phase space ($|\eta|<2.5$ and $5
< p_{T} < 100$ GeV). The isolation efficiency varies between $93\%$ and $100\%$
depending on the selection applied and on the momentum of the muon. Both
efficiencies are well reproduced in simulation. In the central region of the
detector, the momentum resolution is measured to be $1.7\%$ ($2.3\%$) for muons
from $J/\psi\to\mu\mu$ ($Z\to\mu\mu$) decays, and the momentum scale is known
with an uncertainty of $0.05\%$. In the region $|\eta |>2.2$, the $p_{T} $
resolution for muons from $Z\to\mu\mu$ decays is $2.9\%$ while the precision of
the momentum scale for low-$p_{T} $ muons from $J/\psi\to\mu\mu$ decays is
about $0.2\%$.


title: A Soft Electronics-Free robot

abstract:
  Biomimetic entirely soft robots with animal-like behavior and integrated
artificial nervous systems will open up totally new perspectives and
applications. However, until now all presented studies on soft robots were
limited to partly soft designs, since all designs at least needed conventional,
stiff, electronics, to sense, process signals and activate actuators. We
present the first soft robot with integrated artificial nervous system entirely
made of dielectric elastomers - and without any conventional stiff electronic
parts. Supplied with only one external DC voltage, the robot autonomously
generates all signals necessary to drive its actuators, and translates an
in-plane electromechanical oscillation into a crawling locomotion movement.
Thereby, all functional parts are made of polymer materials and carbon. Besides
the basic design of the world's first entirely soft robot we present prospects
to control general behavior of such robots.


title: "What happens if..." Learning to Predict the Effect of Forces in Images

abstract:
  What happens if one pushes a cup sitting on a table toward the edge of the
table? How about pushing a desk against a wall? In this paper, we study the
problem of understanding the movements of objects as a result of applying
external forces to them. For a given force vector applied to a specific
location in an image, our goal is to predict long-term sequential movements
caused by that force. Doing so entails reasoning about scene geometry, objects,
their attributes, and the physical rules that govern the movements of objects.
We design a deep neural network model that learns long-term sequential
dependencies of object movements while taking into account the geometry and
appearance of the scene by combining Convolutional and Recurrent Neural
Networks. Training our model requires a large-scale dataset of object movements
caused by external forces. To build a dataset of forces in scenes, we
reconstructed all images in SUN RGB-D dataset in a physics simulator to
estimate the physical movements of objects caused by external forces applied to
them. Our Forces in Scenes (ForScene) dataset contains 10,335 images in which a
variety of external forces are applied to different types of objects resulting
in more than 65,000 object movements represented in 3D. Our experimental
evaluations show that the challenging task of predicting long-term movements of
objects as their reaction to external forces is possible from a single image.


title: Re-opening dark matter windows compatible with a diphoton excess

abstract:
  We investigate a simple setup in which an excess in the di-photon invariant
mass distribution around $750$ GeV, as seen by the ATLAS and CMS
collaborations, is originated through a pair of collimated photon pairs. In
this framework a scalar state $s$ decays into two light pseudo-Goldstone bosons
$a$, each of which subsequently decays into a pair of collimated photons which
are misidentified as a single photon. In a minimal context of spontaneous
symmetry breaking, we show that coupling a complex scalar field
$\Phi=(s+ia)/\sqrt{2}$ to a fermionic dark matter candidate $\chi$, also
responsible for generating its mass, allows for the correct relic density in a
large region of the parameter space, while not being excluded by the direct or
indirect detection experiments. Moreover, the correct relic abundance can
naturally co-exist with a relatively large width for the resonant field $s$.


title: Exploring the simplest purely baryonic decay processes

abstract:
  Though not considered in general, purely baryonic decays could shed light on
the puzzle of the baryon number asymmetry in the universe by means of a better
understanding of the baryonic nature of our matter world. As such, they
constitute a yet unexplored class of decay processes worth investigating. We
propose to search for purely baryonic decay processes at the LHCb experiment.
No such type of decay has ever been observed. In particular, we concentrate on
the decay $\Lambda_b^0\to p\bar pn$, which is the simplest purely baryonic
decay mode, with solely spin-1/2 baryons involved. We predict its decay
branching ratio to be ${\cal B}(\Lambda_b^0\to p\bar
pn)=(2.0^{+0.3}_{-0.2})\times 10^{-6}$, which is sufficiently large to make the
decay mode accessible to LHCb. Our study can be extended to other purely
baryonic decays such as $\Lambda_b^0\to p\bar p \Lambda$ and $\Lambda_b^0\to
\Lambda\bar \Lambda\Lambda$, as well as to similar decays of anti-triplet
$b$-baryons such as $\Xi_b^{0,-}$.


title: Ultrafast Local Magnetization and Demagnetization in Heusler Alloys

abstract:
  With the goal of pushing Spintronic devices towards faster and faster
timescales, we demonstrate, using ab-intio time-dependent density functional
theory simulations of bulk Heusler compounds subject to ultrashort intense
laser pulses, that the local magnetic moment can increase or decrease in a few
femtoseconds. This speed is due to the all optical nature of the process, which
transfers spin moment from one sublattice to another. This transfer depends on
easily tunable laser parameters. By comparing the spin dynamics of a variety of
Heusler (or half-Heusler) compounds, we demonstrate that the density of states
explains the observed moment transfer; most the physics of inter sublattice
moment transfer is due to the flow of spin current which is governed by
availability of states above the Fermi level.


title: Regularity for parabolic systems of Uhlenbeck type with Orlicz growth

abstract:
  We study the local regularity of $p$-caloric functions or more generally of
$\phi$-caloric functions. In particular, we study local solutions of non-linear
parabolic systems with homogeneous right hand side, where the leading terms has
Uhlenbeck structure of Orlicz type. This paper closes the gap of [22] where
Liebermann proved that if the gradient of a solution is bounded, it is H\"older
continuous.
  The crucial step is a novel local estimates for the gradient of the
solutions, which generalize and improve the pioneering estimates of DiBenedetto
and Friedman [12,10] for the $p$-Laplace heat equation.


title: Multiscale modeling of diffusion in a crowded environment

abstract:
  We present a multiscale approach to model diffusion in a crowded environment
and its effect on the reaction rates. Diffusion in biological systems is often
modeled by a discrete space jump process in order to capture the inherent noise
of biological systems, which becomes important in the low copy number regime.
To model diffusion in the crowded cell environment efficiently, we compute the
jump rates in this mesoscopic model from local first exit times, which account
for the microscopic positions of the crowding molecules, while the diffusing
molecules jump on a coarser Cartesian grid. We then extract a macroscopic
description from the resulting jump rates, where the excluded volume effect is
modeled by a diffusion equation with space dependent diffusion coefficient. The
crowding molecules can be of arbitrary shape and size and numerical experiments
demonstrate that those factors together with the size of the diffusing molecule
play a crucial role on the magnitude of the decrease in diffusive motion. When
correcting the reaction rates for the altered diffusion we can show that
molecular crowding either enhances or inhibits chemical reactions depending on
local fluctuations of the obstacle density.


title:
The Structure Constants of the Exceptional Lie Algebra ${\mathfrak g}_2$
  in the Cartan-Weyl Basis

abstract:
  The purpose of this paper is to answer the question whether it is possible to
realize simultaneously the relations $N_{\alpha,\beta}=-N_{-\alpha,-\beta}$,
$N_{\alpha,\beta}=N_{\beta,-\alpha-\beta}=N_{-\alpha-\beta,\alpha}$ and
$N_{\alpha,\beta}N_{-\alpha,-\beta}=-\frac{1}{2}q(p+1)\langle\alpha,H_{\alpha}\rangle$
by the structure constants of the Lie algebra ${\mathfrak g}_2$. We show that
if the structure constants obey the first relation, the three last ones are
violated, and vice versa. Contrary to the second case, the first one uses the
Cartan matrix elements to derive the structure constants in the form of
$\langle\beta,H_{\alpha}\rangle$. The commutation relations corresponding to
the first case are exactly documented in the prior literature. However, as
expected, a Lie algebra isomorphism is established between the Cartan-Weyl
bases obtained in both approaches.


title:
Quantum phase transition and destruction of Kondo effect in pressurized
  SmB6

abstract:
  SmB6 is a promising candidate material that promises to elucidate the
connection between strong correlations and topological electronic states, which
is a major challenge in condensed matter physics. The electron correlations are
responsible for the development of multiple gaps in SmB6, whose elucidation is
sorely needed. Here we do so by studying the evolutions of the gaps and other
corresponding behaviors under pressure. Our measurements of the valence, Hall
effect and electrical resistivity clearly identify the gap which is associated
with the bulk Kondo hybridization and, moreover, uncover a pressure-induced
quantum phase transition from the putative topological Kondo insulating state
to a Fermi-liquid state at ~4 GPa. We provide the evidences for the transition
by a jump of inverse Hall coefficient, a diverging tendency of the
electron-electron scattering coefficient and, thereby, a destruction of the
Kondo entanglement in the ground state. These effects take place in a
mixed-valence background. Our results raise the new prospect for studying
topological electronic states in quantum critical materials settings.


title: On spt-crank type functions

abstract:
  In a recent paper, Andrews, Dixit, and Yee introduced a new spt-type function
$\operatorname{spt}_\omega(n)$, which is closely related to Ramanujan's third
order mock theta function $\omega(q)$. Garvan and Jennings-Shaffer introduce a
crank function which explains congruences for $\operatorname{spt}_\omega(n)$.
In this note, we study asymptotic behavior of this crank function and confirm a
positivity conjecture of the crank asymptotically. We also study a sign pattern
of the crank and congruences for $\operatorname{spt}_\omega(n)$.


title: ABCDepth: efficient algorithm for Tukey depth

abstract:
  We present a new algorithm for Tukey (halfspace) depth level sets and its
implementation. Given $d$-dimensional data set for any $d\geq 2$, the algorithm
is based on representation of level sets as intersections of balls in $R^d$,
and can be easily adapted to related depths (Type D, Zuo and Serfling (Ann.
Stat. {\bf 28} (2000), 461--482)). The algorithm complexity is $O(dn^2 +
n^2\log{n})$ where $n$ is the data set size. Examples with real and synthetic
data show that the algorithm is much faster than other implemented algorithms
and that it can accept thousands of multidimensional observations, while other
algorithms are tested with two-dimensional data or with a couple of hundreds
multidimensional observations.


title:
Multiple radial positive solutions of semilinear elliptic problems with
  Neumann boundary conditions

abstract:
  Assuming $B_{R}$ is a ball in $\mathbb R^{N}$, we analyze the positive
solutions of the problem \[
  \begin{cases}
  -\Delta u+u= |u|^{p-2}u, &\text{ in } B_{R},\newline
  \partial_{\nu}u=0,&\text{ on } \partial B_{R},
  \end{cases}
  \] that branch out from the constant solution $u=1$ as $p$ grows from $2$ to
$+\infty$. The non-zero constant positive solution is the unique positive
solution for $p$ close to $2$. We show that there exist arbitrarily many
positive solutions as $p\to\infty$ (in particular, for supercritical exponents)
or as $R \to \infty$ for any fixed value of $p>2$, answering partially a
conjecture in [Bonheure-Noris-Weth]. We give the explicit lower bounds for $p$
and $R$ so that a given number of solutions exist. The geometrical properties
of those solutions are studied and illustrated numerically. Our simulations
motivate additional conjectures. The structure of the least energy solutions
(among all or only among radial solutions) and other related problems are also
discussed.


title:
Diffusion in a system of a few distinguishable fermions in a
  one-dimensional double-well potential

abstract:
  Dynamical properties of a few ultra-cold fermions confined in a double-well
potential is studied. We show that the dynamics, which is governed by
single-particle tunnelings for vanishing interactions, is completely different
for strong interactions. Depending on the details of the configuration, for
sufficiently strong interactions (repulsions or attractions) the particle flow
through the barrier can be accelerated or slowed down. This effect cannot be
explained with the single-particle picture. It is clarified with direct
inspection to the spectrum of the few-body Hamiltonian.


title:
Fisher Hartwig determinants, conformal field theory and universality in
  generalised XX models

abstract:
  We discuss certain quadratic models of spinless fermions on a 1D lattice, and
their corresponding spin chains. These were studied by Keating and Mezzadri in
the context of their relation to the Haar measures of the classical compact
groups. We show how these models correspond to translation invariant models on
an infinite or semi-infinite chain, which in the simplest case reduce to the
familiar XX model. We give physical context to mathematical results for the
entanglement entropy, and calculate the spin-spin correlation functions using
the Fisher-Hartwig conjecture. These calculations rigorously demonstrate
universality in classes of these models. We show that these are in agreement
with field theoretic and renormalization group arguments that we provide.


title: Some explicit elliptic modular surfaces

abstract:
  We consider algebraic surfaces, recently constructed by Schreieder, that are
smooth models of the quotient of the self-product of a complex hyperelliptic
curve by a $(\mathbb{Z}/3^c\mathbb{Z})$-action. We show that these surfaces are
elliptic modular surfaces in the sense of Shioda, meaning in particular that
they are universal families of explicit moduli of elliptic curves.


title:
Streaming Algorithms for News and Scientific Literature Recommendation:
  Submodular Maximization with a d-Knapsack Constraint

abstract:
  Submodular maximization problems belong to the family of combinatorial
optimization problems and enjoy wide applications. In this paper, we focus on
the problem of maximizing a monotone submodular function subject to a
$d$-knapsack constraint, for which we propose a streaming algorithm that
achieves a $\left(\frac{1}{1+2d}-\epsilon\right)$-approximation of the optimal
value, while it only needs one single pass through the dataset without storing
all the data in the memory. In our experiments, we extensively evaluate the
effectiveness of our proposed algorithm via two applications: news
recommendation and scientific literature recommendation. It is observed that
the proposed streaming algorithm achieves both execution speedup and memory
saving by several orders of magnitude, compared with existing approaches.


title: A software approach to defeating side channels in last-level caches

abstract:
  We present a software approach to mitigate access-driven side-channel attacks
that leverage last-level caches (LLCs) shared across cores to leak information
between security domains (e.g., tenants in a cloud). Our approach dynamically
manages physical memory pages shared between security domains to disable
sharing of LLC lines, thus preventing "Flush-Reload" side channels via LLCs. It
also manages cacheability of memory pages to thwart cross-tenant "Prime-Probe"
attacks in LLCs. We have implemented our approach as a memory management
subsystem called CacheBar within the Linux kernel to intervene on such side
channels across container boundaries, as containers are a common method for
enforcing tenant isolation in Platform-as-a-Service (PaaS) clouds. Through
formal verification, principled analysis, and empirical evaluation, we show
that CacheBar achieves strong security with small performance overheads for
PaaS workloads.


title:
Gravitational wave source counts at high redshift and in models with
  extra dimensions

abstract:
  Gravitational wave (GW) source counts have been recently shown to be able to
test how gravitational radiation propagates with the distance from the source.
Here, we extend this formalism to cosmological scales, i.e. the high redshift
regime, and we discuss the complications of applying this methodology to high
redshift sources. We also allow for models with compactified extra dimensions
like in the Kaluza-Klein model. Furthermore, we also consider the case of
intermediate redshifts, i.e. $0<z\lesssim1$, where we show it is possible to
find an analytical approximation for the source counts $\frac{dN}{d(S/N)}$.
This can be done in terms of cosmological parameters, such as the matter
density $\Omega_{m,0}$ of the cosmological constant model or the cosmographic
parameters for a general dark energy model. Our analysis is as general as
possible, but it depends on two important factors: a source model for the black
hole binary mergers and the GW source to galaxy bias. This methodology also
allows us to obtain the higher order corrections of the source counts in terms
of the signal-to-noise $S/N$. We then forecast the sensitivity of future
observations in constraining GW physics but also the underlying cosmology by
simulating sources distributed over a finite range of signal-to-noise with a
number of sources ranging from 10 to 500 sources as expected from future
detectors. We find that with 500 events it will be possible to provide
constraints on the matter density parameter at present $\Omega_{m,0}$ on the
order of a few percent and with the precision growing fast with the number of
events. In the case of extra dimensions we find that depending on the
degeneracies of the model, with 500 events it may be possible to provide
stringent limits on the existence of the extra dimensions if the aforementioned
degeneracies can be broken.


title:
Giant molecular filaments in the Milky Way II: The fourth Galactic
  quadrant

abstract:
  Filamentary structures are common morphological features of the cold,
molecular interstellar medium (ISM). Recent studies have discovered massive,
hundred-parsec-scale filaments that may be connected to the large-scale,
Galactic spiral arm structure. Addressing the nature of these Giant Molecular
Filaments (GMFs) requires a census of their occurrence and properties. We
perform a systematic search of GMFs in the fourth Galactic quadrant and
determine their basic physical properties. We identify GMFs based on their dust
extinction signatures in near- and mid-infrared and velocity structure probed
by ^{13}CO line emission. We use the ^{13}CO line emission and ATLASGAL dust
emission data to estimate the total and dense gas masses of the GMFs. We
combine our sample with an earlier sample from literature and study the
Galactic environment of the GMFs. We identify nine GMFs in the fourth Galactic
quadrant; six are located in the Centaurus spiral arm and three in inter-arm
regions. Combining this sample with an earlier study using the same
identification criteria in the first Galactic quadrant results in 16 GMFs, nine
of which are located within spiral arms. The GMFs have sizes of 80-160 pc and
^{13}CO-derived masses between 5-90 x 10^{4} Msun. Their dense gas mass
fractions are between 1.5-37%, being higher in the GMFs connected to spiral
arms. We also compare the different GMF-identification methods and find that
emission and extinction based techniques overlap only partially, highlighting
the need to use both to achieve a complete census.


title:
Genus dependence of the number of (non-)orientable surface
  triangulations

abstract:
  Topological triangulations of orientable and non-orientable surfaces with
arbitrary genus have important applications in quantum geometry, graph theory
and statistical physics. However, until now only the asymptotics for 2-spheres
are known analytically, and exact counts of triangulations are only available
for both small genus and small triangulations. We apply the Wang-Landau
algorithm to calculate the number $N(m,h)$ of triangulations for several order
of magnitudes in system size $m$ and genus $h$. We verify that the limit of the
entropy density of triangulations is independent of genus and orientability and
are able to determine the next-to-leading and the next-to-next-to-leading order
terms. We conjecture for the number of surface triangulations the asymptotic
behavior \begin{equation*} N(m,h) \rightarrow (170.4 \pm 15.1)^h m^{-2(h -
1)/5} \left( \frac{256}{27} \right)^{m / 2}\;, \end{equation*} what might guide
a mathematicians proof for the exact asymptotics.


title:
Exact dynamics of two ultra-cold bosons confined in a one-dimensional
  double-well potential

abstract:
  The dynamics of two ultra-cold bosons confined in a one-dimensional
double-well potential is studied. We compare the exact dynamics governed by a
full two-body Hamiltonian with the dynamics obtained in a two-mode model
approximation. We show that for sufficiently large interactions the two-mode
model breaks down and higher single-particle states have to be taken into
account to describe the dynamical properties of the system correctly.


title: A Moment Majorization principle for random matrix ensembles

abstract:
  We prove a moment majorization principle for matrix-valued functions with
domain $\{-1,1\}^{m}$, $m\in\mathbb{N}$. The principle is an inequality between
higher-order moments of a non-commutative multilinear polynomial with different
random matrix ensemble inputs, where each variable has small influence and the
variables are instantiated independently.
  This technical result can be interpreted as a noncommutative generalization
of one of the two inequalities of the seminal invariance principle of Mossel,
O'Donnell and Oleszkiewicz. Applications to noncommutative noise stability and
noncommutative anticoncentration are given.


title:
Operator Norm Inequalities between Tensor Unfoldings on the Partition
  Lattice

abstract:
  Interest in higher-order tensors has recently surged in data-intensive
fields, with a wide range of applications including image processing, blind
source separation, community detection, and feature extraction. A common
paradigm in tensor-related algorithms advocates unfolding (or flattening) the
tensor into a matrix and applying classical methods developed for matrices.
Despite the popularity of such techniques, how the functional properties of a
tensor changes upon unfolding is currently not well understood. In contrast to
the body of existing work which has focused almost exclusively on
matricizations, we here consider all possible unfoldings of an order-$k$
tensor, which are in one-to-one correspondence with the set of partitions of
$\{1,\ldots,k\}$. We derive general inequalities between the $l^p$-norms of
arbitrary unfoldings defined on the partition lattice. In particular, we
demonstrate how the spectral norm ($p=2$) of a tensor is bounded by that of its
unfoldings, and obtain an improved upper bound on the ratio of the Frobenius
norm to the spectral norm of an arbitrary tensor. For specially-structured
tensors satisfying a generalized definition of orthogonal decomposability, we
prove that the spectral norm remains invariant under specific subsets of
unfolding operations.


title:
Early Science with the Large Millimeter Telescope: Observations of
  Extremely Luminous High-z Sources Identified by Planck

abstract:
  We present 8.5 arcsec resolution 1.1mm continuum imaging and CO spectroscopic
redshift measurements of eight extremely bright submillimetre galaxies
identified from the Planck and Herschel surveys, taken with the Large
Millimeter Telescope's AzTEC and Redshift Search Receiver instruments. We
compiled a candidate list of high redshift galaxies by cross-correlating the
Planck Surveyor mission's highest frequency channel (857 GHz, FWHM = 4.5
arcmin) with the archival Herschel Spectral and Photometric Imaging Receiver
(SPIRE) imaging data, and requiring the presence of a unique, single Herschel
counterpart within the 150 arcsec search radius of the Planck source positions
with 350 micron flux density larger than 100 mJy, excluding known blazars and
foreground galaxies. All eight candidate objects observed are detected in 1.1mm
continuum by AzTEC bolometer camera, and at least one CO line is detected in
all cases with a spectroscopic redshift between 1.3 < z(CO) < 3.3. Their
infrared spectral energy distributions mapped using the Herschel and AzTEC
photometry are consistent with cold dust emission with characteristic
temperature between $T_d$ = 43 K and 84 K. With apparent infrared luminosity of
up to L(IR) = $3\times10^{14} \mu^{-1} L_\odot$, they are some of the most
luminous galaxies ever found (with yet unknown gravitational magnification
factor $\mu$). The analysis of their spectral energy distributions (SEDs)
suggests that star formation is powering the bulk of their extremely large IR
luminosities. Derived molecular gas masses of $M_{H2}=(0.6-7.8)\times 10^{11}
M_\odot$ (for $\mu$~10) also make them some of the most gas-rich high redshift
galaxies ever detected.


title: Steering Macro-Scale Network Community Structure by Micro-Scale Features

abstract:
  Network science plays an increasingly important role to model complex data in
many scientific disciplines. One notable feature of network organization is
community structure, which refers to clusters of tightly interconnected nodes.
A prominent problem is how to investigate the relationship between macro-scale
modules that are retrieved by optimizing global network measures, and
micro-scale structure that are defined by specific queries of the analysis
(e.g., nodal features). By generalizing fundamental concepts of joint
space-frequency localization to network theory, here we propose a flexible
framework to study interactions between micro- and macro-structure. Similar to
pointing and focusing a magnifying glass, the analysis can be directed to
specific micro-scale structure, while the degree of interaction with the
macro-scale community structure can be seamlessly controlled. In addition, the
method is computationally efficient as a result of the underlying
low-dimensional optimization problem.


title: Pseudo-Hermitian Transition in Degenerate Nonlinear Four-Wave Mixing

abstract:
  We show that degenerate four-wave mixing (FWM) in nonlinear optics can be
described by an effective Hamiltonian that is pseudo-Hermitian, which enables a
transition between a pseudo-Hermitian phase with real eigenvalues and a broken
pseudo-Hermitian phase with complex conjugate eigenvalues. While bearing
certain similarity to that in Parity-Time symmetric systems, this transition is
in stark contrast because of the absence of gain and loss in the effective
Hamiltonian. The latter is real after factoring out the system decay, and the
onset of non-Hermiticity in degenerate FWM is due to the total phase change of
the signal wave and the idler wave. This property underlines the intrinsic
coherence in FWM, which opens the door to probe quantum implications of
exceptional points.


title: Two-variable Logic with a Between Predicate

abstract:
  We study an extension of FO^2[<], first-order logic interpreted in finite
words, in which formulas are restricted to use only two variables. We adjoin to
this language two-variable atomic formulas that say, `the letter a appears
between positions x and y'. This is, in a sense, the simplest property that is
not expressible using only two variables.
  We present several logics, both first-order and temporal, that have the same
expressive power, and find matching lower and upper bounds for the complexity
of satisfiability for each of these formulations. We also give an effective
necessary condition, in terms of the syntactic monoid of a regular language,
for a property to be expressible in this logic. We show that this condition is
also sufficient for words over a two-letter alphabet. This algebraic analysis
allows us us to prove, among other things, that our new logic has strictly less
expressive power than full first-order logic FO[<].


title: Quiver Generalization of a Conjecture of King, Tollu, and Toumazet

abstract:
  Stretching the parameters of a Littlewood-Richardson coefficient of value 2
by a factor of n results in a coefficient of value n+1. We give a geometric
proof of a generalization for representations of quivers.


title: Hypergraph Partitioning for Sparse Matrix-Matrix Multiplication

abstract:
  We propose a fine-grained hypergraph model for sparse matrix-matrix
multiplication (SpGEMM), a key computational kernel in scientific computing and
data analysis whose performance is often communication bound. This model
correctly describes both the interprocessor communication volume along a
critical path in a parallel computation and also the volume of data moving
through the memory hierarchy in a sequential computation. We show that
identifying a communication-optimal algorithm for particular input matrices is
equivalent to solving a hypergraph partitioning problem. Our approach is
sparsity dependent, meaning that we seek the best algorithm for the given input
matrices.
  In addition to our (3D) fine-grained model, we also propose coarse-grained 1D
and 2D models that correspond to simpler SpGEMM algorithms. We explore the
relations between our models theoretically, and we study their performance
experimentally in the context of three applications that use SpGEMM as a key
computation. For each application, we find that at least one coarse-grained
model is as communication efficient as the fine-grained model. We also observe
that different applications have affinities for different algorithms.
  Our results demonstrate that hypergraphs are an accurate model for reasoning
about the communication costs of SpGEMM as well as a practical tool for
exploring the SpGEMM algorithm design space.


title:
Multi-Hop Cluster based IEEE 802.11p and LTE Hybrid Architecture for
  VANET Safety Message Dissemination

abstract:
  This paper proposes a hybrid architecture, namely VMaSC-LTE, combining IEEE
802.11p based multi-hop clustering and the fourth generation cellular system,
Long Term Evolution (LTE), with the goal of achieving high data packet delivery
ratio and low delay while keeping the usage of the cellular architecture at the
minimum level. In VMaSC-LTE, vehicles are clustered based on a novel approach
named VMaSC: Vehicular Multi-hop algorithm for Stable Clustering. From the
clustered topology, elected cluster heads operate as dual-interface nodes with
the functionality of IEEE 802.11p and LTE interface to link VANET to LTE
network. Using various key metrics of interest including data packet delivery
ratio, delay, control overhead and clustering stability, we demonstrate
superior performance of the proposed architecture compared to both previously
proposed hybrid architectures and alternative routing mechanisms including
flooding and cluster based routing via extensive simulations in ns-3 with the
vehicle mobility input from the Simulation of Urban Mobility (SUMO). The
proposed architecture also allows achieving higher required reliability of the
application quantified by the data packet delivery ratio at the cost of higher
LTE usage determined by the number of cluster heads in the network.


title: Discriminative Embeddings of Latent Variable Models for Structured Data

abstract:
  Kernel classifiers and regressors designed for structured data, such as
sequences, trees and graphs, have significantly advanced a number of
interdisciplinary areas such as computational biology and drug design.
Typically, kernels are designed beforehand for a data type which either exploit
statistics of the structures or make use of probabilistic generative models,
and then a discriminative classifier is learned based on the kernels via convex
optimization. However, such an elegant two-stage approach also limited kernel
methods from scaling up to millions of data points, and exploiting
discriminative information to learn feature representations.
  We propose, structure2vec, an effective and scalable approach for structured
data representation based on the idea of embedding latent variable models into
feature spaces, and learning such feature spaces using discriminative
information. Interestingly, structure2vec extracts features by performing a
sequence of function mappings in a way similar to graphical model inference
procedures, such as mean field and belief propagation. In applications
involving millions of data points, we showed that structure2vec runs 2 times
faster, produces models which are $10,000$ times smaller, while at the same
time achieving the state-of-the-art predictive performance.


title: Interpreting Numerical Measurements in Fixed Topological Sectors

abstract:
  For quantum field theories with topological sectors, Monte Carlo simulations
on fine lattices tend to be obstructed by an extremely long auto-correlation
time with respect to the topological charge. Then reliable numerical
measurements are feasible only within individual sectors. The challenge is to
assemble such restricted measurements in a way that leads to a substantiated
approximation to the fully fledged result, which would correspond to the
correct sampling over the entire set of configurations. We test an approach for
such a topological summation, which was suggested by Brower, Chandrasekharan,
Negele and Wiese. Under suitable conditions, energy levels and susceptibilities
can be obtained to a good accuracy, as we demonstrate for O(N) models, SU(2)
Yang-Mills theory, and for the Schwinger model.


title: Generative Image Modeling using Style and Structure Adversarial Networks

abstract:
  Current generative frameworks use end-to-end learning and generate images by
sampling from uniform noise distribution. However, these approaches ignore the
most basic principle of image formation: images are product of: (a) Structure:
the underlying 3D model; (b) Style: the texture mapped onto structure. In this
paper, we factorize the image generation process and propose Style and
Structure Generative Adversarial Network (S^2-GAN). Our S^2-GAN has two
components: the Structure-GAN generates a surface normal map; the Style-GAN
takes the surface normal map as input and generates the 2D image. Apart from a
real vs. generated loss function, we use an additional loss with computed
surface normals from generated images. The two GANs are first trained
independently, and then merged together via joint learning. We show our S^2-GAN
model is interpretable, generates more realistic images and can be used to
learn unsupervised RGBD representations.


title:
A quasilinear bistable equation in cylinders and timelike heteroclinics
  in special relativity

abstract:
  In this note we consider the action functional \[ \int_{\mathbb{R} \times
\omega} \left( 1 - \sqrt{ 1 - |\nabla u|^2 } + W(u) \right) \, \mathrm{d}t, \]
where $W$ is a double well potential and $\omega$ is a bounded domain of
$\mathbb{R}^{N-1}$. We prove existence, one-dimensionality and uniqueness (up
to translation) of a smooth minimizing phase transition between the two stable
states $u=1$ and $u=-1$. The question of existence of at least one minimal
heteroclinic connection for the non autonomous model \[ \int_{\mathbb{R}}
\left( 1 - \sqrt{1-|u'|^2} + a(t) W(u) \right) \, \mathrm{d}t \] is also
addressed. For this, we look for the possible assumptions on $a(t)$ ensuring
the existence of a minimizer.


title:
Interface Condition for the Darcy Velocity at the Water-oil Flood Front
  in the Porous Medium

abstract:
  Flood front is the jump interface where fluids distribute discontinuously,
whose interface condition is the theoretical basis of a mathematical model of
the multiphase flow in porous medium. The conventional interface condition at
the jump interface is expressed as the continuous Darcy velocity and fluid
pressure (named CVCM ). Our study has inspected this conclusions. First, it is
revealed that the principle of mass conservation has no direct relation to the
velocity conservation, and the former is not the true foundation of the later,
because the former only reflects the kinetic characteristic of the fluid
particles at one position(the interface), but not the neighborhood of the
interface which required by the later. Then the reasonableness of CVCM is
queried from the following three aspects:(1)Using Mukat's two phase seepage
equation and the mathematical method of apagoge, we have disproved the
continuity of each fluid velocity;(2)Since the analytical solution of the
equation of Buckley-Leveret equations is acquirable, its velocity jumps at the
flood front presents an appropriate example to disprove the CVCM;(3) The
numerical simulation model gives impractical result that flood front would stop
moving if CVCM were used to calculate the velocities at the interface between
two gridcells. Subsequently, a new one, termed as Jump Velocity Condition Model
(JVCM), is deduced from Muskat's two phase seepage equations and Darcy's law
without taking account of the capillary force and compressibility of rocks and
fluids. Finally, several cases are presented. And the comparisons of the
velocity, pressure difference and the front position, which are given by JVCM,
CVCM and SPU, have shown that the result of JVCM is the closest to the exact
solution.


title:
A framework for the direct evaluation of large deviations in
  non-Markovian processes

abstract:
  We propose a general framework to simulate stochastic trajectories with
arbitrarily long memory dependence and efficiently evaluate large deviation
functions associated to time-extensive observables. This extends the "cloning"
procedure of Giardin\'a et al. [Phys. Rev. Lett. 96, 120603 (2006)] to
non-Markovian systems. We demonstrate the validity of this method by testing
non-Markovian variants of an ion-channel model and the Totally Asymmetric
Exclusion Process, recovering results obtainable by other means.


title:
Single-particle spectral function of the $\Lambda$ hyperon in finite
  nuclei

abstract:
  The spectral function of the $\Lambda$ hyperon in finite nuclei is calculated
from the corresponding $\Lambda$ self-energy, which is constructed within a
perturbative many-body approach using some of the hyperon-nucleon interactions
of the J\"{u}lich and Nijmegen groups. Binding energies, wave functions and
disoccupation numbers of different single-particle states are obtained for
various hypernuclei from $^5_{\Lambda}$He to $^{209}_{\,\,\,\,\,\Lambda}$Pb.
The agreement between the calculated binding energies and experimental data is
qualitatively good. The small spin-orbit splitting of the $p-, d-, f-$ and
$g-$wave states is confirmed. The discrete and the continuum contributions of
the single-$\Lambda$ spectral function are computed. Their appearance is
qualitatively similar to that of the nucleons. The $Z$-factor, that measures
the importance of correlations, is also calculated. Our results show that its
value is relatively large, indicating that the $\Lambda$ hyperon is less
correlated than nucleons. This is in agreement with the results obtained by
other authors for the correlations of the $\Lambda$ in infinite nuclear matter.
The disoccupation numbers are obtained by integrating the spectral function
over the energy. Our results show that the discrete contribution to the
disoccupation number decreases when increasing the momentum of the $\Lambda$.
This indicates that, in the production reactions of hypernuclei, the $\Lambda$
hyperon is mostly formed in a quasi-free state.


title:
An Implementation and Analysis of a Kernel Network Stack in Go with the
  CSP Style

abstract:
  Modern operating system kernels are written in lower-level languages such as
C. Although the low-level functionalities of C are often useful within kernels,
they also give rise to several classes of bugs. Kernels written in higher level
languages avoid many of these potential problems, at the possible cost of
decreased performance. This research evaluates the advantages and disadvantages
of a kernel written in a higher level language. To do this, the network stack
subsystem of the kernel was implemented in Go with the Communicating Sequential
Processes (CSP) style. Go is a high-level programming language that supports
the CSP style, which recommends splitting large tasks into several smaller ones
running in independent "threads". Modules for the major networking protocols,
including Ethernet, ARP, IPv4, ICMP, UDP, and TCP, were implemented. In this
study, the implemented Go network stack, called GoNet, was compared to a
representative network stack written in C. The GoNet code is more readable and
generally performs better than that of its C stack counterparts. From this, it
can be concluded that Go with CSP style is a viable alternative to C for the
language of kernel implementations.


title:
The Interface Conditions for Pressures at Oil-water Flood Front in the
  Porous Media Considering Capillary Pressure

abstract:
  Flood front is the jump interface where fluids distribute discontinuously,
whose interface condition is the theoretical basis of a mathematical model of
the multiphase flow in porous medium. The conventional interface condition at
the jump interface is expressed as the continuous Darcy velocity and fluid
pressure (named CPVCM). This paper has inspected it via the studying the
water-oil displacement in one dimensional reservoir with considering capillary
pressure but ignoring the compressibility and gravity. It is proved
theoretically that the total Darcy velocity and total pressure (defined by
Antoncev etc.), instead of the Darcy velocities and pressures of water and oil,
are continuous at the flood front without considering the compressibility of
fluid and porous media. After that, new interface conditions for the pressures
and Darcy velocity of each fluid are established, which are collectively named
as Jump Pressures and Velocities Conditions Model (JPVCM) because the model has
shown the jump pressures and jump Darcy velocities at the flood front. Finally,
three application-examples are proposed and the results show JPVCM is more
reasonable than CPVCM. Keywords: Flood front; Jump Condition; Two phase;
numerical flux; mathematical model


title: WASP-157b, a Transiting Hot Jupiter Observed with K2

abstract:
  We announce the discovery of the transiting hot Jupiter WASP-157b in a 3.95-d
orbit around a V = 12.9 G2 main-sequence star. This moderately inflated planet
has a Saturn-like density with a mass of $0.57 \pm 0.10$ M$_{\rm Jup}$ and a
radius of $1.06 \pm 0.05$ R$_{\rm Jup}$. We do not detect any rotational or
phase-curve modulations, nor the secondary eclipse, with conservative
semi-amplitude upper limits of 250 and 20 ppm, respectively.


title: Sensitivity of mixing times in Eulerian digraphs

abstract:
  Let $X$ be a lazy random walk on a graph $G$. If $G$ is undirected, then the
mixing time is upper bounded by the maximum hitting time of the graph. This
fails for directed chains, as the biased random walk on the cycle
$\mathbb{Z}_n$ shows. However, we establish that for Eulerian digraphs, the
mixing time is $O(mn)$, where $m$ is the number of edges and $n$ is the number
of vertices. In the reversible case, the mixing time is robust to the change of
the laziness parameter. Surprisingly, in the directed setting the mixing time
can be sensitive to such changes. We also study exploration and cover times for
random walks on Eulerian digraphs and prove universal upper bounds in analogy
to the undirected case.


title:
Dephasing measurements in InGaAs/AlInAs heterostructures: manifestations
  of spin-orbit and Zeeman interactions

abstract:
  We have measured weak antilocalization effects, universal conductance
fluctuations, and Aharonov-Bohm oscillations in the two-dimensional electron
gas formed in InGaAs/AlInAs heterostructures. This system possesses strong
spin-orbit coupling and a high Land\'{e} factor. Phase-coherence lengths of
2$-$4 $\mu$m at 1.5$-$4.2 K are extracted from the magnetoconductance
measurements. The analysis of the coherence-sensitive data reveals that the
temperature dependence of the decoherence rate complies with the dephasing
mechanism originating from electron-electron interactions in all three
experiments. Distinct beating patterns superimposed on the Aharonov-Bohm
oscillations are observed over a wide range of magnetic fields, up to 0.7 Tesla
at the relatively high temperature of 1.5 K. The possibility that these beats
are due to the interplay between the Aharonov-Bohm phase and the Berry one,
different for electrons of opposite spins in the presence of strong spin-orbit
and Zeeman interactions in ring geometries, is carefully investigated. It
appears that our data are not explained by this mechanism; rather, a few
geometrically-different electronic paths within the ring's width can account
for the oscillations' modulations.


title:
A non-variational system involving the critical Sobolev exponent. The
  radial case

abstract:
  In this paper we consider the non-variational system $$
  \begin{cases}
  -\Delta u_i = \sum\limits_{j=1}^k a_{ij} u_j^{(N+2)/(N-2)}
  &\text{in }\mathbb R^N,\newline
  u_i>0 &\text{in }\mathbb R^N,\newline
  u_i\in D^{1,2}(\mathbb R^N).
  \end{cases} $$ and we give some sufficient conditions on the matrix
$(a_{ij})_{i,j=1,\dotsc ,k}$ which ensure the existence of solutions
bifurcating from the bubble of the critical Sobolev equation.


title: Optimal Black-Box Reductions Between Optimization Objectives

abstract:
  The diverse world of machine learning applications has given rise to a
plethora of algorithms and optimization methods, finely tuned to the specific
regression or classification task at hand. We reduce the complexity of
algorithm design for machine learning by reductions: we develop reductions that
take a method developed for one setting and apply it to the entire spectrum of
smoothness and strong-convexity in applications.
  Furthermore, unlike existing results, our new reductions are OPTIMAL and more
PRACTICAL. We show how these new reductions give rise to new and faster running
times on training linear classifiers for various families of loss functions,
and conclude with experiments showing their successes also in practice.


title: Variance Reduction for Faster Non-Convex Optimization

abstract:
  We consider the fundamental problem in non-convex optimization of efficiently
reaching a stationary point. In contrast to the convex case, in the long
history of this basic problem, the only known theoretical results on
first-order non-convex optimization remain to be full gradient descent that
converges in $O(1/\varepsilon)$ iterations for smooth objectives, and
stochastic gradient descent that converges in $O(1/\varepsilon^2)$ iterations
for objectives that are sum of smooth functions.
  We provide the first improvement in this line of research. Our result is
based on the variance reduction trick recently introduced to convex
optimization, as well as a brand new analysis of variance reduction that is
suitable for non-convex optimization. For objectives that are sum of smooth
functions, our first-order minibatch stochastic method converges with an
$O(1/\varepsilon)$ rate, and is faster than full gradient descent by
$\Omega(n^{1/3})$.
  We demonstrate the effectiveness of our methods on empirical risk
minimizations with non-convex loss functions and training neural nets.


title: Constraints on Planetesimal Collision Models in Debris Disks

abstract:
  Observations of debris disks offer a window into the physical and dynamical
properties of planetesimals in extrasolar systems through the size distribution
of dust grains. In particular, the millimeter spectral index of thermal dust
emission encodes information on the grain size distribution. We have made new
VLA observations of a sample of seven nearby debris disks at 9 mm, with 3"
resolution and $\sim5$ $\mu$Jy/beam rms. We combine these with archival ATCA
observations of eight additional debris disks observed at 7 mm, together with
up-to-date observations of all disks at (sub)millimeter wavelengths from the
literature to place tight constraints on the millimeter spectral indices and
thus grain size distributions. The analysis gives a weighted mean for the slope
of the power law grain size distribution, $n(a)\propto a^{-q}$, of $\langle q
\rangle = 3.36\pm0.02$, with a possible trend of decreasing $q$ for later
spectral type stars. We compare our results to a range of theoretical models of
collisional cascades, from the standard self-similar, steady-state size
distribution ($q=3.5$) to solutions that incorporate more realistic physics
such as alternative velocity distributions and material strengths, the
possibility of a cutoff at small dust sizes from radiation pressure, as well as
results from detailed dynamical calculations of specific disks. Such effects
can lead to size distributions consistent with the data, and plausibly the
observed scatter in spectral indices. For the AU Mic system, the VLA
observations show clear evidence of a highly variable stellar emission
component; this stellar activity obviates the need to invoke the presence of an
asteroid belt to explain the previously reported compact millimeter source in
this system.


title: Regularity of fixed-point vertex operator subalgebras

abstract:
  We show that if $T$ is a simple non-negatively graded regular vertex operator
algebra with a nonsingular invariant bilinear form and $\sigma$ is a finite
order automorphism of $T$, then the fixed-point vertex operator subalgebra
$T^\sigma$ is also regular. This yields regularity for fixed point vertex
operator subalgebras under the action of any finite solvable group. As an
application, we obtain an $SL_2(\mathbb{Z})$-compatibility between twisted
twining characters for commuting finite order automorphisms of holomorphic
vertex operator algebras. This resolves one of the principal claims in the
Generalized Moonshine conjecture.


title: Filling-Enforced Gaplessness in Band Structures of the 230 Space Groups

abstract:
  Nonsymmorphic symmetries like screws and glides produce electron band
touchings, obstructing the formation of a band insulator and leading, instead,
to metals or nodal semimetals even when the number of electrons in the unit
cell is an even integer. Here, we calculate the electron fillings compatible
with being a band insulator for all 230 space groups, for noninteracting
electrons with time-reversal symmetry. Our bounds are tight - that is, we can
rigorously eliminate band insulators at any forbidden filling and produce
explicit models for all allowed fillings - and stronger than those recently
established for interacting systems. These results provide simple criteria that
should help guide the search for topological semimetals and, also, have
implications for both the nature and stability of the resulting nodal Fermi
surfaces.


title:
Virtually Semisimple Modules and a Generalization of the
  Wedderburn-Artin Theorem

abstract:
  By any measure, semisimple modules form one of the most important classes of
modules and play a distinguished role in the module theory and its
applications. One of the most fundamental results in this area is the
Wedderburn-Artin theorem. In this paper, we establish natural generalizations
of semisimple modules and give a generalization of the Wedderburn-Artin
theorem. We study modules in which every submodule is isomorphic to a direct
summand and name them {\it virtually semisimple modules}. A module $_RM$ is
called {\it completely virtually semisimple} if each submodules of $M$ is a
virtually semisimple module. A ring $R$ is then called {\it left} ({\it
completely}) {\it virtually semisimple} if $_RR$ is a left (compleatly)
virtually semisimple $R$-module. Among other things, we give several
characterizations of left (completely) virtually semisimple rings. For
instance, it is shown that a ring $R$ is left completely virtually semisimple
if and only if $R \cong \prod _{i=1}^ k M_{n_i}(D_i)$ where $k, n_1, ...,n_k\in
\Bbb{N}$ and each $D_i$ is a principal left ideal domain. Moreover, the
integers $k,~ n_1, ...,n_k$ and the principal left ideal domains $D_1, ...,D_k$
are uniquely determined (up to isomorphism) by $R$.


title: Simulations of a multi-layer extended gating grid

abstract:
  A novel idea to control ion back-flow in time projection chambers is to use a
multi-layer extended gating grid to capture back-flowing ions at the expense of
live time and electron transparency. In this initial study, I perform
simulations of a four-layer grid for the ALICE and STAR time projection
chambers, using $\text{Ne}-\text{CO}_{2}\;(90-10)$ and
$\text{Ar}-\text{CH}_{4}\;(90-10)$ gas mixtures, respectively. I report the
live time and electron transparency for both 90% and 99% ion back-flow
suppression. Additionally, for the ALICE configuration I study several effects:
using a mesh vs. wire-plane grid, including a magnetic field, and varying the
over-voltage distribution in the gating region. For 90% ion back-flow
suppression, I achieve 75% live time with 86% electron transparency for ALICE,
and 95% live time with 83% electron transparency for STAR.


title: Detection chamber for search of low Mass WIMP and solar axions

abstract:
  A chamber for direct detection of WIMPs with masses < 10 GeV/c2 and solar
axions is developed. The chamber is filled with a gas mixture of H2 +3ppm TMAE
(1,5,10 bar), or D2 + 3ppm TMAE. These gas fillings make it possible to
suppress an electron background. For detection of events, the system
GEM+pin-anode with a multiplication coefficient of about 10E+05 is constructed.


title:
A feasibility study to track cosmic muons using a detector with SiPM
  devices based on amplitude discrimination

abstract:
  The possibility to build a SiPM-readout muon detector (SiRO), using plastic
scintillators with optical fibers as sensitive volume and readout by SiPM
photo-diodes, is investigated. SiRO shall be used for tracking cosmic muons
based on amplitude discrimination. The detector concept foresees a stack of 6
active layers, grouped in 3 sandwiches for determining the muon trajectories
through 3 planes. After investigating the characteristics of the photodiodes,
tests have been performed using two detection modules, each being composed from
a plastic scintillator sheet, $100 \times 25 \times 1\,$cm$^{3}$, with 12
parallel, equidistant ditches; each ditch filled with an optical fiber of
$1.5\,$mm thickness and always two fibers connected to form a channel. The
attenuation of the light response along the optical fiber and across the
channels have been tested. The measurements of the incident muons based on the
input amplitude discrimination indicate that this procedure is not efficient
and therefore not sufficient, as only about 30\% of the measured events could
be used in the reconstruction of the muon trajectories. Based on the studies
presented in this paper, the layout used for building the SiRO detector will be
changed as well as the analog acquisition technique will be replaced by a
digital one.


title: Linear Accelerator Test Facility at LNF Conceptual Design Report

abstract:
  Test beam and irradiation facilities are the key enabling infrastructures for
research in high energy physics (HEP) and astro-particles. In the last 11 years
the Beam-Test Facility (BTF) of the DA{\Phi}NE accelerator complex in the
Frascati laboratory has gained an important role in the European
infrastructures devoted to the development and testing of particle detectors.
At the same time the BTF operation has been largely shadowed, in terms of
resources, by the running of the DA{\Phi}NE electron-positron collider. The
present proposal is aimed at improving the present performance of the facility
from two different points of view: extending the range of application for the
LINAC beam extracted to the BTF lines, in particular in the (in some sense
opposite) directions of hosting fundamental physics and providing electron
irradiation also for industrial users; extending the life of the LINAC beyond
or independently from its use as injector of the DA{\Phi}NE collider, as it is
also a key element of the electron/positron beam facility. The main lines of
these two developments can be identified as: consolidation of the LINAC
infrastructure, in order to guarantee a stable operation in the longer term;
upgrade of the LINAC energy, in order to increase the facility capability
(especially for the almost unique extracted positron beam); doubling of the BTF
beam-lines, in order to cope with the signicant increase of users due to the
much wider range of applications.


title:
Transition from the $\mathbb{Z}_2$ spin liquid to antiferromagnetic
  order: spectrum on the torus

abstract:
  We describe the finite-size spectrum in the vicinity of the quantum critical
point between a $\mathbb{Z}_2$ spin liquid and a coplanar antiferromagnet on
the torus. We obtain the universal evolution of all low-lying states in an
antiferromagnet with global SU(2) spin rotation symmetry, as it moves from the
4-fold topological degeneracy in a gapped $\mathbb{Z}_2$ spin liquid to the
Anderson "tower-of-states" in the ordered antiferromagnet. Due to the existence
of nontrivial order on either side of this transition, this critical point
cannot be described in a conventional Landau-Ginzburg-Wilson framework. Instead
it is described by a theory involving fractionalized degrees of freedom known
as the O$(4)^\ast$ model, whose spectrum is altered in a significant way by its
proximity to a topologically ordered phase. We compute the spectrum by relating
it to the spectrum of the O$(4)$ Wilson-Fisher fixed point on the torus,
modified with a selection rule on the states, and with nontrivial boundary
conditions corresponding to topological sectors in the spin liquid. The
spectrum of the critical O($2N$) model is calculated directly at $N=\infty$,
which then allows a reconstruction of the full spectrum of the O($2N)^\ast$
model at leading order in 1/N. This spectrum is a unique characteristic of the
vicinity of a fractionalized quantum critical point, as well as a universal
signature of the existence of proximate $\mathbb{Z}_2$ topological and
antiferromagnetically-ordered phases, and can be compared with numerical
computations on quantum antiferromagnets on two dimensional lattices.


title: The origin of the $\alpha$-enhancement of massive galaxies

abstract:
  We study the origin of the stellar $\alpha$-element-to-iron abundance ratio,
$[\alpha/\mathrm{Fe}]_{\ast}$, of present-day central galaxies, using
cosmological, hydrodynamical simulations from the Evolution and Assembly of
GaLaxies and their Environments (EAGLE) project. For galaxies with stellar
masses of $M_{\ast} > 10^{10.5}$ M$_{\odot}$, $[\alpha/\mathrm{Fe}]_{\ast}$
increases with increasing galaxy stellar mass and age. These trends are in good
agreement with observations of early-type galaxies, and are consistent with a
`downsizing' galaxy formation scenario: more massive galaxies have formed the
bulk of their stars earlier and more rapidly, hence from an interstellar medium
that was mostly $\alpha$-enriched by massive stars. In the absence of feedback
from active galactic nuclei (AGN), however, $[\alpha/\mathrm{Fe}]_{\ast}$ in
$M_{\ast} > 10^{10.5}$ M$_{\odot}$ galaxies is roughly constant with stellar
mass and decreases with mean stellar age, extending the trends found for
lower-mass galaxies in both simulations with and without AGN. We conclude that
AGN feedback can account for the $\alpha$-enhancement of massive galaxies, as
it suppresses their star formation, quenching more massive galaxies at earlier
times, thereby preventing the iron from longer-lived intermediate-mass stars
(supernova Type Ia) from being incorporated into younger stars.


title: Chemical abundances in a high velocity RR Lyrae star near the bulge

abstract:
  Low-mass, variable, high-velocity stars are interesting study cases for many
aspects of Galactic structure and evolution. Until recently, the only known
high- or hyper-velocity stars were young stars thought to originate from the
Galactic centre. Wide-area surveys like APOGEE and BRAVA have found several
low-mass stars in the bulge with Galactic rest-frame velocities larger than 350
km/s. In this study we present the first abundance analysis of a low-mass, RR
Lyrae star, located close to the Galactic bulge, with a space motion of ~ -400
km/s. Using medium-resolution spectra, we derive abundances (including upper
limits) of 11 elements. These allow us to chemically tag the star and discuss
its origin, although our derived abundances and metallicity, at [Fe/H] =-0.9
dex, do not point toward one unambiguous answer. Based on the chemical tagging,
we cannot exclude that it originated in the bulge. However, combining its
retrograde orbit and the derived abundances suggests that the star was
accelerated from the outskirts of the inner (or even outer) halo during
many-body interactions. Other possible origins include the bulge itself, or the
star could be stripped from a star cluster or the Sagittarius dwarf galaxy when
it merged with the Milky Way.


title: Gravitational Waves from the Remnants of the First Stars

abstract:
  Gravitational waves (GWs) provide a revolutionary tool to investigate yet
unobserved astrophysical objects. Especially the first stars, which are
believed to be more massive than present-day stars, might be indirectly
observable via the merger of their compact remnants. We develop a
self-consistent, cosmologically representative, semi-analytical model to
simulate the formation of the first stars. By extrapolating binary
stellar-evolution models at 10% solar metallicity to metal-free stars, we track
the individual systems until the coalescence of the compact remnants. We
estimate the contribution of primordial stars to the merger rate density and to
the detection rate of the Advanced Laser Interferometer Gravitational-Wave
Observatory (aLIGO). Owing to their higher masses, the remnants of primordial
stars produce strong GW signals, even if their contribution in number is
relatively small. We find a probability of $\gtrsim1\%$ that the current
detection GW150914 is of primordial origin. We estimate that aLIGO will detect
roughly 1 primordial BH-BH merger per year for the final design sensitivity,
although this rate depends sensitively on the primordial initial mass function
(IMF). Turning this around, the detection of black hole mergers with a total
binary mass of $\sim 300\,\mathrm{M}_\odot$ would enable us to constrain the
primordial IMF.


title: Emergent particle-hole symmetry in the half-filled Landau level

abstract:
  We provide an effective description of a particle-hole symmetric state of
electrons in a half-filled Landau level, starting from the traditional approach
pioneered by Halperin, Lee and Read. Specifically, we study a system consisting
of alternating quasi-one-dimensional strips of composite Fermi liquid (CFL) and
composite hole liquid (CHL), both of which break particle-hole symmetry. When
the CFL and CHL strips are identical in size, the resulting state is manifestly
invariant under the combined action of a particle-hole transformation with
respect to a single Landau level (which interchanges the CFL and CHL) and
translation by one unit, equal to the strip width, in the direction transverse
to the strips. At distances long compared to the strip width, we demonstrate
that the system is described by a Dirac fermion coupled to an emergent gauge
field, with an anti-unitary particle-hole symmetry, as recently proposed by
Son.


title:
Shock Breakout and Early Light Curves of Type II-P Supernovae Observed
  with Kepler

abstract:
  We discovered two transient events in the Kepler field with light curves that
strongly suggest they are type II-P supernovae. Using the fast cadence of the
Kepler observations we precisely estimate the rise time to maximum for KSN2011a
and KSN2011d as 10.5$\pm 0.4$ and 13.3$\pm 0.4$ rest-frame days respectively.
Based on fits to idealized analytic models, we find the progenitor radius of
KSN2011a (280$\pm 20$ R$_\odot$) to be significantly smaller than that for
KSN2011d (490$\pm 20$ R$_\odot$) but both have similar explosion energies of
2.0$\pm 0.3\times 10^{51}$ erg.
  The rising light curve of KSN2011d is an excellent match to that predicted by
simple models of exploding red supergiants (RSG). However, the early rise of
KSN2011a is faster than the models predict possibly due to the supernova
shockwave moving into pre-existing wind or mass-loss from the RSG. A mass loss
rate of $10^{-4}$ M$_\odot$ yr$^{-1}$ from the RSG can explain the fast rise
without impacting the optical flux at maximum light or the shape of the
post-maximum light curve.
  No shock breakout emission is seen in KSN2011a, but this is likely due to the
circumstellar interaction suspected in the fast rising light curve. The early
light curve of KSN2011d does show excess emission consistent with model
predictions of a shock breakout. This is the first optical detection of a shock
breakout from a type II-P supernova.


title:
Inner Engine Shutdown from Transitions in the Angular Momentum
  Distribution in Collapsars

abstract:
  For the collapsar scenario to be effective in the production of Gamma Ray
Bursts, the infalling star's angular momentum $J(r)$ must be larger than the
critical angular momentum needed to form an accretion disk around a blackhole
(BH), namely $J_{\rm crit} = 2r_{g}c$ for a Schwarzschild BH. By means of 3D
SPH simulations, here we study the collapse and accretion onto black holes of
spherical rotating envelopes, whose angular momentum distribution has
transitions between supercritical ($J>J_{\rm crit}$) and subcritical ($J<J_{\rm
crit}$) values. Contrary to results obtained in previous 2D hydrodynamical
simulations, we find that a substantial amount of subcritical material fed to
the accretion disk, lingers around long enough to contribute significantly to
the energy loss rate. Increasing the amount of angular momentum in the
subcritical material increases the time spent at the accretion disk, and only
when the bulk of this subcritical material is accreted before it is replenished
by a massive outermost supercritical shell, the inner engine experiences a
shutdown. Once the muffled accretion disk is provided again with enough
supercritical material, the shutdown will be over and a quiescent time in the
long GRB produced afterwards could be observed.


title: Unveiling causal activity of complex networks

abstract:
  We introduce a novel tool for analyzing complex network dynamics, allowing
for cascades of causally-related events, which we call causal webs (c-webs), to
be separated from other non-causally-related events. This tool shows that
traditionally-conceived avalanches may contain mixtures of spatially-distinct
but temporally-overlapping cascades of events, and dynamical disorder or noise.
In contrast, c-webs separate these components, unveiling previously hidden
features of the network and dynamics. We apply our method to mouse cortical
data with resulting statistics which demonstrate for the first time that
neuronal avalanches are not merely composed of causally-related events.

categories: q-bio.NC nlin.AO physics.bio-ph physics.data-an